853 research outputs found
New results from H.E.S.S. observations of galaxy clusters
Clusters of galaxies are believed to contain a significant population of
cosmic rays. From the radio and probably hard X-ray bands it is known that
clusters are the spatially most extended emitters of non-thermal radiation in
the Universe. Due to their content of cosmic rays, galaxy clusters are also
potential sources of VHE (>100 GeV) gamma rays. Recently, the massive, nearby
cluster Abell 85 has been observed with the H.E.S.S. experiment in VHE gamma
rays with a very deep exposure as part of an ongoing campaign. No significant
gamma-ray signal has been found at the position of the cluster. The
non-detection of this object with H.E.S.S. constrains the total energy of
cosmic rays in this system. For a hard spectral index of the cosmic rays of
-2.1 and if the cosmic-ray energy density follows the large scale gas density
profile, the limit on the fraction of energy in these non-thermal particles
with respect to the total thermal energy of the intra-cluster medium is 8% for
this particular cluster. This value is at the lower bounds of model
predictions.Comment: 4 pages, one figure, invited talk at the 2nd Heidelberg workshop:
"High-Energy Gamma-rays and Neutrinos from Extra-Galactic Sources", January
13 - 16, 2009, to be published in Int. J. Mod. Phys.
Probing cosmic ray escape from \eta\ Carinae
The binary stellar system Carinae is one of very few established
astrophysical hadron accelerators. It seems likely that at least some fraction
of the accelerated particles escape from the system. Copious target material
for hadronic interactions and associated -ray emission exists on a wide
range of spatial scales outside the binary system. This material creates a
unique opportunity to trace the propagation of particles into the interstellar
medium. Here we analyse -ray data from Fermi-LAT of Carinae and
surrounding molecular clouds and investigate the many different scales on which
escaping particles may interact and produce -rays. We find that
interactions of escaping cosmic rays from Carinae in the wind region and
the Homunculus Nebula could produce a significant contribution to the
-ray emission associated with the system. Furthermore, we detect excess
emission from the surrounding molecular clouds. The derived radial cosmic-ray
excess profile is consistent with a steady injection of cosmic rays by a
central source. However, this would require a higher flux of escaping cosmic
rays from Carinae than provided by our model. Therefore it is likely
that additional cosmic ray sources contribute to the hadronic -ray
emission from the clouds.Comment: accepted for publication in A&A, 10 pages, 6 figure
Aqueous Angiography with Fluorescein and Indocyanine Green in Bovine Eyes.
PurposeWe characterize aqueous angiography as a real-time aqueous humor outflow imaging (AHO) modality in cow eyes with two tracers of different molecular characteristics.MethodsCow enucleated eyes (n = 31) were obtained and perfused with balanced salt solution via a Lewicky AC maintainer through a 1-mm side-port. Fluorescein (2.5%) or indocyanine green (ICG; 0.4%) were introduced intracamerally at 10 mm Hg individually or sequentially. With an angiographer, infrared and fluorescent images were acquired. Concurrent anterior segment optical coherence tomography (OCT) was performed, and fixable fluorescent dextrans were introduced into the eye for histologic analysis of angiographically positive and negative areas.ResultsAqueous angiography in cow eyes with fluorescein and ICG yielded high-quality images with segmental patterns. Over time, ICG maintained a better intraluminal presence. Angiographically positive, but not negative, areas demonstrated intrascleral lumens with anterior segment OCT. Aqueous angiography with fluorescent dextrans led to their trapping in AHO pathways. Sequential aqueous angiography with ICG followed by fluorescein in cow eyes demonstrated similar patterns.ConclusionsAqueous angiography in model cow eyes demonstrated segmental angiographic outflow patterns with either fluorescein or ICG as a tracer.Translational relevanceFurther characterization of segmental AHO with aqueous angiography may allow for intelligent placement of trabecular bypass minimally invasive glaucoma surgeries for improved surgical results
Deep Markov Random Field for Image Modeling
Markov Random Fields (MRFs), a formulation widely used in generative image
modeling, have long been plagued by the lack of expressive power. This issue is
primarily due to the fact that conventional MRFs formulations tend to use
simplistic factors to capture local patterns. In this paper, we move beyond
such limitations, and propose a novel MRF model that uses fully-connected
neurons to express the complex interactions among pixels. Through theoretical
analysis, we reveal an inherent connection between this model and recurrent
neural networks, and thereon derive an approximated feed-forward network that
couples multiple RNNs along opposite directions. This formulation combines the
expressive power of deep neural networks and the cyclic dependency structure of
MRF in a unified model, bringing the modeling capability to a new level. The
feed-forward approximation also allows it to be efficiently learned from data.
Experimental results on a variety of low-level vision tasks show notable
improvement over state-of-the-arts.Comment: Accepted at ECCV 201
Prospectus, February 26, 1976
KEVIN WOODARD V.P.; PC news in brief: Auditions March 1, 2, SIU Reps Here March 5; Convocations starts \u27Forum\u27; Letters to the Editor; Comet West: Skylines; P/C Artists Compete In Junior College Art; Board of Trustees Notes; WPGU - Belle concert; Veterans\u27 election set; Prospectus guide to PC Slanguage ; Good News; Country Bouquet: Hank Williams; D.U. serves students; New Gym Lacks Needed Elevator; Disabled score difficulties; readers forum: Wife-beating problem one of brutality, tragedy; Classifieds; Dear Bonnie; It\u27s Debatable; Rozelle rule: Sports views; Cobra\u27s Corner; Who do we A-pre-ci-ate; PC attends ACU-I; Brown leads with 30: Cobras take CIAC Title; Medley takes first First: Tracksters take Third; CIAC Standings; Charity line tells the tale: Cobras fall to Lake Land End season with 88-77 loss; Spoon River falls 44-37: PC Women to State; O\u27Donnell wins Bob\u27s Bonanzahttps://spark.parkland.edu/prospectus_1976/1021/thumbnail.jp
Dual function of rare earth carboxylate compounds on the barrier properties and active corrosion inhibition of epoxy coatings on mild steel
In this work, two rare earth carboxylate compounds, lanthanum 4-hydroxycinnamate (La(4-OHcin)3) and yttrium 3-(4-methylbenzoyl)propanoate (Y(mbp)3), were incorporated into bisphenol-based epoxy resin to investigate their effectiveness in coating barrier properties and active corrosion inhibition. EIS results showed that the incorporation of rare earth carboxylate inhibitors significantly improved corrosion resistance compared to the inhibitor free coating, with the global impedance modulus remaining at a level higher than 1 GΩ cm2 after 219 days immersion. Following EIS experiments, cross-sectional views of the coatings exhibited a pore-plugging behavior by rare earth containing precipitates, which reinforced the coating barrier properties and delayed the electrolyte diffusion process. These effects were also reflected from the electrochemical parameters extracted from breakpoint frequency analysis and equivalent circuit modelling. Filiform corrosion experiments for artificially scratched coatings suggest that the addition of rare earth carboxylates effectively suppressed the initiation and growth of filaments as well as the development of the coating delamination front. The active corrosion inhibition is possibly related to the formation of a surface protective film consisting of bimetallic complexes and rare earth metal rich precipitates. The electrochemical measurements and surface analyses evidence the dual function of rare earth carboxylate species for enhancing coating barrier properties against electrolyte penetration and providing active corrosion inhibition for the underlying AS1020 mild steel
Metamorphosis of plasma turbulence-shear flow dynamics through a transcritical bifurcation
The structural properties of an economical model for a confined plasma
turbulence governor are investigated through bifurcation and stability
analyses. A close relationship is demonstrated between the underlying
bifurcation framework of the model and typical behavior associated with low- to
high-confinement transitions such as shear flow stabilization of turbulence and
oscillatory collective action. In particular, the analysis evinces two types of
discontinuous transition that are qualitatively distinct. One involves
classical hysteresis, governed by viscous dissipation. The other is
intrinsically oscillatory and non-hysteretic, and thus provides a model for the
so-called dithering transitions that are frequently observed. This
metamorphosis, or transformation, of the system dynamics is an important late
side-effect of symmetry-breaking, which manifests as an unusual non-symmetric
transcritical bifurcation induced by a significant shear flow drive.Comment: 17 pages, revtex text, 9 figures comprised of 16 postscript files.
Submitted to Phys. Rev.
TGF- mediates early angiogenesis and latent fibrosis in an Emilin1-deficient mouse model of aortic valve disease
Quasar accretion disk sizes from continuum reverberation mapping in the DES standard-star fields
Measurements of the physical properties of accretion disks in active galactic
nuclei are important for better understanding the growth and evolution of
supermassive black holes. We present the accretion disk sizes of 22 quasars
from continuum reverberation mapping with data from the Dark Energy Survey
(DES) standard star fields and the supernova C fields. We construct continuum
lightcurves with the \textit{griz} photometry that span five seasons of DES
observations. These data sample the time variability of the quasars with a
cadence as short as one day, which corresponds to a rest frame cadence that is
a factor of a few higher than most previous work. We derive time lags between
bands with both JAVELIN and the interpolated cross-correlation function method,
and fit for accretion disk sizes using the JAVELIN Thin Disk model. These new
measurements include disks around black holes with masses as small as
, which have equivalent sizes at 2500\AA \, as small as
light days in the rest frame. We find that most objects have
accretion disk sizes consistent with the prediction of the standard thin disk
model when we take disk variability into account. We have also simulated the
expected yield of accretion disk measurements under various observational
scenarios for the Large Synoptic Survey Telescope Deep Drilling Fields. We find
that the number of disk measurements would increase significantly if the
default cadence is changed from three days to two days or one day.Comment: 33 pages, 24 figure
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