2,559 research outputs found

    Asymptotic Normalization Coefficients for 13C+p->14N

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    The 13C(14N,13C)14N^{13}C(^{14}N,^{13}C)^{14}N proton exchange reaction has been measured at an incident energy of 162 MeV. Angular distributions were obtained for proton transfer to the ground and low lying excited states in 14N^{14}N. Elastic scattering of 14N^{14}N on 13C^{13}C also was measured out to the rainbow angle region in order to find reliable optical model potentials. Asymptotic normalization coefficients for the system 13C+p→14N^{13}C+p\to {}^{14}N have been found for the ground state and the excited states at 2.313, 3.948, 5.106 and 5.834 MeV in 14N^{14}N. These asymptotic normalization coefficients will be used in a determination of the S-factor for 7Be(p,γ)8B^{7}Be(p,\gamma)^{8}B at solar energies from a measurement of the proton transfer reaction 14N(7Be,8B)13C^{14}N(^{7}Be,^{8}B)^{13}C.Comment: 5 pages, 6 figure

    Impact of Social Determinants of Health on Early Hearing Detection and Intervention Screening/Diagnosis Outcomes

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    Purpose We reviewed how Social Determinants of Health relate to health inequities and disparities for Early Hearing Detection and Intervention (EHDI) programs. Then, we examine links between specific sociodemographic factors (maternal age, maternal education, ‘race’/ethnicity) and hearing screening and diagnostic audiology follow-up for newborns in the U.S. and its territories. Methods Maternal demographic, hearing screening and diagnostic data extracted from publicly available Centers for Disease Control and Prevention (CDC) records were reported to CDC by personnel responsible for EHDI programs. Data were subjected to statistical analysis using analysis of variance and multiple regression techniques. Results Results showed no significant differences in screening follow-up outcomes for maternal age, education, or ‘race’/ethnicity. There was a significant difference for maternal education and \u27race\u27/ethnicity for diagnostic follow-up outcomes, but not for age. Conclusion Results of this study are consistent with the findings of previous studies regarding hearing screening follow-up and diagnostic audiologic follow-up outcomes. Maternal education and ‘race’/ethnicity were linked to hearing diagnostic audiologic follow-up for newborns in the US and its territories. Suggestions for future research, policy, and practice to improve the effectiveness of EHDI efforts are provided

    Correlation of Static Stress Changes and Earthquake Occurrence in

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    A systematic analysis is made of static Coulomb stress changes and earthquake occurrence in the area of the North Aegean Sea, Greece, in order to assess the prospect of using static stress changes to construct a regional earthquake likelihood model. The earthquake data set comprises all events of magnitude M ≄ 5.2 which have occurred since 1964. This is compared to the evolving stress field due to constant tectonic loading and perturbations due to coseismic slip associated with major earthquakes (M ≄ 6.4) over the same period. The stress was resolved for sixteen fault orientation classes, covering the observed focal mechanisms of all earthquakes in the region. Analysis using error diagrams shows that earthquake occurrence is better correlated with the constant tectonic loading component of the stress field than with the total stress field changes since 1964, and that little, if any, information on earthquake occurrence is lost if only the maximum of the tectonic loading over the fault orientation classes is considered. Moreover, the information on earthquake occurrence is actually increased by taking the maximum of the evolving stress field since 1964, and of its coseismic–slip component, over the fault orientation classes. The maximum, over fault orientation classes, of linear combinations of the tectonic loading and the evolving stress field is insignificantly better correlated with earthquake occurrence than the maximum of the tectonic loading by itself. A composite stress–change variable is constructed from ordering of the maximum tectonic loading component and the maximum coseismic–slip component, in order to optimize the correlation with earthquake occurrence. The results indicate that it would be difficult to construct a time–varying earthquake likelihood model from the evolving stress field that is more informative than a time–invariant model based on the constant tectonic loading

    Tests of Transfer Reaction Determinations of Astrophysical S-Factors

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    The 16O(3He,d)17F{}^{16}O ({}^{3}He,d) {}^{17}F reaction has been used to determine asymptotic normalization coefficients for transitions to the ground and first excited states of 17F{}^{17}F. The coefficients provide the normalization for the tails of the overlap functions for 17F→16O+p{}^{17}F \to{}^{16}O + p and allow us to calculate the S-factors for 16O(p,γ)17F{}^{16}O (p,\gamma){}^{17}F at astrophysical energies. The calculated S-factors are compared to measurements and found to be in very good agreement. This provides the first test of this indirect method to determine astrophysical direct capture rates using transfer reactions. In addition, our results yield S(0) for capture to the ground and first excited states in 17F^{17}F, without the uncertainty associated with extrapolation from higher energies.Comment: 6 pages, 2 figure

    Expanding the parameters of academia

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    This paper draws on qualitative data gathered from two studies funded by the UK Leadership Foundation for Higher Education to examine the expansion of academic identities in higher education. It builds on Whitchurch’s earlier work, which focused primarily on professional staff, to suggest that the emergence of broadly based projects such as widening participation, learning support and community partnership is also impacting on academic identities. Thus, academic as well as professional staff are increasingly likely to work in multi-professional teams across a variety of constituencies, as well as with external partners, and the binary distinction between ‘academic’ and ‘non-academic’ roles and activities is no longer clear-cut. Moreover, there is evidence from the studies of an intentionality about deviations from mainstream academic career routes among respondents who could have gone either way. Consideration is therefore given to factors that influence individuals to work in more project-oriented areas, as well as to variables that affect ways in which these roles and identities develop. Finally, three models of academically oriented project activity are identified, and the implications of an expansion of academic identities are reviewed

    A general existence principle for fixed point theorems in D

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    We establish two general principles for fixed point theorems in D-metric spaces, and then show that several theorems in D-metric spaces follow as corollaries of these general principles

    Optical model potentials involving loosely bound p-shell nuclei around 10 MeV/A

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    We present the results of a search for optical model potentials for use in the description of elastic scattering and transfer reactions involving stable and radioactive p-shell nuclei. This was done in connection with our program to use transfer reactions to obtain data for nuclear astrophysics, in particular for the determination of the astrophysical S_17 factor for 7Be(p,\gamma)8B using two (7Be,8B) proton transfer reactions. Elastic scattering was measured using 7Li, 10B, 13C and 14N projectiles on 9Be and 13C targets at or about E/A=10 MeV/nucleon. Woods-Saxon type optical model potentials were extracted and are compared with potentials obtained from a microscopic double folding model. We use these results to find optical model potentials for unstable nuclei with emphasis on the reliability of the description they provide for peripheral proton transfer reactions. We discuss the uncertainty introduced by the procedure in the prediction of the DWBA cross sections for the (7Be,8B) reactions used in extracting the astrophysical factor S_17(0).Comment: 16 pages, LaTEX file, 9 figures (PostScript files

    Asymptotic normalization coefficients for 8B->7Be+p from a study of 8Li->7Li+n

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    Asymptotic normalization coefficients (ANCs) for 8Li->7Li+n have been extracted from the neutron transfer reaction 13C(7Li,8Li)12C at 63 MeV. These are related to the ANCs in 8B->7Be+p using charge symmetry. We extract ANCs for 8B that are in very good agreement with those inferred from proton transfer and breakup experiments. We have also separated the contributions from the p_1/2 and p_3/2 components in the transfer. We find the astrophysical factor for the 7Be(p,gamma)8B reaction to be S_17(0)=17.6+/-1.7 eVb. This is the first time that the rate of a direct capture reaction of astrophysical interest has been determined through a measurement of the ANCs in the mirror system.Comment: 5 pages, 3 figures, 2 table

    Residence Time Statistics for Normal and Fractional Diffusion in a Force Field

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    We investigate statistics of occupation times for an over-damped Brownian particle in an external force field. A backward Fokker-Planck equation introduced by Majumdar and Comtet describing the distribution of occupation times is solved. The solution gives a general relation between occupation time statistics and probability currents which are found from solutions of the corresponding problem of first passage time. This general relationship between occupation times and first passage times, is valid for normal Markovian diffusion and for non-Markovian sub-diffusion, the latter modeled using the fractional Fokker-Planck equation. For binding potential fields we find in the long time limit ergodic behavior for normal diffusion, while for the fractional framework weak ergodicity breaking is found, in agreement with previous results of Bel and Barkai on the continuous time random walk on a lattice. For non-binding potential rich physical behaviors are obtained, and classification of occupation time statistics is made possible according to whether or not the underlying random walk is recurrent and the averaged first return time to the origin is finite. Our work establishes a link between fractional calculus and ergodicity breaking.Comment: 12 page

    Collective Modes of Tri-Nuclear Molecules

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    A geometrical model for tri-nuclear molecules is presented. An analytical solution is obtained provided the nuclei, which are taken to be prolately deformed, are connected in line to each other. Furthermore, the tri-nuclear molecule is composed of two heavy and one light cluster, the later sandwiched between the two heavy clusters. A basis is constructed in which Hamiltonians of more general configurations can be diagonalized. In the calculation of the interaction between the clusters higher multipole deformations are taken into account, including the hexadecupole one. A repulsive nuclear core is introduced in the potential in order to insure a quasi-stable configuration of the system. The model is applied to three nuclear molecules, namely 96^{96}Sr + 10^{10}Be + 146^{146}Ba, 108^{108}Mo + 10^{10}Be + 134^{134}Te and 112^{112}Ru + 10^{10}Be + 130^{130}Sn.Comment: 24 pages, 9 figure
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