1,204 research outputs found
Оценка влияния соляного раствора на деформацию эластомеров винтовых забойных двигателей при механическом воздействии
Optimum Experimental Design for the Identification of Gaussian Disorder Mobility Parameters in Charge Transport Models of Organic Semiconductors
This thesis treats optimum experimental design for the parameter estimation problem
of mobility parameters in charge transport models of organic semiconductors. The
models consist of the van Roosbroeck system, a quasi-electrochemical potential
defining equation, and the Extended Gaussian Disorder Model and the Extended
Correlated Disorder Model both describing the mobility. The arising problems are
very ill-conditioned. The essential points of this work are:
• The robust numerical solution of the model equations w.r.t. varying parameters,
control parameters, boundary values and initial guesses for iterative methods.
• The computation of exact derivatives up to order two, which are necessary for
the optimum experimental design problem. This includes derivatives of the
model functions and implicitly given derivatives of the solution.
The Scharfetter-Gummel scheme is applied to the spatial discretization in one dimension,
whereas in two dimensions bilinear finite elements are used. The numerical
simulation of the discretized equations is done by a hybrid simulation method consisting
of Gummel’s method with a special, problem-adapted stabilization term, a
contraction based damping strategy, and a full step Newton method in the end for
quadratic convergence near the solution. These strategies are independent of the
spatial discretization and are applied to the simulation of a polymer nano-chain
attached to the cathode. The simulation of the one dimensional problems are used
for the optimum experimental design. The derivatives are computed with automatic
differentiation exactly up to machine precision. Therefor we use software tools for
the computation of the derivatives of the model functions and solve tangential and
adjoint equations of the problem for the parameters and control parameters. With
optimum experimental design we plan experiments for newest organic materials, like
NRS-PPV and a-NPD. The confidence region of the parameters are reduced by a
factor of 100 for NRS-PPV
Quantitative modeling of superconducting planar resonators with improved field homogeneity for electron spin resonance
We present three designs for planar superconducting microwave resonators for
electron spin resonance (ESR) experiments. We implement finite element
simulations to calculate the resonance frequency and quality factors as well as
the three-dimensional microwave magnetic field distribution of the resonators.
One particular resonator design offers an increased homogeneity of the
microwave magnetic field while the other two show a better confinement of the
mode volume. We extend our model simulations to calculate the collective
coupling rate between a spin ensemble and a microwave resonator in the presence
of an inhomogeneous magnetic resonator field. Continuous-wave ESR experiments
of phosphorus donors in Si demonstrate the feasibility of our
resonators for magnetic resonance experiments. We extract the collective
coupling rate and find a good agreement with our simulation results,
corroborating our model approach. Finally, we discuss specific application
cases for the different resonator designs
Matrix metalloproteinase expression levels suggest distinct enzyme roles during lumbar disc herniation and degeneration
The disruption of the extracellular disc matrix is a major hallmark of disc degeneration. This has previously been shown to be associated with an up-regulation of major matrix metalloproteinase (MMP) expression and activity. However, until now hardly any data are available for MMP/TIMP regulation and thereby no concept exists as to which MMP/TIMP plays a major role in disc degeneration. The objective of this study was, therefore, to identify and quantify the putative up-regulation of MMPs/TIMPs on the mRNA and protein level and their activity in disc material in relation to clinical data and histological evidence for disc degeneration. A quantitative molecular analysis of the mRNA expression levels for the MMPs (MMPs-1, -2, -3, -7, -8, -9, -13) and the MMP inhibitors (TIMPs-1 and -2) was performed on 37 disc specimens obtained from symptomatic disc herniation or degeneration. In addition, disc specimens from patients without disc degeneration/herniation (=controls) were analyzed. Expression of MMPs-1, -2, -3, -7, -8, -9, -13 and TIMPs-1, -2 was analyzed using quantitative RT-PCR, normalized to the expression level of a house keeping gene (GAPDH). Gene expression patterns were correlated with MMP activity (in situ zymography), protein expression patterns (immunohistochemistry), degeneration score (routine histology) and clinical data. MMP-3 mRNA levels were consistently and substantially up-regulated in samples with histological evidence for disc degeneration. A similar but less pronounced up-regulation was observed for MMP-8. This up-regulation was paralleled by the expression of TIMP-1 and to a lesser extent TIMP-2. In general, these findings could be confirmed with regard to protein expression and enzyme activity. This study provides data on the gene and protein level, which highlights the key role of MMP-3 in the degenerative cascade leading to symptomatic disc degeneration and herniation. Control of the proteolytic activity of MMP-3 may, therefore, come into the focus when aiming to develop new treatment options for early disc degeneratio
Einstreumanagement in der Ökologischen Milchviehhaltung
The use of bedding materials of natural source is a requirement of the EU regulation of organic husbandry considering the needs of animals for dry comfortable lying areas. However, organic bedding materials provide an environment for mastitis pathogens, too and therefore increase the risk of intramammary infections if not well managed
Fütterung auf den Praxisbetrieben im Verlauf der Interventionsstudie“Gesundheit und Leistung in der ökologischen Milchviehhaltung – Ausgangssituation Einfluss auf die Tiergesundheit
Die Fütterung hat einen bedeutenden Einfluss auf die Stoffwechselgesundheit und damit auf die Eutergesundheit beim Milchvieh. Aus der vorliegenden Datengrundlage des Projekts "Gesundheit und Leistungsfähigkeit von Milchkühen im Ökologischen Landbau interdisziplinär betrachtet" wird untersucht, welche Fütterungsparameter einschließlich des Fütterungsmanagements einen Einfluss auf das Stoffwechselgeschehen haben. Auch ist es möglich, eine Entwicklung der Betriebe aufgrund der Intervention darzustellen
Haltungshygiene und Eutergesundheit im ökologisch geführten Milchviehbetrieb
Im Rahmen einer interdisziplinären Studie wurden in der der Zeit von Januar 2008 bis April 2010 Daten auf 106 Betreiben in Deutschland erhoben. In diesem Teilprojekt wurde der Zusammenhang zwischen Hygeine und Eutergesundheit oim Rahmen einer ersten Asuwertung untersucht. Die Analyse macht deutlich, dass es einen Zusammenhang zwischen Halltungs- une Tierhygiene gibt. zudem gibt es einen Zusammenhang zwischen der Sauberkeit der Laufgänge und der subklinsichen Eutergesundheit sowie der Sauberkeit der Etuer und der Eutergesundheit der Färsen
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