13,038 research outputs found
Notes on drift theory
It is shown that there is a simpler way to derive the average guiding center drift of a distribution of particles than via the so-called single particle analysis. Based on this derivation it is shown that the entire drift formalism can be considerably simplified, and that results for low order anisotropies are more generally valid than is usually appreciated. This drift analysis leads to a natural alternative derivation of the drift velocity along a neutral sheet
JCMmode: An Adaptive Finite Element Solver for the Computation of Leaky Modes
We present our simulation tool JCMmode for calculating propagating modes of
an optical waveguide. As ansatz functions we use higher order, vectorial
elements (Nedelec elements, edge elements). Further we construct transparent
boundary conditions to deal with leaky modes even for problems with
inhomogeneous exterior domains as for integrated hollow core Arrow waveguides.
We have implemented an error estimator which steers the adaptive mesh
refinement. This allows the precise computation of singularities near the
metal's corner of a Plasmon-Polariton waveguide even for irregular shaped metal
films on a standard personal computer.Comment: 11 page
The mineralization of commercial organic fertilizers at 8°C temperature
In organic production only organic fertilizers and soil conditioners can be used to supply
the soil with nitrogen. The mineralization of these products is slow and so there can be
problems with the supply of nitrogen, when the demand of the plants is high. The supply of
nitrogen from organic products depends on the speed of their mineralization which is
primarily influenced by the composition and formulation of their raw material.
In apple production in the Alps-region especially during spring problems with nitrogen
supply are common. In that period, the weather conditions are sometimes bad, the
temperature in the soil is low and mineralization starts slowly - apple trees demand more
nitrogen than the soil can deliver.
To compensate the demand of the apple tree organic growers can not use mineral
fertilizers but only organic fertilizers and soil conditioners whose mineralization rate is often
unknown. There is a strong need in organic fruit production to receive more information
about the behaviour of fertilizers in the soil especially concerning their N-release under
different conditions.
To acquire that information, incubation experiments under controlled conditions
(temperature, type of soil, humidity of the soil) were carried out in the laboratory to
determine the mineralization-rate of different organic fertilizers and soil conditioners which
are available in our region
Kinematic analysis of handwriting movements in patients with Alzheimer's disease, mild cognitive impairment, depression and healthy subjects
A variety of studies have demonstrated that motor disorders, parkinsonism and extrapyramidal motor symptoms (EPMS) are common in patients with Alzheimer's disease (AD). Several studies have reported an association of EPMS with severity, progression and poor prognosis of AD. The majority of these studies used clinical assessments for the rating of EPMS. In this study, kinematic handwriting analysis was used to quantify differences in fine hand motor function in patients with probable AD and mild cognitive impairment (MCl, as an assumed initial stage of AD) compared to depressed patients and healthy controls. Both patients with MCl and patients with probable AD exhibited loss of fine motor performance. Movements of AD patients were significantly less regular than those of healthy controls. Copyright (C) 2003 S. Karger AG, Basel
Optical microscopy via spectral modifications of a nano-antenna
The existing optical microscopes form an image by collecting photons emitted
from an object. Here we report on the experimental realization of microscopy
without the need for direct optical communication with the sample. To achieve
this, we have scanned a single gold nanoparticle acting as a nano-antenna in
the near field of a sample and have studied the modification of its intrinsic
radiative properties by monitoring its plasmon spectrum.Comment: 6 pages, 4 figures (color
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