Natural engineering principles of electron tunnelling in biological oxidation-reduction

We have surveyed proteins with known atomic structure whose function involves electron transfer; in these, electrons can travel up to 14 A between redox centres through the protein medium. Transfer over longer distances always involves a chain of cofactors. This redox centre proximity alone is sufficient to allow tunnelling of electrons at rates far faster than the substrate redox reactions it supports. Consequently, there has been no necessity for proteins to evolve optimized routes between redox centres. Instead, simple geometry enables rapid tunnelling to high-energy intermediate states. This greatly simplifies any analysis of redox protein mechanisms and challenges the need to postulate mechanisms of superexchange through redox centres or the maintenance of charge neutrality when investigating electron-transfer reactions. Such tunnelling also allows sequential electron transfer in catalytic sites to surmount radical transition states without involving the movement of hydride ions, as is generally assumed. The 14 A or less spacing of redox centres provides highly robust engineering for electron transfer, and may reflect selection against designs that have proved more vulnerable to mutations during the course of evolution.     

The p66shc adaptor protein controls oxidative stress response and life span in mammals

Gene mutations in invertebrates have been identified that extend life span and enhance resistance to environmental stresses such as ultraviolet light or reactive oxygen species. In mammals, the mechanisms that regulate stress response are poorly understood and no genes are known to increase individual life span. Here we report that targeted mutation of the mouse p66shc gene induces stress resistance and prolongs life span. p66shc is a splice variant of p52shc/p46shc (ref. 2), a cytoplasmic signal transducer involved in the transmission of mitogenic signals from activated receptors to Ras. We show that: (1) p66shc is serine phosphorylated upon treatment with hydrogen peroxide (H2O2) or irradiation with ultraviolet light; (2) ablation of p66shc enhances cellular resistance to apoptosis induced by H2O2 or ultraviolet light; (3) a serine-phosphorylation defective mutant of p66shc cannot restore the normal stress response in p66shc-/- cells; (4) the p53 and p21 stress response is impaired in p66shc-/- cells; (5) p66shc-/- mice have increased resistance to paraquat and a 30% increase in life span. We propose that p66shc is part of a signal transduction pathway that regulates stress apoptotic responses and life span in mammals.     

线性与非线性有限单元分析概论计算方法

本书是关于线性和非线性有限单元法的入门教材，是根据作者在过去12年里为美国新奥尔良大学的多个专业学生讲授这两门课程的基础上逐步编撰而成。本书不同于已有教材，有许多新颖的特点，如重视基础应用，力求最少涉及数学理论；内容涉及的专业范围宽，选用大量不同专业的问题进行引导，可供多种学科背景的学生学习；在讲述理论的同时将相关软件的使用贯穿全书。     

模式识别与计算机视觉手册第三版

本书的第一、二、三版分别于1993、1999和2005年出版。书中全面提供了过去20年中在模式识别与计算机视觉领域中的进展和成就，作者都是这个领域的第一流专家，其中的两位Thomas　Huang和Jake　Aggarwal是权威的K．S．Fu奖金获得者，该项奖金是由国际模式识别协会（IAPR）授予。     

下一代传输网络：传输、管理和控制位面

本书全面论述了传输、管理和控制位面的技术，介绍了一些有用的、现行的和下一代电讯网络技术的参考信息。四位作者均在电信学研究、产品开发等方面具有20年以上的经验。     

哲学性的科学家伟大科学发现之哲学结果

这是一本关于哲学如何给物理带来灵感，而物理又如何去影响哲学的书。哲学给科学带来基本观念和预设，但通过科学发现，这些观念又常常受到怀疑和修正，而伟大的科学家常常知道这种影响的脉络所在。本书通过清晰的论述和精美的插图，以科学哲人为中心讲述了他们的伟大发现，以及什么力量又促使他们重新考虑那些过去科学描述自然世界的惯常观念。书中还阐述了：因为电磁学、热力学和原子结构上的发现，使我们对科学和自然的理解经历了基本概念上的改变。     

The effects of manganese and barium on the cardiac pacemaker current,i f,in rabbit sino-atrial node myocytes

Summary The isolation of ionic fluxes contributing to electric currents through cell membranes often requires block of other undesired components which can be achieved, among others, by divalent cations. Mn²⁺ and Ba²⁺ are often used, for example, to block Ca and K currents. Here we have investigated the effects of these two cations on the properties of the hyperpolarization-activated pacemaker current i_f, in rabbit sino-atrial node myocytes, as obtained by voltage clamp analysis. We find that 2 mM Mn²⁺ shifts the i_f activation curve by 3.2±0.3 mV towards more positive values. However, when 1 mM Ba²⁺ is also added, the positive shift is more than halved (1.3±0.2 mV). We find, too, that in the absence of blocking cations the ACh-induced i_f inhibition is slightly higher than in their presence. These results indicate that the alteration of i_f kinetic properties by Ba²⁺ plus Mn²⁺-containing solutions is minimal.     

Wireless Location Determination for Mobile Objects Based on GSM in Intelligent Transportation Systems

1 .INTRODUCTIONTheabilityofpositioningmobileobjects (MOs) ,in cludingvehiclesandtravelersholdingmobiletermi nals,isafundamentalfunctionforsomeITSsubsys tems,suchasemergencyrescue,securitysystem ,au tomaticnavigationsystem ,andtrafficinducementsystem[1 ] .Atpresent,therearethreedominatingtypes[2 ]ofwirelesspositioningtechnologies,i.e.positioningbasedonsatellites,positioningbasedondedicatedcommunicationsystemsandpositioningbasedonpub liclandwirelesstelecommunicationsystems (PLMTS) ,respe…     

Overcast tests with clock-shifted pigeons

In order to investigate the pigeon's compass mechanism, a series of overcast tests with clock-shifted birds were run at two familiar release sites. While controls were able to assume a correct homeward direction, the experimental birds' initial orientation cannot be explained either on the basis of a time-compensated sun compass or of a time-independent magnetic compass. Speculative explanations of our paradoxical results are attempted.