823 research outputs found
An integrative approach based on probabilistic modelling and statistical inference for morpho-statistical characterization of astronomical data
This paper describes several applications in astronomy and cosmology that are
addressed using probabilistic modelling and statistical inference
Cold ultrarelativistic pulsar winds as potential sources of galactic gamma-ray lines above 100 GeV
The evidence of a line-like spectral feature at 130 GeV recently reported
from some parts of the galactic plane poses serious challenges for any
interpretation of this surprise discovery. It is generally believed that the
unusually narrow profile of the spectral line cannot be explained by
conventional processes in astrophysical objects, and, if real, is likely to be
associated with Dark Matter. In this paper we argue that cold ultrarelativistic
pulsar winds can be alternative sources of very narrow gamma-ray lines. We
demonstrate that Comptonization of a cold ultrarelativistic electron-positron
pulsar wind in the deep Klein-Nishina regime can readily provide very narrow
distinct gamma-ray line features. To verify this prediction, we produced photon
count maps based on the Fermi LAT data in the energy interval 100 to 140 GeV.
We confirm earlier reports of the presence of marginal gamma-ray line-like
signals from three regions of the galactic plane. Although the maps show some
structure inside these regions, unfortunately the limited photon statistics do
not allow any firm conclusion in this regard. The confirmation of 130 GeV line
emission by low-energy threshold atmospheric Cherenkov telescope systems, in
particular by the new 27 m diameter dish of the H.E.S.S. array, would be
crucial for resolving the spatial structure of the reported hotspots, and thus
for distinguishing between the Dark Matter and Pulsar origins of the `Fermi
Lines'.Comment: 5 pages. 4 figure
BOSS Great Wall: morphology, luminosity, and mass
We study the morphology, luminosity and mass of the superclusters from the
BOSS Great Wall (BGW), a recently discovered very rich supercluster complex at
the redshift . We have employed the Minkowski functionals to quantify
supercluster morphology. We calculate supercluster luminosities and masses
using two methods. Firstly, we used data about the luminosities and stellar
masses of high stellar mass galaxies with .
Secondly, we applied a scaling relation that combines morphological and
physical parameters of superclusters to obtain supercluster luminosities, and
obtained supercluster masses using the mass-to-light ratios found for local
rich superclusters. We find that the BGW superclusters are very elongated
systems, with shape parameter values of less than . This value is lower
than that found for the most elongated local superclusters. The values of the
fourth Minkowski functional for the richer BGW superclusters (
and ) show that they have a complicated and rich inner structure. We
identify two Planck SZ clusters in the BGW superclusters, one in the richest
BGW supercluster, and another in one of the poor BGW superclusters. The
luminosities of the BGW superclusters are in the range of , and masses in the range of . Supercluster luminosities and masses obtained
with two methods agree well. We conclude that the BGW is a complex of massive,
luminous and large superclusters with very elongated shape. The search and
detailed study, including the morphology analysis of the richest superclusters
and their complexes from observations and simulations can help us to understand
formation and evolution of the cosmic web.Comment: Comments: 10 pages, 2 figures, A&A, in pres
Enhancing Land Development Decision-Making to Reduce Water Quality Impacts
2010 S.C. Water Resources Conference - Science and Policy Challenges for a Sustainable Futur
Atherosclerotic Plaque Stability Is Affected by the Chemokine CXCL10 in Both Mice and Humans.
Background. The chemokine CXCL10 is specifically upregulated during experimental development of plaque with an unstable phenotype. In this study we evaluated the functional consequences of these findings in mice and humans. Methods and Results. In ApoE(-/-) mice, we induced unstable plaque with using a flow-altering device around the carotid artery. From week 1 to 4, mice were injected with a neutralizing CXCL10 antibody. After 9 weeks, CXCL10 inhibition resulted in a more stable plaque phenotype: collagen increased by 58% (P = 0.002), smooth muscle cell content increased 2-fold (P = 0.03), while macrophage MHC class II expression decreased by 50% (P = 0.005). Also, the size of necrotic cores decreased by 41% (P = 0.01). In 106 human carotid endarterectomy specimens we found that increasing concentrations of CXCL10 strongly associate with an increase in atheromatous plaque phenotype (ANOVA, P = 0.003), with high macrophage, low smooth muscle cell, and low collagen content. Conclusions. In the present study we showed that CXCL10 is associated with the development of vulnerable plaque in human and mice. We conclude that CXCL10 might provide a new lead towards plaque-stabilizing therapy
Проблемність законодавчого забезпечення працевлаштування молоді
RATIONALE: Neovascularization stimulated by local or recruited stem cells after ischemia is a key process that salvages damaged tissue and shows similarities with embryonic vascularization. Apelin receptor (Aplnr) and its endogenous ligand apelin play an important role in cardiovascular development. However, the role of apelin signaling in stem cell recruitment after ischemia is unknown. OBJECTIVE: To investigate the role of apelin signaling in recruitment after ischemia. METHODS AND RESULTS: Aplnr was specifically expressed in circulating cKit+/Flk1+ cells but not in circulating Sca1+/Flk1+ and Lin+ cells. cKit+/Flk1+/Aplnr+ cells increased significantly early after myocardial ischemia but not after hind limb ischemia, indicative of an important role for apelin/Aplnr in cell recruitment during the nascent biological repair response after myocardial damage. In line with this finding, apelin expression was upregulated in the infarcted myocardium. Injection of apelin into the ischemic myocardium resulted in accelerated and increased recruitment of cKit+/Flk1+/Aplnr+ cells to the heart. Recruited Aplnr+/cKit+/Flk1+ cells promoted neovascularization in the peri-infarct area by paracrine activity rather than active transdifferentiation, resulting into cardioprotection as indicated by diminished scar formation and improved residual cardiac function. Aplnr knockdown in the bone marrow resulted in aggravation of myocardial ischemia-associated damage, which could not be rescued by apelin. CONCLUSIONS: We conclude that apelin functions as a new and potent chemoattractant for circulating cKit+/Flk1+/Aplnr+ cells during early myocardial repair, providing myocardial protection against ischemic damage by improving neovascularization via paracine action
Recovering 3D structural properties of galaxies from SDSS-like photometry
Because of the 3D nature of galaxies, an algorithm for constructing spatial
density distribution models of galaxies on the basis of galaxy images has many
advantages over surface density distribution approximations. We present a
method for deriving spatial structure and overall parameters of galaxies from
images and estimate its accuracy and derived parameter degeneracies on a sample
of idealised model galaxies. The test galaxies consist of a disc-like component
and a spheroidal component with varying proportions and properties. Both
components are assumed to be axially symmetric and coplanar. We simulate these
test galaxies as if observed in the SDSS project through ugriz filters, thus
gaining a set of realistically imperfect images of galaxies with known
intrinsic properties. These artificial SDSS galaxies were thereafter remodelled
by approximating the surface brightness distribution with a 2D projection of a
bulge+disc spatial distribution model and the restored parameters were compared
to the initial ones. Down to the r-band limiting magnitude 18, errors of the
restored integral luminosities and colour indices remain within 0.05 mag and
errors of the luminosities of individual components within 0.2 mag. Accuracy of
the restored bulge-to-disc ratios (B/D) is within 40% in most cases, and
becomes worse for galaxies with low B/D, but the general balance between bulges
and discs is not shifted systematically. Assuming that the intrinsic disc axial
ratio is < 0.3, the inclination angles can be estimated with errors < 5deg for
most of the galaxies with B/D < 2 and with errors < 15deg up to B/D = 6. Errors
of the recovered sizes of the galactic components are below 10% in most cases.
In general, models of disc components are more accurate than models of
spheroidal components for geometrical reasons.Comment: 15 pages, 13 figures, accepted for publication in RA
Common Variants Associated With OSMR Expression Contribute to Carotid Plaque Vulnerability, but Not to Cardiovascular Disease in Humans
Background and Aims: Oncostatin M (OSM) signaling is implicated in atherosclerosis, however the mechanism remains unclear. We investigated the impact of common genetic variants in OSM and its receptors, OSMR and LIFR, on overall plaque vulnerability, plaque phenotype, intraplaque OSMR and LIFR expression, coronary artery calcification burden and cardiovascular disease susceptibility.
Methods and Results: We queried Genotype-Tissue Expression data and found that rs13168867 (C allele) was associated with decreased OSMR expression and that rs10491509 (A allele) was associated with increased LIFR expression in arterial tissues. No variant was significantly associated with OSM expression.
We associated these two variants with plaque characteristics from 1,443 genotyped carotid endarterectomy patients in the Athero-Express Biobank Study. After correction for multiple testing, rs13168867 was significantly associated with an increased overall plaque vulnerability (β = 0.118 ± s.e. = 0.040, p = 3.00 × 10−3, C allele). Looking at individual plaque characteristics, rs13168867 showed strongest associations with intraplaque fat (β = 0.248 ± s.e. = 0.088, p = 4.66 × 10−3, C allele) and collagen content (β = −0.259 ± s.e. = 0.095, p = 6.22 × 10−3, C allele), but these associations were not significant after correction for multiple testing. rs13168867 was not associated with intraplaque OSMR expression. Neither was intraplaque OSMR expression associated with plaque vulnerability and no known OSMR eQTLs were associated with coronary artery calcification burden, or cardiovascular disease susceptibility. No associations were found for rs10491509 in the LIFR locus.
Conclusions: Our study suggests that rs1316887 in the OSMR locus is associated with increased plaque vulnerability, but not with coronary calcification or cardiovascular disease risk. It remains unclear through which precise biological mechanisms OSM signaling exerts its effects on plaque morphology. However, the OSM-OSMR/LIFR pathway is unlikely to be causally involved in lifetime cardiovascular disease susceptibility
Gamma Lines without a Continuum: Thermal Models for the Fermi-LAT 130 GeV Gamma Line
Recent claims of a line in the Fermi-LAT photon spectrum at 130 GeV are
suggestive of dark matter annihilation in the galactic center and other dark
matter-dominated regions. If the Fermi feature is indeed due to dark matter
annihilation, the best-fit line cross-section, together with the lack of any
corresponding excess in continuum photons, poses an interesting puzzle for
models of thermal dark matter: the line cross-section is too large to be
generated radiatively from open Standard Model annihilation modes, and too
small to provide efficient dark matter annihilation in the early universe. We
discuss two mechanisms to solve this puzzle and illustrate each with a simple
reference model in which the dominant dark matter annihilation channel is
photonic final states. The first mechanism we employ is resonant annihilation,
which enhances the annihilation cross-section during freezeout and allows for a
sufficiently large present-day annihilation cross section. Second, we consider
cascade annihilation, with a hierarchy between p-wave and s-wave processes.
Both mechanisms require mass near-degeneracies and predict states with masses
closely related to the dark matter mass; resonant freezeout in addition
requires new charged particles at the TeV scale.Comment: 17 pages, 8 figure
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