Cosmic strings in dilaton gravity

We examine the metric of an isolated self-gravitating abelian-Higgs vortex in dilatonic gravity for arbitrary coupling of the vortex fields to the dilaton. We look for solutions in both massless and massive dilaton gravity. We compare our results to existing metrics for strings in Einstein and Jordan-Brans-Dicke theory. We explore the generalization of Bogomolnyi arguments for our vortices and comment on the effects on test particles.Comment: 24 pages plain TEX, 4 figures -- references amended, some additional comments added, version to appear in journa

Dilatonic global strings

We examine the field equations of a self-gravitating global string in low energy superstring gravity, allowing for an arbitrary coupling of the global string to the dilaton. Massive and massless dilatons are considered. For the massive dilaton the spacetime is similar to the recently discovered non-singular time-dependent Einstein self-gravitating global string, but the massless dilaton generically gives a singular spacetime, even allowing for time-dependence. We also demonstrate a time-dependent non-singular string/anti-string configuration, in which the string pair causes a compactification of two of the spatial dimensions, albeit on a very large scale.Comment: 18 pages RevTeX, 3 figures, references amende

Passing the Panda Standard: A TAD Off the Mark?

Tilapia, a tropical freshwater fish native to Africa, is an increasingly important global food commodity. The World Wide Fund for Nature (WWF), a major environmental nongovernmental organization, has established stakeholder dialogues to formulate farm certification standards that promote ‘‘responsible’’ culture practices. As a preface to its ‘‘tilapia aquaculture dialogue,’’ the WWF for Nature commissioned a review of potential certification issues, later published as a peer-reviewed article. This article contends that both the review and the draft certification standards subsequently developed fail to adequately integrate critical factors governing the relative sustainability of tilapia production and thereby miss more significant issues related to resource-use efficiency and the appropriation of ecosystem space and services. This raises a distinct possibility that subsequent certification will promote intensive systems of tilapia production that are far less ecologically benign than existing widely practiced semiintensive alternatives. Given the likely future significance of this emergent standard, it is contended that a more holistic approach to certification is essential

Reimagining invasions; the social and cultural impacts of Prosopis on pastoralists in Southern Afar

Abstract Whilst the environmental impacts of biological invasions are clearly conceptualised and there is growing evidence on the economic benefits and costs, the social and cultural dimensions remain poorly understood. This paper presents the perceptions of pastoralist communities in southern Afar, Ethiopian lowlands, on one invasive species, Prosopis juliflora. The socio-cultural impacts are assessed, and the manner in which they interact with other drivers of vulnerability, including political marginalisation, sedentarisation and conflict, is explored. The research studied 10 communities and undertook semi-structured interviews and focus group discussions with pastoralists and agro-pastoralists. These results were supported by interviews with community leaders and key informants. The benefits and costs were analysed using the asset-based framework of the Sustainable Livelihoods Framework and the subject-focused approach of Wellbeing in Development. The results demonstrate that the costs of invasive species are felt across all of the livelihood capital bases (financial, natural, physical, human and social) highlighted within the framework and that the impacts cross multiple assets, such as reducing access through blocking roads. The concept of Wellbeing in Development provides a lens to examine neglected impacts, like conflict, community standing, political marginalisation and cultural impoverishment, and a freedom of definition and vocabulary to allow the participants to define their own epistemologies. The research highlights that impacts spread across assets, transcend objective and subjective classification, but also that impacts interact with other drivers of vulnerability. Pastoralists report deepened and broadened conflict, complicated relationships with the state and increased sedentarisation within invaded areas. The paper demonstrates that biological invasions have complex social and cultural implications beyond the environmental and economic costs which are commonly presented. Through synthesising methodologies and tools which capture local knowledge and perceptions, these implications and relationships are conceptualised

How Market-Based Water Allocation Can Improve Water Use Efficiency in the Aral Sea Basin?

Increasing water demand due to population growth, irrigation expansion, industrial development, and the need for ecosystem improvements under mounting investment costs for developing new water sources calls for the efficient, equitable and sustainable management of water resources. This is particularly essential in the Aral Sea Basin (ASB) where ineffective institutions are the primary reason of intersectoral and inter-state water sharing conflicts and lack of sufficient investments for improving water use efficiency. This study examined market-based water allocation as an alternative option to the traditional administrative allocation to deal with water scarcity issues in the ASB. Potential economic gains of tradable water use rights were analyzed based on a newly constructed integrated hydro-economic river basin management model. The analysis differentiates between inter- catchment and intra-catchment water trading. The former does not consider any restrictions on water trading whereas the latter is based on the assumption that water trading is more likely to happen between neighboring water users located within the same catchment area. The analyses show that compared to fixed water allocation, inter-catchment water trading can improve basin-wide benefits by US$373 and US$ 476 million depending on water availability. Similarly, additional gains of US$259 to US$ 339 million are estimated under intra-catchment water trading depending on relative water availability. Trading gains are higher under drier conditions. However, water trading carries a series of transaction costs. We find that transaction costs exceeding US$0.05 per m3 of water traded wipe out the economic potential for water trading. Enforcement of the rule of law, infrastructural improvements, participation of representatives of all water stakeholders in decision making processes, and friendly relationships among the riparian countries are suggested as means for reducing transaction costs of water trading contracts

Elevated protein concentrations in newborn blood and the risks of autism spectrum disorder, and of social impairment, at age 10 years among infants born before the 28th week of gestation

Among the 1 of 10 children who are born preterm annually in the United States, 6% are born before the third trimester. Among children who survive birth before the 28th week of gestation, the risks of autism spectrum disorder (ASD) and non-autistic social impairment are severalfold higher than in the general population. We examined the relationship between top quartile inflammation-related protein concentrations among children born extremely preterm and ASD or, separately, a high score on the Social Responsiveness Scale (SRS total score ≥65) among those who did not meet ASD criteria, using information only from the subset of children whose DAS-II verbal or non-verbal IQ was ≥70, who were assessed for ASD, and who had proteins measured in blood collected on ≥2 days (N = 763). ASD (N = 36) assessed at age 10 years is associated with recurrent top quartile concentrations of inflammation-related proteins during the first post-natal month (e.g., SAA odds ratio (OR); 95% confidence interval (CI): 2.5; 1.2–5.3) and IL-6 (OR; 95% CI: 2.6; 1.03–6.4)). Top quartile concentrations of neurotrophic proteins appear to moderate the increased risk of ASD associated with repeated top quartile concentrations of inflammation-related proteins. High (top quartile) concentrations of SAA are associated with elevated risk of ASD (2.8; 1.2–6.7) when Ang-1 concentrations are below the top quartile, but not when Ang-1 concentrations are high (1.3; 0.3–5.8). Similarly, high concentrations of TNF-α are associated with heightened risk of SRS-defined social impairment (N = 130) (2.0; 1.1–3.8) when ANG-1 concentrations are not high, but not when ANG-1 concentrations are elevated (0.5; 0.1–4.2)

METASURFACE-BASED MEMS THZ-TO-IR FOCAL PLANE ARRAY

Terahertz (THz) technology has gained momentum in recent years owing to special properties of THz waves being non-ionizing and at the same time being able to penetrate through non-metallic and non-polar materials. Nearly perfect THz absorption, optimized to particular THz quantum cascade laser (QCL) illumination sources, was achieved using metal-dielectric metasurfaces. The metasurfaces are composed of ultra-thin films of silicon oxide and aluminum, deposited on silicon substrates, and were fabricated using standard MEMS processes. The metasurface absorbers were structurally integrated onto an array of thermally insulated free-standing MEMS membranes that work as heat accumulators. The temperature of array is probed directly by a commercial thermal camera, translating the THz scene to infrared. The main characteristics such as spectral response, thermal time constant and sensitivity are controlled by the geometry and tuned by design according to the application demands. The results indicate great potential of using these THz sensors in real-time imaging applications. This thesis focuses on the development of the broadband IR emitter that will be probed by the IR camera. Several metamaterial broadband IR emitter geometries were evaluated and compared using finite element simulations.http://archive.org/details/metasurfacebased1094560448Outstanding ThesisLieutenant, United States NavyApproved for public release; distribution is unlimited