386 research outputs found
A Comparison of Phycocyanins from Three Different Species of Cyanobacteria Employing Resonance-Enhanced Coherent Anti-Stokes Raman Spectroscopy
Resonance-enhanced coherent anti-Stokes Raman spectra are recorded for monomers and trimers of phycocyanin from three different cyanobacteria: Westiellopsis prolifica, Mastigocladus laminosus and Spirulina platensis. It is shown that upon aggregation from monomer to trimer the electronic structures of both the α84 and β84 chromophores are changed. The spectra of the trimers originating from S. platensis and M. laminosus are very similar to each other, but distinctly different from the spectrum of W. prolifica
Soziale Bedingungen von Schulleistungen: Zur Erfassung von Kontextmerkmalen durch Schüler-, Schul- und Elternfragebögen [Elektronische Ressource]
Author's comment: sine ann
Increased Instruction Hours and the Widening Gap in Student Performance
Do increased instruction hours improve the performance of all students? Using PISA scores of students in ninth grade, we analyse the effect of a German education reform that increased weekly instruction hours by two hours (6.5 percent) overalmost five years. In the additional time, students are taught new learning content. On average, the reform improves student performance. However, treatment effects are small and differ across the student performance distribution. While low-performing students do not benefit, high-performing students benefit the most. The findings suggest that increases in instruction hours can widen the gap between low- and high-performing students
Ion energy distribution functions behind the sheaths of magnetized and non magnetized radio frequency discharges
The effect of a magnetic field on the characteristics of capacitively coupled
radio frequency discharges is investigated and found to be substantial. A
one-dimensional particle-in-cell simulation shows that geometrically symmetric
discharges can be asymmetrized by applying a spatially inhomogeneous magnetic
field. This effect is similar to the recently discovered electrical asymmetry
effect. Both effects act independently, they can work in the same direction or
compensate each other. Also the ion energy distribution functions at the
electrodes are strongly affected by the magnetic field, although only
indirectly. The field influences not the dynamics of the sheath itself but
rather its operating conditions, i.e., the ion flux through it and voltage drop
across it. To support this interpretation, the particle-in-cell results are
compared with the outcome of the recently proposed ensemble-in-spacetime
algorithm. Although that scheme resolves only the sheath and neglects
magnetization, it is able to reproduce the ion energy distribution functions
with very good accuracy, regardless of whether the discharge is magnetized or
not
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