486 research outputs found
SIGMA and XTE observations of the soft X-ray transient XTEJ1755-324
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
The position of the two-proton drip line has been calculated for even-even
nuclei with 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
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
Ground-state properties of spherical even-even nuclei and
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 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 channel.Comment: 12 pages, RevTex, 10 p.s figures, submitted to Phys. Rev.
GOHTAM: a website for âGenomic Origin of Horizontal Transfers, Alignment and Metagenomicsâ
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
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
PaleofitogeografĂa de los pinares en las montañas perifĂ©ricas de la cuenca del Duero
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
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
- âŠ