140 research outputs found
Correction to " Saint-Santin Radar Observations of Lower Thermospheric Storms"
No full textInternational audienceIn the paper "Saint-Santin Radar Observations of Lower Thermospheric Storms" by C. Mazaudier, R. Bernard and S.V. Venkateswaran (Journal of Geophysical Research 90 (A3), 2885-2895) the name of the third author was inadvertently omitted from the first page. A corrected first page follow
A comment on the paper 'Solar activity and its influence on climate' Author C. de Jager Published in Netherlands Journal of Geosciences-Geologie en Mijnbouw, 87-3, pp 207213, 3 2008
No full textInternational audienceThe purpose of this comment is not to criticize the results obtained by Dr C. de Jager, and we agree for example with his prediction of the next sunspot cycle amplitude - 68 with σ= 17
A comment on the paper 'Solar activity and its influence on climate' Author C. de Jager Published in Netherlands Journal of Geosciences-Geologie en Mijnbouw, 87-3, pp 207213, 3 2008
No full textInternational audienceThe purpose of this comment is not to criticize the results obtained by Dr C. de Jager, and we agree for example with his prediction of the next sunspot cycle amplitude - 68 with σ= 17
On the oxidation of (U, Pu)C fuel: Experimental and kinetic aspects, practical issues
No full textInternational audienceThe oxidation of mixed (U, Pit) carbide fuel was studied to meet some of the general requirements applicable to the back- and front-end of the nuclear fuel cycle. Data are unfortunately scarce in this field. Based on an experimental study and a kinetic treatment, it was proved that the oxidation of solid or powdered mixed carbide fuel does not involve any unwanted kinetic transition and does not have the intrinsic ability to self-sustain. We never observed the formation of a protective oxide layer on the samples. The oxidation products were always low-density, finely-divided oxide powder expanding and tending to slow down the process. The low thermal activation observed demonstrates the key role of gas transport when using powders. Practical solutions have been derived from this work
Strange currents over Saint‐Santin
No full textInternational audienceAnalysis of 29 days of ionospheric current data obtained by Saint-Santin radar..
Strange Currents Over Saint-Santin
No full textInternational audienceAnalysis of 29 days of ionospheric current data obtained by Saint-Santin radar..
Lake Ohrid, Albania, provides an exceptional multi-proxy record of environmental changes during the last glacial-interglacial cycle
No full textMulti-proxy analyses on core JO2004-1 recovered from Lake Ohrid (40°55.000 N, 20°40.297E, 705 m a.s.l.)
provide the first environmental and climate reconstruction in a mountainous area in Southern Europe over
the last 140,000 years. The response of both lacustrine and terrestrial environments to climate change has
been amplified by the peculiar geomorphological and hydrological setting, with a steep altitudinal gradient
in the catchment and a karstic system feeding the lake. The karstic system was active during interglacials,
leading to high carbonate production in the lake, and blocked during glacials as a result of extremely cold
climate conditions with permafrost in the mountains. At the Riss–Eemian transition (Termination 2) the
increase in lacustrine productivity predated forest expansion by about 10,000 years. In contrast, the Late
Glacial–Holocene transition (Termination 1) was characterized by the dramatic impact of the Younger Dryas,
which initially prevented interglacial carbonate production and delayed its maximum until the mid-
Holocene. In contrast, forest expansion was progressive, starting as early as ca. 38,000 ago. The proximity of
high mountains and the probable moderating lake effect on local climate conditions promoted forest
expansion, and contributed to make the surroundings of Lake Ohrid favourable to forest refugia during the
last glacial, usually steppic, period. Our study of sedimentology, mineralogy, geochemistry, magnetics,
palynology and isotopes illustrates the non-linear response of terrestrial and lacustrine ecosystems to similar
climate events, and demonstrates the potential of Lake Ohrid as an excellent paleoclimatic archive during the Quaternary
Low Temperature Oxidation of pure Iron : Growth kinetics and scale Morphologies
No full textIsothermal oxidation of pure iron has been performed in air at atmospheric pressure between 260°C and 500°C. Growth kinetics are accurately analysed and scale morphologies are investigated by SEM and TEM observations. The calculation of the variations of the parabolic rate constant kp with scale thickness allows a better understanding of scale growth mechanisms involved at this intermediate temperature range, which have been poorly investigated up to now. These results are discussed with the objective of long term behaviour for long term interim storage of some nuclear waste containers
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