598 research outputs found

    Beta decay of 115-In to the first excited level of 115-Sn: Potential outcome for neutrino mass

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    Recent observation of beta decay of 115-In to the first excited level of 115-Sn with an extremely low Q_beta value (Q_beta ~ 1 keV) could be used to set a limit on neutrino mass. To give restriction potentially competitive with those extracted from experiments with 3-H (~2 eV) and 187-Re (~15 eV), atomic mass difference between 115-In and 115-Sn and energy of the first 115-Sn level should be remeasured with higher accuracy (possibly of the order of ~1 eV).Comment: 9 pages, 3 figures; talk at the NANP'05 Conferenc

    On the New Conditions for a Total Neutrino Conversion in a Medium

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    We show that the arguments forming the basis for the claim that the conditions for total neutrino conversion derived and studied in detail in [1,2] ``are just the conditions of the parametric resonance of neutrino oscillations supplemented by the requirement that the parametric enhancement be complete'', given in [4] have flaws which make the claim physically questionable. We show also that in the case of the transitions in the Earth of the Earth-core-crossing solar and atmospheric neutrinos the peaks in the relevant transitions probabilities PabP_{a b}, associated with the new conditions, maxPab=1max P_{a b} = 1, are of physical relevance - in contrast to what is suggested in [4]. Actually, the enhancement of PabP_{a b} in any region of the corresponding parameter space are essentially determined by these absolute maxima of PabP_{a b}. We comment on few other aspects of the results derived in [1,2,3] which have been misunderstood and/or misinterpreted in [4].Comment: 8 pages, late

    The NuMI Neutrino Beam and Potential for an Off-Axis Experiment

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    The Neutrinos at the Main Injector (NuMI) facility at Fermilab is under construction and due to begin operations in late 2004. NuMI will deliver an intense νμ\nu_{\mu} beam of variable energy 2-20 GeV directed into the Earth at 58 mrad. Several aspects of the design are reviewed, and potential limitations to the ultimate neutrino flux are described. In addition, potential measurements of neutrino mixing properties are described.Comment: talk given at NuFact '02, Imperial College London, proceedings to appear in J. Phys. G, revised to add a referenc

    Transcatheter Aortic Valve Implantation in Dialysis Patients

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    Background/Aims: Transcatheter aortic valve implantation (TAVI) has emerged as a new therapeutic option for high-risk patients. However, dialysis patients were excluded from all previous studies. The aim of this study is to compare the outcomes of TAVI for dialysis patients with those for patients with chronic kidney disease (CKD) stages 3 and 4 and to compare TAVI with open surgery in dialysis patients. Methods: Part I: comparison of 10 patients on chronic hemodialysis with 116 patients with non-dialysis-dependent CKD undergoing TAVI. Part II: comparison of transcatheter (n = 15) with open surgical (n = 24) aortic valve replacement in dialysis patients. Results: Part I: dialysis patients were significantly younger (72.3 vs. 82.0 years; p < 0.01). Hospital stay was significantly longer in dialysis patients (21.8 vs. 12.1 days; p = 0.01). Overall 30-day mortality was 3.17%, with no deaths among dialysis patients. Six-month survival rates were similar (log-rank p = 0.935). Part II: patient age was comparable (66.5 vs. 69.5 years; p = 0.42). Patients in the surgical group tended to stay longer in hospital than TAVI patients (29.5 vs. 22.5 days; p = 0.35). Conclusion: TAVI is a safe procedure in patients on chronic hemodialysis. Until new data become available, we find no compelling reason to refuse these patients TAVI. Copyright (C) 2012 S. Karger AG, Base

    Measurement of the Solar Neutrino Capture Rate by the Russian-American Gallium Solar Neutrino Experiment During One Half of the 22-Year Cycle of Solar Activity

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    We present the results of measurements of the solar neutrino capture rate in gallium metal by the Russian-American Gallium Experiment SAGE during slightly more than half of a 22-year cycle of solar activity. Combined analysis of the data of 92 runs during the 12-year period January 1990 through December 2001 gives a capture rate of solar neutrinos with energy more than 233 keV of 70.8 +5.3/-5.2 (stat.) +3.7/-3.2 (syst.) SNU. This represents only slightly more than half of the predicted standard solar model rate of 128 SNU. We give the results of new runs beginning in April 1998 and the results of combined analysis of all runs since 1990 during yearly, monthly, and bimonthly periods. Using a simple analysis of the SAGE results combined with those from all other solar neutrino experiments, we estimate the electron neutrino pp flux that reaches the Earth to be (4.6 +/- 1.1) E10/(cm^2-s). Assuming that neutrinos oscillate to active flavors the pp neutrino flux emitted in the solar fusion reaction is approximately (7.7 +/- 1.8) E10/(cm^2-s), in agreement with the standard solar model calculation of (5.95 +/- 0.06) E10/(cm^2-s).Comment: English translation of article submitted to Russian journal Zh. Eksp. Teor. Fiz. (JETP); 12 pages, 5 figures. V2: Added winter-summer difference and 2 reference

    Safety of percutaneous aortic valve insertion. A systematic review

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    <p>Abstract</p> <p>Background</p> <p>The technique of percutaneous aortic valve implantation (PAVI) for the treatment of severe aortic stenosis (AS) has been introduced in 2002. Since then, many thousands such devices have worldwide been implanted in patients at high risk for conventional surgery. The procedure related mortality associated with PAVI as reported in published case series is substantial, although the intervention has never been formally compared with standard surgery. The objective of this study was to assess the safety of PAVI, and to compare it with published data reporting the risk associated with conventional aortic valve replacement in high-risk subjects.</p> <p>Methods</p> <p>Studies published in peer reviewed journals and presented at international meetings were searched in major medical databases. Further data were obtained from dedicated websites and through contacts with manufacturers. The following data were extracted: patient characteristics, success rate of valve insertion, operative risk status, early and late all-cause mortality.</p> <p>Results</p> <p>The first PAVI has been performed in 2002. Because of procedural complexity, the original transvenous approach from 2004 on has been replaced by the transarterial and transapical routes. Data originating from nearly 2700 non-transvenous PAVIs were identified. In order to reduce the impact of technical refinements and the procedural learning curve, procedure related safety data from series starting recruitment in April 2007 or later (n = 1975) were focused on. One-month mortality rates range from 6.4 to 7.4% in transfemoral (TF) and 11.6 to 18.6% in transapical (TA) series. Observational data from surgical series in patients with a comparable predicted operative risk, indicate mortality rates that are similar to those in TF PAVI but substantially lower than in TA PAVI. From all identified PAVI series, 6-month mortality rates, reflecting both procedural risk and mortality related to underlying co-morbidities, range from 10.0-25.0% in TF and 26.1-42.8% in TA series. It is not known what the survival of these patients would have been, had they been treated medically or by conventional surgery.</p> <p>Conclusion</p> <p>Safety issues and short-term survival represent a major drawback for the implementation of PAVI, especially for the TA approach. Results from an ongoing randomised controlled trial (RCT) should be awaited before further using this technique in routine clinical practice. In the meantime, both for safety concerns and for ethical reasons, patients should only be subjected to PAVI within the boundaries of such an RCT.</p

    Implications of New Gallex Results for the MSW Solution of the Solar Neutrino Problem

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    We compare the implications for 7Be and pp neutrinos of the two MSW fits to the new GALLEX solar neutrino measurements . Small mixing angle solutions tend to suppress the former as electron-neutrinos, but not the latter, and large angle solutions tend to reduce both by about a factor of 2. The consequences for BOREXINO and similar solar neutrino--electron scattering experiments are discussed.Comment: 7 pages (plus 3 figures available upon request) UTAPHY-HEP-

    White paper: CeLAND - Investigation of the reactor antineutrino anomaly with an intense 144Ce-144Pr antineutrino source in KamLAND

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    We propose to test for short baseline neutrino oscillations, implied by the recent reevaluation of the reactor antineutrino flux and by anomalous results from the gallium solar neutrino detectors. The test will consist of producing a 75 kCi 144Ce - 144Pr antineutrino source to be deployed in the Kamioka Liquid Scintillator Anti-Neutrino Detector (KamLAND). KamLAND's 13m diameter target volume provides a suitable environment to measure energy and position dependence of the detected neutrino flux. A characteristic oscillation pattern would be visible for a baseline of about 10 m or less, providing a very clean signal of neutrino disappearance into a yet-unknown, "sterile" state. Such a measurement will be free of any reactor-related uncertainties. After 1.5 years of data taking the Reactor Antineutrino Anomaly parameter space will be tested at > 95% C.L.Comment: White paper prepared for Snowmass-2013; slightly different author lis

    CeLAND: search for a 4th light neutrino state with a 3 PBq 144Ce-144Pr electron antineutrino generator in KamLAND

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    The reactor neutrino and gallium anomalies can be tested with a 3-4 PBq (75-100 kCi scale) 144Ce-144Pr antineutrino beta-source deployed at the center or next to a large low-background liquid scintillator detector. The antineutrino generator will be produced by the Russian reprocessing plant PA Mayak as early as 2014, transported to Japan, and deployed in the Kamioka Liquid Scintillator Anti-Neutrino Detector (KamLAND) as early as 2015. KamLAND's 13 m diameter target volume provides a suitable environment to measure the energy and position dependence of the detected neutrino flux. A characteristic oscillation pattern would be visible for a baseline of about 10 m or less, providing a very clean signal of neutrino disappearance into a yet-unknown, sterile neutrino state. This will provide a comprehensive test of the electron dissaperance neutrino anomalies and could lead to the discovery of a 4th neutrino state for Delta_m^2 > 0.1 eV^2 and sin^2(2theta) > 0.05.Comment: 67 pages, 50 figures. Th. Lasserre thanks the European Research Council for support under the Starting Grant StG-30718
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