2,411 research outputs found
On the Classification of UGC1382 as a Giant Low Surface Brightness Galaxy
We provide evidence that UGC1382, long believed to be a passive elliptical
galaxy, is actually a giant low surface brightness (GLSB) galaxy which rivals
the archetypical GLSB Malin 1 in size. Like other GLSB galaxies, it has two
components: a high surface brightness disk galaxy surrounded by an extended low
surface brightness (LSB) disk. For UGC1382, the central component is a
lenticular system with an effective radius of 6 kpc. Beyond this, the LSB disk
has an effective radius of ~38 kpc and an extrapolated central surface
brightness of ~26 mag/arcsec^2. Both components have a combined stellar mass of
~8x10^10 M_sun, and are embedded in a massive (10^10 M_sun) low-density (<3
M_sun/pc^2) HI disk with a radius of 110 kpc, making this one of the largest
isolated disk galaxies known. The system resides in a massive dark matter halo
of at least 2x10^12 M_sun. Although possibly part of a small group, its low
density environment likely plays a role in the formation and retention of the
giant LSB and HI disks. We model the spectral energy distributions and find
that the LSB disk is likely older than the lenticular component. UGC1382 has
UV-optical colors typical of galaxies transitioning through the green valley.
Within the LSB disk are spiral arms forming stars at extremely low
efficiencies. The gas depletion time scale of ~10^11 yr suggests that UGC1382
may be a very long term resident of the green valley. We find that the
formation and evolution of the LSB disk is best explained by the accretion of
gas-rich LSB dwarf galaxies.Comment: 17 pages, 16 figures, 4 tables; accepted to the Astrophysical Journa
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Long-term safety and efficacy of trifarotene 50 μg/g cream, a first-in-class RAR-γ selective topical retinoid, in patients with moderate facial and truncal acne.
BackgroundTreatment for both facial and truncal acne has not sufficiently been studied.ObjectivesTo evaluate the long-term safety and efficacy of trifarotene in both facial and truncal acne.MethodsIn a multicentre, open-label, 52-week study, patients with moderate facial and truncal acne received trifarotene 50 μg/g cream (trifarotene). Assessments included local tolerability, safety, investigator and physician's global assessments (IGA, PGA) and quality of life (QOL). A validated QOL questionnaire was completed by the patient at Baseline, Week 12, 26 and 52/ET.ResultsOf 453 patients enrolled, 342 (75.5%) completed the study. Trifarotene-related treatment-emergent adverse events (TEAEs) were reported in 12.6% of patients, and none was serious. Most related TEAEs were cutaneous and occurred during the first 3 months. Signs and symptoms of local tolerability were mostly mild or moderate and severe signs, and symptoms were reported for 2.2% to 7.1% of patients for the face and 2.5% to 5.4% for the trunk. Local irritation increased during the first week of treatment on the face and up to Weeks 2 to 4 on the trunk with both decreasing thereafter. At Week 12, IGA and PGA success rates were 26.6% and 38.6%, respectively. Success rates increased to 65.1% and 66.9%, respectively at Week 52. Overall success (both IGA and PGA success in the same patient) was 57.9% at Week 52. At Week 52 visit, 92/171 (53.8%) patients who had completed their assessments had scores from 0 to 1 (i.e. no effect of acne on their QOL) vs. 47/208 (22.6%) patients at Baseline visit.ConclusionIn this 52-week study, trifarotene was safe, well tolerated and effective in moderate facial and truncal acne
The Faint End Slopes Of Galaxy Luminosity Functions In The COSMOS 2-Square Degree Field
We examine the faint-end slope of the rest-frame V-band luminosity function
(LF), with respect to galaxy spectral type, of field galaxies with redshift
z<0.5, using a sample of 80,820 galaxies with photometric redshifts in the
Cosmic Evolution Survey (COSMOS) field. For all galaxy spectral types combined,
the LF slope, alpha, ranges from -1.24 to -1.12, from the lowest redshift bin
to the highest. In the lowest redshift bin (0.02<z<0.1), where the magnitude
limit is M(V) ~ -13, the slope ranges from ~ -1.1 for galaxies with early-type
spectral energy distributions (SEDs), to ~ -1.9 for galaxies with
low-extinction starburst SEDs. In each galaxy SED category (Ell, Sbc, Scd/Irr,
and starburst), the faint-end slopes grow shallower with increasing redshift;
in the highest redshift bin (0.4<z<0.5), the slope is ~ -0.5 and ~ -1.3 for
early-types and starbursts respectively. The steepness of alpha at lower
redshift could be qualitatively explained by large numbers of faint dwarf
galaxies, perhaps of low surface brightness, which are not detected at higher
redshifts.Comment: 24 pages including 5 figures, accepted to ApJ
Modeling Bacterial DNA: Simulation of Self-avoiding Supercoiled Worm-Like Chains Including Structural Transitions of the Helix
Under supercoiling constraints, naked DNA, such as a large part of bacterial
DNA, folds into braided structures called plectonemes. The double-helix can
also undergo local structural transitions, leading to the formation of
denaturation bubbles and other alternative structures. Various polymer models
have been developed to capture these properties, with Monte-Carlo (MC)
approaches dedicated to the inference of thermodynamic properties. In this
chapter, we explain how to perform such Monte-Carlo simulations, following two
objectives. On one hand, we present the self-avoiding supercoiled Worm-Like
Chain (ssWLC) model, which is known to capture the folding properties of
supercoiled DNA, and provide a detailed explanation of a standard MC simulation
method. On the other hand, we explain how to extend this ssWLC model to include
structural transitions of the helix.Comment: Book chapter to appear in The Bacterial Nucleoid, Methods and
Protocols, Springer serie
Open Issues on the Synthesis of Evolved Stellar Populations at Ultraviolet Wavelengths
In this paper we briefly review three topics that have motivated our (and
others') investigations in recent years within the context of evolutionary
population synthesis techniques. These are: The origin of the FUV up-turn in
elliptical galaxies, the age-metallicity degeneracy, and the study of the
mid-UV rest-frame spectra of distant red galaxies. We summarize some of our
results and present a very preliminary application of a UV grid of theoretical
spectra in the analysis of integrated properties of aged stellar populations.
At the end, we concisely suggest how these topics can be tackled once the World
Space Observatory enters into operation in the midst of this decade.Comment: 8 pages, 4 figures, accepted for publication in Astrophysics & Space
Science, UV Universe special issu
Remarks on the neutrino oscillation formula
We show that the neutrino oscillation formula recently derived in the quantum
field theory framework holds true despite the arbitrariness in the mass
parameter for the flavor fields. This formula is exact and exhibits new
features with respect to the usual Pontecorvo formula, which is however valid
in the relativistic limit.Comment: 10 pages, RevTeX, revised version with comments adde
Relation Between Stellar Mass and Star Formation Activity in Galaxies
For a mass-selected sample of 66544 galaxies with photometric redshifts from
the Cosmic Evolution Survey (COSMOS), we examine the evolution of star
formation activity as a function of stellar mass in galaxies. We estimate the
cosmic star formation rates (SFR) over the range 0.2 < z < 1.2, using the
rest-frame 2800 A flux (corrected for extinction). We find the mean SFR to be a
strong function of the galactic stellar mass at any given redshift, with
massive systems (log (M/M(Sun)) > 10.5) contributing less (by a factor of ~ 5)
to the total star formation rate density (SFRD).
Combining data from the COSMOS and Gemini Deep Deep Survey (GDDS), we extend
the SFRD-z relation as a function of stellar mass to z~2. For massive galaxies,
we find a steep increase in the SFRD-z relation to z~2; for the less massive
systems, the SFRD which also increases from z=0 to 1, levels off at z~1. This
implies that the massive systems have had their major star formation activity
at earlier epochs (z > 2) than the lower mass galaxies.
We study changes in the SFRDs as a function of both redshift and stellar mass
for galaxies of different spectral types. We find that the slope of the SFRD-z
relation for different spectral type of galaxies is a strong function of their
stellar mass. For low and intermediate mass systems, the main contribution to
the cosmic SFRD comes from the star-forming galaxies while, for more massive
systems, the evolved galaxies are the most dominant population.Comment: 34 pages; 8 figures; Accepted for publication in Ap
The MSW Effect in Quantum Field Theory
We show in detail the general relationship between the Schr\"{o}dinger
equation approach to calculating the MSW effect and the quantum field
theoretical S-matrix approach. We show the precise form a generic neutrino
propagator must have to allow a physically meaningful ``oscillation
probability'' to be decoupled from neutrino production fluxes and detection
cross-sections, and explicitly list the conditions---not realized in cases of
current experimental interest---in which the field theory approach would be
useful.Comment: 20 page REVTeX file, submitted to Phys. Rev.
Spatial Periodicity of Galaxy Number Counts, CMB Anisotropy, and SNIa Hubble Diagram Based on the Universe Accompanied by a Non-Minimally Coupled Scalar Field
We have succeeded in establishing a cosmological model with a non-minimally
coupled scalar field that can account not only for the spatial
periodicity or the {\it picket-fence structure} exhibited by the galaxy -
relation of the 2dF survey but also for the spatial power spectrum of the
cosmic microwave background radiation (CMB) temperature anisotropy observed by
the WMAP satellite. The Hubble diagram of our model also compares well with the
observation of Type Ia supernovae. The scalar field of our model universe
starts from an extremely small value at around the nucleosynthesis epoch,
remains in that state for sufficiently long periods, allowing sufficient time
for the CMB temperature anisotropy to form, and then starts to grow in
magnitude at the redshift of , followed by a damping oscillation
which is required to reproduce the observed picket-fence structure of the
- relation. To realize such behavior of the scalar field, we have found
it necessary to introduce a new form of potential , with being a constant. Through this parameter ,
we can control the epoch at which the scalar field starts growing.Comment: 19 pages, 18 figures, Accepted for publication in Astrophysics &
Space Scienc
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