Browsing Facultad de Ciencias Exactas y Naturales by Title
Now showing items 1665-1684 of 2667
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Isolation and characterization of partial insulin-like androgenic gland hormone gene from distal terminal ampoules of three marine shrimp Penaeus species from the Eastern Pacific
(2018)The expansion of the shrimp industry depends on scientific advances related to the understanding of reproductive endocrinology that allows the development of aquaculture programs based on biotechnology. An insulin ... -
Isolation and partial purification of a hemolytic sphingomyelin-inhibitable fraction from the sea anemone Anthopleura nigrescens
(2014-03)Actinoporins are highly hemolytic pore-forming proteins with a molecular mass of around 20 kDa and high affinity for sphingomyelin-containing membranes. On the crude extract of the sea anemone Anthopleura nigrescens, the ... -
Isolation of ammonium- and nitrite-oxidizing bacterial strains from soil, and their potential use in the reduction of nitrogen in household waste water
(Universidad de Costa Rica, 2017-12-01)Currently, nitrogen has become the main element of water pollution, causing riverine, lacustrine and coastal eutrophication. The continuous contamination of aquifers and the absence of planned water resource utilization, ... -
Isolation on a remote island: genetic and morphological differentiation of a cosmopolitan odonate
(Nature Publishing Group, 2019-06-01)Although low levels of genetic structure are expected in highly widespread species, geographical and/or ecological factors can limit species distributions and promote population structure and morphological differentiation. ... -
Isomerization of fatty acids: A cellular barrier mechanism in nanotechnology?
(Journal of Nanoscience and Nanotechnology Vol.17 1-9, 2017-01)This work is a kinetic study of the coupling reaction of 2-mercaptoethanol with methyl undecenoate and with methyl oleate through " click " chemistry. Reversibility and reactivity of each system were followed through Fourier ... -
Isotope hydrology and baseflow geochemistry in natural and human-altered watersheds in the Inland Pacific Northwest, USA
(2015-02-18)This study presents a stable isotope hydrology and geochemical analysis in the inland Pacific Northwest (PNW) of the USA. Isotope ratios were used to estimate mean transit times (MTTs) in natural and human-altered watersheds ... -
Isotope hydrology of a tropical coffee agroforestry watershed: Seasonal and event-based analyses
(Wiley & Sons, 2018)Stable isotope variations are extremely useful for flow partitioning within the hydrologic cycle but remain poorly understood throughout the tropics, particularly in watersheds with rapidly infiltrating soils, such as ... -
Isotopic composition and major ion concentrations of national and international bottled waters in Costa Rica
(Elsevier (Países Bajos), 2021)Global bottled water consumption has largely increased (14.35 billion gallons in 2020) [1], [2], [3], [4], [5] during the last decade since consumers are demanding healthier and safer forms of rehydration. Bottled water ... -
Isotopic composition in precipitation and groundwater in the northern mountainous region of the Central Valley of Costa Rica
(Taylor & Francis, 2016)The linkage between precipitation and recharge is still poorlyunderstood in the Central America region. This study focuses onstable isotopic composition in precipitation and groundwater in the northern mountainous region ... -
Isotopic variability (δ18O, δ2 H and d-excess) during rainfall events of the north American monsoon across the Sonora River Basin, Mexico
(Elsevier Ltd, 2021)The economic activities of the Sonora strongly depend on groundwater extraction, which is generally of recent meteoric origin. Understanding the hydrological functioning in this semi-arid region, located in northwestern Mexico, ... -
Key drivers controlling stable isotope variations in daily precipitation of Costa Rica: Caribbean Sea versus Eastern Pacific Ocean moisture sources
(Elsevier, 2016)Costa Rica is located on the Central American Isthmus, which receives moisture inputs directly from the Caribbean Sea and the Eastern Pacific Ocean. This location includes unique mountainous and lowland microclimates, but ... -
Key hydrological processes in the Del Azul Creek basin, sub-humid Pampean Plain
(Elsevier B.V., 2021-02)Groundwater plays an important role in the economic development of the Chaco-Pampean Plain (Argentina), where industry, agriculture and cattle farming are the main economic activities. The 66% of the country's population ... -
Kinetics of anaerobic degradation of screened dairy manure by upflow fixed bed digesters: Effect of natural zeolite addition
(Taylor & Francis, 2009)The effect of the hydraulic retention time (HRT) on the performance of two up-flow anaerobic fixed bed digesters (UFAFBDs) packed with waste tire rubber (D1) and waste tire rubber and zeolite (D2) as micro-organism ... -
Kinetics of Isothermal Degradation Studies in Adhesives by Thermogra vimetric Data: Effect of Hydrophilic Nanosilica Fillers on the Thermal Properties of Thermoplastic Polyurethane-Silica Nanocomposites
(Recent Patents on Nanotechnology, 2008)The kinetics of thermal degradation process on thermoplastic polyurethanes (TPUs) adhesives with hydrophilic nanosilicas was studied using isothermal thermogravimetric analysis within the temperature range from 360 °C ... -
Knowledge Evidenced by Prospective Mathematics Teachers when Performing a Task Involving Geometry, Teaching and the Use of Technology
(Lutheran University of Brazil, 2019)The types of knowledge that prospective mathematics teachers use when faced with tasks involving technology are interesting because this knowledge can be used as a basis for analyzing the relevance of these types of ... -
Knowledge of mathematics teachers in initial training regarding mathematical proofs: Logic-mathematical aspects in the evaluation of arguments
(Universidad Nacional, Costa Rica, 2022-01-31)The objective of this study is to characterize the knowledge of mathematics teachers in initial training (MTITs) at the Universidad Nacional (Costa Rica) on the logic-syntactic and mathematical aspects ... -
La noción de idoneidad didáctica como herramienta para la reflexión de la clase de matemática
Poder realizar una reflexión de lo que ocurre en la clase de matemática es una competencia que debe poseer el profesor en servicio. Esta actividad de reflexión es compleja y más si no se cuenta con una estructura que permita ... -
Landscape analysis for the American crocodile Crocodylus acutus (Reptilia: Crocodilidae) in northwestern Costa Rica
(Instituto de Biología de la UNAM (México), 2022-10-18)Northwest Costa Rica has the largest crocodile population in the country, but it is also an important area of the human population growth, tourism, crops, and aquaculture, that have generated great changes in the region. ... -
LANGUAGE AND A PHYSICAL ORGANIZATION TECHNIQUE FOR SUMMARY TABLES.
(Proceedings of ACM-SIGMOD 1985 International Conference on Management of Data, 2004)A summary table is a tabular representation of summary data, and is a useful data structure for statistical databases. Primitive summary tables are basic building blocks of summary tables, and can be represented as relations ... -
Larvae of the Costa Rican Hetaerina (Odonata: Calopterygidae) with comments on distribution
(Royal Entomological Society, 1993)The larvae of seven of the nine Costa Rican species of Hetaerina (H.capitalis, H.cruentata, H. fuscogutfata, H. majuscula, H. miniata, H. occisa and H. titia) were identified by matching their Cellulose Acetate Gel ...