Das Lehrerprofessionswissen von Mathematiklehrkräften der Sekundarstufe I im Bereich der Beschreibenden Statistik („BeSt Teacher“)

Innerhalb der letzten Jahre konnte eine Veränderung in Bezug auf die Relevanz von Statistik in Schulen beobachtet werden. In Deutschland kam es mit der Einführung der Bildungsstandards zu einer größeren Wertschätzung des Bereichs „Daten und Zufall“, der als eine von fünf zentralen Leitideen herausgestellt wurde. Statistik ist somit ein wichtiger, aber trotz alledem häufig vernachlässigter Bereich mathematischer Bildung in der Schule. Auch das Wissen von Lehrkräften bezüglich dieser Thematik ist nicht zufriedenstellend: „[...] the teachers generally have [...] little knowledge about statistics“ (Batanero et al. 2011, S.12). Die Ursachen dafür können unter anderem in der vormals vernachlässigten Rolle im Unterrichtskontext oder auch in der defizitären Berücksichtigung des Themengebiets in der Ausbildung der Lehrkräfte vermutet werden. Ziel des hier vorgestellten Forschungsvorhabens „BeSt Teacher“ ist es, das Professionswissen von Mathematiklehrkräften der Sekundarstufe I im Bereich der Beschreibenden Statistik mit Hilfe eines selbst konzipierten Testinstruments zu erfassen. Dabei werden zwei zentrale Fragen verfolgt: (1) In welchem Maße verfügen Lehrkräfte über schulbezogenes Wissen im Bereich der Beschreibenden Statistik? (2) Auf welche Art und Weise vermitteln Lehrkräfte ihr Wissen und über welches Wissen von typischen Schülerfehlern und -schwierigkeiten verfügen sie

KCC2 plays a crucial role during the maturation of spinal neurons by regulating the expression of the GlyR alpha subunit and gephyrin

In spinal cord and brain stem, the GlyR is the major receptor type to mediate inhibitory synaptic transmission. Together with the GlyRb subunit, the GlyRa1 subunit forms the adult form of the receptor. Activation of the pentameric GlyR by glycine results in an increased permeability of the GlyR channel for chloride. In juvenile stages, the cell is depolarized whereas adult neurons experience a hyperpolarization. Not least, the activity of KCC2, changing the intracellular chloride level from a high to a low adult state, contributes considerably to the maturation of the neurons. In this thesis, the approximate time point of the switch to occur in vitro could be determined to div 14 via mRNA expression studies of the distinct GlyR subunits. The obtained mRNA data also indicate that the GlyRb subunit exhibits the highest RNA expression whereas GlyRa1 expression is even lower than that of GlyRa2. Taken together, the results suggest that adult neurons as well as juvenile neurons still express heteromeric α2β and/or homomeric α2 receptors. Strychnine application to the SN cultures resulted in a down regulation of KCC2 expression in a dose-dependent manner at div 14. This finding indicates that the activity of the GlyR may regulate the expression of KCC2 to some extent. Subsequent treatments with Ca2+ channel blockers and Ca2+ chelators revealed a role for Ca2+ to destabilize the KCC2 complex. Although suppression of the entire synaptic transmission in the culture by TTX application as well as catching all free Ca2+ ions also reduce KCC2 expression, the latter seems not to be dependent on Ca2+ influx via L-type channels. However, KCC2 expression either depends on Ca2+ being present within the cell or Ca2+ influx through another type of Ca-channel than L-type. To clarify the role of KCC2 in the GlyR subunit switch, its expression successfully was down regulated upon transduction by a silencing shRNA construct. Immunoblot and localization of immunoreactivities reveal a decrease in the expression of the adult GlyRa1 subunit following KCC2 knockdown. The expression of gephyrin is affected as well. In the main, no additionally investigated synaptic proteins are concerned. Therefore, the neurons are supposed to remain in a juvenile state in terms of the GlyR when KCC2 is not expressed properly. The question arising is, whether the pure presence or the activity of KCC2 is responsible for the correct GlyRa1 expression. It also remains unclear whether knockdown of KCC2 affects GlyRa1 expression and hence gephyrin expression, the other way around or whether even both proteins directly are affected by loss of KCC2. I suggest that loss of KCC2 impairs the expression of the scaffolding protein gephyrin via unknown cytoskeletal mechanisms or signalling pathways. The absence of gephyrin in turn directs loss of the adult GlyR consisting of GlyRa1 and GlyRb. This loss might result from either down regulation of GlyRa1 expression or removal of the adult receptor from the membrane and subsequent degradation

Penalty contracts: is it all about paying the cash upfront?

We experimentally investigate the relevance of a cash upfront payment for the effort-enhancing effect of penalty contracts. We find that penalty contracts where participants receive the upfront payment physically before working on a real effort task induce more effort than penalty contracts where participants are only informed about the upfront payment. When comparing penalty contracts with economically-equivalent bonus contracts, we find that penalty contracts lead to higher effort provision than bonus contracts, but only if participants physically receive the upfront cash payment in advance. We suggest that the higher salience of the cash upfront payment might be a core driver of the detected framing effect. Our findings emphasize the importance of experimental design choices when studying framed incentive contracts

Kommunikations- und Notationsverhalten von Erstsemesterstudierenden beim Lernen mit Videotutorials

Im BMBF-geförderten Projekt mamdim soll der Einfluss digitaler Medien auf das Lernen von beschreibender Statistik bei Studierenden unterschiedlicher Fachrichtungen in der Studieneingangsphase an verschiedenen Hochschulen untersucht werden. Mithilfe der Erfassung des Fachwissens, der Motivation und der Selbstwirksamkeitsüberzeugungen der Studierenden vor und nach einer videographierten Interventionsphase mit verschiedenen instruktionalen Formaten (z.B. Lernvideos, kommentierte Präsentationen) zur beschreibenden Statistik werden Gemeinsamkeiten und Unterschiede im Kommunikations- und Notationsverhaltens in den Blick genommen. In diesem Beitrag werden die Analysen der Videoaufnahmen eines Standortes (Lehramtsstudierende der Universität Bielefeld) beim Lernen mit Videotutorials mit beziehungsweise ohne inhaltsbezogene Fragen dargestellt

The GIK-Archive of sediment core radiographs with documentation

The GIK-Archive of radiographs is a collection of X-ray negative and photographic images of sediment cores based on exposures taken since the early 1960s. During four decades of marine geological work at the University of Kiel, Germany, several thousand hours of sampling, careful preparation and X-raying were spent on producing a unique archive of sediment radiographs from several parts of the World Ocean. The archive consists of more than 18 500 exposures on chemical film that were digitized, geo-referenced, supplemented with metadata and archived in the data library PANGAEA®. With this publication, the images have become available open-access for use by the scientific community at https://doi.org/10.1594/PANGAEA.854841