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101.
Given the ethical controversies concerning HIV vaccine trials (HVTs), we aimed to understand through an exploratory study how members of institutional review boards (IRBs) in the United States (US) and research ethics committees (RECs) in South Africa (SA) view issues concerning the process and content of reviews of these studies. We mailed packets of 20 questionnaires to 12 US IRB chairs and administrators and seven REC chairs to distribute to their members. We received 113 questionnaires (76 from the US and 37 from SA). In both countries, members tended to be white males with advanced academic degrees. Compared to the US, SA members called for ‘major changes’ in HVT protocols more frequently (p = 0.004), and were less likely to think that HVT participants understood risks and benefits (p = 0.033) or informed consent forms (p = 0.000). In both countries, members were divided on several critical issues (e.g. the minimum standard for treatment for HVT participants who became infected during the HVT), but agreed that they needed more training. Of the SA respondents, 40% reported that they were ‘self‐taught’ in ethics. This study, the first we know of to offer quantitative data comparing US vs. non‐US IRBs/RECs, thus suggests key similarities and differences (e.g. compared to SA respondents, US respondents appeared to overestimate participants' understanding of informed consent), along with needs for education. These initial exploratory data in this area have important implications for IRBs, RECs, policy‐makers and scholars concerning future practice, training, policy, and investigations in research ethics, and prevention and treatment of HIV and other diseases in the developing world and elsewhere.  相似文献   
102.
The widespread popularity of life-cycle assessment (LCA) is difficult to understand from the point of view of instrumental decision making by economic agents. Ehrenfeld has argued, in a 1997 issue of this journal, that it is the world-shaping potential of LCA that is more important than its use as a decision-making tool. The present study attempts to explore the institutionalization of this "LCA world view" among ordinary market actors. This is important because environmental policy relies increasingly on market-based initiatives. Cognitive and normative assumptions in authoritative LCA documents are examined as empirical data and compared with data from focus group interviews concerning products and the environment with "ordinary" manufacturers, retailers, and consumers in Finland. These assumptions are (1) the "cradle-to-grave" approach, (2) the view that all products have an environmental impact and can be improved, (3) the relativity of environmental merit, and (4) the way responsibility for environmental burdens is attributed. Relevant affinities, but also differences, are identified. It is argued that life-cycle thinking is not primarily instrumental, but rather is gaining a degree of intrinsic value. The study attempts to establish a broader institutional context in which the popularity of LCA can be understood. From the point of view of this broader context, some future challenges for the development of LCA and life-cycle thinking are suggested.  相似文献   
103.
Mouillot D  Simková A  Morand S  Poulin R 《Oecologia》2005,146(2):269-278
The factors that control biodiversity have been the focus of numerous recent investigations; these include species interactions, speciation, environmental gradients and heterogeneity, all of these operating differently at each observation scale. We used a null model to examine the influence of two forces shaping the community structure of Dactylogyrus species parasitic on roach (Rutilus rutilus) gills: interspecific competition that might prevent the coexistence of the most similar species and environmental filters that might result in the most similar species coexisting together. The study was carried out on two sets of fish from two different localities in the Morava river basin (Czech Republic) to evaluate the consistency of the results across host populations, and at three different scales of observation to test for the scale dependence of assembly rules. In decreasing order, from largest to smallest, the three spatial scales investigated were: the individual fish, the individual gill arch and individual sections of each gill arch. The similarity between pairs of parasite species was measured using three different criteria: (1) phylogeny, (2) quantitative functional traits consisting of parasite size and morphometric measurements of the attachment organ’s sclerotized parts and (3) qualitative attributes of reproductive organs. First, our study reveals a strong conservatism of ecological characters for the nine Dactylogyrus parasite species, in particular regarding the attributes of their copulatory organs. Second, our study did not find any limitation of similarity among coexisting Dactylogyrus species due to interspecific competition, irrespective of the scale and the similarity measures considered. Conversely, our results support the niche filtering hypothesis, preventing the co-occurrence of species too dissimilar from one another. This process is particularly apparent at the scale of the individual fish and for functional traits associated with the hard parts of the parasites’ attachment organs. In both localities, the Dactylogyrus species that occur on the same fish individuals tend to have similar values for the haptor dimensions. Our study supports previous studies on monogenean parasite communities indicating a weak influence of competition as a structuring force, but it goes a step further by identifying environmental filtering as a key process shaping these communities.  相似文献   
104.
Perspective: the size-complexity rule   总被引:3,自引:0,他引:3  
It is widely accepted that bigger entities have a greater division of labor than smaller ones and this is reflected in the fact that larger multicellular organisms have a corresponding increase in the number of their cell types. This rule is examined in some detail from very small organisms to large animals, and plants, and societies. Compared to other size-related rules, the size-complexity rule is relatively rough and approximate, yet clearly it holds throughout the whole range of living organisms, as well as for societies. The relationship between size and complexity is analyzed by examining the effects of size increase and decrease: size increase requires an increase in complexity, whereas size decrease permits, and sometimes requires, a decrease in complexity. Conversely, an increase or decrease in complexity permits, but does not require changes in size. An especially compelling argument for the close relation between size and complexity can be found in size quorum sensing in very small multicellular organisms.  相似文献   
105.
The quality of a chosen partner can be one of the most significantfactors affecting an animal's long-term reproductive success.We investigate optimal mate choice rules in an environment wherethere is both local variation in the quality of potential mateswithin each local mating pool and spatial (or temporal) variationin the average quality of the pools themselves. In such a situation,a robust rule that works well across a variety of environmentswill confer a significant reproductive advantage. We formulatea full Bayesian model for updating information in such a varyingenvironment and derive the form of the rule that maximizes expectedreward in a spatially varying environment. We compare the theoreticalperformance of our optimal learning rule against both fixedthreshold rules and simpler near-optimal learning rules andshow that learning is most advantageous when both the localand environmental variances are large. We consider how optimalsimple learning rules might evolve and compare their evolutionwith that of fixed threshold rules using genetic algorithmsas minimal models of the relevant genetics. Our analysis pointsup the variety of ways in which a near-optimal rule can be expressed.Finally, we describe how our results extend to the case of temporallyvarying environments.  相似文献   
106.
胸部双源性疾病外科治疗的临床决策   总被引:1,自引:1,他引:0       下载免费PDF全文
胸部双源性疾病随人口的老龄化而逐年增加,而老年人的心肺及各种脏器功能随年龄的增长逐渐衰退,并发症多,手术风险大,对此类病人的外科治疗如何做出正确的临床医疗决策呢?我们以循证医学理论为基础,努力做到临床医疗决策的科学性,治疗方案的合理性,大胆尝试,逐步从分期手术向一期手术过渡,既达到了解决病人疾苦,救治病人的目的,又解决了医疗需求的增加和卫生资源短缺的矛盾,取得了满意的效果,降低了医疗成本,节约了医疗资源,产生了明显的社会和经济效益。  相似文献   
107.
In a recent paper List, Elsholtz and Seeley (List et al., 2009) have devised an agent-based model of the nest-choice dynamics in swarms of honeybees, and have concluded that both interdependence and independence are needed for the bees to reach a consensus on the best nest site. We here present a simplified version of the model which can be treated analytically with the tools of statistical physics and which largely has the same features as the original dynamics. Based on our analytical approaches it is possible to characterize the co-ordination outcome exactly on the deterministic level, and to a good approximation if stochastic effects are taken into account, reducing the need for computer simulations on the agent-based level. In the second part of the paper we present a spatial extension, and show that transient non-trivial patterns emerge, before consensus is reached. Approaches in terms of Langevin equations for continuous field variables are discussed.  相似文献   
108.
The island rule and a research agenda for studying ecogeographical patterns   总被引:7,自引:4,他引:3  
We are currently experiencing a resurgence of interest in ecogeographical rules, which describe general trends in morphology and related traits along geographical gradients. In order to develop a more comprehensive understanding of the generality and underlying causal mechanisms for these patterns, we recommend a new, more integrated research agenda. In particular, we recommend studies that simultaneously consider different clines in morphology, geographical ranges and diversity as intricately related phenomena; all being ecological, evolutionary and biogeographical responses of organisms to selection regimes that vary non-randomly over space and time, and among species with different ecological and evolutionary histories.  相似文献   
109.
甘肃、新疆、内蒙苹果蠹蛾成虫消长规律   总被引:2,自引:0,他引:2  
苹果蠹蛾Cydia pomonella(L.)是我国重要的果树害虫和检疫对象。2005年至2010年,本研究在甘肃、新疆及内蒙古的不同区县选取了16个果园,使用性信息素诱捕器对其中的苹果蠹蛾成虫发生规律进行长期监测。结果表明,苹果蠹蛾在西北地区每年发生2.5个世代;在正常气候条件下,3个成虫发生高峰分别出现在5月上旬、7月中下旬和8月中下旬,但不同地区及同一地区不同果园之间存在较大差异;化学防治、迷向防治等防治措施对苹果蠹蛾成虫捕获量的影响较大,因此生活史研究为主的监测并不适合在上述果园中开展。综合上述研究结果,未对苹果蠹蛾的季节动态进行准确的预测,需要对苹果蠹蛾除成虫外的其他虫态的季节性变化进行详细研究,并建议选择3个以上的果园进行监测,综合各个果园的监测结果并得出结论。  相似文献   
110.
《Chronobiology international》2012,29(12):1752-1760
ABSTRACT

We compared performance of four popular interpretative algorithms (IAs), i.e., Cole–Kripke, Rescored Cole–Kripke, Sadeh, and UCSD, utilized to derive sleep parameters from wrist actigraphy data. We conducted in-home sleep study of 40 healthy adults (17 female/23 male; age 26.7 ± 12.1 years), assessing sleep variables both by Motionlogger® Micro Watch Actigraphy (MMWA) and Zmachine® Insight+ electroencephalography (EEG). Data of MMWA were separately scored per 30 sec epochs by each of the four popular IAs, and data of the Zmachine were also scored per 30 sec epochs by its proprietary IA. In reference to the EEG Zmachine method, all four of the MMWA algorithms showed high (~94 to 98%) sensitivity and moderate (~42 to 54%) specificity in detecting Sleep epochs. All of them significantly underestimated Sleep Onset Latency (SOL: ~9 to 20 min), and all of them, except the Sadeh IA, significantly underestimated Wake After Sleep Onset (WASO: ~22 to 25 min) and overestimated Total Sleep Time (TST: ~32 to 45 min) and Sleep Efficiency (SE: ~7 to 9%). The Sadeh IA showed significantly smaller bias than the other three IAs in deriving WASO, TST, and SE. Overall, application of ‘Rescoring Rules’ improved performance of the Cole–Kripke IA. The Sadeh and Rescored Cole–Kripke IAs exhibited highest agreement with the EEG Zmachine method (Cohen’s Kappa: ~51%), while the UCSD IA exhibited lowest agreement (Cohen’s kappa: ~47%). However, minimum detectable change across all sleep parameters was smallest with use of the UCSD IA and, except for SOL, largest with use of the Sadeh algorithm. Findings of this study indicate the Sadeh IA is most appropriate for deriving sleep parameters of healthy adults, while the UCSD IA is most appropriate for evaluating change in sleep parameters over time or in response to medical intervention.  相似文献   
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