3,022 research outputs found
Heparin Reduces Neuroinflammation and Transsynaptic Neuronal Apoptosis in a Model of Subarachnoid Hemorrhage
Subarachnoid hemorrhage (SAH) can lead to disabling motor, cognitive, and neuropsychological abnormalities. Part of the secondary injury to cerebral tissues associated with SAH is attributable to the neuroinflammatory response induced by blood. Heparin is a pleiotropic compound that reduces inflammatory responses in conditions outside the central nervous system. Using a model of SAH devoid of global insult, we evaluated the effect of delayed intravenous (IV) infusion of heparin, at a dose that does not produce therapeutic anticoagulation, on neuroinflammation, myelin preservation, and apoptosis. Adult male rats underwent bilateral stereotactic injections of autologous blood (50 μL) into the subarachnoid space of the entorhinal cortex. The rats were implanted with mini-osmotic pumps that delivered either vehicle or unfractionated heparin (10 U/kg/h IV) beginning 12 h after SAH. No mechanical or hemorrhagic injury was observed in the hippocampus. In vehicle controls assessed at 48 h, SAH was associated with robust neuroinflammation in the adjacent cortex [neutrophils, activated phagocytic microglia, nuclear factor-kappa B, tumor necrosis factor-alpha, and interleukin-1beta] and neurodegeneration (Fluoro-Jade C staining and loss of NeuN). In the hippocampus, a muted neuroinflammatory response was indicated by Iba1-positive, ED1-negative microglia exhibiting an activated morphology. The perforant pathway showed Fluoro-Jade C staining and demyelination, and granule cells of the dentate gyrus had pyknotic nuclei, labeled with Fluoro-Jade C and showed upregulation of cleaved caspase-3, consistent with transsynaptic apoptosis. Administration of heparin significantly reduced neuroinflammation, demyelination, and transsynaptic apoptosis. We conclude that delayed IV infusion of low-dose unfractionated heparin may attenuate adverse neuroinflammatory effects of SAH
Immune-Related Gene Expression in Two B-Complex Disparate Genetically Inbred Fayoumi Chicken Lines Following Eimeria maxima Infection
To investigate the influence of genetic differences in the MHC on susceptibility to avian coccidiosis, M5.1 and M15.2 B-haplotype-disparate Fayoumi chickens were orally infected with live Eimeria maxima oocysts, and BW gain, fecal oocyst production, and expression of 14 immune-related genes were determined as parameters of protective immunity. Weight loss was reduced and fecal parasite numbers were lower in birds of the M5.1 line compared with M15.2 line birds. Intestinal intraepithelial lymphocytes from M5.1 chickens expressed greater levels of transcripts encoding interferon-γ (IFN-γ), interleukin-1β (IL-1β), IL-6, IL-8, IL-12, IL-15, IL-17A, inducible nitric oxide synthase, and lipopolysaccharide-induced tumor necrosis factor-α factor and lower levels of mRNA for IFN-α, IL-10, IL-17D, NK-lysin, and tumor necrosis factor superfamily 15 compared with the M15.2 line. In the spleen, E. maxima infection was associated with greater expression levels of IFN-γ, IL-15, and IL-8 and lower levels of IL-6, IL-17D, and IL-12 in M5.1 vs. M15.2 birds. These results suggest that genetic determinants within the chicken MHC influence resistance to E. maxima infection by controlling the local and systemic expression of immune-related cytokine and chemokine genes
Spin-Peierls transition in an anisotropic two-dimensional XY model
The two-dimensional Jordan-Wigner transformation is used to investigate the
zero temperature spin-Peierls transition for an anisotropic two-dimensional XY
model in adiabatic limit. The phase diagram between the dimerized (D) state and
uniform (U) state is shown in the parameter space of dimensionless interchain
coupling and spin-lattice coupling . It is found
that the spin-lattice coupling must exceed some critical value
in order to reach the D phase for any finite . The dependence of on
is given by for and the transition between U and D
phase is of first-order for at least .Comment: 2 eps figures, considerable revisions were mad
The optimal approach of detecting stochastic gravitational wave from string cosmology using multiple detectors
String cosmology models predict a relic background of gravitational wave
produced during the dilaton-driven inflation. It's spectrum is most likely to
be detected by ground gravitational wave laser interferometers (IFOs), like
LIGO, Virgo, GEO, as the energy density grows rapidly with frequency. We show
the certain ranges of the parameters that underlying string cosmology model
using two approaches, associated with 5% false alarm and 95% detection rate.
The result presents that the approach of combining multiple pairs of IFOs is
better than the approach of directly combining the outputs of multiple IFOs for
LIGOH, LIGOL, Virgo and GEO.Comment: 4 pages, 4 figures, accepted for publication in Physics Letters
Bulk spectral function sum rule in QCD-like theories with a holographic dual
We derive the sum rule for the spectral function of the stress-energy tensor
in the bulk (uniform dilatation) channel in a general class of strongly coupled
field theories. This class includes theories holographically dual to a theory
of gravity coupled to a single scalar field, representing the operator of the
scale anomaly. In the limit when the operator becomes marginal, the sum rule
coincides with that in QCD. Using the holographic model, we verify explicitly
the cancellation between large and small frequency contributions to the
spectral integral required to satisfy the sum rule in such QCD-like theories.Comment: 16 pages, 2 figure
Transport Properties of the Quark-Gluon Plasma -- A Lattice QCD Perspective
Transport properties of a thermal medium determine how its conserved charge
densities (for instance the electric charge, energy or momentum) evolve as a
function of time and eventually relax back to their equilibrium values. Here
the transport properties of the quark-gluon plasma are reviewed from a
theoretical perspective. The latter play a key role in the description of
heavy-ion collisions, and are an important ingredient in constraining particle
production processes in the early universe. We place particular emphasis on
lattice QCD calculations of conserved current correlators. These Euclidean
correlators are related by an integral transform to spectral functions, whose
small-frequency form determines the transport properties via Kubo formulae. The
universal hydrodynamic predictions for the small-frequency pole structure of
spectral functions are summarized. The viability of a quasiparticle description
implies the presence of additional characteristic features in the spectral
functions. These features are in stark contrast with the functional form that
is found in strongly coupled plasmas via the gauge/gravity duality. A central
goal is therefore to determine which of these dynamical regimes the quark-gluon
plasma is qualitatively closer to as a function of temperature. We review the
analysis of lattice correlators in relation to transport properties, and
tentatively estimate what computational effort is required to make decisive
progress in this field.Comment: 54 pages, 37 figures, review written for EPJA and APPN; one parag.
added end of section 3.4, and one at the end of section 3.2.2; some Refs.
added, and some other minor change
Response of Holographic QCD to Electric and Magnetic Fields
We study the response of the Sakai-Sugimoto holographic model of large N_c
QCD at nonzero temperature to external electric and magnetic fields. In the
electric case we find a first-order insulator-conductor transition in both the
confining and deconfining phases of the model. In the deconfining phase the
conductor is described by the parallel 8-brane-anti-8-brane embedding with a
current of quarks and anti-quarks. We compute the conductivity and show that it
agrees precisely with a computation using the Kubo formula. In the confining
phase we propose a new kind of 8-brane embedding, corresponding to a baryonic
conductor. In the magnetic field case we show that the critical temperature for
chiral-symmetry restoration in the deconfined phase increases with the field
and approaches a finite value in the limit of an infinite magnetic field. We
also illustrate the nonlinear behavior of the electric and magnetic
susceptibilities in the different phases.Comment: 18 pages, 19 figures; reference added, version published in JHE
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Projected future changes in tropical cyclones using the CMIP6 HighResMIP multimodel ensemble
Future changes in tropical cyclone properties are an important component of climate change impacts and risk for many tropical and midlatitude countries. In this study we assess the performance of a multimodel ensemble of climate models, at resolutions ranging from 250 to 25 km. We use a common experimental design including both atmosphere‐only and coupled simulations run over the period 1950–2050, with two tracking algorithms applied uniformly across the models. There are overall improvements in tropical cyclone frequency, spatial distribution, and intensity in models at 25 km resolution, with several of them able to represent very intense storms. Projected tropical cyclone activity by 2050 generally declines in the South Indian Ocean, while changes in other ocean basins are more uncertain and sensitive to both tracking algorithm and imposed forcings. Coupled models with smaller biases suggest a slight increase in average TC 10 m wind speeds by 2050
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