134 research outputs found

    Measurement of the transverse asymmetry of γ\gamma-rays in the 117^{117}Sn(n,γ\gamma)118^{118}Sn reaction

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    Largely enhanced parity-violating effects observed in compound resonances induced by epithermal neutrons are currently attributed to the mixing of parity-unfavored partial amplitudes in the entrance channel of the compound states. Furthermore, it is proposed that the same mechanism that enhances the parity-violation also enhances the breaking of time-reversal-invariance in the compound nucleus. The entrance-channel mixing induces energy-dependent spin-angular correlations of individual γ\gamma-rays emitted from the compound nuclear state. For a detailed study of the mixing model, a γ\gamma-ray yield in the reaction of 117^{117}Sn(n,γ\gamma)118^{118}Sn was measured using the pulsed beam of polarized epithermal neutrons and Ge detectors. An angular dependence of asymmetric γ\gamma-ray yields for the orientation of the neutron polarization was observed.Comment: 7 pages, 10 figure

    Neutron lifetime measurement with pulsed cold neutrons

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    The neutron lifetime has been measured by comparing the decay rate with the reaction rate of 3^3He nuclei of a pulsed neutron beam from the spallation neutron source at the Japan Proton Accelerator Research Complex (J-PARC). The decay rate and the reaction rate were determined by simultaneously detecting electrons from the neutron decay and protons from the 3^3He(n,p)3^3H reaction using a gas chamber of which working gas contains diluted 3^3He. The measured neutron lifetime was 898\,\pm\,10\,_{\rm stat}\,^{+15}_{-18}\,_{\rm sys}\,s.Comment: 28 pages, 20 figures, will be submitted to PTE

    VERA Observation of the W49N H2O Maser Outburst in 2003 October

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    We report on a strong outburst of the W49N H2O maser observed with VERA. Single-dish monitoring with VERA 20 m telescopes detected a strong outburst of the maser feature at V_LSR = -30.7 km/s in 2003 October. The outburst had a duration of ~100 days and a peak intensity of 7.9 x 10^4 Jy, being one of the strongest outbursts in W49N observed so far. VLBI observations with the VERA array were also carried out near to the maximum phase of the outburst, and the outburst spot was identified in the VLBI map. While the map was in good agreement with previous studies, showing three major concentrations of maser spots, we found a newly formed arc-like structure in the central maser concentration, which may be a shock front powered by a forming star or a star cluster. The outburst spot was found to be located on the arc-like structure, indicating a possible connection of the present outburst to a shock phenomenon.Comment: 4 pages, 2 figures included, to appear in PASJ letter (Vol.56, #3, 2004 June

    A Long Baseline Neutrino Oscillation Experiment Using J-PARC Neutrino Beam and Hyper-Kamiokande

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    Document submitted to 18th J-PARC PAC meeting in May 2014. 50 pages, 41 figuresDocument submitted to 18th J-PARC PAC meeting in May 2014. 50 pages, 41 figuresDocument submitted to 18th J-PARC PAC meeting in May 2014. 50 pages, 41 figuresHyper-Kamiokande will be a next generation underground water Cherenkov detector with a total (fiducial) mass of 0.99 (0.56) million metric tons, approximately 20 (25) times larger than that of Super-Kamiokande. One of the main goals of Hyper-Kamiokande is the study of CPCP asymmetry in the lepton sector using accelerator neutrino and anti-neutrino beams. In this document, the physics potential of a long baseline neutrino experiment using the Hyper-Kamiokande detector and a neutrino beam from the J-PARC proton synchrotron is presented. The analysis has been updated from the previous Letter of Intent [K. Abe et al., arXiv:1109.3262 [hep-ex]], based on the experience gained from the ongoing T2K experiment. With a total exposure of 7.5 MW ×\times 107^7 sec integrated proton beam power (corresponding to 1.56×10221.56\times10^{22} protons on target with a 30 GeV proton beam) to a 2.52.5-degree off-axis neutrino beam produced by the J-PARC proton synchrotron, it is expected that the CPCP phase δCP\delta_{CP} can be determined to better than 19 degrees for all possible values of δCP\delta_{CP}, and CPCP violation can be established with a statistical significance of more than 3σ3\,\sigma (5σ5\,\sigma) for 7676% (5858%) of the δCP\delta_{CP} parameter space

    Variants of C-C Motif Chemokine 22 (CCL22) Are Associated with Susceptibility to Atopic Dermatitis: Case-Control Studies

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    Atopic dermatitis (AD) is a common inflammatory skin disease caused by multiple genetic and environmental factors. AD is characterized by the local infiltration of T helper type 2 (Th2) cells. Recent clinical studies have shown important roles of the Th2 chemokines, CCL22 and CCL17 in the pathogenesis of AD. To investigate whether polymorphisms of the CCL22 gene affect the susceptibility to AD, we conducted association studies and functional studies of the related variants. We first resequenced the CCL22 gene and found a total of 39 SNPs. We selected seven tag SNPs in the CCL22 gene, and conducted association studies using two independent Japanese populations (1st population, 916 cases and 1,032 controls; 2nd population 1,034 cases and 1,004 controls). After the association results were combined by inverse variance method, we observed a significant association at rs4359426 (meta-analysis, combined P = 9.6×10−6; OR, 0.74; 95% CI, 0.65–0.85). Functional analysis revealed that the risk allele of rs4359426 contributed to higher expression levels of CCL22 mRNA. We further examined the allelic differences in the binding of nuclear proteins by electrophoretic mobility shift assay. The signal intensity of the DNA-protein complex derived from the G allele of rs223821, which was in absolute LD with rs4359426, was higher than that from the A allele. Although further functional analyses are needed, it is likely that related variants play a role in susceptibility to AD in a gain-of-function manner. Our findings provide a new insight into the etiology and pathogenesis of AD

    Mucinous cystic neoplasms of the mesentery: a case report and review of the literature

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    <p>Abstract</p> <p>Background</p> <p>Mucinous cystic neoplasms arise in the ovary and various extra-ovarian sites. While their pathogenesis remains conjectural, their similarities suggest a common pathway of development. There have been rare reports involving the mesentery as a primary tumour site.</p> <p>Case presentation</p> <p>A cystic mass of uncertain origin was demonstrated radiologically in a 22 year old female with chronic abdominal pain. At laparotomy, the mass was fixed within the colonic mesentery. Histology demonstrated a benign mucinous cystadenoma.</p> <p>Methods and results</p> <p>We review the literature on mucinous cystic neoplasms of the mesentery and report on the pathogenesis, biologic behavior, diagnosis and treatment of similar extra-ovarian tumors. We propose an updated classification of mesenteric cysts and cystic tumors.</p> <p>Conclusion</p> <p>Mucinous cystic neoplasms of the mesentery present almost exclusively in women and must be considered in the differential diagnosis of mesenteric tumors. Only full histological examination of a mucinous cystic neoplasm can exclude a borderline or malignant component. An updated classification of mesenteric cysts and cystic tumors is proposed.</p
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