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.

Virus-induced senescence is a driver and therapeutic target in COVID-19.

Abstract: Derailed cytokine and immune cell networks account for the organ damage and the clinical severity of COVID-19 (refs. 1–4). Here we show that SARS-CoV-2, like other viruses, evokes cellular senescence as a primary stress response in infected cells. Virus-induced senescence (VIS) is indistinguishable from other forms of cellular senescence and is accompanied by a senescence-associated secretory phenotype (SASP), which comprises pro-inflammatory cytokines, extracellular-matrix-active factors and pro-coagulatory mediators5–7. Patients with COVID-19 displayed markers of senescence in their airway mucosa in situ and increased serum levels of SASP factors. In vitro assays demonstrated macrophage activation with SASP-reminiscent secretion, complement lysis and SASP-amplifying secondary senescence of endothelial cells, which mirrored hallmark features of COVID-19 such as macrophage and neutrophil infiltration, endothelial damage and widespread thrombosis in affected lung tissue1,8,9. Moreover, supernatant from VIS cells, including SARS-CoV-2-induced senescence, induced neutrophil extracellular trap formation and activation of platelets and the clotting cascade. Senolytics such as navitoclax and a combination of dasatinib plus quercetin selectively eliminated VIS cells, mitigated COVID-19-reminiscent lung disease and reduced inflammation in SARS-CoV-2-infected hamsters and mice. Our findings mark VIS as a pathogenic trigger of COVID-19-related cytokine escalation and organ damage, and suggest that senolytic targeting of virus-infected cells is a treatment option against SARS-CoV-2 and perhaps other viral infections. Virus-induced senescence is a central pathogenic feature in COVID-19, and senolytics, which promote apoptosis of senescent cells, can reduce disease severity in hamsters,mice, as well as humans infected with SARS-CoV-2.

Conduction electrons in GaAs: Five-level k⋅p theory and polaron effects

Abstract: Properties of conduction electrons in GaAs are described theoretically using a five-level k\ensuremath{\cdot}p model, which consistently accounts for inversion asymmetry of the material. The dispersion relation E(k) is computed and it is shown that the conduction band is both nonparabolic and nonspherical. The energy dependence of the electron effective mass, the energy-momentum relation in the forbidden gap, and the spin splitting of the band are calculated. Analytical expressions for the band-edge effective mass, the spin splitting, and the Land\'e factor ${g}^{\mathrm{*}}$ are presented, taking explicitly into account an interband matrix element of the spin-orbit interaction. A five-level P\ensuremath{\cdot}p theory for the conduction band in the presence of an external magnetic field is developed. Resonant and nonresonant effects due to polar electron--optic-phonon interaction are included in the theory. The spin g value of conduction electrons is calculated as a function of energy and magnetic field. Spin-doublet splitting of the cyclotron resonance and the cyclotron-resonance-mass anisotropy are described. A comparison of the theory with experimental data of various authors is used to determine important band parameters for GaAs. It is shown that away from the band edge the polaron effects in GaAs are comparable to the band-structure effects.

An imperceptible plastic electronic wrap.

Abstract: Extremely compliant sub-2-μm sensor films enable temperature mapping on complex 3D objects, like integrated circuits on printed circuit boards, food packages, and on human skin. In their stretchable form, these metal films withstand strains up to 275%. This imperceptible electronic foil technology platform offers new avenues for the design of complex, hybrid rigid-island stretchable-interconnect electronic devices such as RGB light-emitting diode (LED) strips that can be stretched and twisted without impairing their function.

A survey of music similarity and recommendation from music context data

Abstract: In this survey article, we give an overview of methods for music similarity estimation and music recommendation based on music context data. Unlike approaches that rely on music content and have been researched for almost two decades, music-context-based (or contextual) approaches to music retrieval are a quite recent field of research within music information retrieval (MIR). Contextual data refers to all music-relevant information that is not included in the audio signal itself. In this article, we focus on contextual aspects of music primarily accessible through web technology. We discuss different sources of context-based data for individual music pieces and for music artists. We summarize various approaches for constructing similarity measures based on the collaborative or cultural knowledge incorporated into these data sources. In particular, we identify and review three main types of context-based similarity approaches: text-retrieval-based approaches (relying on web-texts, tags, or lyrics), co-occurrence-based approaches (relying on playlists, page counts, microblogs, or peer-to-peer-networks), and approaches based on user ratings or listening habits. This article elaborates the characteristics of the presented context-based measures and discusses their strengths as well as their weaknesses.

Ultrafast dynamics of charge carrier photogeneration and geminate recombination in conjugated polymer:fullerene solar cells

Abstract: We investigate the nature of ultrafast exciton dissociation and carrier generation in acceptor-doped conjugated polymers. Using a combination of two-pulse femtosecond spectroscopy with photocurrent detection, we compare the exciton dissociation and geminate charge recombination dynamics in blends of two conjugated polymers, MeLPPP [methyl-substituted ladder-type poly($p$-phenylene)] and MDMO-PPV [poly(2-methoxy,5-(3,7-dimethyloctyloxy)-1,4-phenylenevinylene], with the electron accepting fullerene derivative PCBM [1-(3-methoxycarbonyl)-propyl-1-phenyl-$(6,6){\mathrm{C}}_{61}$]. This technique allows us to distinguish between free charge carriers and Coulombically bound polaron pairs. Our results highlight the importance of geminate pair recombination in photovoltaic devices, which limits the device performance. The comparison of different materials allows us to address the dependence of geminate recombination on the film morphology directly at the polymer:fullerene interface. We find that in the MeLPPP:PCBM blend exciton dissociation generates Coulombically bound geminate polaron pairs with a high probability for recombination, which explains the low photocurrent yield found in these samples. In contrast, in the highly efficient MDMO-PPV:PCBM blend the electron transfer leads to the formation of free carriers. The anisotropy dynamics of electronic transitions from neutral and charged states indicate that polarons in MDMO-PPV relax to delocalized states in ordered domains within $500\phantom{\rule{0.3em}{0ex}}\mathrm{fs}$. The results suggest that this relaxation enlarges the distance of carrier separation within the geminate pair, lowering its binding energy and favoring full dissociation. The difference in geminate pair recombination concurs with distinct dissociation dynamics. The electron transfer is preceded by exciton migration towards the PCBM sites. In MeLPPP:PCBM the exciton migration time decays smoothly with increasing PCBM concentration, indicating a trap-free exciton hopping. In MDMO-PPV:PCBM, however, the exciton migration time is found to show a threshold-like dependence on the PCBM concentration. This observation is explained by efficient interchain energy transfer in ordered MDMO-PPV domains in conjunction with exciton trapping.