14 research outputs found
Reflections of love in Hafez’s poetry
No full textOn the occasion of Valentine\u27s Day, Dr Pascal Held will discuss some of the different reflections of love in the poetry of the famous Sufi poet Hafez
Customizing kernel functions for SVM-based hyperspectral image classification
Get PDFPrevious research applying kernel methods such as support vector machines (SVMs) to hyperspectral image classification has achieved performance competitive with the best available algorithms. However, few efforts have been made to extend SVMs to cover the specific requirements of hyperspectral image classification, for example, by building tailor-made kernels. Observation of real-life spectral imagery from the AVIRIS hyperspectral sensor shows that the useful information for classification is not equally distributed across bands, which provides potential to enhance the SVM's performance through exploring different kernel functions. Spectrally weighted kernels are, therefore, proposed, and a set of particular weights is chosen by either optimizing an estimate of generalization error or evaluating each band's utility level. To assess the effectiveness of the proposed method, experiments are carried out on the publicly available 92AV3C dataset collected from the 220-dimensional AVIRIS hyperspectral sensor. Results indicate that the method is generally effective in improving performance: spectral weighting based on learning weights by gradient descent is found to be slightly better than an alternative method based on estimating ";relevance"; between band information and ground trut
Knowledge-aided STAP in heterogeneous clutter using a hierarchical bayesian algorithm
Get PDFThis paper addresses the problem of estimating the covariance matrix of a primary vector from heterogeneous samples and some prior knowledge, under the framework of knowledge-aided space-time adaptive processing (KA-STAP). More precisely, a Gaussian scenario is considered where the covariance matrix of the secondary data may differ from the one of interest. Additionally, some knowledge on the primary data is supposed to be available and summarized into a prior matrix. Two KA-estimation schemes are presented in a Bayesian framework whereby the minimum mean square error (MMSE) estimates are derived. The first scheme is an extension of a previous work and takes into account the non-homogeneity via an original relation. {In search of simplicity and to reduce the computational load, a second estimation scheme, less complex, is proposed and omits the fact that the environment may be heterogeneous.} Along the estimation process, not only the covariance matrix is estimated but also some parameters representing the degree of \emph{a priori} and/or the degree of heterogeneity. Performance of the two approaches are then compared using STAP synthetic data. STAP filter shapes are analyzed and also compared with a colored loading technique
Adaptive detection of distributed targets in compound-Gaussian noise without secondary data: A Bayesian approach
Get PDFIn this paper, we deal with the problem of adaptive detection of distributed targets embedded in colored noise modeled in terms of a compound-Gaussian process and without assuming that a set of secondary data is available.The covariance matrices of the data under test share a common structure while having different power levels. A Bayesian approach is proposed here, where the structure and possibly the power levels are assumed to be random, with appropriate distributions. Within this framework we propose GLRT-based and ad-hoc detectors. Some simulation studies are presented to illustrate the performances of the proposed algorithms. The analysis indicates that the Bayesian framework could be a viable means to alleviate the need for secondary data, a critical issue in heterogeneous scenarios
Biography of the Guest Editor
No full textF. Thomas Bruss studied Mathematics in Saarbrücken (Germany), and, with a delegation grant from Saarbrücken, in Cambridge(UK) and in Sheffield(UK). He holds the Diplom-Mathematiker as well as his doctorate Dr. rer. nat. in Mathematics of the University of Saarbrücken. His scientific career began in 1977 at the University of Namur. In 1978 he received the docteur l´ egal Dr. en sc. and obtained tenure as First assistant a year later. His time in Namur also included visiting positions at the University of Zaire (1981) and at Strathclyde University Glasgow (1984). He then moved to the United States, first as Visiting Associate Professor at UC Santa Barbara, then as Adjunct Professor (Feodor-Lynen) fellow at the University of Arizona, and then as Visiting Associate Professor at UCLA. In 1990 Thomas returned to Europe as Professor of the Vesalius College of the Vrije Universiteit Brussel. Independently, he obtained the inscription sur liste des professeurs of France. In 1993 he was appointed chair of Mathématiques Générales and Probabilités of the Université Libre de Bruxelles (ULB) where he has stayed ever since. Since then he also held visiting positions at the University of Antwerpen, the University of Namur and the Université Catholique de Louvain. Now, retired from the chair of Math´ ematiques G´ en´ erales, Thomas continues as Professeur de l’université of ULB, and as Invited Professor of the Université Catholique de Louvain. Prof. Bruss has made several important contributions to optimal stopping, including the 1/e-law of best choice (1984), Pascal processes (with LCG Rogers 1991), the odds algorithm (2000), or the solution of the last-arrival problem (with Marc Yor 2012). He also has strong interests in the theory of branching processes, as e.g. in bisexual Branching Processes and Resource-dependent Branching Processes (with Duerinckx 2015) as well as in various questions related with the theory of stochastic processes, as for instance the monotone subsequence problem (with Freddy Delbaen 2001, 2004). Thomas has served twice as head of the ULB Mathematics Department. He is also active in the national science foundations of Belgium, in the Belgian Statistical Society, the Belgian Mathematical Society, and the Collége Belgique. He is an elected member of the Tȕnissteiner Kreis (Germany), a fellow of the von-Humboldt Foundation (Germany) and a fellow of the Institute of Mathematical Statistics (USA). Thomas is also renowned for his outreach activity, with articles published in journals such as Spektrum der Wissenschaft, Pour la Science, Le Soir and Die Welt, as well as for his appearances on radio and television for expertise in probability. He has received several national and international distinctions and awards. In 2011 F. Thomas Bruss was honoured Commandeur de l’ordre de Léopold of Belgium
The future of small farms for poverty reduction and growth:
Get PDF"The people operating small farms in developing countries have to cope with the risks of these small businesses and have long faced heavy challenges. Today, these challenges are particularly severe, and the aspirations of young people on small farms have changed. Globalization and the integration of international markets are stimulating intense competition, offering some opportunities but also new risks. In light of these pressures and others, many of the world's millions of small farmers are simply not making it. Indeed, half of the world's undernourished people, three-quarters of Africa's malnourished children, and the majority of people living in absolute poverty live on small farms. The transformation of the small-farm economy is one of the biggest economic challenges of our time. For some, it entails growth into specialized, market-oriented farms; for others, part-time farming combined with off-farm rural jobs; and for others, a move out of agriculture. The pathways of transformation differ by region and location and will take decades. Policy must take a long-run view to support and guide this process efficiently, effectively, and in social fairness. The role of women farmers and their livelihoods requires particular attention. In this paper, Peter Hazell, Colin Poulton, Steve Wiggins, and Andrew Dorward address several crucial questions. Do small farms in fact have a future? In what situations can small farms succeed? What strategies are most appropriate for helping to raise small-farm productivity? The authors review both sides of the debate over the future of small farms before coming to their conclusions. Coming down firmly on the side of policy support for small farms, they point to small farms' significant potential for reducing poverty and inequity. They also clarify the differing roles of and needs for small farms in different country contexts and spell out a policy agenda for promoting small-farm development. This discussion paper is based on a literature review and the deliberations of an international workshop, “The Future of Small Farms,” organized by the International Food Policy Research Institute (IFPRI) 2020 Vision Initiative, the Overseas Development Institute (ODI), and Imperial College London in Wye, England, from June 26 to 29, 2005. (A proceedings volume for this workshop is available from IFPRI, www.ifpri.org/events/seminars/2005/smallfarms/sfproc.asp.) We hope that this discussion paper will help stimulate renewed attention among many stakeholders— including policymakers, researchers, the private sector, and nongovernmental organizations—to small-scale agricultural development. Healthy and productive small farms could serve as a crucial mechanism for achieving the poverty and hunger Millennium Development Goals. " From Foreword by Joachim von BraunPro-poor growth, Agriculture, Economic development, small farms, Poverty reduction, Sustainable livelihoods, Non-farm development, Rural-urban linkages, small farms,
Biological and pharmacological investigations of novel diamidines in animal models of human African trypanosomiasis
Get PDF"African sleeping sickness, also called human African trypanosomiasis (HAT), results from the infection of humans with either of two protozoan parasites, Trypanosoma brucei gambiense and T. b. rhodesiense. HAT is transmitted by tsetse flies (Glossina spp) and, like the vector, is found exclusively in Africa between the latitudes 14° North and 29° South. A total of 50 million people live in foci where active transmission is possible and are therefore at risk of infection; however, the annual incidence and estimated prevalence currently stand at 7139 and 30 000 cases respectively. When trypanosomes are inoculated into a human host, the resulting clinical disease is classified into a first (early) stage in which trypanosomes are localised within the haemo-lymphatic system and a second (late) stage in which trypanosomes have crossed the blood brain barrier (BBB) and invaded the central nervous system (CNS). Currently, pentamidine and suramin are used to treat the first stage of T. b. gambiense and T. b. rhodesiense HAT, respectively. On the other hand, eflornithine and the nifurtimox eflornithine combination therapy (NECT) are the prefered treatments for second stage T. b. gambiense HAT. The organoarsenic drug melarsoprol may be used for both forms of HAT but is mainly used against T. b. rhodesiense. Clearly, the therapeutic options for HAT are very limited. In addition, available drugs are associated with different levels of toxicity, especially melarsoprol which causes a post treatment reactive encephalopathy (PTRE) in 5-10% of treated patients, up to 50% of PTRE patients may die. There are also reports of high melarsoprol treatment failure rates in some foci and there is a lack of easy to use oral formulations for all the drugs. We have carried out biological and pharmacological investigations of potential new drug candidates in animal models of HAT with the objective of contributing to the development of safe, efficacious and easy to use treatments for HAT. The studies were carried out in the context of a PhD programme at the Swiss TPH/University of Basel and were anchored onto an ongoing diamidines development project of the Consortium for Parasitic Drug Development (CPDD). Vervet monkeys (Chlorocebus [Cercopithecus] aethiops) were the main model for this study. To prepare for the studies in monkeys, one prodrug (DB289) was evaluated in mouse models of first stage HAT. We obtained good activities against different trypanosome isolates, including the one that is used in the monkey model, T. b. rhodesiense KETRI2537. We further evaluated the metabolism of the prodrugs in monkey liver microsomes. In all cases, prodrugs were metabolized to generate expected intermediate and active metabolites, thus allowing us to proceed to test the compounds for safety in un-infected monkeys. We determined that in monkeys: i) diamidine toxicity was dependent on the dose and duration of dosing, ii) the plasma concentrations of active metabolites were potentially therapeutic for HAT, and iii) the dose level at which there were no observed adverse effects (NOAEL). Three prodrugs (DB289, DB844 and DB868) and one active compound (DB829) were subsequently evaluated for efficacy at dose rates that were equal or below NOAEL. In general, the prodrugs were highly active against first stage HAT after oral administration and one prodrug (DB844) had additionally an improved activity (43%) in the second stage monkey HAT model in comparison with pentamidine (0%). The intramuscularly administered parent compound DB829 was fully curative in the second stage HAT model at 2.5 mg/kg x 5 days. Our findings suggest that the two compounds (oral DB868 and intramuscular DB829) should be recommended to enter the regulatory phase of development as potential HAT drugs. Oral DB868 cured the first stage HAT model at a daily dose of 3 mg/kg for 7 days (cumulative dose, CD = 21 mg/kg) compared to a maximum tolerated daily dose of 30 mg/kg for 10 days (CD = 300 mg/kg). The efficacy, safety and pharmacokinetic profiles suggest that this compound would be a useful clinical candidate using an optimal dosing duration of 5-7 days. The second compound, intramuscular DB829, cured the second stage HAT model at a daily dose of 2.5 mg/kg for 5 days and was tolerated at 5 mg/kg for 5 days (CD = 25 mg/kg). Pharmacokinetic analysis indicated the intramuscular administration of DB829 resulted in better systemic bioavailability, thus accounting for the improved efficacy in comparison with oral dosing.
Impact evaluation of research by the International Food Policy Research Institute on agricultural trade liberalization, developing countries, and WTO's Doha negotiations:
Get PDF"This report assesses the impact of IFPRI's work on the agriculture negotiations in the WTO's Doha Round. It is set against the context of IFPRI's mission which emphasizes food security and the interests of poor people in low-income countries and underlines the importance of active engagement in policy communications to link research work to policy action. The report also traces briefly the evolution of IFPRI's work on international agricultural trade more generally, noting its broad disposition to market-oriented policy prescriptions while illuminating the very different impacts of agricultural trade liberalization on individual developing countries through detailed research at the national and household level." from Author's AbstractImpact assessment, WTO, Doha Development Agenda, International trade, Agricultural trade liberalization, Developing countries,
Prize the doubt : the life and work of Francis William Newman.
Get PDFAvailable from British Library Document Supply Centre- DSC:DX180157 / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo
