186 research outputs found
A randomized, open-label study comparing low-dose clevudine plus adefovir combination therapy with clevudine monotherapy in naïve chronic hepatitis B patients
PURPOSE: Clevudine 30 mg showed potent antiviral activity with a marked post-treatment antiviral effect. However, long-term treatment with clevudine monotherapy induced resistance and myopathy in some cases. The objective of this study is to evaluate the preliminary efficacy and safety of the combination of clevudine 20 mg and adefovir compared to clevudine monotherapy. METHODS: Seventy-four patients were randomized to either a combination of clevudine 20 mg and adefovir or clevudine 20 or 30 mg and were treated for 2 years. The viral kinetics for 24 weeks, virological response [VR; hepatitis B virus (HBV) DNA less than 300 copies/ml], and the biochemical response [BR; normal alanine aminotransferase (ALT)] were assessed. RESULTS: There was no difference in baseline characteristics among the three groups. Viral kinetics study showed no statistically significant difference among them during 24 weeks. The combination group showed 95 % virological response with a statistically significant difference compared to the clevudine 30 mg (67 %) and 20 mg (71 %) groups (p = 0.0376). Biochemical response rates were similar in all groups (78–94 %). No resistance was reported in the combination group, while 20 % of patients treated with clevudine 30 mg or 20 mg reported resistance during 2 years. Muscle-related symptoms such as myalgia (1 in clevudine 30 mg, 1 in the combination group) and muscle weakness (1 in clevudine 30 mg, 2 in clevudine 20 mg) were reported in five patients (7 %); of these, three patients discontinued the study. CONCLUSION: We concluded that the combination of clevudine 20 mg and adefovir produced a potent antiviral response together with a good resistance profile compared to clevudine monotherapy at 96 weeks in this pilot study
Unusual Thymic Hyperplasia Mimicking Lipomatous Tumor in an Eight-Year-Old Boy with Concomitant Pericardial Lipomatosis and Right Facial Hemihypertrophy
We report a case of thymic hyperplasia accompanied by pericardial lipomatosis and right facial hemihypertrophy in an 8-year-old boy. On imaging studies, the hyperplastic thymus had prominent curvilinear and nodular fatty areas simulating a fat-containing anterior mediastinal mass, which is an unusual finding in children. To our knowledge, this is the first report on a child with a combination of thymic hyperplasia, pericardial lipomatosis, and right facial hemihypertrophy. The radiologic findings are presented with a brief discussion
Discs in early-type lensing galaxies: effects on magnification ratios and measurements of
Observations of early-type galaxies, both in the local universe and in
clusters at medium redshifts, suggest that these galaxies often contain discs
or disc-like structures. Using the results of Kelson et al. (2000) for the
incidence of disc-components among the galaxies in the redshift z=0.33 cluster
CL 1358+62, we investigate the effect of disc structures on the lensing
properties of early-type galaxies. Statistical properties, like magnification
cross sections and the expected number of quad (four-image) lens systems, are
not affected greatly by the inclusion of discs that contain less than about 10
per cent of the total stellar mass. However, the properties of individual lens
systems are affected. We estimate that 10-30 per cent of all quad lens systems,
with early-type deflector galaxies, would be affected measurably by the
presence of disc components. Intriguingly, the image magnification ratios are
altered significantly. The amplitude of the predicted change is sufficient to
explain the observed magnification ratios in systems like B1422+231 without
requiring compact substructure. Furthermore, time delays between images also
change; fitting a bulge-only model to early-type lenses that in fact contain a
disc would yield a value of the Hubble constant H_0 that is systematically too
low by about 25 per cent.Comment: Accepted for publication in MNRAS. 17 pages, 14 figures, 3 tables.
Mainly minor changes to submitted version. Includes a more extended
discussion on evidence of discs from light profile
Scalelength of disc galaxies
We have derived disk scale lengths for 30374 non-interacting disk galaxies in
all five SDSS bands. Virtual Observatory methods and tools were used to define,
retrieve, and analyse the images for this unprecedentedly large sample
classified as disk/spiral galaxies in the LEDA catalogue. Cross correlation of
the SDSS sample with the LEDA catalogue allowed us to investigate the variation
of the scale lengths for different types of disk/spiral galaxies. We further
investigat asymmetry, concentration, and central velocity dispersion as
indicators of morphological type, and are able to assess how the scale length
varies with respect to galaxy type. We note however, that the concentration and
asymmetry parameters have to be used with caution when investigating type
dependence of structural parameters in galaxies. Here, we present the scale
length derivation method and numerous tests that we have carried out to
investigate the reliability of our results. The average r-band disk scale
length is 3.79 kpc, with an RMS dispersion of 2.05 kpc, and this is a typical
value irrespective of passband and galaxy morphology, concentration, and
asymmetry. The derived scale lengths presented here are representative for a
typical galaxy mass of , and the RMS dispersion
is larger for more massive galaxies. Distributions and typical trends of scale
lengths have also been derived in all the other SDSS bands with linear
relations that indicate the relation that connect scale lengths in one passband
to another. Such transformations could be used to test the results of
forthcoming cosmological simulations of galaxy formation and evolution of the
Hubble sequence.Comment: Accepter for publication in MNRAS (15 pages, 15 figures, and 3
tables
Structural Properties of Central Galaxies in Groups and Clusters
Using a representative sample of 911 central galaxies (CENs) from the SDSS
DR4 group catalogue, we study how the structure of the most massive members in
groups and clusters depend on (1) galaxy stellar mass (Mstar), (2) dark matter
halo mass of the host group (Mhalo), and (3) their halo-centric position. We
establish and thoroughly test a GALFIT-based pipeline to fit 2D Sersic models
to SDSS data. We find that the fitting results are most sensitive to the
background sky level determination and strongly recommend using the SDSS global
value. We find that uncertainties in the background translate into a strong
covariance between the total magnitude, half-light size (r50), and Sersic index
(n), especially for bright/massive galaxies. We find that n depends strongly on
Mstar for CENs, but only weakly or not at all on Mhalo. Less (more) massive
CENs tend to be disk (spheroid)-like over the full Mhalo range. Likewise, there
is a clear r50-Mstar relation for CENs, with separate slopes for disks and
spheroids. When comparing CENs with satellite galaxies (SATs), we find that low
mass (<10e10.75 Msun/h^2) SATs have larger median n than CENs of similar Mstar.
Low mass, late-type SATs have moderately smaller r50 than late-type CENs of the
same Mstar. However, we find no size differences between spheroid-like CENs and
SATs, and no structural differences between CENs and SATs matched in both mass
and colour. The similarity of massive SATs and CENs shows that this distinction
has no significant impact on the structure of spheroids. We conclude that Mstar
is the most fundamental property determining the basic structure of a galaxy.
The lack of a clear n-Mhalo relation rules out a distinct group mass for
producing spheroids, and the responsible morphological transformation processes
must occur at the centres of groups spanning a wide range of masses. (abridged)Comment: 22 pages, 14 figures, submitted to MNRA
2MASS photometry of edge-on spiral galaxies. I. Sample and general results
A sample of edge-on spiral galaxies aimed at a study of the main structural
and photometric parameters of edge-on galaxies both of early and late types is
presented. The data were taken from the 2MASS in the J, H and K_s filters. The
sample consists of 175 galaxies in the K_s-filter, 169 galaxies in the H-filter
and 165 galaxies in the J-filter. We present bulge and disc decompositions of
each galaxy image. All galaxies have been modelled with a Sersic bulge and
exponential disc with the BUDDA v2.1 package.
The main conclusions of our general statistical analysis of the sample are:
(1) The distribution of the apparent bulge axis ratio q_b for the subsample
with n < 2 can be attributed to triaxial, nearly prolate bulges that are seen
from different projections, while n > 2 bulges seem to be oblate spheroids with
moderate flattening.
(2) For the sample galaxies, the effective radius of the bulge r_{e,b}, the
disc scalelength h and the disc scaleheight z_0 are well correlated. However,
there is a clear trend for the ratio r_{e,b}/h to increase with n.
(3) There is a hint that the fundamental planes of discs, which links only
disc parameters and the maximum rotational velocity of gas, are different for
galaxies with different bulges.
(4) The investigation of the Photometric Plane of sample bulges shows that
the plane is not flat and has a prominent curvature towards small values of n.
For bulges this fact was not noticed earlier.
(5) The clear relation between the flattening of stellar discs h/z_0 and the
relative mass of a spherical component, including a dark halo, is confirmed not
for bulgeless galaxies but for galaxies with massive bulges. (Abridged)Comment: 20 pages, 13 figures, accepted for publication in MNRA
The Formation and Evolution of Virgo Cluster Galaxies - II. Stellar Populations
We use a combination of deep optical and near-infrared light profiles for a
morphologically diverse sample of Virgo cluster galaxies to study the
radially-resolved stellar populations of cluster galaxies over a wide range of
galaxy structure. We find that, in the median, the age gradients of Virgo
galaxies are either flat (lenticulars and Sa-Sb spirals) or positive
(ellipticals, Sbc+Sc spirals, gas-rich dwarfs, and irregulars), while all
galaxy types have a negative median metallicity gradient. Comparison of the
galaxy stellar population diagnostics (age, metallicity, and gradients thereof)
against structural and environmental parameters also reveals that the ages of
gas-rich systems depend mainly on their atomic gas deficiencies. Conversely,
the metallicities of Virgo gas-poor galaxies depend on their concentrations,
luminosities, and surface brightnesses. The stellar population gradients of all
Virgo galaxies exhibit no dependence on either their structure or environment.
We interpret these stellar population data for Virgo galaxies in the context of
popular formation and evolution scenarios, and suggest that gas-poor giants
grew hierarchically (through dissipative starbursts), gas-poor dwarfs have
descended from at least two different production channels (e.g., environmental
transformation and merging), while spirals formed inside-out, but with star
formation in the outskirts of a significant fraction of the population having
been quenched due to ram pressure stripping. (Abridged)Comment: 54 pages, 16 figures, 3 tables, re-submitted to MNRAS (edited to
reflect the referee's suggestions
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