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Central Topic (central + topic)
Selected AbstractsFacilitation can increase the phylogenetic diversity of plant communitiesECOLOGY LETTERS, Issue 11 2007Alfonso Valiente-Banuet Abstract With the advent of molecular phylogenies the assessment of community assembly processes has become a central topic in community ecology. These processes have focused almost exclusively on habitat filtering and competitive exclusion. Recent evidence, however, indicates that facilitation has been important in preserving biodiversity over evolutionary time, with recent lineages conserving the regeneration niches of older, distant lineages. Here we test whether, if facilitation among distant-related species has preserved the regeneration niche of plant lineages, this has increased the phylogenetic diversity of communities. By analyzing a large worldwide database of species, we showed that the regeneration niches were strongly conserved across evolutionary history. Likewise, a phylogenetic supertree of all species of three communities driven by facilitation showed that nurse species facilitated distantly related species and increased phylogenetic diversity. [source] Ruthenium-based metathesis initiators: Development and use in ring-opening metathesis polymerizationJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 17 2002Ulrich Frenzel Abstract For many years, olefin metathesis has been a central topic of industrial and academic research because of its great synthetic utility. The employed initiators cover a wide range of compounds, from simple transition-metal salts to highly sophisticated and well-defined alkylidene complexes. Currently, ruthenium-based catalysts are at the center of attention because of their remarkable tolerance toward oxygen, moisture, and numerous functionalities. This article focuses on recent developments in the field of ring-opening metathesis polymerization using ruthenium-based catalysts. ruthenium-based initiators and their applications to the preparation of advanced polymeric materials are briefly reviewed. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2895,2916, 2002 [source] Britain and the Working Time RegulationsPOLITICS, Issue 1 2001Alasdair Blair It is now over a year since the Working Time Regulations entered force in Britain on 1 October 1998, during a period when the government also introduced the minimum wage. But whereas that piece of legislation appears to have faded away into the background of British industrial relations, the Working Time Regulations continue to remain a central topic. Based on a survey of British companies and organisations, this article reviews the implementation of the legislation and examines the scope of coverage. It finds that the failure of the Labour government to consult the social partners , employer and employee representatives , resulted in business being unprepared for the Regulations. The article also notes that the manner in which this legislation was introduced has meant that many of the employees who were working excessive hours continue to do so. [source] The phase transition in inhomogeneous random graphsRANDOM STRUCTURES AND ALGORITHMS, Issue 1 2007Béla Bollobás Abstract The "classical" random graph models, in particular G(n,p), are "homogeneous," in the sense that the degrees (for example) tend to be concentrated around a typical value. Many graphs arising in the real world do not have this property, having, for example, power-law degree distributions. Thus there has been a lot of recent interest in defining and studying "inhomogeneous" random graph models. One of the most studied properties of these new models is their "robustness", or, equivalently, the "phase transition" as an edge density parameter is varied. For G(n,p), p = c/n, the phase transition at c = 1 has been a central topic in the study of random graphs for well over 40 years. Many of the new inhomogeneous models are rather complicated; although there are exceptions, in most cases precise questions such as determining exactly the critical point of the phase transition are approachable only when there is independence between the edges. Fortunately, some models studied have this property already, and others can be approximated by models with independence. Here we introduce a very general model of an inhomogeneous random graph with (conditional) independence between the edges, which scales so that the number of edges is linear in the number of vertices. This scaling corresponds to the p = c/n scaling for G(n,p) used to study the phase transition; also, it seems to be a property of many large real-world graphs. Our model includes as special cases many models previously studied. We show that, under one very weak assumption (that the expected number of edges is "what it should be"), many properties of the model can be determined, in particular the critical point of the phase transition, and the size of the giant component above the transition. We do this by relating our random graphs to branching processes, which are much easier to analyze. We also consider other properties of the model, showing, for example, that when there is a giant component, it is "stable": for a typical random graph, no matter how we add or delete o(n) edges, the size of the giant component does not change by more than o(n). © 2007 Wiley Periodicals, Inc. Random Struct. Alg., 31, 3,122, 2007 [source] Children, Labour Supply and Child Care: Challenges for Empirical AnalysisTHE AUSTRALIAN ECONOMIC REVIEW, Issue 3 2009Guyonne Kalb The aim of this article is to give an overview of the important issues relating to the labour supply of the primary carer in a household. Child care plays a central role in allowing the primary carer time away from the young children in a household. Therefore, child-care use is a central topic of this article, as well. There are a number of different aspects to child care, such as the price, quality, availability and type of service. This article discusses the analytical problems and challenges, taking Australian data, policy and experience as a focus, but drawing on a wide range of international empirical studies. It reports the results from previous research on child-care use and labour supply and it outlines the areas requiring more study. The focus of the article is on economic research. [source] On the edge: The psychoanalyst's transference,THE INTERNATIONAL JOURNAL OF PSYCHOANALYSIS, Issue 5 2007Aira Laine Countertransference is a central topic in analytic work and in the literature. The concept of countertransference includes a basic question which has been understood in different ways. The author attempts to differentiate between the psychoanalyst's transference and his countertransference in the analytic process. It is hard to draw a line between them; analysts are always on the edge. The analyst's transference will be explored and described using three approaches: narcissism, regression profile and the analyst's phase of life. Regression profile is a new concept developed by the author, which may help us to understand the core of the analyst's transference in the analytic situation. She illustrates the topic by clinical vignettes. [source] Capacity to consent to research in schizophrenia: the expanding evidence base,BEHAVIORAL SCIENCES & THE LAW, Issue 4 2006Laura B. Dunn M.D. Capacity to consent to research, fundamental to informed consent and thus vital to the ethical conduct of research, may be impaired among a variety of research populations. Until recently, relatively little empirical evidence has been available to inform discussion and policy-making regarding whose capacity should be assessed, what should be measured, and how it should be measured. Capacity to consent to research has emerged as a central topic in the field of "empirical ethics," an important area of biomedical research devoted to bringing evidence-based methods to the study of ethically salient issues in biomedical and biopsychosocial research. In this paper, empirical studies of capacity to consent to research are reviewed, with a particular focus on studies involving people with schizophrenia. These studies provide intriguing data regarding the nature, correlates, and modifiability of decisional abilities among potentially vulnerable research populations, including individuals with serious neuropsychiatric illnesses. Areas in need of further empirical ethics research are highlighted. Copyright © 2006 John Wiley & Sons, Ltd. [source] | ||||||||||