Silicone-polyethylene blends

Polyethylene and reactive, high molecular weight polydimethylsiloxanes have been blended under conditions of shear and elevated temperature in order to form uniform, thermoplastic blends. The materials can be extruded, coated on wire, injection molded, or compression molded. Despite the thermoplastic nature, a high gel fraction is present. A structure is proposed consisting of microgelled and grafted particles of silicone dispersed in polyethylene. When compared to pure polyethylene, the blends show lowered modulus over a temperature range of ?150 to +65°C increased gas permeability, and lowered mixing energies. Electrical properties include corona resistance superior to polyethylene and a resistance to degradation under conditions simulating those experienced by buried cables superior to typical silicone rubber. Other electrical properties are intermediate between the values observed in the component polymers.     

Volatile organic acids in raw wastewater and in physico-chemical treatment

The purpose of the present study was to identify soluble organics, which comprise the high BOD remaining in the effluent from direct physico-chemical treatment of strong raw sewage. Salts of volatile organic acids were found to be the main constituents of the organic fraction remaining after chemical treatment and activated carbon adsorption. The fate of the volatile acids such as acetic, propionic, butyric, valeric, isovaleric and hexanoic acids was followed in each stage of the physicochemical treatment.     

Differential effects of induced mood on retrieval of pleasant and unpleasant events from episodic memory.

Examined the effect of depressed mood on the accessibility of memories of past real-life experiences of a pleasant or unpleasant nature. By means of a mood induction procedure, 30 students (mean age 19.2 yrs) were made happy on one occasion and depressed on another. The 2 mood states differed significantly on self-report, speech-rate, and recall-latency measures. Stimulus words to which Ss had to associate past pleasant or unpleasant experiences were presented in each mood condition, and latency of retrieval was measured. Time to retrieve pleasant memories, relative to time to retrieve unpleasant memories, was significantly longer when Ss were depressed than when they were happy, suggesting a differential effect of mood on the accessibility of these 2 types of memory. Results are considered in relation to state-dependent learning and activation of memories, and their implications for models and treatment of depression are discussed. It is suggested that cognitive models of depression need to be extended to include a reciprocal relation between thought content and depressed mood. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Control of magnetophoretic mobility by susceptibility-modified solutions as evaluated by cell tracking velocimetry and continuous magnetic sorting

With the analytical expression for the magnetophoretic mobility of an ideal, linearly polarizable sphere undergoing creeping motion in viscous medium, we have shown that both attractive and repulsive motions are possible in the magnetic field. We have validated theoretical predictions using magnetic monodisperse microspheres of 5.2-microm diameter and nonmagnetic polystyrene microspheres of 6.99-microm diameter suspended in solutions of paramagnetic ions. The microsphere magnetophoretic mobility was measured using a modified particle tracking velocimetry system, developed in-house and called a cell tracking velocimeter. The product of measured mobility and viscosity agrees well with the theoretical prediction, differing only by approximately 11%. Further, a 26% increase in resolution between magnetic and nonmagnetic particle distributions was evaluated when paramagnetic ion carrier was used instead of water. Continuous particle sorting based on differences in magnetophoretic mobility was performed with another device developed by us, the quadrupole magnetic flow sorter (QMS). In the QMS, the introduction of paramagnetic ions into the carrier was effective in suppressing nonspecific crossover (i.e., the transport of low-mobility particles into the magnetic particle fraction) in particles and in biologically relevant red blood cells and thus showed promise as a means of increasing the purity of the magnetic separation.     

Estimating potential environmental loadings of Cryptosporidium spp. and Campylobacter spp. from livestock in the Grand River Watershed, Ontario, Canada

Exposure to waterborne pathogens in recreational or drinking water is a serious public health concern. Thus, it is important to determine the sources of pathogens in a watershed and to quantify their environmental loadings. The natural variability of potentially pathogenic microorganisms in the environment from anthropogenic, natural, and livestock sources is large and has been difficult to quantify. A first step in characterizing the risk of nonpoint source contamination from pathogens of livestock origin is to determine the potential environmental loading based on animal prevalence and fecal shedding intensity. This study developed a probabilistic model for estimating the production of Cryptosporidium spp. and Campylobacter spp. from livestock sources within a watershed. Probability density functions representing daily pathogen production rates from livestock were simulated for the Grand River Watershed in southwestern Ontario. The prevalence of pathogenic microorganisms in animals was modeled as a mixture of beta-distributions with parameters drawn from published studies. Similarly, gamma-distributions were generated to describe animal pathogen shedding intensity. Results demonstrate that although cattle are responsible for the largest amount of manure produced, other domesticated farm animals contribute large numbers of the two pathogenic microorganisms studied. Daily pathogen production rates are highly sensitive to the parameters of the gamma-distributions, illustrating the need for reliable data on animal shedding intensity. The methodology may be used for identifying source terms for pathogen fate and transport modeling and for defining and targeting regions that are most vulnerable to water contamination from pathogenic sources.     

Influence of several methodological factors on the growth of Clostridium perfringens in cooling rate challenge studies

Proper temperature control is essential in preventing Clostridium perfringens food poisoning. The U.S. Department of Agriculture Food Safety and Inspection Service cooling guidelines offer two options for the cooling of meat products: follow a standard time-temperature schedule or validate that alternative cooling regimens result in no more than a 1-log CFU/g increase of C. perfringens and no growth of Clostridium botulinum. The latter option requires laboratory challenge studies to validate the efficacy of a given cooling process. Accordingly, the objective of this study was to investigate the role of several methodological variables that might be encountered during typical C. perfringens challenge studies. Variables studied included plastic bag type (Whirlpak or Spiral Biotech), sealing method (Multivac or FoodSaver), initial spore inoculum size (1 to approximately 3 log CFU/g), and growth environment (ground beef or Trypticase-peptone-glucose-yeast extract [TPGY] broth). The major factors that affected growth were sample bag type and growth environment. Samples incubated in Whirlpak bags showed significantly less growth than those incubated in Spiral Biotech bags, which was likely due to the former bag's greater oxygen permeability. C. perfringens spores showed shorter germination, outgrowth, and lag times and C. perfringens cells showed faster growth rates in ground beef compared with TPGY broth. No significant difference was observed between two different sealing methods. Initial spore inoculum levels in the range studied had no significant effect on final C. perfringens cell concentration.     

Fuzzy discrete event simulation: A new tool for rapid analysis of production systems under vague information

Information availability is often a critical point for the application of classical quantitative techniques for production system analysis. In several production problems, indeed, managers have considered the possibility to incorporate expert estimates of production data into a model as a substitute for hard data as very interesting. Furthermore, the use of qualitative representations to model physical systems is attractive because it allows to capture the inherent ambiguity characterizing real systems. Fuzzy set theory allows to gain such attractive options, since it provides tools to process vague information.This paper concerns the new and interesting topic of fuzzy discrete event simulation. In particular, the problem of processing fuzzy data within a discrete event simulation process is discussed and new methods, able to limit time paradox problems, are proposed. Furthermore, the paper addresses the comparison among fuzzy and classical simulation, pointing out peculiarities, potentialities and application fields of such a new tool; finally, the research highlights the necessity to develop proper and specific fuzzy simulation packages by demonstrating that, even under specific and simplifying hypotheses about process uncertainties, fuzzy simulation analysis results cannot be obtained through classical simulation packages.     

Neural basis of individual differences in impulsivity: Contributions of corticolimbic circuits for behavioral arousal and control.

The objective of the current study was to analyze the neural correlates of behavioral arousal and inhibitory control as they relate to individual differences in impulsivity via well-established functional MRI amygdala reactivity and prefrontal inhibitory control paradigms in healthy adult subjects. Impulsivity correlated positively with activity of the bilateral ventral amygdala, parahippocampal gyrus, dorsal anterior cingulate gyrus (BA 32), and bilateral caudate. Conversely, impulsivity correlated negatively with activity of the dorsal amygdala and ventral prefrontal cortex (BA 47). Together, these findings suggest that dispositional impulsivity is influenced by the functional interplay of corticolimbic behavioral arousal and control circuits. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Treatment techniques and outcomes in multidimensional family therapy for adolescent behavior problems.

The link between treatment techniques and long-term treatment outcome was examined in an empirically supported family-based treatment for adolescent drug abuse. Observational ratings of therapist interventions were used to predict outcomes at 6 and 12 months posttreatment for 63 families receiving multidimensional family therapy. Greater use of in-session family-focused techniques predicted reduction in internalizing symptoms and improvement in family cohesion. Greater use of family-focused techniques also predicted reduced externalizing symptoms and family conflict, but only when adolescent focus was also high. In addition, greater use of adolescent-focused techniques predicted improvement in family cohesion and family conflict. Results suggest that both individual and multiperson interventions can exert an influential role in family-based therapy for clinically referred adolescents. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Focused and shifting attention in children with heavy prenatal alcohol exposure.

Attention deficits are a hallmark of the teratogenic effects of alcohol. However, characterization of these deficits remains inconclusive. Children with heavy prenatal alcohol exposure and nonexposed controls were evaluated using a paradigm consisting of three conditions: visual focus, auditory focus, and auditory-visual shift of attention. For the focus conditions, participants responded manually to visual or auditory targets. For the shift condition, participants alternated responses between visual targets and auditory targets. For the visual focus condition, alcohol-exposed children had lower accuracy and slower reaction time for all intertarget intervals (ITIs), while on the auditory focus condition, alcohol-exposed children were less accurate but displayed slower reaction time only on the longest ITI. Finally, for the shift condition, the alcohol-exposed group was accurate but had slowed reaction times. These results indicate that children with heavy prenatal alcohol exposure have pervasive deficits in visual focused attention and deficits in maintaining auditory attention over time. However, no deficits were noted in the ability to disengage and reengage attention when required to shift attention between visual and auditory stimuli, although reaction times to shift were slower. (PsycINFO Database Record (c) 2010 APA, all rights reserved)