Structural and dynamic properties of linker histone H1 binding to DNA

Found in all eukaryotic cells, linker histones H1 are known to bind to and rearrange nucleosomal linker DNA. In vitro, the fundamental nature of H1∕DNA interactions has attracted wide interest among research communities-from biologists to physicists. Hence, H1∕DNA binding processes and structural and dynamical information about these self-assemblies are of broad importance. Targeting a quantitative understanding of H1 induced DNA compaction mechanisms, our strategy is based on using small-angle x-ray microdiffraction in combination with microfluidics. The usage of microfluidic hydrodynamic focusing devices facilitates a microscale control of these self-assembly processes, which cannot be achieved using conventional bulk setups. In addition, the method enables time-resolved access to structure formation in situ, in particular, to transient intermediate states. The observed time dependent structure evolution shows that the H1∕DNA interaction can be described as a two-step process: an initial unspecific binding of H1 to DNA is followed by a rearrangement of molecules within the formed assemblies. The second step is most likely induced by interactions between the DNA and the H1's charged side chains. This leads to an increase in lattice spacing within the DNA∕protein assembly and induces a decrease in the correlation length of the mesophases, probably due to a local bending of the DNA.     

The stark reality of the ‘White Saviour’ complex and the need for critical consciousness: a document analysis of the early journals of a Freirean educator

While the anglophone academic literature has long engaged in analysis of the role of privilege in the work of educators in the Global North, this article represents an initial foray into such analysis in non-formal educational settings in the Global South. Through a cultural-textual document analysis of 12?months of personal journal entries written by the author while working as a Freirean adult educator in Mozambique, this article documents a lack of recognition of social privilege exhibited by the author in these entries, which is here referred to as the ‘White Saviour’ complex. This article also documents how the pursuit of what Freire calls ‘critical consciousness’ can effectively problematise this privileged mindset.     

Supporting learning with interactive multimedia through active integration of representations

When learners explore dynamic and interactive visualisations they are often not able to interact with them in a systematic and goal-oriented way. Frequently, even supporting learners in processes of discovery learning does not lead to better learning outcomes. This can be due to missing pre-requisite knowledge such as the coherent mental integration of the pictorial and symbolic sources of information. In order to support learners in this process, we encouraged them to interactively and externally relate different static sources of information to each other before exploring dynamic and interactive visualisations. We evaluated the benefit of this instructional support in two experimental studies concerning the domains of statistics and mechanics. It revealed that the active integration of static representations before processing dynamic visualisations resulted in better performance and can provide a basis for a more systematic and goal-oriented experimentation behaviour during simulation-based discovery learning.in final form: 16 November 2004     

The role of student-generated externalizations in strategic multimedia learning and how current (web-)technology fails to support learner engagement

In two studies, we investigated how learning strategies can support learning from multimedia. In the first study, 112 students learned from a web-based learning environment. On the basis of a strategy, one group of students took typewritten notes. The second group of students wrote a summary. Producing typewritten notes did not benefit learning any more than writing a summary. In the second study, 100 students learned the same subject matter from print. On the basis of a strategy, the first group produced written notes, the second group highlighted, wrote notes, and produced sketches. The third group wrote a summary. The students who highlighted, wrote notes, and produced sketches outperformed the other students. The students who produced written notes only did not learn more successfully than those who wrote a summary. The results suggest that externalizations in general and sketches in particular may play an important role in multimedia learning.     

„Wirtschaftsseminare für Lehrer“ in West-Berlin

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