1,378 research outputs found

    Search for long-lived massive particles in extensive air showers

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    Air showers containing delayed sub-showers which may be produced by a long-lived massive particle have been investigated by using twelve detectors. Ten events have been selected out as the candidates. However, a definite conclusion cannot be reached at the present time

    Generic phase diagram of "electron-doped" T' cuprates

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    We investigated the generic phase diagram of the electron doped superconductor, Nd2-xCexCuO4, using films prepared by metal organic decomposition. After careful oxygen reduction treatment to remove interstitial Oap atoms, we found that the Tc increases monotonically from 24 K to 29 K with decreasing x from 0.15 to 0.00, demonstrating a quite different phase diagram from the previous bulk one. The implication of our results is discussed on the basis of tremendous influence of Oap "impurities" on superconductivity and also magnetism in T' cuprates. Then we conclude that our result represents the generic phase diagram for oxygen-stoichiometric Nd2-xCexCuO4.Comment: 12 pages, 4 figures; International Symposium on Superconductivity (ISS) 200

    Destabilization of the thermohaline circulation by transient perturbations to the hydrological cycle

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    We reconsider the problem of the stability of the thermohaline circulation as described by a two-dimensional Boussinesq model with mixed boundary conditions. We determine how the stability properties of the system depend on the intensity of the hydrological cycle. We define a two-dimensional parameters' space descriptive of the hydrology of the system and determine, by considering suitable quasi-static perturbations, a bounded region where multiple equilibria of the system are realized. We then focus on how the response of the system to finite-amplitude surface freshwater forcings depends on their rate of increase. We show that it is possible to define a robust separation between slow and fast regimes of forcing. Such separation is obtained by singling out an estimate of the critical growth rate for the anomalous forcing, which can be related to the characteristic advective time scale of the system.Comment: 37 pages, 8 figures, submitted to Clim. Dy

    Pericardial Fat Thickness Increases with Greater Burden of Adverse Metabolic Factors Among Adults with Normal-Range Body Mass Index: The Framingham Heart Study

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    Introduction: Greater burden of pericardial fat is associated with increased body mass index (BMI). Obesity is associated with unfavorable metabolic characteristics such as hypertension, dyslipidemia, and glucose intolerance. We sought to determine whether unfavorable metabolic profile alone, in the absence of excess BMI, was itself associated with increased pericardial fat thickness (PFT). Methods:From the 1,794 Framingham Offspring cohort adults who underwent cardiac magnetic resonance (CMR), we identified 446 free of non-skin cancer and prevalent clinical cardiovascular disease (CVD) who had 18.5‚ȧBMI2and complete covariates. We calculated a metabolic score (MS) based on ATPIII criteria where 1 point was assigned for each of: a) fasting glucose‚Č•100 mg/dL or diabetes; b) SBP‚Č•130 or DBP‚Č•85 mmHg or antihypertensive treatment; c) triglycerides‚Č•150 mg/dL; d) HDL cholesterol \u3c40(M)/ Results: PFT increased with worsening metabolic score at the fixed locations of the apical and mid-level RV, as well as at maximal PFT. On pairwise comparisons, only the MS3+ group had PFT that was consistently significantly greater than that of MS0. Conclusions: In a community-dwelling cohort, among participants who were free of cancer and clinical CVD and had normal-range or BMI, worsening metabolic profile was associated with increased pericardial fat thickness

    Using the past to constrain the future: how the palaeorecord can improve estimates of global warming

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    Climate sensitivity is defined as the change in global mean equilibrium temperature after a doubling of atmospheric CO2 concentration and provides a simple measure of global warming. An early estimate of climate sensitivity, 1.5-4.5{\deg}C, has changed little subsequently, including the latest assessment by the Intergovernmental Panel on Climate Change. The persistence of such large uncertainties in this simple measure casts doubt on our understanding of the mechanisms of climate change and our ability to predict the response of the climate system to future perturbations. This has motivated continued attempts to constrain the range with climate data, alone or in conjunction with models. The majority of studies use data from the instrumental period (post-1850) but recent work has made use of information about the large climate changes experienced in the geological past. In this review, we first outline approaches that estimate climate sensitivity using instrumental climate observations and then summarise attempts to use the record of climate change on geological timescales. We examine the limitations of these studies and suggest ways in which the power of the palaeoclimate record could be better used to reduce uncertainties in our predictions of climate sensitivity.Comment: The final, definitive version of this paper has been published in Progress in Physical Geography, 31(5), 2007 by SAGE Publications Ltd, All rights reserved. \c{opyright} 2007 Edwards, Crucifix and Harriso

    High energy product in Battenberg structured magnets

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    PublishedJournal Article© 2014 AIP Publishing LLC. Multiphase nano-structured permanent magnets show a high thermal stability of remanence and a high energy product while the amount of rare-earth elements is reduced. Non-zero temperature micromagnetic simulations show that a temperature coefficient of remanence of -0.073%/K and that an energy product greater than 400 kJ/m3 can be achieved at a temperature of 450 K in a magnet containing around 40 volume percent Fe65Co35 embedded in a hard magnetic matrix

    Influence of defect thickness on the angular dependence of coercivity in rare-earth permanent magnets

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    This is the final version of the article. Available from the American Institute of Physics via the DOI in this record.The coercive field and angular dependence of the coercive field of single-grain Nd2_{2}Fe14_{14}B permanent magnets are computed using finite element micromagnetics. It is shown that the thickness of surface defects plays a critical role in determining the reversal process. For small defect thicknesses reversal is heavily driven by nucleation, whereas with increasing defect thickness domain wall de-pinning becomes more important. This change results in an observable shift between two well-known behavioral models. A similar trend is observed in experimental measurements of bulk samples, where a Nd-Cu infiltration process has been used to enhance coercivity by modifying the grain boundaries. When account is taken of the imperfect grain alignment of real magnets, the single-grain computed results appears to closely match experimental behaviour.We acknowledge the financial support from the Technology Research Association of Magnetic Materials for High Efficient Motors (MagHEM)
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