485 research outputs found

    SIGMA and XTE observations of the soft X-ray transient XTEJ1755-324

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    We present observations of the X-ray transient XTEJ1755-324 performed during summer 1997 with the XTE satellite and with the SIGMA hard X-ray telescope onboard the GRANAT observatory. The source was first detected in soft X-rays with XTE on July 25 1997 with a rather soft X-ray spectrum and its outburst was monitored in soft X-rays up to November 1997. On September 16 it was first detected in hard X-rays by the French soft gamma ray telescope SIGMA during a Galactic Center observation. The flux was stronger on September 16 and 17 reaching a level of about 110 mCrab in the 40-80 keV energy band. On the same days the photon index of the spectrum was determined to be alpha =-2.3 +/- 0.9 (1 sigma error) while the 40-150 keV luminosity was about 8 x 10^{36} erg/s for a distance of 8.5 kpc. SIGMA and XTE results on this source indicate that this source had an ultrasoft-like state during its main outburst and a harder secondary outburst in September. These characteristics make the source similar to X-Nova Muscae 1991, a well known black hole candidate.Comment: 19 pages LaTeX, 6 Postscript figures included, Accepted by Astrophysical Journa

    Proton drip-line nuclei in relativistic mean-field theory

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    The position of the two-proton drip line has been calculated for even-even nuclei with 10≀Z≀8210 \leq Z \leq 82 in the framework of the relativistic mean-field (RMF) theory. The current model uses the NL3 effective interaction in the mean-field Lagrangian and describes pairing correlations in the Bardeen-Cooper-Schrieffer (BCS) formalism. The predictions of the RMF theory are compared with those of the Hartree-Fock+BCS approach (with effective force Skyrme SIII) and the finite-range droplet model (FRDM) and with the available experimental information.Comment: 18 pages, RevTeX, 2 p.s figures, to appear in Phys. Rev.

    Further evidence to justify reassignment of Mycoplasma mycoides subspecies mycoides Large Colony type to Mycoplasma mycoides subspecies capri

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    Analysis, using the polymerase chain reaction (PCR), restriction enzyme endonuclease analysis (REA), protein profile patterns, random amplification of polymorphic DNA (RAPD) fingerprinting, 16S rRNA gene sequencing and antisera growth inhibition tests, of 22 strains of Mycoplasma mycoides subsp. mycoides Large Colony type (MmmLC) and eight strains of M. mycoides subsp. capri (Mmc) are presented, along with a summary of comparative data from the literature for over 100 strains, all of which supports the reclassification of the MmmLC and Mmc strains into the single subspecies, M. mycoides subspecies capri

    Proton drip-line nuclei in Relativistic Hartree-Bogoliubov theory

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    Ground-state properties of spherical even-even nuclei 14≀Z≀2814\leq Z \leq 28 and N=18,20,22N=18,20,22 are described in the framework of Relativistic Hartree Bogoliubov (RHB) theory. The model uses the NL3 effective interaction in the mean-field Lagrangian, and describes pairing correlations by the pairing part of the finite range Gogny interaction D1S. Binding energies, two-proton separation energies, and proton rmsrms radii that result from fully self-consistent RHB solutions are compared with experimental data. The model predicts the location of the proton drip-line. The isospin dependence of the effective spin-orbit potential is discussed, as well as pairing properties that result from the finite range interaction in the pppp channel.Comment: 12 pages, RevTex, 10 p.s figures, submitted to Phys. Rev.

    GOHTAM: a website for ‘Genomic Origin of Horizontal Transfers, Alignment and Metagenomics’

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    Motivation: This website allows the detection of horizontal transfers based on a combination of parametric methods and proposes an origin by researching neighbors in a bank of genomic signatures. This bank is also used to research an origin to DNA fragments from metagenomics studies

    Properties Of The Hard X-ray Radiation From The Black Hole Candidates: Cygnus X-1 And 1E1740.7-2942

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    The entire dataset of the GRANAT/SIGMA observations of Cyg X-1 and 1E1740.7-2942 in 1990-1994 was analyzed in order to search for correlations between primary observational characteristics of the hard X-ray (40-200 keV) emission - hard X-ray luminosity, hardness of the spectrum (quantified in terms of the best-fit thermal bremsstrahlung temperature kT) and the RMS of short-term flux variations. Although no strict point-to-point correlations were detected certain general tendencies are evident. It was found that for Cyg X-1 the spectral hardness is in general positively correlated with relative amplitude of short-term variability. The correlation of similar kind was found for X-ray transient GRO J0422+32 (X-ray Nova Persei 1992). For both sources an approximate correlation between kT and L_X was found. At low hard X-ray luminosity - below 10E37 erg/sec - kT increases with L_X. At higher luminosity the spectral hardness depends weaker or does not depend at all on the hard X-ray luminosity. The low luminosity end of these approximate correlations (low kT and low RMS) corresponds to extended episodes of very low hard X-ray flux occurred during SIGMA observations.Comment: 6 pages, 7 figures, uses mn.sty, epsf.sty, psfig.tex; Accepted for publication in MNRAS; Also available at http://hea.iki.rssi.ru/~sik/PAPERS/mnras97.ps.gz (gzipped PostScript

    Paleofitogeografía de los pinares en las montañas periféricas de la cuenca del Duero

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    En las dos Ășltimas dĂ©cadas se han obtenido numerosos resultados procedentes de diferentes trabajos paleobotĂĄnicos (Cuaternario final) realizados en los territorios montanos perifĂ©ricos de la depresiĂłn del Duero. Las metodologĂ­as empleadas han sido diversas y tienen que ver con los diferentes tipos de yacimientos y de muestras biolĂłgicas seleccionadas para su estudio; entre ellas destacan las tĂ©cnicas de microscopĂ­a Ăłptica para la identificaciĂłn de maderas subfĂłsiles, la morfologĂ­a comparada de macrorrestos y los estudios dendrocronolĂłgicos en ĂĄrboles longevos y maderas subfĂłsiles. En esta comunicaciĂłn se reĂșnen y resumen los trabajos mĂĄs importantes, haciĂ©ndose una sĂ­ntesis de las conclusiones obtenidas en los trabajos paleofitogeogrĂĄficos realizados hasta el momento; se hace hincapiĂ© en la informaciĂłn proporcionada por los macrorrestos (maderas, estrĂłbilos) asĂ­ como por la recogida en los registros dendrocronolĂłgicos (con extensiĂłn a la dendroecologĂ­a). Otro de los objetivos de la comunicaciĂłn es la sĂ­ntesis de las conclusiones obtenidas en los trabajos paleofitogeogrĂĄficos realizados hasta el momento. Uno de esos resultados es que el comportamiento de los pinares a lo largo del Holoceno presenta diferentes modalidades en cada una de las cordilleras que bordean la cuenca del Duero; desde casos con marcada estabilidad a otros en que se muestran variaciones temporales apreciables (con patrones de heterogeneidad en funciĂłn de un eje N-S y/o O-E

    Genomics and metagenomics of trimethylamine-utilizing Archaea in the human gut microbiome

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    International audienceThe biological significance of Archaea in the human gut microbiota is largely unclear. We recently reported genomic and biochemical analyses of the Methanomassiliicoccales, a novel order of methanogenic Archaea dwelling in soil and the animal digestive tract. We now show that these Methanomassiliicoccales are present in published microbiome data sets from eight countries. They are represented by five Operational Taxonomic Units present in at least four cohorts and phylogenetically distributed into two clades. Genes for utilizing trimethylamine (TMA), a bacterial precursor to an atherosclerogenic human metabolite, were present in four of the six novel Methanomassiliicoccales genomes assembled from ELDERMET metagenomes. In addition to increased microbiota TMA production capacity in long-term residential care subjects, abundance of TMA-utilizing Methanomassiliicoccales correlated positively with bacterial gene count for TMA production and negatively with fecal TMA concentrations. The two large Methanomassiliicoccales clades have opposite correlations with host health status in the ELDERMET cohort and putative distinct genomic signatures for gut adaptation
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