3,389 research outputs found
The Peculiar Balmer Line Profiles of OQ 208
We present spectrophotometric observations of the Broad Line Radio Galaxy OQ
208 (Mrk 668, 1404+286) obtained between 1985 and 1991. We show that the Balmer
line fluxes and profile shapes undergo remarkable changes. The ratio of
intensities between the broad and narrow components of Hbeta increased
monotonically from 15 in 1985 to 40 in 1991. The peak of the broad components
of Hbeta and Halpha were known to be strongly displaced to the red. We have
discovered a correlation between the amplitude of the broad peak displacement
and the luminosity of Hbeta, in the sense that the displacement is larger when
the line luminosity is higher. We suggest that the observations are not
compatible with either a binary Broad Line Region model or one involving
ballistic acceleration of the line emitting gas. Radiative acceleration of a
system of outflowing clouds readily explains the correlation between line shift
and luminosity as well as the peculiar line profiles. Furthermore, it seems
that most or all of the Balmer emission originates from the inward face of the
clouds. Theoretical line profiles suggest that the observed Hbeta profile is
best fit assuming the contribution of an ensemble which might be spherical or
confined in a thick disk in addition to a component emitted in a thin shell
contained in a cone of half opening angle 12 degrees seen along its axis.Comment: 28 pages + tables and figures available upon request, Latex, No
preprint numbe
Near-infrared photometry of isolated spirals with and without an AGN. I: The Data
We present infrared imaging data in the J and K' bands obtained for 18 active
spiral galaxies, together with 11 non active galaxies taken as a control
sample. All of them were chosen to satisfy well defined isolation criteria so
that the observed properties are not related to gravitational interaction. For
each object we give: the image in the K' band, the sharp-divided image
(obtained by dividing the observed image by a filtered one), the difference
image (obtained by subtracting a model to the observed one), the color J-K'
image, the ellipticity and position angle profiles, the surface brightness
profiles in J and K', their fits by bulge+disk models and the color gradient.
We have found that four (one) active (control) galaxies previously classified
as non-barred turn out to have bars when observed in the near-infrared. One of
these four galaxies (UGC 1395) also harbours a secondary bar. For 15 (9 active,
6 control) out of 24 (14 active, 10 control) of the optically classified barred
galaxies (SB or SX) we find that a secondary bar (or a disk, a lense or an
elongated ring) is present. The work presented here is part of a large program
(DEGAS) aimed at finding whether there are differences between active and non
active galaxies in the properties of their central regions that could be
connected with the onset of nuclear activity.Comment: Accepted for publication in Astronomy & Astrophysics Supplement
Serie
The WINGS Survey: a progress report
A two-band (B and V) wide-field imaging survey of a complete, all-sky X-ray
selected sample of 78 clusters in the redshift range z=0.04-0.07 is presented.
The aim of this survey is to provide the astronomical community with a complete
set of homogeneous, CCD-based surface photometry and morphological data of
nearby cluster galaxies located within 1.5 Mpc from the cluster center. The
data collection has been completed in seven observing runs at the INT and
ESO-2.2m telescopes. For each cluster, photometric data of about 2500 galaxies
(down to V~23) and detailed morphological information of about 600 galaxies
(down to V~21) are obtained by using specially designed automatic tools.
As a natural follow up of the photometric survey, we also illustrate a long
term spectroscopic program we are carrying out with the WHT-WYFFOS and AAT-2dF
multifiber spectrographs. Star formation rates and histories, as well as
metallicity estimates will be derived for about 350 galaxies per cluster from
the line indices and equivalent widths measurements, allowing us to explore the
link between the spectral properties and the morphological evolution in high-
to low-density environments, and across a wide range in cluster X-ray
luminosities and optical properties.Comment: 12 pages, 10 eps figures, Proceedings of the SAIt Conference 200
On the use of scaling relations for the Tolman test
The use of relations between structural parameters of early type galaxies to
perform the Tolman test is reconsidered. Scaling relations such as the FP or
the Kormendy relation, require the transformation from angular to metric sizes,
to compare the relation at different z values. This transformation depends on
the assumed world model: galaxies of a given angular size, at a given z, are
larger (in kpc) in a non-expanding universe than in an expanding one.
Furthermore, the luminosities of galaxies are expected to evolve with z in an
expanding model. These effects are shown to conspire to reduce the difference
between the predicted SB change with redshift in the expanding and non
expanding cases. We find that the predictions for the visible photometric bands
of the expanding models with passive luminosity evolution are very similar to
those of the static model till z about 1, and therefore, the test cannot
distinguish between the two world models. Recent good quality data are
consistent with the predictions from both models. In the K-band, where the
expected (model) luminosity evolutionary corrections are smaller, the
differences between the xpanding and static models amount to about 0.4 (0.8)
magnitudes at z = 0.4 (1). It is shown that, due to that small difference
between the predictions in the covered z-range, and to the paucity and
uncertainties of the relevant SB photometry, the existing K-band data is not
adequate to distinguish between the different world metrics, and cannot be yet
used to discard the static case. It is pointed out that the scaling relations
could still be used to rule out the non-evolving case if it could be shown that
the coefficients change with the redshift.Comment: Latex, 15 pages with 2 figures. To be published in ApJ Letter
Patient-centred care in general dental practice--a systematic review of the literature.
Journal ArticleResearch Support, Non-U.S. Gov'tReviewBACKGROUND: Delivering improvements in quality is a key objective within most healthcare systems, and a view which has been widely embraced within the NHS in the United Kingdom. Within the NHS, quality is evaluated across three key dimensions: clinical effectiveness, safety and patient experience, with the latter modelled on the Picker Principles of Patient-Centred Care (PCC). Quality improvement is an important feature of the current dental contract reforms in England, with "patient experience" likely to have a central role in the evaluation of quality. An understanding and appreciation of the evidence underpinning PCC within dentistry is highly relevant if we are to use this as a measure of quality in general dental practice. METHODS: A systematic review of the literature was undertaken to identify the features of PCC relevant to dentistry and ascertain the current research evidence base underpinning its use as a measure of quality within general dental practice. RESULTS: Three papers were identified which met the inclusion criteria and demonstrated the use of primary research to provide an understanding of the key features of PCC within dentistry. None of the papers identified were based in general dental practice and none of the three studies sought the views of patients. Some distinct differences were noted between the key features of PCC reported within the dental literature and those developed within the NHS Patient Experience Framework. CONCLUSIONS: This systematic review reveals a lack of understanding of PCC within dentistry, and in particular general dental practice. There is currently a poor evidence base to support the use of the current patient reported outcome measures as indicators of patient-centredness. Further research is necessary to understand the important features of PCC in dentistry and patients' views should be central to this research.NIH
Patient-centred care in general dental practice--a systematic review of the literature.
BACKGROUND: Delivering improvements in quality is a key objective within most healthcare systems, and a view which has been widely embraced within the NHS in the United Kingdom. Within the NHS, quality is evaluated across three key dimensions: clinical effectiveness, safety and patient experience, with the latter modelled on the Picker Principles of Patient-Centred Care (PCC). Quality improvement is an important feature of the current dental contract reforms in England, with "patient experience" likely to have a central role in the evaluation of quality. An understanding and appreciation of the evidence underpinning PCC within dentistry is highly relevant if we are to use this as a measure of quality in general dental practice. METHODS: A systematic review of the literature was undertaken to identify the features of PCC relevant to dentistry and ascertain the current research evidence base underpinning its use as a measure of quality within general dental practice. RESULTS: Three papers were identified which met the inclusion criteria and demonstrated the use of primary research to provide an understanding of the key features of PCC within dentistry. None of the papers identified were based in general dental practice and none of the three studies sought the views of patients. Some distinct differences were noted between the key features of PCC reported within the dental literature and those developed within the NHS Patient Experience Framework. CONCLUSIONS: This systematic review reveals a lack of understanding of PCC within dentistry, and in particular general dental practice. There is currently a poor evidence base to support the use of the current patient reported outcome measures as indicators of patient-centredness. Further research is necessary to understand the important features of PCC in dentistry and patients' views should be central to this research
Long slit spectroscopy of a sample of isolated spirals with and without an AGN
We present the kinematical data obtained for a sample of active (Seyfert) and
non active isolated spiral galaxies, based on long slit spectra along several
position angles in the Halpha line region and, in some cases, in the Ca triplet
region as well. Gas velocity distributions are presented, together with a
simple circular rotation model that allows to determine the kinematical major
axes. Stellar velocity distributions are also shown. The main result is that
active and control galaxies seem to be equivalent in all kinematical aspects.
For both subsamples, the departure from pure circular rotation in some galaxies
can be explained by the presence of a bar and/or of a spiral arm. They also
present the same kind of peculiarities, in particular, S-shape structures are
quite common near the nuclear regions. They define very similar Tully-Fisher
relations. Emission line ratios are given for all the detected HII regions; the
analysis of the [NII]/Halpha metallicity indicator shows that active and
non-active galaxies have indistinguishable disk metallicities. These results
argue in favour of active and non-active isolated spiral galaxies having
essentially the same properties, in agreement with our previous results based
on the analysis of near infrared images. It appears now necessary to confirm
these results on a larger sample.Comment: 35 pages, 54 figures, Accepted for publication in Astronomy &
Astrophysics The full paper with its figures is available on the anonymous
account of ftp.iap.fr in /home/ftp/pub/from_users/durret/marquez.ps.gz (999
kb
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