Occurrence of Campylobacter spp. in raw and ready-to-eat foods and in a Canadian food service operation

The occurrence of Campylobacter spp. in a variety of foods from Ottawa, Ontario, Canada, and raw milk samples from across Canada was determined over a 2-year period. The samples consisted of 55 raw foods (chicken, pork, and beef), 126 raw milk samples from raw milk cheese manufacturers, and 135 ready-to-eat foods (meat products, salads, and raw milk cheeses). Campylobacter jejuni was detected in 4 of the 316 samples analyzed: 1 raw beef liver sample and 3 raw chicken samples. An isolation rate of 9.7% was observed among the raw chicken samples tested. This study also investigated the role of cross-contamination in disseminating Campylobacter from raw poultry within a food service operation specializing in poultry dishes. Accordingly, kitchen surfaces within a restaurant in Ottawa, Ontario, were sampled between March and August 2001. Tests of the sampling method indicated that as few as 100 Campylobacter cells could be detected if sampling was done within 45 min of inoculation; however, Campylobacter spp. were not detected in 125 swabs of surfaces within the kitchens of this food service operation. Despite the reported high prevalence of Campylobacter spp. in raw poultry, this organism was not detected on surfaces within a kitchen of a restaurant specializing in poultry dishes.     

Insight into the intermolecular interactions in the NF3–HSO system: a computational study

Quantum calculations were carried out in order to investigate the heterodimers of NF₃ with the HSO molecule in the gas phase at the MP2/aug-cc-pVDZ and MP2/aug-cc-pVTZ//MP2/aug-cc-pVDZ computational levels. Ten minima were located on the potential energy surface (PES) of the NF₃–HSO system. Binding energies corrected with basis set superposition error are in the range 3.15–7.85?kJ/mol. The atom in molecules theory was applied to analyze the nature of intermolecular interactions.     

Lipid and lipoprotein concentrations in pregnancies complicated by intrauterine growth restriction

Previous studies have shown that in preeclampsia, plasma lipids climb substantially above levels seen in normal pregnancies. Such lipid changes may play a role in the endothelial damage characteristic of preeclampsia. Pregnancies complicated by intrauterine growth restriction (IUGR), without preeclampsia, have similar placental pathology to preeclampsia despite the absence of the maternal systemic manifestations of hypertension and proteinuria. The aim of this study was to perform a cross-sectional study of lipid and lipoprotein concentrations in the third trimester, from normal pregnancies, and those complicated by IUGR without preeclampsia. Our hypothesis was that, in contrast to the exaggerated lipid changes seen in preeclampsia, lipid and lipoprotein concentrations in IUGR would be similar to those of matched healthy pregnant controls. Fasting blood samples for lipids and lipoprotein fractions were taken in the third trimester, from eight women with IUGR; and eight women with uncomplicated pregnancies, matched as a group for age, booking weight, parity, and gestational age at sampling. There were no significant differences (P > 0.05) in the median concentrations of triglyceride, high-density lipoprotein, and very-low-density lipoprotein 1 (VLDL1), between cases and controls. However, women with IUGR pregnancies had significantly lower cholesterol [4.95 mmol/L (3.35-7.10) vs. 7.47 (5.75-8.45); median (range) for IUGR patients and controls, respectively; P < 0.01], low-density lipoprotein (LDL)-cholesterol [2.45 mmol/L (0.95-3.60) vs. 4.25 (3.35-5.60); P < 0.01], VLDL2 mass [59.0 mg/dL (37-87) vs. 103.0 (64-168); P < 0.01], intermediate-density lipoprotein mass [56.0 mg/dL (31-110) vs. 125.6 (91-157); P < 0.01], and total LDL mass [221.0 mg/dL (104-237) vs. 380.3 (267-534); P < 0.01]. In addition, it was noteworthy that, with respect to LDL-cholesterol and total LDL mass, there was little or no overlap in the ranges of concentrations measured between cases and controls. Because VLDL2 and intermediate-density lipoprotein are the synthetic precursors to LDL in the circulation, their significantly lower median concentrations imply a failure of appropriate LDL synthesis in IUGR pregnancies. Whatever the mechanism, if our results are confirmed in larger studies and longitudinal investigations, then LDL-cholesterol measurements (when LDL-cholesterol fails to rise appropriately or is low in the third trimester) may be of use in identifying mothers with, or at risk of, a pregnancy complicated by IUGR.     

Corporeal veno-occlusive dysfunction: predominantly intracavernous muscular pathology

PURPOSE: We investigated whether a relationship exists between the flow to maintain an erection obtained at cavernosometry and the alteration of intracavernous structures in impotent patients with corporeal veno-occlusive dysfunction and normal arterial inflow. MATERIALS AND METHODS: Computerized histomorphometric analysis of smooth muscle and elastic fibers, and endothelial cells was compared to the flow necessary to maintain erection after intracavernous vasoactive drug injection in 18 patients with corporeal veno-occlusive dysfunction. RESULTS: A significant correlation between percentage of smooth muscle fibers and flow to maintain erection was observed, while no correlation was noted with elastic fibers and endothelial cells. CONCLUSIONS: Corporeal veno-occlusive dysfunction seems to be due mainly to smooth muscular alterations. According to this observation treatment of impotent patients with this abnormality should not be restricted to the penile veins but should also include the intracavernous structures, predominantly the muscular component.     

磺化纤维素减水剂在水泥颗粒表面的吸附与作用机理

对比研究了磺化纤维素(CS)和商品萘系高效减水剂(FDN)在水泥颗粒表面的吸附特性、ζ电位以及减水剂掺量对流动度的影响。探讨了磺化纤维素减水剂的作用机理。结果表明,减水剂吸附改变了水泥颗粒表面结构与电化学性质,通过静电斥力和空间位阻发挥分散作用。掺加CS后水泥颗粒的ζ电位较FDN的小,而CS在水泥颗粒的吸附量较FDN的大;FDN的分散作用主要依赖于ζ电位的静电斥力;CS对水泥的良好分散作用是由静电斥力和空间位阻共同作用;由于新生水化产物对静电斥力的屏蔽作用,静电斥力引起的分散作用稳定性较差,流动度经时损失大;空间位阻效应受水化影响较小,其分散作用的稳定性较好,流动度经时损失较小。     

Composition dependence of some physical, magnetic and electrical properties of Ga substituted Mn-ferrites

Samples with the chemical formula MnGa _x Fe_{2 – x} O₄ (x = 0, 0.1, 0.3, 0.5 and 0.7) were prepared by the usual ceramic method. X-ray analysis revealed the presence of single spinel phase. The lattice parameter as well as the porosity are found to decrease while the density and grain size are increased with increasing Ga concentration (x). The magnetization, the initial permeability and Curie temperature are decreased with increasing x. On the other hand, the electrical resistivity is increased with increasing Ga concentration. The results are explained according to the assumed cation distribution.     

Reinforcement learning of iterative behaviour with multiple sensors

Reinforcement learning allows an agent to be both reactive and adaptive, but it requires a simple yet consistent representation of the task environment. In robotics this representation is the product of perception. Perception is a powerful simplifying mechanism because it ignores much of the complexity of the world by mapping multiple world states to each of a few representational states. The constraint of consistency conflicts with simplicity, however. A consistent representation distinguishes world states that have distinct utilities, but perception systems with sufficient acuity to do this tend to also make many unnecessary distinctions.In this paper we discuss reinforcement learning and the problem of appropriate perception. We then investigate a method for dealing with the problem, called theLion algorithm [1], and show that it can be used to reduce complexity by decomposing perception. The Lion algorithm does not allow iterative rules to be learned, and we describe modifications that overcome this limitation. We present experimental results that demonstrate their effectiveness in further reducing complexity. Finally, we mention some related research, and conclude with suggestions for further work.