Instabilities in the wake of an inclined prolate spheroid

We investigate the instabilities, bifurcations and transition in the wake behind a 45-degree inclined 6:1 prolate spheroid, through a series of direct numerical simulations (DNS) over a wide range of Reynolds numbers (Re) from 10 to 3000. We provide a detailed picture of how the originally symmetric and steady laminar wake at low Re gradually looses its symmetry and turns unsteady as Re is gradually increased. Several fascinating flow features have first been revealed and subsequently analysed, e.g. an asymmetric time-averaged flow field, a surprisingly strong side force etc. As the wake partially becomes turbulent, we investigate a dominating coherent wake structure, namely a helical vortex tube, inside of which a helical symmetry alteration scenario was recovered in the intermediate wake, together with self-similarity in the far wake.Comment: Book chapter in "Computational Modeling of Bifurcations and Instabilities in Fluid Dynamics (A. Gelfgat ed.)", Springe

Rab protein evolution and the history of the eukaryotic endomembrane system

Spectacular increases in the quantity of sequence data genome have facilitated major advances in eukaryotic comparative genomics. By exploiting homology with classical model organisms, this makes possible predictions of pathways and cellular functions currently impossible to address in intractable organisms. Echoing realization that core metabolic processes were established very early following evolution of life on earth, it is now emerging that many eukaryotic cellular features, including the endomembrane system, are ancient and organized around near-universal principles. Rab proteins are key mediators of vesicle transport and specificity, and via the presence of multiple paralogues, alterations in interaction specificity and modification of pathways, contribute greatly to the evolution of complexity of membrane transport. Understanding system-level contributions of Rab proteins to evolutionary history provides insight into the multiple processes sculpting cellular transport pathways and the exciting challenges that we face in delving further into the origins of membrane trafficking specificity

Ritual plants of Muslim graveyards in northern Israel

This article surveys the botanical composition of 40 Muslim graveyards in northern Israel, accompanied by an ethnobotanical study of the folkloristic traditions of the use of these plants in cemeteries. Three groups of plants were found to be repeated systematically and were also recognized for their ritual importance: aromatics herbs (especially Salvia fruticosa and Rosmarinus officinalis), white flowered plants (mainly Narcissus tazetta, Urginea maritima, Iris spp. and Pancratium spp.) and Cupressus sempervirens as the leading cemetery tree. As endemic use we can indicate the essential role of S. fruticosa as the main plant used in all human rites of passage symbolizing the human life cycle. The rosemary is of European origin while the use of basil is of Indian influence. The use of white flowers as cemeteries plants reflects an old European influence and almost the same species are used or their congeners. Most of the trees and shrubs that are planted in Muslim cemeteries in Israel have the same use in ancient as well in modern European cultures. In conclusion, our findings on the occurrence of plants in graveyards reflect the geographic situation of Israel as a crossroads in the cultural arena between Asia and Europe. Most of the traditions are common to the whole Middle East showing high relatedness to the classical world as well as to the present-day Europe

Nothing Lasts Forever: Environmental Discourses on the Collapse of Past Societies

The study of the collapse of past societies raises many questions for the theory and practice of archaeology. Interest in collapse extends as well into the natural sciences and environmental and sustainability policy. Despite a range of approaches to collapse, the predominant paradigm is environmental collapse, which I argue obscures recognition of the dynamic role of social processes that lie at the heart of human communities. These environmental discourses, together with confusion over terminology and the concepts of collapse, have created widespread aporia about collapse and resulted in the creation of mixed messages about complex historical and social processes

Digital Food and foodways. How online food practices and narratives shape the Italian diaspora

The article discusses the role of online food practices and narratives in the formation of transnational identities and communities. Data has been collected in the framework of a doctoral research project undertaken by the author between 2009 and 2012 with a follow-up in 2014. The working hypothesis of this article is that the way Italians talk about food online and offline, the importance they give to ‘authentic’ food, and the way they share their love for Italian food with other members of the same diaspora reveal original insights into migrants’ personal and collective identities, their sense of belonging to the transnational community and processes of adjustment to a new place. Findings suggest that online culinary narratives and practices shape the Italian diaspora in unique ways, through the development of forms of virtual commensality and online mealtime socialization on Skype and by affecting intra and out-group relationships, thus working as elements of cultural identification and differentiation

Document collections, mobilized regulations, and the making of customary law at the end of the Middle Ages

Using late medieval examples from Switzerland, this paper argues that the emergence of formally organized archives around 1500 was part of an important shift in how documents could be deployed. However, this shift was not away from an oral and toward a literate culture, as argued in some earlier studies, but rather away from seeing documents as testimony that reminded a community about past authoritative actors, and toward relating the texts of documents to other texts, that is, to contexts. This shift took place largely through the appropriation of methods for using and organizing written material that had been developed in the realms of scholastic theology and liturgy, and applying them to secular lordship and administration. These methods provided new models for organizing collections of parchments and papers into connected archives and gave rise to new forms of text collection such as reorganized versions of law books (Spiegel, Coutumiers) containing new search tools such as tables of contents (capitulationes) and indices (abecedaria). Individual charters and scattered legal norms were also organized into textus–glossae structures in larger and smaller administrative units. In the Swiss case, the contextualization of legal texts was accompanied by an increased attribution of authority to ‘custom’ in general, because the community-oriented attribution of meaning found in earlier use was lost. Ultimately, recasting individual documents as part of larger textual contexts increased the power of rulers and ushered in an age of lawyers and of archives