Quasi-elastic light scattering of carnauba wax in the liquid phase: dynamics 2

Quasi-elastic light scattering of carnauba wax in the liquid phase is obtained in a heterodyne setup, and dynamic processes are analyzed through electrophoresis. Nonspherical polar clusters are found, containing a net electrical charge. An applied square-wave electric field induces drift and rotation of these clusters.These effects are dependent on strength and frequency of the applied electric field. At 373 K and in the low frequency limit the local electric field strength is approximately 70 times the strength of the applied one. This enhancement is believed to be caused by collective orientation of the clusters. The electrophoretic mobility is 1.1 X 10(-12) m2/V sec in the high frequency limit and 7.4 X 10(-11) m2/V sec in the low frequency limit. The electric dipole moment is 6.3 X 10(-16) N(-1/2) m(-1/2) where N is the cluster density/cubic meter and the net charge is about one or two elementary charges.     

Development of the large neutron imaging system for inertial confinement fusion experiments

Inertial confinement fusion (ICF) requires a high resolution (~10 μm) neutron imaging system to observe deuterium and tritium (DT) core implosion asymmetries. A new large (150 mm entrance diameter: scaled for Laser Me?gaJoule [P. A. Holstein, F. Chaland, C. Charpin, J. M. Dufour, H. Dumont, J. Giorla, L. Hallo, S. Laffite, G. Malinie, Y. Saillard, G. Schurtz, M. Vandenboomgaerde, and F. Wagon, Laser and Particle Beams 17, 403 (1999)]) neutron imaging detector has been developed for such ICF experiments. The detector has been fully characterized using a linear accelerator and a (60)Co γ-ray source. A penumbral aperture was used to observe DT-gas-filled target implosions performed on the OMEGA laser facility. [T. R. Boehly, D. L. Brown, R. S. Craxton, R. L. Keck, J. P. Knauer, J. H. Kelly, T. J. Kessler, S. A. Kumpan, S. J. Loucks, S. A. Letzring, F. J. Marshall, R. L. McCrory, S. F. B. Morse, W. Seka, J. M. Soures, and C. P. Verdon, Opt. Commun. 133, 495 (1997)] Neutron core images of 14 MeV with a resolution of 15 μm were obtained and are compared to x-ray images of comparable resolution.     

Functional and comparative study of lingual papillae in four species of bear (Ursidae) by scanning electron microscopy

The eight current species of bear (Ursidae) are widely distributed throughout Europe, Asia, and America. They are mainly encountered in the northern hemisphere, except for the spectacled bear and the sun bear, which are also found in the south of the equator. Adaptations of the masticatory apparatus (teeth, tongue, and musculature) to diet are one of the factors that imply the greatest structural changes in the cranium. This diet may be carnivorous, herbivorous, melliferous, or insectivorous, with one type of food predominating according to the time of year. The way in which food is eaten determines the morphology of the lingual surface; generally speaking, all bears put their mouth to the food, which, initially, they lick or they let the food stick to their tongue, as occurs when insects are eaten. As in all mammals, a distinction can be made between mechanical and gustatory papillae and the development and distribution of which depend on the species and their eating habits. In this study of the complete tongues of four species of adult bears, we describe the morphology of the lingual surfaces, the different types of papillae, their characteristics, and topographic distribution. It was seen that there were five main types of lingual papillae: filiform, conical, fungiform, foliate, and vallate. Morphology of the microgrooves and pores was similar to that observed in other mammals. In general, there were no great differences among the four species of bears studied, perhaps due to the similarity in the kind of food they consume in captivity.     

南昌市城市防洪排涝水文分析

以南昌市外洲等4个水文水位站已收集到的227站年水文资料为系列样本，对城市化水平下的城市洪水成因和雨洪关系等进行研究，探索市区防洪治涝对策与途径，并为南昌市防洪排涝提供决策依据。     

人类活动与赣江流域泥沙变化规律研究

以赣江流域代表性站长系列降水、径流、泥沙等水文样本资料,研究人类活动对泥沙变化规律的影响,得到赣江流域泥沙变化规律及其发展态势,为水土保持、防洪、航运、灌溉、流域规划、河道治理、水利工程安全运行、河流泥沙站网的合理布设等国民经济建设提供科学依据.     

Complaints of foodborne illness in San Francisco, California, 1998

Foodborne diseases are an important public problem affecting millions of Americans each year and resulting in substantial morbidity and mortality. Many foodborne infections occur in outbreak settings. Outbreaks are often detected by complaints from the public to health authorities. This report reviews complaints received by the San Francisco Department of Public Health involving suspected foodborne illness in 1998. Although such foodborne complaints are commonly received by health officials, we provide the first review of population-based data describing such complaints. We use a broad definition of a foodborne disease outbreak. We judged a complaint to be a "likely foodborne disease outbreak" if it involved more than one person and more than one family; no other common meals were shared recently by ill persons; diarrhea, vomiting, or both was reported; and the incubation period was more than one hour. In 1998, 326 complaints of foodborne illness, involving a total of 599 ill people, were received by the Communicable Disease Control Unit in San Francisco. The complaints involved from 1 to 36 ill persons, with 61% involving one ill person and 25% involving two ill persons. Of the 126 reports involving illness in more than one person, 77 (61%) were judged to be likely foodborne disease outbreaks. Three of these 77 outbreaks had been investigated prior to our review. This project confirms that more foodborne disease outbreaks occur than are reported to state and national outbreak surveillance systems. Our review of the San Francisco system highlights opportunities for gleaning valuable information from the foodborne disease complaint systems in place in most jurisdictions.     

Anisakid larvae in the musculature of the Argentinean hake, Merluccius hubbsi

We report the infection levels of third-stage anisakid larva in the muscle of the Argentinean hake, Merluccius hubbsi, in relation to fish size and location in the musculature. The musculature of 42 hake was separated into hypaxial (ventral) and epiaxial (dorsal) parts and surveyed for nematode larvae. Two anisakid species were detected: Anisakis sp. (prevalence, 52.4%; mean +/- SD abundance, 1.2 +/- 1.7) and Pseudoterranova sp. (prevalence, 9.5%; mean +/- SD abundance, 0.2 +/- 0.7). Since the fish were gutted after capture, the occurrence of anisakids in the flesh indicates that the worms had migrated into the muscle before capture. The number of Anisakis sp. in muscle was not correlated with fish length or weight. Therefore, fish size cannot be used as a predictor of parasite loads in the muscle. Only one Anisakis sp. and one Pseudoterranova sp. appeared in the epiaxial musculature. The density of Anisakis sp. in the hypaxial muscles was significantly higher than that in the epiaxial ones. This suggests that removal of the hypaxial musculature can reduce the risk of anisakid-induced allergies and gastrointestinal anisakidoses among consumers.     

Detection of Campylobacter jejuni and Campylobacter coli in foods by enrichment culture and polymerase chain reaction enzyme-linked immunosorbent assay

A polymerase chain reaction (PCR) assay based on a solution hybridization format with colorimetric end-point detection (PCR ELISA) was investigated for the specific detection of Campylobacter jejuni and Campylobacter coli in food samples following enrichment culture. One hundred fifteen samples of raw meat and offal (poultry, porcine, ovine, and bovine), raw shellfish, and artificially contaminated milk were enriched in blood-free Campylobacter Enrichment Broth for 48 h. Enrichment cultures were subcultured to Campylobacter blood-free selective agar plates, and presumptive isolates were identified by phenotypic methods. DNA was extracted from 1-ml aliquots of the enrichment cultures using a rapid extraction method, and the DNA was used as the template in a PCR ELISA. A comparison of the PCR ELISA with the enrichment culture and subculture to selective agar method showed that the results of 112 of the 115 samples tested were in agreement by both methods. Seventy-one of the various food samples were positive in the PCR ELISA, and 70 samples were positive by culture. The PCR ELISA had a sensitivity of 99% and a specificity of 96%, with a positive predictive value of 97% and a negative predictive value of 98%. The PCR ELISA is a rapid, sensitive, and specific method for the detection of C. jejuni and C. coli in foods following enrichment culture and significantly reduces the time required for their detection.