Biochemical Assessment of Stress in Cardiac Tissue in Response to Weightless Space Travel

The absence of unit gravity may cause physiological changes in the cardiovascular system. For instance, in the absence of Earth's gravity, venous return to the heart may increase due, in pan, to decreased pooling of the blood in the extremities. We hypothesize that this would produce an increase in the heart's work load ultimately resulting in hypertrophy

Elastoplastic and fracture behaviour of semi-crystalline polymers under multiaxial stress states

The deformation behaviour and fracture mechanisms of highdensity polyethylene (HDPE), polypropylene (PP) and polyamide 6 (PA 6) are investigated experimentally under different stress states and at different crosshead speeds of 1, 20 and 200 mm/min. Fracture surface morphologies were investigated in a series of specimens tested at 200 mm/min under combined tension/shear loading at three different loading angles ( ? = 0, 30deg and 90deg) at room temperature (RT) and 50 �C. In addition, the effects of notch profile radii (stress triaxiality) on HDPE, PP and PA 6 fracture behaviour have been studied at RT, using flat and cylindrical notched specimens. Specimens� geometries were carefully designed to achieve various loading conditions and allowing to explore initial stress triaxialities ranged from 0 in pure shear loading ( ? = 0�) to a maximum of 0.84 for flat notched specimens with radius of 5 mm. The yield load shows an explicit dependency on temperature and crosshead speed. The fracture surfaces analysed reveals damage mechanisms such as crazing, void and cavitation formation. Two or more mechanisms are predominant, which means that the stresses along fracture process are not uniform

Genetic polymorphisms of RANTES, IL1-A, MCP-1 and TNF-A genes in patients with prostate cancer

<p>Abstract</p> <p>Background</p> <p>Inflammation has been implicated as an etiological factor in several human cancers, including prostate cancer. Allelic variants of the genes involved in inflammatory pathways are logical candidates as genetic determinants of prostate cancer risk. The purpose of this study was to investigate whether single nucleotide polymorphisms of genes that lead to increased levels of pro-inflammatory cytokines and chemokines are associated with an increased prostate cancer risk.</p> <p>Methods</p> <p>A case-control study design was used to test the association between prostate cancer risk and the polymorphisms <it>TNF-A</it>-308 A/G (rs 1800629), <it>RANTES</it>-403 G/A (rs 2107538), <it>IL1-A</it>-889 C/T (rs 1800587) and <it>MCP-1 </it>2518 G/A (rs 1024611) in 296 patients diagnosed with prostate cancer and in 311 healthy controls from the same area.</p> <p>Results</p> <p>Diagnosis of prostate cancer was significantly associated with <it>TNF-A </it>GA + AA genotype (OR, 1.61; 95% CI, 1.09–2.64) and <it>RANTES </it>GA + AA genotype (OR, 1.44; 95% CI, 1.09–2.38). A alleles in <it>TNF-A </it>and <it>RANTES </it>influenced prostate cancer susceptibility and acted independently of each other in these subjects. No epistatic effect was found for the combination of different polymorphisms studied. Finally, no overall association was found between prostate cancer risk and <it>IL1-A </it>or <it>MCP-1 </it>polymorphisms.</p> <p>Conclusion</p> <p>Our results and previously published findings on genes associated with innate immunity support the hypothesis that polymorphisms in proinflammatory genes may be important in prostate cancer development.</p

A test-bed for researching the interactions of underexcitation and overexcitation limiters of synchronous generators with protection functions.

A test-bed implemented in a real-time digital simulation environment is presented in this article to perform coordination studies between protection functions and excitation limiters of automatic voltage regulators of synchronous generators. A hardware-in-the-loop simulation is implemented in laboratory to test and evaluate several protection schemes during underexcited and overexcited events. The interactions among the underexcitation and overexcitation limiters (UEL and OEL) with these protection functions are investigated, and the best settings for their coordination are proposed. This article increases the scope of [1] and [2] by including the interactions among the protection functions ANSI 24 (V/Hz), ANSI 59 (overvoltage), and ANSI 81 (underfrequency and overfrequency) with the OEL, and the interactions among the protection functions ANSI 21 (distance) and ANSI 27 (undervoltage) with the UEL in addition to the coordination between the protection function ANSI 40 (loss of excitation) and the UEL. Thus, the appropriate settings for these protection and controls are proposed for the excitation system developed. The main results are presented and discussed

A theoretical and practical approach for underexcitation protection and control studies of hydrogenerators in a real-time environment.

?The installation and settings of protection devices and excitation control systems require experience since a failure can cause damage to the synchronous generator and negative impact on the power grid. A test bed implemented in a real-time digital simulator is presented in this paper as an alternative for the training and learning process that involves the knowledge of an effective coordination between such protection and control systems of synchronous generators. A complete generation system is implemented in a real-time digital simulator, including an excitation system model with its limiters. These limiters are coordinated with the protection functions implemented in a physical relay. The contributions of this work are: the demonstration of the importance of this type of study (i.e., real time simulations results through hardware-in-the-loop tests); the consolidation of the impedance (R-X) and admittance (G-B) planes as the more appropriate ones to analyze the coordination between the ANSI 40 function and the underexcitation limiter; and the presentation of a study focused on hydrogenerators (including novel settings for the ANSI 40 protection)