Kieferchirurgische Operationsplanung mit Hilfe von Techniken der virtuellen Realit?t

Zusammenfassung.   Für ein vollst?ndig computergestütztes Planungssystem zum Zwecke der kieferchirurgischen Operationsplanung ist die Bereitstellung von virtuellen Werkzeugen für den Chirurgen eine grundlegende Voraussetzung. Ausgehend von den Volumendaten mit Sch?del- und Kieferknochen des Patienten erm?glicht ein einfaches Interface unter Verwendung einer geeigneten Visualisierung und haptischer Eingabeger?te die interaktive Definition und Manipulation einzelner virtueller Knochensegmente. Wir haben moderne kraftrückgekoppelte Ger?te aus dem Niedrigpreisbereich eingebunden und auf ihre F?higkeit untersucht, das dreidimensionale Verst?ndnis im Planungsproze?durch Anlehnung an die Vorg?nge bei der chirurgischen Prozedur zu erh?hen. Durch diese Eingabeger?te ist es m?glich, die Knochensegmentierung für eine Osteotomie des Unterkiefers intuitiver und schneller durchzuführen. Die definierten Teilvolumina ergeben zusammen mit ihrer r?umlichen Neuanordnung auf Grundlage einer kephalometrischen Analyse einen Operationsplan. Nach erfolgter Planung werden die Planungsergebnisse in den Operationssaal übertragen. Die intraoperativen Techniken beinhalten die Visualisierung der Planungsergebnisse, die Steuerung der Anwendung über Sprache und die Bestimmung der Patientenposition mittels eines elektromagnetischen 3D-Trackingsystems. Eingegangen am 27. April 2000 / Angenommen am 21. Februar 2001     

Filtering Data for Detecting Differential Development

The amount of data available in the context of educational measurement has vastly increased in recent years. Such data are often incomplete, involve tests administered at different time points and during the course of many years, and can therefore be quite challenging to model. In addition, intermediate results like grades or report cards being available to pupils, teachers, parents, and policy makers might influence future performance, which adds to the modeling difficulties. We propose the use of simple data filters to obtain a reduced set of relevant data, which allows for simple checks on the relative development of persons, items, or both.     

Two new readability predictors for the professional writer: pilot trials

A combination of two new, but very different, approaches to the prediction of readability could be particularly valuable in evaluating English texts written for native and non-native speakers. One approach develops the concept of lexical density, whereas the other is a novel measurement of two mechanical variables of text. The paper first outlines the traditional approach to readability. Next, it explains the concept of lexical density, and presents the results of a pilot study into reader preferences for different levels of density in text. It then offers an alternative approach to readability that uses sentence and ‘packet’ lengths. Finally, it indicates how the two approaches have been combined into a computer software program, and suggests the direction of future work. Our conclusions are threefold. Firstly, the lexical density of text is a better indicator of its readability than the scores given by many of the more common readability formulae. Secondly, the effective breaking up of sentences into ‘packets’ is as important to readability as sentence length. Finally, in looking at the mechanical variables of texts, we should not only be concerned with averages, but with distributions and most frequently occurring values.     

Changes in the basic ICT skills of freshmen between 2005 and 2009: Who’s catching up and who’s still behind?

In the last decade, ICT use has expanded enormously in most Western countries. In line with this development, we hypothesised that freshmen at university would not only have mastered more ICT skills, but would also use computers more often than their counterparts of 5 years previously. To compare students’ opinions and behaviour between 2005 and 2009, responses to two online questionnaires (N = 714 in 2005 and N = 1529 in 2009) offered at a large university were compared. The main variables of the Technology Acceptance Model (as well as facilitating factors, study motivation and some contextual variables) were used as predictors to explore the possible changes between 2005 and 2009 in the mastering of 19 ICT skills, and the frequency of the use of computers for six different tasks. The results of the study show that freshmen became more proficient in some ICT skills, while proficiency in other skills did not change or even dropped. Gender is still an important factor to predict ICT skills and the frequency of using computers, but it is shown that for some skills female students have caught up with their male counterparts.     

Highly integrated model assessment technology and tools

Effective and efficient measurement of the development of skill and knowledge, especially in domains of human activity that involve complex and challenging problems, is important with regard to workplace and academic performance. However, there has been little progress in the area of practical measurement and assessment, due in part to the lack of automated tools that are appropriate for assessing the acquisition and development of complex cognitive skills. In the last 2 years, an international team of researchers has developed and validated an integrated set of assessment tools called highly integrated model assessment technology and tools (HIMATT) which addresses this deficiency. HIMATT is web-based and has been shown to scale up for practical use in educational and workplace settings, unlike many of the research tools developed solely to study basic issues in human learning and performance. In this paper, we describe the functions of HIMATT and demonstrate several applications for its use. Additionally, we present two studies on the quality and usability of HIMATT. We conclude with research suggestions for the use of HIMATT and for its further development.     

An altar in honor of the anatomical gift

On All Saints Day 2009 a monument for body donors was unveiled by the Department of Anatomy, at the Radboud University Nijmegen Medical Centre (RUNMC). Although body donation to medical science contributes substantially to the quality of medical education, the ceremony was only the first time that the RUNMC publicly reciprocated the anatomical gift. By means of the monument the department of Anatomy endeavors to express gratitude for the gift of body donors and raise awareness among students to value the gift and treat donor bodies with the proper respect. Furthermore, the large attendance of bereaved at the unveiling ceremony, revealed another equally important meaning of the monument, which is the significance of the monument to the donor kin. The wish of a body donor has large implications for the way bereaved can take leave of the donor; there is limited time to bade the deceased farewell, the body will not be available for a funeral, and the donor kin stay behind empty handed without even a grave or ashes. Therefore the monument can be meaningful by facilitating the bereaved with a place of commemoration. The design of the monument anticipates on these multiple meanings and symbolisms by placing an old marble dissection table in the shape of an altar and fixing a bronze sculpture of a phoenix as symbol of imperishableness. Anat Sci Educ. © 2010 American Association of Anatomists.     

An Historical Phenomenology of Mean and Median

Using Freudenthal’s method of historical phenomenology, the history of statistics was investigated as a source of inspiration for instructional design. Based on systematically selected historical examples, hypotheses were formulated about how students could be supported in learning to reason with particular statistical concepts and graphs. Such a historical study helped to distinguish different aspects and levels of understanding of concepts and helped us as instructional designers to look through the eyes of students. In this paper, we focus on an historical phenomenology of mean and median, and give examples of how hypotheses stemming from the historical phenomenology led to the design of instructional activities used for teaching experiments in grades 7 and 8 (12–14-years old).     

Effects of Instruction on Verbal Interactions During Collaborative Problem Solving

During one school year, data were collected for vocational education students while they worked collaboratively on open-ended mathematics problems. In collaboration with participating teachers, instructional activities were designed with a twofold goal of modelling the process of problem solving and improving collaboration. Instructional activities were based on scaffolding instruction and included modelling problem solving, stimulating reflection, and giving feedback on the process of collaboration. These activities were gradually developed and implemented in collaboration with teachers who participated in the study. The main research question in this study was whether student collaboration while working in small groups creates a learning context where students work on open-ended problems and where instructional activities are aimed at stimulating collaborative problem solving in mathematics.To answer the research question, an experiment was undertaken in two classes in different schools. Two groups of students were videotaped while they tried to solve mathematics problems collaboratively. Observational data were analysed with a schema that was developed as part of this research. Analyses of the data showed that, in both groups, collaboration-oriented patterns increased during the school year. It is argued that the approach of gradual implementation of instructional activities that are designed in cooperation with participating teachers is effective in stimulating collaborative problem solving.     

Neuropsychological intervention in kindergarten children with subtyped risks of reading retardation

Kindergarten children at risk of developing language problems were administered the Florida Kindergarten Screening Battery. A principal components analysis revealed a verbal and a visual-spatial component and subsequent discriminant function analyses a high verbal/low visual-spatial group (LAL: Latent L) and a high visual-spatial/low verbal group (LAP: Latent P). LAL- and LAP-children were considered at risk for developing an L- or P-type of dyslexia, respectively. As is common practice with children suffering from manifest L- or P- dyslexia, the LAL- and LAP-kindergartners received right and left hemisphere stimulation, respectively. The outcomes were compared with those of bilateral hemispheric stimulation and no intervention. Reading tests were administered in primary school Grades 1 and 5/6; teachers’ evaluation of reading took place in Grade 5/6. Overall, the LAL- and LAP- groups showed significant backwardness in word and text reading, both at early and late primary school. Types of intervention made a difference though: not significantly backward in early word, late word, and late text reading were the LAL-children who had received right hemisphere stimulation. Nonintervened LAP-children did not show significant backwardness in early word reading and late text reading, nor did LAP-children who had received left hemisphere or bilateral stimulation. Early text reading was not affected by any treatment. Teacher’s evaluations were in support of these findings.