143 research outputs found
The Wilson renormalization group for low x physics: towards the high density regime
We continue the study of the effective action for low physics based on a
Wilson renormalization group approach. We express the full nonlinear
renormalization group equation in terms of the average value and the average
fluctuation of extra color charge density generated by integrating out gluons
with intermediate values of . This form clearly exhibits the nature of the
phenomena driving the evolution and should serve as the basis of the analysis
of saturation effects at high gluon density at small .Comment: 14 pages, late
Influence of the Magnetic Field on the Fermion Scattering off Bubble and Kink Walls
We investigate the scattering of fermions off domain walls at the electroweak
phase transition in presence of a magnetic field. We consider both the bubble
wall and the kink domain wall. We derive and solve the Dirac equation for
fermions with momentum perpendicular to the walls, and compute the transmission
and reflection coefficients. In the case of kink domain wall, we briefly
discuss the zero mode solutions localized on the wall. The possibile role of
the magnetic field for the electroweak baryogenesis is also discussed.Comment: 11 pages and 3 eps figure
The Intrinsic Glue Distribution at Very Small x
We compute the distribution functions for gluons at very small x and not too
large values of transverse momenta. We extend the McLerran-Venugopalan model by
using renormalization group methods to integrate out effects due to those
gluons which generate an effective classical charge density for
Weizs\"acker-Williams fields. We argue that this model can be extended from the
description of nuclei at small x to the description of hadrons at yet smaller
values of x. This generates a Lipatov like enhancement for the intrinsic gluon
distribution function and a non-trivial transverse momentum dependence as well.
We estimate the transverse momentum dependence for the distribution functions,
and show how the issue of unitarity is resolved in lepton-nucleus interactions.Comment: 31 pages, Latex2e, 5 postecript figure included, using epsf,
latexsym, amssymb and fancyheading
Vector potential versus colour charge density in low-x evolution
We reconsider the evolution equations for multigluon correlators derived in
hep-ph/9709432. We show how to derive these equations directly in terms of
vector potentials (or colour field strength) avoiding the introduction of the
concept of colour charge density in the intermediate steps. The two step
procedure of deriving the evolution of the charge density correlators followed
by the solution of classical equations for the vector potentials is shown to be
consistent with direct derivation of evolution for vector potentials. In the
process we correct some computational errors of hep-ph/9709432 and present the
corrected evolution equations which have a somewhat simpler appearance.Comment: 15 pages, 1 figure, changes made referee report, to be published in
Phys. Rev
Unitarization of the BFKL Pomeron on a Nucleus
We analyze the evolution equation describing all multiple hard pomeron
exchanges in a hadronic or nuclear structure functions that was proposed
earlier. We construct a perturbation series providing us with an exact solution
to the equation outside of the saturation region. The series demonstrates how
at moderately high energies the corrections to the single BFKL pomeron exchange
contribution which are due to the multiple pomeron exchanges start unitarizing
total deep inelastic scattering cross section. We show that as energy increases
the scattering cross section of the quark-antiquark pair of a fixed transverse
separation on a hadron or nucleus given by the solution of our equation inside
of the saturation region unitarizes and becomes independent of energy. The
corresponding F_2 structure function also unitarizes and becomes linearly
proportional to ln s. We also discuss possible applications of the developed
technique to diffraction.Comment: REVTeX, 20 pages, 6 figure
Polarization of Lambda^0 hyperons in nucleus-nucleus collisions at high energies
The measurement of Lambda^0 hyperons polarization in nucleus-nucleus
collisions is considered as one of possible tools to study the phase
transition. Fixed target and collider experiments are discussed for the case of
Lambda^0's production from Au-Au central collisions at \sqrt{s_{NN}} of several
GeV.Comment: 15 pages, 6 figure
Guanylate-binding Protein 1 (GBP1) contributes to the immunity of human mesenchymal stromal cells against toxoplasma gondii
Mesenchymal stromal cells (MSCs) have recently been shown to play important roles in mammalian host defenses against intracellular pathogens, but the molecular mechanism still needs to be clarified. We confirmed that human MSCs (hMSCs) pre-stimulated with IFN-γ showed a significant and dose-dependent ability to inhibit the growth of two types of Toxoplasma gondii (type I strain RH/GFP or type II strain PLK/RED). However, in contrast to previous reports, the anti-T. gondii activity of hMSCs was not mediated by indoleamine 2,3-dioxygenase (IDO). Genome-wide RNA-seq analysis revealed that IFN-γ increased the expression of the p65 family of guanylate-binding proteins (hGBPs) in hMSCs, especially hGBP1. To analyze the functional role of hGBPs, stable knockdowns of hGBP1, -2, -5 in hMSCs were established using a lentiviral transfection system. hGBP1 knockdown in hMSCs resulted in a significant loss of the anti-T. gondii host defense property, compared with hMSCs infected with non-targetted control sequences. hGBP2 and -5 knockdowns had no effect. Moreover, the hGBP1 accumulation on the parasitophorous vacuole (PV) membranes of IFN-γ-stimulated hMSCs might protect against T. gondii infection. Taken together, our results suggest that hGBP1 plays a pivotal role in anti-T. gondii protection of hMSCs and may shed new light on clarifying the mechanism of host defense properties of hMSCs
A spectroscopic and proper motion search of Sloan Digital Sky Survey : red subdwarfs in binary systems
Red subdwarfs in binary systems are crucial for both model calibration and spectral classification. We search for red subdwarfs in binary systems from a sample of high proper motion objects with Sloan Digital Sky Survey spectroscopy. We present here discoveries from this search, as well as highlight several additional objects of interest. We find 30 red subdwarfs in wide binary systems including: two with spectral type of esdM5.5, 6 companions to white dwarfs and 3 carbon-enhanced red subdwarfs with normal red subdwarf companions. 15 red subdwarfs in our sample are partially resolved close binary systems. With this binary sample, we estimate the low limit of the red subdwarf binary fraction of similar to 10 per cent. We find that the binary fraction goes down with decreasing masses and metallicities of red subdwarfs. A spectroscopic esdK7 subdwarf + white dwarf binary candidate is also reported. 30 new M subdwarfs have spectral type of >= M6 in our sample. We also derive relationships between spectral types and absolute magnitudes in the optical and near-infrared for M and L subdwarfs, and we present an M subdwarf sample with measured U, V, W space velocities.Peer reviewe
Eicosanoid Release Is Increased by Membrane Destabilization and CFTR Inhibition in Calu-3 Cells
The antiinflammatory protein annexin-1 (ANXA1) and the adaptor S100A10 (p11), inhibit cytosolic phospholipase A2 (cPLA2α) by direct interaction. Since the latter is responsible for the cleavage of arachidonic acid at membrane phospholipids, all three proteins modulate eicosanoid production. We have previously shown the association of ANXA1 expression with that of CFTR, the multifactorial protein mutated in cystic fibrosis. This could in part account for the abnormal inflammatory status characteristic of this disease. We postulated that CFTR participates in the regulation of eicosanoid release by direct interaction with a complex containing ANXA1, p11 and cPLA2α. We first analyzed by plasmon surface resonance the in vitro binding of CFTR to the three proteins. A significant interaction between p11 and the NBD1 domain of CFTR was found. We observed in Calu-3 cells a rapid and partial redistribution of all four proteins in detergent resistant membranes (DRM) induced by TNF-α. This was concomitant with increased IL-8 synthesis and cPLA2α activation, ultimately resulting in eicosanoid (PGE2 and LTB4) overproduction. DRM destabilizing agent methyl-β-cyclodextrin induced further cPLA2α activation and eicosanoid release, but inhibited IL-8 synthesis. We tested in parallel the effect of short exposure of cells to CFTR inhibitors Inh172 and Gly-101. Both inhibitors induced a rapid increase in eicosanoid production. Longer exposure to Inh172 did not increase further eicosanoid release, but inhibited TNF-α-induced relocalization to DRM. These results show that (i) CFTR may form a complex with cPLA2α and ANXA1 via interaction with p11, (ii) CFTR inhibition and DRM disruption induce eicosanoid synthesis, and (iii) suggest that the putative cPLA2/ANXA1/p11/CFTR complex may participate in the modulation of the TNF-α-induced production of eicosanoids, pointing to the importance of membrane composition and CFTR function in the regulation of inflammation mediator synthesis
Gene expression down-regulation in CD90+ prostate tumor-associated stromal cells involves potential organ-specific genes
<p>Abstract</p> <p>Background</p> <p>The prostate stroma is a key mediator of epithelial differentiation and development, and potentially plays a role in the initiation and progression of prostate cancer. The tumor-associated stroma is marked by increased expression of CD90/THY1. Isolation and characterization of these stromal cells could provide valuable insight into the biology of the tumor microenvironment.</p> <p>Methods</p> <p>Prostate CD90<sup>+ </sup>stromal fibromuscular cells from tumor specimens were isolated by cell-sorting and analyzed by DNA microarray. Dataset analysis was used to compare gene expression between histologically normal and tumor-associated stromal cells. For comparison, stromal cells were also isolated and analyzed from the urinary bladder.</p> <p>Results</p> <p>The tumor-associated stromal cells were found to have decreased expression of genes involved in smooth muscle differentiation, and those detected in prostate but not bladder. Other differential expression between the stromal cell types included that of the CXC-chemokine genes.</p> <p>Conclusion</p> <p>CD90<sup>+ </sup>prostate tumor-associated stromal cells differed from their normal counterpart in expression of multiple genes, some of which are potentially involved in organ development.</p
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