Prácticas de física : laboratorio I

1 archivo PDF (62 páginas)Conjunto de prácticas que indican el camino a seguir en el trabajo que realizara el alumno

Habichuelas y prácticas de cultivo en dos lugares de los llanos costeros de Puerto Rico

Experiments were conducted over a 3-year period (1983-1985) at Fortuna and Isabela, Puerto Rico, to compare the response of three bean (Phaseolus vulgaris L.) genotypes that differ in growth habit and lodging susceptibility to varying cultural practices. The experimental design was a split plot arrangement of a randomized complete block with three replications. Whole-plot treatments consisted of 0.5- and 1.0-m row widths. Subplots consisted of a factorial arrangement of three seeding rate treatments (6.6, 13.2, and 19.8 seeds/m) and three dry bean genotypes. All of the bean lines produced the greatest seed yield in the 0.5-m row width with a seeding rate of 19.8 seed/m. The increased yield was the result of an increased number of pods/ha. Indeterminate genotype 2W-33-2 produced the greatest overall seed yield in spite of the fact that it lodged more than the other genotypes. At the Fortuna Substation the seed yield of all genotypes averaged more than 2000 kg/ha when grown in 0.5-m row widths. At the Fortuna Substation there was no significant effect of row spacing or seeding rate on harvest index, whereas at the Isabela Substation harvest index decreased as the seeding rate increased. Plant height and 100-seed weight were largely unaffected by variation in row spacing and seeding rate. At Fortuna there was more lodging as the seeding rate increased from 6.6 to 19.8 seeds/m.De 1983 a 1985 se hicieron experimentos de campo en dos localidades de Puerto Rico para comparar la respuesta de tres genotipos de habichuela (Phaseolus vulgaris L.) a diferentes prácticas de cultivo. Los genotipos de habichuela variaron en hábito de crecimiento y en susceptibilidad a acamarse. Se utilizó un diseño de bloques completos aleatorizados con un arreglo de parcelas divididas con tres repeticiones. Las parcelas enteras consistieron de dos distancias entre surcos (0.5 y 1.0 m.). Las subparcelas consistieron de un arreglo factorial de tres densidades de siembra (6.6, 13.2, y 19.8 semillas/m.) y tres genotipos de habichuela. Con los tres genotipos se obtuvieron los mayores rendimientos en parcelas con 0.5 m. entre surcos y una densidad de siembra de 19.8 semillas/m. Los mayores rendimientos se debieron a un aumento en el número de vainas/ha. El genotipo 2W-33-2 produjo los mayores rendimientos, a pesar de que el acamado fue mayor que en los demás genotipos. En Fortuna los rendimientos de los genotipos fueron mayores de 2,000 kg./ha. cuando se sembraron en surcos de 0.5 m. de ancho. Con relación al índice de cosecha, en Fortuna no hubo diferencias significativas tanto en distancia entre surcos como en densidad de siembra. Por el contrario, en Isabela, el índice de cosecha disminuyó cuando se aumentó la densidad de siembra. La altura de la planta y el peso de 100 semillas no mostraron diferencias significativas al variar la distancia entre surcos y la densidad de siembra. En Fortuna el acamado fue mayor cuando la densidad de siembra se aumentó

Rockfall Hazard Assessment in Volcanic Regions Based on ISVS and IRVS Geomechanical Indices

In volcanic regions, rockfalls represent a major hazard strongly conditioned by the geomechanical behaviour of volcanic materials, the geomorphological characteristics of the relief and the climatic conditions. Volcanic rocks possess very different properties to those of other lithological groups, presenting highly heterogeneous geomechanical behaviours. Nevertheless, they have received little research attention in the field of geological and geotechnical engineering. To date, the application of geomechanical classifications to characterise and estimate volcanic slope stability has not yielded reliable results, indicating the need to establish specific criteria for these rocks. Consequently, we developed indices to estimate rockfall susceptibility, hazard and risk in volcanic slopes. The index of susceptibility for volcanic slopes (ISVS) is designed to estimate slope susceptibility to instability, which is related to the level of hazard, while the index of risk for volcanic slopes (IRVS) is designed to estimate the level of risk as a function of the potential damage or economic loss caused as a result of rockfalls on slopes. Both indices were developed in order to provide an easily applied procedure that facilitates the adoption of short-term preventive measures against rockfalls. The indices were applied in Tenerife (Canary Islands), which presents exceptional conditions for analysing slope stability in volcanic rocks because of its mountainous orography with very steep slopes and a wide variety of materials. These conditions have frequently precipitated slope instability, causing significant damage to housing, beaches, roads and other infrastructures. After applying these indices to a number of slopes representative of the island’s wide variety of geological, geomorphological and climatic conditions, the results obtained were compared with the actual behaviour of the slopes, determined from extensive rockfall inventory data and in situ geomechanical survey

Estudio filogenético de los géneros de Trichopterygini de Sudamérica Austral (Lepidoptera: Geometridae): una nueva clasifi cación

Phylogenetic study of the genera of South American Austral Trichopterygini (Lepidoptera: Geometridae, Larentiinae): a new classifi cation. In this work, we evaluate the taxonomy of the Trichopterygini in Chile based on a phylogenetic analysis of the morphological attributes. In our analysis, we used Tatosoma and Sauris as outgroups. Two approaches were used to evaluate phylogenetic relationships: 1) parsimony criterion, and 2) Bayesian inference. Parsimony analysis was conducted in PAUP software, and Bayesian analysis with Markov chain Monte Carlo using the BayesPhylogenies software. Our results based on the phylogenetic hypothesis suggest a new taxonomic order for Trichopterygini of the Andean Region of Southern South America. The valid genera are: Arrayanaria Parra, Butleriana Parra, Danielaparra Kemal & Kocak, Fueguina Parra, Hoplosauris Butler, Lagynopteryx Berg, Llampidken Parra & Santos-Salas, Pachrophylla Blanchard, Parapachrophylla Parra, Rindgenaria Parra, Tomopteryx Philippi, Triptila Warren, Triptiloides Parra & Santos-Salas, Warrenaria Parra. The main changes with respect to the previous taxonomic order are: 1) the genus Lagynopteryx Berg is subordinated under the Trichopterygini; 2) Toxopaltes Warren is a junior synonym of Lagynopteryx; 3) Hoplosauris moesta is transferred to the genus Llampidken; 4) Llampidken valdiviana is a junior synonym of L. moesta; 5) Oparabia arenosa is newly combined with the genus Arrayanaria; 6) Danielaparra viridis is a junior synonym of D. fragmentata; 7) Lobophoraimbricaria is newly combined with the genus Danielaparra; 8) Triptiloides fasciata is a junior synonym of T. randallae; and 9) Parapachrophylla michelleae Parra n. sp. is described. Andean Region species are more closely related to the genus Tatosoma from New Zealand, the synapomorphies that demonstrate this are: swollen metaepimeron and hypertrophy of the second abdominal segment. A checklist of the genera and species of the tribe in the region, and the fi gures of adults and genitalia of some species are included.En este trabajo se evalúa la taxonomía de los Trichopterygini de Chile a partir de un análisis fi logenético de los atributos morfológicos. En nuestro análisis, hemos utilizado Tatosoma y Sauris como grupos externos. Se utilizaron dos enfoques para evaluar las relaciones fi logenéticas: 1) criterio de parsimonia, y 2) inferencia bayesiana. El análisis de parsimonia se realizó a través del programa PAUP y el análisis bayesiano con cadenas de Markov y Monte Carlo a través del programa BayesPhylogenies. Nuestros resultados basados en la hipótesis fi logenética sugieren un nuevo orden taxonómico para Trichopterygini de la Región Andina del Sur de Sudamérica. Los géneros válidos son: Arrayanaria Parra, Butleriana Parra, Danielaparra Kemal & Kocak, Fueguina Parra, Hoplosauris Butler, Lagynopteryx Berg, Llampidken Parra & Santos-Salas, Pachrophylla Blanchard, Parapachrophylla Parra, Rindgenaria Parra & Santos-Salas, Tomopteryx Philippi,Triptila Warren y Warrenaria Parra. Los principales cambios con respecto al orden taxonómico anterior son: 1) el género Lagynopteryx Berg se incorpora a Trichopterygini; 2) Toxopaltes Warren es el sinónimo junior de Lagynopteryx; 3) Hoplosauris moesta se incorpora al género Llampidken; 4) Llampidken valdiviana es el sinónimo junior de L. Moesta; 5) Oparabia arenosa es incorporada al género Arrayanaria; 6) Danielaparra viridis es el sinónimo junior de D. fragmentata; 7) Lobophora imbricaria es incorporada al género Danielaparra; Triptiloides fasciata es el sinónimo junior de T. randallae; y 9) Parapachrophylla michelleae Parra n. sp. es descrita. Las especies de la Región Andina están más cerca del Tatosoma de Nueva Zelanda, las sinapomorfi as que demuestran esto son: el metaepimeron hinchado y la hipertrofia del segundo segmento abdominal. Se incluye un catálogo de los géneros y especies de la tribu en la región, y fotografías de adultos y armaduras genitales de algunas especies

Is the Fluorescence Quantum Yield of Tryptophan Independent of Excitation Wavelength?

Tryptophan is a fluorescent amino acid that is commonly used as a probe in protein structure-dynamics studies. It is also widely used as a convenient standard for measurements of fluorescence quantum yields of organic and bioorganic molecules. Literature values of the fluorescence quantum yield range from 0.13 to 0.15 upon excitation of tryptophan at 270 nm in aqueous solution. Even though the fluorescence quantum yield of tryptophan is known with a high degree of accuracy upon excitation at 270 nm (i.e., ca. ± 0.02), this value is being used indiscriminately in the literature for the determination of the fluorescence quantum yield of molecules at other excitation wavelengths. In those studies, the assumption has been made that the magnitude of the fluorescence quantum yield of tryptophan does not change with excitation wavelength. This assumption is based on the so-called Kasha’s rule, which states that fluorescence emission occurs in appreciable yield only from the lowest excited singlet state of an organic molecule. Consequently, the fluorescence quantum yield is typically independent of the excitation wavelength used. However, many molecules are known to not obey the Kasha’s rule. Therefore, in this study, we examine the hypothesis that the fluorescence quantum yield of tryptophan does not depend on the excitation wavelength used. We also investigate if the fluorescence quantum yield of tryptophan varies when the salt concentration of the phosphate buffer solution at a physiological pH of 7.4 is varied. The results demonstrate that the fluorescence quantum yield of tryptophan depends on excitation wavelength. It is, however, independent of the ionic strength of the buffered solution in a salt concentration range from 5 to 100 millimolar. A photophysical relaxation mechanism that satisfactorily explains the excitation wavelength dependence of the fluorescence quantum yield of tryptophan will be presented.https://commons.case.edu/intersections-fa20/1002/thumbnail.jp

New Approaches for Teaching Soil and Rock Mechanics Using Information and Communication Technologies

Soil and rock mechanics are disciplines with a strong conceptual and methodological basis. Initially, when engineering students study these subjects, they have to understand new theoretical phenomena, which are explained through mathematical and/or physical laws (e.g. consolidation process, water flow through a porous media). In addition to the study of these phenomena, students have to learn how to carry out estimations of soil and rock parameters in laboratories according to standard tests. Nowadays, information and communication technologies (ICTs) provide a unique opportunity to improve the learning process of students studying the aforementioned subjects. In this paper, we describe our experience of the incorporation of ICTs into the classical teaching-learning process of soil and rock mechanics and explain in detail how we have successfully developed various initiatives which, in summary, are: (a) implementation of an online social networking and microblogging service (using Twitter) for gradually sending key concepts to students throughout the semester (gradual learning); (b) detailed online virtual laboratory tests for a delocalized development of lab practices (self-learning); (c) integration of different complementary learning resources (e.g. videos, free software, technical regulations, etc.) using an open webpage. The complementary use to the classical teaching-learning process of these ICT resources has been highly satisfactory for students, who have positively evaluated this new approach.This work has been developed in the framework of the RECLAND Project. It has been funded by the European Union under Lifelong Learning Programme, Erasmus Programme: Erasmus Multilateral Projects, 526746-LLP-1-2012-1-ES-ERASMUS-EMCR, MSc Programme in Climate Change and Restoration of Degraded Land

Breeding ecology of Two-banded Plover (Charadrius falklandicus) in Valdés Peninsula, Argentina

Para desarrollar estrategias que mitiguen los impactos de la actividad humana sobre las poblaciones de aves playeras, es necesario conocer el estado de conservación de las especies. El estado de conservación de las especies de aves playeras endémicas del Neotrópico es poco entendido debido a la escasa información sobre el tamaño de las poblaciones, sus destinos migratorios y su ecología reproductiva. En este estudio investigamos la ecología reproductiva del Chorlo de Doble Collar (Charadrius falklandicus), un ave endémica del Neotrópico, en tres sitios de estudio en Chubut, Argentina. Nuestros resultados muestran que esta especie 1) se agrupa en hábitats de reproducción aunque presenta variación en los sitios donde construye los nidos, y 2) que el éxito de incubación disminuye al transcurrir la temporada y es menor que el éxito de crianza. El monitoreo de las aves anilladas, a largo plazo, permitirá investigar la fidelidad a la pareja y la fidelidad a los sitios de reproducción, así como los destinos migratorios durante el invierno austral. Esta información permitirá estimar parámetros demográficos para entender el estado de conservación de esta especie.Developing strategies to mitigate human impacts on shorebird populations require knowledge on the conservation status of shorebird species. The conservation status of endemic Neotropical species is poorly understood as information on population size, migratory movements and reproductive ecology is scanty. Here we investigate the breeding ecology of a Neotropical species, the Two-banded Plover (Charadrius falklandicus), in three study sites in Chubut, Argentina. We found 1) that this species aggregates in reproductive habitats despite presenting variation in nesting sites; and 2) that hatching success decreases with the date of the breeding season and is lower than fledging success. Long term monitoring of individually ringed birds will provide information on mate fidelity, breeding site fidelity, breeding success and migratory destinies during austral winter. This information will allow to estimate demographic parameters for a better understanding of the conservation status of this species.Fil: García Peña, Gabriel. E.. University of Bath; Reino UnidoFil: Hernández, María de Los Angeles. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; ArgentinaFil: Bala, Luis Oscar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Centro Nacional Patagónico; Argentin