1,318 research outputs found
Rapidity Profile of the Initial Energy Density in Heavy-Ion Collisions
The rapidity dependence of the initial energy density in heavy-ion collisions
is calculated from a three-dimensional McLerran-Venugopalan model (3dMVn)
introduced by Lam and Mahlon. This model is infrared safe since global color
neutrality is enforced. In this non-boost-invariant framework, the nuclei have
non-zero thickness in the longitudinal direction. This results in Bjorken-x
dependent unintegrated gluon distribution functions which lead to a
rapidity-dependent initial energy density after the collision. The initial
energy density and its rapidity dependence are important initial conditions for
the quark gluon plasma and its hydrodynamic evolution.Comment: 7 pages, 2 figures. Matches the published versio
Noise Dressing of Financial Correlation Matrices
We show that results from the theory of random matrices are potentially of
great interest to understand the statistical structure of the empirical
correlation matrices appearing in the study of price fluctuations. The central
result of the present study is the remarkable agreement between the theoretical
prediction (based on the assumption that the correlation matrix is random) and
empirical data concerning the density of eigenvalues associated to the time
series of the different stocks of the S&P500 (or other major markets). In
particular the present study raises serious doubts on the blind use of
empirical correlation matrices for risk management.Comment: Latex (Revtex) 3 pp + 2 postscript figures (in-text
Universality for orthogonal and symplectic Laguerre-type ensembles
We give a proof of the Universality Conjecture for orthogonal (beta=1) and
symplectic (beta=4) random matrix ensembles of Laguerre-type in the bulk of the
spectrum as well as at the hard and soft spectral edges. Our results are stated
precisely in the Introduction (Theorems 1.1, 1.4, 1.6 and Corollaries 1.2, 1.5,
1.7). They concern the appropriately rescaled kernels K_{n,beta}, correlation
and cluster functions, gap probabilities and the distributions of the largest
and smallest eigenvalues. Corresponding results for unitary (beta=2)
Laguerre-type ensembles have been proved by the fourth author in [23]. The
varying weight case at the hard spectral edge was analyzed in [13] for beta=2:
In this paper we do not consider varying weights.
Our proof follows closely the work of the first two authors who showed in
[7], [8] analogous results for Hermite-type ensembles. As in [7], [8] we use
the version of the orthogonal polynomial method presented in [25], [22] to
analyze the local eigenvalue statistics. The necessary asymptotic information
on the Laguerre-type orthogonal polynomials is taken from [23].Comment: 75 page
CL9 - PRESENCE OF GLUT4 AND SGLT1 IN DUCTAL CELLS OF NORMAL AND STREPTOZOTOCIN RAT SALIVARY GLANDS
Feeding a Protective Hydrolysed Casein Diet to Young Diabetes-prone BB Rats Affects Oxidation of L[U−C14] glutamine in Islets and Peyer's Patches, Reduces Abnormally High Mitotic Activity in Mesenteric Lymph Nodes, Enhances Islet Insulin and Tends to Normalize NO Production
The present studies were undertaken to examine
concomitant diet-induced changes in pancreatic
islets and cells of the gut immune system of
diabetes-prone BB rats in the period before classic
insulitis. Diabetes-prone (BBdp) and control non-diabetes
prone (BBc) BB rats were fed for ~ 17 days
either a mainly plant-based standard laboratory
rodent diet associated with high diabetes frequency,
NIH-07 (NIH) or a protective semipurified diet with
hydrolyzed casein (HC) as the amino acid source. By
about 7 weeks of age, NIH-fed BBdp rats had lower
plasma insulin and insulin/glucose ratio, lower
insulin content of isolated islets, lower basal levels
of NO but higher responsiveness of NO production
to IL-1β in cultured islets, and higher Con A
response and biosynthetic activities in mesenteric
lymphocytes than control rats fed the same diet. In
control rats, the HC diet caused only minor changes
in most variables, except for a decrease in oxidation
of L-[U−C14]glutamine in Peyer's patch (PP) cells and
an increase in protein biosynthesis in mesenteric
lymphocytes. In BBdp rats, however, the HC diet increased plasma insulin concentration, islet insulin/
protein ratio, and tended to normalize the basal
and IL-1β-stimulated NO production by cultured
islets. The HC diet decreased oxidation of L-[U−C14]glutamine in BBdp pancreatic islets, whereas
oxidation of L-[U−C14]glutamine in PP cells was
increased, and the basal [Methyl-H3] thymidine
incorporation in mesenteric lymphocytes was decreased.
These findings are compatible with the
view that alteration of nutrient catabolism in islet
cells as well as key cells of the gut immune system,
particularly changes in mitotic and biosynthetic
activities in mesenteric lymphocytes, as well as
basal and IL-1β stimulated NO production, participate
in the sequence of events leading to autoimmune
diabetes in BB rats. Thus, the protection afforded by feeding a hydrolysed casein-based diet
derives from alterations in both the target islet tissue
and key cells of the gut immune system in this
animal model of type 1 diabetes
Integration of energy and electron transfer processes in the photosynthetic membrane of Rhodobacter sphaeroides
Photosynthesis converts absorbed solar energy to a protonmotive force, which drives ATP synthesis. The membrane network of chlorophyll–protein complexes responsible for light absorption, photochemistry and quinol (QH2) production has been mapped in the purple phototrophic bacterium Rhodobacter (Rba.) sphaeroides using atomic force microscopy (AFM), but the membrane location of the cytochrome bc1 (cytbc1) complexes that oxidise QH2 to quinone (Q) to generate a protonmotive force is unknown. We labelled cytbc1 complexes with gold nanobeads, each attached by a Histidine10 (His10)-tag to the C-terminus of cytc1. Electron microscopy (EM) of negatively stained chromatophore vesicles showed that the majority of the cytbc1 complexes occur as dimers in the membrane. The cytbc1 complexes appeared to be adjacent to reaction centre light-harvesting 1-PufX (RC–LH1–PufX) complexes, consistent with AFM topographs of a gold-labelled membrane. His-tagged cytbc1 complexes were retrieved from chromatophores partially solubilised by detergent; RC–LH1–PufX complexes tended to co-purify with cytbc1 whereas LH2 complexes became detached, consistent with clusters of cytbc1 complexes close to RC–LH1–PufX arrays, but not with a fixed, stoichiometric cytbc1–RC–LH1–PufX supercomplex. This information was combined with a quantitative mass spectrometry (MS) analysis of the RC, cytbc1, ATP synthase, cytaa3 and cytcbb3 membrane protein complexes, to construct an atomic-level model of a chromatophore vesicle comprising 67 LH2 complexes, 11 LH1–RC–PufX dimers & 2 RC–LH1–PufX monomers, 4 cytbc1 dimers and 2 ATP synthases. Simulation of the interconnected energy, electron and proton transfer processes showed a half-maximal ATP turnover rate for a light intensity equivalent to only 1% of bright sunlight. Thus, the photosystem architecture of the chromatophore is optimised for growth at low light intensities
Salivary Glucose Concentration and Excretion in Normal and Diabetic Subjects
The present report aims mainly at a reevaluation of salivary glucose concentration and excretion in unstimulated and mechanically stimulated saliva in both normal and diabetic subjects. In normal subjects, a decrease in saliva glucose concentration, an increase in salivary flow, but an unchanged glucose excretion
rate were recorded when comparing stimulated saliva to unstimulated saliva. In diabetic patients, an increase in salivary flow with unchanged
salivary glucose concentration and glucose excretion rate were observed under the same
experimental conditions. Salivary glucose concentration and excretion were much higher in
diabetic patients than in control subjects, whether in unstimulated or stimulated saliva. No
significant correlation between glycemia and either glucose concentration or glucose
excretion rate was found in the diabetic patients, whether in unstimulated or stimulated saliva.
In the latter patients, as compared to control subjects, the relative magnitude of the increase in
saliva glucose concentration was comparable, however, to that of blood glucose
concentration. The relationship between these two variables was also documented in normal
subjects and diabetic patients undergoing an oral glucose tolerance test
Small eigenvalues of the staggered Dirac operator in the adjoint representation and Random Matrix Theory
The low-lying spectrum of the Dirac operator is predicted to be universal,
within three classes, depending on symmetry properties specified according to
random matrix theory. The three universal classes are the orthogonal, unitary
and symplectic ensemble. Lattice gauge theory with staggered fermions has
verified two of the cases so far, unitary and symplectic, with staggered
fermions in the fundamental representation of SU(3) and SU(2). We verify the
missing case here, namely orthogonal, with staggered fermions in the adjoint
representation of SU(N_c), N_c=2, 3.Comment: 3 pages, revtex, 2 postscript figure
Character Expansions for the Orthogonal and Symplectic Groups
Formulas for the expansion of arbitrary invariant group functions in terms of
the characters for the Sp(2N), SO(2N+1), and SO(2N) groups are derived using a
combinatorial method. The method is similar to one used by Balantekin to expand
group functions over the characters of the U(N) group. All three expansions
have been checked for all N by using them to calculate the known expansions of
the generating function of the homogeneous symmetric functions. An expansion of
the exponential of the traces of group elements, appearing in the finite-volume
gauge field partition functions, is worked out for the orthogonal and
symplectic groups.Comment: 20 pages, in REVTE
- …