Search results for "Earth"
showing 10 items of 12204 documents
The Role of Excited Oxygen Molecules in the Formation of the Secondary Ozone Layer at 87 to 97 km
2018
The secondary ozone layer is located at elevations of 87 to 97 km in the upper mesosphere – lower thermosphere. It overlaps with the ionospheric D-layer. Daytime intensive UV radiation is dissociating O2 molecules to O atoms and photoexcitating O2 molecules up to 11.07eV level. Ozone photolysis between the wavelengths of 118.7–121.6 nm produces three oxygen atoms from one ozone molecule. Collision reactions of O2(B3 Σu —) and O2(X3 Σg —, υ≥26) with O2(X3 Σg —, υ=0) produce additional oxygen atoms. The number of oxygen atoms is maintained at such a high level that a small but significant ozone concentration survives. UV radiation weakens radically during the night. The number of O atoms show…
Stress sensitivity of stylolite morphology
2009
International audience; Stylolites are rough surfaces that form by localized stress-induced dissolution. Using a set of limestone rock samples collected at different depths from a vertical section in Cirque de Navacelles (France), we study the influence of the lithostatic stress on the stylolites morphology on the basis of a recent morphogenesis model. We measured the roughness of a series of bedding-parallel stylolites and show that their morphology exhibits a scaling invariance with two self-affine scaling regimes separated by a crossover-length (L) at the millimeter scale consistent with previous studies. The importance of the present contribution is to estimate the stylolite formation s…
Girls4STEM: Gender Diversity in STEM for a Sustainable Future
2020
Science, Technology, Engineering, and Mathematics (STEM) are key disciplines towards tackling the challenges related to the Sustainable Development Goals. However, evidence shows that women are enrolling in these disciplines in a smaller percentage than men, especially in Engineering related fields. As stated by the United Nations Women section, increasing the number of women studying and working in STEM fields is fundamental towards achieving better solutions to the global challenges, since the potential for innovation is larger. In this paper, we present the Girls4STEM project, which started in 2019 at the Escola Tè
Gaussian processes retrieval of crop traits in Google Earth Engine based on Sentinel-2 top-of-atmosphere data.
2022
The unprecedented availability of optical satellite data in cloud-based computing platforms, such as Google Earth Engine (GEE), opens new possibilities to develop crop trait retrieval models from the local to the planetary scale. Hybrid retrieval models are of interest to run in these platforms as they combine the advantages of physically-based radiative transfer models (RTM) with the flexibility of machine learning regression algorithms. Previous research with GEE primarily relied on processing bottom-of-atmosphere (BOA) reflectance data, which requires atmospheric correction. In the present study, we implemented hybrid models directly into GEE for processing Sentinel-2 (S2) Level-1C (L1C)…
Emulation of Sun-Induced Fluorescence from Radiance Data Recorded by the HyPlant Airborne Imaging Spectrometer
2021
The retrieval of sun-induced fluorescence (SIF) from hyperspectral radiance data grew to maturity with research activities around the FLuorescence EXplorer satellite mission FLEX, yet full-spectrum estimation methods such as the spectral fitting method (SFM) are computationally expensive. To bypass this computational load, this work aims to approximate the SFM-based SIF retrieval by means of statistical learning, i.e., emulation. While emulators emerged as fast surrogate models of simulators, the accuracy-speedup trade-offs are still to be analyzed when the emulation concept is applied to experimental data. We evaluated the possibility of approximating the SFM-like SIF output directly based…
Niche position drives interspecific variation in occupancy and abundance in a highly-connected lake system
2019
Highlights • We studied interspecific variation in occupancy and abundance of freshwater species. • Occupancy and abundance correlated positively for both diatoms and macroinvertebrates. • Niche position had clearest effects on variation in occupancy and abundance. • The more marginal the niche position, the rarer a species is. We examined how niche position, niche breadth, biological traits and taxonomic relatedness affect interspecific variation in occupancy and abundance of two commonly-used biological indicator groups, i.e. diatoms and macroinvertebrates. We studied 291 diatom and 103 macroinvertebrate species that occupied the littoral zones of a large (305 km2) highly-connected freshw…
Testing and implementing a new approach to estimating interregional output multipliers using input-output data for South Korean regions
2020
Flegg's location quotient (FLQ) is a useful tool for estimating intraregional output multipliers. This paper uses it as one component when estimating interregional multipliers. Using statistical information criteria and official data for 16 South Korean regions, it is found that the best approach is to combine the FLQ with a simple trade model. The paper explains how the proposed procedure can be implemented for both multiple and individual regions, and also how a region-specific value for the unknown parameter δ in the FLQ formula can be determined. Finally, an illustrative case study of one of the regions is carried out.
Impact of Different Washing Conditions on the Release of Ag Species from Textiles
2016
The paper investigates the Ag release from textiles (socks available in shops, cotton and viscose filled with Ag nanoparticles–AgNPs) into a washing solution under different conditions. The released Ag amount depended on various factors, such as test media (chemical composition, temperature and water volume), metal contents, and textile impregnation conditions. Furthermore, it turned out that the textile type and colour were the main parameters affecting the Ag release. The Ag concentration in the washing solution ranged between 0.015 μg/l and 4.44 μg/l (socks) and between 0.61 μg/l and 103 μg/l (AgNPs–filled cotton). The total Ag percentage released into water during one washing varied con…
Study of the Stability of Citrate Capped AgNPs in Several Environmental Water Matrices by Asymmetrical Flow Field Flow Fractionation
2021
Asymmetrical flow field-flow fractionation (AF4) coupled to UV-Vis and dynamic light scattering (DLS) detectors in series, was tested for stability studies of dispersions of citrate-capped silver nanoparticles (AgNPs) in several water matrices. The main goal is to provide knowledge to understand their possible behavior in the environment for short times since mixturing (up to 180 min). Ultrapure (UPW), bottled (BW1, BW2), tap (TW), transitional (TrW) and sea water (SW) matrices were assayed. Observations were compatible with the aggregation of AgNPs, a change in the plasmon band and a size growth with time were done. Fractograms showed different evolution fingerprints in the function of the…
Chimpanzees surviving in a fragmented high‐altitude forest landscape of the Congolese Albertine Rift
2021
This paper documents a community of eastern chimpanzees (Pan troglodytes schweinfurthii Giglioli, 1872) inhabiting three relict forest fragments situated on the Lake Albert escarpment, down the Ituri highlands, of eastern Democratic Republic of the Congo (DRC). The area explored had a combined forested surface of ±18.15 km2 in 2017, shrinking by 1.2% per year between 2010 and 2015. Between 2015 and 2017, we found 160 chimpanzee nests along 37.6 km of pilot walks, some up to 2,000 m altitude. Another 123 nests logged along 6.7 km transects led to an estimate of chimpanzee density of 4.62 weaned individuals per square kilometer of forest habitat. Camera‐trap images and direct observations rev…