Enterovirulence of enterotoxigenic Bacteroides fragilis in gnotobiotic pigs.

A porcine isolate of enterotoxigenic Bacteroides fragilis colonized the intestinal tract and caused watery, nonhemorrhagic diarrhea when given orally to 12, 1- to 2-day-old gnotobiotic pigs. Diarrhea occurred 2 to 3 days post-inoculation and continued throughout the 4 to 6 day post-inoculation period. Diarrheic pigs became mildly anorexic and dehydrated. They developed intestinal lesions characterized by swelling, vacuolation, and exfoliation of enterocytes, and crypt hyperplasia throughout the large intestine and, to a lesser extent, in the distal small intestine. Bacterial adherence to, or invasion of, the intestinal mucosa was not detected. A porcine isolate of nonenterotoxigenic B. fragilis was administered orally to six control pigs. The isolate colonized the intestinal tract, but the pigs did not develop clinical disease or intestinal lesions. The pathogenetic mechanism of the disease may involve mediation by a soluble enterotoxin (or toxins) elaborated by B. fragilis.     

Factors responsible for the introduction and spread of Campylobacter jejuni infection in commercial poultry production

Campylobacter jejuni and related thermophilic campylobacters were not found in a hatchery or in chicks aged less than seven days. However, an increasing proportion of chicks aged two weeks and older shed campylobacters in their droppings. It was shown that a likely source of C jejuni for young chicks was the environment in the immediate vicinity of the rearing houses, and that infection could readily be introduced on the footwear and clothing of farm staff. Thermophilic campylobacters were found in the air, litter and drinking water containers in the rearing and finishing houses.     

Lesions of spinal cord parelaphostrongylosis in sheep. Sequential changes following intramedullary larval migration

Spinal cord nematodiasis epidemiologically, clinically, and histologically consistent with Parelaphostrongylus tenuis infection was noted in two flocks of sheep. Spinal cords from two sheep with active infection and one from a partially recovered animal were studied in an effort to determine the sequence of lesions following larval invasion of the central nervous system. In the former two sheep, migration of larvae within the spinal cord induced asymmetrically irregular tracks of disrupted and necrotic tissue, primarily in white matter. Subsequently, macrophages infiltrated these regions and phagocytized the necrotic tissue, which led to cavity formation. Swelling and loss of axons, diminished myelin staining, mononuclear cell infiltration and increase in astrocytic fibers were often seen in adjacent tissue. Only occasional coiled larvae were found in these actively infected animals. Late stage lesions in the white matter in the partially recovered sheep included multiple small astrogliotic regions with diminished myelin and axonal content, and a single large multicavitary, atrophic, gliotic zone.     

The effect of various flooring materials on performance and foot health of early-weaned pigs

The effects of various flooring materials on the performance and foot health of early-weaned piglets were evaluated in seven trials using 728 pigs. Pigs housed on galvanized flattened expanded metal, plastic-coated expanded metal, perforated galvanized panels, galvanized woven wire and plastic-coated woven wire had similar average daily gains, average daily feed intakes and feed/gain ratios. Foot pad scores were lower (less cuts, cracks and abrasions) for plastic-coated expanded metal, plastic-coated woven wire and perforated galvanized panels than for galvanized expanded metal and galvanized woven wire. While foot pad scores varied among flooring materials, none of the flooring materials produced lesions that resulted in any visible discomfort or inhibition of locomotion of the pigs. Correlation coefficients between individual pig body weight and foot pad scores were positively related indicating that body weight may be a factor contributing to lesion severity. Although foot pad lesions were common in the weanling pigs, with some variation due to flooring materials, there were no differential effects among the flooring materials evaluated on performance or visible comfort of the pigs.     

Making Asian students,making students Asian: The racialisation of export education in Auckland,New Zealand

Abstract: In recent years, international education has become a source of considerable political, academic and media debate in New Zealand. This is nowhere more the case than with regards to Auckland, the New Zealand city that has hosted the greatest number of international students. This paper focuses on the media debates around international students in Auckland with particular emphasis on the representations of the largest group of international students, those who originate from countries within the North‐East Asian region. The media representations of these students have fixed a diverse group of individuals within a singular racial identity that is known by stereotypical economic, cultural and social characteristics. As a result, these representations have further problematised the interaction between international students and the host population in Auckland while simultaneously implicating a cohort of young New Zealand citizens and permanent residents who are of similar descent within the same discourses. This process of othering the Asian student, regardless of citizenship, has consequences not simply for the practice of exporting education in this city but also for the future of a multicultural Auckland and New Zealand.     

Influence of soil moisture stress and soil bulk density on the imbibition of corn seeds in a sandy soil

The imbibition of corn seeds (Zea mays L.) was examined in a sandy soil compacted to simulate the effect that might be expected from pressure wheels behind a planting machine.Water uptake was found to be exponential and to be the only factor contributing to the increase in volume of the seed during imbibition. Changes in bulk density of the soil over the range from 0.90 to 1.31 Mg cm^?3 produced no significant effects on water uptake.It was therefore concluded that the degree of contact between seed coat and soil particles is not an important factor in influencing the rate of imbibition of corn seeds under the specific conditions which were examined.Water flux into the seeds was calculated to be several orders of magnitude lower than bulk soil water flux at all soil water potentials tested. Estimates of seed coat permeability suggest that, for corn, this factor is the major restriction on entry of water into the seed during imbibition.At a field level, the widespread use of pressure wheels behind corn planters as a means of increasing seed/soil contact appears not to be necessary in sandy soils.     

Soil microbial, fungal, and nematode responses to soil fumigation and cover crops under potato production

Sodium N-methyldithiocarbamate (metam sodium) and 1,3 dichloropropene are widely used in potato production for the control of soil-borne pathogens, weeds, and plant parasitic nematodes that reduce crop yield and quality. Soil fumigation with metam sodium has been shown in microcosm studies to significantly reduce soil microbial populations and important soil processes such as C and N mineralization. However, few published data report the impact of metam sodium on microbial populations and activities in potato production systems under field conditions. Fall-planted white mustard (Brassica hirta) and sudangrass (Sorghum sudanense) cover crops may serve as an alternative to soil fumigation. The effect of metam sodium and cover crops was determined on soil microbial populations, soil-borne pathogens (Verticillium dahliae, Pythium spp., and Fusarium spp.), free-living and plant-parasitic nematodes, and C and N mineralization potentials under potato production on five soil types in the Columbia Basin of Eastern Washington. Microbial biomass C was 8–23% greater in cover crop treatments compared to those fumigated with metam sodium among the soil types tested. Replacing fumigation with cover crops did not significantly affect C or N mineralization potentials. Cumulative N mineralized over a 49-day laboratory incubation averaged 18 mg NO₃-N kg⁻¹ soil across all soil types and treatments. There was a general trend for N mineralized from fumigated treatments to be lower than cover-cropped treatments. Soil fungal populations and free-living nematode levels were significantly lowered in fumigated field trials compared to cover-cropped treatments. Fumigation among the five soil types significantly reduced Pythium spp. by 97%, Fusarium spp. by 84%, and V. dahliae by 56% compared to the mustard cover crop treatment. The percentage of bacteria and fungi surviving fumigation was greater for fine- than coarse-textured soils, suggesting physical protection of organisms within the soil matrix or a reduced penetration and distribution of the fumigants. This suggests the potential need for a higher rate of fumigant to be used in fine-textured soils to obtain comparable reductions in soil-borne pathogens.     

Influence of a probiotic adjunct culture of Enterococcus faecium on the quality of cheddar cheese

Cheddar cheese has previously been shown to be an effective vehicle for delivery of viable cells of a probiotic Enterococcus faecium strain to the gastrointestinal tract. The particular strain, E. faecium PR88, has proven efficacy in the treatment of irritable bowel syndrome, and in this study it was evaluated for suitability as a starter adjunct for Cheddar cheese manufacture. When added to cheesemilk at an inoculum of 2 x 10(7) cfu/mL, the enterococcal adjunct maintained viability in Cheddar cheese at levels of up to 3 x 10(8) cfu/g during 9 months of ripening. Increased proteolysis and higher levels of some odor-active volatile compounds were observed in Cheddar cheeses containing the PR88 adjunct compared with the control throughout the ripening period. In addition, the enterococcal adjunct strain did not affect cheese composition. Although sensory evaluation showed no significant difference in flavor/aroma and body/texture scores between control and experimental cheeses, repeated comments by the commercial grader consistently described the cheeses containing PR88 as 'more advanced than the control' and as having 'better flavor'. These findings indicate that the presence of the PR88 adjunct strain in Cheddar cheese at levels of >/=10(8) cfu/g may positively influence Cheddar flavor.     

Generating solitons by phase engineering of a bose-einstein condensate

Quantum phase engineering is demonstrated with two techniques that allow the spatial phase distribution of a Bose-Einstein condensate (BEC) to be written and read out. A quantum state was designed and produced by optically imprinting a phase pattern onto a BEC of sodium atoms, and matter-wave interferometry with spatially resolved imaging was used to analyze the resultant phase distribution. An appropriate phase imprint created solitons, the first experimental realization of this nonlinear phenomenon in a BEC. The subsequent evolution of these excitations was investigated both experimentally and theoretically.