1,086 research outputs found
Material properties of the heel fat pad across strain rates
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 Prony׳s 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
Buoyancy-driven flow inside an asymmetrically heated cavity
Buoyancy-driven flows inside enclosures are in the center of problems related to heat transfer because they can provide a significant insight into the physical mechanisms of heat transfer. Typical examples of such flows include Rayleigh–Bénard convection, differentially heated cavities and partially divided enclosures. In the present study, the buoyancy-driven flow inside an asymmetrically heated closed cavity is investigated and proposed as a benchmark case for future studies to assess the accuracy of simulations and to help in the validation of coarsened turbulence models. Additionally, from an application perspective such a configuration is highly relevant, e.g., in view of its similarity with passive solar systems such as ventilated building facades (Puangsombuta et al, J Fluid Mech 42(6):2218–2226, 2007, [1]) and Trombe walls (Zamora and Kaiser, Heat Mass Transf 45(11):1393–1407, 2009, [2]).</p
Microwave system for in-situ curing of concrete repair
This paper presents some results of the FP7 MCure project on the development of a prototype system for microwave curing of concrete and concrete repair. Microwave curing of concrete provides higher early age strength compared to normally cured concrete. A prototype microwave curing system has been developed based on laboratory results on microwave curing of concrete repair materials. Subsequently, field trials were carried out to validate the Pre-Industrial Prototype system by testing elements of four commercial repair materials and a CEM II cement concrete. The prototype control system was used to record data such as surface temperature of concrete, moisture content of concrete and output power of the magnetron. In addition, the relationships between microwave output power, temperature and volume of repair of the field trials were derived and compared with the laboratory results. The prototype microwave system performed effectively. Slabs of dimensions 1 m x 1 m and depths up to 64 mm were microwave cured to temperature up to 45 ◦C for the predetermined time
Reform paradoxes: Academic freedom and governance in Greek and Turkish higher education
This study evaluates the impact of higher education reforms, implemented in the early 1980s in Greece and Turkey, due to preceding student and wider political radicalization, on academic freedom. It highlights a paradox, namely that authoritarian corporatism in Turkey inadvertently facilitated academic freedom in higher education, whereas in Greece participatory majoritarianism ended up stifling academic freedom. Authoritarian corporatism in Turkey mandated the introduction of private universities. These expanded academic freedom within the wider national goal of the country's European Union membership. Participatory majoritarianism in Greece conversely mandated student organisation participation in the governance of Greek higher education. These acquired powerful rent-seeking interests, which have progressively constricted academic freedom. © 2012 Copyright Taylor and Francis Group, LLC
Utility of VS38c in the diagnostic and prognostic assessment of osteosarcoma and other bone tumours/tumour-like lesions
BACKGROUND: VS38c is a monoclonal antibody that recognises a rough endoplasmic reticulum (rER) intracellular antigen termed cytoskeleton-linking membrane protein 63. rER is typically found in viable tumour cells and is abundant in osteosarcoma cells. The aim of this study was to determine the diagnostic and prognostic utility of VS38c in the histological assessment of osteosarcoma and other bone tumours/tumour-like leisons. METHODS: Immunohistochemical staining with VS38c was carried out on formalin-fixed specimens of osteosarcoma (pre/post-chemotherapy) and a wide range of benign and malignant bone lesions. In addition, VS38c staining of cultures of MG63 and Sa0S2 osteosarcoma cell cultures. (±cisplatin and actinomycin D-treatment) was analysed. RESULTS: VS38c strongly stained tumour cells in all low-grade and high-grade osteosarcomas and in undifferentiated sarcomas and high-grade chondrosarcomas. There was little or no VS38c staining of low-grade chondrosarcomas or chordomas and variable staining of Ewing sarcomas. Osteoblasts in benign bone-forming tumours and mononuclear stromal cells in chondroblastomas, giant cell tumours and non-ossifying fibromas strongly stained for VS38c. VS38c staining was absent in cisplatin and actinomycin D treated Sa0S2 and MG63 cells. In specimens of osteosarcoma post-neoadjuvant therapy, VS38c staining was absent in most morphologically necrotic areas of tumor although some cells with pyknotic nuclei stained for VS38c in these areas. Most tumour cells exhibiting atypical nuclear forms were not stained by VS38c. CONCLUSIONS: Our findings show that VS38c is a sensitive but not specific diagnostic marker of osteosarcoma. Staining with VS38c identifies viable osteosarcoma cells, a feature which may be useful in the assessment of percentage tumour necrosis post-neoadjuvant chemotherapy
Morphological, histochemical, and interstitial pressure changes in the tibialis anterior muscle before and after aortofemoral bypass in patients with peripheral arterial occlusive disease
BACKGROUND: Morphological and electrophysiological studies of ischemic muscles in peripheral arterial disease disclosed evidence of denervation and fibre atrophy. The purpose of the present study is to describe morphological changes in ischemic muscles before and after reperfusion surgery in patients with peripheral occlusive arterial disease, and to provide an insight into the effect of reperfusion on the histochemistry of the reperfused muscle. METHODS: Muscle biopsies were obtained from the tibialis anterior of 9 patients with chronic peripheral arterial occlusive disease of the lower extremities, before and after aortofemoral bypass, in order to evaluate the extent and type of muscle fibre changes during ischemia and after revascularization. Fibre type content and muscle fibre areas were quantified using standard histological and histochemical methods and morphometric analysis. Each patient underwent concentric needle electromyography, nerve conduction velocity studies, and interstitial pressure measurements. RESULTS: Preoperatively all patients showed muscle fibre atrophy of both types, type II fibre area being more affected. The mean fibre cross sectional area of type I was 3,745 μm(2) and of type II 4,654 μm(2) . Fibre-type grouping, great variation in fibre size and angular fibres were indicative of chronic dennervation-reinnervation, in the absence of any clinical evidence of a neuropathic process. Seven days after the reperfusion the areas of both fibre types were even more reduced, being 3,086 μm(2) for type I and 4,009 μm(2) for type II, the proportion of type I fibres, and the interstitial pressure of tibialis anterior were increased. CONCLUSIONS: The findings suggest that chronic ischemia of the leg muscles causes compensatory histochemical changes in muscle fibres resulting from muscle hypoxia, and chronic dennervation-reinnervation changes, resulting possibly from ischemic neuropathy. Reperfusion seems to bring the oxidative capacity of the previously ischemic muscle closer to normal
On the Number of Iterations for Dantzig-Wolfe Optimization and Packing-Covering Approximation Algorithms
We give a lower bound on the iteration complexity of a natural class of
Lagrangean-relaxation algorithms for approximately solving packing/covering
linear programs. We show that, given an input with random 0/1-constraints
on variables, with high probability, any such algorithm requires
iterations to compute a
-approximate solution, where is the width of the input.
The bound is tight for a range of the parameters .
The algorithms in the class include Dantzig-Wolfe decomposition, Benders'
decomposition, Lagrangean relaxation as developed by Held and Karp [1971] for
lower-bounding TSP, and many others (e.g. by Plotkin, Shmoys, and Tardos [1988]
and Grigoriadis and Khachiyan [1996]). To prove the bound, we use a discrepancy
argument to show an analogous lower bound on the support size of
-approximate mixed strategies for random two-player zero-sum
0/1-matrix games
Cyclization of PLP 139-151 peptide reduces its encephalitogenic potential in experimental autoimmune encephalomyelitis
Cyclic MOG₃₅–₅₅ ameliorates clinical and neuropathological features of experimental autoimmune encephalomyelitis
Rel-deficient T cells exhibit defects in production of interleukin 3 and granulocyte-macrophage colony-stimulating factor.
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