Dehydroepiandrosterone sulfate (DHEAS) is neuroprotective when administered either before or after injury in a focal cortical cold lesion model

Dehydroepiandrosterone and its sulfate (DHEAS) are sex hormone precursors that exert marked neurotrophic and/or neuroprotective activity in the central nervous system. The present study evaluated the effects of DHEAS and 17�-estradiol (E2) in a focal cortical cold lesion model, in which DHEAS (50 mg/kg, sc) and E2 (35 mg/kg, sc) were administered either as pretreatment (two subsequent injections 1 d and 1 h before lesion induction) or posttreatment (immediately after lesion induction). The focal cortical cold lesion was induced in the primary motor cortex by means of a cooled copper cylinder placed directly onto the cortical surface. One hour later, the animals were killed, the brains cut into 0.4-mm-thick slices, and the sections stained with 1% triphenyltetrazolium chloride. The volume of the hemispheric lesion was calculated for each animal. The results demonstrated that the lesion area was significantly attenuated in both the DHEAS- and E2- preand posttreated groups and that in the presence of letrozole, a nonsteroidal aromatase inhibitor, no neuroprotection was observed, suggesting that the beneficial effect of DHEAS on the cold injury might depend on the conversion of DHEAS to E2 within the brain. It is concluded that even a single posttraumatic administration of DHEAS may be of substantial therapeutic benefit in the treatment of focal brain injury with vasogenic edema

Social Cohesion, Structural Holes, and a Tale of Two Measures

EMBARGOED - author can archive pre-print or post-print on any open access repository after 12 months from publication. Publication date is May 2013 so embargoed until May 2014.This is an author’s accepted manuscript (deposited at arXiv arXiv:1211.0719v2 [physics.soc-ph] ), which was subsequently published in Journal of Statistical Physics May 2013, Volume 151, Issue 3-4, pp 745-764. The final publication is available at link.springer.com http://link.springer.com/article/10.1007/s10955-013-0722-

Entrepreneurial sons, patriarchy and the Colonels' experiment in Thessaly, rural Greece

Existing studies within the field of institutional entrepreneurship explore how entrepreneurs influence change in economic institutions. This paper turns the attention of scholarly inquiry on the antecedents of deinstitutionalization and more specifically, the influence of entrepreneurship in shaping social institutions such as patriarchy. The paper draws from the findings of ethnographic work in two Greek lowland village communities during the military Dictatorship (1967–1974). Paradoxically this era associated with the spread of mechanization, cheap credit, revaluation of labour and clear means-ends relations, signalled entrepreneurial sons’ individuated dissent and activism who were now able to question the Patriarch’s authority, recognize opportunities and act as unintentional agents of deinstitutionalization. A ‘different’ model of institutional change is presented here, where politics intersects with entrepreneurs, in changing social institutions. This model discusses the external drivers of institutional atrophy and how handling dissensus (and its varieties over historical time) is instrumental in enabling institutional entrepreneurship

Escaping Network Gravity: Relational Structures for Generating Novelty

While there is a long tradition in social networks research about the spread and adoption of innovation, we know much less about the network antecedents of the generation of novel ideas. In his lecture, Vedres argues that the main mechanisms governing social tie formation and operation are at odds with recognizing new ideas. Homophily, closure, skewed degree distributions, and limited vision are four main mechanisms that are conservatizing – the four main forces of network gravity. In his lecture Vedres will highlight cases where some of these gravity forces were overcome by organizational design and emergent institutions. Drawing on qualitative and quantitative sources on startup company formation, video game projects, jazz sessions, and business groups, he will focus especially on the role of structural folds and the significance of generative tension in innovation

Forbidden triads and creative success in jazz: the Miles Davis factor

This article argues for the importance of forbidden triads – open triads with high-weight edges – in predicting success in creative fields. Forbidden triads had been treated as a residual category beyond closed and open triads, yet I argue that these structures provide opportunities to combine socially evolved styles in new ways. Using data on the entire history of recorded jazz from 1896 to 2010, I show that observed collaborations have tolerated the openness of high weight triads more than expected, observed jazz sessions had more forbidden triads than expected, and the density of forbidden triads contributed to the success of recording sessions, measured by the number of record releases of session material. The article also shows that the sessions of Miles Davis had received an especially high boost from forbidden triads

Gendered behavior as a disadvantage in open source software development

Women are severely marginalized in software development, especially in open source. In this article we argue that disadvantage is more due to gendered behavior than to categorical discrimination: women are at a disadvantage because of what they do, rather than because of who they are. Using data on entire careers of users from GitHub.com, we develop a measure to capture the gendered pattern of behavior: We use a random forest prediction of being female (as opposed to being male) by behavioral choices in the level of activity, specialization in programming languages, and choice of partners. We test differences in success and survival along both categorical gender and the gendered pattern of behavior. We find that 84.5% of women’s disadvantage (compared to men) in success and 34.8% of their disadvantage in survival are due to the female pattern of their behavior. Men are also disadvantaged along their interquartile range of the female pattern of their behavior, and users who don’t reveal their gender suffer an even more drastic disadvantage in survival probability. Moreover, we do not see evidence for any reduction of these inequalities in time. Our findings are robust to noise in gender recognition, and to taking into account particular programming languages, or decision tree classes of gendered behavior. Our results suggest that fighting categorical gender discrimination will have a limited impact on gender inequalities in open source software development, and that gender hiding is not a viable strategy for women

Disembedded openness: Inequalities in European economic integration at the sectoral level

The process of European integration resulted in a marked increase in transnational economic flows, yet regional inequalities along many developmental indicators remain. We analyze the unevenness of European economies with respect to the embedding of export sectors in upstream domestic flows and their dependency on dominant export partners. We use the WIOD dataset of sectoral flows for the period of 1995–2011 for 24 European countries. We found that East European economies were significantly more likely to experience increasing unevenness and dependency with increasing openness, while core countries of Europe managed to decrease their unevenness but increased their openness. Nevertheless, by analyzing the trajectories of changes for each country, we see that East European countries are also experiencing a turning point, either switching to a path similar to the core or to a retrograde path with decreasing openness. We analyze our data using pooled time series models and case studies of country trajectories

Social Times of Network Spaces: Network Sequences and Foreign Investment in Hungary

To model, from its inception, interenterprise network formation and its interaction with foreign investment across an entire epoch of rapid and profound economic transformation, the authors gathered data on the complete ownership histories of 1,696 of the largest Hungarian enterprises from 1987 to 2001. They develop a social sequence analysis to identify distinctive pathways whereby firms use network resources to buffer uncertainty, hide or restructure assets, or gain knowledge and legitimacy. During this period, networked property grew, stabilized, and involved a growing proportion of foreign capital. Cohesive networks of recombinant property were robust, and in fact integrated foreign investment. Although multinationals, through their subsidiaries, dissolved ties in joint venture arrangements, the authors find evidence that they also built durable networks. These findings suggest that developing economies do not necessarily face a forced choice between networks of global reach and those of local embeddedness. Social structures often are made to seem the antipodes to, or at least unrelated to details and nuances of, sequencing in timing. This is in part because of the influence of structuralism. Social times should instead be accounted as much part of structure as are network spaces.—Harrison White (1992) Business organizations today must cope with the challenges of a transforming global economy. Markets are volatile, technological change is rapid, and capital is mobile on an increasingly global scale. In settings o

Opening Closure: Intercohesion and Entrepreneurial Dynamics in Business Groups

Entrepreneurial groups face a twinned challenge: recognizing new ideas and implementing them. Recent research suggests that connectivity reaching outside the group channels new ideas, while closure makes it possible to act on them. By contrast, we argue that entrepreneurship is not about importing ideas but about generating new knowledge by recombining resources. In contrast to the brokerage-plus-closure perspective, we identify a distinctive network position, intercohesion, which is found at the overlap of cohesive group structures. The multiple insiders at this intercohesive position participate in dense cohesive ties that provide close familiarity with the operations of the members in their groups. Because they are members of multiple cohesive groups, they have familiar access to diverse resources. First, we test whether intercohesion contributes to higher group performance. Second, because entrepreneurship is a process of creative disruption, we test intercohesion’s contribution to group instability. Third, we move from dynamic methods to historical network analysis and demonstrate that coherence is a property of interwoven lineages of cohesion that are built up through an ongoing pattern of separation and reunification. Business groups use this pattern of interweaving to manage instability while benefitting from intercohesion. To study the evolution of business groups, we construct a dataset that records personnel ties among the largest 1,696 Hungarian enterprises from 1987–2001.Unternehmerisch tätige Gruppen stehen vor zwei Herausforderungen: neue Ideen zu erkennen und sie zu implementieren. Jüngste Forschungsergebnisse unterstellen, dass Konnektivität, die über eine Gruppe hinausreicht, ihr neue Ideen zuführt, während Geschlossenheit der Gruppe ermöglicht, diese Ideen umzusetzen. Demgegenüber argumentieren wir, dass Unternehmertum nichts mit dem Import von Ideen zu tun hat, sondern damit, neues Wissen zu generieren, indem vorhandene Ressourcen neu kombiniert werden. Dabei identifizieren wir eine konkrete Netzwerkposition, die wir als "Intercohesion" bezeichnen. Inhaber einer solchen interkohäsiven Position sind "Mehrfach-Insider": Sie partizipieren an festen kohäsiven Beziehungen, durch die sie mit dem Handeln der Mitglieder ihrer Gruppen eng vertraut sind. Als Mitglieder mehrerer kohäsiver Gruppen haben sie mühelosen Zugang zu einer Vielfalt von Ressourcen. Zunächst untersuchen wir, ob Interkohäsion zu einer höheren Gruppenleistung beiträgt. In einem zweiten Schritt testen wir den Beitrag der Interkohäsion zur Instabilität von Gruppen, da Unternehmertum ein Prozess der kreativen Unterbrechung eingefahrener Abläufe und Strukturen ist. In einem dritten Schritt wenden wir uns von dem dynamischen Fokus hin zur Perspektive einer historischen Netzwerkanalyse und zeigen, dass Kohärenz eine Eigenschaft der miteinander verwobenen Abstammungslinien ist, die durch ein sich wiederholendes Muster von Trennung und Wiedervereinigung entstehen. Unternehmerisch tätige Gruppen verwenden dieses Muster, um Instabilität zu managen und dabei die Vorteile der Interkohäsion zu nutzen. Zur Untersuchung der Entwicklung unternehmerisch tätiger Gruppen bauen wir einen Datensatz auf, der über den Zeitraum von 1987 bis 2001 die Beziehungen zwischen den Führungskräften der größten 1.696 ungarischen Unternehmen abbildet.Network structures for access and action Intercohesion Instability and coherence Data and Methods Data Identifying cohesive groups with the "clique percolation method" Group performance Intercohesion and group stability Recombinant lineages of cohesion Conclusion Appendix: The "clique percolation method