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151.
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Abstract

This article uses culture of poverty and rational choice theories of poverty to explain how quickly nonelderly household heads leave public housing. Data from the Panel Study of Income Dynamics serve as the basis for the analysis.

Although a significant proportion of all household heads have public housing spells lasting five or more years, the majority have spells lasting less than five years. The availability of other housing options has a strong impact on how quickly individuals move out of public housing. Family structure and human capital play a more modest role. To the extent that one's childhood experiences affect the likelihood of exiting public housing, they appear to do so mostly through their effect on the acquisition of human capital. Finally, the evidence presented is inconsistent with the notion that public housing is a trap from which it is more difficult to escape the longer one lives in it.  相似文献   
153.
Neck injuries resulting from motor vehicle collisions (MVC), often referred to as whiplash trauma and injury, often demonstrate little or no evidence of significant tissue damage. In rare instances, however, serious injury to the anterior neck organ injuries can result from such trauma. The present study describes esophageal injury associated with rear-impact collisions, based on a unique case report, review of the scientific literature and a query in the National Automotive Sampling System (NASS) database of the US National Highway Traffic Safety Administration. The Medline search and present case study totaled five cases of rear-impact collision-related serious esophageal injury (laceration or rupture). In the four published cases all patients survived, whereas in the presented case study, the patient died due to mediastinitis and sepsis. The NASS query revealed an additional three cases out of a total of 55,926 investigated crashes. All three cases were associated with fatalities. Although no anatomical or bioengineering studies have presented data on the behavior of the esophagus during rear-impact whiplash loading, sudden tensile and/or compressive forces is the likely explanation of injury, often in combination with a local fracture of a vertebral body. In these 8 cases significant esophageal injury carried a substantial (50%) risk of mortality. Clinicians should be aware of the potential for significant complications in the whiplash trauma-exposed patient who complains of chest pain, mid-thoracic pain, discomfort in the neck and throat, respiratory distress, or hoarseness. For those forensic specialists involved in whiplash cases these study results highlight the need to consider esophageal injuries as a rare but potential consequence of whiplash trauma.  相似文献   
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The PowerPlex 16 BIO multiplex short tandem repeat (STR) system contains the 13 CODIS loci (FGA, TPOX, D8S1179, vWA, D18S51, D21S11, TH01, D3S1358, CSF1PO, D16S539, D7S820, D13S317, and DS5S818), plus two pentanucleotide repeat loci (Penta D and Penta E) and the sex-identifying locus. Amelogenin. The PowerPlex 16 BIO System is optimized for use with the Hitachi FMBIO gel imaging systems. A consortium of seven independent laboratories collaborated to perform the studies defined by the FBI standards for performing a developmental validation, including the evaluation of sample concordance, percent stutter determination, nonprobative casework, precision, sensitivity, mixture determination, effect of substrates, the impact of environmental insults, and species specificity. All samples tested for concordance were consistent except for one sample from the Virginia Division of Forensic Science database that displayed discordance at D13S317, a locus whose primer sequence was altered. Stutter values were comparable to those of other STR multiplex systems, the precision was comparable to other multiplexes analyzed by gel electrophoresis, the DNA profiles were unchanged by the substrate upon which the blood samples were placed, and the nonprobative casework samples re-typed for the PowerPlex 16 BIO System were consistent with previous typing results. When greater than 0.125 ng of DNA was placed into the PowerPlex 16 BIO System amplification reaction, a full profile was generated by all laboratories. The mixture study results were comparable to those reported for other multiplex systems, the environmental study demonstrated a loss of larger molecular weight loci when samples were incubated at elevated temperatures for a prolonged period of time, and the only notable cross species hybridization was observed with primate DNA samples. This extensive validation work performed demonstrates that the PowerPlex 16 BIO System provides STR data of a quality comparable with other PowerPlex STR multiplex kits as well as other widely used STR multiplexes and is thus suitable for evidentiary casework analysis as well as database sample profiling.  相似文献   
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The Everglades is an intensively managed ecosystem where control of the water has allowed agricultural, urban and economic development, while struggling to meet biodiversity conservation goals. The over 100 year history of control began in response to a disastrous series of floods and droughts followed by environmental crises at an ecosystem scale. Each of these events precipitated technological fixes that extended control of water resources. Institutional structures have been continually reorganized over the last century to meet shifting social objectives, the latest of which is ecosystem restoration. However, the basic response, which employs engineering and technological solutions, is a type of social trap, where governmental mandates, planning-based paradigms and vested interests all interact to inhibit the resolution of chronic environmental issues. Experience from other resource systems indicates that in such an inherently complex system wrought with multiple uncertainties, restoration must be discovered through experimentation and learning embraced by adaptive management. Though minimal steps towards adaptive management have been made, we argue that adaptive forms of experimentation and governance are needed to resolve chronic resource issues and achieve restoration goals.  相似文献   
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In this article we share our experiences helping students to think critically about global issues by using the data and the conceptual innovations presented by the authors of the United Nations Development Programme's Human Development Report We discuss a number of strategies we have applied to actively engage students in the analysis of the extensive data in the Report and the approaches we have taken to help our students understand both the research and the policy implications of the diverse conceptual frameworks introduced in each annual edition. By using a publication that introduces new concepts, new measures, and new insights in each annual edition, we help our students to see how social scientists work and how knowledge is constructed. At the same time, by requiring them to use the data to analyze, compare, and conceptualize, we show them they can "do" social science and discover for themselves some of the realities of the global community described in the more traditional texts.  相似文献   
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