2,149 research outputs found
Field galaxies at intermediate redshift (0.2 < z < 0.8) in the direction of the galaxy cluster LCDCS-S001
We present spectroscopic and photometric analysis for eight field galaxies in
the direction of the galaxy cluster LCDCS-S001. The spectra were obtained with
the GMOS instrument in the Gemini South Observatory. The objects were selected
in an i' band image and the multi-object spectroscopic observations were
centered at 7500 A. For the galaxies ID 440 and ID 461 we have determined
redshifts of z=0.7464 and z=0.7465, respectively. For the other six galaxies we
have confirmed the redshift calculated by Rembold & Pastoriza (2006). The
redshifts of the field galaxies are in the range of 0.2201 < z < 0.7784. We
determined the blue and visual luminosities and they are brighter than
M_B=-18.64. The galaxies ID 180, ID 266, ID 461 follow the Faber-Jackson
relation of the Coma and Virgo early-type galaxies, and therefore do not
present a brightening of the B luminosity as observed in galaxies at higher
redshifts. The stellar velocity dispersion was measured for five galaxies and
estimated to be in the range of 200 < sigma < 346 km/s. Lick indices were
measured and used to determine the stellar population properties of galaxies ID
120 and ID 146, by means of spectral synthesis. The first galaxy, ID 120,
presents in its spectrum absorption and emission lines, and we have found that
the main contribution in the flux at lambda 5870 A is of a 0.1 Gyr stellar
population of solar metallicity. For ID 146, the dominant flux contribution at
lambda 4200 A, is provided by a stellar population of 10 Gyr of subsolar
metallicity. From stellar population synthesis we estimated reddening values of
E(B-V)=0.90 and E(B-V)=0.82 for ID 120 and ID 146, respectively. According to
classical diagnostic diagrams the emission lines present in the spectrum of ID
120 indicate that it is a starburst galaxy.Comment: Accepted for publication in Monthly Notices of the Royal
Astronomical. 6 Figures and 4 table
AC-coupled GaAs microstrip detectors with a new type of integrated bias resistors
Full size single-sided GaAs microstrip detectors with integrated coupling
capacitors and bias resistors have been fabricated on 3'' substrate wafers.
PECVD deposited SiO_2 and SiO_2/Si_3N_4 layers were used to provide coupling
capacitaces of 32.5 pF/cm and 61.6 pF/cm, respectively. The resistors are made
of sputtered CERMET using simple lift of technique. The sheet resistivity of 78
kOhm/sq. and the thermal coefficient of resistance of less than 4x10^-3 /
degree C satisfy the demands of small area biasing resistors, working on a wide
temperature range.Comment: 20 pages, 9 figures, to be published in NIM
A conserved role for Snail as a potentiator of active transcription
The transcription factors of the Snail family are key regulators of epithelial-mesenchymal transitions, cell morphogenesis, and tumor metastasis. Since its discovery in Drosophila ~25 years ago, Snail has been extensively studied for its role as a transcriptional repressor. Here we demonstrate that Drosophila Snail can positively modulate transcriptional activation. By combining information on in vivo occupancy with expression profiling of hand-selected, staged snail mutant embryos, we identified 106 genes that are potentially directly regulated by Snail during mesoderm development. In addition to the expected Snail-repressed genes, almost 50% of Snail targets showed an unanticipated activation. The majority of "Snail-activated" genes have enhancer elements cobound by Twist and are expressed in the mesoderm at the stages of Snail occupancy. Snail can potentiate Twist-mediated enhancer activation in vitro and is essential for enhancer activity in vivo. Using a machine learning approach, we show that differentially enriched motifs are sufficient to predict Snail's regulatory response. In silico mutagenesis revealed a likely causative motif, which we demonstrate is essential for enhancer activation. Taken together, these data indicate that Snail can potentiate enhancer activation by collaborating with different activators, providing a new mechanism by which Snail regulates development
Gamma(*)Gamma(*) reaction at high energies
The energy available for gamma(*)gamma(*) physics at LEP2 is opening a new
window on the study of diffractive phenomena, both non-perturbative and
perturbative. We discuss some of the uncertainties and problems connected with
the experimental measurements and their interpretation.Comment: 6 pages, 6 figures, submitted to proceedings of the Durham Collider
Workshop, 22-26 September 199
Joint PDF modelling of turbulent flow and dispersion in an urban street canyon
The joint probability density function (PDF) of turbulent velocity and
concentration of a passive scalar in an urban street canyon is computed using a
newly developed particle-in-cell Monte Carlo method. Compared to moment
closures, the PDF methodology provides the full one-point one-time PDF of the
underlying fields containing all higher moments and correlations. The
small-scale mixing of the scalar released from a concentrated source at the
street level is modelled by the interaction by exchange with the conditional
mean (IECM) model, with a micro-mixing time scale designed for geometrically
complex settings. The boundary layer along no-slip walls (building sides and
tops) is fully resolved using an elliptic relaxation technique, which captures
the high anisotropy and inhomogeneity of the Reynolds stress tensor in these
regions. A less computationally intensive technique based on wall functions to
represent boundary layers and its effect on the solution are also explored. The
calculated statistics are compared to experimental data and large-eddy
simulation. The present work can be considered as the first example of
computation of the full joint PDF of velocity and a transported passive scalar
in an urban setting. The methodology proves successful in providing high level
statistical information on the turbulence and pollutant concentration fields in
complex urban scenarios.Comment: Accepted in Boundary-Layer Meteorology, Feb. 19, 200
Strong Coupling Constant from the Photon Structure Function
We extract the value of the strong coupling constant alpha_s from a
single-parameter pointlike fit to the photon structure function F_2^gamma at
large x and Q^2 and from a first five-parameter full (pointlike and hadronic)
fit to the complete F_2^gamma data set taken at PETRA, TRISTAN, and LEP. In
next-to-leading order and the MSbar renormalization and factorization schemes,
we obtain alpha_s(m_Z)=0.1183 +/- 0.0050(exp.)^+0.0029_-0.0028(theor.)
[pointlike] and alpha_s(m_Z)=0.1198 +/- 0.0028(exp.)^+0.0034_-0.0046(theor.)
[pointlike and hadronic]. We demonstrate that the data taken at LEP have
reduced the experimental error by about a factor of two, so that a competitive
determination of alpha_s from F_2^gamma is now possible.Comment: 11 pages, 2 tables, 2 figures. Version accepted for publication by
Phys. Rev. Let
Experiment Simulation Configurations Used in DUNE CDR
The LBNF/DUNE CDR describes the proposed physics program and experimental
design at the conceptual design phase. Volume 2, entitled The Physics Program
for DUNE at LBNF, outlines the scientific objectives and describes the physics
studies that the DUNE collaboration will perform to address these objectives.
The long-baseline physics sensitivity calculations presented in the DUNE CDR
rely upon simulation of the neutrino beam line, simulation of neutrino
interactions in the far detector, and a parameterized analysis of detector
performance and systematic uncertainty. The purpose of this posting is to
provide the results of these simulations to the community to facilitate
phenomenological studies of long-baseline oscillation at LBNF/DUNE.
Additionally, this posting includes GDML of the DUNE single-phase far detector
for use in simulations. DUNE welcomes those interested in performing this work
as members of the collaboration, but also recognizes the benefit of making
these configurations readily available to the wider community.Comment: 9 pages, 4 figures, configurations in ancillary file
Higgs boson production in photon-photon collision at ILC: a comparative study in different little Higgs models
We study the process \gamma\gamma->h->bb_bar at ILC as a probe of different
little Higgs models, including the simplest little Higgs model (SLH), the
littlest Higgs model (LH), and two types of littlest Higgs models with T-parity
(LHT-I, LHT-II). Compared with the Standard Model (SM) prediction, the
production rate is found to be sizably altered in these little Higgs models
and, more interestingly, different models give different predictions. We find
that the production rate can be possibly enhanced only in the LHT-II for some
part of the parameter space, while in all other cases the rate is suppressed.
The suppression can be 10% in the LH and as much as 60% in both the SLH and the
LHT-I/LHT-II. The severe suppression in the SLH happens for a large \tan\beta
and a small m_h, in which the new decay mode h->\eta\eta (\eta is a light
pseudo-scalar) is dominant; while for the LHT-I/LHT-II the large suppression
occurs when f and m_h are both small so that the new decay mode h->A_H A_H is
dominant. Therefore, the precision measurement of such a production process at
the ILC will allow for a test of these models and even distinguish between
different scenarios.Comment: Version in JHEP (h-g-g & h-gamma-gamma expressions added
SSDSS IV MaNGA - Properties of AGN host galaxies
We present here the characterization of the main properties of a sample of 98
AGN host galaxies, both type-II and type-I, in comparison with those of about
2700 non-active galaxies observed by the MaNGA survey. We found that AGN hosts
are morphologically early-type or early-spirals. For a given morphology AGN
hosts are, in average, more massive, more compact, more central peaked and
rather pressurethan rotational-supported systems. We confirm previous results
indicating that AGN hosts are located in the intermediate/transition region
between star-forming and non-star-forming galaxies (i.e., the so-called green
valley), both in the ColorMagnitude and the star formation main sequence
diagrams. Taking into account their relative distribution in terms of the
stellar metallicity and oxygen gas abundance and a rough estimation of their
molecular gas content, we consider that these galaxies are in the process of
halting/quenching the star formation, in an actual transition between both
groups. The analysis of the radial distributions of the starformation rate,
specific star-formation rate, and molecular gas density shows that the
quenching happens from inside-out involving both a decrease of the efficiency
of the star formation and a deficit of molecular gas. All the intermediate
data-products used to derive the results of our analysis are distributed in a
database including the spatial distribution and average properties of the
stellar populations and ionized gas, published as a Sloan Digital Sky Survey
Value Added Catalog being part of the 14th Data Release:
http://www.sdss.org/dr14/manga/manga-data/manga-pipe3d-value-added-catalog/Comment: 48 pages, 14 figures, in press in RMxA
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