Materialwissenschaftliche, fertigungstechnologische sowie applikative Entwicklungen und Untersuchungen zu Elektroden in muskulärer Umgebung

Elektroden dienen als bidirektionale leitfähige Schnittstelle zwischen biologischem Gewebe und technischen Systemen. In muskulärer Umgebung sind sie mechanischen Belastungen ausgesetzt. Für derzeitige implantierbare, flexible Mikroelektroden hat dies Limitierungen der Langzeitstabilität zur Folge. Durch die ausschließliche Verwendung von Materialien deren Elastizitätsmoduln im Bereich des von Muskelgewebe liegen, können diese überwunden werden. Daher sollte als einziges Material für alle Elektrodenkomponenten unterschiedlich funktionalisiertes Silikon zum Einsatz kommen. Im Rahmen dieser Dissertation wird die Entwicklung und Charakterisierung von Silikon-Elektroden sowie die Beschreibung der Mechanismen an der Phasengrenze zu biologischem Gewebe umfassend und systematisch dargestellt. Dafür wurden materialwissenschaftliche, fertigungstechnische und physikalische Themengebiete bearbeitet. Diese umfassten Untersuchungen zu den verwendbaren Materialien sowie deren Verarbeitung zu Elektrodenstrukturen. Zudem sind sowohl die Materialien selbst als auch die aufgebauten Elektroden optisch, mechanisch, elektrisch und elektrochemisch sowie biologisch untersucht worden. Die Verwendbarkeit der entwickelten PDMS-Elektroden wurde durch die Ableitung von EMG- und EKG-Signalen sowie die Bestimmung der maximal reversibel übertragbaren Ladung zur Stimulation nachgewiesen. Die Ergebnisse wurden diskutiert und in Bezug zur Literatur gesetzt.Electrodes serve as bi-directional conductive interface between biological tissue and technical systems. They are exposed to mechanical stress in muscular environment. For current implantable, flexible micro electrodes, this results in limitations of their long term stability. By using only materials whose young’s moduli are in the range of that of muscle tissue, these limitations can be overcome. Therefore, the only material for all electrode components should be differently functionalized silicone. Within the scope of this dissertation the development and characterization of silicone electrodes as well as the description of mechanisms at the phase boundary to biological tissue are presented comprehensively and systematically. For this purpose material-scientific, production-orientated and physical Topics were addressed. This included investigations regarding the suitable materials as well as their processability into electrode structures. Furthermore both the materials themselves and the built electrodes were examined optically, mechanically, electrically, electrochemically and biologically. The applicability of the developed PDMS-electrodes was demonstrated by the derivation of EMG and ECG signals as well as the determination of the charge injection capacity for stimulation. The results were discussed and related to the literature.Gefördert durch das Bundesministerium für Bildung und Forschung im Rahmen des Projektes "Implantierbare, elastische, nanofunktionalisierte Polysiloxan-Strukturen für Anwendungen in der Neuroprothetik" (elaN

Effects of Various Soil Fertility Treatments on Corn Yields in Eastern Oklahoma

Soil

Soft gluon resummation for squark and gluino pair-production at hadron colliders

We report on the study of soft gluon effects in the production of squarks and gluinos at hadron colliders. Close to production threshold, the emission of soft gluon results in the appearence of large logarithmic corrections in the theoretical expressions. In order to resum these corrections at next-to-leading-logarithmic accuracy appropriate one-loop anomalous dimensions have to be calculated. We present the calculation of the anomalous dimensions for all production channels of squarks and gluinos and provide numerical predictions for the Tevatron and the LHC.Comment: 6 pages, talk given at RADCOR 2009 - 9th International Symposium on Radiative Corrections (Applications of Quantum Field Theory to Phenomenology) October 25-30 2009, Ascona, Switzerlan

Radiative corrections to W-boson hadroproduction: higher-order electroweak and supersymmetric effects

The high accuracy envisaged for future measurements of W-boson production at hadron colliders has to be matched by precise theoretical predictions. We study the impact of electroweak radiative corrections on W-boson production cross sections and differential distributions at the Tevatron and at the LHC. In particular, we include photon-induced processes, which contribute at O(alpha), and leading radiative corrections beyond O(alpha) in the high-energy Sudakov regime and from multi-photon final-state radiation. We furthermore present the calculation of the complete supersymmetric next-to-leading-order electroweak and QCD corrections to W-boson hadroproduction within the MSSM. The supersymmetric corrections turn out to be negligible in the vicinity of the W resonance in general, reaching the percent level only at high lepton transverse momentum and for specific choices of the supersymmetric parameters.Comment: 30 pages, 10 figures, 2 new sections, including a comparison with previous results on multi-photon radiation; version published in PR

Soft-gluon resummation for squark and gluino hadroproduction

We consider the resummation of soft gluon emission for squark and gluino hadroproduction at next-to-leading-logarithmic (NLL) accuracy in the framework of the minimal supersymmetric standard model. We present analytical results for squark-squark and squark-gluino production and provide numerical predictions for all squark and gluino pair-production processes at the Tevatron and at the LHC. The size of the soft-gluon corrections and the reduction in the scale uncertainty are most significant for processes involving gluino production. At the LHC, where the sensitivity to squark and gluino masses ranges up to 3 TeV, the corrections due to NLL resummation over and above the NLO predictions can be as high as 35% in the case of gluino-pair production, whereas at the Tevatron, the NLL corrections are close to 40% for squark-gluino final states with sparticle masses around 500 GeV.Comment: 31 pages, 7 figure

Counselling in the introductory phase of studies

The University of Applied Sciences RheinMain has a heterogenic field of beginners, which leads to a high dropout rate after the first semester. We ran a project to change the engineering department’s introductory phase based on motor learning’s feedback concept. The beginners could choose to have one exam at the end of the semester or having three shorter exams instead during the semester. Failing one of the shorter exams made it mandatory to get individual counselling. The data from that project shows the effects of that counselling which helps the students to be successful in later exams. Students, who assume early support offers, are proven to perform better