533 research outputs found

    K\"{a}hler-Einstein metrics on strictly pseudoconvex domains

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    The metrics of S. Y. Cheng and S.-T. Yau are considered on a strictly pseudoconvex domains in a complex manifold. Such a manifold carries a complete K\"{a}hler-Einstein metric if and only if its canonical bundle is positive. We consider the restricted case in which the CR structure on M\partial M is normal. In this case M must be a domain in a resolution of the Sasaki cone over M\partial M. We give a condition on a normal CR manifold which it cannot satisfy if it is a CR infinity of a K\"{a}hler-Einstein manifold. We are able to mostly determine those normal CR 3-manifolds which can be CR infinities. Many examples are given of K\"{a}hler-Einstein strictly pseudoconvex manifolds on bundles and resolutions.Comment: 30 pages, 1 figure, couple corrections, improved a couple example

    Post-natal parental care in a Cretaceous diapsid from northeastern China

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    Post-natal parental care seems to have evolved numerous times in vertebrates. Among extant amniotes, it is present in crocodilians, birds, and mammals. However, evidence of this behavior is extremely rare in the fossil record and is only reported for two types of dinosaurs, and a varanopid ‘pelycosaur’. Here we report new evidence for post-natal parental care in Philydrosaurus, a choristodere, from the Yixian Formation of western Liaoning Province, China. We review the fossil record of reproduction in choristoderes, and this represents the oldest record of post-natal parental care in diapsids to our knowledge

    Twenty five years after KLS: A celebration of non-equilibrium statistical mechanics

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    When Lenz proposed a simple model for phase transitions in magnetism, he couldn't have imagined that the "Ising model" was to become a jewel in field of equilibrium statistical mechanics. Its role spans the spectrum, from a good pedagogical example to a universality class in critical phenomena. A quarter century ago, Katz, Lebowitz and Spohn found a similar treasure. By introducing a seemingly trivial modification to the Ising lattice gas, they took it into the vast realms of non-equilibrium statistical mechanics. An abundant variety of unexpected behavior emerged and caught many of us by surprise. We present a brief review of some of the new insights garnered and some of the outstanding puzzles, as well as speculate on the model's role in the future of non-equilibrium statistical physics.Comment: 3 figures. Proceedings of 100th Statistical Mechanics Meeting, Rutgers, NJ (December, 2008

    No additional prognostic value of genetic information in the prediction of vascular events after cerebral ischemia of arterial origin

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    Background: Patients who have suffered from cerebral ischemia have a high risk of recurrent vascular events. Predictive models based on classical risk factors typically have limited prognostic value. Given that cerebral ischemia has a heritable component, genetic information might improve performance of these risk models. Our aim was to develop and compare two models: one containing traditional vascular risk factors, the other also including genetic information. Methods and Results: We studied 1020 patients with cerebral ischemia and genotyped them with the Illumina Immunochip. Median follow-up time was 6.5 years; the annual incidence of new ischemic events (primary outcome, n=198) was 3.0%. The prognostic model based on classical vascular risk factors had an area under the receiver operating characteristics curve (AUC-ROC) of 0.65 (95% confidence interval 0.61-0.69). When we added a genetic risk score based on prioritized SNPs from a genome-wide association study of ischemic stroke (using summary statistics from the METASTROKE study which included 12389 cases and 62004 controls), the AUC-ROC remained the same. Similar results were found for the secondary outcome ischemic stroke. Conclusions: We found no additional value of genetic information in a prognostic model for the risk of ischemic events in patients with cerebral ischemia of arterial origin. This is consistent with a complex, polygenic architecture, where many genes of weak effect likely act in concert to influence the heritable risk of an individual to develop (recurrent) vascular events. At present, genetic information cannot help clinicians to distinguish patients at high risk for recurrent vascular events

    Who Are the Workers Who Never Joined a Union? : Empirical Evidence from Western and Eastern Germany

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    "Using representative data from the German social survey ALLBUS 2002 and the European Social Survey 2002/03, this paper provides the first empirical analysis of trade union ‘never-membership’ in Germany. We show that between 54 and 59 percent of all employees in Germany have never been members of a trade union. In western Germany, individuals’ probability of ‘never-membership’ is significantly affected by their personal characteristics, their political orientation and (to a lesser degree) their family background. In addition, the presence of a union at the workplace plays a significant role. While the latter factor is also important in eastern Germany, many of the variables which are relevant for ‘never-membership’ in the west prove to be irrelevant in the east. This difference probably reflects the fact that most employees in eastern Germany did not really have a choice not to become union members during the communist regime." (author's abstract)"Mit Daten des ALLBUS 2002 und des European Social Survey 2002/03 analysiert diese Arbeit erstmalig die ‚Nie-Mitgliedschaft’ in deutschen Gewerkschaften. Wir zeigen, dass 54 bis 59 Prozent aller Beschäftigten in Deutschland niemals Mitglied einer Gewerkschaft waren. Die individuelle Wahrscheinlichkeit einer ‚Nie-Mitgliedschaft’ hängt in Westdeutschland signifikant mit persönlichen Merkmalen, der politischen Ausrichtung und (in geringerem Maße) dem familiären Hintergrund zusammen. Darüber hinaus spielt das Vorhandensein einer Gewerkschaft am Arbeitsplatz eine signifikante Rolle. Während letzteres auch in Ostdeutschland von Bedeutung ist, erweisen sich viele der im Westen relevanten Erklärungsvariablen im Osten als irrelevant. Dieser Unterschied spiegelt wahrscheinlich wider, dass die meisten Arbeitnehmer in Ostdeutschland während des SED-Regimes kaum die Wahl hatten, auf eine Gewerkschaftsmitgliedschaft zu verzichten." (Autorenreferat

    The Origin, Early Evolution and Predictability of Solar Eruptions

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    Coronal mass ejections (CMEs) were discovered in the early 1970s when space-borne coronagraphs revealed that eruptions of plasma are ejected from the Sun. Today, it is known that the Sun produces eruptive flares, filament eruptions, coronal mass ejections and failed eruptions; all thought to be due to a release of energy stored in the coronal magnetic field during its drastic reconfiguration. This review discusses the observations and physical mechanisms behind this eruptive activity, with a view to making an assessment of the current capability of forecasting these events for space weather risk and impact mitigation. Whilst a wealth of observations exist, and detailed models have been developed, there still exists a need to draw these approaches together. In particular more realistic models are encouraged in order to asses the full range of complexity of the solar atmosphere and the criteria for which an eruption is formed. From the observational side, a more detailed understanding of the role of photospheric flows and reconnection is needed in order to identify the evolutionary path that ultimately means a magnetic structure will erupt

    Multidimensional quantum solitons with nondegenerate parametric interactions: Photonic and Bose-Einstein condensate environments

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    We consider the quantum theory of three fields interacting via parametric and repulsive quartic couplings. This can be applied to treat photonic chi((2)) and chi((3)) interactions, and interactions in atomic Bose-Einstein condensates or quantum Fermi gases, describing coherent molecule formation together with a-wave scattering. The simplest two-particle quantum solitons or bound-state solutions of the idealized Hamiltonian, without a momentum cutoff, are obtained exactly. They have a pointlike structure in two and three dimensions-even though the corresponding classical theory is nonsingular. We show that the solutions can be regularized with a momentum cutoff. The parametric quantum solitons have much more realistic length scales and binding energies than chi((3)) quantum solitons, and the resulting effects could potentially be experimentally tested in highly nonlinear optical parametric media or interacting matter-wave systems. N-particle quantum solitons and the ground state energy are analyzed using a variational approach. Applications to atomic/molecular Bose-Einstein condensates (BEC's) are given, where we predict the possibility of forming coupled BEC solitons in three space dimensions, and analyze superchemistry dynamics

    Trans-ancestry genome-wide association study identifies 12 genetic loci influencing blood pressure and implicates a role for DNA methylation

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    We carried out a trans-ancestry genome-wide association and replication study of blood pressure phenotypes among up to 320,251 individuals of East Asian, European and South Asian ancestry. We find genetic variants at 12 new loci to be associated with blood pressure (P = 3.9 × 10-11 to 5.0 × 10-21). The sentinel blood pressure SNPs are enriched for association with DNA methylation at multiple nearby CpG sites, suggesting that, at some of the loci identified, DNA methylation may lie on the regulatory pathway linking sequence variation to blood pressure. The sentinel SNPs at the 12 new loci point to genes involved in vascular smooth muscle (IGFBP3, KCNK3, PDE3A and PRDM6) and renal (ARHGAP24, OSR1, SLC22A7 and TBX2) function. The new and known genetic variants predict increased left ventricular mass, circulating levels of NT-proBNP, and cardiovascular and all-cause mortality (P = 0.04 to 8.6 × 10-6). Our results provide new evidence for the role of DNA methylation in blood pressure regulation

    Leituras da Orfandade família, Declínio do Pai e Ausência de Lei. uma Abordagem do Universo Ficcional de Rubem Fonseca.

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    RESUMO Observamos na contemporaneidade que a família assume formas diferentes às que possuía quando foi formulada, no século XVIII. Caracterizada por inúmeras transformações, já não possui uma estrutura tão fixa. A partir das narrativas de Henri, A força humana, Feliz ano novo e O cobrador, de Rubem Fonseca; não deixando de visitar outros trabalhos do escritor, discutiremos e examinaremos as configurações da família contemporânea. Neste sentido, analisaremos as representações da relação do sujeito com as novas estruturas familiares, o declínio da imago paterna e as consequências que essas transformações trazem à subjetividade, bem como as formas pelas quais tais relações são encenadas literariamente pelo escritor brasileir

    Can COBE see the shape of the universe?

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    In recent years, the large angle COBE--DMR data have been used to place constraints on the size and shape of certain topologically compact models of the universe. Here we show that this approach does not work for generic compact models. In particular, we show that compact hyperbolic models do not suffer the same loss of large angle power seen in flat or spherical models. This follows from applying a topological theorem to show that generic hyperbolic three manifolds support long wavelength fluctuations, and by taking into account the dominant role played by the integrated Sachs-Wolfe effect in a hyperbolic universe.Comment: 16 Pages, 5 Figures. Version published in Phys. Rev.
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