On the nature of reconnection at a solar coronal null point above a separatrix dome

Three-dimensional magnetic null points are ubiquitous in the solar corona, and in any generic mixed-polarity magnetic field. We consider magnetic reconnection at an isolated coronal null point, whose fan field lines form a dome structure. We demonstrate using analytical and computational models several features of spine-fan reconnection at such a null, including the fact that substantial magnetic flux transfer from one region of field line connectivity to another can occur. The flux transfer occurs across the current sheet that forms around the null point during spine-fan reconnection, and there is no separator present. Also, flipping of magnetic field lines takes place in a manner similar to that observed in quasi-separatrix layer or slip-running reconnection.Comment: Accepted for publication in the Astrophysical Journa

Economic Equality and Victory in War: An Empirical Investigation

This paper tests a simple hypothesis: that given the occurrence of war between two countries, the country that is more egalitarian at the moment of military decision is likely to emerge the victor. First, we examine cases where comparative economic inequality can be measured directly, using the nearly comprehensive global data-sets of the University of Texas Inequality Project for the years 1963-1999. Second, we examine cases where reasonable inferences about comparative economic inequality may be drawn by analogy to UTIP measurements or from other political and economic evidence, including both bi-national wars and larger wars where there existed clear pair-wise fronts. Third, we discuss selected cases where inferences may be drawn from literary or historical sources. We find, all in all, that the evidence for an egalitarian victory proposition is remarkably strong.

Flow reversals in turbulent convection via vortex reconnections

We employ detailed numerical simulations to probe the mechanism of flow reversals in two-dimensional turbulent convection. We show that the reversals occur via vortex reconnection of two attracting corner rolls having same sign of vorticity, thus leading to major restructuring of the flow. Large fluctuations in heat transport are observed during the reversal due to this flow reconfiguration. The flow configurations during the reversals have been analyzed quantitatively using large-scale modes. Using these tools, we also show why flow reversals occur for a restricted range of Rayleigh and Prandt numbers

Use of an online interactive space analysis tool to understand student perceptions of four secondary schools

With the sheer complexity of the built environment, understanding the aspects of the building that directly impact the occupants can be prohibitively difficult. Previous methods have been largely split between low-number, high-detail methods (photo-surveys or interviews), or high-number, low-detail methods (questionnaires). This study presents an alternative to these methods; creating an online tool that represents a navigable building, enabling the occupants to freely identify any aspect of the building that they feel is important. This online tool deliberately works in a manner similar to Google Street View, taking advantage of this familiarity to reduce the learning curve and maximise immersion. Using spherical images captured with a special camera or smartphone, each space in the building is captured and then uploaded into the online tool. Whilst in the online version of their building, the respondent can navigate through the building, make unguided comments about any part of the building. Using this tool, four recently built secondary schools were imaged and online versions created. In each school, students from three ICT lessons aged between 11 and 14 explored the online version of their school and marked parts of the building that were important to them. The students were asked to follow a typical day in the school, moving from lesson to lesson and to the spaces they use at breaks. The tool collected both the movement data and the comments, allowing analysis of not just the occupant attitudes, but also the route the students take through the building. The movement data for each school was compared to the visual graph analysis of the building, showing that the movement of the students within the tool resembles patterns seen elsewhere; configurational logic with attractors. The rich data that is generated in parallel with the movement data allowed insights into the way in which the students moved through the space and what was important to them

Maternal-Zygotic Epistasis and the Evolution of Genetic Diseases

Many birth defects and genetic diseases are expressed in individuals that do not carry the disease causing alleles. Genetic diseases observed in offspring can be caused by gene expression in mothers and by interactions between gene expression in mothers and offspring. It is not clear whether the underlying pattern of gene expression (maternal versus offspring) affects the incidence of genetic disease. Here we develop a 2-locus population genetic model with epistatic interactions between a maternal gene and a zygotic gene to address this question. We show that maternal effect genes that affect disease susceptibility in offspring persist longer and at higher frequencies in a population than offspring genes with the same effects. We find that specific forms of maternal-zygotic epistasis can maintain disease causing alleles at high frequencies over a range of plausible values. Our findings suggest that the strength and form of epistasis and the underlying pattern of gene expression may greatly influence the prevalence of human genetic diseases

Plasma Relaxation and Topological Aspects in Hall Magnetohydrodynamics

Parker's formulation of isotopological plasma relaxation process in magnetohydrodynamics (MHD) is extended to Hall MHD. The torsion coefficient alpha in the Hall MHD Beltrami condition turns out now to be proportional to the "potential vorticity." The Hall MHD Beltrami condition becomes equivalent to the "potential vorticity" conservation equation in two-dimensional (2D) hydrodynamics if the Hall MHD Lagrange multiplier beta is taken to be proportional to the "potential vorticity" as well. The winding pattern of the magnetic field lines in Hall MHD then appears to evolve in the same way as "potential vorticity" lines in 2D hydrodynamics

Flux and field line conservation in 3--D nonideal MHD flows: Remarks about criteria for 3--D reconnection without magnetic neutral points

We make some remarks on reconnection in plasmas and want to present some calculations related to the problem of finding velocity fields which conserve magnetic flux or at least magnetic field lines. Hereby we start from views and definitions of ideal and non-ideal flows on one hand, and of reconnective and non-reconnective plasma dynamics on the other hand. Our considerations give additional insights into the discussion on violations of the frozen--in field concept which started recently with the papers by Baranov & Fahr (2003a; 2003b). We find a correlation between the nonidealness which is given by a generalized form of the Ohm's law and a general transporting velocity, which is field line conserving.Comment: 9 pages, 2 figures, submitted to Solar Physic

'Do the resilient things.' Residents' perspectives on responsibilities for flood risk adaptation in England

Residents should take adaptive action to reduce flood risk – this claim increasingly resonates in the academic debate on flood risk management (FRM). Hence it must be assumed that a change in the division of responsibilities between actors involved is an imperative, i.e., beyond the public authorities, residents should become more responsible for their own flood resilience. However, residents’ perspectives on their own and other’s responsibility for adaptive action has not yet been explored extensively. In this contribution, we distinguish between four notions of responsibility in analysing the perspectives of residents regarding flood risk adaptation measures undertaken by public authorities, insurance companies and residents themselves. A qualitative study in England shows how residents perceive responsibilities for flood risk adaptation across the various notions and actors, including themselves. We found that residents have clear expectations and perceptions on how they think responsibility is divided among stakeholders and how they would like it to be. Additionally, the discourse on responsibility division in FRM raises questions and causes mismatches between the formal legal parameters and residents’ perceptions. With the insights into residents’ perceptions, opportunities arise to better inform and encourage them to take flood risk adaptation measures and thereby improve flood resilience

A fluorescent mutant of the phosphorus-solubilizing fungus Penicillium bilaiae to image rhizosphere growth

Non-Peer ReviewedNovozymes manufactures and markets a phosphate inoculant, JumpStart®, based on the phosphorus-solubilizing fungus Penicillium bilaiae. We are developing a mutant of this fungus that expresses the DsRed-Express fluorescent protein, which will be used as a research tool to allow us to see where and how P. bilaiae interacts with plant roots