1,051 research outputs found
Numerical Simulations and Analysis of Thermally Excited Waves in Plasma Crystals
A numerical model for a 2D-monolayer plasma crystal was established using the
Box_tree code. Box_tree is a Barnes_Hut tree code which has proven effective in
modeling systems composed of large numbers of particles. Thermally excited
waves in this plasma crystal were numerically simulated and dispersion
relations for both the longitudinal and transverse wave modes were found. These
were compared with the dispersion relations extrapolated from experiment as
well as a theory based on harmonic approximation. The results were found to
agree with theoretical dispersion relations under different wave propagation
directions with different particle charges and over a range of 0.9<k<5.Comment: 7 pages, Presented at COSPAR '0
Dispersion Relations for Thermally Excited Waves in Plasma Crystals
Thermally excited waves in a Plasma crystal were numerically simulated using
a Box_Tree code. The code is a Barnes_Hut tree code proven effective in
modeling systems composed of large numbers of particles. Interaction between
individual particles was assumed to conform to a Yukawa potential. Particle
charge, mass, density, Debye length and output data intervals are all
adjustable parameters in the code. Employing a Fourier transform on the output
data, dispersion relations for both longitudinal and transverse wave modes were
determined. These were compared with the dispersion relations obtained from
experiment as well as a theory based on a harmonic approximation to the
potential. They were found to agree over a range of 0.9<k<5, where k is the
shielding parameter, defined by the ratio between interparticle distance a and
dust Debye length lD. This is an improvement over experimental data as current
experiments can only verify the theory up to k = 1.5.Comment: 8 pages, Presented at COSPAR '0
Quality assessment of CIPP lining in sewers:Crucial knowledge acquired by IKT and research gaps identified in Germany
Deterioration of buried water and sewer pipes is a significant concern among utilities around the world. Cured-In-Place-Pipe (CIPP) is one of the techniques commonly adopted to rehabilitate pipes. The main purpose of this paper is to provide a brief, but comprehensive, summary of information needed by researchers, engineers and municipalities to recognize the barriers and difficulties that may arise during CIPP sewer rehabilitation work. Thus, this paper outlines the issues and challenges associated with CIPP rehabilitation of main and lateral sewers by analyzing a series of projects conducted by IKT-Institute for Underground Infrastructure in Germany over the last two decades. Finally, ideas for further research are then proposed to reduce the obstacles and risks linked with this technique
Perioperative complications in infant cleft repair
BACKGROUND: Cleft surgery in infants includes special risks due to the kind of the malformation. These risks can be attributed in part to the age and the weight of the patient. Whereas a lot of studies investigated the long-term facial outcome of cleft surgery depending on the age at operation, less is known about the complications arising during a cleft surgery in early infancy. METHODS: We investigated the incidence and severity of perioperative complications in 174 infants undergoing primary cleft surgery. The severity and the complications were recorded during the intraoperative and the early postoperative period according to the classification by Cohen. RESULTS: Our study revealed that minor complications occurred in 50 patients. Severe complications were observed during 13 operations. There was no fatal complication in the perioperative period. The risk of complications was found to be directly correlated to the body weight at the time of the surgery. Most of the problems appeared intraoperatively, but they were also followed by complications immediately after the extubation. CONCLUSION: In conclusion, cleft surgery in infancy is accompanied by frequent and sometimes severe perioperative complications that may be attributed to this special surgical field
Entwicklung einer Informationssystemarchitektur für elektronische Geschäftsmodelle am Beispiel des webbasierten Marketing-Werkzeuges Marcom
Digital Imaging and Analysis of Dusty Plasmas
Dust particles immersed within a plasma environment, such as those found in
planetary rings or cometary environments, will acquire an electric charge. If
the ratio of interparticle potential energy to average kinetic energy is high
enough the particles will form either a 'liquid' structure with short-range
ordering or a crystalline structure with long-range ordering. Since their
discovery in laboratory environments in 1994, such crystals have been the
subject of a variety of experimental, theoretical, and numerical
investigations. Laboratory experiments analyzing the behavior of dust grains in
a plasma rely on optical diagnostics to provide data about the system in a
non-perturbative manner. In the past, capturing, imaging, and analyzing
crystalline structure in dusty plasmas has been a non-trivial problem.
Utilizing digital imaging and analysis systems, data capture, image formatting,
and analysis can be done quickly. Following data capture, image analysis is
conducted using modified Particle Image Velocimetry (PIV) and Particle Tracking
Velocimetry (PTV) algorithms. The data extracted is then used to construct
Voronoi diagrams, calculate particle density, inter-particle spacing, pair
correlation functions, and thermal energy. From this data other dust plasma
parameters can be inferred such as inter-particle forces and grain charges.Comment: 6 pages, Presented at COSPAR '0
ST-2191, an Anellated Bismorpholino Derivative of Oxy-Fingolimod, Shows Selective S1P1 Agonist and Functional Antagonist Potency In Vitro and In Vivo.
Sphingosine 1-phosphate (S1P) is an extensively studied signaling molecule that contributes to cell proliferation, survival, migration and other functions through binding to specific S1P receptors. The cycle of S1P1 internalization upon S1P binding and recycling to the cell surface when local S1P concentrations are low drives T cell trafficking. S1P1 modulators, such as fingolimod, disrupt this recycling by inducing persistent S1P1 internalization and receptor degradation, which results in blocked egress of T cells from the secondary lymphoid tissues. The approval of these compounds for the treatment of multiple sclerosis has placed the development of S1PR modulators in the focus of pharmacological research, mostly for autoimmune indications. Here, we report on a novel anellated bismorpholino derivative of oxy-fingolimod, named ST-2191, which exerts selective S1P1 agonist and functional antagonist potency. ST-2191 is also effective in reducing the lymphocyte number in mice, and this effect is not dependent on phosphorylation by sphingosine kinase 2 for activity. These data show that ST-2191 is a novel S1P1 modulator, but further experiments are needed to analyze the therapeutic impact of ST-2191 in animal models of autoimmune diseases
Dynamics of a Dust Crystal with Two Different Size Dust Species
A self-consistent three-dimensional model for a complex (dusty) plasma is
used to study the effects of multiple-sized dust grains in a dust crystal. In
addition to the interparticle forces, which interact through a Yukawa
potential, the model includes the effects of gravity, the variation of the
sheath potential above the powered electrode, and a radial confining potential.
Simulations studied various ratios of a mix of 6.5- and 8.9-micron monodisperse
particles and compared their correlation functions, electric potential energy
of the crystal formations, and the dispersion relations for in-plane and
out-of-plane dust lattice wave (DLW) modes for two different sheath
thicknesses. In the 7 mm sheath, the particles formed two layers in the
vertical direction by size, and acted as a two-layer crystal with weak
correlation between the layers. In the 3 mm sheath, the particles formed an
essentially monolayer crystal; however the crystal dynamics showed some
characteristics of a bilayer crystal
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