173 research outputs found

    Material properties of the heel fat pad across strain rates

    Get PDF
    The complex structural and material behaviour of the human heel fat pad determines the transmission of plantar loading to the lower limb across a wide range of loading scenarios; from locomotion to injurious incidents. The aim of this study was to quantify the hyper-viscoelastic material properties of the human heel fat pad across strains and strain rates. An inverse finite element (FE) optimisation algorithm was developed and used, in conjunction with quasi-static and dynamic tests performed to five cadaveric heel specimens, to derive specimen-specific and mean hyper-viscoelastic material models able to predict accurately the response of the tissue at compressive loading of strain rates up to 150 s−1. The mean behaviour was expressed by the quasi-linear viscoelastic (QLV) material formulation, combining the Yeoh material model (C10=0.1MPa, C30=7MPa, K=2GPa) and PronyŚłs terms (A1=0.06, A2=0.77, A3=0.02 for τ1=1ms, τ2=10ms, τ3=10s). These new data help to understand better the functional anatomy and pathophysiology of the foot and ankle, develop biomimetic materials for tissue reconstruction, design of shoe, insole, and foot and ankle orthoses, and improve the predictive ability of computational models of the foot and ankle used to simulate daily activities or predict injuries at high rate injurious incidents such as road traffic accidents and underbody blast

    Texture-based estimation of physical characteristics of sand grains

    Get PDF
    The common occurrence and transportability of quartz sand grains make them useful for forensic analysis, providing that grains can be accurately and consistently designated into prespecified types. Recent advances in the analysis of surface texture features found in scanning electron microscopy images of such grains have advanced this process. However, this requires expert knowledge that is not only time intensive, but also rare, meaning that automation is a highly attractive prospect if it were possible to achieve good levels of performance. Basic Image Feature Columns (BIF Columns), which use local symmetry type to produce a highly invariant yet distinctive encoding, have shown leading performance in standard texture recognition tasks used in computer vision. However, the system has not previously been tested on a real world problem. Here we demonstrate that the BIF Column system offers a simple yet effective solution to grain classification using surface texture. In a two class problem, where human level performance is expected to be perfect, the system classifies all but one grain from a sample of 88 correctly. In a harder task, where expert human performance is expected to be significantly less than perfect, our system achieves a correct classification rate of over 80%, with clear indications that performance can be improved if a larger dataset were available. Furthermore, very little tuning or adaptation has been necessary to achieve these results giving cause for optimism in the general applicability of this system to other texture classification problems in forensic analysis

    Rapid-sequence MRI for long-term surveillance for paraganglioma and phaeochromocytoma in patients with succinate dehydrogenase (SDHx) mutations

    Get PDF
    INTRODUCTION: Patients with SDHx mutations need long-term radiological surveillance for the development of paragangliomas and phaeochromocytomas, but no longitudinal data exist. We assessed the performance of rapid-sequence non-contrast magnetic resonance imaging (MRI) in the long-term monitoring of patients with SDHx mutations. METHODS: Retrospective study between 2005-2015 at a University Hospital and regional endocrine genetics referral center. Clinical and imaging data of forty-seven patients with SDHx mutations [SDHB (36), SDHC (6), SDHD (5)] who had surveillance for detection of paragangliomas by rapid-sequence non-contrast MRI (base of skull to pubic symphysis) were collected. RESULTS: Twelve index cases (9 SDHB, 1 SDHC, 2 SDHD) and 35 mutation-positive relatives were monitored for a mean of 6.4 years (range 3.1 to 10.0 years). Mean age at the end of the study: SDHB 46.9+/-17.6 years; SDHC 42.3+/-24.4 years; SDHD 54.9 +/- 10.6 years. Excluding imaging at initial diagnosis of index cases forty-three patients underwent 116 rapid-sequence MRI scans: 83 scans were negative and 31 scans were positive for a sPGL/HNPGL in 13 patients. Most patients had multiple scans [n=number of patients (number of rapid-sequence MRI scans during screening)]; n=9 (2), n=20 (3), n=6 (4), n=1 (6). Nine patients (3 index) were diagnosed with new paragangliomas during surveillance and non-operated tumour size was monitored in 9 patients. There were two false positive scans (1.6%). Scans were repeated every 27 +/- 9 months. CONCLUSIONS: Biannual rapid-sequence non-contrast MRI is effective to monitor patients with SDHx mutations for detection of new tumours and monitoring of known tumours

    Inhibition and young children's performance on the Tower of London task

    Get PDF
    Young children, when performing problem solving tasks, show a tendency to break task rules and produce incomplete solutions. We propose that this tendency can be explained by understanding problem solving within the context of the development of “executive functions” – general cognitive control functions, which serve to regulate the operation of the cognitive system. This proposal is supported by the construction of two computational models that simulate separately the performance of 3–4 year old and 5–6 year old children on the Tower of London planning task. We seek in particular to capture the emerging role of inhibition in the older group. The basic framework within which the models are developed is derived from Fox and Das’ Domino model [Fox, J., & Das, S. (2000). Safe and sound: Artificial intelligence in hazardous applications. Cambridge, MA: MIT Press] and Norman and Shallice’s [Norman, D.A., & Shallice, T. (1986). Attention to action: Willed and automatic control of behaviour. In R. Davidson, G. Schwartz, & D. Shapiro (Eds.), Consciousness and Self Regulation (Vol. 4). New York: Plenum] theory of willed and automatic action. Two strategies and a simple perceptual bias are implemented within the models and comparisons between model and child performance reveal a good fit for the key dependent measures (number of rule breaks and percentage of incomplete solutions) of the two groups

    Psychosocial interventions for adults with visible differences: A systematic review

    Get PDF
    Background: Some individuals with visible differences have been found to experience psychosocial adjustment problems that can lead to social anxiety and isolation. Various models of psychosocial intervention have been used to reduce social anxiety and appearance related distress in this population. The objective of this review was to update a previous systematic review assessing the efficacy of psychosocial intervention programs for adults with visible differences. The original review (Bessell & Moss, 2007) identified 12 papers for inclusion. Methods: A search protocol identified studies from 13 electronic journal databases. Methods: Studies were selected in accordance with pre-set inclusion criteria and relevant data were extracted. Results: This update identified an additional four papers that met the inclusion criteria. Two papers provided very limited evidence for the efficacy of a combined cognitive-behavioural and social skills training approach. None of the papers provided sufficient evidence for the optimal duration, intensity or setting of psychosocial interventions for this population. Discussion: The review concluded that a greater number of Randomised Controlled Trials and experimental studies were required to increase the methodological validity of intervention studies

    Global nuts and local mangoes: a critical reading of the UNDP Growing Sustainable Business Initiative in Kenya

    Full text link
    This article provides a conceptual and empirical assessment of UN brokered partnerships that seek to deepen or create inclusive and sustainable agricultural supply chains in sub-Saharan Africa. More specifically it appraises the decision-making mechanisms, processes of partnership brokerage and project implementation within the UNDP Growing Sustainable Business Initiative (GSB) in Kenya. The paper argues that the lack of bottom-up participation in decision-making mechanisms and the predominantly economic imperatives driving the GSB partnership projects have failed to reach out to the partnerships’ intended beneficiaries—Kenyan small producers of nuts and mangoes. In conclusion it is suggested that opening up the GSB platform might hold the promise of reconciling sustainable business models with (some) poverty reduction

    Campylobacter infection of broiler chickens in a free-range environment

    Get PDF
    Campylobacter jejuni is the most common cause of bacterial gastroenteritis worldwide, with contaminated chicken meat considered to represent a major source of human infection. Biosecurity measures can reduce C. jejuni shedding rates of housed chickens, but the increasing popularity of free-range and organic meat raises the question of whether the welfare benefits of extensive production are compatible with food safety. The widespread assumption that the free-range environment contaminates extensively reared chickens has not been rigorously tested. A year-long survey of 64 free-range broiler flocks reared on two sites in Oxfordshire, UK, combining high-resolution genotyping with behavioural and environmental observations revealed: (i) no evidence of colonization of succeeding flocks by the C. jejuni genotypes shed by preceding flocks, (ii) a high degree of similarity between C. jejuni genotypes from both farm sites, (iii) no association of ranging behaviour with likelihood of Campylobacter shedding, and (iv) higher genetic differentiation between C. jejuni populations from chickens and wild birds on the same farm than between the chicken samples, human disease isolates from the same region and national samples of C. jejuni from chicken meat
    • 

    corecore