Addiction Motivation Reformulated: An Affective Processing Model of Negative Reinforcement.

This article offers a reformulation of the negative reinforcement model of drug addiction and proposes that the escape and avoidance of negative affect is the prepotent motive for addictive drug use. The authors posit that negative affect is the motivational core of the withdrawal syndrome and argue that, through repeated cycles of drug use and withdrawal, addicted organisms learn to detect interoceptive cues of negative affect preconsciously. Thus, the motivational basis of much drug use is opaque and tends not to reflect cognitive control. When either stressors or abstinence causes negative affect to grow and enter consciousness, increasing negative affect biases information processing in ways that promote renewed drug administration. After explicating their model, the authors address previous critiques of negative reinforcement models in light of their reformulation and review predictions generated by their model. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Facteurs reliés au choix de la partenaire qui portera l'enfant chez de futures mères lesbiennes.

This study looks at factors associated to the choice of the surrogate mother in lesbian couples who want to have a child through insemination. Fifty same-sex partners (25 couples) have completed questionnaires evaluating various individual, marital, parental and social aspects associated to parenthood. Variance analysis of theses aspects have shown the effects of two factors that is, the type of mother (biological/non-biological) and the procreation mode (known/unknown genitor). Results show that the future biological mothers are older than their partner, pay less importance to their professional role and intend to ensure a greater number of parental tasks. Also, couples who use a known genitor face higher psychological distress than couples who choose an anonymous genitor. This study suggests that the choice of the partner who will bear the child in lesbian couples could be determined by factors predisposing them to adopt special parental roles and invest themselves differently in a child. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Synthesis and structure of CsTi5Te8: Relation to the TlV5S8, TlCr3S5, and similar channel structures

The compound CsTi₅Te₈ was obtained as a crystalline product by an “U-assisted” reaction of Cs, Ti, U, and Cs₂Te₃ in a CsCl flux at 1173 K. The structure of CsTi₅Te₈ contains a three-dimensional network of face-sharing and edge-sharing TiTe₆ octahedra that form one-dimensional channels. The Cs⁺ cations reside in channels that propagate in the [0 1 0] direction. The structure is closely related to several other types of channel structures including those of the minerals of the hollandite and psilomelane families, and those of the TlV₅S₈ and TlCr₃S₅ structure types.     

Compensatory nicotine self-administration in rats during reduced access to nicotine: An animal model of smoking reduction.

The ability of smoking reduction (e.g., decreasing cigarettes per day) to produce significant reductions in toxin exposure is limited by compensatory increases in smoking behavior. Characterizing factors contributing to the marked individual variability in compensation may be useful for understanding this phenomenon. The goal of the current study was to develop an animal model of smoking reduction and to begin to examine potential behavioral and pharmacokinetic contributors to compensation. Rats trained for nicotine self-administration (NSA) in unlimited access sessions were exposed to a progressive decrease in duration of access to nicotine from 23-hr/day to 10-, 6-, and 2-hr/day. Following a return to 23 hr/day access and extinction, single-dose nicotine pharmacokinetic parameters were determined. Rats exhibited a reduction in total daily nicotine intake during reduced access to NSA, but decreases in nicotine intake were not proportional to decreases in access duration. Compensatory increases in hourly infusion rate were also observed when access was decreased. The magnitude of compensation differed considerably among animals. Early session infusion rate during baseline was significantly correlated, while nicotine clearance was moderately correlated, with 1 measure of compensation. Infusion rates were transiently increased compared to prereduction levels when unlimited access was restored, and this effect was greatest in animals that had exhibited the greatest levels of compensation. These findings indicate that rats exhibit compensatory increases in NSA during reduced access to nicotine, with substantial individual variability. This model may be useful for characterizing underlying factors and potential consequences of compensatory smoking. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Physical activity and cognitive function in a cross-section of younger and older community-dwelling individuals.

Previous reports have indicated a small, positive relationship between physical activity and cognition. However, the majority of research has focused on older adults, with few studies examining this relationship during earlier periods of the life span. This study examined the relationship of physical activity to cognition in a cross-section of 241 community-dwelling individuals 15-71 years of age with a task requiring variable amounts of executive control. Data were analyzed with multiple regression, which controlled for age, sex, and IQ. Participants reported their physical activity behavior and were tested for reaction time (RT) and response accuracy on congruent and incongruent conditions of a flanker task, which manipulates interference control. After controlling for confounding variables, an age-related slowing of RT was observed during both congruent and incongruent flanker conditions. However, physical activity was associated with faster RT during these conditions, regardless of age. Response accuracy findings indicated that increased physical activity was associated with better performance only during the incongruent condition for the older cohort. Findings suggest that physical activity may be beneficial to both general and selective aspects of cognition, particularly among older adults. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Anticorrosive Influence of <Emphasis Type="Italic">Acetobacter aceti</Emphasis> Biofilms on Carbon Steel

Microbiologically influenced corrosion (MIC) of carbon steel infrastructure is an emerging environmental and cost issue for the ethanol fuel industry, yet its examination lacks rigorous quantification of microbiological parameters that could reveal effective intervention strategies. To quantitatively characterize the effect of cell concentration on MIC of carbon steel, numbers of bacteria exposed to test coupons were systematically controlled to span four orders of magnitude throughout a seven-day test. The bacterium studied, Acetobacter aceti, has been found in ethanol fuel environments and can convert ethanol to the corrosive species acetic acid. A. aceti biofilms formed during the test were qualitatively evaluated with fluorescence microscopy, and steel surfaces were characterized by scanning electron microscopy. During exposure, biofilms developed more quickly, and test reactor pH decreased at a faster rate, when cell exposure was higher. Resulting corrosion rates, however, were inversely proportional to cell exposure, indicating that A. aceti biofilms are able to protect carbon steel surfaces from corrosion. This is a novel demonstration of corrosion inhibition by an acid-producing bacterium that occurs naturally in corrosive environments. Mitigation techniques for MIC that harness the power of microbial communities have the potential to be scalable, inexpensive, and green solutions to industrial problems.     

High‐temperature structural stability of ceria‐based inverse opals

The use of ceria‐based inverse opals as a catalyst system for the thermochemical production of fuels from sunlight offers the potential of improved fuel production kinetics over materials with random porosity. Quantitative methods for characterizing ordered porosity are lacking, thus limiting the ability to predict the lifetime of ordered structures at elevated temperatures. In the present work, Fourier transform image analysis was used to determine the effect of composition and temperature on ordered porosity for a series of CeO₂‐ZrO₂ inverse opals having pore sizes ranging from 300 nm to 1 μm. An order parameter, γ, derived from the image analysis, was applied to scanning electron microscopy images and used to determine the degree of order in the inverse opal. The thermal stability studies indicate that loss of ordered porosity is highly dependent on temperature and that gas cycling effects have a minor effect on periodicity. A minimum Zr content of 20 at.% is necessary to retain periodicity for annealing up to 1000°C with pore diameters larger than 1 μm. These results show that CeO₂‐ZrO₂ inverse opals can be used at higher temperatures than previously thought for efficient thermochemical hydrogen production without loss of the benefits associated with ordered porosity.     

Organisational motives and spatial effects in Internet adoption and intensity of use: evidence from French industrial firms

The aim of this study is to examine the reasons why firms use ICTs at varying rates, by making a distinction between the two stages of their diffusion: their adoption and the intensity of their use. What are the differences between Internet adopters (in terms of their internal organization and external environment) that explain the intensity with which they use this technology? Furthermore, do these processes vary according to the type of area in which firms are located (urban vs. rural)? A model of technological diffusion is constructed that merges two types of models: those that concentrate on epidemic effects and the so-called equilibrium models that consider the decision to adopt new technologies as a result of an economic calculation by firms. To test this model, we use data drawn from a recent French national survey of 5,200 industrial firms (“ICT and E-commerce”, 2002). One striking result of this study is that we do not obtain a significant positive correlation between firm’s size and Internet intensity of use. Moreover, though spatial disparities related to ICT adoption are no longer significant in France, they remain very important in the processes of ICT appropriation and use by firms. The results also indicate that the determinants of the intensity of Internet use vary significantly according to the firms’ location: epidemics effects play an essential role in the case of urban the firms, while rank effects are essential in low density areas.     

Immobilization of commercial hydrolytic enzymes on poly (acrylonitrile) nanofibers for anti‐biofilm activity

BACKGROUND: Chemical methods used to control biofilm formation in filtration systems are not always effective. Two commercially available proteases and an amylase were immobilized onto polymer nanofibers that are used in the production of filtration membranes. RESULTS: The enzymes were immobilized onto poly acrylonitrile nanofibers that were chemically activated by imidoesterification to allow the covalent immobilization of enzymes. The immobilized enzymes retained above 80% of the specific activity of the free enzymes. For each of the immobilized enzymes, just below 30% of initial activity was retained after 10 repeated cycles of use. No biofilm formation was observed on nanofibers that were coated with the enzymes, where biofilms formed on non‐coated nanofibers. CONCLUSION: When considering the combined advantages of this effective immobilization process, the robustness of the enzymes used in this study, and the results of this study indicating activity against biofilms, a valuable addition has been made to filtration membrane technology. © 2012 Society of Chemical Industry