Johannes Kepler University of Linz

About: Johannes Kepler University of Linz is a education organization based out in Linz, Oberösterreich, Austria. It is known for research contribution in the topics: Computer science & Thin film. The organization has 6605 authors who have published 19243 publications receiving 385667 citations.

Harnessing snap-through instability in soft dielectrics to achieve giant voltage-triggered deformation

Abstract: A soft dielectric membrane is prone to snap-through instability. We present theory and experiment to show that the instability can be harnessed to achieve giant voltage-triggered deformation. We mount a membrane on a chamber of a suitable volume, pressurize the membrane into a state near the verge of the instability, and apply a voltage to trigger the snap without causing electrical breakdown. For an acrylic membrane we demonstrate voltage-triggered expansion of area by 1692%, far beyond the largest value reported in the literature. The large expansion can even be retained after the voltage is switched off.

A Randomized Trial of Factor VIII and Neutralizing Antibodies in Hemophilia A

Abstract: BackgroundThe development of neutralizing anti–factor VIII alloantibodies (inhibitors) in patients with severe hemophilia A may depend on the concentrate used for replacement therapy. MethodsWe conducted a randomized trial to assess the incidence of factor VIII inhibitors among patients treated with plasma-derived factor VIII containing von Willebrand factor or recombinant factor VIII. Patients who met the eligibility criteria (male sex, age <6 years, severe hemophilia A, and no previous treatment with any factor VIII concentrate or only minimal treatment with blood components) were included from 42 sites. ResultsOf 303 patients screened, 264 underwent randomization and 251 were analyzed. Inhibitors developed in 76 patients, 50 of whom had high-titer inhibitors (≥5 Bethesda units). Inhibitors developed in 29 of the 125 patients treated with plasma-derived factor VIII (20 patients had high-titer inhibitors) and in 47 of the 126 patients treated with recombinant factor VIII (30 patients had high-titer inhib...

Fatty acid salts as stabilizers in size- and shape-controlled nanocrystal synthesis: the case of inverse spinel iron oxide.

Abstract: Various oleic acid salts are demonstrated to act as stabilizers for high-quality iron oxide nanocrystals, synthesized by thermal decomposition of ferric oleate. Changing the cation species in oleic acid salts allows different degrees of dissociation at high temperatures to be obtained, resulting in various stabilizer performances: Sodium oleate as stabilizer results in monodisperse iron oxide nanocrystals of cubic shape with precisely adjustable edge lengths between 7 and 23 nm. Dibutylammonium oleate and oleic acid, in contrast, induce growth of spherical nanocrystals in the same size range. Further adjustment of the growth conditions leads to {100}-bound bipyramidal nanocrystals with a single, (111) oriented twin plane. While the nanocrystal size is related to their superparamagnetic blocking temperature, the shape influences their magnetization hysteresis properties observed at low temperatures.

Convergence rates of convex variational regularization

Abstract: The aim of this paper is to provide quantitative estimates for the minimizers of non-quadratic regularization problems in terms of the regularization parameter, respectively the noise level. As usual for ill-posed inverse problems, these estimates can be obtained only under additional smoothness assumptions on the data, the so-called source conditions, which we identify with the existence of Lagrange multipliers for a limit problem. Under such a source condition, we shall prove a quantitative estimate for the Bregman distance induced by the regularization functional, which turns out to be the natural distance measure to use in this case. We put a special emphasis on the case of total variation regularization, which is probably the most important and prominent example in this class. We discuss the source condition for this case in detail and verify that it still allows discontinuities in the solution, while imposing some regularity on its level sets.