MARGINAL VALUE OF QUALITY ATTRIBUTES FOR NATURAL (ORGANIC) BEEF

Demand and Price Analysis,

Optimized pulse sequences for suppressing unwanted transitions in quantum systems

We investigate the nature of the pulse sequence so that unwanted transitions in quantum systems can be inhibited optimally. For this purpose we show that the sequence of pulses proposed by Uhrig [Phys. Rev. Lett. \textbf{98}, 100504 (2007)] in the context of inhibition of environmental dephasing effects is optimal. We derive exact results for inhibiting the transitions and confirm the results numerically. We posit a very significant improvement by usage of the Uhrig sequence over an equidistant sequence in decoupling a quantum system from unwanted transitions. The physics of inhibition is the destructive interference between transition amplitudes before and after each pulse.Comment: 5 figure

The dynamic analysis of submerged structures

Methods are described by which the dynamic interaction of structures with surrounding fluids can be computed by using finite element techniques. In all cases, the fluid is assumed to behave as an acoustic medium and is initially stationary. Such problems are solved either by explicitly modeling the fluid (using pressure or displacement as the basic fluid unknown) or by using decoupling approximations which take account of the fluid effects without actually modeling the fluid

A survey of stellar X-ray flares from the XMM-Newton serendipitous source catalogue: Hipparcos-Tycho cool stars

The X-ray emission from flares on cool (i.e. spectral-type F-M) stars is indicative of very energetic, transient phenomena, associated with energy release via magnetic reconnection. We present a uniform, large-scale survey of X-ray flare emission. The XMM-Newton Serendipitous Source Catalogue and its associated data products provide an excellent basis for a comprehensive and sensitive survey of stellar flares - both from targeted active stars and from those observed serendipitously in the half-degree diameter field-of-view of each observation. The 2XMM Catalogue and the associated time-series (`light-curve') data products have been used as the basis for a survey of X-ray flares from cool stars in the Hipparcos Tycho-2 catalogue. In addition, we have generated and analysed spectrally-resolved (i.e. hardness-ratio), X-ray light-curves. Where available, we have compared XMM OM UV/optical data with the X-ray light-curves. Our sample contains ~130 flares with well-observed profiles; they originate from ~70 stars. The flares range in duration from ~1e3 to ~1e4 s, have peak X-ray fluxes from ~1e-13 to ~1e-11 erg/cm2/s, peak X-ray luminosities from ~1e29 to ~1e32 erg/s, and X-ray energy output from ~1e32 to ~1e35 erg. Most of the ~30 serendipitously-observed stars have little previously reported information. The hardness-ratio plots clearly illustrate the spectral (and hence inferred temperature) variations characteristic of many flares, and provide an easily accessible overview of the data. We present flare frequency distributions from both target and serendipitous observations. The latter provide an unbiased (with respect to stellar activity) study of flare energetics; in addition, they allow us to predict numbers of stellar flares that may be detected in future X-ray wide-field surveys. The serendipitous sample demonstrates the need for care when calculating flaring rates.Comment: 26 pages, 24 figures. Additional tables and figures available as 4 ancillary files. To be published in Astronomy and Astrophysic

Flexible body dynamic stability for high performance aircraft

Dynamic equations which include the effects of unsteady aerodynamic forces and a flexible body structure were developed for a free flying high performance fighter aircraft. The linear and angular deformations are assumed to be small in the body reference frame, allowing the equations to be linearized in the deformation variables. Equations for total body dynamics and flexible body dynamics are formulated using the hybrid coordinate method and integrated in a state space format. A detailed finite element model of a generic high performance fighter aircraft is used to generate the mass and stiffness matrices. Unsteady aerodynamics are represented by a rational function approximation of the doublet lattice matrices. The equations simplify for the case of constant angular rate of the body reference frame, allowing the effect of roll rate to be studied by computing the eigenvalues of the system. It is found that the rigid body modes of the aircraft are greatly affected by introducing a constant roll rate, while the effect on the flexible modes is minimal for this configuration

Acoustic-loads research for powered-lift configurations

Data presented from large-scale model tests with jet engines having thrusts of 9 kN (2000 lb) and 36 kN (8000 lb) include acoustic loads for an externally blown wing and flap induced by a TF34 jet engine, an upper surface blown (USB) aircraft model in a wind tunnel, and two USB models in static tests. Comparisons of these results with results from acoustic loads studies on configurations of other sizes are made and the implications of these results on interior noise and acoustic fatigue are discussed

Feedback in a cavity QED system for control of quantum beats

Conditional measurements on the undriven mode of a two-mode cavity QED system prepare a coherent superposition of ground states which generate quantum beats. The continuous system drive induces decoherence through the phase interruptions from Rayleigh scattering, which manifests as a decrease of the beat amplitude and an increase of the frequency of oscillation. We report recent experiments that implement a simple feedback mechanism to protect the quantum beat. We continuously drive the system until a photon is detected, heralding the presence of a coherent superposition. We then turn off the drive and let the superposition evolve in the dark, protecting it against decoherence. At a later time we reinstate the drive to measure the amplitude, phase, and frequency of the beats. The amplitude can increase by more than fifty percent, while the frequency is unchanged by the feedback.Comment: 13 pages, 5 figures, ICAP 2012 23rd International Conference on Atomic Physic

Partially Unbiased Entangled Bases

In this contribution we group the operator basis for d^2 dimensional Hilbert space in a way that enables us to relate bases of entangled states with single particle mutually unbiased state bases (MUB), each in dimensionality d. We utilize these sets of operators to show that an arbitrary density matrix for this d^2 dimensional Hilbert space system is analyzed by via d^2+d+1 measurements, d^2-d of which involve those entangled states that we associate with MUB of the d-dimensional single particle constituents. The number $d^2+d+1$ lies in the middle of the number of measurements needed for bipartite state reconstruction with two-particle MUB (d^2+1) and those needed by single-particle MUB [(d^2+1)^2].Comment: 5 page