1,891 research outputs found

    A Growing Hole in the Safety Net: Physician Charity Care Declines Again

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    Examines reasons for the decline in the number of physicians providing free or reduced cost health care in proportion to the number of uninsured Americans, in the last decade. Includes implications related to the decline in access to medical care

    Is the dynamics of open quantum systems always linear?

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    We study the influence of the preparation of an open quantum system on its reduced time evolution. In contrast to the frequently considered case of an initial preparation where the total density matrix factorizes into a product of a system density matrix and a bath density matrix the time evolution generally is no longer governed by a linear map nor is this map affine. Put differently, the evolution is truly nonlinear and cannot be cast into the form of a linear map plus a term that is independent of the initial density matrix of the open quantum system. As a consequence, the inhomogeneity that emerges in formally exact generalized master equations is in fact a nonlinear term that vanishes for a factorizing initial state. The general results are elucidated with the example of two interacting spins prepared at thermal equilibrium with one spin subjected to an external field. The second spin represents the environment. The field allows the preparation of mixed density matrices of the first spin that can be represented as a convex combination of two limiting pure states, i.e. the preparable reduced density matrices make up a convex set. Moreover, the map from these reduced density matrices onto the corresponding density matrices of the total system is affine only for vanishing coupling between the spins. In general, the set of the accessible total density matrices is nonconvex.Comment: 19 pages, 3 figures, minor changes to improve readability, discussion on Mori's linear regime and references adde

    Wide complex tachycardia differentiation: A reappraisal of the state-of-the-art

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    The primary goal of the initial ECG evaluation of every wide complex tachycardia is to determine whether the tachyarrhythmia has a ventricular or supraventricular origin. The answer to this question drives immediate patient care decisions, ensuing clinical workup, and long-term management strategies. Thus, the importance of arriving at the correct diagnosis cannot be understated and has naturally spurred rigorous research, which has brought forth an ever-expanding abundance of manually applied and automated methods to differentiate wide complex tachycardias. In this review, we provide an in-depth analysis of traditional and more contemporary methods to differentiate ventricular tachycardia and supraventricular wide complex tachycardia. In doing so, we: (1) review hallmark wide complex tachycardia differentiation criteria, (2) examine the conceptual and structural design of standard wide complex tachycardia differentiation methods, (3) discuss practical limitations of manually applied ECG interpretation approaches, and (4) highlight recently formulated methods designed to differentiate ventricular tachycardia and supraventricular wide complex tachycardia automatically

    Microeconomia neoclássica contra a Natureza : constructos, conceitos e armadilhas sócio-ecológicas da teoria econômica no Antropoceno

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    Vastas evidências científicas apontam consequências planetárias que, além de profundas, foram imprevistas por diversas tradições do pensamento socioeconômico. Este artigo investiga a microeconomia neoclássica, que, se definida consoante sua mensagem fundamental, é a teoria do puro egoísmo como agente do bem comum, assegurado pelo liberalismo em mercados existentes, crescentes e novos, tradição em que a maioria dos economistas é formada. Para destrinçar tal microeconomia e suas repercussões sociais e ecológicas, realizamos uma revisão holística que combina o exame de seus conceitos socioecológicos (bens públicos, externalidade, equilíbrio geral e propriedades de bem-estar), fragilidades e paradoxos metodológicos do programa, e formas primárias de, não prever, criar realidade conforme seus motivos e métodos, afetando o desenho institucional, como o mercado de carbono e as avaliações valorativas do meio ambiente. A microeconomia, âmago científico do neoliberalismo, tem sido crucial na leitura de mundo, inclusive da crise planetária, na qual, a partir de uma certa perspectiva econômica, alegadamente neutra e universal, oferece respostas. Faz crer que é mais parte da solução do que do problema, levando a situações esdrúxulas como o ensino perpetuado da "prova" do equilíbrio geral, quando temos um enorme desequilíbrio planetário. O Antropoceno é senão um reflexo em larga escala das falácias atribuíveis ao Homo economicus, ao equilíbrio geral e aos processos econômicos capitalistas.Vasta evidencia científica apunta a consecuencias planetarias que, además de profundas, fueron imprevistas por diferentes tradiciones de pensamiento socioeconómico. Este artículo investiga la microeconomía neoclásica, que, si se define de acuerdo con su mensaje fundamental, es la teoría del egoísmo puro como agente del bien común, asegurado por el liberalismo en los mercados existentes, en crecimiento y nuevos, una tradición en la que se forman la mayoría de los economistas. Para desentrañar dicha microeconomía y sus repercusiones sociales y ecológicas, llevamos a cabo una revisión holística que combina el examen de sus conceptos socioecológicos (bienes públicos, externalidad, balance general y propiedades de bienestar), debilidades metodológicas y paradojas del programa, y ​​primarias. formas de, no predecir, crear la realidad según sus motivos y métodos, afectando el diseño institucional, como el mercado de carbono y las evaluaciones de valoración del medio ambiente. La microeconomía, núcleo científico del neoliberalismo, ha sido crucial en la lectura del mundo, incluida la crisis planetaria, en la que, desde una cierta perspectiva económica, pretendidamente neutra y universal, ofrece respuestas. Nos hace creer que es más parte de la solución que del problema, lo que lleva a situaciones bizarras como la enseñanza perpetuada de la "prueba" del equilibrio general, cuando tenemos un gran desequilibrio planetario. El Antropoceno no es más que un reflejo a gran escala de las falacias atribuibles al Homo economicus, el equilibrio general y los procesos económicos capitalistas.Extensive scientific evidence points to human activity's planetary impacts, which have profound andunforeseen consequences for various traditions of socio-economic thought. This article investigatesmicroeconomics, the theory of pure selfishness as an agent of the common good, ensured byliberalism in existing, emerging and new markets, a tradition in which most economists are trained.To untangle microeconomics' social and ecological repercussions, we adopt a holistic approachcombining a breakdown of its socio-ecological concepts (public goods, externality, generalequilibrium and welfare properties), methodological shortcomings and paradoxes of the program, and primary ways to, rather than predict, create reality according to its motives and methods, affecting institutional design, such as the carbon market and monetary valuations of the environment. Microeconomics, the scientific heart of neoliberalism, has been crucial in reading the world, including the planetary crisis, for which, from a particular economic perspective, allegedly neutral and universal, it offers answers. It makes one believe that it is more part of the solution than the problem, leading to such bizarre situations as perpetuating the teaching of general equilibrium "proof" when we face a vast planetary imbalance. The Anthropocene is but a large-scale reflection of the fallacies attributable to Homo economicus, general equilibrium, and capitalist economic processes

    Localization of the succinate receptor in the distal nephron and its signaling in polarized MDCK cells

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    When the succinate receptor (SUCNR1) is activated in the afferent arterioles of the glomerulus it increases renin release and induces hypertension. To study its location in other nephron segments and its role in kidney function, we performed immunohistochemical analysis and found that SUCNR1 is located in the luminal membrane of macula densa cells of the juxtaglomerular apparatus in close proximity to renin-producing granular cells, the cortical thick ascending limb, and cortical and inner medullary collecting duct cells. In order to study its signaling, SUCNR1 was stably expressed in Madin-Darby Canine Kidney (MDCK) cells, where it localized to the apical membrane. Activation of the cells by succinate caused Gq and Gi-mediated intracellular calcium mobilization, transient phosphorylation of extracellular regulated kinase (ERK)1/2 and the release of arachidonic acid along with prostaglandins E2 and I2. Signaling was desensitized without receptor internalization but rapidly resensitized upon succinate removal. Immunohistochemical evidence of phosphorylated ERK1/2 was found in cortical collecting duct cells of wild type but not SUCNR1 knockout streptozotocin-induced diabetic mice, indicating in vivo relevance. Since urinary succinate concentrations in health and disease are in the activation range of the SUCNR1, this receptor can sense succinate in the luminal fluid. Our study suggests that changes in the luminal succinate concentration may regulate several aspects of renal function

    Multiplicity of Plasmodium falciparum infection following intermittent preventive treatment in infants

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    ABSTRACT: BACKGROUND: Intermittent preventive treatment in infants with sulphadoxine-pyrimethamine (IPTi-SP) reduces malaria morbidity by 20% to 33%. Potentially, however, this intervention may compromise the acquisition of immunity, including the tolerance towards multiple infections with Plasmodium falciparum. METHODS: Plasmodium falciparum isolates were obtained from children participating in two Ghanaian IPTi-SP trials (Tamale, Afigya Sekyere) at 15 months of age, i.e., six months after they had received the second dose of IPTi-SP or placebo. By typing the polymorphic merozoite surface protein 1 (msp1) and msp2 genes, multiplicity of infection (MOI) was assessed in 389 isolates. A total of additional 133 samples were collected in Tamale at 3, 6, 9, and 12 months of age. Comparisons of MOI between groups were done by non-parametric statistical tests. RESULTS: The number of distinguishable P. falciparum clones (MOI) ranged between one and six. Mean MOI in Tamale was stable at 2.13 - 2.17 during the first year of life, and increased to 2.57 at age 15 months (P = 0.01). At no age did MOI differ between the IPTi-SP and placebo groups (each, P [greater than or equal to] 0.5). At 15 months of age, i.e., six months after the second dose, MOI was very similar for children who had received IPTi or placebo (means, 2.25 vs. 2.33; P = 0.55) as was the proportion of polyclonal infections (69.6% vs. 69.7%; P = 0.99). Adjusting for study site, current and prior malaria, parasite density, and season did not change this finding. CONCLUSIONS: IPTi-SP appears to have no impact on the multiplicity of infection during infancy and thereafter. This suggests that tolerance of multiple infections, a component of protective immunity in highly endemic areas, is not affected by this interventio

    Differentiating wide complex tachycardias: A historical perspective

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    One of the most critical and challenging skills is the distinction of wide complex tachycardias into ventricular tachycardia or supraventricular wide complex tachycardia. Prompt and accurate differentiation of wide complex tachycardias naturally influences short- and long-term management decisions and may directly affect patient outcomes. Currently, there are many useful electrocardiographic criteria and algorithms designed to distinguish ventricular tachycardia and supraventricular wide complex tachycardia accurately; however, no single approach guarantees diagnostic certainty. In this review, we offer an in-depth analysis of available methods to differentiate wide complex tachycardias by retrospectively examining its rich literature base - one that spans several decades

    Measles vaccination in the presence or absence of maternal measles antibody: impact on child survival.

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    BACKGROUND: Measles vaccine (MV) has a greater effect on child survival when administered in early infancy, when maternal antibody may still be present. METHODS: To test whether MV has a greater effect on overall survival if given in the presence of maternal measles antibody, we reanalyzed data from 2 previously published randomized trials of a 2-dose schedule with MV given at 4-6 months and at 9 months of age. In both trials antibody levels had been measured before early measles vaccination. RESULTS: In trial I (1993-1995), the mortality rate was 0.0 per 1000 person-years among children vaccinated with MV in the presence of maternal antibody and 32.3 per 1000 person-years without maternal antibody (mortality rate ratio [MRR], 0.0; 95% confidence interval [CI], 0-.52). In trial II (2003-2007), the mortality rate was 4.2 per 1000 person-years among children vaccinated in presence of maternal measles antibody and 14.5 per 1000 person-years without measles antibody (MRR, 0.29; 95% CI, .09-.91). Possible confounding factors did not explain the difference. In a combined analysis, children who had measles antibody detected when they received their first dose of MV at 4-6 months of age had lower mortality than children with no maternal antibody, the MRR being 0.22 (95% CI, .07-.64) between 4-6 months and 5 years. CONCLUSIONS: Child mortality in low-income countries may be reduced by vaccinating against measles in the presence of maternal antibody, using a 2-dose schedule with the first dose at 4-6 months (earlier than currently recommended) and a booster dose at 9-12 months of age. CLINICAL TRIALS REGISTRATION: NCT00168558

    Multi-level governance and power in climate change policy networks

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    This article proposes an innovative theoretical framework that combines institutional and policy network approaches to study multi-level governance. The framework is used to derive a number of propositions on how cross-level power imbalances shape communication and collaboration across multiple levels of governance. The framework is then applied to examine the nature of cross-level interactions in climate change mitigation and adaptation policy processes in the land use sectors of Brazil and Indonesia. The paper identifies major barriers to cross-level communication and collaboration between national and sub-national levels. These are due to power imbalances across governance levels that reflect broader institutional differences between federal and decentralized systems of government. In addition, powerful communities operating predominantly at the national level hamper cross-level interactions. The analysis also reveals that engagement of national level actors is more extensive in the mitigation and that of local actors in the adaptation policy domain, and specialisation in one of the climate change responses at the national level hampers effective climate policy integration in the land use sector.Peer reviewe

    Snowpack measurements suggest role for multi-year sea ice regions in Arctic atmospheric bromine and chlorine chemistry

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    As sources of reactive halogens, snowpacks in sea ice regions control the oxidative capacity of the Arctic atmosphere. However, measurements of snowpack halide concentrations remain sparse, particularly in the high Arctic, limiting our understanding of and ability to parameterize snowpack participation in tropospheric halogen chemistry. To address this gap, we measured concentrations of chloride, bromide, and sodium in snow samples collected during polar spring above remote multi-year sea ice (MYI) and first-year sea ice (FYI) north of Greenland and Alaska, as well as in the central Arctic, and compared these measurements to a larger dataset collected in the Alaskan coastal Arctic by Krnavek et al. (2012). Regardless of sea ice region, these surface snow samples generally featured lower salinities, compared to coastal snow. Surface snow in FYI regions was typically enriched in bromide and chloride compared to seawater, indicating snowpack deposition of bromine and chlorine-containing trace gases and an ability of the snowpack to participate further in bromine and chlorine activation processes. In contrast, surface snow in MYI regions was more often depleted in bromide, indicating it served as a source of bromine-containing trace gases to the atmosphere prior to sampling. Measurements at various snow depths indicate that the deposition of sea salt aerosols and halogen-containing trace gases to the snowpack surface played a larger role in determining surface snow halide concentrations compared to upward brine migration from sea ice. Calculated enrichment factors for bromide and chloride, relative to sodium, in the MYI snow samples suggests that MYI regions, in addition to FYI regions, have the potential to play an active role in Arctic boundary layer bromine and chlorine chemistry. The ability of MYI regions to participate in springtime atmospheric halogen chemistry should be considered in regional modeling of halogen activation and interpretation of satellite-based tropospheric bromine monoxide column measurements
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