Threading the spindle: a geometric study of chiral liquid crystal polymer microparticles

Polymeric particles are strong candidates for designing artificial materials capable of emulating the complex twisting-based functionality observed in biological systems. In this letter, we provide the first detailed investigation of the swelling behavior of bipolar polymer liquid crystalline microparticles. Deswelling from the spherical bipolar configuration causes the microparticle to contract anisotropically and twist in the process, resulting in a twisted spindle shaped structure. We propose a model to describe the observed spiral patterns and twisting behavior

Childhood and the politics of scale: Descaling children's geographies?

This is the post-print version of the final published paper that is available from the link below. Copyright @ 2008 SAGE Publications.The past decade has witnessed a resurgence of interest in the geographies of children's lives, and particularly in engaging the voices and activities of young people in geographical research. Much of this growing body of scholarship is characterized by a very parochial locus of interest — the neighbourhood, playground, shopping mall or journey to school. In this paper I explore some of the roots of children's geographies' preoccupation with the micro-scale and argue that it limits the relevance of research, both politically and to other areas of geography. In order to widen the scope of children's geographies, some scholars have engaged with developments in the theorization of scale. I present these arguments but also point to their limitations. As an alternative, I propose that the notion of a flat ontology might help overcome some difficulties around scalar thinking, and provide a useful means of conceptualizing sociospatiality in material and non-hierarchical terms. Bringing together flat ontology and work in children's geographies on embodied subjectivity, I argue that it is important to examine the nature and limits of children's spaces of perception and action. While these spaces are not simply `local', they seldom afford children opportunities to comment on, or intervene in, the events, processes and decisions that shape their own lives. The implications for the substance and method of children's geographies and for geographical work on scale are considered

Understanding inclusion in collaborative governance: a mixed methods approach

Who should be included in collaborative governance and how they should be included is an important topic, though the dynamics of inclusion are not yet well understood. We propose a conceptual model to shape the empirical analysis of what contributes to inclusion in collaborative processes. We propose that incentives, mutual interdependence and trust are important preconditions of inclusion, but that active inclusion management also matters a great deal. We also hypothesize that inclusion is strategic, with ‘selective activation’ of participants depending on functional and pragmatic choices. Drawing on cases from the Collaborative Governance Case Databank, we used a mixed method approach to analyse our model. We found support for the model, and particularly for the central importance of active inclusion management.Fil: Ansell, Christopher. University of California at Berkeley; Estados UnidosFil: Doberstein, Carey. University of British Columbia; CanadáFil: Henderson, Hayley. The Australian National University; Australia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Saavedra 15. Centro de Estudios Urbanos y Regionales; ArgentinaFil: Siddiki, Saba. Syracuse University; Estados UnidosFil: ‘t Hart, Paul. Utrecht University; Países Bajo

Role of Reactive Oxygen Species in the Neural and Hormonal Regulation of the PNMT Gene in PC12 Cells

The stress hormone, epinephrine, is produced predominantly by adrenal chromaffin cells and its biosynthesis is regulated by the enzyme phenylethanolamine N-methyltransferase (PNMT). Studies have demonstrated that PNMT may be regulated hormonally via the hypothalamic-pituitary-adrenal axis and neurally via the stimulation of the splanchnic nerve. Additionally, hypoxia has been shown to play a key role in the regulation of PNMT. The purpose of this study was to examine the impact of reactive oxygen species (ROS) produced by the hypoxia mimetic agent CoCl2, on the hormonal and neural stimulation of PNMT in an in vitro cell culture model, utilizing the rat pheochromocytoma (PC12) cell line. RT-PCR analyses show inductions of the PNMT intron-retaining and intronless mRNA splice variants by CoCl2 (3.0- and 1.76-fold, respectively). Transient transfection assays of cells treated simultaneously with CoCl2 and the synthetic glucocorticoid, dexamethasone, show increased promoter activity (18.5-fold), while mRNA levels of both splice variants do not demonstrate synergistic effects. Similar results were observed when investigating the effects of CoCl2-induced ROS on the neural stimulation of PNMT via forskolin. Our findings demonstrate that CoCl2-induced ROS have synergistic effects on hormonal and neural activation of the PNMT promoter

Understanding Collaboration:Introducing the Collaborative Governance Case Databank

Studying collaborative governance has become a booming business. However, the empirical literature still struggles to produce robust generalizations and cumulative knowledge that link contextual, situational and institutional design factors to processes and outcomes. We still have not mustered the broad and deep evidence base that will really help us sort fact from fiction and identify more and less productive approaches to collaboration. The current empirical evidence in the study of collaborative governance consists chiefly of small-N case studies or large-N surveys. The challenge is to move from case-based, mid-range theory building to more largeN-driven systematic theory-testing, while also retaining the rich contextual and process insights that only small-N studies tend to yield. This article, and the articles in the accompanying special issue, introduces an attempt to provide this middle ground– the Collaborative Governance Case Database. The database has been developed to serve as a free common pool resource for researchers to systematically collect and compare high-quality collaborative governance case studies. This article is an introduction to the database, exploring its design, opportunities and limitations. This article is also an invitation; inviting all researchers to freely use the cases in the database for their own research interest and to help strengthening the database by adding new cases they are eager to share with colleagues

Superintegrable relativistic systems in scalar background fields

14 pages, two PDF figuresWe consider a relativistic charged particle in a background scalar field depending on both space and time. Poincar\'e, dilation and special conformal symmetries of the field generate conserved quantities in the charge motion, and we exploit this to generate examples of superintegrable relativistic systems. We also show that the corresponding single-particle wavefunctions needed for the quantum scattering problem can be found exactly, by solving the Klein-Gordon equation

The Political Economy of Tuna Exploitation in the Western Indian Ocean - Geopolitics and Resource Management

This paper is based on work that the authors have carried out on EU financed projects in the South Western Indian Ocean (SWIO) in collaboration with the Indian Ocean Tuna Commission and the Indian Ocean Commission (IOC)¹ on a range of fisheries management issue including, stock assessment, tagging and monitoring, control and surveillance (MCS). The Indian Ocean Tuna Commission (IOTC) is a non-governmental organization established under Article XIV of the FAO constitution. Its mandate is to manage tuna stocks and other main tuna-like species of the Indian Ocean and adjacent waters. It brings together the coastal states of the Indian Ocean and some of the states that fish tuna and tuna-like species in the WIO. The twenty three member states of the CTOI submit catch data to the CTOI. The CTOI is the only organisation that actively collects such information. This information is then disaggregated and through specific Working Parties analysed to form the basis of management decisions and resolutions and recommendations to its contracting parties. Large pelagic resources (tuna and tuna like fish) constitute the single largest marine resource at the disposal of the small island states of the IOC (with the exception of Madagascar). Long-term sustainable management of tuna and associated resources is without doubt of critical importance both to the coastal states of the Western Indian Ocean (WIO) and to the dependent markets of the European Union and Asia. Tuna contributes significantly to foreign exchange generation through receipts from fishing agreements, exports of tuna and tuna products as well as by the expenditure of foreign fishing fleets in the ports of the region and access/licence fees. The paper considers some of major issues - is the rent extraction from tuna fisheries optimal from the point of view of the WIO states and what are the key issues for the future of tuna fisheries? What are the threats to the regions tuna fisheries? - illegal, unregulated and unreported (IUU) fishing, over exploitation and what are the options for the WIO states in the future for the better management of the tuna resources. Fish has become a major world commodity with increased trade, globalisation and increasing demand. Within marine fisheries, tuna is one of the high value commodities in terms of aggregate value and for certain species as a product for high income consumers who buy sushi and other tuna based products. The paper also looks at the geopolitics of the tuna fisheries in terms of resource competition between countries.Keywords: Tuna, Globalisation, Indian Ocean, EEZ, WTO, Tagging, Unregulated and Unreported, Geopolitics, Indian Ocean Tuna Commission, Precautionary Approach, EU, Tuna Like Species, Illegal, Indian Ocean Commission, Political Economy, Commodity, FA