558 research outputs found
Using Environmental and Biological Indices as Proxies for Egg and Larval Production of Marine Fish
Tachyon Couplings to Fermion
By fixing the internal CP factor of tachyon and massless Ramond vertex
operators in different pictures, we have shown that the internal CP factor of
the disk level S-matrix elements of two fermions and odd number of tachyon
vertex operators in the world volume of non-BPS D-branes/D-brane-anti-D-brane
is zero. We have calculated the S-matrix element of two fermions and two
tachyons which has non vanishing internal CP factor, and found the momentum
expansion of this amplitude. In the abelian case, we have compared the
two-fermion-two-tachyon coupling at low energy with the corresponding coupling
in the gauge-fixed supersymmetric tachyon DBI action. The couplings in the two
cases are exactly the same.Comment: 16 pages, latex file; V2:a missing term in the modified tachyon DBI
action adde
Kinky D-branes and straight strings of open string tachyon effective theory
In this letter we construct the kink D1-brane super D-helix solution and its
T-dual the D2-brane supertube using the effective action of non-BPS tachyonic
D-branes . In the limit of zero angular momentum, both types of solutions
collapse to zero radius, giving rise respectively to a degenerate string
configuration corresponding to a particle travelling with the speed of light
and to a static straight string configuration. These solutions share all the
properties of fundamental strings and do not have the pathological behavior of
other solutions previously found in this context. A short discussion on the
``generalized gauge transformations'' suggested by Sen is used to justify the
validity of our approach.Comment: 10 pages, latex, typos corrected and references adde
Pressure and linear heat capacity in the superconducting state of thoriated UBe13
Even well below Tc, the heavy-fermion superconductor (U,Th)Be13 has a large
linear term in its specific heat. We show that under uniaxial pressure, the
linear heat capacity increases in magnitude by more than a factor of two. The
change is reversible and suggests that the linear term is an intrinsic property
of the material. In addition, we find no evidence of hysteresis or of latent
heat in the low-temperature and low-pressure portion of the phase diagram,
showing that all transitions in this region are second order.Comment: 5 pages, 4 figure
Relativistic D-brane Scattering is Extremely Inelastic
We study the effects of quantum production of open strings on the
relativistic scattering of D-branes. We find strong corrections to the brane
trajectory from copious production of highly-excited open strings, whose
typical oscillator level is proportional to the square of the rapidity. In the
corrected trajectory, the branes rapidly coincide and remain trapped in a
configuration with enhanced symmetry. This is a purely stringy effect which
makes relativistic brane collisions exceptionally inelastic. We trace this
effect to velocity-dependent corrections to the open-string mass, which render
open strings between relativistic D-branes surprisingly light. We observe that
pair-creation of open strings could play an important role in cosmological
scenarios in which branes approach each other at very high speeds.Comment: 30 pages; added references and a comment about velocity-dependent
masse
D-brane Solitons in Supersymmetric Sigma-Models
Massive D=4 N=2 supersymmetric sigma models typically admit domain wall
(Q-kink) solutions and string (Q-lump) solutions, both preserving 1/2
supersymmetry. We exhibit a new static 1/4 supersymmetric `kink-lump' solution
in which a string ends on a wall, and show that it has an effective realization
as a BIon of the D=4 super DBI-action. It is also shown to have a
time-dependent Q-kink-lump generalization which reduces to the Q-lump in a
limit corresponding to infinite BI magnetic field. All these 1/4 supersymmetric
sigma-model solitons are shown to be realized in M-theory as calibrated, or
`Q-calibrated', M5-branes in an M-monopole background.Comment: 16 pages, 3 figures, Late
A World-Volume Perspective on the Recombination of Intersecting Branes
We study brane recombination for supersymmetric configurations of
intersecting branes in terms of the world-volume field theory. This field
theory contains an impurity, corresponding to the degrees of freedom localized
at the intersection. The Higgs branch, on which the impurity fields condense,
consists of vacua for which the intersection is deformed into a smooth
calibrated manifold. We show this explicitly using a superspace formalism for
which the calibration equations arise naturally from F- and D-flatness.Comment: References adde
Interacting entropy-corrected new agegraphic tachyon, K-essence and dilaton scalar field models of dark energy in non-flat universe
We present the new agegraphic dark energy model by introducing the quantum
corrections to the entropy-area relation in the setup of loop quantum gravity.
Employing this new form of dark energy, we investigate the model of interacting
dark energy and derive its equation of state. We study the correspondence
between the tachyon, K-essence and dilaton scalar field models with the
interacting entropy-corrected new agegraphic dark energy model in the non-flat
FRW universe. Moreover, we reconstruct the corresponding scalar potentials
which describe the dynamics of the scalar field models.Comment: 11 pages, typos fixe
Interacting Ricci Dark Energy with Logarithmic Correction
Motivated by the holographic principle, it has been suggested that the dark
energy density may be inversely proportional to the area of the event
horizon of the universe. However, such a model would have a causality problem.
In this work, we consider the entropy-corrected version of the holographic dark
energy model in the non-flat FRW universe and we propose to replace the future
event horizon area with the inverse of the Ricci scalar curvature. We obtain
the equation of state (EoS) parameter , the deceleration
parameter and in the presence of interaction between Dark
Energy (DE) and Dark Matter (DM). Moreover, we reconstruct the potential and
the dynamics of the tachyon, K-essence, dilaton and quintessence scalar field
models according to the evolutionary behavior of the interacting
entropy-corrected holographic dark energy model.Comment: 24 pages, accepted for publication in 'Astrophysics and Space
Science, DOI:10.1007/s10509-012-1031-8
Genome-wide association analyses identify 13 new susceptibility loci for generalized vitiligo
We previously reported a genome-wide association study (GWAS) identifying 14 susceptibility loci for generalized vitiligo. We report here a second GWAS (450 individuals with vitiligo (cases) and 3,182 controls), an independent replication study (1,440 cases and 1,316 controls) and a meta-analysis (3,187 cases and 6,723 controls) identifying 13 additional vitiligo-associated loci. These include OCA2-HERC2 (combined P = 3.80 × 10 ), MC1R (P = 1.82 × 10 ), a region near TYR (P = 1.57 × 10 ), IFIH1 (P = 4.91 × 10 ), CD80 (P = 3.78 × 10 ), CLNK (P = 1.56 × 10 ), BACH2 (P = 2.53 × 10 ), SLA (P = 1.58 × 10 ), CASP7 (P = 3.56 × 10 ), CD44 (P = 1.78 × 10 ), IKZF4 (P = 2.75 × 10 ), SH2B3 (P = 3.54 × 10 ) and TOB2 (P = 6.81 × 10 ). Most vitiligo susceptibility loci encode immunoregulatory proteins or melanocyte components that likely mediate immune targeting and the relationships among vitiligo, melanoma, and eye, skin and hair coloration
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