Search

The development of effective CO2 sorbents is vital to achieving net-zero CO2 emission targets. MgO promoted with molten salts is an emerging class of CO2 sorbents. However, the structural features that govern their performance remain elusive. Using in situ time-resolved powder x-ray diffraction, we follow the structural dynamics of a model NaNO3-promoted, MgO-based CO2 sorbent. During the first few cycles of CO2 capture and release, the sorbent deactivates owing to an increase in the sizes of the MgO crystallites, reducing in turn the abundance of available nucleation points, i.e., MgO surface defects, for MgCO3 growth. After the third cycle, the sorbent shows a continuous reactivation, which is linked to the in situ formation of Na2Mg(CO3)2 crystallites that act effectively as seeds for MgCO3 nucleation and growth. Na2Mg(CO3)2 forms due to the partial decomposition of NaNO3 during regeneration at T ≥ 450°C followed by carbonation in CO2. ISSN:2375-2548

To advance CaO-based CO2 sorbents it is crucial to understand how their structural parameters control the cyclic CO2 uptake. Here, CaO-based sorbents with varying ratios of Na2CO3:CaCO3 are synthesized via mechanochemical activation of a mixture of Na2CO3 and CaCO3 to investigate the effect of sodium species on the structure, morphology, carbonation rate and cyclic CO2 uptake of the CO2 sorbents. The addition of Na2CO3 in the range of 0.1–0.2 mol% improves the CO2 uptake by up to 80% after 10 cycles when compared to ball-milled bare CaCO3, while for Na2CO3 loadings >0.3 mol% the cyclic CO2 uptake decreases by more than 40%. Energy dispersive X-ray spectroscopy (EDX), transmission electron microscopy, X-ray absorption spectroscopy (XAS), and 23Na MAS NMR, reveal that in sorbents with Na2CO3 contents 100 nm, and enhance the diffusion of CO2 through CaCO3. For Na2CO3 contents >0.3 mol%, the accelerated deactivation of the sorbents via sintering is related to the formation of crystalline Na2Ca(CO3)2 and the high mobility of Na. ISSN:1616-3028 ISSN:1616-301X

In southern Patagonia, fire and domestic herbivory are the main disturbances affecting native forest dynamics. The effects of disturbances such as fire and livestock on the diversity and structure of plant communities depends on the intensity of these disturbances and the characteristics of the stand type. The overall objective of this study was to evaluate changes in forest diversity and structure under varying intensities of fire and livestock disturbances in Nothofagus antarctica forests in three different stand types. Two types of disturbances, fire and cattle, were evaluated at three different intensities; maximum disturbance, medium disturbance and no disturbance in high, medium and low stand types. Ecological and structural parameters were calculated for each experimental unit and their corresponding interactions. Diversity increased for the three stand types at maximum and medium disturbance intensities. Herbaceous cover increased for the three stand types at maximum and medium disturbance intensities. Shrub cover decreased in the high and medium stands due to the disturbances, but not in the lower stands. Understanding the responses of plant communities to fire and domestic livestock disturbances under different intensities and stand types is fundamental to predict the dynamics of native vegetation recovery and to guide sustainable management practices for each stand type., En la Patagonia sur, el fuego y la herbivoría doméstica son los principales disturbios que controlan la dinámica de los bosques nativos. La respuesta de la diversidad y estructura de las comunidades vegetales frente a los disturbios fuego y ganado depende de la intensidad de los mismos y a las características del tipo de rodal que se considere. El objetivo general del trabajo fue evaluar la diversidad y estructura bajo distintas intensidades de disturbios de fuego y ganado en bosques de Nothofagus antarctica (Ñire) en tres tipos de rodales contrastantes. Se evaluaron dos tipos de disturbios: fuego y ganado en tres tipos de áreas: con intensidades máximas de disturbio, con intensidades medias de disturbio, y áreas sin disturbio en tipos de rodales altos, intermedios y bajos. Se calcularon parámetros ecológicos y de estructura para cada unidad experimental y sus correspondientes interacciones. La diversidad aumentó para los tres tipos de rodales a intensidades máximas y media de disturbio. Las herbáceas aumentaron para los tres tipos de rodales a intensidades máximas y media de disturbio. La cobertura de arbustivas disminuyó en los rodales altos e intermedios, por efecto de los disturbios, pero no para los rodales bajos. Comprender la respuesta de la comunidad vegetal al fuego y ganado doméstico bajo distintas intensidades y tipos de rodales es fundamental para predecir la dinámica de recuperación de la vegetación nativa y orientar las prácticas de manejo sustentable para esta especie.

Refugee integration is one of the main global challenges of the present, at a time when the corporate sector is regarded as a key actor in multi-stakeholder partnerships through the 2030 Agenda for Sustainable Development. This paper examines its role as a partner of the state in addressing the movement of refugees into Germany from 2015 onwards. Based on interview data and informal conversations with members of Wir Zusammen, an integration initiative, and supplemented by a review of business reports and media documentation, it discusses the multifaceted engagements by parts of the corporate sector in Germany with refugee integration. These are analysed as ‘thin’ and ‘thick’, and as following different institutional logics. The paper adds to understanding of the political dimensions of corporate responses, their potential to challenge the status quo, and their pitfalls. Ultimately, it argues that corporate involvement with humanitarian and development challenges works best whenembedded locally and is context specific.

Open data for publication "Probing the dynamics of the local structure of Na in NaNO3-promoted, MgO-based CO2 sorbents via X-ray absorption spectroscopy "

We elucidate the underlying cause of a commonly observed increase in the rate of oxygen release of an oxygen carrier with redox cycling (here specifically for the perovskite Sr0.8Ca0.2FeO3-delta) in chemical looping applications. This phenomenon is often referred to as activation. To this end we probe the evolution of the structure and surface elemental composition of the oxygen carrier with redox cycling by both textural and morphological characterization techniques (N-2 physisorption, microscopy, X-ray powder diffraction and X-ray absorption spectroscopy). We observe no appreciable changes in the surface area, pore volume and morphology of the sample during the activation period. X-ray powder diffraction and X-ray absorption spectroscopy analysis (at the Fe and Sr K-edges) of the material before and after redox cycles do not show significant differences, implying that the bulk (average and local) structure of the perovskite is largely unaltered upon cycling. The analysis of the surface of the perovskite via X-ray photoelectron and in situ Raman spectroscopy indicates the presence of surface carbonate species in the as-synthesized sample (due to its exposure to air). Yet, such surface carbonates are absent in the activated material, pointing to the removal of carbonates during cycling (in a CO2-free atmosphere) as the underlying cause behind activation. Importantly, after activation and a re-exposure to CO2, surface carbonates re-form and yield a deactivation of the perovskite oxygen carrier, which is often overlooked when using such materials at relatively low temperature (, Journal of Materials Chemistry A, 11 (12), ISSN:2050-7488, ISSN:2050-7496

The influence of the phase of the ZrO2 support (monoclinic, tetragonal, and amorphous, referred to as m-, t-, and am-, respectively) on the nature of the surface species involved in methanol synthesis and the rates of their formation on ZrO2-supported, In-based catalysts for CO2 hydrogenation has been investigated. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) at 300 degrees C and 20 bar (H-2:CO2:N-2 = 3:1:1 volume ratio) on m-ZrO2:In, In2O3/t-ZrO2, and In2O3/am-ZrO2 catalysts (m-ZrO2:In is a solid solution) shows that formate species (HCOO*) appear prior to methoxy species (*OCH3), and both intermediates form faster on the more active m- ZrO2:In catalyst. Only formate bands are detected for the In2O3/t-ZrO2 catalyst. For these materials, indium sites are essential for the formation of HCOO* and *OCH3 species as only carbonate species are observed on m-, t-, and am-ZrO2 supports under CO2 hydrogenation conditions. The nature of the reaction intermediates is confirmed by ex situ solid-state nuclear magnetic resonance (NMR), where both methoxy and formate species are detected in m-ZrO2:In and In2O3/am-ZrO2, respectively, but only a weak formate peak is observed for In2O3/t-ZrO2. The presence of a major methoxy peak and only a very minor formate signal in unsupported In2O3 indicates that an india-zirconia interface is required for the effective stabilization of formate species. Catalytic tests in a fixed bed reactor are consistent with both CO and Me0H being primary products of CO2 hydrogenation; the tests also show that the methanol selectivity and space time yield decrease in the following order: m-ZrO2:In > In2O3/t-ZrO2 > In2O3/am-ZrO2 for all of the contact times tested. ISSN:1932-7455 ISSN:1932-7447

Linear computation coding is concerned with the compression of multidimensional linear functions, i.e. with reducing the computational effort of multiplying an arbitrary vector to an arbitrary, but known, constant matrix. This paper advances over the state-of-the art, that is based on a discrete matching pursuit (DMP) algorithm, by a step-wise optimal search. Offering significant performance gains over DMP, it is however computationally infeasible for large matrices and high accuracy. Therefore, a reduced-state algorithm is introduced that offers performance superior to DMP, while still being computationally feasible even for large matrices. Depending on the matrix size, the performance gain over DMP is on the order of at least 10%., Comment: Accepted as paper for presentation at Data Compression Conference (DCC) 2023, Snowbird, UT. 10 pages, 4 figures

In our HELIPORT workshop, we provided insights into our project and share our results. In addition, we would like to provide a platform for the presentation of similar projects, as well as extensions or integrations from the surrounding research areas. The overall goal of the workshop is bringing together different institutions with similar challenges and establishing a community around our HELIPORT project. We therefore encouraged our community to submit an abstract for a talk or poster. The submissions are dedicated to four thematic points: • HELIPORTuse-cases, • Scientificprojectandmetadatamanagement, • Experiment-specificandoverallmetadataand • Scientificworkflows. HELIPORT (Helmholtz ScIentific Project WORkflow PlaTform) itself is a project funded by the Helmholtz Metadata Collaboration, and runs from July 2021 until June 2023. HELIPORT aims to make the entire life cycle of a scientific project findable, accessible, interoperable and reusable according to the FAIR principles. In particular, our data management solution deals with the areas from the generation of the data to the publication of primary research data, the workflows carried out and the actual research results. For this purpose, a concept was developed which shows the various essential components and their connections.

International audience; Not available.

The development of effective CO2 sorbents is vital to achieving net-zero CO2 emission targets. MgO promoted with molten salts is an emerging class of CO2 sorbents. However, the structural features that govern their performance remain elusive. Using in situ time-resolved powder x-ray diffraction, we follow the structural dynamics of a model NaNO3-promoted, MgO-based CO2 sorbent. During the first few cycles of CO2 capture and release, the sorbent deactivates owing to an increase in the sizes of the MgO crystallites, reducing in turn the abundance of available nucleation points, i.e., MgO surface defects, for MgCO3 growth. After the third cycle, the sorbent shows a continuous reactivation, which is linked to the in situ formation of Na2Mg(CO3)2 crystallites that act effectively as seeds for MgCO3 nucleation and growth. Na2Mg(CO3)2 forms due to the partial decomposition of NaNO3 during regeneration at T ≥ 450°C followed by carbonation in CO2., Science Advances, 9 (26), ISSN:2375-2548

Classical antenna selection schemes require instantaneous channel state information (CSI). This leads to high signaling overhead in the system. This work proposes a novel joint receive antenna selection and precoding scheme for multiuser multiple-input multiple-output uplink transmission that relies only on the long-term statistics of the CSI. The proposed scheme designs the switching network and the uplink precoders, such that the expected throughput of the system in the long term is maximized. Invoking results from the random matrix theory, we derive a closed-form expression for the expected throughput of the system. We then develop a tractable iterative algorithm to tackle the throughput maximization problem, capitalizing on the alternating optimization and majorization-maximization (MM) techniques. Numerical results substantiate the efficiency of the proposed approach and its superior performance as compared with the baseline., 6 pages

MgO-based CO2 sorbents promoted with molten alkali metal nitrates (e.g., NaNO3) have emerged as promising materials for CO2 capture and storage technologies due to their low cost and high theoretical CO2 uptake capacities. Yet, the mechanism by which molten alkali metal nitrates promote the carbonation of MgO (CO2 capture reaction) remains debated and poorly understood. Here, we utilize O-18 isotope labeling experiments to provide new insights into the carbonation mechanism of NaNO3-promoted MgO sorbents, a system in which the promoter is molten under operation conditions and hence inherently challenging to characterize. To conduct the O-18 isotope labeling experiments, we report a facile and large-scale synthesis procedure to obtain labeled MgO with a high O-18 isotope content. We use Raman spectroscopy and in situ thermogravimetric analysis in combination with mass spectrometry to track the O-18 label in the solid (MgCO3), molten (NaNO3), and gas (CO2) phases during the CO2 capture (carbonation) and regeneration (decarbonation) reactions. We discovered a rapid oxygen exchange between CO2 and MgO through the reversible formation of surface carbonates, independent of the presence of the promoter NaNO3. On the other hand, no oxygen exchange was observed between NaNO3 and CO2 or NaNO3 and MgO. Combining the results of the O-18 labeling experiments, with insights gained from atomistic calculations, we propose a carbonation mechanism that, in the first stage, proceeds through a fast, surface-limited carbonation of MgO. These surface carbonates are subsequently dissolved as [Mg2+center dot center dot center dot CO32-] ionic pairs in the molten NaNO3 promoter. Upon reaching the solubility limit, MgCO3 crystallizes at the MgO/NaNO3 interface., JACS Au, 2 (12), ISSN:2691-3704

This manuscript goes through the fundamental connections between statistical mechanics and estimation theory by focusing on the particular problem of compressive sensing. We first show that the asymptotic analysis of a sparse recovery algorithm is mathematically equivalent to the problem of calculating the free energy of a spin glass in the thermodynamic limit. We then use the replica method from statistical mechanics to evaluate the performance in the asymptotic regime. The asymptotic results have several applications in communications and signal processing. We briefly go through two instances of these applications: Characterization of joint sparse recovery algorithms used in distributed compressive sensing, and tuning of receivers employed for detection of spatially modulated signals., "A Comprehensive Introduction to the Applications of the Replica Method in Analysis of Large Inference Problems". Initial version of the contribution to the book "Compressed Sensing in Information Processing''; 32 pages, 2 figures

Ammonium hydrosulphide has long since been postulated to exist at least in certain layers of the giant planets. Its radiation products may be the reason for the red colour seen on Jupiter. Several ammonium salts, the products of NH3 and an acid, have previously been detected at comet 67P/Churyumov-Gerasimenko. The acid H2S is the fifth most abundant molecule in the coma of 67P followed by NH3. In order to look for the salt NH4+SH-, we analysed in situ measurements from the Rosetta/ROSINA Double Focusing Mass Spectrometer during the Rosetta mission. NH3 and H2S appear to be independent of each other when sublimating directly from the nucleus. However, we observe a strong correlation between the two species during dust impacts, clearly pointing to the salt. We find that NH4+SH- is by far the most abundant salt, more abundant in the dust impacts than even water. We also find all previously detected ammonium salts and for the first time ammonium fluoride. The amount of ammonia and acids balance each other, confirming that ammonia is mostly in the form of salt embedded into dust grains. Allotropes S2 and S3 are strongly enhanced in the impacts, while H2S2 and its fragment HS2 are not detected, which is most probably the result of radiolysis of NH4+SH-. This makes a prestellar origin of the salt likely. Our findings may explain the apparent depletion of nitrogen in comets and maybe help to solve the riddle of the missing sulphur in star forming regions., accepted by MNRAS

The ability to tailor the properties of metal centers in single-atom heterogeneous catalysts depends on the availability of advanced approaches for characterization of their structure. Except for specific host materials with well-defined metal adsorption sites, determining the local atomic environment remains a crucial challenge, often relying heavily on simulations. This article reports an advanced analysis of platinum atoms stabilized on poly(triazine imide), a nanocrystalline form of carbon nitride. The approach discriminates the distribution of surface coordination sites in the host, the evolution of metal coordination at different stages during the synthesis of the material, and the potential locations of metal atoms within the lattice. Consistent with density functional theory predictions, simultaneous high-resolution imaging in high-angle annular dark field and bright field modes experimentally confirms the preferred localization of platinum in-plane in the corners of the triangular cavities. X-ray absorption spectroscopy (XAS), X-ray photoelectron spectroscopy (XPS), and dynamic nuclear polarization enhanced N-15 nuclear magnetic resonance (DNP-NMR) spectroscopies coupled with density functional theory (DFT) simulations reveal that the predominant metal species comprise Pt(II) bound to three nitrogen atoms and one chlorine atom inside the coordination sites. The findings, which narrow the gap between experimental and theoretical elucidation, contribute to the improved structural understanding and provide a benchmark for exploring the speciation of single-atom catalysts based on carbon nitrides., Small, 18 (33), ISSN:1613-6810, ISSN:1613-6829

The thermal carburization of MoO3 nanobelts (nb) and SiO2-supported MoO3 nanosheets under a 1 : 4 mixture of CH4 : H-2 yields Mo2C-nb and Mo2C/SiO2. Following this process by in situ Mo K-edge X-ray absorption spectroscopy (XAS) reveals different carburization pathways for unsupported and supported MoO3. In particular, the carburization of alpha-MoO3-nb proceeds via MoO2, and that of MoO3/SiO(2)via the formation of highly dispersed MoOx species. Both Mo2C-nb and Mo2C/SiO2 catalyze the dry reforming of methane (DRM, 800 degrees C, 8 bar) but their catalytic stability differs. Mo2C-nb shows a stable performance when using a CH4-rich feed (CH4 : CO2 = 4 : 2), however deactivation due to the formation of MoO2 occurs for higher CO2 concentrations (CH4 : CO2 = 4 : 3). In contrast, Mo2C/SiO2 is notably more stable than Mo2C-nb under the CH4 : CO2 = 4 : 3 feed. The influence of the morphology of Mo2C and its dispersion on silica on the structural evolution of the catalysts under DRM is further studied by in situ Mo K-edge XAS. It is found that Mo2C/SiO2 features a higher resistance to oxidation under DRM than the highly crystalline unsupported Mo2C-nb and this correlates with an improved catalytic stability. Lastly, the oxidation of Mo in both Mo2C-nb and Mo2C/SiO2 under DRM conditions in the in situ XAS experiments leads to an increased activity of the competing reverse water gas shift reaction., Catalysis Science & Technology, 12 (18), ISSN:2044-4753, ISSN:2044-4761

Fingering instabilities akin to the Rayleigh-Taylor (RT) instability in fluids have been observed in a binary granular system consisting of dense and small particles layered on top of lighter and larger particles, when the system is subjected to vertical vibration and fluidizing gas flow. Using observations from experiments and numerical modelling we explore whether the theory developed to describe the Rayleigh-Taylor (RT) instability in fluids is also applicable to binary granular systems. Our results confirm the applicability of the classic RT instability theory for binary granular systems demonstrating that several key features are observed in both types of systems, viz: (i) The characteristic wavenumber of the instability is constant with time, (ii) the amplitude of the characteristic wavenumber initially grows exponentially and (iii) the dispersion relation between the wavenumbers k of the interface instability and the growth rates n(k) of their amplitudes holds in both fluid-fluid and binary granular systems. Our results also demonstrate that inter-particle friction is essential for the RT instability to occur in granular media. For zero particle friction the interface instability bears a greater resembles to the Richtmyer-Meshkov instability. We further define a yield criterion Y for the interface by treating the granular medium as a viscoplastic material; only for Y > 15 fingering occurs. Interestingly, previous work has shown that instabilities in the Earth's lower mantle, another viscoplastic material, also occur for similar values of Y., 13 pages, 14 figures (including appendices)

This work extends the concept of channel hardening to multi-antenna systems that are aided by intelligent reflecting surfaces (IRSs). For fading links between a multi-antenna transmitter and a single-antenna receiver, we derive an accurate approximation for the distribution of the input-output mutual information when the number of reflecting elements grows large. The asymptotic results demonstrate that by increasing the number of elements on the IRS, the end-to-end channel hardens as long as the physical dimensions of the IRS grow as well. The growth rate however need not to be of a specific order and can be significantly sub-linear. The validity of the analytical result is confirmed by numerical experiments., Accepted for presentation at 2022 IEEE Sensor Array and Multichannel Signal Processing Workshop (SAM ) in Trondheim, Norway; 5 pages and 2 figures. arXiv admin note: text overlap with arXiv:2203.11592

This paper develops a class of low-complexity device scheduling algorithms for over-the-air federated learning via the method of matching pursuit. The proposed scheme tracks closely the close-to-optimal performance achieved by difference-of-convex programming, and outperforms significantly the well-known benchmark algorithms based on convex relaxation. Compared to the state-of-the-art, the proposed scheme poses a drastically lower computational load on the system: For $K$ devices and $N$ antennas at the parameter server, the benchmark complexity scales with $\left(N^2+K\right)^3 + N^6$ while the complexity of the proposed scheme scales with $K^p N^q$ for some $0 < p,q \leq 2$. The efficiency of the proposed scheme is confirmed via numerical experiments on the CIFAR-10 dataset., 47 Pages and 10 Figures

Thrombocyte formation from megakaryocyte and their progenitor cells is tightly regulated by thrombopoietin (TPO) and its receptor c‐MPL, thereby maintaining physiological functionality and numbers of circulating platelets. In patients, dysfunction of this regulation could cause thrombocytopenia or myeloproliferative syndromes. Since regulation of this pathway is still not completely understood, we investigated the role of the ubiquitin ligase c‐Cbl which was previously shown to negatively regulated c‐MPL signalling. We developed a new conditional mouse model using c‐Cblfl/flPf4Cre mice and demonstrated that platelet‐specific knockout of c‐Cbl led to severe microthrombocytosis and impaired uptake of TPO and c‐MPL receptor internalization. Furthermore, we characterized a constitutive STAT5 activation c‐Cbl KO platelets. This study identified c‐Cbl as a potential player in causing megakaryocytic and thrombocytic disorders.

Summary Dendritic cells (DCs) are sentinels of the immune system that bridge innate and adaptive immunity. By capturing antigens in peripheral tissue, processing and presenting them with concurrent expression of co‐stimulatory molecules and cytokine secretion they control and modulate immune reactions. Through pattern recognition receptors, DCs sense molecules that are associated with infection or tissue damage, frequently resulting in the formation of inflammasomes upon intracellular stimulation. The inherited autoinflammatory familial Mediterranean fever (FMF) is associated with deregulated activity of the pyrin inflammasome leading to acute inflammatory episodes. However, differentiation and function of DCs in this disease are as yet unclear. Therefore, we first determined DC subpopulation frequency in peripheral blood of a cohort of FMF patients. Joint evaluation without classification according to specific patient characteristics, such as mutational status, did not disclose significant differences compared to healthy controls. For the further examination of phenotype and function, we used immature and mature monocyte‐derived DCs (imMo‐DCs, mMo‐DCs) that were generated in vitro from FMF patients. Immunophenotypical analysis of imMo‐DCs revealed a significantly elevated expression of CD83, CD86 and human leukocyte antigen D‐related (HLA‐DR) as well as a significant down‐regulation of CD206, CD209 and glycoprotein NMB (GPNMB) in our FMF patient group. Furthermore, FMF imMo‐DCs presented a significantly higher capacity to migrate and to stimulate the proliferation of unmatched allogeneic T cells. Finally, the transition towards a more mature, and therefore activated, phenotype was additionally reinforced by the fact that peripheral blood DC populations in FMF patients exhibited significantly increased expression of the co‐stimulatory molecule CD86., Analysis of monocyte‐derived DCs from patients with familial Mediterranean fever (FMF) revealed a significantly increased expression of the maturation marker CD83, the costimulatory molecule CD86 as well as HLA‐DR.In contrast, the mannose receptor CD206, CD209 (DC‐SIGN) and the coinhibitory molecule GPNMB were significantly downregulated. These findings indicate that DCs of FMF patients display a transition towards a more mature, and therefore, activated phenotype.

A sustainable hybrid aerogel based on β-lactoglobulin amyloid fibril/UiO-66-NH2 is developed for environmental remediation. The hybrid aerogel's CO2 capture and water purification performances were investigated. The hybrid aerogel can achieve CO2 capture and possesses excellent adsorption capacities for several heavy metals, dyes, and organic solvents., Chemical Communications, 58 (33), ISSN:1359-7345, ISSN:1364-548X

Unlike the classical linear model, nonlinear generative models have been addressed sparsely in the literature of statistical learning. This work aims to bringing attention to these models and their secrecy potential. To this end, we invoke the replica method to derive the asymptotic normalized cross entropy in an inverse probability problem whose generative model is described by a Gaussian random field with a generic covariance function. Our derivations further demonstrate the asymptotic statistical decoupling of the Bayesian estimator and specify the decoupled setting for a given nonlinear model. The replica solution depicts that strictly nonlinear models establish an all-or-nothing phase transition: There exists a critical load at which the optimal Bayesian inference changes from perfect to an uncorrelated learning. Based on this finding, we design a new secure coding scheme which achieves the secrecy capacity of the wiretap channel. This interesting result implies that strictly nonlinear generative models are perfectly secured without any secure coding. We justify this latter statement through the analysis of an illustrative model for perfectly secure and reliable inference., 72 pages, 14 figures

The influence of the phase of the ZrO2 support (monoclinic, tetragonal, and amorphous, referred to as m-, t-, and am-, respectively) on the nature of the surface species involved in methanol synthesis and the rates of their formation on ZrO2-supported, In-based catalysts for CO2 hydrogenation has been investigated. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) at 300 degrees C and 20 bar (H-2:CO2:N-2 = 3:1:1 volume ratio) on m-ZrO2:In, In2O3/t-ZrO2, and In2O3/am-ZrO2 catalysts (m-ZrO2:In is a solid solution) shows that formate species (HCOO*) appear prior to methoxy species (*OCH3), and both intermediates form faster on the more active m- ZrO2:In catalyst. Only formate bands are detected for the In2O3/t-ZrO2 catalyst. For these materials, indium sites are essential for the formation of HCOO* and *OCH3 species as only carbonate species are observed on m-, t-, and am-ZrO2 supports under CO2 hydrogenation conditions. The nature of the reaction intermediates is confirmed by ex situ solid-state nuclear magnetic resonance (NMR), where both methoxy and formate species are detected in m-ZrO2:In and In2O3/am-ZrO2, respectively, but only a weak formate peak is observed for In2O3/t-ZrO2. The presence of a major methoxy peak and only a very minor formate signal in unsupported In2O3 indicates that an india-zirconia interface is required for the effective stabilization of formate species. Catalytic tests in a fixed bed reactor are consistent with both CO and Me0H being primary products of CO2 hydrogenation; the tests also show that the methanol selectivity and space time yield decrease in the following order: m-ZrO2:In > In2O3/t-ZrO2 > In2O3/am-ZrO2 for all of the contact times tested., The Journal of Physical Chemistry C, 136 (4), ISSN:1932-7455, ISSN:1932-7447

MgO is a promising solid oxide-based sorbent to capture anthropogenic CO2 emissions due to its high theoretical gravimetric CO2 uptake and its abundance. When MgO is coated with alkali metal salts such as LiNO3, NaNO3, KNO3, or their mixtures, the kinetics of the CO2 uptake reaction is significantly faster resulting in a 15 times higher CO2 uptake compared to bare MgO. However, the underlying mechanism that leads to this dramatic increase in the carbonation rate is still unclear. This study aims to determine the most favourable location for the nucleation and growth of MgCO3 and more specifically, whether the carbonation occurs preferentially at the buried interface, the triple phase boundary (TPB), and/or inside the molten salt of the NaNO3-MgO system. For this purpose, a model system consisting of a MgO single crystal that is structured by ultra-short pulse laser ablation and coated with NaNO3 as the promoter is used. To identify the location of nucleation and growth of MgCO3, micro X-ray computed tomography, scanning electron microscopy, Raman microspectroscopy and optical profilometry were applied. We found that MgCO3 forms at the NaNO3/MgO interface and not inside the melt. Moreover, there was no preferential nucleation of MgCO3 at the TPB when compared to the buried interface. Furthermore, it is found that there is no observable CO2 diffusion limitation in the nucleation step. However, it was observed that CO2 diffusion limits MgCO3 crystal growth, i.e. the growth rate of MgCO3 is approximately an order of magnitude faster in shallow grooves compared to that in deep grooves., Journal of Materials Chemistry A, 10 (32), ISSN:2050-7488, ISSN:2050-7496

Since the introduction of massive MIMO (mMIMO), the design of a transceiver with feasible complexity has been a challenging problem. Initially, it was believed that the main issue in this respect is the overall RF-cost. However, as mMIMO is becoming more and more a key technology for future wireless networks, it is realized, that the RF-cost is only one of many implementational challenges and design trade-offs. In this paper, we present, analyze and compare various novel mMIMO architectures, considering recent emerging technologies such as intelligent surface-assisted and Rotman lens based architectures. These are compared to the conventional fully digital (FD) and hybrid analog-digital beamforming (HADB) approaches. To enable a fair comparison, we account for various hardware imperfections and losses and utilize a novel, universal algorithm for signal precoding. Based on our thorough investigations, we draw a generic efficiency to quality trade-off for various mMIMO architectures. We find that in a typical cellular communication setting the reflect/transmit array based architectures sketch the best overall trade-off. Further, we show that in a qualitative ranking the power efficiency of the considered architectures is independent of the frequency range., Comment: 11 pages, 3 tables, 3 figures

This work studies a low-complexity design for reconfigurable intelligent surface (RIS)-aided multiuser multiple-input multiple-output systems. The base station (BS) applies receive antenna selection to connect a subset of its antennas to the available radio frequency chains. For this setting, the BS switching network, uplink precoders, and RIS phase-shifts are jointly designed, such that the uplink sum-rate is maximized. The principle design problem reduces to an NP-hard mixed-integer optimization. We hence invoke the weighted minimum mean squared error technique and the penalty dual decomposition method to develop a tractable iterative algorithm that approximates the optimal design effectively. Our numerical investigations verify the efficiency of the proposed algorithm and its superior performance as compared with the benchmark., Comment: 6 pages

The catalytic hydrogenation of CO2 to methanol depends significantly on the structures of metal-oxide interfaces. We show that doping a high-valency metal, viz. tungsten, to CeO2 could render improved catalytic activity for the hydrogenation of CO2 on a Cu/CeW0.25Ox catalyst, whilst making it more selective towards methanol than the undoped Cu/CeO2. We experimentally investigated and elucidated the structural-functional relationship of the Cu/CeO2 interface for CO2 hydrogenation. The promotional effects are attributed to the irreversible reduction of Ce4+ to Ce3+ by W-doping, the suppression of the formation of redox-active oxygen vacancies on CeO2, and the activation of the formate pathway for CO2 hydrogenation. This catalyst design strategy differs fundamentally from those commonly used for CeO2-supported catalysts, in which oxygen vacancies with high redox activity are considered desirable. Ministry of Education (MOE) National Research Foundation (NRF) Submitted/Accepted version This research is funded by the National Research Foundation (NRF), Prime Minister’s Office, Singapore under its Campus for Research Excellence and Technological Enterprise (CREATE) programme and Ministry of Education, Singapore under its AcRF Tier 1 (RT03/19).

Unlike active array antennas, intelligent reflecting surfaces (IRSs) are efficiently implemented at large dimensions. This allows for traceable realizations of large-scale IRS-aided MIMO systems in which not necessarily the array antennas, but the passive IRSs are large. It is widely believed that large IRS-aided MIMO settings maintain the fundamental features of massive MIMO systems, and hence they are the implementationally feasible technology for establishing the performance of large-scale MIMO settings. This work gives a rigorous proof to this belief. We show that using a large passive IRS, the end-to-end MIMO channel between the transmitter and the receiver always hardens, even if the IRS elements are strongly correlated. For the fading direct and reflection links between the transmitter and the receiver, our derivations demonstrate that as the number of IRS elements grows large, the capacity of end-to-end channel converges in distribution to a real-valued Gaussian random variable whose variance goes to zero. The order of this drop depends on how the physical dimensions of the IRS grow. We derive this order explicitly. Numerical experiments depict that the analytical asymptotic distribution almost perfectly matches the histogram of the capacity, even in practical scenarios. As a sample application of the results, we use the asymptotic characterization to study the dimensional trade-off between the transmitter and the IRS. The result is intuitive: For a given target performance, the larger the IRS is, the less transmit antennas are required to achieve the target. For an arbitrary ergodic and outage performance, we characterize this trade-off analytically. Our investigations demonstrate that using a practical IRS size, the target performance can be achieved with significantly small end-to-end MIMO dimensions., Comment: 17 pages, 11 figures

MgO-based materials possess favorable thermodynamic properties that enable them to be used as CO2 sorbents in the temperature range of 300–550 °C — at least theoretically. MgO-based sorbents have seen a boost in activity since the discovery of molten alkali metal salt promoters, and yet, they practically remove CO2 from a gas stream efficiently only at very high pressures (p > 10 bar), rendering them suitable for precombustion, but not for postcombustion CO2 capture schemes. Most of the current performance assessments rely on measurements of the transition between MgO and MgCO3 (or Mg-double carbonates) rather than the ability of the sorbents to actually remove CO2 from a gas stream, which may be misleading regarding their practical use and application. Further, reliable thermodynamic data for sorbents involving Mg-double carbonates is missing, although these materials have large potential for industrial CO2 capture applications., Current Opinion in Green and Sustainable Chemistry, 36

Application of the ALD of TMA onto dehydroxylated silica allows the precise control of the abundance of strong BAS on the support. The abundance of strong BAS is found to correlate directly with the ETP activity of Ni(II) single sites supported on such ALD-prepared silica-aluminates., Online Abstracts: 27th North American Catalysis Society Meeting

Here, we present a detailed structure-performance analysis of Ni-Ga/SiO2 catalysts under CO2 hydrogenation conditions using operando X-ray absorption spectroscopy and X-ray total scattering. The use of these complementary techniques is key to characterize the structure of the active phases in the Ni-Ga system across the electronic, atomic and nanoscale., Online Abstracts: 27th North American Catalysis Society Meeting

Hintergrund und Stand (inter)nationaler Forschung: Viele Pflegeeinrichtungen in Deutschland halten demenzspezifische Wohnbereiche mit unterschiedlichen Konzepten vor. Der Einfluss des Kontextes eines Wohnbereichs in Studien der Versorgungsforschung ist bislang weitestgehend unerforscht. Daher ist es [zum vollständigen Text gelangen Sie über die oben angegebene URL]

The addition of molten alkali metal salts drastically accelerates the kinetics of CO2 capture by MgO through the formation of MgCO3. However, the growth mechanism, the nature of MgCO3 formation, and the exact role of the molten alkali metal salts on the CO2 capture process remain elusive, holding back the development of more-effectiveMgO-based CO2 sorbents. Here, we unveil the growth mechanism of MgCO3 under practically relevant conditions using a well-defined, yet representative, model system that is a MgO(100) single crystal coated with NaNO3. The model system is interrogated by in situ X-ray reflectometry coupled with grazing incidence X-ray diffraction, scanning electron microscopy, and high-resolution transmission electron microscopy. When bare MgO(100) is exposed to a flow of CO2, a noncrystalline surface carbonate layer of ca. 7-Å thickness forms. In contrast, when MgO(100) is coated with NaNO3, MgCO3 crystals nucleate and grow. These crystals have a preferential orientation with respect to the MgO(100) substrate, and form at the interface between MgO(100) and the molten NaNO3. MgCO3 grows epitaxially with respect to MgO(100), and the lattice mismatch between MgCO3 and MgO is relaxed through lattice misfit dislocations. Pyramid-shaped pits on the surface ofMgO, in proximity to and below the MgCO3 crystals, point to the etching of surface MgO, providing dissolved [Mg2+ O2-] ionic pairs forMgCO3 growth. Our studies highlight the importance of combining X-rays and electron microscopy techniques to provide atomic to micrometer scale insight into the changes occurring at complex interfaces under reactive conditions., Proceedings of the National Academy of Sciences of the United States of America, 118 (26), ISSN:0027-8424, ISSN:1091-6490

Deep learning approaches to anomaly detection (AD) have recently improved the state of the art in detection performance on complex data sets, such as large collections of images or text. These results have sparked a renewed interest in the AD problem and led to the introduction of a great variety of new methods. With the emergence of numerous such methods, including approaches based on generative models, one-class classification, and reconstruction, there is a growing need to bring methods of this field into a systematic and unified perspective. In this review, we aim to identify the common underlying principles and the assumptions that are often made implicitly by various methods. In particular, we draw connections between classic ""shallow"" and novel deep approaches and show how this relation might cross-fertilize or extend both directions. We further provide an empirical assessment of major existing methods that are enriched by the use of recent explainability techniques and present specific worked-through examples together with practical advice. Finally, we outline critical open challenges and identify specific paths for future research in AD.

Objects released into a granular packing close to incipient fluidization may float or sink depending on their density. Contrary to intuition, Oshitani et al. [Phys. Rev. Lett. 116, 068001 (2016)10.1103/PhysRevLett.116.068001] reported that under certain conditions, a lighter sphere can sink further and slower than a heavier one. While this phenomenon has been attributed to a local fluidization around the sinking sphere, its physical mechanisms have not yet been understood. Here, we studied this intriguing phenomenon using both magnetic resonance imaging and discrete particle simulation. Our findings suggest that local fluidization around the sinking sphere and the formation and detachment of gas bubbles play a critical role in driving this anomaly. An analysis of forces acting on the intruder revealed that the upward-directed fluid force acting on a sphere is almost fully counterbalanced by the sum of the net contact forces and the gravitational force acting downward, when the sphere density is close to the bulk density of the granular packing (ρsphere/ρbulk≈1). At the time when bubbles detach from the sphere, the gas pressure gradient experienced by the sphere is slightly attenuated and the sphere is pushed downward by the particle cap located on top of the sphere. Because the deviations from the force equilibrium are small, the sphere sinks slowly. Even after the sphere has reached its final stable depth, local fluidization in combination with bubble formation remains in the proximity of the sphere., Physical Review Fluids, 6 (6), ISSN:2469-990X

Titanium dioxide (TiO2) (nano)particles are produced in large quantities and their potential impacts on ecosystems warrants investigations into their fate after disposal. TiO2 particles released into wastewater are retained by wastewater treatment plants and accumulate in digested sludge, which is increasingly incinerated in industrialized countries. Therefore, we investigated the changes of the Ti-speciation during incineration of as-received sludge and of sludge spiked with anatase (d=20–50 nm) or rutile (d=200–400 nm) using X-ray absorption spectroscopy (XAS) and transmission electron microscopy (TEM). In the as-received sludge, rutile and anatase were the dominant Ti bearing minerals and both remained unaffected by the anaerobic treatment. During incineration, Ti reacts with hematite to members of the hematite-ilmenite solid solution series (Hem-Ilm). Up to 80% of the Ti spiked as anatase transformed into Hem-Ilm, a distorted 6-fold coordinated Ti (Ti(IV)sulfate) and rutile during incineration. Up to 30% and 60% of rutile transformed into Hem-Ilm and Ti(IV)sulfate represented phases in fly and bottom ash, respectively. Fe and Ti were spatially correlated in ash derived from as-received and anatase spiked sludge, whereas only a thin layer of the spiked rutile reacted with Fe, in line with XAS data. This study highlights the transient nature of nano-Ti species during sewage sludge incineration., Journal of Hazardous Materials, 411, ISSN:0304-3894, ISSN:1873-3336

The KM3NeT Collaboration is constructing two deep-sea Cherenkov detectors in the Mediterranean Sea, aiming at neutrino oscillation measurements with the ORCA array, while the ARCA array aims at neutrino astronomy in the TeV range. In April 2021, 5 additional detection units were deployed in the ARCA site. The KM3NeT/ARCA instrumented volume is currently similar to the one of the ANTARES neutrino telescope. In this contribution, an analysis of the data obtained with the detector before April 2021 is presented as well as the analysis of the very first data from the new KM3NeT/ARCA configuration. The performance is demonstrated using atmospheric muons and the first atmospheric neutrinos are shown. Article signat per 297 autors/es: M.Ageron, S. Aiello, A. Albert, M. Alshamsi, S. Alves Garre, Z. Aly, A. Ambrosone, F. Ameli, M. Andre, G. Androulakis, M. Anghinolfi, M. Anguita, G. Anton, M. Ardid, S. Ardid, W. Assal, J. Aublin, C. Bagatelas, B. Baret, S. Basegmez du Pree, M. Bendahman, F. Benfenati, E. Berbee, A. M. van den Berg, V. Bertin, S. Beurthey, V. van Beveren, S. Biagi, M. Billault, M. Bissinger, M. Boettcher, M. Bou Cabo, J. Boumaaza, M. Bouta, C. Boutonnet, G. Bouvet, M. Bouwhuis, C. Bozza, H.Brânzas, R. Bruijn, J. Brunner, R. Bruno, E. Buis, R. Buompane, J. Busto, B. Caiffi, L. Caillat, D. Calvo, S. Campion, A. Capone, H. Carduner, V. Carretero, P. Castaldi, S. Celli;, R. Cereseto, M. Chabab, C. Champion, N. Chau, A. Chen, S. Cherubini, V. Chiarella, T. Chiarusi, M. Circella, R. Cocimano, J. A. B. Coelho, A. Coleiro, M. Colomer Molla, S. Colonges, R. Coniglione, A. Cosquer, P. Coyle, M. Cresta, A. Creuso, A. Cruz, G. Cuttone, A. D’Amico, R. Dallier, B. De Martino, M. De Palma, I. Di Palma, A. F. Díaz, D. Diego- Tortosa, C. Distefano, A. Domi, C. Donzaud, D. Dornic, M. Dörr, D. Drouhin, T. Eberl, A. Eddyamoui, T. van Eeden, D. van Eijk, I. El Bojaddaini, H. Eljarrari, D. Elsaesser, A. Enzenhöfer, V. Espinosa, P. Fermani, G. Ferrara, M. D. Filipovic, F. Filippini, J. Fransen, L. A. Fusco, D. Gajanana, T. Gal, J. García Méndez, A. Garcia Soto, E. Garçon, F. Garufi, C. Gatius, N. Geißelbrecht, L. Gialanella, E. Giorgio, S. R. Gozzini, R. Gracia, K. Graf, G. Grella, D. Guderian, C. Guidi, B. Guillon, M. Gutiérrez, J. Haefner, S. Hallmann, H. Hamdaoui, H. van Haren, A. Heijboer, A. Hekalo, L. Hennig, S. Henry, J. J. Hernández-Rey, J. Hofestädt, F. Huang,W. Idrissi Ibnsalih, A. Ilioni, G. Illuminati, C.W. James, D. Janezashvili, P. Jansweijer, M. de Jong, P. de Jong, B. J. Jung, M. Kadler, P. Kalaczynski, O. Kalekin,U. F. Katz, F. Kayzel, P.Keller, N. R. Khan Chowdhury, G. Kistauri, F. van der Knaap, P. Kooijman, A. Kouchner, M. Kreter, V. Kulikovskiy, M. Labalme, P. Lagier, R. Lahmann, P. Lamare, M. Lamoureux, G. Larosa, C. Lastoria, J. Laurence, A. Lazo, R. Le Breton, E. Le Guirriec, S. Le Stum, G. Lehaut, O. Leonardi, F. Leone, E. Leonora, C. Lerouvillois, J. Lesrel, N. Lessing, G. Levi, M. Lincetto, M. Lindsey Clark, T. Lipreau, C. LLorens Alvarez, A. Lonardo, F. Longhitano, D. Lopez-Coto, N. Lumb, L. Maderer, J. Majumdar, J. Manczak, A. Margiotta, A. Marinelli, A. Marini, C. Markou, L. Martin, J. A. Martínez-Mora, A. Martini, F. Marzaioli, S. Mastroianni, K.W. Melis, G. Miele, P. Migliozzi, E. Migneco, P. Mijakowski, L. S. Miranda, C. M. Mollo, M. Mongelli, A. Moussa, R. Muller, P. Musico, M. Musumeci, L. Nauta, S. Navas, C. A. Nicolau, B. Nkosi, B. Ó Fearraigh, M. O’Sullivan, A. Orlando, G. Ottonello, S. Ottonello, J. Palacios González5, G. Papalashvili, R. Papaleo, C. Pastore, A. M. Paun, G. E. Pavalas, G. Pellegrini, C. Pellegrino, M. Perrin-Terrin, V. Pestel, P. Piattelli, C. Pieterse, O. Pisanti, C. Poirè, V. Popa, T. Pradier, F. Pratolongo, I. Probst, G. Pühlhofer, S. Pulvirenti, G. Quéméner, N. Randazzo, A. Rapicavoli, S. Razzaque, D. Real, S. Reck, G. Riccobene, L. Rigalleau, A. Romanov, A. Rovelli, J. Royon, F. Salesa Greus, D. F. E. Samtleben, A. Sánchez Losa, M. Sanguineti, A. Santangelo, D. Santonocito, P. Sapienza, J. Schmelling, J. Schnabel, M. F. Schneider, J. Schumann, H. M. Schutte, J. Seneca, I. Sgura, R. Shanidze, A. Sharma, A. Sinopoulou, B. Spisso, M. Spurio, D. Stavropoulos, J. Steijger, S. M. Stellacci, M. Taiuti, F. Tatone, Y. Tayalati, E. Tenllado, D. Tézier, T. Thakore, S. Theraube, H. Thiersen, P. Timmer, S. Tingay, S. Tsagkli, V. Tsourapis, E. Tzamariudaki, D. Tzanetatos, C. Valieri, V. Van Elewyck, G. Vasileiadis, F. Versari, S. Viola, D. Vivolo, G. de Wasseige, J.Wilms, R.Wojaczynski, E. deWolf, T. Yousfi, S. Zavatarelli, A. Zegarelli, D. Zito, J. D. Zornoza, J. Zúñiga, N. Zywucka.

Intelligent reflecting surfaces (IRSs) enable multiple-input multiple-output (MIMO) transmitters to modify the communication channels between the transmitters and receivers. In the presence of eavesdropping terminals, this degree of freedom can be used to effectively suppress the information leakage towards such malicious terminals. This leads to significant potential secrecy gains in IRS-aided MIMO systems. This work exploits these gains via a tractable joint design of downlink beamformers and IRS phase-shifts. In this respect, we consider a generic IRS-aided MIMO wiretap setting and invoke fractional programming and alternating optimization techniques to iteratively find the beamformers and phase-shifts that maximize the achievable weighted secrecy sum-rate. Our design concludes two low-complexity algorithms for joint beamforming and phase-shift tuning. Performance of the proposed algorithms are numerically evaluated and compared to the benchmark. The results reveal that integrating IRSs into MIMO systems not only boosts the secrecy performance of the system, but also improves the robustness against passive eavesdropping., Comment: 54 pages, 11 figures, A shortened version of this manuscript has been submitted to IEEE Transactions on Information Forensics and Security

The development of effective catalytic processes for the conversion of CO2 into value-added chemicals or fuels, such as methanol synthesis or the dry reforming of methane (DRM) relies strongly on a rational catalyst design, which in turn requires an in-depth understanding of structure-activity relationships. Due to the inherent complexity of heterogeneous catalytic systems, an arsenal of complementary techniques is required to characterize the catalytic structure (and dynamics thereof) from the atomic-to-nanoscale (under reaction conditions). In this talk, we show how the application of combined X-ray powder diffraction (XRD) and X-ray absorption spectroscopy (XAS) allows obtaining the oxidation state, the local and (nano)crystalline structure of the catalysts providing the basis for the formulation of structure-performance relationships in catalysts for CO2 valorization reactions. In the first example, we demonstrate how a combined operando XAS-XRD experiment allowed us to relate the evolution of the structure of In2O3 nanoparticles (NPs) to their activity for CO2 hydrogenation to methanol.[1] The experiments revealed a reductive amorphization of the In2O3−x nanocrystallites with time on stream (TOS), leading ultimately to an over-reduction of In2O3−x to (molten) In0, in a process that is linked to catalyst deactivation. When the In2O3 NPs were supported on a nanocrystalline monoclinic ZrO2 support, we observed the stabilization of the oxidation state of In via the formation of a solid solution m-ZrO2:In.[2] In the second example, we explore a Ni-Fe-based catalyst for the DRM. Combined, operando XAS-XRD experiments allowed us to probe the dynamics of Ni-Fe alloying/dealloying with the formation of FeO to explain the superior stability of the NiFe catalysts compared to a Ni-based analogue, due to a Fe-FeOx-based redox cycle.[3] In the last example, combined XAS–XRD experiments are used to shed light on the formation of Ru0 nanoparticles (ca.1 nm) via their exsolution from defective, fluorite-type Sm2RuxCe2−xO7 solid solutions. The resulting exsolved nanoparticles show a high activity and stability for the DRM.[4]

Chemical Reviews, 121 (20), ISSN:0009-2665, ISSN:1520-6890

Objective: The aim of the project is to teach clinical practical and communication skills in the Clinical Skills Lab (CSL) of the University of Veterinary Medicine Hannover, Foundation (TiHo) during the COVID-19 pandemic. Methodology: As a measure to limit potential SARS-CoV2 infections, the CSL learning stations were digitised and made available on the Moodle learning platform of the TiHo. Online quiz stations were also developed, as well as improvisations that allowed students to practise practical skills at home using everyday materials. Courses for Practical Year (PY) students were digitised and again combined with classroom exercises throughout the year. The teaching formats could be evaluated by the students by means of a questionnaire using a Likert scale (1=agree; 4=disagree). Results: A total of 24.92% of students (n=1272) completed the learning stations with improvisations. The quiz stations were completed with a percentage of 75.08%. Students indicated that the improvisations were easily implementable from home (M=1.33) and assisted in learning the practical skills in question (M=1.89). The quiz stations were considered helpful (M=1.40) and complementary to previous CSL offers (M=1.13). The PY students found the amount of teaching materials adequate (M=1.76) and described communication with the lecturers as problem-free (compulsory electives=1.24). Conclusions: Digital teaching is suitable as a supplement to existing face-to-face courses at the CSL, but cannot replace on-site training under the guidance of trained personnel. The CSL will continue to strive for a combination of online and face-to-face courses for some learning stations in the future., Zielsetzung: Ziel des Projekts ist die Vermittlung klinisch-praktischer und kommunikativer Fertigkeiten im Clinical Skills Lab (CSL) der Stiftung Tierärztliche Hochschule Hannover (TiHo) während der COVID-19-Pandemie. Methodik: Als Maßnahme zur Einschränkung möglicher Infektionen durch SARS-CoV2 wurden die Lernstationen des CSL digitalisiert und auf der Lernplattform Moodle bereit gestellt. Außerdem wurden Online-Quizstationen sowie Improvisationen entwickelt, bei denen Studierende praktische Fertigkeiten zu Hause mit alltäglichen Materialien trainieren konnten. Kurse für Studierende des Praktischen Jahres (PJ) wurden digitalisiert und im Verlauf des Jahres wieder mit Präsenz-Übungen kombiniert. Die Lehrformate konnten von den Studierenden mittels Fragebogen anhand einer Likert-Skala (1= trifft zu bis 4= trifft nicht zu) evaluiert werden. Ergebnisse: 24,92% der Studierenden (n=1272) führten die Lernstationen mit Improvisationen durch. Die Quizstationen wurden mit einem Anteil von 75,08 % absolviert. Die Studierenden gaben an, dass die Improvisationen problemlos von zu Hause aus umsetzbar waren (MW=1,33) und dabei unterstützten, die betreffenden praktischen Fertigkeiten zu erlernen (MW: 1,89). Die Quizstationen wurden als hilfreich (MW=1,40) und als Ergänzung zu den bisherigen Angeboten des CSL (MW=1,13) angesehen. Die PJ-Studierenden fanden den Umfang der Lehrmaterialien angemessen (MW=1,76) und beschrieben die Kommunikation mit den Dozierenden als problemlos (WP=1,24). Schlussfolgerungen: Digitale Lehre eignet sich als Ergänzung zu bestehenden Präsenzkursen des CSL, kann das Training vor Ort unter Anleitung von geschultem Personal aber nicht ersetzen. Eine Kombination aus Online-und Präsenzveranstaltungen wird vom CSL auch in Zukunft für einige Lernstationen angestrebt., GMS Journal for Medical Education; 38(5):Doc86

Photography can be used for a wide variety of social functions. The hermeneutic method of image cluster analysis presented deals with a comparatively new social use and understanding of photography: as digital montage forming intricate compilations. At the methodological heart of this approach is the 1. figurative analysis of the compositional principles of particular image compilations, i.e., their expressive meaning. This ideographic perspective is expanded and supplemented by 2. investigating the structure of the mediated field of perception and action of each image cluster, as well as the styles of observing and knowing that they predicate. Methodologically speaking, the approach relies on an assumption that far from being an invention of technological media, the "game" (WITTGENSTEIN) which is constitutive of iconic image clusters, complete with relationships of similarity and difference, has its anthropological basis and primary social expression in people's body language and in minor social distinctions. According to this hypothesis, in recent image clusters photography is no longer necessarily understood as depicting or documenting occurrences in the lifeworld, but is instead consolidated as a collectively shared means of expression which can be repeatedly recombined to form new figures of expression—in other words, it achieves a decidedly idiomatic quality., Forum Qualitative Sozialforschung / Forum: Qualitative Social Research, Vol 21, No 2 (2020): Challenging Times— Qualitative Methods and Methodological Approaches to Research on Time

This paper presents a method to calculate the exact average block error probability of some random code ensembles under maximum-likelihood decoding. The proposed method is applicable to various channels and ensembles. The focus is on both spherical and Gaussian random codes on the additive white Gaussian noise channel as well as binary random codes on both the binary symmetric channel and the binary erasure channel. While for the uniform spherical ensemble Shannon, in 1959, argued with solid angles in $N$-dimensional space, the presented approach projects the problem into two dimensions and applies standard trigonometry. This simplifies the derivation and also allows for the analysis of the independent identically distributed (i.i.d.) Gaussian ensemble which turns out to perform better for short blocklengths and high rates. Moreover, a new lower bound on the average block error probability of the uniform spherical ensemble is found. For codes with more than three codewords, it is tighter than the sphere packing bound, but requires exactly the same computing effort. Furthermore, tight approximations are proposed to simplify the computation of both the exact average error probability and the two bounds. For the binary symmetric channel and the binary erasure channel, bounds on the average block error probability for i.i.d.\ random coding are derived and compared to the exact calculations., Comment: Typo in Equation (60) corrected

Positronium in the 2 3 S metastable state exhibits a low electrical polarizability and a long lifetime (1140 ns), making it a promising candidate for interferometry experiments with a neutral matter-antimatter system. In the present work, 2 3 S positronium is produced, in the absence of an electric field, via spontaneous radiative decay from the 3 3 P level populated with a 205-nm UV laser pulse. Thanks to the short temporal length of the pulse, 1.5 ns full width at half maximum, different velocity populations of a positronium cloud emitted from a nanochanneled positron-positronium converter were selected by delaying the excitation pulse with respect to the production instant. 2 3 S positronium atoms with velocity tuned between 7 × 10 4 ms −1 and 10 × 10 4 ms −1 were thus produced. Depending on the selected velocity, a 2 3 S production efficiency ranging from ∼0.8% to ∼1.7%, with respect to the total amount of emitted positronium, was obtained. The observed results give a branching ratio for the 3 3 P-2 3 S spontaneous decay of (9.7 ± 2.7)%. The present velocity selection technique could allow one to produce an almost monochromatic beam of ∼1 × 10 3 2 3 S atoms with a velocity spread of

A key challenge in the catalytic conversion of CH4 and CO2 into a synthesis gas (CO and H2) via the dry reforming of methane (DRM) is the development of stable catalysts. We demonstrate that the reductive exsolution of metallic Ru from fluorite-type solid solutions Sm2RuxCe2–xO7 (x = 0, 0.1, 0.2, 0.4) yields catalysts with high activity and remarkable stability for the DRM. The catalysts feature Ru(0) nanoparticles about 1–2 nm in diameter that are uniformly dispersed on the surface of the resulting oxide support. The exsolved material was investigated by synchrotron X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS at Ru, Sm, and Ce K-edges), Raman spectroscopy, and transmission electron microscopy. In situ XAS-XRD experiments revealed that the exsolution of metallic ruthenium is accompanied by a rearrangement of the oxygen vacancies within the lattice. The catalysts derived through exsolution outperform (stable over 4 days) the reference catalysts prepared by wetness impregnation and sodium borohydride reduction. The superior performance of the exsolved catalysts is explained by their high resistance to sintering-induced deactivation owing to the stabilizing metal–support interaction in this class of materials. It is also demonstrated that the Ru nanoparticles can undergo redissolution (in air at 700 °C)–exsolution cycles., ACS Catalysis, 10 (3), ISSN:2155-5435