172 research outputs found
Les étudiant·e·s en médecine mènent une recherche dans La communauté. [Male/female medical students conduct research in the community]
Pendant quatre semaines, les étudiant(e)s en médecine de 3e année de l'Université de Lausanne mènent une enquête dans la communauté sur le sujet de leur choix. L'objectif de ce module est de faire découvrir aux futurs médecins les déterminants non biomédicaux de la santé, de la maladie et de l'exercice de la médecine : les styles de vie, les facteurs psychosociaux et culturels, l'environnement, les décisions politiques, les contraintes économiques, les questions éthiques, etc.
Par groupes de cinq, les étudiant(e)s commencent par définir une question de recherche originale et en explorent la littérature scientifique. Leur travail de recherche les amène à entrer en contact avec le réseau d'acteurs de la communauté concernés, professionnels ou associations de patients dont ils analysent les rôles et influences respectives. Chaque groupe est accompagné par un(e) tuteur(trice), enseignant(e) de la Faculté de biologie et de médecine de l'Université de Lausanne. Les étudiant(e)s présentent la synthèse de leurs travaux pendant un congrès de deux jours à la fin du module. Quatre travaux parmi les plus remarquables ont été choisis pour être publiés dans la Revue Médicale Suisse et Primary Care
Mira's wind explored in scattering infrared CO lines
We have observed the intermediate regions of the circumstellar envelope of
Mira (o Ceti) in photospheric light scattered by three vibration-rotation
transitions of the fundamental band of CO, from low-excited rotational levels
of the ground vibrational state, at an angular distance of beta = 2"-7" away
from the star. The data were obtained with the Phoenix spectrometer mounted on
the 4 m Mayall telescope at Kitt Peak. The spatial resolution is approximately
0.5" and seeing limited. Our observations provide absolute fluxes, leading to
an independent new estimate of the mass-loss rate of approximately 3e-7
Msun/yr, as derived from a simple analytic wind model. We find that the
scattered intensity from the wind of Mira for 2" < beta < 7" decreases as
beta^-3, which suggests a time constant mass-loss rate, when averaged over 100
years, over the past 1200 years.Comment: accepted for publication in the Astrophysical Journa
The hot core-ultracompact HII connection in G10.47+0.03
We present infrared imaging and spectroscopic data of the complex massive
star-forming region G10.47+0.03. The detection of seven mid-infrared (MIR)
sources in our field combined with a sensitive Ks/ISAAC image allows to
establish a very accurate astrometry, at the level of 0.3". Two MIR sources are
found to be coincident with two ultracompact HII regions (UCHIIs) within our
astrometric accuracy. Another MIR source lies very close to three other UCHII
regions and to the hot molecular core (HMC) in G10.47+0.03. Spectroscopy of two
of the most interesting MIR sources allows to identify the location and
spectral type of the ionizing sources. We discuss in detail the relationship
between the HMC, the UCHII regions and the nearby MIR source. The nature of the
other MIR sources is also investigated.Comment: 12 pages, 5 figures, Accepted by Astronomy and Astrophysic
Multiple Sources toward the High-mass Young Star S140 IRS1
S140 IRS1 is a remarkable source where the radio source at the center of the
main bipolar molecular outflow in the region is elongated perpendicular to the
axis of the outflow, an orientation opposite to that expected if the radio
source is a thermal jet exciting the outflow. We present results of 1.3 cm
continuum and H2O maser emission observations made with the VLA in its A
configuration toward this region. In addition, we also present results of
continuum observations at 7 mm and re-analyse observations at 2, 3.5 and 6 cm
(previously published). IRS 1A is detected at all wavelengths, showing an
elongated structure. Three water maser spots are detected along the major axis
of the radio source IRS 1A. We have also detected a new continuum source at 3.5
cm (IRS 1C) located ~0.6'' northeast of IRS 1A. The presence of these two YSOs
(IRS 1A and 1C) could explain the existence of the two bipolar molecular
outflows observed in the region. In addition, we have also detected three
continuum clumps (IRS 1B, 1D and 1E) located along the major axis of IRS 1A. We
discuss two possible models to explain the nature of IRS 1A: a thermal jet and
an equatorial wind.Comment: 17 pages, 4 figures, to be published in A
The 3-D kinematics of water masers around the semiregular variable RT Virginis
We report observations of water masers around the semiregular variable RT
Virginis (RT Vir), which have been made with the Very Long Baseline Array
(VLBA) of the National Radio Astronomy Observatory (NRAO) at five epochs, each
separated by three weeks of time. We detected about 60 maser features at each
epoch. Overall, 61 features, detected at least twice, were tracked by their
radial velocities and proper motions. The 3-D maser kinematics exhibited a
circumstellar envelope that is expanding roughly spherically with a velocity of
about 8 km/s. Asymmetries in both the spatial and velocity distributions of the
maser features were found in the envelope, but less significant than that found
in other semiregular variables. Systematic radial-velocity drifts of individual
maser features were found with amplitudes of <= 2 km/s/yr. For one maser
feature, we found a quadratic position shift with time along a straight line on
the sky. This apparent motion indicates an acceleration with an amplitude of 33
km/s/yr, implying the passage of a shock wave driven by the stellar pulsation
of RT Vir. The acceleration motion is likely seen only on the sky plane because
of a large velocity gradient formed in the accelerating maser region. We
estimated the distance to RT Vir to be about 220 pc on the basis of both the
statistical parallax and model-fitting methods for the maser kinematics.Comment: 18 pages, 8 figures. Accepted to appear in the Astrophysical Journa
The G9.62+0.19-F Hot Molecular Core - The infrared view on very young massive stars
(abridged) We present the results of an extensive infrared study of the
massive star-forming region G9.62+0.19. The data cover information from broad-
and narrow-band filters in the wavelength range from 1 to 19 micrometer and are
obtained with ESO's infrared cameras ISAAC and TIMMI2 and with SpectroCam-10
(Mt. Palomar). The high sensitivity and resolution provided by these facilities
revealed intriguing new details of this star-forming region and especially
about the embedded hot molecular core (HMC) - component F. We analyse the newly
found infrared sub-structure of four objects in this HMC region. While one of
these objects (F2) is probably a foreground field star, the nature of the
brightest object in the near-infrared there (F1) remains somewhat enigmatic.
Our new astrometry proves that this object is not coincident with the peak of
the molecular line emission of the HMC, but displaced by 1.7 arcsecs (nearly
10000 AU on a linear scale). We estimate this object to be an additional
embedded object with a dense dust shell. Very near the HMC location we find L'
band emission which strongly rises in flux towards longer wavelengths. We
presume that this emission (F4) arises from the envelope of the HMC which is
known to be associated with a molecular outflow roughly aligned along the line
of sight. Thus, the clearing effect of this outflow causes strong deviations
from spherical symmetry which might allow infrared emission from the HMC to
escape through the outflow cavities. This presents the first direct detection
of an HMC at a wavelength as short as 3.8 micron. At 11.7 and 18.75 micron, the
HMC counterpart F4 ultimately proves to be the most luminous IR source within
the G9.62+0.19-F region.Comment: 39 pages, 10 figures, accepted for publication in Astronomy &
Astrophysics. The paper contains several colour images. It is highly
advisable to go to the following website to get a high-resolution version of
this preprint:
http://www.tls-tautenburg.de/research/tls-research/papers/linz/G9.62.htm
Interpreting the Mg II h and k Line Profiles of Mira Variables
We use radiative transfer calculations to reproduce the basic appearance of
Mg II lines observed from Mira variables. These lines have centroids that are
blueshifted by at least 30 km/s from the stellar rest frame. It is unlikely
that flow velocities in the stellar atmospheres are this fast, so radiative
transfer effects must be responsible for this behavior. Published hydrodynamic
models predict the existence of cool, downflowing material above the shocked
material responsible for the Mg II emission, and we demonstrate that scattering
in this layer can result in Mg II profiles as highly blueshifted as those that
are observed. However, our models also show that scattering within the shock
plays an equally strong role in shaping the Mg II profiles, and our
calculations illustrate the importance of partial redistribution and the
effects of being out of ionization equilibrium.Comment: 14 pages, 3 figures; AASTEX v5.0 plus EPSF extensions in mkfig.sty;
to appear in Ap
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