116 research outputs found
Very-wide-field camera. Proposal of Space Astronomy Laboratory for second Spacelab mission
A proposal is made for inclusion of a very wide field camera onboard Spacelab. Its scientific program is outlined: detection and photometry, spectrography, and star and starlike object photography. The optics, receptor, and mechanical structure are described. Scientific and technical constraints are discussed, and a development plan is detailed. The dust contamination of Spacelab using the camera was also studied
KH15D: a star eclipsed by a large scale dusty vortex?
We propose that the large photometric variations of KH15D are due to an
eclipsing swarm of solid particles trapped in giant gaseous vortex rotating at
\~0.2 AU from the star. The efficiency of the capture-in-vortex mechanism
easily explains the observed large optical depth. The weaker opacity at
mid-eclipse is consistent with a size segregation of the particles toward the
center of the vortex. This dusty structure must extend over ~1/3 of an orbit to
account for the long eclipse duration. The estimated size of the trapped
particles is found to range from 1 to 10cm, consistent with the gray extinction
of the star. The observations of KH15D support the idea that giant vortices can
grow in circumstellar disks and play a central role in planet formation.Comment: Accepted in ApJ Letters - 4 pages - 2 figure
Single and Composite Hot Subdwarf Stars in the Light of 2MASS Photometry
Utilizing the Two Micron All Sky Survey (2MASS) Second Incremental Data
Release Catalog, we have retrieved near-IR magnitudes for several hundred hot
subdwarfs (sdO and sdB stars) drawn from the "Catalogue of Spectroscopically
Identified Hot Subdwarfs" (Kilkenny, Heber, & Drilling 1988, 1992). This sample
size greatly exceeds that of previous studies of hot subdwarfs. Examining 2MASS
photometry alone or in combination with visual photometry (Johnson BV or
Stromgren uvby) available in the literature, we show that it is possible to
identify hot subdwarf stars that exhibit atypically red IR colors that can be
attributed to the presence of an unresolved late type companion. Utilizing this
large sample, we attempt for the first time to define an approximately volume
limited sample of hot subdwarfs. We discuss the considerations, biases, and
difficulties in defining such a sample.
We find that, of the hot subdwarfs in Kilkenny et al., about 40% in a
magnitude limited sample have colors that are consistent with the presence of
an unresolved late type companion. Binary stars are over-represented in a
magnitude limited sample. In an approximately volume limited sample the
fraction of composite-color binaries is about 30%.Comment: to appear in Sept 2003 AJ, 41 pages total, 12 figures, 2 tables are
truncated (full tables to appear in electronic journal or available by
request
Suivi sur dix années de l’évolution qualitative et quantitative de la marche d’une patiente atteinte d’une maladie de Charcot-Marie-Tooth et porteuse de chaussures orthopédiques
An assessment of patient satisfaction for a short-stay program in a physical and rehabilitation medicine day hospital
AbstractIntroductionThe aim of the Physical and Rehabilitation Medicine (PRM) day hospital's short-stay program is to propose a one- or two-day medical and psychosocial assessment to patients with disabilities. The day hospital is run by an interprofessional team, using interdisciplinary cooperation and a hospital/community network.ObjectivesTo describe a tool for assessing patient satisfaction and to present the results of our survey.Patients and methodsA self-administered questionnaire about patient satisfaction was created and given to patients coming to the PRM day hospital. The questionnaire included 27 multiple-choice questions, two visual analogic scales, and one free-response question. The survey was conducted over two months. For the 603 annual day hospital sessions, 143 questionnaires on 143 sessions were filled out.ResultsPatients found the questionnaire easy to use, but a few needed help to fill it out. It permitted us to highlight the places where the short-stay program performed unsatisfactorily.ConclusionsThe self-administered questionnaire seems to be appropriate for assessing patient satisfaction. The highest scores helped to emphasize where the program was functioning correctly, and the lowest scores allowed us to identify the points that needed to be improved
Large-Amplitude Ultraviolet Variations in the RR Lyrae Star ROTSE-I J143753.84+345924.8
The NASA Galaxy Evolution Explorer (GALEX) satellite has obtained
simultaneous near and far ultraviolet light curves of the ROTSE-I Catalog RR
Lyrae ab-type variable star J143753.84+345924.8. A series of 38 GALEX Deep
Imaging Survey observations well distributed in phase within the star's
0.56432d period shows an AB=4.9mag variation in the far UV (1350-1750A) band
and an AB=1.8mag variation in the near UV (1750-2750A) band, compared with only
a 0.8mag variation in the broad, unfiltered ROTSE-I (4500-10000A) band. These
GALEX UV observations are the first to reveal a large RR Lyrae amplitude
variation at wavelengths below 1800A. We compare the GALEX and ROTSE-I
observations to predictions made by recent Kurucz stellar atmosphere models. We
use published physical parameters for the comparable period (0.57433d),
well-observed RR Lyrae star WY Antliae to compute predicted FUV, NUV, and
ROTSE-I light curves for J143753.84+345924.8. The observed light curves agree
with the Kurucz predictions for [Fe/H]=-1.25 to within AB=0.2mag in the GALEX
NUV and ROTSE-I bands, and within 0.5mag in the FUV. At all metallicities
between solar and one hundredth solar, the Kurucz models predict 6-8mag of
variation at wavelengths between 1000-1700A. Other variable stars with similar
temperature variations, such as Cepheids, should also have large-amplitude FUV
light curves, observable during the ongoing GALEX imaging surveys.Comment: This paper will be published as part of the Galaxy Evolution Explorer
(GALEX) Astrophysical Journal Letters Special Issue. Links to the full set of
papers will be available at http:/www.galex.caltech.edu/PUBLICATIONS after
November 22, 200
Sensori-motor adaptation to knee osteoarthritis during stepping-down before and after total knee replacement
BACKGROUND: Stepping-down is preceded by a shift of the center of mass towards the supporting side and forward. The ability to control both balance and lower limb movement was investigated in knee osteoarthritis patients before and after surgery. It was hypothesized that pain rather than knee joint mobility affects the coordination between balance and movement control. METHODS: The experiment was performed with 25 adult individuals. Eleven were osteoarthritic patients with damage restricted to one lower limb (8 right leg and 3 left leg). Subjects were recruited within two weeks before total knee replacement by the same orthopedic surgeon using the same prosthesis and technics of surgery. Osteoarthritic patients were tested before total knee replacement (pre-surgery session) and then, 9 of the 11 patients were tested one year after the surgery when re-educative training was completed (post-surgery session). 14 adult individuals (men: n = 7 and women: n = 7) were tested as the control group. RESULTS: The way in which the center of mass shift forward and toward the supporting side is initiated (timing and amplitude) did not vary within patients before and after surgery. In addition knee joint range of motion of the leading leg remained close to normal before and after surgery. However, the relative timing between both postural and movement phases was modified for the osteoarthritis supporting leg (unusual strategy for stepping-down) before surgery. The "coordinated" control of balance and movement turned to be a "sequential" mode of control; once the body weight transfer has been completed, the movement onset is triggered. This strategy could be aimed at shortening the duration-time supporting on the painful limb. However no such compensatory response was observed. CONCLUSION: The change in the strategy used when supporting on the arthritis and painful limb could result from the action of nociceptors that lead to increased proprioceptor thresholds, thus gating the proprioceptive inputs that may be the critical afferents in controlling the timing of the coordination between balance and movement initiation control
The Unseen Population of F to K-type Companions to Hot Subdwarf Stars
We present a method to select hot subdwarf stars with A to M-type companions
using photometric selection criteria. We cover a wide range in wavelength by
combining GALEX ultraviolet data, optical photometry from the SDSS and the
Carlsberg Meridian telescope, near-infrared data from 2MASS and UKIDSS. We
construct two complimentary samples, one by matching GALEX, CMC and 2MASS, as
well as a smaller, but deeper, sample using GALEX, SDSS and UKIDSS. In both
cases, a large number of composite subdwarf plus main-sequence star candidates
were found. We fit their spectral energy distributions with a composite model
in order to estimate the subdwarf and companion star effective temperatures
along with the distance to each system. The distribution of subdwarf effective
temperature was found to primarily lie in the 20,000 - 30,000 K regime, but we
also find cooler subdwarf candidates, making up ~5-10 per cent. The most
prevalent companion spectral types were seen to be main-sequence stars between
F0 and K0, while subdwarfs with M-type companions appear much rarer. This is
clear observational confirmation that a very efficient first stable Roche-lobe
overflow channel appears to produce a large number of subdwarfs with F to
K-type companions. Our samples thus support the importance of binary evolution
for subdwarf formation.Comment: 30 pages, 10 figures, 11 tables. Accepted for publication in MNRA
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