22,433 research outputs found
CE Challenges: Work to Do
No full textCE has been used for more than two decades now. Despite many successes and advantages, there are still many challenges to be addressed. These challenges are both technical and organisational. In the paper we will address the current challenges of CE. Many challenges are related to the exchange of data and knowledge and to the systems that make data and knowledge exchange possible. Although much progress has been made in enabling extensive data and knowledge exchange and use, much remains to be wished. For example, there are still barriers to data exchange. Technically, these barriers may consist of different formats, differences in infrastructures and systems, and different semantics. There are also organisational and political barriers. For example, investment in information system may heavily impact upstream suppliers, while revenues of better information exchange may predominantly be gained by downstream actors. Without sharing costs and revenues, chain-wide information exchange will not be easily realised. Another barrier is the possible lack of willingness to share information, because of potential misuse of knowledge and loss of power. The paper is organised as follows. First we will describe the current manifestation of CE as described in a recent book. Second, we will list current trends in CE. Third, we will present some Critical Success Factors (CSFs) that are considered relevant for implementing and adapting CE practices. Last, we indicate some research and practical questions to be addressed, especially for areas that have a high potential and actual impact. </p
Mangrove forests under climate change in a 2°C world
No full textThe world's nations are committed to keeping global temperature rises to less than 2°C to avoid the worst impacts of climate change. Such a target is crucial for mangrove forests, because they are located primarily in tropical and subtropical regions that are expected to see large changes in climatic conditions; their intertidal location and sensitivity to changes in environmental conditions means that mangroves are expected to be on the front line of climate change impacts. We conceptualize what a 2°C world might look like for mangroves, and in particular the potential negative and positive responses of the mangrove ecosystem to anticipated changes in future atmospheric CO2 concentrations, temperature, sea level, cyclone activity, storminess and changes in the frequency, and magnitude of climatic oscillations. We also assess the spatial distribution of such stressors, their relative contributions to mangrove ecosystem dynamics, and discuss the challenges in attributing mangrove ecosystem dynamics to climate change versus other global change stressors. Such knowledge can help future-proof conservation and restoration activities, improve the Intergovernmental Panel on Climate Change's confidence level ascribed to climate change impacts on mangrove forests, and highlight the key temperature thresholds beyond which the future of the world's mangroves is less certain. This article is categorized under: Climate, Ecology, and Conservation > Modeling Species and Community Interactions Climate, Ecology, and Conservation > Observed Ecological Changes.Full Tex
Synthesis optimization and charge carrier transfer mechanism in LiLuSiO<sub>4</sub>:Ce, Tm storage phosphor
No full textLiLuSiO4:Ce and LiLuSiO4:Ce, Tm show very efficient charge carrier storage properties upon beta irradiation after samples have received treatment in vacuum. They outperform the commercial storage phosphor BaFBr(I):Eu2+ in many aspects. The influence of the synthesis conditions, Ce and Tm concentration, nonstoichiometry and codoping with Ca, Hf, Al and Ge are reported. Based on the results of the synthesis optimization, thermoluminescence (TL) emission and TL excitation spectra a mechanism of charge carrier transfer, storage, and recombination during irradiation and thermal or optical readout is proposed.Accepted Author ManuscriptRST/Fundamental Aspects of Materials and EnergyRST/Luminescence Material
Mangroves in arid regions: Ecology, threats, and opportunities
No full textMangroves are one of the few woody ecosystems that grow in hot-arid climates. They can survive extreme conditions of low precipitation, high solar radiation, wide temperature fluctuations and hypersalinity. These unique mangroves have distinct geomorphology, hydrology, forest structure, tree physiology, and soil biogeochemistry. In this review, supported by field data from Australia and Mexico, we explore the characteristics of mangroves in arid climates of the world. These mangroves are mostly tide-dominated with freshwater flows restricted to groundwater and sporadic tropical storms. They form dense forests with stunted growth dominated mainly by trees of the genus Avicennia that co-occur with salt marshes in the high intertidal. Their soils have low nutrient and carbon concentrations, and high soil δ15 N and δ13C values compared to subhumid and humid mangroves. Mangroves in arid climates have relatively low human pressure due to sparse human settlements. Key threats to these mangroves, which often persist at the edge of their physiological tolerances, include extreme drought, reductions in groundwater inputs, altered hydrology, sea-level fluctuations and increases in nutrient loading. Restoration of mangroves in arid climates should focus on restoring their hydrology. Mangroves in arid zones are under-represented in global maps and assessment programs, as they may not be consistent with countries’ definition of “forests”. Improved global representation and understanding of the ecology of mangroves in arid climates could help sustain their valuable ecosystem services.Full Tex
Les multiples facettes de l'entrepreneuriat scientifique de James Lovelock dans les années 1960-70 : développement d’instruments, consultance sur les pollutions et hypothèse Gaïa
No full textInternational audienceJames Lovelock (1919-…), a chemist famous for having elaborated the Gaia hypothesis, portrays himself as an "independent scientist" settled in a remote lab-house in the English countryside. Against this narrative, the authors describe Lovelock's life in the 1960s and 1970s as that of a "scientific entrepreneur". After twenty years as an engineer in a civil biomedical laboratory, Lovelock resigned to set up on his own. His skills as an expert in chromatography and as an engineer gifted for inventing chemistry instruments were so renowned that he rapidly became a highly demanded consultant, working both for major chemical and petroleum industries and for prestigious public scientific institutions. Obvious synergies, but also tensions, appear between his activities as an expert on environmental issues, his consulting work for industries, and his theoretical work giving birth to a new conception of Earth and life. Lovelock must not only be eventually regarded as one of the fathers of Earth system science and as an important contributor to cultural mutations linked to the environment from the 1960s onwards, but also as an early embodiment of a scientific entrepreneur with a foot in the world of public environmental research and the other in the world of industry.Chimiste célèbre pour avoir élaboré l'hypothèse Gaïa, James Lovelock (1919-…) se présente comme un « scientifique indépendant » installé dans son laboratoire-maison, retiré dans la campagne anglaise. À rebours de ce récit, les auteurs décrivent son parcours dans les années 1960-70 comme celui d'un « scientifique entrepreneur ». Après vingt ans comme ingénieur-fonctionnaire dans le domaine biomédical, Lovelock délaisse cette position pour s'établir à son compte. Son expertise dans le domaine de la chromatographie et l'invention d'instruments font de lui un consultant courtisé, aussi bien par de grandes entreprises chimiques et pétrolières que par de prestigieuses institutions scientifiques publiques. De grandes synergies, mais aussi des tensions, s'opèrent entre ses activités d'expert sur des questions environnementales, de consultant pour des entreprises et de théoricien élaborant une nouvelle conception de la Terre et de la vie. Lovelock ne doit plus uniquement être regardé comme l'un des pères des sciences du système Terre et un acteur important des mutations culturelles autour de l'environnement depuis les années 1960, mais également comme une incarnation précoce de scientifique entrepreneur avec un pied dans la recherche publique sur l'environnement et l'autre dans la recherche industrielle
The impact of P(NDI2OD-T2) crystalline domains on the open-circuit voltage of bilayer all-polymer solar cells with an inverted configuration
No full textWe fabricated P(NDI2OD-T2)/PTB7 bilayer all-polymer solar cells with an inverted configuration, where the annealing temperature was systematically varied. The current density-voltage behavior was investigated and the structural properties of the P(NDI2OD-T2) layers were characterized. Absorption spectroscopy, surface morphology, and crystallite analysis showed that increasing phase segregation of P(NDI2OD-T2) films occurred as the annealing temperature increased. We found that, as the P(NDI2OD-T2) stacking improved, with larger domains, the open-circuit voltage decreased and the saturation dark current density increased. This work provides a guide for the processing of P(NDI2OD-T2) layers to maximize the power conversion efficiency of all-polymer solar cells. (C) 2015 Author(s).open1186sciescopu
Data and code for: Variational Graph Author Topic Modeling
No full textThis is the tensorflow implementation of KDD-2022 paper "Variational Graph Author Topic Modeling" by Delvin Ce Zhang and Hady W. Lauw.
VGATM is a Graph Neural Network model that extracts interpretable topics for documents with authors and venues. Topics of documents then fulfill document classification, citation prediction, etc.
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Updated analytical solutions of continuity equation for electron beams precipitation – I. Pure collisional and pure ohmic energy losses
No full textWe present updated analytical solutions of continuity equations for power-law beam electrons precipitating in (a) purely collisional losses and (b) purely ohmic losses. The solutions of continuity equation (CE) normalized on electron density presented in Dobranskis & Zharkova are found by method of characteristics eliminating a mistake in the density characteristic pointed out by Emslie et al. The corrected electron beam differential densities (DD) for collisions are shown to have energy spectra with the index of −(γ + 1)/2, coinciding with the one derived from the inverse problem solution by Brown, while being lower by 1/2 than the index of −γ/2 obtained from CE for electron flux. This leads to a decrease of the index of mean electron spectra from −(γ − 2.5) (CE for flux) to −(γ − 2.0) (CE for electron density). The similar method is applied to CE for electrons precipitating in electric field induced by the beam itself. For the first time, the electron energy spectra are calculated for both constant and variable electric fields by using CE for electron density. We derive electron DD for precipitating electrons (moving towards the photosphere, μ = +1) and ‘returning’ electrons (moving towards the corona, μ = −1). The indices of DD energy spectra are reduced from −γ − 1 (CE for flux) to −γ (CE for electron density). While the index of mean electron spectra is increased by 0.5, from −γ + 0.5 (CE for flux) to −γ + 1(CE for electron density). Hard X-ray intensities are also calculated for relativistic cross-section for the updated differential spectra revealing closer resemblance to numerical Fokker–Planck (FP) solutions
Introduction and Author Biographical Notes
No full textThe Introductory Notes include The Cutting EDge\u27s mission statement, editorial board, founder\u27s note, and author\u27s biographies
From the Editors and Author Biographical Notes
No full textLetter from the Editors and Author Biographical Note
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