A comparative cerebral blood flow study in a baboon model with acetazolamide provocation: 99mTc-HMPAO vs 123I(IMP)

Pharmacological interactions are important when nuclear medical procedures are applied to patients under drug therapy, or drug provocation. This study compares in baboon models (regional) cerebral blood flow [(r)CBF] results from 99mTc-HMPAO and 123I-iodoamphetamine [123I(IMP)] each with and without acetazolamide, the latter a suggested drug for testing cerebrovascular reserve. Expected differences in cerebral uptake were observed between the two radio-tracers without acetazolamide. The increase in tracer uptake resulting from acetazolamide is significantly enhanced for 123I(IMP), which could have diagnostic implications.     

IC CAD中的图形运算算法与实现

熊猫系统是一个基于全定制ASIC,同时能完成半定制ASIC设计的完整的ICCAD系统。GOA(Geometric Operations and Analysis tool)是其中的完成图形算术、逻辑、拓扑运算的工具及软件库。本文将介绍它的作用及其与其它工具的关系,并详细介绍了其算法及我们在α测试和β测试中针对速度和精度要求所做的改进工作。     

2012年苹果仍将是平板电脑销量冠军

虽然基于Android系统的平板电脑增长快速,但目前看来苹果仍将保持绝对领先的态势。随着英特尔超极本的推出以及Windows8面市,PC型平板或将成为平板市场上一股新的力量。据IHS iSuppli公司全球平板电脑市场追踪报告显示,2012年苹果公司将以其iPad系列产品轻松保持在全球平板电脑市场的绝对领先地位,尽管一众Android产品和基于PC的平板产品也在努力进入这个迅速增长的市场。今年包括媒体平板和PC型平板在内的平板电脑销量将增加到1.266亿台,比2011年的     

哈佛研制出具有宏观电势的纳米光伏电池

Charles Lieber博士领导哈佛大学的一个研究小组开发了一种约300nm厚的共轴硅纳米线,可以制作用来驱动小型电路和纳米机器的光伏（PV）电池。     

扬声器系统的自动均衡、分频和对齐

为了得到更好的音质,扬声器设计除了采用新材料和新工艺外,设计人员还利用DSP实现精确的信号处理与控制。而先进的软件可以帮助设计师提高产品开发效率,获得最佳扬声器设计方案。     

2011电视半导体市场增长势头减弱

由于价格压力沉重和电视销售低迷,去年电视主板上使用的半导体销售额萎缩,并迫使一些知名厂商永远退出该产业。不过随着新功能的推出,半导体企业仍存在增长机会。     

THE HYSTERESIS LOOP 3. STRESS-DIP EXPERIMENTS

Abstract— A stress-dip technique for the determination of an effective stress in cyclic straining has been improved. The critical stress drop, Δσ_C, for which zero strain relaxation rate is observed can be obtained from experiments. The significance of this quantity is discussed in terms of the statistical theory of the hysteresis loop. The measurements of the effective stress at different temperatures and along the hysteresis loop are reported. The observed asymmetry of stress in cyclic straining is ascribed to asymmetry of effective stress.     

Measurement of agonist efficacy using an alpha2A-adrenoceptor-Gi1alpha fusion protein

A fusion protein was constructed between the porcine alpha2A-adrenoceptor and a pertussis toxin-insensitive (Cys351Gly) form of the alpha subunit of the G protein Gi1. Addition of agonist ligands to membranes of COS-7 cells transiently transfected to express this construct, and treated with pertussis toxin prior to cell harvest, resulted in stimulation of both high affinity GTPase activity and enhanced binding of [35S]GTPgammaS. By considering the fusion protein as an agonist-activated enzyme and measuring Vmax of GTP hydrolysis a range of agonist ligands displayed varying efficacy in their capacity to activate the receptor-associated G protein with adrenaline = noradrenaline = alpha-methylnoradrenaline > UK14304 > BHT933 > or = xylazine = clonidine. A similar rank order was observed following independent co-expression of the alpha2A-adrenoceptor and Cys351Gly-Gi1alpha. These data demonstrate the utility and applicability of using a receptor-G protein fusion protein approach, in which the stoichiometry of receptor and G protein is fixed at 1:1, to measure and further understand the nature of agonist efficacy.