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1.
Leadbeater's possum is a small, cryptic nongliding petaurid, which is threatened by habitat loss due to the collapse of large hollow‐bearing trees and ongoing timber production in Victoria's central highlands. The recent decline of this species and the difficulties faced by researchers collecting field data has prompted the development of a suite of polymorphic microsatellite markers for application to the continuing conservation of the Leadbeater's possum.  相似文献   

2.
Scientific collaboration has been studied by researchers for decades. Several approaches have been adopted to address the question of how collaboration has evolved in terms of publication output, numbers of coauthors, and multidisciplinary trends. One particular type of collaboration that has received very little attention concerns advisor and advisee relationships. In this paper, we examine this relationship for the researchers who are involved in the area of Exact and Earth Sciences in Brazil and its eight subareas. These pairs are registered in the Lattes Platform that manages the individual curricula vitae of Brazilian researchers. The individual features of these academic researchers and their coauthoring relationships were investigated. We have found evidence that there exists positive correlation between time of advisor–advisee relationship with the advisee’s productivity. Additionally, there has been a gradual decline in advisor–advisee coauthoring over a number of years as measured by the Kulczynski index, which could be interpreted as decline of the dependence.  相似文献   

3.
There is a range of forest management systems between pure extraction and plantation systems. Such “intermediate systems” range from wild forests modified for increased production of selected products to anthropogenic forests with a high-density of valuable species growing within a relatively diverse and complex structure. These systems, classed here as “Forest Garden Systems” (FGS), have important socioeconomic and ecological benefits, and yet they have been largely overlooked by researchers, development practitioners, and policy makers. Based on case examples and the authors’ experience, this paper analyzes the socioeconomic and institutional factors that explain the development, persistence, and decline of FGS. These systems combine productivity and biodiversity values and are important components in the diverse economic systems of their managers. As such, the model warrants increased attention to protect existing values, to support the adaptation of existing systems to changing circumstances, and to inform the development of new models of integrated forest management  相似文献   

4.
Kenya was one of the first sub-Saharan countries to enter the fertility transition, and analysts have suggested various explanations for this. This paper examines the growth in contraceptive availability in Kenya by looking at the Kenya family planning programme and its association with the fertility transition. This is of critical programmatic importance because the fertility transition is not yet underway in many sub-Saharan countries. Policymakers will find the information from this study helpful in evaluating the efficacy of current programmes and replicating the Kenyan programme in areas where fertility decline has not yet occurred. For researchers, the study attempts to highlight some of the major factors driving Kenya's fertility decline, apart from the conventional arguments about social and economic development.  相似文献   

5.
6.
Behavior and conservation: a bridge too far?   总被引:2,自引:0,他引:2  
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7.
White KJ 《Social biology》2002,49(1-2):58-73
Historically, population researchers considered the Hutterites the champions of high fertility, since they most closely approximated the human fertility potential. Yet contemporary researchers have found evidence of a decline in fertility and a shift from natural to controlled fertility behavior among the Hutterite population. Various reasons for these recent changes have been suggested, including the use of birth control. Using interview data from a Dariusleut colony, this is the first paper to document the presence and prevalence of birth control among the North American Hutterites. All interviewed women recognized the use of birth control and reported that female sterilization was the most commonly used method. I address how the various forms of birth control and the reasons for its use relate to the Hutterite ideology.  相似文献   

8.
衰老表现为随着时间推移而带来的功能上的衰退和死亡率的上升.利用模式生物,研究人员已经证明,衰老受高度保守的信号通路所调控,而且遗传与环境因素的改变可以显著延长寿命并延缓功能上的衰退.作为一种模式生物,秀丽线虫由于其遗传操作的简单性以及基因组的高度保守性,已被广泛应用于现代生物学研究中.许多关于衰老的分子机理最初是在秀丽线虫中被阐明的.本文总结了秀丽线虫中高度保守的胰岛素类生长因子(IGF-1)和雷帕霉素受体(TOR)这两条信号通路调控衰老的研究进展,并对未来的研究方向展开了评述.  相似文献   

9.
细胞的冷冻保存是细胞生物学实验中重要的实验技术.长期以来,人们使用冷冻保存液重悬细胞后进行冷冻储存,但是近年来,众多研究者发现传统冷冻方案往往会导致细胞活率大幅下降和细胞功能方面受损,从而很难满足生物医学、组织再生工程、细胞移植技术等高新技术的要求.所以研究者提出利用三维海藻酸微囊包埋细胞后再进行冷冻保存,从而在保证较高细胞活率的同时维持细胞的原有功能,有效的提高细胞的冷冻保存效率.本文概述了海藻酸微囊在细胞冷冻保存过程中的研究现状,同时对其应用进行了展望,以期为后续研究工作提供参考.  相似文献   

10.
The decline of many coral reef ecosystems in recent decades surprised experienced managers and researchers. It shattered old paradigms that these diverse ecosystems are spatially uniform and temporally stable on the scale of millennia. We now see reefs as heterogeneous, fragile, globally stressed ecosystems structured by strong positive or negative feedback processes. We review the causes and consequences of reef decline and ask whether management practices are addressing the problem at appropriate scales. We conclude that both science and management are currently failing to address the comanagement of extractive activities and ecological processes that drive ecosystems (e.g. productivity and herbivory). Most reef conservation efforts are directed toward reserve implementation, but new approaches are needed to sustain ecosystem function in exploited areas.  相似文献   

11.
UV-C induced chemiluminescence of human skin was investigated in vivo by means of an image-producing system using photon-counting camera and computer PERICOLOR-1000. Luminescence after UV-C application is shown to decline nonexponentially, the parameters of the decline depending on irradiation dose, skin specimen and previous irradiations. If the same skin specimen is irradiated second time 3-36 hours after the first irradiation, the luminescence decline time increases from one-two minutes to more than half an hour. During the time when the decline is slow the images produced by irradiation through the diaphragm do not sustain distinct contours due to the luminescence of nonirradiated skin. The luminescence is shown to be under the organisms' control and to diminish significantly after the application of acetylsalicylic acid.  相似文献   

12.
The potential effect that food prices may have on the health of the U.S. population needs to be further explored, particularly in light of the rising food prices currently being observed. Declining food prices over time have been singled out as a main contributor, for example, to the rising trend in obesity. In this paper we use data from the Bureau of Labor Statistics, the American Chamber of Commerce Researchers Association, the Consumer Expenditure Survey, and the United States Department of Agriculture to analyze trends in various types of food prices, to create a food price index, and to estimate the price of a calorie. Results may be used by future researchers in estimating the health implications of these trends. We find that while the general trend in food prices has been declining, that of restaurant meal prices and prices of fruits and vegetables has risen over time. It is doubtful that the decline in food prices has been sufficiently large to account for the large increase in caloric intake that is said to have contributed to the obesity epidemic in the U.S.  相似文献   

13.
As the pace of life science discovery increases, so do the demands on researchers. To remain competitive in the life science industry, researchers must use every tool at their disposal to keep up with new products, protocols, news, and literature in their field. While there are now myriad Web sites that assist researchers with this problem, many suffer from confusing user interfaces, poorly designed search engines, and a narrow information focus. Here, we present LabVelocity, a user-friendly Web site that provides a free multidisciplinary information-gathering service for the life science research community. Using LabVelocity, a researcher can quickly find the products, protocols, technical references, news, MEDLINE abstracts, and interactive software tools necessary for an experiment. This aggregation of information can streamline experimental planning and is especially useful when researchers want to set up a new laboratory or to venture outside their field of expertise.  相似文献   

14.

Background

Poorly preserved biological tissues have become an important source of DNA for a wide range of zoological studies. Measuring the quality of DNA obtained from these samples is often desired; however, there are no widely used techniques available for quantifying damage in highly degraded DNA samples. We present a general method that can be used to determine the frequency of polymerase blocking DNA damage in specific gene-regions in such samples. The approach uses quantitative PCR to measure the amount of DNA present at several fragment sizes within a sample. According to a model of random degradation the amount of available template will decline exponentially with increasing fragment size in damaged samples, and the frequency of DNA damage (λ) can be estimated by determining the rate of decline.

Results

The method is illustrated through the analysis of DNA extracted from sea lion faecal samples. Faeces contain a complex mixture of DNA from several sources and different components are expected to be differentially degraded. We estimated the frequency of DNA damage in both predator and prey DNA within individual faecal samples. The distribution of fragment lengths for each target fit well with the assumption of a random degradation process and, in keeping with our expectations, the estimated frequency of damage was always less in predator DNA than in prey DNA within the same sample (mean λpredator = 0.0106 per nucleotide; mean λprey = 0.0176 per nucleotide). This study is the first to explicitly define the amount of template damage in any DNA extracted from faeces and the first to quantify the amount of predator and prey DNA present within individual faecal samples.

Conclusion

We present an approach for characterizing mixed, highly degraded PCR templates such as those often encountered in ecological studies using non-invasive samples as a source of DNA, wildlife forensics investigations and ancient DNA research. This method will allow researchers to measure template quality in order to evaluate alternate sources of DNA, different methods of sample preservation and different DNA extraction protocols. The technique could also be applied to study the process of DNA decay.  相似文献   

15.
BACKGROUND TO THE DEBATE: Uganda is one of the few African countries where rates of HIV infection have fallen, from about 15 percent in the early 1990s to about five percent in 2001. At the end of 2005, UNAIDS estimated that 6.7 percent of adults were infected with the virus. The reasons behind Uganda's success have been intensely studied in the hope that other countries can emulate the strategies that worked. Some researchers credit the success to the Ugandan government's promotion of "ABC behaviors"--particularly abstinence and fidelity. Uganda receives funds from the United States President's Emergency Plan for AIDS Relief, which promotes the ABC approach with a focus on abstinence-driven public health campaigns. Other researchers question whether the ABC approach was really responsible for the decline in HIV infection. Critics of the ABC approach also argue that by emphasizing abstinence over condom use, the approach leaves women at risk of infection, because in many parts of the world women are not empowered to insist on abstinence or fidelity.  相似文献   

16.
Material transfer agreements exist to facilitate the exchange of materials and associated data between researchers as well as to protect the interests of the researchers and their institutions. But this dual mandate can be a source of frustration for researchers, creating administrative burdens and slowing down collaborations. We argue here that in most cases in pre-competitive research, a simple agreement would suffice; the more complex agreements and mechanisms for their negotiation should be reserved for cases where the risks posed to the institution and the potential commercial value of the research reagents is high.  相似文献   

17.
Yellow‐cedar (Callitropsis nootkatensis (D. Don) Oerst.) is a valuable tree species that is experiencing a widespread decline and mortality in southeast Alaska. This study evaluated the relative importance of several potential risk factors associated with yellow‐cedar decline: soil saturation, soil aluminum (Al) toxicity or calcium (Ca) deficiency, and air and soil temperature. Data were collected from permanent vegetation plots established in two low‐elevation coastal forests exhibiting broad ranges of cedar mortality. Measurements of each risk factor were contrasted among classified forest zones to indicate if there were strong links with decline. Hydrology alone is weakly associated with yellow‐cedar decline, but could have a predisposing role in the decline by creating exposed conditions because of reduced forest productivity. Yellow‐cedar decline is not strongly associated with soil pH and extractable Al and Ca, but there appears to be Ca enrichment of surface soils by feedback from dead yellow‐cedar foliage. Air and soil temperature factors are strongly associated with decline. Based on these results, an hypothesis is presented to explain the mechanism of tree injury where exposure‐driven tree mortality is initiated in gaps created by soil saturation and then expands in gaps created by the tree‐mortality itself. The exposure allows soils to warm in early spring causing premature dehardening in yellow‐cedar trees and subsequent freezing injury during cold events. Yellow‐cedars growing in the protection of shade or snow are not preconditioned by this warming, and thus not as susceptible to cold injury. Yellow‐cedar decline appears to be associated with regional climate changes, but whether the cause of these changes is related to natural or human‐induced climate shifts remains uncertain. Management implications, the possible role of climate, and recommended research are discussed.  相似文献   

18.
Ovarian cycling continues to similar ages in women and chimpanzees yet our nearest living cousins become decrepit during their fertile years and rarely outlive them. Given the importance of estrogen in maintaining physiological systems aside from fertility, similar ovarian aging in humans and chimpanzees combined with somatic aging differences indicates an important role for nonovarian estrogen. Consistent with this framework, researchers have nominated the adrenal androgen dehydroepiandrosterone (DHEA) and its sulfate (DHEAS), which can be peripherally converted to estrogen, as a biomarker of aging in humans and other primates. Faster decline in production of this steroid with age in chimpanzees could help explain somatic aging differences. Here, we report circulating levels of DHEAS in captive female chimpanzees and compare them with published levels in women. Instead of faster, the decline is slower in chimpanzees, but from a much lower peak. Levels reported for other great apes are lower still. These results point away from slowed decline but toward increased DHEAS production as one of the mechanisms underlying the evolution of human longevity. Am J Phys Anthropol 151:643–648, 2013. © 2013 Wiley Periodicals, Inc.  相似文献   

19.
Research, Informed Consent, and the Limits of Disclosure   总被引:1,自引:0,他引:1  
T.M. Williamson 《Bioethics》2001,15(4):341-363
According to this paper, respect for informed consent implies that subjects should often be told a good deal more than ethical guidelines explicitly or implicitly require. Unless subjects are informed of the researchers' personal characteristics, views, and sponsors whenever they would be likely to consider them significant, their autonomy is being overridden. However, overriding subjects' autonomy is sometimes required by the interests of researchers in not being discriminated against or suffering intrusions into their privacy. This paper resolves the conflict between informed consent and the interests of researchers by recommending that (i) subjects generally should be told of the personal characteristics of researchers when relevant as part of the researchers' job and (ii) that subjects should be told of researchers' views when conceptually connected to the research and (iii) that subjects should almost always be told about sponsorship. While the paper explicitly limits the role of informed consent, these recommendations go significantly beyond most guidelines in their requirements about what information should be disclosed.  相似文献   

20.
Participatory research is a radical praxis through which marginalized people acquire research capabilities that they use to transform their own lives. In this article, I examine how parent writers incorporated facets of community writing into their research practice as they developed their practices and identities as researchers. I also consider how anthropology, as both research practice and sensibility, contributed to the ways I engaged as an outside collaborator with these parent researchers.  [community writing, participatory research, praxis, anthropological sensibility]  相似文献   

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