Browsing Facultad de Ciencias Exactas y Naturales by Title
Now showing items 2457-2476 of 2624
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The challenges of mathematics education for Indigenous teacher training
(Intercultural Education, 2015-12-15)In this article, I outline research carried out on in an Ethnomathematics course designed to train Indigenous teachers in Costa Rica, in which the following ethnic groups participated: Ngabes, Bribris, and Cabecares. The ... -
The conservation status of Costa Rican velvet worms (Onychophora): geographic pattern, risk assessment and comparison with New Zealand velvet worms
(Universidad Estatal a Distancia (Costa Rica), 2019-12)Introduction: Charismatic species, like the panda, play an important role in conservation, and velvet worms arguably are charismatic worms. Thanks to their extraordinary hunting mechanism, they have inspired from a ... -
The direct effect on geoid computations
(Universidad Nacional (Costa Rica), 2004)La técnica más popular para la reducción de observaciones gravimétricas al geoide es el método de condensación de Helmert. Dos maneras deferentes de aplicar dicha reducción son estudiadas: el enfoque clásico (Wang y Rapp, ... -
The downward continuation of the disturbing potential based on poisson's integral
(Universidad Nacional (Costa Rica), 2004)En este artículo se prueban y valoran dos métodos diferentes para la realización de la continuación descendente de potencial perturbante. La importancia del potencial perturbante en geodesia reside en que éste es fundamental ... -
The effect of high rearing densities on the growth of juveniles of the cichlid, cichlasoma managuense
(Universidad Nacional, Costa Rica, 1992-01-01)The effect of high density culture on the growth of juvenile jaguar cichlids was investigated. Mean growth rate decreased with density, while the growth rate of the largest fishes was not affected. Reduction in mean growth ... -
The effect of Ibuprofen on female and male reproduction of the open thelyca marine shrimp, Litopenaeus
(Aquaculture Research, 2013-03-11)A research was designed to explore the effect of ibuprofen (IBU) as an intervening agent for prostaglandin biosynthesis on male and female reproduction of three species of Litopenaeus. Ovarian maturation was studied in L. ... -
The effect of solution environment and the electrostatic factor on the crystallisation of desmotropes of irbesartan
(Royal Society of Chemistry, 2019)The experimental conditions necessary for stabilising irbesartan (IBS) tautomers in solution and selectively obtaining the desmotropic crystal forms are presented herein. 1H and 2H tautomers were stabilized in specific ... -
The first experiences of the UNA STEM network
(Centro Latinoamericano de Estudios en Informática (Chile), 2021-10)The UNA STEM Network is a proposal of several academics from the Faculties of Exact and Natural Sciences, and Earth and Sea of the National University, which aims to generate appreciation for science in Costa Rican primary ... -
The first gynandromorph of the Neotropical bee Megalopta amoena (Spinola, 1853) (Halictidae) with notes on its circadian rhythm
(Pensoft Publishers, 2020-04-27)Gynandromorphy is an anomaly that results in an organism phenotypically expressing both male and female characteristics. Here we describe the first gynandromorph of the bee species Megalopta amoena (Spinola, 1853) (Halictidae, ... -
The geographic distribution of Costa Rican velvet worms (Onychophora: Peripatidae)
(Revista de Biologia Tropical vol.64 no.4 1401-1414 2016, 2016-06-06)Velvet worms, “peripatus” or onychophorans, are “living fossils” that were geographically widespread in Cambrian seas but now occur exclusively on terrestrial habitats. The only extant species studied in some detail are ... -
The growth of juvenile jaguar guapote (Cichlasoma managuense) fed diets with different carbohydrate levels
(Universidad Nacional (Costa Rica), 1995-06-27)Se evaluó el crecimiento de juveniles del guapote tigre (Cichlasoma managuense) alimentado con dietas isocalóricas conteniendo niveles de carbohidrato del 11 al 36 por ciento. El experimento se realizó en un sistema de ... -
The histological structure of the androgenic gland and cellular cord of the male reproductive system of adult litopenaeus and rimapenaeus byrdi
(2012-05-01)The current knowledge of the precise extension and location of the androgenic gland (AG) in the genera Litopenaeus and Rimapenaeus is partial. Therefore, we analyzed the complete structure of the AG and cellular cord ... -
The Influence of IoT Simulation in the Learning Process: A Case Study
(Association for Computing Machinery, 2020-03-28)Internet of things (IoT) is a relatively novel technology which provides connection between things. It was presented for the first time by Kevin Ashton in 90´s.The software and hardware development of IoT is not growing ... -
The interplay between irrigation and fruiting on branch growth and mortality, gas exchange and water relations of coffee trees
(Oxford University Press, 2021)The overall coordination between gas exchanges and plant hydraulics may be affected by soil water availability and source-to-sink relationships. Here we evaluated how branch growth and mortality, leaf gas exchange and ... -
The magnetic dispersion
(Editorial de la Universidad Nacional, 1985-01-01)We present a study of the elastic scattering of an electron in a constant homogeneous magnetic field. The dependency of the cross section on the electron spin orientation is given. If the spin polarization is along or ... -
The manufacture and properties of oil palm and pineapple leaf fiberboard panels
(WIT Transactions on Ecology and the Environment, 2014)Particleboards were manufactured from oil palm fruit, the oil palm mesocarp fiber of Elaeis guineensis, the leaves of pineapple (Ananas comosus) and the sawdust from three fast-growing species of trees (Gmelina arborea, ... -
The opossum and other didelphids in the cultures of Costa Rican society and indigenous peoples: an approach to ecology and conservation
(Cold Spring Harbor Laboratory (Estados Unidos), 2024)The opossum Didelphis marsupialis, commonly referred to as the zorro pelón in Costa Rica, is a marsupial that holds significant representation in both Costa Rican and indigenous cultures, such as the Talamanca natives. ... -
The persistent embrace of onychophorans: What determines copulation duration in velvet worms?
(Universidad de Costa Rica (Costa Rica), 2019)In the only onychophorans mating that has been photographed, instead of fleeing, the couple remained together despite being manipulated. Why? The duration of copulation in onychophoran sis possibly controlled by the female, ... -
The polynucleotide kinase 3′-phosphatase gene (PNKP) is involved in Charcot-Marie-Tooth disease (CMT2B2) previously related to MED25
(Springer, 2018-07-24)Charcot-Marie-Tooth disease (CMT) represents a heterogeneous group of hereditary peripheral neuropathies. We previously reported a CMT locus on chromosome 19q13.3 segregating with the disease in a large Costa Rican family ... -
The proteolytic digestive activity and growth during ontogeny of Parachromis dovii larvae (Pisces: Cichlidae) using two feeding protocols
(2014)Se evaluó la actividad proteolítica digestiva y el crecimiento de larvas de Parachromis dovii durante la ontogenia en un sistema de recirculación utilizando dos estrategias de alimentación durante un período de 28 días. ...