1,963 research outputs found
The Anomaly Structure of Regularized Supergravity
On-shell Pauli-Villars regularization of the one-loop divergences of
supergravity theories is used to study the anomaly structure of supergravity
and the cancellation of field theory anomalies under a gauge
transformation and under the T-duality group of modular transformations in
effective supergravity theories with three K\"ahler moduli obtained from
orbifold compactification of the weakly coupled heterotic string. This
procedure requires constraints on the chiral matter representations of the
gauge group that are consistent with known results from orbifold
compactifications. Pauli-Villars regulator fields allow for the cancellation of
all quadratic and logarithmic divergences, as well as most linear divergences.
If all linear divergences were canceled, the theory would be anomaly free, with
noninvariance of the action arising only from Pauli-Villars masses. However
there are linear divergences associated with nonrenormalizable
gravitino/gaugino interactions that cannot be canceled by PV fields. The
resulting chiral anomaly forms a supermultiplet with the corresponding
conformal anomaly, provided the ultraviolet cut-off has the appropriate field
dependence, in which case total derivative terms, such as Gauss-Bonnet, do not
drop out from the effective action. The anomalies can be partially canceled by
the four-dimensional version of the Green-Schwarz mechanism, but additional
counterterms, and/or a more elaborate set of Pauli-Villars fields and
couplings, are needed to cancel the full anomaly, including D-term
contributions to the conformal anomaly that are nonlinear in the parameters of
the anomalous transformations.Comment: 103 page
Nature Conservation and Veterinary Problems:Issues and Options. With case studies of foot and mouth disease and classical swine fever.
Nature Conservation and Veterinary Problems:Issues and Options. With case studies of foot and mouth disease and classical swine fever.
Molecular dynamics simulations of the dipolar-induced formation of magnetic nanochains and nanorings
Iron, cobalt and nickel nanoparticles, grown in the gas phase, are known to
arrange in chains and bracelet-like rings due to the long-range dipolar
interaction between the ferromagnetic (or super-paramagnetic) particles. We
investigate the dynamics and thermodynamics of such magnetic dipolar
nanoparticles for low densities using molecular dynamics simulations and
analyze the influence of temperature and external magnetic fields on two- and
three-dimensional systems. The obtained phase diagrams can be understood by
using simple energetic arguments.Comment: 6 pages, 6 figure
Hole Injection at the Silicon/Aqueous Electrolyte Interface: A Possible Mechanism for Chemiluminescence from Porous Silicon
Dipole Interactions and Electrical Polarity in Nanosystems -- the Clausius-Mossotti and Related Models
Point polarizable molecules at fixed spatial positions have solvable
electrostatic properties in classical approximation, the most familiar being
the Clausius-Mossotti (CM) formula. This paper generalizes the model and
imagines various applications to nanosystems. The behavior is worked out for a
sequence of octahedral fragments of simple cubic crystals, and the crossover to
the bulk CM law is found. Some relations to fixed moment systems are discussed
and exploited. The one-dimensional dipole stack is introduced as an important
model system. The energy of interaction of parallel stacks is worked out, and
clarifies the diverse behavior found in different crystal structures. It also
suggests patterns of self-organization which polar molecules in solution might
adopt. A sum rule on the stack interaction is found and tested. Stability of
polarized states under thermal fluctuations is discussed, using the
one-dimensional domain wall as an example. Possible structures for polar hard
ellipsoids are considered. An idea is formulated for enhancing polarity of
nanosystems by intentionally adding metallic coatings.Comment: 18 pages (includes 6 embedded figures and 3 tables). New references,
and other small improvements. Scheduled for publication by J. Chem. Phys.,
Jan. 200
Nature Conservation and Veterinary Problems:Issues and Options. With case studies of foot and mouth disease and classical swine fever.
Anomaly Structure of Supergravity and Anomaly Cancellation
We display the full anomaly structure of supergravity, including new D-term
contributions to the conformal anomaly. This expression has the super-Weyl and
chiral U(1)_K transformation properties that are required for implementation of
the Green-Schwarz mechanism for anomaly cancellation. We outline the procedure
for full anomaly cancellation. Our results have implications for effective
supergravity theories from the weakly coupled heterotic string theory.Comment: 8 page
Propagating and Debunking Conspiracy Theories on Twitter During the 2015–2016 Zika Virus Outbreak
Analysis of the early immune response to infection by infectious bursal disease virus in chickens differing in their resistance to the disease
Chicken whole-genome gene expression arrays were used to analyze the host response to infection by infectious bursal disease virus (IBDV). Spleen and bursal tissue were examined from control and infected birds at 2, 3, and 4 days postinfection from two lines that differ in their resistance to IBDV infection. The host response was evaluated over this period, and differences between susceptible and resistant chicken lines were examined. Antiviral genes, including IFNA, IFNG, MX1, IFITM1, IFITM3, and IFITM5, were upregulated in response to infection. Evaluation of this gene expression data allowed us to predict several genes as candidates for involvement in resistance to IBDV. © 2015, American Society for Microbiology
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