900 research outputs found
Aprendizaje con robótica, algunas experiencias
Este artículo presenta el análisis de experiencias, revisadas en diversos artículos, acerca de la implementación de la robótica en la educación, con el fin de obtener referentes pertinentes para la construcción de una propuesta para el aprendizaje de la robótica en la educación básica secundaria y media. Se consideran dos ámbitos de aplicación de la robótica en la educación: el primero es el aprendizaje de la robótica mediante la conceptualización de cada uno de los subsistemas de un robot para luego realizar la construcción de robots con diferentes propósitos, en este ámbito el objetivo es desarrollar las competencias, en los estudiantes, para el diseño y construcción de tecnofactos robóticos, mediante un proceso de construcción del conocimiento necesario para hacerlo; el segundo ámbito de aplicación es la utilización de la robótica como medio que motiva y da sentido a la construcción de conocimiento en diversas áreas, promoviendo habilidades y competencias en los estudiantes. Además, el aprendizaje de la robótica y el aprendizaje con robótica pueden ser mediados por la informática, la cual aporta tecnologías y herramientas software como los lenguajes de modelado matemático y simulación, tutoriales multimediales, laboratorios virtuales y remotos, entre otros. Así, este artículo se propone destacar cómo la robótica en el aula de clase permite, por una parte, el enriquecer estrategias de aprendizaje como apoyo a la formación integral de los estudiantes, y por otra, es un campo que presenta una demanda creciente en la atención de docentes e investigadores, así como en los estímulos para su investigación, desarrollo y divulgación de parte del estado
Density-Temperature-Softness Scaling of the Dynamics of Glass-forming Soft-sphere Liquids
The principle of dynamic equivalence between soft-sphere and hard-sphere
fluids [Phys. Rev. E \textbf{68}, 011405 (2003)] is employed to describe the
interplay of the effects of varying the density n, the temperature T, and the
softness (characterized by a softness parameter {\nu}^{-1}) on the dynamics of
glass-forming soft-sphere liquids in terms of simple scaling rules. The main
prediction is that the dynamic parameters of these systems, such as the
{\alpha}-relaxation time and the long-time self-diffusion coefficient, depend
on n, T, and {\nu} only through the reduced density n^\ast \equiv
n{\sigma}^{3}_{HS}(T, {\nu}),where the effective hard-sphere diameter
{\sigma}_{HS}(T, {\nu}) is determined, for example, by the
Andersen-Weeks-Chandler condition for soft-sphere-hard-sphere structural
equivalence. A number of scaling properties observed in recent simulations
involving glass-forming fluids with repulsive short range interactions are
found to be a direct manifestation of this general dynamic equivalence
principle. The self-consistent generalized Langevin equation (SCGLE) theory of
colloid dynamics is shown to accurately capture these scaling rule
Uso de Herramientas de Simulación Electrónica como Apoyo Docente en Electrónica de Potencia
El objetivo de este trabajo es el mostrar cómo las herramientas de simulación electrónica pueden apoyar didácticamente al profesor en la enseñanza de asignaturas relacionadas con la electrónica de potencia. Se va a presentar un ejemplo guiado de uso de este tipo de herramientas en para el diseño del circuito de control de un convertidor CC/CC para una aplicación de alimentación dual en el entorno del automóvil. Para diseñar el circuito de control es necesario determinar en primer lugar la respuesta en frecuencia del convertidor. Se va a hacer uso del programa Simplorer con la biblioteca SMPS Library como herramienta de simulación para este ejemplo. Existen modelos en dicha biblioteca que permiten obtener la respuesta en frecuencia del circuito de forma directa. Este artículo explica los pasos que deben seguirse para diseñar el circuito de control de un convertidor Buck multi-fase usando tanto modelos promediados como modelos conmutados
Teaching Magnetic Design using CAD tools
Design of magnetic components is a multivariable problem. There are many different combinations of shapes, sizes and materials for the core with many diameters for the wires. So it is difficult to find the optimum design without a great number of iterations. Analytically only a few combinations are usually studied but it is very easy to take into account all the combinations using a CAD tool [1]. In this work the CAD tool used is PExprt (ANSYS [2]) which is being developed at UPMCEI
Synthesis of IAN-type N,N-Ligands via Dynamic Kinetic Asymmetric Buchwald-Hartwig Amination
The Pd-catalyzed coupling of racemic heterobiaryl bromides, triflates, or nonaflates with aryl/alkyl primary amines using QUINAP as the ligand provides the corresponding axially chiral heterobiaryl amines with excellent yields and enantioselectivities. Reactivity and structural studies of neutral and cationic oxidative addition intermediates support a dynamic kinetic asymmetric amination mechanism based on the labilization of the stereogenic axis in the latter and suggest that coordination of the amine to the Pd center is the stereodetermining step.Ministerio de Ciencia e Innovación CTQ2013-48164-C2-1-P, CTQ2013-48164-C2-2-P, RYC-2013-12585 for A.R.European FEDER FundsJunta de Andalucía 2012/FQM 1078
Influence of irrigation conditions in the germination of plasma treated Nasturtium seeds
Plasma treatments had emerged as a useful technique to improve seed germination. In this work we investigate the influence of different irrigation conditions and plasma treatments on the germination of nasturtium seeds. During plasma treatment, seeds experience a progressive weight loss as a function of treatment time that has been associated to water release, a process that is more pronounced after longer plasma treatment times. Seeds treated for short times (<30 s) are able to germinate more efficiently than untreated specimen under hydric stress (drought conditions), while plasma treatments for longer times (up to 300 s) impaired germination independently on irrigation conditions. Characterization analysis of plasma treated seeds by FTIR-ATR, SEM/EDX and XPS showed that plasma treatment affected the chemical state of pericarp while, simultaneously, induced a considerable increase in the seeds water uptake capacity. The decrease in germination efficiency found after plasma treatment for long times, or for short times under optimum irrigation conditions, has been attributed to that the excess of water accumulated in the pericarp hampers the diffusion up to the embryo of other agents like oxygen which are deemed essential for germination.España FEDER y MINECO MINECO (projects MAT2013-40852-R, MAT2016-79866-R, MINECOCSIC 201560E055)España, RECUPERA 2020 y Junta de Andalucía project P12-2265 M
Experience with the use of Rituximab for the treatment of rheumatoid arthritis in a tertiary Hospital in Spain: RITAR study
There is evidence supporting that there are no
relevant clinical differences between dosing rituximab 1000 mg or 2000 mg
per cycle in rheumatoid arthritis (RA) patients in clinical trials, and low-dose
cycles seem to have a better safety profile. Our objective was to describe the
pattern of use of rituximab in real-life practice conditions.
Methods: Rituximab for RA in clinical practice (RITAR) study is a retrospective cohort study from 2005 to 2015. Eligibility criteria were RA adults
treated with rituximab for active articular disease. Response duration was
the main outcome defined as months elapsed from the date of rituximab
first infusion to the date of flare. A multivariable analysis was performed
to determine the variables associated with response duration.
Results: A total of 114 patients and 409 cycles were described, 93.0%
seropositive and 80.7% women. Rituximab was mainly used as second-line
biological therapy. On demand retreatment was used in 94.6% of cases
versus fixed 6 months retreatment in 5.4%. Median response duration
to on demand rituximab cycles was 10 months (interquartile range,
7–13). Multivariable analysis showed that age older than 65 years, number
of rituximab cycles, seropositivity, and first- or second-line therapy were
associated with longer response duration. The dose administered at each
cycle was not significantly associated with response duration.
Conclusions: Our experience suggests that 1000 mg rituximab single infusion on demand is a reasonable schedule for long-term treatment of those
patients with good response after the first cycles, especially in seropositive
patients and when it is applied as a first- or second-line biological therap
A Dynamic Kinetic Asymmetric Heck Reaction for the Simultaneous Generation of Central and Axial Chirality
A highly diastereo- and enantioselective, scalable Pd-catalyzed dynamic kinetic asymmetric Heck reaction of heterobiaryl sulfonates with electron-rich olefins is described. The coupling of 2,3-dihydrofuran or N-boc protected 2,3-dihydropyrrole with a variety of quinoline, quinazoline, phthalazine, and picoline derivatives takes place with simultaneous installation of central and axial chirality, reaching excellent diastereo- and enantiomeric excesses when in situ formed [Pd0/DM-BINAP] was used as the catalyst, with loadings reduced down to 2 mol % in large scale reactions. The coupling of acyclic, electron-rich alkenes can also be performed using a [Pd0/Josiphos ligand] to obtain axially chiral heterobiaryl α-substituted alkenes in high yields and enantioselectivities. Products from Boc-protected 2,3-dihydropyrrole can be easily transformed into N,N ligands or appealing axially chiral, bifunctional proline-type organocatalysts. Computational studies suggest that a β-hydride elimination is the stereocontrolling step, in agreement with the observed stereochemical outcome of the reaction.Ministerio de Ciencia e Innovación (Grants CTQ2016-76908-C2-1-P; CTQ2016-76908-C2-2-P; CTQ2016-78083-P; RYC-2013-12585)European Commission (FEDER Programme)Junta de Andalucía (Grant 2012/FQM 10787)Universidad de Sevilla (Grant No. 1800511201)European Union - Marie Skłodowska-Curie (COFUND—Grant Agreement nº 291780
Modelación hidrológica a la cuenca El Hato (Cundinamarca) comparando los diferentes resultados de pérdidas por infiltración utilizando la herramienta computacional HEC-HMS
Trabajo de InvestigaciónEn el presente trabajo se realizó una modelacion hidrologica con tres tipos de modelos de pérdida con el programa HEC-HMS donde se simularon eventos de lluvia y caudal en un intervalo de tiempo para la cuenca el Hato ubicada en el departemento de Cundinamarca, con el fin de obtener como resultado las pérdidas por infiltracion, flujo base y escorrentía que se presentan en la cuencaINTRODUCCIÓN 1. GENERALIDADES DEL TRABAJO DE GRADO 2. MARCO DE REFERENCIA 3. METODOLOGÍA 4. RESULTADOS 5. ANÁLISIS Y DISCUSIÒN DE RESULTADOS 6. CONCLUSIONES REFERENCIAS BIBLIOGRÀFICAS ANEXOSPregradoIngeniero Civi
Red-Emitting Tetracoordinate Organoboron Chelates: Synthesis, Photophysical Properties, and Fluorescence Microscopy
Seven tetracoordinate organoboron fluorophores with heterobiaryl N,O- or N,N-chelate ligands were prepared and photophysically characterized (in toluene). The electronic variation of the heteroaromatic moiety provided a means for the fine-tuning of the UV/vis absorption and emission spectra. In the most interesting cases, the spectra were red-shifted to maximum absorbance at wavelengths longer than 500 nm and emission maxima between 620 and 660 nm. The pronounced intramolecular charge-transfer character of the dyes yielded large Stokes shifts (3500-5100 cm), while maintaining appreciable fluorescence quantum yields of up to 0.2 for emission maxima longer than 600 nm. The lipophilic character of the dyes enabled their application as stains of vesicle substructures in confocal fluorescence microscopy imaging.Ministerio de Economía y Competitividad CTQ2014-54729 - C2 - 1 - P for U.P., CTQ2013 - 48164 - C2 - 1 - P , CTQ2013 - 48164 - C2 - 2 - P for A.R., CTQ2013 - 41339 - P, CTQ2015 - 71896 - REDT for E.P.I., Ramón y Cajal contract RYC - 2013 - 12585 for A.R.FEDER FundJunta de Andalucía 2012/FQM - 2140 for U.P., 2009/FQM - 4537 and 2012/FQM - 1078 for A.R
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