7,318 research outputs found
Euclidean Path Integral, D0-Branes and Schwarzschild Black Holes in Matrix Theory
The partition function in Matrix theory is constructed by Euclidean path
integral method. The D0-branes, which move around in the finite region with a
typical size of Schwarzschild radius, are chosen as the background. The mass
and entropy of the system obtained from the partition function contain the
parameters of the background. After averaging the mass and entropy over the
parameters, we find that they match the properties of 11D Schwarzschild black
holes. The period \b of Euclidean time can be identified with the reciprocal
of the boosted Hawking temperature. The entropy is shown to be proportional
to the number of Matrix theory partons, which is a consequence of the
D0-brane background.Comment: 15 pages, Late
D-branes in B Fields
The RR Page charges for the D2-, D4-, D6-brane in B fields are constructed
explicitly from the equations of motion and the nonvanishing (modified) Bianchi
identities by exploiting their properties --- conserved and localized. It is
found that the RR Page charges are independent of the backgound B fields, which
provides further evidence that the RR Page charge should be quantized. In our
construction, it is highly nontrivial that the terms like B x B x B, B x B x F,
B x F x F from different sources are exactly cancelled with each other.Comment: 13 pages, latex, version to appear in Nucl. Phys.
Hyperinsulinemia and hypovitaminosis D among overweight adolescents
In the past two decades, the prevalence of childhood obesity has doubled. Obesity, insulin resistance, and type 2 diabetes mellitus have been shown to be interrelated. Hypovitaminosis D has also been shown to be more prevalent in overweight patients. Because current studies regarding insulin resistance and hypovitaminosis D have focused on the adult population, we have chosen to examine the adolescent population in this study
Adenovirus-36 antibody status and BMI comparison among obese Missouri adolescents
Worldwide obesity rates have skyrocketed since 1980, a phenomenon often attributed due to changes in diet and physical activity. Adenovirus-36 (Adv-36) has been implicated in the multi-factorial etiology of obesity. Adv-36 has been shown to cause obesity in animal models, and previous studies in the U.S. and internationally have found a higher prevalence of Adv-36 antibodies in obese persons compared to non-obese persons. The prevalence of the virus in overweight and normal-weight individuals has never been studied in a Missouri population
Magnetic power spectra from Faraday rotation maps - REALMAF and its use on Hydra A
We develop a novel maximum-a-posteriori method to measure magnetic power
spectra from Faraday rotation data and implement it in the REALMAF code. A
sophisticated model for the magnetic autocorrelation in real space permits us
to alleviate previously required simplifying assumptions in the processing. We
also introduce a way to treat the divergence relation of the magnetic field
with a multiplicative factor in Fourier space, with which we can model the
magnetic autocorrelation as a spherically symmetric function. Applied to the
dataset of Hydra A north, we find a power law power spectrum on spatial scales
between 0.3 kpc and 8 kpc, with no visible turnover at large scales within this
range and a spectral index consistent with a Kolmogorov-like power law regime.
The magnetic field strength profile seems to follow the electron density
profile with an index alpha=1. A variation of alpha from 0.5 to 1.5 would lead
to a spectral index between 1.55 and 2.05. The extrapolated magnetic field
strength in the cluster centre highly depends on the assumed projection angle
of the jet. For an angle of 45 degree we derive extrapolated 36 muG in the
centre and directly probed 16 muG at 50 kpc radius.Comment: 13 pages, 13 figures, version accepted by A&A with restructured
introduction and language improvement
Magnetic Fields in the 3C 129 Cluster
We present multi-frequency VLA observations of the two radio galaxies 3C 129
and 3C 129.1 embedded in a luminous X-ray cluster. These radio observations
reveal a substantial difference in the Faraday Rotation Measures (RMs) toward
3C 129.1 at the cluster center and 3C 129 at the cluster periphery. After
deriving the density profile from available X-ray data, we find that the RM
structure of both radio galaxies can be fit by a tangled cluster magnetic field
with strength 6 microGauss extending at least 3 core radii (450 kpc) from the
cluster center. The magnetic field makes up a small contribution to the total
pressure (5%) in the central regions of the cluster. The radio morphology of 3C
129.1 appears disturbed on the southern side, perhaps by the higher pressure
environment. In contrast with earlier claims for the presence of a moderately
strong cooling flow in the 3C 129 cluster, our analysis of the X-ray data
places a limit on the mass deposition rate from any such flow of <1.2 Msun/yr.Comment: in press at MNRA
Radio galaxies and magnetic fields in A514
A514 contains six extended and polarized radio sources located at various
projected distances from the cluster center. Here we present a detailed study
of these six radio sources in total intensity and polarization using the Very
Large Array at 3.6 and 6 cm. Since the radio sources sample different lines of
sight across the cluster, an analysis of the Faraday Rotation Measures (RMs)
provides information on the strength and the structure of the cluster magnetic
field. These sources show a decreasing Faraday Rotation Measure with increasing
distance from the cluster center. We estimate the strength of the magnetic
field to be ~3-7 uG in the cluster center. From the RM structure across the
stronger and more extended sources we estimate the coherence length of the
magnetic field to be about 9 kpc at the cluster center.Comment: 16 pages, 18 ps figures accepted by A&
Measuring the Cluster Magnetic Field Power Spectra from Faraday Rotation Maps of Abell 400, Abell 2634 and Hydra A
We apply a novel technique of Faraday Rotation measure (RM) map analysis to
three galaxy clusters, Abell 400, Abell 2634 and Hydra A, in order to estimate
cluster magnetic field strengths, length scales and power spectra. This
analysis is based on the assumption that the magnetic fields are statistically
isotropically distributed across the Faraday screen. We investigate the
difficulties involved in the application of the analysis to observational data.
We derive magnetic power spectra for the three clusters and discuss influences
on their shapes. We show that magnetic fluctuations are probed on length scales
ranging over at least one order of magnitude. Using this range for the
determination of central cluster magnetic field strength yields 3 muG in Abell
2634, 6 muG in Abell 400 and 12 muG in Hydra A. The magnetic field
autocorrelation length was determined to be 4.9 kpc for Abell 2634, 3.6 kpc for
Abell 400 and 0.9 kpc for Hydra A. We show that the RM autocorrelation length
is larger than the magnetic field autocorrelation length. We investigate in a
response analysis if it is possible to determine spectral slopes of the power
spectra. We find that integrated numbers can be determined from this analysis
but differential parameters such as spectral slopes have to be treated
differently. Our response analysis results in spectral slopes of the power
spectra of spectral indices alpha = 1.6 to 2.0 suggesting that Kolmogorov
spectra are possible but flatter spectral slopes than alpha = 1.3 can be
excluded.Comment: 14 pages, 9 figures, accepted by A&
A framework for space-efficient string kernels
String kernels are typically used to compare genome-scale sequences whose
length makes alignment impractical, yet their computation is based on data
structures that are either space-inefficient, or incur large slowdowns. We show
that a number of exact string kernels, like the -mer kernel, the substrings
kernels, a number of length-weighted kernels, the minimal absent words kernel,
and kernels with Markovian corrections, can all be computed in time and
in bits of space in addition to the input, using just a
data structure on the Burrows-Wheeler transform of the
input strings, which takes time per element in its output. The same
bounds hold for a number of measures of compositional complexity based on
multiple value of , like the -mer profile and the -th order empirical
entropy, and for calibrating the value of using the data
- …