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11.
We examine the question of whether or not reducing the costs of voting by conducting elections entirely through the mail rather than at the traditional polling place increases participation. Using election data from Oregon, we examine whether or not elections conducted through the mail increase turnout in both local and statewide elections. Using precinct-level data merged with census data we also examine how postal voting may alter the composition of the electorate. We find that, while all-mail elections tend to produce higher turnout, the most significant increases occur in low stimulus elections, such as local elections or primaries where turnout is usually low. The increase in turnout, however, is not uniform across demographic groups. Voting only by mail is likely to increase turnout among those who are already predisposed to vote, such as those with higher socioeconomic status. Like other administrative reforms designed to make voting easier, postal voting has the potential to increase turnout. However, the expanded pool of voters will be limited most likely to those already inclined to vote but find it inconvenient to go to the polling place. This conclusion is consistent with the growing body of research that suggests that relaxing administrative requirements is not likely to be the panacea for low turnout among the disenfranchised.  相似文献   
12.
Using high sensitivity forensic STR polymerase chain reaction (PCR) typing procedures, we have found low concentrations of DNA contamination in plasticware and water assumed to be sterile, which is not detected by standard DNA procedures. One technique commonly used to eliminate the presence of DNA is ultraviolet (UV) irradiation; we optimized such a protocol used in the treatment of water, tubes, plates, and tips for low copy number DNA (LCN) amplification. UV light from a Stratalinker((R)) 2400 was administered to 0.2, 1.5 mL tubes, and PCR plates contaminated with up to 500 pg of DNA. They were subsequently quantified with an ALU-based real-time PCR method using the Rotorgene 3000. Overall, there was a decrease in concentration of DNA recovered as the duration of treatment increased. Nonetheless, following 45 min of irradiating a PCR plate with 500 pg of DNA, nearly 6 pg were still detected. However, when the plate was raised within an inch of the UV source, less than 0.2 pg of DNA was detected. Additionally, lining the area around the samples with aluminum foil further reduced the amount of time necessary for irradiation, as only 30 min eliminated the presence DNA in the raised PCR plate. Similar experiments were conducted using tubes filled with a solution of DNA and water in equivalent concentrations for 50, 15, and 1.5 mL tubes with comparative results. It is plausible that the aluminum foil increased the amount of reflection in the area thereby enhancing penetration of UV rays through the walls of the plasticware. This protocol was tested for the possibility of inhibitors produced from irradiation of plastic tubes. As our protocols require less irradiation time than previous studies, PCR sensitivity was not affected. Moreover, the lifespan of the UV lamps was extended. Our findings demonstrate that this method is useful as an additional precautionary measure to prevent amplification of extraneous DNA from plasticware and water without compromising the sensitivity of LCN DNA amplifications.  相似文献   
13.
血,尿中甲基苯丙胺以及代谢产物苯丙胺的分析研究   总被引:17,自引:1,他引:17  
沈敏  沈保华 《法医学杂志》1997,13(3):129-132
介绍了血、尿中甲基苯丙胺及其代谢产物苯丙胺的GC/MS,GC/FID和GC/NPD的定性定量分析方法.样品以4-苯基丁胺为内标,用200μl环己烷直接提取进样或提出物经微波照射快速衍生化后分析.方法简便、快速,回收率高于80%.检出限为2~5ng/ml.建立了体内甲基苯丙胶和苯丙胺的d/l光学对映体测定方法,可用于判断毒品来源及毒作用.  相似文献   
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