A hysteretic multiscale formulation for nonlinear dynamic analysis of composite materials

This article has been made available through the Brunel Open Access Publishing Fund.A new multiscale finite element formulation is presented for nonlinear dynamic analysis of heterogeneous structures. The proposed multiscale approach utilizes the hysteretic finite element method to model the microstructure. Using the proposed computational scheme, the micro-basis functions, that are used to map the microdisplacement components to the coarse mesh, are only evaluated once and remain constant throughout the analysis procedure. This is accomplished by treating inelasticity at the micro-elemental level through properly defined hysteretic evolution equations. Two types of imposed boundary conditions are considered for the derivation of the multiscale basis functions, namely the linear and periodic boundary conditions. The validity of the proposed formulation as well as its computational efficiency are verified through illustrative numerical experiments

Serum tartrate-resistant acid phosphatase 5b activity as a prognostic marker of survival in breast cancer with bone metastasis

<p>Abstract</p> <p>Background</p> <p>Serum tartrate-resistant acid phosphatase 5b (TRACP 5b) activity is a marker of osteoclast number and is elevated in breast cancer (BC) patients with extensive bone metastasis, which might in turn reflect the tumour burden. We tested the hypothesis that baseline serum TRACP 5b activity and its interval change are potential prognostic markers of survival in BC patients with bone metastasis.</p> <p>Methods</p> <p>We analyzed the data from previous prospective studies. A total of 100 patients with newly diagnosed bone metastasis were included. Cox proportional regression model was used to evaluate the correlation between the overall survival time (OS) and baseline serum TRACP 5b activity and its interval changes. The least significant change (LSC) of TRACP 5b was calculated from data obtained from 15 patients with early BC.</p> <p>Results</p> <p>Estrogen receptor status (Hazard Ratio (HR) = 0.397; <it>p </it>= 0.003) and visceral metastasis (HR = 0.492; <it>p </it>= 0.0045) were significantly correlated with OS. The OS was significantly shorter in those patients with higher baseline TRACP 5b activity based on a cut-off value to delineate the highest tertile (HR = 3.524; <it>p </it>< 0.0001). Further analysis demonstrated that among patients in the highest tertile, OS was significantly longer in those patients who had achieved a decrease of serum TRACP 5b activity greater than the LSC (38.59%) (<it>p </it>= 0.0015).</p> <p>Conclusions</p> <p>We found that TRACP 5b activity and its interval change after treatment bore a prognostic role in BC patients with bone metastasis and a high baseline serum TRACP 5b activity. Further prospective phase II study is necessary to confirm these results.</p

Bioenergetics Failure and Oxidative Stress in Brain Stem Mediates Cardiovascular Collapse Associated with Fatal Methamphetamine Intoxication

Background: Whereas sudden death, most often associated with cardiovascular collapse, occurs in abusers of the psychostimulant methamphetamine (METH), the underlying mechanism is much less understood. The demonstration that successful resuscitation of an arrested heart depends on maintained functionality of the rostral ventrolateral medulla (RVLM), which is responsible for the maintenance of stable blood pressure, suggests that failure of brain stem cardiovascular regulation, rather than the heart, holds the key to cardiovascular collapse. We tested the hypothesis that cessation of brain stem cardiovascular regulation because of a loss of functionality in RVLM mediated by bioenergetics failure and oxidative stress underlies the cardiovascular collapse elicited by lethal doses of METH. Methodology/Principal Findings: Survival rate, cardiovascular responses and biochemical or morphological changes in RVLM induced by intravenous administration of METH in Sprague-Dawley rats were investigated. High doses of METH induced significant mortality within 20 min that paralleled concomitant the collapse of arterial pressure or heart rate and loss of functionality in RVLM. There were concurrent increases in the concentration of METH in serum and ventrolateral medulla, along with tissue anoxia, cessation of microvascular perfusion and necrotic cell death in RVLM. Furthermore, mitochondrial respiratory chain enzyme activity or electron transport capacity and ATP production in RVLM were reduced, and mitochondria-derived superoxide anion level was augmented. All those detrimental physiological and biochemica