The Quality of Life of Families of Children with Cerebral Palsy

Cerebral palsy, the most common cause of physical childhood disability, is a non-progressive disorder that results from an anoxic brain injury to the fetal or newborn brain. Because this disorder can cause disability, ranging from mild to severe effects on motor and cognitive functioning, the diagnosis can vary from one child to another, causing family stress due to vague and unknown predicted outcomes of the disorder. Because the diagnosis of cerebral palsy affects families in different ways depending on coping mechanisms, support systems, and the age and level of functioning of the child, among other factors, it is important to take an individualistic approach to care. Family-centered care has been shown to be beneficial in approaching the care needs of these families. To promote overall quality of life, efforts should be made to evaluate specific family member needs and include the entire family in the education, care planning, and implementation processes

Atomically resolved scanning force studies of vicinal Si(111)

Well-ordered stepped semiconductor surfaces attract intense attention owing to the regular arrangements of their atomic steps that makes them perfect templates for the growth of one- dimensional systems, e.g. nanowires. Here, we report on the atomic structure of the vicinal Si(111) surface with 10 degree miscut investigated by a joint frequency-modulation scanning force microscopy (FM-SFM) and ab initio approach. This popular stepped surface contains 7 x 7-reconstructed terraces oriented along the Si(111) direction, separated by a stepped region. Recently, the atomic structure of this triple step based on scanning tunneling microscopy (STM) images has been subject of debate. Unlike STM, SFM atomic resolution capability arises from chemical bonding of the tip apex with the surface atoms. Thus, for surfaces with a corrugated density of states such as semiconductors, SFM provides complementary information to STM and partially removes the dependency of the topography on the electronic structure. Our FM-SFM images with unprecedented spatial resolution on steps confirm the model based on a (7 7 10) orientation of the surface and reveal structural details of this surface. Two different FM-SFM contrasts together with density functional theory calculations explain the presence of defects, buckling and filling asymmetries on the surface. Our results evidence the important role of charge transfers between adatoms, restatoms, and dimers in the stabilisation of the structure of the vicinal surface

DNA methylation in CHO cells - Characterization of epigenetic phenomena under process conditions

Wippermann A. DNA methylation in CHO cells - Characterization of epigenetic phenomena under process conditions. Bielefeld: Universität Bielefeld; 2017

Grinding of transformation-toughened mixed oxide ceramic

During the manufacturing of ceramic components, grinding is an important manufacturing step. It influences the workpiece quality and the operational reliability. Thermomechanical loads during grinding can influence the lifetime and operational reliability of ceramics by modifying their bending strength and subsurface properties. Therefore, it is necessary to consider the influence of the grinding forces and mechanical loads on the strength of the ceramics in order to design a suitable grinding process. In this investigation, a quick-stop device is used to interrupt the grinding process of the newly developed mixed oxide ceramic SHYTZ (strontium hexaaluminate/yttria-toughened zirconia) and the market-established ceramic ATZ (alumina-toughened zirconia). Subsequently, an analysis of the occurring material removal phenomena, the number of active abrasive grains, and the real thermomechanical loads is carried out. It was found that the number of active grains and the material removal phenomena are influenced by the tool specifications. Besides that, the experimentally determined number of active grains was found to be up to 14 times higher than predicted by an analytical model given in literature. Consequently, the calculated single grain chip thickness was found to be up to 12.1% lower than analytically predicted. The investigation of the process forces and thermal loads showed up to 52% higher loads for ATZ than for SHYTZ. The subsequent analysis of the resulting bending strength of the ceramics revealed a lower influence of the grinding process on the strength of SHYTZ than for ATZ. Furthermore, a correlation between the used tool bonding and the resulting thermomechanical loads, bending strength, and residual stresses could be observed. © 2020, The Author(s)

Chirped refractive microlens arrays

The presented thesis deals with the design, the fabrication, and the characterization of nonregular microlens arrays that are referred to as "chirped microlens array" (cMLA) in accordance to other non-periodical structures. In contrast to conventional, regular microlens arrays that consist of a repetitive arrangement of a unit cell on a fixed, equidistantly sectioned grid, a cMLA contains similar but not identical lenses that are defined by a parametric description. The parameters of each cell can be defined by analytical functions, by using numerical optimization techniques, or by a combination of the both. Dependency on the position of the cell within the array is the most characteristic property of these functions. Overcoming the inflexibility of a regular arrangement leads to the enhancement of the classical array concept and enables new degrees of freedom in the design of micro-optical systems. The focus of this thesis is to point out the potentials of these new design possibilities which are explained by example systems built as prototypes. Fields of application are amongst others the improvement of the system's integration and the optimization of the optical performance of a system. Applications in the field of beam shaping and miniaturized imaging optics are discussed in detail as example systems. The latter enables extremely thin imaging objectives with a track length shorter than 250µm that have their natural antetype in the compound eyes of insects. The use of a cMLA allows the correction of off-axis aberrations and consequently the extension of the field of view of the objective, whereas the array describing function can be derived analytically. For the rst time, the use of a cMLA with individually adapted lenses allows the fabrication of objectives based on the well-known imaging principle that are compliant to the demands of industrial applications rather than just being proof-of-principle demonstrators. Furthermore, a fly's eye condenser setup based on cMLAs is discussed. In contrast to the application examples mentioned before, here the focus is on the collective interaction of all lenses of the array that leads to novel coherent effects. The periodic intensity peaks appearing in the plane of homogenization which are typical when using regular arrays can be avoided by employing non-periodic arrays. This leads to an improved homogeneity of the radiation. Fly's eye condensers based on cMLAs are especially advantageous when dealing with short pulse applications such as in sensing or material processing since otherwise applicable homogeneity improving measures are not suitable. The microlens arrays are fabricated using reflow of photoresist or laser lithography which had to be adapted to the specifics of cMLAs. This concerns especially software tools for the generation of mask layouts for the reflow of photoresist as well as profile data for laser lithography which had to be developed beforehand the prototyping and are now available as universal tools.Die vorliegende Arbeit befasst sich mit Aspekten des Designs, der Herstellung und der Charakterisierung nichtregulärer Mikrolinsenarrays, für die in Anlehnung an weitere nichtperiodische Strukturen der englischsprachige Begriff "chirped microlens array" (cMLA) eingeführt wurde. Im Gegensatz zu klassischen - regulären - Mikrolinsenarrays, die aus identischen Linsen mit konstantem Abstand zueinander gebildet werden, bestehen cMLAs aus ähnlichen, jedoch nicht identischen Linsen, die mittels parametrischer Beschreibung deniert sind. Die Zelldefinition kann durch analytische Funktionen, numerische Optimierungsverfahren oder eine Kombination aus beiden gewonnen werden. Bei allen gechirpten Arrays hängen die Funktionen von der Position der jeweiligen Zelle im Array ab.insen mit konstantem Abstand zueinander gebildet werden, bestehen cMLAs aus ähnlichen, jedoch nicht identischen Linsen, die mittels parametrischer Beschreibung deniert sind. Die Zelldefinition kann durch analytische Funktionen, numerische Optimierungsverfahren oder eine Kombination aus beiden gewonnen werden. Bei allen gechirpten Arrays hängen die Funktionen von der Position der jeweiligen Zelle im Array ab. Die Loslösung von der starren Geometrie regulärer Arrays führt zu einer Erweiterung des klassischen Arraybegriffes und ermöglicht neue Freiheitsgrade im Design mikrooptischer Systeme. Der Schwerpunkt der Arbeit ist auf das Aufzeigen der neuen Designmöglichkeiten gerichtet, welche anhand von prototypenhaft umgesetzten Beispielsystemen erläutert werden. Anwendungsgebiete sind hierbei unter anderem die Verbesserung der Integrationsmöglichkeiten und die Optimierung der Funktionsparameter optischer Systeme. Exemplarisch werden hierzu optische Designs und Prototypen diskutiert, die unter anderem Anwendungen in der Strahlformung und der miniaturisierten Abbildungsoptik besitzen. Letzteres betrifft ein ultra-dünnes Kamerasystem, welches auf einem Sehprinzip von Insekten basiert und Baulängen kleiner als 250um ermöglicht. Hierbei findet ein cMLA Einsatz, welches die Korrektur außeraxialer Bildfehler und damit die Vergrößerung des Gesichtsfeldes der Kamera ermöglicht. Die das Array beschreibenden Funktionen können hierbei vollständig analytisch abgeleitet werden. Die Nutzung eines cMLA aus individuell angepassten Linsen ermöglicht damit erstmals, das bekannte Abbildungsprinzip von akademischen Prinzipprototypen zu Systemen mit optischen Parametern zu erweitern, die den Einsatzbedingungen industrieller Anwendungen genügen. Weiterhin wird ein Wabenkondensoraufbau auf Basis von cMLAs zur Strahlhomogenisierung behandelt. Im Gegensatz zu den zuvor aufgeführten Anwendungsbereichen von cMLAs steht hierbei die Interaktion der Gesamtheit aller Linsen des Arrays im Mittelpunkt, was im Besonderen zu neuartigen kohärenten Effekten führt. Die Nutzung nichtregulärer Arrays ermöglicht die Vermeidung der ansonsten auftretenden periodischen Intensitätsmaxima und -minima in der Homogenisierungsebene, was mit einer Verbesserung der Homogenität einhergeht. Wabenkondensoren auf Basis von cMLAs sind im Speziellen für Kurzpulsanwendungen in der Sensorik und Materialbearbeitung von Interesse, da andere homogenitätsverbessernde Maßnahmen nicht angewendet werden können. Für die Herstellung der Arraystrukturen werden das Reflow von Fotolack und die Laserlithographie genutzt, die an die Besonderheiten der cMLAs anzupassen waren. Dies betrifft im Speziellen Softwaretools zur Erstellung von Maskendaten für den Reflowprozess und von profilbeschreibenden Daten für die Laserlithographie, die im Vorfeld der Prototypenfertigung entwickelt wurden und als universelle Werkzeuge zur Verfügung stehen