The constructivist view in science education - what it has to offer and what should not be expected

There is certainly something fashionable about constructivism in science education nowadays. It is further true that constructivism is by no means a consistent movement, there are many variants of this view in use. Furthermore, it appears that constructivism, for some science educators, in any case, has become the new ideology of science education that provides a cure for every problem of teaching and learning science. But without any doubt constructivism has become also a most valuable guideline for science education -- for science teaching and learning as well as for research in these fields. This paper attempts to review the myths, the misunderstandings, the polemics and the serious critiques concerning constructivism. It will be argued in favor of a consistent and "moderate" constructivist view in science education that in fact may provide substantial progress in our field and which major features will be among the valuable views of science education even after the term constructivism will have gone out of fashion

Novel insights into hair structure and the effects of chemical stressors on hair and skin using label-free advanced light microscopy

There is a need for a better method to image hair as the current methods involve embedding the hair in resin, which may produce artefacts, or using dyes which are limited in their depth of penetration into the hair. The research performed in this thesis endeavours to characterise the cellular structure of human hair with label-free imaging using autofluorescence and fluorescence lifetime imaging. Wavelengths were shown to selectively excite the hair cuticle, cortex and medulla, and subcellular compartments. Development of an optical transverse imaging method enabled discoveries including different fluorescence lifetimes across the cuticle cell layers and suggests the cuticle layers possess differing chemical environments. A new method was developed to distinguish between eumelanin and pheomelanin using 405nm and 633nm wavelengths. The newly developed methods were additionally used in the characterisation of an unidentified hair and skin disorder, which found poorly differentiated cuticle cells and showed differences in the fluorescence lifetimes of the hair compared to control hairs. The hair care industry needs more efficacious chemical depilatories and information into their action. This was elucidated using the developed methods and a new dynamic imaging method. Potassium thioglycolate was shown to cause drastic expansion of the hair which was amplified by the addition of guanidine carbonate, creating fissures through the cuticle and into the cortex. Other experimental depilatory formulations were tested and were found to have varying effects upon the structure of the hair. New chemical depilatories require development because existing depilatories can cause irritation in the skin. Potassium thioglycolate and guanidine carbonate were tested on HaCaT cells, isolated cornified envelopes, and HEKn cells in a 3D epidermal model. An investigation into the differentiation, proliferation and acute stress response of the cells showed that the treatments had no significant effect on these markers. However, the chemicals negatively affected HaCaT cell viability and damaged the cornified envelopes. Despite this, the viability and structural integrity of the living cells of the epidermal model were maintained through the protection provided by the stratum corneum

Improving science and mathematics instruction - the SINUS-project as an example for reform as teacher professional development

This article presents an example of teacher professional development based on a perspective of situated learning and implemented on a large scale. We consider teacher professional development from three perspectives. First, teacher professional development is a key factor in improving classroom instruction. Second, teacher professional development is a vehicle for conveying knowledge from research into classrooms. Third, teacher professional development is an object of research itself. A German project to improve science and mathematics teaching (SINUS) – comprising 180 schools in a pilot-phase and more than 1,700 schools in a second phase of scaling-up – serves as an example of this framework for teacher professional development. Using these three views we describe the foundations of the programme and provide a brief account of the programme’s background and its conception. We show how the central elements of the programme (11 modules) are based on an in-depth analysis of science and mathematics education, as well as how those modules structure the professional development of the teachers. Finally, we provide an overview of the evaluation of the programme. A large-scale comparison between SINUS schools and a representative sample of German schools tested in PISA 2003 showed positive effects of the programme with regard to students' interest and motivation as well as competencies in science and mathematics. In the light of these findings, we argue that teachers’ learning related to daily pedagogical challenges in the classroom should be central to professional development initiatives

Regulation and differential functions of ApoER2 and VLDL receptor in Reelin signaling

Der Reelin Signalweg gewährleistet in der Hirnentwicklung von Vertebraten die korrekte Schichtung des Cerebellums, des cerebralen Cortex und des Hippocampus. Das Matrix-Protein Reelin steuert dabei wandernde Neuroblasten, indem es an zwei ihrer Membranrezeptoren, ApoER2 und VLDL Rezeptor, bindet. Beide Rezeptoren übermitteln dieses Signal in die Zelle, wo es zu Phosphorilierung des Adapterproteins Dab1 führt. Bis zu einem gewissen Grad können ApoER2 und VLDL Rezeptor den Verlust des jeweils anderen kompensieren. Daher führt nur der Verlust beider Rezeptoren zum Reeler Phänotyp, der auch bei Mäusen mit fehlerhaftem Reelin Protein auftritt. Dennoch haben beide Rezeptoren zusätzliche individuelle Funktionen, wie die weniger ausgeprägten, aber spezifischen Phänotypen von ApoER2- oder VLDL Rezeptor-defizienten Mäusen vermuten lassen. Diese Arbeit konzentriert sich auf ebendiese funktionellen Unterschiede der Reelin Rezeptoren. ApoER2 und VLDL Rezeptor wurden in Hinblick auf Lokalisierung in der Plasmamembran, Endozytosemechanismus, zelluläre Reelin-Aufnahme, intrazelluläre Sortierung, Prozessierung und Abbau verglichen. Weiters wurde die Regulation der Rezeptormenge durch einen erst kürzlich beschriebenen Liver-X-Rezeptor-abhängigen Abbauweg untersucht. Mit Hilfe von chimären Rezeptoren aus den Extrazellulär-, Transmembran- und Intrazellulärdomänen von ApoER2 und VLDL Rezeptor wurden des Weiteren strukturelle Eigenschaften sowie Membranlokalisation innerhalb oder ausserhalb von Lipid Rafts als mögliche Ursachen für die rezeptorspezifischen Besonderheiten gegenübergestellt. Die hier demonstrierten, unterschiedlichen Wege von ApoER2 und VLDL Rezeptor nach der Bindung von Reelin könnten eine Feinabstimmung des Reelin Signalwegs darstellen. VLDL Rezeptor, welcher ausserhalb der Lipid Raft-Fraktion der Plasmamembran zu finden ist, internalisiert Reelin über den Clathrin-coated pit/Clathrin-coated vesicle/Endosom-Weg und führt es so dem Abbau zu, ohne selbst abgebaut zu werden. Bindung von Reelin an den Lipid Raft-assoziierten ApoER2 führt zur Produktion von spezifischen Rezeptorfragmenten und zum lysosomalen Abbau des Rezeptors. Anhand dieser Ergebnisse wurde ein neues Modell des Reelin Signalwegs entwickelt, welches spezifische Rückkopplungs-Effekte durch ApoER2 und VLDL Rezeptor miteinbezieht.The Reelin signaling cascade is an important pathway in the development of the brain of vertebrates, guaranteeing proper lamination of cerebellum, cerebral cortex, and hippocampus. The matrix protein Reelin controls positioning of migrating neuroblasts by binding to two receptors on their cell surface, ApoER2 and VLDL receptor. Both receptors transmit the signal into the cell which results in phosphorylation of the intracellular adapter protein Dab1. To a certain extent, both receptors can compensate for each other, and only the loss of both results in a phenotype similar to that of reeler mice which lack functional Reelin. Nevertheless, both receptors also have specific distinct functions, as corroborated by analyses of the subtle phenotypes displayed in mice lacking either ApoER2 or VLDL receptor. This study focusses on those functional differences between the two Reelin receptors. ApoER2 and VLDLR were studied and compared in terms of sorting within the plasma membrane, mechanism of endocytosis, Reelin internalization rate, intracellular traffic, degradation, and proteolytic processing. Moreover, regulation of ApoER2 and VLDL receptor levels by a liver X receptor mediated degradation pathway recently described for related receptors was investigated. Using a panel of chimeric receptors, composed of extracellular, transmembrane and intracellular domains of ApoER2 and VLDL receptor in diverse combinations, it was furthermore analysed if differential behaviour is structurally determined or based on specific sorting of the receptors to lipid raft or non-raft domains of the plasma membrane. The different fates of ApoER2 and VLDL receptor after Reelin binding which are demonstrated here could affect further signaling and might therefore constitute a mechanism for finetuning of the Reelin pathway. VLDL receptor, residing in the non-raft domain, internalizes and destines Reelin for degradation via the clathrin-coated pit/clathrin-coated vesicle/endosome pathway without being degraded to a significant extent. Binding of Reelin to ApoER2, resident of rafts, leads to the production of particular receptor fragments with specific functions of their own and to degradation of ApoER2 via lysosomes. These features contribute to a novel model that emphasizes negative feedback loops specifically mediated by ApoER2 and VLDL receptor, respectively

Impact of controlled vacuum induced surface freezing on the freeze drying of human plasma

During the freezing step of a typical freeze drying process, the temperature at which nucleation is induced is generally stochastically distributed, resulting in undesired within-batch heterogeneity. Controlled nucleation techniques have been developed to address this problem; these make it possible to trigger the formation of ice crystals at the same time and temperature in all the batch. Here, the controlled nucleation technique known as vacuum induced surface freezing is compared to spontaneous freezing for the freeze drying of human plasma, a highly concentrated system commonly stored in a dried state. The potency of Factor VIII (FVIII), a sensitive, labile protein present in plasma, and the reconstitution time of the dried cakes are evaluated immediately after freeze drying, and after 1, 3, 6 or 9 months storage at different degradation temperatures. We show that the application of controlled nucleation significantly reduces the reconstitution time and in addition helps to improve FVIII stability

Lehr-Lernprozesse im Physikunterricht - eine Videostudie

[Der Beitrag berichtet aus einem Projekt des DFG-Schwerpunktprogramms Bildungsqualität]. Hintergrund für dieses Projekt sind ... die Befunde aus internationalen Vergleichsstudien (TIMSS, PISA). Die Studie untersucht den deutschen Physikunterricht und die Lernprozesse, die in diesem Unterricht ermöglicht werden. Ziel ist es, eine erste Bestandsaufnahme der "didaktischen Orchestrierung" von Physikuntericht vorzunehmen und insbesondere die Möglichkeiten für verständnisvolles Lernen zu untersuchen ... . Mit theoriegeleiteten Analysen von Unterrichtsbeobachtungen und von ergänzenden Daten aus Befragungen und Tests soll geklärt werden, wie sich Bedingungen bzw. Muster des Physikunterrichts auf Lernprozesse und Bildungsergebnisse auswirken. Der Beitrag konzentriert sich auf die Zielorientierung und die Lernbegleitung. (DIPF/Orig.

Teaching energy conservation as a unifying principle in physics

In this work we present the design and assessment of a teaching sequence aimed at introducing the principle of energy conservation at post-compulsory secondary school level (16-18 year olds). The proposal is based on the result of research into teaching-learning difficulties and on the analysis of the physics framework. Evidence is shown that this teaching sequence, together with the methodology used in the classroom, may result in students having a better grasp of the principle of energy conservation. Keywords Physics education · Energy conceptions · Teaching activitie

Mobile monitoring application to support sustainable behavioural change towards healthy lifestyle

We describe the development of body area networks (BANs) incorporating sensors and other devices to provide intelligent mobile services in healthcare and well-being. The first BAN applications were designed to simply transmit biosignals and display them remotely. Further developments include analysis and interpretation of biosignals in the light of context data. By including feedback loops, BAN telemonitoring was also augmented with teletreatment services. Recent developments include incorporation of clinical decision support by applying techniques from artificial intelligence. These developments represent a movement towards smart healthcare, making health BAN applications more intelligent by incorporating feedback, context awareness, personalization, and decision support.\ud The element of decision support was first introduced into the BAN health and well-being applications in the Food Valley Eating Advisor (FOVEA) project. Obesity and overweight represent a growing threat to health and well-being in modern society. Physical inactivity has been shown to contribute significantly to morbidity and mortality rates, and this is now a global trend bringing huge costs in terms of human suffering and reduction in life expectancy as well as uncontrolled growth in demand on healthcare services. Part of the solution is to foster healthier lifestyle. A major challenge however is that exercise and dietary programs may work for the individual in the short term, but adherence in the medium and long term is difficult to sustain, making weight management a continuing struggle for individuals and a growing problem for society, governments, and health services. Using ICT to support sustainable behavioral change in relation to healthy exercise and diet is the goal of the FOVEA monitoring and feedback application. We strive to design and develop intelligent BAN-based applications that support motivation and adherence in the long term. We present this healthy lifestyle application and report results of an evaluation conducted by surveying professionals in related disciplines