Dielectrophoretic manipulation of ribosomal RNA

The manipulation of ribosomal RNA (rRNA) extracted from E. coli cells by dielectrophoresis (DEP) has been demonstrated over the range of 3 kHz-50 MHz using interdigitated microelectrodes. Quantitative measurement using total internal reflection fluorescence microscopy of the time dependent collection indicated a positive DEP response characterized by a plateau between 3 kHz and 1 MHz followed by a decrease in response at higher frequencies. Negative DEP was observed above 9 MHz. The positive DEP response below 1 MHz is described by the Clausius-Mossotti model and corresponds to an induced dipole moment of 3300 D with a polarizability of 7.8×10(-32) F m(2). The negative DEP response above 9 MHz indicates that the rRNA molecules exhibit a net moment of -250 D, to give an effective permittivity value of 78.5 ε(0), close to that of the aqueous suspending medium, and a relatively small surface conductance value of ～0.1 nS. This suggests that our rRNA samples have a fairly open structure accessible to the surrounding water molecules, with counterions strongly bound to the charged phosphate groups in the rRNA backbone. These results are the first demonstration of DEP for fast capture and release of rRNA units, opening new opportunities for rRNA-based biosensing devices.     

Transcultural Communicative Competence and the Growth of European Citizenship

Les discussions concernant l'introduction de la dimension européenne dans l'éducation se concentrent trop souvent uniquement sur le role joué par les sciences sociales. Le role de l'enseignement des langues étrangères est peu reconnue et si elles sont mentionées dans ce contexte c'est souvent en dernier lieu. Ceci peut être causé par le contenu utilisé et la méthodologie appliquée dans la classe, mais cette négligeance n'est certainement pas justifiée. Cet article traite du rôle que joue l'enseignement des langues étrangères dans la formation des jeunes comme citoyens européens. Evidemment l'article contient des suggestions à la fois pour des changements dans le contenu et la méthodologie de l'enseignement des langues étrangères. L'article établit un lien entre la langue et la culture dans laquelle elle fonctionne et il suggère comme éléments centraux dans l'enseignement des langues la prise de conscience de l'alterité et les aptitudes linguistiques, pragmatiques et stratégiques qui sont nécessaires pour jeter un pont entre les écarts culturels qui séparent les peuples européens.

     

Item Clusters and Computerized Adaptive Testing: A Case for Testlets

It is observed that many sorts of difficulties may preclude the uneventful construction of tests by a computerized algorithm, such as those currently in favor in Computerized Adaptive Testing (CAT). In this essay we discuss a number of these problems, as well as some possible avenues of solution. We conclude with the development of the "testlet," a bundle of items that can be arranged either hierarchically or linearly, thus maintaining the efficiency of an adaptive test while keeping the quality control of test construction that is possible currently only with careful expert scrutiny. Performance on the separate testlets is aggregated to yield ability estimates.     

Integrating assessment tasks in a problem‐based learning environment

The purpose of this study was to get more insight in the effects of written assessment tasks integrated in a problem‐based learning environment. Both the influence on students' performances and students' perceptions were investigated. Students' final exam results were used to find out whether students who make the assessment tasks do better than students who do not. Answers from questionnaires and semi‐structured interviews were used to discover the most important concerns in students' and teachers' perceptions of the assessment tasks. The results indicate that making the assessment tasks had positive influence on the students' overall performance. From the questionnaires and interviews it appears that both the students and the teachers see the benefits of the assessment tasks. It is concluded that small steps in the change of the assessment system can result in relatively big changes in students' learning and results.     

Using relief texture for interactive and tangible virtual environments

This paper first introduces a way to improve interactivity with high polygon count virtual objects through the ＂mixed＂ use of image-based representation within one object. That is, both 3D polygonal and image-based representations are maintained for an object, and switched for rendering depending on the functional requirement of the object. Furthermore, in order to reduce the popping effect and provide smooth and gradual transition during the object representation switch, the object is subdivided with the subdivided parts possibly represented differently, i.e., using 3D models or images. As for the image-based representation, the relief texture （RT） method is used. In particular, through the use of the mixed representation, a new way called TangibleScreen is proposed to provide object tangibility by associating the image-based representation with a physical prop （projecting the RTs） in a selective and flexible way. Overall, the proposed method provides a way to maintain an interactive frame rate with selective perceptual details in a large-scale virtual environment, while allowing the user to interact with virtual objects in a tangible way.     

Mother‐Child Interactions and Early Intervention Programmes for Handicapped Infants and Young Children

Increased emphasis in the provision of early intervention programmes with families of biologically impaired or at‐risk infants, in recent years, has produced a wide variety of such services based upon various conceptual and empirical analyses of early development. The impact of these early interventions has been investigated quite extensively since the mid‐sixties, particularly regarding positive effects upon intellectual development. A synthesis of recent research regarding mother‐child interaction patterns and the influence of these social interactions upon cognitive, linguistic, and social development has resulted in a shifting emphasis in early interventions from the parent‐as‐teacher model to a parent‐infant interaction model. In concert with this shifting emphasis, interactional models of intervention are considered and described which provide the basis for identifying specific intervention strategies related to parent‐child interaction dynamics. These strategies provide the basis for programmes which would be sensitive to the idiosyncracies of individual families. That is, the unique characteristics of each family/infant may be more effectively accommodated through a transactional analysis of individual dyadic interaction patterns, and through the identification of strategies specifically suited to the unique needs of the parent‐child dyad.