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1.
A recent randomized controlled trial shows a significant reduction in women-to-men transmission of HIV due to male circumcision.
Such development calls for a rigorous mathematical study to ascertain the full impact of male circumcision in reducing HIV
burden, especially in resource-poor nations where access to anti-retroviral drugs is limited. First of all, this paper presents
a compartmental model for the transmission dynamics of HIV in a community where male circumcision is practiced. In addition
to having a disease-free equilibrium, which is locally-asymptotically stable whenever a certain epidemiological threshold
is less than unity, the model exhibits the phenomenon of backward bifurcation, where the disease-free equilibrium coexists
with a stable endemic equilibrium when the threshold is less than unity. The implication of this result is that HIV may persist
in the population even when the reproduction threshold is less than unity. Using partial data from South Africa, the study
shows that male circumcision at 60% efficacy level can prevent up to 220,000 cases and 8,200 deaths in the country within
a year. Further, it is shown that male circumcision can significantly reduce, but not eliminate, HIV burden in a community.
However, disease elimination is feasible if male circumcision is combined with other interventions such as ARVs and condom
use. It is shown that the combined use of male circumcision and ARVs is more effective in reducing disease burden than the
combined use of male circumcision and condoms for a moderate condom compliance rate. 相似文献
2.
The recent movement to revitalize the Hawaiian language and culture through the Kula Kaiapuni, or the Hawaiian Language Immersion Program, has grown over the past 11 years to include almost 1,600 students during the 1998–99 school year. During this period, the field of Hawaiian language has become highly politicized by nonindigenous Hawaiian language educators attempting to colonize the field and control resources purported to redress wrongs to the native people including loss of language and culture. 相似文献
3.
Feminist researchers have contrasted the caring provided by women in hospitals with a more fragmented curing approach, which they identify with the predominantly male professions of medicine and surgery. The author spoke with hospital cleaners about their jobs and their health. Several themes emerged: the invisibility of the cleaning function, lack of respect for cleaners, representations of cleaning as undemanding, and assumptions that women s work in cleaning is particularly easy. Cleaners use various strategies to combat these stereotypes but receive little help from administrators or fellow employees. There is a hierarchy in the status of Quebec hospital workers with curing (doctors) at the top, followed by caring and healing (nurses, therapists, and attendants), and hygiene (cleaners, sterilizers, and launderers) at the bottom. Authority hierarchies in health care are not related to gender in a simple way, although there is discrimination against women cleaners. The fact that cleaning, especially cleaning performed by women, is invisible to managers, other hospital personnel, and patients has important consequences for cleaners' and for patients' health. [cleaning, health, hierarchy, hospital workers, gender] 相似文献
4.
Self-recognition in front of a mirror is used as an indicator of self-awareness. Along with humans, some chimpanzees and orangutans have been shown to be self-aware using the mark test. Monkeys are conspicuously absent from this list because they fail the mark test and show persistent signs of social responses to mirrors despite prolonged exposure, which has been interpreted as evidence of a cognitive divide between hominoids and other species. In stark contrast with those reports, the rhesus monkeys in this study, who had been prepared for electrophysiological recordings with a head implant, showed consistent self-directed behaviors in front of the mirror and showed social responses that subsided quickly during the first experimental session. The self-directed behaviors, which were performed in front of the mirror and did not take place in its absence, included extensive observation of the implant and genital areas that cannot be observed directly without a mirror. We hypothesize that the head implant, a most salient mark, prompted the monkeys to overcome gaze aversion inhibition or lack of interest in order to look and examine themselves in front of the mirror. The results of this study demonstrate that rhesus monkeys do recognize themselves in the mirror and, therefore, have some form of self-awareness. Accordingly, instead of a cognitive divide, they support the notion of an evolutionary continuity of mental functions. 相似文献
5.
Concerns about the negative effects of marine scientific research are in clear juxtaposition to the beneficial role that scientific knowledge plays in enhancing the understanding of the oceans and protecting the marine environment. This presents a regulatory paradox that is examined in this article in light of the legal framework in the 1982 United Nations Convention on the Law of the Sea. The article traces how these general principles in the Convention are elaborated in soft law instruments for the promotion of environmentally sustainable research practices. It also looks at an example of state practice in this area by examining regulatory measures instituted in the Canadian Endeavour Hydrothermal Vent Marine Protected Area. 相似文献
7.
非人灵长类动物在亲缘关系上和人最接近,与人类的遗传物质有75%~98.5%的同源性,在组织结构、免疫、生理和代谢等方面与人类高度近似,是极其珍贵的实验动物,其应用价值远超过其他种属的实验动物。本文就非人灵长类和人类之间的进化关系和目前的使用情况,及其在毒理学、传染病、神经科学、生殖生物学、胎儿发育和衰老等医学科学实验中的应用等方面的内容做了简要的介绍。 相似文献
8.
针对灾难医学的研究特点,结合国内外有关灾难医学救治的研究资料,梳理灾难医学的主要研究方向,同时通过总结分析现有灾难医学科研管理的策略、具体做法及其问题,提出适合我国现状的灾难医学科研管理的建议。 相似文献
9.
In this paper we show that response facilitation in choice reaction tasks achieved by priming the (previously perceived) effect is based on stimulus-response associations rather than on response-effect associations. The reduced key-press response time is not accounted for by earlier established couplings between the key-press movement and its subsequent effect, but instead results from couplings between this effect and the contingent key-release movement. This key-release movement is an intrinsic part of the entire performed response action in each trial of a reaction-time task, and always spontaneously follows the key-press movement. Eliminating the key-release movement from the task leads to the disappearance of the response facilitation, which raises the question whether response-effect associations actually play a role in studies that use the effect-priming paradigm. Together the three experiments presented in the paper cast serious doubts on the claim that action-effect couplings are acquired and utilized by the cognitive system in the service of action selection, and that the priming paradigm by itself can provide convincing evidence for this claim. As a corollary, we question whether the related two-step model for the ideomotor principle holds a satisfying explanation for how anticipation of future states guides action planning. The results presented here may have profound implications for priming studies in other disciplines of psychology as well. 相似文献
12.
The β subunit of the bovine brain S100-b protein (ββ) lacks tryptophyl residue but contains one tyrosine. Our experiments show that this protein is characterized by a typical tyrosine fluorescence spectrum, with a maximum at 303 nm. Identical fluroescence properties were found for the rat brain S100-b protein. Comparison with the fluorescence spectrum of the bovine brain S100-a’ protein (α'β), which contains a tryptophan residue in the α’ subunit, enables us to demonstrate that the recent report describing an abnormal fluorescence spectrum for the bovine brain S100-b protein may result from a contamination of the S100-b by the S100-α’ protein. 相似文献
15.
When binary responses are observed over time, the dependence between observations for an individual must be considered. If the focus of a study is to identify the relationship between the binary response and a set of explanatory variables then the dependence between observations may also depend on the explanatory variables. An extension of a model where dependence is assumed to be constant will be considered. A model previously proposed for dependent binary responses will be revisited and a robust estimate of the variance-covariance matrix of coefficient estimates will be suggested to provide estimates of standard errors. The results of simulation studies investigating the properties of coefficient estimates will be discussed. An example based on a study of the AIDS epidemic and intravenous drug use behaviour will be analyzed to illustrate the techniques. 相似文献
16.
This report examines the extent to which dream recall involves the 3 R's (reading, writing, and arithmetic). Two separate studies were done. In the first study, two scorers rated, on a blind basis, a total of 456 written dream reports, available from five previous studies. There was perfect agreement between the two scorers. They agreed that there were no instances of reading, no instances of writing, and one instance of probable calculating in the 456 dreams. The second study was a questionnaire survey. Complete responses were obtained from 240 frequent dreamers (who reported remembering a mean of seven dreams per week). The study examined in two ways the frequency of the 3 R's in their recalled dreams. First, in answer to direct questions as to how frequently they dreamt about each activity, roughly 90% of the respondents reported that they never or hardly ever dreamt about each of four activities: reading, writing, typing, and calculating. In answers to other questions, this group reported spending a mean of six hours per day engaged in these activities. Second, responses as to the relative prominence of six activities (walking, writing, talking with friends, reading, sexual activity, typing) in dreaming versus waking produced two clear groupings of activities. Walking, talking with friends, and sexual activity were each rated almost as prominent in dreaming as in waking whereas the second group consisting of writing, reading, and typing were rated as far more prominent in waking than in dreaming. The two activity groups differed at p < .0001. Thus, the 3 R's appear to occur very infrequently in dreams. These findings are placed in a theoretical frame which suggests that dreaming (compared to waking) deals very little with serial activities characterized by input—rapid-processing—output in which the neural nets function in a feed-forward mode. Rather, dreaming may be characterized by relatively broad or loose connection making in which the nets function more in an autoassociative mode. 相似文献
17.
Information Quality (IQ) is a critical factor for the success of many activities in the information age, including the development of data warehouses and implementation of data mining. The issue of IQ risk is recognized during the process of data mining; however, there is no formal methodological approach to dealing with such issues. Consequently, it is essential to measure the risk of IQ in a data warehouse to ensure success in implementing data mining. This article presents a methodology to determine three IQ risk characteristics: accuracy, comprehensiveness, and non-membership. The methodology provides a set of quantitative models to examine how the quality risks of source information affect the quality for information outputs produced using the relational algebra operations: Restriction, Projection, and Cubic product. It can be used to determine how quality risks associated with diverse data sources affect the derived data. The study also develops a data cube model and associated algebra to support IQ risk operations. 相似文献
18.
In this paper, a statistical model for clinical trials is presented for the special situation that a varying and unstructered number of binary responses is obtained from each subject. The assumptions of the model are the following: 1.) For each subject there is a (constant) individual Bernoulli parameter determining the distribution of the binary responses of this subject. 2.) The Bernoulli parameters associated with the subjects are realizations of independent random variables with distributions Pg in treatment group g(g = 1, 2, …, G). 3.) Given the value of the Bernoulli parameter, the observations are stochastically independent within each subject. Under these assumptions, a test statistic is derived to test the hypothesis H0: E( P1) = E( P2) = … = E( PG). It is proven and demonstrated by simulations, that the test statistic asymptotically (i.e. for a large number of subjects) follows the X2-distribution. 相似文献
19.
Next-generation problem-solving environments (PSEs) promise significant advances over those now available. They will span scientific disciplines and incorporate collaboration capabilities. They will host feature-detection and other agents, allow data mining and pedigree tracking, and provide access from a wide range of devices. Fundamental changes in PSE architecture are required to realize these and other PSE goals. This paper focuses specifically on issues related to data management and recommends an approach based on open, metadata-driven repositories with loosely defined, dynamic schemas. Benefits of this approach are discussed, and the redesign of the Extensible Computational Chemistry Environment's (Ecce) data storage architecture to use such a repository is described, based on the distributed authoring and versioning (DAV) standard. The suitability of DAV for scientific data, the mapping of the Ecce schema to DAV, and promising initial results are presented. 相似文献
20.
Although the synthesis pathways of intracellular triacylglycerol (TAG) species have been well elucidated, assessment of the contribution of an individual pathway to TAG pools in different mammalian organs, particularly under pathophysiological conditions, is difficult, although not impossible. Herein, we developed and validated a novel bioinformatic approach to assess the differential contributions of the known pathways to TAG pools through simulation of TAG ion profiles determined by shotgun lipidomics. This powerful approach was applied to determine such contributions in mouse heart, liver, and skeletal muscle and to examine the changes of these pathways in mouse liver induced after treatment with a high-fat diet. It was clearly demonstrated that assessment of the altered TAG biosynthesis pathways under pathophysiological conditions can be readily achieved through simulation of lipidomics data. Collectively, this new development should greatly facilitate our understanding of the biochemical mechanisms underpinning TAG accumulation at the states of obesity and lipotoxicity. 相似文献
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