A rapid most-probable-number-based enzyme-linked immunosorbent assay for the detection and enumeration of Salmonella Typhimurium in poultry wastewater.

The rapid and accurate detection and enumeration of low levels of Salmonella Typhimurium in food processing facilities are critical components of an effective hazard analysis critical control point program. The objective of this study was to develop a rapid (8 h) most probable number (MPN)-enzyme-linked immunosorbent assay (ELISA) for the detection and enumeration of Salmonella Typhimurium in wastewater. The specific objectives were to (i) characterize poly- and monoclonal Salmonella Typhimurium-specific antibodies in order to select the most specific and sensitive antibody for Salmonella Typhimurium detection, and (ii) validate the MPN assay through a correlation between the 8-h MPN-ELISA and the traditional 48-h Salmonella Typhimurium MPN method in poultry scald water. Poultry scald water samples were spiked with 10 and 50 CFU/ml of Salmonella Typhimurium. The traditional MPN method used a 48-h enrichment period followed by an analysis, while the MPN-ELISA used a 5-h enrichment period followed by a 3-h ELISA analysis. No differences (P < 0.05) were found between the traditional MPN and the MPN-ELISA, indicating the promise of the MPN-ELISA for the rapid detection and enumeration of Salmonella Typhimurium within an 8-h shift. This abbreviated assay will permit increased product sampling and more rapid movement of food between production and processing, resulting in reduced spoilage and quality losses.

Ultraviolet disinfection: similitude in Taylor-Couette and channel flow.

The inactivation data for Escherichia coli are recorded for the three reactor geometries of Taylor-Couette flow and flow between either concentric cylinders or a square channel. All of the data are shown to be correlated with the assumption of plug flow. In particular, the effects of nonuniform radiation levels are accounted for by integration across the fluid channel as done previously. However, a new correction factor is introduced that is shown to be inversely proportional to the laminar, velocity boundary thickness to account for the effects of a concentration boundary layer of surviving pathogen. It has also been demonstrated that the common problems of nonuniform radiation levels and concentration boundary layer effects in UV reactors are largely eliminated with the use of Taylor-Couette flow. Moreover, the repetitive exposure of fluid parcels to a small number of lamps in the rotating Taylor-Couette flow decreases maintainance requirements compared to the hydrodynamic equivalent of cross-flow over a tube bank or lamp array. Over a 3-log reduction in the inactivation of E. coli was demonstrated compared to a conventional channel with the same radiation dosage. Moreover, greater than a 2-log reduction was evident compared to flow through concentric cylinders.

Sampling and characterization of pharmaceutical powders and granular blends.

We use a variety of experimental results to illustrate issues and challenges involved in the sampling and characterization of pharmaceutical mixtures. Accurate and reliable characterization of granular mixtures is hindered by both the complexity of granular systems and the lack of validated and reliable sampling technology and techniques. Both sampling tools and sampling protocols are critically important for accurate characterization. Using cohesive and free-flowing powders and four thief probe designs, we reveal a large potential for extremely misleading results as well as severe disturbance of the granular bed. We also discuss results from several experiments designed to test the validity of various sampling protocols by varying parameters such as sampling location and frequency of sampling. These experiments illustrate the importance of effective sampling procedures to achieve the best and most efficient results.

Detecting functional relationships between simultaneous time series.

We describe a method to characterize the predictability and functionality between two simultaneously generated time series. This nonlinear method requires minimal assumptions and can be applied to data measured either from coupled systems or from different positions on a spatially extended system. This analysis generates a function statistic, Theta(c(0)), that quantifies the level of predictability between two time series. We illustrate the utility of this procedure by presenting results from a computer simulation and two experimental systems.

Functional dependence and quasiperiodicity in the spatiotemporal dynamics of yttrium iron garnet films.

When thin films of yttrium iron garnet (YIG) are placed in a magnetic field and driven at microwave (rf) frequencies, nonlinear interactions within the material cause the normal microwave spin precession to be modulated at lower frequencies. We measure these lower frequency (kHz) signals at two spatially separated locations on the YIG film and use linear and nonlinear analysis to study the functional dependence of the spin dynamics at one location on the spin dynamics at the other location. We see dynamical states where nonlinear analysis can detect a functional dependence that the linear analysis fails to reveal.

Antenatal marijuana use is unrelated to sexually transmitted infections during pregnancy.

OBJECTIVE: This study evaluated the relationship between marijuana use and sexually transmitted diseases in pregnant women. METHODS: A retrospective review of clinic records over a 12-1/2 month period identified all women entering prenatal care. Eighty-six women using no illicit substance other than marijuana were compared to 441 drug-free women. The prevalence of gonorrhea, chlamydia, syphilis, human immunodeficiency virus, hepatitis B surface antigen, human papilloma virus, and herpes was ascertained. RESULTS: No significant differences were found in the prevalence of any single sexually transmitted disease between pregnant women who used marijuana and drug-free pregnant women. When the presence of one or more sexually transmitted disease was considered, again no difference was found. CONCLUSION: Marijuana use was not associated with sexually transmitted disease in pregnant women.