Bayesian logistic regression of soybean sclerotinia stem rot prevalence in the u.s. North-central region: accounting for uncertainty in parameter estimation

ABSTRACT Bayesian ideas have recently gained considerable ground in several scientific fields mainly due to the rapid progress in computing resources. Nevertheless, in plant epidemiology, Bayesian methodology is not yet commonly discussed or applied. Results of a logistic regression analysis of a 4-year data set collected between 1995 and 1998 on soybean Sclerotinia stem rot (SSR) prevalence in the north-central region of the United States were reexamined with Bayesian methodology. The objective of this study was to use Bayesian methodology to explore the level of uncertainty associated with the parameter estimates derived from the logistic regression analysis of SSR prevalence. Our results suggest that the 4-year data set used in the logistic regression analysis of SSR prevalence in the north-central region of the United States may not be informative enough to produce reliable estimates of the effect of some explanatory variables on SSR prevalence. Such confident estimations are necessary for deriving robust conclusions and high quality predictions.     

Vitamin B12 responses to cobalt pellets in beef cows

Objective To assess the effectiveness of cobalt pellets in maintaining adequate vitamin B₁₂ in beef cows on pasture of low cobalt content.
Design A field experiment in a herd grazing cobalt deficient pasture.
Animals Mature Murray Grey cows.
Procedure Cows were given a single oral dose of 0, 1, 2 or 4 cobalt pellets (30 g pellets containing 30% by weight cobaltic oxide) with a selenium pellet and a grub screw. Samples of blood, liver, faeces and milk for chemical analyses were collected at intervals over a period of 2 years after treatment.
Results A single cobalt pellet raised liver vitamin B₁₂ concentration of cows above that of untreated cows for at least 28 weeks, and 2 or 4 pellets for 57 weeks. Plasma vitamin B₁₂ concentration was an unreliable indicator of the effectiveness of cobalt pellet therapy. Milk vitamin B₁₂ and faecal cobalt concentrations increased in response to cobalt pellet therapy.
Conclusion These studies show that one cobalt pellet will prevent vitamin B₁₂ inadequacy in beef cows for between 28 and 57 weeks; two or four pellets will prevent inadequacy for 57 to 75 weeks. Milk vitamin B₁₂ concentration may be a useful indicator of the effectiveness of cobalt pellets in increasing the vitamin B₁₂ supply in lactating cows.     

Bayesian analysis in plant pathology

ABSTRACT Bayesian methods are currently much discussed and applied in several disciplines from molecular biology to engineering. Bayesian inference is the process of fitting a probability model to a set of data and summarizing the results via probability distributions on the parameters of the model and unobserved quantities such as predictions for new observations. In this paper, after a short introduction of Bayesian inference, we present the basic features of Bayesian methodology using examples from sequencing genomic fragments and analyzing microarray gene-expressing levels, reconstructing disease maps, and designing experiments.     

The relationship of subsequent racing performance to foreleg flight patterns during racing speed workouts of unraced 2-year-old Thoroughbred racehorses at auctions

Workouts of 980 unraced 2-year-old Thoroughbred racehorses at major U.S. auctions were videotaped using digital high-speed video equipment (ie, slow motion) and studied for signs of extraneous foreleg motion.^a Extraneous foreleg motion included, but was not limited to: 1) hyper rotation of the cannon bone on an axis parallel to the plane of the running surface (ie, moving in sagittal plane; hoof hitting an elbow in extreme cases) and perpendicular to the direction of the racetrack longitudinally; and 2) foreleg flight patterns not symmetrical and/or not parallel to the vector of the forward momentum of the horse's center of gravity (eg, winging, paddling, and/or wobbling at joints). Experienced Thorough bred racehorse industry videographers and gait analysis researchers were trained and used as film reviewers who rated foreleg motion on a scale of 1 to 5, with 1 indicating little or no extraneous motion, 3.5 indicating average extraneous motion (relative to the other unraced 2-year-olds at these auctions and to more than 20,000 similar horses at similar auctions over the past 10 years), and 5 indicating extreme extraneous motion (ie, at least 1 standard deviation or more from the mean). Because these were subjective ratings, only the more extreme rankings were used for comparison purposes in this study—that is, a minority (15.3%) of the overall study population.

A group of 73 horses with “good” foreleg motion had ratings from 1 to 3. A group of 77 horses with “bad” foreleg motion had ratings from 4 to 5. The subsequent North American racing performance of horses with good and bad foreleg motion was compared. Both groups had similar average velocity and similar distribution patterns of the velocities of the workouts, so the differences between the groups that are discussed in this study were not caused by different overall workout velocities.

Extraneous foreleg motion was shown to be related to subsequent racing earnings and the level of racing competition achieved. Horses with good foreleg motion (as defined herein) earned more and had greater stakes-level success than horses with bad foreleg motion. For example, the median earnings per start of horses with good foreleg motion was 83% higher than those of horses with bad foreleg motion, and horses with good foreleg motion were 58% more likely to win a top race (ie, one designated as a “graded” stakes) than horses with bad foreleg motion. However, the “good movers” raced less overall than the “bad movers.”

A secondary finding of this study is that although there is a widely held industry belief that horses with high action or bad foreleg motion are more suited to turf racing, horses with good foreleg motion were more likely than horses with bad foreleg motion to race at least once on turf, and, among horses to race on turf, horses with good foreleg motion were more likely than horses with bad foreleg motion to win and to finish “in the money” (ie, at least third).     

Thermal Structure of Jupiter's Upper Atmosphere Derived from the Galileo Probe

Temperatures in Jupiter's atmosphere derived from Galileo Probe deceleration data increase from 109 kelvin at the 175-millibar level to 900 ± 40 kelvin at 1 nanobar, consistent with Voyager remote sensing data. Wavelike oscillations are present at all levels. Vertical wavelengths are 10 to 25 kilometers in the deep isothermal layer, which extends from 12 to 0.003 millibars. Above the 0.003-millibar level, only 90- to 270- kilometer vertical wavelengths survive, suggesting dissipation of wave energy as the probable source of upper atmosphere heating.