Optik und Mechatronik
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Technikethik im Jahr 2021
(2021)
Application of a robotic THz imaging system for sub-surface analysis of ancient human remains
(2019)
We used a robotic-based THz imaging system to investigate the sub-surface structure of an artificially mummified ancient Egyptian human left hand. The results obtained are compared to the results of a conventional CT and a micro-CT scan. Using such a robotic THz system promises new insights into the sub-surface structure of human remains. The depth resolution of the THz images exceeds the resolution of a conventional CT scan and is comparable with a micro-CT scan. The advantage of THz measurements over micro-CT scans is the fact that even comparatively large samples, like complete bodies, can be scanned. These would not fit into a conventional micro-CT scanner.
Wideband-tympanometry (WBT) could give more informative data about the tympanic condition than the conventional tympanometry. In the actual literature, the clinical profit of wideband-tympanometry in pediatric audiological settings is not well evaluated. The aim of this study was to analyze the additional clinical benefit.
Fluorescence Microscopy-Based Quantitation of GLUT4 Translocation: High Throughput or High Content?
(2020)
Pharmaceutical agents or drugs often have a pronounced impact on protein-protein interactions in cells, and in particular, cell membranes. Changes of molecular conformations as well as of intermolecular interactions may affect dipole-dipole interaction between chromophoric groups, which can be proven by measuring the Förster resonance energy transfer (FRET). If these chromophores are located within or in close proximity to the plasma membrane, they are excited preferentially by an evanescent electromagnetic wave upon total internal reflection (TIR) of an incident laser beam. For the TIR-FRET screening of larger cell collectives, we performed three separate steps: (1) setting up of a membrane associated test system for probing the interaction between the epidermal growth factor receptor (EGFR) and the growth factor receptor-bound protein 2; (2) use of the Epac-SH188 sensor for quantitative evaluation under the microscope; and (3) application of a TIR fluorescence reader to probe the interaction of GFP with Nile Red. In the first two steps, we measured FRET from cyan (CFP) to yellow fluorescent protein (YFP) by spectral analysis and fluorescence lifetime imaging (FLIM) upon illumination of whole cells (epi-illumination) as well as selective illumination of their plasma membranes by TIR. In particular, TIR excitation permitted FRET measurements with high sensitivity and low background. The Epac sensor showed a more rapid response to pharmaceutical agents, e.g., Forskolin or the A2B adenosine receptor agonist NECA, in close proximity to the plasma membrane compared to the cytosol. Finally, FRET from a membrane associated GFP to Nile Red was used to test a multi-well TIR fluorescence reader with simultaneous detection of a larger number of samples.
The present manuscript gives a short overview on Förster Resonance Energy Transfer (FRET) of molecular interactions in the nanometre range. First, its principle is described and a short historical overview is given. Subsequently some principal methods and applications of FRET sensing and imaging are described (with some emphasis on fluorescence lifetime imaging, FLIM), and finally two innovative FRET techniques are presented in more detail. Applications are focused on measurements of living cells.
Identification and quantitative segmentation of individual blood vessels in mice visualized with preclinical imaging techniques is a tedious, manual or semiautomated task that can require weeks of reviewing hundreds of levels of individual data sets. Preclinical imaging, such as micro-magnetic resonance imaging (μMRI) can produce tomographic datasets of murine vasculature across length scales and organs, which is of outmost importance to study tumor progression, angiogenesis, or vascular risk factors for diseases such as Alzheimer’s. Training a neural network capable of accurate segmentation results requires a sufficiently large amount of labelled data, which takes a long time to compile. Recently, several reasonably automated approaches have emerged in the preclinical context but still require significant manual input and are less accurate than the deep learning approach presented in this paper—quantified by the Dice score. In this work, the implementation of a shallow, three-dimensional U-Net architecture for the segmentation of vessels in murine brains is presented, which is (1) open-source, (2) can be achieved with a small dataset (in this work only 8 μMRI imaging stacks of mouse brains were available), and (3) requires only a small subset of labelled training data. The presented model is evaluated together with two post-processing methodologies using a cross-validation, which results in an average Dice score of 61.34% in its best setup. The results show, that the methodology is able to detect blood vessels faster and more reliably compared to state-of-the-art vesselness filters with an average Dice score of 43.88% for the used dataset.
Data logging (DL) is used to compare the patients’ testimonials about how often they used their hearing aids. In addition, the hearing aid acoustician can compare how long and in which acoustic environments the patients wore their hearing aids. The hearing aid users’ statements often deviate from the information gained from DL. This raises the question of whether and when complications can occur in the recording of wearing behavior. The present study examined the reliability of DL and the factors that can affect it. In addition to the duration of the logging, the situation detection for three different manufacturers was also investigated. Different acoustic situations were designed using eight loudspeakers while the duration of measurement was three and eight hours. The results show that de documentation of the overall wearing time is very reliable, while reliability for detecting the hearing environment depends on the situation a manufacturer. Das Data Logging (DL) kommt in der Praxis häufig zum Einsatz, um die Aussagen der Kunden hinsichtlich der Tragedauer von Hörgeräten abzugleichen. Ebenfalls ist es dem Hörakustiker möglich nachzuvollziehen, wie lange und in welcher Situation der Kunde das Hörsystem getragen hat. Oftmals kommt es jedoch zu dem Fall, dass die Aufzeichnungen der Geräte von den Aussagen der Kunden abweichen. Somit stellt sich die Frage ob und wann es zu Komplikationen in der Aufzeichnung des Trageverhaltens kommen kann. In der hier vorgestellten Studie wurden die Zuverlässigkeit des Data Loggings und die Faktoren, wie z.B. der binauralen Synchronisation, die dieses beeinträchtigen können, untersucht. Dazu wurde neben der Aufzeichnungsdauer auch die Situationserkennung für drei verschiedene Hersteller überprüft. Unter Laborbedingungen wurden zum einen akustisch definierte „Standardsituationen“ (Sprache in Ruhe, Sprache im Störgeräusch) sowie eine komplexe Situation (Sprache im Störgeräusch zusammen mit Musik) über einen Lautsprecherkreis konstruiert und anhand von 3- und 8-Stunden-Messungen ausgewertet. Die Ergebnisse zeigen, dass die Tragedauer insgesamt sehr zuverlässig aufgezeichnet wird, die Hörumgebung hingegen je nach Situation und Hersteller besser und schlechter erfasst wird.
Eine Analyse des vorderen Augenabschnitts mit dem Oculus Pentacam Corneo-Skleral-Profil-Report
(2021)
Grundlagen der Optik
(2018)