硬件问答

QT60无线上网不定期掉线一台IBM的T60笔记本,买了也就两个月左右,安装Vista操作系统,无线上网经常掉线,有时候一两小时左右一次,有时候时间长一些。无线路由器使用的是Netgear     

MSN也能显示Foobar播放信息

我们知道,MSN有"个性化个人信息"的功能,其中就有一个"向联系人显示您听的音乐"一项,只要我们选中它,就将在MSN上动态显示你正在听的歌曲信息,同时     

硬件问答

选购指南双BIOS有什么用处Q现在不少主板和显卡都采用双BIOS设计,请问双BIOS究竟有什么用处?A双BIOS技术实际上是让主板上搭载两个相同的BIOSROM芯片,并在其中写入两个版本相同的BIOS文件,这样一来,一旦主BIOS出现异常损坏,主板同样能够借助备份的BIOS正常工作,而备份的BIOS同时也能对主BIOS进行修复,有效地确保整机的安全性。现在很多显卡上同样     

2-mJ single-axial-mode gain-switched Cr:forsterite lasers

Single-longitudinal-mode operation of gain-switched Cr4+ laser, with output energy as much as 1.9 mJ, is reported from two different coupled-cavity resonators. A prism-coupled cavity and a modified Michelson interferometric grazing-incidence (MIGI) cavity was pumped by a multilongitudinal-mode Q-switched Nd:YAG laser; the modified MIGI cavity obtained 100-MHz-bandwidth laser output tunable between 1150 and 1330 nm. Conversion efficiency of 3.2% (slope efficiency of 4%) was achieved, with a pump threshold density as small as 0.2 J/cm2. Mode spacing of the laser output in multilongitudinal mode showed increased mode spacing in agreement with a coupled-cavity theory.     

Model-based resolution: applying the theory in quantitative microscopy

Model-based image processing techniques have been proposed as a way to increase the resolution of optical microscopes. Here a model based on the microscope's point-spread function is analyzed, and the resolution limits achieved with a proposed goodness-of-fit criterion are quantified. Several experiments were performed to evaluate the possibilities and limitations of this method: (a) experiments with an ideal (diffraction-limited) microscope, (b) experiments with simulated dots and a real microscope, and (c) experiments with real dots acquired with a real microscope. The results show that a threefold increase over classical resolution (e.g., Rayleigh) is possible. These results can be affected by model misspecifications, whereas model corruption, as seen in the effect of Poisson noise, seems to be unimportant. This research can be considered to be preliminary with the final goal being the accurate measurement of various cytogenetic properties, such as gene distributions, in labeled preparations.     

Comparative study of tunable room-temperature laser operation in the 900-1100-nm range: LiF:F2+ and Ti3+:sapphire

We report on a comparative evaluation of efficient room-temperature solid-state lasers based on Ti:sapphire and LiF:F(2)(+) operating in the 900-1100-nm range. LiF:F(2)(+) lasers are shown to operate with substantially lower threshold, broader tuning, and higher output pulse energies. The shorter fluorescence lifetime in LiF:F(2)(+) leads to higher peak output powers and a considerable reduction in buildup-time fluctuations. The main limitations on LiF:F(2)(+) laser operation are identified as amplified spontaneous emission (ASE) and long-term thermal degradation of the color centers. ASE restricts the tuning range, slope efficiency, and bandwidth of the LiF:F(2)(+) laser for high pump intensity, but broader tuning is achieved with longer pump pulses. The beam quality of the LiF:F(2)(+) laser is comparable with that of the Ti:sapphire laser.     

正视网络安全以及网络安全问题一览

在2005年中,伴随着网络技术和计算机技术的发展,网格服务的成熟以及Web service的广泛应用,更多的新技术新应用将融入我们的生活中,而随之而来的,除了便利,还有一些不安。从互联网的兴起开始,越来越多的病毒感染从原本的exe文件感染方式改变为漏洞攻击+驻留+尝试攻击其他机器的模式。不管是Windows也好,Linux也好,Solaris或者其他操作系统也好,软件是人写的,由于效率或考虑不周等因素,常常会在极端测试下造成程序溢出,进而让攻击者取得权限。Windows xp的sp2刚发布没多久,微软的“安全服务”还没喊响之际,就又爆出10多个IE漏洞来,漏洞—…     

DL_POLY_3: the CCP5 national UK code for molecular-dynamics simulations

DL_POLY_3 is a general-purpose molecular-dynamics simulation package embedding a highly efficient domain decomposition (DD) parallelization strategy. It was developed at Daresbury Laboratory under the auspices of the Engineering and Physical Sciences Research Council. Written to support academic research, it has a wide range of applications and will run on a wide range of computers; from single-processor workstations to multi-processor computers, with accent on the efficient use of multi-processor power. A new DD adaptation of the smoothed particle mesh Ewald method for calculating long-range forces in molecular simulations, incorporating a novel three-dimensional fast Fourier transform (the Daresbury Advanced Fourier Transform), makes it possible to simulate systems of the order of one million particles and beyond. DL_POLY_3 structure, functionality, performance and availability are described in this feature paper.     

PKC signalling regulates tight junction membrane assembly in the pre-implantation mouse embryo

Epithelial differentiation including tight junction (TJ) formation occurs exclusively within the trophectoderm (TE) lineage of the mouse blastocyst. Here we examine mechanisms by which TJ protein membrane assembly might be regulated by protein kinase C (PKC) in the embryo. To overcome the inherent staging asynchrony of individual blastomeres within intact embryos, we have used isolated inner cell masses (ICMs) from early blastocysts to induce epithelial differentiation in their outer cells responding to their new cell contact pattern. Two TJ proteins examined retain their order of membrane assembly in isolated ICMs in culture as during normal development (early-assembling ZO-2 and late-assembling ZO-1alpha(+)), but this process is highly accelerated. Using six chemical modulators of PKC activity, we show here that PKC signalling is involved in the regulation of TJ membrane assembly. While indolactam-mediated PKC activation stimulates membrane assembly of both TJ proteins, TPA-mediated PKC activation stimulates only that of ZO-1alpha(+). The PKC inhibitors Ro-31-8220, Ro-31-8425 and G? 6983 suppress the stimulatory effect of both PKC activators on membrane assembly to varying extents according to inhibitor and TJ protein examined. G? 6983 similarly inhibits ZO-2 and ZO-1alpha(+) membrane assembly. PKC inhibition by G? 6976 appeared to stimulate TJ membrane assembly. Despite the broad PKC isotype specificity of the inhibitors used, these data suggest that the two TJ proteins are differently regulated by PKC isotypes or subfamilies. As G? 6983 uniquely affects aPKC (particularly PKCzeta) and we find that both PKCdelta and zeta relocate upon activator treatment to colocalise partially with the TJ proteins in isolated ICMs, we suggest that at least PKCdelta and zeta may play a central role in regulating TJ membrane assembly.     

Microbiology, chemistry and biofilm development in a pilot drinking water distribution system with copper and plastic pipes

We studied the changes in water quality and formation of biofilms occurring in a pilot-scale water distribution system with two generally used pipe materials: copper and plastic (polyethylene, PE). The formation of biofilms with time was analysed as the number of total bacteria, heterotrophic plate counts and the concentration of ATP in biofilms. At the end of the experiment (after 308 days), microbial community structure, viable biomass and gram-negative bacterial biomass were analysed via lipid biomarkers (phospholipid fatty acids and lipopolysaccharide 3-hydroxy fatty acids), and the numbers of virus-like particles and total bacteria were enumerated by SYBR Green I staining. The formation of biofilm was slower in copper pipes than in the PE pipes, but after 200 days there was no difference in microbial numbers between the pipe materials. Copper ion led to lower microbial numbers in water during the first 200 days, but thereafter there were no differences between the two pipe materials. The number of virus-like particles was lower in biofilms and in outlet water from the copper pipes than PE pipes. Pipe material influenced also the microbial and gram-negative bacterial community structure in biofilms and water.