1,015 research outputs found
BF Theories and Group-Level Duality
It is known that the partition function and correlators of the
two-dimensional topological field theory on the Riemann
surface is given by Verlinde numbers, dim() and that
the large limit of dim() gives Vol(), the volume of
the moduli space of flat connections of gauge group on ,
up to a power of . Given this relationship, we complete the computation of
Vol() using only algebraic results from conformal field theory. The
group-level duality of is used to show that if is a classical
group, then is a BF
theory with gauge group . Therefore this limit computes Vol(), the volume of the moduli space of flat connections of gauge
group
Differential effect of acute compressive injury on young and aged tendons
5R00AG063896-04 REVISED - NIH/National Institute on Agin
Integrable N = 2 Landau-Ginzburg Theories from Quotients of Fusion Rings
The discovery of integrable supersymmetric Landau-Ginzburg theories
whose chiral rings are fusion rings suggests a close connection between fusion
rings, the related Landau-Ginzburg superpotentials, and quantum
integrability. We examine this connection by finding the natural
analogue of the construction that produced the superpotentials with
and fusion rings as chiral rings. The chiral rings of the new
superpotentials are not directly the fusion rings of any conformal field
theory, although they are natural quotients of the tensor subring of the
fusion ring.
The new superpotentials yield solvable (twisted ) topological field
theories. We obtain the integer-valued correlation functions as sums of
Verlinde dimensions by expressing the correlators as fusion residues.
The and related topological Landau-Ginzburg
theories are isomorphic, despite being defined via quite different
superpotentials.Comment: 34 pages, BRX-TH-34
Diurnal cycle RANS simulations applied to wind resource assessment
Microscale computational fluid dynamics (CFD) models can be used for wind resource assessment on complex terrains. These models generally assume neutral atmospheric stratification, an assumption that can lead to inaccurate modeling results and to large uncertainties at certain sites. We propose a methodology for wind resource evaluation based on unsteady Reynolds averaged Navier‐Stokes (URANS) simulations of diurnal cycles including the effect of thermal stratification. Time‐dependent boundary conditions are generated by a 1D precursor to drive 3D diurnal cycle simulations for a given geostrophic wind direction sector. Time instants of the cycle representative of four thermal stability regimes are sampled within diurnal cycle simulations and combined with masts time series to obtain the wind power density (WPD). The methodology has been validated on a complex site instrumented with seven met masts. The WPD spatial distribution is in good agreement with observations with the mean absolute error improving 17.1% with respect to the neutral stratification assumption.This work has been partially supported by the three EU H2020 projects, New European Wind Atlas ERA‐NET PLUS (NEWA, FP7‐ENERGY.2013.10.1.2, European Commission's grant agreement 618122), High Performance Computing for Energy (HPC4E, grant agreement 689772), and the Energy oriented Centre of Excellence (EoCoE, grant agreement 676629), and the SEDAR (“Simulación eólica de alta resolución”) project. Jordi Barcons is grateful to a PhD fellowship from the Industrial Doctorates Plan of the Government of Catalonia (Ref. eco/2497/2013). We also thank Iberdrola Renovables Energa S.A. and Impulsora Latinoamericana de Energa Renovables S.A. for providing the access to Puebla met masts data for validation and to Luis Prieto and Daniel Paredes for their help. We also thank the reviewers for their productive comments and observations.Peer ReviewedPostprint (published version
Poincare Polynomials and Level Rank Dualities in the Coset Construction
We review the coset construction of conformal field theories; the emphasis is
on the construction of the Hilbert spaces for these models, especially if fixed
points occur. This is applied to the superconformal cosets constructed by
Kazama and Suzuki. To calculate heterotic string spectra we reformulate the
Gepner con- struction in terms of simple currents and introduce the so-called
extended Poincar\'e polynomial. We finally comment on the various equivalences
arising between models of this class, which can be expressed as level rank
dualities. (Invited talk given at the III. International Conference on
Mathematical Physics, String Theory and Quantum Gravity, Alushta, Ukraine, June
1993. To appear in Theor. Math. Phys.)Comment: 14 pages in LaTeX, HD-THEP-93-4
Clouds in the atmospheres of extrasolar planets. II. Thermal emission spectra of Earth-like planets influenced by low and high-level clouds
We study the impact of multi-layered clouds (low-level water and high-level
ice clouds) on the thermal emission spectra of Earth-like planets orbiting
different types of stars. Clouds have an important influence on such planetary
emission spectra due to their wavelength dependent absorption and scattering
properties. We also investigate the influence of clouds on the ability to
derive information about planetary surface temperatures from low-resolution
spectra.Comment: accepted for publication in A&
Level-rank duality of D-branes on the SU(N) group manifold
The consequences of level-rank duality for untwisted D-branes on an SU(N)
group manifold are explored. Relations are found between the charges of
D-branes (which are classified by twisted K-theory) belonging to su(N)_K and
su(K)_N WZW theories, in the case of odd N+K. An isomorphism between the charge
algebras is also demonstrated in this case.Comment: 15 pages. v2 and v3: references added. v4: proof clarified and minor
typos fixe
Impact of Multiple Scattering on Longwave Radiative Transfer Involving Clouds
General circulation models (GCMs) are extensively used to estimate the influence of clouds on the global energy budget and other aspects of climate. Because radiative transfer computations involved in GCMs are costly, it is typical to consider only absorption but not scattering by clouds in longwave (LW) spectral bands. In this study, the flux and heating rate biases due to neglecting the scattering of LW radiation by clouds are quantified by using advanced cloud optical property models, and satellite data from Cloudâ Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO), CloudSat, Clouds and the Earth’s Radiant Energy System (CERES), and Moderate Resolution Imaging Spectrometer (MODIS) merged products (CCCM). From the products, information about the atmosphere and clouds (microphysical and buck optical properties, and top and base heights) is used to simulate fluxes and heating rates. Oneâ year global simulations for 2010 show that the LW scattering decreases topâ ofâ atmosphere (TOA) upward flux and increases surface downward flux by 2.6 and 1.2 W/m2, respectively, or approximately 10% and 5% of the TOA and surface LW cloud radiative effect, respectively. Regional TOA upward flux biases are as much as 5% of global averaged outgoing longwave radiation (OLR). LW scattering causes approximately 0.018 K/d cooling at the tropopause and about 0.028 K/d heating at the surface. Furthermore, over 40% of the total OLR bias for ice clouds is observed in 350â 500 cmâ 1. Overall, the radiative effects associated with neglecting LW scattering are comparable to the counterpart due to doubling atmospheric CO2 under clearâ sky conditions.Key PointsGlobal impacts of LW scattering are evaluated by using high spatial resolution satelliteâ derived cloud properties and top and base heightsOmitting cloud LW scattering increases annual mean TOA upward flux by 2.6 W/m2 and decreases annual mean surface downward flux by 1.2 W/m2Including LW scattering of clouds in simulations cools the tropopause approximately 0.018 K/d and heats the surface about 0.028 K/dPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141388/1/jame20524_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/141388/2/jame20524.pd
Superconformal Coset Equivalence from Level-Rank Duality
We construct a one-to-one map between the primary fields of the N=2
superconformal Kazama-Suzuki models G(m,n,k) and G(k,n,m) based on complex
Grassmannian cosets, using level-rank duality of Wess-Zumino-Witten models. We
then show that conformal weights, superconformal U(1) charges, modular
transformation matrices, and fusion rules are preserved under this map,
providing strong evidence for the equivalence of these coset models.Comment: 25 pages, harvmac, no figures, added referenc
Use of arm measurements to improve radiative transfer models used in climate models
The demands of accurate predictions of radiative transfer for climate applications are well-documented. While much effort is being devoted to evaluating the accuracy of the GCM radiative transfer schemes, the problem of developing accurate, computationally efficient schemes for climate models still remains. This paper discusses our efforts in developing accurate and fast computational methods for global and regional climate models
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