Effects of addiction-associated and affective stimuli on the attentional blink in a sample of abstinent opiate dependent patients

The attentional blink reveals the limits of the brain's ability in information processing. It has been extensively studied in people with neurological and psychiatric disturbances to explore the temporal characteristics of information processing and exami

Effects of unconditioned and conditioned aversive stimuli in an intense fear conditioning paradigm on synaptic plasticity in the hippocampal CA1 area in vivo

Repeated vivid recalls or flashbacks of traumatic memories and memory deficits are the cardinal features of post-traumatic stress disorder (PTSD). The underlying mechanisms are not fully understood yet. Here, we examined the effects of very strong fear conditioning (20 pairings of a light with a 1.5-mA, 0.5-s foot shock) and subsequent reexposure to the conditioning context (chamber A), a similar context (chamber B), and/or to the fear conditioned stimulus (CS) (a light) on synaptic plasticity in the hippocampal CA1 area in anesthetized Sprague-Dawley rats. The conditioning procedure resulted in very strong conditioned fear, as reflected by high levels of persistent freezing, to both the contexts and to the CS, 24 h after fear conditioning. The induction of long-term potentiation ON was blocked immediately after fear conditioning. It was still markedly impaired 24 h after fear conditioning; reexposure to the conditioning chamber A (CA) or to a similar chamber 13 (CB) did not affect the impairment. However, presentation of the CS in the CA exacerbated the impairment of LTP, whereas the CS presentation in a CB ameliorated the impairment so that LTP induction did not differ from that of control groups. The induction of long-term depression (LTD) was facilitated immediately, but not 24 h, after fear conditioning. Only reexposure to the CS in the CA, but not reexposure to either chamber A or B alone, or the CS in chamber B, 24 h after conditioning, reinstated the facilitation of LTD induction. These data demonstrate that unconditioned and conditioned aversive stimuli in an intense fear conditioning paradigm can have profound effects on hippocampal synaptic plasticity, which may aid to understand the mechanisms underlying impairments of hippocampus-dependent memory by stress or in PTSD. (c) 2005 Wiley-Liss, Inc.

Kaffe在龙芯2E上的移植

为了在龙芯2E处理器上建立稳定的Java运行环境,丰富龙芯平台的上层软件库,以Kaffe这款开源Java虚拟机为移植对象,分析了其运行机制,确定了其代码结构中平台相关的3个主要模块:SysCallMethod、Trampoline和JTT,并结合龙芯2E处理器的特点,给出了相关模块的修改方案.最后用第三方的测试标准对移植后的虚拟机进行了测试,表明了移植的有效性.

Kaffe虚拟机在龙芯2E上的移植研究

Java虚拟机作为Java运行环境的核心，已成为现代计算机平台不可缺少的组成部分。Java虚拟机和平台间的兼容性直接决定了上层Java程序的运行的稳定性。龙芯2E是由中科院计算机研究所自主研发的高性能微处理器。由于采用MIPS指令集，现有Java虚拟机对龙芯的支持并不理想，这极大地限制了龙芯平台的上层应用。 针对这一问题，本文对现有虚拟机进行了分析，选择了移植性较强的Kaffe虚拟机作为移植对象，力求在龙芯2E上建立一个稳定的Java运行环境。以此为目的，本文整理了龙芯2E相关的内容，包括龙芯2E的指令集特点，龙芯下参数传递的方式，龙芯下函数栈的组织等等；研究了Java虚拟机规范中，一般Java虚拟机的体系结构；分析了Kaffe虚拟机的代码结构，确定了移植需要修改的三个主要模块：本地代码调用接口，Trampoline技术和JIT3引擎；给出了移植方案。其中，JIT3引擎作为整个虚拟机的核心，是整个移植工作的重点。本文对其编译过程，寄存器分配策略，Java栈的组织方式，以及标签，常量池等平台相关机制进行了深入的分析。在此基础上，修改了Java栈向本地栈的映射方式，实现了标签机制中平台相关部分的代码，重新描述了寄存器信息并重新实现了本地汇编指令。 针对Java虚拟机调试困难的问题，本文总结了龙芯平台下Kaffe虚拟机的调试方法。在调试过程中发现了Kaffe原有代码中的编码错误，并给出了修改方案。 最后采用第三方的评测工具对移植后的虚拟机进行测试，验证了移植的有效性。

Ne原子(e,2e)反应中反冲离子动量分析；Analysis of Recoil Ion Momentum in Ne(e,2e)Ne~+ Reaction

利用冷靶反冲离子动量谱仪,对电子轰击Ne原子的单电离反应(e,2e)进行了研究,实验测量了70—3300eV入射能量情况下,反应过程中产生的一价反冲离子的动量分布,并对反冲离子的总动量进行了还原。介绍了一个简单的碰撞机制,据此着重分析了反冲离子纵向动量和横向动量二维谱形成的原因,该碰撞机制能够较好地解释较高能量入射时的实验结果。最后根据反冲离子的动量,估算了出射电子的能量范围,为下一步进行电子、离子的符合测量奠定了基础。

Effect of block sequence and block length on the stimuli-responsive behavior of polyampholyte brushes: hydrogen bonding and electrostatic interaction as the driving force for surface rearrangement

Diblock polyampholyte brushes with different block sequences (Si/SiO2/poly(acrylic acid)-b-poly (2-vinylpyridine) (PAA-b-P2VP) brushes and Si/SiO2/P2VP-b-PAA brushes) and different block lengths were synthesized by sequent surface-initiated atom transfer radical polymerization (ATRP). The PAA block was obtained through hydrolysis from the corresponding poly(tert-butyl acrylate). The polyampholyte brushes demonstrated unique pH-responsive behavior. In the intermediate pH region, the brushes exhibited a less hydrophilic wetting behavior and a rougher surface morphology due to the formation of polyelectrolyte complex through electrostatic interaction between oppositely charged blocks. In the low pH and high pH regions, the rearrangement of polyampholyte brushes showed great dependence on the block sequence and block length. The polyampholyte brushes with P2VP-b-PAA sequence underwent rearrangement during alternative treatment by acidic aqueous solution (low pH value) and basic aqueous solution (high pH value).

Stimuli-responsive polyelectrolyte block copolymer brushes synthesized from the si wafer via atom-transfer radical polymerization

Surface-tethered oppositely charged weak polyelectrolyte block copolymer brushes composed of poly(2-vinyl pyridine) (P2VP) and poly(acrylic acid) (PAA) were grown from the Si wafer by atom-transfer radical polymerization. The P2VP-b-PAA brushes were prepared through hydrolysis of the second PtBA block to the corresponding acrylic acid. The P2VP-b-PAA brushes with different PAA block length were obtained. The P2VP-b-PAA brushes revealed a unique reversible wetting behavior with pH. The difference between the solubility parameters for P2VP and PAA, the changes of surface chemical composition and surface roughness, and the reversible wetting behavior illustrated that the surface rearrangement occurred during treatment of the P2VP-b-PAA brushes by aqueous solution with different pH value. The reversible properties of the P2VP-b-PAA brushes can be used to regulate the adsorption of the sulfonated PS nanoparticles.

A STUDY ON 2E SPECTRA OF BIPHENYL DERIVATIVES

A study of doubly charged ion mass spectra (2E spectra), the substituents effect and the target gas pressure deppendence of biphenyl derivitives was presented in this work. The decomposition of doubly charged ion formed in the ion source is dominant by the losses of H, C2H2, C2H4 and HR(R represents substituent). [C12H8]2+, [C12H6]2+ and [C10H6]2+ among others are the most stable product ions. The substituents effect is Various in different decomposition reactions, and in some cases it can not be predicted by Hammett equition. While the TIC of 2E spectra was markedly influenced by the target gas pressure, but the fragmentation pattern of the 2E spectra is independent of it.

联苯取代物的双电荷离子质谱(2E谱)研究

本文研究了联苯取代物双电荷离子2E谱及其取代基效应和靶气压力影响。离子源中产生的双电荷离子的解离反应主要有丢失H原子、C_2H_2、C_2H_4、HR(R为取代基)等反应通道。产物离子中[C_(12)H_8]~(2+)、[C_(12)H_6]~(2+)、[C_(10)H_6]~(2+)等具有相当的稳定性。取代基对不同的反应有不同的影响,主要取决于产物离子的相对稳定性。取代基对分子离子的稳定性的贡献有以下顺序:NH_2>OH>Ph>F>H>Br>NO_2。升高靶气压力,2E谱的总离子流迅速升高,而样品离子流占总离子流的百分数却直线降低。靶气压力影响样品的检测灵敏度,但不影响离子的碎裂途径。