1,955 research outputs found
Symmetric Spaces and Star representations II : Causal Symmetric Spaces
We construct and identify star representations canonically associated with
holonomy reducible simple symplectic symmetric spaces. This leads the a
non-commutative geometric realization of the correspondence between causal
symmetric spaces of Cayley type and Hermitian symmetric spaces of tube type.Comment: 13 page
The Leiden/Argentine/Bonn (LAB) Survey of Galactic HI: Final data release of the combined LDS and IAR surveys with improved stray-radiation corrections
We present the final data release of observations of lambda 21-cm emission
from Galactic neutral hydrogen over the entire sky, merging the
Leiden/Dwingeloo Survey (LDS: Hartmann & Burton, 1997) of the sky north of
delta = -30 deg with the Instituto Argentino de Radioastronomia Survey (IAR:
Arnal et al., 2000, and Bajaja et al., 2005) of the sky south of delta = -25
deg. The angular resolution of the combined material is HPBW ~ 0.6 deg. The LSR
velocity coverage spans the interval -450 km/s to +400 km/s, at a resolution of
1.3 km/s. The data were corrected for stray radiation at the Institute for
Radioastronomy of the University of Bonn, refining the original correction
applied to the LDS. The rms brightness-temperature noise of the merged database
is 0.07 - 0.09 K. Residual errors in the profile wings due to defects in the
correction for stray radiation are for most of the data below a level of 20 -
40 mK. It would be necessary to construct a telescope with a main beam
efficiency of eta_{MB} > 99% to achieve the same accuracy. The merged and
refined material entering the LAB Survey of Galactic HI is intended to be a
general resource useful to a wide range of studies of the physical and
structural characteristices of the Galactic interstellar environment. The LAB
Survey is the most sensitive Milky Way HI survey to date, with the most
extensive coverage both spatially and kinematically.Comment: 9 pages, 5 figures, accepted for publication by Astronomy &
Astrophysic
Proanthocyanidins Modulate MicroRNA Expression in Human HepG2 Cells
Mi(cro)RNAs are small non-coding RNAs of 18-25 nucleotides in length that modulate gene expression at the post-transcriptional level. These RNAs have been shown to be involved in a several biological processes, human diseases and metabolic disorders. Proanthocyanidins, which are the most abundant polyphenol class in the human diet, have positive health effects on a variety of metabolic disorders such as inflammation, obesity, diabetes and insulin resistance. The present study aimed to evaluate whether proanthocyanidin-rich natural extracts modulate miRNA expression. Using microarray analysis and Q-PCR, we investigated miRNA expression in HepG2 cells treated with proanthocyanidins. Our results showed that when HepG2 cells were treated with grape seed proanthocyanidin extract (GSPE), cocoa proanthocyanidin extract (CPE) or pure epigallocatechin gallate isolated from green tea (EGCG), fifteen, six and five differentially expressed miRNAs, respectively, were identified out of 904 mRNAs. Specifically, miR-30b* was downregulated by the three treatments, and treatment with GSPE or CPE upregulated miR-1224-3p, miR-197 and miR-532-3p. Therefore, these results provide evidence of the capacity of dietary proanthocyanidins to influence microRNA expression, suggesting a new mechanism of action of proanthocyanidins
Monte Carlo Calculations on Electron Backscattering in Amorphous or Polycrystalline Targets
We propose an application of the Monte Carlo method in the field of backscattering. The results obtained for incident electron energies ranging from 0.3 to 3 MeV and for targets of Al, Cu, Ag and Au are compared with experimental values from several sources.
An electron travelling through matter undergoes successive collisions between which it is assumed to travel in a straight line. In our case, we consider the elementary process of interaction electron-nucleus; we have used analytical models for the scattering cross-sections. In order to follow the electron through the specimen, we divide the real trajectory into elements of length much smaller than the mean free path. Pseudo-random number process permits us to determine whether or not an interaction occurs, also the type of interaction. For the energy losses, we introduced a relation derived from Landau\u27s theory. We then followed the electron until it is emerged from the material or halted.
The backscattering coefficients obtained for thin and thick targets as a function of the incident electron energy are in good agreement with the experimental data. We have introduced the depth distribution function of the backscattered electrons, which allows us to test the predictions of various theoretical models proposed by other authors
Closedness of star products and cohomologies
We first review the introduction of star products in connection with
deformations of Poisson brackets and the various cohomologies that are related
to them. Then we concentrate on what we have called ``closed star products" and
their relations with cyclic cohomology and index theorems. Finally we shall
explain how quantum groups, especially in their recent topological form, are in
essence examples of star products.Comment: 16 page
Liver bioengineering using decellularized whole-liver scaffolds
Currently, due to the progress made in the field of regenerative medicine, whole-organ bioengineering is becoming a valid alternative to cope with the shortages of organs for transplantation. In this chapter, we describe the main techniques carried out for pig liver bioengineering, which serves as an essential model for future human liver bioengineering. These include porcine whole-liver decellularization, endothelial and mesenchymal stem cell isolation, porcine ES-derived hepatoblasts, and scaffold recellularization using a bioreactor perfusion system
IMPACT OF TYPE 2 DIABETES ON THE DEVELOPMENT OF PERIODONTAL DISEASE IN THE MOUSE
Oral Communication presented at the ";;Forum des Jeunes Chercheurs";;, Brest (France) 2011
HII Shells Surrounding Wolf-Rayet stars in M31
We present the results of an ongoing investigation to provide a detailed view
of the processes by which massive stars shape the surrounding interstellar
medium (ISM), from pc to kpc scales. In this paper we have focused on studying
the environments of Wolf-Rayet (WR) stars in M31 to find evidence for WR
wind-ISM interactions, through imaging ionized hydrogen nebulae surrounding
these stars.
We have conducted a systematic survey for HII shells surrounding 48 of the 49
known WR stars in M31. There are 17 WR stars surrounded by single shells, or
shell fragments, 7 stars surrounded by concentric limb brightened shells, 20
stars where there is no clear physical association of the star with nearby
H-alpha emission, and 4 stars which lack nearby H-alpha emission. For the 17+7
shells above, there are 12 which contain one or two massive stars (including a
WR star) and that are <=40 pc in radius. These 12 shells may be classical WR
ejecta or wind-blown shells. Further, there may be excess H-alpha point source
emission associated with one of the 12 WR stars surrounded by putative ejecta
or wind-blown shells. There is also evidence for excess point source emission
associated with 11 other WR stars. The excess emission may arise from
unresolved circumstellar shells, or within the extended outer envelopes of the
stars themselves.
In a few cases we find clear morphological evidence for WR shells interacting
with each other. In several H-alpha images we see WR winds disrupting, or
punching through, the walls of limb-brightened HII shells.Comment: 20 pages, 4 figures (in several parts: some .jpg and others .ps),
accepted to AJ (appearing Oct, 1999
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