SAMPLING SCHEMES TO DETECT VERY LOW CONCENTRATIONS

Many mycotoxins and certain drug residues can be important at very low concentrations in feeds and foods. Government regulatory agencies establish maximum acceptance concentrations (Action Levels) to avoid proven effects of known toxins and provide Advisory Levels where effects are not yet well established. The Action Levels for the aflatoxins range from 5 to 300 ppb (ng/g) depending on the particular toxin and the intended use of the feed or food. Other naturally occurring mycotoxins, such as DON, zearalenones, and fumonisons, have advisory levels in the range of 1 to 5 ppm (j.A-g/g) . Chemotherapeutic agents in feeds must be measured in ppm or even ppb. Common acceptance sampling techniques can usually be used for liquids, flours, meals, etc. A problem arises, however, when the substance to be measured is concentrated in individual kernels of grain. In some cases, a single hot II kernel contains enough toxin to contaminate thousands of clean kernels. The common sampling techniques for large lots (such as truck, barge or ship loads) can be unreliable at concentrations around the Action or Advisory Levels. The problem will continue to arise as modern testing instruments become more sensitive at lower concentrations. This paper will review some biases of current sampling procedures and discuss methods of changing the sizes of the types I and II errors

INTEGRATION, RISK, AND SUPPLY RESPONSE: A SIMULATION AND LINEAR PROGRAMMING ANALYSIS OF AN EAST TEXAS COW-CALF PRODUCER

Livestock Production/Industries,

NEW TOOLS FOR NEW TIMES

The purpose of this presentation is to challenge statisticians to develop new tools needed by modern scientists. We are in the midst of a Scientific Revolution being driven by computers and the internet. Scientists are gathering huge amounts of data on the usual measurements while continually developing new instruments for new measurements. Data sets full of measurements which may pertain to the scientist\u27s research are easily available on the internet. Scientists are being overwhelmed with data. Agricultural producers and consumers are asking for more information. Scientists need new tools to evaluate variation. They need help with sampling - numbers of observations required and proper sampling schemes. Examples and suggestions will be offered. Statistical Process Control as applied to farming systems will be discussed

X-Ray Microanalysis of Ca and K in Corn Bran and Oat Hulls

Oat hulls and dry-milled corn bran were loaded with calcium or potassium and made into either sectioned bulk specimens of intact tissue embedded in resin or into non-sectioned bulk specimens made from powdered-compressed tissue formed into disks without resin. Regression lines of X-ray count versus mineral concentration were similar for both Ca and K. X-ray count versus mineral concentration relationships were similar for intact oat hulls and powdered-compressed specimens of either oat hulls or corn bran. However, the relationship for intact corn bran embedded in resin was significantly different. While the reason for this difference is not known, the result emphasizes the importance of using a proper calibration matrix to relate mineral concentration in biological material with X-ray count values. The standard error in slope of the regression lines, 0.07 and 0.08 for corn bran and oat hull, respectively, embedded in aged epoxy resin suggest that X-ray counts from these specimens allow one to estimate Ca or K concentration with a standard deviation of ± 10%. X-ray counts of Ca, K, and Cl in specimens embedded in epoxy resin decreased to stable values approximately four weeks after the resin was cured

A Hybrid Lagrangian Variation Method for Bose-Einstein Condensates in Optical Lattices

Solving the Gross--Pitaevskii (GP) equation describing a Bose--Einstein condensate (BEC) immersed in an optical lattice potential can be a numerically demanding task. We present a variational technique for providing fast, accurate solutions of the GP equation for systems where the external potential exhibits rapid varation along one spatial direction. Examples of such systems include a BEC subjected to a one--dimensional optical lattice or a Bragg pulse. This variational method is a hybrid form of the Lagrangian Variational Method for the GP equation in which a hybrid trial wavefunction assumes a gaussian form in two coordinates while being totally unspecified in the third coordinate. The resulting equations of motion consist of a quasi--one--dimensional GP equation coupled to ordinary differential equations for the widths of the transverse gaussians. We use this method to investigate how an optical lattice can be used to move a condensate non--adiabatically.Comment: 16 pages and 1 figur

Testing the Gaussian Copula Hypothesis for Financial Assets Dependences

Using one of the key property of copulas that they remain invariant under an arbitrary monotonous change of variable, we investigate the null hypothesis that the dependence between financial assets can be modeled by the Gaussian copula. We find that most pairs of currencies and pairs of major stocks are compatible with the Gaussian copula hypothesis, while this hypothesis can be rejected for the dependence between pairs of commodities (metals). Notwithstanding the apparent qualification of the Gaussian copula hypothesis for most of the currencies and the stocks, a non-Gaussian copula, such as the Student's copula, cannot be rejected if it has sufficiently many ``degrees of freedom''. As a consequence, it may be very dangerous to embrace blindly the Gaussian copula hypothesis, especially when the correlation coefficient between the pair of asset is too high as the tail dependence neglected by the Gaussian copula can be as large as 0.6, i.e., three out five extreme events which occur in unison are missed.Comment: Latex document of 43 pages including 14 eps figure

the impact of delayed treatment on 6 minute walk distance test in patients with pulmonary arterial hypertension a meta analysis

Abstract Background The impact of treatment delay in stable patients with pulmonary arterial hypertension (PAH) remains unaddressed. Methods This meta-analysis included six datasets of PAH therapies with randomized-controlled trials (RCT) and corresponding open-label extension (OLE) studies. We evaluated the change in 6MWD at 1year in the OLE studies by active treatment versus ex-placebo group. The ex-placebo group (i.e., the patients randomized to placebo in the RCT and ultimately treated with active therapy in the OLE) represented the "delay-in-treatment" population. Results Patients with a treatment delay of 12–16weeks in PAH targeted therapy had an improvement in 6-minute walk distance (6MWD) test at 1year, but this improvement did not amount to the same degree of improvement as their initially treated counterparts. The difference in 6MWD was 15m to 20m at 1year. Conclusion A short-term delay in PAH targeted therapy may adversely affect functional capacity in patients with PAH. This meta-analysis provides some insight as to whether earlier treatment would benefit stable patients with PAH

Astrophysics and Technical Study of a Solar Neutrino Spacecraft

We report on our study of the design of a neutrino detector, shielding and veto array needed to operate a neutrino detector in space close to the Sun. This study also took into account the expected rates of Galactic gamma and cosmic rays in addition to the particles from the Sun.These preliminary studies show that we can devise a detector such that a small signal of neutrino interactions can be extracted from a large random number of events from the background sources using a double timing method from the conversion electron produced in the neutrino interaction and a secondary delayed signal from the nuclear excited state produced from the initial neutrino interaction; in our case the conversion of Ga 69 or 71 into Ge 69 or 71, but this method could apply to other nuclei with large neutrino cross sections such as Ir 115. Although these types of events need to be above 0.405 megaelectronvolt (MeV) neutrino energy and are only 66 percent of all conversion neutrino interactions on Gallium, this is a small price to pay for an increase of 10,000 by going close to the Sun to enhance the neutrino rate over the background combatorical fake-signal events. The conclusion of this Phase-1 study is very positive in that we can get the backgrounds less than 20 percent fake signals, and in addition to this we have devised another shielding method that makes the Galactic gamma-ray rate a hundred fold less which will make further improvements over these initial estimates. Although these studies are very encouraging it suggests that the next step is a NIAC Phase-II to actually build a test device,measuring basic principles such as light attention within the scintillator with high dopants and to take data in the lab with a cosmic-ray test stand and triggered X-ray source for comparison with simulated expected performance of the detector. This would be the perfect lead into a future proposal beyond a NIAC (NASA Innovative Advanced Concepts) Phase-II for a test flight of a small one-pint detector in orbit of the detector concept beyond Earth outside of the radiation belts