817 research outputs found
Local Casimir Energy For Solitons
Direct calculation of the one-loop contributions to the energy density of
bosonic and supersymmetric phi-to-the-fourth kinks exhibits: (1) Local mode
regularization. Requiring the mode density in the kink and the trivial sectors
to be equal at each point in space yields the anomalous part of the energy
density. (2) Phase space factorization. A striking position-momentum
factorization for reflectionless potentials gives the non-anomalous energy
density a simple relation to that for the bound state. For the supersymmetric
kink, our expression for the energy density (both the anomalous and
non-anomalous parts) agrees with the published central charge density, whose
anomalous part we also compute directly by point-splitting regularization.
Finally we show that, for a scalar field with arbitrary scalar background
potential in one space dimension, point-splitting regularization implies local
mode regularization of the Casimir energy density.Comment: 18 pages. Numerous new clarifications and additions, of which the
most important may be the direct derivation of local mode regularization from
point-splitting regularization for the bosonic kink in 1+1 dimension
Chern-simon type photon mass from fermion electric dipole moments at finite temperature in 3+1 dimensions
We study the low energy effective field theory of fermions with electric and
magnetic dipole moments at finite temperature. We find that at one loop there
is an interaction term of the Chern-Simon form . The four vector is interpreted as a Chern- Simon type mass of photons,
which is determined by the electric (magnetic) dipole moments ()
of the fermions in the vacuum polarisation loop diagram. The physical
consequence of such a photon mass is that, photons of opposite circular
polarisations, propagating through a hot medium, have different group
velocities. We estimate that the time lag between the arrival times of the left
and right circularly polarised light signals from pulsars. If the light
propagates through a hot plasma (where the temperature in some regions is ) then the time lag between the two circularly polarised signals
of frequency will be . It may
be possible to observe this effect in pulsar signals which propagate through
nebula at high temperatures.Comment: plain TeX, 9 page
Central charge and renormalization in supersymmetric theories with vortices
Some quantum features of vortices in supersymmetric theories in 1+2
dimensions are studied in a manifestly supersymmetric setting of the superfield
formalism. A close examination of the supercurrent that accommodates the
central charge and super-Poincare charges in a supermultiplet reveals that
there is no genuine quantum anomaly in the supertrace identity and in the
supercharge algebra, with the central-charge operator given by the bare
Fayet-Iliopoulos term alone. The central charge and the vortex spectrum undergo
renormalization on taking the expectation value of the central-charge operator.
It is shown that the vortex spectrum is exactly determined at one loop while
the spectrum of the elementary excitations receives higher-order corrections.Comment: 9 pages, revte
Ten-year consistency in neurological test performance of children without focal neurological deficit
To assess \u27soft-sign\u27 persistence and its correlates outside a referred sample, 159 members of a local birth cohort of the United National Collaborative Perinatal Project were traced and their performance on six neurological test scales was measured at age 17 by examiners blind to their status at age seven. A comparison group was also formed, who had been \u27sign-free\u27 at age seven. On four of the six tests (dysdiadochokinesis, mirror movements, dysgraphesthesia and motor slowness) index boys did significantly worse than the comparison boys; by contrast, index girls scored significantly worse than comparisons only on motor slowness
Open Access Publishing in Business Research: The Authors’ Perspective
Open access (OA) publishing is now accepted as an integral part of the emerging trends within scholarly communication. Business librarians, like their subject specialist colleagues in other disciplines, are increasingly called upon to interpret scholarly communication trends to their faculty. This study surveys 1,293 business faculty from American schools of business accredited by the Association to Advance Collegiate Schools of Business. Issues explored include business faculty publishing practices within the discipline and how these affect academic advancement, obtaining articles for their own research, electronic publishing, self-archiving, and their perceptions about OA publishing generally.With support from the Emerald Publishing Research Award 2009
Self-DUal SU(3) Chern-Simons Higgs Systems
We explore self-dual Chern-Simons Higgs systems with the local and
global symmetries where the matter field lies in the adjoint
representation. We show that there are three degenerate vacua of different
symmetries and study the unbroken symmetry and particle spectrum in each
vacuum. We classify the self-dual configurations into three types and study
their properties.Comment: Columbia Preprint CU-TP-635, 19 page
Estrogen Up-regulates Apolipoprotein E (ApoE) Gene Expression by Increasing ApoE mRNA in the Translating Pool via the Estrogen Receptor α-Mediated Pathway
The antiatherogenic property of estrogens is mediated via at least two mechanisms: first by affecting plasma lipoprotein profiles, and second by affecting the components of the vessel wall. Raising plasma apolipoprotein E (apoE) in mice protects them against diet-induced atherosclerosis (Shimano, H., Yamada, N., Katsuki, M., Gotoda, T., Harada, K., Murase, T., Fukuzawa, C., Takaku, F., and Yazaka, Y. (1992) Proc. Natl. Acad. Sci. U. S. A. 89, 1750-1754). It is possible that estrogen may be antiatherogenic at least in part by increasing plasma apoE levels. Therefore, we studied the regulation of apoE by estrogen. A survey of 15 inbred strains of mice showed that some mouse strains responded to injections or subcutaneously implanted pellets of estradiol by raising their apoB and apoE levels and some did not. We performed detailed studies in two "responder" strains, C57L and C57BL, and two "non-responder" strains, C3H and BALBc. Responders increased their plasma apoE levels 2.5-fold. Non-responders' levels were altered +/-10%. In the responders the distribution of apoE among the plasma lipoproteins shifted from high density lipoprotein toward the apoB-containing lipoprotein fractions. In nonresponders the shift was toward high density lipoprotein. Hepatic apoE mRNA levels and relative rates of apoE mRNA transcription were unchanged in all strains, suggesting that apoE regulation occurred at posttranscriptional loci. Therefore, we measured apoE synthesis in fresh liver slices and on isolated hepatic polysomes. Two-fold increases were noted but only in responders accompanied by selective 1.5-fold increases in polysomal apoE mRNA levels. Similar increases in apoE synthesis were also observed in castrated C57BL mice given either physiological or pharmacological replacement doses of estradiol, but not testosterone, suggesting that the effect of estradiol was specific on the distribution of apoE mRNA in the translationally active polysomal pool. Next, we examined whether the effects of estrogen on apoE translation were mediated by estrogen receptors (ER). ER-alpha knock-out mice and their wild-type littermates were administered estradiol. As expected, apoE levels and hepatic apoE synthesis increased more than 2-fold in the wild-type littermates, but only 20% increases in the plasma apoE and hepatic synthesis were observed in the ER knock-out mice. Hepatic apoE mRNA levels did not change in either the wild-type or the ER knock-out mice. Thus, estradiol up-regulates apoE gene expression by increasing levels of apoE mRNA in the polysomal translating pool. Furthermore, the increased polysomal recruitment of apoE mRNA is largely mediated by estrogen receptors
Failure of Gauge Invariance in the Nonperturbative Formulation of Massless Lorentz-Violating QED
We consider a Lorentz-violating modification to the fermionic Lagrangian of
QED that is known to produce a finite Chern-Simons term at leading order. We
compute the second order correction to the one-loop photon self-energy in the
massless case using an exact propagator and a nonperturbative formulation of
the theory. This nonperturbative theory assigns a definite value to the
coefficient of the induced Chern-Simons term; however, we find that the theory
fails to preserve gauge invariance at higher orders. We conclude that the
specific nonperturbative value of the Chern-Simons coefficient has no special
significance.Comment: 8 pages, very minor change
Dynamical mass generation of a two-component fermion in Maxwell-Chern-Simons QED_3: The lowest ladder approximation
Dynamical mass generation of a two-component fermion in with a
Chern-Simons term is investigated by solving the Schwinger-Dyson equation
formulated in the lowest ladder approximation. Dependence of the dynamical
fermion mass on a gauge-fixing parameter, a gauge coupling constant, and a
topological mass is examined by approximated analytical and also numerical
methods. The inclusion of the Chern-Simons term makes impossible to choose a
peculiar gauge in which a wave function renormalization is absent. The
numerical evaluation shows that the wave function renormalization is fairly
close to 1 in the Landau gauge. It means that this gauge is still a specific
gauge where the Ward-Takahashi identity is satisfied approximately. We also
find that the dynamical mass is almost constant if the topological mass is
larger than the coupling constant, while it decreases when the topological mass
is comparable to or smaller than the coupling constant and tends to the value
in without the Chern-Simons term.Comment: 22 pages, 9 figures, Version to appear in Phys. Rev.
- …