Selecting an ignition criterion methodology for use in a radiative fire spread submodel

Research is ongoing to increase the functionality of the fire zone modeling software BRANZFIRE, by converting it from a deterministic to a probabilistic model. One component of this work is the development of a radiative fire spread submodel for which a suitable ignition criterion method is needed. This paper provides details of that ignition criterion procedure and its implementation into the submodel. A list of requirements that the ignition methodology had to satisfy was established. Of the many different piloted ignition models available, the Flux–Time Product technique, and its associated ignition criterion, was selected to be incorporated into the fire spread submodel. This method provides a practical engineering approximation of when a secondary fuel item that is subjected to incident radiation will ignite that is commensurate with the accuracy of the overall model. Primarily to demonstrate the use of the technique in the submodel, a series of ignition experiments were conducted on a single example of upholstered furniture using the Cone Calorimeter apparatus, with specimens tested in both the horizontal and vertical orientation, under piloted and auto ignition conditions. The experimental incident radiation and time‐to‐ignition data, for the piloted ignition mode, was analyzed using a modified Flux–Time Product correlation procedure. To deal with the auto ignition mode, an empirical approximation, based on the modified Flux–Time Product procedure, is proposed. Data for use in the submodel was therefore also derived for the auto ignition mode, based on an experimental determination of the minimum ignition flux. Copyright © 2010 John Wiley & Sons, Ltd.     

Solve the problem first: Constructive solution strategies can influence the accuracy of retrospective confidence judgments.

Two experiments tested whether differences in problem-solving strategies influence the ability of people to monitor their problem-solving effectiveness as measured by confidence judgments. On multiple choice problems, people tend to use either a constructive matching strategy, whereby they attempt to solve a problem before looking at the response options, or a response elimination strategy, whereby they work backward from response options trying to find one that fits as a solution. Constructive matching gives rise to different cues that may enhance confidence monitoring. Experiment 1 showed that spontaneous constructive matching in nonverbal spatial reasoning problems was associated with better confidence calibration and resolution than response elimination. We manipulated strategy in Experiment 2 by requiring constructive matching and found improved monitoring. Implications for research on monitoring, overconfidence, and the association between skill and monitoring are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of altered sterol composition on the osmotic behavior of sphaeroplasts and mitochondria ofSaccharomyces cerevisiae

The effect of sterols on the osmotic stability of mitochondrial and plasma membranes of yeast wild-types and mutants that are defective in ergosterol biosynthesis has been studied. Incorporation of the nonfungal sterol, cholesterol, into yeast membranes reduces membrane elasticity which is observed as an increased susceptibility to osmotic lysis. However, the wild-type and nystatin-resistant strains which were examined indicate that qualitative alterations in endogenously generated sterols do not affect resistance to swelling. Although these strains exhibit differences in membrane fluidity, which is influenced by the sterol accumulated by the organisms, the membrane stretching capacity shows no distinct dependence on sterol structure or bilayer fluidity.     

Impact of the Alga Cladophora on the Survival of E. coli, Salmonella, and Shigella in Laboratory Microcosm

E. coli is an indicator of recent fecal contamination of freshwater beaches around the Great Lakes region. Elevated concentrations indicate that a fecal contamination has occurred, and that the risk for contact with fecal pathogenic organisms is heightened. The green algae, Cladophora, harbors populations of E. coli and potentially allows for prolonged survival and even replication of the bacterium in the lake environment. If presence of Cladophora mats on beaches is associated with persistence of E. coli in beach water, then E. coli would be a useful indicator organism only if pathogens also were able to survive and persist in the algae. This study utilized lab microcosms to study the persistence of E. coli, and of the fecal pathogens, Salmonella and Shigella, in lake water with and without the presence of Cladophora. E. coli was able to persist for extended periods in the presence of Cladophora (attached to algal mats for 45 days). Salmonella and Shigella, however, were unable to persist for this time period while in the presence of Cladophora (Salmonella attached to Cladophora was detectable for 10 days and Shigella was detectable for only 2 days). These data imply that E. coli is able to survive in the presence of Cladophora for greater times than are the fecal pathogens and that E. coli may not be an appropriate indicator organism for beaches with accumulations of algal material.     

Receiver operating characteristics (ROCs) in recognition memory: A review.

Receiver operating characteristic (ROC) analysis is being used increasingly to examine the memory processes underlying recognition memory. The authors discuss the methodological issues involved in conducting and analyzing ROC results, describe the various models that have been developed to account for these results, review the behavioral empirical literature, and assess the models in light of those results. The empirical literature includes studies of item recognition, relational recognition (e.g., source and associative tests), as well as exclusion and remember-know tasks. Nine empirical regularities are described, and a number of unresolved empirical issues are identified. The results indicate that several common classes of recognition models, such as pure threshold and pure signal detection models, are inadequate to account for recognition memory, whereas several hybrid models that incorporate a signal detection-based process and a threshold recollection or attention process are in better agreement with the results. The results indicate that there are at least 2 functionally distinct component/processes underlying recognition memory. In addition, the ROC results have various implications for how recognition memory performance should be measured. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Preferred interpersonal distance as a function of locus of control orientation in chronic schizophrenics, nonschizophrenic patients, and normals.

Used a new instrument, the Comfortable Interpersonal Distance scale, to reassess the relationship between psychopathology and interpersonal distance. It was predicted that, since schizophrenics are more external than normals and since externality has been shown to be related to greater preferred distance from others, 20 female schizophrenics theoretically should prefer greater distance, in general, from interpersonal stimuli. 20 female nonschizophrenic patients were included as controls for the "externalizing" effects of hospitalization. Results show that schizophrenics were more external than nonschizophrenics, who were more external than 20 normals. Preferred distance from interpersonal stimuli as measured by the Comfortable Interpersonal Distance scale was greatest for schizophrenics and least for normals. Implications for future research and treatment of schizophrenic patients are discussed. (16 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Development processes in social inference: Averaging of intentions and consequences in moral judgment.

Conducted 2 experiments wih 53 kindergartners, 33 1st graders, 12 5th and 6th graders, and 19 adults to test the applicability of N. H. Anderson's (see record 1971-24805-001) relative-weight averaging model to children's judgments based on intentions and consequences. Exp I provided support for the model over a wide age range (kindergarten through adult) using stimuli similar to J. Piaget's (1965) in which the intentions ranged from positive to negative and the consequences ranged from neutral to negative. Exp II extended Exp I by including consequences ranging from positive to negative. In Exp II, intentions and consequences interacted suggesting that some modification of the assumptions of the averaging model is necessary to fully account for the data. Data from the 2 experiments suggest that both intentions and consequences influence judgments at all ages examined and that developmental changes in moral judgments are continuous rather than stagelike. These developmental differences can best be described by changes in the weights of intentions and consequences. The major developmental change appears to be a decrease in the weight of consequences with increasing age. The possibility of using algebraic models to describe the results of studies that have attempted to influence the relative importance of intentions and consequences in children's moral judgments is discussed. (16 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Reductive dissolution and biomineralization of iron hydroxide under dynamic flow conditions

Iron cycling and the associated changes in solid phase have dramatic implications for trace element mobility and bioavailability. Here we explore the formation of secondary iron phases during microbially mediated reductive dissolution of ferrihydrite-coated sand under dynamic flow conditions. An initial period (10 d) of rapid reduction, indicated by consumption of lactate and production of acetate and Fe-(II) to the pore water in association with a darkening of the column material, is followed by much lower rate of reduction to the termination of the experiment after 48 d. Although some Fe (<25%) is lost to the effluent pore water, the majority remains within the column as ferrihydrite (20-70%) and the secondary mineral phases magnetite (0-70%) and goethite (0-25%). Ferrihydrite converts to goethite in the influent end of the column where dissolved Fe(II) concentrations are low and converts to magnetite toward the effluent end where Fe(III) concentrations are elevated. A decline in the rate of Fe(II) production occurs concurrent with the formation of goethite and magnetite; at the termination of the experiment, the rate of reduction is <5% the initial rate. Despite the dramatic decrease in the rate of reduction, greater than 80% of the residual Fe remains in the ferric state. These results highlight the importance of coupled flow and water chemistry in controlling the rate and solid-phase products of iron (hydr)oxide reduction.     

Thermal inactivation of H5N1 high pathogenicity avian influenza virus in naturally infected chicken meat

Thermal inactivation of the H5N1 high pathogenicity avian influenza (HPAI) virus strain A/chicken/Korea/ES/2003 (Korea/03) was quantitatively measured in thigh and breast meat harvested from infected chickens. The Korea/03 titers were recorded as the mean embryo infectious dose (EID50) and were 10(8.0) EID50/g in uncooked thigh samples and 10(7.5) EID50/g in uncooked breast samples. Survival curves were constructed for Korea/03 in chicken thigh and breast meat at 1 degrees C intervals for temperatures of 57 to 61 degrees C. Although some curves had a slightly biphasic shape, a linear model provided a fair-to-good fit at all temperatures, with R2 values of 0.85 to 0.93. Stepwise linear regression revealed that meat type did not contribute significantly to the regression model and generated a single linear regression equation for z-value calculations and D-value predictions for Korea/03 in both meat types. The z-value and the upper limit of the 95% confidence interval for the z-value were 4.64 and 5.32 degrees C, respectively. From the lowest temperature to the highest, the predicted D-values and the upper limits of their 95% prediction intervals (conservative D-values) for 57 to 61 degrees C were 241.2 and 321.1 s, 146.8 and 195.4 s, 89.3 and 118.9 s, 54.4 and 72.4 s, and 33.1 and 44.0 s. D-values and conservative D-values predicted for higher temperatures were 0.28 and 0.50 s for 70 degrees C and 0.041 and 0.073 s for 73.9 degrees C. Calculations with the conservative D-values predicted that cooking chicken meat according to current U.S. Department of Agriculture Food Safety and Inspection Service time-temperature guidelines will inactivate Korea/03 in a heavily contaminated meat sample, such as those tested in this study, with a large margin of safety.