Die Lösungen der Blasiusschen Grenzschichtdifferentialgleichung

Die Blasiussche Grenzschichtdifferentialgleichung f''' + ff'' = 0 für die dimensionslose Stromfunktion f ([eta]) wird systematisch auf ihre Lösungen hin untersucht. Unter Ausnutzung bekannter mathematischer Eigenschaften dieser Differentialgleichung und ihrer Lösungen und unter Verwendung gewisser Transformationen der Differentialgleichung gelingt es, eine Übersicht über alle reellen Lösungen zu gewinnen. Die Lösungen können in drei Lösungstypen unterteilt werden, die sich durch ihr asymptotisches Verhalten für [eta] - [unendlich]; 3. Lösungen des Typs III sind durch die asymptotische Form f = [alpha] + [beta][eta] für [eta] -> - [unendlich] gekennzeichnet. Die Lösungen des Typs I bilden in der f' - f-Ebene eine Enveloppe, deren Verlauf berechnet wird. - Die Lösungen werden hinsichtlich ihrer physikalischen Interpretierbarkeit diskutiert

Efficient computation of the pressures developed during high-speed train passing events

The paper resumes the results obtained applying various implementations of the direct boundary element method (BEM) to the solution of the Laplace Equation governing the potential flow problem during everyday service manoeuvres of high-speed trains. In particular the results of train passing events at three different speed combinations are presented. Some recommendations are given in order to reduce calculation times which as is demonstrated can be cut down to not exceed reasonable limits even when using nowadays office PCs. Thus the method is shown to be a very valuable tool for the design engineer

Branching of the Falkner-Skan solutions for λ < 0

The Falkner-Skan equation f'" + ff" + λ(1 - f'^2) = 0, f(0) = f'(0) = 0, is discussed for λ < 0. Two types of problems, one with f'(∞) = 1 and another with f'(∞) = -1, are considered. For λ = 0- a close relation between these two types is found. For λ < -1 both types of problem allow multiple solutions which may be distinguished by an integer N denoting the number of zeros of f' - 1. The numerical results indicate that the solution branches with f'(∞) = 1 and those with f'(∞) = -1 tend towards a common limit curve as N increases indefinitely. Finally a periodic solution, existing for λ < -1, is presented.

Kopfformen fuer Hochgeschwindigkeitstriebzuege: die SD-Reihe und die KS-Form

TIB: RN 4173 (1980,29) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

HBEGF-TNF induce a complex outer retinal pathology with photoreceptor cell extrusion in human organoids

Human organoids could facilitate research of complex and currently incurable neuropathologies, such as age-related macular degeneration (AMD) which causes blindness. Here, we establish a human retinal organoid system reproducing several parameters of the human retina, including some within the macula, to model a complex combination of photoreceptor and glial pathologies. We show that combined application of TNF and HBEGF, factors associated with neuropathologies, is sufficient to induce photoreceptor degeneration, glial pathologies, dyslamination, and scar formation: These develop simultaneously and progressively as one complex phenotype. Histologic, transcriptome, live-imaging, and mechanistic studies reveal a previously unknown pathomechanism: Photoreceptor neurodegeneration via cell extrusion. This could be relevant for aging, AMD, and some inherited diseases. Pharmacological inhibitors of the mechanosensor PIEZO1, MAPK, and actomyosin each avert pathogenesis; a PIEZO1 activator induces photoreceptor extrusion. Our model offers mechanistic insights, hypotheses for neuropathologies, and it could be used to develop therapies to prevent vision loss or to regenerate the retina in patients suffering from AMD and other diseases