904 resultados para Linearized higher-derivative gravity


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Peer-reviewed

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In this paper we identify the requirements for creating formal descriptions of learning scenarios designed under the European HigherEducation Area paradigm, using competences and learning activities as the basic pieces of the learning process, instead of contents and learning resources, pursuing personalization. Classical arrangements of content based courses are no longer enough to describe all the richness of this new learning process, where user profiles, competences and complex hierarchical itineraries need to be properly combined. We study the intersection with the current IMS Learning Design specification and theadditional metadata required for describing such learning scenarios. This new approach involves the use of case based learning and collaborativelearning in order to acquire and develop competences, following adaptive learning paths in two structured levels.

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A straightforward synthesis of the Met antagonist JLK1360 involving an alkylationcyclocondensation process using aminothiazole 1 and nitrophenacyl bromide 2, reduction of the nitro group, and coupling of the resulting tetracyclic aniline 5 with an appropriate N-acyl alanine derivative, is reported.

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A straightforward synthesis of the Met antagonist JLK1360 involving an alkylationcyclocondensation process using aminothiazole 1 and nitrophenacyl bromide 2, reduction of the nitro group, and coupling of the resulting tetracyclic aniline 5 with an appropriate N-acyl alanine derivative, is reported.

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In this paper, glasses in the systems In-Ba-Mg and In-Ba-Zn-Sr-Mg were water leachead at 80ºC showing surface degradation after 72 hours of leaching. The extent of such degradation is determined by the solubility and the concentration of the elemental fluorides that constitute the glasses. The formation of a layer of crystallized phases on the surface of the samples was observed. Small weight losses were registered and the absence of water on the glass matrix after the attack suggested that the use of MgF2 in the systems studied can lead to better results against moisture corrosion when compared to other fluoride glasses such as the fluorozirconates.

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In environmental studies it is necessary to know the adsorption behavior of metals by soils, since the unfavorable effects of heavy metals and even the micronutrients at high concentrations in the environment are related to these adsorbents' ability to immobilize them. A sample of a humic yellow red oxisol from Araponga region in the State of Minas Gerais, Brazil, was used to verify the adsorption behavior of Cu2+ ions in this substrate. The mathematical model described by Langmuir's adsorption equation in its linearized form was applied and the values of the maximum capacity b and those of the constant related to the bonding energy a were obtained. Aliquots of copper nitrate solutions containing several concentrations of this metal were added to soil samples, the pH being predetermined for developing the adsorption experiments. The chemical and physical characterization of soil sample were performed by determining the organic carbon, nitrogen and phosphorus concentrations, cation exchange capacity (CEC), pH, concentration of metals (Al, Fe, K, Mg, Ca, Zn, Cu, Ni, Cr, Co, Pb, and Cd), granulometric analysis and X-ray diffraction. Langmuir isotherms presented two distinct adsorption regions at both pH 4 and pH 5, showing that the adsorptive phenomenon occurs in two distinct stages. The adsorption sites for the lower part presented greater bonding energy and low adsorption capacity compared with the adsorption sites of the part of the curve corresponding to higher Cu concentrations in the equilibrating solution.

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A descriptive, exploratory study is presented based on a questionnaire regarding the following aspects of reflective learning: a) self-knowledge, b) relating experience to knowledge, c) self-reflection, and d) self-regulation of the learning processes. The questionnaire was completed by students studying four different degree courses (social education, environmental sciences, nursing, and psychology). Specifically, the objectives of a self-reported reflective learning questionnaire are: i) to determine students’ appraisal of reflective learning methodology with regard to their reflective learning processes, ii) to obtain evidence of the main difficulties encountered by students in integrating reflective learning methodologies into their reflective learning processes, and iii) to collect students’ perceptions regarding the main contributions of the reflective learning processes they have experienced

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This article reflects on how some values, interests, and particularities of 2.0 culture enter on higher and postgraduate education institutions. Through theidentification of the features of 2.0, this document visualizes some of the resistances, obstacles, possibilities, and opportunities detected in these institutions, many of them focusing on the core of the higher education and postgraduate institutions (i.e. strategic vision, methodology, role of teachers and students, relation between formal and informal learning, contents and assessment). Responsibility in the training and updating of current and future professionals places these institutions under the discussion and decision-making process related to the role that 2.0 tools should play. We wonder if it implies a crossroad which affects the whole set of attitudes and values on the role of training institutions in the context of the construction of socialized knowledge.

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We analyze the timing of photons observed by the MAGIC telescope during a flare of the active galactic nucleus Mkn 501 for a possible correlation with energy, as suggested by some models of quantum gravity (QG), which predict a vacuum refractive index similar or equal to 1 + (E/M-QGn)(n), n = 1, 2. Parametrizing the delay between gamma-rays of different energies as Delta t = +/-tau E-1 or Delta t = +/-tau E-q(2), we find tau(1) = (0.030 +/- 0.012) s/GeV at the 2.5-sigma level, and tau(q) = (3.71 +/- 2.57) x 10(-6) s/GeV2, respectively. We use these results to establish lower limits M-QG1 > 0.21 X 10(18) GeV and M-QG2 > 0.26 x 10(11) GeV at the 95% C.L. Monte Carlo studies confirm the MAGIC sensitivity to propagation effects at these levels. Thermal plasma effects in the source are negligible, but we cannot exclude the importance of some other source effect.

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Microbial lipase from Candida rugosa was immobilized by covalent binding on wood cellulignin (Eucaliptus grandis) chemically modified with carbonyldiimidazole. The immobilized system was fully evaluated in aqueous (olive oil hydrolysis) and organic (ester synthesis) media. A comparative study between free and immobilized lipase was carried out in terms of pH, temperature and thermal stability. A higher pH value (8.0) was found optimal for the immobilized lipase. The optimal reaction temperature shifted from 37 °C for the free lipase to 45 °C for the immobilized lipase. The pattern of heat stability indicated that the immobilization process tends to stabilize the enzyme. Kinetics tests at 37 °C following the hydrolysis of olive oil obeyed the Michaelis-Menten rate equation. Values for Km = 924.9 mM and Vmax = 198.3 U/mg were lower than for free lipase, suggesting that the affinity towards the substrate changed and the activity of the immobilized lipase decreased during the course of immobilization. The immobilized derivative was also tested in the ester synthesis from several alcohols and carboxylic acids.

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The present article comes from a doctoral thesis that turns on digital learner portfolio, which is an innovating methodology from the perspective of European Higher Education Area. First, the educative concept of eportfolio is described in the sense of its procedure and its structure, by means of the technological support of a platform of virtual campus. Second, it is shown the pedagogical model of an eportfolio that adapts subjects with an instrumental character to one organization based on tasks and reflections. This design of virtual learning environment is based on a teaching- learning methodology sustained in the activity of the student, which tries to give support to the management of his or her own process of learning and assessment. Finally, the article illustrates the experience of implementation of the first digital learner portfolios in the University of Barcelona and the Autonomous University of Barcelona, with the objective of reflecting about the pedagogical consequences that this assessment model with technological support has in a traditional higher education institution.

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A rapid HPLC analytical method was developed and validated for the determination of the N-phenylpiperazine derivative LASSBio-579in plasma rat. Analyses were performed using a C18 column and elution with 20 mM sodium dihydrogen phosphate monohydrate - methanol. The analyte was monitored using a photodiode array detector (257 nm). Calibration curves in spiked plasma were linear over the concentration range of 0.3-8 mg/mL with determination coefficient > 0.99. The lower limit of quantification was 0.3 mg/mL. The applicability of the HPLC method for pharmacokinetic studies was tested using plasma samples obtained after administration of LASSBio-579 to Wistar rats, showing the specificity of the method.

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En este estudio presentamos una experiencia llevada a cabo con estudiantes de la asignatura “Psicología de la Educación” de diferentes centros universitarios. Tomando como marco de referencia las teorías constructivistas del aprendizaje, el objetivo de nuestro trabajo se centra en comprobar la incidencia de la utilización de diferentes estrategias de enseñanza por parte del profesor y de determinadas estrategias de aprendizaje en el proceso de registrar la información por parte de los estudiantes, en la significatividad del aprendizaje.Los resultados obtenidos muestran que en los grupos donde los profesores han utilizado estrategias de enseñanza diferentes a la clase magistral, se ha producido un cambio positivo en las respuestas de los estudiantes o se ha mantenido el mismo nivel, mientras que el grupo donde se ha utilizado una metodología magistral, el nivel de respuesta es inferior. Así mismo, hemos podido observar como los grupos de estudiantes que utilizan las estrategias de aprendizaje seleccionadas para tomar apuntes mejoran su nivel de respuestas, lo cual no se produce en el grupo control

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The purpose of this study was to synthesize a water-soluble derivative of rutin (compound 2) by introducing carboxylate groups on rutin's sugar moiety. The rutin derivative showed an almost 100-fold solubility increase in water. The antiradical capacity of compound 2 was evaluated using the luminol/AAPH system, and the derivative's activity was 1.5 times greater than that of Trolox®. Despite the derivative's high solubility in water (log P = -1.13), lipid peroxidation of brain homogenate membranes was very efficiently inhibited (inhibition values were only 19% lower than the inhibition values of rutin).