729 research outputs found

    Tuberculosis in pregnancy and adverse neonatal outcomes in two peruvian hospitals

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    Background: According to the World Health Organization, tuberculosis (TB) ranks among the top 10 causes of death worldwide. The significance of TB during pregnancy lies in its symptoms, which can be mistaken for physiological changes associated with pregnancy. This confusion can lead to maternal-perinatal complications. Objective: To evaluate the association between pulmonary TB in pregnancy and adverse neonatal outcomes in two Peruvian hospitals. Methods: This is a retrospective cohort study. The target population consisted of pregnant women with and without pulmonary TB whose deliveries were attended at two public hospitals, located in Lima, Peru. The adverse neonatal outcomes were prematurity, low birth weight (LBW), and being small for gestational age (SGA). Crude and adjusted relative risks (RRa) were calculated with their respective 95% confidence intervals (95%CI). Results: Information from 212 patients was analyzed; 48.1% had TB during pregnancy, and 23.1% had adverse neonatal outcomes (8%, 11.3%, and 12.3% for LBW, prematurity, and SGA, respectively). In the adjusted model, pregnant women with pulmonary TB had a 3.52 times higher risk of having a newborn with at least one of the adverse outcomes than those who were not exposed (aRR, 3.52; 95%CI: 1.93–6.68). Conclusion: Pulmonary TB in pregnancy was jointly and independently associated with adverse neonatal outcomes, including LBW, prematurity, and being SGA

    Neutrino Halos in Clusters of Galaxies and their Weak Lensing Signature

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    We study whether non-linear gravitational effects of relic neutrinos on the development of clustering and large-scale structure may be observable by weak gravitational lensing. We compute the density profile of relic massive neutrinos in a spherical model of a cluster of galaxies, for several neutrino mass schemes and cluster masses. Relic neutrinos add a small perturbation to the mass profile, making it more extended in the outer parts. In principle, this non-linear neutrino perturbation is detectable in an all-sky weak lensing survey such as EUCLID by averaging the shear profile of a large fraction of the visible massive clusters in the universe, or from its signature in the general weak lensing power spectrum or its cross-spectrum with galaxies. However, correctly modeling the distribution of mass in baryons and cold dark matter and suppressing any systematic errors to the accuracy required for detecting this neutrino perturbation is severely challenging.Comment: 13 pages, 11 figures. Submitted to JCA

    Solar Neutrinos Before and After KamLAND

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    We use the recently reported KamLAND measurements on oscillations of reactor anti-neutrinos, together with the data of previously reported solar neutrino experiments, to show that: (1) the total 8B neutrino flux emitted by the Sun is 1.00(1.0 \pm 0.06) of the standard solar model (BP00) predicted flux, (2) the KamLAND measurements reduce the area of the globally allowed oscillation regions that must be explored in model fitting by six orders of magnitude in the Delta m^2-tan^2 theta plane, (3) LMA is now the unique oscillation solution to a CL of 4.7sigma, (4) maximal mixing is disfavored at 3.1 sigma, (5) active-sterile admixtures are constrained to sin^2 eta<0.13 at 1 sigma, (6) the observed ^8B flux that is in the form of sterile neutrinos is 0.00^{+0.09}_{-0.00} (1 sigma), of the standard solar model (BP00) predicted flux, and (7) non-standard solar models that were invented to completely avoid solar neutrino oscillations are excluded by KamLAND plus solar at 7.9 sigma . We also refine quantitative predictions for future 7Be and p-p solar neutrino experiments.Comment: Published version, includes editorial improvement

    Immune response to SARS-CoV-2 variants after immunization with different vaccines in Mexico

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    There is limited information on the antibody responses against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in subjects from developing countries with populations having a high incidence of co-morbidities. Here, we analysed the immunogenicity of homologous schemes using the ChAdOx1-S, Sputnik V, or BNT162b2 vaccines and the effect of a booster dose with ChAdOx1-S in middle-aged adults who were seropositive or seronegative to the SARS-CoV-2 spike protein before vaccination. The study was conducted post-vaccination with a follow-up of 4 months for antibody titre using enzyme-linked immunosorbent assay (ELISA) and pseudovirus (PV) neutralization assays (PNAs). All three vaccines elicited a superior IgG anti-receptor-binding domain (RBD) and neutralization response against the Alpha and Delta variants when administered to individuals with a previous infection by SARS-CoV-2. The booster dose spiked the neutralization activity among individuals with and without a prior SARS-CoV-2 infection. The ChAdOx1-S vaccine induced weaker antibody responses in infection-naive subjects. A follow-up of 4 months post-vaccination showed a drop in antibody titre, with about 20% of the infection-naive and 100% of SARS-CoV-2 pre-exposed participants with detectable neutralization capacity against Alpha pseudovirus (Alpha-PV) and Delta PV (Delta-PV). Our observations support the use of different vaccines in a country with high seroprevalence at the vaccination time

    Solar models and solar neutrino oscillations

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    We provide a summary of the current knowledge, theoretical and experimental, of solar neutrino fluxes and of the masses and mixing angles that characterize solar neutrino oscillations. We also summarize the principal reasons for doing new solar neutrino experiments and what we think may be learned from the future measurements.Comment: Submitted to the Neutrino Focus Issue of New Journal of Physics at http://www.njp.or

    Robust signatures of solar neutrino oscillation solutions

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    With the goal of identifying signatures that select specific neutrino oscillation parameters, we test the robustness of global oscillation solutions that fit all the available solar and reactor experimental data. We use three global analysis strategies previously applied by different authors and also determine the sensitivity of the oscillation solutions to the critical nuclear fusion cross section, S_{17}(0), for the production of 8B. The favored solutions are LMA, LOW, and VAC in order of g.o.f. The neutral current to charged current ratio for SNO is predicted to be 3.5 +- 0.6 (1 sigma), which is separated from the no-oscillation value of 1.0 by much more than the expected experimental error. The predicted range of the day-night difference in charged current rates is (8.2 +- 5.2)% and is strongly correlated with the day-night effect for neutrino-electron scattering. A measurement by SNO of either a NC to CC ratio > 3.3 or a day-night difference > 10%, would favor a small region of the currently allowed LMA neutrino parameter space. The global oscillation solutions predict a 7Be neutrino-electron scattering rate in BOREXINO and KamLAND in the range 0.66 +- 0.04 of the BP00 standard solar model rate, a prediction which can be used to test both the solar model and the neutrino oscillation theory. Only the LOW solution predicts a large day-night effect(< 42%) in BOREXINO and KamLAND. For the KamLAND reactor experiment, the LMA solution predicts 0.44 of the standard model rate; we evaluate 1 sigma and 3 sigma uncertainties and the first and second moments of the energy spectrum.Comment: Included predictions for KamLAND reactor experiment and updated to include 1496 days of Super-Kamiokande observation

    Present and Future Bounds on Non-Standard Neutrino Interactions

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    We consider Non-Standard neutrino Interactions (NSI), described by four-fermion operators of the form (νˉαγνβ)(fˉγf)(\bar{\nu}_{\alpha} \gamma {\nu}_{\beta}) (\bar{f} \gamma f), where ff is an electron or first generation quark. We assume these operators are generated at dimension 8\geq 8, so the related vertices involving charged leptons, obtained by an SU(2) transformation νδeδ\nu_{\delta} \to e_{\delta}, do not appear at tree level. These related vertices necessarily arise at one loop, via WW exchange. We catalogue current constraints from sin2θW\sin^2 \theta_W measurements in neutrino scattering, from atmospheric neutrino observations, from LEP, and from bounds on the related charged lepton operators. We estimate future bounds from comparing KamLAND and solar neutrino data, and from measuring sin2θW\sin^2 \theta_W at the near detector of a neutrino factory. Operators constructed with νμ\nu_\mu and νe\nu_e should not confuse the determination of oscillation parameters at a ν\nufactory, because the processes we consider are more sensitive than oscillations at the far detector. For operators involving ντ\nu_\tau, we estimate similar sensitivities at the near and far detector.Comment: Erratum added at the end of the documen

    Analog gravity from field theory normal modes?

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    We demonstrate that the emergence of a curved spacetime ``effective Lorentzian geometry'' is a common and generic result of linearizing a field theory around some non-trivial background. This investigation is motivated by considering the large number of ``analog models'' of general relativity that have recently been developed based on condensed matter physics, and asking whether there is something more fundamental going on. Indeed, linearization of a classical field theory (a field theoretic ``normal mode analysis'') results in fluctuations whose propagation is governed by a Lorentzian-signature curved spacetime ``effective metric''. For a single scalar field, this procedure results in a unique effective metric, which is quite sufficient for simulating kinematic aspects of general relativity (up to and including Hawking radiation). Quantizing the linearized fluctuations, the one-loop effective action contains a term proportional to the Einstein--Hilbert action, suggesting that while classical physics is responsible for generating an ``effective geometry'', quantum physics can be argued to induce an ``effective dynamics''. The situation is strongly reminiscent of Sakharov's ``induced gravity'' scenario, and suggests that Einstein gravity is an emergent low-energy long-distance phenomenon that is insensitive to the details of the high-energy short-distance physics. (We mean this in the same sense that hydrodynamics is a long-distance emergent phenomenon, many of whose predictions are insensitive to the short-distance cutoff implicit in molecular dynamics.)Comment: Revtex 4 (beta 5); 12 pages in single-column forma

    Three-Neutrino Mixing after the First Results from K2K and KamLAND

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    We analyze the impact of the data on long baseline \nu_\mu disappearance from the K2K experiment and reactor \bar\nu_e disappearance from the KamLAND experiment on the determination of the leptonic three-generation mixing parameters. Performing an up-to-date global analysis of solar, atmospheric, reactor and long baseline neutrino data in the context of three-neutrino oscillations, we determine the presently allowed ranges of masses and mixing and we consistently derive the allowed magnitude of the elements of the leptonic mixing matrix. We also quantify the maximum allowed contribution of \Delta m^2_{21} oscillations to CP-odd and CP-even observables at future long baseline experiments.Comment: Some typos correcte

    Phenomenology of Maximal and Near-Maximal Lepton Mixing

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    We study the phenomenological consequences of maximal and near-maximal mixing of the electron neutrino with other (xx=tau and/or muon) neutrinos. We describe the deviations from maximal mixing in terms of a parameter ϵ12sin2θex\epsilon\equiv1-2\sin^2\theta_{ex} and quantify the present experimental status for ϵ<0.3|\epsilon|<0.3. We find that the global analysis of solar neutrino data allows maximal mixing with confidence level better than 99% for 10810^{-8} eV^2\lsim\Delta m^2\lsim2\times10^{-7} eV2^2. In the mass ranges \Delta m^2\gsim 1.5\times10^{-5} eV2^2 and 4×10104\times10^{-10} eV^2\lsim\Delta m^2\lsim2\times10^{-7} eV2^2 the full interval ϵ<0.3|\epsilon|<0.3 is allowed within 4σ\sigma(99.995 % CL). We suggest ways to measure ϵ\epsilon in future experiments. The observable that is most sensitive to ϵ\epsilon is the rate [NC]/[CC] in combination with the Day-Night asymmetry in the SNO detector. With theoretical and statistical uncertainties, the expected accuracy after 5 years is Δϵ0.07\Delta \epsilon\sim 0.07. We also discuss the effects of maximal and near-maximal νe\nu_e-mixing in atmospheric neutrinos, supernova neutrinos, and neutrinoless double beta decay.Comment: 49 pages Latex file using RevTeX. 16 postscript figures included. ( Fig.2 and Fig.4 bitmapped for compression,better resolution at http://ific.uv.es/~pppac/). Improved presentation: some statements included and labels added in figures. Some misprint corrected. Final version to appear in Phys. Rev D. Report no: IFIC/00-40, IASSNS-HEP-00-5
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