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Isotope ratio mass spectrometry as a tool for forensic investigation (examples from recent studies).
James F Carter Richard Sleeman Jenny C Hill Fay Idoine Emma L Titterton 《Science & justice》2005,45(3):141-149
The versatility of isotope ratio mass spectrometry is demonstrated by reference to diverse case studies. Variations in the natural isotopic composition of non-biological, organic materials are compared as a means by which samples may be associated or discriminated. These techniques may be used to augment or compliment conventional forensic methodologies. delta13C analysis was used to demonstrate that different masking tape had been recovered in two, apparently similar cases, involving the smuggling of money. Visually similar ecstasy tablets were compared by consideration of the delta13C and delta15N composition of MDMA extracted from the tablets. Although only a limited number of tablets were analysed, the isotopic similarity between two different seizures was sufficient to induce a guilty plea from a person suspected of possessing both. A combination of delta2H, delta13C, delta15N and delta18O together with GC-MS analyses were applied to small samples of seized heroin. Although GC-MS analysis indicated differences between the chemical composition of two of the heroin samples, isotopic analysis suggested similarities, which were confirmed by further delta2H, delta13C and delta18O isotopic analysis of the clingfilm in which the samples were wrapped. 相似文献
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James S. Larson 《政策研究评论》2000,17(4):99-110
This study evaluates the emerging field of medical outcomes research based on interviews at Harvard Medical School. Medical outcomes research at Harvard is multifaceted, but may be summarized as involving certain key components. The emphasis at Harvard is on “quality of care,” viewed as a combination of outcomes evaluation and process evaluation, delivery of the service and its result. In a time of shrinking budgets, outcomes and process research can be justified economically because of the relatively low cost of patient self‐reports and because of their usefulness. Physicians may be motivated to measure quality of care by emphasizing the positive effects of research on the process of care and outcomes. Medical outcomes research is a field that is undergoing change and is becoming increasingly oriented toward the practical needs of patients and physicians. 相似文献
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James R. Thompson 《Public administration review》2000,60(6):508-521
The conclusion of the Clinton Administration presents an opportune time to investigate the outcomes of the National Performance Review (NPR). Any such evaluation, however, is complicated by the nature of the objectives sought, many of which relate to subtle and elusive elements of organizational life: empowering employees, inducing a less risk-adverse culture, and enhancing the quality of service delivery. The strategy employed here as a means of gaining insight into such phenomena was to couple a broad review of government-wide survey results with an in-depth investigation into the impact of NPR on a single agency, the Social Security Administration. A conclusion is that many of the NPR's "higher-order" objectives have not been met on a systemic basis. While a variety of proximate explanations for this finding can be identified, a more fundamental explanation relates to a failure by the sponsors to adjust their strategy to account for basic differences between NPR and past reforms. 相似文献
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Netherlands International Law Review - 相似文献
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James C. McDavid Annette E. Mueller 《Canadian public administration. Administration publique du Canada》2008,51(4):589-615
Abstract: The primary purpose of this article is to investigate the factors that predict the efficiency of residential recycling collection services in Canadian local governments. The findings are based on a survey of 128 residential recycling producers from all regions of Canada. One of the most significant findings is the lack of a relationship between private‐sector companies collecting recyclables and the overall efficiency of collection operations. The dominance of the private‐sector collection of recyclables (over seventy‐seven per cent of all producers were contracted companies) does not translate into greater efficiencies. The most important variables in the model are amenable to local control. They include tonnes collected per vehicle per year, requiring full bins, inclusion of composting operations in the overall recycling program, the number of different kinds of materials recycled, participation rate, and reliance on side‐loading collection vehicles. Among the direct predictors of unit costs, the key underlying factor is the productivity of residential recycling operations. Because recyclables are marketed, handling them takes time, reduces the weights that collection vehicles can carry, and generally reduces productivity. Even diligent efforts to improve productivity will not bring recycling costs down to the levels for residential solid‐waste collection. Sommaire: L'objectif principal du présent article est d'examiner les facteurs qui prévoient l'efficacité des services de collecte de produits recyclables résidentiels dans les municipalités canadiennes. Les résultats reposent sur un sondage réalisé auprès de 128 producteurs de collecte de produits recyclables résidentiels opérant dans toutes les régions du Canada. L'un des résultats les plus notoires est le manque de relations entre les sociétés du secteur privé qui récupèrent les produits recyclables et l'efficacité d'ensemble des opérations de collecte. La prédominance de la collecte de produits recyclables par le secteur privé (plus de soixante‐dix‐sept pour cent de tous les producteurs étaient des sociétés contractuelles) ne se traduit pas par une plus grande efficacité. Les variables les plus importantes du modèle peuvent faire l'objet d'un contrôle local. Elles comprennent les tonnes récupérées par véhicule par an, l'exigence de poubelles pleines, l'inclusion d'opérations de compostage au programme général de recyclage, le nombre de différentes sortes de matériaux recyclés, le taux de participation, et le recours à des camions de collecte à chargement latéral. Parmi les variables explicatives directes des coûts unitaires, le principal facteur sous‐jacent est la productivité des opérations de recyclage résidentiel. Comme les produits recyclables sont commercialisés, leur manutention prend du temps, réduit le poids que les camions de collecte peuvent transporter, et réduit d'une manière générale la productivité. Même des efforts diligents pour améliorer la productivité ne feront pas baisser les coûts du recyclage aux niveaux de ceux de la collecte des déchets solides résidentiels. 相似文献