3,063 research outputs found
Global-String and Vortex Superfluids in a Supersymmetric Scenario
The main goal of this work is to investigate the possibility of finding the
supersymmetric version of the U(1)-global string model which behaves as a
vortex-superfluid. To describe the superfluid phase, we introduce a
Lorentz-symmetry breaking background that, in an approach based on
supersymmetry, leads to a discussion on the relation between the violation of
Lorentz symmetry and explicit soft supersymmetry breakings. We also study the
relation between the string configuration and the vortex-superfluid phase. In
the framework we settle down in terms of superspace and superfields, we
actually establish a duality between the vortex degrees of freedom and the
component fields of the Kalb-Ramond superfield. We make also considerations
about the fermionic excitations that may appear in connection with the vortex
formation.Comment: 9 pages. This version presented the relation between Lorentz symmetry
violation by the background and the appearance of terms that explicitly break
SUS
Plane Gravitational Radiation from Neutrinos Source with Kalb-Ramond Coupling
In this work, we propose a model based on a non-minimal coupling of neutrinos
to a Kalb-Ramond field. The latter is taken as a possible source for
gravitational radiation. As an immediate illustration of this system, we have
studied the case where gravitational (plane) wave solutions behave as damped
harmonic oscillators.Comment: Presented at 7th Alexander Friedmann International Seminar on
Gravitation and Cosmology, Joao Pessoa, Brazil, 29-05 Jul 200
Canonical transformation for stiff matter models in quantum cosmology
In the present work we consider Friedmann-Robertson-Walker models in the
presence of a stiff matter perfect fluid and a cosmological constant. We write
the superhamiltonian of these models using the Schutz's variational formalism.
We notice that the resulting superhamiltonians have terms that will lead to
factor ordering ambiguities when they are written as operators. In order to
remove these ambiguities, we introduce appropriate coordinate transformations
and prove that these transformations are canonical using the symplectic method.Comment: Revtex4 Class, 3 pages, No Figure
Induction of Colon Cancer Cell Death by Cranberry Proanthocyanidins via MAPK Pathway
The potential ability of dietary cranberry to inhibit colon carcinogenesis is under investigation. Compounds isolated from locally grown cranberry fruit (Vaccinium macrocarpon) have been shown in vitro to decrease proliferation of colon cancer cells, in part by induction of apoptosis. These compounds include oligomeric polyphenols known as proanthocyanidins (PACs) containing two or more epicatechin units with different types of linkages. To further elucidate the mechanism by which PACs induce cell death, we transcriptionally profiled cells treated with PACs. HCT116 and HT29 colon cancer cells were exposed to a cranberry proanthocyanidin (PACs) fraction isolated from Early Black variety cranberry fruit, at time intervals of 6, 12, 18 and 24 hours. Total RNA was extracted from PAC-treated and untreated control cells. Transcriptional profiling was performed using an Illumina microarray bead system. Microarray results revealed that expression of several members of the mitogen activated protein kinase family (MAPK) was significantly altered in the presence of PACs, leading to decreased transcription of genes in the nucleus and decreased tumor cell growth. Quantitative (Q)-PCR was used to confirm microarray data showing gene expression changes in some key apoptotic pathways. Western blotting was used to confirm the up- regulation or down-regulation of key proteins involved in the MAPK pathway. Significant changes in p53, APAF and VEGF protein expression were seen as early as eighteen hours. Flow cytometry was employed to identify changes in the cell cycle due to exposure to PACs. HCT116 and HT29 colon cancer cells showed a significant change in granularity and a significant increase in G2 arrest compared to control when exposed to PACs for as little as six hours. This study has provided insight into mechanisms by which cranberry PACs may inhibit colon cancer
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