Über den Einfluss der Fensterung von Sweep-Signalen bei der Messung von Raumimpulsantworten

Diese Arbeit beschäftigt sich mit der Untersuchung der Eigenschaften von gemessenen Raumimpulsantworten. Um die Impulsantwort zu bestimmen, wird das System in geeigneter Weise angeregt und die Systemantwort gemessen. Dabei wird untersucht, inwieweit sich die Fensterung von Sweep-Signalen unter Einfluss von Rauschen auf die Impulsantwort auswirkt. Im Rahmen dieser Arbeit wurde eine Software implementiert, die einen in der Realität vorkommenden Messaufbau simuliert. Durch eine strikte Trennung von Mess- und Simulationsmodul findet die Software auch für reale Messungen Anwendung

Continuous Electrical Stimulation Affects Initial Growth and Proliferation of Adipose-Derived Stem Cells

The aim of the study was to establish electrical stimulation parameters in order to improve cell growth and viability of human adipose-derived stem cells (hADSC) when compared to non-stimulated cells in vitro. hADSC were exposed to continuous electrical stimulation with 1.7 V AC/20 Hz. After 24, 72 h and 7 days, cell number, cellular surface coverage and cell proliferation were assessed. In addition, cell cycle analysis was carried out after 3 and 7 days. After 24 h, no significant alterations were observed for stimulated cells. At day 3, stimulated cells showed a 4.5-fold increase in cell numbers, a 2.7-fold increase in cellular surface coverage and a significantly increased proliferation. Via cell cycle analysis, a significant increase in the G2/M phase was monitored for stimulated cells. Contrastingly, after 7 days, the non-stimulated group exhibited a 11-fold increase in cell numbers and a 4-fold increase in cellular surface coverage as well as a significant increase in cell proliferation. Moreover, the stimulated cells displayed a shift to the G1 and sub-G1 phase, indicating for metabolic arrest and apoptosis initiation. In accordance, continuous electrical stimulation of hADSC led to a significantly increased cell growth and proliferation after 3 days. However, longer stimulation periods such as 7 days caused an opposite result indicating initiation of apoptosis