3,059 research outputs found
Deforming tachyon kinks and tachyon potentials
In this paper we investigate deformation of tachyon potentials and tachyon
kink solutions. We consider the deformation of a DBI type action with gauge and
tachyon fields living on D1-brane and D3-brane world-volume. We deform tachyon
potentials to get other consistent tachyon potentials by using properly a
deformation function depending on the gauge field components. Resolutions of
singular tachyon kinks via deformation and applications of deformed tachyon
potentials to scalar cosmology scenario are discussed.Comment: To appear in JHEP, 19 pages, 5 eps figures, minor changes and one
reference adde
Tumor-Associated Macrophages Suppress the Cytotoxic Activity of Antimitotic Agents.
Antimitotic agents, including Taxol, disrupt microtubule dynamics and cause a protracted mitotic arrest and subsequent cell death. Despite the broad utility of these drugs in breast cancer and other tumor types, clinical response remains variable. Tumor-associated macrophages (TAMs) suppress the duration of Taxol-induced mitotic arrest in breast cancer cells and promote earlier mitotic slippage. This correlates with a decrease in the phosphorylated form of histone H2AX (γH2AX), decreased p53 activation, and reduced cancer cell death in interphase. TAMs promote cancer cell viability following mitotic slippage in a manner sensitive to MAPK/ERK kinase (MEK) inhibition. Acute depletion of major histocompatibility complex class II low (MHCIIlo) TAMs increased Taxol-induced DNA damage and apoptosis in cancer cells, leading to greater efficacy in intervention trials. MEK inhibition blocked the protective capacity of TAMs and phenocopied the effects of TAM depletion on Taxol treatment. TAMs suppress the cytotoxic effects of Taxol, in part through cell non-autonomous modulation of mitotic arrest in cancer cells, and targeting TAM-cancer cell interactions potentiates Taxol efficacy
Tachyon Tunnelling in D-brane-anti-D-brane
Using the tachyon DBI action proposal for the effective theory of
non-coincident D-brane-anti-D-brane system, we study the decay of this
system in the tachyon channel. We assume that the branes separation is held
fixed, i.e. no throat formation, and then find the bounce solution which
describe the decay of the system from false to the true vacuum of the tachyon
potential. We shall show that due to the non-standard form of the kinetic term
in the effective action, the thin wall approximation for calculating the bubble
nucleation rate gives a result which is independent of the branes separation.
This unusual result might indicate that the true decay of this metastable
system should be via a solution that represents a throat formation as well as
the tachyon tunneling.Comment: 15 pages, 4 figures, Latex file, minor changes, reference adde
Evolution of Tachyon Kink with Electric Field
We investigate the decay of an inhomogeneous D1-brane wrapped on a with
an electric field. The model that we consider consists of an array of tachyon
kink and anti-kink with a constant electric flux. Beginning with an initially
static configuration, we numerically evolve the tachyon field with some
perturbations under a fixed boundary condition at diametrically opposite points
on the circle . When the electric flux is smaller than the critical value,
the tachyon kink becomes unstable; the tachyon field rolls down the potential,
and the lower dimensional D0- and -brane become thin, which
resembles the caustic formation known for this type of the system in the
literature. For the supercritical values of the electric flux, the tachyon kink
remains stable.Comment: 27 pages, 8 figures, some changes, one reference added, version to
appear in JHE
Tachyon Kink on non-BPS Dp-brane in the General Background
This paper is devoted to the study of the tachyon kink on the worldvolume of
a non-BPS Dp-brane that is embedded in general background, including NS-NS two
form B and also general Ramond-Ramond field. We will explicitly show that the
dynamics of the kink is described by the equations of motion that arrise from
the DBI and WZ action for D(p-1)-brane.Comment: 28 page
Non-Extremal D-instantons and the AdS/CFT Correspondence
We investigate non-extremal D-instantons in an asymptotically background and the role they play in the correspondence.
We find that the holographic dual operators of non-extremal D-instanton
configurations do not correspond to self-dual Yang-Mills instantons, and we
compute explicitly the deviation from self-duality. Furthermore, a class of
non-extremal D-instantons yield Euclidean axionic wormhole solutions with two
asymptotic boundaries. After Wick rotating, this provides a playground for
investigating holography in the presence of cosmological singularities in a
closed universe.Comment: 30 pages, 3 figure
Towards 5D Grand Unification without SUSY Flavor Problem
We consider the renormalization group approach to the SUSY flavor problem in
the supersymmetric SU(5) model with one extra dimension. In higher dimensional
SUSY gauge theories, it has been recently shown that power corrections due to
the Kaluza-Klein states of gauge fields run the soft masses generated at the
orbifold fixed point to flavor conserving values in the infra-red limit. In
models with GUT breaking at the brane where the GUT scale can be larger than
the compactification scale, we show that the addition of a bulk Higgs
multiplet, which is necessary for the successful unification, is compatible
with the flavor universality achieved at the compactification scale.Comment: JHEP style file of 35 pages with 3 figures, Version to appear in JHE
Tricritical gravity waves in the four-dimensional generalized massive gravity
We construct a generalized massive gravity by combining quadratic curvature
gravity with the Chern-Simons term in four dimensions. This may be a candidate
for the parity-odd tricritical gravity theory. Considering the AdS vacuum
solution, we derive the linearized Einstein equation, which is not similar to
that of the three dimensional (3D) generalized massive gravity. When a
perturbed metric tensor is chosen to be the Kerr-Schild form, the linearized
equation reduces to a single massive scalar equation. At the tricritical points
where two masses are equal to -1 and 2, we obtain a log-square wave solution to
the massive scalar equation. This is compared to the 3D tricritical generalized
massive gravity whose dual is a rank-3 logarithmic conformal field theory.Comment: 17 pages, 1 figure, version to appear in EPJ
Predictors for occupational injuries and diseases among commercial fishers in Finland 1996–2015
Fishing is a hazardous occupation worldwide. Commercial fishers in Finland are an aging and diminishing population with a high injury rate. Insurance claims data for self-employed Finnish commercial fishers during the years 1996 through 2015 (n = 1951) were analysed to assess predictors for occupational injuries and diseases. Out of the available variables, fishery location, career length, and participation in the voluntary occupational health service programme were not significant predictors. Male gender (OR 2.02; 95% CI 1.37–2.99), Finnish mother tongue vs. Swedish (OR 1.98, 95% CI 1.53–2.55), and higher income levels from fishing (four income categories, OR range: 1.71–3.53) were associated with higher odds for a compensated occupational injury or disease claim among commercial fishers in the final multivariate model. The identified risk groups could be targeted for interventions, and the content of the occupational health service programme should be developed to gain protective effect
SELF-DUAL ANYONS IN UNIFORM BACKGROUND FIELDS
We study relativistic self-dual Chern-Simons-Higgs systems in the presence of
uniform background fields that explicitly break CTP. A rich, but discrete
vacuum structure is found when the gauge symmetry is spontaneously broken,
while the symmetric phase can have an infinite vacuum degeneracy at tree level.
The latter is due to the proliferation of neutral solitonic states that cost
zero energy. Various novel self-dual solitons, such as these, are found in both
the symmetric and the asymmetric phases. Also by considering a similar system
on a two-sphere and the subsequent large sphere limit, we isolate sensible and
finite expressions for the conserved angular and linear momenta, which satisfy
anomalous commutation relations. We conclude with a few remarks on unresolved
issues.Comment: LaTeX, 20 pages, 4 uuencoded figures included
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