7,825 research outputs found
Pneumoccal Hemolysin
The purposes of this report are to describe a method of preparing a potent crude pneumococcal hemolysin, to define some of it characteristics, and to describe the effects of its administration to rabbits
SUPPLY RELATIONSHIPS IN THE SOUTH - WHAT HAVE WE LEARNED?
Industrial Organization,
DISCUSSION OF AGRICULTURAL ECONOMICS AND THE CHANGING STRUCTURE OF HIGHER EDUCATION
Teaching/Communication/Extension/Profession,
Effects of Fermion Flavor on Exciton Condensation in Double Layer Systems
We use fermionic path integral quantum Monte Carlo to study the effects of
fermion flavor on the physical properties of dipolar exciton condensates in
double layer systems. We find that by including spin in the system weakens the
effective interlayer interaction strength, yet this has very little effect on
the Kosterlitz-Thouless transition temperature. We further find that, to obtain
the correct description of screening, it is necessary to account for
correlation in both the interlayer and intralayer interactions. We show that
while the excitonic binding cannot completely surpress screening by additional
fermion flavors, their screening effectiveness is reduced leading to a much
higher transition temperatures than predicted with large-N analysis.Comment: 4 pages, 3 figure
RECENT DUALITY CONTRIBUTIONS IN PRODUCTION ECONOMICS
This article is a limited assessment of the agricultural production economics literature since 1982 that resulted from dual modeling approaches. Contributions have removed several perceived obstacles to dual modeling, such as testing curvature, identifying the technology when prices are collinear, and examining dynamics of production. Some contributions have also removed obstacles to primal modeling. Dual methods have been used in risk applications only recently and still appear less convenient than primal methods. Convenience may become the primary criterion for selecting primal or dual methods.Production Economics,
DERIVED DEMAND FOR IRRIGATION WATER: THE CALIFORNIA AQUEDUCT
Resource /Energy Economics and Policy,
Estimation of trend in state-space models: Asymptotic mean square error and rate of convergence
The focus of this paper is on trend estimation for a general state-space
model , where the th difference of the trend
is assumed to be i.i.d., and the error sequence
is assumed to be a mean zero stationary process. A fairly precise asymptotic
expression of the mean square error is derived for the estimator obtained by
penalizing the th order differences. Optimal rate of convergence is
obtained, and it is shown to be "asymptotically equivalent" to a nonparametric
estimator of a fixed trend model of smoothness of order . The results of
this paper show that the optimal rate of convergence for the stochastic and
nonstochastic cases are different. A criterion for selecting the penalty
parameter and degree of difference is given, along with an application to
the global temperature data, which shows that a longer term history has
nonlinearities that are important to take into consideration.Comment: Published in at http://dx.doi.org/10.1214/08-AOS675 the Annals of
Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical
Statistics (http://www.imstat.org
Path Integral Monte Carlo Simulations for Fermion Systems: Pairing in the Electron-Hole Plasma
We review the path integral method wherein quantum systems are mapped with
Feynman's path integrals onto a classical system of "ring-polymers" and then
simulated with the Monte Carlo technique. Bose or Fermi statistics correspond
to possible "cross-linking" of polymers. As proposed by Feynman, superfluidity
and Bose condensation result from macroscopic exchange of bosons. To map
fermions onto a positive probability distribution, one must restrict the paths
to lie in regions where the fermion density matrix is positive. We discuss a
recent application to the two-component electron-hole plasma. At low
temperature excitons and bi-excitons form. We have used nodal surfaces
incorporating paired fermions and see evidence of a Bose condensation in the
energy, specific heat and superfluid density. In the restricted path integral
picture, pairing appears as intertwined electron-hole paths. Bose condensation
occurs when these intertwined paths wind around the periodic boundaries.Comment: 14 pages, 7 figures Prepared for the 1999 International Conference on
Strongly Coupled Coulomb Systems, Saint-Malo, Franc
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