Antonio Roberto Pereira Leite de Albuquerque

A Semantic Web-based authoring tool to facilitate the planning of collaborative learning scenarios compliant with learning theories

When the goal of group activities is to support long-term learning, the task of designing well-thought-out collaborative learning (CL) scenarios is an important key to success. To help students adequately acquire and develop their knowledge and skills, a teacher can plan a scenario that increases the probability for learning to occur. Such a scenario defines pedagogically sound structures that prevent off-task behavior and engage students in more meaningful interactions. The main difficulty in designing effective CL scenarios is transforming the teachers intentions into elements that constitute the learning scenario. This problem is frequently observed when novice teachers attempt to improve the quality of learning and instruction by blending collaborative activities with individual activities without careful planning. With the goal of helping teachers in planning collaborative scenarios, we have developed an intelligent authoring tool referred to as CHOCOLATO using Semantic Web technologies (e.g. ontologies) in order to represent knowledge about different pedagogies and practices related to collaboration. Through the use of this knowledge, CHOCOLATO can provide intelligent guidance that helps teachers to create theory-based CL scenarios which has proven to be effective in a variety of situations. We evaluated it by conducting two experiments. We were interested in verifying whether the recommendations given by CHOCOLATO help novice teachers to design pedagogically sound CL activities, and if these activities help students to learn collaboratively in real classroom settings. The first experiment had the participation of 58 pre-service teachers that created CL scenarios with and without our authoring tool and the second experiment was carried out in a Brazilian public school together with 218 students. The results suggest that the guidance provided by CHOCOLATO do help novice teachers plan, understand and share CL scenarios more easily. They also suggest that the continuous utilization of well-designed theory-based CL activities create favorable conditions for students (particularly less knowledgeable ones) to improve their overall performance throughout the school year.

The EPR Spectra of X-Ray Irradiated Gypsum

EPR spectroscopy in X-Ray irradiated natural crystals of gypsum (CaSO 4 2H 2 O) from Ceara, Brazil, showed the presence of four paramagnetic centers. The spectra of these centers were separated using temperature and power variations techniques. The g and A tensor parameters of two of these centers, identified as OH · and O 2 .H · were calculated.

An authoring tool to support the design and use of theory-based collaborative learning activities

Design of pedagogically sound collaborative learning (CL) activities is a complex task, but necessary if the goal is to support learning Through the design of CL scenarios, a designer can define structures that increase the chance for learning to occur It means that the effectiveness of the collaboration depends on the transformation of the designers intentions into elements that will constitute the learning scenario To support the creation of CL scenarios this paper presents an intelligent authoring tool that is equipped with the knowledge about different pedagogies and practices related to collaboration Through the use of this information, the tool can provide intelligent guidance that support designers to create more effective CL scenarios The results of an experiment suggest that our tool helps teachers to more easily introduce CL activities in classroom and creates favorable conditions for students to perform collaboration improving their overall learning performance throughout the year.

Irradiation and heating effects in topaz crystals from minas cerais, Brazil

Abstract The origin of the blue color induced by irradiation in topaz crystals from the region around Governador Valadares, Minas Gerais, was examined through chemical analyses and heat treatments before irradiation. No correlation between impurities and the induced blue color was found. Heat treatments above 300°C before irradiation inhibit the formation of color.

Color Dependence on Thickness in Topaz Crystal from Brazil

It is well known that crystals of topaz from the Eastern Brazilian Pegmatite Province may turn blue by the irradiation with 60Co gamma rays followed by heat treatment. Also, it is known that the sensation of color changes with the thickness of these crystals. The dependence of the color, given by 1931 CIE chromaticity coordinates, with the thickness of the crystal was analyzed. The absorbance used in the calculation of these coordinates was given by the sum of Gaussian lines. The parameters of these lines were determined through the decomposition of the optical absorption spectra in the ultraviolet and visible regions. The decomposition revealed several lines, whose assignment was made considering studies in spodumene and beryl crystals and highly accurate quantum mechanical calculations. The transmittance becomes very narrow with increasing thickness, and the CIE chromaticity coordinates converge to the borderline of the CIE Chromaticity Diagram at the wavelength of maximum transmittance. Furthermore, the purity of color increases with increasing thickness, and the dominant wavelength reaches the wavelength of maximum transmittance.