2,746 research outputs found
Learning Design: reflections on a snapshot of the current landscape
The mounting wealth of open and readily available information and the swift evolution of social, mobile and creative technologies warrant a re-conceptualisation of the role of educators: from providers of knowledge to designers of learning. This need is being addressed by a growing trend of research in Learning Design. Responding to this trend, the Art and Science of Learning Design workshop brought together leading voices in the field and provided a forum for discussing its key issues. It focused on three thematic axes: practices and methods, tools and resources, and theoretical frameworks. This paper reviews some definitions of Learning Design and then summarises the main contributions to the workshop. Drawing upon these, we identify three key challenges for Learning Design that suggest directions for future research
Sodium abundances in nearby disk stars
We present sodium abundances for a sample of nearby stars. All results have
been derived from NLTE statistical equilibrium calculations. The influence of
collisional interactions with electrons and hydrogen atoms is evaluated by
comparison of the solar spectrum with very precise fits to the Na I line cores.
The NLTE effects are more pronounced in metal-poor stars since the statistical
equilibrium is dominated by collisions of which at least the electronic
component is substantially reduced. The resulting influence on the
determination of sodium abundances is in a direction opposite to that found
previously for Mg and Al. The NLTE corrections are about -0.1 in thick-disk
stars with [Fe/H] about -0.6. Our [Na/Fe] abundance ratios are about solar for
thick- and thin-disk stars. The increase in [Na/Fe] as a function of [Fe/H] for
metal-rich stars found by Edvardsson et al. (1993) is confirmed. Our results
suggest that sodium yields increase with the metallicity, and quite large
amounts of sodium may be produced by AGB stars. We find that [Na/Fe]ratios,
together with either [Mg/Fe] ratio, kinematic data or stellar evolutionary
ages, make possible the individual discrimination between thin- and thick-disk
membership.Comment: 11pages, 11 figures. A&A accepte
State Space Formulas for Coprime Factorization
In this paper we will give a uniform approach to the derivation of state space formulas of coprime factorizations, of different types, for rational matrix functions
Damping of giant resonances in asymmetric nuclear matter
The giant collective modes in asymmetric nuclear matter are investigated
within a dynamic relaxation time approximation. We derive a coupled dispersion
relation and show that two sources of coupling appear: (i) a coupling of
isoscalar and isovector modes due to different mean-fields acting and (ii) an
explicit new coupling in asymmetric matter due to collisional interaction. We
show that the latter one is responsible for a new mode arising besides
isovector and isoscalar modes.Comment: Varenna conference proceeding
Protein Arginine Methylation and Citrullination in Epigenetic Regulation
The post-translational modification of arginine residues represents a key mechanism for the epigenetic control of gene expression. Aberrant levels of histone arginine modifications have been linked to the development of several diseases including cancer. In recent years, great progress has been made in understanding the physiological role of individual arginine modifications and their effects on chromatin function. The present review aims to summarize the structural and functional aspects of histone arginine modifying enzymes and their impact on gene transcription. We will discuss the potential for targeting these proteins with small molecules in a variety of disease states
On four numerical schemes for a unipolar degenerate drift-diffusion model
International audienceWe consider a unipolar degenerate drift-diffusion system where the relation between the concentration of the charged species c and the chemical potential h is . For four different finite volume schemes based on four different formulations of the fluxes of the problem, we discuss stability and existence results. For two of them, we report a convergence proof. Numerical experiments illustrate the behaviour of the different schemes
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