2,141 research outputs found
Higher Order Supersymmetric Truncated Oscillators
We study the supersymmetric partners of the harmonic oscillator with an
infinite potential barrier at the origin and obtain the conditions under which
it is possible to add levels to the energy spectrum of these systems. It is
found that instead of the usual rule for non-singular potentials, where the
order of the transformation corresponds to the maximum number of levels which
can be added, now it is the integer part of half the order of the
transformation which gives the maximum number of levels to be created.Comment: This article is a natural continuation of arXiv:1603.05173 and
arXiv:1310.562
Relativistic stars in f(R) and scalar-tensor theories
We study relativistic stars in the context of scalar tensor theories of
gravity that try to account for the observed cosmic acceleration and satisfy
the local gravity constraints via the chameleon mechanism. More specifically,
we consider two types of models: scalar tensor theories with an inverse power
law potential and f(R) theories. Using a relaxation algorithm, we construct
numerically static relativistic stars, both for constant energy density
configurations and for a polytropic equation of state. We can reach a
gravitational potential up to at the surface of the star, even
in f(R) theories with an "unprotected" curvature singularity. However, we find
static configurations only if the pressure does not exceed one third of the
energy density, except possibly in a limited region of the star (otherwise, one
expects tachyonic instabilities to develop). This constraint is satisfied by
realistic equations of state for neutron stars.Comment: 20 pages, 10 Figs, revtex4; v2. minor corrections and changes; v3: a
few changes, matches published versio
Ks1, an epithelial cell-specific gene, responds to early signals of head formation in Hydra
As a molecular marker for head specification in
Hydra, we
have cloned an epithelial cell-specific gene which responds
to early signals of head formation. The gene, designated
ks1, encodes a 217-amino acid protein lacking significant
sequence similarity to any known protein. KS1 contains a
N-terminal signal sequence and is rich in charged residues
which are clustered in several domains. ks1 is expressed in
tentacle-specific epithelial cells (battery cells) as well as in
a small fraction of ectodermal epithelial cells in the gastric
region subjacent to the tentacles. Treatment with the
protein kinase C activator 12-O-tetradecanoylphorbol-13-
acetate (TPA) causes a rapid increase in the level of ks1
mRNA in head-specific epithelial cells and also induces
ectopic ks1 expression in cells of the gastric region.
Sequence elements in the 5
¢-flanking region of ks1 that are
related to TPA-responsive elements may mediate the TPA
inducibility of ks1 expression. The pattern of expression of
ks1 suggests that a ligand-activated diacylglycerol second
messenger system is involved in head-specific differentiation
A Literature Review on Electricity Transmission Expansion Planning: The Mexican Case
Numéro de référence interne originel : a1.1 g 113
Determining the BDMPS transport coefficient via medium-modified fragmentation functions
In nucleus-nucleus collisions at RHIC and LHC, partons produced at high
transverse momentum can undergo multiple scattering within the collision region
prior to fragmenting into hadrons. We have studied the resulting
medium-modified fragmentation function based on a calculation of the BDMPS-Z
medium-induced gluon radiation for a dense, expanding medium of small finite
extension. Here we explain how the BDMPS transport coefficient which measures
the energy density attained in the collision, can be extracted from the
observed modification of high-pt hadroproduction. We also comment on the
significant remaining uncertainties in extracting the transport coefficient
from data.Comment: 4 pages, 4 postscript figures. Proceedings for Quark Matter 200
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