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Earthquake-Induced Chains of Geologic Hazards (2019)
Fan, Xuanmei ; Scaringi, Gianvito ; Korup, Oliver ; West, A. Joshua ; van Westen, Cees J. ; Tanyas, Hakan ; Hovius, Niels ; Hales, Tristram C. ; Jibson, Randall W. ; Allstadt, Kate E. ; Zhang, Limin ; Evans, Stephen G. ; Xu, Chong ; Li, Gen ; Pei, Xiangjun ; Xu, Qiang ; Huang, Runqiu
Large earthquakes initiate chains of surface processes that last much longer than the brief moments of strong shaking. Most moderate‐ and large‐magnitude earthquakes trigger landslides, ranging from small failures in the soil cover to massive, devastating rock avalanches. Some landslides dam rivers and impound lakes, which can collapse days to centuries later, and flood mountain valleys for hundreds of kilometers downstream. Landslide deposits on slopes can remobilize during heavy rainfall and evolve into debris flows. Cracks and fractures can form and widen on mountain crests and flanks, promoting increased frequency of landslides that lasts for decades. More gradual impacts involve the flushing of excess debris downstream by rivers, which can generate bank erosion and floodplain accretion as well as channel avulsions that affect flooding frequency, settlements, ecosystems, and infrastructure. Ultimately, earthquake sequences and their geomorphic consequences alter mountain landscapes over both human and geologic time scales. Two recent events have attracted intense research into earthquake‐induced landslides and their consequences: the magnitude M 7.6 Chi‐Chi, Taiwan earthquake of 1999, and the M 7.9 Wenchuan, China earthquake of 2008. Using data and insights from these and several other earthquakes, we analyze how such events initiate processes that change mountain landscapes, highlight research gaps, and suggest pathways toward a more complete understanding of the seismic effects on the Earth's surface.
Optimized highly efficient multilayer-coated blazed gratings for the tender X-ray region (2019)
Sokolov, Andrey ; Huang, Qiushi ; Senf, Friedmar ; Feng, Jiangtao ; Lemke, Stephanie ; Alimov, Svyatoslav ; Knedel, Jeniffa ; Zeschke, Thomas ; Kutz, Oliver ; Seliger, Tino ; Gwalt, Grzegorz ; Schäfers, Franz ; Siewert, Frank ; Kozhevnikov, Igor ; Qi, Runze ; Zhang, Zhong ; Li, Wenbin ; Wang, Zhanshan
The optimized design of multilayer-coated blazed gratings (MLBG) for high-flux tender X-ray monochromators was systematically studied by numerical simulations. The resulting correlation between the multilayer d-spacing and grating blaze angle significantly deviated from the one predicted by conventional equations. Three high line density gratings with different blaze angles were fabricated and coated by the same Cr/C multilayer. The MLBG with an optimal blaze angle of 1.0 degrees showed a record efficiency reaching 60% at 3.1 keV and 4.1 keV. The measured efficiencies of all three gratings were consistent with calculated results proving the validity of the numerical simulation and indicating a more rigorous way to design the optimal MLBG structure. Published by The Optical Society under the terms of the Creative Commons Attribution 4.0 License.
Nuclear dynamics in resonant inelastic X-ray scattering and X-ray absorption of methanol (2019)
Vaz da Cruz, Vinícius ; Ignatova, Nina ; Couto, Rafael ; Fedotov, Daniil ; Rehn, Dirk R. ; Savchenko, Viktoriia ; Norman, Patrick ; Ågren, Hans ; Polyutov, Sergey ; Niskanen, Johannes ; Eckert, Sebastian ; Jay, Raphael Martin ; Fondell, Mattis ; Schmitt, Thorsten ; Pietzsch, Annette ; Föhlisch, Alexander ; Odelius, Michael ; Kimberg, Victor ; Gel’mukhanov, Faris
We report on a combined theoretical and experimental study of core-excitation spectra of gas and liquid phase methanol as obtained with the use of X-ray absorption spectroscopy (XAS) and resonant inelastic X-ray scattering (RIXS). The electronic transitions are studied with computational methods that include strict and extended second-order algebraic diagrammatic construction [ADC(2) and ADC(2)-x], restricted active space second-order perturbation theory, and time-dependent density functional theory-providing a complete assignment of the near oxygen K-edge XAS. We show that multimode nuclear dynamics is of crucial importance for explaining the available experimental XAS and RIXS spectra. The multimode nuclear motion was considered in a recently developed "mixed representation" where dissociative states and highly excited vibrational modes are accurately treated with a time-dependent wave packet technique, while the remaining active vibrational modes are described using Franck-Condon amplitudes. Particular attention is paid to the polarization dependence of RIXS and the effects of the isotopic substitution on the RIXS profile in the case of dissociative core-excited states. Our approach predicts the splitting of the 2a RIXS peak to be due to an interplay between molecular and pseudo-atomic features arising in the course of transitions between dissociative core- and valence-excited states. The dynamical nature of the splitting of the 2a peak in RIXS of liquid methanol near pre-edge core excitation is shown. The theoretical results are in good agreement with our liquid phase measurements and gas phase experimental data available from the literature. (C) 2019 Author(s).
Hierarchically structured iron-doped silver (Ag-Fe) lotus flowers for an efficient oxygen reduction reaction (vol 10, pg 7304 -7310, 2018) (2019)
El-Nagar, Gumaa A. ; Lauermann, Iver ; Sarhan, Radwan Mohamed ; Roth, Christina
Estimation of suspended sediment concentration in an intermittent river using multi-temporal high-resolution satellite imagery (2019)
Soares Pereira, Francisco Jairo ; Gomes Costa, Carlos Alexandre ; Förster, Saskia ; Brosinsky, Arlena ; de Araujo, Jose Carlos
There is a shortage of sediment-routing monitoring worldwide, despite its relevance to environmental processes. In drylands, where water resources are more vulnerable to the sediment dynamics, this flaw is even more harmful. In the semi-arid Caatinga biome in the North-east of Brazil, rivers are almost all intermittent and hydro-sedimentological monitoring is scarce. In the biome, water supply derives from thousands of surface reservoirs, whose water availability is liable to be reduced by siltation and sediment-related pollution. The goal of this research was to evaluate the potential of multi-temporal high-resolution satellite imagery (RapidEye) to assess the suspended sediment concentration (SSC) in the medium-sized intermittent Jaguaribe River, Brazil, during a 5-year period. We validated 15 one-, two- and three-band indices for SSC estimation based on RapidEye spectral bands deduced in the context of the present investigation and nine indices proposed in the literature for other optical sensors, by comparing them with in-situ concentration data. The in-situ SSC data ranged from 67 mg.L-1 to 230 mg.L-1. We concluded that RapidEye images can assess moderate SSC of intermittent rivers, even when their discharge is low. The RapidEye indices performed better than those from literature. The spectral band that best represented SSC was the near infrared, whose performance improved when associated with the green band. This conclusion agrees with literature findings for diverse sedimentological contexts. The three-band spectral indices performed worse than those with only one or two spectral bands, showing that the use of a third band did not enhance the model ability. Besides, we show that the hydrological characteristics of semi-arid intermittent rivers generate difficulties to monitor SSC using optical satellite remote sensing, such as time-concentrated sediment yield; and its association with recent rainfall events and, therefore, with cloudy sky.
Validation study for measuring absorption and reduced scattering coefficients by means of laser-induced backscattering imaging (2019)
Zude-Sasse, Manuela ; Hashim, Norhashila ; Hass, Roland ; Polley, Nabarun ; Regen, Christian
Decoupling of optical properties appears challenging, but vital to get better insight of the relationship between light and fruit attributes. In this study, nine solid phantoms capturing the ranges of absorption (μa) and reduced scattering (μs’) coefficients in fruit were analysed non-destructively using laser-induced backscattering imaging (LLBI) at 1060 nm. Data analysis of LLBI was carried out on the diffuse reflectance, attenuation profile obtained by means of Farrell’s diffusion theory either calculating μa [cm−1] and μs’ [cm−1] in one fitting step or fitting only one optical variable and providing the other one from a destructive analysis. The nondestructive approach was approved when calculating one unknown coefficient non-destructively, while no ability of the method was found to analysis both, μa and μs’, non-destructively. Setting μs’ according to destructive photon density wave (PDW) spectroscopy and fitting μa resulted in root mean square error (rmse) of 18.7% in comparison to fitting μs’ resulting in rmse of 2.6%, pointing to decreased measuring uncertainty, when the highly variable μa was known. The approach was tested on European pear, utilizing destructive PDW spectroscopy for setting one variable, while LLBI was applied for calculating the remaining coefficient. Results indicated that the optical properties of pear obtained from PDW spectroscopy as well as LLBI changed concurrently in correspondence to water content mainly. A destructive batch-wise analysis of μs’ and online analysis of μa may be considered in future developments for improved fruit sorting results, when considering fruit with high variability of μs’.
Causative classification of river flood events (2019)
Tarasova, Larisa ; Merz, Ralf ; Kiss, Andrea ; Basso, Stefano ; Blöchl, Günter ; Merz, Bruno ; Viglione, Alberto ; Plötner, Stefan ; Guse, Björn ; Schumann, Andreas ; Fischer, Svenja ; Ahrens, Bodo ; Anwar, Faizan ; Bárdossy, András ; Bühler, Philipp ; Haberlandt, Uwe ; Kreibich, Heidi ; Krug, Amelie ; Lun, David ; Müller-Thomy, Hannes ; Pidoto, Ross ; Primo, Cristina ; Seidel, Jochen ; Vorogushyn, Sergiy ; Wietzke, Luzie
A wide variety of processes controls the time of occurrence, duration, extent, and severity of river floods. Classifying flood events by their causative processes may assist in enhancing the accuracy of local and regional flood frequency estimates and support the detection and interpretation of any changes in flood occurrence and magnitudes. This paper provides a critical review of existing causative classifications of instrumental and preinstrumental series of flood events, discusses their validity and applications, and identifies opportunities for moving toward more comprehensive approaches. So far no unified definition of causative mechanisms of flood events exists. Existing frameworks for classification of instrumental and preinstrumental series of flood events adopt different perspectives: hydroclimatic (large-scale circulation patterns and atmospheric state at the time of the event), hydrological (catchment scale precipitation patterns and antecedent catchment state), and hydrograph-based (indirectly considering generating mechanisms through their effects on hydrograph characteristics). All of these approaches intend to capture the flood generating mechanisms and are useful for characterizing the flood processes at various spatial and temporal scales. However, uncertainty analyses with respect to indicators, classification methods, and data to assess the robustness of the classification are rarely performed which limits the transferability across different geographic regions. It is argued that more rigorous testing is needed. There are opportunities for extending classification methods to include indicators of space-time dynamics of rainfall, antecedent wetness, and routing effects, which will make the classification schemes even more useful for understanding and estimating floods. This article is categorized under: Science of Water > Water Extremes Science of Water > Hydrological Processes Science of Water > Methods
The Club Approach: A Gateway to Effective Climate Co-operation? (2019)
Hovi, Jon ; Sprinz, Detlef F. ; Saelen, Håkon ; Underdal, Arild
Although the Paris Agreement arguably made some progress, interest in supplementary approaches to climate change co-operation persist. This article examines the conditions under which a climate club might emerge and grow. Using agent-based simulations, it shows that even with less than a handful of major actors as initial members, a club can eventually reduce global emissions effectively. To succeed, a club must be initiated by the ‘right’ constellation of enthusiastic actors, offer sufficiently large incentives for reluctant countries and be reasonably unconstrained by conflicts between members over issues beyond climate change. A climate club is particularly likely to persist and grow if initiated by the United States and the European Union. The combination of club-good benefits and conditional commitments can produce broad participation under many conditions.
Actin dynamics and the Bmp pathway drive apical extrusion of proepicardial cells (2019)
Andrés-Delgado, Laura ; Ernst, Alexander ; Galardi-Castilla, María ; Bazaga, David ; Peralta, Marina ; Münch, Juliane ; Gonzalez-Rosa, Juan M. ; Marques, Inês ; Tessadori, Federico ; de la Pompa, José Luis ; Vermot, Julien ; Mercader, Nadia
The epicardium, the outer mesothelial layer enclosing the myocardium, plays key roles in heart development and regeneration. During embryogenesis, the epicardium arises from the proepicardium (PE), a cell cluster that appears in the dorsal pericardium (DP) close to the venous pole of the heart. Little is known about how the PE emerges from the pericardial mesothelium. Using a zebrafish model and a combination of genetic tools, pharmacological agents and quantitative in vivo imaging, we reveal that a coordinated collective movement of DP cells drives PE formation. We found that Bmp signaling and the actomyosin cytoskeleton promote constriction of the DP, which enables PE cells to extrude apically. We provide evidence that cell extrusion, which has been described in the elimination of unfit cells from epithelia and the emergence of hematopoietic stem cells, is also a mechanism for PE cells to exit an organized mesothelium and fulfil their developmental fate to form a new tissue layer, the epicardium.
Particle filters for high-dimensional geoscience applications: A review (2019)
van Leeuwen, Peter Jan ; Kunsch, Hans R. ; Nerger, Lars ; Potthast, Roland ; Reich, Sebastian
Particle filters contain the promise of fully nonlinear data assimilation. They have been applied in numerous science areas, including the geosciences, but their application to high-dimensional geoscience systems has been limited due to their inefficiency in high-dimensional systems in standard settings. However, huge progress has been made, and this limitation is disappearing fast due to recent developments in proposal densities, the use of ideas from (optimal) transportation, the use of localization and intelligent adaptive resampling strategies. Furthermore, powerful hybrids between particle filters and ensemble Kalman filters and variational methods have been developed. We present a state-of-the-art discussion of present efforts of developing particle filters for high-dimensional nonlinear geoscience state-estimation problems, with an emphasis on atmospheric and oceanic applications, including many new ideas, derivations and unifications, highlighting hidden connections, including pseudo-code, and generating a valuable tool and guide for the community. Initial experiments show that particle filters can be competitive with present-day methods for numerical weather prediction, suggesting that they will become mainstream soon.
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