Impaired timing precision produced by striatal D2 receptor overexpression is mediated by cognitive and motivational deficits.

Increased striatal dopamine D2 receptor activity is thought to contribute to the pathophysiology of schizophrenia. To model this condition in mice, Kellendonk et al. (2006) generated transgenic mice that selectively overexpress the D2 receptor in striatum (D2OE). Drew et al. (2007) reported that D2OE mice display deficits in interval timing and motivation. The present study further explored the impaired timing in D2OE mice. Experiment 1 assessed the role of motivation in producing timing deficits in the peak procedure and found that performance in D2OE mice was improved by increasing motivation. In addition, performance was impaired in control mice when motivation was decreased. In Experiment 2, we found that D2OE mice have no timing impairment when tested using the bisection task, a procedure in which the measure of timing performance is less influenced by motivation to respond. In Experiment 3, we also used the bisection task and found selective impairment in timing of long durations in D2OE mice. These results suggest that striatal D2 overexpression impairs timing by decreasing motivation and through its impact on working memory and/or sustained attention. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of parents in the socialization of children: An historical overview.

The history of research on childhood socialization in the context of the family is traced through the present century. The 2 major early theories (behaviorism and psychoanalytic theory) are described. These theories declined in mid-century, under the impact of failures to find empirical support. Simple reinforcement theory was seriously weakened by work on developmental psycholinguistics, attachment, modeling, and altruism. The field turned to more domain-specific mini-theories. The advent of microanalytic analyses of parent–child interaction focused attention on bidirectional processes. Views about the nature of identification and its role in socialization underwent profound change. The role of "parent as teacher" was reconceptualized (with strong influence from Vygotskian thinking). There has been increasing emphasis on the role of emotions and mutual cognitions in establishing the meaning of parent–child exchanges. The enormous asymmetry in power and competence between adults and children implies that the parent–child relationship must have a unique role in childhood socialization. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Thermal behaviour of partially neutralised ethylene-maleic acid copolymer

As part of continuing studies on the cure of candidate polymers for waterborne coatings, the thermal behaviour of partially neutralised ethylene-maleic acid copolymer, EMA, has been examined. Films of EMA neutralised with a variety of bases were heated at 250°C. For this copolymer, as for poly(acrylic acid) at the same temperature, reflectance infrared spectroscopy has shown that heating led initially to anhydride formation. In the unneutralised state, or with the divalent ions calcium, magnesium, cobalt or zinc, further heating led to little or no further reaction. By contrast, the presence of univalent metal ions lithium, sodium and potassium caused a second reaction to occur, namely decarboxylation to yield keto crosslinks. This second reaction, however, did not occur to the extent that it does with poly(acrylic acid) under identical conditions. Possible reasons for this are discussed. Unlike poly(acrylic acid), EMA when partially neutralised was found not to form continuous films on the tin-plate substrate.     

The influence of polymer morphology on the performance of molecularly imprinted polymers

This is the first in-depth study examining the effect of morphology on the performance of 2-aminopyridine (2-apy) imprinted polymers. A series of polymers were prepared by varying the amount of crosslinking monomer (EGDMA) whilst the other polymer components remained constant. Physical characterisation was carried out using conventional techniques, such as nitrogen sorption porosimetry and solvent swelling studies. The use of a novel thermal desorption GC-MS technique suggested higher levels of polymer degradation with prolonged exposure to elevated temperatures for those polymers formed with lower amounts of EGDMA. The thermal desorption GC-MS profiles obtained correlated with the physical characteristics of the polymers, where higher levels of polymer bleed was found to occur with larger average pore diameters. Polymer physical characteristics were also found to correlate with the binding parameters (number of binding sites and polymer-template association energy) obtained from the Langmuir-Freundlich Isotherm (L-FI) and affinity distribution spectra (AD). The flexibility of the polymers formed from lower amounts of EGDMA combined the swelling effect of the solvents on the polymers resulted in an increase in affinity, which was both specific and non-specific in nature.     

Design,construction and performance of a portable handheld electrohydrodynamic multi-needle spray gun for biomedical applications

Electrohydrodynamic (EHD) processing has attracted substantial interest in the technological and pharmaceutical sectors in recent years. Given the complexity of the process, exploring new ideas for EHD electrospraying and electrospinning delivery is a challenge. In this article, the design, construction and testing of a portable handheld EHD multi-needle device are described to produce multifunctional particles and fibers. Solid and encapsulated polymer particles and fibers were generated in order to study the performance of the device. The intrinsic properties of the feed solution/suspension and the processing conditions were adjusted to ensure robustness of the process and give uniform and reproducible products, with diameters ranging from the sub-micrometer scale to a few micrometers. These products have a broad range of applications in many advanced industrial sectors e.g. drug delivery systems, wound dressing patches, low calorie food products and cosmetics.     

Age differences in saccadic averaging.

Younger and older adults were asked to saccade to an orientation-defined target that was presented alone, with a more central distractor, or with a more peripheral distractor. Both age groups exhibited saccadic averaging that was more pronounced in the central distractor condition, wherein older adults had the larger effect. These results are relevant to questions of oculomotor control and also have implications for the study of age differences in other visually guided behaviors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Gender and relationships: A developmental account.

This article argues that behavioral differentiation of the sexes is minimal when children are observed or tested individually. Sex differences emerge primarily in social situations, and their nature varies with the gender composition of dyads and groups. Children find same-sex play partners more compatible, and they segregate themselves into same-sex groups, in which distinctive interaction styles emerge. These styles are described. As children move into adolescence, the patterns they developed in their childhood same-sex groups are carried over into cross-sex encounters in which girls' styles put them at a disadvantage. Patterns of mutual influence can become more symmetrical in intimate male–female dyads, but the distinctive styles of the two sexes can still be seen in such dyads and are subsequently manifested in the roles and relationships of parenthood. The implications of these continuities are considered. (PsycINFO Database Record (c) 2010 APA, all rights reserved)