Skinning measures in negative curvature and equidistribution of equidistant submanifolds

Let C be a locally convex subset of a negatively curved Riemannian manifold M. We define the skinning measure on the outer unit normal bundle to C in M by pulling back the Patterson-Sullivan measures at infinity, and give a finiteness result of skinning measures, generalising the work of Oh and Shah, with different methods. We prove that the skinning measures, when finite, of the equidistant hypersurfaces to C equidistribute to the Bowen-Margulis measure on the unit tangent bundle of M, assuming only that the Bowen-Margulis measure is finite and mixing for the geodesic flow. Under additional assumptions on the rate of mixing, we give a control on the rate of equidistribution.Comment: 32 pages. Revised version with important modifications to Section

Onset voltage shift due to non-zero Landau ground state level in coherent magnetotransport

Coherent electron transport in double-barrier heterostructures with parallel electric and magnetic fields is analyzed theoretically and with the aid of a quantum simulator accounting for 3-dimensional transport effects. The onset-voltage shift induced by the magnetic field in resonant tunneling diodes, which was previously attributed to the cyclotron frequency $w_c$ inside the well is found to arise from an upward shift of the non-zero ground (lowest) Landau state energy in the entire quantum region where coherent transport takes place. The spatial dependence of the cyclotron frequency is accounted for and verified to have a negligible impact on resonant tunneling for the device and magnetic field strength considered. A correction term for the onset-voltage shift arising from the magnetic field dependence of the chemical potential is also derived. The Landau ground state with its nonvanishing finite harmonic oscillator energy $\hbar w_c /2$ is verified however to be the principal contributor to the onset voltage shift at low temperatures.Comment: 13 pages, and 3 figures. Accepted for publication in Phys. Rev.

Teacher design teams as a strategy for professional development : the role of the facilitator

The goal of the current study was to explore the role and importance of the facilitator in Teacher Design Teams. The study took place in the context of a pre-service teacher education institution in Belgium, where teacher design teams were set up to facilitate the professional development of teacher educators. The findings from focus group discussions with team members and semi-structured interviews with facilitators confirm that the perceived importance of a facilitator depends on several factors, such as team characteristics and the design phase. Moreover, we found that a facilitator can fulfil three roles in a dynamic way: 1) providing logistic support, 2) scaffolding the design process and 3) monitoring the design process. The discussion centers on how these results can be used to support facilitators for successful Teacher Design Teams

Research-informed strategies to address educational challenges in a digitally networked world

This special issue represents the scholarly work that emerged from the EDUsummIT 2013. EDUsummIT is a growing and active community of researchers, policy makers and practitioners that is committed to promote research-informed strategies to effectively integrate ICT in educational policy and practice. First the background and aim of EDUsummIT is presented, followed by an overview of the contributions to this special issue

Comportement harmonique des densités conformes et frontière de Martin

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Research-practice interactions as reported in recent design studies: Still promising, still hazy

This study portrays recent research–practice connections found in 18 design research reports focusing on the creation of instructional solutions. Solutions in different stages of development varied greatly in duration, ranging from one lesson to a whole year curriculum, spanned all levels of education, many subjects (science, math, language, culture, teacher education, etc.). Close collaboration between researchers and practitioners was prominent in all of the 18 projects studied. Participants in primary and secondary education projects have quite distinct roles regarding the teaching and researching, but they design their instruction solutions often collaboratively. Nearly all projects reported on how designed solutions were anchored in research, either from literature or from in-house project data. All articles indicated that research fed (re-)design, but few specified how. Based on our findings, we call for increased research and reporting on the specific strategies employed by design research participants to facilitate the production of new theoretical understanding through design of instructional solution

Conditions for the successful implementation of teacher educator design teams for ICT integration : a Delphi study

Teacher educators often struggle to model effective integration of technology. Several studies suggest that the involvement of teacher educators in collaborative design is effective in developing the competences necessary for integrating information and communication technology (ICT) in teaching. In a teacher educator design team (TeDT), two or more teacher educators (re-)design curriculum materials together. For the successful implementation of TeDTs, conditions at both team and institutional levels have to be taken into account. However, there is little consensus among stakeholders about which of these conditions are of highest priority. Most studies present priority or critical conditions from the viewpoint of just one group (e.g., school leaders). A Delphi study was set up aiming at synthesising the knowledge and views of various stakeholders about the conditions for the successful implementation of TeDTs for ICT integration. Consensus about the importance of ten conditions was reached in the entire sample after three rounds. These conditions include a long-term vision, trust, ownership, time and supportive institutional policies