48 research outputs found
Small-scale solar magnetic fields
As we resolve ever smaller structures in the solar atmosphere, it has become
clear that magnetism is an important component of those small structures.
Small-scale magnetism holds the key to many poorly understood facets of solar
magnetism on all scales, such as the existence of a local dynamo, chromospheric
heating, and flux emergence, to name a few. Here, we review our knowledge of
small-scale photospheric fields, with particular emphasis on quiet-sun field,
and discuss the implications of several results obtained recently using new
instruments, as well as future prospects in this field of research.Comment: 43 pages, 18 figure
Genetic variation in complement regulators and susceptibility to age-related macular degeneration.
Age-related macular degeneration (AMD) is the commonest cause of blindness in Western populations. Risk is influenced by age, genetic and environmental factors. Complement activation appears to be important in the pathogenesis and associations have been found between AMD and genetic variations in complement regulators such as complement factor H. We therefore investigated other complement regulators for association with AMD
Ab initio calculations of optical properties of silver clusters: cross-over from molecular to nanoscale behavior
Electronic and optical properties of silver clusters were calculated using
two different \textit{ab initio} approaches: 1) based on all-electron
full-potential linearized-augmented plane-wave method and 2) local basis
function pseudopotential approach. Agreement is found between the two methods
for small and intermediate sized clusters for which the former method is
limited due to its all-electron formulation. The latter, due to non-periodic
boundary conditions, is the more natural approach to simulate small clusters.
The effect of cluster size is then explored using the local basis function
approach. We find that as the cluster size increases, the electronic structure
undergoes a transition from molecular behavior to nanoparticle behavior at a
cluster size of 140 atoms (diameter \,nm). Above this cluster size
the step-like electronic structure, evident as several features in the
imaginary part of the polarizability of all clusters smaller than
Ag, gives way to a dominant plasmon peak localized at
wavelengths 350\,nm 600\,nm. It is, thus, at this length-scale
that the conduction electrons' collective oscillations that are responsible for
plasmonic resonances begin to dominate the opto-electronic properties of silver
nanoclusters
Communicatie en betrokkenheid. Een surveyonderzoek naar de invloed van communicatietevredenheid op medewerkerbetrokkenheid
Contains fulltext :
67629-OA.pdf (publisher's version ) (Open Access)19 p