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Potential Strengths (potential + strength)
Selected AbstractsToward a greater appreciation of noncovalent chemical/DNA interactions: Application of biological and computational approaches,ENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 2-3 2005Ronald D. Snyder Abstract Noncovalent DNA interactions, e.g., DNA intercalation and DNA groove-binding, have not been well studied relative to covalent interactions largely due to the inability of predicting and detecting such events in intact cells. We have adapted an in vitro bleomycin amplification method for DNA intercalation for use in cultured V79 Chinese hamster cells and have validated this approach through the use of a three-dimensional DNA computational docking model that quantifies potential strength of DNA intercalative binding based on electrostatics and hydrogen bonding. For many structural classes of molecules, DNA intercalation is necessary but not sufficient for genotoxicity. The present article reviews our progress to date in predicting and confirming noncovalent binding of drugs and other chemicals and in understanding the mechanistic relationship between intercalation and genotoxicity. Environ. Mol. Mutagen., 2005. © 2005 Wiley-Liss, Inc. [source] SEXUAL DIMORPHISM AND ADAPTIVE SPECIATION: TWO SIDES OF THE SAME ECOLOGICAL COINEVOLUTION, Issue 11 2003Daniel I. Bolnick Abstract Models of adaptive speciation are typically concerned with demonstrating that it is possible for ecologically driven disruptive selection to lead to the evolution of assortative mating and hence speciation. However, disruptive selection could also lead to other forms of evolutionary diversification, including ecological sexual dimorphisms. Using a model of frequency-dependent intraspecific competition, we show analytically that adaptive speciation and dimorphism require identical ecological conditions. Numerical simulations of individual-based models show that a single ecological model can produce either evolutionary outcome, depending on the genetic independence of male and female traits and the potential strength of assortative mating. Speciation is inhibited when the genetic basis of male and female ecological traits allows the sexes to diverge substantially. This is because sexual dimorphism, which can evolve quickly, can eliminate the frequency-dependent disruptive selection that would have provided the impetus for speciation. Conversely, populations with strong assortative mating based on ecological traits are less likely to evolve a sexual dimorphism because females cannot simultaneously prefer males more similar to themselves while still allowing the males to diverge. This conflict between speciation and dimorphism can be circumvented in two ways. First, we find a novel form of speciation via negative assortative mating, leading to two dimorphic daughter species. Second, if assortative mating is based on a neutral marker trait, trophic dimorphism and speciation by positive assortative mating can occur simultaneously. We conclude that while adaptive speciation and ecological sexual dimorphism may occur simultaneously, allowing for sexual dimorphism restricts the likelihood of adaptive speciation. Thus, it is important to recognize that disruptive selection due to frequency-dependent interactions can lead to more than one form of adaptive splitting. [source] SEXUAL SELECTION AND INTERACTING PHENOTYPES IN EXPERIMENTAL EVOLUTION: A STUDY OF DROSOPHILA PSEUDOOBSCURA MATING BEHAVIOREVOLUTION, Issue 7 2008Leonardo D. Bacigalupe Sexual selection requires social interactions, particularly between the sexes. When trait expression is influenced by social interactions, such traits are called interacting phenotypes and only recently have the evolutionary consequences of interacting phenotypes been considered. Here we investigated how variation in relative fitness, or the opportunity for sexual selection, affected the evolutionary trajectories of interacting phenotypes. We used experimentally evolved populations of the naturally promiscuous Drosophila pseudoobscura, in which the numbers of potential interactions between the sexes, and therefore relative fitness, were manipulated by altering natural levels of female promiscuity. We considered two different mating interactions between the sexes: mating speed and copulation duration. We investigated the evolutionary trajectories of means and (co)variances (P) and also the influence of genetic drift on the evolutionary response of these interactions. Our sexual selection treatments did not affect the means of either mating speed or copulation duration, but they did affect P. We found that the means of both traits differed among replicates within each selection treatment whereas the Ps did not. Changes as a consequence of genetic drift were excluded. Our results show that although variable potential strengths of sexual interactions influence the evolution of interacting phenotypes, the influence may be nonlinear. [source] Lone mothers, workfare and precarious employment: Time for a Canadian Basic Income?INTERNATIONAL SOCIAL SECURITY REVIEW, Issue 1 2009Patricia M. Evans Abstract The growth of precarious employment poses significant challenges to current social assistance income support policies yet it remains largely neglected in policy-making arenas. Drawing upon qualitative data from a study in Ontario, Canada, this paper examines the particular implications of these challenges for lone mothers, who figure prominently both in non-standard employment and as targets for workfare policies. In the context of changing labour markets, the article considers the potential strengths and limitations of Basic Income approaches to achieving economic security for lone mothers. [source] Meta-analysis of pharmacokinetic data of veterinary drugs using the Food Animal Residue Avoidance Databank: oxytetracycline and procaine penicillin GJOURNAL OF VETERINARY PHARMACOLOGY & THERAPEUTICS, Issue 5 2004A. L. Craigmill Investigators frequently face the quandary of how to interpret the oftentimes disparate pharmacokinetic parameter values reported in the literature. Combining of data from multiple studies (meta-analysis) is a useful tool in pharmacokinetics. Few studies have explored the use of meta-analysis for veterinary species. Even fewer studies have explored the potential strengths and weaknesses of the various methods of performing a meta-analysis. Therefore, in this study we performed a meta-analysis for oxytetracycline (OTC) and procaine penicillin G (PPG) given intramuscularly to cattle. The analysis included 28 individual data sets from 18 published papers for PPG (288 data points), and 41 individual data sets from 25 published papers for OTC (489 data points). Three methods were used to calculate the parameters. The first was a simple statistical analysis of the parameter values reported in each paper. The second method was a standard Two-Stage Method (TSM) using the mean concentration vs. time data extracted from each paper. The third method was the use of nonlinear mixed effect modeling (NMEM) of the concentration vs. time data reported in the various papers, treating the mean data as if each set came from an individual animal. The results of this evaluation indicate that all three methods generate comparable mean parameter estimates for OTC and PPG. The only significant difference noted was for OTC absorption half-lives taken from the published literature, a difference attributable to the use of an alternative method of parameter calculation. The NMEM procedure offers the possibility of including covariates such as dose, age, and weight. In this study the covariates did not influence the derived parameters. A combination approach to meta-analysis of published mean data is recommended, where the TSM is the first step, followed by the NMEM approach. [source] The complementarity of single-species and ecosystem-oriented research in conservation researchOIKOS, Issue 7 2007David B. Lindenmayer There has been much debate about the relative merits of single-species vs ecosystem-oriented research for conservation. This debate has become increasingly important in recent times as resource managers and policy makers in some jurisdictions focus on ecosystem-level problems. We highlight the potential strengths and limitations of both kinds of research, discuss their complementarity and highlight problems that may arise where competition occurs between the two kinds of research. While a combination of approaches is ideal, a scarcity of funding, time, and expertise means it is impossible to study and manage each species, ecological process, or ecological pattern separately. Making decisions about priorities for the kinds of research, priorities for the kinds of conservation management, and associated allocation of scarce funds is a non-trivial task. We argue for an approach whereby limited resources for conservation research are targeted at projects most likely to close important knowledge gaps, while also promoting ongoing synergies between single-species and ecosystem-oriented research. [source] Statistical Methods for Analysis of Radiation Effects with Tumor and Dose Location-Specific Information with Application to the WECARE Study of Asynchronous Contralateral Breast CancerBIOMETRICS, Issue 2 2009Bryan Langholz Summary Methods for the analysis of individually matched case-control studies with location-specific radiation dose and tumor location information are described. These include likelihood methods for analyses that just use cases with precise location of tumor information and methods that also include cases with imprecise tumor location information. The theory establishes that each of these likelihood based methods estimates the same radiation rate ratio parameters, within the context of the appropriate model for location and subject level covariate effects. The underlying assumptions are characterized and the potential strengths and limitations of each method are described. The methods are illustrated and compared using the WECARE study of radiation and asynchronous contralateral breast cancer. [source] Selling the Public on Sustainable Watershed ConservationBULLETIN OF LATIN AMERICAN RESEARCH, Issue 3 2004Jeff Pugh Abstract:, The city of Quito, Ecuador, began working in 2000 to protect the ecologically fragile watershed area for its drinking water. In order to protect the Papallacta watershed, the independent Fund for the Conservation of Watersheds (FONAG) was launched to finance and manage economically sound sustainability projects in the area. FONAG is funded in part through start up grants from several organisations and a 1 per cent fee on all Quito water bills, but it has been unable to build an endowment sizeable enough to begin implementing conservation projects. We measure perceptions of the fund among Quito's university,based residents in two settings and evaluate the quality of the fund's proposed communication campaign based on existing communication theory. Further, we propose an adapted environmental education model based on a synthesis of existing theory and the empirical findings from our examination of the FONAG example. The Papallacta case study illuminates the potential strengths and weaknesses of the cultural ecology and political will of this type of collaborative sustainability project for addressing water problems in a developing country in a mountainous setting, centred around the themes of water conservation and sustainable development. [source] | |||||||||||||