5,832 research outputs found
Near Horizon Extremal Geometry Perturbations: Dynamical Field Perturbations vs. Parametric Variations
In arXiv:1310.3727 we formulated and derived the three universal laws
governing Near Horizon Extremal Geometries (NHEG). In this work we focus on the
Entropy Perturbation Law (EPL) which, similarly to the first law of black hole
thermodynamics, relates perturbations of the charges labeling perturbations
around a given NHEG to the corresponding entropy perturbation. We show that
field perturbations governed by the linearized equations of motion and symmetry
conditions which we carefully specify, satisfy the EPL. We also show that these
perturbations are limited to those coming from difference of two NHEG solutions
(i.e. variations on the NHEG solution parameter space). Our analysis and
discussions shed light on the "no-dynamics" statements of arXiv:0906.2380 and
arXiv:0906.2376.Comment: 38 page
Extremal Rotating Black Holes in the Near-Horizon Limit: Phase Space and Symmetry Algebra
We construct the NHEG phase space, the classical phase space of Near-Horizon
Extremal Geometries with fixed angular momenta and entropy, and with the
largest symmetry algebra. We focus on vacuum solutions to dimensional
Einstein gravity. Each element in the phase space is a geometry with
isometries which has vanishing and constant charges. We construct an on-shell vanishing symplectic
structure, which leads to an infinite set of symplectic symmetries. In four
spacetime dimensions, the phase space is unique and the symmetry algebra
consists of the familiar Virasoro algebra, while in dimensions the
symmetry algebra, the NHEG algebra, contains infinitely many Virasoro
subalgebras. The nontrivial central term of the algebra is proportional to the
black hole entropy. This phase space and in particular its symmetries might
serve as a basis for a semiclassical description of extremal rotating black
hole microstates.Comment: Published in PLB, 5 page
Wiggling Throat of Extremal Black Holes
We construct the classical phase space of geometries in the near-horizon
region of vacuum extremal black holes as announced in [arXiv:1503.07861].
Motivated by the uniqueness theorems for such solutions and for perturbations
around them, we build a family of metrics depending upon a single periodic
function defined on the torus spanned by the isometry directions. We
show that this set of metrics is equipped with a consistent symplectic
structure and hence defines a phase space. The phase space forms a
representation of an infinite dimensional algebra of so-called symplectic
symmetries. The symmetry algebra is an extension of the Virasoro algebra whose
central extension is the black hole entropy. We motivate the choice of
diffeomorphisms leading to the phase space and explicitly derive the symplectic
structure, the algebra of symplectic symmetries and the corresponding conserved
charges. We also discuss a formulation of these charges with a Liouville type
stress-tensor on the torus defined by the isometries and outline
possible future directions.Comment: 56 pages, 3 figure
in generalized supergravity
We showed in previous work that for homogeneous Yang-Baxter (YB) deformations
of AdSS, the open string metric and coupling, and as a result the
closed string density , remain undeformed. In this work,
in addition to extending these results to the deformation associated with the
modified CYBE, or -deformation, we identify the Page forms as the open
string counterpart for RR fields and demonstrate case by case that the non-zero
Page forms remain invariant under YB deformations. We give a physical meaning
to the Killing vector of generalized supergravity and show for all YB
deformations: 1) appears as a current for center of mass motion on the
worldvolume of a D-branes probing the background, 2) is equal to the
divergence of the noncommutativity parameter, 3) exhibits "holographic"
behavior, where the radial component of vanishes at the AdS boundary, and
4) in pure spinor formalism is related to a certain state in the BRST
cohomology.Comment: 11 pages, 2 column; v2 references updated; v3 to appear in EPJ
A capillary electrophoretic method for isolation and characterization of grape xylem proteins
European (Vitis vinifera) and American (Vitis labrusca) grape species succumb to a bacterial disease known as Pierce's Disease (PD). In contrast, muscadine grape genotypes (Vitis rotundifolia) are tolerant/resistant to PD. This is due to the unique biochemical composition of muscadine xylem. However, because of low protein concentration, conventional methods such as low-pressure chromatography and PAGE are unsuitable for grape xylem protein characterization. In addition, these procedures are tedious, time-consuming and require large amount of sample. This study reports a procedure for isolating and separating proteins from muscadine and bunch grape xylem tissue. The procedure consists of separation of xylem from cortex and phloem, removal of pigments and other gummy substances from xylem with ethanol: ethylacetate (2:1) and subsequent Capillary Electrophoretic (CE) analysis of xylem protein extracts to achieve desired resolution. Number of peaks, peak height and areas, retention time and baseline position were used to compare resolution and study the effect of sample and separation buffer. Xylem tissue proteins extracted with 0.05% sodium borate buffer (pH 8.3) and subjected to CE using 1.2% sodium borate (pH 8.3) as a separation buffer were found to yield most satisfactory resolution of grape xylem proteins. The data obtained by CE were consistent and reproducible, and hence, is well suited to obtain excellent resolution of xylem tissue protein for identifying differences in protein composition among the grape genotypes.
(African Journal of Biotechnology: 2003 2(3): 66-70
A Study on Causes of Condemnation of Carcass and Organs at Shah Alam Abattoir
A two-week study of the causes of condemnation at Shah Alam abattoir was conducted. In the bovine
species, liver and lungs w.ere the main organs condemned due to fluke infestation. and emphysema respectively.
Ninety-five percent of pig lungs were condemned because of back bleeding, while in sheep caseous lymphadenitis
was the major cause of organ condemnedtion affectingg mainly the lungs and lymph nodes. No total carcass
condemnation was observed in any species during the study perio
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