36 research outputs found
Determinants for a low health-related quality of life in asthmatics
People with asthma suffer from impaired health-related quality of life (HRQL), but the determinants of HRQL among asthmatics are not completely understood. The aim of this investigation was to study determinants of low HRQL in asthmatics and to study whether the determinants of HRQL differ between sexes and age groups. A cohort of three age groups in Sweden was investigated in 1990 using a questionnaire with focus on respiratory symptoms. To study quality of life, the generic instrument Gothenburg Quality of Life was used. The participants were also investigated with interviews, spirometry, and allergy testing. Asthma was diagnosed in 616 subjects. Fifty-eight per cent (n = 359) of the subjects were women; and 24% were smokers, 22% ex-smokers, and 54% were non-smokers. Women were more likely than men to report poor health-related quality of life. Respiratory symptoms severity was another independent determinant of a lower quality of life as well as airway responsiveness to irritants. Current and former smokers also reported lower quality of life. Finally, absenteeism from school and work was associated with lower quality of life. Factors such as sex, smoking habits, airway responsiveness to irritants, respiratory symptom severity, allergy, and absenteeism from school and work were associated with low HRQL in asthmatics
Photometric Monitoring of Open Clusters I. The Survey
Open clusters, which have age, abundance, and extinction information from
studies of main-sequence turn off stars, are the ideal location in which to
determine the mass-luminosity-radius relation for low-mass stars. We have
undertaken a photometric monitoring survey of open clusters in the Galaxy
designed to detect low-mass eclipsing binary systems through variations in
their relative light curves. Our aim is to provide an improved calibration of
the mass-luminosity-radius relation for low-mass stars and brown dwarfs, to
test stellar structure and evolution models, and to help quantify the
contribution of low-mass stars to the global mass census in the Galaxy. In this
paper we present our survey, describing the data and outlining the analysis
techniques. We study six nearby open clusters, with a range of ages from to 4 Gyr and metallicities from approximately solar to -0.2dex. We monitor
a field-of-view of > 1 square degree per target cluster, well beyond the
characteristic cluster radius, over timescales of hours, days, and months with
a sampling rate optimised for the detection of eclipsing binaries with periods
of hours to days. Our survey depth is designed to detect eclipse events in a
binary with a primary star of \lesssim 0.3~M_{\sun}. Our data have a
photometric precision of mmag at .Comment: 50 pages, 18 figures, accepted for publication in A
Multi-wavelength polarimetric study towards the open cluster NGC 1893
We present multi-wavelength linear polarimetric observations for 44 stars of
the NGC 1893 young open cluster region along with V-band polarimetric
observations of stars of other four open clusters located between l ~160 to
~175 degree. We found evidence for the presence of two dust layers located at a
distance of ~170 pc and ~360 pc. The dust layers produce a polarization Pv
~2.2%. It is evident from the clusters studied in the present work that, in the
Galactic longitude range l ~160 to 175 degree and within the Galactic plane
(|b| < 2 degree), the polarization angles remain almost constant, with a mean
~163 degree and a dispersion of 6 degree. The small dispersion in polarization
angle could be due to the presence of uniform dust layer beyond 1 kpc. Present
observations reveal that in case of NGC 1893, the foreground two dust layers,
in addition to the intracluster medium, seems to be responsible for the
polarization effects. It is also found that towards the direction of NGC 1893,
the dust layer that exists between 2-3 kpc has a negligible contribution
towards the total observed polarization. The weighted mean for percentage of
polarization (Pmax) and the wavelength at maximum polarization ({\lambda}max)
are found to be 2.59 \pm 0.02% and 0.55 \pm 0.01 \mum respectively. The
estimated mean value of {\lambda}max indicates that the average size of the
dust grains within the cluster is similar to that in the general interstellar
medium. The spatial variation of the polarization is found to decrease towards
the outer region of the cluster. In the present work, we support the notion, as
already has been shown in previous studies, that polarimetry, in combination
with (U-B)/(B-V) colour-colour diagram, is a useful tool for identifying
non-members in a cluster.Comment: 36 pages, 12 figures, 10 tables, accepted for the publication in
MNRA
Optical Imaging of Nova Shells and the Maximum Magnitude-Rate of Decline Relationship
An optical imaging study of recent 30 novae has been undertaken using both
ground-based and space-based observations. Resolved shells have been detected
around 9 objects in the ground-based data, while another four objects have
shells detected by HST observations; for RW UMi, we fail to detect a shell
which was observed five years earlier. Images in H-alpha, and when appropriate
[O III], are shown, and finding charts for novae without shells are given if no
published chart is available. Expansion parallaxes for all systems with shells
are derived, and absolute magnitudes for a total of 28 objects are presented,
along with a discussion of the maximum magnitude-rate of decline relation. We
find that separate linear fits for fast and slow novae may be a better
representation of the data than a single, global fit. At minimum, most novae
have similar magnitudes as those of dwarf novae at maximum and novalike stars.Comment: 39 pages, 5 ps-figures, 13 jpg-figures. Accepted for publication in
the Astronomical Journal (October 2000