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Using panel data that track individual students from year to year, we examine the effects of charter schools in North Carolina on racial segregation and black‐white test score gaps. We find that North Carolina's system of charter schools has increased the racial isolation of both black and white students, and has widened the achievement gap. Moreover, the relatively large negative effects of charter schools on the achievement of black students is driven by students who transfer into charter schools that are more racially isolated than the schools they have left. Our analysis of charter school choices suggests that asymmetric preferences of black and white charter school students (and their families) for schools of different racial compositions help to explain why there are so few racially balanced charter schools. © 2006 by the Association for Public Policy Analysis and Management. 相似文献
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Despite the fact that the Reagan election was viewed as a power shift toward the West, the decade of the 1980s produced cruel disappointment. The region was generally left out of the economic recmery of the nation because of the bust in the agricultural and mineral industries. These state and local gmernments which sufferfrom high costs and low resources were particularly dependent on the national gmernment at the very time when the Reagan Administration was cutting federal aid and transferring power to the states. Unlike Nixon's New Federalism which helped the state and local governments of the West, Reagan's policies caused their relative position in federal aid flows to deteriorate. Although the Reagan revolution in cutting domestic programs was viewed as the embodiment of western rugged individualism, the region lost in terms of federal aid to small rural local governments. 相似文献
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Clark K 《Journal of law and medicine》2002,9(3):303-322
Claims that the practice of obstetrics is in crisis appear regularly in the media, but evidence for the claims is scarce. This article examines a range of evidence from Australia and overseas and explores the relationship between obstetric practice and litigation. While anecdotal evidence abounds, there is no hard evidence to confirm that litigation is the threat to obstetric practice that many practitioners strongly believe it is. It is likely that such practitioners respond by practising defensive medicine but this is very difficult to measure. 相似文献
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Mitochondrial DNA (mtDNA) analysis of forensic samples typically is performed when the quantity and quality of DNA are insufficient for nuclear DNA analysis or when maternal relatives may be the only reference source. Many of the steps required in the analytical process are both lengthy and labor intensive. Therefore, improvements in the process that reduce labor without compromising the quality of the data are desirable. The current procedure requires purification of the amplicons by centrifugal filtration after PCR and prior to cycle sequencing. Because this method requires several manipulations to perform, alternate cleanup procedures were investigated. These include the use of 1) Qiagen QlAquick PCR Purification columns, 2) Concert Rapid PCR Purification columns, and 3) ExoSAP-IT reagent. When the yield of purified amplicons, quality of the sequence profile, and ease of assay were evaluated, the use of ExoSAP-IT reagent for post-amplification purification was chosen to replace the filtration method. 相似文献
69.
This paper considers a form of the Tullock imperfectly discriminating rent-seeking game in which the contestants are uncertain about the value of a bias parameter in the probability of winning function. Beliefs about this unknown parameter are not constrained to be static; we consider two methods by which the players' prior beliefs on this parameter can be updated. First, we allow for information to emerge by considering the case in which the game is played twice, with the outcome of the first game known before the second begins. The identity of the winner of the first contest represents information which emerges endogenously that can be used to revise beliefs on the unknown bias parameter. Second, information can be produced outside of the model by an external agency; this gives rise to exogenous learning. We consider the consequences for rent-seeking in each of these two cases. 相似文献
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This paper considers the division of a public budget among competing interests. The planner determines the optimal allocation by maximizing a weighted social welfare function. These weights reflect society's attitudes to different recipient groups, and are not constrained to be constant. By exerting “pressure”, the recipients can attempt to manipulate the weights and hence influence the division of the budget. The amount of resources used on pressure, and the effects on the preference weights are calculated. An important parameter in the model is the elasticity of pressure, for which an appropriate estimate is presented from the case of competition for a share of a health services budget in Norway. 相似文献