Ensemble forecasting applied to the field of hydrology is currently an established area of research embracing a broad spectrum of operational situations. This work catalogs the various pathways of ...ensemble streamflow forecasting based on an exhaustive review of more than 700 studies over the last 40 years. We focus on the advanced state of the art in the model‐based (dynamical) ensemble forecasting approaches. Ensemble streamflow prediction systems are categorized into three leading classes: statistics‐based streamflow prediction systems, climatology‐based ensemble streamflow prediction systems and numerical weather prediction‐based hydrological ensemble prediction systems. For each ensemble approach, technical information, as well as details about its strengths and weaknesses, are provided based on a critical review of the studies listed. Through this literature review, the performance and uncertainty associated with the ensemble forecasting systems are underlined from both operational and scientific viewpoints. Finally, the remaining key challenges and prospective future research directions are presented, notably through hybrid dynamical ‐ statistical learning approaches, which obviously present new challenges to be overcome in order to allow the successful employment of ensemble streamflow forecasting systems in the next decades. Targeting students, researchers and practitioners, this review provides a detailed perspective on the major features of an increasingly important area of hydrological forecasting.
Key Points
This work summarizes the 40 years of research in the generation of streamflow forecasts based on an exhaustive review of studies
Ensemble prediction systems are categorized into three classes: statistics‐based, climatology‐based and numerical weather prediction‐based hydrological ensemble prediction systems
For each ensemble forecasting system, thorough technical information is provided
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Since 11 March 2020 when officially declared a global pandemic, Covid‐19 (or SARS‐COV2) has turned out to be a multifaceted disease differently affecting countries and individuals. What makes certain ...countries more vulnerable than others has attracted the interest of scientists from various disciplines. This paper intends to compare the impact of demographic parameters, population health conditions and policy actions on prevalence and fatality levels of Covid‐19 during the first 3 months since its declaration of global pandemic. A country‐level exploratory analysis has been conducted in order to assess how demography, national health conditions and measures taken interact and condition the disease outcomes. Analysis relies on publicly available data on Covid‐19 reported cases, deaths and number of persons tested. Those data are combined with demographic parameters (sex ratio, mean age, population density and life expectancy), health data (cardiovascular death rate, diabetes prevalence, share of smokers among males and females and number of hospital beds) and information about relative national policies aiming the management of the pandemic (lockdown timing and duration). Our analysis confirms the diversity of factors and the complexity of their interaction in explaining the propagation and fatality of the disease across Europe. Our findings question some well‐established attitudes concerning the role of demographic variables and public health conditions in the spread of the disease.
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A new class of high-order numerical methods for approximating nonlinear conservation laws is described (entropy viscosity method). The novelty is that a nonlinear viscosity based on the local size of ...an entropy production is added to the numerical discretization at hand. This new approach does not use any flux or slope limiters, applies to equations or systems supplemented with one or more entropy inequalities and does not depend on the mesh type and polynomial approximation. Various benchmark problems are solved with finite elements, spectral elements and Fourier series to illustrate the capability of the proposed method.
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In designing organic materials for electronics applications, particularly for organic photovoltaics (OPV), the ionization potential (IP) of the donor and the electron affinity (EA) of the acceptor ...play key roles. This makes OPV design an appealing application for computational chemistry since IPs and EAs are readily calculable from most electronic structure methods. Unfortunately reliable, high-accuracy wave function methods, such as coupled cluster theory with single, double, and perturbative triples CCSD(T) in the complete basis set (CBS) limit are too expensive for routine applications to this problem for any but the smallest of systems. One solution is to calibrate approximate, less computationally expensive methods against a database of high-accuracy IP/EA values; however, to our knowledge, no such database exists for systems related to OPV design. The present work is the first of a multipart study whose overarching goal is to determine which computational methods can be used to reliably compute IPs and EAs of electron acceptors. This part introduces a database of 24 known organic electron acceptors and provides high-accuracy vertical IP and EA values expected to be within ±0.03 eV of the true non-relativistic, vertical CCSD(T)/CBS limit. Convergence of IP and EA values toward the CBS limit is studied systematically for the Hartree–Fock, MP2 correlation, and beyond-MP2 coupled cluster contributions to the focal point estimates.
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5.
Corpus Nancy, Jean-Luc
2008, 2008-10-15, 20081015, 2009, 2008.
eBook, Book
How have we thought ?the body?? How can we think it anew? The body of mortal creatures, the body politic, the body of letters and of laws, the ?mystical body of Christ??all these (and others) are ...incorporated in the word Corpus, the title and topic of Jean-Luc Nancy?s masterwork.Corpus is a work of literary force at once phenomenological, sociological, theological, and philosophical in its multiple orientations and approaches. In thirty-six brief sections, Nancy offers us at once an encyclopedia and a polemical program?reviewing classical takes on the ?corpus? from Plato, Aristotle, and Saint Paul to Descartes, Hegel, Husserl, and Freud, while demonstrating that the mutations (technological, biological, and political) of our own culture have given rise to the need for a new understanding of the body. He not only tells the story of this cultural change but also explores the promise and responsibilities that such a new understanding entails.The long-awaited English translation is a bold, bravura rendering. To the title essay are added five closely related recent pieces?including a commentary by Antonia Birnbaum?dedicated in large part to the legacy of the ?mind-body problem? formulated by Descartes and the challenge it poses to rethinking the ancient problems of the corpus. The last and most poignant of these essays is ?The Intruder,? Nancy?s philosophical meditation on his heart transplant. The book also serves as the opening move in Nancy?s larger project called ?The deconstruction of Christianity.?
Large wild ungulates are a major biotic factor shaping plant communities. They influence species abundance and occurrence directly by herbivory and plant dispersal, or indirectly by modifying ...plant‐plant interactions and through soil disturbance. In forest ecosystems, researchers’ attention has been mainly focused on deer overabundance. Far less is known about the effects on understory plant dynamics and diversity of wild ungulates where their abundance is maintained at lower levels to mitigate impacts on tree regeneration. We used vegetation data collected over 10 years on 82 pairs of exclosure (excluding ungulates) and control plots located in a nation‐wide forest monitoring network (Renecofor). We report the effects of ungulate exclusion on (i) plant species richness and ecological characteristics, (ii) and cover percentage of herbaceous and shrub layers. We also analyzed the response of these variables along gradients of ungulate abundance, based on hunting statistics, for wild boar (Sus scrofa), red deer (Cervus elaphus) and roe deer (Capreolus capreolus). Outside the exclosures, forest ungulates maintained higher species richness in the herbaceous layer (+15%), while the shrub layer was 17% less rich, and the plant communities became more light‐demanding. Inside the exclosures, shrub cover increased, often to the benefit of bramble (Rubus fruticosus agg.). Ungulates tend to favour ruderal, hemerobic, epizoochorous and non‐forest species. Among plots, the magnitude of vegetation changes was proportional to deer abundance. We conclude that ungulates, through the control of the shrub layer, indirectly increase herbaceous plant species richness by increasing light reaching the ground. However, this increase is detrimental to the peculiarity of forest plant communities and contributes to a landscape‐level biotic homogenization. Even at population density levels considered to be harmless for overall plant species richness, ungulates remain a conservation issue for plant community composition.
The French forest ecosystem monitoring network (Renecofor) provided vegetation surveys resampled over 10 years, of 82 pairs of exclosure (no ungulate) and control plots. The analysis revealed that ungulates reduce the cover and richness of the shrub layers, and increase species richness of the herbaceous layer to the benefit of light‐demanding, ruderal and non‐forest species. We also show that the magnitude of vegetation changes is proportional to local deer abundances. The tremendous increase of wild ungulate populations throughout the Northern Hemisphere in the last decades has been altering not only the woody regeneration but also the diversity of herbaceous species.
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Donor–acceptor organic solar cells often show high quantum yields for charge collection, but relatively low open-circuit voltages (V OC) limit power conversion efficiencies to around 12%. We report ...here the behavior of a system, PIPCP:PC61BM, that exhibits very low electronic disorder (Urbach energy less than 27 meV), very high carrier mobilities in the blend (field-effect mobility for holes >10–2 cm2 V–1 s–1), and a very low driving energy for initial charge separation (50 meV). These characteristics should give excellent performance, and indeed, the V OC is high relative to the donor energy gap. However, we find the overall performance is limited by recombination, with formation of lower-lying triplet excitons on the donor accounting for 90% of the recombination. We find this is a bimolecular process that happens on time scales as short as 100 ps. Thus, although the absence of disorder and the associated high carrier mobility speeds up charge diffusion and extraction at the electrodes, which we measure as early as 1 ns, this also speeds up the recombination channel, giving overall a modest quantum yield of around 60%. We discuss strategies to remove the triplet exciton recombination channel.
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Background
Coronavirus disease‐2019 (COVID‐19) has been associated with cardiovascular complications and coagulation disorders.
Objectives
To explore the coagulopathy and endothelial dysfunction in ...COVID‐19 patients.
Methods
The study analyzed clinical and biological profiles of patients with suspected COVID‐19 infection at admission, including hemostasis tests and quantification of circulating endothelial cells (CECs).
Results
Among 96 consecutive COVID‐19‐suspected patients fulfilling criteria for hospitalization, 66 were tested positive for SARS‐CoV‐2. COVID‐19‐positive patients were more likely to present with fever (P = .02), cough (P = .03), and pneumonia at computed tomography (CT) scan (P = .002) at admission. Prevalence of D‐dimer >500 ng/mL was higher in COVID‐19‐positive patients (74.2% versus 43.3%; P = .007). No sign of disseminated intravascular coagulation were identified. Adding D‐dimers >500 ng/mL to gender and pneumonia at CT scan in receiver operating characteristic curve analysis significantly increased area under the curve for COVID‐19 diagnosis. COVID‐19‐positive patients had significantly more CECs at admission (P = .008) than COVID‐19‐negative ones. COVID‐19‐positive patients treated with curative anticoagulant prior to admission had fewer CECs (P = .02) than those without. Interestingly, patients treated with curative anticoagulation and angiotensin‐converting‐enzyme inhibitors or angiotensin receptor blockers had even fewer CECs (P = .007).
Conclusion
Curative anticoagulation could prevent COVID‐19‐associated coagulopathy and endothelial lesion.
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With their unusual electronic structures, organic radical molecules display luminescence properties potentially relevant to lighting applications; yet, their luminescence quantum yield and stability ...lag behind those of other organic emitters. Here, we designed donor-acceptor neutral radicals based on an electron-poor perchlorotriphenylmethyl or tris(2,4,6-trichlorophenyl)methyl radical moiety combined with different electron-rich groups. Experimental and quantum-chemical studies demonstrate that the molecules do not follow the Aufbau principle: the singly occupied molecular orbital is found to lie below the highest (doubly) occupied molecular orbital. These donor-acceptor radicals have a strong emission yield (up to 54%) and high photostability, with estimated half-lives reaching up to several months under pulsed ultraviolet laser irradiation. Organic light-emitting diodes based on such a radical emitter show deep-red/near-infrared emission with a maximal external quantum efficiency of 5.3%. Our results provide a simple molecular-design strategy for stable, highly luminescent radicals with non-Aufbau electronic structures.
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A spin-flip from a triplet to a singlet excited state, that is, reverse intersystem crossing (RISC), is an attractive route for improving light emission in organic light-emitting diodes, as shown by ...devices using thermally activated delayed fluorescence (TADF). However, device stability and efficiency roll-off remain challenging issues that originate from a slow RISC rate (kRISC). Here, we report a TADF molecule with multiple donor units that form charge-resonance-type hybrid triplet states leading to a small singlet–triplet energy splitting, large spin–orbit couplings, and a dense manifold of triplet states energetically close to the singlets. The kRISC in our TADF molecule is as fast as 1.5 × 107 s−1, a value some two orders of magnitude higher than typical TADF emitters. Organic light-emitting diodes based on this molecule exhibit good stability (estimated T90 about 600 h for 1,000 cd m−2), high maximum external quantum efficiency (>29.3%) and low efficiency roll-off (<2.3% at 1,000 cd m−2).An organic molecule, 5Cz-TRZ, with multiple donor units supports fast reverse intersystem crossing, allowing fabrication of high-performance organic light-emitting diodes.
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