Instanton Calculus With R-R Background And Topological Strings

The non-perturbative low energy effective action of N=2 SYM is studied within a microscopic string realization via D3/D-instanton systems. The localization deformation of instanton moduli space which has allowed the exact computation of multi-instanton contributions is, in this setting, due to a RR graviphoton background. The relation of deformed instanton contributions to topological string amplitudes on CY, argued by Nekrasov, appears quite natural in this framework. Based on arXiv:hep-th/0606013.Comment: 5 pages, 3 fig.s, Latex, uses w-art class (included). To appear in the proceedings of the RTN workshop "ForcesUniverse", Naples, October 9-13, 200

Anomalous Creation of Branes

In certain circumstances when two branes pass through each other a third brane is produced stretching between them. We explain this phenomenon by the use of chains of dualities and the inflow of charge that is required for the absence of chiral gauge anomalies when pairs of D-branes intersect.Comment: 7 pages, two figure

Spatial analysis of the benefits and burdens of ecological focus areas for water-related ecosystem services vulnerable to climate change in Europe

There are many concerns regarding the effects of climate change including threats to ecosystem services. Rural land use can influence these services and there is scope for associated policies to steer decisions towards maximising benefits and minimising burdens. In Europe, for example, ecological focus areas (EFAs), introduced in the last reform of the Common Agricultural Policy, can have impacts on ecosystem services which vary with location, including potential trade-offs between benefits and burdens in some regions. This study combines the outputs from two continental-scale projects to provide a new perspective on the potential impact of EFAs for water-related ecosystem services under threat from climate change. An ecosystem service impact indicator framework was applied in conjunction with a climate change vulnerability assessment. This resulted in vulnerability and area weighted performance scores for dilution, filtration, water provision, and flood regulation services for 10 EFAs in 1256 regions. Best, average and worst case scenario maps were created that highlight the relative benefits and burdens of EFAs. Six EFAs have been identified which have not been activated in nine European Member States but which have potential to provide benefits. Eleven Member States have been identified which have regions where 3 EFAs should be avoided due to potential burdens. This analysis facilitates broad spatial targeting on a continental-scale of specific EFAs which may help maintain (and ideally increase) ecosystem service capacity and resilience in vulnerable regions.Peer reviewedFinal Accepted Versio

Identifying integrated options for agricultural climate change mitigation

Purpose: In order to achieve reductions in greenhouse gas emissions it is essential that all industry sectors have the appropriate knowledge and tools to contribute. This includes agriculture, which is considered to contribute about a third of emissions globally. This paper reports on one such tool: IMPACCT: Integrated Management oPtions for Agricultural Climate Change miTigation. Design/methodology/approach: IMPACCT focuses on greenhouse gas emissions, carbon sequestration and associated mitigation options. However, it also attempts to include information on economic and other environmental impacts in order to provide a more holistic perspective. The model identifies mitigation options, likely economic impacts and any synergies and trade-offs with other environmental objectives. The model has been applied on 22 case study farms in seven member states. Findings: The tool presents some useful concepts for developing carbon calculators in the future. It has highlighted that calculators need to evolve from simply calculating emissions to identifying cost effective and integrated emissions reduction options. Practical implications: IMPACCT has potential to become an effective means of provided targeted guidance, as part of a broader knowledge transfer programme based on an integrated suite of guidance, tools and advice delivered via different media. Originality/value: IMPACCT is a new model that demonstrates how to take a more integrated approach to mitigating greenhouse gas emissions on farms across Europe. It is a holistic carbon calculator that presents mitigation options in the context other environmental and economic objectives in the search for more sustainable methods of food production.Peer reviewedFinal Accepted Versio

Adapting to climate change : Assessing the vulnerability of ecosystem services in Europe in the context of rural development

This document is the Accepted Manuscript version. The final publication is available at Springer via https://doi.org/10.1007/s11027-013-9507-6.Over the past decade, efforts to move towards a low carbon economy have been increasingly coupled with the acknowledgement that we also need to develop climate resilient economies, capable of adapting and responding to changes in climate. To shift society in these directions we need to quantify impacts in relation to these objectives and develop cost-effective interventions. Techniques for quantifying greenhouse gas emissions are relatively well established and enable identification of hotspots where there is emissions reduction potential. However, there are no established techniques to assess and quantify adaptation vulnerability issues and identify hotspots for intervention. This paper presents work undertaken at a European level with the objective of identifying potential hotspots where ecosystem services may be vulnerable to climate change and thus where intervention may be required under the European Rural Development Programme. A pragmatic and relatively simple approach is presented, based on data that is readily available across Europe. The vulnerability assessments cover: Water (quality: dilution and filtration, regulation: flooding and provision); soils (erosion and organic matter); and biodiversity (forest fires, migration and pollination). The framework and assessments presented are considered fit for purpose (at a basic level) and they are potentially valuable tools for targeting limited resources to achieve desirable outcomes. They also contribute towards providing a better understanding of the climate change challenges we face and support the formulation of solutions to optimally address those challenges. There is scope to further improvement and a number of options are discussed and explored within this paperPeer reviewe

Pair Creation of Open Strings in an Electric Field

We calculate exactly the rate of pair production of open bosonic and supersymmetric strings in a constant electric field. The rate agrees with Schwinger's classic result in the weak-field limit, but diverges when the electric field approaches some critical value of the order of the string tension. (Phyzzx file)Comment: 13 pages, CPTH-A182.089

Generalized Green-Schwarz mechanism in F theory

We derive the anomaly 8-form of 6-dimensional gauge theories arising in F theory compactifications on elliptic Calabi-Yau threefolds. The result allows to determine the matter content of certain such theories in terms of intersection numbers on the base of elliptic fibration. We also discuss gauge theories on 7-branes with double point singularities on the worldvolume. Applications to Type II compactifications on Hirzebruch surfaces and $P^2$ are outlined.Comment: 11 pages, harvmac. Normalization of (tr R^2)^2 term correcte

Short Distance Contributions to Graviton-Graviton Scattering: Matrix Theory versus Supergravity

We study graviton scattering in the presence of higher dimensional operators - particularly, R^4 - arising from loop effects. We find that the results do not correspond to any known terms in the effective action of Matrix Theory, thus lending support to the idea that the finite N Matrix Theory has no simple relation to supergravity with large compactification radii.Comment: 13 pages, LaTeX file with 3 Postscript figures. Uses epsf.tex and fps.sty macros. Revisions of v2: some comments in the end of section 3 have been remove