326 research outputs found

    Some functional equations related to the characterizations of information measures and their stability

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    The main purpose of this paper is to investigate the stability problem of some functional equations that appear in the characterization problem of information measures.Comment: 36 pages. arXiv admin note: text overlap with arXiv:1307.0657, arXiv:1307.0631, arXiv:1307.0664, arXiv:1307.065

    Social research on neglected diseases of poverty: Continuing and emerging themes

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    Copyright: © 2009 Manderson et al.Neglected tropical diseases (NTDs) exist and persist for social and economic reasons that enable the vectors and pathogens to take advantage of changes in the behavioral and physical environment. Persistent poverty at household, community, and national levels, and inequalities within and between sectors, contribute to the perpetuation and re-emergence of NTDs. Changes in production and habitat affect the physical environment, so that agricultural development, mining and forestry, rapid industrialization, and urbanization all result in changes in human uses of the environment, exposure to vectors, and vulnerability to infection. Concurrently, political instability and lack of resources limit the capacity of governments to manage environments, control disease transmission, and ensure an effective health system. Social, cultural, economic, and political factors interact and influence government capacity and individual willingness to reduce the risks of infection and transmission, and to recognize and treat disease. Understanding the dynamic interaction of diverse factors in varying contexts is a complex task, yet critical for successful health promotion, disease prevention, and disease control. Many of the research techniques and tools needed for this purpose are available in the applied social sciences. In this article we use this term broadly, and so include behavioral, population and economic social sciences, social and cultural epidemiology, and the multiple disciplines of public health, health services, and health policy and planning. These latter fields, informed by foundational social science theory and methods, include health promotion, health communication, and heath education

    Sea-level constraints on the amplitude and source distribution of Meltwater Pulse 1A.

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    During the last deglaciation, sea levels rose as ice sheets retreated. This climate transition was punctuated by periods of more intense melting; the largest and most rapid of these—Meltwater Pulse 1A—occurred about 14,500 years ago, with rates of sea-level rise reaching approximately 4 m per century1, 2, 3. Such rates of rise suggest ice-sheet instability, but the meltwater sources are poorly constrained, thus limiting our understanding of the causes and impacts of the event4, 5, 6, 7. In particular, geophysical modelling studies constrained by tropical sea-level records1, 8, 9 suggest an Antarctic contribution of more than seven metres, whereas most reconstructions10 from Antarctica indicate no substantial change in ice-sheet volume around the time of Meltwater Pulse 1A. Here we use a glacial isostatic adjustment model to reinterpret tropical sea-level reconstructions from Barbados2, the Sunda Shelf3 and Tahiti1. According to our results, global mean sea-level rise during Meltwater Pulse 1A was between 8.6 and 14.6 m (95% probability). As for the melt partitioning, we find an allowable contribution from Antarctica of either 4.1 to 10.0 m or 0 to 6.9 m (95% probability), using two recent estimates11, 12 of the contribution from the North American ice sheets. We conclude that with current geologic constraints, the method applied here is unable to support or refute the possibility of a significant Antarctic contribution to Meltwater Pulse 1A

    Reciprocity as a foundation of financial economics

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    This paper argues that the subsistence of the fundamental theorem of contemporary financial mathematics is the ethical concept ‘reciprocity’. The argument is based on identifying an equivalence between the contemporary, and ostensibly ‘value neutral’, Fundamental Theory of Asset Pricing with theories of mathematical probability that emerged in the seventeenth century in the context of the ethical assessment of commercial contracts in a framework of Aristotelian ethics. This observation, the main claim of the paper, is justified on the basis of results from the Ultimatum Game and is analysed within a framework of Pragmatic philosophy. The analysis leads to the explanatory hypothesis that markets are centres of communicative action with reciprocity as a rule of discourse. The purpose of the paper is to reorientate financial economics to emphasise the objectives of cooperation and social cohesion and to this end, we offer specific policy advice

    B cell depletion in autoimmune diabetes:insights from murine models

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    INTRODUCTION: The incidence of type 1 diabetes (T1D) is rising for reasons that largely elude us. New strategies aimed at halting the disease process are needed. One type of immune cell thought to contribute to T1D is the B lymphocyte. The first Phase II trial of B cell depletion in new onset T1D patients indicated that this slowed the destruction of insulin-producing pancreatic beta cells. The mechanistic basis of the beneficial effects remains unclear. AREAS COVERED: Studies of B cell depletion and deficiency in animal models of T1D. How B cells can influence T cell-dependent autoimmune diabetes in animal models. The heterogeneity of B cell populations and current evidence for the potential contribution of specific B cell subsets to diabetes, with emphasis on marginal zone B cells and B1 B cells. EXPERT OPINION: B cells can influence the T cell response to islet antigens and B cell depletion or genetic deficiency is associated with decreased insulitis in animal models. New evidence suggests that B1 cells may contribute to diabetes pathogenesis. A better understanding of the roles of individual B cell subsets in disease will permit fine-tuning of therapeutic strategies to modify these populations

    Middle Segment Pancreatectomy: A Useful Tool in the Management of Pancreatic Neoplasms

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    Small, benign, or low-grade malignant tumors located in the neck of the pancreas are usually treated with enucleation. However, if enucleation is too risky because of possible damage of the main pancreatic duct, standard pancreatic resections are performed. Such operations can lead to impaired long-term exocrine–endocrine function. Middle segment pancreatectomy consists of a limited resection of the midportion of the pancreas and can be performed in selected patients affected by tumors of the pancreatic neck. Middle segment pancreatectomy is a safe and feasible procedure for treating tumors of the pancreatic neck; in experienced hands it is associated with no mortality but with high morbidity, even if the rate of “clinical” pancreatic fistula is about 20%. Moreover, it allows a surgeon to preserve pancreatic parenchyma and consequently long-term endocrine and exocrine pancreatic function

    Islet Formation during the Neonatal Development in Mice

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    The islet of Langerhans is a unique micro-organ within the exocrine pancreas, which is composed of insulin-secreting beta-cells, glucagon-secreting alpha-cells, somatostatin-secreting delta-cells, pancreatic polypeptide-secreting PP cells and ghrelin-secreting epsilon-cells. Islets also contain non-endocrine cell types such as endothelial cells. However, the mechanism(s) of islet formation is poorly understood due to technical difficulties in capturing this dynamic event in situ. We have developed a method to monitor beta-cell proliferation and islet formation in the intact pancreas using transgenic mice in which the beta-cells are specifically tagged with a fluorescent protein. Endocrine cells proliferate contiguously, forming branched cord-like structures in both embryos and neonates. Our study has revealed long stretches of interconnected islets located along large blood vessels in the neonatal pancreas. Alpha-cells span the elongated islet-like structures, which we hypothesize represent sites of fission and facilitate the eventual formation of discrete islets. We propose that islet formation occurs by a process of fission following contiguous endocrine cell proliferation, rather than by local aggregation or fusion of isolated beta-cells and islets. Mathematical modeling of the fission process in the neonatal islet formation is also presented
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