The dopaminergic system, and in particular the dopamine D2 receptor, has been profoundly implicated in reward mechanisms in the brain. Dysfunction of the D2 dopamine receptors leads to aberrant substance seeking behaviour (alcohol, drug, tobacco, and food) and other related behaviours (pathological gambling, Tourette's syndrome, and attention deficit hyperactivity disorder). We propose that variants of the D2 dopamine receptor gene are important common genetic determinants of the 'reward deficiency syndrome'.

This paper empirically explores the relations between alternative organizational designs and a firm's ability to explore as well as exploit. We operationalize exploitation and exploration in terms of innovation streams; incremental innovation in existing products as well as exploring into architectural and/or discontinuous innovation. Based on in-depth, longitudinal data on 13 business units and 22 innovations, we investigate the consequences of organization design choices on innovation outcomes as well as the ongoing performance of existing products. We find that ambidextrous organization designs are significantly more effective in executing innovation streams than functional, cross-functional, and spinout designs. Further, transitions to ambidextrous designs were associated with significantly increased innovation outcomes, while shifts away from ambidextrous designs were associated with decreases in innovation outcomes. We explore the nature of ambidextrous organizational designs-their characteristics, how they operate, and their boundary conditions. Given these results, we discuss the relations between streams of innovation, organizations designs, and the nature of organizational adaptation.

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The nonhuman primate (Nhp) has proven to be a useful model of human periodontitis. This study describes the immunological characteristics of this model and the ability of active immunization to interfere with ecological changes in the microbiota and its associated disease symptoms. Nhps were parenterally immunized with whole-cell antigens of Porphyromonas gingivalis and Prevotella intermedia. The immunization elicited an approximate 2-log increase in serum immunoglobulin G (IgG), IgM, and IgA isotype antibody that was highly specific for these immunogens. Postimmunization and postligation, there was minimal change in the levels of specific antibody. P. gingivalis immunization significantly inhibited the emergence of this species during disease progression. In contrast, induction of anti-P. intermedia antibody had a minimal effect on this species within the subgingival plaque. Plaque indices showed few changes that could be attributed to active immunization. Both bleeding on probing and loss of attachment were higher in ligated sites of immunized animals than in the placebo-treated group. A signfficant increase in bone density loss was observed in the ligated teeth from immunized versus control animals. These findings indicate that active immunization of Nhps can elicit a substantial systemic immune response; however, while this response may effect the emergence of an individual microorganism, it appears that other ecological considerations are critical in disease progression. It is also possible that the induction of a broad-based immune response to multiple bacterial antigens can result in increased disease, potentially associated with hypersensitivity reactions to the bacteria in the subgingival plaque.

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Social support is critical for women in abusive relationships. While social support may decrease the risk of getting into a violent relationship, it can also allow battered women to remain in violent relationships by reducing the negative impact of intimate partner violence (IPV). In addition to the social isolation that women in abusive relationships may experience, her social contacts appear to be important. The purpose of this study was to compare the size, structure, and composition of the social networks of women in abusive relationships with those of a matched cohort of nonabused women. The authors enrolled women from primary care clinics who reported abuse within the prior month, and a demographically matched comparison group of women in nonabusive relationships. Participants completed a social network analysis, and investigators compared social networks of abused with nonabused women. The networks of women in abusive relationships were smaller in size, but more efficient in their ability to reach their members, than those of nonabused women. Proportionally, networks of abused women had more women but fewer in-laws than those of comparison women. The women in these abusive relationships had higher measures of centrality, suggesting that they were more critical in holding their networks together. Yet, they had fewer social contacts, and provided more support than they received with fewer reciprocated ties. Thus, social networks of women in violent relationships are small and offer less support than those of comparison women. However, previous work on networks with weak ties and structural holes suggests that access to resources may be available through these networks.

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