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  • Chapter 2 Living Laboratories: Double Designs and Multiple Methods
    22 février 2017
    Publication date: 2018
    Source:Twin Mythconceptions

    Author(s): Nancy L. Segal

    This chapter explains and describes the different ways in which twins are used in psychological and medical research. These different approaches include the classic twin method, cotwin control, twin-family designs, children-of-twins designs, twins reared apart from birth, and many more. A fundamental assumption underlying twin research, the equal environments assumption, is also explained and illustrated. Some more exotic approaches to studying behavior, such as the use of virtual twins and switched-at-birth twins, are also defined and described. Molecular genetic approaches to human behavior and disease that use twins are also examined, given their great proliferation in recent years. The different topics include genome-wide association studies, genome-wide complex trait analysis, copy number variations, and epigenetic analyses. Cross-cultural differences in twinning rates are also considered. These topics set the stage for the more detailed information that is provided later in the book.





  • Chapter 7 Mind Readers? Twin Telepathy, Intelligence, and Elite Performance
    22 février 2017
    Publication date: 2018
    Source:Twin Mythconceptions

    Author(s): Nancy L. Segal

    This chapter tackles what is probably the most controversial and contentious topic of all when it comes to twins: extrasensory perception. My review of research in this area demonstrates that this behavior does not exist between twins, and that there are better ways to explain identical twins’ similar choices and social connections. A second debate concerns whether or not twins, on average, are below nontwins in intelligence, and whether they are underrepresented among elite performers. The findings that give rise to these notions are examined, as is the evidence that challenges them. A related topic is cheating, that is, whether twins who perform alike are necessarily guilty of dishonest behavior.





  • Experiences of South African multiparous labouring women using the birthing ball to encourage vaginal births
    22 février 2017
    Publication date: December 2017
    Source:Health SA Gesondheid, Volume 22

    Author(s): Sindiwe James, Melissa Hudek

    The article explores the experiences of South African multiparous labouring women on their use of the birthing ball during the first stage of labour. The authors used a qualitative research approach using unstructured audiotaped interviews as the data collection method and data were collected over a period of one calendar month. The sample for the study were women who were six hours to six weeks post-delivery, had at least one child already, used the birthing ball, were on no medication, and had delivered a live infant. The sample consisted of twelve purposively selected participants, two of whom were used for the pilot study. The data analysis method was Data Analysis Spiral. The authors made use of an independent coder to assist with coding the data and three major themes were identified. The results revealed that the labouring women experienced the birthing ball as a useful labour tool, as shortening the labour process and as empowering them during labour.





  • Digestive Fistula Due to Acetabular Protrusion: Case Report and Review of the Literature
    22 février 2017
    Publication date: December 2017
    Source:Journal of Orthopaedics, Trauma and Rehabilitation, Volume 23

    Author(s): Carlos Marqués, Francisco Melchor, David Pescador, Francisco Javier García, Juan Francisco Blanco

    Intrapelvic migration of the acetabular component after primary or revision hip arthroplasty is a rare complication. We present a case of an intrapelvic migration of the acetabular component after a revision hip arthroplasty which led to an enteric fistula to the hip joint as well as to a sigmoid colon perforation.





  • Combined Anterior Cruciate Ligament Reconstruction and High Tibial Osteotomy in Anterior Cruciate Ligament-Deficient Varus Knees
    22 février 2017
    Publication date: December 2017
    Source:Journal of Orthopaedics, Trauma and Rehabilitation, Volume 23

    Author(s): Ayman M. Ebied, Adel Abdel Azim Foda

    Background The presence of varus deformity in anterior cruciate ligament (ACL)-deficient knees can be a source of persistent knee pain owing to medial compartment overload. This deformity may threaten the outcome of ACL reconstruction because of increased tension on the graft. Methods In the period between June 2006 to January 2013, 12 patients with ACL deficiency and genu varus were treated by anatomical single bundle ACL reconstruction and open medial wedge high tibial osteotomy. The selected patients had manifestations of ACL deficiency in association with medial joint line pain with or without lateral thrust. Results Prospective evaluation using the International Knee Documentation Committee (IKDC) score was performed. The mean follow-up period was 56 months (range, 26–74 months). This technique achieved knee stability and realignment to normal values. The IKDC score has significantly improved from 37 (pre-operation) to 78 (post-operation) (p <0.05). Conclusion The combined procedure of ACL reconstruction and high tibial osteotomy restored knee stability and reduced pain over the medial compartment. Although the combined procedure has a longer period of rehabilitation than an isolated ACL reconstruction, the elimination of lateral thrust and preservation of articular cartilage of the medial compartment are of paramount importance to the future of these knees.





  • A Novel Closed Method to Retrieve Broken Teflon Tube During Intramedullary Nailing in Proximal Humeral Fracture
    22 février 2017
    Publication date: December 2017
    Source:Journal of Orthopaedics, Trauma and Rehabilitation, Volume 23

    Author(s): Yuk Fai Lau, Alexander Pak Hin Chan, Jeffrey Justin Siu Cheong Koo, Ka Bon Kwok, Jason Chi Ho Fan

    Broken medullary tubes have been used for intramedullary (IM) nailing of femoral and tibial fractures. In these reported cases, fragments of the medullary tube were retrieved by opening the fracture sites or left in situ, which might jeopardize periosteal blood supply. We herein present the case of a 58-year-old woman who underwent IM nailing for proximal humeral fracture, which was complicated by breakage of the medullary tube intraoperatively. Different instruments including guide rods, straight forceps, and cement extract hook were used to retrieve the retained fragments from the medullary canal, but these attempts were unsuccessful. Finally, the fragments were successfully removed using an anterior cruciate ligament (ACL) ENDOBUTTON depth gauge. This case highlights that medullary tubes can break during humeral IM nailing, which could be minimized by ensuring integrity of the medullary tube prior to surgery and disposing medullary tubes with more than 100 exposures. A novel method of using ACL ENDOBUTTON depth gauge to retrieve retained tube fragments is recommended because of its long and slim design.





  • Correction of Combined Flexed and Stiff Knee Gait in Spastic Diplegic Cerebral Palsy by Double Tendon Transfers Around the Knee as Part of Multilevel Surgery
    22 février 2017
    Publication date: December 2017
    Source:Journal of Orthopaedics, Trauma and Rehabilitation, Volume 23

    Author(s): Kam Ling Kung, Alexander Kai Yiu Choi, Arthur King Hay Ma, Miko Lai Miu Lao, Nerita Nar Chi Chan, Tung Leung Kwun

    Background/Purpose Flexed knee gait and stiff knee gait are common coexisting gait disturbances in children with cerebral palsy. We analyzed the effect of medial hamstring transfer and distal rectus transfer around the knee as part of multi-level surgery for this group of patient. Methods Eleven lower limbs of six patients who received double transfer were retrospectively studied. Instrumented gait analysis were carried out before and a minimum of 2 years after operation. Results Comparing the kinematic study before and after the operation, maximum knee extension in stance phase (MKES), total knee swing (TKS) and the time to maximum knee flexion in swing phase (TMKFS) showed statistically significant improvement (p <0.05). Hip extension in swing phase and hip extension power were maintained. The oxygen consumption during walking also decreased after operation (p <0.05). Conclusion Double transfer around the knee can improve both flexed knee gait and stiff knee gait, without causing significant hip extension weakness.





  • Paediatric First-Time Patella Dislocators: An Approach to Conservative Management
    22 février 2017
    Publication date: December 2017
    Source:Journal of Orthopaedics, Trauma and Rehabilitation, Volume 23

    Author(s): Kai Yet Lam, Collin Looi, Arjandas Mahadev

    Background First-time lateral patella dislocations are generally treated nonoperatively. However, the ideal form of conservative management and immobilization remains unknown. We compare the clinical outcomes after different immobilization methods. Methods Paediatric-age patients that met our inclusion criteria, and presenting with a first episode of lateral patella dislocation to our hospital from 2006 to 2013, were enrolled. Different immobilization methods included brace, backslab, or cylinder cast. A retrospective review was performed to compare bracing against other immobilization methods, using a primary outcome measure of redislocation rate, and secondary outcome measures like progression to surgery, range-of-motion, pain, and weight-bearing status. Results A total of 142 patients (with 147 affected knees) with minimum 1-year follow-up were included in the study. Bracing was found to be superior to other immobilization methods in preventing repeat dislocations, and need for subsequent surgery. At 6 weeks, patients treated with the backslab had the highest incidence of pain. There were no differences with regards to range-of-motion or weight-bearing status. Conclusion We recommend the use of a brace, with a progressive rehabilitation protocol in the management of first-time lateral patella dislocators. This study is also unique, in that it specifically addresses nonoperative management of first time patella dislocators in a paediatric-age population group.





  • Reduced Incision Surgical Fixation of Diaphyseal Forearm Fractures in Adults through a Minimally Invasive Volar Approach
    22 février 2017
    Publication date: December 2017
    Source:Journal of Orthopaedics, Trauma and Rehabilitation, Volume 23

    Author(s): Li Wen Nathaniel Ng, Zongwei Joel Louis Lim, Roland Weixiang Xu, Hwee Weng Dennis Hey

    Purpose The study aimed to describe and evaluate the minimally invasive volar approach to the forearm for open reduction and internal fixation of diaphyseal radius fractures. Methods This is a matched case-control study involving patients with diaphyseal forearm fractures operated by one orthopaedic surgeon over 2 years. Cases underwent a minimally invasive volar approach, whereas controls underwent a standard Henry’s approach. In total, 17 cases and 17 controls were studied based on patient demographics, injury patterns, and surgical outcomes. Results The duration of surgery was significantly shorter for cases than for controls in combined radius and ulna fracture fixation (58.8 minutes vs. 84 minutes; p =0.03). There was no significant difference in operative time for isolated radius fractures, hospitalisation duration, and time to return to work. No malalignment or complications were observed. Conclusion The minimally invasive volar approach to the forearm is as safe and efficacious as traditional approaches in the fixation of diaphyseal radius fractures.





  • Effect of bone morphogenetic protein on Zn-HAp and Zn-HAp/collagen composite: A systematic in vivo study
    22 février 2017
    Publication date: December 2017
    Source:Research in Veterinary Science, Volume 115

    Author(s): Howa Begam, Samit Kumar Nandi, Abhijit Chanda, Biswanath Kundu

    Due to good biocompatibility and osteoconductivity, hydroxyapatite (HAp) and its composite with different polymers have been widely investigated for the application in the field of bone tissue engineering. The present study reports the, in vivo performance of zinc doped HAp and HAp/collagen composite (HAC) using bone morphogenetic protein-2. It was done for a span of two months on New Zealand rabbit model. After two months postoperatively, there was no marked inflammatory reaction in experimental groups and control groups. The histological images showed well-formed bony matrix with well differentiated haversian system. From the fluorochrome labeling study, it was observed that higher amount of new bone formed in case of bone morphogenetic protein-2 (BMP-2) loaded Zn-HAp (50%) and HAC (27%) specimens than control. The percentage of new bone formation was significantly higher in case of BMP loaded Zn-HAp group than BMP loaded HAC group. From the SEM images similar trend was observed. As the HAC specimen consists of amorphous phase, it had a negative impact on new bone formation.

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  • Distribution of bupivacaine hydrochloride after sciatic and femoral nerve blocks in cats: A magnetic resonance imaging study
    22 février 2017
    Publication date: December 2017
    Source:Research in Veterinary Science, Volume 115

    Author(s): Marina C Evangelista, Julie de Lassalle, Christine Chevrier, Eric N. Carmel, Denise T Fantoni, Paulo V M Steagall

    The objective of this study was to evaluate the distribution of bupivacaine hydrochloride using magnetic resonance imaging (MRI) after electrical nerve stimulator (ENS)-guided sciatic (ScN) and femoral (FN) nerve blocks in cats. Six adult cats (body weight 4.8±0.6kg) were anesthetized with acepromazine-buprenorphine-propofol-isoflurane. Transverse and sagittal plan sequences of pelvic limbs were obtained using a high-field magnet (1.5T). Afterwards, the ScN and FN blocks (one block per limb) were performed using 0.1mL/kg of bupivacaine 0.5% per site and the MRI sequence was repeated after each block. The injection was considered successful when bupivacaine was in contact with the nerve. Injectate location and complications were recorded. The length (mm) of contact (spread) between bupivacaine and nerves was measured and classified as fair (<15mm) or adequate (≥15mm). Five out of six ScN injections were successful; of these, four had adequate spread over the nerve [26 (13–39) mm]. All FN injections were successful, but in one case bupivacaine was administered over the motor branch of FN, distally to the bifurcation between the femoral and saphenous nerve. It was not possible to measure neither the length of contact between bupivacaine and FN nor to identify iatrogenic trauma caused by the injections. MRI can be used for the evaluation of bupivacaine distribution, but not complications, following ENS-guided ScN and FN blocks in cats. Despite most of the injections were considered successful, individual variability regarding the injectate location may explain differences in efficacy in the clinical setting.





  • Role of outer membrane protein T in pathogenicity of avian pathogenic Escherichia coli
    22 février 2017
    Publication date: December 2017
    Source:Research in Veterinary Science, Volume 115

    Author(s): Hassan M.A. Hejair, Jiale Ma, Yingchu Zhu, Min Sun, Wenyang Dong, Yue Zhang, Zihao Pan, Wei Zhang, Huochun Yao

    An outer membrane protein T (OmpT) could play a vital role in the pathogenesis of the neonatal meningitis Escherichia coli (NMEC) in human and animals. However, whether ompT plays a role in avian pathogenic E. coli (APEC) infection remains unclear. In this study we evaluated the potential of ompT in APEC pathogenesis. An ompT gene was deleted from APEC mutant strain (TW-XM) was constructed and characterized. The inactivation of ompT reduced significantly the adherence and invasion capabilities of APEC to mouse brain microvascular endothelial cell (BMEC) bEnd.3 cells at the rates of 43.8% and 28.8% respectively, compared with the wild strain TW-XM. Further studies showed that deletion of ompT gene reduced the bacterial virulence with 15.2-fold in ducklings and 9.7-fold in mouse models based on the measurement of the LD50. Furthermore, experimental infection of animals revealed that, loss of ompT showed reduced APEC colonization and invasion capacity in brains, lungs and blood by 2-fold, 1.96-fold, and 1.7-fold, respectively, compared with the wild-type strain TW-XM. These virulence-related phenotypes were partially recoverable by genetic complementation. The results of the quantitative real-time reverse transcription-PCR (qRT-PCR) indicated that the loss of ompT significantly decreased the expression levels of ompA, fimC and tsh in the mutant strain ΔOmpT, when compared with TW-XM (p <0.01). Collectively, our data showed that inactivation of ompT decreased adhesion, invasion, colonization, proliferation capacities, possibly by reduced expression levels of ompA, fimC and tsh, which may justify that, ompT is implicated in APEC pathogenicity.





  • Immunological, clinical, haematological and oxidative responses to long distance transportation in horses
    22 février 2017
    Publication date: December 2017
    Source:Research in Veterinary Science, Volume 115

    Author(s): Barbara Padalino, Sharanne Lee Raidal, Nicole Carter, Pietro Celi, Gary Muscatello, Leo Jeffcott, Kumudika de Silva

    Horses are transported frequently and often over long distances. Transportation may represent a physiological stressor with consequential health and welfare implications. This study reports the effects of a long distance journey on immunological, clinical, haematological, inflammatory and oxidative parameters in an Experimental Group (EG) of ten horses, comparing them with six horses of similar age and breed used as a non-transported Control Group (CG). Clinical examination and blood sampling were performed twice on all horses: immediately after unloading for the EG, and at rest on the same day for the CG (day 1); at rest on the same day one week later for both groups (day 7). On day 1 EG horses showed increased heart and respiratory rates (P<0.01), rectal temperature (P<0.05), capillary refilling time (P<0.01), neutrophil numbers (P<0.01), serum albumin (P<0.01), plasma total antioxidant status (P<0.01), and a lower rate of mitogen induced proliferation of lymphocytes (P<0.05), in comparison with CG. On day 7 only an increase in total serum protein (P<0.05) and serum globulins (P<0.001) was seen in the EG. No difference in serum cortisol concentration was found. Long distance transportation induced an acute phase response impairing the cell-mediated immune response. Clinical examinations, including assessing CRT and body weight loss, and the monitoring of redox balance may be useful in evaluating the impact of extensive transport events on horses. A better understanding of the link between transportation stress, the immune system and the acute phase response is likely to inform strategies for enhancing the welfare of transported horses.





  • Calciphylaxis of the breast with associated diffuse dermal angiomatosis
    22 février 2017
    Publication date: September 2017
    Source:Human Pathology: Case Reports, Volume 9

    Author(s): Magdalene Hope Maung, Judith Hugh

    In 2013, approximately 660,000 Americans had end stage renal disease (ESRD), requiring either dialysis or transplantation. Up to 5% of dialysis dependent patients may develop calcific uremic arteriolopathy or calciphylaxis (CPX) with vascular medial calcification of arterioles and subcutaneous capillaries with superimposed thrombotic occlusion. Risk factors other than chronic kidney disease include: female gender, diabetes mellitus, liver disease, warfarin, obesity, and hypercoagulability. CPX usually affects adipose rich areas on the trunk and proximal extremities, however an increasing number of reports document breast involvement. We report a case of unilateral breast CPX with a protracted clinical course and superimposed diffuse dermal angiomatosis (DDA). These two unusual cutaneous vaso-occlusive conditions have rarely been reported simultaneously. We review the literature and discuss the relationship and predisposing factors between these two conditions. We believe our case suggests that DDA could be precipitated by CPX secondary to calcific vaso-occlusion.





  • Botryoid Wilms tumor of the renal pelvis: A case report
    22 février 2017
    Publication date: September 2017
    Source:Human Pathology: Case Reports, Volume 9

    Author(s): Saori Nakachi, Hirofumi Matsumoto, Iwao Nakazato, Naoki Yoshimi







  • Primary mucinous adenocarcinoma of the eyelid: A case-series
    22 février 2017
    Publication date: September 2017
    Source:Human Pathology: Case Reports, Volume 9

    Author(s): Debra-Meghan Sanft, Pablo Zoroquiain, Bryan Arthurs, Miguel N. Burnier

    Purpose Primary mucinous adenocarcinomas (PMAs) of the eyelid are rare clinical entities typically arising from the peri-orbital area. The purpose of this case-series is to report 3 cases of PMA as well as to discuss the pathological and immunohistochemical features of these tumors. Material & methods Three cases of PMA of the eyelid were identified from 2 tertiary ophthalmology referral centers. Clinical and histopathological features of the cases were reviewed. Immunohistochemistry was performed for cytokeratin (CK) 7, CK20 and p63. Results PMA of the eyelid was identified in the three male patients, ages 63–73years old. Immunohistochemistry demonstrated positive staining for CK7 and GCDP-15 and were negative for CK20. One of the 3 cases was stained for p63, and it was found to be positive. Conclusion Due to the difficult clinical diagnosis of this often benign appearing lesion, it is imperative that physicians send all specimens for histopathological and immunohistochemical correlation. Advances in IHC including CK7 and CK20 as well as p63 are important for the diagnosis of this rare eyelid tumor, though are not yet totally definitive in their ability to distinguish PMA from other lesions with similar profiles.





  • A review of affective computing: From unimodal analysis to multimodal fusion
    22 février 2017
    Publication date: September 2017
    Source:Information Fusion, Volume 37

    Author(s): Soujanya Poria, Erik Cambria, Rajiv Bajpai, Amir Hussain

    Affective computing is an emerging interdisciplinary research field bringing together researchers and practitioners from various fields, ranging from artificial intelligence, natural language processing, to cognitive and social sciences. With the proliferation of videos posted online (e.g., on YouTube, Facebook, Twitter) for product reviews, movie reviews, political views, and more, affective computing research has increasingly evolved from conventional unimodal analysis to more complex forms of multimodal analysis. This is the primary motivation behind our first of its kind, comprehensive literature review of the diverse field of affective computing. Furthermore, existing literature surveys lack a detailed discussion of state of the art in multimodal affect analysis frameworks, which this review aims to address. Multimodality is defined by the presence of more than one modality or channel, e.g., visual, audio, text, gestures, and eye gage. In this paper, we focus mainly on the use of audio, visual and text information for multimodal affect analysis, since around 90% of the relevant literature appears to cover these three modalities. Following an overview of different techniques for unimodal affect analysis, we outline existing methods for fusing information from different modalities. As part of this review, we carry out an extensive study of different categories of state-of-the-art fusion techniques, followed by a critical analysis of potential performance improvements with multimodal analysis compared to unimodal analysis. A comprehensive overview of these two complementary fields aims to form the building blocks for readers, to better understand this challenging and exciting research field.





  • Phenotypic heterogeneity of a compound heterozygous SUCLA2 mutation
    22 février 2017
    Publication date: September 2017
    Source:Molecular Genetics and Metabolism Reports, Volume 12

    Author(s): Gerard T. Berry







  • Advances in the design and higher-order assembly of collagen mimetic peptides for regenerative medicine
    22 février 2017
    Publication date: August 2017
    Source:Current Opinion in Biotechnology, Volume 46

    Author(s): Kevin Strauss, Jean Chmielewski

    Regenerative medicine makes use of cell-supporting biomaterials to replace lost or damaged tissue. Collagen holds great potential in this regard caused by its biocompatibility and structural versatility. While natural collagen has shown promise for regenerative medicine, collagen mimetic peptides (CMPs) have emerged that allow far higher degrees of customization and ease of preparation. A wide range of two and three-dimensional assemblies have been generated from CMPs, many of which accommodate cellular adhesion and encapsulation, through careful sequence design and the exploitation of electrostatic and hydrophobic forces. But the methodology that has generated the greatest plethora of viable biomaterials is metal-promoted assembly of CMP triple helices—a rapid process that occurs under physiological conditions. Architectures generated in this manner promote cell growth, enable directed attachment of bioactive cargo, and produce living tissue.





  • Stomatal development in time: the past and the future
    22 février 2017
    Publication date: August 2017
    Source:Current Opinion in Genetics & Development, Volume 45

    Author(s): Xian Qu, Kylee M Peterson, Keiko U Torii

    Stomata have significantly diversified in nature since their first appearance around 400 million years ago. The diversification suggests the active reprogramming of molecular machineries of stomatal development during evolution. This review focuses on recent progress that sheds light on how this rewiring occurred in different organisms. Three specific aspects are discussed in this review: (i) the evolution of the transcriptional complex that governs stomatal state transitions; (ii) the evolution of receptor-ligand pairs that mediate extrinsic signaling; and (iii) the loss of stomatal development genes in an astomatous angiosperm.





  • Voltage-gated sodium channels viewed through a structural biology lens
    22 février 2017
    Publication date: August 2017
    Source:Current Opinion in Structural Biology, Volume 45

    Author(s): Thomas Clairfeuille, Hui Xu, Christopher M Koth, Jian Payandeh

    Voltage-gated sodium (Nav) channels initiate and propagate action potentials in excitable cells, and are frequently dysregulated or mutated in human disease. Despite decades of intense physiological and biophysical research, eukaryotic Nav channels have so far eluded high-resolution structure determination because of their biochemical complexity. Recently, simpler bacterial voltage-gated sodium (BacNav) channels have provided templates to understand the structural basis of voltage-dependent activation, inactivation, ion selectivity, and drug block in eukaryotic Nav and related voltage-gated calcium (Cav) channels. Further breakthroughs employing BacNav channels have also enabled visualization of bound small molecule modulators that can guide the rational design of next generation therapeutics. This review will highlight the emerging structural biology of BacNav channels and its contribution to our understanding of the gating, ion selectivity, and pharmacological regulation of eukaryotic Nav (and Cav) channels.





  • Follow-up of selective eaters from childhood to adulthood
    22 février 2017
    Publication date: August 2017
    Source:Eating Behaviors, Volume 26

    Author(s): Meredith L. Van Tine, Fiona McNicholas, Debra L. Safer, W. Stewart Agras

    Objective The aim of this study was to examine the prevalence and course of selective eating, the stability of its behavioral profile over time, and the presence of eating disorder psychopathology among selective eaters in a non-treatment seeking cohort of young adults followed longitudinally from birth to age 23. Method A prospective design tracking a subset of the original participants from the Stanford Infant Growth Study (n =216) who had been followed since birth. At age 11, 120 participants had completed all assessments. The current study included a subset of the original participants who, at age 11, had completed all assessments (n =120) and, at age 23, had current contact information available (n =62) and agreed to participate (n =61). Results Of the 61 young adults, 17 (28%) were identified as selective eaters at age 23. The selective eating-related behaviors reported during adulthood were similar to those endorsed during childhood. New onset selective eating cases were reported during adolescence or young adulthood by 35% of the selective eating sample. Participants who were selective eaters for >6years prior to age 11 remained selective at age 23. There was no evidence of increased eating disorder psychopathology, excessive thinness, or obesity in selective eaters compared with non-selective eaters. Conclusions These results suggest that a proportion of selective eaters continue from childhood into adulthood with similar eating patterns; new onset selective eating occurs in adolescence or young adulthood; and selective and non-selective eaters at age 23 do not differ with regard to weight or eating psychopathology.





  • High-disinhibition restrained eaters are disinhibited by self-regulatory depletion in the food-related inhibitory control
    22 février 2017
    Publication date: August 2017
    Source:Eating Behaviors, Volume 26

    Author(s): Yizhou Zhou, Xiao Gao, Hong Chen, Fanchang Kong

    Restrained eating for weight control and loss is becoming highly prevalent in many affluent societies, while most of the restrained eaters are rather unsuccessful in the long term. According to the strength model of self-control, the disinhibition effect of restrained eaters may occur after the depletion of self-control resources. However, no work has examined the direct impact of self-control resources on inhibitory control ability of restrained eaters. This study investigated the influences of self-control resources on the food-related inhibitory control among high-restraint/low-disinhibition restrained eaters, high-restraint/high-disinhibition restrained eaters and unrestrained eaters using stop signal task. Results reveal that there’s no difference of food-related inhibitory control between three groups when the self-control resources are non-depleted, while high-restraint/high-disinhibition restrained eaters showing a decrease of food-related inhibitory control after ego-depletion. This disinhibition effect only seems to occur in samples of restrained eaters with a high tendency toward overeating.





  • Antihypertensive peptides from animal products, marine organisms, and plants
    22 février 2017
    Publication date: 1 August 2017
    Source:Food Chemistry, Volume 228

    Author(s): Seung Yun Lee, Sun Jun Hur

    Bioactive peptides from food proteins exert beneficial effects on human health, such as angiotensin-converting enzyme (ACE) inhibition and antihypertensive activity. Several studies have reported that ACE-inhibitory peptides can come from animal products, marine organisms, and plants—derived by hydrolyzing enzymes such as pepsin, chymotrypsin, and trypsin—and microbial enzymes such as alcalase, thermolysin, flavourzyme, and proteinase K. Different ACE-inhibitory effects are closely related with different peptide sequences and molecular weights. Sequences of ACE-inhibitory peptides are composed of hydrophobic (proline) and aliphatic amino acids (isoleucine and leucine) at the N-terminus. As result of this review, we assume that low molecular weight peptides have a greater ACE inhibition because lower molecular weight peptides have a higher absorbency in the body. Therefore, the ACE-inhibitory effect is closely related with the degree of enzymatic hydrolysis and the composition of the peptide sequence.





  • Susceptibility of dry-cured tuna to oxidative deterioration and biogenic amines generation: I. Effect of NaCl content, antioxidant type and ageing
    22 février 2017
    Publication date: 1 August 2017
    Source:Food Chemistry, Volume 228

    Author(s): L.C. Roseiro, C. Santos, H. Gonçalves, C. Serrano, C. Aleixo, A. Partidário, A.R. Lourenço, M. Abreu Dias, D.J.B. da Ponte

    This study aimed to assess lipid oxidation and biogenic amine (BA) development in “muxama”, a dry-cured tuna muscle product, as affected by salt content, antioxidant type and ageing time. Overall, BA contents decreased with NaCl level (2785.1mgkg−1, 1148.1mgkg−1 and 307.7mgkg−1) and increased with ageing time (366.2mgkg−1, 1711.8mgkg−1 and 2959.2mgkg−1 in the final product (T0), and after 1 (T1) and 3 (T3) months of ageing, respectively). Regardless of the test conditions, the most concentrated BA was always tyramine. For the ageing periods considered in the present study, malondialdehyde formation was affected by the NaCl level, with the saltiest samples exhibiting lower content. Rosemary and sage extracts represented promising technological options for preserving muxama from oxidation and to minimize the presence of a fishy flavour and odour, but this treatment may cause the colour to lose some of its redness and become less appealing.





  • Development and validation of a LC-MS/MS method for the determination of isoeugenol in finfish
    22 février 2017
    Publication date: 1 August 2017
    Source:Food Chemistry, Volume 228

    Author(s): Lin Ye

    A simple, rapid, selective and sensitive LC-MS/MS method was developed and validated for the determination of isoeugenol in finfish using an off-line dansylation derivatization step to enhance signal intensity. The sample was extracted with 10mL acetone using a tissue homogenizer, followed by derivatization with dansyl chloride and analysis by liquid chromatography tandem mass spectrometry. The method detection limit ranged from 0.2 to 0.7ngg−1 in six fish species. The limit of quantification was 2.5ngg−1 in each species. Recoveries of isoeugenol at three different levels (5, 10 and 20ngg−1) over two different days ranged from 91.2% to 108.0%. Precision (%RSDR) values determined at 10ngg−1 were 4.3%, 8.0%, 5.3%, 5.1%, 2.6% and 8.0% for tilapia, catfish, trout, salmon, hybrid striped bass and yellow perch, respectively. Studies of linearity in the range 2.5–40ngg−1 produced determination coefficients (R2) above 0.997 for all matrices.





  • Analysis of cannabinoids by liquid chromatography–mass spectrometry in milk, liver and hemp seed to ensure food safety
    22 février 2017
    Publication date: 1 August 2017
    Source:Food Chemistry, Volume 228

    Author(s): Úrsula Escrivá, María Jesús Andrés-Costa, Vicente Andreu, Yolanda Picó

    A method for determining cannabinoids, Δ9-tetrahidrocannabinol (THC), 11-nor-9-carboxy-Δ9-THC (THC-COOH) and 11-hidroxy-Δ9-THC (THC-OH) in milk, liver and hemp seeds based on liquid chromatography tandem mass spectrometry has been optimized and validated. Analytes were extracted with methanol and the extracts cleaned-up by solid-phase extraction using Oasis HLB (60mg). The developed method was validated according to the Commission Decision 2002/657/EC. The decision limit (CCα) and detection capability (CCβ) ranged from 3.10–10.5ngg−1 and 3.52–11.5ngg−1, the recoveries were 76–118% and matrix effect ranged from −17.8% to 19.9% in the three matrices studied. The method was applied to food samples obtaining positive results for THC in hemp seeds (average 0.82μgg−1) and three brands of junior formula milk at concentrations from 4.76 to 56.11ngg−1. The developed method was suitable achieving identification and quantification of cannabinoids in food matrices.





  • Cryoprotective roles of trehalose and alginate oligosaccharides during frozen storage of peeled shrimp (Litopenaeus vannamei)
    22 février 2017
    Publication date: 1 August 2017
    Source:Food Chemistry, Volume 228

    Author(s): Bin Zhang, Hai-xiao Wu, Hui-cheng Yang, Xing-wei Xiang, Hai-bo Li, Shang-gui Deng

    Cryoprotective saccharides are widely accepted additives that reduce thawing loss, maintain texture, and retard protein denaturation in the frozen seafood. The present study aimed to investigate the roles of trehalose and alginate oligosaccharides on cryoprotection of frozen shrimp, primarily focusing on the interactions between myosin and saccharide molecules using a molecular dynamics (MD) simulation analysis. The results indicated that soaking in the trehalose and alginate oligosaccharides solutions markedly reduced thawing and cooking losses in frozen shrimp, with respective values decreasing to 6.02%, 8.14%, and 5.99%, 8.19% after 9weeks of storage, which were significantly lower than that of fresh water treatment (9.75% and 15.09%). Our assumption was that water replacement played a leading role in cryoprotection, as shown in previous experimental results and reports. Furthermore, homology modeling and MD simulations confirmed that trehalose and alginate oligosaccharides substituted the water molecules around the myosin surface by forming hydrogen bonds with polar residues of amino acids, thereby stabilizing the structures in the absence of water during frozen storage. These conditions affected the flexibility of particular amino acid residues, enhanced the residue cross correlations within the two chains of myosin, and also increased the total interaction energy between myosin and water/saccharide molecules, thereby leading to an increase in protein stability. Finally, by comparing the experimental results to that of MD simulation, significant positive correlation existed between saccharides and the stabilization of myosin in shrimp muscle. The findings of the present study may help better understand the cryoprotective mechanisms of saccharides in frozen shrimp, and the two saccharides may be potentially used as alternative additives in seafood to maintain better quality during frozen storage.





  • l-Carnitine ameliorates the oxidative stress response to angiotensin II by modulating NADPH oxidase through a reduction in protein kinase c activity and NF-κB translocation to the nucleus
    22 février 2017
    Publication date: 1 August 2017
    Source:Food Chemistry, Volume 228

    Author(s): Antonio J. Blanca, María V. Ruiz-Armenta, Sonia Zambrano, José L. Miguel-Carrasco, Francisco M. González-Roncero, Ana Fortuño, Elisa Revilla, Alfonso Mate, Carmen M. Vázquez

    l-Carnitine (LC) exerts beneficial effects in arterial hypertension due, in part, to its antioxidant capacity. We investigated the signalling pathways involved in the effect of LC on angiotensin II (Ang II)-induced NADPH oxidase activation in NRK-52E cells. Ang II increased the generation of superoxide anion from NADPH oxidase, as well as the amount of hydrogen peroxide and nitrotyrosine. Co-incubation with LC managed to prevent these alterations and also reverted the changes in NADPH oxidase expression triggered by Ang II. Cell signalling studies evidenced that LC did not modify Ang II-induced phosphorylation of Akt, p38 MAPK or ERK1/2. On the other hand, a significant decrease in PKC activity, and inhibition of nuclear factor kappa B (NF-kB) translocation, were attributable to LC incubation. In conclusion, LC counteracts the pro-oxidative response to Ang II by modulating NADPH oxidase enzyme via reducing the activity of PKC and the translocation of NF-kB to the nucleus.





  • Molecular study of mucin-procyanidin interaction by fluorescence quenching and Saturation Transfer Difference (STD)-NMR
    22 février 2017
    Publication date: 1 August 2017
    Source:Food Chemistry, Volume 228

    Author(s): Elsa Brandão, Mafalda Santos Silva, Ignacio García-Estévez, Nuno Mateus, Victor de Freitas, Susana Soares

    Astringency is closely related to the interaction between procyanidins and salivary proteins (SP). The aim of this work was to study the interaction between mucin, a SP responsible for saliva lubricating properties, with different procyanidins (B4 dimer, tetramer (TT) and fractions of oligomeric procyanidins), and the influence of several conditions [pH, ionic strength, procyanidins’ mean degree of polymerization (mDP) and different solvents (ethanol or dimethylsulfoxide)] on this interaction by fluorescence quenching and Saturation Transfer Difference (STD)-NMR. For fractions of oligomeric procyanidins, the mucin-procyanidin interaction increased with mDP; however, for pure compounds, procyanidin TT has lower affinity than dimer B4 which could be due to a lower structural flexibility imposed by its complex structure. Furthermore, EtOH and DMSO can disrupt the main driving forces of these interactions, hydrophobic interactions and hydrogen bonds, respectively, lowering significantly the binding constants.





  • A new real-time PCR method for rapid and specific detection of ling (Molva molva)
    22 février 2017
    Publication date: 1 August 2017
    Source:Food Chemistry, Volume 228

    Author(s): Ledicia Taboada, Ana Sánchez, Carmen G. Sotelo

    Seafood fraud – often involving substitution of one species by another – has attracted much attention as it is prevalent worldwide. Whilst DNA analysis has helped to combat this type of fraud some of the methods currently in use are time-consuming and require sophisticated equipment or highly-trained personnel. This work describes the development of a new, real-time PCR TaqMan assay for the detection of ling (Molva molva) in seafood products. For this purpose, specific primers and a minor groove binding (MGB) TaqMan probe were designed to amplify the 81bp region on the cyt b gene. Efficiency, specificity and cross-reactivity assays showed statistically significant differences between the average Ct value obtained for Molva molva DNA (19.45±0.65) and the average Ct for non-target species DNA (38.3±2.8), even with closely related species such as Molva dypterygia (34.9±0.09). The proposed methodology has been validated with 31 commercial samples.





  • Bacterial communities of fresh goat meat packaged in modified atmosphere
    22 février 2017
    Publication date: August 2017
    Source:Food Microbiology, Volume 65

    Author(s): Elia Carrizosa, María José Benito, Santiago Ruiz-Moyano, Alejandro Hernández, Maria del Carmen Villalobos, Alberto Martín, María de Guía Córdoba

    The objective of this work was to study the growth and development of fortuitous flora and food pathogens in fresh goat meat packaged under modified atmospheres containing two different concentrations of CO2. Meat samples were stored at 10 °C under two different modified-atmosphere packing (MAP) conditions: treatment A had 45% CO2 + 20% O2 + 35% N2 and treatment B had 20% CO2 + 55% O2 + 25% N2. During 14 days of storage, counts of each bacterial group and dominant species identification by 16S rRNA gene sequencing were performed to determine the microbial diversity present. The MAP condition used for treatment A was a more effective gas mixture for increasing the shelf life of fresh goat meat, significantly reducing the total number of viable bacteria and enterobacteria counts. Members of the Enterobacteriaceae family were the most common contaminants, although Hafnia alvei was dominant in treatment A and Serratia proteamaculans in treatment B. Identification studies at the species level showed that different microorganisms develop under different storage conditions, reflecting the importance of gas composition in the modified atmosphere on the bacterial community. This work provides new insights into the microbial changes of goat meat storage under different MAP conditions, which will be beneficial for the meat industry.





  • Eulerian finite element method for the numerical modeling of fluid dynamics of natural and pathological aortic valves
    22 février 2017
    Publication date: 1 August 2017
    Source:Journal of Computational and Applied Mathematics, Volume 319

    Author(s): Aymen Laadhari, Gábor Székely

    We present a finite element methodology tailored for the simulation of pulsatile flow in the full aorta and sinus of Valsalva interacting with highly deformable thin leaflets. We describe an extension of the so-called “Resistive Immersed Surface” method. To circumvent stability issues resulting from the bad conditioning of the linear system, especially when flow and geometry become complex after the inclusion of the aorta, we use a Lagrange multiplier technique that couples the dynamics of valve and flow. A banded level set variant allows to address the singularity of the resulting linear system while featuring, in addition to the parallel implementation, higher accuracy and an affordable computational burden. High-fidelity computational geometries are built and simulations are performed under physiological conditions. Several numerical experiments illustrate the ability of the model to capture the basic fluidic phenomena in both healthy and pathological configurations. We finally examine numerically the flow dynamics in the sinus of Valsalva after Transcatheter Aortic Valve Implantation. We show numerically that flow may be subject to stagnation in the lower part of the sinuses. We highlight the far-reaching implications of this phenomenon and we hope inciting adequate studies to further investigate its potential clinical consequences.

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  • Angiogenesis in the atherosclerotic plaque
    22 février 2017
    Publication date: August 2017
    Source:Redox Biology, Volume 12

    Author(s): Caroline Camaré, Mélanie Pucelle, Anne Nègre-Salvayre, Robert Salvayre

    Atherosclerosis is a multifocal alteration of the vascular wall of medium and large arteries characterized by a local accumulation of cholesterol and non-resolving inflammation. Atherothrombotic complications are the leading cause of disability and mortality in western countries. Neovascularization in atherosclerotic lesions plays a major role in plaque growth and instability. The angiogenic process is mediated by classical angiogenic factors and by additional factors specific to atherosclerotic angiogenesis. In addition to its role in plaque progression, neovascularization may take part in plaque destabilization and thromboembolic events. Anti-angiogenic agents are effective to reduce atherosclerosis progression in various animal models. However, clinical trials with anti-angiogenic drugs, mainly anti-VEGF/VEGFR, used in anti-cancer therapy show cardiovascular adverse effects, and require additional investigations.

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  • Taking up the cudgels for the traditional reactive oxygen and nitrogen species detection assays and their use in the cardiovascular system
    22 février 2017
    Publication date: August 2017
    Source:Redox Biology, Volume 12

    Author(s): Andreas Daiber, Matthias Oelze, Sebastian Steven, Swenja Kröller-Schön, Thomas Münzel

    Reactive oxygen and nitrogen species (RONS such as H2O2, nitric oxide) confer redox regulation of essential cellular functions (e.g. differentiation, proliferation, migration, apoptosis), initiate and catalyze adaptive stress responses. In contrast, excessive formation of RONS caused by impaired break-down by cellular antioxidant systems and/or insufficient repair of the resulting oxidative damage of biomolecules may lead to appreciable impairment of cellular function and in the worst case to cell death, organ dysfunction and severe disease phenotypes of the entire organism. Therefore, the knowledge of the severity of oxidative stress and tissue specific localization is of great biological and clinical importance. However, at this level of investigation quantitative information may be enough. For the development of specific drugs, the cellular and subcellular localization of the sources of RONS or even the nature of the reactive species may be of great importance, and accordingly, more qualitative information is required. These two different philosophies currently compete with each other and their different needs (also reflected by different detection assays) often lead to controversial discussions within the redox research community. With the present review we want to shed some light on these different philosophies and needs (based on our personal views), but also to defend some of the traditional assays for the detection of RONS that work very well in our hands and to provide some guidelines how to use and interpret the results of these assays. We will also provide an overview on the “new assays” with a brief discussion on their strengths but also weaknesses and limitations.





  • Shortcuts to a functional adipose tissue: The role of small non-coding RNAs
    22 février 2017
    Publication date: August 2017
    Source:Redox Biology, Volume 12

    Author(s): Bruna B. Brandão, Beatriz A. Guerra, Marcelo A. Mori

    Metabolic diseases such as type 2 diabetes are a major public health issue worldwide. These diseases are often linked to a dysfunctional adipose tissue. Fat is a large, heterogenic, pleiotropic and rather complex tissue. It is found in virtually all cavities of the human body, shows unique plasticity among tissues, and harbors many cell types in addition to its main functional unit – the adipocyte. Adipose tissue function varies depending on the localization of the fat depot, the cell composition of the tissue and the energy status of the organism. While the white adipose tissue (WAT) serves as the main site for triglyceride storage and acts as an important endocrine organ, the brown adipose tissue (BAT) is responsible for thermogenesis. Beige adipocytes can also appear in WAT depots to sustain heat production upon certain conditions, and it is becoming clear that adipose tissue depots can switch phenotypes depending on cell autonomous and non-autonomous stimuli. To maintain such degree of plasticity and respond adequately to changes in the energy balance, three basic processes need to be properly functioning in the adipose tissue: i) adipogenesis and adipocyte turnover, ii) metabolism, and iii) signaling. Here we review the fundamental role of small non-coding RNAs (sncRNAs) in these processes, with focus on microRNAs, and demonstrate their importance in adipose tissue function and whole body metabolic control in mammals.

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  • Reciprocal regulation of eNOS, H2S and CO-synthesizing enzymes in human atheroma: Correlation with plaque stability and effects of simvastatin
    22 février 2017
    Publication date: August 2017
    Source:Redox Biology, Volume 12

    Author(s): Fragiska Sigala, Panagiotis Efentakis, Dimitra Karageorgiadi, Konstadinos Filis, Paraskevas Zampas, Efstathios K. Iliodromitis, George Zografos, Andreas Papapetropoulos, Ioanna Andreadou

    The molecular and cellular mechanisms underlying plaque destabilization remain obscure. We sought to elucidate the correlation between NO, H2S and CO-generating enzymes, nitro-oxidative stress and plaque stability in carotid arteries. Carotid atherosclerotic plaques were collected from 62 patients who had undergone endarterectomy due to internal artery stenosis. Following histological evaluation the plaques were divided into stable and unstable ones. To investigate the impact of simvastatin we divided patients with stable plaques, into those receiving and to those not receiving simvastatin. Expression and/or levels of p-eNOS/eNOS, pAkt/t-Akt, iNOS, cystathionine beta synthase (CBS), cystathionine gamma lyase (CSE), heme oxygenase-1(HO-1), soluble guanyl cyclase sGCα1, sGCβ1, NOX-4 and HIF-1α were evaluated. Oxidative stress biomarkers malondialdehyde (MDA) and nitrotyrosine (NT) were measured. NT levels were decreased in stable plaques with a concomitant increase of eNOS phosphorylation and expression and Akt activation compared to unstable lesions. An increase in HIF-1α, NOX-4, HO-1, iNOS, CBS and CSE expression was observed only in unstable plaques. 78% of patients under simvastatin were diagnosed with stable plaques whereas 23% of those not receiving simvastatin exhibited unstable plaques. Simvastatin decreased iNOS, HO-1, HIF-1α and CSE whilst it increased eNOS phosphorylation. In conclusion, enhanced eNOS and reduced iNOS and NOX-4 were observed in stable plaques; CBS and CSE positively correlated with plaque vulnerability. Simvastatin, besides its known effect on eNOS upregulation, reduced the HIF-1α and its downstream targets. The observed changes might be useful in developing biomarkers of plaque stability or could be targets for pharmacothepary against plaque vulnerability.





  • Numerical analysis and simulation of a bio-thermal model for the human foot
    22 février 2017
    Publication date: 15 July 2017
    Source:Applied Mathematics and Computation, Volume 305

    Author(s): M.I.M. Copetti, J. Durany, J.R. Fernández, L. Poceiro

    This paper analyses the numerical convergence and the approximation of the finite element method applied to a biothermal nonlinear model for the bare foot. As far as we know, there is not a previous finite element analysis of this well-known bioheat equation. Thus, this work can be seen as a first step to study the coupling with energy and mass transfer models (water, vapor and gas) at the textiles surrounding the foot. The model is posed as a steady partial differential equation for the temperature field, and a non-linear boundary condition on the external boundary, where heat losses due to convection, radiation and evaporation are considered. The existence and the uniqueness of the solution is proved for the weak formulation and also for its finite element approximation by using arguments of monotone operators. Then, numerical convergence and an a priori error estimates result are obtained. Some numerical simulations are presented to show the accuracy of the numerical method and the behavior of the solution, being qualitatively acceptable and, in some cases, validated against experimentation, being quantitatively correct too. Interesting conclusions are followed from the analysis of the model parameters as well as from the comparison of 2D and 3D solutions.





  • Antioxidant and functional properties of protein hydrolysates obtained from squid pen chitosan extraction effluent
    22 février 2017
    Publication date: 15 July 2017
    Source:Food Chemistry, Volume 227

    Author(s): Amin Shavandi, Zhihao Hu, SueSiang Teh, Jenny Zhao, Alan Carne, Adnan Bekhit, Alaa El-Din A. Bekhit

    Squid pens were subjected to alkali hydrolysis to extract chitin and chitosan. Proteins present in the alkaline extraction wastewater were recovered at pH 3, 4, 5 and 6, and were subjected to hydrolysis by trypsin, pepsin and a bacterial protease called HT for 1, 2, 4 and 24h. Hydrolysis of the extracted proteins with either trypsin or HT generated more antioxidant activity than hydrolysis with pepsin. Higher ACE-inhibitory activity was generated in the trypsin and pepsin hydrolysates than in the HT hydrolysate. Squid pen protein recovered from chitosan processing waste alkaline solution can be a potential source of bioactive peptides for addition to foods. The antioxidant and ACE-inhibitory activities of the extracted proteins were initially low and increased upon incubation with the proteases. Pepsin generated significantly lower (P<0.05) antioxidant activities compared to trypsin and HT, while trypsin and pepsin hydrolysates exhibited higher ACE-inhibitory activity than HT (P<0.05).





  • Changes in the myosin secondary structure and shrimp surimi gel strength induced by dense phase carbon dioxide
    22 février 2017
    Publication date: 15 July 2017
    Source:Food Chemistry, Volume 227

    Author(s): Minghui Guo, Shucheng Liu, Marliya Ismail, Mohammed M. Farid, Hongwu Ji, Weijie Mao, Jing Gao, Chengyong Li

    Dense phase carbon dioxide (DPCD) could induce protein conformation changes. Myosin and shrimp surimi from Litopenaeus vannamei were treated with DPCD at 5–25MPa and 40–60°C for 20min. Myosin secondary structure was investigated by circular dichroism and shrimp surimi gel strength was determined using textural analysis to develop correlations between them. DPCD had a greater effect on secondary structure and gel strength than heating. With increasing pressure and temperature, the α-helix content of DPCD-treated myosin decreased, while the β-sheet, β-turn and random coil contents increased, and the shrimp surimi gel strength increased. The α-helix content was negatively correlated with gel strength, while the β-sheet, β-turn and random coil contents were positively correlated with gel strength. Therefore, when DPCD induced myosin to form a gel, the α-helix of myosin was unfolded and gradually converted to a β-sheet. Such transformations led to protein-protein interactions and cross-linking, which formed a three-dimensional network to enhance the gel strength.





  • Effect of 4-hydroxy-2-nonenal on myoglobin-mediated lipid oxidation when varying histidine content and hemin affinity
    22 février 2017
    Publication date: 15 July 2017
    Source:Food Chemistry, Volume 227

    Author(s): Eric W. Grunwald, Nantawat Tatiyaborworntham, Cameron Faustman, Mark P. Richards

    The compound 4-hydroxy-2-nonenal (HNE) dissolved in water was examined to remove potential effects of using ethanol to solubilize the aldehyde such as altering protein structure or redox properties of myoglobin (Mb). HNE became covalently bound to sperm whale Mb at up to five sites based on ESI-MS analysis. Adducted Mb promoted lipid oxidation in washed muscle more effectively than non-adducted Mb. Alkylation of P88H/Q152HMb with HNE accelerated metMb formation and subsequent lipid oxidation. P88H/Q152HMb exposed to HNE enhanced lipid oxidation compared to wild-type Mb exposed to HNE. Results using H97A Mb suggested that the combination of HNE and low hemin affinity facilitated rapid decomposition of preformed lipid hydroperoxides to secondary lipid oxidation products. HNE and HHE (4-hydroxy-2-hexenal) facilitated Mb-mediated lipid oxidation similarly. The potential mechanisms by which Mb binding of α,β-unsaturated aldehydes affect Mb oxidation and the onset of lipid oxidation are discussed.





  • Incorporation of dietary fibre-rich oyster mushroom (Pleurotus sajor-caju) powder improves postprandial glycaemic response by interfering with starch granule structure and starch digestibility of biscuit
    22 février 2017
    Publication date: 15 July 2017
    Source:Food Chemistry, Volume 227

    Author(s): Sze Han Ng, Sathyasurya Daniel Robert, Wan Amir Nizam Wan Ahmad, Wan Rosli Wan Ishak

    The purpose of this study was to determine the effects of Pleurotus sajor-caju (PSC) powder addition at 0, 4, 8 and 12% levels on the nutritional values, pasting properties, thermal characteristics, microstructure, in vitro starch digestibility, in vivo glycaemic index (GI) and sensorial properties of biscuits. Elevated incorporation levels of PSC powder increased the dietary fibre (DF) content and reduced the pasting viscosities and starch gelatinisation enthalpy value of biscuits. The addition of DF-rich PSC powder also interfered with the integrity of the starch granules by reducing the sizes and inducing the uneven spherical shapes of the starch granules, which, in turn, resulted in reduced starch susceptibility to digestive enzymes. The restriction starch hydrolysis rate markedly reduced the GI of biscuits. The incorporation of 8% PSC powder in biscuits (GI=49) could be an effective way of developing a nutritious and low-GI biscuit without jeopardizing its desirable sensorial properties.





  • Detection of β-agonists in pork tissue with novel electrospun nanofibers-based solid-phase extraction followed ultra-high performance liquid chromatography/tandem mass spectrometry
    22 février 2017
    Publication date: 15 July 2017
    Source:Food Chemistry, Volume 227

    Author(s): Lanling Chu, Shenglan Zheng, Bin Qu, Shiwei Geng, Xuejun Kang

    A selective analytical method based on packed-fiber solid-phase extraction and ultra-high performance liquid chromatography–tandem mass spectrometry (PFSPE-UPLC–MS/MS) has been developed for determination of six β-agonists (clorprenaline, bambuterol, clenbuterol, brombuterol, mabuterol, and penbuterol) in pork tissue. Polystyrene-polymeric crown ether (PS-PCE) composite nanofibers were fabricated by electrospinning and utilized to prepare the homemade extraction columns. With optimal conditions, all analytes were separated very well and the blank pork did not disturb the determination, and the linearity is good in a range of 5.0μg/kg–25.0μg/kg. The recoveries were 79.3–110.1%. RSDs for intra-day were in the range of 1.5–10.5% and RSDs for inter-day were 4.7–11.8%. Above all, only 5mg of sorbent and 200μL of elution solvent were favorable to directly extract all analytes in a complex matrix. The method is simple and cost-effective, and has the potential to be applied to quantitatively analyze the concentrations of polar species in food samples containing complex matrix.





  • Effect of tailored, gamified, mobile physical activity intervention on life satisfaction and self-rated health in young adolescent men: A population-based, randomized controlled trial (MOPO study)
    22 février 2017
    Publication date: July 2017
    Source:Computers in Human Behavior, Volume 72

    Author(s): Riitta Pyky, Heli Koivumaa-Honkanen, Anna-Maiju Leinonen, Riikka Ahola, Noora Hirvonen, Heidi Enwald, Tim Luoto, Eija Ferreira, Tiina M. Ikäheimo, Sirkka Keinänen-Kiukaanniemi, Matti Mäntysaari, Timo Jämsä, Raija Korpelainen

    Background Online behavior-change programs may increase physical activity in adolescents, but their effects on subjective health and wellbeing are not well known. Purpose We investigated the effects of a mobile physical activity intervention on life satisfaction and self-rated health among young adolescent men. Methods In this population-based study, 496 men (17.8y, SD 0.6y) participated in a 6-month trial. They were randomized into an intervention (n = 250) and a control group (n = 246). Only the intervention group had access to a tailored mobile service. Life satisfaction and self-rated health were inquired about at baseline and at the end of the trial. Results Life satisfaction improved in the intervention (p < 0.001) and control group (p = 0.01). Life satisfaction was most likely to improve among men with low baseline satisfaction (OR 13.8; 95% CI 3.7–51.8) and mood-related exercise motive (2.5 (1.1–5.6)). There were no statistically significant changes in self-rated health, but those who reported poor health at baseline (OR 9.6; 95% CI 3.7–24.9) and improved self-rated fitness during the trial (4.2 (1.5–11.9)) were more likely to gain improvements in self-rated health. Conclusion In this mobile physical activity intervention, improvements in self-rated health and life satisfaction were associated with low life satisfaction and poor self-rated health at baseline within the intervention group. Trial registration This randomized controlled trial is registered to the clinical trials register NCT01376986.





  • How do older and young adults start searching for information? Impact of age, domain knowledge and problem complexity on the different steps of information searching
    22 février 2017
    Publication date: July 2017
    Source:Computers in Human Behavior, Volume 72

    Author(s): M. Sanchiz, A. Chevalier, F. Amadieu

    The present study addressed the age-related differences in query production and information searching performance when interacting with a search engine. To this end, 20 older adults and 20 young ones performed 12 information search problems of varying complexity in two knowledge domains (health and fantastic movies). Participants had simple (useful keywords provided and answer directly accessible in Google), inferential (inferences to produce useful keywords required) and multicriteria problems (information gathering and navigation required). Results showed that older adults produced their first query with more keywords extracted from the search problem statements and spent more time on the search engine pages than young ones. In the fantastic movies, older adults struggled more than young ones and had difficulties reformulating their queries (i.e. fewer new keywords produced, more statement provided keywords). Older adults especially struggled at the beginning of the search (more time spent on the first search engine result page than young ones and they produced less elaborate initial query). In contrast, in the health domain, higher prior knowledge helped older users reformulate queries that were more elaborated (i.e.no age-related differences on the number of new keywords) and improved the processing of the first search engine page consulted.





  • Cyberloafing and social desirability bias among students and employees
    22 février 2017
    Publication date: July 2017
    Source:Computers in Human Behavior, Volume 72

    Author(s): Yavuz Akbulut, Onur Dönmez, Özcan Özgür Dursun

    This study addressed the prevalence of cyberloafing and social desirability bias among 1339 students and 996 jobholders. An online survey was administered which included a five-factor cyberloafing scale and a two-factor social desirability scale. Each measure revealed acceptable fit values in confirmatory factor analyses. Findings showed that different types of cyberloafing had different prevalence rates. Students surpassed employees and males surpassed females with regard to overall cyberloafing scores. However, different types of cyberloafing revealed different patterns in individual comparisons. Employees surpassed students in terms of the impression management component of social desirability. Cyberloafing and social desirability were positively related, which implied the need for including social desirability as a covariate in further research.





  • The MEK1 inhibitors UO126 and PD98059 block PDGF-AB induced phosphorylation of threonine 292 in porcine smooth muscle cells
    22 février 2017
    Publication date: July 2017
    Source:Cytokine, Volume 95

    Author(s): Thomas Kubin, Ayse Cetinkaya, Markus Schönburg, Andres Beiras-Fernandez, Thomas Walther, Manfred Richter

    PDGF-AB and FGF-2 (GFs) induce smooth muscle cell (SMC) proliferation which is indispensible for arteriogenesis. While there is common agreement that GFs stimulate SMC proliferation through phosphorylation (P-) of MEK1/2 at Ser218/222, we previously demonstrated that the MEK inhibitors PD98059 and UO126 did not inhibit P-Ser218/222 as originally proposed but caused strong hyperphosphorylation. Here, we demonstrate that GFs increased phosphorylation of MEK1 at Thr292 while UO126 and PD98059 blocked this phosphorylation. This was again surprising since phosphorylation of Thr292 is regarded as a negative feedback loop. Our findings suggest that inhibition of Thr292 phosphorylation in combination with hyperphosphorylation of Ser218/222 serves as an “off” switch of SMC proliferation and potentially of arteriogenesis.





  • Histamine and mast cell activator compound 48/80 are safe but inefficient systemic adjuvants for gilthead seabream vaccination
    22 février 2017
    Publication date: July 2017
    Source:Developmental & Comparative Immunology, Volume 72

    Author(s): N.E. Gómez González, I. Cabas, J. Montero, A. García Alcázar, V. Mulero, A. García Ayala

    Histamine has a key role in the regulation of inflammatory and innate immune responses in vertebrates. Gilthead seabream (Sparus aurata L.), a marine hermaphrodite teleost of great commercial value, was the first fish species shown to possess histamine-containing mast cells (MCs) at mucosal tissues. MCs are highly abundant in the peritoneal exudate of gilthead seabream and compound 48/80 (Co 48/80), often used to promote MC activation and histamine release, is able to promote histamine release from gilthead seabream MCs in vitro and in vivo. The aim of the present study was to analyze the effect of histamine and Co 48/80 on the immune responses of gilthead seabream. For this purpose, histamine and Co 48/80 were intraperitoneally injected alone or combined with 109 heat-killed Vibrio anguillarum cells and their effects on head kidney and peritoneal exudate were analyzed. The results indicated that although histamine and Co 48/80 were both able to alter the percentage of peritoneal exudate and head kidney immune cell types, only Co 48/80 increased reactive oxygen species production by peritoneal leukocytes. In addition, histamine, but not Co 48/80, was able to slightly impair the humoral adaptive immune response, i.e. production of specific IgM to V. anguillarum. Notably, both histamine and Co 48/80 reduced the expression of the gene encoding histamine receptor H2 in peritoneal exudate leukocytes. These results show for the first time in fish that although systemic administration of histamine and Co 48/80 is safe, neither compound can be regarded as an efficient adjuvant for gilthead seabream vaccination.





  • Heat shock 70 kDa protein cognate 5 involved in WSSV toleration of Litopenaeus vannamei
    22 février 2017
    Publication date: July 2017
    Source:Developmental & Comparative Immunology, Volume 72

    Author(s): Kai Yuan, Feng-Hua Yuan, Hong-Hui He, Hai-Tao Bi, Shao-Ping Weng, Jian-Guo He, Yi-Hong Chen

    The expression levels of 97 unigenes encoding heat shock proteins of Litopenaeus vannamei was scanned, and ten of them were significantly induced by white spot syndrome virus (WSSV). Among these genes, heat shock 70 kDa protein cognate 5 (LvHSC70-5) was upregulated to the highest extent and subjected to further studies. Subcellular localization assay revealed that LvHSC70-5 was located in the mitochondria. Aside from WSSV infection, unfolded protein response activation and thermal stress could also upregulate LvHSC70-5. Results of reporter gene assay demonstrated that promoter of LvHSC70-5 was activated by L. vannamei heat shock factor protein 1, activating transcription factor 4 and thermal stress. A decrease in the expression of LvHSC70-5 could reduce the aggregation of proteins in hemocytes and the cumulative mortality of WSSV-infected L. vannamei. LvHSC70-5 in L. vannamei hemocytes was upregulated by mild thermal stress. In addition, mild thermal stress, decreased the copy number of WSSV in shrimp muscle and the cumulative mortality of WSSV-infected L. vannamei. Therefore, collecting results suggested that LvHSC70-5 should be involved in WSSV toleration of shrimp L. vannamei.





  • Enzymatic synthesis of lysophosphatidylcholine with n−3 polyunsaturated fatty acid from sn-glycero-3-phosphatidylcholine in a solvent-free system
    22 février 2017
    Publication date: 1 July 2017
    Source:Food Chemistry, Volume 226

    Author(s): Yanjun Liu, Qin Zhang, Yongli Guo, Junyi Liu, Jie Xu, Zhaojie Li, Jingfeng Wang, Yuming Wang, Changhu Xue

    The n−3 polyunsaturated fatty acids (PUFA)-rich lysophosphatidylcholine (LPC) was successfully synthesized by Thermomyces lanuginosus lipase (TL IM)-catalyzed esterification of glycerylphosphorylcholine (GPC) and n−3 PUFA-rich fatty acids in a solvent-free system. Effects of reaction temperature, enzyme loading and substrate mole ratio on the yield of LPC and incorporation of n−3 PUFA were evaluated. The acyl-specificities of five enzymes were tested for direct esterification of n−3 PUFA, and Lipozyme TL IM was found to be more effective than others for production of LPC with n−3 PUFA. Substrate mole ratio and reaction temperature, however, had no significant effect on the incorporation. The maximal yield of LPC was obtained under the following conditions: temperature 45°C, enzyme loading 15% by weight and substrate mole ratio (GPC/n−3 PUFA) 1:20. Furthermore, the composition of products were further investigated in the study. The 1-acyl-sn-glycero-3-lysophosphatidylcholine (2-LPC) was predominant in the mixtures at early stages of reaction, whereas less increment of 2-acyl-sn-glycero-3-lysophosphatidylcholine (1-LPC) and PC was observed at later stages.






 

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  • Paediatric First-Time Patella Dislocators: An Approach to Conservative Management
    22 février 2017
    Publication date: December 2017
    Source:Journal of Orthopaedics, Trauma and Rehabilitation, Volume 23

    Author(s): Kai Yet Lam, Collin Looi, Arjandas Mahadev

    Background First-time lateral patella dislocations are generally treated nonoperatively. However, the ideal form of conservative management and immobilization remains unknown. We compare the clinical outcomes after different immobilization methods. Methods Paediatric-age patients that met our inclusion criteria, and presenting with a first episode of lateral patella dislocation to our hospital from 2006 to 2013, were enrolled. Different immobilization methods included brace, backslab, or cylinder cast. A retrospective review was performed to compare bracing against other immobilization methods, using a primary outcome measure of redislocation rate, and secondary outcome measures like progression to surgery, range-of-motion, pain, and weight-bearing status. Results A total of 142 patients (with 147 affected knees) with minimum 1-year follow-up were included in the study. Bracing was found to be superior to other immobilization methods in preventing repeat dislocations, and need for subsequent surgery. At 6 weeks, patients treated with the backslab had the highest incidence of pain. There were no differences with regards to range-of-motion or weight-bearing status. Conclusion We recommend the use of a brace, with a progressive rehabilitation protocol in the management of first-time lateral patella dislocators. This study is also unique, in that it specifically addresses nonoperative management of first time patella dislocators in a paediatric-age population group.





  • Efficiency evaluation of robots in machining applications using industrial performance measure
    22 février 2017
    Publication date: December 2017
    Source:Robotics and Computer-Integrated Manufacturing, Volume 48

    Author(s): Alexandr Klimchik, Alexandre Ambiehl, Sébastien Garnier, Benoit Furet, Anatol Pashkevich

    The paper is devoted to the robotic based machining. The main focus is made on robot accuracy in milling operation and evaluation robot capacity to perform the task with desired precision. Particular attention is paid to the proper modeling of manipulator stiffness properties and the cutting force estimation. In contrast to other works, the robot performance is evaluated using the circularity norm that evaluates the contortion degree of the benchmark circle to be machined. The developed approach is applied to five industrial robots of KUKA family, which have been ranked for several machining tasks. The validity of the proposed technique was confirmed by experimental study dealing with robot-based machining of circular grooves for several workpiece samples and different locations.





  • A Mode-Accelerated XXr (MAX) method for complex structures with large blends
    22 février 2017
    Publication date: 1 September 2017
    Source:Mechanical Systems and Signal Processing, Volume 93

    Author(s): Yiqian Gan, John L. Mayer, Kiran X. D’Souza, Bogdan I. Epureanu

    Various reduced order models have been proposed for characterizing cyclic symmetric structures with complex geometry and varying material properties that are subject to complex boundary or loading conditions. Small variations can be represented as small mass or stiffness mistuning. Techniques developed to handle such variations rely on the fact that the modes of the system can be accurately approximated using a linear combination of modes of the healthy/nominal system. Such approximations are valid in regions of high modal density, but they break down when variations are large or geometric changes are present. To address this challenge, a novel method is presented to predict the vibration response of cyclic symmetric structures with large geometric changes due to damage in the form of missing material (blends). The central idea of the new approach is an extension of the XXr method for cracked structures. The XXr method was developed for modeling small mistuning and large cracks. That method is extended in this work to handle large blends. In addition, a specialized component mode synthesis is combined with the extended XXr method to maintain accuracy. Also, unique to the proposed novel method is a technique to accelerate the convergence of the order reduction, and thus obtain very low order models. These low order models provide excellent computational speed and effectiveness while maintaining accuracy. Therefore, the method can be applied to highly refined, realistic models of industrial size. To demonstrate the proposed mode-accelerated XXr method, the effects of large blends on the response of a bladed disk are investigated.





  • Experimental investigation of the influence of internal frames on the vibroacoustic behavior of a stiffened cylindrical shell using wavenumber analysis
    22 février 2017
    Publication date: 1 September 2017
    Source:Mechanical Systems and Signal Processing, Volume 93

    Author(s): V. Meyer, L. Maxit, Y. Renou, C. Audoly

    The understanding of the influence of non-axisymmetric internal frames on the vibroacoustic behavior of a stiffened cylindrical shell is of high interest for the naval or aeronautic industries. Several numerical studies have shown that the non-axisymmetric internal frame can increase the radiation efficiency significantly in the case of a mechanical point force. However, less attention has been paid to the experimental verification of this statement. That is why this paper proposes to compare the radiation efficiency estimated experimentally for a stiffened cylindrical shell with and without internal frames. The experimental process is based on scanning laser vibrometer measurements of the vibrations on the surface of the shell. A transform of the vibratory field in the wavenumber domain is then performed. It allows estimating the far-field radiated pressure with the stationary phase theorem. An increase of the radiation efficiency is observed in the low frequencies. Analysis of the velocity field in the physical and wavenumber spaces allows highlighting the coupling of the circumferential orders at the origin of the increase in the radiation efficiency.





  • Unbalance vibration suppression for AMBs system using adaptive notch filter
    22 février 2017
    Publication date: 1 September 2017
    Source:Mechanical Systems and Signal Processing, Volume 93

    Author(s): Qi Chen, Gang Liu, Bangcheng Han

    The unbalance of rotor levitated by active magnetic bearings (AMBs) will cause synchronous vibration which greatly degrade the performance at high speeds in the rotating machinery. To suppress the unbalance vibration without angular velocity information, a novel modified adaptive notch filter (ANF) with phase shift in the AMBs system is presented in this study. Firstly, a 4-degree-of-freedom (DOF) radial unbalanced AMB rotor system is described and analyzed, and the solution of rotor vibration displacement is compared with the experimental data to verify the preciseness of the dynamic model. Then the principle and structure of the proposed notch filter used for the frequency estimation and online identification of synchronous component are presented. As well, the convergence property of the algorithm is investigated. In addition, the stability analysis of the closed-loop AMB system with the proposed ANF is conducted. Simulation and experiments on an AMB driveline system demonstrate the effectiveness and the adaptive characteristics of the proposed ANF on the elimination of synchronous controlled current in a widely operating speed range.





  • Coexistence of two families of sub-harmonic resonances in a time-delayed nonlinear system at different forcing frequencies
    22 février 2017
    Publication date: 1 September 2017
    Source:Mechanical Systems and Signal Processing, Volume 93

    Author(s): J.C. Ji, Jin Zhou

    Two coexisting families of sub-harmonic resonances can be induced at different forcing frequencies in a time-delayed nonlinear system having quadratic nonlinearities. They occur in the region where two stable bifurcating periodic solutions coexist in the corresponding autonomous system following two-to-one resonant Hopf bifurcations of the trivial equilibrium. The forced response is found to demonstrate small- and large-amplitude quasi-periodic motion under the family of sub-harmonic resonances related to Hopf bifurcation frequencies, and large-amplitude periodic and quasi-periodic motion under the family of sub-harmonic resonances associated with the shifted Hopf bifurcation frequencies. The family of sub-harmonic resonances related to Hopf bifurcation frequencies may cease to exist with the loss of the initially established frequency relationship of sub-harmonic resonances when the magnitude of periodic excitation is beyond a certain value. This will lead to a jump phenomenon from small- to large-amplitude quasi-periodic motion. Bifurcation diagrams, time trajectories and frequency spectra are numerically obtained to characterize the sub-harmonic resonances of the time-delayed nonlinear system around the critical point of the resonant Hopf bifurcations.





  • Novel bursting patterns in a Van der pol-Duffing oscillator with slow varying external force
    22 février 2017
    Publication date: 1 September 2017
    Source:Mechanical Systems and Signal Processing, Volume 93

    Author(s): Yue Yu, Min Zhao, Zhengdi Zhang

    In this paper, we investigate the emergence of bursting dynamics with complex waveforms and their relation to periodic behavior in typical Van der pol-Duffing equation with fifth order polynomial stiffness nonlinearity, when the external force changes slowly with the variation of time. We exploit bifurcation characteristics of the fast subsystem using the slowly changing periodic excitation as a bifurcation parameter to show how the bursting oscillations are created in this model. We also identify that some regimes of bursting patterns are related to codimension two bifurcation type over a wide range of parameters. A subsequent two-parameter continuation reveals a transition in the bursting behavior from fold/fold hysteresis cycle to sup-Hopf/sup-Hopf or limit point cycle/sub-Hopf bursting type. Furthermore, the effects of external forcing item on bursting oscillations are investigated. For instance, the time interval between two adjacent spikes of bursting oscillations is dependent on the forcing frequency. Some numerical simulations are included to illustrate the validity of our study.





  • GNAR-GARCH model and its application in feature extraction for rolling bearing fault diagnosis
    22 février 2017
    Publication date: 1 September 2017
    Source:Mechanical Systems and Signal Processing, Volume 93

    Author(s): Jiaxin Ma, Feiyun Xu, Kai Huang, Ren Huang

    Given its simplicity of modeling and sensitivity to condition variations, time series model is widely used in feature extraction to realize fault classification and diagnosis. However, nonlinear and nonstationary characteristics common in fault signals of rolling bearing bring challenges to the diagnosis. In this paper, a hybrid model, the combination of a general expression for linear and nonlinear autoregressive (GNAR) model and a generalized autoregressive conditional heteroscedasticity (GARCH) model, (i.e., GNAR-GARCH), is proposed and applied to rolling bearing fault diagnosis. An exact expression of GNAR-GARCH model is given. Maximum likelihood method is used for parameter estimation and modified Akaike Information Criterion is adopted for structure identification of GNAR-GARCH model. The main advantage of this novel model over other models is that the combination makes the model suitable for nonlinear and nonstationary signals. It is verified with statistical tests that contain comparisons among the different time series models. Finally, GNAR-GARCH model is applied to fault diagnosis by modeling mechanical vibration signals including simulation and real data. With the parameters estimated and taken as feature vectors, k-nearest neighbor algorithm is utilized to realize the classification of fault status. The results show that GNAR-GARCH model exhibits higher accuracy and better performance than do other models.





  • Hybrid Evidence Theory-based Finite Element/Statistical Energy Analysis method for mid-frequency analysis of built-up systems with epistemic uncertainties
    22 février 2017
    Publication date: 1 September 2017
    Source:Mechanical Systems and Signal Processing, Volume 93

    Author(s): Shengwen Yin, Dejie Yu, Hui Yin, Hui Lü, Baizhan Xia

    Considering the epistemic uncertainties within the hybrid Finite Element/Statistical Energy Analysis (FE/SEA) model when it is used for the response analysis of built-up systems in the mid-frequency range, the hybrid Evidence Theory-based Finite Element/Statistical Energy Analysis (ETFE/SEA) model is established by introducing the evidence theory. Based on the hybrid ETFE/SEA model and the sub-interval perturbation technique, the hybrid Sub-interval Perturbation and Evidence Theory-based Finite Element/Statistical Energy Analysis (SIP-ETFE/SEA) approach is proposed. In the hybrid ETFE/SEA model, the uncertainty in the SEA subsystem is modeled by a non-parametric ensemble, while the uncertainty in the FE subsystem is described by the focal element and basic probability assignment (BPA), and dealt with evidence theory. Within the hybrid SIP-ETFE/SEA approach, the mid-frequency response of interest, such as the ensemble average of the energy response and the cross-spectrum response, is calculated analytically by using the conventional hybrid FE/SEA method. Inspired by the probability theory, the intervals of the mean value, variance and cumulative distribution are used to describe the distribution characteristics of mid-frequency responses of built-up systems with epistemic uncertainties. In order to alleviate the computational burdens for the extreme value analysis, the sub-interval perturbation technique based on the first-order Taylor series expansion is used in ETFE/SEA model to acquire the lower and upper bounds of the mid-frequency responses over each focal element. Three numerical examples are given to illustrate the feasibility and effectiveness of the proposed method.





  • Development and testing of an integrated smart tool holder for four-component cutting force measurement
    22 février 2017
    Publication date: 1 September 2017
    Source:Mechanical Systems and Signal Processing, Volume 93

    Author(s): Zhengyou Xie, Yong Lu, Jianguang Li

    Cutting force measurement is a significant requirement for monitoring and controlling the machining processes. Hence, various methods of measuring the cutting force have been proposed by many researchers. In this study, an innovative integrated smart tool holder system based on capacitive sensors is designed, constructed and tested, which is capable of measuring triaxial cutting force and a torque simultaneously in a wireless environment system. A standard commercial tool holder is modified to make itself be the force sensing element that has advantages of simple structure and easy machining. Deformable beams are created in the tool holder, and the tiny deformations of which used to calculate the four-component cutting force are detected by six high precision capacitive sensors. All the sensors and other electronics, like data acquisition and transmitting unit, and wireless power unit, are incorporated into the tool holder as a whole system. The device is intended to be used in a rotating spindle such as in milling and drilling processes. Eventually, the static and dynamic characteristics of the smart tool holder have been determined by a series of tests. Cutting tests have also been carried out and the results show it is stable and practical to measure the cutting force in milling and drilling processes.





  • Quasi-optical coherence vibration tomography technique for damage detection in beam-like structures based on auxiliary mass induced frequency shift
    22 février 2017
    Publication date: 1 September 2017
    Source:Mechanical Systems and Signal Processing, Volume 93

    Author(s): Shuncong Zhong, Jianfeng Zhong, Qiukun Zhang, Nuno Maia

    A novel quasi-optical coherence vibration tomography (Quasi-OCVT) measurement system suitable for structural damage detection is proposed by taking the concept of two-dimensional optical coherence vibration tomography (2D-OCVT) technique. An artificial quasi-interferogram fringe pattern (QIFP) similar to the interferogram of 2D-OCVT system, as a sensor, was pasted on the surface of a vibrating structure. Image sequences of QIFP were captured by a high-speed camera that worked as a detector. The period density of the imaged QIFP changed due to the structural vibration, from which the vibration information of the structure could be obtained. Noise influence on the measurement accuracy, torsional sensitivity and optical distortion effect of the Quasi-OCVT system were investigated. The efficiency and reliability of the proposed method were demonstrated by applying the system to damage detection of a cracked beam-like structure with a roving auxiliary mass. The roving of the mass along the cracked beam brings about the change of natural frequencies that could be obtained by the Quasi-OCVT technique. Therefore, frequency-shift curves can be achieved and these curves provide additional spatial information for structural damage detection. Same cases were also analyzed by the finite element method (FEM) and conventional accelerometer-based measurement method. Comparisons were carried out among these results. Results obtained by the proposed Quasi-OCVT method had a good agreement with the ones obtained by FEM, from which the damage could be directly detected. However, the results obtained by conventional accelerometer showed misleading ambiguous peaks at damage position owing to the mass effect on the structure, where the damage location cannot be identified confidently without further confirmation. The good performance of the cost-effective Quasi-OCVT method makes it attractive for vibration measurement and damage detection of beam-like structures.





  • Multi-faults decoupling on turbo-expander using differential-based ensemble empirical mode decomposition
    22 février 2017
    Publication date: 1 September 2017
    Source:Mechanical Systems and Signal Processing, Volume 93

    Author(s): Hongguang Li, Ming Li, Cheng Li, Fucai Li, Guang Meng

    This paper dedicates on the multi-faults decoupling of turbo-expander rotor system using Differential-based Ensemble Empirical Mode Decomposition (DEEMD). DEEMD is an improved version of DEMD to resolve the imperfection of mode mixing. The nonlinear behaviors of the turbo-expander considering temperature gradient with crack, rub-impact and pedestal looseness faults are investigated respectively, so that the baseline for the multi-faults decoupling can be established. DEEMD is then utilized on the vibration signals of the rotor system with coupling faults acquired by numerical simulation, and the results indicate that DEEMD can successfully decouple the coupling faults, which is more efficient than EEMD. DEEMD is also applied on the vibration signal of the misalignment coupling with rub-impact fault obtained during the adjustment of the experimental system. The conclusion shows that DEEMD can decompose the practical multi-faults signal and the industrial prospect of DEEMD is verified as well.





  • A unified approach for squeal instability analysis of disc brakes with two types of random-fuzzy uncertainties
    22 février 2017
    Publication date: 1 September 2017
    Source:Mechanical Systems and Signal Processing, Volume 93

    Author(s): Hui Lü, Wen-Ben Shangguan, Dejie Yu

    Automotive brake systems are always subjected to various types of uncertainties and two types of random-fuzzy uncertainties may exist in the brakes. In this paper, a unified approach is proposed for squeal instability analysis of disc brakes with two types of random-fuzzy uncertainties. In the proposed approach, two uncertainty analysis models with mixed variables are introduced to model the random-fuzzy uncertainties. The first one is the random and fuzzy model, in which random variables and fuzzy variables exist simultaneously and independently. The second one is the fuzzy random model, in which uncertain parameters are all treated as random variables while their distribution parameters are expressed as fuzzy numbers. Firstly, the fuzziness is discretized by using α-cut technique and the two uncertainty analysis models are simplified into random-interval models. Afterwards, by temporarily neglecting interval uncertainties, the random-interval models are degraded into random models, in which the expectations, variances, reliability indexes and reliability probabilities of system stability functions are calculated. And then, by reconsidering the interval uncertainties, the bounds of the expectations, variances, reliability indexes and reliability probabilities are computed based on Taylor series expansion. Finally, by recomposing the analysis results at each α-cut level, the fuzzy reliability indexes and probabilities can be obtained, by which the brake squeal instability can be evaluated. The proposed approach gives a general framework to deal with both types of random-fuzzy uncertainties that may exist in the brakes and its effectiveness is demonstrated by numerical examples. It will be a valuable supplement to the systematic study of brake squeal considering uncertainty.





  • Effect of model-form definition on uncertainty quantification in coupled models of mid-frequency range simulations
    22 février 2017
    Publication date: 1 September 2017
    Source:Mechanical Systems and Signal Processing, Volume 93

    Author(s): Kendra L. Van Buren, Morvan Ouisse, Scott Cogan, Emeline Sadoulet-Reboul, Laurent Maxit

    In the development of numerical models, uncertainty quantification (UQ) can inform appropriate allocation of computational resources, often resulting in efficient analysis for activities such as model calibration and robust design. UQ can be especially beneficial for numerical models with significant computational expense, such as coupled models, which require several subsystem models to attain the performance of a more complex, inter-connected system. In the coupled model paradigm, UQ can be applied at either the subsystem model level or the coupled model level. When applied at the subsystem level, UQ is applied directly to the physical input parameters, which can be computationally expensive. In contrast, UQ at the coupled level may not be representative of the physical input parameters, but comes at the benefit of being computationally efficient to implement. To be physically meaningful, analysis at the coupled level requires information about how uncertainty is propagated through from the subsystem level. Herein, the proposed strategy is based on simulations performed at the subsystem level to inform a covariance matrix for UQ performed at the coupled level. The approach is applied to a four-subsystem model of mid-frequency vibrations simulated using the Statistical Modal Energy Distribution Analysis, a variant of the Statistical Energy Analysis. The proposed approach is computationally efficient to implement, while simultaneously capturing information from the subsystem level to ensure the analysis is physically meaningful.





  • Nonlinear system stochastic response determination via fractional equivalent linearization and Karhunen–Loève expansion
    22 février 2017
    Publication date: August 2017
    Source:Communications in Nonlinear Science and Numerical Simulation, Volume 49

    Author(s): Hongzhe Dai, Zhibao Zheng, Wei Wang

    In this paper, a novel fractional equivalent linearization (EL) approach is developed by incorporating a fractional derivative term into the classical linearization equation. Due to the introduction of the fractional derivative term, the accuracy of the new linearization is improved, illustrated by a Duffing oscillator that is subjected to a harmonic excitation. Furthermore, a new method for solving stochastic response of nonlinear SDOF system is developed by combining Karhunen–Loève (K-L) expansion and fractional EL. The method firstly decomposes the stochastic excitation in terms of a set of random variables and deterministic sub-excitations using K-L expansion, and then construct sub-fractional equivalent linear system according to each sub-excitation by fractional EL, the response of the original nonlinear system is finally approximated as the weighed summation of the deterministic response of each sub-system multiplied by the corresponding random variable. The random nature of the final response comes from the set of random variables that is obtained in K-L expansion. In this way, the stochastic response computation is converted to a set of deterministic response analysis problems. The effectiveness of the developed method is demonstrated by a Duffing oscillator that is subjected to stochastic excitation modeled by Winner process. The results are compared with the numerical method and Monte Carlo simulation (MCS).





  • Advances in the clinical translation of nanotechnology
    22 février 2017
    Publication date: August 2017
    Source:Current Opinion in Biotechnology, Volume 46

    Author(s): David A Scheinberg, Jan Grimm, Daniel A Heller, Evan P Stater, Michelle Bradbury, Michael R McDevitt

    The use of novel materials in the nano-scale size range for applications in devices, drugs and diagnostic agents comes with a number of new opportunities, and also serious challenges to human applications. The larger size of particulate-based agents, as compared to traditional drugs, allows for the significant advantages of multivalency and multi-functionality. However, the human use of nanomaterials requires a thorough understanding of the biocompatibility of the synthetic molecules and their complex pharmacology. Possible toxicities created by the unusual properties of the nanoparticles are neither well-understood, nor predictable yet. A key to the successful use of the burgeoning field of nanomaterials as diagnostic and therapeutic agents will be to appropriately match the biophysical features of the particle to the disease system to be evaluated or treated.

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  • Low methoxyl pectin/sodium caseinate interactions and composite film formation at neutral pH
    22 février 2017
    Publication date: August 2017
    Source:Food Hydrocolloids, Volume 69

    Author(s): Noushin Eghbal, Pascal Degraeve, Nadia Oulahal, Mohammad Saeed Yarmand, Mohammad E. Mousavi, Adem Gharsallaoui

    The behavior of mixed negatively charged sodium caseinate (CAS) and low methoxyl pectin (LMP) at pH 7.0 was presented by phase diagram. The existence of interactions between CAS and LMP as a function of increasing protein concentration at neutral pH was studied by turbidity and zeta potential measurements. The observed significant increase of turbidity value for higher CAS/LMP ratios as well as the obtained zeta potential profile confirmed the formation of complexes at pH 7.0 at which the two macromolecules are negatively charged. Then, composite films were elaborated from CAS and LMP mixtures by increasing protein to polysaccharide ratio at neutral pH. The results revealed that the incorporation of protein to pectin-based films significantly increased the stiffness of films (Young’s modulus) and decreased their flexibility (p < 0.05). Water content of composite films decreased significantly as the concentration of CAS increased (p < 0.05) and reached its lowest value for CAS/LMP ratios of 2 and 5 (7.50 ± 0.10% and 7.63 ± 0.19%) compared to LMP film (19.82 ± 0.19%). The prepared films, having tunable properties by varying the ratio of CAS/LMP, seem to be adequate for the packaging of moist foods.

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  • Quantifying the consistency and rheology of liquid foods using fractional calculus
    22 février 2017
    Publication date: August 2017
    Source:Food Hydrocolloids, Volume 69

    Author(s): Caroline E. Wagner, Alexander C. Barbati, Jan Engmann, Adam S. Burbidge, Gareth H. McKinley

    It is well known that the perceived texture and consistency of liquid foods are strong drivers of consumer preference, yet quantification of these parameters is made complicated by the absence of a concise mathematical framework. In this paper, we demonstrate that fractional rheological models, including the fractional Maxwell model (FMM) and the fractional Jeffreys model (FJM), are potential candidates to fill this void as a result of their ability to succinctly and accurately predict the linear and nonlinear viscoelastic response of a range of liquid food solutions. These include a benchmark fluid, the dysphagia product Resource ® Thicken Up Clear, various plant extracts whose constituent polysaccharides have been reported to impart significant viscoelasticity, and human whole saliva. These fractional constitutive models quantitatively describe both the linear viscoelasticity of all of the liquid foods as well as the shear thinning of their steady shear viscosity (through application of the Cox-Merz rule), and outperform conventional multi-mode Maxwell models with up to 50 physical elements in terms of the goodness of fit to experimental data. Further, by accurately capturing the shear viscosity of the various liquid food solutions at the shear rate of γ ˙ = 50 s 1 (widely deemed relevant for oral evaluation of liquid texture), we show that two of the constitutive parameters of the fractional Maxwell model can be used to construct a state diagram that succinctly characterizes both the viscous and elastic properties of the different fluids. This characterization facilitates the assignment of quantitative values to largely heuristic food textural terms, which may improve the design of future liquid foods of specific desired consistencies or properties.

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  • Multiscale model reduction method for Bayesian inverse problems of subsurface flow
    22 février 2017
    Publication date: 1 August 2017
    Source:Journal of Computational and Applied Mathematics, Volume 319

    Author(s): Lijian Jiang, Na Ou

    This work presents a model reduction approach to the inverse problem in the application of subsurface flows. One such an application is to estimate model’s inputs and identify model’s parameters. This is often challenging because the complicated multiscale structures are inherent in the model and the estimated inputs are parameterized in a high-dimensional space. We often need to estimate the probabilistic distribution of the unknown inputs based on some observations. Bayesian inference is desirable for this situation and solving the inverse problem. For the Bayesian inverse problem, the forward model needs to be repeatedly computed for a large number of samplers to get a stationary chain. This requires large computational efforts. To significantly improve the computation efficiency, we use generalized multiscale finite element method and least-squares stochastic collocation method to construct a reduced computational model. To avoid the difficulty of choosing regularization parameter, hyperparameters are introduced to build a hierarchical model. We use truncated Karhunen–Loeve expansion (KLE) to reduce the dimension of the parameter spaces and decrease the mixed time of Markov chains. The techniques of hyperparameter and KLE are incorporated into the model reduction method. The reduced model is constructed offline. Then it is computed very efficiently in the online sampling stage. This strategy can significantly accelerate the evaluation of the Markov chain and the resultant posterior distribution converges fast. We analyze the convergence for the approximation between the posterior distribution by the reduced model and the reference posterior distribution by the full-order model. A few numerical examples in subsurface flows are carried out to demonstrate the performance of the presented model reduction method with application of the Bayesian inverse problem.





  • Eulerian finite element method for the numerical modeling of fluid dynamics of natural and pathological aortic valves
    22 février 2017
    Publication date: 1 August 2017
    Source:Journal of Computational and Applied Mathematics, Volume 319

    Author(s): Aymen Laadhari, Gábor Székely

    We present a finite element methodology tailored for the simulation of pulsatile flow in the full aorta and sinus of Valsalva interacting with highly deformable thin leaflets. We describe an extension of the so-called “Resistive Immersed Surface” method. To circumvent stability issues resulting from the bad conditioning of the linear system, especially when flow and geometry become complex after the inclusion of the aorta, we use a Lagrange multiplier technique that couples the dynamics of valve and flow. A banded level set variant allows to address the singularity of the resulting linear system while featuring, in addition to the parallel implementation, higher accuracy and an affordable computational burden. High-fidelity computational geometries are built and simulations are performed under physiological conditions. Several numerical experiments illustrate the ability of the model to capture the basic fluidic phenomena in both healthy and pathological configurations. We finally examine numerically the flow dynamics in the sinus of Valsalva after Transcatheter Aortic Valve Implantation. We show numerically that flow may be subject to stagnation in the lower part of the sinuses. We highlight the far-reaching implications of this phenomenon and we hope inciting adequate studies to further investigate its potential clinical consequences.

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  • A Discontinuous Extended Kalman Filter for non-smooth dynamic problems
    22 février 2017
    Publication date: August 2017
    Source:Mechanical Systems and Signal Processing, Volume 92

    Author(s): M.N. Chatzis, E.N. Chatzi, S.P. Triantafyllou

    Problems that result into locally non-differentiable and hence non-smooth state-space equations are often encountered in engineering. Examples include problems involving material laws pertaining to plasticity, impact and highly non-linear phenomena. Estimating the parameters of such systems poses a challenge, particularly since the majority of system identification algorithms are formulated on the basis of smooth systems under the assumption of observability, identifiability and time invariance. For a smooth system, an observable state remains observable throughout the system evolution with the exception of few selected realizations of the state vector. However, for a non-smooth system the observable set of states and parameters may vary during the evolution of the system throughout a dynamic analysis. This may cause standard identification (ID) methods, such as the Extended Kalman Filter, to temporarily diverge and ultimately fail in accurately identifying the parameters of the system. In this work, the influence of observability of non-smooth systems to the performance of the Extended and Unscented Kalman Filters is discussed and a novel algorithm particularly suited for this purpose, termed the Discontinuous Extended Kalman Filter (DEKF), is proposed.





  • Lateral-torsional response of base-isolated buildings with curved surface sliding system subjected to near-fault earthquakes
    22 février 2017
    Publication date: August 2017
    Source:Mechanical Systems and Signal Processing, Volume 92

    Author(s): Fabio Mazza

    The curved surface sliding (CSS) system is one of the most in-demand techniques for the seismic isolation of buildings; yet there are still important aspects of its behaviour that need further attention. The CSS system presents variation of friction coefficient, depending on the sliding velocity of the CSS bearings, while friction force and lateral stiffness during the sliding phase are proportional to the axial load. Lateral-torsional response needs to be better understood for base-isolated structures located in near-fault areas, where fling-step and forward-directivity effects can produce long-period (horizontal) velocity pulses. To analyse these aspects, a six-storey reinforced concrete (r.c.) office framed building, with an L-shaped plan and setbacks in elevation, is designed assuming three values of the radius of curvature for the CSS system. Seven in-plan distributions of dynamic-fast friction coefficient for the CSS bearings, ranging from a constant value for all isolators to a different value for each, are considered in the case of low- and medium-type friction properties. The seismic analysis of the test structures is carried out considering an elastic-linear behaviour of the superstructure, while a nonlinear force-displacement law of the CSS bearings is considered in the horizontal direction, depending on sliding velocity and axial load. Given the lack of knowledge of the horizontal direction at which near-fault ground motions occur, the maximum torsional effects and residual displacements are evaluated with reference to different incidence angles, while the orientation of the strongest observed pulses is considered to obtain average values.





  • Self-tuning pressure-feedback control by pole placement for vibration reduction of excavator with independent metering fluid power system
    22 février 2017
    Publication date: August 2017
    Source:Mechanical Systems and Signal Processing, Volume 92

    Author(s): Ruqi Ding, Bing Xu, Junhui Zhang, Min Cheng

    Independent metering control systems are promising fluid power technologies compared with traditional valve controlled systems. By breaking the mechanical coupling between the inlet and outlet, the meter-out valve can open as large as possible to reduce energy consumptions. However, the lack of damping in outlet causes strongervibrations. To address the problem, the paper designs a hybrid control method combining dynamic pressure-feedback and active damping control. The innovation resides in the optimization of damping by introducing pressure feedback to make trade-offs between high stability and fast response. To achieve this goal, the dynamic response pertaining to the control parameters consisting of feedback gain and cut-off frequency, are analyzed via pole-zero locations. Accordingly, these parameters are tuned online in terms of guaranteed dominant pole placement such that the optimal damping can be accurately captured under a considerable variation of operating conditions. The experiment is deployed in a mini-excavator. The results pertaining to different control parameters confirm the theoretical expectations via pole-zero locations. By using proposed self-tuning controller, the vibrations are almost eliminated after only one overshoot for different operation conditions. The overshoots are also reduced with less decrease of the response time. In addition, the energy-saving capability of independent metering system is still not affected by the improvement of controllability.





  • Wavelet-based spectral finite element dynamic analysis for an axially moving Timoshenko beam
    22 février 2017
    Publication date: August 2017
    Source:Mechanical Systems and Signal Processing, Volume 92

    Author(s): Ali Mokhtari, Hamid Reza Mirdamadi, Mostafa Ghayour

    In this article, wavelet-based spectral finite element (WSFE) model is formulated for time domain and wave domain dynamic analysis of an axially moving Timoshenko beam subjected to axial pretension. The formulation is similar to conventional FFT-based spectral finite element (SFE) model except that Daubechies wavelet basis functions are used for temporal discretization of the governing partial differential equations into a set of ordinary differential equations. The localized nature of Daubechies wavelet basis functions helps to rule out problems of SFE model due to periodicity assumption, especially during inverse Fourier transformation and back to time domain. The high accuracy of WSFE model is then evaluated by comparing its results with those of conventional finite element and SFE results. The effects of moving beam speed and axial tensile force on vibration and wave characteristics, and static and dynamic stabilities of moving beam are investigated.





  • Chaos vibration of pinion and rack steering trapezoidal mechanism containing two clearances
    22 février 2017
    Publication date: August 2017
    Source:Mechanical Systems and Signal Processing, Volume 92

    Author(s): Daogao Wei, Yu Wang, Tong Jiang, Sifa Zheng, Wenjing Zhao, Zhijie Pan

    The multi-clearances of breaking type steering trapezoidal mechanism joints influences vehicle steering stability. Hence, to ascertain the influence of clearance value on steering stability, this paper takes the steering mechanism of a certain vehicle type as a prototype that can be simplified into a planar six-bar linkage, then establishes the system dynamic differential equations after considering the two clearances of tie rods and the steering knuckle arms. The influence of the clearance parameters on the movement stability of the steering mechanism is studied using a numerical computation method. Results show that when the two clearances are equal, the planar movement of the tie rods changes from period-doubling to chaos as the clearances increase. When the two clearances are 0.25mm and 1.5mm respectively, the planar movements of the two side tie rods come into chaos, causing the steering stability to deteriorate. Moreover, with the increase of clearances, turning moment fluctuates more intensively and the peak value increases.





  • A new Gibbs sampling based algorithm for Bayesian model updating with incomplete complex modal data
    22 février 2017
    Publication date: August 2017
    Source:Mechanical Systems and Signal Processing, Volume 92

    Author(s): Sai Hung Cheung, Sahil Bansal

    Model updating using measured system dynamic response has a wide range of applications in system response evaluation and control, health monitoring, or reliability and risk assessment. In this paper, we are interested in model updating of a linear dynamic system with non-classical damping based on incomplete modal data including modal frequencies, damping ratios and partial complex mode shapes of some of the dominant modes. In the proposed algorithm, the identification model is based on a linear structural model where the mass and stiffness matrix are represented as a linear sum of contribution of the corresponding mass and stiffness matrices from the individual prescribed substructures, and the damping matrix is represented as a sum of individual substructures in the case of viscous damping, in terms of mass and stiffness matrices in the case of Rayleigh damping or a combination of the former. To quantify the uncertainties and plausibility of the model parameters, a Bayesian approach is developed. A new Gibbs-sampling based algorithm is proposed that allows for an efficient update of the probability distribution of the model parameters. In addition to the model parameters, the probability distribution of complete mode shapes is also updated. Convergence issues and numerical issues arising in the case of high-dimensionality of the problem are addressed and solutions to tackle these problems are proposed. The effectiveness and efficiency of the proposed method are illustrated by numerical examples with complex modes.





  • Agglomerative concentric hypersphere clustering applied to structural damage detection
    22 février 2017
    Publication date: August 2017
    Source:Mechanical Systems and Signal Processing, Volume 92

    Author(s): Moisés Silva, Adam Santos, Reginaldo Santos, Eloi Figueiredo, Claudomiro Sales, João C.W.A. Costa

    The present paper proposes a novel cluster-based method, named as agglomerative concentric hypersphere (ACH), to detect structural damage in engineering structures. Continuous structural monitoring systems often require unsupervised approaches to automatically infer the health condition of a structure. However, when a structure is under linear and nonlinear effects caused by environmental and operational variability, data normalization procedures are also required to overcome these effects. The proposed approach aims, through a straightforward clustering procedure, to discover automatically the optimal number of clusters, representing the main state conditions of a structural system. Three initialization procedures are introduced to evaluate the impact of deterministic and stochastic initializations on the performance of this approach. The ACH is compared to state-of-the-art approaches, based on Gaussian mixture models and Mahalanobis squared distance, on standard data sets from a post-tensioned bridge located in Switzerland: the Z-24 Bridge. The proposed approach demonstrates more efficiency in modeling the normal condition of the structure and its corresponding main clusters. Furthermore, it reveals a better classification performance than the alternative ones in terms of false-positive and false-negative indications of damage, demonstrating a promising applicability in real-world structural health monitoring scenarios.





  • Two methods for modeling vibrations of planetary gearboxes including faults: Comparison and validation
    22 février 2017
    Publication date: August 2017
    Source:Mechanical Systems and Signal Processing, Volume 92

    Author(s): J. Parra, Cristián Molina Vicuña

    Planetary gearboxes are important components of many industrial applications. Vibration analysis can increase their lifetime and prevent expensive repair and safety concerns. However, an effective analysis is only possible if the vibration features of planetary gearboxes are properly understood. In this paper, models are used to study the frequency content of planetary gearbox vibrations under non-fault and different fault conditions. Two different models are considered: phenomenological model, which is an analytical-mathematical formulation based on observation, and lumped-parameter model, which is based on the solution of the equations of motion of the system. Results of both models are not directly comparable, because the phenomenological model provides the vibration on a fixed radial direction, such as the measurements of the vibration sensor mounted on the outer part of the ring gear. On the other hand, the lumped-parameter model provides the vibrations on the basis of a rotating reference frame fixed to the carrier. To overcome this situation, a function to decompose the lumped-parameter model solutions to a fixed reference frame is presented. Finally, comparisons of results from both model perspectives and experimental measurements are presented.





  • Damage identification of beam structures using free response shapes obtained by use of a continuously scanning laser Doppler vibrometer system
    22 février 2017
    Publication date: August 2017
    Source:Mechanical Systems and Signal Processing, Volume 92

    Author(s): Y.F. Xu, Da-Ming Chen, W.D. Zhu

    Spatially dense operating deflection shapes and mode shapes can be rapidly obtained by use of a continuously scanning laser Doppler vibrometer (CSLDV) system, which sweeps its laser spot over a vibrating structure surface. This paper introduces a new type of vibration shapes called a free response shape (FRS) that can be obtained by use of a CSLDV system, and a new damage identification methodology using FRSs is developed for beam structures. An analytical expression of FRSs of a damped beam structure is derived, and FRSs from the analytical expression compare well with those from a finite element model. In the damage identification methodology, a free-response damage index (FRDI) is proposed, and damage regions can be identified near neighborhoods with consistently high values of FRDIs associated with different modes; an auxiliary FRDI is defined to assist identification of the neighborhoods. A FRDI associated with a mode consists of differences between curvatures of FRSs associated with the mode in a number of half-scan periods of a CSLDV system and those from polynomials that fit the FRSs with properly determined orders. A convergence index is proposed to determine the proper order of a polynomial fit. One advantage of the methodology is that the FRDI does not require any baseline information of an undamaged beam structure, if it is geometrically smooth and made of materials that have no stiffness and mass discontinuities. Another advantage is that FRDIs associated with multiple modes can be obtained using free response of a beam structure measured by a CSLDV system in one scan. The number of half-scan periods for calculation of the FRDI associated with a mode can be determined by use of the short-time Fourier transform. The proposed methodology was numerically and experimentally applied to identify damage in beam structures; effects of the scan frequency of a CSLDV system on qualities of obtained FRSs were experimentally investigated.





  • Multi-objective optimization design of a high-speed PM machine supported by magnetic bearings
    22 février 2017
    Publication date: August 2017
    Source:Mechanical Systems and Signal Processing, Volume 92

    Author(s): Bangcheng Han, Qinghao Xue, Xu Liu, Kun Wang

    This paper proposes an optimal design method of permanent magnet machine (PMM) with cylindrical permanent magnet supported by magnetic bearings. The objectives of optimization design are minimizing the rotor loss while maximizing the power density of the PMM as well as the 1st order nature frequency of the rotor, and the constraints are size, the strength safety factor and the phase current. A 30kW, 48,000r/min PMM designed by the multi-objective optimization method is proposed and the results indicate: the rotor loss is decreased from 393W to 290W (is reduced by 26.2%); the power density of the PMM is increased from 1.86kW/kg to 2.19kW/kg (is increased by 17.7%); the 1st order nature frequency of the rotor is increased from 1579Hz to 1812Hz (is increased by 14.7%). The performances of the PMM are improved after optimization, which are verified by experiment.





  • Parameter sensitivity analysis of a 5-DoF parallel manipulator
    22 février 2017
    Publication date: August 2017
    Source:Robotics and Computer-Integrated Manufacturing, Volume 46

    Author(s): Binbin Lian, Tao Sun, Yimin Song

    With the capability of determining main/subordinate parameters, parameter sensitivity analysis plays an important role in eliminating unimportant parameters and simplifying performance analysis and optimization model. Taking a 5 degree-of-freedom parallel manipulator (T5 PM) as an example, the effects of joint stiffness/compliance coefficients and parameters of cross section to the mass and stiffness performance are investigated through parameter sensitivity analysis based on response surface method and performance reliability. By selecting experimental strategy and implementing accuracy assessment, the response surface method is adopted to establish the mapping model of parameters and performance with high efficiency and accuracy. In the light of reliability sensitivity, the performance reliability to parameter mean value and variance are simultaneously considered by the global parameter sensitivity index, which is the principle for determining the impact extent of parameters. Moreover, how the parameters affect the targeted performance can be evaluated through RSAV, RSPC and RSNC defined by the performance reliability to the parameter mean value. After verifying the sensitivity analysis approach by SolidWorks simulation, the parameter discussion of T5 PM is carried out. 15 parameters are selected from the original 39 parameters and effects of these parameters are clearly demonstrated, which provide reference for the future optimization process.





  • Sensorless model-based object-detection applied on an underactuated adaptive hand enabling an impedance behavior
    22 février 2017
    Publication date: August 2017
    Source:Robotics and Computer-Integrated Manufacturing, Volume 46

    Author(s): M. Beschi, E. Villagrossi, L. Molinari Tosatti, D. Surdilovic

    This paper introduces a sensorless object-detection control strategy designed for an underactuated three fingers hand. The proposed algorithm achieves a very accurate object-detection, through a simple joint impedance control scheme combined with a state-observer. The joint impedance control adapts the position set-point of each finger according to the estimated kinematics state computed from the kinematics model of the finger. The additional control loop is applied as external controller w.r.t. the standard one. The object-detection is obtained without any external sensors using only the measures of position and current provided by the fingers actuators. A friction compensation strategy based on a probabilistic approach has been implemented. An impedance control algorithm avoids the tuning of grasping parameters (i.e. grasping velocity and holding force). In this way developed controller provides adaptive behavior enabling the manipulation of objects made by unknown materials, without producing damages on their surfaces. This approach represents a step ahead to the flexibility of the grasping devices, in particular in manufacturing production, where the variability of manipulated pieces, in terms of shape and materials can be very high. An experimental campaign demonstrates the feasibility of the proposed method.





  • Dynamic performance analysis of the X4 high-speed pick-and-place parallel robot
    22 février 2017
    Publication date: August 2017
    Source:Robotics and Computer-Integrated Manufacturing, Volume 46

    Author(s): Jiao Mo, Zhu-Feng Shao, Liwen Guan, Fugui Xie, Xiaoqiang Tang

    With the closed-loop structure, parallel manipulators possess some inherent advantages, such as high stiffness, enhanced dynamics, and compact structure. As a result, parallel manipulators gradually gain wide application. In the great variety of parallel manipulators, a kind of high-speed parallel robot, the limb of which is composed of active pendulum and passive parallelogram, gets popular and has realized industrial application firstly. Dynamic performance is the core of the high-speed parallel manipulator, which is usually illustrated through dynamic performance analysis with the aid of the index. Thus, developing reasonable dynamic performance indices is of great theoretical and practical significance for the high-speed parallel manipulator. In this paper, the Coefficient of Variation of joint-space Inertia (CVI) index is proposed to illustrate the acceleration consistency of each limb of the parallel manipulator. By taking the X4 high-speed pick-and-place parallel manipulator as object, the dynamic model and joint-space inertia matrix is established, and the dynamic performance analysis is carried out with the proposed CVI index and the existing Joint-Reflected Inertia (JRI) index. Simulation results illustrate changes of the dynamic performance of the X4 parallel manipulator, and reveal that the JRI index is well complemented with the CVI index. Finally, the workspace with good dynamic performance is discussed. This paper provides a new approach for dynamic analysis and optimal design of high-speed parallel manipulator.





  • Stiffness analysis of parallel manipulators with linear limbs by considering inertial wrench of moving links and constrained wrench
    22 février 2017
    Publication date: August 2017
    Source:Robotics and Computer-Integrated Manufacturing, Volume 46

    Author(s): Yi Lu, Zhuohong Dai, Nijia Ye

    A stiffness of the parallel manipulators with linear limbs is analyzed by considering the inertial wrench of the moving links and the constrained wrench. First, a formula is derived for solving the dynamic active and constrained wrenches, the inertial wrench of moving links based on the principle of virtual work. Second, the relationship between the elastic deformations of limbs and the dynamic active/constrained wrench and the inertial wrench of moving links are discovered and analyzed. Third, a unified stiffness model of parallel manipulators is established by considering the inertial wrench of moving links and the dynamic active/constrained wrench. Fourth, a unified formula is derived for solving the elastic deformations of the moving platform by considering the inertial wrench of the moving links and the dynamic active/constrained wrenches. Finally, an analytic numerical example of the 3SPR-type parallel manipulator is given for solving its stiffness and elastic deformation. The correctness of derived formulae of the stiffness and the elastic deformations are verified by the analytic numerical solutions.





  • Modeling and design optimization of a robot gripper mechanism
    22 février 2017
    Publication date: August 2017
    Source:Robotics and Computer-Integrated Manufacturing, Volume 46

    Author(s): Alaa Hassan, Mouhammad Abomoharam

    Structure modeling and optimizing are important topics for the design and control of robots. In this paper, we propose a process for modeling robots and optimizing their structure. This process is illustrated via a case study of a robot gripper mechanism that has a closed-loop and a single degree of freedom (DOF) structure. Our aim is to conduct a detailed study of the gripper in order to provide an in-depth step-by-step demonstration of the design process and to illustrate the interactions among its steps. First, geometric model is established to find the relationship between the operational coordinates giving the location of the end-effector and the joint coordinates. Then, equivalent Jacobian matrix is derived to find the kinematic model; and the dynamic model is obtained using Lagrange formulation. Based on these models, a structural multi-objective optimization (MOO) problem is formalised in the static configuration of the gripper. The objective is to determine the optimum force extracted by the robot gripper on the surface of a grasped rigid object under geometrical and functional constraints. The optimization problem of the gripper design is solved using a non-dominated sorting genetic algorithm version II (NSGA-II). The Pareto-optimal solutions are investigated to establish some meaningful relationships between the objective functions and variable values. Finally, design sensitivity analysis is carried out to compute the sensitivity of objective functions with respect to design variables.





  • Minimizing the influence of revolute joint clearance using the planar redundantly actuated mechanism
    22 février 2017
    Publication date: August 2017
    Source:Robotics and Computer-Integrated Manufacturing, Volume 46

    Author(s): Xuchong Zhang, Xianmin Zhang

    Joint clearance is unavoidable in real mechanism, so its effects should be minimized in order to fulfill the designed performances of the mechanism. In this paper, we proposed a method which is based on the redundantly actuated mechanism to minimize the influence of revolute joint clearance. A planar 3DOF redundantly actuated 4-RRR mechanism with 8 clearance joints is applied as an illustration to show how it works. Firstly, the kinematic and dynamic equations of the 4-RRR mechanism are established. Secondly, the joint clearance is geometrically described and the contact force models are introduced. After that, the joint clearances are restrained by preloading the passive links of the 4-RRR mechanism, the two-step Bathe integration method is used to solve these equations. Comparisons are made between the mechanisms with and without clearance restrain. Finally, experiments are carried out to verify the proposed method. Both simulation and experimental results show that the joint clearance can be successfully controlled by the redundantly actuated mechanism.





  • An automated in-situ alignment approach for finish machining assembly interfaces of large-scale components
    22 février 2017
    Publication date: August 2017
    Source:Robotics and Computer-Integrated Manufacturing, Volume 46

    Author(s): Pei Lei, Lianyu Zheng

    Alignment is a crucial issue for finish machining the assembly interfaces of a large-scale component before final assembly in the aviation industry, as it affects the distribution of machining allowance and is time and effort consuming in the current manual way. This study presents an automated and in-situ alignment approach with the assistance of computer numerical controlled (CNC) positioners and laser trackers. The aligning process mainly consists of three steps, that is, measurement, posture evaluation, and posture adjustment. For measuring using laser tracker, a closed-loop method is proposed to establish a global reference frame (GRF) on the shop floor to unify measuring results from multi-stations based on the machine tool coordinate system. Therefore, the large-scale component is aligned to the machine tool as long as it is adjusted to the nominal posture in the GRF. As regards posture evaluation, the key characteristics (KCs) of the large-scale component are considered in the evaluation process based on the geometrical meaning of the singular value decomposition (SVD) to reduce the residual error of the KC with higher importance. An in-process calibration method is proposed during the adjustment process to calculate the actual position of the sphere hinge center and avoid the alignment accuracy loss in the kinematic backward transformation. A vertical tail of a certain large passenger aircraft is then used to validate the proposed alignment system and methods. The experimental results show that: (1) the GRF is accurately established on the shop floor; (2) the proposed posture evaluation algorithm enhances the transformation accuracy of the KC with greater importance; (3) the center position of the sphere hinge is calibrated, such that it hardly affects the alignment accuracy; and (4) the large component is aligned to the machine tool, satisfying all the tolerance requirements.





  • Three-dimensional free vibrations analysis of functionally graded rectangular plates by the meshless local Petrov–Galerkin (MLPG) method
    22 février 2017
    Publication date: 1 July 2017
    Source:Applied Mathematics and Computation, Volume 304

    Author(s): M. Rashidi Moghaddam, G.H. Baradaran

    In this paper, the meshless local Petrov–Galerkin (MLPG) method is used for three-dimensional (3D) elastodynamic analysis of functionally graded (FG) isotropic plates. The 3D linear elasticity theory and infinitesimal strains are the basic assumptions in this analysis. Unlike 2-D theories, in 3D theory, no restricting assumptions are made about the kinematics of deformation in plates. Therefore, a higher accuracy can be achieved by using 3D theory. Heaviside step functions are used as test functions on the local sub-domain of each node and the field variables are interpolated using the 3D moving least squares (MLS) approximation. To impose the essential boundary conditions, the penalty method is adopted and Young's modulus is assumed to be graded through the thickness of plates by the Mori–Tanaka estimation and Poisson's ratio is assumed to be constant. The natural frequencies of thick rectangular plates are obtained for different boundary conditions. Also, the effects of different parameters such as functionally graded power law index, thickness-to-length ratio, and the aspect ratio on the natural frequencies of plates are also studied in details. In order to validate this method, the results are compared with the available exact 3D solutions. The results show the accuracy and effectiveness of the present method.





  • Bifurcations of periodic motion in a three-degree-of-freedom vibro-impact system with clearance
    22 février 2017
    Publication date: July 2017
    Source:Communications in Nonlinear Science and Numerical Simulation, Volume 48

    Author(s): Yongbao Liu, Qiang Wang, Huidong Xu

    The smooth bifurcation and grazing non-smooth bifurcation of periodic motion of a three-degree-of-freedom vibro-impact system with clearance are studied in this paper. Firstly, a periodic solution of vibro-impact system is solved and a six-dimensional Poincaré map is established. Then, for the six-dimensional Poincaré map, the analytic expressions of all eigenvalues of Jacobi matrix with respect to parameters are unavailable. This implies that with application of the classical critical criterion described by the properties of eigenvalues, we have to numerically compute eigenvalues point by point and check their properties to search for the bifurcation points. Such the numerical calculation is a laborious job in the process of determining bifurcation points. To overcome the difficulty that originates from the classical bifurcation criteria, the explicit critical criteria without using eigenvalues calculation of high-dimensional map are applied to determine bifurcation points of Co-dimension-one period doubling bifurcation and Co-dimension-one Neimark–Sacker bifurcation and Co-dimension-two Flip–Neimark–Sacker bifurcation, and then local dynamical behaviors of these bifurcations are analyzed. Moreover, the directions of period doubling bifurcation and Neimark–Sacker bifurcation are analyzed by center manifold reduction theory and normal form approach. Finally, the existence of the grazing periodic motion of the vibro-impact system is analyzed and the grazing bifurcation point is obtained, the discontinuous grazing bifurcation behavior is studied based on the compound normal form map near the grazing point, the discontinuous jumping phenomenon and co-existing multiple solutions near the grazing bifurcation point are revealed.





  • Fractional viscoelastic beam under torsion
    22 février 2017
    Publication date: July 2017
    Source:Communications in Nonlinear Science and Numerical Simulation, Volume 48

    Author(s): N. Colinas-Armijo, S. Cutrona, M. Di Paola, A. Pirrotta

    This paper introduces a study on twisted viscoelastic beams, having considered fractional calculus to capture the viscoelastic behaviour. Further another novelty of this paper is extending a recent numerical approach, labelled line elementless method (LEM), to viscoelastic beams. The latter does not require any discretization neither in the domain nor in the boundary. Some numerical applications have been reported to demonstrate the efficiency and accuracy of the method.





  • Vibrational energy harvesting by exploring structural benefits and nonlinear characteristics
    22 février 2017
    Publication date: July 2017
    Source:Communications in Nonlinear Science and Numerical Simulation, Volume 48

    Author(s): Chongfeng Wei, Xingjian Jing

    Traditional energy harvesters are often of low efficiency due to very limited energy harvesting bandwidth, which should also be enough close to the ambient excitation frequency. To overcome this difficulty, some attempts can be seen in the literature typically with the purposes of either increasing the energy harvesting bandwidth with a harvester array, or enhancing the energy harvesting bandwidth and peak with nonlinear coupling effect etc. This paper presents an alternative way which can achieve tuneable resonant frequency (from high frequency to ultralow frequency) and improved energy harvesting bandwidth and peak simultaneously by employing special structural benefits and advantageous displacement-dependent nonlinear damping property. The proposed energy harvesting system employs a lever systems combined with an X-shape supporting structure and demonstrates very adjustable stiffness and unique nonlinear damping characteristics which are very beneficial for energy harvesting. It is shown that the energy harvesting performance of the proposed system is directly determined by several easy-to-tune structural parameters and also by the relative displacement in a special nonlinear manner, which provides a great flexibility and/or a unique tool for tuning and improving energy harvesting efficiency via matching excitation frequencies and covering a broader frequency band. This study potentially provides a new insight into the design of energy harvesting systems by employing structural benefits and geometrical nonlinearities.





  • Turing pattern formation on the sphere for a morphochemical reaction-diffusion model for electrodeposition
    22 février 2017
    Publication date: July 2017
    Source:Communications in Nonlinear Science and Numerical Simulation, Volume 48

    Author(s): Deborah Lacitignola, Benedetto Bozzini, Massimo Frittelli, Ivonne Sgura

    The present paper deals with the pattern formation properties of a specific morpho-electrochemical reaction-diffusion model on a sphere. The physico-chemical background to this study is the morphological control of material electrodeposited onto spherical particles. The particular experimental case of interest refers to the optimization of novel metal-air flow batteries and addresses the electrodeposition of zinc onto inert spherical supports. Morphological control in this step of the high-energy battery operation is crucial to the energetic efficiency of the recharge process and to the durability of the whole energy-storage device. To rationalise this technological challenge within a mathematical modeling perspective, we consider the reaction-diffusion system for metal electrodeposition introduced in [Bozzini et al., J. Solid State Electr.17, 467–479 (2013)] and extend its study to spherical domains. Conditions are derived for the occurrence of the Turing instability phenomenon and the steady patterns emerging at the onset of Turing instability are investigated. The reaction-diffusion system on spherical domains is solved numerically by means of the Lumped Surface Finite Element Method (LSFEM) in space combined with the IMEX Euler method in time. The effect on pattern formation of variations in the domain size is investigated both qualitatively, by means of systematic numerical simulations, and quantitatively by introducing suitable indicators that allow to assign each pattern to a given morphological class. An experimental validation of the obtained results is finally presented for the case of zinc electrodeposition from alkaline zincate solutions onto copper spheres.





  • Numerical prediction of the creep behaviour of an unstabilised and a chemically stabilised soft soil
    22 février 2017
    Publication date: July 2017
    Source:Computers and Geotechnics, Volume 87

    Author(s): Paulo J. Venda Oliveira, António A.S. Correia, Luís J.L. Lemos

    This paper examines the ability of volumetric and deviatoric creep laws associated with constitutive models to simulate the creep behaviour of a soft soil in its natural state or chemically stabilised state. Initially, the models/laws are validated by oedometer and triaxial creep tests, for the stabilised and unstabilised soils. Finally, the long-term behaviour of an embankment built on a soft soil reinforced with deep mixing columns is predicted based on the properties for a curing time of 28days. The results show that the creep phenomenon should be considered in a long-term analysis of deep mixing columns.





  • Parameters controlling pressure and fracture behaviors in field injectivity tests: A numerical investigation using coupled flow and geomechanics model
    22 février 2017
    Publication date: July 2017
    Source:Computers and Geotechnics, Volume 87

    Author(s): Yongcun Feng, K.E. Gray

    Field injectivity tests are widely used in the oil and gas industry to obtain key formation characteristics. The prevailing approaches for injectivity test interpretation rely on traditional analytical models. A number of parameters may affect the test results and lead to interpretation difficulties. Understanding their impacts on pressure response and fracture geometry of the test is essential for accurate test interpretation. In this work, a coupled flow and geomechanics model is developed for numerical simulation of field injectivity tests. The coupled model combines a cohesive zone model for simulating fluid-driven fracture and a poro-elastic/plastic model for simulating formation behavior. The model can capture fracture propagation, fluid flow within the fracture and formation, deformation of the formation, and evolution of pore pressure and stress around the wellbore and fracture during the tests. Numerical simulations are carried out to investigate the impacts of a multitude of parameters on test behaviors. The parameters include rock permeability, the leak-off coefficient of the fracture, rock stiffness, rock toughness, rock strength, plasticity deformation, and injection rate. The sensitivity of pressure response and fracture geometry on each parameter is reported and discussed. The coupled flow and geomechanics model provides additional advantages in the understanding of the fundamental mechanisms of field injectivity tests.





  • A full 3D rigid block model for the collapse behaviour of masonry walls
    22 février 2017
    Publication date: July–August 2017
    Source:European Journal of Mechanics - A/Solids, Volume 64

    Author(s): Daniele Baraldi, Antonella Cecchi

    This paper presents and validates a non-commercial rigid block model code for performing pushover analysis of one leaf masonry assemblages with regular texture, in three dimensional field. Hypotheses of rigid blocks and joints modelled as interfaces are adopted for representing historic masonry behaviour, characterized by dry joints or weak mortar joints having negligible size with respect to block size. Masonry elastic and inelastic behaviour is concentrated at joints by defining their normal, shear, bending and torsion stiffness and strength, adopting a Mohr-Coulomb criterion for restraining interface actions. The proposed model is an extension to the field of material nonlinearity of an existing code, moreover nonlinear analyses follow an effective approach introduced by authors for the in-plane case, based on the determination and update of the stiffness matrix of the masonry assemblage during the incremental analysis, accounting for damage. A numerical experimentation is performed for determining limit load multipliers and collapse mechanisms of several masonry walls subject to in-plane actions generated by self-weight and out-of-plane actions that may cause tilting or toppling of masonry assemblage portions. Dry and mortar joints are considered and existing case studies are adopted for calibrating the proposed model and evaluating its effectiveness.





  • Vibrating nonlocal multi-nanoplate system under inplane magnetic field
    22 février 2017
    Publication date: July–August 2017
    Source:European Journal of Mechanics - A/Solids, Volume 64

    Author(s): Danilo Karličić, Milan Cajić, Sondipon Adhikari, Predrag Kozić, Tony Murmu

    The recent development in nanotechnology resulted in growing of various nanoplate like structures. High attention was devoted to graphene sheet nanostructure, which enforced the scientist to start developing various theoretical models to investigate its physical properties. Magnetic field effects on nanoplates, especially graphene sheets, have also attracted a considerable attention of the scientific community. Here, by using the nonlocal theory, we examine the influence of in-plane magnetic field on the viscoelastic orthotropic multi-nanoplate system (VOMNPS) embedded in a viscoelastic medium. We derive the system of m partial differential equations describing the free transverse vibration of VOMNPS under the uniaxial in-plane magnetic field using the Eringen's nonlocal elasticity and Kirchhoff's plate theory considering the viscoelastic and orthotropic material properties of nanoplates. Closed form solutions for complex natural frequencies are derived by applying the Navier's and trigonometric method for the case of simply supported nanoplates. The results obtained with analytical method are validated with the results obtained by using the numerical method. In addition, numerical examples are given to show the effects of nonlocal parameter, internal damping, damping and stiffness of viscoelastic medium, rotary inertia and uniaxial in-plane magnetic force on the real and the imaginary parts of complex natural frequencies of VOMNPS. This study can be useful as a starting point for the research and design of nanoelectromechanical devices based on graphene sheets.

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  • Assisted crack tip flipping under Mode I thin sheet tearing
    22 février 2017
    Publication date: July–August 2017
    Source:European Journal of Mechanics - A/Solids, Volume 64

    Author(s): C.L. Felter, K.L. Nielsen

    Crack tip flipping, where the fracture surface alternates from side to side in roughly 45° shear bands, seems to be an overlooked propagation mode in Mode I thin sheet tearing. In fact, observations of crack tip flipping is rarely found in the literature. Unlike the already established modes such as slanting, cup-cone (rooftop), or cup-cup (bathtub) the flipping crack never settles in a steady-state as the near tip stress/strain field continuously change when the flip successively initiates and develops shear-lips. A recent experimental investigation has revealed new insight by exploiting 3D X-ray tomography scanning of a developing crack tip flip. But, it remains to be understood what makes the crack flip systematically, what sets the flipping frequency, and under which material conditions this mode occurs. The present study aims at investigating the idea that a slight out-of-plane action (Mode III type loading) on the tip of a slant Mode I crack can provoke it to flip to the opposite side. Both experiments and micro-mechanics based modeling support this hypothesis.





  • Multiscale modeling of regularly staggered carbon fibers embedded in nano-reinforced composites
    22 février 2017
    Publication date: July–August 2017
    Source:European Journal of Mechanics - A/Solids, Volume 64

    Author(s): S.I. Kundalwal, S.A. Meguid

    This article deals with the multiscale modeling of stress transfer characteristics of nano-reinforced polymer composite reinforced with regularly staggered carbon fibers. The distinctive feature of construction of nano-reinforced composite is such that the microscale carbon fibers are packed in hexagonal array in the carbon nanotube reinforced polymer matrix (CNRP). We considered three different cases of CNRP, in which carbon nanotubes (CNTs) are: (i) aligned along the direction of carbon fiber, (ii) aligned radially to the axis of carbon fiber, and (iii) randomly dispersed. Accordingly, multiscale models were developed. First, molecular dynamics (MD) simulations and then Mori-Tanaka technique were used to estimate the effective elastic properties of CNRP. Second, a micromechanical three-phase shear lag model was developed considering the staggering effect of microscale fibers and the application of radial loads on the cylindrical representative volume element (RVE) of nano-reinforced composite. Our results reveal that the stress transfer characteristics of the nano-reinforced composite are significantly improved by controlling the CNT morphology, particularly, when they are randomly dispersed around the microscale fiber. The results from the developed shear lag model were also validated with the finite element shear lag simulations and found to be in good agreement.





  • Stress estimates for particle damage in Fe-TiB2 metal matrix composites from experimental data and simulation
    22 février 2017
    Publication date: July–August 2017
    Source:European Journal of Mechanics - A/Solids, Volume 64

    Author(s): M. Gaspérini, M. Dammak, P. Franciosi

    Experimental data regarding microstructural damage evolution in Fe-TiB2 composites are examined in order to estimating the fracture stress of the TiB2 particles in relation to their size distribution. At first, an a priori “on/off” particle breaking mode is introduced in a numerical modelling based on nonlinear homogenization methods, considering a three (matrix plus undamaged and damaged particles) phase assemblage. Specific effects on the stress estimates in the particles and on the damage evolution, due to particle shape and elasticity anisotropy, to matrix grain size and hardening, as well as to the loading mode, are examined in comparison with a reference estimate from a fully isotropic description of the undamaged material. The firstly assumed “on/off” brutal particle damage description is shown to overestimate both the damage-induced porosity in the material and the matrix hardening. Both are then adjusted with the available data using a much lower and gradual decrease of the TiB2 particle stiffness from the undamaged state. From these adjustments, estimates of the size-related particle fracture stresses are obtained. Particle fracturing occurs with limited and gradual stiffness loss of the composite, consistently with a quite good bonding of the TiB2 particles with the surrounding ferrite matrix.





  • Fast simulation of the pantograph–catenary dynamic interaction
    22 février 2017
    Publication date: July 2017
    Source:Finite Elements in Analysis and Design, Volume 129

    Author(s): S. Gregori, M. Tur, E. Nadal, J.V. Aguado, F.J. Fuenmayor, F. Chinesta

    Simulation of the pantograph–catenary dynamic interaction has now become a useful tool for designing and optimizing the system. In order to perform accurate simulations, including system non-linearities, the Finite Element Method is commonly employed combined with a time integration scheme, even though the computational time required may be longer than with the use of other simpler approaches. In this paper we propose a two-stage methodology (Offline/Online) which notably reduces the computational cost without any loss in accuracy and makes it possible to successfully carry out very efficient optimizations or even Hardware in the Loop simulations with real-time requirements.








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  • A bio-statistical mining approach for classifying multivariate clinical time series data observed at irregular intervals
    22 février 2017
    Publication date: 15 July 2017
    Source:Expert Systems with Applications, Volume 78

    Author(s): Jane Y. Nancy, Nehemiah H. Khanna, Arputharaj Kannan

    In medical information system, the data that describe patient health records are often time stamped. These data are liable to complexities such as missing data, observations at irregular time intervals and large attribute set. Due to these complexities, mining in clinical time-series data, remains a challenging area of research. This paper proposes a bio-statistical mining framework, named statistical tolerance rough set induced decision tree (STRiD), which handles these complexities and builds an effective classification model. The constructed model is used in developing a clinical decision support system (CDSS) to assist the physician in clinical diagnosis. The STRiD framework provides the following functionalities namely temporal pre-processing, attribute selection and classification. In temporal pre-processing, an enhanced fuzzy-inference based double exponential smoothing method is presented to impute the missing values and to derive the temporal patterns for each attribute. In attribute selection, relevant attributes are selected using the tolerance rough set. A classification model is constructed with the selected attributes using temporal pattern induced decision tree classifier. For experimentation, this work uses clinical time series datasets of hepatitis and thrombosis patients. The constructed classification model has proven the effectiveness of the proposed framework with a classification accuracy of 91.5% for hepatitis and 90.65% for thrombosis.





  • A comparison of self-reported emotional and implicit responses to aromas in beer
    22 février 2017
    Publication date: July 2017
    Source:Food Quality and Preference, Volume 59

    Author(s): C. Beyts, C. Chaya, F. Dehrmann, S. James, K. Smart, J. Hort

    Sensory scientists are increasingly measuring consumer emotions to aid discrimination between similarly liked products. Some investigations have solely focused on explicit measures of emotional response, asking consumers to self-report their emotions. Others have focused on understanding whether implicit measures such as changes in physiological and facial expression which they believe may capture unconscious responses to stimuli. In this study physiological response and facial expression along with self-reported emotional response and conventional hedonic liking measures towards a range of pleasant, unpleasant and neutral aromas within beer were evaluated. Physiological measures included heart rate and skin temperature, whilst facial expression was assessed by measuring corrugator supercilli and zygomatic major muscle activity using facial electromyography recorded via a MP150WSW (MP150) physiological data acquisition system (Biopac, Goleta, CA, USA). Self-reported emotional response was recorded using a beer specific emotional lexicon. No differences in heart rate and skin temperature were observed in response to presentation of any of the aromas. Facial expression measures found that corrugator supercilli and zygomatic major activity changed in response to unpleasant and pleasant or unpleasant and neutral samples respectively. Liking scores were found to distinguish between more aromas than facial expression measures, allowing distinction between pleasant and neutral samples. Self-reported emotional response was found to be more discriminating than both liking and facial expression measures, allowing discrimination between pleasant and neutral samples as well as between the pleasant samples themselves. The ability for self-reported emotional response to distinguish between pleasant aromas is of particular interest to industry where commercial products may be poorly discriminated on the basis of liking alone. However further work to understand the contribution of implicit measures to understanding emotional response, in particular their association with explicit measures and their representation of unconscious response is required.





  • A novel dominant D109A CRYAB mutation in a family with myofibrillar myopathy affects αB-crystallin structure
    22 février 2017
    Publication date: June 2017
    Source:BBA Clinical, Volume 7

    Author(s): Jakub P. Fichna, Anna Potulska-Chromik, Przemysław Miszta, Maria Jolanta Redowicz, Anna M. Kaminska, Cezary Zekanowski, Sławomir Filipek

    Myofibrillar myopathy (MFM) is a group of inherited muscular disorders characterized by myofibrils dissolution and abnormal accumulation of degradation products. So far causative mutations have been identified in nine genes encoding Z-disk proteins, including αB-crystallin (CRYAB), a small heat shock protein (also called HSPB5). Here, we report a case study of a 63-year-old Polish female with a progressive lower limb weakness and muscle biopsy suggesting a myofibrillar myopathy, and extra-muscular multisystemic involvement, including cataract and cardiomiopathy. Five members of the proband's family presented similar symptoms. Whole exome sequencing followed by bioinformatic analysis revealed a novel D109A mutation in CRYAB associated with the disease. Molecular modeling in accordance with muscle biopsy microscopic analyses predicted that D109A mutation influence both structure and function of CRYAB due to decreased stability of oligomers leading to aggregate formation. In consequence disrupted sarcomere cytoskeleton organization might lead to muscle pathology. We also suggest that mutated RQDE sequence of CRYAB could impair CRYAB chaperone-like activity and promote aggregation of lens crystallins.





  • Myotonic dystrophy: disease repeat range, penetrance, age of onset, and relationship between repeat size and phenotypes
    22 février 2017
    Publication date: June 2017
    Source:Current Opinion in Genetics & Development, Volume 44

    Author(s): Kevin Yum, Eric T Wang, Auinash Kalsotra

    Myotonic dystrophy (DM) is an autosomal dominant neuromuscular disease primarily characterized by myotonia and progressive muscle weakness. The pathogenesis of DM involves microsatellite expansions in noncoding regions of transcripts that result in toxic RNA gain-of-function. Each successive generation of DM families carries larger repeat expansions, leading to an earlier age of onset with increasing disease severity. At present, diagnosis of DM is challenging and requires special genetic testing to account for somatic mosaicism and meiotic instability. While progress in genetic testing has been made, more rapid, accurate, and cost-effective approaches for measuring repeat lengths are needed to establish clear correlations between repeat size and disease phenotypes.





  • Protection of the genitofemoral nerve using endoscopic assistance in minimally invasive lateral lumbar fusion
    22 février 2017
    Publication date: June 2017
    Source:Interdisciplinary Neurosurgery, Volume 8

    Author(s): Thomas K. Lee, Joseph S. Yazdi, Kenneth E. Floro, Processo T. Arenos, Jessica R. Lee

    Postoperative groin and thigh dysesthesias are known potential sequelae of minimally invasive lateral lumbar interbody fusions (LLIF). Injury to the genitofemoral nerve (GFN) may play some role in occurrence of these symptoms. Our goals were to determine a precise, reproducible manner of diagnosing postoperative GFN dysfunction, and to evaluate an endoscopic assisted LLIF as a viable method of identifying and protecting the GFN. We performed a retrospective review of 21 consecutive patients undergoing endoscopic-assisted LLIF at 33 disc levels. CO2 insufflation was performed through a laterally placed incision. The GFN was visualized over the surface of the psoas muscle and mobilized away from the surgical corridor. The rest of the surgery proceeded as previously described (Ozgur et al., 2006 [18]). The presence of GFN injury was defined as a subjective sense of pain, numbness, or dysesthesias in the GFN territory, or an objective decrease in sensation in the ipsilateral femoral triangle. The patients were followed for an average of 15.1months (range of 2 to 41months). The GFN was identified in the surgical corridor in seven cases. In 6 patients, the nerve was easily mobilized. In one patient, intramuscular dissection was required. This patient experienced temporary diminished sensation in the territory of the GFN. Therefore, our rate of transient genitofemoral neuropathy was 4.8%, and there were no cases of permanent nerve damage. This paper further confirms the specific sensory distribution of the femoral branch of the GFN and also provides in vivo evidence that the vulnerably situated GFN can be safely mobilized and avoided using an endoscopic direct look.





  • Atypical anatomy associated with a lumbar far lateral disc herniation
    22 février 2017
    Publication date: June 2017
    Source:Interdisciplinary Neurosurgery, Volume 8

    Author(s): Michael D. Staudt, Abhishek Ray, Alia Hdeib, Jonathan P. Miller

    Far lateral disc herniation is an uncommon but potentially significant cause of intractable leg pain associated with compression of the exiting nerve root and associated dorsal root ganglion. Since far lateral disc herniations are located outside the spinal canal, several minimally invasive paraspinal muscle-splitting techniques have been developed that allow for neural decompression with reduced soft tissue and bony trauma compared with conventional midline approaches. However, minimally invasive approaches require familiarity with the microsurgical anatomy of the extra-foraminal compartment because of the limited exposure. We report a case of an atypical anatomic relationship identified during far lateral discectomy involving a disc fragment located in a superolateral location relative to the exiting nerve root rather than the more common inferomedial location. This report highlights that familiarity with atypical locations of an extra-foraminal disc herniation and careful exploration of all quadrants in the surgical field is important during minimally invasive far lateral discectomy.





  • Selecting optimum base wavelet for extracting spectral alteration features associated with porphyry copper mineralization using hyperspectral images
    22 février 2017
    Publication date: June 2017
    Source:International Journal of Applied Earth Observation and Geoinformation, Volume 58

    Author(s): Mehdi Abdolmaleki, Morteza Tabaei, Nader Fathianpour, Ben G.H. Gorte

    Extracting a set of meaningful spectral features could enhance the classification performance. This is particularly important in hyperspectral images where the dataset are very large and time consuming to process. Wavelet transform as a powerful decomposition tool in both low and high frequency components could play an essential role in extracting spectral features of target minerals. Selecting the optimum base wavelet is an important step in wavelet transform. In this research, two criteria to select optimum base wavelet were implemented on three wavelet series including Daubechie (db), symlet (sym) and coiflet (coif). Energy criterion involves entropy factor and energy-to-Shannon entropy ratio while matching shape criterion operates according to correlation coefficients. High ranking base wavelets in both energy and shape criteria, coif1, db3 and db7, are recommended to be utilized in hyperspectral image classification. Neural Network technique was used for classification and trained by means of mineral spectral features related to typical porphyry copper deposits. Non-Linear wavelet feature extraction was employed to select the efficient features as input data. The study area covered by Hyperion data contains two well-known porphyry copper deposits, Darrehzar and Sarcheshmeh, located in the Iranian copper belt. Based on classification error matrix, it is concluded that db7 through 12 selected features exhibits the maximum consistency with the field measured data and can be recommended as an appropriate base wavelet for detecting porphyry copper deposits.





  • Social consequences of subclinical negative symptoms: An EMG study of facial expressions within a social interaction
    22 février 2017
    Publication date: June 2017
    Source:Journal of Behavior Therapy and Experimental Psychiatry, Volume 55

    Author(s): Marcel Riehle, Tania M. Lincoln

    Background and objectives The negative symptoms of schizophrenia are related to lower social functioning even in non-clinical samples, but little is known about the distinct social consequences of motivational and expressive negative symptoms. In this study we focused on expressive negative symptoms and examined how these symptoms and varying degrees of pro-social facial expressiveness (smiling and mimicry of smiling) relate to the social evaluations by face-to-face interaction partners and to social support. Methods We examined 30 dyadic interactions within a sample of non-clinical participants (N = 60) who were rated on motivational and expressive negative symptoms with the Clinical Assessment Interview for Negative Symptoms (CAINS). We collected data on both interaction partners’ smiling-muscle (zygomaticus major) activation simultaneously with electromyography and assessed the general amount of smiling and the synchrony of smiling muscle activations between interaction partners (mimicry of smiling). Interaction partners rated their willingness for future interactions with each other after the interactions. Results Interaction partners of participants scoring higher on expressive negative symptoms expressed less willingness for future interactions with these participants (r = −0.37; p = 0.01). Smiling behavior was negatively related to expressive negative symptoms but also explained by motivational negative symptoms. Mimicry of smiling and both negative symptom domains were also associated with participants’ satisfaction with their social support network. Limitations Non-clinical sample with (relatively) low levels of symptoms. Conclusions Expressive negative symptoms have tangible negative interpersonal consequences and directly relate to diminished pro-social behavior and social support, even in non-clinical samples.





  • Self-efficacy theory applied to undergraduate biomechanics instruction
    22 février 2017
    Publication date: June 2017
    Source:Journal of Hospitality, Leisure, Sport & Tourism Education, Volume 20

    Author(s): Brian Wallace, Thomas Kernozek

    Undergraduates are usually required to complete one or more biomechanics courses in a movement science curriculum. Students often avoid taking this course, perhaps because they have a reduced perception of success due to low self-efficacy with the perceived content, particularly related to mathematics. Student learning may be increased through the self-efficacy theory constructs of performance accomplishments, vicarious experiences, verbal persuasion, and emotional arousal. Within these, instructors may enhance student learning by: increasing students’ perception of the content's application, reducing the use of technical equipment, utilizing modern presentation technologies, and emphasizing qualitative understanding. This paper will detail each of these.

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  • Interleukin 37 expression in mice alters sleep responses to inflammatory agents and influenza virus infection
    22 février 2017
    Publication date: June 2017
    Source:Neurobiology of Sleep and Circadian Rhythms, Volume 3

    Author(s): Christopher J. Davis, Mark R. Zielinski, Danielle Dunbrasky, Ping Taishi, Charles A. Dinarello, James M. Krueger

    Multiple interactions between the immune system and sleep are known, including the effects of microbial challenge on sleep or the effects of sleep loss on facets of the immune response. Cytokines regulate, in part, sleep and immune responses. Here we examine the role of an anti-inflammatory cytokine, interleukin-37 (IL-37) on sleep in a mouse strain that expresses human IL-37b (IL37tg mice). Constitutive expression of the IL-37 gene in the brains of these mice under resting conditions is low; however, upon an inflammatory stimulus, expression increases dramatically. We measured sleep in three conditions; (a) under baseline conditions and after 6h of sleep loss, (b) after bolus intraperitoneal administration of lipopolysaccharide (LPS) or IL-1β and (c) after intranasal influenza virus challenge. Under baseline conditions, the IL37tg mice had 7% more spontaneous non-rapid eye movement sleep (NREMS) during the light period than wild-type (WT) mice. After sleep deprivation both WT mice and IL37tg mice slept an extra 21% and 12%, respectively, during the first 6h of recovery. NREMS responses after sleep deprivation did not significantly differ between WT mice and IL37tg mice. However, in response to either IL-1β or LPS, the increases in time spent in NREMS were about four-fold greater in the WT mice than in the IL37tg mice. In contrast, in response to a low dose of mouse-adapted H1N1 influenza virus, sleep responses developed slowly over the 6day recording period. By day 6, NREMS increased by 10% and REMS increased by 18% in the IL37tg mice compared to the WT mice. Further, by day 4 IL37tg mice lost less weight, remained more active, and retained their body temperatures closer to baseline values than WT mice. We conclude that conditions that promote IL-37 expression attenuate morbidity to severe inflammatory challenge.





  • Capacitive biopotential electrode with a ceramic dielectric layer
    22 février 2017
    Publication date: June 2017
    Source:Sensors and Actuators B: Chemical, Volume 245

    Author(s): Karel Vlach, Jan Kijonka, Frantisek Jurek, Petr Vavra, Pavel Zonca

    This paper presents the design of an innovative active capacitive electrode with a ceramic dielectric layer. The electrode meets the requirements for contactless measurement, resistance to motion artefacts and possibility to make long and repeated recordings. The proposed capacitive electrode is distinguished from other capacitive electrodes by the construction of the capacitive coupling element, which is placed on the body surface. While common capacitive electrodes use a metal plate with a relatively large surface area as the capacitive coupling element, the proposed electrode uses a dielectric ceramic layer with high permittivity and a surface area no greater than a few cm2. In order to test the electrode, an electrocardiography (ECG) measuring system was designed. Several different dielectric materials, different sizes of the electrode surface, as well as different electronics of the electrode were compared. The results show 26dB signal to noise ratio (SNR) for the electrode with a ceramic dielectric layer, which was put on a skin over a cotton fabric, compared to 13dB SNR for an electrode with a metal plate with a four times larger surface area.





  • Opening the mind through the body: The effects of posture on creative processes
    22 février 2017
    Publication date: June 2017
    Source:Thinking Skills and Creativity, Volume 24

    Author(s): Valentina Rita Andolfi, Chiara Di Nuzzo, Alessandro Antonietti

    Body movements and gestures have been found to influence the generation of novel ideas, however, whether posture does, has not yet been investigated. Two studies were conducted in order to assess whether open vs. closed body postures influenced creative thinking. In Study 1, the participants completed two creative tasks when assuming an open or a closed posture, whereas in Study 2 the participants completed creative and logic tasks assuming the same postures. Comfort and physiological indexes, as well as electromyograms were recorded. The scores that were obtained in the creative tasks were significantly higher for those participants who performed the tasks in the open posture rather than in the closed posture. The comfort and physiological indexes were not affected by posture. The data supported the notion that posture modulates a performance in creative tasks, thus facilitating the production of innovative ideas when subjects embody a posture that metaphorically suggests an adoption of a broader mental framework.





  • Work boot design affects the way workers walk: A systematic review of the literature
    22 février 2017
    Publication date: May 2017
    Source:Applied Ergonomics, Volume 61

    Author(s): Jessica A. Dobson, Diane L. Riddiford-Harland, Alison F. Bell, Julie R. Steele

    Safety boots are compulsory in many occupations to protect the feet of workers from undesirable external stimuli, particularly in harsh work environments. The unique environmental conditions and varying tasks performed in different occupations necessitate a variety of boot designs to match each worker's occupational safety and functional requirements. Unfortunately, safety boots are often designed more for occupational safety at the expense of functionality and comfort. In fact, there is a paucity of published research investigating the influence that specific variations in work boot design have on fundamental tasks common to many occupations, such as walking. This literature review aimed to collate and examine what is currently known about the influence of boot design on walking in order to identify gaps in the literature and develop evidence-based recommendations upon which to design future research studies investigating work boot design.





  • A new method of ergonomic testing of gloves protecting against cuts and stabs during knife use
    22 février 2017
    Publication date: May 2017
    Source:Applied Ergonomics, Volume 61

    Author(s): Emilia Irzmańska, Tomasz Tokarski

    The paper presents a new method of ergonomic evaluation of gloves protecting against cuts and stabs during knife use, consisting of five manual dexterity tests. Two of them were selected based on the available literature and relevant safety standards, and three were developed by the authors. All of the tests were designed to simulate occupational tasks associated with meat processing as performed by the gloved hand in actual workplaces. The tests involved the three most common types of protective gloves (knitted gloves made of a coverspun yarn, metal mesh gloves, and metal mesh gloves with an ergonomic polyurethane tightener) and were conducted on a group of 20 males. The loading on the muscles of the upper limb (adductor pollicis, flexor carpi ulnaris, flexor carpi radialis, and biceps brachii) was measured using surface electromyography. For the obtained muscle activity values, correlations were found between the glove type and loading of the upper limb. ANOVA showed that the activity of all muscles differed significantly between the five tests. A relationship between glove types and electromyographic results was confirmed at a significance level of α = 0.05.





  • Effects of touch target location on performance and physical demands of computer touchscreen use
    22 février 2017
    Publication date: May 2017
    Source:Applied Ergonomics, Volume 61

    Author(s): Hwayeong Kang, Gwanseob Shin

    Touchscreen interfaces for computers are known to cause greater physical stress compared to traditional computer interfaces. The objective of this study was to evaluate how physical demands and task performance of a tap gesture on a computer touchscreen vary between target locations and display positions. Twenty-three healthy participants conducted reach-tap-return trials with touch targets at fifteen locations in three display positions. Mean completion time, touch accuracy and electromyography of the shoulder and neck extensor muscles were compared between the target locations and display positions. The results demonstrated that participants completed the trial 12%–27% faster with 13%–39% less muscle activity when interacting with targets in the lower area of the display compared to when tapping upper targets (p < 0.05). The findings suggest that proper target placement and display positioning can improve task performance and lessen physical demands of computer touchscreen interface use.





  • Evolving type-2 web news mining
    22 février 2017
    Publication date: May 2017
    Source:Applied Soft Computing, Volume 54

    Author(s): Choiru Za’in, Mahardhika Pratama, Edwin Lughofer, Sreenatha G. Anavatti

    Web news articles are generated in continuous, time-varying, and rapid modes. This environment causes an explosion of information which needs to be stored, processed and analyzed. Conventional machine learning algorithms that are applied in the web news mining work in an offline environment cannot efficiently handle data streams. In this paper, we propose an evolving web news mining framework based on the recently published Evolving Type-2 Classifier (eT2Class). The eT2Class adopts an open structure that can be used in non-stationary environments and works on a single pass learning mode that is applicable for online real-time applications. The effectiveness of our evolving web news mining techniques is numerically validated and compared against state-of-the-art algorithms. The efficacy of our methodology has been numerically validated with real local Australian news articles, namely the Age, spanning from 26/2/2016 to 13/3/2016 and has been compared with 6 state of the art algorithms. Our algorithm outperforms other consolidated algorithms and achieves a tradeoff between complexity and accuracy with almost 10% improvement in term of complexity.

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  • Effects of aging on mechanical properties of sternocleidomastoid and trapezius muscles during transition from lying to sitting position—A cross-sectional study
    22 février 2017
    Publication date: May–June 2017
    Source:Archives of Gerontology and Geriatrics, Volume 70

    Author(s): Piotr Kocur, Marcin Grzeskowiak, Marzena Wiernicka, Magdalena Goliwas, Jacek Lewandowski, Dawid Łochyński

    Aim The aim of this study was to analyze the effects of aging on the viscoelastic properties of the upper trapezius (UT) and the sternocleidomastoid (SCM) muscle during transition from lying to sitting position. Materials and methods The study included 39 older (mean age 67±5.9years) and 36 younger (21.1±1.8years) women. Tone, stiffness and elasticity of the UT and the SCM were measured by means of myotonometry (MyotonPRO) in lying and then, in sitting position. The results were compared using two-way analysis of variance. Results Irrespective of the position, older women presented with significantly higher muscle tone, stiffness and elasticity than younger subjects (P<0.05). In both groups, the transition from lying to sitting position resulted in a decrease (P<0.05) in the tone and stiffness, but not the elasticity (P>0.05) of the SCM, and stimulated an increase in the tone, stiffness and elasticity of the UT (P<0.05). The degree of changes in both study groups was similar, except from the absolute value of the UT elasticity, significantly higher increase in older women than in younger subjects (P<0.05). Conclusion Age contributes to an increase in the stiffness and tone of the UT and the SCM, as well as to a decrease in the elasticity of these muscles in female subjects. In contrast, age exerts only a slight effect on the mechanical properties of both muscles during transition from lying to sitting position.





  • Multi-sensor fusion in body sensor networks: State-of-the-art and research challenges
    22 février 2017
    Publication date: May 2017
    Source:Information Fusion, Volume 35

    Author(s): Raffaele Gravina, Parastoo Alinia, Hassan Ghasemzadeh, Giancarlo Fortino

    Body Sensor Networks (BSNs) have emerged as a revolutionary technology in many application domains in health-care, fitness, smart cities, and many other compelling Internet of Things (IoT) applications. Most commercially available systems assume that a single device monitors a plethora of user information. In reality, BSN technology is transitioning to multi-device synchronous measurement environments; fusion of the data from multiple, potentially heterogeneous, sensor sources is therefore becoming a fundamental yet non-trivial task that directly impacts application performance. Nevertheless, only recently researchers have started developing technical solutions for effective fusion of BSN data. To the best of our knowledge, the community is currently lacking a comprehensive review of the state-of-the-art techniques on multi-sensor fusion in the area of BSN. This survey discusses clear motivations and advantages of multi-sensor data fusion and particularly focuses on physical activity recognition, aiming at providing a systematic categorization and common comparison framework of the literature, by identifying distinctive properties and parameters affecting data fusion design choices at different levels (data, feature, and decision). The survey also covers data fusion in the domains of emotion recognition and general-health and introduce relevant directions and challenges of future research on multi-sensor fusion in the BSN domain.





  • Creep-fatigue damage modeling in Ti-6Al-4V alloy: A mechanistic approach
    22 février 2017
    Publication date: May 2017
    Source:International Journal of Fatigue, Volume 98

    Author(s): Jalaj Kumar, A.K. Singh, S. Ganesh Sundara Raman, Vikas Kumar

    This study investigates the mechanistic approach to evaluate total stored energy consisting of damage energy (due to voids and microcracks) and deformation energy (due to dislocations). Thermal data obtained by online IRT technique have been employed for this evaluation. The deformation energy is estimated through EBSD analysis. Subsequently, the damage and deformation induced by creep and fatigue have been modeled as functions of applied stress and cumulative plastic strain, individually. By using the data of experimental creep stress and fatigue strain for each creep-fatigue cycle, the contributions of creep and fatigue damage energies have been estimated for creep-fatigue interaction. New fatigue and creep damage parameters have been proposed based on the damage mechanics concepts. Different regimes have been identified and explained with creep and fatigue damage evolution curves. The present approach has also been extended to characterize incremental creep-fatigue interactions.

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  • A personalized 3D-printed prosthetic joint replacement for the human temporomandibular joint: From implant design to implantation
    22 février 2017
    Publication date: May 2017
    Source:Journal of the Mechanical Behavior of Biomedical Materials, Volume 69

    Author(s): David C. Ackland, Dale Robinson, Michael Redhead, Peter Vee Sin Lee, Adrian Moskaljuk, George Dimitroulis

    Personalized prosthetic joint replacements have important applications in cases of complex bone and joint conditions where the shape and size of off-the-shelf components may not be adequate. The objective of this study was to design, test and fabricate a personalized 3D-printed prosthesis for a patient requiring total joint replacement surgery of the temporomandibular joint (TMJ). The new ‘Melbourne’ prosthetic TMJ design featured a condylar component sized specifically to the patient and fixation screw positions that avoid potential intra-operative damage to the mandibular nerve. The Melbourne prosthetic TMJ was developed for a 58-year-old female recipient with end-stage osteoarthritis of the TMJ. The load response of the prosthesis during chewing and a maximum-force bite was quantified using a personalized musculoskeletal model of the patient's masticatory system developed using medical images. The simulations were then repeated after implantation of the Biomet Microfixation prosthetic TMJ, an established stock device. The maximum condylar stresses, screw stress and mandibular stress at the screw-bone interface were lower in the Melbourne prosthetic TMJ (259.6MPa, 312.9MPa and 198.4MPa, respectively) than those in the Biomet Microfixation device (284.0MPa, 416.0MPa and 262.2MPa, respectively) during the maximum-force bite, with similar trends also observed during the chewing bite. After trialing surgical placement and evaluating prosthetic TMJ stability using cadaveric specimens, the prosthesis was fabricated using 3D printing, sterilized, and implanted into the female recipient. Six months post-operatively, the prosthesis recipient had a normal jaw opening distance (40.0 mm), with no complications identified. The new design features and immediate load response of the Melbourne prosthetic TMJ suggests that it may provide improved clinical and biomechanical joint function compared to a commonly used stock device, and reduce risk of intra-operative nerve damage during placement. The framework presented may be useful for designing and testing customized devices for the treatment of debilitating bone and joint conditions.

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  • Abnormal lipid metabolism in skeletal muscle tissue of patients with muscular dystrophy: In vitro, high-resolution NMR spectroscopy based observation in early phase of the disease
    22 février 2017
    Publication date: May 2017
    Source:Magnetic Resonance Imaging, Volume 38

    Author(s): Niraj Kumar Srivastava, Ramakant Yadav, Somnath Mukherjee, Lily Pal, Neeraj Sinha

    Purpose Qualitative (assignment of lipid components) and quantitative (quantification of lipid components) analysis of lipid components were performed in skeletal muscle tissue of patients with muscular dystrophy in early phase of the disease as compared to control/normal subjects. Methods Proton nuclear magnetic resonance (NMR) spectroscopy based experiment was performed on the lipid extract of skeletal muscle tissue of patients with muscular dystrophy in early phase of the disease and normal individuals for the analysis of lipid components [triglycerides, phospholipids, total cholesterol and unsaturated fatty acids (arachidonic, linolenic and linoleic acid)]. Specimens of muscle tissue were obtained from patients with Duchenne muscular dystrophy (DMD) [n =11; Age, Mean±SD; 9.2±1.4years; all were males], Becker muscular dystrophy (BMD) [n =12; Age, Mean±SD; 21.4±5.0years; all were males], facioscapulohumeral muscular dystrophy (FSHD) [n =11; Age, Mean±SD; 23.7±7.5years; all were males] and limb girdle muscular dystrophy-2B (LGMD-2B) [n =18; Age, Mean±SD; 24.2±4.1years; all were males]. Muscle specimens were also obtained from [n =30; Mean age±SD 23.1±6.0years; all were males] normal/control subjects. Results Assigned lipid components in skeletal muscle tissue were triglycerides (TG), phospholipids (PL), total cholesterol (CHOL) and unsaturated fatty acids (arachidonic, linolenic and linoleic acid)]. Quantity of lipid components was observed in skeletal muscle tissue of DMD, BMD, FSHD and LGMD-2B patients as compared to control/normal subjects. TG was significantly elevated in muscle tissue of DMD, BMD and LGMD-2B patients. Increase level of CHOL was found only in muscle of DMD patients. Level of PL was found insignificant for DMD, BMD and LGMD-2B patients. Quantity of TG, PL and CHOL was unaltered in the muscle of patients with FSHD as compared to control/normal subjects. Linoleic acids were significantly reduced in muscle tissue of DMD, BMD, FSHD and LGMD-2B as compared to normal/control individuals. Conclusions Results clearly indicate alteration of lipid metabolism in patients with muscular dystrophy in early phase of the disease. Moreover, further evaluation is required to understand whether these changes are primary or secondary to muscular dystrophy. In future, these findings may prove an additional and improved approach for the diagnosis of different forms of muscular dystrophy.





  • Seizure-associated central apnea in a rat model: Evidence for resetting the respiratory rhythm and activation of the diving reflex
    22 février 2017
    Publication date: May 2017
    Source:Neurobiology of Disease, Volume 101

    Author(s): S.M. Villiere, K. Nakase, R. Kollmar, J. Silverman, K. Sundaram, M. Stewart

    Respiratory derangements, including irregular, tachypnic breathing and central or obstructive apnea can be consequences of seizure activity in epilepsy patients and animal models. Periods of seizure-associated central apnea, defined as periods >1s with rapid onset and offset of no airflow during plethysmography, suggest that seizures spread to brainstem respiratory regions to disrupt breathing. We sought to characterize seizure-associated central apneic episodes as an indicator of seizure impact on the respiratory rhythm in rats anesthetized with urethane and given parenteral kainic acid to induce recurring seizures. We measured central apneic period onsets and offsets to determine if onset-offset relations were a consequence of 1) a reset of the respiratory rhythm, 2) a transient pausing of the respiratory rhythm, resuming from the pause point at the end of the apneic period, 3) a transient suppression of respiratory behavior with apnea offset predicted by a continuation of the breathing pattern preceding apnea, or 4) a random re-entry into the respiratory cycle. Animals were monitored with continuous ECG, EEG, and plethysmography. One hundred ninety central apnea episodes (1.04 to 36.18s, mean: 3.2±3.7s) were recorded during seizure activity from 7 rats with multiple apneic episodes. The majority of apneic period onsets occurred during expiration (125/161 apneic episodes, 78%). In either expiration or inspiration, apneic onsets tended to occur late in the cycle, i.e. between the time of the peak and end of expiration (82/125, 66%) or inspiration (34/36, 94%). Apneic period offsets were more uniformly distributed between early and late expiration (27%, 34%) and inspiration (16%, 23%). Differences between the respiratory phase at the onset of apnea and the corresponding offset phase varied widely, even within individual animals. Each central apneic episode was associated with a high frequency event in EEG or ECG records at onset. High frequency events that were not associated with flatline plethysmographs revealed a constant plethysmograph pattern within each animal, suggesting a clear reset of the respiratory rhythm. The respiratory rhythm became highly variable after about 1s, however, accounting for the unpredictability of the offset phase. The dissociation of respiratory rhythm reset from the cessation of airflow also suggested that central apneic periods involved activation of brainstem regions serving the diving reflex to eliminate the expression of respiratory movements. This conclusion was supported by the decreased heart rate as a function of apnea duration. We conclude that seizure-associated central apnea episodes are associated with 1) a reset of the respiratory rhythm, and 2) activation of brainstem regions serving the diving reflex to suppress respiratory behavior. The significance of these conclusions is that these details of seizure impact on brainstem circuitry represent metrics for assessing seizure spread and potentially subclassifying seizure patterns.





  • Chemosensory anxiety signals prime defensive behavior in prepubertal girls
    22 février 2017
    Publication date: 1 May 2017
    Source:Physiology & Behavior, Volume 173

    Author(s): Katrin T. Lübke, Anne Busch, Matthias Hoenen, Benoist Schaal, Bettina M. Pause

    Chemosensory anxiety signals effectively prime motor responses related to withdrawal behavior, such as the startle reflex, in adult humans. As the reproductive status strongly affects the response to social chemosignals, the current study examined whether chemosensory anxiety signals would augment the startle response in prepubertal children as it does in adults. Using cotton pads, axillary sweat was collected from 28 men while waiting for an important oral examination (anxiety condition), and during ergometer training (sport control condition). Using a constant-flow olfactometer, sweat samples and pure cotton samples (cotton control) were presented to 10 prepubertal girls aged 9–13years (M=11.25, SD=1.25) for 3000ms during inhalation. White noise bursts of 102dB(A) served as startle probes, and startle responses were recorded via electromyography of the orbicularis oculi muscle. The girls showed larger startle amplitudes to probes presented in the context of chemosensory anxiety signals as compared to a context of sport control sweat (p<0.01) as well as cotton control (p<0.05). This effect was not attributable to differences in stimulus detection rates or stimulus hedonics. The results show that in prepubertal girls, similar to adults, chemosensory anxiety signals prime defensive motor behavior. This effect appears unrelated to the odorous quality of anxiety sweat, but seems to reflect a specific preparedness to respond to the underlying social alarm signal. Thus, chemosensory communication supporting individual harm protection is independent of the reproductive status in humans.





  • Validation of a quantitative method to measure neural respiratory drive in children during sleep
    22 février 2017
    Publication date: May 2017
    Source:Respiratory Physiology & Neurobiology, Volume 239

    Author(s): Sandra Ya-chu Chuang, Arthur Teng, Jane Elizabeth Butler, Simon Charles Gandevia, Hiran Selvadurai, Adam Jaffe

    Aims Quantitatively measure and validate analysis of neural respiratory drive (NRD) using a commercial polysomnography system in children during sleep. Method Surface electromyogram of the diaphragm (sEMGdi) recorded from primary snoring children were analysed. A subset was re-analysed to assess intra- and inter-investigator reproducibility. Effects of different band pass filter settings (20–100Hz vs 10–1000Hz) on sEMGdi amplitude were evaluated. Results Mean sEMGdi from 45 children aged 4.38 years (median; IQR 3.00–7.96) was 5.05μV (SD 2.73). The sEMGdi had a high intra-subject intraclass correlation coefficient (ICC) of 0.88. sEMGdi analysis was reproducible with high ICC between occasions (0.99; 95% CI 0.98–0.99) and between investigators (0.98; 95% CI 0.97–0.99). There was also a high ICC (0.99, 95% CI 0.96–1.00) between the sEMGdi measured using different band-pass filter settings. Age and BMI were negative predictors of sEMGdi (p< 0.0001 and p =0.0004 respectively). Conclusion NRD in children during sleep as assessed by sEMGdi can be quantified in a reliable and reproducible fashion.





  • Respiratory load perception in overweight and asthmatic children
    22 février 2017
    Publication date: May 2017
    Source:Respiratory Physiology & Neurobiology, Volume 239

    Author(s): Victoria MacBean, Lorna Wheatley, Alan C. Lunt, Gerrard F. Rafferty

    Overweight asthmatic children report greater symptoms than normal weight asthmatics, despite comparable airflow obstruction. This has been widely assumed to be due to heightened perception of respiratory effort. Three groups of children (healthy weight controls, healthy weight asthmatics, overweight asthmatics) rated perceived respiratory effort throughout an inspiratory resistive loading protocol. Parasternal intercostal electromyogram was used as an objective marker of respiratory load; this was expressed relative to tidal volume and reported as a ratio of the baseline value (neuroventilatory activity ratio (NVEAR)). Significant increases in perception scores (p<0.0001), and decreases in NVEAR (p<0.0001) were observed from lowest to highest resistive load. Higher BMI increased overall perception scores, with no influence of asthma or BMI-for-age percentile on the resistance-perception relationships. These data, indicating elevated overall respiratory effort in overweight asthmatic children but comparable responses to dynamic changes in load, suggest that the greater disease burden in overweight asthmatic children may be due to altered respiratory mechanics associated with increased body mass.





  • EMG-based decoding of grasp gestures in reaching-to-grasping motions
    22 février 2017
    Publication date: May 2017
    Source:Robotics and Autonomous Systems, Volume 91

    Author(s): I. Batzianoulis, S. El-Khoury, E. Pirondini, M. Coscia, S. Micera, A. Billard

    Predicting the grasping function during reach-to-grasp motions is essential for controlling a prosthetic hand or a robotic assistive device. An early accurate prediction increases the usability and the comfort of a prosthetic device. This work proposes an electromyographic-based learning approach that decodes the grasping intention at an early stage of reach-to-grasp motion, i.e. before the final grasp/hand pre-shape takes place. Superficial electrodes and a Cyberglove were used to record the arm muscle activity and the finger joints during reach-to-grasp motions. Our results showed a 90 % accuracy for the detection of the final grasp about 0.5 s after motion onset. This paper also examines the effect of different objects’ distances and different motion speeds on the detection time and accuracy of the classifier. The use of our learning approach to control a 16-degrees of freedom robotic hand confirmed the usability of our approach for the real-time control of robotic devices.





  • Robotic wrist training after stroke: Adaptive modulation of assistance in pediatric rehabilitation
    22 février 2017
    Publication date: May 2017
    Source:Robotics and Autonomous Systems, Volume 91

    Author(s): Francesca Marini, Charmayne M.L. Hughes, Valentina Squeri, Luca Doglio, Paolo Moretti, Pietro Morasso, Lorenzo Masia

    In this paper we present a case study in which a 14-year-old, right-handed stroke patient with severe weakness, spasticity, and motor dysfunction of the left upper extremity participated in a three-month distal robotic training program. The robotic device was compliant to the patient’s movements and was able to modulate the level of assistance continuously throughout the trial (i.e., online adaptive modulation). Standard clinical and robotic evaluations of upper extremity motor performance were conducted before and after robotic training. There were improvements in upper extremity spasticity and motor functions. In addition, robotic training lead to positive changes in wrist active range of motion and kinematics: movements were smoother and there was a noticeable decrease in the level of robotic intervention required to complete each trial. In sum, results of the present case study demonstrate that distal upper extremity robotic rehabilitation that features the proposed adaptive control algorithm promoted positive changes in upper limb motor coordination and function after pediatric stroke.





  • Optimal duration-bandwidth localized antisymmetric biorthogonal wavelet filters
    22 février 2017
    Publication date: May 2017
    Source:Signal Processing, Volume 134

    Author(s): Manish Sharma, Abhinav Dhere, Ram Bilas Pachori, Vikram M. Gadre

    We present a design of a new class of compactly supported antisymmetric biorthogonal wavelet filter banks which have the analysis as well as the synthesis filters of even-length. Here, the analysis and the synthesis filters are designed to have minimum joint duration-bandwidth localization (JDBL). The design of filters has been formulated as a direct time-domain linearly constrained eigenvalue problem that does not involve any parametrization and iterations. The optimal analysis and synthesis filters have been obtained as the eigenvectors of the positive definite matrices. The closed form analytic expression for the objective function has been presented. The perfect reconstruction and regularity conditions have been incorporated in the design by employing time-domain matrix characterization. The method can control duration and bandwidth localizations of the analysis and synthesis filters, independently. A few design examples have been presented and compared with previous works. The performance of the optimal filter banks designed by employing the proposed method has been evaluated in image coding and signal denoising applications.





  • Hidden-layer visible deep stacking network optimized by PSO for motor imagery EEG recognition
    22 février 2017
    Publication date: 19 April 2017
    Source:Neurocomputing, Volume 234

    Author(s): Xianlun Tang, Na Zhang, Jialin Zhou, Qing Liu

    A novel method called PSO optimized hidden-layer visible deep stacking network (PHVDSN) is proposed for feature extraction and recognition of motor imagery electroencephalogram (EEG) signals. A prior knowledge is introduced into the intermediate layer of deep stacking network (DSN) and the hidden nodes are expanded by the unsupervised training of restricted Boltzmann machine (RBM) for the parameter initialization. Then particle swarm optimization (PSO) is applied to optimize the input weights, aiming at alleviating the risk of being immersed in the curse of dimensionality. The performance of the proposed method is evaluated with real EEG signals from different subjects. Experimental results show that the recognition accuracy of PHVDSN is superior to some state-of-the-art feature extraction algorithms. Furthermore, on another benchmark data set where the EEG sessions for each subject are recorded on separated days, the proposed method is demonstrated to be robust against transferring from session to session.





  • Increasing trend of wearables and multimodal interface for human activity monitoring: A review
    22 février 2017
    Publication date: 15 April 2017
    Source:Biosensors and Bioelectronics, Volume 90

    Author(s): Preeti Kumari, Lini Mathew, Poonam Syal

    Activity recognition technology is one of the most important technologies for life-logging and for the care of elderly persons. Elderly people prefer to live in their own houses, within their own locality. If, they are capable to do so, several benefits can follow in terms of society and economy. However, living alone may have high risks. Wearable sensors have been developed to overcome these risks and these sensors are supposed to be ready for medical uses. It can help in monitoring the wellness of elderly persons living alone by unobtrusively monitoring their daily activities. The study aims to review the increasing trends of wearable devices and need of multimodal recognition for continuous or discontinuous monitoring of human activity, biological signals such as Electroencephalogram (EEG), Electrooculogram (EOG), Electromyogram (EMG), Electrocardiogram (ECG) and parameters along with other symptoms. This can provide necessary assistance in times of ominous need, which is crucial for the advancement of disease-diagnosis and treatment. Shared control architecture with multimodal interface can be used for application in more complex environment where more number of commands is to be used to control with better results in terms of controlling.





  • Advances in assessing myotonia: Can sensor-engineered glove have a role?
    22 février 2017
    Publication date: 15 April 2017
    Source:Journal of the Neurological Sciences, Volume 375

    Author(s): Simona Portaro, Margherita Russo, Antonino Naro, Alessia Bramanti, Placido Bramanti, Carmelo Rodolico, Rocco Salvatore Calabrò

    Non-dystrophic (NDMs) and Dystrophic Myotonias (DMs) are diseases characterized by the presence of myotonia with or without muscle weakness. A standardized myotonia assessment is important to more objectively quantify the handgrip myotonia. We screened 10 patients affected by NDM and 10 patients with DM, using the sensor-engineered glove (SEG). The time required to perform a complete finger extension (grip myotonia time, GMT) at maximum velocity (MV) after maximum voluntary contraction (MVC) was evaluated through an ad hoc protocol including rest, exercise, and ice effects on handgrip myotonia. We observed a general trend to GMT increase when applying the ice block and a GMT decrease when repeating GM movements, at individual level in both NDM and DM patients. SEG is an automated, non-invasive, quick, and easy technique for evaluating handgrip myotonia in NDM and DM patients. SEG could, therefore, be considered a promising tool to evaluate myotonia and monitor treatment efficacy for clinical trials.





  • Immunoglobulin therapy in the treatment of multifocal motor neuropathy
    22 février 2017
    Publication date: 15 April 2017
    Source:Journal of the Neurological Sciences, Volume 375

    Author(s): Aditya Kumar, Huned S. Patwa, Richard J. Nowak

    Multifocal motor neuropathy (MMN) is a chronic immune-mediated disorder leading to slowly progressive muscle weakness and wasting. Current treatments are aimed at modulating the immune system in order to avoid further decline and to maintain functional status. Intravenous immunoglobulin (IVIg) is widely used in the treatment of immune-mediated disorders and is the only treatment approved for MMN. While patients do remain stable with maintenance IVIg treatment, most patients will slowly deteriorate over many years. The use of subcutaneous immunoglobulin (ScIg) is also gaining acceptance in this disease. The amount of axonal loss and the number of years without immunoglobulin (Ig) treatment appear to be associated with the permanence of weakness. We summarize the key literature to date that supports Ig use in the treatment of MMN.





  • The duration of the cortical silent period is not abnormal in Restless Legs Syndrome/Willis-Ekbom Disease
    22 février 2017
    Publication date: 15 April 2017
    Source:Journal of the Neurological Sciences, Volume 375

    Author(s): Joselisa Péres Queiroz de Paiva, Samir Câmara Magalhães, Gilmar Fernandes do Prado, Alan Luiz Eckeli, Alain Kaelin-Lang, Adriana Bastos Conforto

    Objective To compare the duration of the cortical silent period (CSP) measured in a hand muscle in subjects with primary Restless Legs Syndrome (RLS/WED) and controls, using four different methods of analysis. Methods The CSP to transcranial magnetic stimulation of the dominant motor cortex was assessed in the abductor digiti minimi of 33 subjects with RLS/WED and 24 controls. CSP duration was measured by an automated and three visually-guided methods. Results There were significant differences between absolute values of CSP duration according to the method of analysis. However, irrespectively of the method used for CSP assessment, no differences were found between measurements performed in subjects with RLS/WED and subjects from the control group. Conclusions Absolute values of CSP durations analyzed by different methods should not be directly compared, because significantly different results can be obtained from the same data set. Significance The CSP assessed from a hand muscle is unlikely to be a biomarker of primary RLS/WED. Our results highlight the importance of standardizing the definition of CSP onset and offset, as well as of describing in detail the methodology chosen to record and measure CSP duration, in order to enable comparisons between studies.





  • Piezoelectric BaTiO3/alginate spherical composite beads for energy harvesting and self-powered wearable flexion sensor
    22 février 2017
    Publication date: 12 April 2017
    Source:Composites Science and Technology, Volume 142

    Author(s): Nagamalleswara Rao Alluri, Sophia Selvarajan, Arunkumar Chandrasekhar, Balasubramaniam Saravanakumar, Ji Hyun Jeong, Sang-Jae Kim

    A simple, large-scale fabrication of spherical composite (BaTiO3 nanoparticle/Ca-alginate) beads was developed using the ionotropic gelation (IG) method. The energy harvesting performance of a composite bead-based nanogenerator (CBNG) was studied using various device areas (3 cm2, 11.25 cm2), different mechanical pressures (170 Pa–1.77 kPa) and bending angles, rapid hand force, capacitive loadings and electrical poling. High output (82 V, 227 μA) was generated with a simple low mechanical pressure of 1.70 kPa, which is enough to drive low power electronic devices. We demonstrate that the strip-based CBNG (S-CBNG) device can act as a self-powered wearable flexion sensor for decoding right arm finger flexion/extension movements in a periodic manner without any external battery and additional sensory circuit. It is highly desirable to classify and detect finger movements for in-patient rehabilitation, finger Braille typing and directional bending of the human body. In this work, the average peak power of the flexible S-CBNG varied from 1.23 pW to 0.4 nW for flexion/extension movements of the right arm fingers. The reliability of the sensor depends on the generated electric potential, the location of the device on the forearm, the strain applied by the fingers, and the flexibility of the S-CBNG device. The proposed work is non-invasive, robust, cost-effective and it does not require external power for wearable and smart devices.

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  • Repositioning a passive patient in bed: Choosing an ergonomically advantageous assistive device
    22 février 2017
    Publication date: April 2017
    Source:Applied Ergonomics, Volume 60

    Author(s): Chava Weiner, Leonid Kalichman, Joseph Ribak, Deborah Alperovitch-Najenson

    Repositioning of passive patients in bed creates health risks to the nursing personnel. Therefore, appropriate assistive devices should be used. Our aim was to find the optimal assistive device for reducing musculoskeletal load while moving a passive patient in bed. Torso kinematic inputs evaluated by the Lumbar Motion Monitor (LMM) and perceived load (Borg scale) were measured in female nurses performing 27 patient transfers [represented by a mannequin weighing 55 (12 nurses), 65 (24 nurses) and 75 kg (12 nurses) in bed] using a regular sheet, a sliding sheet and a carrier. The lowest rates of perceived exertion were found when the sliding sheet and/or carrier were used, for all tasks (p ≤ 0.009). According to the predicted risk for Low Back Disorder (LBD) based on the LMM inputs, negligible differences between assistive devices were found. In a 75 kg mannequin, the participants were able to perform all tasks only by using a sliding sheet. Utilizing sliding sheets is an advantageous technique in comparison to traditional cotton sheets and even carriers.





  • Difference between male and female workers lifting the same relative load when palletizing boxes
    22 février 2017
    Publication date: April 2017
    Source:Applied Ergonomics, Volume 60

    Author(s): A. Plamondon, C. Larivière, D. Denis, H. Mecheri, I. Nastasia

    A few biomechanical studies have contrasted the work techniques of female and male workers during manual material handling (MMH). A recent study showed that female workers differed from males mostly in the strategy they used to lift 15-kg boxes from the ground, especially regarding task duration, knee and back postures and interjoint coordination. However, the lifting technique difference observed in females compared to males was perhaps due to a strength differences. The objective of this study was to test whether female workers would repeat the same lifting technique with a load adjusted to their overall strength (females: 10 kg; males: 15 kg), which can be considered a “relative load” since the overall back strength of females is 2/3 that of males. The task for the participants consisted in transferring boxes from one pallet to another. A dynamic 3D linked segment model was used to estimate the net moments at L5/S1, and different kinematic variables were considered. The results showed that the biomechanics of the lifting techniques used by males and females were similar in terms of task duration and cumulative loading, but different in terms of interjoint coordination pattern. The sequential interjoint coordination pattern previously seen in females with an absolute load (15 kg) was still present with the relative load, suggesting the influence of factors more intrinsically linked to sex. Considering that the female coordination pattern likely stretched posterior passive tissues when lifting boxes from the ground, potentially leading to higher risk of injury, the reason for this sex effect must be identified so that preventive interventions can be proposed.





  • Development of a usability evaluation method using natural product-use motion
    22 février 2017
    Publication date: April 2017
    Source:Applied Ergonomics, Volume 60

    Author(s): Joonho Chang, Kihyo Jung, Wonsup Lee, Heecheon You

    The present study developed and tested a new usability evaluation method which considers natural product-use motions. The proposed method measures both natural product-use motions (NMs) and actual product-use motions (AMs) for a product using an optical motion capture system and examines the usability of the product based on motion similarity (MS; %) between NMs and AMs. The proposed method was applied to a usability test of four vacuum cleaners (A, B, C, and D) with 15 participants and their MSs were compared with EMG measurements and subjective discomfort ratings. Cleaners A (44.6%) and C (44.2%) showed higher MSs than cleaners B (42.9%) and D (41.7%); the MSs mostly corresponded to the EMG measurements, which could indicate that AMs deviated from NMs may increase muscular efforts. However, the MSs were slightly different from the corresponding discomfort ratings. The proposed method demonstrated its usefulness in usability testing, but further research is needed with various products to generalize its effectiveness.





  • Effects of display curvature, display zone, and task duration on legibility and visual fatigue during visual search task
    22 février 2017
    Publication date: April 2017
    Source:Applied Ergonomics, Volume 60

    Author(s): Sungryul Park, Donghee Choi, Jihhyeon Yi, Songil Lee, Ja Eun Lee, Byeonghwa Choi, Seungbae Lee, Gyouhyung Kyung

    This study examined the effects of display curvature (400, 600, 1200 mm, and flat), display zone (5 zones), and task duration (15 and 30 min) on legibility and visual fatigue. Each participant completed two 15-min visual search task sets at each curvature setting. The 600-mm and 1200-mm settings yielded better results than the flat setting in terms of legibility and perceived visual fatigue. Relative to the corresponding centre zone, the outermost zones of the 1200-mm and flat settings showed a decrease of 8%–37% in legibility, whereas those of the flat setting showed an increase of 26%–45% in perceived visual fatigue. Across curvatures, legibility decreased by 2%–8%, whereas perceived visual fatigue increased by 22% during the second task set. The two task sets induced an increase of 102% in the eye complaint score and a decrease of 0.3 Hz in the critical fusion frequency, both of which indicated an increase in visual fatigue. In summary, a curvature of around 600 mm, central display zones, and frequent breaks are recommended to improve legibility and reduce visual fatigue.





  • Effect of hammer mass on upper extremity joint moments
    22 février 2017
    Publication date: April 2017
    Source:Applied Ergonomics, Volume 60

    Author(s): Nilanthy Balendra, Joseph E. Langenderfer

    This study used an OpenSim inverse-dynamics musculoskeletal model scaled to subject-specific anthropometrics to calculate three-dimensional intersegmental moments at the shoulder, elbow and wrist while 10 subjects used 1 and 2 lb hammers to drive nails. Motion data were collected via an optoelectronic system and the interaction of the hammer with nails was recorded with a force plate. The larger hammer caused substantial increases (50–150%) in moments, although increases differed by joint, anatomical component, and significance of the effect. Moment increases were greater in cocking and strike/follow-through phases as opposed to swinging and may indicate greater potential for injury. Compared to shoulder, absolute increases in peak moments were smaller for elbow and wrist, but there was a trend toward larger relative increases for distal joints. Shoulder rotation, elbow varus-valgus and pronation-supination, and wrist radial-ulnar deviation and rotation demonstrated large relative moment increases. Trial and phase durations were greater for the larger hammer. Changes in moments and timing indicate greater loads on musculoskeletal tissues for an extended period with the larger hammer. Additionally, greater variability in timing with the larger hammer, particularly for cocking phase, suggests differences in control of the motion. Increased relative moments for distal joints may be particularly important for understanding disorders of the elbow and wrist associated with hammer use.





  • Effects of button position on a soft keyboard: Muscle activity, touch time, and discomfort in two-thumb text entry
    22 février 2017
    Publication date: April 2017
    Source:Applied Ergonomics, Volume 60

    Author(s): Joonho Chang, Bori Choi, Amir Tjolleng, Kihyo Jung

    Intensive use of the thumbs for text entry on smartphones may contribute to discomfort, pain, or musculoskeletal disorders. This study investigated the effect of twenty-five button positions (5 rows × 5 columns) on a soft keyboard for two-thumb entry. Two experiments measured muscle activity, touch time, and discomfort as a function of the button positions. In Phase I, the muscle activities of two intrinsic (abductor pollicis brevis and first dorsal interossei) and two extrinsic (abductor pollicis longus and extensor digitorum communis) muscles associated with thumb motions were observed for ten college students (age: 24.2). In Phase II, touch time and discomfort were measured for 40 college students (age: 23.6). The results demonstrated that the %MVCs of the intrinsic muscles significantly increased when the thumbs flexed and abducted. Also, the button positions near the rest positions of the thumbs resulted in significantly shorter touch times (0.66 s) and lower discomfort ratings (0.70 pt) than their peripheral buttons (0.76 s; 2.29 pt).





  • The influence of a semi-reclined seated posture on head and neck kinematics and muscle activity while reading a tablet computer
    22 février 2017
    Publication date: April 2017
    Source:Applied Ergonomics, Volume 60

    Author(s): Ethan C. Douglas, Kaitlin M. Gallagher

    Increased tablet computer usage calls for a proper understanding of potential injury risks from these devices. The purpose of this study was to assess the influence of tablet computer reading postures on head and neck flexion and muscle activity. Nineteen participants completed read a tablet computer in four different postures (standard computer monitor, tablet on a desk, tablet in the lap, semi-reclined with tablet in the lap). Reading the tablet in a semi-reclined trunk posture with the tablet in one's lap increased (p < 0.001) neck flexion angle (71.6%ROM) relative to reading from the standard computer monitor (6.39%ROM). Head flexion in the semi-reclined posture (19.7%ROM) and muscle activity (8.88%MVC) were similar to when reading from a standard computer monitor. Despite potentially reducing the gravitational moment produced by the head, the semi-reclined position could still compromise the force capabilities of the neck extensor musculature and result in increased strain on the passive tissues of the spine. Future work should assess how the semi-reclined position influences cervical intervertebral angles and passive tissue properties of the cervical spine. Overall, more research needs to be conducted on thoracic spine kinematics while reading a tablet computer.





  • Job rotation: Effects on muscular activity variability
    22 février 2017
    Publication date: April 2017
    Source:Applied Ergonomics, Volume 60

    Author(s): Andres C. Rodriguez, Lope H. Barrero

    Job rotation strategies have been used for years as an administrative intervention to reduce the risk of musculoskeletal disorders. The benefits of job rotation have been hypothesized to occur via changes in muscular activity variability (MAV). However, the effect of job rotation on MAV has not been fully analyzed in a literature review. A wide search was conducted to identify studies testing the effect of different job rotation strategies on MAV. Twenty-six studies of acceptable quality were included. Several studies on different types of tasks supported the view that job rotation can increase muscular activity variability, particularly with strategies such as alternating tasks and pace changes. However, it remains uncertain whether such variability changes immediately translate into benefits for the worker because little evidence was found that showed simultaneous changes in different muscular groups. Additionally, variability was occasionally achieved at the expense of average activity in the assessed muscles.





  • Effects of localized versus widespread TMD pain on sleep parameters in patients with bruxism: A single-night polysomnographic study
    22 février 2017
    Publication date: April 2017
    Source:Archives of Oral Biology, Volume 76

    Author(s): José Tadeu Tesseroli de Siqueira, Cinara Maria Camparis, Silvia Regina Dowgan Tesseroli de Siqueira, Manoel Jacobsen Teixeira, Lia Bittencourt, Sérgio Tufik

    Objective The purpose of this study was to investigate whether the presence of concomitant widespread pain could influence the polysomnographic characteristics of patients with Sleep Bruxism(SB) and chronic masticatory muscle pain(TMD). Methods 20 SB/TMD patients (17 women and 3 men) were evaluated according to the RDC/TMD questionnaire; and were divided into two groups according to the absence (Group A) or presence (Group B) of widespread pain. They were evaluated in a one night polysomnography paradigm. Results Group B had lower sleep efficiency (p=0.034) and higher mean age (p=0.000) than Group A. Self-reported orofacial pain complaints, clinical and emotional aspects (RDC/TMD Axis I and II), and SB PSG parameters were similar in both groups; all patients had masticatory myofascial pain and the pain characteristics were bilateral location (95.0%) and tightness/pressure quality (70.0%). Conclusions At a single-night PSG, SB/TMD patients with widespread pain presented lower PSG sleep efficiency and higher mean age.





  • Laryngeal myofascial pain syndrome as a new diagnostic entity of dysphonia
    22 février 2017
    Publication date: April 2017
    Source:Auris Nasus Larynx, Volume 44, Issue 2

    Author(s): Soo Yeon Jung, Hae Sang Park, Hasuk Bae, Jeong Hyun Yoo, Hyung Jun Park, Kee Duk Park, Han Su Kim, Sung Min Chung

    Objective To consider the feasibility of diagnosing intrinsic laryngeal muscle myofascial pain syndrome (MPS) in dysphonic patients who demonstrated immediate symptom and stroboscopic finding improvement after laryngeal electromyography (LEMG) without further treatment. Methods A chart review of patients who showed subtle vocal fold movement abnormalities on a stroboscopic examination and underwent ultrasonography (US)-guided LEMG was performed. Patients with vocal fold paralysis, mucosal lesions, spasmodic dysphonia, and vocal tremor on stroboscopic examination were excluded. Among them, patients with normal EMG findings were included in this study. The patients who reported voice symptom improvement after LEMG without further treatment were placed in laryngeal MPS (LMPS) group and the other patients were placed in non-laryngeal MPS (non-MPS) group. Predisposing factors, voice symptom, symptom-duration, and stroboscopic findings of these patients were reviewed. Results Among the 16 patients, LEMG findings were normal, five (31%) were included in the LMPS group and the other 11 patients (69%) were included in the non-MPS group. All LMPS group patients had a history of voice abuse and reported odynophonia. The Korean Voice Handicap Index-10 score decreased significantly after US-guided LEMG without additional treatment in the LMPS group. The stroboscopic findings revealed that vocal fold hypomobility was the most common finding in the LMPS group, and two patients showed a muscle tension dysphonia pattern. The LMPS groups showed improvement of vocal fold mobility on 1-week stroboscopic evaluation. Conclusion LMPS is a potential diagnosis for patients with vocal fold hypomobility finding on stroboscopic findings but with normal EMG results. Diagnosis of LMPS could be considered in patients who showed symptom and vocal fold movement improvement after LEMG.





  • Biodegradable scaffolds promote tissue remodeling and functional improvement in non-human primates with acute spinal cord injury
    22 février 2017
    Publication date: April 2017
    Source:Biomaterials, Volume 123

    Author(s): Jonathan R. Slotkin, Christopher D. Pritchard, Brian Luque, Janice Ye, Richard T. Layer, Mathew S. Lawrence, Timothy M. O'Shea, Roland R. Roy, Hui Zhong, Isabel Vollenweider, V. Reggie Edgerton, Grégoire Courtine, Eric J. Woodard, Robert Langer

    Tissue loss significantly reduces the potential for functional recovery after spinal cord injury. We previously showed that implantation of porous scaffolds composed of a biodegradable and biocompatible block copolymer of Poly-lactic-co-glycolic acid and Poly-l-lysine improves functional recovery and reduces spinal cord tissue injury after spinal cord hemisection injury in rats. Here, we evaluated the safety and efficacy of porous scaffolds in non-human Old-World primates (Chlorocebus sabaeus) after a partial and complete lateral hemisection of the thoracic spinal cord. Detailed analyses of kinematics and muscle activity revealed that by twelve weeks after injury fully hemisected monkeys implanted with scaffolds exhibited significantly improved recovery of locomotion compared to non-implanted control animals. Twelve weeks after injury, histological analysis demonstrated that the spinal cords of monkeys with a hemisection injury implanted with scaffolds underwent appositional healing characterized by a significant increase in remodeled tissue in the region of the hemisection compared to non-implanted controls. The number of glial fibrillary acidic protein immunopositive astrocytes was diminished within the inner regions of the remodeled tissue layer in treated animals. Activated macrophage and microglia were present diffusely throughout the remodeled tissue and concentrated at the interface between the preserved spinal cord tissue and the remodeled tissue layer. Numerous unphosphorylated neurofilament H and neuronal growth associated protein positive fibers and myelin basic protein positive cells may indicate neural sprouting inside the remodeled tissue layer of treated monkeys. These results support the safety and efficacy of polymer scaffolds in a primate model of acute spinal cord injury. A device substantially similar to the device described here is the subject of an ongoing human clinical trial.





  • Long-term usability and bio-integration of polyimide-based intra-neural stimulating electrodes
    22 février 2017
    Publication date: April 2017
    Source:Biomaterials, Volume 122

    Author(s): S. Wurth, M. Capogrosso, S. Raspopovic, J. Gandar, G. Federici, N. Kinany, A. Cutrone, A. Piersigilli, N. Pavlova, R. Guiet, G. Taverni, J. Rigosa, P. Shkorbatova, X. Navarro, Q. Barraud, G. Courtine, S. Micera

    Stimulation of peripheral nerves has transiently restored lost sensation and has the potential to alleviate motor deficits. However, incomplete characterization of the long-term usability and bio-integration of intra-neural implants has restricted their use for clinical applications. Here, we conducted a longitudinal assessment of the selectivity, stability, functionality, and biocompatibility of polyimide-based intra-neural implants that were inserted in the sciatic nerve of twenty-three healthy adult rats for up to six months. We found that the stimulation threshold and impedance of the electrodes increased moderately during the first four weeks after implantation, and then remained stable over the following five months. The time course of these adaptations correlated with the progressive development of a fibrotic capsule around the implants. The selectivity of the electrodes enabled the preferential recruitment of extensor and flexor muscles of the ankle. Despite the foreign body reaction, this selectivity remained stable over time. These functional properties supported the development of control algorithms that modulated the forces produced by ankle extensor and flexor muscles with high precision. The comprehensive characterization of the implant encapsulation revealed hyper-cellularity, increased microvascular density, Wallerian degeneration, and infiltration of macrophages within the endoneurial space early after implantation. Over time, the amount of macrophages markedly decreased, and a layer of multinucleated giant cells surrounded by a capsule of fibrotic tissue developed around the implant, causing an enlargement of the diameter of the nerve. However, the density of nerve fibers above and below the inserted implant remained unaffected. Upon removal of the implant, we did not detect alteration of skilled leg movements and only observed mild tissue reaction. Our study characterized the interplay between the development of foreign body responses and changes in the electrical properties of actively used intra-neural electrodes, highlighting functional stability of polyimide-based implants over more than six months. These results are essential for refining and validating these implants and open a realistic pathway for long-term clinical applications in humans.





  • Motor unit profile: A new way to describe the scanning-EMG potential
    22 février 2017
    Publication date: April 2017
    Source:Biomedical Signal Processing and Control, Volume 34

    Author(s): Íñigo Corera, Armando Malanda, Javier Rodriguez-Falces, Sonia Porta, Javier Navallas

    The motor unit profile, a representation of the trajectories of positive and negative turns of a scanning-EMG signal, is a new way to characterize the motor unit potential. Such characterization allows quantification of the scanning-EMG signal's complexity, which is closely related to the anatomy and physiology of the motor unit. To extract the motor unit profile, an algorithm that detects the turns of the scanning-EMG signal and links them using point-tracking techniques has been developed. The performance of this algorithm is sensitive to three parameters: the turn detection threshold, the maximum tracking interval threshold, and the trajectory purge threshold. Real scanning-EMG signals have been used to analyze the algorithm's behavior and the influence of the algorithm's parameters and to determine which parameter values provide the best performance.





  • Algorithm for EMG noise level approximation in ECG signals
    22 février 2017
    Publication date: April 2017
    Source:Biomedical Signal Processing and Control, Volume 34

    Author(s): Mohamed Marouf, Lazar Saranovac, Goran Vukomanovic

    In this paper, we introduce an approach for Electromyogram (EMG) noise level approximation in Electrocardiogram (ECG) signals. The stationary wavelet transform (SWT) is used to find efficient translation-invariant approximation of EMG noise. This is accomplished in the form of reference signal extracted as an estimation of the signal quality vs. EMG noise. The reference signal is built and then normalized after considering different heart rates and rhythms which increases its robustness and reliability to give accurate results regardless of input signal rhythm. Additionally, four applications of the extracted reference signal are suggested in this paper. For evaluation purposes both real EMG and artificial noises were used. The tested ECG signals are from MIT-BIH Arrhythmia Database Directory. The correlation coefficient between the added noise and the reference signal were computed for moving windows over the signal. Finally, the correlation between beats detection and reference signal was computed and presented. Reference signal gave high correlation with false positive values. Most false positives caused by EMG noise occur in intervals of greater amplitude reference signal and vice versa.





  • Objects rapidly prime the motor system when located near the dominant hand
    22 février 2017
    Publication date: April 2017
    Source:Brain and Cognition, Volume 113

    Author(s): Paula J. Rowe, Corinna Haenschel, Maciej Kosilo, Kielan Yarrow

    Objects are said to automatically “afford” various actions depending upon the motor repertoire of the actor. Such affordances play a part in how we prepare to handle or manipulate tools and other objects. Evidence obtained through fMRI, EEG and TMS has proven that this is the case but, as yet, the temporal evolution of affordances has not been fully investigated. The aim here was to further explore the timing of evoked motor activity using visual stimuli tailored to drive the motor system. Therefore, we presented three kinds of stimuli in stereoscopic depth; whole hand grasp objects which afforded a power-grip, pinch-grip objects which afforded a thumb and forefinger precision-grip and an empty desk, affording no action. In order to vary functional motor priming while keeping visual stimulation identical, participants adopted one of two postures, with either the dominant or non-dominant hand forward. EEG data from 29 neurologically healthy subjects were analysed for the N1 evoked potential, observed in visual discrimination tasks, and for the N2 ERP component, previously shown to correlate with affordances (Proverbio, Adorni, & D’Aniello, 2011). We observed a link between ERPs, previously considered to reflect motor priming, and the positioning of the dominant hand. A significant interaction was detected in the left-hemisphere N2 between the participants’ posture and the object category they viewed. These results indicate strong affordance-related activity around 300ms after stimulus presentation, particularly when the dominant hand can easily reach an object.





  • Peripheral nerve ultrasonography in patients with transthyretin amyloidosis
    22 février 2017
    Publication date: April 2017
    Source:Clinical Neurophysiology, Volume 128, Issue 4

    Author(s): Simon Podnar, Stayko Sarafov, Ivailo Tournev, Gregor Omejec, Janez Zidar

    Objective To systematically study peripheral nerve morphology in patients with transthyretin (TTR) amyloidosis and TTR gene mutation carriers using high-resolution ultrasonography (US). Methods In this prospective cross-sectional study we took a structured history, performed neurological examination, and measured peripheral nerve cross-sectional areas (CSAs) bilaterally at 28 standard locations using US. Demographic and US findings were compared to controls. Results Peripheral nerve CSAs were significantly larger in 33 patients with familial amyloid polyneuropathy (FAP) compared to 50 controls, most dramatically at the common entrapment sites (median nerve at the wrist, ulnar nerve at the elbow), and in the proximal nerve segments (median nerve in the upper arm, sciatic nerve in the thigh). Findings in 21 asymptomatic TTR gene mutation carriers were less marked compared to controls, with CSAs being larger only in the median nerve in the upper arm. Nerve CSAs correlated with abnormalities on nerve conduction studies. Conclusion Using US, we confirmed previous pathohistological and imaging reports in FAP of the most pronounced peripheral nerve thickening in the proximal limb segments. Significance Similar to US findings in diabetic and vasculitic neuropathies these predominantly proximal locations of nerve thickening may be attributed to ischaemic nerve damage caused by poor perfusion in the watershed zones along proximal limb segments.





 

Mis à jour le 03 avril 2013