关键词： diabetes mellitus   type 2   glucosuria   SGLT2 inhibitors   sodium-glucose transport proteins  

摘要： Glucose is freely filtered in the glomeruli before being almost entirely reabsorbed into circulation from the proximal renal tubules. The sodium-glucose cotransporter 2 (SGLT2), present in the Si segment of the proximal tubule, is responsible for the majority of glucose reabsorption. SGLT2 inhibitors reduce glucose reabsorption and increase urinary glucose excretion. In animal models and humans with type 2 diabetes, this effect is associated with reduced fasting and postprandial blood glucose levels, and reduced hemoglobin A1c. Animal studies suggest that reduction of hyperglycemia with SGLT2 inhibitors may also improve insulin sensitivity and preserve beta-cell function. Urinary excretion of excess calories with SGLT2 inhibitors is also associated with reduction in body weight. Modest reductions in blood pressure have been noted with SGLT2 inhibitors, consistent with a mild diuretic action. Some C-glucoside SGLT2 inhibitors, such as dapagliflozin, have pharmacokinetic properties that make them amenable to once-daily dosing. Kidney International (2011) 79 (Suppl 120), S20-S27;doi:10.1038/ki.2010.512

关键词： HIV   Joint models   Nonlinear mixed effects models   Ordinary differential equations   Surrogacy  

摘要： Joint models are used to rigorously explore the relationship between the dynamics of biomarkers and clinical events. In the context of HIV infection, where the multivariate dynamics of HIV-RNA and CD4 are complex, a mechanistic approach based on a system of nonlinear differential equations naturally takes into account the correlation between the biomarkers. Using data from a randomized clinical trial comparing dual antiretroviral therapy to a single drug regimen, a full maximum likelihood approach is proposed to explore the relationship between the evolution of the biomarkers and the time to a clinical event. The role of each marker as an independent predictor of disease progression is assessed. We show that the joint dynamics of HIV-RNA and CD4 captures the effect of antiretroviral treatment;the CD4 dynamics alone is found to capture most but not all of the treatment effect.

关键词： 气候试验   组件   周期性荷载   定义(术语)   电负载   电气工程   电学测量   电子工程   电子设备及元件   环境测试   故障   集成电路   负载交替   机械测试   电力电子学   耐力   半导体器件   半导体   模拟   试验   测试条件  

标准号: BS EN 60749-34-2010

摘要： IEC 60749-34:2010 describes a test method used to determine the resistance of a semiconductor device to thermal and mechanical stresses due to cycling the power dissipation of the internal semiconductor die and internal connectors. This happens when low-voltage operating biases for forward conduction (load currents) are periodically applied and removed, causing rapid changes of temperature. The power cycling test is intended to simulate typical applications in power electronics and is complementary to high temperature operating life (see IEC 60749-23). Exposure to this test may not induce the same failure mechanisms as exposure to air-to-air temperature cycling, or to rapid change of temperature using the two-fluid-baths method. This test causes wear-out and is considered destructive. This second edition cancels and replaces the first edition published in 2004 and constitutes a technical revision. The significant changes with respect from the previous edition include: - the specification of tighter conditions for more accelerated power cycling in the wire bond fatigue mode; - information that under harsh power cycling conditions high current densities in a thin die metalization might initiate electromigration effects close to wire bonds.

关键词： CRYSTALS   MICROSCOPY   CRYSTAL growth   PHASE transformations (Physics)   STRAINS & stresses (Mechanics)   CHEMICAL kinetics  

摘要： We investigated by optical microscopy the thermal spin transition in single crystals of [Fe(bbtr)(3)](ClO4)(2) (bbtr = 1,4-di(1,2,3-triazol-1-yl) butane). The growth of the low-spin phase was observed for different crystal orientations and sizes. The process always started from a corner of the crystal but its further development depended on the size, shape and thermal history of the crystal. In crystals of smaller size, under isothermal conditions, the low-spin phase developed in a continuous way, through the propagation of a rather well defined transformation front, with a higher propagation velocity inside the planes perpendicular to the c axis. In larger crystals the spontaneous occurrence of inhomogeneous stresses led to a stepwise propagation process. (C) 2011 Elsevier B. V. All rights reserved.

关键词： 复杂机械系统   动力学   李群李代数   递推算法  

摘要： 针对日益复杂的机械系统,提出用李群李代数符号描述正向和反向递推动力学,研究其控制和仿真问题。运用李群李代数符号表示了伴随变换和伴随算子,基于树形拓扑结构系统,推导得到其递推动力学方法,讨论了其闭环系统和柔性系统的高效动力学算法。实例验证表明:李群李代数描述的动力学算法计算效率高,形式简洁,易于编程,对于实时动力学的研究具有重要意义。