The influence of race on approaching families for organ donation and their decision to donate

OBJECTIVES: This study examined whether patients' race was associated with their families' being approached for organ donation and agreeing to donation. METHODS: Logistic regression models were applied to data collected from records at 112 hospitals. RESULTS: The odds that a family of a White patient was approached for donation were nearly twice those for a family of an African American. The odds of donation also differed by race, but the magnitude varied by patient and hospital characteristics. CONCLUSIONS: Much attention directed toward racial disparity in donation has focused on attitudes of the public. The behavior of hospital staff also may be related to differences in rates.     

Analysis of germline mutation spectra at the Huntington's disease locus supports a mitotic mutation mechanism

Trinucleotide repeat disease alleles can undergo 'dynamic' mutations in which repeat number may change when a gene is transmitted from parent to offspring. By typing >3500 sperm, we determined the size distribution of Huntington's disease (HD) germline mutations produced by 26 individuals from the Venezuelan cohort with CAG/CTG repeat numbers ranging from 37 to 62. Both the mutation frequency and mean change in allele size increased with increasing somatic repeat number. The mutation frequencies averaged 82% and, for individuals with at least 50 repeats, 98%. The extraordinarily high mutation frequency levels are most consistent with a mutation process that occurs throughout germline mitotic divisions, rather than resulting from a single meiotic event. In several cases, the mean change in repeat number differed significantly among individuals with similar somatic allele sizes. This individual variation could not be attributed to age in a simple way or to ' cis ' sequences, suggesting the influence of genetic background or other factors. A familial effect is suggested in one family where both the father and son gave highly unusual spectra compared with other individuals matched for age and repeat number. A statistical model based on incomplete processing of Okazaki fragments during DNA replication was found to provide an excellent fit to the data but variation in parameter values among individuals suggests that the molecular mechanism might be more complex.     

聚酯生产中端羧基及二甘醇的在线表现

将伊文达-卡尔费休聚酯装置的缩聚过程分成三类反应,应用聚合机理,恰当解析了端羧基含量、二甘醇含量与生产线在线表现的关系,并指出酯化率才是影响反应过程的关键因素。     

A conserved histidine is essential for glycerolipid acyltransferase catalysis

Sequence analysis of membrane-bound glycerolipid acyltransferases revealed that proteins from the bacterial, plant, and animal kingdoms share a highly conserved domain containing invariant histidine and aspartic acid residues separated by four less conserved residues in an HX4D configuration. We investigated the role of the invariant histidine residue in acyltransferase catalysis by site-directed mutagenesis of two representative members of this family, the sn-glycerol-3-phosphate acyltransferase (PlsB) and the bifunctional 2-acyl-glycerophosphoethanolamine acyltransferase/acyl-acyl carrier protein synthetase (Aas) of Escherichia coli. Both the PlsB[H306A] and Aas[H36A] mutants lacked acyltransferase activity. However, the Aas[H36A] mutant retained significant acyl-acyl carrier protein synthetase activity, illustrating that the lack of acyltransferase activity was specifically associated with the H36A substitution. The invariant aspartic acid residue in the HX4D pattern was also important. The substitution of aspartic acid 311 with glutamic acid in PlsB resulted in an enzyme with significantly reduced catalytic activity. Substitution of an alanine at this position eliminated acyltransferase activity; however, the PlsB[D311A] mutant protein did not assemble into the membrane, indicating that aspartic acid 311 is also important for the proper folding and membrane insertion of the acyltransferases. These data are consistent with a mechanism for glycerolipid acyltransferase catalysis where the invariant histidine functions as a general base to deprotonate the hydroxyl moiety of the acyl acceptor.     

栈溢出的动态检测技术

缓冲区溢出是计算机界的一个古老话题，计算机界和学术界为检测和预防缓冲区溢出投入了很多的精力。但根据CERT（www．cert．org）的数据显示，最近几年中，缓冲区溢出大约占程序错误的50％。另外，根据CERT Ad—visory数据显示，目前仍然有50％左右的安全威胁系来自缓冲区溢出。因此可以说，缓冲区溢出的问题并没有得到根本的解决，而栈溢出是一种最基本的缓冲区溢出。和堆溢出相比，栈溢出更难于监控和危害性更大，因此研究栈溢出具有实际意义。本文对各种栈溢出的检测技术进行了分类和总结，希望能够对栈设计溢出的检测工具提供一些思路。同时，本文介绍了实现栈溢出的动态检测技术中涉及到的各种插装技术，并对各种各样的插装技术进行了总结。     

干船坞世界高压直流电转换平台完工

由迪拜干船坞世界公司与瑞士ABB公司及挪威Aibel公司合作建造的、具有开创意义的高压直流电（HVDC）转换平台——DolWinbeta完工。     

世界最大起吊船将交付

由美国A．K．Suda股份有限公司设计、越南Saigon船建造的起吊船SUDA450-L3T将交付船尔新加坡EMASOllLshore公司。     

全彩LED显示屏用非对称节能型LAMP器件的设计

全彩LED显示屏通常是仰视的应用环境,上视角范围内的亮度没有被有效利用。本论文提出了一种将LAMP器件上视角范围内的亮度,向下视角范围转移的设计方法。通过设计得到透镜型面数据,制作透镜模具,封装成成品灯珠并进行测试,非对称LAMP器件上视角20°,下视角40°。下视角增大后,在同等条件下,非对称器件与常规器件相比,下视角可视范围内亮度提升了30%。同时,配光的一致性也获得了明显提升,降低了色偏差。由于上视角减小,也减少了上视角范围内的亮度造成的光污染。     

浅谈燃气企业的社会责任

承担社会责任正为越来越多的企业所重视,本文就燃气企业应承担的社会责任并如何履行社会维稳责任进行了论述。     

食品安全的现状分析

通过近几年对市场随机抽查的结果汇总分析,分析目前的食品安全状况、产生问题的主要原因和特点。提出尽快完善统一全面的食品安全标准、在食品生产企业中进一步推广建立食品安全管理体系、运用风险性分析框架管理食品安全,建立和完善的食品安全风险评估评价体系和建立食品安全信息监测、通报和发布的网络体系的建议。