University of Costa Rica

About: University of Costa Rica is a education organization based out in San José, Costa Rica. It is known for research contribution in the topics: Population & Venom. The organization has 9817 authors who have published 16781 publications receiving 238208 citations. The organization is also known as: UCR & Universidad de Costa Rica.

An adaptive choice of primal constrains for BDDC domain decomposition algorithms

Abstract: An adaptive choice based on parallel sums for the primal space of BDDC [1] deluxe methods [2] is analyzed. The primal constraints of a BDDC algorithm provide the global, coarse part of such a preconditioner and is of crucial importance for obtaining rapid convergence of these preconditioned conjugate gradient methods for the case of many subdomains. For problems in three dimensions, there is a need to develop algorithms and results for equivalence classes with three or more elements, e.g., subdomain edges. For this purpose, parallel sums for general equivalence classes are considered. The use of parallel sums for equivalence classes with two elements (subdomain faces) has proven very successful; see [3]. An upper bound of the square of the norm of a jump operator PD acting on the elements in a product space related to the subdomains is derived; it has been known that such a bound provides an estimate of the condition number of the BDDC algorithm; see [4]. This bound is given in terms of parallel sums of single Schur complements and sums of other Schur complements. Hence, generalized eigenvalue problems with parallel sums related to the faces and edges of the subdomains are formulated. A few eigenvectors associated with the smallest eigenvalues are selected and they generate a primal constraint. These generalized eigenvalue problems are defined in terms of the relevant Schur complements and Schur complements of these Schur complements associated with a minimal energy extension, e.g., from a subdomain edge of a three-dimensional finite element problem. Numerical results for elliptic problems verify the performance of the algorithm, using a series of experiments with regular subdomains as well as subdomains generated by a METIS mesh partitioner. There is also fast convergence for problems with a quite irregular coefficient inside the subdomains.

Energy intake and food sources of eight Latin American countries: results from the Latin American Study of Nutrition and Health (ELANS).

Abstract: The ELANS is supported by a scientific grant from the Coca-Cola Company (Atlanta, GA, USA) and by grants and/or support from ILSI Argentina, Instituto Pensi/Hospital Infantil Sabara, Universidad de Costa Rica, Pontificia Universidad Catolica de Chile, Pontificia Universidad Javeriana, Universidad Central de Venezuela/Fundacion Bengoa, Universidad San Francisco de Quito and Instituto de Investigacion Nutricional de Peru. The funders had no role in study design, data collection, analysis, the decision to publish or the preparation of this manuscript.

Implicaciones educativas de la teoría sociocultural de Vigotsky

Abstract: The purpose of this article is to analyze the sociocultural theory of Lev Vygotsky and reflect on theeducational implications of this theory in the processesteaching and learning that are organized in the school. Based on Vygotsky's postulates, are invitedthe teachers and teachers to rethink their teaching practices and promote changes in their professional work withIn order to provide a more contextualized education andsignificant to help build critical and creative people to contribute to building a more democratic and supportive.

Structural, stratigraphic, and petrologic aspects of the Arenal-Chato volcanic system, Costa Rica: Evolution of a young stratovolcanic complex

Abstract: Geologic mapping on a scale of 1:10000 and detailed stratigraphic studies of lava flows and tephra deposits of the Arenal-Chato volcanic system reveal a complex and cyclic volcanic history. This cyclicity provides insight into the evolution of magma batches during the growth of the andesitic volcanic system. The Arenal and Chato volcanoes have a central zone comprised of a lava armor and a distal zone comprised of a tephra apron. During Arenal's last two eruptive periods major craters formed near intersections of regional fractures at the lava armortephra apron transition. We suggest that such intersections are potential sites for future major explosions. The earliest rocks, i.e., the Chato lava flows, range in composition from basaltic andesite to andesite. These rocks, except for the andesitic domes of Chatito and La Espina, appear to have evolved from a common parental magma. The last active period of Chato volcano occurred 3550 B. P. The earliest known activity of Arenal volcano is 2900 B. P. Arenal lava flows have 54–56 wt% SiO2 and may be subdivided into a high-alumina group (HAG, Al2O3 = 20 wt%) and a low-alumina group (LAG, Al2O3 = 19 wt%). Compared to the HAG, the LAG also has smaller amounts of incompatible elements and higher amounts of FeO and MgO. Arenal tephra deposits were emplaced by Plinian-Sub-Plinian explosions occurring at 300±150-yr intervals. These deposits are compositionally zoned and alternate between dacite and basalt. The stratigraphy reveals an apparent magmatic cycle consisting of (a) dacitic-andesitic tephra, (b) HAG lava flows, (c) LAG lava flows, and (d) andesitic-basaltic tephra. This magmatic cycle is repeated four times during Arenal's history and is interpreted to have developed by the crystal fractionation and crystal redistribution of a single magma batch. The period of this cycle, and consequently the “life” of a magma batch, is about 800 years. If the cyclic pattern continues, a basaltic explosive phase may occur in the next 250 years.

Chemical and Morphological Characterization of Costa Rican Papaya (Carica papaya L.) Hybrids and Lines with Particular Focus on Their Genuine Carotenoid Profiles

Abstract: Papaya (Carica papaya L.) F1 hybrids and inbred lines grown in Costa Rica were screened for morphological and nutritionally relevant fruit traits. The qualitative composition of carotenoids showed great similarity, being mostly composed of free and esterified β-cryptoxanthins accompanied by β-carotene, lycopene, and biosynthetic precursors. High levels of (all-E)-lycopene and its isomers were distinctive for red-fleshed hybrids, whereas yellow-fleshed fruits were virtually devoid of lycopenes. Because carotenoid levels among the investigated hybrids and lines differed significantly, this study supports the hypothesis of an exploitable genetic variability, and a potential heterotic effect regarding carotenoid expression may be instrumental in papaya-breeding programs. Due to significantly higher levels of provitamin A carotenoids and coinciding high levels of total lycopene, particularly red-fleshed hybrids might represent prospective sources of these compounds. Furthermore, the nutritional value of some genotypes was boosted by substantial amounts of ascorbic acid (up to 73 mg/100 g of fresh weight), which correlated to total soluble solids (R(2) = 0.86).