1000 resultados para 948.0


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In this work we describe the synthesis and characterization of chalcogenide glass (0.3La2S3-0.7Ga2S 3) with low phonons frequencies. Several properties were measured like Sellmeier parameters, linear refractive index dispersion and material dispersion. Samples with the composition above were doped with Dy2S3. The absorption and emission characteristics were measured by electronic spectroscopy and fluorescence spectrum respectively. Raman and infrared spectroscopy shows that these glasses present low phonons frequencies and strucuture composed by GaS4 tetrahedrals. The Lines model was used for calculate the coefficients values of the non linear refractive index.

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The reaction of an aqueous solution of poly(ethylene oxide) (peo - mw 100.000) with a neutral aqueous suspension of single layers of MoS2 was studied. The single layers aqueous suspension was prepared by first intercalating lithium (using n-Butyllithium in n-hexane) and reaction of these ternary compound with water under ultrasound stirring. The suspension was washed several times with water until neutral pH. The suspension was mixed with the PEO aqueous solution in the presence of KCl. Two single phase compounds were obtained with the expansion of 4,8 and 9,0Å, attributed to the solvation of the intercalated potassium cations with mono and double layers, respectively.

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Peer-reviewed

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High levels of Fe and Mn present in some soils and compost organic matter decrease the resolution of 13C NMR spectra of humic substances. Addition of KCl up to a concentration of 0,03 mol L-1 to humic substances extracts followed by centrifugation is an efficient method of eliminating clays and minerals containing high levels of paramagnetic metals such as Fe and Mn thus increasing the resolution of 13C NMR spectra.

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SIMBENFISC v1.0 permet simular els beneficis fiscals que generen els següents impostos: Successions, Donacions, Transmissions Patrimonials, Actes Jurídics i Operacions Societàries. Genera un informe per a cada impost que conté: 1- Els resultats de la recaptació real per a la liquidació de l’impost segons la normativa vigent a Catalunya i la normativa vigent a l’estat. 2- Els resultats dels beneficis fiscals que corresponen a l’execució de les diferents reduccions i/o deduccions contemplades a cada impost. 3- Els resultats de la projecció de recaptació i dels beneficis fiscals que s’obtindrien d’aplicar determinats supòsits de creixement a) de la base imposable, b) de les liquidacions i c) de canvis de normativa. La informació que processa aquest simulador, òbviament, és específica de cada impost, però el seu ventall es situa aproximadament entre els 50.000 i 300.000 registres. Aquesta informació és l’input del microsimulador i la proporciona la Direcció General de Tributs i Jocs, del Departament d’Economia i Coneixement de la Generalitat de Catalunya, a partir de les autoliquidacions que s’efectuen en cada exercici fiscal anual.

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A simple and inexpensive time-of-flight mass spectrometer, dedicated to the study of gas-phase ionization processes induced by high energy electrons (0.5 - 3.0 keV), is described. The spectrometer design is based on the Wiley-McLaren principle, with a total length of about 18 cm. As a demonstration of the performance of the apparatus, mass spectra for Ar, CH4, CO2, and SF6, obtained at 1 keV electron energy, are presented.

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La intenció del present estudi es esbrinar si el propòsit institucional d'integrar les TICs i desenvolupar les competències digitals entre l'alumnat s'assoleix a l'escola primària, si la formació del professorat es suficient per aquests objectius i si l'ús està integrat en el procés d'ensenyament i aprenentatge. També volem saber si a la pràctica les TICs queden relegades només a un nivell individual, deixant en segon pla l'ús col·lectiu dins l'aula amb l'alumnat, i l'ús queda restringit sobre tot a la consulta i no incorpora la producció de material digital.Per tant, el nostre objectiu és conèixer el grau d'utilització de les TICs, en particular les que donen pas i fomenten la cultura participativa (eines 2.0) del professorat de Primària, el tipus d'ús i el coneixement sobre l'alumnat destinatari de l'aprenentatge. Per tal d'obtenir una descripció de la utilització d'aquest col·lectiu de les TICs s'ha creat un qüestionari que intentarà respondre als nostres objectius.

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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 assessed the effects of nutrient enrichment on three stream ecosystems running through distinct biomes (Mediterranean, Pampean and Andean). We increased the concentrations of N and P in the stream water 1.6–4-fold following a before–after control–impact paired series (BACIPS) design in each stream, and evaluated changes in the biomass of bacteria, primary producers, invertebrates and fish in the enriched (E) versus control (C) reaches after nutrient addition through a predictive-BACIPS approach. The treatment produced variable biomass responses (2–77% of explained variance) among biological communities and streams. The greatest biomass response was observed for algae in the Andean stream (77% of the variance), although fish also showed important biomass responses (about 9–48%). The strongest biomass response to enrichment (77% in all biological compartments) was found in the Andean stream. The magnitude and seasonality of biomass responses to enrichment were highly site specific, often depending on the basal nutrient concentration and on windows of ecological opportunity (periods when environmental constraints other than nutrients do not limit biomass growth). The Pampean stream, with high basal nutrient concentrations, showed a weak response to enrichment (except for invertebrates), whereas the greater responses of Andean stream communities were presumably favored by wider windows of ecological opportunity in comparison to those from the Mediterranean stream. Despite variation among sites, enrichment globally stimulated the algal-based food webs (algae and invertebrate grazers) but not the detritus-based food webs (bacteria and invertebrate shredders). This study shows that nutrient enrichment tends to globally enhance the biomass of stream biological assemblages, but that its magnitude and extent within the food web are complex and are strongly determined by environmental factors and ecosystem structure

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We assessed the effects of nutrient enrichment on three stream ecosystems running through distinct biomes (Mediterranean, Pampean and Andean). We increased the concentrations of N and P in the stream water 1.6–4-fold following a before–after control–impact paired series (BACIPS) design in each stream, and evaluated changes in the biomass of bacteria, primary producers, invertebrates and fish in the enriched (E) versus control (C) reaches after nutrient addition through a predictive-BACIPS approach. The treatment produced variable biomass responses (2–77% of explained variance) among biological communities and streams. The greatest biomass response was observed for algae in the Andean stream (77% of the variance), although fish also showed important biomass responses (about 9–48%). The strongest biomass response to enrichment (77% in all biological compartments) was found in the Andean stream. The magnitude and seasonality of biomass responses to enrichment were highly site specific, often depending on the basal nutrient concentration and on windows of ecological opportunity (periods when environmental constraints other than nutrients do not limit biomass growth). The Pampean stream, with high basal nutrient concentrations, showed a weak response to enrichment (except for invertebrates), whereas the greater responses of Andean stream communities were presumably favored by wider windows of ecological opportunity in comparison to those from the Mediterranean stream. Despite variation among sites, enrichment globally stimulated the algal-based food webs (algae and invertebrate grazers) but not the detritus-based food webs (bacteria and invertebrate shredders). This study shows that nutrient enrichment tends to globally enhance the biomass of stream biological assemblages, but that its magnitude and extent within the food web are complex and are strongly determined by environmental factors and ecosystem structure

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Postprint (published version)

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El bullying, lamentablemente, no es un tema nuevo en el ámbito educativo. Sin embargo, con la introducción de las nuevas tecnologías en nuestras vidas, una nueva forma de acoso ha cobrado protagonismo más allá de las aulas: el ciberbullying.

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Con la llegada de la web 2.0, ha sido posible para todos los usuarios participar y colaborar en la construcción del conocimiento, además de servir al dominio público gracias al intercambio libre y legal de los contenidos y a su reutilización. Además los recursos educativos abiertos, son un concepto reciente en lo que respecta a la organización del mundo de intercambio de variedad de materiales y herramientas educacionales, e instituciones como la UNESCO están interesadas en el desarrollo de estos, para ser utilizados en una escala tan amplia y global como sea posible. Sin embargo los REA están teniendo algunas dificultades para alcanzar su eficacia, ya que hay algunas diferencias cruciales en la organización y en la interacción de estas redes abiertas. Este artículo intenta realizar un análisis del intercambio libre y legal de los contenidos y su reutilización utilizadas como apoyo para el aprendizaje en diferentes espacios en línea, aprovechando las posibilidades tecnológicas que permiten conformar nuevas estructuras de socialización-colaboración en línea.

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Aim of the Thesis is to study and understand the theoretical concept of Metanational corporation and understand how the Web 2.0 technologies can be used to support the theory. Empiric part of the study compares the theory to the case company’s current situation Goal of theoretical framework is to show how the Web 2.0 technologies can be used in the three levels of the Metanational corporation. In order to do this, knowledge management and more accurately knowledge transferring is studied to understand what is needed from the Web 2.0 technologies in the different functions and operations of the Metanational corporation. Final synthesis of the theoretical framework is to present a model where the Web 2.0 technologies are placed on the levels of the Metanational corporation. Empirical part of the study is based on interviews made in the case company. Aim of the interviews is to understand the current state of the company related to the theoretical framework. Based on the interviews, the differences between the theoretical concept and the case company are presented and studied. Finally the study presents the found problem areas, and where the adoption of the Web 2.0 tools is seen as beneficiary, based on the interviews and theoretical framework.