671 research outputs found
ESO Imaging survey: Optical Deep Public Survey
This paper presents new five passbands (UBVRI) optical wide-field imaging
data accumulated as part of the DEEP Public Survey (DPS) carried out as a
public survey by the ESO Imaging Survey (EIS) project. Out of the 3 square
degrees originally proposed, the survey covers 2.75 square degrees, in at least
one band (normally R), and 1.00 square degrees in five passbands. The median
seeing, as measured in the final stacked images, is 0.97", ranging from 0.75"
to 2.0". The median limiting magnitudes (AB system, 2" aperture, 5 sigma
detection limit) are U_(AB)=25.65, B_(AB)=25.54, V_(AB)=25.18, R_(AB) = 24.8
and I_(AB)=24.12 mag, consistent with those proposed in the original survey
design. The paper describes the observations and data reduction using the EIS
Data Reduction System and its associated EIS/MVM library. The quality of the
individual images were inspected, bad images discarded and the remaining used
to produce final image stacks in each passband, from which sources have been
extracted. Finally, the scientific quality of these final images and associated
catalogs was assessed qualitatively by visual inspection and quantitatively by
comparison of statistical measures derived from these data with those of other
authors as well as model predictions, and from direct comparison with the
results obtained from the reduction of the same dataset using an independent
(hands-on) software system. Finally to illustrate one application of this
survey, the results of a preliminary effort to identify sub-mJy radio sources
are reported. To the limiting magnitude reached in the R and I passbands the
success rate ranges from 66 to 81% (depending on the fields). These data are
publicly available at CDS.Comment: 24 pages, 26 figures. Accepted for pubblication in A&
The First VLT FORS1 spectra of Lyman-break candidates in the HDF-S and AXAF Deep Field
We report on low-resolution multi-object spectroscopy of 30 faint targets (R
\~ 24-25) in the HDF-S and AXAF deep field obtained with the VLT Focal
Reducer/low dispersion Spectrograph (FORS1). Eight high-redshift galaxies with
2.75< z < 4 have been identified. The spectroscopic redshifts are in good
agreement with the photometric ones with a dispersion at z<2
and at z>2. The inferred star formation rates of the
individual objects are moderate, ranging from a few to a few tens solar masses
per year. Five out of the eight high-z objects do not show prominent emission
lines. One object has a spectrum typical of an AGN. In the AXAF field two
relatively close pairs of galaxies have been identified, with separations of
8.7 and 3.1 proper Mpc and mean redshifts of 3.11 and 3.93, respectively.Comment: 5 pages Latex, with 2 PostScript figures. Astronomy and Astrophysics,
in pres
A refined stable restriction theorem for vector bundles on quadric threefolds
Let E be a stable rank 2 vector bundle on a smooth quadric threefold Q in the
projective 4-space P. We show that the hyperplanes H in P for which the
restriction of E to the hyperplane section of Q by H is not stable form, in
general, a closed subset of codimension at least 2 of the dual projective
4-space, and we explicitly describe the bundles E which do not enjoy this
property. This refines a restriction theorem of Ein and Sols [Nagoya Math. J.
96, 11-22 (1984)] in the same way the main result of Coanda [J. reine angew.
Math. 428, 97-110 (1992)] refines the restriction theorem of Barth [Math. Ann.
226, 125-150 (1977)].Comment: Ann. Mat. Pura Appl. 201
The XXL Survey VII: A supercluster of galaxies at z=0.43
The XXL Survey is the largest homogeneous and contiguous survey carried out
with XMM-Newton. Covering an area of 50 square degrees distributed over two
fields, it primarily investigates the large-scale structures of the Universe
using the distribution of galaxy clusters and active galactic nuclei as tracers
of the matter distribution. Given its depth and sky coverage, XXL is
particularly suited to systematically unveiling the clustering of X-ray
clusters and to identifying superstructures in a homogeneous X-ray sample down
to the typical mass scale of a local massive cluster. A friends-of-friends
algorithm in three-dimensional physical space was run to identify large-scale
structures. In this paper we report the discovery of the highest redshift
supercluster of galaxies found in the XXL Survey. We describe the X-ray
properties of the clusters members of the structure and the optical follow-up.
The newly discovered supercluster is composed of six clusters of galaxies at a
median redshift z around 0.43 and distributed across approximately 30 by 15 arc
minutes (10 by 5 Mpc on sky) on the sky. This structure is very compact with
all the clusters residing in one XMM pointing; for this reason this is the
first supercluster discovered with the XXL Survey. Spectroscopic follow-up with
WHT (William Herschel Telescope) and NTT (New Technology Telescope) confirmed a
median redshift of z = 0.43. An estimate of the X-ray mass and luminosity of
this supercluster and of its total gas mass put XLSSC-e at the average mass
range of superclusters; its appearance, with two members of equal size, is
quite unusual with respect to other superclusters and provides a unique view of
the formation process of a massive structure.Comment: A&A, accepted; special XXL issu
Ăvaluation des compĂ©tences pratiques en fin de deuxiĂšme cycle des Ă©tudes mĂ©dicales : exemple du drainage du bas appareil urinaire
IntroductionLe drainage vĂ©sical peut, mal pratiquĂ©, ĂȘtre iatrogĂšne en se compliquant notamment dâinfections et de traumatismes de lâappareil urinaire. Cette Ă©tude a pour objectif de dĂ©terminer la capacitĂ© des Ă©tudiants en mĂ©decine de fin de deuxiĂšme cycle Ă pratiquer les diffĂ©rents moyens de drainage des urines. MatĂ©riel et mĂ©thodes Entre janvier et mars 2007, un questionnaire dâautoĂ©valuation des compĂ©tences de drainage urinaire a Ă©tĂ© envoyĂ© par mail Ă un Ă©chantillon reprĂ©sentatif dâĂ©tudiants en mĂ©decine en derniĂšre annĂ©e dâexternat, soit deux mois avant lâĂ©preuve de lâexamen national classant. RĂ©sultats Deux cent soixante-dix-sept rĂ©ponses ont Ă©tĂ© reçues et analysĂ©es. Soixante-douze Ă©tudiants (26 %) jugeaient quâils maĂźtrisaient le cathĂ©tĂ©risme urĂ©trovĂ©sical chez lâhomme et 106 Ă©tudiants (38,3 %) chez la femme Ă la fin de leur externat. Soixante et onze Ă©tudiants sur les 277 (25,5 %) avaient effectuĂ© un stage en urologie au cours de leur cursus. Parmi eux, 53,5 % estimaient acquis le sondage Ă demeure (SAD) chez lâhomme (p < 0,001) et 39 (54,9 %) chez la femme (p < 0,001). Soixante-treize Ă©tudiants (26,4 %) estimaient quâils maĂźtrisaient le sondage minute dâune femme ou dâun homme et un seul considĂ©rait la pose de cathĂ©ter sus-pubien comme acquis. Conclusion Lâapprentissage des gestes de drainage urinaire est enseignĂ© de façon inappropriĂ©e au cours des Ă©tudes mĂ©dicales puisque de jeunes mĂ©decins se sentent incapables de les reproduire au terme de leur externat. Cela est critiquable, car le sondage doit pouvoir ĂȘtre rĂ©alisĂ© par tous mĂ©decins non urologues dans leur pratique quotidienne, notamment en terrain hospitalier. Cette Ă©tude doit mener Ă une rĂ©flexion sur lâamĂ©lioration de lâenseignement des gestes pratiques mĂ©dicaux essentiels pendant lâexternat
Vortex matter in superconducting mesoscopic disks: Structure, magnetization, and phase transitions
The dense vortex matter structure and associated magnetization are calculated
for type-II superconducting mesoscopic disks. The magnetization exhibits
generically first-order phase transitions as the number of vortices changes by
one and presents two well-defined regimes: A non-monotonous evolution of the
magnitude of the magnetization jumps signals the presence of a vortex glass
structure which is separated by a second-order phase transition at
from a condensed state of vortices (giant vortex) where the magnitude of the
jumps changes monotonously. We compare our results with Hall magnetometry
measurements by Geim et al. (Nature 390, 259 (1997)) and claim that the
magnetization exhibits clear traces of the presence of these vortex glass
states.Comment: 4 pages, 3 figure
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