Elephant movement patterns in relation to human inhabitants in and around the Great Limpopo Transfrontier Park.

The presence of humans and African elephants (Loxodonta africana) in the Great Limpopo Transfrontier Park can create situations of potential human–elephant conflict. Such conflict will likely be exacerbated as elephant and human populations increase, unless mitigation measures are put in place. In this study we analysed the movement patterns of 13 collared adult African elephants from the northern Kruger National Park over a period of eight years (2006–2014). We compared the occurrence and displacement rates of elephant bulls and cows around villages in the Limpopo National Park and northern border of the Kruger National Park across seasons and at different times of the day. Elephants occurred close to villages more often in the dry season than in the wet season, with bulls occurring more frequently around villages than cows. Both the bulls and the cows preferred to use areas close to villages from early evening to midnight, with the bulls moving closer to villages than the cows. These results suggest that elephants, especially the bulls, are moving through the studied villages in Mozambique and Zimbabwe at night and that these movements are most common during the drier months when resources are known to be scarce. Conservation implications: Elephants from the Kruger National Park are moving in close proximity to villages within the Great Limpopo Transfrontier Park. Resettlement of villages within and around the park should therefore be planned away from elephant seasonal routes to minimise conflict between humans and elephants

Feasibility of organo-beryllium target mandrels using organo-germanium PECVD as a surrogate

Inertial Confinement Fusion capsules incorporating beryllium are becoming attractive for use in implosion experiments designed for modest energy gain. This paper explores the feasibility of chemical vapor deposition of organo-beryllium precursors to form coating materials of interest as ablators and fuel containers. Experiments were performed in a surrogate chemical system utilizing tetramethylgermane as the organometallic precursor. Coatings with up to 60 mole percent germanium were obtained. These coatings compare favorably with those previously reported in the literature and provide increasing confidence that a similar deposition process with an organo-beryllium precursor would be successful

Introduction to Isolated Horizons in Numerical Relativity

We present a coordinate-independent method for extracting mass (M) and angular momentum (J) of a black hole in numerical simulations. This method, based on the isolated horizon framework, is applicable both at late times when the black hole has reached equilibrium, and at early times when the black holes are widely separated. We show how J and M can be determined in numerical simulations in terms of only those quantities which are intrinsic to the apparent horizon. We also present a numerical method for finding the rotational symmetry vector field (required to calculate J) on the horizon.Comment: 14 pages, revtex4, 7 figures. Final PRD versio

Généralisation du diagramme de Voronoï et placement de formes géométriques complexes dans un nuage de points.

La géométrie algorithmique est une discipline en pleine expansion dont l'objet est la conception d'algorithmes résolvant des problèmes géométriques. De tels algorithmes sont très utiles notamment dans l'ingénierie, l'industrie et le multimédia. Pour être performant, il est fréquent qu'un algorithme géométrique utilise des structures de données spécialisées.Nous nous sommes intéressés à une telle structure : le diagramme de Voronoï et avons proposé une généralisation de celui-ci. Ladite généralisation résulte d'une extension du prédicat du disque vide (prédicat propre à toute région de Voronoï) à une union de disques. Nous avons analysé les régions basées sur le prédicat étendu et avons proposé des méthodes pour les calculer par ordinateur.Par ailleurs, nous nous sommes intéressés aux problèmes de placement de formes , thème récurrent en géométrie algorithmique. Nous avons introduit un formalisme universel pour de tels problèmes et avons, pour la première fois, proposé une méthode de résolution générique, en ce sens qu'elle est apte à résoudre divers problèmes de placement suivant un même algorithme.Nos travaux présentent, d'une part, l'avantage d'élargir le champ d'application de structures de données basées sur Voronoï. D'autre part, ils facilitent de manière générale l'utilisation de la géométrie algorithmique, en unifiant définitions et algorithmes associés aux problèmes de placement de formes.Computational geometry is an active branch of computer science whose goal is the design of efficient algorithms solving geometric problems. Such algorithms are useful in domains like engineering, industry and multimedia. In order to be efficient, algorithms often use special data structures.In this thesis we focused on such a structure: the Voronoi diagram. We proposed a new generalized diagram. We have proceeded by extending the empty disk predicate (satisfied by every Voronoi region) to an arbitrary union of disks. We have analyzed the new plane regions based on the extended predicate, and we designed algorithms for computing them.Then, we have considered another topic, which is related to the first one: shape placement problems. Such problems have been studied repeatedly by researchers in computational geometry. We introduced new notations along with a global framework for such problems. We proposed, for the first time a generic method, which is able to solve various placement problems using a single algorithm.Thus, our work extend the scope of Voronoi based data structures. It also simplifies the practical usage of placement techniques by unifying the associated definitions and algorithms.MULHOUSE-SCD Sciences (682242102) / SudocSudocFranceF

1/Nc1/N_c Expansion for Excited Baryons

We derive consistency conditions which constrain the possible form of the strong couplings of the excited baryons to the pions. The consistency conditions follow from requiring the pion-excited baryon scattering amplitudes to satisfy the large-N_c Witten counting rules and are analogous to consistency conditions used by Dashen, Jenkins and Manohar and others for s-wave baryons. The consistency conditions are explicitly solved, giving the most general allowed form of the strong vertices for excited baryons in the large-N_c limit. We show that the solutions to the large-N_c consistency conditions coincide with the predictions of the nonrelativistic quark model for these states, extending the results previously obtained for the s-wave baryons. The 1/N_c corrections to these predictions are studied in the quark model with arbitrary number of colors N_c.Comment: 56 pages, REVTeX; one new Appendix added containing a discussion of the results in the language of quark operator

Strings on conifolds from strong coupling dynamics, part I

A method to solve various aspects of the strong coupling expansion of the superconformal field theory duals of AdS_5 x X geometries from first principles is proposed. The main idea is that at strong coupling the configurations that dominate the low energy dynamics of the field theory compactified on a three sphere are given by certain non-trivial semi-classical configurations in the moduli space of vacua. We show that this approach is self-consistent and permits one to express most of the dynamics in terms of an effective N=4 SYM dynamics. This has the advantage that some degrees of freedom that move the configurations away from moduli space can be treated perturbatively, unifying the essential low energy dynamics of all of these theories. We show that with this formalism one can compute the energies of strings in the BMN limit in the Klebanov-Witten theory from field theory considerations, matching the functional form of results found using AdS geometry. This paper also presents various other technical results for the semiclassical treatment of superconformal field theories.Comment: 52 pages, JHEP3 styl

A framework for the local information dynamics of distributed computation in complex systems

The nature of distributed computation has often been described in terms of the component operations of universal computation: information storage, transfer and modification. We review the first complete framework that quantifies each of these individual information dynamics on a local scale within a system, and describes the manner in which they interact to create non-trivial computation where "the whole is greater than the sum of the parts". We describe the application of the framework to cellular automata, a simple yet powerful model of distributed computation. This is an important application, because the framework is the first to provide quantitative evidence for several important conjectures about distributed computation in cellular automata: that blinkers embody information storage, particles are information transfer agents, and particle collisions are information modification events. The framework is also shown to contrast the computations conducted by several well-known cellular automata, highlighting the importance of information coherence in complex computation. The results reviewed here provide important quantitative insights into the fundamental nature of distributed computation and the dynamics of complex systems, as well as impetus for the framework to be applied to the analysis and design of other systems.Comment: 44 pages, 8 figure