A software framework for the development of Web-based medical education using learning object classes.

A software framework for the development of Web-based medical education is proposed. The objective is to optimize the development process by introducing Learning Objects (LO) and Learning Object Classes (LO Classes) so that the content preparation can be separated from the educational issues, ergonomic design, and technical realization. Based on the concept of case-based, problem-oriented education, different learning scenarios were analysed and then modelled as different LOs. These LOs can be further abstracted in several reusable LO Classes that represent certain patterns of content structure, pedagogical concept, and user interface. With the help of LO input templates, the educational material can be prepared by the authors in the authoring process easily and appropriately. An LO content management system was developed to store and maintain different LOs and to generate the Web-presentation of LOs adaptively and dynamically in the tutoring process. This software framework has been applied to the exemplary development of an interactive course in orthopaedics. The LOs and LO Classes also help to maintain consistency of the course representation to users. As a result, more efficiency in the development phase and good usability and quality of the end products can be achieved.

Concept and development of an orthotropic FE model of the proximal femur.

PURPOSE: In contrast to many isotropic finite-element (FE) models of the femur in literature, it was the object of our study to develop an orthotropic FE "model femur" to realistically simulate three-dimensional bone remodelling. METHODS: The three-dimensional geometry of the proximal femur was reconstructed by CT scans of a pair of cadaveric femurs at equal distances of 2mm. These three-dimensional CT models were implemented into an FE simulation tool. Well-known "density-determined" bony material properties (Young's modulus; Poisson's ratio; ultimate strength in pressure, tension and torsion; shear modulus) were assigned to each FE of the same "CT-density-characterized" volumetric group. In order to fix the principal directions of stiffness in FE areas with the same "density characterization", the cadaveric femurs were cut in 2mm slices in frontal (left femur) and sagittal plane (right femur). Each femoral slice was scanned into a computer-based image processing system. On these images, the principal directions of stiffness of cancellous and cortical bone were determined manually using the orientation of the trabecular structures and the Haversian system. Finally, these geometric data were matched with the "CT-density characterized" three-dimensional femur model. In addition, the time and density-dependent adaptive behaviour of bone remodelling was taken into account by implementation of Carter's criterion. RESULTS: In the constructed "model femur", each FE is characterized by the principal directions of the stiffness and the "CT-density-determined" material properties of cortical and cancellous bone. Thus, on the basis of anatomic data a three-dimensional FE simulation reference model of the proximal femur was realized considering orthotropic conditions of bone behaviour. CONCLUSIONS: With the orthotropic "model femur", the fundamental basis has been formed to realize realistic simulations of the dynamical processes of bone remodelling under different loading conditions or operative procedures (osteotomies, total hip replacements, etc).

cosmovisión aymara

Contiene: Cronistas del siglo XVI-XVII como fuentes de investigación aymara. Tendencias y desiderata (Norbert Schiffers) - Historia (Roberto Choque Canqui) - Los aymaras: características demográficas de un grupo étnico indígena antiguo en los Andes Centrales (Gerrit K÷ster) - El idioma aymara (Felix Laime Pairumani) - "Economía" comunitaria aymara (Simón Yampara Huarachi) - La sociedad aymara. Sistemas y estructuras sociales de Los Andes (Somón Yampara Huarachi) - Apuntes en torno al planeamiento político aymara (José Antonio Rocha) - Educación (Roberto Choque Canqui) - Religión aymara (Hans van den Berg) - Ist'apxam!-Escuchen! tradición musical y oral aymaras (Raimund Schramm).