Rapid detection of Salmonella in pet food: design and evaluation of integrated methods based on real-time PCR detection

Reducing the risk of Salmonella contamination in pet food is critical for both companion animals and humans, and its importance is reflected by the substantial increase in the demand for pathogen testing. Accurate and rapid detection of foodborne pathogens improves food safety, protects the public health, and benefits food producers by assuring product quality while facilitating product release in a timely manner. Traditional culture-based methods for Salmonella screening are laborious and can take 5 to 7 days to obtain definitive results. In this study, we developed two methods for the detection of low levels of Salmonella in pet food using real-time PCR: (i) detection of Salmonella in 25 g of dried pet food in less than 14 h with an automated magnetic bead-based nucleic acid extraction method and (ii) detection of Salmonella in 375 g of composite dry pet food matrix in less than 24 h with a manual centrifugation-based nucleic acid preparation method. Both methods included a preclarification step using a novel protocol that removes food matrix-associated debris and PCR inhibitors and improves the sensitivity of detection. Validation studies revealed no significant differences between the two real-time PCR methods and the standard U.S. Food and Drug Administration Bacteriological Analytical Manual (chapter 5) culture confirmation method.     

Effectiveness of neural network types for prediction of business failure

The study examines the effectiveness of different neural networks in predicting bankruptcy filing. Two approaches for training neural networks, Back-Propagation and Optimal Estimation Theory, are considered. Within the back-propagation training method, four different models (Back-Propagation, Functional Link Back-Propagation With Sines, Pruned Back-Propagation, and Cumulative Predictive Back-Propagation) are tested. The neural networks are compared against traditional bankruptcy prediction techniques such as discriminant analysis, logit, and probit. The results show that the level of Type I and Type II errors varies greatly across techniques. The Optimal Estimation Theory neural network has the lowest level of Type I error and the highest level of Type II error while the traditional statistical techniques have the reverse relationship (i.e., high Type I error and low Type II error). The back-propagation neural networks have intermediate levels of Type I and Type II error. We demonstrate that the performance of the neural networks tested is sensitive to the choice of variables selected and that the networks cannot be relied upon to “sift through” variables and focus on the most important variables (network performance based on the combined set of Ohlson and Altman data was frequently worse than their performance with one of the subsets). It is also important to note that the results are quite sensitive to sampling error. The significant variations across replications for some of the models indicate the sensitivity of the models to variations in the data.     

Rhesus monkeys (Macaca mulatta), video tasks, and implications for stimulus-response spatial contiguity.

Recent reports (Iwai, Yaginuma, & Mishkin, 1986; Yaginuma & Iwai, 1986) have supported the earlier conclusion by Meyer, Treichler, and Meyer (1965) and by Stollnitz (1965) that the efficiency of primate learning is compromised to the degree that there is spatial discontiguity between discriminanda and the locus of response. The research reported in this article calls for a reconsideration of this conclusion. Two rhesus monkeys (Macaca mulatta) easily mastered precise control of a joystick to respond to a variety of computer-generated targets despite the fact that the joystick was located 9 to 18 cm from the video screen. We hold that stimulus–response contiguity is a significant parameter of learning only to the degree that the monkey visually attends to the directional movements of its hand in order to displace discriminanda as in the Wisconsin General Test Apparatus. If, instead, attention is focused on the effects of the hand's movement rather than on the hand itself, stimulus–response contiguity is no longer a primary parameter of learning. The implications of this work for mirror-guided studies are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Self-efficacy and outcome expectancy mechanisms in reading and writing achievement.

Examined the relation between self-efficacy and outcome expectancy beliefs and achievement in reading and writing. Most of the 153 subjects were White, middle-class undergraduate students. Efficacy for reading and writing tasks and component skills and outcome expectancies that reading and writing are important for realizing life goals were assessed. Reading achievement was measured by the Degrees of Reading Power test and writing achievement was measured by a holistically scored writing sample. Results from regression analysis indicated that self-efficacy and outcome expectancy beliefs jointly account for significant variance in reading achievement with self-efficacy being the stronger predictor and that self-efficacy, but not outcome expectancy, accounts for significant variance in writing achievement. Canonical correlation analysis identified a single underlying dimension linking beliefs and achievement for reading and writing, with reading beliefs and achievement contributing most strongly to the relation. Results are discussed as they relate to previous research and needed areas of future study. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Summation in the chimpanzee (Pan troglodytes).

In this research, we asked whether 2 chimpanzee (Pan troglodytes) subjects could reliably sum across pairs of quantities to select the greater total. Subjects were allowed to choose between two trays of chocolates. Each tray contained two food wells. To select the tray containing the greater number of chocolates, it was necessary to sum the contents of the food wells on each tray. In experiments where food wells contained from zero to four chocolates, the chimpanzees chose the greater value of the summed wells on more than 90% of the trials. In the final experiment, the maximum number of chocolates assigned to a food well was increased to five. Choice of the tray containing the greater sum still remained above 90%. In all experiments, subjects reliably chose the greater sum, even though on many trials a food well on the "incorrect" tray held more chocolates than either single well on the "correct" tray. It was concluded that without any known ability to count, these chimpanzees used some process of summation to combine spatially separated quantities. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Children's perceptions of the personal relationships in their social networks.

Tested the hypothesis that children would report that different social-network members provide different social provisions, using 199 5th–6th grade White children. Ss completed network of relationships inventories, which assessed 10 qualities of their relationships with mothers, fathers, siblings, grandparents, friends, and teachers. Consistent with R. S. Weiss's (1974) theory (i.e., that individuals seek specific social provisions or types of social support in their relationships with others), Ss reported seeking different provisions from different individuals. Mothers and fathers were turned to most often for affection, enhancement of worth, a sense of reliable aid, and instrumental aid. Next to parents, grandparents were turned to most often for affection and enhancement of worth, and teachers were turned to most often for instrumental aid. Friends were the greatest source of companionship, and friends and mothers received the highest ratings of intimacy. Ss also reported having more power in their relationships with other children than in those with adults. Conflict was perceived as occurring most often in sibling relationships. Ss were most satisfied with their relationships with mothers, and they thought their relationships with mothers and fathers were the most important. Bases for children's differentiations of their relationships and implications for understanding social networks are discussed. (19 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Issues in the Processing of Cuprate Ceramic Superconductors

A number of the important issues in the processing of dense, superconducting ceramics are addressed and illustrated with examples drawn from our studies of the processing of yttrium barium cuprate. Among the phenomena affecting the attainment of dense, fully superconducting materials are those common to the processing of other ceramics, namely, control of composition, prevention of microcracking, adequate time for the decomposition, and escape of intermediaries prior to surface densification (the so-called "binder burn-off" problem). Additional requirements include the necessity to ensure complete oxygenation throughout the microstructure for full volume superconductivity and the control of texture development for maximizing the attainable transport critical current density. On the basis of the processing issues described, it is concluded that the optimum microstructure is one having finescale, interconnected porosity (to ensure escape of carbonate-like species and subsequent, rapid oxygenation) with a fine grain size (∼1 μm) to avoid microcracking.     

Video-task assessment of learning and memory in macaques (Macaca mulatta): Effects of stimulus movement on performance.

Effects of stimulus movement on learning, transfer, matching, and short-term memory performance were assessed with 2 monkeys using a video-task paradigm (VTP) in which the animals responded to computer-generated images by manipulating a joystick. Performance on tests of learning set, transfer index, matching to sample, and delayed matching to sample in the VTP was comparable to that obtained in previous investigations using the Wisconsin General Testing Apparatus (D. M. Rumbaugh et al, 1989). Additionally, learning, transfer, and matching were reliably and significantly better when the stimuli or discriminanda moved than when the stimuli were stationary. External manipulations such as stimulus movement may increase attention to the demands of a task, which in turn should increase the efficiency of learning. Findings have implications for the investigation of learning in other populations, as well as for the application of the VTP to comparative study. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Polynomial trend surface analysis applied to AVHRR images to improve definition of arctic leads

Polynomial trend surface analysis was applied to three AVHRR images to determine whether regional trends in image radiance can be removed with this procedure. Results suggest that trend surface techniques can be effective in removing region-scale variation in image radiances that are related to uneven illumination, intermittent cloud cover, and variation in the surface temperature field. The dominant effects of illumination in Channel 2 (visible) data, caused by variable sun angle and proximity of the scene to the terminator, can be minimized by removing (subtracting) the first- and second-order trend surfaces from the raw image. These low-order surfaces also remove regional variation in the surface temperature field, which leads to marginal improvement in binary images derived from Channel 4 (infrared) data. Optimum results for both Channel 2 and Channel 4 data are achieved when the third- and fourth-order surfaces are subtracted to remove local temperature and illumination anomalies that occur at smaller spatial scales, primarily in the vicinity of clouds. Application of higher order surfaces fails to improve image quality. There is some indication that the topography of these higher-order surfaces in part maps regional variation in lead density. Use of a best-fit criterion based on a strict variance technique (such as the least-squares method) to define the trend surface limits the effectiveness of the technique in this application. Criteria that allow for data to be weighted based on their distance from the plane about which they cluster are more appropriate to the structure of AVHRR radiance data typical of images that show sea ice. A criterion that incorporates a rule system based on fuzzy logic offers an alternative means of assessing goodness-of-fit that might prove appropriate in this application.     

Catalytic reduction of residual styrene monomer in polystyrene

Styrene monomer has a low taste and odor threshold, and its presence in the polystyrene used in food packaging applications must be as low as possible. Conventional devolatilization technology does not lower styrene contents to desired levels, so special costly devolatilization techniques have to be used. Attempts to employ scavengers for styrene to reduce residual monomer levels have been largely unsuccessful. This article evaluates the possibility that strong acids can be used to induce residual styrene to alkylate styrene units in polystyrene by Friedel–Crafts reactions. The results of studies evaluating this approach indicate its feasibility, but colored products are obtained when sulfonic acids are used and prohibitively high levels of acids must be used to be effective. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1786–1791, 2002