3,404 research outputs found

    El desarrollo de la geología en la Universidad de Buenos Aires

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    La enseñanza de la geología en la Universidad de Buenos Aires comenzó en 1865 con Pellegrino Strobel, al que siguieron Juan Ramorino y Eduardo Aguirre. Este último fue el primer profesor de geología argentino hasta su retiro en 1906. En ese año Enrique Hermitte lo reemplaza e inicia una nueva etapa en la enseñanza. Hermitte formó a los primeros geólogos en el país, dirigiendo las tesis doctorales de Franco Pastore (1914), Juan J. Nágera (1915) y Edelmira Mórtola (1921). Un fuerte impulso al inicio de la investigación geológica fue la llegada a la Universidad de Juan Keidel y posteriormente de Pablo Groeber. Un importante cambio en la calidad de las tesis se evidenció en el trabajo doctoral de Horacio J. Harrington en 1933, la primera tesis de excelente nivel científico. En esos años Harrington propuso una nueva currícula para la carrera, y posteriormente como director del Instituto de Geología de la Universidad, junto con Armando Leanza como profesor, fue uno de los más destacados geólogos argentinos de esos años. El golpe militar en 1955 marca una importante discontinuidad y el inicio de una nueva etapa. Se modernizó el plan de estudios y se introdujeron una serie de cambios en la enseñanza y el equipamiento del flamante Departamento de Ciencias Geológicas, liderados por Félix González Bonorino. La Geología estuvo caracterizada por una educación más sólida en diferentes especialidades y con profesores formados en el exterior y extranjeros, que enseñaron disciplinas poco desarrolladas en el país. Esto fue arrasado con la Noche de los Bastones Largos que derivó en un largo período de opacidad entre 1966-1983, con algunas excepciones como el desarrollo del paleomagnetismo por Daniel Valencio y sus discípulos. En esa época se destacan el afianzamiento del Laboratorio de Paleomagnetismo y la creación del Instituto de Geología Isotópica, que produjo por varios años las primeras dataciones sistemáticas del país bajo la dirección de Enrique Linares. Se analizan y describen los protagonistas de los diferentes períodos, destacando a aquellas figuras que con sus aportes a través de los años permitieron consolidar al Departamento de Ciencias Geológicas de la Universidad de Buenos Aires La última etapa comienza con la vuelta a la democracia que, con concursos docentes abiertos sin restricciones, permitió alcanzar el presente desarrollo

    Proposal and Description of a Test System with Wind, Hydro and Fossil Fuel Power Plants for Static Analyses

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    This article presents and describes a 229 bus test system that includes wind, hydro and fossil fuel power plants. It represents the Northeast subsystem of the Brazilian Interconnected Power System (BIPS). The test system supplies a load of 4.17 GW, being 13% powered by wind farms, which is the current wind power penetration level of the BIPS. The data comprehends different load levels based on the typical load behavior and typical capacity factors of wind, hydro and fossil fuel plants, as well as the capacity of transmission and sub-transmission lines, transformers, and the adopted structure for the test system. The data is compiled considering models and operating scenarios of the BIPS, and allow performing studies of static voltage stability, sensitivity of voltage stability margin considering the wind farms, and multi-objective optimization considering market constraints. The results of the simulations with the test system indicate the consistency of their data structure and its applicability to different studies of electric power systems.Comment: In proceedings of the 11th Bulk Power Systems Dynamics and Control Symposium (IREP 2022), July 25-30, 2022, Banff, Canad

    Gender equality in the information systems and tecnhonology fields: a comprehensive diagnosis at the school of engineering of the University of Minho

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    Gender equality in academia and science has been a central theme in several scientific studies around the world. Over the last few years, there has been an extensive literature production on the explicit and implicit processes that drive gender inequalities and make them persist over time. In contexts of increasing mobility, globalization and cultural change, it is urgent that science and education policies, defined in the context of Universities and their human resources (including teaching, non-teaching staff as well as students), recognize the existence of gender inequalities and promote effective measures for its eradication, in a collective and participatory approach. Despite the production of literature attesting the existence of gender inequalities in academia, which documents processes of segregation and discrimination that affect the various participants of the organization as well as a set of methodological proposals to overcome them, it has not proved sufficient to change the reality of practices in teaching and research institutions Since gender inequality is a transversal problem and holds implications for the University as a whole, and individually for the people that compose it, this study documents the initial measures implemented at Engineering School, as part of Project EQUAL_IST- Gender Equality Plan for Information Sciences and Technology Research Institutions, which is being carried out by teams in several European countries, and aims, mainly, to study and intervene in the advancement of gender equality in the area of Technology and Information systems.This work was partly funded by FCT –Fundação para a Ciência e Tecnologia within the Project Scope: "Project UID/CTM/00264/2019 of2C2T –Centro de Ciência e Tecnologia Têxtil,; “Project UID/CEC/00319/2019” and COMPETE: POCI-01-0145-FEDER-007560; project UID/CCI/00736/2013

    Cretaceous deformation of the southern Central Andes: synorogenic growth strata in the Neuquén Group (35° 300–37° S)

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    The Neuquén Group is an Upper Cretaceous continental sedimentary unit exhumed during the latest Miocene contractional phase occurred in the southern Central Andes, allowing a direct field observation and study of the depositional geometries. The identification of growth strata on these units surrounding the structures of the frontal parts of the Andes, sedimentological analyses and U–Pb dating of detrital components, allowed the definition of a synorogenic unit that coexisted with the uplift of the early Andean orogen since ca. 100 Ma, maximum age obtained in this work, compatible with previous assignments and constrained in the top by the deposition of the Malarg€ue Group, in the Maastrichtian (ca. 72 Ma). The definition of a wedge top area in this foreland basin system, where growth strata were described, permitted to identify a Late Cretaceous orogenic front and foredeep area, whose location and amplitude contrast with previous hypotheses. This wedge top area was mostly fed from the paleo-Andes with small populations coming from sources in the cratonic area that are interpreted as a recycling in Jurassic and Lower Cretaceous sections, which contrasts with other analyses performed at the foredeep zone that have mixed sources. In particular, Permian sources are interpreted as coming directly from the cores of the basement structures, where Neopaleozoic sections are exposed, next to the synorogenic sedimentation, implying a strong incision in Late Cretaceous times with an exhumation structural level similar to the present. The maximum recognised advance for this Late Cretaceous deformation in the study area is approximately 500 km east of the Pacific trench, which constitutes an anomaly compared with neighbour segments where Late Cretaceous deformations were found considerably retracted. The geodynamic context of the sedimentation of this unit is interpreted as produced under the westward fast moving of South America, colliding with two consecutive mid-ocean ridges during a period of important plate reorganisation. The subduction of young, anhydrous, buoyant lithosphere would have produced changes in the subduction geometry, reflected first by an arc waning/gap and subsequently by an arc migration that coexisted with synorogenic sedimentation. These magmatic and deformational processes would be the product of a shallow subduction regime, following previous proposals, which occurred in Late Cretaceous times, synchronous to the sedimentation of the Neuqu en Group.Facultad de Ciencias Naturales y Muse

    Tras los pasos de Carl E. Burckhardt en los Andes Mendocinos

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    Within the framework of the expeditions organized by the Museo de la Plata, stand out the observations of the Mendoza Andes by Carl Burckhardt, Leo Wehrli and Rudolf Hauthal. Based on their descriptions and the existing photographic archive in the library of the Federal Polytechnic School (ETH) of Zurich, it was possible to reconstruct the route made in 1897. Based on the published works, mainly those of Burckhardt, we were able to relocate two classic fossiliferous localities, the Cajón del Burro and the “Molinos Colgados”. In the first were collected type specimens of ammonites, which are presently lost. The second, Mallines Colgados, was located on the right bank of the Rio Grande. The new material collected, as well as the observations made, highlight the work done by these explorers at the end of the 19th century.En el marco de las expediciones organizadas por el Museo de la Plata se destacan las observaciones de los Andes mendocinos de Carl Burckhardt, Leo Wehrli y Rudolf Hauthal. Sobre la base de sus precisas descripciones y del archivo fotográfico existente en la biblioteca de la Escuela Politécnica Federal (ETH) de Zúrich, se ha podido reconstruir el recorrido realizado en 1897. Teniendo en cuenta los trabajos publicados, en especial los de Burckhardt, se han reubicados dos clásicas localidades fosilíferas, el Cajón del Burro y los “Molinos Colgados”. En la primera se habían extraído amonites, cuyos ejemplares tipo se encuentran perdidos. La segunda corresponde en realidad a Mallines Colgados, ubicada en la margen derecha del río Grande. El nuevo material colectado, así como las observaciones realizadas ponen en valor el trabajo realizado por estos exploradores a fines del siglo XIX

    Controls in the variation of Andean volume between 20º and 46ºS

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    La cadena andina presenta, desde los Andes Centrales hasta los Andes Patagónicos, una importante variación en su volumen orogénico. Recientemente se ha propuesto que esta variación estaría controlada por factores climáticos que condicionarían la abundancia de material sedimentario presente en la trinchera. Con el objetivo de evaluar esta hipótesis y determinar otros posibles mecanismos de generación de volumen orogénico, hemos realizado un estudio detallado de la relación entre espesores sedimentarios dentro de la trinchera, volúmenes orogénicos y tasas de precipitación entre 15º-46ºS, considerando intervalos discretos de 2º de latitud. Los resultados demuestran que si el control climático fuese válido actuaría solo en el intervalo comprendido entre los 30ºS y 44ºS. Allí se observa que a medida que aumenta, de norte a sur, el volumen sedimentario presente en la trinchera, disminuye el volumen orogénico. Sin embargo, entre 20º-30º S se observa una progresiva disminución del volumen orogénico mientras que la cantidad de material sedimentario dentro de la trinchera no varía sustancialmente. Esto implica que si bien el factor climático podría ejercer algún tipo de control en el desarrollo del volumen orogénico andino, existirían otros condicionantes coexistentes con éste.The Andean chain, from the Central Andes next to the Arica bending to the Patagonian Andes, shows an important variation in its orogenic volume. Recently it has been proposed that this variation could be controlled by climatic factors that would define the amount of sediments inside the trench. To evaluate this hypothesis and to determine other possible mechanisms that generate orogenic volume, we have made a detailed study about the existing relation between sedimentary thickness within the trench, orogenic volumes and rates of precipitation between 15º-46ºS, considering discreet intervals of 2º latitude each. The results demonstrate that the climatic control, if valid, would act only in the interval between 30º and 44ºS. Along this sector can be observed that, as sedimentary thickness in the trench increases, orogenic volume decreases. Nevertheless, between 20º-30ºS a progressive decrease in the orogenic volume is observed, whereas the amount of sedimentary material within the trench does not vary substantially. This would imply that although the climatic factor could exert a limited role in constructing Andean volume, other coexisting conditioners would be acting at the same time.Fil: Pose, Fernando A.. No especifica;Fil: Spagnuolo, Mauro Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Folguera Telichevsky, Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Ramos, Victor Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; Argentin

    Evidence of cross gene regulation of some virulence factors of Porphyromonas gingivalis by Streptococcus intermedius

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    Periodontal disease has been associated with poor dental care, which promotes the accumulation of bacteria and the development of diseases of the mouth. Porphyromonas gingivalis are anaerobic Gramnegative bacteria found in the subgingival plaque. They are largely responsible for chronic periodontal disease. Streptococcus intermedius is a Gram positive coccus found in the supragingival plaque. The objective of the present work was to evaluate the expression of several virulence genes of P. gingivalis in a mixed culture with S. intermedius using qPCR and heterologous microarrays. P. gingivalis ATCC 33277 and W83 and S. intermedius ATCC 27335 strains were cultured and total RNA was extracted using the High Pure RNA isolation kit. Oligodeoxynucleotides were designed to make multiple comparisons with organisms. Microarray was performed to identify gene expression. To quantify gene expression, cDNA samples from three different P. gingivalis:S. intermedius ratios were diluted 10-1, 10-2 and 10-3. The microarray experiment indicated that in P. gingivalis, 29 genes were upregulated. The putative function of upregulated genes was the biosynthesis of different metabolic pathways. Heterologous microarrays are a new approach that are useful for investigating gene expression.Keywords: Porphyromonas gingivalis, Streptococcus intermedius, periodontal disease, virulence genes, cross gene regulation.African Journal of Biotechnology Vol. 12(28), pp. 4498-450

    DNA-based population density estimation of black bear at northern Mexico: A preliminary study

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    The analysis of deoxyribonucleic acid (DNA) microsatellites from hair samples obtained by the non-invasive method of traps was used to estimate the population density of black bears (Ursus americanus eremicus) in a mountain located at the county of Lampazos, Nuevo Leon, Mexico. The genotyping of bears was performed by multiplex polymerase chain reaction (PCR) using an average of two hairs for each animal. Samples were obtained with barbed wire placed at the traps, which contained food as bait. Multiplex PCR was performed with the GenomiPhiTM, G.E. kit and genotyping with an automated DNA sequencing machine (ABI 310 System). Allelic frequency, heterozygosis and exclusion probability of seven DNA microsatellites were calculated and analyzed with computer programs to determine the population density. Three of the microsatellites had a heterozygosis higher than 0.7 and the population density was calculated in at least 1 bear/km2.Keywords: Black bear, Ursus americanus, population size, DNA microsatellite, MexicoAfrican Journal of Biotechnology Vol. 12(2), pp. 103-10

    Analysis of the pathogenic potential of nosocomial Pseudomonas putida strains

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    Pseudomonas putida strains are ubiquitous in soil and water but have also been reported as opportunistic human pathogens capable of causing nosocomial infections. In this study we describe the multilocus sequence typing of four P. putida strains (HB13667, HB8234, HB4184 and HB3267) isolated from in-patients at the Besançon Hospital (France). The four isolates (in particular HB3267) were resistant to a number of antibiotics. The pathogenicity and virulence potential of the strains was tested ex vivo and in vivo using different biological models: human tissue culture, mammalian tissues and insect larvae. Our results showed a significant variability in the ability of the four strains to damage the host; HB13667 did not exhibit any pathogenic traits, HB4184 caused damage only ex vivo in human tissue cultures, and HB8234 had a deleterious effect in tissue culture and in vivo on rat skin, but not in insect larvae. Interestingly, strain HB3267 caused damage in all the model systems studied. The putative evolution of these strains in medical environments is discussed
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