1,863,750 research outputs found
Analyticity Properties of Graham-Witten Anomalies
Analytic properties of Graham-Witten anomalies are considered. Weyl anomalies
according to their analytic properties are of type A (coming from
-singularities in correlators of several energy-momentum tensors) or of
type B (originating in counterterms which depend logarithmically on a mass
scale). It is argued that all Graham-Witten anomalies can be divided into 2
groups: internal and external, and that all external anomalies are of type B,
whereas among internal anomalies there is one term of type A and all the rest
are of type B. This argument is checked explicitly for the case of a free
scalar field in a 6-dimensional space with a 2-dimensional submanifold.Comment: 2 typos correcte
Protoadditive functors, derived torsion theories and homology
Protoadditive functors are designed to replace additive functors in a
non-abelian setting. Their properties are studied, in particular in
relationship with torsion theories, Galois theory, homology and factorisation
systems. It is shown how a protoadditive torsion-free reflector induces a chain
of derived torsion theories in the categories of higher extensions, similar to
the Galois structures of higher central extensions previously considered in
semi-abelian homological algebra. Such higher central extensions are also
studied, with respect to Birkhoff subcategories whose reflector is
protoadditive or, more generally, factors through a protoadditive reflector. In
this way we obtain simple descriptions of the non-abelian derived functors of
the reflectors via higher Hopf formulae. Various examples are considered in the
categories of groups, compact groups, internal groupoids in a semi-abelian
category, and other ones
Consistency analysis of Kaluza-Klein geometric sigma models
Geometric sigma models are purely geometric theories of scalar fields coupled
to gravity. Geometrically, these scalars represent the very coordinates of
space-time, and, as such, can be gauged away. A particular theory is built over
a given metric field configuration which becomes the vacuum of the theory.
Kaluza-Klein theories of the kind have been shown to be free of the classical
cosmological constant problem, and to give massless gauge fields after
dimensional reduction. In this paper, the consistency of dimensional reduction,
as well as the stability of the internal excitations, are analyzed. Choosing
the internal space in the form of a group manifold, one meets no
inconsistencies in the dimensional reduction procedure. As an example, the
SO(n) groups are analyzed, with the result that the mass matrix of the internal
excitations necessarily possesses negative modes. In the case of coset spaces,
the consistency of dimensional reduction rules out all but the stable mode,
although the full vacuum stability remains an open problem.Comment: 13 pages, RevTe
Torsion theories and coverings of preordered groups
In this article we explore a non-abelian torsion theory in the category of
preordered groups: the objects of its torsion-free subcategory are the
partially ordered groups, whereas the objects of the torsion subcategory are
groups (with the total order). The reflector from the category of preordered
groups to this torsion-free subcategory has stable units, and we prove that it
induces a monotone-light factorization system. We describe the coverings
relative to the Galois structure naturally associated with this reflector, and
explain how these coverings can be classified as internal actions of a Galois
groupoid. Finally, we prove that in the category of preordered groups there is
also a pretorsion theory, whose torsion subcategory can be identified with a
category of internal groups. This latter is precisely the subcategory of
protomodular objects in the category of preordered groups, as recently
discovered by Clementino, Martins-Ferreira, and Montoli.Comment: 21 pages, minor changes and improvement
Static quark anti-quark free and internal energy in 2-flavor QCD and bound states in the QGP
We present results on heavy quark free energies in 2-flavour QCD. The
temperature dependence of the interaction between static quark anti-quark pairs
will be analyzed in terms of temperature dependent screening radii, which give
a first estimate on the medium modification of (heavy quark) bound states in
the quark gluon plasma. Comparing those radii to the (zero temperature) mean
squared charge radii of cha rmonium states indicates that the may
survive the phase transition as a bound state, while and are
expected to show significant thermal modifications at temperatures close to the
transition. Furthermore we will analyze the relation between heavy quark free
energies, entropy contributions and internal energy and discuss their relation
to potential models used to analyze the melting of heavy quark bound states
above the deconfinement temperature. Results of different groups and various
potential models for bound states in the deconfined phase of QCD are compared.Comment: 6 pages, 8 figures, Lattice 2005 (Finite temperature and density
Effect of Turmeric and Carrot Seed Extracts on Serum Liver Biomarkers and Hepatic Lipid Peroxidation, Antioxidant Enzymes and Total Antioxidant Status in Rats
Introduction: Pathogenic role of free radicals are well known in various metabolic diseases. They originate from internal and external sources of body. Essential roles of antioxidant defense system for cellular redox regulation and free radical scavenging activity were described in this study. Many in vitro investigations have shown that turmeric (TE) and carrot seed extract (CSE) exhibits to possess antioxidant activities. In this study, we evaluated the antioxidant potentials of ethanolic TE and CSE based on in vivo experiment in the rats. Methods: Animals were assigned to six groups: the 1st and 2nd groups were control groups and 2nd group received 0.2 ml dimethyl sulphoxide as vehicle treated group; other four experimental groups received different doses of TE (100, 200 mg/kg b.w.) and CSE (200, 400 mg/kg b.w.) by gavages, respectively for a period of one month. The indicators of oxidative stress, lipids peroxidation, markers of hepatocyte injury and biliary function markers were measured. Results: The levels of superoxide dismutase, catalase, and glutathione peroxidase were significantly stimulated in the hepatic tissue of treatment groups. The malondialdehyde contents of liver tissue were significantly reduced in the groups fed with TE and CSE. Serum levels of alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase, in treated groups were found to be significantly decreased, whereas albumin and total protein increased as compared to the control groups (P<0.05). Conclusion: this study showed that the regular intake of TE and CSE through the diet can improve antioxidant status and inhibit peroxidation activity in the liver tissue so that using these extracts may protect tissue oxidative stress
Gauge Transformations, BRST Cohomology and Wigner's Little Group
We discuss the (dual-)gauge transformations and BRST cohomology for the two
(1 + 1)-dimensional (2D) free Abelian one-form and four (3 + 1)-dimensional
(4D) free Abelian 2-form gauge theories by exploiting the (co-)BRST symmetries
(and their corresponding generators) for the Lagrangian densities of these
theories. For the 4D free 2-form gauge theory, we show that the changes on the
antisymmetric polarization tensor e^{\mu\nu} (k) due to (i) the (dual-)gauge
transformations corresponding to the internal symmetry group, and (ii) the
translation subgroup T(2) of the Wigner's little group, are connected with
each-other for the specific relationships among the parameters of these
transformation groups. In the language of BRST cohomology defined w.r.t. the
conserved and nilpotent (co-)BRST charges, the (dual-)gauge transformed states
turn out to be the sum of the original state and the (co-)BRST exact states. We
comment on (i) the quasi-topological nature of the 4D free 2-form gauge theory
from the degrees of freedom count on e^{\mu\nu} (k), and (ii) the Wigner's
little group and the BRST cohomology for the 2D one-form gauge theory {\it
vis-{\`a}-vis} our analysis for the 4D 2-form gauge theory.Comment: LaTeX file, 29 pages, misprints in (3.7), (3.8), (3.9), (3.13) and
(4.14)corrected and communicated to IJMPA as ``Erratum'
Are internal focuses really useful? A replication study in Basketball
To evaluate the external vs. internal focus during free basketball shots in non-basketball players. For this analysis 49 subjects participated in one baseline and one experimental session. During the baseline session all the participants performed 20 free basketball shots without instructions (Non-Instructions). During the experimental session participants were randomly allocated to one group: Dominant-Group, which performed the free basketball shots with the dominant hand; or a Non-dominant Group, which performed the shots with the non-dominant hand. Both groups performed 20 throws under internal and external focus of attention conditions. In the Dominant-Group internal focus of attention resulted in a higher number of successful shots compared with the external focus condition. Our study does not support previous findings and shows that external focus of attention impairs the performance of free basketball shots with the dominant hand in comparison with internal focus and ¨no instructions¨ conditions, in non-basketball players
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