Causality, Input Price Variability, and Structural Changes in the U.S. Livestock- Meat Industry

Industrial Organization, Livestock Production/Industries,

A human operator simulator model of the NASA Terminal Configured Vehicle (TCV)

A generic operator model called HOS was used to simulate the behavior and performance of a pilot flying a transport airplane during instrument approach and landing operations in order to demonstrate the applicability of the model to problems associated with interfacing a crew with a flight system. The model which was installed and operated on NASA Langley's central computing system is described. Preliminary results of its application to an investigation of an innovative display system under development in Langley's terminal configured vehicle program are considered

Parameterization of Dark-Energy Properties: a Principal-Component Approach

Considerable work has been devoted to the question of how to best parameterize the properties of dark energy, in particular its equation of state w. We argue that, in the absence of a compelling model for dark energy, the parameterizations of functions about which we have no prior knowledge, such as w(z), should be determined by the data rather than by our ingrained beliefs or familiar series expansions. We find the complete basis of orthonormal eigenfunctions in which the principal components (weights of w(z)) that are determined most accurately are separated from those determined most poorly. Furthermore, we show that keeping a few of the best-measured modes can be an effective way of obtaining information about w(z).Comment: Unfeasibility of a truly model-independent reconstruction of w at z>1 illustrated. f(z) left out, and w(z) discussed in more detail. Matches the PRL versio

A Slower Superluminal Velocity for the Quasar 1156+295

As part of an ongoing effort to observe high energy gamma-ray blazars with VLBI, we have produced 8 and 2 GHz VLBI images, at ten epochs spanning the years 1988 to 1996, of the quasar 1156+295. The VLBI data have been taken from the Washington VLBI correlator's geodetic database. We have detected detected four components and have measured their apparent speeds to be 8.8 +/- 2.3, 5.3 +/- 1.1, 5.5 +/- 0.9, and 3.5 +/- 1.2 h^{-1}c from the outermost component inwards. (H_{0}=100h km/(s Mpc), q_{0}=0.5 throughout paper). These velocities contradict a previously published very high superluminal velocity of 26 h^{-1}c for this source.Comment: 8 pages, 2 figures, accepted to ApJ Letter

New method of making advanced tube-bundle rocket thrust chambers

An improved method of fabrication rocket chambers for future space applications is described. Included are fabrication demonstrator and test chambers produced by this method. This concept offers the promise of improved cyclic life, reusability, and performance. The performance is improved because of the enhanced enthalpy extraction. The improved cyclic life, reusability, and reliability is improved because of the structural compliance inherent in the construction. The method of construction involves the forming of the combustion chamber by a tube-bundle of high conductivity copper or copper alloy tubes and the bonding of these tubes by a unique electroforming operation. Furthermore, the method of fabrication reduces chamber complexity by incorporating manifolds, and structural stiffeners while having the potential for thrust chamber cost and weight reduction

Chern-Simons action for inhomogeneous Virasoro group as an extension of three dimensional flat gravity

We initiate the study of a Chern-Simons action associated to the semi-direct sum of the Virasoro algebra with its coadjoint representation. This model extends the standard Chern-Simons formulation of three dimensional flat gravity and is similar to the higher-spin extension of three dimensional anti-de Sitter or flat gravity. The extension can also be constructed for the exotic but not for the cosmological constant deformation of flat gravity.Comment: 15 pages. Version to appear in J. of Math. Phy

Constraining the initial temperature and shear viscosity in a hybrid hydrodynamic model of sNN\sqrt{s_{NN}}=200 GeV Au+Au collisions using pion spectra, elliptic flow, and femtoscopic radii

A new framework for evaluating hydrodynamic models of relativistic heavy ion collisions has been developed. This framework, a Comprehesive Heavy Ion Model Evaluation and Reporting Algorithm (CHIMERA) has been implemented by augmenting UVH 2+1D viscous hydrodynamic model with eccentricity fluctuations, pre-equilibrium flow, and the Ultra-relativistic Quantum Molecular Dynamic (UrQMD) hadronic cascade. A range of initial temperatures and shear viscosity to entropy ratios were evaluated for four initial profiles, $N_{part}$ and $N_{coll}$ scaling with and without pre-equilibrium flow. The model results were compared to pion spectra, elliptic flow, and femtoscopic radii from 200 GeV Au+Au collisions for the 0--20% centrality range.Two sets of initial density profiles, $N_{part}$ scaling with pre-equilibrium flow and $N_{coll}$ scaling without were shown to provide a consistent description of all three measurements.Comment: 21 pages, 32 figures, version 3 includes additional text for clarification, division of figures into more manageable units, and placement of chi-squared values in tables for ease of viewin

Femtoscopic results in Au+Au and p+p from PHENIX at RHIC

Ultra-relativistic gold-gold and proton-proton collisions are investigated in the experiments of the Relativistic Heavy Ion Collider (RHIC). In the last several years large amount of results were revealed about the matter created in these collisions. The latest PHENIX results for femtoscopy and correlations are reviewed in this paper. Bose-Einstein correlations of charged kaons in 200 GeV Au+Au collisions and of charged pions in 200 GeV p+p collisions are shown. They are both compatible with previous measurements of charged pions in gold-gold collisions, with respect to transverse mass or number of participants scaling.Comment: Talk given at the VI Workshop on Particle Correlations and Femtoscopy, Kiev, September 14-18, 2010. 6 pages, 4 figures. This work was supported by the OTKA grant NK73143 and M. Csanad's Bolyai scholarshi