Cellular Prion Protein Mediates Toxic Signaling of Amyloid Beta

Prion diseases in humans and animals comprise a group of invariably fatal neurodegenerative diseases characterized by the formation of a pathogenic protein conformer designated PrPSc and infectious particles denoted prions. The cellular prion protein (PrPC) has a central role in the pathogenesis of prion disease. First, it is the precursor of PrPSc and infectious prions and second, its expression on neuronal cells is required to mediate toxic effects of prions. To specifically study the role of PrPC as a mediator of toxic signaling, we have developed novel cell culture models, including primary neurons prepared from PrP-deficient mice. Using these approaches we have been able to show that PrPC can interact with and mediate toxic signaling of various beta-sheet-rich conformers of different origins, including amyloid beta, suggesting a pathophysiological role of the prion protein beyond prion diseases. Copyright (C) 2011 S. Karger AG, Base

Time–temperature–transformation diagram and microstructures of bulk glass forming Pd40Cu30Ni10P20

Isothermal crystallization studies were performed on the bulk glass forming alloy Pd40Cu30Ni10P20 in the undercooled liquid region between the glass transition and liquidus temperature, resulting in a complete time–temperature–transformation (TTT) diagram for crystallization. The TTT diagram shows a typical "C" shape with the nose at 50 s and 680 K. Assuming steady state nucleation and a diffusion-controlled growth rate, the TTT diagram was successfully fit over the entire range of the measurement. The microstructure after isothermal crystallization shows a modulation in Cu and P for all degrees of undercooling. The primary solidified phase is Cu3Pd, which forms distinct dendrites at low undercooling. From additional constant cooling experiments, the critical cooling rate to bypass crystallization was determined to be 0.33 K/s

Optical transparency of graphene as determined by the fine-structure constant

The observed 97.7% optical transparency of graphene has been linked to the value 1/137 of the fine structure constant, by using results for noninteracting Dirac fermions. The agreement in three significant figures requires an explanation for the apparent unimportance of the Coulomb interaction. Using arguments based on Ward identities, the leading corrections to the optical conductivity due to the Coulomb interactions are correctly computed (resolving a subtle theoretical issue) and shown to amount to only 1-2%, corresponding to 0.03-0.04% in the transparency.Comment: 5 pages, 2 figures, Minor changes, published version with a new titl

Critical behavior of the three-dimensional bond-diluted Ising spin glass: Finite-size scaling functions and Universality

We study the three-dimensional (3D) bond-diluted Edwards-Anderson (EA) model with binary interactions at a bond occupation of 45% by Monte Carlo (MC) simulations. Using an efficient cluster MC algorithm we are able to determine the universal finite-size scaling (FSS) functions and the critical exponents with high statistical accuracy. We observe small corrections to scaling for the measured observables. The critical quantities and the FSS functions indicate clearly that the bond-diluted model for dilutions above the critical dilution p*, at which a spin glass (SG) phase appears, lies in the same universality class as the 3D undiluted EA model with binary interactions. A comparison with the FSS functions of the 3D site-diluted EA model with Gaussian interactions at a site occupation of 62.5% gives very strong evidence for the universality of the SG transition in the 3D EA model.Comment: Revised version. 10 pages, 9 figures, 2 table

From ²²²Rn measurements in XENONnT and HeXe to radon mitigation in future liquid xenon experiments

While overwhelming evidence has been found for the existence of dark matter in our universe, its true nature remains a mystery. The XENONnT experiment has recently completed its commissioning and is now on the quest to solve this puzzle. This endeavor is threatened by the background caused by the emanation of 222Rn. In this work, a first estimate of the experiment’s radon concentration will be given. Furthermore, the capabilities of the distillation-based radon removal system are demonstrated. For future liquid xenon (LXe) based experiments, the 222Rn-induced background needs to be suppressed even further. A novel radon mitigation technique using surface coatings has been investigated. Very promising reduction factors of more than three orders of magnitude have been achieved with electrochemically plated copper layers, applied to radium implanted stainless steel samples. Additionally, the interactions of alpha particles from 222Rn and electrons from 83mKr have been studied in the Heidelberg Xenon (HeXe) time projection chamber (TPC). Field dependent measurements of the electron drift velocity as well as the charge and light yield are presented. For both, an emphasis was put on the regime of low drift fields, to improve the modeling and reconstruction in future LXe detectors

Energy gaps in quantum first-order mean-field-like transitions: The problems that quantum annealing cannot solve

We study first-order quantum phase transitions in models where the mean-field traitment is exact, and the exponentially fast closure of the energy gap with the system size at the transition. We consider exactly solvable ferromagnetic models, and show that they reduce to the Grover problem in a particular limit. We compute the coefficient in the exponential closure of the gap using an instantonic approach, and discuss the (dire) consequences for quantum annealing.Comment: 6 pages, 3 figure

Strong Einstein-Podolsky-Rosen entanglement from a single squeezed light source

Einstein-Podolsky-Rosen (EPR) entanglement is a criterion that is more demanding than just certifying entanglement. We theoretically and experimentally analyze the low resource generation of bi-partite continuous variable entanglement, as realized by mixing a squeezed mode with a vacuum mode at a balanced beam splitter, i.e. the generation of so-called vacuum-class entanglement. We find that in order to observe EPR entanglement the total optical loss must be smaller than 33.3 %. However, arbitrary strong EPR entanglement is generally possible with this scheme. We realize continuous wave squeezed light at 1550 nm with up to 9.9 dB of non-classical noise reduction, which is the highest value at a telecom wavelength so far. Using two phase controlled balanced homodyne detectors we observe an EPR co-variance product of 0.502 \pm 0.006 < 1, where 1 is the critical value. We discuss the feasibility of strong Gaussian entanglement and its application for quantum key distribution in a short-distance fiber network.Comment: 4 pages, 4 figure

Improving Sustainable Performance of SMEs

"This thesis aims to design and develop a comprehensive SME model and measuring tool and to close the narrowing gap of research concerned with performance optimization in SMEs. This study focuses on the positions of 27 individual SMEs concerning specific issues against their societal, economic and physical context.