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In the brain-cell microenvironment, diffusion plays an important role: apart from delivering glucose and oxygen from the vascular system to brain cells, it also moves informational substances between cells. The brain is an extremely complex structure of interwoven, intercommunicating cells, but recent theoretical and experimental works showed that the classical laws of diffusion, cast in the framework of porous media theory, can deliver an accurate quantitative description of the way molecules are transported through this tissue. The mathematical modeling and the numerical simulations are successfully applied in the investigation of diffusion processes in tissues, replacing the costly laboratory investigations. Nevertheless, modeling must rely on highly accurate information regarding the main parameters (tortuosity, volume fraction) which characterize the tissue, obtained by structural and functional imaging. The usual techniques to measure the diffusion mechanism in brain tissue are the radiotracer method, the real time iontophoretic method and integrative optical imaging using fluorescence microscopy. A promising technique for obtaining the values for characteristic parameters of the transport equation is the direct optical investigation using optical fibers. The analysis of these parameters also reveals how the local geometry of the brain changes with time or under pathological conditions. This paper presents a set of computations concerning the mass transport inside the brain tissue, for different types of cells. By measuring the time evolution of the concentration profile of an injected substance and using suitable fitting procedures, the main parameters characterizing the tissue can be determined. This type of analysis could be an important tool in understanding the functional mechanisms of effective drug delivery in complex structures such as the brain tissue. It also offers possibilities to realize optical imaging methods for in vitro and in vivo measurements using optical fibers. The model also may help in radiotracer biomarker models for the understanding of the mechanism of action of new chemical entities.
Not only is the number of new devices constantly increasing, but so is their application complexity and power. Most of their applications are in optics, photonics, acoustic and mobile devices. Working speed and functionality is achieved in most of media devices by strategic use of digital signal processors and microcontrollers of the new generation. Considering all these premises of media development dynamics, the authors present how to integrate microcontrollers and digital signal processors in the curricula of media technology lectures by using adequate content. This also includes interdisciplinary content that consists of using the acquired knowledge in media software. These entries offer a deeper understanding of photonics, acoustics and media engineering.
Member Lens
(2013)
After Image
(2013)
Hybrid SPECT/US
(2014)
This paper presents new measurements of a bronze cast from the right hand of the famous Italian violin virtuoso Nicolò Paganini (1782-1840). These are compared to anthropometric standard values. In addition, detailed dorsal and palmar views of the cast are shown. With a middle finger length of 75 mm, the palm width is 60 mm and the hand length 152 mm, which is significantly below the 5% percentile of today's standard values. Also the finger length index (0.55), the ratio of finger length to palm length (0.98) and the ratio of finger length to palm width (1.25) are significantly above normal limits. Hence, Paganini had abnormal hand measurements with a very small palm and relatively "long" fingers. This remarkable constellation, among others, could have been advantageous for his amazing skills as a violinist.
Geschichte(n) der Medizin
(2014)
Seit Menschengedenken schreibt die Medizin ihre eigene(n) Geschichte(n). Bis heute faszinieren Berichte über Krankheiten oder Todesfolgen vergangener Zivilisationen, Herrscher und Persönlichkeiten. In diesem Band werden ausgewählte Vitae aus der Zeit zwischen dem zweiten Jahrhundert vor Christus und heute exemplarisch und kurzweilig vorgestellt.
Doch nicht nur die hier wiedergegebenen Krankheitsverläufe der prominenten Protagonisten faszinieren. Mindestens genauso bemerkenswert sind die dargestellten Veränderungen von Moral-Vorstellungen innerhalb der Geschichte(n): So verbietet beispielsweise der Eid des Hippokrates das Blasenstein¬-Schneiden – doch heute ist die Entfernung von Nephrolithen immanenter Bestandteil der Urologie. Und während die Deklaration des Weltärztebundes aus dem Jahr 1948 – das sogenannte Genfer Gelöbnis – den Schwangerschaftsabbruch noch ablehnt, ist dieser heutzutage (in engen Grenzen) erlaubt.
Den renommierten Autoren des vorliegenden Bandes gelingt es mühelos und mitreißend, Geschichte(n) der Medizin in Biografien und Erzählungen lebendig werden zu lassen. Ihre historischen Betrachtungen sind gleichermaßen unterhaltsam wie lehrreich.
We report the use of the Raman spectral information of the chemical compound toluene C7H8 as a reference on the analysis of laboratory-prepared and commercially acquired gasoline-ethanol blends. The rate behavior of the characteristic Raman lines of toluene and gasoline has enabled the approximated quantification of this additive in commercial gasoline-ethanol mixtures. This rate behavior has been obtained from the Raman spectra of gasoline-ethanol blends with different proportions of toluene.
All these Raman spectra have been collected by using a self-designed, frequency precise and low-cost Fourier-transform Raman spectrometer (FT-Raman spectrometer) prototype. This FT-Raman prototype has helped to accurately confirm the frequency position of the main characteristic Raman lines of toluene present on the different gasoline-ethanol samples analyzed at smaller proportions than those commonly found in commercial gasoline-ethanol blends. The frequency accuracy validation has been performed by analyzing the same set of toluene samples with two additional state-of-the-art commercial FT-Raman devices. Additionally, the spectral information has been contrasted, with highly-correlated coefficients as a result, with the values of the standard Raman spectrum of toluene.
Chronic insomnia is defined by difficulties in falling asleep, maintaining sleep, and early morning awakening, and is coupled with daytime consequences such as fatigue, attention deficits, and mood instability. These symptoms persist over a period of at least 3 months (Diagnostic and Statistical Manual 5 criteria). Chronic insomnia can be a symptom of many medical, neurological, and mental disorders. As a disorder, it incurs substantial health-care and occupational costs, and poses substantial risks for the development of cardiovascular and mental disorders, including cognitive deficits. Family and twin studies confirm that chronic insomnia can have a genetic component (heritability coefficients between 42% and 57%), whereas the investigation of autonomous and central nervous system parameters has identified hyperarousal as a final common pathway of the pathophysiology, implicating an imbalance of sleep–wake regulation consisting of either overactivity of the arousal systems, hypoactivity of the sleep-inducing systems, or both. Insomnia treatments include benzodiazepines, benzodiazepine-receptor agonists, and cognitive behavioural therapy. Treatments currently under investigation include transcranial magnetic or electrical brain stimulation, and novel methods to deliver psychological interventions.
Geschichte(n) der Medizin
(2015)
Renommierte Autoren erzählen lebendige und mitreißende Geschichte(n) der Medizin über Krankheiten, Ärzte und Forscher.
-Wie kam es zur Entdeckung des Blutkreislaufes, wo man doch lange Zeit glaubte, die Leber produziere täglich Tausende von Litern Blut?
-Warum sind Hirnschrittmacher erst viel später als Herzschrittmacher auf der medizinischen Bühne erschienen, wo doch das Gehirn schon in der Antike trepaniert und erforscht wurde?
-Die Antworten auf diese und andere Fragen werden nicht nur wissenschaftlich exakt, sondern auch überaus unterhaltsam gegeben.
-Beachtlich, dass Friedrich II. von Preußen auch begnadeter Hobby-Arzt war.
-Bemerkenswert, wie eine Frau zu einer Zeit zielstrebig Ärztin wurde, als nur Männer Medizin studieren durften.
-Bewegend die Erlebnisse eines Arztes an der Front.
-Faszinierend, wie ein „Wunderdoktor“ reihenweise Frauen in Ohnmacht versetzte, um sie zu heilen; er wurde damit zum Mitbegründer der Psychotherapie.
-Das Buch knüpft mit diesen und weiteren Erzählungen an den großen Erfolg des ersten Bandes an und bietet in populärwissenschaftlicher Weise neues Lese- und Bildungsvergnügen.
Die vorliegende Bachelor Thesis befasst sich mit der Funktionsweise des ArduPilot Open Source Autopiloten. Für die Ausführung erfolgt mit einem Pixhawk Flugcontroller. Dabei wird die Funktionsweise der Regler und der Navigation des Luftfahrzeuges untersucht. Nach der Analyse des Regler Aufbaus werden wird die Regelung für einen Multiplex EasyStar 2 ausgelegt und in dem Flugzeug verbaut. Für die Kommunikation mit dem Pixhawk Flugcontroller und der Parametereinstellung für die Regelung wird die Mission Planner Bodenstation verwendet. Die Regelung wird mit praktischen Flugtests und der automatischen Tuning Funktion durchgeführt. Mit Hilfe der angelegten Daten Protokolle während des Flugs wird im Nachhinein das Flugverhalten des Multiplex EasyStar 2 ausgewertet und angepasst. Nach der Auslegung der Regelparameter besteht die Aufgabe darin, einen vollautonomen Flug mit automatischem Start und automatischer Landung durchzuführen. Die Wegpunkt Generierung für den autonomen Flug erfolgt mit der Mission Planner Bodenstation. Es soll mit dieser Arbeit die Zuverlässigkeit und Genauigkeit des Systems überprüft werden.
UAVs (engl. Unmanned Aerial Vehicles) sind in den vergangenen Jahren auch außerhalb militärischer und wissenschaftlicher Nutzung beliebter geworden. Für autonome Fluganwendungen ist die Überwachung der Umgebung zwingend notwendig. In dieser Arbeit wird ein experimenteller Ansatz zur Hinderniserkennung mit Radar- und Lidarsensorik präsentiert. Dieser setzt sich aus der Kollisionsvermeidung der Flugsteuerung px4, einem Nvidia Jetson TX2 als Flugbegleitcomputer und den Sensoren Slamtec RPLidar A2M6 und Texas Instruments AWR1443 Radar zusammen. Insgesamt wurden drei verschiedene Hardwarekomponenten getestet. Zur Auswertung der Versuche wird eine durch Python OS-unabhängige Auswertesoftware entwickelt und implementiert. Die Versuchsplanung setzt sich aus drei Versuchen mit jeweils fünf in Geometrie und Textur unterschiedlichen Hindernissen zusammen. Die Versuchsergebnisse zeigen, dass der eingesetzte Lidar gegenüber dem Radar Vorteile auf kurze Distanz aufweist. Zur Reproduzierbarkeit von Experimenten auf kurzer Distanz wird die Entwicklung eines fixen Messaufbaus empfohlen.
In this study, various imaging algorithms for the localization of objects have been investigated. Therefore, an Ultra-Wideband (UWB) radar based experimental setup with a circular antenna array is designed as part of this work. This concept could be particularly useful in microwave medical imaging applications. In order to validate its applicability in microwave imaging, different imaging algorithms have been evaluated and compared by means of our experimental setup. Accurate imaging results have been achieved with our system under multiple test-scenarios.
In this study, an approach to a microwave-based radar system for the localization of objects has been proposed. This could be particularly useful in microwave imaging applications such as cardiac catheter detection. An experimental system is defined and realized with the selection of an appropriate antenna design. Hardware control functions and different imaging algorithms are implemented as well. The functionality of this measurement setup has been analyzed considering multiple testscenarios and it is proved to be capable of locating multiple objects as well as expanded objects.
In automotive parking scenario, where the curb shall be detected and classified to be traversable or not, radars play an important role. There are different approaches already proposed in other works to estimate the target height. This paper assesses and compares two methods. The first is based on Angle of Arrival (AoA) estimation of input signals of multiple antennas using the Multiple-Input-Multiple-Output (MIMO) principle. The second method uses the geometry in multipath propagation of the radar echo signal for one antenna input. In this work a modified method of calculation of the curb height based on the second method is proposed. The theory of approach is mathematically proved and effectiveness is demonstrated by evaluation of measurements with a 77 GHz Frequency Modulated Continuous Wave (FMCW) radar. In order to evaluate the performance of the introduced method the mean square error (MSE) is used in the proposed scenario. This method, using only one antenna input, produced up to 3.4 times better results for curb height detection in comparison with former methods.
Konzeption und Evaluierung eines Trainings-Windkanals für den spezifischen Einsatz im Skisprung
(2022)
AI-based Ground Penetrating Radar Signal Processing for Thickness Estimation of Subsurface Layers
(2023)
This thesis focuses on the estimation of subsurface layer thickness using Ground Penetrating Radar (GPR) A-scan and B-scan data through the application of neural networks. The objective is to develop accurate models capable of estimating the thickness of up to two subsurface layers.
Two different approaches are explored for processing the A-scan data. In the first approach, A-scans are compressed using Principal Component Analysis (PCA), and a regression feedforward neural network is employed to estimate the layers’ thicknesses. The second approach utilizes a regression one-dimensional Convolutional Neural Network (1-D CNN) for the same purpose. Comparative analysis reveals that the second approach yields superior results in terms of accuracy.
Subsequently, the proposed 1-D CNN architecture is adapted and evaluated for Step Frequency Continuous Wave (SFCW) radar, expanding its applicability to this type of radar system. The effectiveness of the proposed network in estimating subsurface layer thickness for SFCW radar is demonstrated.
Furthermore, the thesis investigates the utilization of GPR B-scan images as input data for subsurface layer thickness estimation. A regression CNN is employed for this purpose, although the results achieved are not as promising as those obtained with the 1-D CNN using A-scan data. This disparity is attributed to the limited availability of B-scan data, as B-scan generation is a resource-intensive process.
Skin cancer detection proves to be complicated and highly dependent on the examiner’s skills. Millimeter-wave technologies seem to be a promising aid for the detection of skin cancer. The different water content of the skin area affected by cancer compared to healthy skin changes its reflective property. Due to limited available resources on the dielectric properties of skin cancer, especially in comparison to surrounding healthy skin, accurate simulations and evaluations are quite challenging. Therefore, comparing different results for different approaches and starting points can be difficult. In this paper, the Effective Medium Theory is applied to model skin cancer, which provides permittivity values dependent on the water content.
A method for evaluating skin cancer detection based on millimeter-wave technologies is presented. For this purpose, the relative permittivities are calculated using the effective medium theory for the benign and cancerous lesion, considering the change in water content between them. These calculated relative permittivities are further used for the simulation and evaluation of skin cancer detection using a substrate-integrated waveguide probe. A difference in the simulated scattering parameters S 11 of up to 13dB between healthy and cancerous skin can be determined in the best-case.
Investigation on Bowtie Antennas Operating at Very Low Frequencies for Ground Penetrating Radar
(2023)
The efficiency of Ground Penetrating Radar (GPR) systems significantly depends on the antenna performance as the signal has to propagate through lossy and inhomogeneous media. GPR antennas should have a low operating frequency for greater penetration depth, high gain and efficiency to increase the receiving power and should be compact and lightweight for ease of GPR surveying. In this paper, two different designs of Bowtie antennas operating at very low frequencies are proposed and analyzed.