32 research outputs found

    Dificultades en la producción argumentativa escrita en ingresantes universitarios

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    Luego de haber analizado las producciones escritas de los alumnos de acuerdo con el plan de categorías organizado a tal efecto, nos propusimos identificar las dificultades que tuvieron los alumnos para poder argumentar. La inquietud planteada se originó a partir de los resultados que obtuvimos del análisis del nivel de desarrollo actual de habilidades argumentativas escritas de los ingresantes. En concreto se les había solicitado que expresaran su punto de vista respecto de las razones expresadas por un autor de un texto de opinión para una parte de la muestra y de un texto académico a la otra parte de la muestra. En ambos casos se solicitaban dos pedidos, el primero era que expresara su punto de vista respecto de la posición adoptada por el autor justificándola, el segundo pedido solicitaba que adoptara la posición contraria a la que había adoptado en el primer pedido, justificándola.Eje: Psicología y EducaciónPublicado en: Memorias del IV Congreso Internacional de Investigación de la Facultad de Psicología: conocimiento y práctica profesional : perspectivas y problemáticas actuales - Tomo IFacultad de Psicologí

    Formation of self-organized Mn3O4 nanoinclusions in LaMnO3 films

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    et al.We present a single-step route to generate ordered nanocomposite thin films of secondary phase inclusions (Mn3O4) in a pristine perovskite matrix (LaMnO3) by taking advantage of the complex phase diagram of manganese oxides. We observed that in samples grown under vacuum growth conditions from a single LaMnO3 stoichiometric target by Pulsed Laser Deposition, the most favorable mechanism to accommodate Mn2+ cations is the spontaneous segregation of self-assembled wedge-like Mn3O4 ferrimagnetic inclusions inside a LaMnO3 matrix that still preserves its orthorhombic structure and its antiferromagnetic bulk-like behavior. A detailed analysis on the formation of the self-assembled nanocomposite films evidences that Mn3O4 inclusions exhibit an epitaxial relationship with the surrounding matrix that it may be explained in terms of a distorted cubic spinel with slight (~9°) c-axis tilting. Furthermore, a Ruddlesden-Popper La2MnO4 phase, helping to the stoichiometry balance, has been identified close to the interface with the substrate. We show that ferrimagnetic Mn3O4 columns influence the magnetic and transport properties of the nanocomposite by increasing its coercive field and by creating local areas with enhanced conductivity in the vicinity of the inclusions.Financial support from the Spanish Ministry of Economy and Competitiveness, through the “Severo Ochoa” Program for Centres of Excellence in R&D (SEV-2015-0496 and SEV 2013-0295), Projects MAT2011-29081 and MAT2015-71664-R and Ministry of Education and Science of Serbia (Grant—III45018) is acknowledged. This work has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 645658 (DAFNEOX Project). NB thanks the Spanish MINECO for financial support through the FPI program.Peer reviewedPeer Reviewe

    Nonstoichiometry driven ferromagnetism in double perovskite La2Ni1-xMn1+ xO6 insulating thin films

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    This is an open access article published under an ACS AuthorChoice License. See Standard ACS AuthorChoice/Editors' Choice Usage AgreementIn this work we report on the epitaxial growth of LaNiMnO double perovskite thin films on top of (001) oriented SrTiO substrates by RF magnetron sputtering. The influence of oxygen pressure (P O) and growth temperature on the microstructure, stoichiometry of the films, and magnetic and transport properties is thoroughly investigated. It is found that high oxygen pressure promotes the growth of stoichiometric films, with a Ni/Mn ratio almost equal to 1. However, these films exhibit poor ferromagnetic properties with respect to the expected optimum values corresponding to ferromagnetic ordering mediated by superexchange interaction between Mn and Ni according to the Goodenough-Kanamori rules. Most interestingly, films grown at low P O exhibit Ni/Mn ratios below 1, but ferromagnetic properties close to the optimal ones. The valence balance between Ni and Mn ions in nonstoichiometric sample has been elucidated by X-ray absorption spectroscopy. The results indicate that Ni deficiency plays a crucial role in the puzzling insulating ferromagnetic behavior observed in nonstoichiometric samples

    Engineering the microstructure and magnetism of La2CoMnO6-δ thin films by tailoring oxygen stoichiometry

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    Under the terms of the Creative Commons Attribution (CC BY) license to their work.We report on the magnetic and structural properties of ferromagnetic-insulating La2CoMnO6-δ thin films grown on top of (001) SrTiO3 substrates by means of RF sputtering technique. Careful structural analysis, by using synchrotron X-ray diffraction, allows identifying two different crystallographic orientations that are closely related to oxygen stoichiometry and to the features (coercive fields and remanence) of the hysteresis loops. Both Curie temperature and magnetic hysteresis turn out to be dependent on the oxygen stoichiometry. In situ annealing conditions allow tailoring the oxygen content of the films, therefore controlling their microstructure and magnetic properties.We acknowledge financial support from the Spanish MEC (MAT2011-29081 and MAT2012-33207), CONSOLIDER (CSD2007-00041), and FEDER program. R.G., L.L.-M. and N.B. thank the Spanish MINECO for the financial support through the FPI program. The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) under Grant Agreement No. 312284.Peer Reviewe

    La producción de inferencias "on line" en la "prueba de lectura crítica", dentro del proceso de desgranamiento de los alumnos ingresantes a la UBA

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    El presente trabajo se desprende del proyecto de investigación UBACyT denominado “Desarrollo del pensamiento crítico en alumnos ingresantes a la UBA. Estudio de la trayectoria educativa: Promoción y desgranamiento”. Uno de los objetivos de la investigación fue conocer los procesos cognitivos que se despliegan durante la lectura de textos académicos. Nos propusimos conocer la comprensión lectora de los alumnos desgranados (Colombo y col. 2008) para verificar la presencia o ausencia de lectura crítica en ellos. La hipótesis que orienta nuestro trabajo es que “los alumnos que promocionan en el proceso educativo cambian su relación con los artefactos mediadores de una relación pragmática a una relación epistémica”. El instrumento utilizado, “Prueba de Lectura Crítica”, es la reestructuración estratégica del método que implementó Marciales Vivas (2003) en su tesis, referente de nuestra investigación. Consiste en la presentación a cada alumno de un texto académico y la solicitud de expresar sus ideas al finalizar la lectura de cada oración y al final de cada párrafo.Eje: Psicología educacional y orientación vocacionalFacultad de Psicologí

    La producción de inferencias "on line" en la "prueba de lectura crítica", dentro del proceso de desgranamiento de los alumnos ingresantes a la UBA

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    El presente trabajo se desprende del proyecto de investigación UBACyT denominado “Desarrollo del pensamiento crítico en alumnos ingresantes a la UBA. Estudio de la trayectoria educativa: Promoción y desgranamiento”. Uno de los objetivos de la investigación fue conocer los procesos cognitivos que se despliegan durante la lectura de textos académicos. Nos propusimos conocer la comprensión lectora de los alumnos desgranados (Colombo y col. 2008) para verificar la presencia o ausencia de lectura crítica en ellos. La hipótesis que orienta nuestro trabajo es que “los alumnos que promocionan en el proceso educativo cambian su relación con los artefactos mediadores de una relación pragmática a una relación epistémica”. El instrumento utilizado, “Prueba de Lectura Crítica”, es la reestructuración estratégica del método que implementó Marciales Vivas (2003) en su tesis, referente de nuestra investigación. Consiste en la presentación a cada alumno de un texto académico y la solicitud de expresar sus ideas al finalizar la lectura de cada oración y al final de cada párrafo.Eje: Psicología educacional y orientación vocacionalFacultad de Psicologí

    Formation of Self-Organized Mn3O4 Nanoinclusions in LaMnO3 Films

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    We present a single-step route to generate ordered nanocomposite thin films of secondary phase inclusions (Mn3O4) in a pristine perovskite matrix (LaMnO3) by taking advantage of the complex phase diagram of manganese oxides. We observed that in samples grown under vacuum growth conditions from a single LaMnO3 stoichiometric target by Pulsed Laser Deposition, the most favorable mechanism to accommodate Mn2+ cations is the spontaneous segregation of self-assembled wedge-like Mn3O4 ferrimagnetic inclusions inside a LaMnO3 matrix that still preserves its orthorhombic structure and its antiferromagnetic bulk-like behavior. A detailed analysis on the formation of the self-assembled nanocomposite films evidences that Mn3O4 inclusions exhibit an epitaxial relationship with the surrounding matrix that it may be explained in terms of a distorted cubic spinel with slight (~9°) c-axis tilting. Furthermore, a Ruddlesden-Popper La2MnO4 phase, helping to the stoichiometry balance, has been identified close to the interface with the substrate. We show that ferrimagnetic Mn3O4 columns influence the magnetic and transport properties of the nanocomposite by increasing its coercive field and by creating local areas with enhanced conductivity in the vicinity of the inclusions

    Modelling the spatial risk of malaria through probability distribution of Anopheles maculipennis s.l. and imported cases

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    Malaria remains one of the most important infectious diseases globally due to its high incidence and mortality rates. The influx of infected cases from endemic to non-endemic malaria regions like Europe has resulted in a public health concern over sporadic local outbreaks. This is facilitated by the continued presence of competent Anopheles vectors in non-endemic countries. We modelled the potential distribution of the main malaria vector across Spain using the ensemble of eight modelling techniques based on environmental parameters and the Anopheles maculipennis s.l. presence/absence data collected from 2000 to 2020. We then combined this map with the number of imported malaria cases in each municipality to detect the geographic hot spots with a higher risk of local malaria transmission. The malaria vector occurred preferentially in irrigated lands characterized by warm climate conditions and moderate annual precipitation. Some areas surrounding irrigated lands in northern Spain (e.g. Zaragoza, Logroño), mainland areas (e.g. Madrid, Toledo) and in the South (e.g. Huelva), presented a significant likelihood of A. maculipennis s.l. occurrence, with a large overlap with the presence of imported cases of malaria. While the risk of malaria re-emergence in Spain is low, it is not evenly distributed throughout the country. The four recorded local cases of mosquito-borne transmission occurred in areas with a high overlap of imported cases and mosquito presence. Integrating mosquito distribution with human incidence cases provides an effective tool for the quantification of large-scale geographic variation in transmission risk and pinpointing priority areas for targeted surveillance and prevention

    Repositioning of the global epicentre of non-optimal cholesterol

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    High blood cholesterol is typically considered a feature of wealthy western countries(1,2). However, dietary and behavioural determinants of blood cholesterol are changing rapidly throughout the world(3) and countries are using lipid-lowering medications at varying rates. These changes can have distinct effects on the levels of high-density lipoprotein (HDL) cholesterol and non-HDL cholesterol, which have different effects on human health(4,5). However, the trends of HDL and non-HDL cholesterol levels over time have not been previously reported in a global analysis. Here we pooled 1,127 population-based studies that measured blood lipids in 102.6 million individuals aged 18 years and older to estimate trends from 1980 to 2018 in mean total, non-HDL and HDL cholesterol levels for 200 countries. Globally, there was little change in total or non-HDL cholesterol from 1980 to 2018. This was a net effect of increases in low- and middle-income countries, especially in east and southeast Asia, and decreases in high-income western countries, especially those in northwestern Europe, and in central and eastern Europe. As a result, countries with the highest level of non-HDL cholesterol-which is a marker of cardiovascular riskchanged from those in western Europe such as Belgium, Finland, Greenland, Iceland, Norway, Sweden, Switzerland and Malta in 1980 to those in Asia and the Pacific, such as Tokelau, Malaysia, The Philippines and Thailand. In 2017, high non-HDL cholesterol was responsible for an estimated 3.9 million (95% credible interval 3.7 million-4.2 million) worldwide deaths, half of which occurred in east, southeast and south Asia. The global repositioning of lipid-related risk, with non-optimal cholesterol shifting from a distinct feature of high-income countries in northwestern Europe, north America and Australasia to one that affects countries in east and southeast Asia and Oceania should motivate the use of population-based policies and personal interventions to improve nutrition and enhance access to treatment throughout the world.Peer reviewe

    Contributions of mean and shape of blood pressure distribution to worldwide trends and variations in raised blood pressure: A pooled analysis of 1018 population-based measurement studies with 88.6 million participants

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    © The Author(s) 2018. Background: Change in the prevalence of raised blood pressure could be due to both shifts in the entire distribution of blood pressure (representing the combined effects of public health interventions and secular trends) and changes in its high-blood-pressure tail (representing successful clinical interventions to control blood pressure in the hypertensive population). Our aim was to quantify the contributions of these two phenomena to the worldwide trends in the prevalence of raised blood pressure. Methods: We pooled 1018 population-based studies with blood pressure measurements on 88.6 million participants from 1985 to 2016. We first calculated mean systolic blood pressure (SBP), mean diastolic blood pressure (DBP) and prevalence of raised blood pressure by sex and 10-year age group from 20-29 years to 70-79 years in each study, taking into account complex survey design and survey sample weights, where relevant. We used a linear mixed effect model to quantify the association between (probittransformed) prevalence of raised blood pressure and age-group- and sex-specific mean blood pressure. We calculated the contributions of change in mean SBP and DBP, and of change in the prevalence-mean association, to the change in prevalence of raised blood pressure. Results: In 2005-16, at the same level of population mean SBP and DBP, men and women in South Asia and in Central Asia, the Middle East and North Africa would have the highest prevalence of raised blood pressure, and men and women in the highincome Asia Pacific and high-income Western regions would have the lowest. In most region-sex-age groups where the prevalence of raised blood pressure declined, one half or more of the decline was due to the decline in mean blood pressure. Where prevalence of raised blood pressure has increased, the change was entirely driven by increasing mean blood pressure, offset partly by the change in the prevalence-mean association. Conclusions: Change in mean blood pressure is the main driver of the worldwide change in the prevalence of raised blood pressure, but change in the high-blood-pressure tail of the distribution has also contributed to the change in prevalence, especially in older age groups
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