462 research outputs found

    Role of dynamical particle-vibration coupling in reconciliation of the d3/2d_{3/2} puzzle for spherical proton emitters

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    It has been observed that decay rate for proton emission from d3/2d_{3/2} single particle state is systematically quenched compared with the prediction of a one dimensional potential model although the same model successfully accounts for measured decay rates from s1/2s_{1/2} and h11/2h_{11/2} states. We reconcile this discrepancy by solving coupled-channels equations, taking into account couplings between the proton motion and vibrational excitations of a daughter nucleus. We apply the formalism to proton emitting nuclei 160,161^{160,161}Re to show that there is a certain range of parameter set of the excitation energy and the dynamical deformation parameter for the quadrupole phonon excitation which reproduces simultaneously the experimental decay rates from the 2d3/2d_{3/2}, 3s1/2s_{1/2} and 1h11/2h_{11/2} states in these nuclei.Comment: RevTex, 12 pages, 4 eps figure

    High quality MgB2 thin films in-situ grown by dc magnetron sputtering

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    Thin films of the recently discovered magnesium diboride (MgB2) intermetalic superconducting compound have been grown using a magnetron sputtering deposition technique followed by in-situ annealing at 830 C. High quality films were obtained on both sapphire and MgO substrates. The best films showed maximum Tc = 35 K (onset), a transition width of 0.5 K, a residual resistivity ratio up to 1.6, a low temperature critical current density Jc > 1 MA/cm2 and anisotropic critical field with gamma = 2.5 close to the values obtained for single crystals. The preparation technique can be easily scaled to produce large area in-situ films.Comment: 7 pages, 4 figure

    Structure of positive energy states in a deformed mean-field potential

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    We investigate the properties of single-particle resonances in a non-spherical potential by solving the coupled-channels equations for the radial wave functions. We first generalize the box discretization method for positive energy states to a deformed system. As in the spherical case, we find that the discretized energy is stabilized against the box size when a resonance condition is met. Using the wave functions thus obtained, we then discuss the energy and the radial dependences of scattering wave functions in the vicinity of an isolated resonance. In the eigenchannel basis, where the SS-matrix is diagonal, we propose a generalized expression for the factorization formula for the multi-channel wave function. We find that the factorized wave function agrees well with the exact solution inside the centrifugal barrier when the energy distance from the resonance is less than the resonance width.Comment: 22 pages, 5 eps figures; a figure adde

    Theoretical description of deformed proton emitters: nonadiabatic coupled-channel method

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    The newly developed nonadiabatic method based on the coupled-channel Schroedinger equation with Gamow states is used to study the phenomenon of proton radioactivity. The new method, adopting the weak coupling regime of the particle-plus-rotor model, allows for the inclusion of excitations in the daughter nucleus. This can lead to rather different predictions for lifetimes and branching ratios as compared to the standard adiabatic approximation corresponding to the strong coupling scheme. Calculations are performed for several experimentally seen, non-spherical nuclei beyond the proton dripline. By comparing theory and experiment, we are able to characterize the angular momentum content of the observed narrow resonance.Comment: 12 pages including 10 figure

    STM tunneling spectroscopic studies of YNdxBa2−xCu3O7−δ thin films

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    We performed tunneling spectroscopy on high quality superconducting YNdxBa2-xCu3O7-delta thin films using a low-temperature scanning tunneling microscope. Superconducting regions show very well-defined gap structures. Disorder introduced by Nd substitution at the Ba site dramatically affects locally the quasiparticle density of states. The measurements show that the impurities induce surface resonant states at energies very close to the Fermi energy, typical of a d-wave superconductor

    B Cells Regulate Neutrophilia during Mycobacterium tuberculosis Infection and BCG Vaccination by Modulating the Interleukin-17 Response

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    We have previously demonstrated that B cells can shape the immune response to Mycobacterium tuberculosis, including the level of neutrophil infiltration and granulomatous inflammation at the site of infection. The present study examined the mechanisms by which B cells regulate the host neutrophilic response upon exposure to mycobacteria and how neutrophilia may influence vaccine efficacy. To address these questions, a murine aerosol infection tuberculosis (TB) model and an intradermal (ID) ear BCG immunization mouse model, involving both the μMT strain and B cell-depleted C57BL/6 mice, were used. IL (interleukin)-17 neutralization and neutrophil depletion experiments using these systems provide evidence that B cells can regulate neutrophilia by modulating the IL-17 response during M. tuberculosis infection and BCG immunization. Exuberant neutrophilia at the site of immunization in B cell-deficient mice adversely affects dendritic cell (DC) migration to the draining lymph nodes and attenuates the development of the vaccine-induced Th1 response. The results suggest that B cells are required for the development of optimal protective anti-TB immunity upon BCG vaccination by regulating the IL-17/neutrophilic response. Administration of sera derived from M. tuberculosis-infected C57BL/6 wild-type mice reverses the lung neutrophilia phenotype in tuberculous μMT mice. Together, these observations provide insight into the mechanisms by which B cells and humoral immunity modulate vaccine-induced Th1 response and regulate neutrophila during M. tuberculosis infection and BCG immunization. © 2013 Kozakiewicz et al

    Proton emission from the deformed odd-odd nuclei near drip line

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    Proton emission from odd-odd nuclei is studied within the two quasiparticle plus rotor model which includes the non-adiabatic effects and the residual interaction between valence proton and neutron. Justification of the formalism is discussed through corroboration of our results with the experimental spectrum of 180Ta. Exact calculations are performed to get the proton emission halflives. Our results for the proton emitter 130Eu leads to the assignment of spin and parity Jπ = 1+ for the ground state. The role of Coriolis and residual neutron-proton interactions on the proton emission halflives and their interplay are also discussed

    Advanced LIGO

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    The Advanced LIGO gravitational wave detectors are second-generation instruments designed and built for the two LIGO observatories in Hanford, WA and Livingston, LA, USA. The two instruments are identical in design, and are specialized versions of a Michelson interferometer with 4 km long arms. As in Initial LIGO, Fabry–Perot cavities are used in the arms to increase the interaction time with a gravitational wave, and power recycling is used to increase the effective laser power. Signal recycling has been added in Advanced LIGO to improve the frequency response. In the most sensitive frequency region around 100 Hz, the design strain sensitivity is a factor of 10 better than Initial LIGO. In addition, the low frequency end of the sensitivity band is moved from 40 Hz down to 10 Hz. All interferometer components have been replaced with improved technologies to achieve this sensitivity gain. Much better seismic isolation and test mass suspensions are responsible for the gains at lower frequencies. Higher laser power, larger test masses and improved mirror coatings lead to the improved sensitivity at mid and high frequencies. Data collecting runs with these new instruments are planned to begin in mid-2015.submittedVersionFil: Domínguez, Alfredo Eduardo. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Domínguez, Alfredo Eduardo. Argentinian Gravitational Wave Group; Argentina.Fil: Maglione, César Germán. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Maglione, César Germán. Argentinian Gravitational Wave Group; Argentina.Fil: Ortega Larcher, Walter Emanuel. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Ortega Larcher, Walter Emanuel. Argentinian Gravitational Wave Group; Argentina.Fil: Quiroga, Gonzalo Damián. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Quiroga, Gonzalo Damián. Argentinian Gravitational Wave Group; Argentina.Fil: Reula, Oscar Alejandro. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Reula, Oscar Alejandro. Argentinian Gravitational Wave Group; Argentina.Física de Partículas y Campo

    Recurrent neck abscesses due to cervical tuberculous lymphadenopathy in an elderly woman post-splenectomy: a case report

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    <p>Abstract</p> <p>Introduction</p> <p>There are approximately 7000 new cases of tuberculosis every year in the UK, the majority of which are pulmonary. Approximately 5% affect the lymph nodes in immunocompetent patients. Scrofula is an old term used to describe lymph nodes of the neck infected with tuberculosis</p> <p>Case presentation</p> <p>In the elderly population, growing neck lumps are always treated as red flags until a diagnosis is confirmed. Here, the case of an 89-year-old Caucasian woman is presented. She was reluctant to seek medical help as she feared the cause was sinister and did not want surgical intervention.</p> <p>Conclusion</p> <p>It is difficult to culture tuberculosis from superficial swabs, resulting in a high proportion of false negative results. Where there is a high degree of clinical suspicion for tuberculosis, it is important to consider a biopsy with culture. Patients over the age of 65 have waning immunity and are therefore a vulnerable group for acute infections as well as the re-activation of indolent organisms. Post-splenectomy patients are at a major disadvantage during sepsis and when a cellular immune response is required, such as when faced with a <it>Mycobacterium tuberculosis </it>infection. Scrofula is treated with a similar regime as pulmonary tuberculosis and has a near 100% success rate.</p
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