Search results for "angling"
showing 10 items of 99 documents
Disentangling scattered charcoal assemblages for palimpsest dissection: Spatial analyses from El Salt Stratigraphic Unit Xb (Eastern Iberia)
2017
International audience; Disentangling scattered charcoal assemblages for palimpsest dissection: spatial analyses from El Salt Stratigraphic unit Xb (Eastern Iberia)
El marcaje revela un intercambio limitado de inmaduros de tortuga boba (Caretta caretta) entre regiones en el Mediterráneo occidental
2008
El marcaje revela un intercambio limitado de inmaduros de tortuga boba (Caretta caretta) entre regiones en el Mediterráneo occidental. – Se investigó el intercambio de inmaduros de tortuga boba (Caretta caretta) entre las regiones septentrional y meridional del Mediterráneo occidental a partir de los datos obtenidos por varios programas españoles de marcaje. El rango de la longitud recta de caparazón de las tortugas marcadas fue de 23 a 74 cm. 36 de ellas se recapturaron tras un intervalo medio de 390,5±462,6 días (DS). Como la distancia media de dispersión (MDD) de una población de tortugas que se dispersan por el Mediterráneo occidental se estabilizaría al cabo de 117 días (IC 95%: 98-149…
Defects in oxide glasses
2005
An insight into the present understanding of point defects in the simplest and the most radiation-resistant oxide glass, glassy silicon dioxide (silica) is presented. The defects and their generation processes in glassy and α-quartz forms of silicon dioxide are significantly different. The only defect, confirmed to be similar in both materials, is oxygen vacancy. In silica, additional defects of dangling bond type are generated from precursor sites formed by strained Si-O bonds, and by modifier ions. The optical absorption spectra of silica are dominated by paramagnetic dangling bond type defects: silicon dangling bond (“E′-center”) and oxygen dangling bond (“non-bridging oxygen hole center…
Computer Simulation of Molten and Glassy Silica and its Mixtures with Sodium Oxide and Aluminium Oxide
2007
A STUDY ON THE POSSIBLE EFFECT OF TWO CRAYFISH SPECIES ON EPILITHIC ALGAE IN A MOUNTAIN STREAM FROM CENTRAL SPAIN
2006
The effects on epilithic algae of increasing densities of two crayfish species, Austropotamobius italicus and Pacifastacus leniusculus, the latter recently introduced in Spain, have been monitored using riverine enclosures, within a large experimental study on crayfish-macrobenthos interactions in a mountain stream. A 3-month test was carried out for each species using crayfish densities comprising between 0-5 individuals/m2 kept in 1-m2 enclosures. Epilithon was sampled periodically within the enclosures and chlorophyll a, b and c were measured by spectrophotometry. Neither statistically significant positive nor negative effects were observed on algal abundance (Chl concentrations) during …
Modifications of optical absorption band of E'gamma center in silica
2005
We report a study by electron paramagnetic resonance on the E0 point defect in amorphous silicon dioxide (a-SiO2). Our experiments were performed on -ray irradiated oxygen-deficient materials and pointed out that the 29Si hyperfine structure of the E0 consists of a pair of lines split by 49 mT. On the basis of the experimental results, a microscopic model is proposed for the E0 center, consisting of a hole trapped in an oxygen vacancy with the unpaired electron sp3 orbital pointing away from the vacancy in a back-projected configuration and interacting with an extra oxygen atom of the a-SiO2 matrix.
29Si Hyperfine structure of the E’_alfa center in amorphous silicon dioxide
2006
We report a study by electron paramagnetic resonance on the E0 point defect in amorphous silicon dioxide (a-SiO2). Our experiments were performed on -ray irradiated oxygen-deficient materials and pointed out that the 29Si hyperfine structure of the E0 consists of a pair of lines split by 49 mT. On the basis of the experimental results, a microscopic model is proposed for the E0 center, consisting of a hole trapped in an oxygen vacancy with the unpaired electron sp3 orbital pointing away from the vacancy in a back-projected configuration and interacting with an extra oxygen atom of the a-SiO2 matrix.
Characterization of E'delta and triplet point defects in oxygen-deficient amorphous silicon dioxide
2005
We report an experimental study by electron paramagnetic resonance (EPR) of gamma ray irradiation induced point defects in oxygen deficient amorphous SiO2 materials. We have found that three intrinsic (E'gamma, E'delta and triplet) and one extrinsic ([AlO4]0) paramagnetic centers are induced. All the paramagnetic defects but E'gamma center are found to reach a concentration limit value for doses above 10^3 kGy, suggesting a generation process from precursors. Isochronal thermal treatments of a sample irradiated at 10^3 kGy have shown that for T>500 K the concentrations of E'gamma and E'delta centers increase concomitantly to the decrease of [AlO4]0. This occurrence speaks for an hole tra…
Oxidation-Induced Changes in the ALD-Al2O3/InAs(100) Interface and Control of the Changes for Device Processing
2018
InAs crystals are emerging materials for various devices like radio frequency transistors and infrared sensors. Control of oxidation-induced changes is essential for decreasing amounts of the harmful InAs surface (or interface) defects because it is hard to avoid the energetically favored oxidation of InAs surface parts in device processing. We have characterized atomic-layer-deposition (ALD) grown Al2O3/InAs interfaces, preoxidized differently, with synchrotron hard X-ray photoelectron spectroscopy (HAXPES), low-energy electron diffraction, scanning tunneling microscopy, and time-of-flight elastic recoil detection analysis. The chemical environment and core-level shifts are clarified for w…
Creation of glass-characteristic point defects in crystalline SiO2 by 2.5 MeV electrons and by fast neutrons
2019
The support from M -ERANET project “MyND” is acknowledged. K.K. was partially supported by the Collaborative Research Project of Laboratory for Materials and Structures, Tokyo Institute of Technology . Visiting researcher support from Ecole Polytechnique, Palaiseau is appreciated. Mr. Olivier Cavani is thanked for the expert help with irradiations.