13,423 research outputs found

    A Revised Effective Temperature Scale for the Kepler Input Catalog

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    We present a catalog of revised effective temperatures for stars observed in long-cadence mode in the Kepler Input Catalog (KIC). We use SDSS griz filters tied to the fundamental temperature scale. Polynomials for griz color-temperature relations are presented, along with correction terms for surface gravity effects, metallicity, and statistical corrections for binary companions or blending. We compare our temperature scale to the published infrared flux method (IRFM) scale for VJKs in both open clusters and the Kepler fields. We find good agreement overall, with some deviations between (J - Ks)-based temperatures from the IRFM and both SDSS filter and other diagnostic IRFM color-temperature relationships above 6000 K. For field dwarfs we find a mean shift towards hotter temperatures relative to the KIC, of order 215 K, in the regime where the IRFM scale is well-defined (4000 K to 6500 K). This change is of comparable magnitude in both color systems and in spectroscopy for stars with Teff below 6000 K. Systematic differences between temperature estimators appear for hotter stars, and we define corrections to put the SDSS temperatures on the IRFM scale for them. When the theoretical dependence on gravity is accounted for we find a similar temperature scale offset between the fundamental and KIC scales for giants. We demonstrate that statistical corrections to color-based temperatures from binaries are significant. Typical errors, mostly from uncertainties in extinction, are of order 100 K. Implications for other applications of the KIC are discussed.Comment: Corrected for sign flip errors in the gravity corrections. Erratum to this paper is attached in Appendix. Full version of revised Table 7 can be found at http://home.ewha.ac.kr/~deokkeun/kic/sdssteff_v2.dat.g

    Multiple-antibiotic-resistant bacteria from cockroaches trapped from a public hospital and a nearby students’ hostel in Accra, Ghana

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    The ability of cockroaches, found in and around hospital settings, to harbour multiple- antibioticresistant bacteria poses serious health implications. This study investigated and compared multiple-antibioticresistant bacteria carried by cockroaches from a hospital environment. Antibiotic susceptibility patterns of isolated pathogenic bacteria on the internal and external surfaces of trapped cockroaches showed that over 60% of the Gram negative enteric  bacilli, >90% of the 23 Pseudomonas aeruginosa and all three Gram positive bacteria isolates were resistant to at least four of the antibiotics tested. Necessary control measures need to be taken against the infestation of such facilities by cockroaches.Keywords: Multiple-antibiotic-resistant bacteria, cockroaches, hospital, hostel

    Deep crustal heating by neutrinos from the surface of accreting neutron stars

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    We present a new mechanism for deep crustal heating in accreting neutron stars. Charged pions (π+\pi^+) are produced in nuclear collisions on the neutron star surface during active accretion and upon decay they provide a flux of neutrinos into the neutron star crust. For massive and/or compact neutron stars, neutrinos deposit ≈1–2 MeV\approx 1\textrm{--} 2 \, \mathrm{MeV} of heat per accreted nucleon into the inner crust. The strength of neutrino heating is comparable to the previously known sources of deep crustal heating, such as from pycnonuclear fusion reactions, and is relevant for studies of cooling neutron stars. We model the thermal evolution of a transient neutron star in a low-mass X-ray binary, and in the particular case of the neutron star MXB~1659-29 we show that additional deep crustal heating requires a higher thermal conductivity for the neutron star inner crust. A better knowledge of pion production cross sections near threshold would improve the accuracy of our predictions.Comment: 12 pages, 9 figures, 3 tables; [Added a new figure and edited the text in response to Referee's remarks and suggestions

    Pion Transparency in 500 MeV C(pi,pi') Reactions?

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    The question whether there is a pion transparency in 500 MeV C(π,π′)C(\pi, \pi^{'}) scatterings is studied using a semiclassical, hadronic transport model. The double differential cross sections of this reaction measured at LAMPF can be largely accounted for, if one uses energy-dependent, anisotropic angular distributions which are fitted to pion-nucleon scattering data for the decay of Δ(1232)\Delta(1232) and N∗(1440)N^*(1440) resonances. The remaining discrepancy between the data and the calculation sets a limit on effects of more exotic processes.Comment: Latex file, 11 pages, 3 figures availabe upon request. Phys. Lett. B in pres
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