University of Los Andes, Venezuela
Merida, Venezuela

The University of the Andes is the second-oldest university in Venezuela, whose main campus is located in the city of Mérida, Venezuela. ULA is the largest public university in the Venezuelan Andes, having one of the largest student bodies in the country. Wikipedia.

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Agency: European Commission | Branch: FP7 | Program: CSA | Phase: INFRA-2007-1.2.3;INFRA-2007-1.2-03 | Award Amount: 5.11M | Year: 2008

EELA-2 aims to build, on the current EELA e-Infrastructure, a high capacity, production-quality, scalable Grid Facility providing round-the-clock, worldwide access to distributed computing, storage and network resources for a wide spectrum of applications from European and Latin American scientific communities. The project will provide an empowered Grid Facility with versatile services fulfilling application requirements and ensure the long-term sustainability of the e-Infrastructure beyond the term of the project. The specific EELA-2 objectives are: - Build a Grid Facility by: Expanding the current EELA e-Infrastructure to consist of more production sites mobilising more computing nodes and more storage space, at start of the project and to further grow storage over the duration of the project; Providing, in collaboration with related projects (e.g. EGEE), the full set of Grid Services needed by all types of scientific applications; Supporting applications various types (from classical off-line data processing up to control and data acquisition of scientific instruments), selected against well defined criteria (including grid added value, suitability for Grid deployment, outreach/potential impact); - Ensure the Grid Facility sustainability: Through the already established and new contacts with policy/decision makers, collaborating with RedCLARA and NRENs and supporting the ongoing creation of e-Science Initiatives and/or National Grid initiatives (NGI). Building the support of the e-Infrastructure to provide a complete set of Global Services from a Central Operation Centre and to pave the way for the creation of Regional Operation Centres in Latin America: Attracting new applications; Making available knowledge of EELA-2 Grid Facility to all potential users, developers, and decision makers through an extensive Training and Dissemination program; Creating knowledge repositories federated with the EGEE ones.

Agency: European Commission | Branch: FP7 | Program: CPCSA | Phase: INFRA-2010-1.2.3 | Award Amount: 2.76M | Year: 2010

The GISELA objective is to guarantee the long-term sustainability of the European Latin American e-Infrastructure and thus ensure the continuity and enhancement of the Virtual Research Communities (VRC) using it. The project will focus on:\n\tImplementing the Latin American Grid Initiative (LGI) sustainability model rooted on National Grid Initiatives (NGI) or Equivalent Domestic Grid Structures (EDGS), in association with CLARA and collaborating with EGI;\n\tProviding VRCs with the e-Infrastructure and Application-related Services required to improve the effectiveness of their research, addressing both:\no\tCurrent EELA-2 small User Communities;\no\tLarger VRCs through Specialised Support Centres (SSCs).\nThe GISELA mission is twofold:\n- Ensure the sustainability of the EU-LA e-Infrastructure\nThe sustainability of the EU part of the e-Infrastructure being cared of by EGI, GISELA will concentrate on its LA component. The tasks, at each level of the e-Infrastructure are:\n\tInstitution: Get all Services fully operational in the Resource Centre (RC);\n\tCountry: Implement all Grid Operation Centre (GOC) Services;\n\tContinent: Implement all Grid & Network Support Centres (GSC, NSC) Services;\n\tSupport a catchall GOC.\n- Support Virtual Research Communities\nThe support will encompass:\n\tUser Support:\no\tProvide access to the EU-LA Infrastructure to VOs represented in GISELA (HEP, Life Sciences, Earth Sciences, etc.);\no\tPublicise and support the GISELA e-Infrastructure and Application Services;\no\tCollaborate with VRCs or SSCs to the development of integrated services (e.g. gateways).\n\tTraining & Dissemination activities\no\tOrganisation of tutorials for single users and VRCs;\no\tCoordinate dissemination actions, workshops, Conferences;\no\tProduce dissemination material.\nGrid Services for VRCs will be provided by CLARA on the basis of a business plan using a Life Cycle Product Management (LCPM) approach.

Herrera L.,University of the Basque Country | Barreto W.,University of Los Andes, Venezuela
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

We set up the general formalism to model polytropic Newtonian stars with anisotropic pressure. We obtain the corresponding Lane-Emden equation. A heuristic model based on an ansatz to obtain anisotropic matter solutions from known solutions for isotropic matter is adopted to illustrate the effects of the pressure anisotropy on the structure of the star. In particular, we calculate the Chandrasekhar mass for a white dwarf. It is clearly displayed how the Chandrasekhar mass limit changes depending on the anisotropy. Prospective astrophysical applications of the proposed approach are discussed. © 2013 American Physical Society.

Herrera L.,University of the Basque Country | Barreto W.,University of Los Andes, Venezuela
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

We set up in detail the general formalism to model polytropic general relativistic stars with anisotropic pressure. We shall consider two different possible polytropic equations, all of which yield the same Lane-Emden equation in the Newtonian limit. A heuristic model based on an ansatz to obtain anisotropic matter solutions from known solutions for isotropic matter is adopted to illustrate the effects of the pressure anisotropy on the structure of the star. In this context, the Tolman mass, which is a measure of the active gravitational mass, is invoked to explain some features of the models. Prospective extensions of the proposed approach are pointed out. © 2013 American Physical Society.

Paredes J.L.,University of Los Andes, Venezuela | Arce G.R.,University of Delaware
IEEE Transactions on Signal Processing | Year: 2011

In this paper, we propose a simple and robust algorithm for compressive sensing (CS) signal reconstruction based on the weighted median (WM) operator. The proposed approach addresses the reconstruction problem by solving a l 0-regularized least absolute deviation (l0-LAD) regression problem with a tunable regularization parameter, being suitable for applications where the underlying contamination follows a statistical model with heavier-than-Gaussian tails. The solution to this regularized LAD regression problem is efficiently computed, under a coordinate descent framework, by an iterative algorithm that comprises two stages. In the first stage, an estimation of the sparse signal is found by recasting the reconstruction problem as a parameter location estimation for each entry in the sparse vector leading to the minimization of a sum of weighted absolute deviations. The solution to this one-dimensional minimization problem turns out to be the WM operator acting on a shifted-and-scaled version of the measurement samples with weights taken from the entries in the measurement matrix. The resultant estimated value is then passed to a second stage that identifies whether the corresponding entry is relevant or not. This stage is achieved by a hard threshold operator with adaptable thresholding parameter that is suitably tuned as the algorithm progresses. This two-stage operation, WM operator followed by a hard threshold operator, adds the desired robustness to the estimation of the sparse signal and, at the same time, ensures the sparsity of the solution. Extensive simulations demonstrate the reconstruction capability of the proposed approach under different noise models. We compare the performance of the proposed approach to those yielded by state-of-the-art CS reconstruction algorithms showing that our approach achieves a better performance for different noise distributions. In particular, as the distribution tails become heavier the performance gain achieved by the proposed approach increases significantly. © 2011 IEEE.

Aguilar J.,University of Los Andes, Venezuela
Applied Soft Computing Journal | Year: 2013

We study in this work the problem of adaptation on cognitive maps (CMs). We review different approaches of adaptation for CM, based on the idea that the causal relationships of the CM change during their phase of execution (runtime). Particularly, we study three dynamic causal relationships: the first one where the relationships between the concepts are defined as fuzzy rules, and the concepts and the relationship are fuzzy variables; the second one where mathematical models that describe the real system are used to define the causal relationships; and finally, in the last one the causal relationships are defined by generic logic rules based on the state of the concepts of the map. Each one can be used to model different types of systems, because each one exploits specific characteristics of the modeled system. These approaches are tested in different problems, giving very good results, and demonstrating that the utilization of CM as dynamic models is reliable and good. © 2012 Elsevier B.V.

Gonzalez-Cortes S.L.,University of Los Andes, Venezuela | Imbert F.E.,University of Los Andes, Venezuela
Applied Catalysis A: General | Year: 2013

The recent progress in solution combustion synthesis (SCS)-based preparation approaches in the synthesis of solid catalysts is discussed. This integrated overview includes not only the current understanding of the SCS chemistry and catalyst properties but also catalyst applications. SCS-based methods have had a variety of applications in heterogeneous catalysis including oxidation reactions, exhaust emission control, hydrogenation reactions, hydrogen production, and photocatalytic processes. The effects of using the fuel as chelating agent and reducing agent for the production of nanosized catalysts are also presented. Finally, the future of this important topic is discussed. © 2012 Elsevier B.V.

The effect of group improvisational music therapy on depression in adolescents and adults with substance abuse was investigated. It was hypothesized that group improvisational music therapy would relieve depressive symptoms. Twenty-four Spanish-speaking patients receiving treatment for substance abuse at Fundación José Felix Ribas (FJFR) in Mérida-Venezuela participated in the study. Participants completed the Beck Depression Inventory (BDI) and the Hamilton Rating Scale for Depression (HRSD) before being randomly assigned to experimental or control groups, each consisting of three cohort groups recruited over a nine-month period. The experimental group received 12 group improvisation sessions over a three-month period, along with the standard treatment program provided at the facility, and the control group received only the standard treatment program. Post-test measures were completed at the end of each three-month treatment cycle. Differences between the groups (pre-test-post-test scores) were calculated (Mann-Whitney U Test). Results showed that both groups were equally matched on all pre-test measures. As for post-test measures, significant differences were found between the groups on HRSD but not the BDI. The experimental group was significantly less depressed after treatment than the control group, as measured by the HRSD. Improvisational music therapy led to statistically significant greater improvements in psychologist-rated depression (HRSD) when compared with the regular treatment program alone; improvisational music therapy had a clinically significant effect. Among limitations of the study were: a small sample size and the absence of a depression assessment tool for substance abuse. © 2011 The Grieg Academy Music Therapy Research Centre.

Ferrin I.,University of Los Andes, Venezuela
Planetary and Space Science | Year: 2010

In this work we have compiled 37,692 observations of 27 periodic and non-periodic comets to create the secular light curves (SLCs), using two plots per comet. The data have been reduced homogeneously. Our overriding goal is to learn the properties of the ensemble of comets. More than 30 parameters are listed, of which over ∼20 are new and measured from the plots. We define two ages for a comet using activity as a proxy, the photometric age P-AGE, and the time-age, T-AGE. It is shown that these parameters are robust, implying that the input data can have significant errors but P-AGE and T-AGE come out with small errors. This is due to their mathematical definition. It is shown that P-AGE classifies comets by shape of their light curve. The value of this Atlas is twofold: The SLCs not only show what we know, but also show what we do not know, thus pointing the way to meaningful observations. Besides their scientific value, these plots are useful for planning observations. The SLCs have not been modeled, and there is no cometary light curve standard model as there is for some variable stars (i.e. eclipsing binaries). Comets are classified by age and size. In this way it is found that 29P/Schwassmann-Wachmann 1 is a baby goliath comet, while C/1983 J1 Sugano-Saigusa-Fujikawa is a middle age dwarf. There are new classes of comets based on their photometric properties. The secular light curves presented in this Atlas exhibit complexity beyond current understanding. © 2009 Elsevier Ltd. All rights reserved.

Barreto W.,University of Los Andes, Venezuela
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014

Associated to the unique 4-parametric subgroup of translations, normal to the Bondi-Metzner-Sachs group, there exists a generator of the temporal translation asymptotic symmetry. Such a descriptor of the motion along the conformal orbit near null infinity is propagated to finite regions. This allows us to observe the global energy conservation even in extreme situations near the critical behavior of the massless scalar field collapse in spherical symmetry. © 2014 American Physical Society.

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