719 research outputs found

    Classes of exact Einstein-Maxwell solutions

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    We find new classes of exact solutions to the Einstein-Maxwell system of equations for a charged sphere with a particular choice of the electric field intensity and one of the gravitational potentials. The condition of pressure isotropy is reduced to a linear, second order differential equation which can be solved in general. Consequently we can find exact solutions to the Einstein-Maxwell field equations corresponding to a static spherically symmetric gravitational potential in terms of hypergeometric functions. It is possible to find exact solutions which can be written explicitly in terms of elementary functions, namely polynomials and product of polynomials and algebraic functions. Uncharged solutions are regainable with our choice of electric field intensity; in particular we generate the Einstein universe for particular parameter values.Comment: 16 pages, To appear in Gen. Relativ. Gravi

    Low-lying quadrupole collective states of the light and medium Xenon isotopes

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    Collective low lying levels of light and medium Xenon isotopes are deduced from the Generalized Bohr Hamiltonian (GBH). The microscopic seven functions entering into the GBH are built from a deformed mean field of the Woods-Saxon type. Theoretical spectra are found to be close to the ones of the experimental data taking into account that the calculations are completely microscopic, that is to say, without any fitting of parameters.Comment: 8 pages, 4 figures, 1 tabl

    Time to revisit the definition and clinical criteria for anaphylaxis?

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    Anaphylaxis represents the severe end of the spectrum of allergic reactions. A number of different definitions for anaphylaxis are currently foundin the literature (Table 1).[1-6]Manydefine anaphylaxis as a life-threatening reaction. However, data from large case series and patient registries have demonstrated that despite the fact thatthe vast majority of anaphylaxisreactionsare not treated appropriately with prompt administration of epinephrine/adrenaline, ingeneral this does not result in increased mortality or morbidity(such as hospitalization);[7-9]this observation is also consistent with national epidemiological datafor food anaphylaxis, which indicate that fatal anaphylaxis is a rare (but unpredictable) event.[10-12]Therefore, the majority of anaphylaxis reactions cannot be described as life-threatening in themselves,althoughdue to our inability to predict severity of reaction, [12]we emphasise that all anaphylaxis must be appropriately treated with intramuscular epinephrine/adrenaline. Both the descriptions used by the Australasian Society of Clinical Immunology and Allergy (ASCIA)[4] and National Institute of Allergy and Infectious Disease (NIAID)[5] refer to anaphylaxis as a serious allergic reaction, and acknowledge the spectrum of severity in terms of identifying the potential for anaphylaxis to be life-threatening

    Stars in five dimensional Kaluza Klein gravity

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    In the five dimensional Kaluza Klein (KK) theory there is a well known class of static and electromagnetic--free KK--equations characterized by a naked singularity behavior, namely the Generalized Schwarzschild solution (GSS). We present here a set of interior solutions of five dimensional KK--equations. These equations have been numerically integrated to match the GSS in the vacuum. The solutions are candidates to describe the possible interior perfect fluid source of the exterior GSS metric and thus they can be models for stars for static, neutral astrophysical objects in the ordinary (four dimensional) spacetime.Comment: 15 pages, 8 figures. To be published in EPJ

    PneuMum: Impact from a randomised controlled trial of maternal 23-valent pneumococcal polysaccharide vaccination on middle ear disease amongst Indigenous infants, Northern Territory, Australia

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    BackgroundWe assessed maternal 23-valent pneumococcal polysaccharide (23vPPV) vaccine efficacy (VE) against middle ear disease and pneumococcal carriage amongst Australian Indigenous infants.MethodsIn an open label, allocation concealed, outcome-assessor blinded, community stratified, randomised controlled trial, healthy pregnant Indigenous women aged 17–39 years in the Northern Territory of Australia received the 23vPPV (1:1:1) at: 30–36 weeks gestation, birth, or were unvaccinated (ClinicalTrials.gov NCT00714064). Co-primary outcomes were the point prevalences of infant middle ear disease and 23vPPV-type carriage at age 7 months.ResultsThe consent rate was 50% (313/632). Among 227 eligible participants randomised, retention rates were 86% (66/77) controls; 89% (67/75) pregnancy vaccinees; 88% (66/75) birth vaccinees. At infant age 7 months, ear disease prevalence was: 71% (47/66) controls, 63% (42/67) pregnancy vaccinees, 76% (50/66) birth vaccinees; and 23vPPV-type carriage was: 26% (17/66) controls, 18% (12/67) pregnancy vaccinees, 18% (12/66) birth vaccinees. For pregnancy vaccinees, VE was 12% (95% CI −12% to 31%) against infant ear disease and 30% (95% CI −34% to 64%) against 23vPPV-type carriage. In a post-hoc analysis, VE against infant ear disease concurrent with carriage of 23vPPV or related types was 51% (95% CI −2% to 76%). There were no serious adverse effects following receipt of the 23vPPV in pregnancy or at birth.ConclusionsIn a high risk population, our study was unable to demonstrate efficacy of 23vPPV in pregnancy against the co-primary outcomes of either all-cause infant ear disease or 23vPPV-type nasopharyngeal carriage at age 7 months. Efficacy against ear disease concurrent with carriage of vaccine-related serotypes (a more specific outcome) suggests 23vPPV in pregnancy may complement childhood pneumococcal vaccination programs

    Persistent misconceptions about HIV transmission among males and females in Malawi

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    Background: The prevalence of HIV in Malawi is one of the highest in sub-Saharan Africa, and misconceptions about its mode of transmission are considered a major contributor to the continued spread of the virus. Methods: Using the 2010 Malawi Demographic and Health Survey, the current study explored factors associated with misconceptions about HIV transmission among males and females. Results: We found that higher levels of ABC prevention knowledge were associated with lower likelihood of endorsing m

    Search for lepton-flavor violation at HERA

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    A search for lepton-flavor-violating interactions epμXe p \to \mu X and epτXe p\to \tau X has been performed with the ZEUS detector using the entire HERA I data sample, corresponding to an integrated luminosity of 130 pb^{-1}. The data were taken at center-of-mass energies, s\sqrt{s}, of 300 and 318 GeV. No evidence of lepton-flavor violation was found, and constraints were derived on leptoquarks (LQs) that could mediate such interactions. For LQ masses below s\sqrt{s}, limits were set on λeq1βq\lambda_{eq_1} \sqrt{\beta_{\ell q}}, where λeq1\lambda_{eq_1} is the coupling of the LQ to an electron and a first-generation quark q1q_1, and βq\beta_{\ell q} is the branching ratio of the LQ to the final-state lepton \ell (μ\mu or τ\tau) and a quark qq. For LQ masses much larger than s\sqrt{s}, limits were set on the four-fermion interaction term λeqαλqβ/MLQ2\lambda_{e q_\alpha} \lambda_{\ell q_\beta} / M_{\mathrm{LQ}}^2 for LQs that couple to an electron and a quark qαq_\alpha and to a lepton \ell and a quark qβq_\beta, where α\alpha and β\beta are quark generation indices. Some of the limits are also applicable to lepton-flavor-violating processes mediated by squarks in RR-Parity-violating supersymmetric models. In some cases, especially when a higher-generation quark is involved and for the process epτXe p\to \tau X , the ZEUS limits are the most stringent to date.Comment: 37 pages, 10 figures, Accepted by EPJC. References and 1 figure (Fig. 6) adde

    Multijet production in neutral current deep inelastic scattering at HERA and determination of alpha_s

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    Multijet production rates in neutral current deep inelastic scattering have been measured in the range of exchanged boson virtualities 10 < Q2 < 5000 GeV2. The data were taken at the ep collider HERA with centre-of-mass energy sqrt(s) = 318 GeV using the ZEUS detector and correspond to an integrated luminosity of 82.2 pb-1. Jets were identified in the Breit frame using the k_T cluster algorithm in the longitudinally invariant inclusive mode. Measurements of differential dijet and trijet cross sections are presented as functions of jet transverse energy E_{T,B}{jet}, pseudorapidity eta_{LAB}{jet} and Q2 with E_{T,B}{jet} > 5 GeV and -1 < eta_{LAB}{jet} < 2.5. Next-to-leading-order QCD calculations describe the data well. The value of the strong coupling constant alpha_s(M_Z), determined from the ratio of the trijet to dijet cross sections, is alpha_s(M_Z) = 0.1179 pm 0.0013(stat.) {+0.0028}_{-0.0046}(exp.) {+0.0064}_{-0.0046}(th.)Comment: 22 pages, 5 figure

    Measurement of (anti)deuteron and (anti)proton production in DIS at HERA

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    The first observation of (anti)deuterons in deep inelastic scattering at HERA has been made with the ZEUS detector at a centre-of-mass energy of 300--318 GeV using an integrated luminosity of 120 pb-1. The measurement was performed in the central rapidity region for transverse momentum per unit of mass in the range 0.3<p_T/M<0.7. The particle rates have been extracted and interpreted in terms of the coalescence model. The (anti)deuteron production yield is smaller than the (anti)proton yield by approximately three orders of magnitude, consistent with the world measurements.Comment: 26 pages, 9 figures, 5 tables, submitted to Nucl. Phys.

    Photoproduction of D±D^{*\pm} mesons associated with a leading neutron

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    The photoproduction of D±(2010)D^{*\pm} (2010) mesons associated with a leading neutron has been observed with the ZEUS detector in epep collisions at HERA using an integrated luminosity of 80 pb1^{-1}. The neutron carries a large fraction, {xL>0.2x_L>0.2}, of the incoming proton beam energy and is detected at very small production angles, {θn<0.8\theta_n<0.8 mrad}, an indication of peripheral scattering. The DD^* meson is centrally produced with pseudorapidity {η1.9|\eta| 1.9 GeV}, which is large compared to the average transverse momentum of the neutron of 0.22 GeV. The ratio of neutron-tagged to inclusive DD^* production is 8.85±0.93(stat.)0.61+0.48(syst.)%8.85\pm 0.93({\rm stat.})^{+0.48}_{-0.61}({\rm syst.})\% in the photon-proton center-of-mass energy range {130<W<280130 <W<280 GeV}. The data suggest that the presence of a hard scale enhances the fraction of events with a leading neutron in the final state.Comment: 28 pages, 4 figures, 2 table
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