Stronger Partnerships for Safer Food: An Agenda for Strengthening State and Local Roles in the Nation's Food Safety System

Examines federal, state, and local agencies' responsibilities, strengths, and weaknesses in ensuring food safety. Recommends systemwide reforms to enhance state and local roles and improve surveillance, outbreak response, and regulation and inspection

SSX MHD Plasma Wind Tunnel

A new turbulent plasma source at the Swarthmore Spheromak Experiment (SSX) facility is described. The MHD wind tunnel configuration employs a magnetized plasma gun to inject high-beta plasma into a large, well-instrumented, vacuum drift region. This provides unique laboratory conditions approaching that in the solar wind: there is no applied background magnetic field in the drift region and has no net axial magnetic flux; the plasma flow speed is on the order of the local sound speed (M ~ 1), so flow energy density is comparable to thermal energy density; and the ratio of thermal to magnetic pressure is of order unity (plasma β ~ 1) so thermal energy density is also comparable to magnetic energy density. Results presented here and referenced within demonstrate the new capabilities and show how the new platform is proving useful for fundamental plasma turbulence studies

Statistically optimal analysis of samples from multiple equilibrium states

We present a new estimator for computing free energy differences and thermodynamic expectations as well as their uncertainties from samples obtained from multiple equilibrium states via either simulation or experiment. The estimator, which we term the multistate Bennett acceptance ratio (MBAR) estimator because it reduces to the Bennett acceptance ratio when only two states are considered, has significant advantages over multiple histogram reweighting methods for combining data from multiple states. It does not require the sampled energy range to be discretized to produce histograms, eliminating bias due to energy binning and significantly reducing the time complexity of computing a solution to the estimating equations in many cases. Additionally, an estimate of the statistical uncertainty is provided for all estimated quantities. In the large sample limit, MBAR is unbiased and has the lowest variance of any known estimator for making use of equilibrium data collected from multiple states. We illustrate this method by producing a highly precise estimate of the potential of mean force for a DNA hairpin system, combining data from multiple optical tweezer measurements under constant force bias.Comment: 13 pages (including appendices), 1 figure, LaTe

Horticultural Studies 1999

Horticultural Studies 1999 is the second edition of a Research Series dedicated to horticultural programs in the University of Arkansas Division of Agriculture and the Dale Bumpers College of Agricultural, Food and Life Sciences. This publication summarizes research, extension, and educational activities that serve horticultural industries and interest groups in Arkansas. The goals of this publication are to provide relevant information to the growers and end-users of horticulture crops in Arkansas and to inform the citizens of Arkansas and the surrounding region of activities related to horticulture

Interferometric Visibility of a Scintillating Source: Statistics at the Nyquist Limit

We derive the distribution of interferometric visibility for a source exhibiting strong diffractive scintillation, with particular attention to spectral resolution at or near the Nyquist limit. We also account for arbitrary temporal averaging, intrinsic variability within the averaging time, and the possibility of spatially-extended source emission. We demonstrate that the interplay between scintillation and self-noise induces several remarkable features, such as a broad "skirt" in the visibility distribution. Our results facilitate the interpretation of interferometric observations of pulsars at meter and decimeter wavelengths.Comment: 14 Pages, 5 Figures, accepted for publication in Ap

Horticultural Studies 1998

Horticulture connects with people in many ways including an enhanced awareness concerning the importance of fruits and vegetables in our diet. The health benefits of such a diet is gaining wide recognition throughout the public and will likely provide tremendous opportunities for research, education and business development. Significant faculty additions and programmatic efforts were made to the university’s fruit and vegetable programs in 1998

New High Proper Motion Stars from the Digitized Sky Survey. II. Northern Stars with 0.5<mu<2.0 arcsec/yr at High Galactic Latitudes

In a continuation of our systematic search for high proper motion stars in the Digitized Sky Survey, we have completed the analysis of northern sky fields at galactic latitudes above 25 degrees. With the help of our SUPERBLINK software, a powerful automated blink comparator developed by us, we have identified 1146 stars in the magnitude range 8<r<20 with proper motions 0.500<mu<2.000 arcsec/yr. These include 1080 stars previously listed in Luyten's proper motion catalogs (LHS, NLTT), 9 stars not previously listed in the Luyten catalogs but reported elsewhere in the literature (including 1 previously reported by our team), and 57 new objects reported here for the first time. This paper includes a list of positions, proper motions, magnitudes, and finder charts for all the new high proper motion stars. Combined with our previous study of low galactic latitude fields (see Paper I), our survey now covers over 98% of the northern sky. We conclude that the Luyten catalogs were 90% complete in the northern sky for stars with 0.5<mu<2.0 arcsec/yr down to magnitude r=19. We discuss the incompleteness of the old Luyten proper motion survey, and estimate completeness limits for our new survey.Comment: To appear in The Astronomical Journa

Simulating the Role of Stellar Rotation in the Spectroscopic Effects of Differential Limb Magnification

Finite-source effects of gravitationally microlensed stars have been well discussed in the literature, but the role that stellar rotation plays has been neglected. A differential magnification map applied to a differentially Doppler-shifted surface alters the profiles of absorption lines, compromising their ordinarily symmetric nature. Herein, we assess the degree to which this finite-source effect of differential limb magnification (DLM), in combination with stellar rotation, alters spectroscopically derived stellar properties. To achieve this, we simulated a grid of high-magnification microlensing events using synthetic spectra. Our analysis shows that rotation of the source generates differences in the measured equivalent widths of absorption lines supplementary to DLM alone, but only of the order of a few percent. Using the wings of H alpha from the same simulated data, we confirmed the result of Johnson et al. (2010) that DLM alters measurements of effective temperature by < 100 K for dwarf stars, while showing rotation to bear no additional effect.Comment: Accepted for publication in PASA, 7 pages, 5 figures, 1 tabl