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The concentrations of antimony, copper, tin, arsenic, silver, bismuth, and cadmium in lead alloys produced by two smelters and one ammunition manufacturer were determined using inductively coupled plasma-atomic emission spectrometry. These element concentrations were used to measure the variations in composition of lead products that result from various processes involved in the manufacture of lead projectiles. In general, when a pot containing molten lead is used to cast a number of objects, these objects are similar, although not necessarily analytically indistinguishable in their elemental compositions. In each subsequent step in the processing of lead at the smelter and at the ammunition manufacturer, the size of an individual homogeneous melt of lead decreases as more distinct compositions are formed as a result of remelting and mixing of sources, including lead scrap. The ammunition manufacturer in this study produced at least 10 compositionally distinguishable groups of bullet wire in a 19.7-h period. The largest group could potentially be used to produce a maximum of 1.3 million compositionally indistinguishable 40 grain bullets.  相似文献   
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Validation of a 16-locus fluorescent multiplex system   总被引:24,自引:0,他引:24  
STR multiplexes have been indispensable for the efficient genotyping of forensic samples. The PowerPlex 16 System contains the coreCODIS loci, D3S1358, D5S818, D7S820, D8S1179, D13S317, D16S539, D18S51, D21S11, CSF1PO, FGA, THOI, TPOX, vWA, the sex determinant locus, amelogenin, and two pentanucleotide STR loci, Penta D and Penta E. This multiplex satisfies the locus requirements for most national databases and is the most efficient currently available system due to its single PCR amplification. To provide the groundwork for judicial acceptance, including the publication of primer sequences, and to evaluate laboratory-to-laboratory variation, a developmental validation for casework on this commercially available system was performed in 24 laboratories and produced the following conclusions. Amplification was reliable on a variety of thermal cyclers and product could be analyzed on either an ABI PRISM 310 Genetic Analyzer or an ABI PRISM 377 DNA Sequencer. Genotyping using single source samples was consistent between 0.25 and 2 ng of input DNA template with a few laboratories obtaining complete genotypes at 0.0625 ng. However, heterozygote allele imbalance (<60% peak height balance) caused by stochastic effects was observed at a rate of 13% with 0.125 ng DNA and 22% at 0.0625 ng DNA. Mixture analyses were done using a total of 1 ng of DNA template. Most alleles were detected in mixtures of 4 to 1 and some minor alleles were detected in mixtures of 19 to 1. Optimum amplification cycle number was dependent on the sensitivity of the detection instrument used and could also be adjusted to accommodate larger amounts of DNA on solid supports such as FTA paper. Reaction conditions including volume, annealing temperature, and concentrations of primer, AmpliTaq Gold, and magnesium were shown to be optimal yet robust enough to withstand moderate variations without affecting genotype analysis. Environmental, matrix and standard source analyses revealed an ability to obtain complete genotypes in all sample types except those exposed to 80 degrees C for 12-48 days. Finally, comparison of genotype results from the PowerPlex 16 System with other commercially available systems on non-probative reference and forensic samples showed consistent results.  相似文献   
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Abstract: Efforts to design merit‐based appointment systems for the boards of government agencies, boards and commissions (abcs) have gained greater priority over the past decade in order to enhance public confidence in the integrity of the political process, improve the governance of organizations operating at arm's length from ministers, and reduce the risks to the public interest and public purse that come with incompetent boards. The Nova Scotia reform experience in this regard is instructive because this province's appointment regime not only encompasses a legislative committee veto over ministerial appointments, a power unique to this province in the Canadian and comparative Westminster systems, but also uniquely sets the merit standard as relative‐merit, that is, the appointment of the most qualified of all applicants, and not merely a qualified candidate. This article reviews this provincial experience and concludes that a merit‐based appointment system that pursues relative merit can be created but only by restricting the authority of ministers to a veto over the appointment of candidates nominated by the abcs themselves. Sommaire: Ces dix demières années, les efforts déployés pour concevoir des systemes de nomination au mérite pour les conseils d'administration d'organismes, des régies et des commissions du gouvernement ont obtenu une priorité beaucoup plus grande, et cela, afin de rehausser la confiance du public envers I'intégrite du processus politique, d'ameliorer la gouvernance d'organismes fonctionnant sans contrôle ministériel direct et de réduire les risques que représentent les conseils incompétents pour le bien et les deniers publics. L'expérience de la réforme entreprise en NouvelleÉcosse est à cet égard instructive pour les partisans de la réforme. Le régime de nomination de cette province comporte non seulement un droit de veto de la part d'un comité législatif sur les nominations ministéielles, pouvoir unique à cette province dans le systéme canadien et le systéme comparatif de Westminster, mais il établit également la norme de mérite comme un mérite relatif, c'est‐à‐dire la nomination de la personne la mieux qualifiée parmi tous les candidats et non simplement la nomination d'une personne qualifiée. Le présent article examine I'expérience de cette province et conclut qu'un système de nomination au mérite visant le mérite relatif peut être mis en place, mais seulernent à condition de limiter le pouvoir des ministres à opposer leur veto à la nomination de candidats par les organismes, régies et commissions gouvernementaux.  相似文献   
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