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Now showing items 56-75 of 13018
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A methane sink in the Central American high elevation páramo: Topographic, soil moisture and vegetation effects
(Elsevier B.V., 2020-03-15)Methane (CH4) is a strong greenhouse gas with a global warming potential 23 times larger than that of carbon dioxide. Characterizing ecosystems as either sources or sinks for methane and their magnitudes informs on biosphere ... -
A method to obtain rapid zoosporogenesis of Pythium insidiosum
(Kluwer Academic Publishers, 1988-10)Nine strains of Pythium insidiosum the etiologic agent of pythiosis, were inoculated on 2% water agar plus grass blades and then incubated one day at 25°C, 35°C and 37°C. Sporangium and secondary biflagellate-type zoosporas ... -
A methodological proposal to improve the descriptive paragraph writing skills of eleventh grade students from Colegio Ambientalista Isaías Retana Arias in Pérez Zéledón
(Universidad Nacional, Costa Rica, 2010)Esta investigación se realizó en el Colegio Ambientalista Isaias Retana Arias en Pérez Zeledón. Esta es una institución pública y se construyó en el año 2000. El proyecto trata sobre la mejora de las habilidades de escritura ... -
A Microscopic Model for a One Parameter Class of Fractional Laplacians with Dirichlet Boundary Conditions
(Springer Science and Business Media Deutschland GmbH, 2021)We prove the hydrodynamic limit for the symmetric exclusion process with long jumps given by a mean zero probability transition rate with infinite variance and in contact with infinitely many reservoirs with density α ... -
A mixed virtual element method for a pseudostress-based formulation of linear elasticity
(Elsevier B.V., 2019)In this paper we introduce and analyze a mixed virtual element method (mixed-VEM) for a pseudostress-displacement formulation of the linear elasticity problem with non homogeneous Dirichlet boundary conditions. We follow ... -
A mixed virtual element method for quasi-Newtonian stokes flows
(SIAM, 2018)In this paper we introduce and analyze a virtual element method (VEM) for an augmented mixed variational formulation of a class of nonlinear Stokes models arising in quasi-Newtonian fluids. While the original unknowns are ... -
A mixed virtual element method for the boussinesq problem on polygonal meshes
(Global Science Press, 2021)In this work we introduce and analyze a mixed virtual element method (mixed-VEM) for the two-dimensional stationary Boussinesq problem. The continuous formulation is based on the introduction of a pseudostress tensor ... -
A mixed virtual element method for the Brinkman problem
(Mathematical Models and Methods in Applied Sciences vol.27 no.4 707-743 2017, 2017)In this paper, we introduce and analyze a mixed virtual element method (mixed-VEM) for the two-dimensional Brinkman model of porous media flow with non-homogeneous Dirichlet boundary conditions. More precisely, we employ ... -
A Monte Carlo Study of the Photon Spectrum due to the Different Materials Used in the Construction of Flattening Filters of LINAC
(Hindawi, 2017-07-10)Different types the spectrum of photons were studied; they were emitted from the flattening filter of a LINAC Varian 2100 C/D that operates at 15 MV. The simplified geometry of the LINAC head was calculated using the MCNPX ... -
A new Costa Rican species of Drosophila visiting inflorescences of the hemi-epiphytic climber Monstera lentii (Araceae)
(Universidad Nacional, Costa Rica, 2018-09)Drosophila monsterae sp. nov. is described from 11 males and 13 females collected from the inside of closed inflorescences of Monstera lentii (Araceae) at 1810 m altitude in the Forest Reserve of Cerro de La Carpintera, ... -
A new dagger nematode, Xiphinema tica n. sp. (Nematoda: Longidoridae), from Costa Rica with updating of the polytomous key of Loof and Luc (1990)
(Springer, 2017-05-15)A new dagger nematode, Xiphinema tica n. sp., is described and illustrated from several populations extracted from soil associated with several crops and wild plants in Costa Rica. The new dagger nematode is characterised ... -
A new giant species of placented worm and the mechanism by which onychophorans weave their nets (Onychophora: Peripatidae)
(Universidad de Costa Rica, 2010)Onychophorans, or velvet worms, are poorly known and rare animals. Here we report the discovery of a new species that is also the largest onychophoran found so far, a 22cm long female from the Caribbean coastal forest of ... -
A new giant velvet worm from Costa Rica suggests absence of the genus Peripatus (Onychophora: Peripatidae) in Central Americ
(Universidad de Costa Rica, 2020-02-03)Introduction: Neotropical onychophoran taxonomy and diversity has been poorly investigated. Recent studies have discovered problems in species classification: they have questioned the accepted genera and the actual number ... -
A New Hybrid of Serpocaulon (Polypodiaceae) from Costa Rica
(Bio One Research Evolved, 2013)A new hybrid Serpocaulon 3 sessilipinnum A. Rojas & J.M. Chaves is described. The new taxon has characters intermediate between S. fraxinifolium (Jacq.) A.R. Sm. and S. ptilorhizon (Christ) A.R. Sm., which are related ... -
A new method for the detection of phospholipase A2 variants: Identification of isozymes in the venoms of newborn and adult Bothrops asper (terciopelo) snakes
(Elsevier B.V, 1988)E. Moreno, A. Alape, M. Sánchez and J. M. Gutiérrez. A new method for the detection of phospholipase A2 variants: identification of isozymes in the venoms of newborn and adult Bothrops asper (terciopelo) snakes. Toxicon ... -
A new nesting record for the jabiru in Costa Rica
(Universidad Nacional, Costa Rica, 1988)I document the first nesting record of the jabiru (Jabiru mycteria) in "Los Guatuzos" forest floodplain, Alajuela province, Costa Rica. The active nest was located in March 1995 at 10°49'23.70"N and 84°47'23.2"W. The nest ... -
A new species of Elaphoglossum Schott ex J. Sm. (Dryopteridaceae) from Costa Rica
(Universidad Nacional (Costa Rica), 2017-12)Una especie nueva de Elaphoglossum Schott ex J.Sm. Dryopteridaceae) para Costa Rica.Una especie nueva de ElaphoglossumSchott ex J. Smde la sección UndulataChrist es descrita aquí: Elaphoglossum pallidosquamum A. Rojas & ... -
A NEW SPECIES OF NEMATODE, SCLERORHABDITIS NEOTROPICALIS SP.N. (RHABDITIDA), ASSOCIATED WITH AZTECA ANTS IN CECROPIA OBTUSIFOLIA
(Nematropica, 2012-06)Sclerorhabditis neotropicalis sp. n. is described and illustrated. It can be distinguished by its body length (515-560 μm in females and 363-455 μm in males), lip region with crown-shaped lips, having acute three acute ... -
A new species of Seticeros from Costa Rica (Coleoptera, Cerambycidae, Prioninae)
(Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA), 2011)A new species of Seticeros Perger & Santos-Silva, 2010 (Prioninae: Callipogonini) from San Isidro del General, San José, Costa Rica is described and illustrated. A key to the species of Seticeros is added. -
A New Sulfur and Carbon Degassing Inventory for the Southern Central American Volcanic Arc: The Importance of Accurate Time-Series Data Sets and Possible Tectonic Processes Responsible for Temporal Variations in Arc-Scale Volatile Emissions
(AGU Publications, 2017-12-12)This work presents a new database of SO2 and CO2 fluxes from the Southern Central American Volcanic Arc (SCAVA) for the period 2015–2016. We report 300 SO2 flux measurements from 10 volcanoes and gas ratios from 11 volcanoes ...