La "Oración de gracias" de Casimiro Gómez Ortega a la Real Academia de la Historia (5 de Octubre de 1770)

En la presente nota ofrecemos la transcripción y edición de la Oracidn de gracias que Casimiro Gómez Ortega leyó con motivo de su ingreso en la Real Academia de la Historia, el día 5 de octubre de 1770. Por su contenido podemos situar tal discurso en el contexto de la polémica acerca de la ciencia española. Dos de los científicos que intervinieron en dicha polémica durante el período ilustrado fueron José Quer (1695-1 764) y José Cavanilles (1 754-1804), los cuales presentan matices en sus escritos o en la elaboración de los mismos, que impiden una interpretación lineal.CAICYT y el CSi

Gradients from GOCE reveal gravity changes before Pisagua Mw = 8.2 and Iquique Mw = 7.7 large megathrust earthquakes

Considerable improvements in the measurement of the Earth gravity field from GOCE satellite mission have provided global gravity field models with homogeneous coverage, high precision and good spatial resolution. In particular, the vertical gravity gradient (Tzz), in comparison to the classic Bouguer anomaly, defines more accurately superficial mass heterogeneities. Moreover, the correction of these satellitederived data from the effect of Earth topographic masses by means of new techniques taking into account the Earth curvature, improves results in regional analyses. In a recent work we found a correlation between Tzz and slip distribution for the 2010 Maule Mw= 8.8 earthquake. In the present work, we derive the vertical gravity gradient from the last GOCE only model, corrected by the topographic effect and also by the sediments on depocenters of the offshore region at the PerueChile margin, in order to study a spatial relationship between different lobes of the gravity derived signal and the seismic sources of large megathrust earthquakes. In particular, we analyze this relation for the slip models of the 1996 Mw = 7.7 Nazca, 2001 Mw = 8.4 Arequipa, 2007 Mw = 8.0 Pisco events and for the slip models of the 2014 Mw = 8.2 Pisagua and Mw = 7.7 Iquique earthquakes from Schurr et al. (2014), including the previously analyzed 2010 Mw = 8.8 Maule event. Then we find a good correlation between vertical gravity gradients and main rupture zones, correlation that becomes even stronger as the event magnitude increases. Besides this, a gravity fall in the gravity gradient was noticed over the area of the main slip patches at least for the two years before 2014 Mw = 8.2 Pisagua and Mw = 7.7 Iquique earthquakes. Additionally, we found temporal variations of the gravity field after 2010 Mw = 8.8 Maule event, related to the main patches of the slip distribution, and coseismic deformation. Therefore, we analyzed vertical gravity gradient field variations as an indirect measure of the variable seismic coupling finding a potential relationship between Tzz and the seismic b-value. These relationships exemplify the strong potential of the satellite only derived models as a predictive tool to determine potential seismic energy released in a subduction segment, determining the potential size of a potential rupture zone, and in particular internal slip distribution that allows inferring coseismic displacement field at surface

Analysis of variability in the manufacture of Cr-Co fixed partial dentures by geometric comparison

[EN] This article studies tridimensional adjustment of Cr-Co fixed partial dentures obtained with different manufacturing processes (CNC milling, laser metal sintering and lost-wax), making a special point of the most critical adjustment, the marginal fit. A model was obtained with the impression taken in the oral cavity of a patient. This model was digitalized, and serves as the reference for manufacturing fixed partial dentures using different manufacturing processes. This article proposes a method of comparing the original model with the fixed partial dentures. This comparison was carried out using commercial software, allowing dental technicians to obtain information which can identify errors and geometric discrepancies before the fixed partial denture is implanted in the patient.Gutiérrez, SC.; Meseguer, MD.; Bellera Sosa, J.; Folguera Arbas, F. (2013). Analysis of variability in the manufacture of Cr-Co fixed partial dentures by geometric comparison. Procedia Engineering. 63:481-488. doi:10.1016/j.proeng.2013.08.270S4814886

El terremoto del último 7 de septiembre : tiembla, todo tiembla

Fil: Folguera, Andrés. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Laboratorio de Tectónica Andina; Argentina.Fil: Triep, Enrique. Instituto de Sismología Volponi; Argentina.Fil: González Díaz, Emilio M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil: Ramos, Víctor A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Laboratorio de Tectónica Andina; Argentina.Los terremotos no son un fenómeno del pasado y las placas que conforman los niveles móviles más\nsuperficiales de la Tierra están aún en pleno movimiento. Con respecto a la intensidad de los mismos y\nsus desplazamientos asociados, la actividad actual, en especial la deformación permanente asociada\na estos terremotos, se ha mantenido en el mismo orden de magnitud que en los últimos 10 millones de\naños. La frecuencia con la que ocurren estos movimientos está también dentro del mismo orden,\nsiendo quizás la diferencia más significativa el avance de la tecnología y las comunicaciones de este\nmundo global que nos permiten conocer al instante este tipo de eventos en cualquier parte del planeta,\npareciendo de esta forma un fenómeno más periódico en la actualidad

New evidence about the subduction of the Copiap\uf2 ridge beneath South America, and its connection with the Chilean-Pampean flat slab, tracked by satellite GOCE and EGM2008 models

Satellite-only gravity measurements and those integrated with terrestrial observations provide global gravity field models of unprecedented precision and spatial resolution, which allow analyzing lithospheric structure allowing the analysis of the lithospheric structure. We used the model EGM2008 (Earth Gravitational Model) to calculate the gravity anomaly and the vertical gravity gradient in the South Central Andes region, correcting these quantities by the topographic effect. Both quantities show a spatial relationship between the projected subduction of the Copiap\uf3 aseismic ridge (located at 33 about 27\uba 30\u2019 S), its potential deformational effects in the overriding plate, and the Ojos del Salado-San Buenaventura volcanic lineament. This volcanic lineament constitutes a projection of the volcanic arc towards the retroarc zone, whose origin and development were not clearly understood. The analysis of the gravity anomalies, at the extrapolated zone of the Copiap\uf3 ridge beneath the continent, shows a change in the general NNE38 trend of the Andean structures to an ENE-direction coincident with the area of the Ojos del Salado-San Buenaventura volcanic lineament. This anomalous pattern over the upper plate is interpreted to be linked with the subduction of the Copiap\uf3 ridge. We explore the relation between deformational effects and volcanism at the northern Chilean-Pampean flat slab and the collision of the Copiap\uf3 ridge, on the basis of the Moho geometry and elastic thicknesses calculated from the new satellite GOCE data. Neotectonic deformations interpreted in previous works associated with volcanic eruptions along the Ojos del Salado-San Buenaventura volcanic lineament is interpreted as caused by crustal doming, imprinted by the subduction of the Copiap\uf3 ridge, evidenced by crustal thickening at the sites of ridge inception along the trench. Finally, we propose that the Copiap\uf3 ridge could have controlled the northern edge of the Chilean-Pampean flat slab, due to higher buoyancy, similarly to the control that the Juan Fernandez ridge exerts in the geometry of the flat slab further south

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

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

The matrix Kadomtsev--Petviashvili equation as a source of integrable nonlinear equations

A new integrable class of Davey--Stewartson type systems of nonlinear partial differential equations (NPDEs) in 2+1 dimensions is derived from the matrix Kadomtsev--Petviashvili equation by means of an asymptotically exact nonlinear reduction method based on Fourier expansion and spatio-temporal rescaling. The integrability by the inverse scattering method is explicitly demonstrated, by applying the reduction technique also to the Lax pair of the starting matrix equation and thereby obtaining the Lax pair for the new class of systems of equations. The characteristics of the reduction method suggest that the new systems are likely to be of applicative relevance. A reduction to a system of two interacting complex fields is briefly described.Comment: arxiv version is already officia

A Mobile Augmented Reality System for the Learning of Dental Morphology

[EN] Three-dimensional models are important when the learning content is difficult to acquire from 2D images or other traditional methods. This is the case for learning dental morphology. In this paper, we present a mobile augmented reality (AR) system for learning dental morphology. A study with students was carried out to determine whether learning outcomes were greater using the AR system or following a video session that was recorded in a real class. Other aspects were also considered. Thirty-eight undergraduate students, 6 Master's students and 11 employees of the center (most of them lecturers) participated in the study. The analysis about the acquired knowledge indicates that the students increased their knowledge using the two methods. When the post-knowledge scores for the two methods were compared, no statistically significant differences were found. Therefore, the AR system could be used as an effective transmitter of knowledge. The rest of the questions, which all of the participants answered, indicated that they were highly satisfied with the AR system, they considered the AR system to be very easy to use, and they would like to use it for dental learning. Moreover, as a mobile AR system, it could facilitate versatility in the learning process.Juan, M.; Alexandrescu, L.; Folguera, F.; García García, I. (2016). A Mobile Augmented Reality System for the Learning of Dental Morphology. Digital Education Review. (30):234-247. https://doi.org/10.1344/der.2016.30.234-247S2342473

Geometry of Middle to Late Triassic extensional deformation pattern in the Cordillera del Viento (Southern Central Andes): A combined field and geophysical study

Combined field and gravimetric-magnetic data reveal a complex pattern of extensional structures superimposed to the late Carboniferous – Early Permian Gondwanan orogen at the inner sectors of the Southern Central Andes, in the westernmost part of the Chos Malal fold and thrust belt at the cordillera del Viento area. W-NW, NW basement structures of regional significance, segmented by minor NE structures are bounding Late Triassic depocenters and structural highs corresponding to the cordillera del Viento rifting, equivalent to the Precuyo cycle. A pattern of roughly N-S trending structures recognized in the field associated with Andean thrusts do not show evidences of previ­ous structural controls, as they cut the magnetic anomalies. Field observations show that W-NW, NW and NE normal structures control changes in Late Triassic sedimentary thicknesses and are associated with synextensional geometries. Our model indicates that Late Triassic rifting in the area would have had a regional W-NW to NW trend being segmented by minor NE structures. Both sets were reactivated dur­ing Andean times, acting W-NW and NW structures as transfer zones between decoupled contractional panels and NE structures as frontal contractional structures. N-S contractional structures did not respect rifting architecture cutting through the depocenters and occasionaly exhuming synextensional geometries.La combinacion de datos de campo, junto con magnéticos y gravimétricos, revelan un patrón complejo de estructuras sobreimpuestas al orógeno gondwánico (Carbonífero superior– Pérmico) en el sector interno de la faja plegada y corrida de los Andes Centrales australes, en el área de la cordillera del Viento. Estructuras de basamento W-NW, NW de significancia regional, segmentadas por estruturas menores NE están limitando depocentros y altos estructurales correspondientes al rifting del Triásico Superior de la cordillera del Viento, equivalente de las unidades del ciclo Precuyo. En el campo se reconoce además un patrón de estructuras de rumbo N, asociadas a fallas andinas que no muestran evidencias de un control estrutural previo, ya que las anomalías magnéticas están cortadas por éstas. Las observaciones de campo demuestran que tanto las estructuras W-NW y NW como las NE controlan cambios de espesor de los sedimentos del Triásico Superior y se asocian a geometrías sinextensionales. El modelo propuesto indica que el rifting del Triásico Superior podría haber tenido una geometría elongada según el patrón de estructuras identificadas W-NW a NW, segmentado por estructuras menores NE. Ambas muestran reactivación durante tiempos andinos, las primeras actuando como zonas de transferencia entre sectores que muestran diferentes grados y mecánicas de contracción y las últimas como estructuras frontales contraccionales. Las estructuras contraccionales de orientación N-S no respetan la arquitectura del rift triásico, cortando los depocentros y eventualmente exhumando geometrías sinextensionales