DLR’s Dual-Polarized Offset Reflector Antenna with Digital Feed Array for Synthetic Aperture Radar

The German Aerospace Center (DLR) is currently developing a ground-based Synthetic Aperture Radar (SAR) with digital beamforming (DBF) capabilities for versatile scientific use. Primary focus of the project is on the reflector antenna and on the implementation of onboard DBF preprocessing concepts & data reduction in real-time. This paper describes the innovative contributions and challenges during the X-band offset reflector antenna design with 4x32 dual-polarized feed elements at a center frequency of 9.6 GHz

Magnesium Anode Protection by an Organic Artificial Solid Electrolyte Interphase for Magnesium-Sulfur Batteries

In the search for post-lithium battery systems, magnesium–sulfur batteries have attracted research attention in recent years due to their high potential energy density, raw material abundance, and low cost. Despite significant progress, the system still lacks cycling stability mainly associated with the ongoing parasitic reduction of sulfur at the anode surface, resulting in the loss of active materials and passivating surface layer formation on the anode. In addition to sulfur retention approaches on the cathode side, the protection of the reductive anode surface by an artificial solid electrolyte interphase (SEI) represents a promising approach, which contrarily does not impede the sulfur cathode kinetics. In this study, an organic coating approach based on ionomers and polymers is pursued to combine the desired properties of mechanical flexibility and high ionic conductivity while enabling a facile and energy-efficient preparation. Despite exhibiting higher polarization overpotentials in Mg–Mg cells, the charge overpotential in Mg–S cells was decreased by the coated anodes with the initial Coulombic efficiency being significantly increased. Consequently, the discharge capacity after 300 cycles applying an Aquivion/PVDF-coated Mg anode was twice that of a pristine Mg anode, indicating effective polysulfide repulsion from the Mg surface by the artificial SEI. This was backed by operando imaging during long-term OCV revealing a non-colored separator, i.e. mitigated self-discharge. While SEM, AFM, IR and XPS were applied to gain further insights into the surface morphology and composition, scalable coating techniques were investigated in addition to ensure practical relevance. Remarkably therein, the Mg anode preparation and all surface coatings were prepared under ambient conditions, which facilitates future electrode and cell assembly. Overall, this study highlights the important role of Mg anode coatings to improve the electrochemical performance of magnesium–sulfur batteries

Altered EEG spectral power during rest and cognitive performance: a comparison of preterm-born adolescents to adolescents with ADHD

Preterm birth has been associated with an increased risk for ADHD-like behavioural symptoms and cognitive impairments. However, direct comparisons across ADHD and preterm-born samples on neurophysiological measures are limited. The aim of this analysis was to test whether quantitative EEG (QEEG) measures identify differences or similarities in preterm-born adolescents, compared to term-born adolescents with and without ADHD, during resting-state and cognitive task conditions. We directly compared QEEG activity between 186 preterm-born adolescents, 69 term-born adolescents with ADHD and 135 term-born control adolescents during an eyes-open resting-state condition (EO), which previously discriminated between the adolescents with ADHD and controls, and during a cued continuous performance task (CPT-OX). Absolute delta power was the only frequency range to demonstrate a significant group-by-condition interaction. The preterm group, like the ADHD group, displayed significantly higher delta power during EO, compared to the control group. In line with these findings, parent-rated ADHD symptoms in the preterm group were significantly correlated with delta power during rest. While the preterm and control groups did not differ with regard to absolute delta power during CPT-OX, the ADHD group showed significantly higher absolute delta power compared to both groups. Our results provide evidence for overlapping excess in the absolute delta range in preterm-born adolescents and term-born adolescents with ADHD during rest. During CPT-OX, preterm-born adolescents resembled controls. Increased delta power during rest may be a potential general marker of brain trauma, pathology or neurotransmitter disturbances

ADHD Remission is linked to better neurophysiological error detection and attention-vigilance processes

Background: The processes underlying persistence and remission of attention-deficit/hyperactivity disorder (ADHD) are poorly understood. We aimed to examine whether cognitive and neurophysiological impairments on a performance monitoring task distinguish between ADHD persisters and remitters. Methods: On average six years after initial assessment, 110 adolescents and young adults with childhood ADHD (87 persisters, 23 remitters) and 169 age-matched controls were compared on cognitive-performance measures and event-related potentials (ERPs) of conflict monitoring (N2) and error processing (ERN, Pe) from an arrow flanker task with low- and high-conflict conditions. ADHD outcome was examined with parent-reported symptoms and functional impairment measures using a categorical (DSM-IV) and a dimensional approach. Results: ADHD persisters were impaired compared to controls on all cognitive-performance and ERP measures (all p<0.05). ADHD remitters differed from persisters, and were indistinguishable from controls, on the number of congruent (low-conflict) errors, reaction time variability (RTV), ERN and Pe (all p≤0.05). Remitters did not differ significantly from the other groups on incongruent (high-conflict) errors, mean reaction time and N2. In dimensional analyses on all participants with childhood ADHD, ADHD symptoms and functional impairment at follow up were significantly correlated with congruent errors, RTV and Pe (r=0.19-0.23, p≤0.05). Conclusions: Cognitive and neurophysiological measures of attention-vigilance and error detection distinguished ADHD remitters from persisters. These results extend our previous findings with other tasks (Cheung et al. 2015), and indicate that such measures are markers of remission and candidates for the development of non-pharmacological interventions

X/Ka-Band Dual-Polarized Digital Beamforming Synthetic Aperture Radar

This paper presents a digital beamforming (DBF) synthetic aperture radar (SAR) for future spaceborne earth observation systems. The objective of the DBF-SAR system is to achieve a low cost, lightweight, low-power consumption, and dual-band (X/Ka) dual-polarized module for the next-generation spaceborne SAR system in Europe. The architectures and modules of the proposed DBF-SAR system are designed according to a realistic mission scenario, which is compatible with the future small/microsatellites platforms. This system fills an important gap in the conception of the future DBF-SAR, facilitating a high level of integration and complexity reduction. The proposed system is considered not only the first demonstrator of a receive-only spaceborne DBF system, but also the first X/Ka-band dual-polarized SAR system with shared aperture. This paper presents a description of the proposed instrument hardware and first experimental validations. The concept and design of the DBF multistatic SAR system are discussed and presented first, followed by the design of subsystems such as DBF networks, microwave integrated circuit, and antennas. Simulated and measured results of the subsystems are presented, demonstrating that the proposed SAR instrument architecture is well-suited for the future SAR applications

Why it is time to look beyond algal genes in photosynthetic slugs

Eukaryotic organelles depend on nuclear genes to perpetuate their biochemical integrity. This is true for mitochondria in all eukaryotes and plastids in plants and algae. Then how do kleptoplasts, plastids that are sequestered by some sacoglossan sea slugs, survive in the animals' digestive gland cells in the absence of the algal nucleus encoding the vast majority of organellar proteins? For almost two decades, lateral gene transfer (LGT) from algae to slugs appeared to offer a solution, but RNA-seq analysis, later supported by genome sequencing of slug DNA, failed to find any evidence for such LGT events. Yet, isolated reports continue to be published and are readily discussed by the popular press and social media, making the data on LGT and its support for kleptoplast longevity appear controversial. However, when we take a sober look at the methods used, we realize that caution is warranted in how the results are interpreted. There is no evidence that the evolution of kleptoplasty in sea slugs involves LGT events. Based on what we know about photosystem maintenance in embryophyte plastids, we assume kleptoplasts depend on nuclear genes. However, studies have shown that some isolated algal plastids are, by nature, more robust than those of land plants. The evolution of kleptoplasty in green sea slugs involves many promising and unexplored phenomena, but there is no evidence that any of these require the expression of slug genes of algal origin

Der Geologische Dienst in Sachsen: Festband zum Jubiläum 150 Jahre Landesgeologie

Der Geologische Dienst von Sachsen feiert im Jahr 2022 sein 150-jähriges Jubiläum – am 6. April 1872 wurde die Geologische Landesuntersuchung im Königreich Sachsen gegründet. Auf 153 Seiten der Reihe „Geoprofil“ werden Einblicke in die Arbeit des Geologischen Dienstes im LfULG, seinen Aufgaben und die Dienste als zuständige Fachbehörde gegeben. Die elf Einzelbeiträge zeigen die aktuellen Herausforderungen und Chancen, die sich aus den Themenbereichen Umwelt, Naturschutz und Geologie für Sachsen stellen. Im Einzelnen geht es in den Beiträgen um die sächsische Rohstoffstrategie, die Suche nach einem Endlagerstandort für radioaktive Abfälle, Erdwärme, Hydrogeologie, die Eisenbahn Neubaustrecke Dresden – Prag, Naturgefahren, das geowissenschaftliche Archiv, Träger öffentlicher Belange (TöB), Geoparks und einen Blick in die 150 jährige Geschichte. Redaktionsschluss: 30.11.202

The electoral consequences of offshoring: how the globalization of production shapes party preferences

How does offshoring affect individual party preferences in multiparty systems? We argue that exposure to offshoring influences individual preferences for those political parties with clear policy positions on issues relevant for individuals with offshorable jobs (left, liberal, and center-right parties) but does not affect voting decisions for parties concentrating on other issues (green or populist right parties). Examining individual-level data from five waves of the European Social Survey for 18 advanced democracies, we find that these effects vary by skill level and exposure. Offshoring increases preferences for liberal and center-right parties that advocate economic openness among the highly skilled. In contrast, low-skilled individuals exposed to offshoring are more likely to prefer leftist political parties that champion social protection and redistribution. Offshoring does not affect the propensity to vote for green and populist right parties

Detection of Multipath Propagation Effects in SAR-Tomography with MIMO Modes

This paper introduces a Multiple-Input Multiple-Output (MIMO) concept for Synthetic Aperture Radar (SAR) tomography. Basic idea is to localize multipath propagation effects with a combined transmit and receive Digital Beam Forming (DBF) technique. Major part of this paper is attended to the description of a MIMO-radar experiment, conducted for a final proof of concept. For this experiment, a ground-based MIMO-radar was placed on top of a building, while the antenna array was looking downwards to a dihedral scatterer placed on a meadow. In addition, the equivalent phase center of the target was covered with absorbing material to avoid direct reflections. By using an antenna beam configuration, where the transmit and the receive antenna beams are looking to the equivalent phase center of the dihedral scatterer, it was possible to suppress the target. In a repeated processing of the same acquired data set, where each of the antenna beams illuminates one of the two perpendicularly aligned surfaces of the dihedral scatterer, the target appeared in the range compressed data