1,604 research outputs found

    High Energy Cosmic Rays from Neutrinos

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    We discuss recent models in which neutrinos, which are assumed to have mass in the eV range, originate the highest energy cosmic rays by interaction with the enhanced density in the galactic halo of the relic cosmic neutrino background. We make an analytical calculation of the required neutrino fluxes to show that the parameter space for these models is constrained by horizontal air shower searches and by the total number of background neutrinos, so that only models which have fairly unnatural halo sizes and enhanced densities are allowed.Comment: 14 pages, 3 ps figures. To appear in Phys. Rev.

    Increasing trend in the prevalence of morbid obesity in Spain: from 1.8 to 6.1 per thousand in 14 years

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    Obesity, and especiallymorbid obesity, increases the risk of cardiovascular as well as non-cardiovascular diseases. Our objective was to ascertain the trends in morbid obesity in Spain from 1993 to 2006 using representative data from 106,048 participants in the National Health Surveys. An age-adjusted Poisson regression model stratified by sex was fitted using morbid obesity as the dependent variable. An increasing trend in prevalent morbid obesity from 1.8 to 6.1 per thousand participants was found (increase > 200%). Morbid obesity prevalence was higher in women. After adjusting for age, a monotonically increasing prevalence of morbid obesity was apparent for both men and women: the relative increase was 4% per year in women and 12% per year in men. These trends highlight the importance of preventive actions

    Validation of metabolic syndrome using medical records in the SUN cohort

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    The objective of this study was to evaluate the validity of self reported criteria of Metabolic Syndrome (MS) in the SUN (Seguimiento Universidad de Navarra) cohort using their medical records as the gold standard. METHODS: We selected 336 participants and we obtained MS related data according to Adult Treatment Panel III (ATP III) and International Diabetes Federation (IDF). Then we compared information on the self reported diagnosis of MS and MS diagnosed in their medical records. We calculated the proportion of confirmed MS, the proportion of confirmed non-MS and the intraclass correlation coefficients for each component of the MS. RESULTS: From those 336 selected participants, we obtained sufficient data in 172 participants to confirm or reject MS using ATP III criteria. The proportion of confirmed MS was 91.2% (95% CI: 80.7- 97.1) and the proportion of confirmed non-MS was 92.2% (95% CI: 85.7-96.4) using ATP III criteria. The proportion of confirmed MS using IDF criteria was 100% (95% CI: 87.2-100) and the proportion of confirmed non-MS was 97.1% (95% CI: 85.1-99.9). Kappa Index was 0.82 in the group diagnosed by ATP III criteria and 0.97 in the group diagnosed by IDF criteria. Intraclass correlation coefficients for the different component of MS were: 0.93 (IC 95%:0.91- 0.95) for BMI; 0.96 (IC 95%: 0.93-0.98) for waist circumference; 0.75 (IC 95%: 0.66-0.82) for fasting glucose; 0.50 (IC 95%:0.35-0.639) for HDL cholesterol; 0.78 (IC 95%: 0.70-0.84) for triglycerides; 0.49 (IC 95%:0.34-0.61) for systolic blood pressure and 0.55 (IC 95%: 0.41-0.65) for diastolic blood pressure. CONCLUSIONS: Self-reported MS based on self reported components of the SM in a Spanish cohort of university graduates was sufficiently valid as to be used in epidemiological studies

    Optimization of the design of OMNIS, the observatory of multiflavor neutrinos from supernovae

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    A Monte Carlo code has been developed to simulate the operation of the planned detectors in OMNIS, a supernova neutrino observatory. OMNIS will detect neutrinos originating from a core collapse supernova by the detection of spalled neutrons from Pb- or Fe-nuclei. This might be accomplished using Gd-loaded liquid scintillator. Results for the optimum configuration for such modules with respect to both neutron detection efficiency and cost efficiency are presented. Careful consideration has been given to the expected levels of radioactive backgrounds and their effects. The results show that the amount of data to be processed by a software trigger can be reduced to the <10kHz region and a neutron, once produced in the detector, can be detected and identified with an efficiency of >30%.Comment: Elsevier preprint; 29 pages, 23 figure

    Staff training influence on non-invasive ventilation outcome for acute hypercapnic respiratory failure

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    Background. Although non-invasive ventilation (NIV) efficacy in the treatment of acute hypercapnic respiratory failure (AHRF) have been previously demonstrated, not all the studies reveal this fact in the same degree, with some variability in the results. This study aimed to analyse variables related to NIV outcome for AHRF. Methods. A group of consecutive patients requiring NIV due to AHRF were included in a prospective observational cohort study performed in conventional wards. Variables considered included those reported in the literature, as well as staff problems during the management of the ventilators. The study aimed to include all patients during one year, but after the initial results, it had to be suspended. Results. Fifteen patients were included in the study: 10 males, mean age 68 ± 12. APACHE-II score was 17.6 ± 6.5. pH and pCO2 before NIV were 7.22 ± 0.11 and 110 ± 72 mmHg respectively. pH, corticosteroids use, APACHE score, and EPAP were found to influence outcome. Besides, an inadequate use of NIV due to lack of personnel training was detected in all patients with NIV failure (RR 3.5; 95% CI: 1.08-11.2; p = 0.007). In the light of these results, the study had to be suspended and patients were transferred to the respiratory ward. Conclusions. NIV is a life-saving respiratory treatment influenced by several factors, of which staff training is a key one. Centres attending acute respiratory patients should have an area in which this requirement is fulfilled

    Status of four-neutrino mass schemes: a global and unified approach to current neutrino oscillation data

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    We present a unified global analysis of neutrino oscillation data within the framework of the four-neutrino mass schemes (3+1) and (2+2). We include all data from solar and atmospheric neutrino experiments, as well as information from short-baseline experiments including LSND. If we combine only solar and atmospheric neutrino data, (3+1) schemes are clearly preferred, whereas short-baseline data in combination with atmospheric data prefers (2+2) models. When combining all data in a global analysis the (3+1) mass scheme gives a slightly better fit than the (2+2) case, though all four-neutrino schemes are presently acceptable. The LSND result disfavors the three-active neutrino scenario with only Δmsol2\Delta m^2_{sol} and Δmatm2\Delta m^2_{atm} at 99.9% CL with respect to the four-neutrino best fit model. We perform a detailed analysis of the goodness of fit to identify which sub-set of the data is in disagreement with the best fit solution in a given mass scheme.Comment: 32 pages, 8 Figures included, REVTeX4.Improved discussion in sec. XI, references added, version accepted by Phys. Rev.

    The effect of spontaneous collapses on neutrino oscillations

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    We compute the effect of collapse models on neutrino oscillations. The effect of the collapse is to modify the evolution of the `spatial' part of the wave function, which indirectly amounts to a change on the flavor components. In many respects, this phenomenon is similar to neutrino propagation through matter. For the analysis we use the mass proportional CSL model, and perform the calculation to second order perturbation theory. As we will show, the CSL prediction is very small - mainly due to the very small mass of neutrinos - and practically undetectable.Comment: 24 pages, RevTeX. Updated versio

    Three Generation Neutrino Oscillation Parameters after SNO

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    We examine the solar neutrino problem in the context of the realistic three neutrino mixing scenario including the SNO charged current (CC) rate. The two independent mass squared differences Δm212\Delta m^2_{21} and Δm312Δm322\Delta m^2_{31} \approx \Delta m^2_{32} are taken to be in the solar and atmospheric ranges respectively. We incorporate the constraints on Δ\Deltam312^2_{31} as obtained by the SuperKamiokande atmospheric neutrino data and determine the allowed values of Δm212\Delta m^2_{21}, θ12\theta_{12} and θ13\theta_{13} from a combined analysis of solar and CHOOZ data. Our aim is to probe the changes in the values of the mass and mixing parameters with the inclusion of the SNO data as well as the changes in the two-generation parameter region obtained from the solar neutrino analysis with the inclusion of the third generation. We find that the inclusion of the SNO CC rate in the combined solar + CHOOZ analysis puts a more restrictive bound on θ13\theta_{13}. Since the allowed values of θ13\theta_{13} are constrained to very small values by the CHOOZ experiment there is no qualitative change over the two generation allowed regions in the Δm212tan2θ12\Delta m^2_{21} - \tan^2 \theta_{12} plane. The best-fit comes in the LMA region and no allowed area is obtained in the SMA region at 3σ\sigma level from combined solar and CHOOZ analysis.Comment: One reference added. Version to apprear in PR
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