Mixed action computations on fine dynamical lattices

We report on our first experiences in simulating Neuberger valence fermions on CLS $N_f=2$ configurations with light sea quark masses and small lattice spacings. Valence quark masses are considered that allow to explore the matching to (partially quenched) chiral perturbation theory both in the $\epsilon$- and $p$-regimes. The setup is discussed, and first results are presented for spectral observables.Comment: 7 pages. Presented at the XXVII International Symposium on Lattice Field Theory, July 26-31, 2009, Peking University, Beijing, Chin

Langlands duality for representations of quantum groups

We establish a correspondence (or duality) between the characters and the crystal bases of finite-dimensional representations of quantum groups associated to Langlands dual semi-simple Lie algebras. This duality may also be stated purely in terms of semi-simple Lie algebras. To explain this duality, we introduce an "interpolating quantum group" depending on two parameters which interpolates between a quantum group and its Langlands dual. We construct examples of its representations, depending on two parameters, which interpolate between representations of two Langlands dual quantum groups.Comment: 37 pages. References added. Accepted for publication in Mathematische Annale

Diffusion Approximations for Demographic Inference: DaDi

Models of demographic history (population sizes, migration rates, and divergence times) inferred from genetic data complement archeology and serve as null models in genome scans for selection. Most current inference methods are computationally limited to considering simple models or non-recombining data. We introduce a method based on a diffusion approximation to the joint frequency spectrum of genetic variation between populations. Our implementation, DaDi, can model up to three interacting populations and scales well to genome-wide data. We have applied DaDi to human data from Africa, Europe, and East Asia, building the most complex statistically well-characterized model of human migration out of Africa to date

Grants and debt forgiveness in Africa : a descriptive analysis

The authors analyze the effects of bilateral debt forgiveness on 32 low-income countries in Africa (1984-93). Asking whether it makes a difference for recipient countries to receive pure grants rather that official development assistance (ODA) debt relief, they focus on how one form of aid or the other affects the countries'import capacity. They conclude that: a) grants allowed recipient countries to significantly expand their import capacity for 1984-93 as grants and import capacity have been increasing since 1984. But the increasing share of concessional lending and debt relief in recent years has not allowed these countries to reduce total indebtedness nor solve debt overhang. b) the biggest recipients of debt relief also received the lion's share of the pure grants increase. Debt forgiveness and pure grants were allocated not entirely consistent with standard economic hierarchies. c) bilateral ODA debt forgiveness appears to be neutral in the sense of not having any significant impact on import capacity. During 1989-93, multilateral lending replaced the bilateral lending decrease caused by an increase in grants. d) private creditors have typically withdrawn money as grants increased. And debt relief has had a crowding-out effect on new lending. Bilateral donors are switching their development finance to Africa from concessional and non-concessional lending to a combination of pure grants and ODA relief.Payment Systems&Infrastructure,Banks&Banking Reform,Public Sector Economics&Finance,Municipal Financial Management,Public&Municipal Finance,Urban Economics,Municipal Financial Management,Banks&Banking Reform,Public Sector Economics&Finance,Public&Municipal Finance

Automatic classification of reforested Pinus SPP and Eucalyptus SPP in Mogi-Guacu, SP, Brazil, using LANDSAT data

The author has identified the following significant results. Single date LANDSAT CCTs were processed, by Image-100 to classify Pinus and Eucalyptus species and their age groups. The study area Mogi-Guagu was located in the humid subtropical climate zone of Sao Paulo. The study was divided into ten preliminary classes and featured selection algorithms were used to calculate Bhattacharyya distance between all possible pairs of these classes in the four available channels. Classes having B-distance values less than 1.30 were grouped in four classes: (1) class PE - P. elliottii, (2) class P0 - Pinus species other than P. elliotii, (3) class EY - Eucalyptus spp. under two years, and (4) class E0 - Eucalyptus spp. more than two years old. The percentages of correct classification ranged from 70.9% to 94.12%. Comparisons of acreage estimated from the Image-100 with ground truth data showed agreement. The Image-100 percent recognition values for the above four classes were 91.62%, 87.80%, 89.89%, and 103.30%, respectively