305 research outputs found
Draft Genome Sequences of Five Enterococcus Species Isolated from the Gut of Patients with Suspected Clostridium difficile Infection
Indexación: Scopus.We present draft genome sequences of five Enterococcus species from patients suspected of Clostridium difficile infection. Genome completeness was confirmed by presence of bacterial orthologs (97%). Gene searches using Hidden-Markov models revealed that the isolates harbor between seven and 11 genes involved in antibiotic resistance to tetracyclines, beta-lactams, and vancomycin.http://genomea.asm.org/content/5/20/e00379-17.ful
Searching for tidal tails around Centauri using RR Lyrae Stars
We present a survey for RR Lyrae stars in an area of 50 deg around the
globular cluster Centauri, aimed to detect debris material from the
alleged progenitor galaxy of the cluster. We detected 48 RR Lyrae stars of
which only 11 have been previously reported. Ten among the eleven previously
known stars were found inside the tidal radius of the cluster. The rest were
located outside the tidal radius up to distances of degrees from the
center of the cluster. Several of those stars are located at distances similar
to that of Centauri. We investigated the probability that those stars
may have been stripped off the cluster by studying their properties (mean
periods), calculating the expected halo/thick disk population of RR Lyrae stars
in this part of the sky, analyzing the radial velocity of a sub-sample of the
RR Lyrae stars, and finally, studying the probable orbits of this sub-sample
around the Galaxy. None of these investigations support the scenario that there
is significant tidal debris around Centauri, confirming previous
studies in the region. It is puzzling that tidal debris have been found
elsewhere but not near the cluster itself.Comment: 11 pages, 11 figures, Accepte
Close encounters involving RAVE stars beyond the 47 Tucanae tidal radius
The most accurate 6D phase-space information from the Radial Velocity
Experiment (RAVE) was used to integrate the orbits of 105 stars around the
galactic globular cluster 47 Tucanae, to look for close encounters between them
in the past, with a minimum distance approach less than the cluster tidal
radius. The stars are currently over the distance range 3.0 kpc d 5.5
kpc. Using the uncertainties in the current position and velocity vector for
both, star and cluster, 105 pairs of star-cluster orbits were generated in a
Monte Carlo numerical scheme, integrated over 2 Gyr and considering an
axisymmetric and non-axisymmetric Milky-Way-like Galactic potential,
respectively. In this scheme, we identified 20 potential cluster members that
had close encounters with the globular cluster 47 Tucanae, all of which have a
relative velocity distribution (V) less than 200 km s at the
minimum distance approach. Among these potential members, 9 had close
encounters with the cluster with velocities less than the escape velocity of 47
Tucanae, therefore a scenario of tidal stripping seems likely. These stars have
been classified with a 93\% confidence level, leading to the identification of
extratidal cluster stars. For the other 11 stars, V exceeds the escape
velocity of the cluster, therefore they were likely ejected or are unassociated
interlopers.Comment: 10 pages, 6 figures, 2 table, Accepted for publication in MNRA
Possible ring material around centaur (2060) Chiron
We propose that several short duration events observed in past stellar
occultations by Chiron were produced by rings material. From a reanalysis of
the stellar occultation data in the literature we determined two possible
orientations of the pole of Chiron's rings, with ecliptic coordinates
l=(352+/-10) deg, b=(37+/-10) deg or l=(144+/-10) deg, b=(24+/-10) deg . The
mean radius of the rings is (324 +/- 10) km. One can use the rotational
lightcurve amplitude of Chiron at different epochs to distinguish between the
two solutions for the pole. Both imply lower lightcurve amplitude in 2013 than
in 1988, when the rotational lightcurve was first determined. We derived
Chiron's rotational lightcurve in 2013 from observations at the 1.23-m CAHA
telescope and indeed its amplitude is smaller than in 1988. We also present a
rotational lightcurve in 2000 from images taken at CASLEO 2.15-m telescope that
is consistent with our predictions. Out of the two poles the l=(144+/-10) deg,
b=(24+/-10) deg solution provides a better match to a compilation of rotational
lightcurve amplitudes from the literature and those presented here. We also
show that using this preferred pole, Chiron's long term brightness variations
are compatible with a simple model that incorporates the changing brightness of
the rings as the tilt angle with respect to the Earth changes with time. Also,
the variability of the water ice band in Chiron's spectra in the literature can
be explained to a large degree by an icy ring system whose tilt angle changes
with time and whose composition includes water ice, analogously to the case of
Chariklo. We present several possible formation scenarios for the rings from
qualitative points of view and speculate on the reasons why rings might be
common in centaurs. We speculate on whether the known bimodal color
distribution of centaurs could be due to presence of rings and lack of them
The visible and thermal light curve of the large Kuiper belt object (50000) Quaoar
Recent stellar occultations have allowed accurate instantaneous size and
apparent shape determinations of the large Kuiper belt object (50000)~Quaoar
and the detection of two rings with spatially variable optical depths. In this
paper we present new visible range light curve data of Quaoar from the
Kepler/K2 mission, and thermal light curves at 100 and 160 m obtained with
Herschel/PACS. The K2 data provide a single-peaked period of 8.88 h, very close
to the previously determined 8.84 h, and it favours an asymmetric double-peaked
light curve with a 17.76 h period. We clearly detected a thermal light curve
with relative amplitudes of 10% at 100 and at 160 m. A detailed
thermophysical modelling of the system shows that the measurements can be best
fit with a triaxial ellipsoid shape, a volume-equivalent diameter of 1090 km,
and axis ratios of a/b = 1.19 and b/c = 1.16. This shape matches the published
occultation shape}, as well as visual and thermal light curve data. The
radiometric size uncertainty remains relatively large (40 km) as the ring
and satellite contributions to the system-integrated flux densities are
unknown. In the less likely case of negligible ring or satellite contributions,
Quaoar would have a size above 1100 km and a thermal inertia 10
JmKs. A large and dark Weywot in combination with a
possible ring contribution would lead to a size below 1080\,km in combination
with a thermal inertia 10 JmKs, notably higher
than that of smaller Kuiper belt objects with similar albedo and colours. We
find that Quaoar's density is in the range 1.67-1.77 g/cm, significantly
lower than previous estimates. This density value closely matches the
relationship observed between the size and density of the largest Kuiper belt
objects.Comment: Accepted for publication in Astronomy and Astrohysics (language
edited version
A Tale of 3 Dwarf Planets: Ices and Organics on Sedna, Gonggong, and Quaoar from JWST Spectroscopy
We observed Sedna, Gonggong, and Quaoar with the NIRSpec instrument on the
James Webb Space Telescope (JWST). All three bodies were observed in the
low-resolution prism mode at wavelengths spanning 0.7 to 5.2 m. Quaoar was
also observed at 10x higher spectral resolution from 0.97 to 3.16 m using
medium-resolution gratings. Sedna's spectrum shows a large number of absorption
features due to ethane (CH), as well as acetylene (CH),
ethylene (CH), HO, and possibly minor CO. Gonggong's spectrum
also shows several, but fewer and weaker, ethane features, along with stronger
and cleaner HO features and CO complexed with other molecules. Quaoar's
prism spectrum shows even fewer and weaker ethane features, the deepest and
cleanest HO features, a feature at 3.2 m possibly due to HCN, and
CO ice. The higher-resolution medium grating spectrum of Quaoar reveals
several overtone and combination bands of ethane and methane (CH). Spectra
of all three objects show steep red spectral slopes and strong, broad
absorptions between 2.7 and 3.6 m indicative of complex organic molecules.
The suite of light hydrocarbons and complex organic molecules are interpreted
as the products of irradiation of methane. We infer that the differences in
apparent abundances of irradiation products are likely due to their distinctive
orbits, which lead to different timescales of methane retention and to
different charged particle irradiation environments. In all cases, however, the
continued presence of light hydrocarbons implies a resupply of methane to the
surface. We suggest that these three bodies have undergone internal melting and
geochemical evolution similar to the larger dwarf planets and distinct from all
smaller KBOs.Comment: 32 pages, 9 figures, 5 tables, accepted for publication in Icaru
Discovery of a Metal-Poor Field Giant with a Globular Cluster Second-Generation Abundance Pattern
We report on the detection, from observations obtained with the Apache Point Observatory Galactic Evolution Experiment spectroscopic survey, of a metal-poor ([Fe/H] = −1.3 dex) field giant star with an extreme Mg–Al abundance ratio ([Mg/Fe] = −0.31 dex; [Al/Fe] = 1.49 dex). Such low Mg/Al ratios are seen only among the second-generation population of globular clusters (GCs) and are not present among Galactic disk field stars. The light-element abundances of this star, 2M16011638-1201525, suggest that it could have been born in a GC. We explore several origin scenarios, studying the orbit of the star in particular to check the probability of its being kinematically related to known GCs. We performed simple orbital integrations assuming the estimated distance of 2M16011638-1201525 and the available six-dimensional phase-space coordinates of 63 GCs, looking for close encounters in the past with a minimum distance approach within the tidal radius of each cluster. We found a very low probability that 2M16011638-1201525 was ejected from most GCs; however, we note that the best progenitor candidate to host this star is GC ω Centauri (NGC 5139). Our dynamical investigation demonstrates that 2M16011638-1201525 reaches a distance from the Galactic plane and minimum and maximum approaches to the Galactic center of R min < 0.62 kpc and R max < 7.26 kpc in an eccentric (e ~ 0.53) and retrograde orbit. Since the extreme chemical anomaly of 2M16011638-1201525 has also been observed in halo field stars, this object could also be considered a halo contaminant, likely to have been ejected into the Milky Way disk from the halo. We conclude that 2M16011638-20152 is also kinematically consistent with the disk but chemically consistent with halo field stars
V01 345. Implante de prótesis aórtica transcatéter por vía transaórtica: una alternativa de abordaje a las vías convencionales
Objetivosel implante de prótesis valvulares aórticas por vía transcatéter es una opción terapéutica reconocida en pacientes de alto riesgo quirúrgico. Nuestro objetivo es mostrar una vía de abordaje alternativa para su implante en algunos pacientes no candidatos para las vías usuales de acceso vascular periférico (femoral/subclavia) o transapical.Material y métodospresentamos el caso de un varón de 74 años con estenosis aórtica grave, CF IV y fracción de eyección del ventrículo izquierdo (FEVI) gravemente deprimida. Antecedentes de neoplasia de colon, diabetes mellitus tipo 2, enfermedad vascular periférica grave, cardiopatía isquémica crónica con revascularización percutánea mediante stents convencionales y neumonectomía derecha por carcinoma de pulmón. EuroSCORE logístico: 42,57%. Ecocardiograma: válvula aórtica trivalva (gradiente máximo 76, medio 51mmHg, área: 0,6cm2;, anillo: 24mm). Angiotomografía computarizada (angio-TC): grave ateromatosis ilíaca bilateral, desplazamiento importante del ápex cardíaco hacia la línea media y de la aorta ascendente hacia el hemitórax derecho. Cateterismo: ateromatosis grave de subclavia izquierda y estenosis grave de subclavia derecha, no reestenosis intra-stents.Se somete a implante de prótesis aórtica Core-Valve autoexpandible número 29 vía transaórtica (aorta ascendente) bajo visión directa a través de minitoracotomía anterior derecha por segundo espacio intercostal.Resultadosel paciente es extubado en 6h. Ecocardiograma de control: prótesis con apertura conservada e insuficiencia aórtica ligera-moderada. Ritmo sinusal estable.Conclusionesaunque la vía transaórtica mediante cirugía mínimamente invasiva está aún poco utilizada, en pacientes con alto riesgo para cirugía convencional puede ser una opción factible y segura para el implante de prótesis transcatéter en las que no sea posible el abordaje habitual
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