AN ASSESSMENT OF LOCAL COMMUNITy DEVELOPMENT NEEDS CRITERIA

Objectives needs criteria adopted by local housing and community development administrators are typically not direct measures of urban blight; rather they are labels for disadvantaged circumstances assumed to be associated with adverse living conditions. This case study of Portland, Oregon, addresses the question of whether such criteria (1) document the actual presence of blighting problems, and (2) can be identified in spatial concentrations for the purpose of geographical targeting. The results of hypothesis tests, correlations, and factor analysis show strong positive relationships among most but not all locally adopted criteria. Findings support the conclusion that the principal benefits test and neighborhood strategy area concept, both integral to the original CDBG program, are still valid.     

THE DEVELOPMENT OF A RISK ASSESSMENT MODEL FOR USE IN THE POULTRY INDUSTRY

A simulation model that assesses the risk of acquiring salmonellosis from consumption and handling of chicken was created in an Excel ™ spreadsheet and was simulated using Risk ™. The model simulated the distribution, preparation, and consumption of 1,000 chickens and was designed to determine the relationship between the level of Salmonella contamination on chickens at the processing plant exit and the risk of salmonellosis for consumers of the chickens. A scatter plot of the probability of acquiring salmonellosis from consumption of the chickens simulated versus the Salmonella load on the chickens at the processing plant exit clearly showed that highly (i.e., > 100 Salmonella/ bird) contaminated chickens at the plant exit did not necessarily pose greater risk of salmonellosis than lightly (i.e., < 10 Salmonella/ bird) contaminated chickens at the plant exit. Rather, greater risk of salmonellosis was realized from lightly contaminated chickens when they were temperature-abused, undercooked, and consumed by someone from the high risk population.     

EFFECT OF CHILLING AND FREEZING ON SURVIVAL OF VIBRIO PARAHAEMOLYTICUS ON FISH FILLETS1

Vibrio parahaemolyticus is a foodborne pathogen isolated from coastal waters of the United States, and from seafoods including fish. No information is available on the viability of V. parahaemolyticus on raw, chilled and frozen fish. A three‐strain mixture of V. parahaemolyticus was inoculated on fish fillets (pH 6.4) to obtain a bacterial load of 10⁴ (high) or 10³ (low) CFU/fillet, and stored at 4C or 8C for 9 days or at – 18C for seven weeks. At 4C and 8C, and at both levels of inoculation, V. parahaemolyticus survived on the fillets for the entire duration of the study. However, there was a significant reduction (P < 0.01) in V. parahaemolyticus population on the fillets by 9 days of storage. In the frozen fillets, there was a sharp decline (P < 0.01) in the population of V. parahaemolyticus by day 5 of storage. Although chilling and freezing significantly (P < 0.01) inactivated high numbers of V. parahaemolyticus on fish, they cannot be relied upon as a method to reduce V. parahaemolyticus on fish, since the time and magnitude of reduction depends on the initial load of the pathogen and the storage temperature.     

Quantification of Factors Which Influence Nisin's Inhibition of CIostridium botulinum 56A in a Model Food System

We modeled nisin's anticlostridial activity and assessed the antagonistic or potentiating influences of food ingredients. The model systems contained yeast extract, proteose peptone, and glucose; were supplemented with protein (0.075, 0.75, 7.5% w/v), phospholipid (0.075, 0.75, 7.5% w/v), or soluble starch (5, 17.5, 30% w/v); and were adjusted to pH 5.5, 6.0, or 6.5. Samples inoculated with 10⁴/mL spores were incubated at 15, 25, or 35°C. Statistical analysis developed an equation (r²= 0.76) that modeled the response and identified temperature as the most significant (α 0.001) variable. Nisin lost effectiveness with increasing temperature. Nisin concentration had significant positive and phospholipid negative, linear effects. Many interactive effects were significant (α 0.20). Nisin inhibited C. botulinum until its residual level dropped below a threshold, which decreased from 154 IU/mL at 35°C to 12 IU/mL at 15°C.     

Current and emerging molecular diagnostic technologies applicable to bacterial food safety

There is an increasing need for rapid test methods to certify the quality and safety of food products. Current tests applied for the microbiological assessment of food products are based on standard approved culture-based isolation methods and can take several days to yield results. Nucleic acid diagnostic (NAD) tests for the identification of bacterial foodborne pathogens employing in vitro amplification technologies are capable of sensitive and specific detection of single or multiple pathogens in foods in a shorter timeframe than traditional methods. New developments in molecular biosensors have the potential to provide at-line bioanalysis, whereas microarray-based technologies may in the future be the NAD platforms of choice for multiple pathogen detection and identification. This article reviews current and emerging NAD platforms for foodborne bacterial pathogens that have the potential to impact food safety.     

Predicted Static Fatigue Behavior of Specially Coated Optical Glass Fibers

Long-term static fatigue behavior of optical glass fibers is controlled by their strength, fatigue resistance, and zerostress aging behavior. The effectiveness of four special coatings in preventing the long-term static fatigue deterioration of optical glass fibers was evaluated by determining the dynamic fatigue behavior and the effects of zero-stress aging on strength of the four specially coated optical glass fibers in water from 25° to 85°C. The results clearly show that the strength, fatigue resistance, and aging behavior varied significantly between these specially coated fibers. By analysis of these experimental results in terms of fracture mechanics principles, the predicted static fatigue behaviors of the four fibers were compared. Ideally the optimum fiber is one that exhibits a high strength, low strength variability, high fatigue resistance, and high aging resistance. Each of these specially coated fibers had a deficiency in at least one of these properties.     

Tracer Diffusion and Electrical Conductivity in Sodium-Rubidium Silicon Sulfide Glasses

The tracer diffusion coefficients of ²²Na and ⁸⁶Rb and electrical conductivity were measured in a series of 0.56(Na, Rb)₂S.0.44SiS₂ glasses as a function of the Rb/Na ratio and temperature. The data were used to calculate the Haven ratio as a function of the Rb/Na ratio. The Haven ratio at 149.6°C increases from ∼0.3 in single-alkali glasses to ∼0.80 for intermediate compositions. The results are consistent with a single jump mechanism involving jumps of alkali ions between unoccupied sites. The observed correlation effects arise through interactions between alkali ions and charge-compensating centers in the glass network. The charge-compensating centers are thought to correspond to non-bridging oxygen ions in some oxide glasses and to nonbridging sulfur ions in sodium-rubidium silicon sulfide glasses.     

Glass Inhomogeneity Measurement Using the Shelyubskii Method

Inhomogeneity in glass can be measured in terms of the variance of the refractive index distribution by using the Shelyubskii method. In the method, the transmission of an optical cell containing glass particles immersed in a nearly matching refractive index liquid is measured. Transmission can be measured accurately and reproducibly as a function of wavelength with a conventional spectrophotometer. The primary source of errors, hitherto, has been the Raman-Shelyubskii theory to relate the transmission to the refractive index variance by using interference optics principles. It is shown that a common Shelyubskii experiment can be described more cogently by a theory based on the principles of geometric optics. A Monte Carlo simulation of light ray tracing through the optical cell containing glass particles with a random distribution of refractive index was conducted. The fraction of intensity collected within the acceptance angle of the spectrophotometer, identified as the transmission, agrees well with the measured data. A glass inhomogeneity meter based on the simulation experiments is described.