229 research outputs found
The DEEP2 Galaxy Redshift Survey: The Voronoi-Delaunay Method Catalog of Galaxy Groups
We present a public catalog of galaxy groups constructed from the spectroscopic sample of galaxies in the fourth data release from the Deep Extragalactic Evolutionary Probe 2 (DEEP2) Galaxy Redshift Survey, including the Extended Groth Strip (EGS). The catalog contains 1165 groups with two or more members in the EGS over the redshift range 0 0.6 in the rest of DEEP2. Twenty-five percent of EGS galaxies and fourteen percent of high-z DEEP2 galaxies are assigned to galaxy groups. The groups were detected using the Voronoi-Delaunay method (VDM) after it has been optimized on mock DEEP2 catalogs following similar methods to those employed in Gerke et al. In the optimization effort, we have taken particular care to ensure that the mock catalogs resemble the data as closely as possible, and we have fine-tuned our methods separately on mocks constructed for the EGS and the rest of DEEP2. We have also probed the effect of the assumed cosmology on our inferred group-finding efficiency by performing our optimization on three different mock catalogs with different background cosmologies, finding large differences in the group-finding success we can achieve for these different mocks. Using the mock catalog whose background cosmology is most consistent with current data, we estimate that the DEEP2 group catalog is 72% complete and 61% pure (74% and 67% for the EGS) and that the group finder correctly classifies 70% of galaxies that truly belong to groups, with an additional 46% of interloper galaxies contaminating the catalog (66% and 43% for the EGS). We also confirm that the VDM catalog reconstructs the abundance of galaxy groups with velocity dispersions above ~300 km s^(â1) to an accuracy better than the sample variance, and this successful reconstruction is not strongly dependent on cosmology. This makes the DEEP2 group catalog a promising probe of the growth of cosmic structure that can potentially be used for cosmological tests
Mid-IR Luminosities and UV/Optical Star Formation Rates at z<1.4
UV continuum and mid-IR emission constitute two widely used star formation
indicators at intermediate and high redshifts. We study 2430 galaxies with
z<1.4 in the Extended Groth Strip with MIPS 24 mic observations from FIDEL,
spectroscopy from DEEP2, and UV, optical, and near-IR photometry from AEGIS.
The data are coupled with stellar population models and Bayesian SED fitting to
estimate dust-corrected SFRs. In order to probe the dust heating from stellar
populations of various ages, the derived SFRs were averaged over various
timescales--from 100 Myr for "current" SFR to 1--3 Gyr for long-timescale SFRs.
These SED-based UV/optical SFRs are compared to total infrared luminosities
extrapolated from 24 mic observations. We find that for the blue, actively star
forming galaxies the correlation between the IR luminosity and the UV/optical
SFR shows a decrease in scatter when going from shorter to longer SFR-averaging
timescales. We interpret this as the greater role of intermediate age stellar
populations in heating the dust than what is typically assumed. This holds over
the entire redshift range. Many so-called green valley galaxies are simply
dust-obscured actively star-forming galaxies. However, there exist 24
mic-detected galaxies, some with L>10^11 L_sun, yet with little current star
formation. For them a reasonable amount of dust absorption of stellar light is
sufficient to produce the observed levels of IR. In our sample optical and
X-ray AGNs do not contribute on average more than ~50% to the mid-IR
luminosity, and we see no evidence for a large population of "IR excess"
galaxies (Abridged).Comment: Accepted for publication in ApJ. Content identical to arXiv version
1. No color figure
Bounded excursion stable gravastars and black holes
Dynamical models of prototype gravastars were constructed in order to study
their stability. The models are the Visser-Wiltshire three-layer gravastars, in
which an infinitely thin spherical shell of stiff fluid divides the whole
spacetime into two regions, where the internal region is de Sitter, and the
external is Schwarzschild. It is found that in some cases the models represent
the "bounded excursion" stable gravastars, in which the thin shell is
oscillating between two finite radii, while in other cases they collapse until
the formation of black holes. In the phase space, the region for the ``bounded
excursion" gravastars is very small in comparison to that of black holes, but
not empty. Therefore, although the existence of gravastars cannot be excluded
from such dynamical models, our results do indicate that, even if gravastars
indeed exist, they do not exclude the existence of black holes.Comment: Revtex4, 12 figures. Version published in JCAP, 06 (2008) 02
Management of subclinical hyperthyroidism
The ideal approach for adequate management of subclinical hyperthyroidism (low levels
of thyroid-stimulating hormone [TSH] and normal thyroid hormone level) is a matter of
intense debate among endocrinologists. The prevalence of low serum TSH levels ranges
between 0.5% in children and 15% in the elderly population. Mild subclinical hyperthyroid
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ism is more common than severe subclinical hyperthyroidism. Transient suppression of
TSH secretion may occur because of several reasons; thus, corroboration of results from
different assessments is essential in such cases. During differential diagnosis of hyperthy
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roidism, pituitary or hypothalamic disease, euthyroid sick syndrome, and drug-mediated
suppression of TSH must be ruled out. A low plasma TSH value is also typically seen in
the first trimester of gestation. Factitial or iatrogenic TSH inhibition caused by excessive
intake of levothyroxine should be excluded by checking the patientâs medication history.
If these nonthyroidal causes are ruled out during differential diagnosis, either transient
or long-term endogenous thyroid hormone excess, usually caused by Gravesâ disease or
nodular goiter, should be considered as the cause of low circulating TSH levels.
We recommend the following 6-step process for the assessment and treatment of this
common hormonal disorder: 1) confirmation, 2) evaluation of severity, 3) investiga
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tion of the cause, 4) assessment of potential complications, 5) evaluation of the neces
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sity of treatment, and 6) if necessary, selection of the most appropriate treatment.
In conclusion, management of subclinical hyperthyroidism merits careful monitoring
through regular assessment of thyroid function. Treatment is mandatory in older patients
(> 65 years) or in presence of comorbidities (such as osteoporosis and atrial fibrillation
Supermassive Black Holes in Galactic Nuclei: Past, Present and Future Research
This review discusses the current status of supermassive black hole research,
as seen from a purely observational standpoint. Since the early '90s, rapid
technological advances, most notably the launch of the Hubble Space Telescope,
the commissioning of the VLBA and improvements in near-infrared speckle imaging
techniques, have not only given us incontrovertible proof of the existence of
supermassive black holes, but have unveiled fundamental connections between the
mass of the central singularity and the global properties of the host galaxy.
It is thanks to these observations that we are now, for the first time, in a
position to understand the origin, evolution and cosmic relevance of these
fascinating objects.Comment: Invited Review, 114 pages. Because of space requirements, this
version contains low resolution figures. The full resolution version can be
downloaded from http://www.physics.rutgers.edu/~lff/publications.htm
Performance of the CMS Cathode Strip Chambers with Cosmic Rays
The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device
in the CMS endcaps. Their performance has been evaluated using data taken
during a cosmic ray run in fall 2008. Measured noise levels are low, with the
number of noisy channels well below 1%. Coordinate resolution was measured for
all types of chambers, and fall in the range 47 microns to 243 microns. The
efficiencies for local charged track triggers, for hit and for segments
reconstruction were measured, and are above 99%. The timing resolution per
layer is approximately 5 ns
Characterization of the genetic diversity of Mycobacterium tuberculosis in SĂŁo Paulo city, Brazil
<p>Abstract</p> <p>Background</p> <p>Tuberculosis is a major health problem in SĂŁo Paulo, Brazil, which is the most populous and one of the most cosmopolitan cities in South America. To characterize the genetic diversity of <it>Mycobacterium tuberculosis </it>in the population of this city, the genotyping techniques of spoligotyping and MIRU were applied to 93 isolates collected in two consecutive years from 93 different tuberculosis patients residing in SĂŁo Paulo city and attending the Clemente Ferreira Institute (the reference clinic for the treatment of tuberculosis).</p> <p>Findings</p> <p>Spoligotyping generated 53 different spoligotype patterns. Fifty-one isolates (54.8%) were grouped into 13 spoligotyping clusters. Seventy- two strains (77.4%) showed spoligotypes described in the international databases (SpolDB4, SITVIT), and 21 (22.6%) showed unidentified patterns. The most frequent spoligotype families were Latin American Mediterranean (LAM) (26 isolates), followed by the T family (24 isolates) and Haarlem (H) (11 isolates), which together accounted for 65.4% of all the isolates. These three families represent the major genotypes found in Africa, Central America, South America and Europe. Six Spoligo-International-types (designated SITs by the database) comprised 51.8% (37/72) of all the identified spoligotypes (SIT53, SIT50, SIT42, SIT60, SIT17 and SIT1). Other SITs found in this study indicated the great genetic diversity of <it>M. tuberculosis</it>, reflecting the remarkable ethnic diversity of SĂŁo Paulo city inhabitants. The MIRU technique was more discriminatory and did not identify any genetic clusters with 100% similarity among the 93 isolates. The allelic analysis showed that MIRU loci 26, 40, 23 and 10 were the most discriminatory. When MIRU and spoligotyping techniques were combined, all isolates grouped in the 13 spoligotyping clusters were separated.</p> <p>Conclusions</p> <p>Our data indicated the genomic stability of over 50% of spoligotypes identified in SĂŁo Paulo and the great genetic diversity of <it>M. tuberculosis </it>isolates in the remaining SITs, reflecting the large ethnic mix of the SĂŁo Paulo city inhabitants. The results also indicated that in this city, <it>M. tuberculosis </it>isolates acquired drug resistance independently of genotype and that resistance was more dependent on the selective pressure of treatment failure and the environmental circumstances of patients.</p
Type and extent of trans-disciplinary co-operation to improve food security, health and household environment in low and middle income countries: systematic review
Acknowledgements: We are grateful to Dr Steve Turner and Dr Adam Price for their insightful comments that improved the manuscript. We would like to thank Heather Clark and Bimbola Kalejaiye for their help in data extraction. We are also grateful to Melanie Bickerton and Dr Amudha Poobalan for their systematic review advice.Peer reviewedPublisher PD
Performance and Operation of the CMS Electromagnetic Calorimeter
The operation and general performance of the CMS electromagnetic calorimeter
using cosmic-ray muons are described. These muons were recorded after the
closure of the CMS detector in late 2008. The calorimeter is made of lead
tungstate crystals and the overall status of the 75848 channels corresponding
to the barrel and endcap detectors is reported. The stability of crucial
operational parameters, such as high voltage, temperature and electronic noise,
is summarised and the performance of the light monitoring system is presented
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