Flexibles Lernen: Erfolgreiche online-gestützte Lernprozesse ermöglichen

Die Digitalisierung im Gesundheitswesen erfordert eine kontinuierliche Weiterqualifikation der betroffenen Berufsgruppen. Die Universität UMIT hat daher 2017 einen online-gestützten, postgraduellen Universitätslehrgang gestartet. Beim didaktischen Design lag ein Schwerpunkt auf der Flexibilität des Lernens, um so den Anforderungen der berufstätigen Teilnehmer/innen besonders zu entsprechen. Dabei wurde neben Flexibilität von Ort und Zeit des Lernens auch Flexibilität z. B. beim Setzen eigener Lernziele und bei Lerninhalten ermöglicht. Wir stellen das gewählte didaktische Design vor und beleuchten auf Basis einer Analyse von Log-Daten, studentischer Evaluationen sowie studentischer Reflexionen die Akzeptanz sowie die Herausforderungen des flexiblen Lernens aus Sicht der Lernenden

New theoretical approaches for correlated systems in nonequilibrium

Abstract.: We review recent developments in the theory of interacting quantum many-particle systems that are not in equilibrium. We focus mainly on the nonequilibrium generalizations of the flow equation approach and of dynamical mean-field theory (DMFT). In the nonequilibrium flow equation approach one first diagonalizes the Hamiltonian iteratively, performs the time evolution in this diagonal basis, and then transforms back to the original basis, thereby avoiding a direct perturbation expansion with errors that grow linearly in time. In nonequilibrium DMFT, on the other hand, the Hubbard model can be mapped onto a time-dependent self-consistent single-site problem. We discuss results from the flow equation approach for nonlinear transport in the Kondo model, and further applications of this method to the relaxation behavior in the ferromagnetic Kondo model and the Hubbard model after an interaction quench. For the interaction quench in the Hubbard model, we have also obtained numerical DMFT results using quantum Monte Carlo simulations. In agreement with the flow equation approach they show that for weak coupling the system relaxes to a "prethermalized” intermediate state instead of rapid thermalization. We discuss the description of nonthermal steady states with generalized Gibbs ensemble

Indikatoren für kooperative, online-basierte Lernprozesse: Entwicklung und Erprobung

Lernen als konstruktiver und sozialer Prozess funktioniert am besten in Interaktion mit anderen Personen. Insbesondere in online-basierten Lernsettings sind Interaktion und Kooperation der Studierenden ein wichtiger Faktor für erfolgreiches Lernen. In dieser Arbeit schlagen wir zunächst Indikatoren für das Monitoring der Aktivität und Interaktivität von Studierenden sowie Lehrenden in kooperativen online-basierten Lernsettings vor. In einer Fallstudie werden die Indikatoren dann am Beispiel von drei Online-Kursen eingesetzt. Die Ergebnisse zeigen, dass die Indikatoren wichtige Aufschlüsse über die Aktivität und Interaktivität der Studierenden liefern können. Ergänzt um Daten zur Arbeitsbelastung, um Prüfungsergebnisse und um Lehrevaluierungen können auch Aussagen zur Qualität der Lernprozesse und zum Lernerfolg gemacht werden

Weak and strong electronic correlations in Fe superconductors

In this chapter the strength of electronic correlations in the normal phase of Fe-superconductors is discussed. It will be shown that the agreement between a wealth of experiments and DFT+DMFT or similar approaches supports a scenario in which strongly-correlated and weakly-correlated electrons coexist in the conduction bands of these materials. I will then reverse-engineer the realistic calculations and justify this scenario in terms of simpler behaviors easily interpreted through model results. All pieces come together to show that Hund's coupling, besides being responsible for the electronic correlations even in absence of a strong Coulomb repulsion is also the origin of a subtle emergent behavior: orbital decoupling. Indeed Hund's exchange decouples the charge excitations in the different Iron orbitals involved in the conduction bands thus causing an independent tuning of the degree of electronic correlation in each one of them. The latter becomes sensitive almost only to the offset of the orbital population from half-filling, where a Mott insulating state is invariably realized at these interaction strengths. Depending on the difference in orbital population a different 'Mottness' affects each orbital, and thus reflects in the conduction bands and in the Fermi surfaces depending on the orbital content.Comment: Book Chapte

MicroRNAs differentially present in the plasma of HIV elite controllers reduce HIV infection in vitro

Elite controllers maintain HIV-1 viral loads below the limit of detection. The mechanisms responsible for this phenomenon are poorly understood. As microRNAs (miRNAs) are regulators of gene expression and some of them modulate HIV infection, we have studied the miRNA profile in plasma from HIV elite controllers and chronically infected individuals and compared against healthy donors. Several miRNAs correlate with CD41 T cell count or with the known time of infection. No significant differences were observed between elite controllers and healthy donors; however, 16 miRNAs were different in the plasma of chronic infected versus healthy donors. In addition, levels of hsa-miR-29b-3p, hsa-miR-33a-5p and hsa-miR-146a-5p were higher in plasma from elite controllers than chronic infected and hsa-miR-29b-3p and hsa-miR-33a-5p overexpression significantly reduced the viral production in MT2 and primary T CD41 cells. Therefore, levels of circulating miRNAs might be of diagnostic and/or prognostic value for HIV infection, and hsa-miR-29b-3p and miR-33a-5p may contribute to the design of new anti-HIV drugs.Fil: Reynoso, Rita Paola. University of Natural Resources and Life Sciences; AustriaFil: Laufer, Natalia Lorna. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas en Retrovirus y Sida; Argentina. Gobierno de la Ciudad de Buenos Aires. Hospital General de Agudos "Juan A. Fernández"; Argentina. Universidad de Buenos Aires; ArgentinaFil: Hackl, Matthias. University of Natural Resources and Life Sciences; Austria. Tamirna Gmbh; AustriaFil: Skalicky, Susanna. Evercyte Gmbh; AustriaFil: Monteforte, Rossella. University of Natural Resources and Life Sciences; AustriaFil: Turk, Gabriela Julia Ana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas en Retrovirus y Sida; Argentina. Universidad de Buenos Aires; ArgentinaFil: Carobene, Mauricio. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas en Retrovirus y Sida; ArgentinaFil: Quarleri, Jorge Fabian. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Investigaciones Biomédicas en Retrovirus y Sida. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Investigaciones Biomédicas en Retrovirus y Sida; ArgentinaFil: Cahn, Pedro. Fundación Huésped; Argentina. Gobierno de la Ciudad de Buenos Aires. Hospital General de Agudos "Juan A. Fernández"; ArgentinaFil: Werner, Roland. Medizinische Universitat Innsbruck; AustriaFil: Stoiber, Heribert. Medizinische Univesitat Innsbruck; AustriaFil: Grillari Voglauer, Regina. University of Natural Resources and Life Sciences; Austria. Evercyte Gmbh; AustriaFil: Grillari, Johannes. University of Natural Resources and Life Sciences; Austria. Evercyte Gmbh; Austri

Stripes and electronic quasiparticles in the pseudogap state of cuprate superconductors

This article is devoted to a discussion of stripe and electron-nematic order and their connection to electronic properties in the pseudogap regime of copper-oxide superconductors. We review basic properties of these symmetry-breaking ordering phenomena as well as proposals which connect them to quantum-oscillation measurements. Experimental data indicate that these orders are unlikely to be the cause of the pseudogap phenomenon, implying that they occur on top of the pseudogap state which itself is of different origin. Specifically, we discuss the idea that the non-superconducting pseudogap ground state hosts electron-like quasiparticles which coexist with a spin liquid, realizing a variant of a fractionalized Fermi liquid. We speculate on how stripe order in such a pseudogap state might offer a consistent description of ARPES, NMR, quantum-oscillation, and transport data.Comment: 15 pages, 6 figs. Article prepared for a Physica C special issue on "Stripes and Electronic Liquid Crystals

Microscopic origin of Cooper pairing in the iron-based superconductor Ba₁₋ₓKₓFe₂As₂

Resolving the microscopic pairing mechanism and its experimental identification in unconventional superconductors is among the most vexing problems of contemporary condensed matter physics. We show that Raman spectroscopy provides an avenue towards this aim by probing the structure of the pairing interaction at play in an unconventional superconductor. As we study the spectra of the prototypical Fe-based superconductor Ba1−xKxFe2As2 for 0.22 ≤ x ≤ 0.70 in all symmetry channels, Raman spectroscopy allows us to distill the leading s-wave state. In addition, the spectra collected in the B1g symmetry channel reveal the existence of two collective modes which are indicative of the presence of two competing, yet sub-dominant, pairing tendencies of dx2−y2 symmetry type. A comprehensive functional Renormalization Group and random-phase approximation study on this compound confirms the presence of the two sub-leading channels, and consistently matches the experimental doping dependence of the related modes. The consistency between the experimental observations and the theoretical modeling suggests that spin fluctuations play a significant role in superconducting pairing

Orbital-selective Mott transitions: Heavy fermions and beyond

Quantum phase transitions in metals are often accompanied by violations of Fermi liquid behavior in the quantum critical regime. Particularly fascinating are transitions beyond the Landau-Ginzburg-Wilson concept of a local order parameter. The breakdown of the Kondo effect in heavy-fermion metals constitutes a prime example of such a transition. Here, the strongly correlated f electrons become localized and disappear from the Fermi surface, implying that the transition is equivalent to an orbital-selective Mott transition, as has been discussed for multi-band transition-metal oxides. In this article, available theoretical descriptions for orbital-selective Mott transitions will be reviewed, with an emphasis on conceptual aspects like the distinction between different low-temperature phases and the structure of the global phase diagram. Selected results for quantum critical properties will be listed as well. Finally, a brief overview is given on experiments which have been interpreted in terms of orbital-selective Mott physics.Comment: 29 pages, 4 figs, mini-review prepared for a special issue of JLT