11,008 research outputs found
Rare kaon decays in SUSY with non-universal A terms
We study the rare kaon decays in the framework of general SUSY models. Unlike
the results in the literature, we find the contributions from the gluino
exchange to the branching ratio of can reach the
central value () of the new E787 data while the
predicted value of standard model is less than . We also find that
the same effects also enhance the decays of ,
and .Comment: 9 pages, references added, revised version to appear in J. Phys.
Effects of Heparin and Enoxaparin on APP Processing and Aβ Production in Primary Cortical Neurons from Tg2576 Mice
BACKGROUND Alzheimer's disease (AD) is caused by accumulation of Aβ, which is produced through sequential cleavage of β-amyloid precursor protein (APP) by the β-site APP cleaving enzyme (BACE1) and γ-secretase. Enoxaparin, a low molecular weight form of the glycosaminoglycan (GAG) heparin, has been reported to lower Aβ plaque deposition and improve cognitive function in AD transgenic mice. METHODOLOGY/PRINCIPAL FINDINGS We examined whether heparin and enoxaparin influence APP processing and inhibit Aβ production in primary cortical cell cultures. Heparin and enoxaparin were incubated with primary cortical cells derived from Tg2576 mice, and the level of APP and proteolytic products of APP (sAPPα, C99, C83 and Aβ) was measured by western blotting. Treatment of the cells with heparin or enoxaparin had no significant effect on the level of total APP. However, both GAGs decreased the level of C99 and C83, and inhibited sAPPα and Aβ secretion. Heparin also decreased the level of β-secretase (BACE1) and α-secretase (ADAM10). In contrast, heparin had no effect on the level of ADAM17. CONCLUSIONS/SIGNIFICANCE The data indicate that heparin and enoxaparin decrease APP processing via both α- and β-secretase pathways. The possibility that GAGs may be beneficial for the treatment of AD needs further study.This work was funded by a project grant (490031) from the National Health and Medical Research Council of Australia (http://www.nhmrc.gov.au). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript
Rank 3 permutation characters and maximal subgroups
In this paper we classify all maximal subgroups M of a nearly simple
primitive rank 3 group G of type L=Omega_{2m+1}(3), m > 3; acting on an L-orbit
E of non-singular points of the natural module for L such that 1_P^G <=1_M^G
where P is a stabilizer of a point in E. This result has an application to the
study of minimal genera of algebraic curves which admit group actions.Comment: 41 pages, to appear in Forum Mathematicu
Experimental verification of a self-consistent theory of the first-, second-, and third-order (non)linear optical response
We show that a combination of linear absorption spectroscopy, hyper-Rayleigh
scattering, and a theoretical analysis using sum rules to reduce the size of
the parameter space leads to a prediction of the two-photon absorption
cross-section of the dye AF455 that agrees with two-photon absorption
spectroscopy. Our procedure, which demands self-consistency between several
measurement techniques and does not use adjustable parameters, provides a means
for determining transition moments between the dominant excited states based
strictly on experimental characterization. This is made possible by our new
approach that uses sum rules and molecular symmetry to rigorously reduce the
number of required physical quantities.Comment: 10 pages, 9 figure
A momentum-space representation of Feynman propagator in Riemann-Cartan spacetime
We first construct generalized Riemann-normal coordinates by using
autoparallels, instead of geodesics, in an arbitrary Riemann-Cartan spacetime.
With the aid of generalized Riemann-normal coordinates and their associated
orthonormal frames, we obtain a momentum-space representation of the Feynman
propagator for scalar fields, which is a direct generalization of Bunch and
Parker's works to curved spacetime with torsion. We further derive the
proper-time representation in dimensional Riemann-Cartan spacetime from the
momentum-space representation. It leads us to obtain the renormalization of
one-loop effective Lagrangians of free scalar fields by using dimensional
regularization. When torsion tensor vanishes, our resulting momentum-space
representation returns to the standard Riemannian results.Comment: 12 page
Direct Emission of multiple strange baryons in ultrarelativistic heavy-ion collisions from the phase boundary
We discuss a model for the space-time evolution of ultrarelativistic
heavy-ion collisions which employs relativistic hydrodynamics within one region
of the forward light-cone, and microscopic transport theory (i.e. UrQMD) in the
complement. Our initial condition consists of a quark-gluon plasma which
expands hydrodynamically and hadronizes. After hadronization the solution
eventually changes from expansion in local equilibrium to free streaming, as
determined selfconsistently by the interaction rates between the hadrons and
the local expansion rate. We show that in such a scenario the inverse slopes of
the -spectra of multiple strange baryons (, ) are practically
unaffected by the purely hadronic stage of the reaction, while the flow of
's and 's increases. Moreover, we find that the rather ``soft''
transverse expansion at RHIC energies (due to a first-order phase transition)
is not washed out by strong rescattering in the hadronic stage. The earlier
kinetic freeze-out as compared to SPS-energies results in similar inverse
slopes (of the -spectra of the hadrons in the final state) at RHIC and SPS
energies.Comment: 4 pages, 3 figures, statistics for Omegas improved, slight revision
of the manuscript (expansion of hadronization volume more emphasized,
pi-Omega scattering is discussed very briefly
Cosmological perturbations in f(T) gravity
We investigate the cosmological perturbations in f(T) gravity. Examining the
pure gravitational perturbations in the scalar sector using a diagonal
vierbien, we extract the corresponding dispersion relation, which provides a
constraint on the f(T) ansatzes that lead to a theory free of instabilities.
Additionally, upon inclusion of the matter perturbations, we derive the fully
perturbed equations of motion, and we study the growth of matter overdensities.
We show that f(T) gravity with f(T) constant coincides with General Relativity,
both at the background as well as at the first-order perturbation level.
Applying our formalism to the power-law model we find that on large subhorizon
scales (O(100 Mpc) or larger), the evolution of matter overdensity will differ
from LCDM cosmology. Finally, examining the linear perturbations of the vector
and tensor sectors, we find that (for the standard choice of vierbein) f(T)
gravity is free of massive gravitons.Comment: 11 pages, 4 figures. Analysis of the vector and tensor sectors adde
Poincar\'e gauge theory with even and odd parity dynamic connection modes: isotropic Bianchi cosmological models
The Poincar\'e gauge theory of gravity has a metric compatible connection
with independent dynamics that is reflected in the torsion and curvature. The
theory allows two good propagating spin-0 modes. Dynamical investigations using
a simple expanding cosmological model found that the oscillation of the 0
mode could account for an accelerating expansion similar to that presently
observed. The model has been extended to include a mode and more
recently cross parity couplings. We investigate the dynamics of this model in a
situation which is simple, non-trivial, and yet may give physically interesting
results that might be observable. We consider homogeneous cosmologies, more
specifically, isotropic Bianchi class A models. We find an effective Lagrangian
for our dynamical system, a system of first order equations, and present some
typical dynamical evolution.Comment: 8 pages, 1 figures, submitted to IARD 2010 Conference Proceedings in
{\em Journal of Physics: Conference Series}, eds. L. Horwitz and M. Land
(2011
Using interaction signatures to find and label chairs and floors
The use of interaction signatures to recognize objects without considering the object\u27s physical structure is discussed. Without object recognition, smart homes cannot make full use of video cameras because vision systems cannot provide object-related context to the human activities monitored. One important advantage of interaction signatures is that people frequently and repeatedly interact with household objects, so the system can build evidence for object locations and labels
- …