23,300 research outputs found
Development of advanced digital techniques for data acquisition processing and communication Interim scientific report
Digital techniques for automatic evaluation of images and data compression algorithm
Gender-Specific Protection from Microvessel Rarefaction in Female Hypertensive Rats
Epidemiologic studies reveal that women have a significantly lower age-adjusted morbidity and mortality from cardiovascular disease than men, suggesting that gender is a cardiovascular disease risk factor. The mechanism of the “gender protection” is unknown. In this study, we investigated the microvascular remodeling in reduced renal mass plus a high salt (4.0% NaCl) diet model of hypertension (RRM + HS). We hypothesized that women would be protected from the increase in blood pressure and from the microvascular rarefaction associated with RRM + HS hypertension. Studies were designed to determine whether female rats were less susceptible to changes in microvessel density during RRM + HS. Microvessel density was measured in male and female low salt (0.4% LS) sham-operated controls (Sham + LS) and after 3 days or 4 weeks of RRM + HS hypertension. The microcirculation of hind limb (medial and lateral gastrocnemius, plantaris, soleus) muscles was visualized using rhodamine-labeled Griffonia simplicifolia I lectin. Tissue sections were examined by videomicroscopy and microvessel density was determined by quantitative stereology. As shown previously, mean arterial pressure increased to 160 ± 8 mm Hg and microvessel density decreased (\u3e30% decrease in all beds) in male RRM + HS. In contrast, mean arterial pressure of female RRM + HS rats was modestly increased from 101 ± 2 to 118 ± 4 mm Hg. Despite previous results showing a reduction in microvessel density of both normotensive and hypertensive male rats on a high salt diet, microvessel density of female RRM + HS rats was not reduced at either time. These results suggest that gender protection in the RRM rat extends beyond an attenuation of the increase in pressure to an immunity from microvascular rarefaction
Steep-Spectrum Radio Emission from the Low-Mass Active Galactic Nucleus GH 10
GH 10 is a broad-lined active galactic nucleus (AGN) energized by a black
hole of mass 800,000 Solar masses. It was the only object detected by Greene et
al. in their Very Large Array (VLA) survey of 19 low-mass AGNs discovered by
Greene & Ho. New VLA imaging at 1.4, 4.9, and 8.5 GHz reveals that GH 10's
emission has an extent of less than 320 pc, has an optically-thin synchrotron
spectrum with a spectral index -0.76+/-0.05, is less than 11 percent linearly
polarized, and is steady - although poorly sampled - on timescales of weeks and
years. Circumnuclear star formation cannot dominate the radio emission, because
the high inferred star formation rate, 18 Solar masses per year, is
inconsistent with the rate of less than 2 Solar masses per year derived from
narrow Halpha and [OII] 3727 emission. Instead, the radio emission must be
mainly energized by the low-mass black hole. GH 10's radio properties match
those of the steep-spectrum cores of Palomar Seyfert galaxies, suggesting that,
like those Seyferts, the emission is outflow-driven. Because GH 10 is radiating
close to its Eddington limit, it may be a local analog of the starting
conditions, or seeds, for supermassive black holes. Future imaging of GH 10 at
higher resolution thus offers an opportunity to study the relative roles of
radiative versus kinetic feedback during black-hole growth.Comment: 7 pages; 2 figures; emulateapj; to appear in Ap
Raising the unification scale in supersymmetry
In the minimal supersymmetric standard model, the three gauge couplings
appear to unify at a mass scale near GeV. We investigate the
possibility that intermediate scale particle thresholds modify the running
couplings so as to increase the unification scale. By requiring consistency of
this scenario, we derive some constraints on the particle content and locations
of the intermediate thresholds. There are remarkably few acceptable solutions
with a single cleanly defined intermediate scale far below the unification
scale.Comment: 22 pages, macros included. One figure, available at
ftp://ftp.phys.ufl.edu/incoming/rais.ep
Radio Emission from the Intermediate-mass Black Hole in the Globular Cluster G1
We have used the Very Large Array (VLA) to search for radio emission from the
globular cluster G1 (Mayall-II) in M31. G1 has been reported by Gebhardt et al.
to contain an intermediate-mass black hole (IMBH) with a mass of ~2 x 10^4
solar masses. Radio emission was detected within an arcsecond of the cluster
center with an 8.4 GHz power of 2 x 10^{15} W/Hz. The radio/X-ray ratio of G1
is a few hundred times higher than that expected for a high-mass X-ray binary
in the cluster center, but is consistent with the expected value for accretion
onto an IMBH with the reported mass. A pulsar wind nebula is also a possible
candidate for the radio and X-ray emission from G1; future high-sensitivity
VLBI observations might distinguish between this possibility and an IMBH. If
the radio source is an IMBH, and similar accretion and outflow processes occur
for hypothesized ~ 1000-solar-mass black holes in Milky Way globular clusters,
they are within reach of the current VLA and should be detectable easily by the
Expanded VLA when it comes on line in 2010.Comment: ApJ Letters, accepted, 11 pages, 1 figur
Substance Abuse in Indiana: An Urban-Rural Perspective
The use of alcohol and drugs is a significant public health problem in the United States. Indiana, like many other states in the nation, is lacking in substance abuse treatment services and rural areas are particularly underserved. Rural residents may encounter additional barriers to receiving substance abuse treatment, including stigma, fear that they may know their treatment providers, a lack of access to specialized services, inferior quality of care, and having to pay more for treatment
Families of Quintic Calabi-Yau 3-Folds with Discrete Symmetries
At special loci in their moduli spaces, Calabi-Yau manifolds are endowed with
discrete symmetries. Over the years, such spaces have been intensely studied
and have found a variety of important applications. As string compactifications
they are phenomenologically favored, and considerably simplify many important
calculations. Mathematically, they provided the framework for the first
construction of mirror manifolds, and the resulting rational curve counts.
Thus, it is of significant interest to investigate such manifolds further. In
this paper, we consider several unexplored loci within familiar families of
Calabi-Yau hypersurfaces that have large but unexpected discrete symmetry
groups. By deriving, correcting, and generalizing a technique similar to that
of Candelas, de la Ossa and Rodriguez-Villegas, we find a calculationally
tractable means of finding the Picard-Fuchs equations satisfied by the periods
of all 3-forms in these families. To provide a modest point of comparison, we
then briefly investigate the relation between the size of the symmetry group
along these loci and the number of nonzero Yukawa couplings. We include an
introductory exposition of the mathematics involved, intended to be accessible
to physicists, in order to make the discussion self-contained.Comment: 54 pages, 3 figure
Scale-dependent bias of galaxies and mu-type distortion of the cosmic microwave background spectrum from single-field inflation with a modified initial state
We investigate the phenomenological consequences of a modification of the
initial state of a single inflationary field. While single-field inflation with
the standard Bunch-Davies initial vacuum state does not generally produce a
measurable three-point function (bispectrum) in the squeezed configuration,
allowing for a non-standard initial state produces an exception. Here, we
calculate the signature of an initial state modification in single-field
slow-roll inflation in both the scale-dependent bias of the large-scale
structure (LSS) and mu-type distortion in the black-body spectrum of the cosmic
microwave background (CMB). We parametrize the initial state modifications and
identify certain choices of parameters as natural, though we also note some
fine-tuned choices that can yield a larger bispectrum. In both cases, we
observe a distinctive k^-3 signature in LSS (as opposed to k^-2 for the
local-form). As a non-zero bispectrum in the squeezed configuration correlates
a long-wavelength mode with two short-wavelength modes, it induces a
correlation between the CMB temperature anisotropy on large scales with the
temperature-anisotropy-squared on very small scales; this correlation persists
as the small-scale anisotropy-squared is processed into mu-type distortions.
While the local-form mu-distortion turns out to be too small to detect in the
near future, a modified initial vacuum state enhances the signal by a large
factor owing to an extra factor of k_1/k. For example, a proposed
absolutely-calibrated experiment, PIXIE, is expected to detect this correlation
with a signal-to-noise ratio greater than 10, for an occupation number of about
0.5 in the observable modes. Relatively calibrated experiments such as Planck
and LiteBIRD should also be able to measure this effect, provided that the
relative calibration between different frequencies meets the required
precision. (Abridged)Comment: 14 pages, 6 figures. Matches version in PRD. Improved explanation in
Sec. IV; added references and corrected typo
The Potential of Teledentistry in Community Oral Health for the Pediatric Population
• Dental caries is the most prevalent chronic disease of childhood in the US. • Young children are a particularly vulnerable population because of their dependence, inability to communicate needs, and relative poverty. • Furthermore, this can be exacerbated by disparities such that an increased rates of caries are observed in children who are of low socioeconomic status and minority backgrounds. • However, community oral health screenings can play a vital role in childhood caries as a predominately preventable disease. • The current emphasis on social distance during the COVID-19 pandemic has brought attention to teledentistry, which may have a valuable role in the future of community oral health outreach
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