2,104 research outputs found
Unified approach to study quantum properties of primordial black holes, wormholes and of quantum cosmology
We review the anomaly induced effective action for dilaton coupled spinors
and scalars in large N and s-wave approximation. It may be applied to study the
following fundamental problems: construction of quantum corrected black holes
(BHs), inducing of primordial wormholes in the early Universe (this effect is
confirmed) and the solution of initial singularity problem. The recently
discovered anti-evaporation of multiple horizon BHs is discussed. The existance
of such primordial BHs may be interpreted as SUSY manifestation. Quantum
corrections to BHs thermodynamics maybe also discussed within such scheme.Comment: LaTeX file and two eps files, to appear in MPLA, Brief Review
An Investigation into Land Use Changes and Consequences in the Northern Great Plains Using Systems Thinking and Dynamics
From 1997 to 2007, 9.6 million hectares of grassland were converted to cropland and fifty seven percent of these conversions occurred in the Northern Great Plains (NGP). Since 2007, another 9.5 million U.S. hectares have been converted with the majority located in the NGP. Shortterm, positive benefits include increased food production and higher financial returns to farmers. However, there could be unintended consequences through loss of ecosystem services. Consequences may include compromised water quality, wildlife habitat loss/fragmentation, and decreased carbon sequestration. The principal objective of this work is to: 1) identify structural features influencing land use decisions through agricultural stakeholder engagement; and 2) to synthesize results into a causal loop diagram through a group model building process. This information can be used to construct a stock-flow model to quantify implications for land management, forecast potential unintended consequences from major land use changes, and develop strategies to minimize their impacts
Chiral Rings and Anomalies in Supersymmetric Gauge Theory
Motivated by recent work of Dijkgraaf and Vafa, we study anomalies and the
chiral ring structure in a supersymmetric U(N) gauge theory with an adjoint
chiral superfield and an arbitrary superpotential. A certain generalization of
the Konishi anomaly leads to an equation which is identical to the loop
equation of a bosonic matrix model. This allows us to solve for the expectation
values of the chiral operators as functions of a finite number of ``integration
constants.'' From this, we can derive the Dijkgraaf-Vafa relation of the
effective superpotential to a matrix model. Some of our results are applicable
to more general theories. For example, we determine the classical relations and
quantum deformations of the chiral ring of super Yang-Mills theory with
SU(N) gauge group, showing, as one consequence, that all supersymmetric vacua
of this theory have a nonzero chiral condensate.Comment: 67 pages, minor change
Gravity a la Born-Infeld
A simple technique for the construction of gravity theories in Born-Infeld
style is presented, and the properties of some of these novel theories are
investigated. They regularize the positive energy Schwarzschild singularity,
and a large class of models allows for the cancellation of ghosts. The possible
correspondence to low energy string theory is discussed. By including curvature
corrections to all orders in alpha', the new theories nicely illustrate a
mechanism that string theory might use to regularize gravitational
singularities.Comment: 21 pages, 2 figures, new appendix B with corrigendum: Class. Quantum
Grav. 21 (2004) 529
Variable velocity system for evaluating effects of air velocity on Japanese quail
This study documents the design and performance of a system to apply different
magnitudes of air velocity to Japanese quail, to evaluate the combined effects of velocity,
temperature and humidity on bird behaviour, performance and welfare. The system was
developed to simulate observed field conditions ocurring in regions with high winds where quail
are raised in curtain-sided housing. System performance consisted of characterizing air velocity
distribution in cages downstream of the air velocity which was directed at the front of the cages.
The system consisted of two fans attached to a 25 cm PVC tube, one at each end, with the outlet
airflow directed through a continuous slot over the cage front at the feeder. The design and
performance of this experimental system was evaluated, with six such systems were built and
utilized in research trials. To assess system performance, air velocity was measured at 275 points
per cage uniformly arranged along the three dimensions (length, width and height) in eight cages
with zero, 1, 2 or 3 m s-1 nominal velocity setpoints. Spatial distribution of velocity was analysed
by mapping and from descriptive statistics, with attention to the zone closest to the feeder where
birds must go to eat. There was no significant difference (P > 0.05) found in mean paired
difference of air speed data measured for pairs of front portion cages with similar velocities. A
significant positive correlation was found (P < 0.001) between the measured air velocity at paired
points in the cages subjected to the same velocity treatment. A comparison of measured mean air
velocity to the nominal setpoint values used for experiments indicated that careful attention to
outlet adjustment is important, especially at higher nominal velocity setpoint as 3 (± 0.10) m s-1
which was difficult to achieve with the system. An example of the use of the deployment of the
variable velocity system in controlled environment chambers with Japanese quail is provided
Renovation of Seeded Warm-season Pastures with Atrazine
Numerous warm-season pastures have been established in the last 30 years in the central Great Plains. Some of these pastures are old enough to verify that they can be abused by overgrazing as easily as native tallgrass prairies. Overgrazed warm-season pastures are invaded and dominated by cool-season grasses such as smooth brome (Bromus inermis Leyss.) and Kentucky bluegrass (Poa pratensis L.), which diminishes the pasture productivity during the hot summer months. Since established warm-season grasses have greater tolerance to the herbicide atrazine than cool-season grasses, the effectiveness of atrazine applications in renovating invaded warm-season pastures was evaluated. A single, early spring application of atrazine (3.3 kg/ha) killed or sufficiently suppressed the cool-season grasses so that surviving warm-season remnants were able to effectively re-establish the warm-season pasture in a single growing season without any loss in total pasture forage production. Lower rates of atrazine were not as effective, particularly if smooth brome was the primary cool-season grass. The single atrazine application cost was approximately 25% of the seed cost associated with more conventional renovation. Pastures should not be grazed the treatment year but can be hayed rt the end of the growing season. The success of the practice is dependent on the presence of warm-season grass remnants. Spraying test strips in small fenced areas would be advisable before treating entire pastures
Superfield Formulation for Non-Relativistic Chern-Simons-Matter Theory
We construct a superfield formulation for non-relativistic
Chern-Simons-Matter theories with manifest dynamical supersymmetry. By
eliminating all the auxiliary fields, we show that the simple action reduces to
the one obtained by taking non-relativistic limit from the relativistic
Chern-Simons-Matter theory proposed in the literature. As a further
application, we give a manifestly supersymmetric derivation of the
non-relativistic ABJM theory.Comment: 18 page
d=2, N=2 Superconformal Symmetries and Models
We discuss the following aspects of two-dimensional N=2 supersymmetric
theories defined on compact super Riemann surfaces: parametrization of (2,0)
and (2,2) superconformal structures in terms of Beltrami coefficients and
formulation of superconformal models on such surfaces (invariant actions,
anomalies and compensating actions, Ward identities).Comment: 43 pages, late
A Note on Flux Induced Superpotentials in String Theory
Non-vanishing fluxes in M-theory and string theory compactifications induce a
superpotential in the lower dimensional theory. Gukov has conjectured the
explicit form of this superpotential. We check this conjecture for the
heterotic string compactified on a Calabi-Yau three-fold as well as for warped
M-theory compactifications on Spin(7) holonomy manifolds, by performing a
Kaluza-Klein reduction.Comment: 19 pages, no figure
Non(anti)commutative SYM theory: Renormalization in superspace
We present a systematic investigation of one-loop renormalizability for
nonanticommutative N=1/2, U(N) SYM theory in superspace. We first discuss
classical gauge invariance of the pure gauge theory and show that in
contradistinction to the ordinary anticommutative case, different
representations of supercovariant derivatives and field strengths do not lead
to equivalent descriptions of the theory. Subsequently we develop background
field methods which allow us to compute a manifestly covariant gauge effective
action. One-loop evaluation of divergent contributions reveals that the theory
simply obtained from the ordinary one by trading products for star products is
not renormalizable. In the case of SYM with no matter we present a N=1/2
improved action which we show to be one-loop renormalizable and which is
perfectly compatible with the algebraic structure of the star product. For this
action we compute the beta functions. A brief discussion on the inclusion of
chiral matter is also presented.Comment: Latex file, 59 pages, 10 figures, One reference adde
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