253 research outputs found

    The Evolution of Altruism in Spatially Structured Populations

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    The evolution of altruism in humans is still an unresolved puzzle. Helping other individuals is often kinship-based or reciprocal. Several examples show, however, that altruism goes beyond kinship and reciprocity and people are willing to support unrelated others even when this is at a cost and they receive nothing in exchange. Here we examine the evolution of this "pure" altruism with a focus on altruistic teaching. Teaching is modeled as a knowledge transfer which enhances the survival chances of the recipient, but reduces the reproductive efficiency of the provider. In an agent-based simulation we compare evolutionary success of genotypes that have willingness to teach with those who do not in two different scenarios: random matching of individuals and spatially structured populations. We show that if teaching ability is combined with an ability to learn and individuals encounter each other on a spatial proximity basis, altruistic teaching will attain evolutionary success in the population. Settlement of the population and accumulation of knowledge are emerging side-products of the evolution of altruism. In addition, in large populations our simple model also produces a counterintuitive result that increasing the value of knowledge keeps fewer altruists alive.Altruism, Teaching, Knowledge Transfer, Spatially Structured Social Dilemmas

    Conformational Dependence of a Protein Kinase Phosphate Transfer Reaction

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    Atomic motions and energetics for a phosphate transfer reaction catalyzed by the cAMP-dependent protein kinase (PKA) are calculated by plane-wave density functional theory, starting from structures of proteins crystallized in both the reactant conformation (RC) and the transition-state conformation (TC). In the TC, we calculate that the reactants and products are nearly isoenergetic with a 0.2 eV barrier; while phosphate transfer is unfavorable by over 1.2 eV in the RC, with an even higher barrier. With the protein in the TC, the motions involved in reaction are small, with only Pγ_\gamma and the catalytic proton moving more than 0.5 \AA. Examination of the structures reveals that in the RC the active site cleft is not completely closed and there is insufficient space for the phosphorylated serine residue in the product state. Together, these observations imply that the phosphate transfer reaction occurs rapidly and reversibly in a particular conformation of the protein, and that the reaction can be gated by changes of a few tenths of an \AA in the catalytic site.Comment: revtex4, 7 pages, 4 figures, to be submitted to Scienc

    Inferring tumor progression from genomic heterogeneity

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    Cancer progression in humans is difficult to infer because we do not routinely sample patients at multiple stages of their disease. However, heterogeneous breast tumors provide a unique opportunity to study human tumor progression because they still contain evidence of early and intermediate subpopulations in the form of the phylogenetic relationships. We have developed a method we call Sector-Ploidy-Profiling (SPP) to study the clonal composition of breast tumors. SPP involves macro-dissecting tumors, flow-sorting genomic subpopulations by DNA content, and profiling genomes using comparative genomic hybridization (CGH). Breast carcinomas display two classes of genomic structural variation: (1) monogenomic and (2) polygenomic. Monogenomic tumors appear to contain a single major clonal subpopulation with a highly stable chromosome structure. Polygenomic tumors contain multiple clonal tumor subpopulations, which may occupy the same sectors, or separate anatomic locations. In polygenomic tumors, we show that heterogeneity can be ascribed to a few clonal subpopulations, rather than a series of gradual intermediates. By comparing multiple subpopulations from different anatomic locations, we have inferred pathways of cancer progression and the organization of tumor growth. © 2010 by Cold Spring Harbor Laboratory Press

    Poverty and Well-being in Post-Apartheid South Africa: An Overview of Data, Outcomes and Policy

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    WP 2006-03 January 2006This is an overview of poverty and well-being in the first decade of post-apartheid South Africa. It is an introduction to a volume that brings together some of the most prominent academic research done on this topic for the 10-year review process in South Africa. This overview highlights three key aspects of the picture that the detailed research paints. First, data quality and comparability has been a constant issue in arriving at a consensus among analysts on the outcomes for households and individuals in postapartheid South Africa. Second, while the outcomes on unemployment, poverty and inequality are indeed bad, the outcomes on social indicators and access to public services are much more encouraging. Third, the prospects for rapid and sustained economic growth, without which poverty and well-being cannot be addressed in the long run, are themselves negatively affected by increasing inequality, poverty and unemployment

    Integrating social science into conservation planning

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    A growing body of literature has highlighted the value of social science for conservation, yet the diverse approaches of the social sciences are still inconsistently incorporated in conservation initiatives. Building greater capacity for social science integration in conservation requires frameworks and case studies that provide concrete guidance and specific examples. To address this need, we have developed a framework aimed at expanding the role for social science in formal conservation planning processes. Our framework illustrates multiple ways in which social science research can contribute to four stages of such processes: 1) defining the problem and project team; 2) defining goals; 3) identifying impact pathways and designing interventions; and 4) developing and evaluating indicators of success (or failure). We then present a timely case study of wolf reintroduction in Colorado, U.S.A., to demonstrate the opportunities, challenges, and complexities of applying our framework in practice

    Scenario-Based Design Theorizing:The Case of a Digital Idea Screening Cockpit

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    As ever more companies encourage employees to innovate, a surplus of ideas has become reality in many organizations – often exceeding the available resources to execute them. Building on insights from a literature review and a 3-year collaboration with a banking software provider, the paper suggests a Digital Idea Screening Cockpit (DISC) to address this challenge. Following a design science research approach, it suggests a prescriptive design theory that provides practitioner-oriented guidance for implementing a DISC. The study shows that, in order to facilitate the assessment, selection, and tracking of ideas for different stakeholders, such a system needs to play a dual role: It needs to structure decision criteria and at the same be flexible to allow for creative expression. Moreover, the paper makes a case for scenario-based design theorizing by developing design knowledge via scenarios

    Complications and pitfalls of lumbar interlaminar and transforaminal epidural injections

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    Lumbar interlaminar and transforaminal epidural injections are used in the treatment of lumbar radicular pain and other lumbar spinal pain syndromes. Complications from these procedures arise from needle placement and the administration of medication. Potential risks include infection, hematoma, intravascular injection of medication, direct nerve trauma, subdural injection of medication, air embolism, disc entry, urinary retention, radiation exposure, and hypersensitivity reactions. The objective of this article is to review the complications of lumbar interlaminar and transforaminal epidural injections and discuss the potential pitfalls related to these procedures. We performed a comprehensive literature review through a Medline search for relevant case reports, clinical trials, and review articles. Complications from lumbar epidural injections are extremely rare. Most if not all complications can be avoided by careful technique with accurate needle placement, sterile precautions, and a thorough understanding of the relevant anatomy and contrast patterns on fluoroscopic imaging

    Advancing social equity in and through marine conservation

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    Substantial efforts and investments are being made to increase the scale and improve the effectiveness of marine conservation globally. Though it is mandated by international law and central to conservation policy, less attention has been given to how to operationalize social equity in and through the pursuit of marine conservation. In this article, we aim to bring greater attention to this topic through reviewing how social equity can be better integrated in marine conservation policy and practice. Advancing social equity in marine conservation requires directing attention to: recognition through acknowledgment and respect for diverse peoples and perspectives; fair distribution of impacts through maximizing benefits and minimizing burdens; procedures through fostering participation in decision-making and good governance; management through championing and supporting local involvement and leadership; the environment through ensuring the efficacy of conservation actions and adequacy of management to ensure benefits to nature and people; and the structural barriers to and institutional roots of inequity in conservation. We then discuss the role of various conservation organizations in advancing social equity in marine conservation and identify the capacities these organizations need to build. We urge the marine conservation community, including governments, non-governmental organizations and donors, to commit to the pursuit of socially equitable conservation

    Chronic and structural poverty in South Africa: Challenges for action and research

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    Ten years after liberation, the persistence of poverty is one of the most important and urgent problems facing South Africa. This paper reflects on some of the findings based on research undertaken as part of the participation of the Programme for Land and Agrarian Studies (PLAAS) at the University of the Western Cape in the work of the Chronic Poverty Research Centre (CPRC), situates it within the broader literature on poverty in South Africa, and considers some emergent challenges. Although PLAAS’s survey, being only the first wave of a panel study, does not yet cast light on short term poverty dynamics, it illuminates key aspects of the structural conditions that underpin long-term poverty: the close interactions between asset poverty, employment-vulnerability and subjection to unequal social power relations. Coming to grips with these dynamics requires going beyond the limitations of conventional ‘sustainable livelihoods’ analyses; and functionalist analyses of South African labour markets. The paper argues for a re-engagement with the traditions of critical sociology, anthropology and the theoretical conventions that allow a closer exploration of the political economy of chronic poverty at micro and macro level
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