Repair and Prepare: Strengthening Europe's Economies after the Crisis. Bertelsmann Studies

Europe is often portrayed as a ship with sails of different colours from different countries pushing the common boat in the right direction. From 2010 to 2012, that ship faced the perfect storm: The euro area almost caused the ship to sink, there was massive disagreement on how to get out of the storm, and it was unclear who was steering the ship. However, Euro-Europe eventually managed to buoy the ship while in the eye of the storm, and the decisive action by ECB President Mario Draghi, arguably not the captain of the ship, managed to steer the common project away from imminent danger

An axon initial segment is required for temporal precision in action potential encoding by neuronal populations

Central neurons initiate action potentials (APs) in the axon initial segment (AIS), a compartment characterized by a high concentration of voltage-dependent ion channels and specialized cytoskeletal anchoring proteins arranged in a regular nanoscale pattern. Although the AIS was a key evolutionary innovation in neurons, the functional benefits it confers are not clear. Using a mutation of the AIS cytoskeletal protein \beta IV-spectrin, we here establish an in vitro model of neurons with a perturbed AIS architecture that retains nanoscale order but loses the ability to maintain a high NaV density. Combining experiments and simulations we show that a high NaV density in the AIS is not required for axonal AP initiation; it is however crucial for a high bandwidth of information encoding and AP timing precision. Our results provide the first experimental demonstration of axonal AP initiation without high axonal channel density and suggest that increasing the bandwidth of the neuronal code and hence the computational efficiency of network function was a major benefit of the evolution of the AIS.Comment: Title adjusted, no other change

photoluminescence of a single quantum emitter in a strongly inhomogeneous chemical environment

A comprehensive photoluminescence study of defect centers in single SiO2 nanoparticles provides new insight into the complex photo-physics of single quantum emitters embedded into a random chemical environment

Metasurface-based total internal reflection microscopy

Recent years have seen a tremendous progress in the development of dielectric metasurfaces for visible light applications. Such metasurfaces are ultra-thin optical devices that can manipulate optical wavefronts in an arbitrary manner. Here, we present a newly developed metasurface which allows for coupling light into a microscopy coverslip to achieve total internal reflection (TIR) excitation. TIR fluorescence microscopy (TIRFM) is an important bioimaging technique used specifically to image cellular membranes or surface-localized molecules with high contrast and low background. Its most commonly used modality is objective-type TIRFM where one couples a focused excitation laser beam at the edge of the back focal aperture of an oil-immersion objective with high numerical aperture (N.A.) to realize a high incident-angle plane wave excitation above the critical TIR angle in sample space. However, this requires bulky and expensive objectives with a limited field-of-view (FOV). The metasurface which we describe here represents a low cost and easy-to-use alternative for TIRFM. It consists of periodic 2D arrays of asymmetric structures fabricated in TiO2 on borosilicate glass. It couples up to 70% of the incident non-reflected light into the first diffraction order at an angle of 65 degrees in glass, which is above the critical TIR angle for a glass-water interface. Only similar to 7% of the light leaks into propagating modes traversing the glass surface, thus minimizing any spurious background fluorescence originating far outside the glass substrate. We describe in detail design and fabrication of the metasurface, and validate is applicability for TIRFM by imaging immunostained human mesenchymal stem cells over a FOV of 200 mu m x 200 mu m. We envision that these kinds of metasurfaces can become a valuable tool for low-cost and TIRFM, offering high contrast, low photodamage, and high surface selectivity in fluorescence excitation and detection. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreemen