Nonradiating electromagnetic configurations in nanostructures open new horizons for applications due to two essential features: a lack of energy losses and invisibility to the propagating ...electromagnetic field. Such radiationless configurations form a basis for new types of nanophotonic devices, in which a strong electromagnetic field confinement can be achieved together with lossless interactions between nearby components. In our work, we present a new design of free-standing disk nanoantennas with nonradiating current distributions for the optical near-infrared range. We show a novel approach to creating nanoantennas by slicing III–V nanowires into standing disks using focused ion-beam milling. We experimentally demonstrate the suppression of the far-field radiation and the associated strong enhancement of the second-harmonic generation from the disk nanoantennas. With a theoretical analysis of the electromagnetic field distribution using multipole expansions in both spherical and Cartesian coordinates, we confirm that the demonstrated nonradiating configurations are anapoles. We expect that the presented procedure of designing and producing disk nanoantennas from nanowires becomes one of the standard approaches to fabricating controlled chains of standing nanodisks with different designs and configurations. These chains can be essential building blocks for new types of lasers and sensors with low power consumption.
Glutaredoxins catalyze the reduction of disulfides and are key players in redox metabolism and regulation. While important insights were gained regarding the reduction of glutathione disulfide ...substrates, the mechanism of non-glutathione disulfide reduction remains highly debated. Here we determined the rate constants for the individual redox reactions between PfGrx, a model glutaredoxin from Plasmodium falciparum, and redox-sensitive green fluorescent protein 2 (roGFP2), a model substrate and versatile tool for intracellular redox measurements. We show that the PfGrx-catalyzed oxidation of roGFP2 occurs via a monothiol mechanism and is up to three orders of magnitude faster when roGFP2 and PfGrx are fused. The oxidation kinetics of roGFP2-PfGrx fusion constructs reflect at physiological GSSG concentrations the glutathionylation kinetics of the glutaredoxin moiety, thus allowing intracellular structure-function analysis. Reduction of the roGFP2 disulfide occurs via a monothiol mechanism and involves a ternary complex with GSH and PfGrx. Our study provides the mechanistic basis for understanding roGFP2 redox sensing and challenges previous mechanisms for protein disulfide reduction.
Despite large morphological differences between the nervous systems of lower animals and humans, striking functional similarities have been reported. However, little is known about how these ...functional similarities translate to cognitive similarities. As a first step towards studying the cognitive abilities of simple nervous systems, we here characterize the ongoing electrophysiological activity of the planarian Schmidtea mediterranea. One previous report using invasive microelectrodes describes that the ongoing neural activity is characterized by a 1/f
power spectrum with the exponent 'x' of the power spectrum close to 1. To extend these findings, we aimed to establish a recording protocol to measure ongoing neural activity safely and securely from alive and healthy planarians under different lighting conditions using non-invasive surface electrodes.
As a replication and extension of the previous results, we show that the ongoing neural activity is characterized by a 1/f
power spectrum, that the exponent 'x' in living planarians is close to 1, and that changes in lighting induce changes in neural activity likely due to the planarian photophobia.
We confirm the existence of continuous EEG activity in planarians and show that it is possible to noninvasively record this activity with surface wire electrodes. This opens up broad possibilities for continuous recordings across longer intervals, and repeated recordings from the same animals to study cognitive processes.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
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•The first photoelectron images of water droplets are presented.•Electron mean free path values are derived for liquid water.•Photoelectron imaging of water droplets is complementary ...to liquid microjet studies.•Gradual variation from shadowing to nanofocusing is demonstrated.
Angle-resolved photoelectron spectroscopy of aerosol droplets is a promising method for the determination of electron mean free paths in liquids. It is particularly attractive for volatile liquids, such as water. Here we report the first angle-resolved photoelectron images of droplets with defined sizes, viz. of water, glycerol, and dioctyl phthalate droplets. Simulations of water droplet photoelectron images and data for electron mean free paths for liquid water at low kinetic energy (<3eV) are provided. We present an approach that allows one to gradually vary the conditions from shadowing to nanofocusing to optimize the information content contained in the photoelectron images.
The orientation of microtubule (MT) networks is exploited by motors to deliver cargoes to specific intracellular destinations and is thus essential for cell polarity and function. Reconstituted in ...vitro systems have largely contributed to understanding the molecular framework regulating the behavior of MT filaments. In cells, however, MTs are exposed to various biomechanical forces that might impact on their orientation, but little is known about it. Oocytes, which display forceful cytoplasmic streaming, are excellent model systems to study the impact of motion forces on cytoskeletons in vivo. Here we implement variational optical flow analysis as a new approach to analyze the polarity of MTs in the
oocyte, a cell that displays distinct Kinesin-dependent streaming. After validating the method as robust for describing MT orientation from confocal movies, we find that increasing the speed of flows results in aberrant plus end growth direction. Furthermore, we find that in oocytes where Kinesin is unable to induce cytoplasmic streaming, the growth direction of MT plus ends is also altered. These findings lead us to propose that cytoplasmic streaming - and thus motion by advection - contributes to the correct orientation of MTs in vivo. Finally, we propose a possible mechanism for a specialized cytoplasmic actin network (the actin mesh) to act as a regulator of flow speeds to counteract the recruitment of Kinesin to MTs.
Die Energiekrise zwingt Deutschland und die EU-Staaten energiepolitische Entscheidungen neu zu bewerten und gegebenenfalls anzupassen. Zunächst rückt die Notwendigkeit, die erneuerbaren Energien ...schnell und ambitioniert auszubauen noch stärker in den Fokus. Zudem gibt es einerseits Überlegungen, Kohlekraftwerke aus der Reserve oder der Betriebsbereitschaft zu reaktivieren. Andererseits werden Entscheidungen hinterfragt, Kohle- und Kernkraftwerke in den kommenden Jahren stillzulegen. Diese Kurzstudie analysiert die Auswirkungen dieser Handlungsoptionen in verschiedenen Szenarien für die Jahre 2024 und 2027, um die kurzfristigen Herausforderungen sowie die mittelfristigen Perspektiven zu beleuchten.
The energy crisis is forcing Germany and other EU countries to reconsider and, if necessary, adjust energy policy decisions. New perspectives envisage a rapid expansion of renewable energies in the next few years. In the short term, Germany is considering reactivating coal-fired power plants from the reserve and revising decisions to decommission coal-fired and nuclear power plants in the coming years. This brief study analyses the price effects for the years 2024 and 2027 to shed light on both the short-term challenges and the medium-term prospects.
Kohleausstieg 2030 unter neuen Vorzeichen Egerer, Jonas; Grimm, Veronika; Lang, Lukas M ...
Wirtschaftsdienst (Hamburg),
08/2022, Letnik:
102, Številka:
8
Journal Article
Recenzirano
Odprti dostop
Der russische Angriff auf die Ukraine und die Abhängigkeit der deutschen Energiewirtschaft von russischem Gas führen aktuell zu einer sehr angespannten Versorgungssituation, die sich im kommenden ...Winter noch verschärfen könnte. Auch mittelfristig dürfte der Importpreis für Erdgas deutlich oberhalb der historischen Werte liegen, wenn Europa sich von Russland unabhängig aufstellt. Diese Entwicklungen erfordern eine Neubewertung der deutschen Energiepolitik, unter anderem für die Energiewende im Stromsektor.
The Russian attack on Ukraine and the German energy industry's dependence on Russian gas are currently leading to a very tight supply situation, which could worsen in the coming winter. In the medium term, too, the import price for natural gas is likely to be significantly above historical levels as Europe becomes independent of Russian gas. These developments call for a reassessment of German energy policy, including for the energy transition in the power sector.
Through decarbonization of the world economy a normative imperative to the realization of a post-fossil age emerged. The global ecosystem is threatened by the current world economic model and ...fundamental transformations are asked for in all economic sectors. For two decades now, the automotive industry is undergoing a permanent ambidextrous phase, after having been locked in technological routines for nearly a century. The omni-present electrification of the powertrain together with the technological convergence with connected-car and autonomous-driving technology are the key challenges. To process the pressure, new strategies are designed and implemented. Nevertheless, current studies, based on patent analysis show that classic powertrain technology still represents the dominant design. At the same time, patent analysis shows that competition between firms in the field of electric powertrain technology is fierce. We use patent citation analysis to improve our understanding of the underlying industrial learning processes and of their impacts. To analyze the change in the automotive industry and unveil actors’ strategies, we examine the three most essential differentiating features of an automobile: classic powertrain, electric powertrain and autonomous driving. We aim to analyze these main differentiators along three key questions: the geographic dimension, the positioning in the value chain, and the individual company perspective, by developing a new structuring logic– the ambidexterity matrix – and its dynamic representation along the ambidexterity path.
We propose a variational regularisation approach for the problem of template-based image reconstruction from indirect, noisy measurements as given, for instance, in X-ray computed tomography. An ...image is reconstructed from such measurements by deforming a given template image. The image registration is directly incorporated into the variational regularisation approach in the form of a partial differential equation that models the registration as either mass- or intensity-preserving transport from the template to the unknown reconstruction. We provide theoretical results for the proposed variational regularisation for both cases. In particular, we prove existence of a minimiser, stability with respect to the data, and convergence for vanishing noise when either of the abovementioned equations is imposed and more general distance functions are used. Numerically, we solve the problem by extending existing Lagrangian methods and propose a multilevel approach that is applicable whenever a suitable downsampling procedure for the operator and the measured data can be provided. Finally, we demonstrate the performance of our method for template-based image reconstruction from highly undersampled and noisy Radon transform data. We compare results for mass- and intensity-preserving image registration, various regularisation functionals, and different distance functions. Our results show that very reasonable reconstructions can be obtained when only few measurements are available and demonstrate that the use of a normalised cross correlation-based distance is advantageous when the image intensities between the template and the unknown image differ substantially.
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