133 research outputs found
Aprendizaje colaborativo guiado: Fundamentos y aplicaciones
Full text linkEl objetivo de esta exposición es describir un tipo de sistemas para la enseñanza asistida
por ordenador de reciente aparición, basados en el aprendizaje colaborativo guiado. Se
muestra así mismo el contexto en el que han surgido estos sistemas y las principales
ideas subyacentes. Igualmente se describe FACT, un framework para el desarrollo de
aplicaciones educativas basadas en aprendizaje colaborativo guiado, y algunas
aplicaciones desarrolladas con él
Developing applications with a framework for the analysis of the learning process and collaborative tutoring
Full text linkIn this paper we describe FACT, a Framework for the Analysis of
the learning process and Collaborative Tutoring, developed at Universidad
Autónoma de Madrid, Spain. First we describe guided collaborative tutoring;
the type of tutoring that FACT makes possible. After that, we show the
architecture of FACT, and different applications developed with it, as well as
how it can be used to build new teaching tools from simple training
applications. FACT uses learning histories and related annotations to enhance
the guidance of the teaching process. It allows students and tutors to review the
work of the students and the history of their work sessions, using the original
application, while allowing reviewers to extend that history. Optionally,
reviewers can attach commentaries to some points of the extended and revised
histories. The generated applications can be used collaboratively, either
synchronously or asynchronously. The generated histories can be stored in
order to create a knowledge database with solved problems and commentaries
from tutors and students
Lipid Involvement in Viral Infections: Present and Future Perspectives for the Design of Antiviral Strategies
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A gas-to-particle conversion mechanism helps to explain atmospheric particle formation through clustering of iodine oxides
Get PDFEmitted from the oceans, iodine-bearing molecules are ubiquitous in the atmosphere and a source of new atmospheric aerosol particles of potentially global significance. However, its inclusion in atmospheric models is hindered by a lack of understanding of the first steps of the photochemical gas-to-particle conversion mechanism. Our laboratory results show that under a high humidity and low HOx regime, the recently proposed nucleating molecule (iodic acid, HOIO2) does not form rapidly enough, and gas-to-particle conversion proceeds by clustering of iodine oxides (IxOy), albeit at slower rates than under dryer conditions. Moreover, we show experimentally that gas-phase HOIO2 is not necessary for the formation of HOIO2-containing particles. These insights help to explain new particle formation in the relatively dry polar regions and, more generally, provide for the first time a thermochemically feasible molecular mechanism from ocean iodine emissions to atmospheric particles that is currently missing in model calculations of aerosol radiative forcing
The first steps of iodine gas-to-particle conversion as seen in the lab: constraints on the role of iodine oxides and oxyacids
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<p>The photooxidation of gas phase iodine-bearing molecules emitted by marine biota leads to intense particle nucleation events in the coastal and polar marine boundary layer<sup>1-3</sup>. The ubiquity of iodine in the marine atmospheric environment<sup>4-7</sup> has suggested that this may be a previously unrecognized global source of new aerosol particles<sup>8</sup>. Atmospheric modeling is required in order to evaluate the importance of this process, but a substantial lack of understanding of the gas-to-particle conversion mechanism is hindering this effort, especially regarding the gas phase chemistry of the nucleating molecules (iodine oxides<sup>9</sup><sup>,</sup><sup>10</sup> and/or oxyacids<sup>7</sup>) and the formation kinetics of molecular clusters. To address this problem, we have conducted new flow tube laboratory experiments where pulsed laser photolysis or continuous broad-band photolysis of I<sub>2</sub>/O<sub>3</sub> mixtures  in air are used to generate iodine radicals in the presence of atmospherically representative mixing ratios of water vapor. The molecular reactants and the resulting molecular products are detected by time-resolved VUV laser photo-ionization time-of-flight mass spectrometry. High-level quantum chemistry and master equation calculations and gas kinetics modelling are used to analyse the experimental data. In this presentation we discuss our results and their implications for the interpretation of field meassurements and for the implementatiion of an iodine oxide particle formation mechanism in atmospheric models.</p><p>References:</p><p>1. Hoffmann, T., O'Dowd, C. D. & Seinfeld, J. H. Iodine oxide homogeneous nucleation: An explanation for coastal new particle production. Geophys. Res. Lett. <strong>28</strong>, 1949-1952 (2001).</p><p>2. McFiggans, G. et al. Direct evidence for coastal iodine particles from Laminaria macroalgae - linkage to emissions of molecular iodine. Atmos. Chem. Phys. <strong>4</strong>, 701-713 (2004).</p><p>3. O'Dowd, C. D. et al. Marine aerosol formation from biogenic iodine emissions. Nature <strong>417</strong>, 632-636 (2002).</p><p>4. Prados-Roman, C. et al. Iodine oxide in the global marine boundary layer. Atmos. Chem. Phys. <strong>15</strong>, 583-593, doi:10.5194/acp-15-583-2015 (2015).</p><p>5. Schönhardt, A. et al. Simultaneous satellite observations of IO and BrO over Antarctica. Atmos. Chem. Phys. <strong>12</strong>, 6565-6580, doi:10.5194/acp-12-6565-2012 (2012).</p><p>6. Mahajan, A. S. et al. Concurrent observations of atomic iodine, molecular iodine and ultrafine particles in a coastal environment. Atmos. Chem. Phys. <strong>10</strong>, 27227-27253 (2010).</p><p>7. Sipilä, M. et al. Molecular-scale evidence of aerosol particle formation via sequential addition of HIO3. Nature <strong>537</strong>, 532-534, doi:10.1038/nature19314 (2016).</p><p>8. Saiz-Lopez, A. et al. Atmospheric Chemistry of Iodine. Chem. Rev. <strong>112</strong>, 1773–1804, doi:DOI: 10.1021/cr200029u (2012).</p><p>9. Gómez Martín, J. C. et al. On the mechanism of iodine oxide particle formation. Phys. Chem. Chem. Phys. <strong>15</strong>, 15612-15622, doi:10.1039/c3cp51217g (2013).</p><p>10. Saunders, R. W., Mahajan, A. S., Gómez Martín, J. C., Kumar, R. & Plane, J. M. C. Studies of the Formation and Growth of Aerosol from Molecular Iodine Precursor. Z. Phys. Chem. <strong>224</strong>, 1095-1117 (2010).</p>
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Macrophage-Dependent Interleukin-6-Production and Inhibition of I-K Contributes to Acquired QT Prolongation in Lipotoxic Guinea Pig Heart
Full text link[EN] In the heart, the delayed rectifier K current, I-K, composed of the rapid (I-Kr) and slow (I-Ks) components contributes prominently to normal cardiac repolarization. In lipotoxicity, chronic elevation of pro-inflammatory cytokines may remodel I-K, elevating the risk for ventricular arrythmias and sudden cardiac death. We investigated whether and how the pro-inflammatory interleukin-6 altered I-K in the heart, using electrophysiology to evaluate changes in I-K in adult guinea pig ventricular myocytes. We found that palmitic acid (a potent inducer of lipotoxicity), induced a rapid (~24 h) and significant increase in IL-6 in RAW264.7 cells. PA-diet fed guinea pigs displayed a severely prolonged QT interval when compared to low-fat diet fed controls. Exposure to isoproterenol induced torsade de pointes, and ventricular fibrillation in lipotoxic guinea pigs. Pre-exposure to IL-6 with the soluble IL-6 receptor produced a profound depression of I-Kr and I-Ks densities, prolonged action potential duration, and impaired mitochondrial ATP production. Only with the inhibition of I-Kr did a proarrhythmic phenotype of I-Ks depression emerge, manifested as a further prolongation of action potential duration and QT interval. Our data offer unique mechanistic insights with implications for pathological QT interval in patients and vulnerability to fatal arrhythmias.This study was supported by an AHA (13SDG16850065 to A.S.A), NIH (R01 HL147044 to A.S.A), and Programa Prometeu de la Conselleria d'innovacio, Universitats, Ciencia i Societat Digital de la Generalitat Valenciana (Award number prometeu/2020/043 to J.S).Chowdhury, MKH.; Martínez-Mateu, L.; Do, J.; Aromolaran, KA.; Saiz Rodríguez, FJ.; Aromolaran, A. (2021). Macrophage-Dependent Interleukin-6-Production and Inhibition of I-K Contributes to Acquired QT Prolongation in Lipotoxic Guinea Pig Heart. International Journal of Molecular Sciences. 22(20):1-15. https://doi.org/10.3390/ijms222011249S115222
New Insights into Martian Atmospheric Chemistry
Get PDFHO_x radicals are produced in the Martian atmosphere by the photolysis of water vapor and subsequently participate in catalytic cycles that recycle carbon dioxide (CO_2) from its photolysis product carbon monoxide (CO), providing a qualitative explanation for the stability of its atmosphere. Balancing CO_2 production and loss based on our current understanding of Martian gas-phase chemistry has, however, proven to be difficult. The photolysis of O_3 produces O(^1D), while oxidation of CO produces HOCO radicals, a new member of the HO_x family. The O(^1D) quantum yield has recently been updated, which quantifies nonzero quantum yields in the Huggins bands. In Earth’s atmosphere HOCO is considered to be unimportant since it is quickly removed by abundant oxygen molecules. The smaller amount of O_2 in the Mars’ atmosphere causes HOCO’s lifetime to be longer in Mars’ atmosphere than Earth’s (3 × 10^(-5) seconds to 1.2 days from Mars’s surface to 240 km, respectively). Limited kinetic data on reactions involving HOCO prevented consideration of its reactions directly in atmospheric models. Therefore, the impact of HOCO reactions on Martian chemistry is currently unknown. Here, we incorporate new literature rate constants for HOCO chemistry and an updated representation of the O(^1D) quantum yield in the Caltech/JPL 1-D photochemical model for Mars’ atmosphere. Our simulations exemplify perturbations to NO_y, HO_x, and CO_x species, ranging from 5 to 50%. The modified O(^1D) quantum yield and new HOCO chemistry cause a 10% decrease and a 50% increase in OH and H_2O_2 total column abundances, respectively. At low altitudes, HOCO production contributes 5% towards CO_2 production. Given recent experimentally-obtained branching ratios for the oxidation of CO, HOCO may contribute up to 70% toward the production of NO_y, where HO_x and NO_y species are enhanced up to a factor 3, which has implications for rethinking the fundamental understanding of NO_y, HO_x, and CO/CO_2 cycling on Mars. Two new reaction mechanisms for converting CO to CO_2 using HOCO reactions are proposed, which reveal that H_2O_2 is more intimately coupled to CO_x chemistry. Our simulations are in good agreement with satellite/spacecraft measurements of CO and H_2O_2 on Mars
Clinical infections by herpesviruses in patients treated with valproic acid: A nested case-control study in the Spanish Primary Care Database, BIFAP
Get PDFThe objective of this study is to evaluate the risk of clinical infections by herpesviruses in
patients exposed to valproic acid (VPA).We performed a case-control study nested in a primary cohort
selected from the Spanish primary care population-based research database BIFAP (Base de datos para
la Investigación Farmacoepidemiológica en Atención Primaria) over the period 2001–2015. The events
of interest were those diseases caused by any herpesviruses known to infect humans. For each
case, up to 10 controls per case matched by age, gender, and calendar date were randomly selected.
A conditional logistic regression was used to compute adjusted odds ratios (OR) and their 95%
confidence intervals (95% CI). Current use of VPA was associated with a trend towards a reduced risk
of clinical infections by herpesviruses as compared with non-users (OR 0.84; CI 95% 0.7–1.0; p = 0.057).
Among current users, a trend to a decreased risk with treatment durations longer than 90 days was
also observed. The results show a trend to a reduced risk of clinical infection by herpesviruses in
patients exposed to VPA. These results are consistent with those in vitro studies showing that, in
cultured cells, VPA can inhibit the production of the infectious progeny of herpesviruses. This study
also shows the efficient use of electronic healthcare records for clinical exploratory research studie
Predicción de la activación neuronal en estimulación tónica en la terapia de EME: uso de modelos 3D de médula espinal personalizados al paciente frente a modelos generalizados
Full text link[ES] La terapia de Estimulación de Médula Espinal (EME) es una
técnica utilizada para el tratamiento del dolor crónico. En
estimulación tónica, el objetivo es estimular las fibras sensitivas
Aß que se encuentran en los cordones posteriores de la médula
espinal. Esta estimulación produce una sensación de parestesia
que bloquea la señal del dolor. Sin embargo, el 35% de los
pacientes perciben una estimulación molesta, pues los cambios
posturales, la migración de los electrodos o una incorrecta
posición de los mismos produce cambios en la parestesia. En los
últimos 40 años se han desarrollado modelos computacionales de
médula espinal generalizados que permiten entender mejor el
efecto de los parámetros de estimulación y de la geometría de los
electrodos en la activación neuronal. Pero, el avance hacia una
medicina personalizada obliga a desarrollar modelos
computacionales personalizados al paciente para optimizar la
estimulación de forma individual. Para conocer las ventajas de
usar un modelo personalizado frente a uno generalizado, en este
estudio se ha comparado la predicción de la activación neuronal
y de los parámetros de estimulación que se obtiene de ambos
modelos con un caso real. Los resultados muestran que el modelo
personalizado predice de forma más aproximada la activación
neuronal y, por tanto, el efecto de la estimulación en un paciente.
Por tanto, el uso de modelos personalizados podría suponer en
un futuro la mejora de la eficacia de la terapia, pues se podría
optimizar la programación y la posición de los electrodos antes
del implante del sistema de EMESolanes, C.; Durá, JL.; Canós, MA.; De Andres, J.; Martí-Bonmatí, L.; Saiz Rodríguez, FJ. (2020). Predicción de la activación neuronal en estimulación tónica en la terapia de EME: uso de modelos 3D de médula espinal personalizados al paciente frente a modelos generalizados. Sociedad Española de Ingeniería Biomédica. 306-309. http://hdl.handle.net/10251/167126S30630
Consensus of experts from the Spanish Pharmacogenetics and Pharmacogenomics Society and the Spanish Society of Medical Oncology for the genotyping of DPYD in cancer patients who are candidates for treatment with fluoropyrimidines
Get PDF5-Fluorouracil (5-FU) and oral fluoropyrimidines, such as capecitabine, are widely used in the treatment of cancer, especially gastrointestinal tumors and breast cancer, but their administration can produce serious and even lethal toxicity. This toxicity is often related to the partial or complete deficiency of the dihydropyrimidine dehydrogenase (DPD) enzyme, which causes a reduction in clearance and a longer half-life of 5-FU. It is advisable to determine if a DPD deficiency exists before administering these drugs by genotyping DPYD gene polymorphisms. The objective of this consensus of experts, in which representatives from the Spanish Pharmacogenetics and Pharmacogenomics Society and the Spanish Society of Medical Oncology participated, is to establish clear recommendations for the implementation of genotype and/or phenotype testing for DPD deficiency in patients who are candidates to receive fluoropyrimidines. The genotyping of DPYD previous to treatment classifies individuals as normal, intermediate, or poor metabolizers. Normal metabolizers do not require changes in the initial dose, intermediate metabolizers should start treatment with fluoropyrimidines at doses reduced to 50%, and poor metabolizers are contraindicated for fluoropyrimidines
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