1,998 research outputs found

    Supersymmetric Kundt four manifolds and their spinorial evolution flows

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    We investigate the differential geometry and topology of four-dimensional Lorentzian manifolds (M,g)(M,g) equipped with a real Killing spinor ε\varepsilon, where ε\varepsilon is defined as a section of a bundle of irreducible real Clifford modules satisfying the Killing spinor equation with non-zero real constant. Such triples (M,g,ε)(M,g,\varepsilon) are precisely the supersymmetric configurations of minimal four-dimensional supergravity and necessarily belong to the class Kundt of space-times, hence we refer to them as supersymmetric Kundt configurations. We characterize a class of Lorentzian metrics on R2×X\mathbb{R}^2\times X, where XX is a two-dimensional oriented manifold, to which every supersymmetric Kundt configuration is locally isometric, proving that XX must be an elementary hyperbolic Riemann surface when equipped with the natural induced metric. This yields a class of space-times that vastly generalize the Siklos class of space-times describing gravitational waves in AdS4_4. Furthermore, we study the Cauchy problem posed by a real Killing spinor and we prove that the corresponding evolution problem is equivalent to a system of differential flow equations, the real Killing spinorial flow equations, for a family of functions and coframes on any Cauchy hypersurface ΣM\Sigma\subset M. Using this formulation, we prove that the evolution flow defined by a real Killing spinor preserves the Hamiltonian and momentum constraints of the Einstein equation with negative curvature and is therefore compatible with the latter. Moreover, we explicitly construct all left-invariant evolution flows defined by a Killing spinor on a simply connected three-dimensional Lie group, classifying along the way all solutions to the corresponding constraint equations, some of which also satisfy the constraint equations associated to the Einstein condition.Comment: 28 pages, 2 tables. Minor text fixe

    Crystal structure of the catalytic fragment of murine poly(ADP-ribose) polymerase-2.

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    Poly(ADP-ribose) polymerase-1 (PARP-1) has become an important pharmacological target in the treatment of cancer due to its cellular role as a 'DNA-strand break sensor', which leads in part to resistance to some existing chemo- and radiological treatments. Inhibitors have now been developed which prevent PARP-1 from synthesizing poly(ADP-ribose) in response to DNA-breaks and potentiate the cytotoxicity of DNA damaging agents. However, with the recent discoveries of PARP-2, which has a similar DNA-damage dependent catalytic activity, and additional members containing the 'PARP catalytic' signature, the isoform selectivity and resultant pharmacological effects of existing inhibitors are brought into question. We present here the crystal structure of the catalytic fragment of murine PARP-2, at 2.8 A resolution, and compare this to the catalytic fragment of PARP-1, with an emphasis on providing a possible framework for rational drug design in order to develop future isoform-specific inhibitors

    Macro-Prudential Assessment of Colombian Financial Institutions’ Systemic Importance

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    Three metrics are designed to assess Colombian financial institutions’ size, connectedness and non-­substitutability as the main drivers of systemic importance: (i) centrality as net borrower in the money market network; (ii) centrality as payments originator in the large-value payment system network, and (iii) asset value of core financial services. Two systemic importance indexes are calculated based on two different aggregation methods for the three metrics: fuzzy logic and principal component analysis. The resulting indexes are complementary and provide a comprehensive relative assessment of each financial institution’s systemic importance in the Colombian case, in which the choice of metrics pursues the macro-­prudential perspective of financial stability. They both (i) agree on the skewed (i.e. inhomogeneous) nature of systemic importance and its approximate scale-­free distribution; (ii) on the preeminence of credit institutions as the main contributors to systemic importance, and (iii) on the non-­‐trivial importance of a few non-­‐banking institutions

    DIMENSIONS OF FINANCIAL WELLBEING: AN ALTERNATIVE SCALE FOR MICROFINANCE BORROWERS IN DIGOS CITY, PHILIPPINES

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    The aim of this study is to establish the dimensions of financial wellbeing of microfinance borrowers in Digos City. A sequential-exploratory mixed methods research design was used as the approach of the study, and data were gathered from N=10 key informant interviews which then became the basis in the development of the preliminary 30-item financial wellbeing scale. A total of N=377 lenders of microfinance institutions in Digos City participated in the cross-sectional online and face-to-face survey. Descriptive statistics and multivariate analysis via exploratory factor analysis were used as statistical tools, all carried in IBM-SPSS 20. Results revealed that 26 of the 28 items were found to have passed the +0.40-coefficient requirement. These 26 items clustered in five extracted dimensions. Thematic analysis of the item loadings revealed three valid dimensions – freedom from debt, investment and financial discipline, and financial resilience – all with acceptable Cronbach’s α and McDonald’s ω values. Implications of the utility of this alternative scale of financial wellbeing are discussed. JEL: D01; D31  Article visualizations

    Viral antibody dynamics in a chiropteran host

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    1. Bats host many viruses that are significant for human and domestic animal health, but the dynamics of these infections in their natural reservoir hosts remain poorly elucidated.<p></p> 2. In these, and other, systems, there is evidence that seasonal life-cycle events drive infection dynamics, directly impacting the risk of exposure to spillover hosts. Understanding these dynamics improves our ability to predict zoonotic spillover from the reservoir hosts.<p></p> 3. To this end, we followed henipavirus antibody levels of >100 individual E. helvum in a closed, captive, breeding population over a 30-month period, using a powerful novel antibody quantitation method.<p></p> 4. We demonstrate the presence of maternal antibodies in this system and accurately determine their longevity. We also present evidence of population-level persistence of viral infection and demonstrate periods of increased horizontal virus transmission associated with the pregnancy/lactation period.<p></p> 5.The novel findings of infection persistence and the effect of pregnancy on viral transmission, as well as an accurate quantitation of chiropteran maternal antiviral antibody half-life, provide fundamental baseline data for the continued study of viral infections in these important reservoir hosts

    A temperature sensitive live-attenuated canine influenza virus H3N8 vaccine

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    Canine influenza is a respiratory disease of dogs caused by canine influenza virus (CIV). CIV subtypes responsible for influenza in dogs include H3N8, which originated from the transfer of H3N8 equine influenza virus to dogs; and the H3N2 CIV, which is an avian-origin virus that adapted to infect dogs. Influenza infections are most effectively prevented through vaccination to reduce transmission and future infection. Currently, only inactivated influenza vaccines (IIVs) are available for the prevention of CIV in dogs. However, the efficacy of IIVs is suboptimal, and novel approaches are necessary for the prevention of disease caused by this canine respiratory pathogen. Using reverse genetics techniques, we have developed a live-attenuated CIV vaccine (LACIV) for the prevention of H3N8 CIV. The H3N8 LACIV replicates efficiently in canine cells at 33°C but is impaired at temperatures of 37 to 39°C and was attenuated compared to wild-type H3N8 CIV in vivo and ex vivo. The LACIV was able to induce protection against H3N8 CIV challenge with a single intranasal inoculation in mice. Immunogenicity and protection efficacy were better than that observed with a commercial CIV H3N8 IIV but provided limited cross-reactive immunity and heterologous protection against H3N2 CIV. These results demonstrate the feasibility of implementing a LAIV approach for the prevention and control of H3N8 CIV in dogs and suggest the need for a new LAIV for the control of H3N2 CIV. Importance: Two influenza A virus subtypes has been reported in dogs in the last 16 years: the canine influenza viruses (CIV) H3N8 and H3N2 of equine and avian origins, respectively. To date, only inactivated influenza vaccines (IIVs) are available to prevent CIV infections. Here, we report the generation of a recombinant, temperature-sensitive H3N8 CIV as a live-attenuated influenza vaccine (LAIV), which was attenuated in mice and dog tracheal, explants compared to CIV H3N8 wild type. A single dose of H3N8 LACIV showed immunogenicity and protection against a homologous challenge that was better than that conferred with an H3N8 IIV, demonstrating the feasibility of implementing a LAIV approach for the improved control of H3N8 CIV infections in dogs
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