662 research outputs found

    Future Atmospheric Neutrino Detectors

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    Future experiments focusing on atmospheric neutrino detection are reviewed. One of the main goals of these experiments is the detection of an unambiguous oscillation pattern (nu_mu reappearance) to prove the oscillation hypothesis. Further goals include the discrimination of nu_mu - nu_tau and nu_mu - nu_sterile oscillations, and the detection of a potential small nu_mu - nu_e contribution. The search for matter effects in three or more flavour oscillations can be used to constrain hybrid oscillation models and potentially measure the sign of delta m^2. The detectors and measurement techniques proposed to achieve these goals are described, and their physics reach is discussed.Comment: 9 pages, invited talk at the XIX International Conference on Neutrino Physics and Astrophysics, Sudbury, Canada, June 16-21, 2000, to appear in Nucl. Phys. B (Proc. Suppl.

    Efficient Replication of Over 180 Genetic Associations with Self-Reported Medical Data

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    While the cost and speed of generating genomic data have come down dramatically in recent years, the slow pace of collecting medical data for large cohorts continues to hamper genetic research. Here we evaluate a novel online framework for amassing large amounts of medical information in a recontactable cohort by assessing our ability to replicate genetic associations using these data. Using web-based questionnaires, we gathered self-reported data on 50 medical phenotypes from a generally unselected cohort of over 20,000 genotyped individuals. Of a list of genetic associations curated by NHGRI, we successfully replicated about 75% of the associations that we expected to (based on the number of cases in our cohort and reported odds ratios, and excluding a set of associations with contradictory published evidence). Altogether we replicated over 180 previously reported associations, including many for type 2 diabetes, prostate cancer, cholesterol levels, and multiple sclerosis. We found significant variation across categories of conditions in the percentage of expected associations that we were able to replicate, which may reflect systematic inflation of the effects in some initial reports, or differences across diseases in the likelihood of misdiagnosis or misreport. We also demonstrated that we could improve replication success by taking advantage of our recontactable cohort, offering more in-depth questions to refine self-reported diagnoses. Our data suggests that online collection of self-reported data in a recontactable cohort may be a viable method for both broad and deep phenotyping in large populations

    Linfomas primários do estômago: casuística e discussão

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    Os autores relatam sua experiência com linfomas primários do estômago, revisando os casos assistidos no Hospital Santa Rita da Irmandade da Santa Casa de Misericórdia de Porto Alegre, ao curso de uma década. A despeito de se constituir em patologia de baixa incidência, ajuntaram, por denomada lida, em Serviço de Referência em Câncer, oito casos de linfomas gástricos e um de pseudolinfoma. Exibem os singulares aspectos clínicos, semiológicos e terapêuticos desta neoplasia, discernindo, particularmente, o seguimento daqueles pacientes

    Recoilless resonant neutrino capture and basics of neutrino oscillations

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    It is shown that the experiment on recoilless resonant emission and absorption of νˉe\bar \nu_{e}, proposed recently by Raghavan, could have an important impact on our understanding of the physics of neutrino oscillations.Comment: Additional information in the last chapte

    Observation of prompt single muons and of missing energy associated with μ+μ\mu^{+}\mu^{-} pairs produced in hadronic interactions

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    In a study of interactions of 400 GeV protons in a totally absorbing iron calorimeter the authors report two observations indicating the hadronic production of heavy short-lived weakly decaying particles. First they have observed a prompt muon signal in the region .8<p/sub t /<2.5 GeV/c. The rate is comparable in magnitude to the prompt 2 mu rate in the same kinematic region. In addition to detecting mu /sup +/ mu /sup -/ events arising from electromagnetic sources (e.g. rho to mu /sup +/ mu /sup -/, psi to mu /sup +/ mu /sup -/ etc.) they have observed mu /sup +/ mu /sup -/ pairs associated with a significant amount of missing energy indicative of final state neutrinos. Interpreting these data as production of DD pairs followed by single or double muonic decays leads to a model dependent estimate of total production cross-section of order 15 mu b. (14 refs)

    Neutrino oscillation parameters from MINOS, ICARUS and OPERA combined

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    We perform a detailed analysis of the capabilities of the MINOS, ICARUS and OPERA experiments to measure neutrino oscillation parameters at the atmospheric scale with their data taken separately and in combination. MINOS will determine Δm322\Delta m^2_{32} and sin22θ23\sin^2 2\theta_{23} to within 10% at the 99% C.L. with 10 kton-years of data. While no one experiment will determine sin22θ13\sin^2 2\theta_{13} with much precision, if its value lies in the combined sensitivity region of the three experiments, it will be possible to place a lower bound of O(0.01) at the 95% C.L. on this parameter by combining the data from the three experiments. The same bound can be placed with a combination of MINOS and ICARUS data alone.Comment: Version to appear in PR

    A Compact Beam Stop for a Rare Kaon Decay Experiment

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    We describe the development and testing of a novel beam stop for use in a rare kaon decay experiment at the Brookhaven AGS. The beam stop is located inside a dipole spectrometer magnet in close proximity to straw drift chambers and intercepts a high-intensity neutral hadron beam. The design process, involving both Monte Carlo simulations and beam tests of alternative beam-stop shielding arrangements, had the goal of minimizing the leakage of particles from the beam stop and the resulting hit rates in detectors, while preserving maximum acceptance for events of interest. The beam tests consisted of measurements of rates in drift chambers, scintilation counter hodoscopes, a gas threshold Cherenkov counter, and a lead glass array. Measurements were also made with a set of specialized detectors which were sensitive to low-energy neutrons, photons, and charged particles. Comparisons are made between these measurements and a detailed Monte Carlo simulation.Comment: 39 pages, 14 figures, submitted to Nuclear Instruments and Method
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