Proton translocation by cytochrome c oxidase.

Cell respiration in mitochondria and some bacteria is catalysed by cytochrome c oxidase, which reduces O2 to water, coupled with translocation of four protons across the mitochondrial or bacterial membrane. The enzyme's catalytic cycle consists of a reductive phase, in which the oxidized enzyme receives electrons from cytochrome c, and an oxidative phase, in which the reduced enzyme is oxidized by O2. Previous studies indicated that proton translocation is coupled energetically only to the oxidative phase, but this has been challenged. Here, with the purified enzyme inlaid in liposomes, we report time-resolved measurements of membrane potential, which show that half of the electrical charges due to proton-pumping actually cross the membrane during reduction after a preceding oxidative phase. pH measurements confirm that proton translocation also occurs during reduction, but only when immediately preceded by an oxidative phase. We conclude that all the energy for proton translocation is conserved in the enzyme during its oxidation by O2. One half of it is utilized for proton-pumping during oxidation, but the other half is unlatched for this purpose only during re-reduction of the enzyme.     

旅行商问题（TSP）的模拟退火求解

提出了循环排序中６种不同的随机抽样方式，对旅行商问题（ＴＳＰ）的模拟退火求解进行了进一步深入研究．理论分析证明，６种抽样方式均满足模拟退火算法的全局收敛性条件．实例计算表明，子排列反序并移位抽样方式的求解寻优效率最高，且明显优于目前公认最好的著名的Ｓ．Ｌｉｎ“２－交换”抽样方法．本研究和结论对循环排序类优化问题及其求解具有普遍意义．     

Protein translocation across the eukaryotic endoplasmic reticulum and bacterial plasma membranes

A decisive step in the biosynthesis of many proteins is their partial or complete translocation across the eukaryotic endoplasmic reticulum membrane or the prokaryotic plasma membrane. Most of these proteins are translocated through a protein-conducting channel that is formed by a conserved, heterotrimeric membrane-protein complex, the Sec61 or SecY complex. Depending on channel binding partners, polypeptides are moved by different mechanisms: the polypeptide chain is transferred directly into the channel by the translating ribosome, a ratcheting mechanism is used by the endoplasmic reticulum chaperone BiP, and a pushing mechanism is used by the bacterial ATPase SecA. Structural, genetic and biochemical data show how the channel opens across the membrane, releases hydrophobic segments of membrane proteins laterally into lipid, and maintains the membrane barrier for small molecules.     

Travelling waves and spatial hierarchies in measles epidemics.

Spatio-temporal travelling waves are striking manifestations of predator-prey and host-parasite dynamics. However, few systems are well enough documented both to detect repeated waves and to explain their interaction with spatio-temporal variations in population structure and demography. Here, we demonstrate recurrent epidemic travelling waves in an exhaustive spatio-temporal data set for measles in England and Wales. We use wavelet phase analysis, which allows for dynamical non-stationarity--a complication in interpreting spatio-temporal patterns in these and many other ecological time series. In the pre-vaccination era, conspicuous hierarchical waves of infection moved regionally from large cities to small towns; the introduction of measles vaccination restricted but did not eliminate this hierarchical contagion. A mechanistic stochastic model suggests a dynamical explanation for the waves-spread via infective 'sparks' from large 'core' cities to smaller 'satellite' towns. Thus, the spatial hierarchy of host population structure is a prerequisite for these infection waves.     

古代游宦诗人在广西桂东地区的文学书写

清人汪森的《粤西诗载》收入自秦汉至明末游宦桂东的88名诗人在桂东创作且吟咏桂东的诗作212首。没有收进《粤西诗载》的游宦诗人和歌唱桂东的诗词还有很多。从这些游宦诗人在桂东的文学书写,可以读到各时代诗人的诗心,诸如迁谪之情,隐逸之念,用世之心。他们对桂东地理、风土、政治的记录,是研究桂东政治、经济、文化、旅游的重要史料,他们的诗作为桂东文学的繁荣增添了绚烂多彩的一笔。     

用路径代数求解旅行商问题的新结果

针对求解旅行商问题的一种路径代数解法在解题中遇到的问题。通过引进无环点集、替代点集等概念,使修改后的PATSP算法的解题能力得以显著增强。     

在信息烟尘中穿行

过去,我们说捕捉、搜集信息,现在,恐怕我们得说“打捞”信息,我们都快被信息的洪水吞没了。 (一) 一位财经类媒体主管曾自述他上班时要处理的信息。早晨一到办公室,立刻翻看当天报刊,除中央类报刊外,还有大量经济类报刊,但只来得及大概浏览一遍。     

行波法定点输电电缆故障诊断研究

本文针对地下及地面铺设的输电电缆的短路、断路及绝缘破损故障，根据传输线理论及对反射系数的讨论，论证了行波法定点电缆故障的可行性。并讨论了实施该法的某些具体技术细节问题。     

Breeding of T. aestivum-Ag. intermedium translocation lines with T. timopheevii cytoplasm and characterization by GISH

A male-sterileT. aestivum-Ag. intermedium partial amphiploid with cytoplasm ofT. timopheevii as a female parent was crossed to common wheat. The hybrid was backcrossed to the male parent several times continually and setf-crossed at last. Two stable lines with common wheat phenotype, H96269-2 and H96278, have been obtained. The chromosome numbers of the two lines are all2n = 42 in somatic cetls. By inoculation test, the two lines show a high levet of resistance to yetlow rust. Through genomicin situ hybridization (GISH) withAg. intermedium total genomic DNA as a probe, it is demonstrated that the two stable lines are all small segmental translocation lines, and the translocated chromosome segments fromAg. intermedium are located on the short arm terminals of wheat chromosomes. Genetics analysis suggests that the yetlow rust resistance gene(s) are probably located on the translocated chromosome segments ofAg. intermedium.     

江湖诗人戴复古与镇江

戴复古是南宋时期江湖诗派的代表人物，在我国诗坛上也有相当大的影响。他在一生中曾三次出远门游历天下，到过许多地方。作为江南历史文化名城的镇江，亦有他的足迹和影响，可惜以往的著述中对此提及甚少。从揭示戴复古在诗坛的影响入手，可考索其与镇江的关系及对镇江人文的贡献。     

庄子"逍遥游"之我见

庄子在《逍遥游》中,不仅表现出了自身对精神自由的执着追求,而且体现了他反对社会对个人的异化的思想。人们一旦汲汲于追求功名利禄,就会"丧己于物",被这些世俗价值所束缚。有着自身发展的目的的人,被抽象为单一的手段,这是人的本质的进一步丧失。     

K1ein—Gordon方程的行波解

文章应用平面动力系统理论研究了Klein-Gordon方程，光滑的孤立行波、周期波、扭子与反扭子波的存在性得到了证明。在一些简单条件下，给出了所有可能的精确的解析行波解。     

无粘性流体内部传播的横波

无粘性流体内部,虽然不存在切向应力,但是,在一定条件下,横波仍可在其中传播。如在重力场作用下,密度分层理想流体内部的重力内破及旋转非惯性系中理想流体内部的惯性和罗斯贝(Rossby)波都是这类横波,其中浮力及牵连惯性力和科里奥利惯性力分别相应地担当了在通常情况下切向应力所扮演的回复力角色。     

穿越时空的奇迹

<正>6月1日出版的英国《自然》杂志子刊《自然·光子学》以封面论文发表了"世界上最远距离——长达16公里的量子态隐形传输",这一成果由以潘建伟、彭承志为首席专家的中国科技大学和清华大学组成的联合小组完成。首次成功实现了世     

一类反应扩散方程的有限行波解

利用上、下解方法和比较原理,研究了一类带有对流项和吸收项的反应扩散方程的非负有限行波解。得出了该方程行波解的唯一性,局部存在性,整体存在性和爆破的充要条件。     

KP方程的精确行波解

借助一个新的代数方法,其算法为研究一个一阶并具有六次非线性项的微分方程,研究了KP方程,得到新的孤波解和周期解,这种方法也适合研究其他的非线性演化方程.     

Klein-Gordon方程的行波解

文章应用平面动力系统理论研究了Klein-Gordon方程,光滑的孤立行波、周期波、扭子与反扭子波的存在性得到了证明。在一些简单条件下,给出了所有可能的精确的解析行波解。