首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 15 毫秒
1.
In this article, I examine the impact of neoliberalism and welfare reform on the delivery of Medicaid, specifically how the advent of Medicaid managed care (MMC) has been wrought with contradictions, placing increased burdens on primary safety-net organizations and impacting the many communities they serve. I argue that federally qualified health centers (FQHCs) operate as a primary safety net among safety-net providers, supporting and subsidizing New Mexico's MMC program financially and administratively. By presenting ethnographic data, I will demonstrate how FQHCs pay many of the hidden financial and institutional costs of the shift to managed care. Such findings uncover paradoxes inherent to neoliberal ideologies and privatization, raising questions about the efficacy of a managed care system for Medicaid as well as the future of the health care safety net and access to health care for the diverse populations it serves.  相似文献   

2.
Underwater acoustics in marine fisheries and fisheries research   总被引:9,自引:0,他引:9  
Underwater acoustics enables the detection and precise location of fish and is therefore a prerequisite for effective fishing methods such as pelagic trawling and purse seining. The application of acoustic instruments to detect fish and monitor gear performance in modern commercial fisheries is outlined. The latest developments in obtaining information such as bottom roughness and determining such characteristics of fish detected as size and species are presented.Echo integration is now widely used to estimate the abundance of commercially important fish stocks. The principles of the method are outlined briefly, and special emphasis is put on such effects of fish behaviour as the dramatic influence of fish orientation on its backscattering cross section, the possible effects of vessel avoidance, and the uncertainties connected with spatial variability.The use of acoustic tags, echosounders and sonar to study and quantify fish behaviour and distribution is outlined, with particular attention to new developments that provide detailed information on fish behaviour and distribution in relation to environmental parameters.Future developments and improvements in the application of underwater acoustics to commercial fisheries and fisheries research are suggested  相似文献   

3.
Noncompliance with study medications is an important issue in the design of endpoint clinical trials. Including noncompliant patient data in an intention-to-treat analysis could seriously decrease study power. Standard methods for calculating sample size account for noncompliance, but all assume that noncompliance is noninformative, i.e., that the risk of discontinuation is independent of the risk of experiencing a study endpoint. Using data from several published clinical trials (OPTIMAAL, LIFE, RENAAL, SOLVD-Prevention and SOLVD-Treatment), we demonstrate that this assumption is often untrue, and we discuss the effect of informative noncompliance on power and sample size.  相似文献   

4.
1. To manage the environmental flow requirements of sedentary taxa, such as mussels and aquatic insects with fixed retreats, we need a measure of habitat availability over a variety of flows (i.e. a measure of persistent habitat). Habitat suitability measures in current environmental flow assessments are measured on a ‘flow by flow’ basis and thus are not appropriate for these taxa. Here, we present a novel measure of persistent habitat suitability for the dwarf wedgemussel (Alasmidonta heterodon), listed as federally endangered in the U.S.A., in three reaches of the Delaware River. 2. We used a two‐dimensional hydrodynamic model to quantify suitable habitat over a range of flows based on modelled depth, velocity, Froude number, shear velocity and shear stress at three scales (individual mussel, mussel bed and reach). Baseline potentially persistent habitat was quantified as the sum of pixels that met all thresholds identified for these variables for flows ≥40 m3 s?1, and we calculated the loss of persistently suitable habitat by sequentially summing suitable habitat estimates at lower flows. We estimated the proportion of mussel beds exposed at each flow and the amount of change in the size of the mussel bed for one reach. 3. For two reaches, mussel beds occupied areas with lower velocity, shear velocity, shear stress and Froude number than the reach average at all flows. In the third reach, this was true only at higher flows. Together, these results indicate that beds were possible refuge areas from the effects of these hydrological parameters. Two reaches showed an increase in the amount of exposed mussel beds with decreasing flow. 4. Baseline potentially persistent habitat was less than half the areal extent of potentially suitable habitat, and it decreased with decreasing flow. Actually identified beds and modelled persistent habitat showed good spatial overlap, but identified beds occupied only a portion of the total modelled persistent habitat, indicating either that additional suitable habitat is available or the need to improve habitat criteria. At one site, persistent beds (beds where mussels were routinely collected) were located at sites with stable substratum, whereas marginal beds (beds where mussels were infrequently collected or that were lost following a large flood event) were located in scoured areas. 5. Taken together, these model results support a multifaceted approach, which incorporates the effects of low and high flow stressors, to quantify habitat suitability for mussels and other sedentary taxa. Models of persistent habitat can provide a more holistic environmental flow assessment of rivers.  相似文献   

5.
6.
Matsui S 《Biometrics》2005,61(3):816-823
This article develops methods for stratified analyses of additive or multiplicative causal effect on binary outcomes in randomized trials with noncompliance. The methods are based on a weighted estimating function for an unbiased estimating function under randomization in each stratum. When known weights are used, the derived estimator is a natural extension of the instrumental variable estimator for stratified analyses, and test-based confidence limits are solutions of a quadratic equation in the causal parameter. Optimal weights that maximize asymptotic efficiency incorporate variability in compliance aspects across strata. An assessment based on asymptotic relative efficiency shows that a substantial enhancement in efficiency can be gained by using optimal weights instead of conventional ones, which do not incorporate the variability in compliance aspects across strata. Application to a field trial for coronary heart disease is provided.  相似文献   

7.
8.
R B Thompson 《FASEB journal》2001,15(10):1671-1676
'Blockbuster' drugs, which are widely prescribed and improve the health of millions, often originate in fundamental laboratory research. An important example of such drugs are the cholesterol-lowering drugs called 'statins', including Zocor, Pravachol, and Lipitor, which millions of people take in the U.S. every year. This short paper outlines the direct and indirect contributions of federally sponsored research to the development of these important drugs.  相似文献   

9.
Confirmation in evolutionary biology depends on what biologists take to be the genuine rivals. Investigating what constrains the scope of biological possibility provides part of the story: explaining how possible helps determine what counts as a genuine rival and thus informs confirmation. To clarify the criteria for genuine rivalry I distinguish between global and local constraints on biological possibility, and offer an account of how-possibly explanation. To sharpen the connection between confirmation and explaining how possible I discuss the view that formal inquiry can provide a kind of confirmation-theoretic support for evolutionary models, and offer an example of how-possibly explanation interacting with testing practice.  相似文献   

10.
11.
12.
13.
O'Malley AJ  Normand SL 《Biometrics》2005,61(2):325-334
While several new methods that account for noncompliance or missing data in randomized trials have been proposed, the dual effects of noncompliance and nonresponse are rarely dealt with simultaneously. We construct a maximum likelihood estimator (MLE) of the causal effect of treatment assignment for a two-armed randomized trial assuming all-or-none treatment noncompliance and allowing for subsequent nonresponse. The EM algorithm is used for parameter estimation. Our likelihood procedure relies on a latent compliance state covariate that describes the behavior of a subject under all possible treatment assignments and characterizes the missing data mechanism as in Frangakis and Rubin (1999, Biometrika 86, 365-379). Using simulated data, we show that the MLE for normal outcomes compares favorably to the method-of-moments (MOM) and the standard intention-to-treat (ITT) estimators under (1) both normal and non-normal data, and (2) departures from the latent ignorability and compound exclusion restriction assumptions. We illustrate methods using data from a trial to compare the efficacy of two antipsychotics for adults with refractory schizophrenia.  相似文献   

14.
M M Burgess 《CMAJ》1989,141(8):777-780
Physicians have an ethical responsibility for cost-saving within the current medical care delivery system. Noncompliance and overtreatment are among the causes of excessive health care expenses. An effective means of improving compliance and avoiding unwanted or fruitless treatment is improved physician-patient communication. Improved communication is also the most ethical means of avoiding these expenses. The educated participation of patients in treatment decisions and of the public in health policy formation is ethically and economically preferable to bureaucratic responses and user fees. The public must be made aware of the costs and limited benefits of medical treatments and of the effects of lifestyle on health. The medical encounter must become more supportive and educational. Medical school curricula must emphasize patient involvement, which must be reinforced to medical students and residents by staff physicians'' genuine concern and effort. Quality assessments and assurance should include evaluation of communication, patient satisfaction, use of follow-up and duplication of services.  相似文献   

15.
J. M. Caffrey 《Hydrobiologia》1996,340(1-3):259-263
Glyphosate is the active ingredient of the broad-spectrum, translocated herbicide Roundup. Glyphosate is cleared for safe use in or near watercourses, being rated virtually non-toxic by the World Health Organisation. Trials in and alongside Irish fishery watercourses first commenced in 1989 and are continuing to date. The aim of this work is to evaluate the product's efficacy in clearing nuisance reed species in recreational fisheries. The longevity of control and impact on the habitat and its fauna is also investigated. Trials in canal fisheries have demonstrated the capacity of glyphosate to remove obstructive stands of reeds (mainly Schoenoplectus lacustris, Glyceria maxima, Phragmites australis, Sparganium erectum and Typha latifolia), so creating reed-free areas and swims for anglers. These swims remained open for three years following a single application. In 1992 a trial over a 3 km length of the River Boyne, a renowned salmonid fishery, was undertaken. The results clearly demonstrated the ability of glyphosate to provide long-term control of dense (354 shoots m–2) Schoenoplectus infestations in a large watercourse. In the year following, less than one shoot per m2 was present in the channel. In 1994 a small increase in density (7.6 shoots m–2 was recorded, so enabling unobstructed angling in a stretch of river that had been virtually unfishable for years. Trout (Salmo trutta L.) and salmon (Salmo salar L.) also used the newly exposed gravels for spawning in the winter of 1993, thereby improving fish recruitment and production in the fishery.  相似文献   

16.
Genetics in fisheries management   总被引:2,自引:1,他引:1  
Ward  R. D. 《Hydrobiologia》2000,420(1):191-201
Genetic analyses have much to offer fisheries managers, especially in the provision of tools enabling unequivocal specimen identification and assessment of stock structure. The three commonly-used genetic tools – allozymes, mitochondrial DNA and microsatellites – differ in their properties. These differences must be born in mind, especially when interpreting gene frequency data collected for stock structure research. Examples where genetic approaches have been used to identify specimens are given, with special attention being given to compliance and labelling issues. Treatment of stock structure focuses on Atlantic cod and on yellowfin, bigeye and albacore tunas. The different resolving powers of the various techniques are discussed. Marine fish typically show low levels of population genetic differentiation, and in such species the use of large sample sizes and, preferably, multiple types of markers are desirable to resolve stock structure issues.  相似文献   

17.
18.
Shark depredation, where a shark partially or completely consumes an animal caught by fishing gear before it can be retrieved to the fishing vessel, occurs in commercial and recreational fisheries worldwide, causing a range of negative biological and economic impacts. Despite this, it remains relatively understudied compared to other fisheries issues. This is the first review of the literature relating to shark depredation, which also includes an overview of the potential mechanisms underlying its occurrence and options for mitigation. Furthermore, this review highlights key research gaps that remain to be investigated, thereby providing impetus for future research. In total, 61 studies have been published between 1955 and 2018, which include information on shark depredation. These studies recorded quantitative rates of depredation between 0.9 and 26% in commercial and recreational fisheries and during research fishing, identified 27 shark species from seven families that were responsible for depredation and discussed potential factors influencing its occurrence. Information from research into bycatch mitigation and the testing of shark deterrent approaches and technologies is also presented, in the context of applying these approaches to the reduction of shark depredation. This review presents an holistic overview of shark depredation in fisheries globally and, in doing so, provides a central resource for fisheries researchers and managers focusing on this topic to stimulate further collaborative research on this important fisheries issue.  相似文献   

19.
Prehistoric fisheries in the Caribbean   总被引:1,自引:0,他引:1  
We studied faunal remains from archaeological sites on five Caribbean islands, each with an early (1,850-1,280 years B.P.) and late (1,415-560 years B.P.) occupation. On each of these islands (Puerto Rico, St. Thomas, St. Martin, Saba, and Nevis), the mean size of reef fishes in the faunal remains declined from the early to the late occupation. The large samples from sites on St. Thomas and Nevis allowed examination of the size distribution of individual taxa. Samples of obligate reef fishes (Scaridae, Acanthuridae, Lutjanidae, and Serranidae) showed large reductions in size between the early and late occupations. Samples of facultative reef fishes (Carangidae and Clupeidae) showed little change in size frequency distribution. The percentage of estimated reef fish biomass in the total aquatic faunal record sharply declined in the samples from four of the islands, while on Nevis there was a slight increase. The mean trophic level of reef fishes declined from the early to the late occupations on each island. Together these patterns suggest that populations of reef fishes adjacent to occupation sites on these islands were heavily exploited in prehistoric times. Such exploitation resulted in shifts in size structure and species composition among the reef fish fauna. On some islands the decline in reef fish resources corresponded with a shift towards greater exploitation of pelagic species.  相似文献   

20.
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号