45,956 research outputs found
Three loop HTL perturbation theory at finite temperature and chemical potential
In this proceedings contribution we present a recent three-loop
hard-thermal-loop perturbation theory (HTLpt) calculation of the thermodynamic
potential for a finite temperature and chemical potential system of quarks and
gluons. We compare the resulting pressure, trace anomaly, and
diagonal/off-diagonal quark susceptibilities with lattice data. We show that
there is good agreement between the three-loop HTLpt analytic result and
available lattice data.Comment: 4 pages, 4 figure
The scheduling of sparse matrix-vector multiplication on a massively parallel dap computer
An efficient data structure is presented which supports general unstructured sparse matrix-vector multiplications on a Distributed Array of Processors (DAP). This approach seeks to reduce the inter-processor data movements and organises the operations in batches of massively parallel steps by a heuristic scheduling procedure performed on the host computer.
The resulting data structure is of particular relevance to iterative schemes for solving linear systems. Performance results for matrices taken from well known Linear Programming (LP) test problems are presented and analysed
Magnetic and superfluid phases of confined fermions in two-dimensional optical lattices
We examine antiferromagnetic and d-wave superfluid phases of cold fermionic
atoms with repulsive interactions in a two-dimensional optical lattice combined
with a harmonic trapping potential. For experimentally realistic parameters,
the trapping potential leads to the coexistence of magnetic and superfluid
ordered phases with the normal phase. We study the intriguing shell structures
arising from the competition between the magnetic and superfluid order as a
function of the filling fraction. In certain cases antiferromagnetism induce
superfluidity by charge redistributions. We furthermore demonstrate how these
shell structures can be detected as distinct anti-bunching dips and pairing
peaks in the density-density correlation function probed in expansion
experiments.Comment: 4 pages, 3 figure
Statistical Analysis of Project Pyro Liquid Propellant Explosion Data
Statistical regression analysis of Project Pyro cryogenic propellant explosion test dat
Stochastic Bioeconomics: A Review of Basic Methods and Results
Basic bioeconomic models which incorporate uncertainty are reviewed to show and compare the principal methods used and results reported in the literature. Beginning with a simple linear control model of stock uncertainty, we proceed to discuss more complex models which explicitly recognize risk preferences, firm and industry behavior, and market price effects. The effects of uncertainty on the results of bioeconomic analysis are rarely unambiguous, and in some instances differ little from corresponding deterministic results. This review is presented to enhance readers' appreciation of the papers to follow in this and the next issue of the journal.Environmental Economics and Policy, International Development, Resource /Energy Economics and Policy, Risk and Uncertainty,
Realized volatility
Realized volatility is a nonparametric ex-post estimate of the return variation. The most obvious realized volatility measure is the sum of finely-sampled squared return realizations over a fixed time interval. In a frictionless market the estimate achieves consistency for the underlying quadratic return variation when returns are sampled at increasingly higher frequency. We begin with an account of how and why the procedure works in a simplified setting and then extend the discussion to a more general framework. Along the way we clarify how the realized volatility and quadratic return variation relate to the more commonly applied concept of conditional return variance. We then review a set of related and useful notions of return variation along with practical measurement issues (e.g., discretization error and microstructure noise) before briefly touching on the existing empirical applications.Stochastic analysis
Do bonds span volatility risk in the U.S. Treasury market? a specification test for affine term structure models
We investigate whether bonds span the volatility risk in the U.S. Treasury market, as predicted by most 'affine' term structure models. To this end, we construct powerful and model-free empirical measures of the quadratic yield variation for a cross-section of fixed- maturity zero-coupon bonds ('realized yield volatility') through the use of high-frequency data. We find that the yield curve fails to span yield volatility, as the systematic volatility factors are largely unrelated to the cross- section of yields. We conclude that a broad class of affine diffusive, Gaussian-quadratic and affine jump-diffusive models is incapable of accommodating the observed yield volatility dynamics. An important implication is that the bond markets per se are incomplete and yield volatility risk cannot be hedged by taking positions solely in the Treasury bond market. We also advocate using the empirical realized yield volatility measures more broadly as a basis for specification testing and (parametric) model selection within the term structure literature.Bonds ; Treasury bonds
Answering the Critics: Yes, ARCH Models Do Provide Good Volatility Forecasts
Volatility permeates modern financial theories and decision making processes. As such, accurate measures and good forecasts of future volatility are critical for the implementation and evaluation of asset pricing theories. In response to this, a voluminous literature has emerged for modeling the temporal dependencies in financial market volatility at the daily and lower frequencies using ARCH and stochastic volatility type models. Most of these studies find highly significant in-sample parameter estimates and pronounced intertemporal volatility persistence. Meanwhile, when judged by standard forecast evaluation criteria, based on the squared or absolute returns over daily or longer forecast horizons, ARCH models provide seemingly poor volatility forecasts. The present paper demonstrates that ARCH models, contrary to the above contention, produce strikingly accurate interdaily forecasts for the latent volatility factor that is relevant for most financial applications.
Do Bonds Span Volatility Risk in the U.S. Treasury Market? A Specification test for Affine Term Structure Models
We investigate whether bonds span the volatility risk in the U.S. Treasury market, as predicted by most 'affine' term structure models. To this end, we construct powerful and model-free empirical measures of the quadratic yield variation for a cross-section of fixed-maturity zero-coupon bonds ("realized yield volatility") through the use of high-frequency data. We find that the yield curve fails to span yield volatility, as the systematic volatility factors are largely unrelated to the cross-section of yields. We conclude that a broad class of affine diffusive, Gaussian-quadratic and affine jump-diffusive models is incapable of accommodating the observed yield volatility dynamics. An important implication is that the bond markets per se are incomplete and yield volatility risk cannot be hedged by taking positions solely in the Treasury bond market. We also advocate using the empirical realized yield volatility measures more broadly as a basis for specification testing and (parametric) model selection within the term structure literature.
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