Condensing Nielsen-Olesen strings and the vortex-boson duality in 3+1 and higher dimensions

The vortex-boson (or Abelian-Higgs, XY) duality in 2+1 dimensions demonstrates that the quantum disordered superfluid is equivalent to an ordered superconductor and the other way around. Such a duality structure should be ubiquitous but in 3+1 (and higher) dimensions a precise formulation of the duality is lacking. The problem is that the topological defects become extended objects, strings in 3+1D. We argue how the condensate of such vortex strings must behave from the known physics of the disordered superfluid, namely the Bose-Mott insulator. A flaw in earlier proposals is repaired, and a more direct viewpoint, avoiding gauge fields, in terms of the physical supercurrent is laid out, that also easily generalizes to higher-dimensional and more complicated systems. Furthermore topological defects are readily identified; we demonstrate that the Bose-Mott insulator supports line defects, which may be seen in cold atom experiments.Comment: LaTeX, 25 pages, 5 figures; several revisions and addition

Redundant disc

A rotatable disc is described that consists of parallel plates tightly joined together for rotation about a hub. Each plate is provided with several angularly projecting spaced lands. The lands of each plate are interposed in alternating relationship between the lands of the next adjacent plate. In this manner, circumferential displacement of adjacent sectors in any one plate is prevented in the event that a crack develops. Each plate is redundantly sized so that, in event of structural failure of one plate, the remaining plates support a proportionate share of the load of the failed plate. The plates are prevented from separating laterally through the inclusion of generally radially extending splines which are inserted to interlock cooperating, circumferentially adjacent lands

Virtual Assets, Real Tax: The Capital Gains/Ordinary Income Distinction in Virtual Worlds

A great deal of economic activity now occurs in virtual worlds, raising questions about the proper taxation of income generated by virtual world activity. This Note focuses on the characterization of such income, that is, whether income earned in virtual worlds should be classified as ordinary income or capital gains. Generally, the character of income is determined by the activity which generated the income. In the context of virtual worlds, the issue is whether character should be determined by the nature of the user's transactions within the world. As argued below, there is no good conceptual justification for treating economic activity in virtual worlds differently from analogous activity that occurs in the real world. However, applying the capital gains-ordinary income distinction to virtual worlds would not be administratively feasible. Thus, for the reasons set forth in this Note, the best possible tax regime is to classify all income earned in virtual worlds as ordinary income

Type-II Bose-Mott insulators

The Mott insulating state formed from bosons is ubiquitous in solid He-4, cold atom systems, Josephson junction networks and perhaps underdoped high-Tc superconductors. We predict that close to the quantum phase transition to the superconducting state the Mott insulator is not at all as featureless as is commonly believed. In three dimensions there is a phase transition to a low temperature state where, under influence of an external current, a superconducting state consisting of a regular array of 'wires' that each carry a quantized flux of supercurrent is realized. This prediction of the "type-II Mott insulator" follows from a field theoretical weak-strong duality, showing that this 'current lattice' is the dual of the famous Abrikosov lattice of magnetic fluxes in normal superconductors. We argue that this can be exploited to investigate experimentally whether preformed Cooper pairs exist in high-Tc superconductors.Comment: RevTeX, 17 pages, 6 figures, published versio

De consumptie van dierlijke producten : ontwikkelingen, invloedsfactoren, actoren en interventies

LEI Wageningen UR heeft in opdracht van het Planbureau voor de Leefomgeving (PBL) met behulp van kwantitatief onderzoek onderzocht hoe de consumptie van dierlijke producten zich in Europese landen in de afgelopen decennia heeft ontwikkeld. Daarnaast zijn met behulp van kwalitatief onderzoek mogelijke interventies geïdentificeerd gericht op het beïnvloeden van de consumptie van dierlijke producten. Dit onderzoek biedt een basis voor de verdere uitwerking en uitvoering van door publieke en private actoren te nemen maatregelen gericht op verandering of vermindering van de consumptie van dierlijke producten

Територія і кордон як фактори формування етнічної ідентичності (за матеріалами досліджень прикордонних територій Брянської області)

В статье на основе современного исследования, проведённого среди населения Брянской области России, которое проживает на пограничье с Беларусью и Украиной, отражён процесс формирования этнической идентичности у местных подростков (16–18 лет). Также проанализирован ряд идентичных критериев, факторов исторического взаимодействия трёх восточнославянских народов в сфере образования, культуры, языка, конфессиональной принадлежности и т. п.Based on the modern investigation amongst the Russian Briansk Oblast people living on the frontier with Byelorussia and Ukraine there is an elucidation of the ethnical identity formative process amidst the local teenagers (16–18-year-old). Moreover analysed is a number of the identical criteria and factors of the historical interrelations of the three Eastern Slavonic nations in the fields of education, culture, language, confession, etc

An analysis of the challenges for groundwater governance during shale gas development in South Africa

As a prelude to potential development of South Africa’s shale gas resources, it is critical to develop and implement effective groundwater governance arrangements. Existing policies and plans were analysed to determine whether critical gaps or barriers exist that could potentially lead to impacts on groundwater systems. Ten high-priority governance challenges were identified: (a) defining relevant metrics for baseline groundwater quality and availability; (b) developing guidelines for shale gas resource licensing, exploration, drilling, extraction, production, and completion; (c) defining and enforcing compliance monitoring systems; (d) dealing punitively with non-compliant operators; (e) mitigating and managing risks to prevent impairment of groundwater resources; (f) implementing a goal-based regulatory framework; g) enforcing strict chemical disclosure requirements; (h) coordinating across government departments and regulatory bodies meaningfully and productively; (i) implementing a framework for subsidiarity and support to local water management; and (j) providing an incentive framework that supports strong groundwater management and environmental protection. To overcome these challenges, it is recommended that a decentralised, polycentric, bottom-up approach involving multiple institutions is developed to adaptively manage shale gas development. This transition from the current rigid regulatory structure can foster cooperation and collaboration among key stakeholders. The use of a pro-active groundwater governance structure that can accommodate current, near-term, and long-term shale gas development is important for ensuring that future energy development in South Africa incorporates the influence of other simultaneous stressors such as climate (e.g. drought), landuse changes, population growth, industry, and competing demands for water.Keywords: groundwater, water governance, shale gas, South Afric