80 research outputs found
Parameterized Post-Newtonian coefficients for Brans-Dicke gravity with d+1 dimensions
We present calculations of Post-Newtonian parameters for Brans-Dicke
tensor-scalar gravity in an arbitrary number of compact extra dimensions in
both the Jordan and Einstein conformal frames. We find that the parameter
gamma, which measures the amount of spacetime curvature per unit mass, becomes
a function of omega, the coefficient of the scalar kinetic term in the
Brans-Dicke Lagrangian. Experiment has placed strong constraints on gamma which
require that omega become negative in the Jordan frame for any number of extra
dimensions, highlighting that this formulation is not physical. We also confirm
the well-known result that a compact extra dimension can be equivalently viewed
as a massless scalar `dilaton.' In the Einstein frame, we find that the
behavior of gamma as constrained by experiment replicates that which is
predicted by string theory.Comment: 9 pages, accepted in Classical and Quantum Gravit
The Deep SWIRE Field II. 90cm Continuum Observations and 20cm-90cm Spectra
We present one of the deepest radio continuum surveys to date at a wavelength
~1 meter, at 324.5 MHz. The data reduction and analysis are described and an
electronic catalog of the sources detected above 5 sigma is presented. We also
discuss the observed angular size distribution for the sample. Using our deeper
20cm survey of the same field, we calculate spectral indices for sources
detected in both surveys. The spectral indices for 90cm-selected sources,
defined as S ~nu^(-alpha}, shows a peak near 0.7 and only a few sources with
very steep spectra. Thus no large population of very steep spectrum microJy
sources seems to exist down to the limit of our survey.
For 20cm-selected sources, we find similar mean spectral indices for sources
with S_20>1 mJy. For weaker sources, below the detection limit for individual
sources at 90cm, we use stacking to study the radio spectra. We find that the
spectral indices of small (<3") 20cm-selected sources with S_20< 10 mJy have
mean and median alpha(90,20)~0.3-0.5. This is flatter than the spectral indices
of the stronger source population.
We report log N-log S counts at 90cm which show a flattening below 5 mJy.
Given the median redshift of the population, z~1, the spectral flattening and
the flattening of the log N-log S counts occurs at radio luminosities normally
associated with AGN rather than with galaxies dominated by star-formation.Comment: 13 pages, 8 tables, 7 figures, full electronic tables at
http://www.aoc.nrao.edu/~fowen/papers/SWIRE/90cmpaper2/, accepted A
An X-ray Investigation of Three Supernova Remnants in the Large Magellanic Cloud
We have investigated three SNRs in the LMC using multi-wavelength data. These
SNRs are generally fainter than the known sample and may represent a previously
missed population. One of our SNRs is the second LMC remnant analyzed which is
larger than any Galactic remnant for which a definite size has been
established. The analysis of such a large remnant contributes to the
understanding of the population of highly evolved SNRs. We have obtained X-ray
images and spectra of three of these recently identified SNRs using the
XMM-Newton observatory. These data, in conjunction with pre-existing optical
emission-line images and spectra, were used to determine the physical
conditions of the optical- and X-ray-emitting gas in the SNRs. We have compared
the morphologies of the SNRs in the different wavebands. The physical
properties of the warm ionized shell were determined from the H-alpha surface
brightness and the SNR expansion velocity. The X-ray spectra were fit with a
thermal plasma model and the physical conditions of the hot gas were derived
from the model fits. Finally, we have compared our observations with
simulations of SNR evolution
The Lick AGN Monitoring Project: Photometric Light Curves and Optical Variability Characteristics
The Lick AGN Monitoring Project targeted 13 nearby Seyfert 1 galaxies with
the intent of measuring the masses of their central black holes using
reverberation mapping. The sample includes 12 galaxies selected to have black
holes with masses roughly in the range 10^6-10^7 solar masses, as well as the
well-studied AGN NGC 5548. In conjunction with a spectroscopic monitoring
campaign, we obtained broad-band B and V images on most nights from 2008
February through 2008 May. The imaging observations were carried out by four
telescopes: the 0.76-m Katzman Automatic Imaging Telescope (KAIT), the 2-m
Multicolor Active Galactic Nuclei Monitoring (MAGNUM) telescope, the Palomar
60-in (1.5-m) telescope, and the 0.80-m Tenagra II telescope. Having
well-sampled light curves over the course of a few months is useful for
obtaining the broad-line reverberation lag and black hole mass, and also allows
us to examine the characteristics of the continuum variability. In this paper,
we discuss the observational methods and the photometric measurements, and
present the AGN continuum light curves. We measure various variability
characteristics of each of the light curves. We do not detect any evidence for
a time lag between the B- and V-band variations, and we do not find significant
color variations for the AGNs in our sample.Comment: 16 pages, 20 figures, 8 tables, accepted for publication in ApJ
Depletion of stromal cells expressing fibroblast activation protein-α from skeletal muscle and bone marrow results in cachexia and anemia.
Fibroblast activation protein-α (FAP) identifies stromal cells of mesenchymal origin in human cancers and chronic inflammatory lesions. In mouse models of cancer, they have been shown to be immune suppressive, but studies of their occurrence and function in normal tissues have been limited. With a transgenic mouse line permitting the bioluminescent imaging of FAP(+) cells, we find that they reside in most tissues of the adult mouse. FAP(+) cells from three sites, skeletal muscle, adipose tissue, and pancreas, have highly similar transcriptomes, suggesting a shared lineage. FAP(+) cells of skeletal muscle are the major local source of follistatin, and in bone marrow they express Cxcl12 and KitL. Experimental ablation of these cells causes loss of muscle mass and a reduction of B-lymphopoiesis and erythropoiesis, revealing their essential functions in maintaining normal muscle mass and hematopoiesis, respectively. Remarkably, these cells are altered at these sites in transplantable and spontaneous mouse models of cancer-induced cachexia and anemia. Thus, the FAP(+) stromal cell may have roles in two adverse consequences of cancer: their acquisition by tumors may cause failure of immunosurveillance, and their alteration in normal tissues contributes to the paraneoplastic syndromes of cachexia and anemia
Allergic Rhinitis and its Impact on Asthma (ARIA) Guidelines - 2016 Revision
BACKGROUND: Allergic rhinitis (AR) affects 10% to 40% of the population. It reduces quality of life and school and work performance and is a frequent reason for office visits in general practice. Medical costs are large, but avoidable costs associated with lost work productivity are even larger than those incurred by asthma. New evidence has accumulated since the last revision of the Allergic Rhinitis and its Impact on Asthma (ARIA) guidelines in 2010, prompting its update.
OBJECTIVE: We sought to provide a targeted update of the ARIA guidelines.
METHODS: The ARIA guideline panel identified new clinical questions and selected questions requiring an update. We performed systematic reviews of health effects and the evidence about patients' values and preferences and resource requirements (up to June 2016). We followed the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) evidence-to-decision frameworks to develop recommendations.
RESULTS: The 2016 revision of the ARIA guidelines provides both updated and new recommendations about the pharmacologic treatment of AR. Specifically, it addresses the relative merits of using oral H1-antihistamines, intranasal H1-antihistamines, intranasal corticosteroids, and leukotriene receptor antagonists either alone or in combination. The ARIA guideline panel provides specific recommendations for the choice of treatment and the rationale for the choice and discusses specific considerations that clinicians and patients might want to review to choose the management most appropriate for an individual patient.
CONCLUSIONS: Appropriate treatment of AR might improve patients' quality of life and school and work productivity. ARIA recommendations support patients, their caregivers, and health care providers in choosing the optimal treatment
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