Danube University Krems

About: Danube University Krems is a education organization based out in Krems, Niederösterreich, Austria. It is known for research contribution in the topics: Stroke & Population. The organization has 498 authors who have published 1572 publications receiving 68797 citations.

Carrier-based ranging in IEEE 802.11 wireless local area networks

Abstract: With the rise of Global Navigation Satellite Systems (GNSSes), accurate outdoor localization has become a widelyused service in our daily lives. Yet, most indoor localization systems are not able to deliver a similar performance due to typical multipath environments causing scattering and diffraction of the received signal. Depending on the amplitudes, phases, and delays of the multipath components, the measured range estimates are deteriorated by a significant ranging bias. This paper proposes a novel carrier phase locating method which improves the accuracy of time difference of arrival positioning systems in packet-based networks. The feasibility and practical applicability of the presented approach is demonstrated for a locating system based on IEEE 802.11 Wireless LAN. It is shown that the method is capable of reducing the ranging error to a few centimeters.

Hypomorphic Mutations in the BCR Signalosome Lead to Selective Immunoglobulin M Deficiency and Impaired B-cell Homeostasis.

Abstract: B cell activation via the B cell receptor (BCR) signalosome involves participation of signaling molecules such as BTK and BLNK. Genetic defects in these molecules are known to impair B cell differentiation and subsequently lead to agammaglobulinemia. Here we identified novel mutations in BTK and BLNK in two unrelated patients that perturb the intrinsic B-cell receptor signaling pathway and lead to selective IgM deficiency, whereas production of other immunoglobulin isotypes and IgG antibody response remain intact. Currently it is unknown how BCR signaling strength affects mature B cell development in humans. Both patients show reduced levels of BCR signalosome phosphorylation as well as impaired BCR-dependent Ca2+ influx, which was accompanied by a marked decrease in IgD+IgM+CD27+ MZ-like B-cells. We further describe reduced expression of essential B cell differentiation factors such as BAFF-R and T-Bet in the patients' B-cells, which might contribute to the observed deficiency of MZ-like B cells. MZ-like B cells are known to produce natural IgM antibodies that play an essential role in immune homeostasis. By using surface plasmon resonance (SPR) technology and a synthetic blood group A trisaccharide as antigen we were able to show that both patients lack the presence of anti-blood group A IgM considered to be prototypical natural antibodies whereas IgG levels were normal. Antibody binding dynamics and binding affinity of anti-blood group A IgG were comparable between patients and healthy controls. These results indicate that human IgM deficiency can be associated with signaling defects in the BCR signalosome, defective production of natural IgM antibodies in the blood group A/B/0 system and abnormalities in B cell development.

Multifunctional Nanostructures and Nanopocket Particles Fabricated by Nanoimprint Lithography.

Abstract: Nanostructured surfaces and nanoparticles are already widely employed in many different fields of research, and there is an ever-growing demand for reliable, reproducible and scalable nanofabrication methods. This is especially valid for multifunctional nanomaterials with physical properties that are tailored for specific applications. Here, we report on the fabrication of two types of nanomaterials. Specifically, we present surfaces comprising a highly uniform array of elliptical pillars as well as nanoparticles with the shape of nanopockets, possessing nano-cavities. The structures are fabricated by nanoimprint lithography, physical and wet-chemical etching and sputter deposition of thin films of various materials to achieve a multifunctional nanomaterial with defined optical and magnetic properties. We show that the nanopockets can be transferred to solution, yielding a nanoparticle dispersion. All fabrication steps are carefully characterized by microscopic and optical methods. Additionally, we show optical simulation results that are in good agreement with the experimentally obtained data. Thus, this versatile method allows to fabricate nanomaterials with specific tailor-made physical properties that can be designed by modelling prior to the actual fabrication process. Finally, we discuss possible application areas of these nanomaterials, which range from biology and medicine to electronics, photovoltaics and photocatalysis.

Student-Centered Classrooms in Engineering Education: Concept and Evaluation of a Learning Office for Software Development and Applied Mathematics

Abstract: This Research to Practice Full Paper depicts and evaluates a school pilot project introducing student-centered classrooms for applied mathematics and software development at a higher technical secondary school. These student-centered classrooms are an alternative organizational form: If students choose to participate in the pilot project, they have non-traditional class schedules. Students can choose freely which subject they want to work on each day and visit the respective room, called “learning office”. Self-explanatory learning material is available in each learning office and students work independently on exercises and projects at their own pace and level, allowing them to specialize according to their personal interests. Teachers accompany pupils as coaches who help them plan and structure.The evaluation showed that students choosing the student-centered form need time, about half a year, to adapt to the change of system and thus perform worse in their first attempt at exams. However, after passing the first year, there is no notable difference in software development and only a weakly significant difference in applied mathematics. The average grades and passing rate of the two approaches show no notable differences. By cooperating significantly more frequently they develop social skills and show significantly higher motivation for attending school.