Abrogation of p53 function affects gadd gene responses to DNA base-damaging agents and starvation

The tumor suppressor p53 is required for induction of its downstream effector genes such as GADD45 and CIP1/WAF1 by ionizing radiation (IR). This response is probably mediated through defined p53 binding sites located in the promoter of CIP1/WAF1 and in the third intron of GADD45. In contrast, the gadd gene stress response to base-damaging agents, such as methylmethane sulfonate (MMS) or UV radiation, or medium depletion (starvation) occurs in all mammalian cells examined to date regardless of p53 status for both GADD45 and also GADD153, which is not IR-responsive in many lines with functional p53. These agents strongly induce the p53 protein and raise the possibility that, although p53 is not required for the typical "gadd" response to these agents, p53 may contribute to these non-IR stress responses. This possibility was confirmed by the finding that disruption of p53 function by transfection with dominant-negative vectors expressing HPV E6, mutant p53, or SV40 T Ag reduced the induction of GADD45 and GADD153 as measured by increases in mRNA and protein levels in human lines with wild-type p53. Similarly, induction of these genes by MMS or UV radiation was consistently stronger in the parental mouse embryo fibroblasts compared to cells derived from mice where both p53 alleles had been deleted. Similar qualitative responses were also seen for CIP1/WAF1. In agreement with reduced induction of p53-regulated genes, the G1 checkpoint activated by MMS or UV radiation was markedly abrogated in p53-wt human MCF-7 breast carcinoma cells by E6 expression. Interestingly, induction of reporter constructs driven by the GADD45 or GADD153 promoters was substantially reduced in human cells transfected with mutant p53 or E6 expression vectors or in cells lacking p53 following treatment with MMS, UV radiation, or starvation. Because neither promoter is inducible by IR, and neither contains a strong p53 binding site, these results indicate that p53 has a synergistic or cooperative role in these non-IR stress responses for both GADD45 and GADD153, and that this role is not mediated through identifiable p53-binding sites.     

Dependency mining-based causal message logging

In fault-tolerant computing, the approach of causal message logging provides on-demand stable logging and enables the independent recovery of nodes. It imposes the requirement that the dependency between non-deterministic events needs to be known for nodes. The dependency information is disseminated through messages. A central problem in traditional causal message logging is that if the message logging progress of nodes cannot be effectively tracked, some redundant dependency information will be piggybacked on the messages. In this paper, a dependency mining based approach is proposed. It tries to detect the message logging progress of nodes only from the dependency between non-deterministic events, without needing to piggyback an additional dependency vector or dependency matrix on each message.     

企业对标管理信息系统的应用研究

对某炼化企业的对标管理信息系统的应用进行研究分析,从系统模型、逻辑流程、系统功能设计等进行了深入的分析,并对此系统为企业管理带来的影响进行了全面讨论,肯定了该系统在企业对标管理过程中的重要作用.     

网络图形最短路径算法分析与研究

着重对求网络图上每一对节点之间最短路径的矩阵算法及Floyed算法进行分析与比较,详述它们的功能、原理及异同点,以求在实际应用中合理选择恰当的算法。     

基于ARM-WINCE系统的EVC图像处理界面开发

基于ARM-WINCE的嵌入式图像分析与处理系统与基于PC计算机的图像处理系统相比,具有速度更快、体积更小、应用灵活及成本更低等特点。介绍基于ARM-WINCE平台,在EVC(Embedded Visual C++)环境下开发静态图像处理用户界面,进行图像分析和算法实现。实验结果表明用EVC开发的图像用户界面应用于嵌入式图像处理系统效果良好。     

Structural reliability assessment based on probability and convex set mixed model

This paper investigates the reliability assessment of structures exhibiting both stochastic and bounded uncertainties by using a probability and convex set mixed model. The safety measure of a structure is quantified by a reliability index defined by a nested minimization problem. An iterative procedure is developed for seeking the worst-case point and the most probable failure point in the standard uncertainty space. Numerical examples are given to demonstrate the applicability of the probability and convex set mixed model representation in the structural reliability assessment, as well as to illustrate the validity and effectiveness of the proposed numerical method.     

支持策略隐藏的加密云存储访问控制机制

使用密码技术对云存储数据实施机密性保护和访问控制,是当前云计算安全研究的重要内容.选择加密(Selective Encryption)技术根据访问控制策略产生密钥推导图来分发密钥,在保证云存储数据机密性和细粒度访问控制的前提下,具有简化文件存储加密、系统密钥量少的优势.然而,已有选择加密方案需要完全或部分地公开访问控制策略,以用于密钥推导;该信息反映了用户/文件之间的授权访问关系,泄露用户隐私.基于现有的研究工作,本文提出了一个新的访问控制策略隐藏机制,在支持加密云存储数据的细粒度访问控制和高效密钥分发的前提下,能更好地隐藏访问控制策略信息;而且在密钥获取计算速度上有明显优势.     

Performance of multiple access CSK communication system with DF cooperative strategy

A multiple access chaos shift keying cooperative communication (MA-CSK-CC) system over Rayleigh fading channels and in the presence of Gaussian white noise is investigated in depth in this paper. The simplified half-duplex with a single relay decode-and-forward (DF) cooperative strategy is proposed to illustrate and analysis as an example. Exact and approximation bit-error-ratio (BER) performance expressions are derived. Simulation results demonstrate that the proposed system has a prominent advantage of high BER performance over the conventional multiple access CSK systems that have a single path to transmit signal at the same data rate over Rayleigh fading channels with additive Gaussian white noise. Moreover, based on the BER performance analysis, some useful results are also derived such as the relationships between BER versus spread spectrum factors, BER versus the number of users, etc.     

Iterative quadtree decomposition based automatic selection of the seed point for ultrasound breast tumor images

Based on seed region growing method, lesion segmentation for ultrasound breast tumor images often requires manual selection of the seed point, which is both time-consuming and laborious. To overcome this limit, this paper attempts to explore an automatic method for finding the seed point inside the tumor. Two criteria combining iterative quadtree decomposition (QTD) and the gray characteristics of the lesion are thus designed to locate the seed point. One is to seek the biggest homogenous region and the other is to select the seed region where the seed point is found. Furthermore, this study validates the proposed algorithm through 110 ultrasonic breast tumor images (including 58 malignant tumor images and 52 benign tumor images). According to the needs of the seed region growing algorithm, if the seed point is found inside the tumor, it means the proposed method is correct. Otherwise, it means that the method is a failure. As the quantitative experiment results show, the proposed method in this paper can automatically find the seed point inside the tumor with an accuracy rate of 97.27 %.     

基于不同排序方法的快速霍夫曼编码硬件实现

针对软件霍夫曼静态编码计算量大,而动态霍夫曼编码使得解码器同样复杂的缺点,提出了一种准动态霍夫曼硬件编码器。该编码器每次对一组数据序列进行静态编码,然后将编码并行输出,从而使得编码器具有较高的编码速度,而其延迟时间仅为一次编码过程的总时间。首先,为了充分利用硬件并行特性,分别使用动态排序和静态排序两种排序网络,以适应不同场合的编码需要。然后,使用数据流驱动的硬件二叉树构建和解析结构得到信源符号对应的霍夫曼编码。最后,将储存在FIFO中的输入数据查表并输出。设计结果表明,当使用Nexys4 DDR平台时,该编码器可以工作于100MHz以上的频率,同时具有吞吐高、延迟低、编码效率高和译码器简单的特性。