597 research outputs found

    Possible Superconductivity at 37 K in Graphite-Sulfur Composite

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    Sulfur intercalated graphite composites with diamagnetic transitions at 6.7 K and 37 K are prepared. The magnetization hysteresis loops (MHL), Xray diffraction patterns, and resistance were measured. From the MHL, a slight superconducting like penetration process is observed at 15 K in low field region. The XRD shows no big difference from the mixture of graphite and sulfur indicating that the volume of the superconducting phase (if any) is very small. The temperature dependence of resistance shows a typical semiconducting behavior with a saturation in low temperature region. This saturation is either induced by the de-localization of conducting electrons or by possible superconductivity in this system.Comment: CHIN. PHYS.LETT v18 1648 (2001

    Survivorship care for older adults with cancer: U13 conference report

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    Older adult cancer survivors currently account for almost 60% of all cancer survivors. The number of older cancer survivors will continue to increase as the population ages and as patients’ live longer after a cancer diagnosis. As part of cancer center accreditation, the American College of Surgeons Commission on Cancer¼ (CoC) has placed great importance on survivorship care planning. While the CoC has set standards for general survivorship care, there is sparse evidence on how to best care for older adult cancer survivors. Concern exists among the medical community that survivorship care plans could increase paperwork without improving outcomes. Given the diverse and unique needs of older adult cancer survivors, the inter-professional team provides a structure and process for survivorship care built around the particular needs of older adults. The Cancer and Aging Research Group (CARG), in partnership with the NIA/NCI, held a U13 conference in May 2015 in part to discuss survivorship care for older adults with cancer. This report discusses four themes that emerged from one section of the conference: (1) survivorship care is a process that continually evolves to meet the needs of older adults; (2) older adult cancer survivors have unique needs and care plans should be tailored to meet these needs; (3) the inter-professional team is ideally suited to structure survivorship care of older adults; (4) patient advocacy must be encouraged throughout the cancer care continuum. As evidence based survivorship practices develop, the unique needs of older adults need to be given substantial attention

    A comparison of transgenic rodent mutation and in vivo comet assay responses for 91 chemicals.

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    A database of 91 chemicals with published data from both transgenic rodent mutation (TGR) and rodent comet assays has been compiled. The objective was to compare the sensitivity of the two assays for detecting genotoxicity. Critical aspects of study design and results were tabulated for each dataset. There were fewer datasets from rats than mice, particularly for the TGR assay, and therefore, results from both species were combined for further analysis. TGR and comet responses were compared in liver and bone marrow (the most commonly studied tissues), and in stomach and colon evaluated either separately or in combination with other GI tract segments. Overall positive, negative, or equivocal test results were assessed for each chemical across the tissues examined in the TGR and comet assays using two approaches: 1) overall calls based on weight of evidence (WoE) and expert judgement, and 2) curation of the data based on a priori acceptability criteria prior to deriving final tissue specific calls. Since the database contains a high prevalence of positive results, overall agreement between the assays was determined using statistics adjusted for prevalence (using AC1 and PABAK). These coefficients showed fair or moderate to good agreement for liver and the GI tract (predominantly stomach and colon data) using WoE, reduced agreement for stomach and colon evaluated separately using data curation, and poor or no agreement for bone marrow using both the WoE and data curation approaches. Confidence in these results is higher for liver than for the other tissues, for which there were less data. Our analysis finds that comet and TGR generally identify the same compounds (mainly potent mutagens) as genotoxic in liver, stomach and colon, but not in bone marrow. However, the current database content precluded drawing assay concordance conclusions for weak mutagens and non-DNA reactive chemicals

    Determination of absolute neutrino masses from Z-bursts

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    Ultrahigh energy neutrinos (UHE\nu) scatter on relic neutrinos (R\nu) producing Z bosons, which can decay hadronically producing protons (Z-burst). We compare the predicted proton spectrum with the observed ultrahigh energy cosmic ray (UHECR) spectrum and determine the mass of the heaviest R\nu via a maximum likelihood analysis. Our prediction depends on the origin of the power-like part of the UHECR spectrum: m_\nu=2.75^{+1.28}_{-0.97} eV for Galactic halo and 0.26^{+0.20}_{-0.14} eV for extragalactic (EG) origin. The necessary UHE\nu flux should be detected in the near future.Comment: slight rewording, revised neutrino fluxes, conclusions unchanged, version to appear in Phys. Rev. Let

    Experimental Search for Solar Axions

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    A new technique has been used to search for solar axions using a single crystal germanium detector. It exploits the coherent conversion of axions into photons when their angle of incidence satisfies a Bragg condition with a crystalline plane. The analysis of approximately 1.94 kg.yr of data from the 1-kg DEMOS detector in Sierra Grande, Argentina, yields a new laboratory bound on axion-photon coupling of g_{a,\gamma\gamma}<2.7\times 10^{-9} GeV^{-1} independent of axion mass up to \sim 1 keV

    Relic neutrino masses and the highest energy cosmic rays

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    We consider the possibility that a large fraction of the ultrahigh energy cosmic rays are decay products of Z bosons which were produced in the scattering of ultrahigh energy cosmic neutrinos on cosmological relic neutrinos. We compare the observed ultrahigh energy cosmic ray spectrum with the one predicted in the above Z-burst scenario and determine the required mass of the heaviest relic neutrino as well as the necessary ultrahigh energy cosmic neutrino flux via a maximum likelihood analysis. We show that the value of the neutrino mass obtained in this way is fairly robust against variations in presently unknown quantities, like the amount of neutrino clustering, the universal radio background, and the extragalactic magnetic field, within their anticipated uncertainties. Much stronger systematics arises from different possible assumptions about the diffuse background of ordinary cosmic rays from unresolved astrophysical sources. In the most plausible case that these ordinary cosmic rays are protons of extragalactic origin, one is lead to a required neutrino mass in the range 0.08 eV - 1.3 eV at the 68 % confidence level. This range narrows down considerably if a particular universal radio background is assumed, e.g. to 0.08 eV - 0.40 eV for a large one. The required flux of ultrahigh energy cosmic neutrinos near the resonant energy should be detected in the near future by AMANDA, RICE, and the Pierre Auger Observatory, otherwise the Z-burst scenario will be ruled out.Comment: 19 pages, 22 figures, REVTeX

    Tibio-femoral joint constraints for bone pose estimation during movement using multi-body optimization

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    The financial support of the Universita'Italo-Francese (Call Vinci) and of the Department of Human Movement and Sport Sciences of the University of Rome ''Foro Italico'' is gratefully acknowledged. The authors wish to acknowledge Dr. Sophie Lacoste for her technical support and John McCamley for his contribution to the refinement of the manuscriptWhen using skin markers and stereophotogrammetry for movement analysis, bone pose estimation may be performed using multi-body optimization with the intent of reducing the effect of soft tissue artefacts. When the joint of interest is the knee, improvement of this approach requires defining subject-specific relevant kinematic constraints. The aim of this work was to provide these constraints in the form of plausible values for the distances between origin and insertion of the main ligaments (ligament lengths), during loaded healthy knee flexion, taking into account the indeterminacies associated with landmark identification during anatomical calibration. Ligament attachment sites were identified through virtual palpation on digital bone templates. Attachments sites were estimated for six knee specimens by matching the femur and tibia templates to low-dose stereoradiography images. Movement data were obtained using stereophotogrammetry and pin markers. Relevant ligament lengths for the anterior and posterior cruciate, lateral collateral, and deep and superficial bundles of the medial collateral ligaments (ACL, PCL, LCL, MCLdeep, MCLsup) were calculated. The effect of landmark identification variability was evaluated performing a Monte Carlo simulation on the coordinates of the origin-insertion centroids. The ACL and LCL lengths were found to decrease, and the MCLdeep length to increase significantly during flexion, while variations in PCL and MCLsup length was concealed by the experimental indeterminacy. An analytical model is given that provides subject-specific plausible ligament length variations as functions of the knee flexion angle and that can be incorporated in a multi-body optimization procedure
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