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Salmonella is one of the most important foodborne pathogens around the world. The knowledge that very low numbers of Salmonella cells can be infectious emphasizes the need for stringent food safety measures Traditional methods for isolating and identifying Salmonella in food rely on preenrichment, selective enrichment in selective and differential media, biochemical tests, and serological confirmation. Recent advances in diagnostic technology have considerably altered testing methods for foodborne Salmonella. Many commercial assay systems and kits that use newer technologies are available to facilitate the identification of Salmonella in foods. These systems include miniaturized biochemical tests, new media formulations, automated instrumentation, DNA/RNA probes, antibody-dependent assays, and polymerase chain reaction. The technologies used for these systems are described, and the various kit formats are compared. Among the limitations of detection methods in terms of food safety are timeliness, limits of detection, and differentiation of virulent and nonvirulent isolates. Current efforts of prevention measures and strategies at different links of the food chain such as consumer education and hazard analysis and critical control point (HACCP) programs are reviewed, Global approaches to food safety are needed.. 相似文献
334.
Release behavior of tritium from the graphite tiles used at dome top and inner dome wing in JT-60U was investigated by the thermal desorption method in dry argon, argon with oxygen and water vapor, or argon with hydrogen. It was found that approximately 20-40% of total tritium is left in graphite even after heating to the high temperature above 1000 °C in dry argon. The residual tritium could be removed by exposing the graphite tile to oxygen with water vapor or hydrogen at the high temperature above 1000 °C. The tritium retention of the dome top tile was quantified as 84-30 kBq/cm2. The inner dome wing tile had a steep tritium distribution from 8 to 0.1 kBq/cm2. It is observed that a measurable amount of tritium existed in the deep site of the graphite tile. 相似文献
335.
Takezawa Y. Itoh Y. Shimodera M. Miya H. 《Dielectrics and Electrical Insulation, IEEE Transactions on》1998,5(2):290-295
When most organic insulators are exposed to thermal stress, they turn darker in color. The increase of electronic transition absorption due to thermal oxidation of the resin is responsible for this darker coloration. A correlation between the degree of aging of these insulators and their reflective absorbances in the near IR (infrared) wavelength range has been established previously. In this paper, a novel non-destructive diagnostic apparatus using an optical fiber sensor developed to evaluate the aging of thermally deteriorated insulators is reported. The key point of this technique is measuring the change of reflective absorbance ratio at two different wavelengths. The sensor consists of two plastic optical fibers (for light transmitting and receiving), a plastic optical coupler, two kinds of near-IR light emitting diodes as light sources, and an optical power meter as a detector, and hence is very compact and lightweight (<2 kg). The aging of an insulator can be estimated using the diagnostic curve, which is obtained by an accelerated heating experiment using model pieces. We applied this measurement technique to predict the residual life of low-voltage induction motors used in elevators 相似文献
336.
Diagnosis and management of steroid-resistant asthma 总被引:1,自引:0,他引:1
The term "steroid-resistant (SR) asthma" has been used to describe a group of asthmatics who demonstrate persistent airway obstruction and inflammation despite treatment with high doses of systemic glucocorticoids. There are at least two forms of SR asthma, that is, primary and acquired types. Type I SR asthma is acquired and is associated with abnormally reduced glucocorticoid receptor (GR) ligand and DNA binding affinity. Type II SR asthma is due to a primary GR binding abnormality. An important distinction between these two types of SR asthma is that the GR defect in Type I, but not Type II, SR asthma is reversible in culture and is sustained by incubation with combination IL-2 and IL-4. The treatment of these patients requires a systematic approach to rule out confounding factors, including triggers of immune activation, optimizing steroid therapy, and use of alternative strategies to inhibit airway inflammation. 相似文献
337.
Dipterous larvae were found in the appendices from two postmortem examinations. The single maggot in the first case was not immediately identified in the sections. However, when the posterior end of the larva was recovered from the unsectioned portion of the appendix, it was identified as a maggot of the genus Sarcophaga. The first case was believed to be a case of "pseudomyiasis,+ i.e., the accidental entrapment of a swallowed larva passing through the digestive tract. In the second case, the appendix contained numerous larvae with great variation in sizes and stages of development of the mouth hooks, pharyngeal sclerites, and spiracular breathing plates. Such development was considered to have occurred within the intestinal tract, which indicated that this was a case of true intestinal myiasis. 相似文献
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339.
The inversion procedure presented in this paper is based on the statistical regression of the inverse map between the spaces of ECT scan data, and of crack parameters. The mapping is realized by a combination between a statistical data processing step, i.e., a principal component transformation of the scan data, and an incremental resolution neural network training. Starting from the necessities of improving the detrimental conditioning of the regression and of providing the inversion approach with enhanced potential for automation, a novel shifting aperture mapping concept and a data fusion technique are proposed. Supplementing the primary mapping algorithm with these latter processing steps allows one to avoid the usual anomalous-region focusing approach and improves the inversion capabilities by allowing a dynamic reconstruction of the object's profile. Unconnected and multiply connected crack shapes are well estimated, that so far eluded most other inversion methods. For this primary validation of the completed algorithm, only synthetic B-scan data are used, which are collected by an optimized, high performance sensor on the interior of a metal tube. 相似文献
340.
The effects of pergolide, a mixed D1/D2 receptor agonist, and bromocriptine, a selective D2 receptor agonist, were assessed in a visual delay task to further investigate the "dopamine link" of working memory in humans and to look for differential D1 versus D2 receptor contributions. Two groups of 32 healthy young adults (16 female) received either 0.1 mg of pergolide or 2.5 mg of bromocriptine in a placebo-controlled cross-over design. A pretreatment with domperidone, a peripherally active D2 antagonist, was performed in both groups to reduce side effects. Interindividual differences in pharmacokinetics were controlled by the time course of serum prolactin inhibition. The working memory paradigm was a visuospatial delayed matching task; the location of a randomly generated seven-point pattern had to be memorized and compared after 2, 8, or 16 sec with a second pattern that was either identical or slightly shifted within a reference frame. The task was designed with the intention to present unique stimuli at each trial and to require minimal motor demands. Practice effects between the two pharmacological test days were minimized by training sessions that preceded the tests. The paradigm showed significant error and reaction time increases with longer delays. After comparable doses, only pergolide, but not bromocriptine, facilitated visuospatial working memory performance as demonstrated by a significant drug-by-delay interaction. These findings are in accordance with the monkey literature as well as with neuroanatomical findings, and they confirm a preferential role of prefrontal D1 receptors for working memory modulation in humans. 相似文献