Perspective: network-guided pattern formation of neural dynamics

The understanding of neural activity patterns is fundamentally linked to an understanding of how the brain's network architecture shapes dynamical processes. Established approaches rely mostly on deviations of a given network from certain classes of random graphs. Hypotheses about the supposed role of prominent topological features (for instance, the roles of modularity, network motifs, or hierarchical network organization) are derived from these deviations. An alternative strategy could be to study deviations of network architectures from regular graphs (rings, lattices) and consider the implications of such deviations for self-organized dynamic patterns on the network. Following this strategy, we draw on the theory of spatiotemporal pattern formation and propose a novel perspective for analyzing dynamics on networks, by evaluating how the self-organized dynamics are confined by network architecture to a small set of permissible collective states. In particular, we discuss the role of prominent topological features of brain connectivity, such as hubs, modules and hierarchy, in shaping activity patterns. We illustrate the notion of network-guided pattern formation with numerical simulations and outline how it can facilitate the understanding of neural dynamics

Mathematical knowledge for teaching and mathematics didactic knowledge : A comparative study

This paper compares and contrasts two approaches that are widely used in the English- and German-speaking discourse on mathematics teacher knowledge: ‘mathematical knowledge for teaching’ and ‘mathematics didactic knowledge’. It is proposed that these constructs are based on distinct theoretical and conceptual positions and origins. Mathematical knowledge for teaching is viewed as a utilitarian-pragmatic approach rooted in English-speaking traditions as it focuses on its use in teaching and represents a practice-based conceptualization of knowledge domains required for mathematics teaching. Mathematics didactic knowledge, on the other hand, is considered normative-descriptive as it is formulated based on didactic principles and broader theoretical perspectives, providing a theory-driven conceptualization of knowledge domains rooted in traditions of German-speaking didactics of mathematics. The paper further highlights similarities and differences in these two constructs through an examination of two central knowledge domains: specialized content knowledge (part of mathematical knowledge for teaching) and subject matter didactic knowledge (part of mathematics didactic knowledge)

Proteomuntersuchung von Körperflüssigkeiten mittels online gekoppelter Kapillarelektrophorese : Massenspektrometrie als Routineverfahren der Diagnostik

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Wild genius - domestic fool? Spatial learning abilities of wild and domestic guinea pigs

<p>Abstract</p> <p>Background</p> <p>Domestic animals and their wild relatives differ in a wide variety of aspects. The process of domestication of the domestic guinea pig (<it>Cavia aperea </it>f. <it>porcellus</it>), starting at least 4500 years ago, led to changes in the anatomy, physiology, and behaviour compared with their wild relative, the wild cavy, <it>Cavia aperea</it>. Although domestic guinea pigs are widely used as a laboratory animal, learning and memory capabilities are often disregarded as being very scarce. Even less is known about learning and memory of wild cavies. In this regard, one striking domestic trait is a reduction in relative brain size, which in the domesticated form of the guinea pig amounts to 13%. However, the common belief, that such a reduction of brain size in the course of domestication of different species is accomplished by less learning capabilities is not at all very well established in the literature. Indeed, domestic animals might also even outperform their wild conspecifics taking advantage of their adaptation to a man-made environment.</p> <p>In our study we compared the spatial learning abilities of wild and domestic guinea pigs. We expected that the two forms are different regarding their learning performance possibly related to the process of domestication. Therefore wild cavies as well as domestic guinea pigs of both sexes, aged 35 to 45 days, were tested in the Morris water maze to investigate their ability of spatial learning.</p> <p>Results</p> <p>Both, wild cavies and domestic guinea pigs were able to learn the task, proving the water maze to be a suitable test also for wild cavies. Regarding the speed of learning, male as well as female domestic guinea pigs outperformed their wild conspecifics significantly. Interestingly, only domestic guinea pigs showed a significant spatial association of the platform position, while other effective search strategies were used by wild cavies.</p> <p>Conclusion</p> <p>The results demonstrate that domestic guinea pigs do not at all perform worse than their wild relatives in tests of spatial learning abilities. Yet, the contrary seems to be true. Hence, artificial selection and breeding did not lead to a cognitive decline but rather to an adaptation to man-made environment that allows solving the task more efficiently.</p

Measuring teacher noticing : A scoping review of standardized instruments

This scoping review provides an overview of standardized instruments used to measure teacher noticing. A systematic literature search identified 37 publications in English-language peer-reviewed journals describing 22 different test instruments. Regarding the underlying conceptualization of noticing, instruments commonly distinguish mental processes (e.g., attending and interpreting) using heterogeneous nomenclatures and focus on various aspects of teaching. Regarding the test design, the instruments are predominantly video-based and vary considerably with respect to measurement approach and test requirements. High test quality was demonstrated for established test instruments. However, on a general level, desiderata became apparent regarding construct and criterion-related validity

Mixing and decay constants of pseudoscalar mesons: Octet-singlet vs. quark flavor basis

Although eta-eta' mixing is qualitatively well understood as a consequence of the U(1)_A anomaly in QCD together with a broken SU(3) flavor symmetry, until recently the values of decay and mixing parameters of the eta and eta' were only approximately known, e.g. values for the octet-singlet mixing angle between -20 degrees and -10 degrees could be found in the literature. New experimental data, especially for the reactions gamma gamma* -> eta, eta' and B -> eta' K, together with new theoretical results from higher order corrections in chiral perturbation theory stimulated a phenomenological re-analysis of this subject, which led to a coherent qualitative and quantitative picture of eta-eta' mixing and even of eta-eta'-eta_c mixing.Comment: 4 pages Latex, uses espcrc2.sty, contribution to "QCD 98", Montpellier 2-8 July 199

Optomechanical self-structuring in cold atomic gases

The rapidly developing field of optomechanics aims at the combined control of optical and mechanical (solid-state or atomic) modes. In particular, laser cooled atoms have been used to exploit optomechanical coupling for self-organization in a variety of schemes where the accessible length scales are constrained by a combination of pump modes and those associated to a second imposed axis, typically a cavity axis. Here, we consider a system with many spatial degrees of freedom around a single distinguished axis, in which two symmetries - rotations and translations in the plane orthogonal to the pump axis - are spontaneously broken. We observe the simultaneous spatial structuring of the density of a cold atomic cloud and an optical pump beam. The resulting patterns have hexagonal symmetry. The experiment demonstrates the manipulation of matter by opto-mechanical self-assembly with adjustable length scales and can be potentially extended to quantum degenerate gases.Comment: 20 pages, 6 figure