Geología de la Ventania (Provincia de Buenos Aires, Argentina)

La provincia geológica de Ventania, en el SO de la Provincia de Buenos Aires, República Argentina, constituye el afloramiento más importante, dentro de la Placa Sudamericana, de una extensa cuenca paleozoica desarrollada en el margen del Gondwana y que, junto, con otros sectores ahora expuestos en Suráfrica, Australia, y Antártida fue deformada en el Permo-Triásico para formar los Gondwánides. En el área que nos ocupa la cuenca sedimentaria fue rellenada entre el Paleozoico Inferior y el Superior y deformada en un único episodio en condiciones de moderada presión y temperatura, que no superaron los 400º C y los 2Kb. La estructura sobresaliente es el plegamiento en diversos órdenes, cuya intensidad decrece de oeste a este. La forma sigmoidal de la cadena, así como muchas de las micro y mesoestructuras se interpretan como resultado de la presencia de componentes de cizalla durante la deformación, del mismo modo que la vergencia al NE de los planos axiales de los pliegues regionales.The geologic province of Ventania, in the south-west of the Province of Buenos Aires (Republica Argentina) is the most important outcrop on the South American Dpto. de Ciencias Geológicas, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires. * Email: [email protected]. 43 José Sellés-Martínez Plate of what formerly was a continuous basin fringing the south-western margin of Gondwana during Palaeozoic times. This part of the basin, along with what at present are the South African, Australian and Antarctic counterparts, was deformed in the Permo-Triassic to become the Gondwanides. In Ventania area, the basin was receptive from Lower to Upper Palaeozoic, and was deformed in a single episode under moderate pressure and temperature, actually about 400 C° y 23Kb. The most outstanding feature is the folding, at different scales, decreasing in intensity from SW to NE. The sigmoidal shape of the belt -and many of the micro- and mesostructures present- are the result of penetrative simple shear deformation acting on the horizontal plane. The SW tilting of axial planes of regional folds is assigned to vertical shear directed top to NE

Lower Paleozoic microestructures in the headwaters of Río Jachal, San Juan Province: Their description and interpretation

Group of microstructures present in the Ordovician Yerba Loca and Los Sombreros Formations (cropping out in the vicinity of Road 150, between cuesta del Viento and Los Túneles), are described and interpreted. Cleavage, joints and fractures, shear zones, planar and sigmoid (en echelon) veins and kink bands are most common among them. Folded and domino faulted quartz veins, resulting from pressure solution contraction during formation of axial plane cleavage, are an outstanding feature and allowed calculation of contraction associated to cleavage development. The assemblage of minor structures shows coherency with the major structures hosting them and evidences a systematic displacement and stacking of rock masses from west to east. They also show the important participation of pressure solution and re-crystallization processes during deformation, along with progressive deformation due to rotation of local structures in the regional stress field.Fil:Sellés-Martínez, J. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Azcurra, D. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Lower Paleozoic structure in the headwaters of Río Jachal, San Juan Province

Structures cropping out in the Jachal Valley from the Cuesta del Viento dam to the locality of Los Tuneles are described and analyzed. These structures affect the Ordovician Yerba Loca and Los Sombreros Formations and the Paleogene-Neogene Vallecito and Rodeo Formations. The oldest units form the heights, Sierra Negra de Rodeo and Sierra de los Túneles, which are limited in their eastern flanks by the La Tranca and Los Blanquitos overthrusts, and by the angular unconformity underlying Rodeo Formation in their western ones. The regional folds show asymmetrical shapes and a wavelength comparable to the width of the Sierras, but minor structures ranging from meters to tens of meters are very common in their eastern limbs. Regional folds axis trend varies from Az 315 to Az 360 and the vergence of pre-carboniferous and andean structures point to the east, what makes very difficult to use orientation as a criterion to discriminate the differentiated deformational episodes. The comparison of sedimentological and structural features in the Rodeo area with those at the San Juan River evidences strong similarities but also important differences. Among the first ones, it can be mentioned the lithological and structural resemblance of the Ordovician units, which show NS trending axis in the eastern outcrops and point N-NW in the western ones. Main differences are the absence -in the Rodeo area- of the metapelites of the Silurian Calingasta Formation. and that of the conglomerates and rhythmites of the Devonian (?) El Planchón Formation. present in the San Juan River section.Fil:Sellés-Martínez, J. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Azcurra, D. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

Current and Future Use of Artificial Intelligence in Electrocardiography.

Artificial intelligence (AI) is increasingly used in electrocardiography (ECG) to assist in diagnosis, stratification, and management. AI algorithms can help clinicians in the following areas: (1) interpretation and detection of arrhythmias, ST-segment changes, QT prolongation, and other ECG abnormalities; (2) risk prediction integrated with or without clinical variables (to predict arrhythmias, sudden cardiac death, stroke, and other cardiovascular events); (3) monitoring ECG signals from cardiac implantable electronic devices and wearable devices in real time and alerting clinicians or patients when significant changes occur according to timing, duration, and situation; (4) signal processing, improving ECG quality and accuracy by removing noise/artifacts/interference, and extracting features not visible to the human eye (heart rate variability, beat-to-beat intervals, wavelet transforms, sample-level resolution, etc.); (5) therapy guidance, assisting in patient selection, optimizing treatments, improving symptom-to-treatment times, and cost effectiveness (earlier activation of code infarction in patients with ST-segment elevation, predicting the response to antiarrhythmic drugs or cardiac implantable devices therapies, reducing the risk of cardiac toxicity, etc.); (6) facilitating the integration of ECG data with other modalities (imaging, genomics, proteomics, biomarkers, etc.). In the future, AI is expected to play an increasingly important role in ECG diagnosis and management, as more data become available and more sophisticated algorithms are developed.Manuel Marina-Breysse has received funding from European Union’s Horizon 2020 research and innovation program under the grant agreement number 965286; Machine Learning and Artificial Intelligence for Early Detection of Stroke and Atrial Fibrillation, MAESTRIA Consortium; and EIT Health, a body of the European Union.S

Misleading Analogies that Lead to the Belief that the Mantle of the Earth is Liquid

The use of analogous models has proven to be a very useful tool for enhancing comprehension of complex scientific concepts but, in several cases, it may render undesired results. The structure, rheological properties and dynamics of the Earth’s mantle are usually modeled using some fluid (water, oil, etc.) heated in a container. A survey through children's introductory science books has rendered alarming results. Most of the books, taking the analogous for the object of study, assign the properties of the materials used in the model to the materials of the earth, what is certainly not true. This mistake is reinforced by at least two facts. The first is that most illustrations about volcanoes show these structures being fed directly from a "hot and mobile" mantle. The second fact is that scaling parameters are never taken into consideration when describing or performing the simulation. The situation is not to be neglected. The misuse of these analogies have resulted in widespread misconceptions among the general public, many teachers, and worst of all, the authors of books on science education. Several strategies to overcome this situation are proposed, focusing in the explanation of what models do accurately represent and what they do not. Scaling parameters, like size, time and -most important- the viscosity of the materials involved, need to be emphasized when using models

El registro del Mesón de Fierro en la cartografía de los siglos XVI a XIX

Since the mid-16th Century and until today, the meteorites of Campo del Cielo (Chaco and Santiago del Estero) have been subject of study and numerous expeditions set out to find it, but not always successfully. They generated no more than two cartographic documents, one of them -corresponding to the expedition of Francisco de Ibarra in 1779- has been lost and the following, corresponding to the expedition of Miguel Rubin de Celis of the year 1783, is preserved in different copies. In all other maps, the location of the Mesón de Fierro and the itineraries of the expeditions have been reconstructed on tabulated data (distances traveled between points) or copied from the Rubin de Celis map. As curious facts, the location of the “Penol de hieiro” is included on a Dutch map from the year 1640, which is the oldest mention found by the author, and the anachronistic mention of a “Native iron” location on an English map of 1850.Desde mediados del Siglo XVI y hasta la actualidad, los meteoritos del Campo del Cielo (Chaco y Santiago del Estero) han sido motivo de estudio y numerosas expediciones se propusieron dar con él, no siempre con éxito. Como resultado de las mismas no se habrían generado más que dos documentos cartográficos, uno de ellos -correspondiente a la expedición de Francisco de Ibarra en el año 1779- se ha perdido y del siguiente, correspondiente a la expedición de Miguel Rubin de Celis del año 1783, se conservan algunas copias. En todos los demás mapas la localización del Mesón de Fierro y los itinerarios de las expediciones han sido reconstruidos sobre los datos tabulados (distancias recorridas entre puntos) o copiados del mapa de Rubin de Celis. Como datos curiosos se incluye la localización del “Penol de hieiro” en un mapa holandés del año1640, que es la mención más antigua encontrada por el autor, y la anacrónica mención a una localidad  “Native iron” en un mapa inglés de 1850

M. Doello Jurado and the acquisition of “El Toba” meteorite by the Museum of Natural History in 1924

Se analiza el importante papel que el interés y la diligencia del Dr. M. Doello Jurado tuvieron en la adquisición del meteorito El Toba para la colección del entonces Museo de Historia Natural y las convicciones que lo llevaron a moverse con toda celeridad para que el mismo no fuera destruido ni comercializado inescrupulosamente. Para ello contó con la colaboración del Dr. Antenor Álvarez, médico sanitarista y político que llegó a ser Gobernador de Santiago del Estero, quién le informa de su existencia y el peligro de su destrucción. El trabajo de campo, la nada fácil tarea de transportar las más de cuatro toneladas de hierro desde el monte chaqueño hasta las instalaciones del museo en la calle Bernardo de Irigoyen fue encomendada al naturalista Enrique de Carles, quién -según él mismo señala y agradece- contó para ello con el apoyo de numerosas personas e instituciones como el Ejército Argentino y el Ferrocarril Central Córdoba. Carles es también el responsable de la redacción del informe y memoria de la labor de campo. El informe final que Doello Jurado eleva al Ministro de Justicia e Instrucción Pública termina con un enfático párrafo en el que el autor deja en claro su firme convicción de que el valor científico, y no el material, justifica que los meteoritos caídos y por caer en el territorio de la Nación deban ser considerados de propiedad de ésta y conservados en sus museos para la investigación y la educación del pueblo.The important role that the interest and diligence of Dr. M. Doello Jurado played in the acquisition of El Toba meteorite for the collection of the (at that time) Museum of Natural History, and the convictions that led him to proceed quickly to avoid it being destroyed or unscrupulously sold, are presented. In this task he was assisted by Dr. Antenor Alvarez, sanitarian physician and politic and ex-governor of Santiago del Estero, who informed him about the existence and danger of destruction of the meteorite. The fieldwork and the not easy task of transporting more than four tons of iron from the Chaco forest to the museum facilities at Bernardo de Irigoyen street was assigned to naturalist Enrique de Carles, who -as he points and acknowledges- was helped in his task by many people and institutions such as the Argentine Army and the Córdoba Central Railroad. De Carles is also responsible for drafting the official report and writing the memory of the fieldwork. The final report that Doello Jurado sends to the Minister of Justice and Public Instruction ends with an emphatic paragraph in which the author makes clear his firm conviction that the scientific value, and not the material one, justifies that meteorites that had fallen or may fall into the territory of the Nation should be considered its property and preserved in museums for research and education of the people.Facultad de Ciencias Naturales y Muse