Ciencias básicas
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Ítem 1,1-Diphenyl-4-(thiophen-2-yl)but-3-yn-1-ol(2018-11) Umaña, Christian A.; Pineda Cedeño, Leslie William; Cabezas Pizarro, Jorge A.The asymmetric unit of the title homopropargyl alcohol, C20H16OS, contains two independent molecules comprising a hydroxy group, a 3-(2-thiophenyl)- propargylic moiety and two aromatic rings linked to a central carbon atom. The two unique molecules are linked into a dimer by an O—HO hydrogen bond. In one molecule, the thiophene ring is disordered over two orientations rotated by 180 with a refined occupancy ratio of 0.575 (4):0.425 (4). The crystal structure is stabilized by O—H and C—H hydrogen-bond interactions. The crystal studied was a two-component non-merohedral twin, the refined ratio of the twin components being 0.575 (4):0.425 (4).Ítem 1,3-Bis{[(2,6-dimethylphenyl)sulfanyl]methyl}benzene(2019) Garita Salazar, Bruno; Pineda Cedeño, Leslie WilliamThe structure of the title compound, C24H26S2, an example of a pincer ligand with an SCS-chelation motif, illustrates the steric effects of the methyl groups in the thiophenyl rings at the 2- and 6-positions, forcing a dissimilar spatial orientation of the thiophenyl rings relative to the central aryl group [dihedral angles = 33.58 (7) and 40.49 (7)°]. In the crystal, weak S⋯S contacts [3.4009 (7) Å] link the molecules into inversion dimers.Ítem 1-Nitro-4-(1-propyn-1-yl)benzene(2019) Campos Fernández, Cristian Saúl; Pineda Cedeño, Leslie William; Cabezas Pizarro, Jorge A.The title compound, C9H7NO2, was prepared by alkynylation of 4-iodonitrobenzene with 1,3-dilithiopropyne in the presence of 1 equivalent of CuI and catalytic amounts of Pd(PPh3)2Cl2. The complete molecule is generated by crystallographic twofold symmetry with the C—N and C—C[triple bond]C—C units lying on the rotation axis. No directional interactions beyond normal van der Waals contacts could be identified in the packing.Ítem (1S,3R)-N-{(3S,10S,12S,13R,17R)-12-Hydroxy-17- [(R)-5-hydroxypentan-2-yl]-10,13-dimethylhexa- decahydro-1H-cyclopenta[a]phenanthren-3-yl}- adamantane-1-carboxamide 0.25-hydrate(2022-10-12) Campos Fernández, Cristian Saúl; Procúpez Schtirbu, Rolando; Soto Tellini, Victor Hugo; Salazar Camacho, Juan Carlos; Jancik, VojtechThe title compound, C 35H 57 NO 3 0.25H 2O, was synthesized from deoxycholic acid followed by a protection, a Mitsonobu substitution, a Staudinger reduction, formation of an amide and final reduction in the lateral chain. The compound crystallizes in the P1 space group with four steroid molecules and one water molecule in the triclinic cell unit. The crystal structure features O—H O hydrogen bonding. The crystal studied was refined as a non-merohedral twinÍtem (2922) Proposal to conserve the name Loasa rudis (“Nasa rudis”) against L. rhoeadifolia (Loasaceae)(2022-10-17) Acuña Castillo, Rafael; Weigend, MaximilianThe genus Nasa was established by Weigend in 2006, encompassing species previously classified under Loasa. The distinction between the two genera is supported by the presence of a single bract per flower, a unique structure of the nectar scale, and molecular evidence. Among the widely collected and distributed taxa in Nasa is N. triphylla subsp. rudis, which spans from southern Mexico to Panama. Recent molecular evidence suggests elevating N. triphylla subsp. rudis to species rank, as it is morphologically and phylogenetically closer to N. dyeri than to the type subspecies of N. triphylla. N. rudis and N. dyeri exhibit distinct characteristics in comparison to N. triphylla, including robust basal stems, dark green calli at the base of petioles, and petals with long filiform appendages. N. rudis can be differentiated from N. dyeri by stem characteristics, stinging trichome cover, and pedicel length. The history of nomenclature for this taxon involves various names under Loasa, and the name "Loasa rhoeadifolia" is considered a synonym. Due to the lack of recognizable type material and the established usage of the name "Loasa rudis," it is recommended to conserve the name Loasa rudis for nomenclatural stability and to avoid further confusion.Ítem 5,5-Diphenyl-cis-penta-2,4-dienoic acid(2019) Pineda Cedeño, Leslie William; Amey, Adam R.; Cabezas Pizarro, Jorge A.In the title compound, C17H14O2, the dihedral angle between the phenyl rings is 76.52 (7)°. In the crystal, pairwise O—H⋯O hydrogen bonds link the molecules into carboxylic acid inversion dimers.Ítem A basic model for the propagation of ideologies(2022-11) Mata Boschini, Luis Diego; Salas Jiménez, Eduardo; Sánchez Peña, Fabio ArielIdeas and ideologies move the world and are involved in almost every aspect of human life and society. This paper presents a mathematical model for the propagation of two different ideologies in a group of people that could convert or not to one of the ideologies. This model allowed us to analyze which relations between parameters influence the survival and dominance of an ideology. The basic reproductive number was computed and numerical simulations were performed to analyze different scenarios.Ítem A BDDC algorithm with deluxe scaling for H(curl) in two dimensions with irregular subdomains(2015) Calvo Alpízar, Juan GabrielA bound is obtained for the condition number of a BDDC algorithm for problems posed in H(curl) in two dimensions, where the subdomains are only assumed to be uniform in the sense of Peter Jones. For the primal variable space, a continuity constraint for the tangential average over each interior subdomain edge is imposed. For the averaging operator, a new technique named deluxe scaling is used. Our optimal bound is independent of jumps in the coefficients across the interface between the subdomains and depends only on a few geometric parameters of the decomposition. Numerical results that verify the result are shown, including some with subdomains with fractal edges and others obtained by a mesh partitioner.Ítem A biogeographical evaluation of high-elevation myxomycete assemblages in the northern Neotropics(2011-08) Rojas Alvarado, Carlos Alonso; Stephenson, Steven L.; Valverde González, Randall; Estrada Torres, ArturoThis study represented an effort to apply some of the relatively well-known biogeographical and macroecological models to the observed structure of myxomycete assemblages, with emphasis on the northern Neotropical region. A series of 28 experimental plots located in 14 study sites within five different countries was surveyed during two consecutive years using a standard methodology that included both field collections and specimens obtained from moist chamber cultures. Results showed that myxomycetes in high-elevation areas of the northern Neotropics seem to have different levels of preference for macro- and microenvironments, varying degrees of niche breadth and overlap, and different patterns of species occurrence in comparable areas. In a similar manner, species assemblages along a latitudinal gradient that extends from Mexico to Costa Rica showed a decreasing level of similarity with an assemblage studied in the temperate forests of the eastern United Stated and were clearly distinct from an assemblage in Thailand.Ítem A brief survey of Higgs bundles(2019-06) Zúñiga Rojas, Ronald AlbertoConsidering a compact Riemann surface of genus greater or equal than two, a Higgs bundle is a pair composed of a holomorphic bundle over the Riemann surface, joint with an auxiliar vector field, so-called Higgs field. This theory started around thirty years ago, with Hitchin’s work, when he reduced the self-duality equations from dimension four to dimension two, and so, studied those equations over Riemann surfaces. Hitchin baptized those fields as Higgs fields because in the context of physics and gauge theory, they describe similar particles to those described by the Higgs bosson. Later, Simpson used the name Higgs bundle for a holomorphic bundle together with a Higgs field. Today, Higgs bundles are the subject of research in several areas such as non-abelian Hodge theory, Langlands, mirror symmetry, integrable systems, quantum field theory (QFT), among others. The main purposes here are to introduce these objects, and to present a brief but complete construction of the moduli space of Higgs bundles.Ítem A call-and-response system facilitates group cohesion among disc-winged bats(2013) Chaverri Echandi, Gloriana; Gillam, Erin H.; Kunz, Thomas H.Acoustic signals are important in maintaining group cohesion, particularly in highly mobile species. For these signals to facilitate group cohesion, individuals must be able to recognize, and respond to, calls emitted by group members. In this study, we document the use and recognition of complementary contact calls in Spix’s disc-winged bat (Thyroptera tricolor), a species known to form very stable social groups despite using an extremely ephemeral roosting resource. This bat uses 2 sets of calls: “inquiry,” which are emitted by flying bats that are seeking roosts or group mates, and “response,” which are produced in reply to an inquiry call by individuals that have already located a roost. Here, we test if bats are capable of discriminating between the inquiry and response calls of group and nongroup mates using playback experiments. Results show that flying bats can discriminate between the inquiry and response calls emitted by group and nongroup members and can maintain contact preferentially with the former. Roosting bats, however, exhibited no preference for group over nongroup members and thus responded indiscriminately. We argue that differences in how individuals respond to calls from group and nongroup members may be partly attributed to the costs associated with flight and the potential benefits of recruiting roost mates.Ítem A carbonate platform associated with shallow cold methane seeps in Golfo Dulce, Pacific Costa Rica(2015) Wild, Christian; Rixen, Tim; Sánchez Noguera, Celeste; Merico, Agostino; Jiménez Centeno, Carlos; Cortés Núñez, Jorge; Naumann, Malik S.Marine methane seeps are typically observed in cold, anoxic and organic-rich deep-sea environments, such as in the Black Sea, where methane emissions fuel the authigenic accretion of calcium carbonate structures via microbial sulphate reduction and anaerobic methane oxidation (Michaelis et al. 2002). For shallow tropical waters, methane seeps are only known from hydrothermal vents (Nakamura et al. 2006). Here, we report about our recent discovery of a cold methane seep in warm (ca. 29℃) and O2-saturated (97-100%) Golfo Dulce (8.496450°N, 83.262610°W) that is located at the Southern Pacific coast of Costa Rica, Central America.Ítem A Chronoamperometric Screen Printed Carbon Biosensor Based on Alkaline Phosphatase Inhibition for W(VI) Determination in Water, Using 2-Phospho-l-Ascorbic Acid Trisodium Salt as a Substrate(2015) Alvarado Gámez, Ana Lorena; Alonso Lomillo, María Asunción; Domínguez Renedo, Olga; Arcos Martínez, María JuliaThis paper presents a chronoamperometric method to determine tungsten in water using screen-printed carbon electrodes modified with gold nanoparticles and cross linked alkaline phosphatase immobilized in the working electrode. Enzymatic activity over 2-phospho-l-ascorbic acid trisodium salt, used as substrate, was affected by tungsten ions, which resulted in a decrease of chronoamperometric current, when a potential of 200 mV was applied on 10 mM of substrate in a Tris HCl buffer pH 8.00 and 0.36 M of KCl. Calibration curves for the electrochemical method validation, give a reproducibility of 5.2% (n = 3), a repeatability of 9.4% (n = 3) and a detection limit of 0.29 ± 0.01 μM. Enriched tap water, purified laboratory water and bottled drinking water, with a certified tungsten reference solution traceable to NIST, gave a recovery of 97.1%, 99.1% and 99.1% respectively (n = 4 in each case) and a dynamic range from 0.6 to 30 μM. This study was performed by means of a Lineweaver–Burk plot, showing a mixed kinetic inhibition.Ítem A ClC Chloride Channel Homolog and Ornithine-Containing Membrane Lipids of Rhizobium tropici CIAT899 Are Involved in Symbiotic Efficiency and Acid Tolerance(2005) Rojas Jiménez, Keilor Osvaldo; Sohlenkamp, Christian; Geiger, Otto; Martínez Romero, Esperanza; Werner, Dietrich; Vinuesa, PabloRhizobium tropici CIAT899 is highly tolerant to several environmental stresses and is a good competitor for nodule occupancy of common bean plants in acid soils. Random transposon mutagenesis was performed to identify novel genes of this strain involved in symbiosis and stress tolerance. Here, we present a genetic analysis of the locus disrupted by the Tn5 insertion in mutant 899-PV9, which lead to the discovery of sycA, a homolog of the ClC family of chloride channels and Cl-/H+ exchange transporters. A nonpolar deletion in this gene caused serious deficiencies in nodule development, nodulation competitiveness, and N2 fixation on Phaseolus vulgaris plants, probably due to its reduced ability to invade plant cells and to form stable symbiosomes, as judged by electron transmission microscopy. A second gene (olsC), found downstream of sycA, is homologous to aspartyl/asparaginyl β-hydroxylases and modifies two species of ornithine-containing lipids in vivo, presumably by hydroxylation at a still-unknown position. A mutant carrying a nonpolar deletion in olsC is symbiotically defective, whereas overexpressed OlsC in the complemented strain provokes an acid-sensitive phenotype. This is the first report of a ClC homolog being essential for the establishment of a fully developed N2-fixing root nodule symbiosis and of a putative β-hydroxylase that modifies ornithine-containing membrane lipids of R. tropici CIAT899, which, in turn, are contributing to symbiotic performance and acid tolerance.Ítem A climate change projection for summer hydrologic conditions in a semiarid watershed of central Arizona(2015-03-05) Hawkins, Gretchen A.; Vivoni, Enrique R.; Robles Morua, Agustin; Mascaro, Giuseppe; Rivera Fernández, Erick; Dominguez, FrancinaPotential climate change impacts on summer precipitation and subsequent hydrologic responses in the southwestern U.S. are poorly constrained at present due to a lack of studies accounting for high resolution processes. In this investigation, we apply a distributed hydrologic model to the Beaver Creek watershed of central Arizona to explore its utility for climate change assessments. Manual model calibration and model validation were performed using radar-based precipitation data during three summers and compared to two alternative meteorological products to illustrate the sensitivity of the streamflow response. Using the calibrated and validated model, we investigated the watershed response during historical (1990–2000) and future (2031–2040) summer projections derived from a single realization of a mesoscale model forced with boundary conditions from a general circulation model under a high emissions scenario. Results indicate spatially-averaged changes across the two projections: an increase in air temperature of 1.2 °C, a 2.4-fold increase in precipitation amount and a 3-fold increase in variability, and a 3.1-fold increase in streamflow amount and a 5.1-fold increase in variability. Nevertheless, relatively minor changes were obtained in spatially-averaged evapotranspiration. To explain this, we used the simulated hydroclimatological mechanisms to identify that higher precipitation limits radiation through cloud cover leading to lower evapotranspiration in regions with orographic effects. This challenges conventional wisdom on evapotranspiration trends and suggest that a more nuanced approach is needed to communicate hydrologic vulnerability to stakeholders and decision-makers in this semiarid region.Ítem A Climate Feature of the Tropical Americas: The Trade Wind Easterly Jet(1998-06) Amador Astúa, Jorge AlbertoUtilizando datos medios mensuales globales de los Reanálisis de NCEP/NCARP para el periodo 1982-1994 se documenta una característica de la circulación de las Américas tropicales no reportada hasta el momento en la literatura: la corriente en chorro de bajo nivel en los alisios del este. Esta intensa corriente se desarrolla en niveles bajos (especialmente en 925, 800, 700 mb) en la parte central del Mar Caribe y de mayo julio, el viento aumenta hasta un máximo y luego la corriente media decrece desde este mes hasta septiembre. Se observan valores en exceso de 14 ms¬-1 en el nivel de 925 mb durante julio. Estimaciones dinámicas básicas de la cortante horizontal del viento muestran que este flujo es baratrópicamente inestable durante los meses de verano en niveles bajos, de manera que perturbaciones tropicales en la región podrían crecer a expensas de la energía cinética media del flujo zonal. Las circulaciones cruzadas asociadas al flujo en la región de salida de la corriente en chorro son consistentes con la velocidad vertical (dp/dt) y con el máximo de precipitación que se encuentra en el este del Caribe cerca de las costas de Centro América durante los meses de verano.Ítem A climatology of low level wind regimes over Central America using a weather type classification approach(2015-04) Sáenz Soto, Fernán; Durán Quesada, Ana MaríaBased on the potential of the weather types classification method to study synoptic features, this study proposes the application of such methodology for the identification of the main large scale patterns related with weather in Central America. Using ERA Interim low-level winds in a domain that encompasses the intra-Americas sea, the eastern tropical Pacific, southern North America, Central America and northern South America, the K-means clustering algorithm was applied to find recurrent regimes of low-level winds. Eleven regimes were identified and good coherency between the results and known features of regional circulation was found. It was determined that the main large scale patterns can be either locally forced or a response to tropical-extratropical interactions. Moreover, the local forcing dominates the summer regimes whereas mid latitude interactions lead to winter regimes. The study of the relationship between the large scale patterns and regional precipitation shows that winter regimes are related with the Caribbean-Pacific precipitation seesaw. Summer regimes, on the other hand, enhance the Caribbean-Pacific precipitation with contrasting distribution as a function of the dominant regimes. A strong influence of ENSO on the frequency and duration of the regimes was found. It was determined that the specific effect of ENSO on the regimes depends on whether the circulation is locally forced or lead by the interaction between the tropics and the mid-latitudes. The study of the cold surges using the information of the identified regimes revealed that three regimes are linkable with the occurrence of cold surges that affect Central America and its precipitation. As the winter regimes are largely dependent of mid-latitude interaction with the tropics, the effect that ENSO has on the Jet Stream is reflected in the winter regimes. An automated analysis of large scale conditions based on reanalysis and/or model data seems useful for both dynamical studies and as a tool to support forecasting. The application of the approach implemented in this study may be promising to improve current understanding on how large scale conditions affect regional weather.Ítem A comparative study of hurricanes Fifi (1974) and Greta (1978) and their associated rainfall distributions over central America(1996) Fernández Rojas, Walter; Vega Guzmán, NormanA comparative study of hurricanes Fifi (1974), which had similar tracks but produced different rainfall distributions over Central America, was made. It was found that Fifia was much rainier in spite of being much less intensa than Grete, The direct effect of the cyclones (produced by the convergent fields in the central parts and local orographic enhancement) and the indirect effect (the interaction of a westerly component flow induced by the presence of the cyclones with orography on the Pacific side of Central America) were also studied. It was found that the indirect effect is as importan as the direct effect when accumulated rainfall amounts for a period of about three days are considered.Ítem A Comparison of four Methods to Evaluate the Butterfly Abundance. Using a Tropical Community(Journal of the Lepidopterists' Society 45(3), 1991, 241-243, 1991-03-18) Monge Nájera, Julián; Nielsen Muñoz, VanessaIn recent years. several transect methods to evaluate the abundance of butterflies have been proposed (Pollard, E. 1977, Biol. Conserv. 12:115—134; Feltwell, 3. 1982. Proc. Trans. Br. Entomol. Nat. Hist. Soc. 15:17—24). but to our knowledge there has been no attempt to compare experimentally their usefulness in relation to the availability of time and resources. Herein, we present the results of an experiment in which modifications of four of those methods were applied, simultaneously, to a community of neotropical butterfliesÍtem A comparison of Monstera deliciosa and M. tacanaensis, with comments on Monstera section Tornelia (Araceae)(2020) Cedeño Fonseca, Marco Vinicio; Díaz Jiménez, Pedro; Zuluaga Trochez, Alejandro; Blanco Coto, Mario AlbertoMonstera deliciosa, one of the most commonly cultivated aroids, is a morphologically variable species and has traditionally been considered native to southern Mexico, Guatemala, Costa Rica and Panama. We demonstrate that M. tacanaensis, which naturally occurs in those four countries and has been considered a synonym of M. deliciosa, is a closely related but different species. The natural range of M. deliciosa is restricted to southern Mexico and Guatemala. The name M. borsigiana is a synonym of M. deliciosa, representing one of its variations. The name Tornelia fragrans (another synonym of M. deliciosa) is lectotypified. A taxonomic history of Monstera section Tornelia (of which both M. deliciosa and M. tacanaensis are members) is presented; we also include M. maderaverde of Honduras in this section. Detailed descriptions and illustrations of M. deliciosa and M. tacanaensis are provided. The seeds of M. tacanaensis are extruded from the fruit at maturity, a phenomenon first reported here for the genus.