Resource pressure and environmental change on the North African littoral: Epipalaeolithic to Roman gastropods from Cyrenaica, Libya.

This paper discusses the marine and terrestrial shell on Epipalaeolithic to Classical-period sites in the Cyrenaican coastlands, northeast Libya, with particular reference to the Haua Fteah, with parallel studies at a late-Roman farmstead and two small caves. Together they provide evidence for coastal and terrestrial environments and for the continued nutritional importance of gastropods to humans during the Holocene. Land snail evidence is consistent with regional vegetation in coastal Cyrenaica becoming increasingly open through the Holocene, as a result of some combination of climate change and human impact. Marine species suggest that the coastline near the Haua had been rocky throughout the Holocene. At Hagfet al-Gama, changing faunas provide evidence for sand encroachment onto a previously rocky shoreline in Hellenistic times. A biometric study of Osilinus turbinatus shows that in the archaeological sites these shells are systematically smaller than modern specimens, providing evidence for long-term dietary stress in the human populations around the Haua Fteah, with particularly severe stress in parts of the Epipalaeolithic. A biometric study of Patella spp. provided evidence for size selection, but also seems to show evidence for resource pressure. It is unlikely that variations in resource pressure seen in the mollusc biometrics are the result of climatic stress or natural ecological factors and explanations must be sought in society-environment dynamics.

The Development of Entrepreneurial Leadership: The Role of Human, Social and Institutional Capital

This paper contributes to the literature on entrepreneurial leadership development. Leadership studies are characterized by an increasing emphasis given to an individual leader's social and organizational domain. Within the context of human capital and social capital theory, the paper reflects on the emergence of a social capital theory of leadership development. Using a retrospective, interpretivist research method, the authors present the experience of a cohort of business leaders on an executive development programme to uncover the everydayness of leadership development in practice. Specifically, they explore how entrepreneurial leadership develops as a social process and what the role of social capital is in this. The findings suggest that the enhancement of leaders’ human capital only occurred through their development of social capital. There is not, as extant literature suggests, a clear separation between leader development and leadership development. Further, the analysis implies that the social capital theory of leadership is limited in the context of the entrepreneurial small firm, and the authors propose that it should be expanded to incorporate institutional capital, that is, the formal structures and organizations which enhance the role of social capital and go beyond enriching the human capital stock of individual leaders

Cognitive Adaptation to the Experience of Social and Cultural Diversity

Diversity is a defining characteristic of modern society, yet there remains considerable debate over the benefits that it brings. The authors argue that positive psychological and behavioral outcomes will be observed only when social and cultural diversity is experienced in a way that challenges stereotypical expectations and that when this precondition is met, the experience has cognitive consequences that resonate across multiple domains. A model, rooted in social categorization theory and research, outlines the preconditions and processes through which people cognitively adapt to the experience of social and cultural diversity and the resulting cross-domain benefits that this brings. Evidence is drawn from a range of literatures to support this model, including work on biculturalism, minority influence, cognitive development, stereotype threat, work group productivity, creativity, and political ideology. The authors bring together a range of differing diversity experiences and explicitly draw parallels between programs of research that have focused on both perceiving others who are multicultural and being multicultural oneself. The findings from this integrative review suggest that experiencing diversity that challenges expectations may not only encourage greater tolerance but also have benefits beyond intergroup relations to varied aspects of psychological functioning.

Outer membrane differences between pathogenic and environmental Yersinia enterocolitica biogroups probed with hydrophobic permeants and polycationic peptides

Sensitivities to polycationic peptides and EDTA were compared in Yersinia enterocolitica pathogenic and environmental biogroups. As shown by changes in permeability to the fluorescent hydrophobic probe N-phenylnaphthylamine (NPN), the outer membranes (OMs) of pathogenic and environmental strains grown at 26 degrees C in standard broth were more resistant to poly-L-lysine, poly-L-ornithine, melittin, cecropin P1, polymyxin B, and EDTA than Escherichia coli OMs. At 37 degrees C, OMs of pathogenic biogroups were resistant to EDTA and polycations and OMs of environmental strains were resistant to EDTA whereas E. coli OMs were sensitive to both EDTA and polycations. Similar results were found when testing deoxycholate sensitivity after polycation exposure or when isogenic pairs with or without virulence plasmid pYV were compared. With bacteria grown without Ca++ available, OM permeability to NPN was drastically increased in pathogenic but not in environmental strains or E. coli. Under these conditions, OMs of pYV+ and pYV- cells showed small differences in NPN permeability but differences in polycation sensitivity could not be detected by fluorimetry. O:1,6 (environmental type) lipopolysaccharide (LPS), but not O:3 or O:8 LPS, was markedly rough at 37 degrees C, and this could explain the differences in polycation sensitivity. LPSs from serotypes O:3 and O:8 grown at 37 degrees C were more permeable to NPN than O:1,6 LPS, and O:8 LPS was resistant to polycation-induced permeabilization. These data suggest that LPSs relate to some but not all the OM differences described. It is hypothesized that the different OM properties of environmental and pathogenic biogroups reflect the adaptation of the latter biogroups to pathogenicity.