On computing distance function for Level Set Method using USFEM/Rothe as stabilized formulation

En este trabajo se ha utilizado la formulación estabilizada de elementos finitos Unusual Stabilized Finite Element Method (USFEM) asociada al método de Rothe para resolver el problema del redistanciamiento en el método de Funciones de Nivel. Se ha utilizado el método de Rothe primero para el avance de la solución en el pseudotiempo y la formulación USFEM para la solución del problema advectivo–reactivo en estado estacionario, para cada paso de tiempo resultante. Se han hecho ejemplos en 2D y se han comparado sus resultados con el esquema de estabilización SUPG, incrementado con un operador de captura de discontinuidades no lineal.In this work we use the Unusual Stabilized Finite Element Method (USFEM) associated to Rothes method for solving the redistancing problem in the Level Set Method . Rothes method is used first for advancing the solution in (pseudo)time and USFEM for solving the resulting steady advective–reaction problem in each time step. Several 2D problems are solved and results compared with SUPG scheme supplemented with a nonlinear discontinuity–capturing operator.Peer Reviewe

Kahler Anomalies in Supergravity and Flux Vacua

We review the subject of Kahler anomalies in gauged supergravity, emphasizing that field equations are inconsistent when the Kahler potential is non-invariant under gauge transformations or when there are elementary Fayet-Iliopoulos couplings. Flux vacua solutions of string theory with gauged U(1) shift symmetries appear to avoid this problem. The covariant Kahler anomalies involve tensors which are composite functions of the scalars as well as the gauge field strength and space-time curvature tensors. Anomaly cancellation conditions will be discussed in a sequel to this paper.Comment: 29 pages; v2: revised presentation, section on Fayet-Iliopoulos couplings cut, effects of gauginos on anomalies included, references adde

Modeling and behavior of the simulation of electric propagation during deep brain stimulation

Deep brain stimulation (DBS) is an effective treatment for Parkinson's disease. In the literature, there are a wide variety of mathematical and computational models to describe electric propagation during DBS; however unfortunately, there is no clarity about the reasons that justify the use of a specific model. In this work, we present a detailed mathematical formulation of the DBS electric propagation that supports the use of a model based on the Laplace Equation. Moreover, we performed DBS simulations for several geometrical models of the brain in order to determine whether geometry size, shape and ground location influence electric stimulation prediction by using the Finite Element Method (FEM). Theoretical and experimental analysis show, firstly, that under the correct assumptions, the Laplace equation is a suitable alternative to describe the electric propagation, and secondly, that geometrical structure, size and grounding of the head volume affect the magnitude of the electric potential, particularly for monopolar stimulation. Results show that, for monopolar stimulation, basic and more realistic models can differ more than 2900%

Systematic Investigation of Nucleon Knockout around 132Sn

Peer reviewe

Shrinking a large dataset to identify variables associated with increased risk of Plasmodium falciparum infection in Western Kenya

Large datasets are often not amenable to analysis using traditional single-step approaches. Here, our general objective was to apply imputation techniques, principal component analysis (PCA), elastic net and generalized linear models to a large dataset in a systematic approach to extract the most meaningful predictors for a health outcome. We extracted predictors for Plasmodium falciparum infection, from a large covariate dataset while facing limited numbers of observations, using data from the People, Animals, and their Zoonoses (PAZ) project to demonstrate these techniques: data collected from 415 homesteads in western Kenya, contained over 1500 variables that describe the health, environment, and social factors of the humans, livestock, and the homesteads in which they reside. The wide, sparse dataset was simplified to 42 predictors of P. falciparum malaria infection and wealth rankings were produced for all homesteads. The 42 predictors make biological sense and are supported by previous studies. This systematic data-mining approach we used would make many large datasets more manageable and informative for decision-making processes and health policy prioritization

Coulomb and nuclear excitations of narrow resonances in Ne-17

New experimental data for dissociation of relativistic 17Ne projectiles incident on targets of lead, carbon, and polyethylene targets at GSI are presented. Special attention is paid to the excitation and decay of narrow resonant states in 17Ne. Distributions of internal energy in the O15+p+p three-body system have been determined together with angular and partial-energy correlations between the decay products in different energy regions. The analysis was done using existing experimental data on 17Ne and its mirror nucleus 17N. The isobaric multiplet mass equation is used for assignment of observed resonances and their spins and parities. A combination of data from the heavy and light targets yielded cross sections and transition probabilities for the Coulomb excitations of the narrow resonant states. The resulting transition probabilities provide information relevant for a better understanding of the 17Ne structure

Quasi-free neutron and proton knockout reactions from light nuclei in a wide neutron-to-proton asymmetry range

The quasi-free scattering reactions 11C(p,2p) and 10,11,12C(p,pn) have been studied in inverse kinematics at beam energies of 300–400 MeV/u at the R3B-LAND setup. The outgoing proton-proton and proton-neutron pairs were detected in coincidence with the reaction fragments in kinematically complete measurements. The efficiency to detect these pairs has been obtained from GEANT4 simulations which were tested using the 12C(p,2p) and 12C(p,pn) reactions. Experimental cross sections and momentum distributions have been obtained and compared to DWIA calculations based on eikonal theory. The new results reported here are combined with previously published cross sections for quasi-free scattering from oxygen and nitrogen isotopes and together they enable a systematic study of the reduction of single-particle strength compared to predictions of the shell model over a wide neutron-to-proton asymmetry range. The combined reduction factors show a weak or no dependence on isospin asymmetry, in contrast to the strong dependency reported in nucleon-removal reactions induced by nuclear targets at lower energies. However, the reduction factors for (p,2p) are found to be 'significantly smaller than for (p,pn) reactions for all investigated nuclei.German Federal Ministry of Education and Research | Ref. BMBF 05P2015RDFN1German Federal Ministry of Education and Research | Ref. 05P15WOFNAEuropean Commission | Ref. FP7, ENSAR, n. 262010Comisión Interministerial de Ciencia y Tecnología (CICYT) | Ref. FPA2012-32443Comisión Interministerial de Ciencia y Tecnología (CICYT) | Ref. FPA2015-64969-07387Comisión Interministerial de Ciencia y Tecnología (CICYT) | Ref. FPA2015-69640-C2-1-PSwedish Research Council | Ref. 621-2011-5324National Science Foundation, EE. UU. | Ref. n. 1415656Department of Energy, EE. UU. | Ref. n. DE-FG02-08ER41533Fundação para a Ciência e a Tecnologia | Ref. PTDC/FIS/ 103902/200

Seasonal drought limits tree species across the Neotropics

Within the tropics, the species richness of tree communities is strongly and positively associated with precipitation. Previous research has suggested that this macroecological pattern is driven by the negative effect of water-stress on the physiological processes of most tree species. This process implies that the range limits of taxa are defined by their ability to occur under dry conditions, and thus in terms of species distributions it predicts a nested pattern of taxa distribution from wet to dry areas. However, this ‘dry-tolerance’ hypothesis has yet to be adequately tested at large spatial and taxonomic scales. Here, using a dataset of 531 inventory plots of closed canopy forest distributed across the Western Neotropics we investigated how precipitation, evaluated both as mean annual precipitation and as the maximum climatological water deficit, influences the distribution of tropical tree species, genera and families. We find that the distributions of tree taxa are indeed nested along precipitation gradients in the western Neotropics. Taxa tolerant to seasonal drought are disproportionally widespread across the precipitation gradient, with most reaching even the wettest climates sampled; however, most taxa analysed are restricted to wet areas. Our results suggest that the ‘dry tolerance’ hypothesis has broad applicability in the world's most species-rich forests. In addition, the large number of species restricted to wetter conditions strongly indicates that an increased frequency of drought could severely threaten biodiversity in this region. Overall, this study establishes a baseline for exploring how tropical forest tree composition may change in response to current and future environmental changes in this region