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161.
"This article examines the probable effects of the North American Free Trade Agreement (NAFTA) on migration from Mexico to the United States, disputing the view that expansion of jobs in Mexico could rapidly reduce undocumented migration. To the extent that NAFTA causes Mexican export agriculture to expand, migration to the United States will increase rather than decrease in the short run. Data collected in both California and the Mexican State of Baja California show that indigenous migrants from southern Mexico typically first undertake internal migration, which lowers the costs and risks of U.S. migration. Two features of employment in export agriculture were found to be specially significant in lowering the costs of U.S. migration: first, working in export agriculture exposes migrants to more diverse social networks and information about U.S. migration; second, agro-export employment in northern Mexico provides stable employment, albeit low-wage employment, for some members of the family close to the border (especially women and children) while allowing other members of the family to assume the risks of U.S. migration."  相似文献   
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Implementing partial least squares   总被引:2,自引:0,他引:2  
Partial least squares (PLS) regression has been proposed as an alternative regression technique to more traditional approaches such as principal components regression and ridge regression. A number of algorithms have appeared in the literature which have been shown to be equivalent. Someone wishing to implement PLS regression in a programming language or within a statistical package must choose which algorithm to use. We investigate the implementation of univariate PLS algorithms within FORTRAN and the Matlab (1993) and Splus (1992) environments, comparing theoretical measures of execution speed based on flop counts with their observed execution times. We also comment on the ease with which the algorithms may be implemented in the different environments. Finally, we investigate the merits of using the orthogonal invariance of PLS regression to improve the algorithms.  相似文献   
164.
Applied sociology is basically what sociologists do for nonsociologists and sometimes for themselves. Applied sociology includes the teaching of sociology as one of the liberating arts and sciences. It also involves the practice of sociology outside academia in the public and private sectors. Either way, applied sociology needs support groups, and state sociological associations need useful things to do beyond their traditional interests in academic teaching and research. Professional sociological associations, and especially those that serve at the local, state level, can become important support groups for applied sociology. This article suggests five types of applied sociology projects appropriate for state associations. These are volunteering applied sociology; doing applied sociology through consulting; making the value of sociological applications more visible; identifying applied sociology jobs for our baccalaureate, master's, and doctoral graduates; and helping to improve the socioeconomic outlook for our academic colleagues and, in turn, ourselves. State associations provide an organizational base, proximate members, and local opportunities for applying sociology. Ron Wimberley, teaches sociological research methods and does research on the southern Black Belt and other topics. He also attempts applied sociology through volunteer work, consulting, and occasional leaves from his university position. Catherine Harris of Wake Forest University is appreciated for suggesting the topic. The author is responsible for the views expressed in the article.  相似文献   
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This Issue Brief provides an overview of the issues relating to the Employee Retirement Income Security Act of 1974 (ERISA) and health benefit plans, the major case law relating to ERISA and health plans, and the implications of the preemption of state regulations for health plan sponsors and participants. It also presents the latest data on the number of health plan participants in self-funded ERISA plans. Finally, it presents a summary of current legislative proposals that would attempt to amend ERISA. Under the framework ERISA established for employee benefit plans, the regulation of employment-based health benefit plans has evolved into a two-tiered system in which both federal and state laws play important roles. The Supreme Court has interpreted ERISA's "savings" and "deemer" clauses to mean that insured plans are subject to regulations directly at the federal level and indirectly at the state level, while self-funded plans are regulated exclusively at the federal level. The ERISA statute and the courts' interpretations of the Act have created a sharp controversy over how employee health benefit plans are provided and administered, with state regulators and consumer advocates on one side of the debate and plan sponsors (e.g., employers and unions) on the other. State regulators and consumer advocates tend to favor more regulation, and in many instances greater regulation at the state level, which they argue would provide more protections for consumers. However, employers and unions (or any plan sponsors) think ERISA preemption is very important to their ability to provide innovative and cost-effective health benefits for their employees, and assert that ERISA's present structure should be preserved. The U.S. General Accounting Office (GAO) found that 44 million individuals (39 percent of those in ERISA plans) were enrolled in self-funded ERISA plans in 1993, up from 39 million (33 percent of those in ERISA plans) in 1989. The Employee Benefit Research Institute (EBRI), using the same methodology as GAO with 1995 data, estimated that 48 million individuals (39 percent of those in ERISA plans) were enrolled in self-funded ERISA plans in 1995. When policymakers look to amend ERISA, they should consider whether the change to ERISA will produce a higher level of quality for consumers than is being provided under the present system and will continue to do so in the future. Policymakers must also decide whether quality of care is better enhanced by health plans' greater exposure to liability or by market forces. If policymakers decide that increased exposure to liability is the route to go, will consumers be able to enjoy any potential improvement in quality or will more individuals end up uninsured because of increased costs and not be able to get any care regardless of the quality?  相似文献   
167.
Sample selection in radiocarbon dating   总被引:1,自引:0,他引:1  
Archaeologists working on the island of O'ahu, Hawai'i, use radiocarbon dating of samples of organic matter found trapped in fish-pond sediments to help them to learn about the chronology of the construction and use of the aquicultural systems created by the Polynesians. At one particular site, Loko Kuwili, 25 organic samples were obtained and funds were available to date an initial nine. However, on calibration to the calendar scale, the radiocarbon determinations provided date estimates that had very large variances. As a result, major issues of chronology remained unresolved and the archaeologists were faced with the prospect of another expensive programme of radiocarbon dating. This paper presents results of research that tackles the problems associated with selecting samples from those which are still available. Building on considerable recent research that utilizes Markov chain Monte Carlo methods to aid archaeologists in their radiocarbon calibration and interpretation, we adopt the standard Bayesian framework of risk functions, which allows us to assess the optimal samples to be sent for dating. Although rather computer intensive, our algorithms are simple to implement within the Bayesian radiocarbon framework that is already in place and produce results that are capable of direct interpretation by the archaeologists. By dating just three more samples from Loko Kuwili the expected variance on the date of greatest interest could be substantially reduced.  相似文献   
168.
Siblings who have suffered severe trauma and disrupted attachment relate to one another in ways that interfere with individual development, the chance to benefit from connections with adults, the establishment of healthy sibling relationships, and the working through of traumatic experiences. The authors use case examples to illustrate four distinct sibling patterns: absent, adult lockout, half and half, and trauma shield. The authors highlight the importance of recognizing these types and then varying the therapist's treatment stance to pursue five goals. These include suspending problematic sibling relationships to create room for bonding with caring adults, transferring attachment behaviors and impulses to a receptive adult, resuming healthy individual development, forming more adaptive sibling connections, and expressing shared traumatic content.  相似文献   
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170.
As hospitals and health care systems maneuver for a position in the integrated health care delivery system, no initiative is more important than building an effective and competitive primary care network. Yet this critical initiative is fraught with potential pitfalls. In their haste to develop primary care networks, hospitals and health care systems may fail to thoroughly evaluate network participants and in turn create large, inclusive, and inefficient primary care networks that don't come close to breaking even, much less repay practice acquisition costs. In an effort to become more efficient, practitioners often find themselves in the unenviable position of "de-selecting" peers retrospectively. The author presents criteria for evaluating and selecting network physicians.  相似文献   
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