210 research outputs found

    Critical Computation: Digital Automata and General Artificial Thinking

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    Since the 1980s, computational systems of information processing have evolved to include not only deductive methods of decision, whereby results are already implicated in their premises, but have crucially shifted towards an adaptive practice of learning from data, an inductive method of retrieving information from the environment and establish general premises. This shift in logical methods of decision-making does not simply concern technical apparatuses, but is a symptom of a transformation in logical thinking activated with and through machines. This article discusses the pioneering work of Katherine Hayles whose study of the cybernetic and computational infrastructures of our culture particularly clarifies this epistemological transformation of thinking in relation to machines

    Pressure stability field of Mg-perovskite under deep mantle conditions: A topological approach based on Bader's analysis coupled with catastrophe theory

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    The pressure stability field of the Mg-perovskite phase was investigated by characterizing the evolution of the electron arrangement in the crystal. Ab initio calculations of the perovskite structures in the range 0\u2013185 GPa were performed at the HF/DFT (Hartree-Fock/Density Functional Theory) exchange\u2013correlation terms level. The electron densities, calculated throughout the ab-initio wave functions, were analysed by means of the Bader's theory, coupled with Thom's catastrophe theory. To the best of our knowledge the approach is used for the first time. The topological results show the occurrence of two topological anomalies at P~20 GPa and P~110 GPa which delineate the pressure range where Mg-perovskite is stable. The paper accomplishes the twofold objectives of providing a contribution in shading light into the behaviour of the dominant component of the Earth's lower mantle across the D\u2019\u2019 layer and of proposing a novel approach in predicting the stability of a compound at extreme conditions

    An innovative method for highly-efficient fabrication of carbon fiber precursors via acrylonitrile emulsion copolymerization coupled to a chemical oscillator

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    A new synthetic protocol to produce the carbon fiber precursor polyacrylonitrile (PAN) and its block copolymers with polyethylene glycol (PEG) is proposed here. The constant flux of radical species produced at low concentrations during the oscillating Belousov-Zhabotinsky (BZ) reaction was properly exploited to initiate the radical polymerization reaction. Compared with conventional methods, this oscillating initiation decreases the probability of chain termination, thus favouring the production of high molecular weight polymers, and it does not require an inert atmosphere and elevated temperatures to be produced. The solubility of the polymeric chains during the polymerization reaction was improved by adding the anionic micelle-forming surfactant sodium dodecyl sulphate (SDS). Following the initiation step, short oligomer chains are able to overcome the micellar interface, thereby reaching a favourable environment for the increase of the polymeric chains, thus strongly contributing to the increase of the molecular weight of the fibers’ precursors. The synthesis was conducted by adding the monomer acrylonitrile (AN) to the unperturbed and PEG-perturbed BZ system after the onset of the oscillations, in the absence and presence of increasing amounts of the SDS surfactant. The potentiometric technique was utilized to detect the dynamics of the oscillatory reaction. Preliminarily, the response of the BZ system to the monomer addition was investigated. Additional information was provided from the study of the effect of the SDS and PEG concentration on the dynamics of the BZ reaction during AN polymerization, thus obtaining a deepening in the understanding of the BZ mechanism. The characterization of the obtained polymers and copolymers, by melting point measurements, molecular weight determinations, Fourier Transform Infrared (FTIR), X-ray diffraction (XRD) analyses, and thermal treatments, indicated that the proposed synthetic method produces carbon fiber precursors with high molecular weight and good thermal stability. The addition of the surfactant was revealed as a good method to improve and/or finely tune the precursor molecular weight. The proposed synthetic protocol represents a valuable alternative to conventional methods to produce highperformant precursors of carbon fibers

    Detection of a novel clone of Acinetobacter baumannii isolated from a dog with otitis externa

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    In this study, the isolation ofAcinetobacter baumanniiin a dog with clinical bilateral otitis externa is described.Moreover, to investigate the zoonotic potential of the isolate, microbiological examinations on the familymembers were performed. AnA. baumanniistrain was isolated from nasal swab in one of the dog owners. Theidentity of bacterial strains, either from dog and owner, was confirmed by phenotypic and molecular typing(wgMLST). Furthermore, to assess the pathogenic potential of the isolates a deep characterization of virulenceand antibiotic resistance genes was done by Whole Genome Sequencing (WGS). Finally, the susceptibility to-wards a wide panel of antimicrobials was investigated. In our knowledge, this is thefirst recorded case ofA.baumanniiisolation from canine auricular swabs in Italy. And interestingly, this study underlines the possiblespread of this microorganism from human to anima

    In Vitro Infection of Trypanosoma cruzi Causes Decrease in Glucose Transporter Protein-1 (GLUT1) Expression in Explants of Human Placental Villi Cultured under Normal and High Glucose Concentrations

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    Trypanosoma cruzi, the etiologic Chagas' disease agent, induces changes in protein pattern of the human placenta syncytiotrophoblast. The glucose transporter protein-1 (GLUT1) is the primary isoform involved in transplacental glucose transport. We carried out in vitro assays to determine if T. cruzi infection would induce changes in placental GLUT1 protein expression under normal and high concentration of glucose. Using Western blot and immunohistological techniques, GLUT1 expression was determined in normal placental villi cultured under normal or high concentrations of glucose, with or without in vitro T. cruzi infection, for 24 and 48 hours. High glucose media or T. cruzi infection alone reduced GLUT1 expression. A yet more accentuated reduction was observed when infection and high glucose condition took place together. We inform, for the first time, that T. cruzi infection may induce reduction of GLUT1 expression under normal and high glucose concentrations, and this effect is synergic to high glucose concentrations

    Avaliação ambiental do ciclo de vida de telhas de fibrocimento com fibras de amianto ou com fibras de polipropileno

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    Este trabalho teve por objetivo avaliar o ciclo de vida de telhas de fibrocimento fabricadas com fibras de amianto ou com fibras de polipropileno. Foram utilizadas as técnicas de Avaliação do Ciclo de Vida (ACV) e de Levantamento de Aspectos e Impactos Ambientais (Laia) para analisar comparativamente os impactos ambientais causados. Na ACV determinaram-se, para todas as etapas, as emissões atmosféricas causadoras do efeito estufa, da chuva ácida e as que possuem toxicidade humana, além do consumo de insumos (água e energia). No Laia agregaram-se à ACV os impactos de utilização de recursos naturais e os riscos à saúde devido aos fatores prejudiciais dos materiais constituintes das telhas. Foram avaliados dois cenários, onde se fixaram os locais de extração de matéria-prima, o local da obra e o aterro industrial para o qual seriam levados os resíduos das telhas após a vida útil deles, variando-se apenas os locais de fabricação das telhas. O cenário que empregou fibras de polipropileno foi mais vantajoso ambientalmente em quatro categorias entre as sete avaliadas, confirmando assim, com essa avaliação, que o uso de amianto é mais desfavorável que o uso de polipropileno sob o foco ambiental

    Formación de planetas gigantes y fragmentación de planetesimales

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    Durante el proceso de formación de un planeta gigante las velocidades relativas de los planetesimales aumentan debido a las perturbaciones gravitatorias que genera el planeta en formación sobre los mismos. Este fenómeno produce que las colisiones entre los planetesimales cambien de un régimen de coagulación a bajas velocidades relativas a un régimen de fragmentación a medida que dichas velocidades aumentan. En general, los modelos de formación planetaria, que incluyen el fenómeno de la fragmentación de los planetesimales, consideran la energía específica de impacto a una velocidad y un material fijos. Sin embargo la energía específica de impacto de un blanco es función tanto de las velocidades relativas entre el blanco y el proyectil como así también de la composición de los mismos. En este trabajo estudiamos la formación de un planeta gigante ubicado a 5 UA incorporando a nuestro modelo de fragmentación de planetesimales la dependencia de la energía específica de impacto con el material y la velocidad. Nuestros resultados muestran que dicha dependencia juega un rol importante en la formación de núcleos masivos, y por ende en la formación de planetas gigantes, antes de la disipación de la componente gaseosa del disco protoplanetario.During the process of giant planet formation the planetesimal relative velocities are increased by the growing planet due to the gravitational perturbations. This phenomenon produces a change of regimen in the planetesimal collision, from coagulation at low relative velocities to a regimen of fragmentation while the velocities increase. In general, the models of planetary formation that include planetesimal fragmentation consider the specific impact energy for a fixed velocity and composition of the plantesimals. However, the specific impact energy of a target is a function of the relative velocities between the target and projectile as well as the planetesimal composition. We studied the formation of a giant planet at 5 AU incorporating the dependence of the specific impact energy with composition and relative velocity in our fragmentation model. Our results show that this dependence plays a fundamental role in the formation of massive cores, and thus in the formation of giant planets, before the dissipation of the gaseous component of the protoplanetary disk.Fil: San Sebastián, Irina Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; ArgentinaFil: Guilera, Octavio Miguel. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Astrofísica La Plata. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas. Instituto de Astrofísica La Plata; ArgentinaFil: Parisi, Mirta Gabriela. Universidad Nacional de La Plata. Facultad de Ciencias Astronómicas y Geofísicas; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; Argentina60 Reunión Anual de la Asociación Astronomía de ArgentinaMalargüeArgentinaInstituto de Tecnologías en Detección y AstropartículasUNiversidad Nacional de Río NegroObservatorio Pierre Auge

    Ca II triplet spectroscopy of Small Magellanic Cloud red giants. IV. Abundances for a large sample of field stars and comparison with the cluster sample

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    This paper represents a major step forward in the systematic and homogeneous study of Small Magellanic Cloud (SMC) star clusters and field stars carried out by applying the Calcium Triplet technique. We present in this study the radial velocity and metallicity of approximately 400 red giant stars in 15 SMC fields, with typical errors of about 7 km/sec and 0.16 dex respectively. We added to this information our previously determined metallicity values for 29 clusters and approximately 350 field stars using the identical techniques. Using this enlarged sample, we analize the metallicity distribution and gradient in this galaxy. We also compare the chemical properties of the clusters and of their surrounding fields. We find a number of surprising results. While the clusters, taken as a whole, show no strong evidence for a metallicity gradient, the field stars exhibit a clear negative gradient in the inner region of the SMC consistent with the recent results of Dobbie et al. (2014b). For distances to the center of the galaxy less than 4 degrees, field stars show a considerable smaller metallicity dispersion than that of the clusters. However, in the external SMC regions, clusters and field stars exhibit similar metallicity dispersions. Moreover, in the inner region of the SMC, clusters appear to be concentrated in two groups: one more metal-poor and another more metal-rich than field stars. Individually considered, neither cluster group presents a metallicity gradient. Most surprisingly, the metallicity gradient for both stellar populations (clusters and field stars) appears to reverse sign in the outer regions of the SMC. The difference between the cluster metallicity and the mean metallicity of the surrounding field stars turns out to be a strong function of the cluster metallicity. These results could be indicating different chemical evolution histories for these two stellar populations. They could also indicate variations in the chemical behavior of the SMC in its internal and external regions. Fil: Parisi, Maria Celeste. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba. Departamento de Astrofísica Estelar; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Concepción; ChileFil: Geisler, D.. Universidad de Concepción; ChileFil: Carraro, G.. European Southern Observatory; ChileFil: Claria Olmedo, Juan Jose. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Villanova, S.. Universidad de Concepción; ChileFil: Gramajo, Luciana Veronica. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Córdoba. Observatorio Astronómico de Córdoba; ArgentinaFil: Sarajedini, A.. University of Florida; Estados UnidosFil: Grocholski, A.. State University of Louisiana; Estados Unido

    Certainties and uncertainties affecting the postdoctoral phase of the scientific career in Argentina

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    En la etapa posdoctoral enfrentamos una serie de desafíos e interrogantes que determinan nuestra formación y consolidación como jóvenes investigadores. Desde nuestra perspectiva, y en base a la orientación de un grupo de investigadores formados, pudimos identificar algunas reflexiones y herramientas que pueden ayudarnos a obtener buenos antecedentes académicos. La trasmisión de la producción propia al resto de la comunidad científica a través de publicaciones ocupa un lugar central. La preparación de una publicación no termina con la redacción del manuscrito. Es fundamental una adecuada elección de la revista, realizar una buena presentación del trabajo respetando el formato requerido, presentar una carta al editor que destaque el desarrollo conceptual y la originalidad de nuestro trabajo y su alcance a la audiencia que deseamos captar. No obstante, identificamos también la necesidad de hallar un balance entre la producción científica y la jerarquización de otras tareas, tales como la formación de recursos humanos, la docencia y el pedido de financiamiento, entre otras. La claridad en los requisitos necesarios para ingresar en la carrera científica del CONICET, la estabilidad de los recursos para investigar y la búsqueda de ideas relevantes para ir consolidando una línea de trabajo son otros aspectos claves en la etapa posdoctoral. Quedan varias preguntas e inquietudes por resolver. Con este artículo pretendemos abrir el debate a investigadores formados y en formación para encontrar alternativas más eficientes para el desarrollo de la carrera científica.In the postdoctoral stage several challenges and questions define our development and consolidation as researchers. Based on the guidance of trained researchers, we identified various certainties and uncertainties during this phase. We also highlight several tools to achieve a good academic performance and obtain a position as researchers of the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). The main certainty was that publishing is a 'must': it is essential to transmit the knowledge to the community and it is the most valued aspect by the CONICET. However, a publication involves much more than writing a manuscript. Detecting the conceptual contribution and the originality of our work is fundamental. One of the uncertainties identified was producing several high-impact publications, while performing other activities (e.g., human resources training, teaching, grant applications and stays abroad) during the seven years that fellowships usually last (five for Ph.D. and two for postdoctoral fellowships). Other uncertainties are the constantly changing rules and the increasing requisites to meet CONICET conditions for researchers. Besides, the scarce stability of resources to research and the need to develop original ideas are particularly uncertain at this stage. Those wanting to develop a scientific career in Argentina must outline a strategy. We propose ‘successful’ postdoctoral fellows’ profiles to find pathways towards a permanent position at the CONICET scientific career, with good development prospects. As a way to open a fruitful debate, your survey feedback will be highly valued. Said survey is available at (goo.gl/forms/k185nQG8ABxjL4bo2, until March 31st, 2019), addressed to doctoral students, postdoctoral fellows and researchers with permanent positions. This will allow opening the range of profiles and opinions. This debate may be a guide for those young researchers willing to perform successfully as Scientists within our country.Fil: Reyes, María Fernanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Piazza, María Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Telesnicki, Marta Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: D'acunto, Luciana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Di Bella, Carla Estefania. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Spirito, María Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: Garcia Parisi, Pablo Adrian. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Producción Animal. Cátedra de Forrajicultura; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones Fisiológicas y Ecológicas Vinculadas a la Agricultura; ArgentinaFil: de Paepe, Josefina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Ingeniería Agrícola y Uso de la Tierra. Cátedra de Fertilidad y Fertilizantes; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cavagnaro, Romina Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Recursos Naturales y Ambiente. Cátedra de Botánica Agrícola; Argentin

    Media Ontology and Transcendental Instrumentality

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    This article takes inspiration from Kittler’s claim that philosophy has neglected the means used for its production. Kittler’s argument for an ontology of media invites us to reflect upon the cybernetic mechanization of logic, which has led practical or instrumental knowledge to challenge the classical division between theory and practice, ideas and demonstrations. This article suggests that procedures, tasks, and functions are part of an instrumental thinking. By drawing on information theory and the mathematical logic of constructivism, the article addresses indeterminacy within automated logic and proposes a re-habilitation of instrumentality whereby the connection between means and ends is articulated away from classical idealism and analytic realism. By following John Dewey’s argument for instrumental reasoning, the article suggests that post-Kantian critique of techne shall be revisited in order to account for a machine philosophy, which has originated from within the practical thinking of machines
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