Ciencia y Tecnología

Influence of exchange in NMR pore size/relaxation correlation experiments

CONICET Digital -

Influence of exchange in NMR pore size/relaxation correlation experiments Silletta, Emilia Victoria; Franzoni, Maria Belen; Monti, Gustavo Alberto; Acosta, Rodolfo Héctor The influence of molecular exchange in porous polymeric systems on experiments that simultaneously correlate and determine pore length scales and surface relaxivities is studied. Pore length scales are determined by taking advantage of the internal field gradients generated by the difference in magnetic susceptibility between the polymer matrix and the contained water, namely the Decay Due to the Internal Field experiment. Transverse relaxation is codified in the detection period thus enabling correlation with the pore length. For the hierarchical very well connected porous polymer system, the considerable molecular exchange of water between different environments renders signals in the two-dimensional maps that make the determination of the surface relaxivity a complex problem.

Haloarchaea from the Andean Puna: Biological Role in the Energy Metabolism of Arsenic

CONICET Digital -

Haloarchaea from the Andean Puna: Biological Role in the Energy Metabolism of Arsenic Ordoñez, Omar Federico; Rasuk, Maria Cecilia; Soria, Mariana Noelia; Contreras, Manuel; Farias, Maria Eugenia Biofilms, microbial mats, and microbialites dwell under highly limiting conditions (high salinity, extreme aridity, pH, and elevated arsenic concentration) in the Andean Puna. Only recent pioneering studies have described the microbial diversity of different Altiplano lakes and revealed their unexpectedly diverse microbial communities. Arsenic metabolism is proposed to be an ancient mechanism to obtain energy by microorganisms. Members of Bacteria and Archaea are able to exploit arsenic as a bioenergetic substrate in either anaerobic arsenate respiration or chemolithotrophic growth on arsenite. Only six aioAB sequences coding for arsenite oxidase and three arrA sequences coding for arsenate reductase from haloarchaea were previously deposited in the NCBI database. However, no experimental data on their expression and function has been reported. Recently, our working group revealed the prevalence of haloarchaea in a red biofilm from Diamante Lake and microbial mat from Tebenquiche Lake using a metagenomics approach. Also, a surprisingly high abundance of genes used for anaerobic arsenate respiration (arr) and arsenite oxidation (aio) was detected in the Diamante’s metagenome. In order to study in depth the role of arsenic in these haloarchaeal communities, in this work, we obtained 18 haloarchaea belonging to the Halorubrum genus, tolerant to arsenic. Furthermore, the identification and expression analysis of genes involved in obtaining energy from arsenic compounds (aio and arr) showed that aio and arr partial genes were detected in 11 isolates, and their expression was verified in two selected strains. Better growth of two isolates was obtained in presence of arsenic compared to control. Moreover, one of the isolates was able to oxidize As[III]. The confirmation of the oxidation of arsenic and the transcriptional expression of these genes by RT-PCR strongly support the hypothesis that the arsenic can be used in bioenergetics processes by the microorganisms flourishing in these environments.

Spectral characteristics of road surfaces and eye transmittance: Effects on energy efficiency of road lighting at mesopic levels

CONICET Digital -

Spectral characteristics of road surfaces and eye transmittance: Effects on energy efficiency of road lighting at mesopic levels Preciado Olvera, Oscar Ulises; Manzano, Eduardo Roberto In 2010, the CIE published a recommended system for mesopic photometry based on visual performance. According to this system, scenes illuminated at mesopic levels with light sources of high S/P ratio, will produce better visual performance than those illuminated with light sources of a lower S/P ratio at equal photopic luminance. However, there could be other factors affected by SPD that, when quantified, could lead to a contradictory final effect. The scope of this paper was to evaluate how road lighting is affected by the spectral road surface reflectance and by the human eye transmittance as people get older. Our results suggest that the benefits of considering the mesopic vision effect for light sources with high S/P ratios are totally counteracted by the other two effects at mesopic luminances between 0.75 cd/m2 and 1.73 cd/m2 for people between 20 and 60 years of age, depending on the light source and the age of observers.

Acoustic confinement phenomena in oxide multifunctional nanophononic devices

CONICET Digital -

Acoustic confinement phenomena in oxide multifunctional nanophononic devices Bruchhausen, Axel Emerico; Lanzillotti Kimura, Norberto Daniel; Jusserand, B.; Soukiassian, A.; Schlom, D. G.; Dekorsy, T.; Fainstein, Alejandro The engineering of phononic resonances in ferroelectric structures appears as a new knob in the designand realization of novel multifunctional devices. In this work we experimentally study phononicresonators based on insulating (BaTiO 3 , SrTiO 3 ) and metallic (SrRuO 3 ) oxides. We experimentallydemonstrate the confinement of acoustic waves in the 100 GHz frequency range in a phonon nanocavity,the time and spatial beatings resulting from the coupling of two different hybrid nanocavities forming anacoustic molecule, and the direct measurement of Bloch-like oscillations of acoustic phonons in a systemformed by 10 coupled resonators. By means of coherent phonon generation techniques we study thephonon dynamics directly in the time-domain. The metallic SrRuO 3 introduces a local phonon generatorand transducer that allows for the spatial, spectral and time-domain monitoring of the complex generatedwaves. Our results introduce ferroelectric cavity systems as a new tool for the study of complex wavelocalization phenomena at the nanoscale.

Ricardo Piglia, editor

CONICET Digital -

Ricardo Piglia, editor Esposito, Fabio El trabajo se propone reconstruir la trayectoria de Ricardo Piglia como editor, desde sus primeras colaboraciones para la efímera editorial Nueve 64 en los primeros años de la década de 1960 hasta la dirección de la colección Serie del Recienvenido para el Fondo de Cultura Económica durante los últimos años de su vida, pasando por sus trabajos como editor freelance en Jorge Álvarez y Tiempo Contemporáneo. Su trabajo de editor fue algo más que un medio de vida cuando aún no podía mantenerse con la venta de sus libros. Fue una actividad que le permitió introducirse en el mundo literario y construir una carrera de escritor al amparo de un nuevo público lector que consumía con avidez los libros e impresos ofrecidos por las editoriales vinculadas con la nueva izquierda.; This essay aims to reconstruct the trajectory of Ricardo Piglia as editor, from his first collaboration for the ephemeral editorial Nueve 64 in the early 1960s to the collection Serie del Recienvenido for Fondo de Cultura Económica, in the later years of his life, and his work as freelance editor in Jorge Álvarez and Tiempo Contemporáneo. His work as editor was more than a means of subsistence when he still could not support himself with book sales. It was an activity that allowed him to introduce himself in the literary world and build a writing career under the wing of a new reading public that readily consumed the books and printed materiales offered by editorials related to the New Left.

Modalidades de explotación, procesamiento y consumo de pinnípedos en la margen meridional de Tierra del Fuego

CONICET Digital -

Modalidades de explotación, procesamiento y consumo de pinnípedos en la margen meridional de Tierra del Fuego Martinoli, Maria Paz En términos generales, en cuanto al modo de subsistencia, es posible sostener que los pinnípedos fueron una de las fuentes energéticas principales de los grupos que habitaron el sur del archipiélago fueguino. No obstante, se observa variabilidad temporo-espacial en la importancia económica de estas presas en la dieta de los cazadores-recolectores-pescadores de esta amplia región. En algunos trabajos se avanzó sobre aspectos relacionados con la explotación de estos animales, particularmente en la región central de la costa norte canal Beagle: dos contextos del Holoceno medio, el Segundo Componente de Túnel I (Schiavini 1990, 1993) y el Segundo Componente de Imiwaia I. Sin embargo, en la mayoría de los conjuntos de la costa sur del archipiélago fueguino -especialmente en Moat, Península Mitre y en la Isla delos Estados- se desconocen las posibles pautas de aprovisionamiento, procesamiento, transporte y consumo seleccionadas por los grupos humanos que habitaron la región, y si estas variaron a lo largo del tiempo. El objetivo principal de la presente tesis es analizar en perspectiva comparativa las modalidades de explotación de pinnípedos en la costa sur de Tierra del Fuego y en la Isla de los Estados, y sus variaciones a lo largo del Holoceno.

Evaluation of classical reinforcement and passive control systems on a reinforced concrete bridge subjected to seismic loading

CONICET Digital -

Evaluation of classical reinforcement and passive control systems on a reinforced concrete bridge subjected to seismic loading Nanclares, Germán Aníbal; Ambrosini, Ricardo Daniel; Curadelli, Raul Oscar In this paper, different strategies are studied with the main objectiveto reduce structural demand and damage of an existent bridge in Mendoza,Argentina, with post-tensioning reinforced concrete girders that are a commonstructural typology in the region. A numerical study was carried out with thispurpose. The numerical model was calibrated against experimentalmeasurements of vibration natural frequencies. The alternatives studied are:a) classical reinforcement of the structural overall stiffness; b) tuned massdampers; c) viscous dampers; d) metallic dampers. The model is subjected toreal near-fault seismic records, thereby obtaining response parameters toevaluate the efficiency of each protective system. The response is evaluated notonly in terms of reduction of displacements, but also in increasing of shearforce in key elements, which is a negative characteristic of some of the systemsstudied. Advantages and disadvantages of each studied system are highlighted.

La adopción de una ontología matemática en la filosofía de Alain Badiou. Algunas de sus implicancias políticas

CONICET Digital -

La adopción de una ontología matemática en la filosofía de Alain Badiou. Algunas de sus implicancias políticas García Ponzo, Leandro El presente trabajo explora la relación entre la ontología propuesta por AlainBadiou y algunas de sus consecuencias políticas mediatas. Se trata de una tesis queha sido construida. Primeramente, a partir de una preocupación política casiomnipresente: la de la emancipación, si quiera local, de los explotados y de losoprimidos. En ese sentido, ha recibido su impulso de una necesidad menos teóricaque biográfica. A esto se ha añadido un interés particular por una filosofía -y unfilósofo- que se ha ocupado obsesivamente de la misma preocupación. Dicho interésposee además una filiación suplementaria: la del gusto por la filosofía platónica, queprecede incluso al momento de redactar el proyecto de esta tesis. Estos tres intereses disjuntos han acabado por reunirse, o al menos eso es algoque esperamos poner en juego aquí. Badiou, platónico él mismo, reivindica sí para lacontinuidad de esa filosofía libertaria en el linaje que se abre después de Marx. Sigue,como propuso su maestro Althusser, la exploración de esa escarpada senda quequiere forjar una filosofía materialista. Para ello discutirá hasta la concepción marxianade política.Creemos que en ese intento, Badiou despliega una estrategia sin precedentes,en donde la apelación fundamental será a la figura de Platón. Allí repetirá un recursoque estuvo desde siempre en el origen de la filosofía sistemática: la toma y el uso delmatema, es decir, del dispositivo matemático en tanto tal, para otorgarle un estatutoontológico específico. De ese modo intentará resolver otras cuestiones cruciales en supretensión por continuar aquella dinastía materialista.Así, la hipótesis que vertebra el presente escrito se anuncia como sigue: existeuna operación fundamental, que puede nombrarse como "buena repetición" respectode una operación originaria efectuada por Platón, que le permitió a Badiou rehabilitarla filosofía y preservar una política emancipatoria relativamente eficaz, pero que hoy semuestra -teórica y prácticamente- insuficiente. A su vez, esa insuficiencia es inherentea la operación fundamental. La presente investigación, entonces, intentará ofrecer undetalle de este tránsito, a la vez que albergar algunas preguntas -y quizás respuestas-a la mentada insuficiencia.

ℓ-boson stars

CONICET Digital -

ℓ-boson stars Alcubierre, Miguel; Barranco, Juan; Bernal, Argelia; Degollado, Juan Carlos; Diez Tejedor, Alberto; Megevand Politano, Miguel Federico; Núñez, Darío; Sarbach, Olivier We present new, fully nonlinear numerical solutions to the static, spherically symmetric Einstein-Klein-Gordon system for a collection of an arbitrary odd number N of complex scalar fields with an internal symmetry and no self-interactions. These solutions, which we dub -boson stars, are parametrized by an angular momentum number ℓ =(N - 1)/2, an excitation number n, and a continuous parameter representing the amplitude of the fields. They are regular at every point and possess a finite total mass. For ℓ = 0the standard spherically symmetric boson stars are recovered. We determine their generalizations for ℓ ≤ 0, and show that they give rise to a large class of new static configurations which might have a much larger compactness ratio than stars.

La asistencia técnica internacional del Ministerio de Turismo argentino

CONICET Digital -

La asistencia técnica internacional del Ministerio de Turismo argentino; International technical assistance of the Ministry of Tourism of Argentina Navarro, Diego Mauricio Esta investigación se propone explorar las acciones de asistencia técnica del Ministerio de Turismo argentino a Estados de Sudamérica y el Caribe entre 2009 y 2014. A tales efectos, se prevén dos objetivos específicos (teórico y empírico): 1. Analizar la asistencia técnica y el turismo como formas de construcción de poder blando, con marco en la teoría de la interdependencia compleja; y 2. Identificar las acciones exteriores de asistencia técnica del Ministerio de Turismo. A tales efectos, se revisan las gacetillas de prensa del Ministerio de Turismo desde 2009; los tratados turísticos en Biblioteca Digital de Tratados de la Cancillería argentina; y los proyectos de cooperación internacional (particularmente aquéllos financiados por el FO.AR. (Fondo Argentino de Cooperación Sur-Sur y Triangular).; This research studies the technical assistance developed by Argentina ́s Ministry of Tourism (MinTur) in South American and Caribbean States between 2009 and 2014. Its specifics aims are: 1. From a theoretical perspective, analysing technical assistance and tourism as sources for building soft power (theory of complex interdependence); 2. Identify foreign actions on technical assistance of the Ministry of Tourism. For that purpose, several sources are checked: Ministry of Tourism news since 2009 (MinTur website); tourist treaties (Treaties Digital Library - Argentine Chancery); and international cooperation projects, particularly those financed by the Argentine Found for South-South and Triangular Cooperation (FO.AR.).

Páginas

Suscribirse a Facultad de Ciencias Químicas de la Universidad Nacional de Córdoba agregador - Ciencia y Tecnología