135 research outputs found
Boosts, Schwarzschild Black Holes and Absorption cross-sections in M theory
dimensional neutral black strings wrapped on a circle are related to
dimensional charged black holes by boosts. We show that the boost has
to be performed in the covering space and the boosted coordinate has to be
compactified on a circle with a Lorentz contracted radius. Using this fact we
show that the transition between Schwarzschild black holes to black p-branes
observed recently in M theory is the well-known black hole- black string
transition viewed in a boosted frame. In a similar way the correspondence point
where an excited string state goes over to a neutral black hole is mapped
exactly to the correspondence point for black p-branes. In terms of the
brane quantities the equation of state for an excited string state becomes
identical to that of a 3+1 dimensional massless gas for all . Finally, we
show how boosts can be used to relate Hawking radiation rates. Using the known
microscopic derivation of absorption by extremal 3-branes and near-extremal 5D
holes with three large charges we provide a microscopic derivation of
absorption of 0-branes by seven and five dimensional Schwarzschild black holes
in a certain regime.Comment: Some references added, minor clarifications (harvmac, 16 pages
Hawking Radiation from Four-dimensional Schwarzschild Black Holes in M-theory
Recently a method has been developed for relating four dimensional Schwarzschild black holes in M-theory to near-extremal black holes in string theory with four charges, using suitably defined ``boosts'' and T-dualities. We show that this method can be extended to obtain the emission rate of low energy massless scalars for the four dimensional Schwarzschild hole from the microscopic picture of radiation from the near extremal hole
FUZZY BASED CASCADED MULTILEVEL SHUNT ACTIVE POWER FILTER FOR POWER LINE CONDITIONERS
In this paper shunt active power filter is used to improve the power quality at distribution system. Due to nonlinear loads, current harmonics, unbalanced voltages and current and reactive power problems will be created in the network. The Instantaneous real power theory (IRPT) provides the real power calculation with PI controller will not provide accurate result and good performance under both steady state and transient state. Compensating above problems by using fuzzy based on Cascaded multi-level voltage source inverter. The inverter switching signals are generated based on the triangular sampling current controller provides power line conditioning. The Paper deals with three phase, five level cascaded multi level voltage source inverter based shunt active filter with PI and Fuzzy controller by using MATLAB/Simulink
Super-A-polynomials for Twist Knots
We conjecture formulae of the colored superpolynomials for a class of twist
knots where p denotes the number of full twists. The validity of the
formulae is checked by applying differentials and taking special limits. Using
the formulae, we compute both the classical and quantum super-A-polynomial for
the twist knots with small values of p. The results support the categorified
versions of the generalized volume conjecture and the quantum volume
conjecture. Furthermore, we obtain the evidence that the Q-deformed
A-polynomials can be identified with the augmentation polynomials of knot
contact homology in the case of the twist knots.Comment: 22+16 pages, 16 tables and 5 figures; with a Maple program by Xinyu
Sun and a Mathematica notebook in the ancillary files linked on the right; v2
change in appendix B, typos corrected and references added; v3 change in
section 3.3; v4 corrections in Ooguri-Vafa polynomials and quantum
super-A-polynomials for 7_2 and 8_1 are adde
Genomic sequence derived simple sequence repeat markers: case study with Medicago spp
Simple sequence repeats (SSR) or micro-satellites are becoming standard DNA markers for plant genome analysis and are being used as markers in marker assisted breeding. De novo generation of micro-satellite markers through laboratory-based screening of SSR-enriched genomic libraries is highly time consuming and expensive. An alternative is to screen the public databases of related model species where abundant sequence data is already available. All the genomic sequences of Medicago from the public domain database were searched and analysed of di, tri, and tetra nucleotide repeats. Of the total of about 156,000 sequences which were searched, 7325 sequences were found to contain repeat motif and may yield SSR which will yield product sizes of around 200 bp. Of these the most abundantly found repeats were the tri-nucleotide (5210) group. Except for a very small proportion (436), these link to the gene annotation database at TIGR (http://www.tigr.org)
Genomic sequence derived simple sequence repeats markers. A case study with medicago spp.
Simple sequence repeats (SSR) or microsatellites are becoming standard DNA markers for plant genome analysis and are being used as markers in marker assisted breeding. De novo generation of microsatellite markers through laboratory-based screening of SSR-enriched genomic libraries is highly time consuming and expensive. An alternative is to screen the public databases of related model species where abundant sequence data is already available. All the genomic sequences of Medicago from the public domain database were searched and analysed for di, tri and tetra nucleotide repeats. Of the total 156 000 sequences which were searched, 7325 sequences contained repeat motif and may yield SSR which will yield product sizes of around 200 bp. Of these, the most abundantly found repeats were the trinucleotide (5210) group. Except for a very small proportion (436), these link to the gene annotation database at TIGR (http://www.tigr.org). To facilitate further exploration of this resource, a dynamic database with options to search and link to other resources is available at (http://www.icrisat.org/text/research/ grep/homepage/genomics/medssrs1.asp) and on CDs from [email protected]
A Note on Dimer Models and D-brane Gauge Theories
The connection between quiver gauge theories and dimer models has been well
studied. It is known that the matter fields of the quiver gauge theories can be
represented using the perfect matchings of the corresponding dimer model.We
conjecture that a subset of perfect matchings associated with an internal point
in the toric diagram is sufficient to give information about the charge matrix
of the quiver gauge theory. Further, we perform explicit computations on some
aspects of partial resolutions of toric singularities using dimer models. We
analyse these with graph theory techniques, using the perfect matchings of
orbifolds of the form \BC^3/\Gamma, where the orbifolding group may
be noncyclic. Using these, we study the construction of the superpotential of
gauge theories living on D-branes which probe these singularities, including
the case where one or more adjoint fields are present upon partial resolution.
Applying a combination of open and closed string techniques to dimer models, we
also study some aspects of their symmetries.Comment: Discussions expanded, clarifications added, typos fixed. 1+49 page
HOMFLY and superpolynomials for figure eight knot in all symmetric and antisymmetric representations
Explicit answer is given for the HOMFLY polynomial of the figure eight knot
in arbitrary symmetric representation R=[p]. It generalizes the old
answers for p=1 and 2 and the recently derived results for p=3,4, which are
fully consistent with the Ooguri-Vafa conjecture. The answer can be considered
as a quantization of the \sigma_R = \sigma_{[1]}^{|R|} identity for the
"special" polynomials (they define the leading asymptotics of HOMFLY at q=1),
and arises in a form, convenient for comparison with the representation of the
Jones polynomials as sums of dilogarithm ratios. In particular, we construct a
difference equation ("non-commutative A-polynomial") in the representation
variable p. Simple symmetry transformation provides also a formula for
arbitrary antisymmetric (fundamental) representation R=[1^p], which also passes
some obvious checks. Also straightforward is a deformation from HOMFLY to
superpolynomials. Further generalizations seem possible to arbitrary Young
diagrams R, but these expressions are harder to test because of the lack of
alternative results, even partial.Comment: 14 page
Quantum Knitting
We analyze the connections between the mathematical theory of knots and
quantum physics by addressing a number of algorithmic questions related to both
knots and braid groups.
Knots can be distinguished by means of `knot invariants', among which the
Jones polynomial plays a prominent role, since it can be associated with
observables in topological quantum field theory.
Although the problem of computing the Jones polynomial is intractable in the
framework of classical complexity theory, it has been recently recognized that
a quantum computer is capable of approximating it in an efficient way. The
quantum algorithms discussed here represent a breakthrough for quantum
computation, since approximating the Jones polynomial is actually a `universal
problem', namely the hardest problem that a quantum computer can efficiently
handle.Comment: 29 pages, 5 figures; to appear in Laser Journa
Chern-Simons Invariants of Torus Links
We compute the vacuum expectation values of torus knot operators in
Chern-Simons theory, and we obtain explicit formulae for all classical gauge
groups and for arbitrary representations. We reproduce a known formula for the
HOMFLY invariants of torus links and we obtain an analogous formula for
Kauffman invariants. We also derive a formula for cable knots. We use our
results to test a recently proposed conjecture that relates HOMFLY and Kauffman
invariants.Comment: 20 pages, 5 figures; v2: minor changes, version submitted to AHP. The
final publication is available at
http://www.springerlink.com/content/a2614232873l76h6
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