A simulation model for studying the role of pre-slaughter factors on the exposure of beef carcasses to human microbial hazards.

A Monte Carlo simulation model was constructed for assessing the quantity of microbial hazards deposited on cattle carcasses under different pre-slaughter management regimens. The model permits comparison of industry-wide and abattoir-based mitigation strategies and is suitable for studying pathogens such as Escherichia coli O157:H7 and Salmonella spp. Simulations are based on a hierarchical model structure that mimics important aspects of the cattle population prior to slaughter. Stochastic inputs were included so that uncertainty about important input assumptions (such as prevalence of a human pathogen in the live cattle-population) would be reflected in model output. Control options were built into the model to assess the benefit of having prior knowledge of animal or herd-of-origin pathogen status (obtained from the use of a diagnostic test). Similarly, a facility was included for assessing the benefit of re-ordering the slaughter sequence based on the extent of external faecal contamination. Model outputs were designed to evaluate the performance of an abattoir in a 1-day period and included outcomes such as the proportion of carcasses contaminated with a pathogen, the daily mean and selected percentiles of pathogen counts per carcass, and the position of the first infected animal in the slaughter run. A measure of the time rate of introduction of pathogen into the abattoir was provided by assessing the median, 5th percentile, and 95th percentile cumulative pathogen counts at 10 equidistant points within the slaughter run. Outputs can be graphically displayed as frequency distributions, probability densities, cumulative distributions or x-y plots. The model shows promise as an inexpensive method for evaluating pathogen control strategies such as those forming part of a Hazard Analysis and Critical Control Point (HACCP) system.     

An economic feasibility assessment of autonomous field machinery in grain crop production

Precision Agriculture - A multi-faceted whole farm planning model is developed to compare conventional and autonomous machinery for grain crop production under various benefit, farm size, suitable...     

Host Range and Characterization of Sunflower mosaic virus

ABSTRACT Sunflower mosaic is caused by a putative member of the family Potyviridae. Sunflower mosaic virus (SuMV) was characterized in terms of host range, physical and biological characteristics, and partial nucleotide and amino acid sequence. Cells infected with SuMV had cytoplasmic inclusion bodies typical of potyviruses. Of 74 genera tested, only species in Helianthus, Sanvitalia, and Zinnia, all Asteraceae, were systemic hosts. Commercial sunflower hybrids from the United States, Europe, and South Africa were all equally susceptible. The mean length of purified particles is approximately 723 nm. The virus was transmitted by Myzus persicae and Capitphorus elaegni, and also was seedborne in at least one sunflower cultivar. Indirect enzyme-linked immunosorbent assay tests with a broad-spectrum potyvirus monoclonal antibody were strongly positive. SuMV-specific polyclonal antisera recognized SuMV and, to a lesser extent, Tobacco etch virus (TEV). When tested against a panel of 31 potyvirus-differentiating monoclonal antibodies, SuMV was distinct from any potyvirus previously tested. SuMV shared four epitopes with TEV, but had a reaction profile more similar to Tulip breaking virus (TBV). SuMV did not possess epitopes unique only to TBV. The predicted coat protein had a molecular weight of 30.5 kDa. The 3' end of the virus genome was cloned and sequenced. Phylogenetic analysis of the coat protein amino acid sequence revealed that SuMV is a distinct species within the family Potyviridae, most closely related to TEV.     

Radar soundings of the subsurface of Mars

The martian subsurface has been probed to kilometer depths by the Mars Advanced Radar for Subsurface and Ionospheric Sounding instrument aboard the Mars Express orbiter. Signals penetrate the polar layered deposits, probably imaging the base of the deposits. Data from the northern lowlands of Chryse Planitia have revealed a shallowly buried quasi-circular structure about 250 kilometers in diameter that is interpreted to be an impact basin. In addition, a planar reflector associated with the basin structure may indicate the presence of a low-loss deposit that is more than 1 kilometer thick.     

Within and between-field spatial variation in soil phosphorus in permanent grassland

Soil phosphorus (P) concentrations above certain critical thresholds are a problem in many areas leading to its transport into surface and ground waters. Site-specific nutrient applications and the development of nutrient management plans for farms would help to optimize nutrient applications, meet crop requirements and take into consideration current soil nutrient status. In Northern Ireland, high concentrations of soil P are common, whereas low concentrations of soil potassium (K) and sulphur (S) have been reported in many silage fields. This study used grid and transect soil sampling to measure within- and between-field spatial variation in soil Olsen-P status across a 50-ha permanent grassland site used for silage production. Soil phosphorus indices ranged from Index 1 to Index 4 within single fields. The spatial patterns of soil P across fields suggested that there was scope for site-specific P fertilizer applications, with variable quantities of P being applied to different fields and within individual fields. Site-specific nutrient management has the potential to reduce excess P applications in some areas and avoid deficiencies in others, thereby minimizing environmental problems and optimizing yield.