7,859 research outputs found
X-ray burst induced spectral variability in 4U 1728-34
Aims. INTEGRAL has been monitoring the Galactic center region for more than a
decade. Over this time INTEGRAL has detected hundreds of type-I X-ray bursts
from the neutron star low-mass X-ray binary 4U 1728-34, a.k.a. "the slow
burster". Our aim is to study the connection between the persistent X-ray
spectra and the X-ray burst spectra in a broad spectral range. Methods. We
performed spectral modeling of the persistent emission and the X-ray burst
emission of 4U 1728-34 using data from the INTEGRAL JEM-X and IBIS/ISGRI
instruments. Results. We constructed a hardness intensity diagram to track
spectral state variations. In the soft state the energy spectra are
characterized by two thermal components - likely from the accretion disc and
the boundary/spreading layer - together with a weak hard X-ray tail that we
detect in 4U 1728-34 for the first time in the 40 to 80 keV range. In the hard
state the source is detected up to 200 keV and the spectrum can be described by
a thermal Comptonization model plus an additional component: either a powerlaw
tail or reflection. By stacking 123 X-ray bursts in the hard state, we detect
emission up to 80 keV during the X-ray bursts. We find that during the bursts
the emission above 40 keV decreases by a factor of about three with respect to
the persistent emission level. Conclusions. Our results suggest that the
enhanced X-ray burst emission changes the spectral properties of the accretion
disc in the hard state. The likely cause is an X-ray burst induced cooling of
the electrons in the inner hot flow near the neutron star.Comment: 7 pages, 5 figures, Accepted for publication in A&
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
Acceptance of an Augmented Reality system as a visualization tool for Computer-Aided Design classes
This paper presents a study conducted with nineteen students from the Technical University of Catalonia. The study examines user experience and acceptance of an Augmented Reality (AR) system as a visualization tool for Computer-Aided Design (CAD) classes. Although results showed that AR does not improve the learning of CAD techniques, students mentioned that they would find it useful and interesting to continue using AR in CAD lectures. They said that AR helps them to easily understand the forms and volumes of objects and better comprehend the location of objects in the space and its relations with others.This paper presents a study conducted with nineteen students from the Technical University of Catalonia. The study examines user experience and acceptance of an Augmented Reality (AR) system as a visualization tool for Computer-Aided Design (CAD) classes. Although results showed that AR does not improve the learning of CAD techniques, students mentioned that they would find it useful and interesting to continue using AR in CAD lectures. They said that AR helps them to easily understand the forms and volumes of objects and better comprehend the location of objects in the space and its relations with others
The High-Frequency QPOs in GRS 1915+105
We analyzed two 1996 observations of the Galactic Microquasar GRS 1915+105 taken with the Proportional Counter Array on board the Rossi X-ray Timing Explorer. We focus on the properties of the high-frequency QPO as a function of the `dip' oscillations, a factor of 1000 slower. In one observation, 1996 May 5th, we find that the energy spectrum of the QPO at ~65 Hz changes drastically between the high-intervals and the dips, hardening during the dips to the point that the QPO peak is no longer detected at low energies. In the second observation, 1996 May 14th, although it has similar overall characteristics, the 65 Hz QPO is not seen, but another broader QPO peak appears at 27 Hz, only during the dips. This peak is too weak to obtain reliable information about its spectrum. Our results indicate that the presence/absence of high-frequency features in this enigmatic source are intimately linked to the slower oscillations and variations that happen on longer time scales
Cross-species tests of 45 microsatellite loci isolated from different species of ungulates in the Iberian red deer (Cervus elaphus hispanicus) to generate a multiplex panel
The Iberian red deer (Cervus elaphus hispanicus) is an emblematic game species in Spain. To generate a battery of polymorphic markers for multiplex polymerase chain reactions for the Spanish red deer, 45 loci isolated in different species of ungulates were tested. Of the primers tested, 27 amplified but only 21 were polymorphic. Eleven of these markers were subsequently optimized for multiplex in four polymerase chain reactions. This allows analysing several molecular markers jointly to substantially reduce costs. Finally, we report descriptive summary statistics such as number of alleles for the former and also test of disequilibria and heterozygosity for the latter. © 2008 The Authors.Peer Reviewe
Acceptance of an Augmented Reality system as a visualization tool for Computer-Aided Design classes
This paper presents a study conducted with nineteen students from the Technical University of Catalonia. The study examines user experience and acceptance of an Augmented Reality (AR) system as a visualization tool for Computer-Aided Design (CAD) classes. Although results showed that AR does not improve the learning of CAD techniques, students mentioned that they would find it useful and interesting to continue using AR in CAD lectures. They said that AR helps them to easily understand the forms and volumes of objects and better comprehend the location of objects in the space and its relations with others.This paper presents a study conducted with nineteen students from the Technical University of Catalonia. The study examines user experience and acceptance of an Augmented Reality (AR) system as a visualization tool for Computer-Aided Design (CAD) classes. Although results showed that AR does not improve the learning of CAD techniques, students mentioned that they would find it useful and interesting to continue using AR in CAD lectures. They said that AR helps them to easily understand the forms and volumes of objects and better comprehend the location of objects in the space and its relations with others
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