282 research outputs found

    The Abnormally Weighting Energy Hypothesis: the Missing Link between Dark Matter and Dark Energy

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    We generalize tensor-scalar theories of gravitation by the introduction of an abnormally weighting type of energy. This theory of tensor-scalar anomalous gravity is based on a relaxation of the weak equivalence principle that is now restricted to ordinary visible matter only. As a consequence, the convergence mechanism toward general relativity is modified and produces naturally cosmic acceleration as an inescapable gravitational feedback induced by the mass-variation of some invisible sector. The cosmological implications of this new theoretical framework are studied. From the Hubble diagram cosmological test \textit{alone}, this theory provides an estimation of the amount of baryons and dark matter in the Universe that is consistent with the independent cosmological tests of Cosmic Microwave Background (CMB) and Big Bang Nucleosynthesis (BBN). Cosmic coincidence is naturally achieved from a equally natural assumption on the amplitude of the scalar coupling strength. Finally, from the adequacy to supernovae data, we derive a new intriguing relation between the space-time dependences of the gravitational coupling and the dark matter mass, providing an example of crucial constraint on microphysics from cosmology. This glimpses at an enticing new symmetry between the visible and invisible sectors, namely that the scalar charges of visible and invisible matter are exactly opposite.Comment: 24 pages, 6 figures, new version with extended discussions and added references. Accepted for publication in JCAP (sept. 2008

    Inflationary attractor in Gauss-Bonnet brane cosmology

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    The inflationary attractor properties of the canonical scalar field and Born-Infeld field are investigated in the Randall-Sundrum II scenario with a Gauss-Bonnet term in the bulk action. We find that the inflationary attractor property will always hold for both the canonical and Born-Infeld fields for any allowed non-negative Gauss-Bonnet coupling. We also briefly discuss the possibility of explaining the suppressed lower multiples and running scalar spectral index simultaneously in the scenario of Gauss-Bonnet brane inflation.Comment: 7 pages, no figures. An error in the discussion of BI field corrected, conclusion correcte

    Non linear equation of state and effective phantom divide in brane models

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    Here, DGP model of brane-gravity is analyzed and compared with the standard general relativity and Randall-Sundrum cases using non-linear equation of state. Phantom fluid is known to violate the weak energy condition. In this paper, it is found that this characteristic of phantom energy is affected drastically by the negative brane-tension λ\lambda of the RS-II model. It is found that in DGP model strong energy condition(SEC) is always violated and the universe accelerates only where as in RS-II model even SEC is not violated for 1<ρ/λ<21 < \rho/\lambda < 2 and the universe decelerates

    AcciĂłn de tutela y barreras de acceso a servicios de salud en labio y/o paladar hendido

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    La investigación busca identificar barreras de acceso a servicios de salud para la atención integral de pacientes con labio y/o paladar hendido (LPH) a partir del anålisis de acciones de tutela relacionadas con esta condición en un periodo de veinte años: 1994-2014. Se identificaron tutelas interpuestas por familiares de niños con LPH; se construyó una matriz para organizar los datos mås relevantes (motivos de tutela, fallo y consideraciones para este); posteriormente, se hizo un anålisis para identificar las barreras y la manera como la justicia resuelve la solicitud. En total, se analizaron once fallos de tutela. El principal motivo para interponerlas fue la negación por parte de la entidad promotora de salud de tratamientos para LPH por no encontrarse incluidos en el plan de atención en salud (catalogados como estéticos) o por falta de infraestructura para su atención. Cinco de ellas fueron negadas por razones administrativas o procedimentales, por dificultades en la afiliación a una entidad de salud o porque cesaron los efectos que motivaron la tutela. En las tutelas aceptadas, se obliga a realizar la atención integral, considerando la garantía del derecho a la salud en conexidad con los derechos a la vida, la dignidad y los derechos de los niños. Conclusión: la principal barrera de atención para pacientes con LPH se relaciona con el hecho de que algunos tratamientos no estån incluidos en el plan de atención en salud de Colombia; por tanto la acción de tutela, a la luz del derecho a la salu

    Reconceptualizing CSR in the media industry as relational accountability

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    In this paper, we reconceptualize CSR in the media industries by combining empirical data with theoretical perspectives emerging from the communication studies and business ethics literature. We develop a new conception of what corporate responsibility in media organizations may mean in real terms by bringing Bardoel and d’Haenens’ (European Journal of Communication 19 165–194 2004) discussion of the different dimensions of media accountability into conversation with the empirical results from three international focus group studies, conducted in France, the USA and South Africa. To enable a critical perspective on our findings, we perform a philosophical analysis of its implications for professional, public, market, and political accountability in the media, drawing on the insights of Paul Virilio. We come to the conclusion that though some serious challenges to media accountability exist, the battle for responsible media industries is not lost. In fact, the speed characterizing the contemporary media environment may hold some promise for fostering the kind of relational accountability that could underpin a new understanding of CSR in the media

    Overestimating Outcome Rates: Statistical Estimation When Reliability Is Suboptimal

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    To demonstrate how failure to account for measurement error in an outcome (dependent) variable can lead to significant estimation errors and to illustrate ways to recognize and avoid these errors. Data Sources . Medical literature and simulation models. Study Design/Data Collection . Systematic review of the published and unpublished epidemiological literature on the rate of preventable hospital deaths and statistical simulation of potential estimation errors based on data from these studies. Principal Findings . Most estimates of the rate of preventable deaths in U.S. hospitals rely upon classifying cases using one to three physician reviewers (implicit review). Because this method has low to moderate reliability, estimates based on statistical methods that do not account for error in the measurement of a “preventable death” can result in significant overestimation. For example, relying on a majority rule rating with three reviewers per case (reliability ∌0.45 for the average of three reviewers) can result in a 50–100 percent overestimation compared with an estimate based upon a reliably measured outcome (e.g., by using 50 reviewers per case). However, there are statistical methods that account for measurement error that can produce much more accurate estimates of outcome rates without requiring a large number of measurements per case. Conclusion . The statistical principles discussed in this case study are critically important whenever one seeks to estimate the proportion of cases belonging to specific categories (such as estimating how many patients have inadequate blood pressure control or identifying high-cost or low-quality physicians). When the true outcome rate is low (<20 percent), using an outcome measure that has low-to-moderate reliability will generally result in substantially overestimating the proportion of the population having the outcome unless statistical methods that adjust for measurement error are used.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/74896/1/j.1475-6773.2006.00661.x.pd

    Cosmological Dynamics of Phantom Field

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    We study the general features of the dynamics of the phantom field in the cosmological context. In the case of inverse coshyperbolic potential, we demonstrate that the phantom field can successfully drive the observed current accelerated expansion of the universe with the equation of state parameter wϕ<−1w_{\phi} < -1. The de-Sitter universe turns out to be the late time attractor of the model. The main features of the dynamics are independent of the initial conditions and the parameters of the model. The model fits the supernova data very well, allowing for −2.4<wϕ<−1-2.4 < w_{\phi} < -1 at 95 % confidence level.Comment: Typos corrected. Some clarifications and references added. To appear in Physical Review

    Complement C5a receptors and neutrophils mediate fetal injury in the antiphospholipid syndrome.

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    Antiphospholipid syndrome (APS) is defined by recurrent pregnancy loss and thrombosis in the presence of antiphospholipid (aPL) Ab’s. Currently, therapy for pregnant women with APS is focused on preventing thrombosis, but anticoagulation is only partially successful in averting miscarriage. We hypothesized that complement activation is a central mechanism of pregnancy loss in APS and tested this in a model in which pregnant mice receive human IgG containing aPL Ab’s. Here we identify complement component C5 (and particularly its cleavage product C5a) and neutrophils as key mediators of fetal injury, and we show that Ab’s or peptides that block C5a–C5a receptor interactions prevent pregnancy complications. The fact that F(ab)â€Č2 fragments of aPL Ab’s do not mediate fetal injury and that C4-deficient mice are protected from fetal injury suggests that activation of the complement cascade is initiated via the classical pathway. Studies in factor B–deficient mice, however, indicate that alternative pathway activation is required and amplifies complement activation. In contrast, activating FcÎłRs do not play an important role in mediating aPL Ab–induced fetal injury. Our findings identify the key innate immune effectors engaged by pathogenic autoantibodies that mediate poor pregnancy outcomes in APS and provide novel and important targets for prevention of pregnancy loss in APS
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