Report on a visit to South Africa to facilitate a participatory workshop for an urban agriculture project in Sobantu Village, KwaZulu-Natal, as part of the DfID funded project: "Support to the Institute of Natural Resources for institutional development in South Africa"

The DfID project "Support to the INR for institutional development in South Africa" is led by the Natural Resources Adviser at DfID in Pretoria, and managed by NRinternational. The project consists of several components (curriculum development, project management, appropriate technology, participatory rural appraisal and farming systems/fanner participatory research FSRIFPR) with inputs from Reading University, Intermediate Technology Consultants and NRI. The project is due to finish by July 1998. In two previous visits, the authors have given courses in Farming Systems and Farmer Participatory Research to members of the Institute for Natural Resources (INR), the Department of Agriculture, the Agricultural Research Council and other institutions concerned with agricultural development of disadvantaged communities in KwaZulu Natal. The content of these training courses has been compiled into a draft training handbook. This visit was made at the request of INR. Unlike previous visits it was concerned with a real development initiative, rather than training, and provided an excellent opportunity to put into practice many of the approaches and methods which had been the focus of training in previous visits. Visit Objectives. The objectives of the visit were as follows: a) With the Sobantu community and INR and Department of Agriculture staff, facilitate a participatory workshop to identify organisational/institutional, social, technical and financial issues and the processes and activities necessary to initiate an urban agriculture project; b) Discuss the draft of a manual on FSR/FPR being prepared by NRI/INR; c) Discuss follow-on activities with INR Chief Executive and staff (given that the present project finishes by July 1998)

Black hole perturbation theory and gravitational self-force

Much of the success of gravitational-wave astronomy rests on perturbation theory. Historically, perturbative analysis of gravitational-wave sources has largely focused on post-Newtonian theory. However, strong-field perturbation theory is essential in many cases such as the quasinormal ringdown following the merger of a binary system, tidally perturbed compact objects, and extreme-mass-ratio inspirals. In this review, motivated primarily by small-mass-ratio binaries but not limited to them, we provide an overview of essential methods in (i) black hole perturbation theory, (ii) orbital mechanics in Kerr spacetime, and (iii) gravitational self-force theory. Our treatment of black hole perturbation theory covers most common methods, including the Teukolsky and Regge-Wheeler-Zerilli equations, methods of metric reconstruction, and Lorenz-gauge formulations, casting them in a unified notation. Our treatment of orbital mechanics covers quasi-Keplerian and action-angle descriptions of bound geodesics and accelerated orbits, osculating geodesics, near-identity averaging transformations, multiscale expansions, and orbital resonances. Our summary of self-force theory's foundations is brief, covering the main ideas and results of matched asymptotic expansions, local expansion methods, puncture schemes, and point particle descriptions. We conclude by combining the above methods in a multiscale expansion of the perturbative Einstein equations, leading to adiabatic and post-adiabatic evolution and waveform-generation schemes. Our presentation includes some new results but is intended primarily as a reference for practitioners.Comment: 121 pages, 1 figure. Invited chapter for "Handbook of Gravitational Wave Astronomy" (Eds. C. Bambi, S. Katsanevas, and K. Kokkotas; Springer, Singapore, 2021). The second version corrects typos and adds Table

Climate change, agriculture and Fairtrade: identifying the challenges and opportunities

This paper presents the findings of a study commissioned by the UK's Fairtrade Foundation on the implications of climate change for agricultural producers in Fairtrade value chains

Second-order perturbation theory: the problem of infinite mode coupling

Second-order self-force computations, which will be essential in modeling extreme-mass-ratio inspirals, involve two major new difficulties that were not present at first order. One is the problem of large scales, discussed in [Phys. Rev. D 92, 104047 (2015)]. Here we discuss the second difficulty, which occurs instead on small scales: if we expand the field equations in spherical harmonics, then because the first-order field contains a singularity, we require an arbitrarily large number of first-order modes to accurately compute even a single second-order mode. This is a generic feature of nonlinear field equations containing singularities, allowing us to study it in the simple context of a scalar toy model in flat space. Using that model, we illustrate the problem and demonstrate a robust strategy for overcoming it

Principles and practical implementation of farming systems research and farmer participatory research. Including Vulindlela District and Sobantu Village case studies

This publication integrates theory and practical work arising from courses in Farming Systems and Farmer Participatory Research held at the Institute of Natural Resources and associated institutions in KwaZulu-Natal during 1996 and 1997. The courses were conducted as part of a project supported by the UK. Government's Department for International Development and managed by the UK Natural Resources Institute (NRI). Objectives of this publication are 1) to provide reference material in Farming Systems and Farmer Participatory Research for interested audiences in KwaZulu-Natal and elsewhere; 2) by integrating theory and practice, to demonstrate how the principles, approaches and methods of FSRJFPR can be applied to real situations; 3) to record the situation, suggestions and priorities of rural and peri-urban families in Vulindlela District, as recorded by course participants; 4) to provide a springboard of information for further development initiatives in Vulindlela and elsewhere in KwaZulu-Natal; 5) to present the Urban Agriculture workshop held in Sobantu Village as a case study of participatory workshop methods

Livelihoods analysis of landmine affected communities in Yemen (Volume I: main report)

The government of Yemen is committed to the complete elimination of landmines and explosive remnants of war. The National Mine Action Committee (NMAC) was established in June 1998 to formulate policy, allocate resources, and develop a national mine-action strategy. Furthermore, the Yemen Executive Mine Action Centre (YEMAC) was established in January 1999 as the implementing body of the NMAC with the primary responsibility of coordinating all mine-action activities in the country. The aim of the current Strategic Mine Action Plan is to put an end to the suffering and casualties caused by anti-personnel landmines, by the end of March 2009. As of September 2005, over 240 million square meters of affected land have been surveyed, cleared and returned to the local users. In 2005, the Mid-term Evaluation for strengthening national capacity for mine action in Yemen praised the achievements of YEMAC and NMAC to date, and also recommended that Community Rehabilitation become an integral part of mine action in Yemen in the future. This study was commissioned by YEMAC and the Geneva International Centre for Humanitarian Demining (GICHD), with the following objectives: 1. To assess the overall socio-economic returns from mine clearance investments; 2. to make a preliminary assessment of complementary development initiatives for mine-affected communities: and 3. to enhance the capacity of YEMAC to conduct future assessments of socio-economic benefits from mine action; assess the community Landmine Impact Scores as a tool for identifying impact and determining priorities for action; advise on how to design and conduct on-going socio-economic surveys relating to ERW; advise on integrating social differentiation within LIS survey protocols, and advise on enhancements to YEMAC’s monitoring and evaluation system

Livelihoods analysis of landmine affected communities in Yemen (Volume 2: annexes 1-11)

The government of Yemen is committed to the complete elimination of landmines and explosive remnants of war. The National Mine Action Committee (NMAC) was established in June 1998 to formulate policy, allocate resources, and develop a national mine-action strategy. Furthermore, the Yemen Executive Mine Action Centre (YEMAC) was established in January 1999 as the implementing body of the NMAC with the primary responsibility of coordinating all mine-action activities in the country. The aim of the current Strategic Mine Action Plan is to put an end to the suffering and casualties caused by anti-personnel landmines, by the end of March 2009. As of September 2005, over 240 million square meters of affected land have been surveyed, cleared and returned to the local users. In 2005, the Mid-term Evaluation for strengthening national capacity for mine action in Yemen praised the achievements of YEMAC and NMAC to date, and also recommended that Community Rehabilitation become an integral part of mine action in Yemen in the future. This study was commissioned by YEMAC and the Geneva International Centre for Humanitarian Demining (GICHD), with the following objectives: 1. To assess the overall socio-economic returns from mine clearance investments; 2. to make a preliminary assessment of complementary development initiatives for mine-affected communities: and 3. to enhance the capacity of YEMAC to conduct future assessments of socio-economic benefits from mine action; assess the community Landmine Impact Scores as a tool for identifying impact and determining priorities for action; advise on how to design and conduct on-going socio-economic surveys relating to ERW; advise on integrating social differentiation within LIS survey protocols, and advise on enhancements to YEMAC’s monitoring and evaluation system

Gravitational-wave energy flux for compact binaries through second order in the mass ratio

Within the framework of self-force theory, we compute the gravitational-wave energy flux through second order in the mass ratio for compact binaries in quasicircular orbits. Our results are consistent with post-Newtonian calculations in the weak field and they agree remarkably well with numerical-relativity simulations of comparable-mass binaries in the strong field. We also find good agreement for binaries with a spinning secondary or a slowly spinning primary. Our results are key for accurately modelling extreme-mass-ratio inspirals and will be useful in modelling intermediate-mass-ratio systems.Comment: 5 pages + supplemental material, 7 figure

Comparing second-order gravitational self-force and effective one body waveforms from inspiralling, quasi-circular and nonspinning black hole binaries II: the large-mass-ratio case

We compare recently computed waveforms from second-order gravitational self-force (GSF) theory to those generated by a new, GSF-informed, effective one body (EOB) waveform model for (spin-aligned, eccentric) inspiralling black hole binaries with large mass ratios. We focus on quasi-circular, nonspinning, configurations and perform detailed GSF/EOB waveform phasing comparisons, either in the time domain or via the gauge-invariant dimensionless function $Q_\omega\equiv \omega^2/\dot{\omega}$, where $\omega$ is the gravitational wave frequency. The inclusion of high-PN test-mass terms within the EOB radiation reaction (notably, up to 22PN) is crucial to achieve an EOB/GSF phasing agreement below 1~rad up to the end of the inspiral for mass ratios up to 500. For larger mass ratios, up to $5\times 10^4$, the contribution of horizon absorption becomes more and more important and needs to be accurately modeled. Our results indicate that our GSF-informed EOB waveform model is a promising tool to describe waveforms generated by either intermediate or extreme mass ratio inspirals for future gravitational wave detectorsComment: 13 pages, 8 figures. Submitted to Phys. Rev.

Comparing second-order gravitational self-force, numerical relativity and effective one body waveforms from inspiralling, quasi-circular and nonspinning black hole binaries

We present the first systematic comparison between gravitational waveforms emitted by inspiralling, quasi-circular and nonspinning black hole binaries computed with three different approaches: second-order gravitational self-force (2GSF) theory, as implemented in the 1PAT1 model; numerical relativity (NR), as implemented by the SXS collaboration; and the effective one body (EOB) formalism, as implemented in the TEOBResumS waveform model. To compare the models we use both a standard, time-domain waveform alignment and a gauge-invariant analysis based on the dimensionless function $Q_\omega(\omega)\equiv \omega^2/\dot{\omega}$, where $\omega$ is the gravitational wave frequency. We analyse the domain of validity of the 1PAT1 model, deriving error estimates and showing that the effects of the final transition to plunge, which the model neglects, extend over a significantly larger frequency interval than one might expect. Restricting to the inspiral regime, we find that, while for mass ratios $q = m_1/m_2\le 10$ TEOBResumS is largely indistinguishable from NR, 1PAT1 has a significant dephasing $\gtrsim 1$rad; conversely, for $q\gtrsim 100$, 1PAT1 is estimated to have phase errors $<0.1$rad on a large frequency interval, while TEOBResumS develops phase differences $\gtrsim1$rad with it. Most crucially, on that same large frequency interval we find good agreement between TEOBResumS and 1PAT1 in the intermediate regime $15\lesssim q\lesssim 64$, with $<0.5$rad dephasing between them. A simple modification to the TEOBResumS flux further improves this agreement for $q\gtrsim 30$, reducing the dephasing to $\approx0.27$rad even at $q=128$. Our results pave the way for the construction of GSF-informed EOB models for both intermediate and extreme mass ratio inspirals for the next generation of gravitational wave detectors.Comment: 31 pages, 19 figures, submitted to Phys. Rev.