ikiMap, la plataforma social de la cartografía

ikiMap es un servicio web para crear, compartir y publicar mapas en Internet, basada en software libre (como Openlayers o PostGIS). ikiMap pretende ser no sólo una red social, sino un plataforma de publicación de mapas en la Red a diversos niveles (usuarios, organizaciones, desarrolladores de aplicaciones, etc), siendo a este respecto el feedback y la comunicación con éstos algo imprescindible para la evolución de la plataforma

O dia a dia de uma criança com perturbação do espectro autista em contexto escolar e familiar – estudo de caso

Nas crianças com perturbações do Espectro do Autismo, as capacidades para desenvolverem interacções sociais recíprocas são limitadas, pela ausência de iniciações sociais com os seus companheiros e falta de sensibilidade às iniciativas dos outros. Evitam, frequentemente, o contacto social, isolam-se, exibem respostas negativas ou mesmo comportamentos disruptivos. Todas estas características dificultam aos seus pares o convívio e o jogo, mesmo quando estes mostram interesse em brincar com as crianças com Perturbações do Espectro do Autismo. Não admira então que ao longo das leituras realizadas durante o desenvolvimento deste trabalho, vários foram os autores que referiram a importância da promoção das competências sociais nestas crianças. Face ao exposto, com este estudo procura-se saber como se desenvolve a acção educativa de uma criança com Autismo nos contextos escolar e familiar. Propõe-se, assim, investigar o modo como é atendida no seu dia-a-dia, analisando os tipos de comportamento que revela, as estratégias educativas que são, para si, activadas, como reage em situação lúdica, bem como o grau de evolução constatada ao nível das aprendizagens. No seio familiar visa-se descrever o processo relacional, sob o ponto de vista educativo e, principalmente, analisar de que foram a criança em estudo é ajudada a ser autónoma. Como tal – e com base na análise das entrevistas realizadas no âmbito do estudo - é legítimo afirmar que os resultados da investigação evidenciam um contexto escolar e familiar seguro, envolvente e convergente entre si, no apoio à criança-alvo. Além disso, de acordo com os inquiridos e com os investigadores estudados na revisão da literatura é possível afirmar que os programas de intervenção precoce, o desenvolvimento das actividades lúdicas e um acompanhamento personalizado por um professor especializado (sem nunca esquecer a integração na turma) foram factores fundamentais para um melhor desenvolvimento global da criança em estudo.

Lipoperoxidação dos óleos alimentares

Este trabalho tem por objectivo fazer uma revisão de alguns conceitos sobre a lipoperoxidação dos óleos e gorduras alimentares no uso quotidiano, bem como as implicações envolvidas nos processos de aquecimento durante a fritura e reutilização.

Lost in the supermarket – The Traditional Museums Challenges

“I’m all lost in the supermarket. I can no longer shop happily. I came in here for the special offer. A guaranteed personality”. The song by The Clash, released in 1979, “Lost in the Supermarket” describes the protagonist struggle to deal with an increasingly commercialized society and the depersonalization of the world around him. The song speaks about alienation and the feelings of disillusionment and lack of identity that come through modern society. There are different ways which one can decrease those feelings and promote knowledge, self-awareness and understanding. The museum, when used with all its potential, is one of the ways. But how to do that? That is the question museum professionals ask themselves. This paper analyses how the traditional museum can use the new museology concepts, and the challenges of this approach, to become a vehicle for community development and empowerment, diminishing the feelings sang by The Clash.

Improvement in the Reduction Behavior of Novel ZrO(2)-CeO(2) Solid Solutions with a Tubular Nanostructure by Incorporation of Pd

In this work, 1 wt % Pd/ZrO(2)-CeO(2) mixed oxide nanotubes with 90 mol % CeO(2) were synthesized following a very simple, high-yield procedure and their properties were characterized by synchrotron radiation X-ray diffraction, X-ray absorption near-edge spectroscopy (XANES), and scanning and high-resolution transmission electron microscopy (SEM and HRTEM). In situ XANES experiments were carried out under reducing conditions to investigate the reduction behavior of these novel nanotube materials. The Pd/CeO(2)-based nanotubes exhibited the cubic phase (Fm3m space group). The nanotube walls were composed of nanoparticles with an average crystallite size of about 7 nm, and the nanotubes exhibited a large specific surface area (85 m(2).g(-1)). SEM and HRTEM studies showed that individual nanotubes were composed of a curved sheet of these nanoparticles. Elemental analysis showed that the Ce:Zr:Pd ratios appeared to be approximately constant across space, suggesting compositional homogeneity in the samples. XANES results indicated that the extent of reduction of these materials is low and that the Ce(4+) state is in the majority over the reduced Ce(3+) state. The results suggest that Pd cations-most likely Pd(2+)-form a Pd-Ce-Zr oxide solid solution and that the Pd(2+) is stabilized against reduction in this phase. However, incorporation of the Pd (1 wt %) into the crystal lattice of the nanotubes also appeared to destabilize Ce(4+) against reduction to Ce(3+) and caused a significant increase in its reducibility.

Retention at room temperature of the tetragonal t ``-form in Sc(2)O(3)-doped ZrO(2) nanopowders

Synchrotron X-ray powder diffraction was applied to the study of the effect of crystallite size on the crystal structure of ZrO(2)-10 mol% Sc(2)O(3) nanopowders synthesized by a nitrate-lysine gel-combustion route Nanopowders with different average crystallite sizes were obtained by calcination at several temperatures, ranging from 650 to 1200 degrees C The metastable t""-form of the tetragonal phase, exhibiting a cubic unit cell and tetragonal P4(2)/nmc spatial symmetry, was retained at room temperature in fine nanocrystalline powders, completely avoiding the presence of the stable rhombohedral beta phase. Differently, this phase was identified in samples calcined at high temperatures and its content increased with increasing crystallite size The critical maximum crystallite size for the retention of the mestastable t""-form resulted of about 35 nm (C) 2009 Elsevier B.V All rights reserved

Metastable Phase Diagram of Nanocrystalline ZrO(2)-Sc(2)O(3) Solid Solutions

We have investigated the crystal structures and phase transitions of nanocrystalline ZrO(2)-1 to -13 mol % Sc(2)O(3) by synchrotron X-ray powder diffraction and Raman spectroscopy. ZrO(2)-Sc(2)O(3) nanopowders were synthesized by using a stoichiometric nitrate-lysine get-combustion route. Calcination processes at 650 and at 850 degrees C yielded nanocrystalline materials with average crystallite sizes of (10 +/- 1) and (25 +/- 2) nm, respectively. Only metastable tetragonal forms and the cubic phase were identified, whereas the stable monoclinic and rhombohedral phases were not detected in the compositional range analyzed in this work. Differently from the results of investigations reported in the literature for ZrO(2)-Sc(2)O(3) materials with large crystallite sizes, this study demonstrates that, if the crystallite sizes are small enough (in the nanometric range), the metastable t ``-form of the tetragonal phase is retained. We have also determined the t`-t `` and t ``-cubic compositional boundaries at room temperature and analyzed these transitions at high temperature. Finally, using these results, we built up a metastable phase diagram for nanocrystalline compositionally homogeneous ZrO(2)-Sc(2)O(3) solid solutions that strongly differs from that previously determined from compositionally homogeneous ZrO(2)-Sc(2)O(3), Solid solutions with much larger crystallite sizes.

Tetragonal-cubic phase boundary in nanocrystalline ZrO(2)-Y(2)O(3) solid solutions synthesized by gel-combustion

By means of synchrotron X-ray powder diffraction (SXPD) and Raman spectroscopy, we have detected, in a series of nanocrystalline and compositionally homogeneous ZrO(2)-Y(2)O(3) solid solutions, the presence at room temperature of three different phases depending on Y(2)O(3) content, namely two tetragonal forms and the cubic phase. The studied materials, with average crystallite sizes within the range 7-10 nm, were synthesized by a nitrate-citrate gel-combustion process. The crystal structure of these phases was also investigated by SXPD. The results presented here indicate that the studied nanocrystalline ZrO(2)-Y(2)O(3) solid solutions exhibit the same phases reported in the literature for compositionally homogeneous materials containing larger (micro)crystals. The compositional boundaries between both tetragonal forms and between tetragonal and cubic phases were also determined. (C) 2011 Elsevier B.V. All rights reserved.

Exciton behavior in GaAs/AlGaAs coupled double quantum wells with interface disorder

In this work, we present a detailed study on the optical properties of two GaAs/Al(0.35)Ga(0.65)As coupled double quantum wells (CDQWs) with inter-well barriers of different thicknesses, by using photoluminescence (PL) spectroscopy. The two CDQWs were grown in a single sample, assuring very similar experimental conditions for measurements of both. The PL spectrum of each CDQW exhibits two recombination channels which can be accurately identified as the excitonic e(1)-hh(1) transitions originated from CDQWs of different effective dimensions. The PL spectra characteristics and the behavior of the emissions as a function of temperature and excitation power are interpreted in the scenario of the bimodal interface roughness model, taking into account the exciton migration between the two regions considered in this model and the difference in the potential fluctuation levels between those two regions. The details of the PL spectra behavior as a function of excitation power are explained in terms of the competition between the band gap renormalization (BGR) and the potential fluctuation effects. The results obtained for the two CDQWs, which have different degrees of potential fluctuation, are also compared and discussed. (C) 2009 Elsevier B.V. All rights reserved.

Reentrant quantum Hall effect in bilayer system at high filling factors

We report on the measurements of the quantum Hall effect states in double quantum well structures at the filling factors v = 4N + 1 and 4N + 3, where N is the Landau index number, in the presence of the in-plane magnetic field. The quantum Hall states at these filling factors vanish and reappear several times. Repeated reentrance of the transport gap occurs due to the periodic vanishing of the tunneling amplitude in the presence of the in-plane field. When the gap vanishes, the transport becomes anisotropic. The anisotropy persist at half-odd filling factors, when bilayer quantum Hall states are recovered with increase of the tilt angle. (C) 2007 Elsevier B.V. All rights reserved.

QUANTUM HALL FERROMAGNET IN A DOUBLE WELL WITH VANISHING g-FACTOR.

We have studied the quantum Hall effect in Al(x)Ga(1-x)As-double well structure with vanishing g-factor. We determined the density-magnetic field n(s) - B diagrams for the longitudinal resistance R(xx). In spite of the fact that the n(s) - B diagram for conventional GaAs double wells shows a striking similarity with the theory, we observed the strong difference between these diagrams for double wells with vanishing g-factor. We argue that the electron-electron interaction is responsible for unusual behavior of the Landau levels in such a system.