Favier V. et D. Six. (2008). Rapport de mission glacioclim.
Abstract: Consultable sur http://www-lgge.obs.ujf-grenoble.fr/~christo/glacioclim/samba/
Programme: 411
|
|
Agosta, C. (2008).
|
Simon, N.S.C.; Neumann, E.-R.; Bonadiman, C.; Coltorti, M.; Delpech, G.; Gregoire, M.; Widom, E. (2008). Ultra-refractory Domains in the Oceanic Mantle Lithosphere Sampled as Mantle Xenoliths at Ocean Islands. Journal of petrology, 49(6), 1223–1251.
Abstract: Many peridotite xenoliths sampled at ocean islands appear to have strongly refractory major element and modal compositions. To better constrain the chemistry, abundance and origin of these ultra-refractory rocks we compiled a large number of data for xenoliths from nine groups of ocean islands. The xenoliths were filtered petrographically for signs of melt infiltration and modal metasomatism, and the samples affected by these processes were excluded. The xenolith suites from most ocean islands are dominated by ultra-refractory harzburgites. Exceptions are the Hawaii and Tahiti peridotites, which are more fertile and contain primary clinopyroxene, and the Cape Verde suite, which contains both ultra-refractory and more fertile xenoliths. Ultra-refractory harzburgites are characterized by the absence of primary clinopyroxene, low whole-rock Al2O3, CaO, FeO/MgO and heavy rare earth element (HREE) concentrations, low Al2O3 in orthopyroxene (generally < 3 wt %), high Cr-number in spinel (0{middle dot}3-0{middle dot}8) and high forsterite contents in olivine (averages > 91{middle dot}5). They are therefore on average significantly more refractory than peridotites dredged and drilled from mid-ocean ridges and fracture zones. Moreover, their compositions resemble those of oceanic forearc peridotites. The formation of ultra-refractory ocean island harzburgites requires potential temperatures above those normally observed at modern mid-ocean ridges, and/or fluid fluxed conditions. Some ultra-refractory ocean island harzburgites give high Os model ages (up to 3300 Ma), showing that their formation significantly pre-dates the oceanic crust in the area. A genetic relationship with the host plume is considered unlikely based on textural observations, equilibration temperatures and pressures, inferred physical properties, and the long-term depleted Os and Sr isotope compositions of some of the harzburgites. Although we do not exclude the possibility that some ultra-refractory ocean island harzburgites have formed at mid-ocean ridges, we favor a model in which they formed in a process spatially and temporally unrelated to the formation of the oceanic plate and the host plume. As a result of their whole-rock compositions, ultra-refractory harzburgites have a very high solidus temperature at a given pressure, low densities and very high viscosities, and will tend to accumulate at the top of the convecting mantle. They may be preserved as fragments in the convecting mantle over long periods of time and be preferentially incorporated into newly formed lithosphere.
Programme: 444
|
Talbot, D.A.; Duchamp, C.; Rey, B.; Hanuise, N.; Rouanet, J.L.; Sibille, B.; Brand, M.D. (2004). Uncoupling protein and ATP/ADP carrier increase mitochondrial proton conductance after cold adaptation of king penguins. J. Physiol. (Lond.), 558(1), 123–135.
Abstract: Juvenile king penguins develop adaptive thermogenesis after repeated immersion in cold water. However, the mechanisms of such metabolic adaptation in birds are unknown, as they lack brown adipose tissue and uncoupling protein-1 (UCP1), which mediate adaptive non-shivering thermogenesis in mammals. We used three different groups of juvenile king penguins to investigate the mitochondrial basis of avian adaptive thermogenesis . Skeletal muscle mitochondria isolated from penguins that had never been immersed in cold water showed no superoxide-stimulated proton conductance, indicating no functional avian UCP. Skeletal muscle mitochondria from penguins that had been either experimentally immersed or naturally adapted to cold water did possess functional avian UCP, demonstrated by a superoxide-stimulated, GDP-inhibitable proton conductance across their inner membrane. This was associated with a markedly greater abundance of avian UCP mRNA. In the presence (but not the absence) of fatty acids, these mitochondria also showed a greater adenine nucleotide translocase-catalysed proton conductance than those from never-immersed penguins. This was due to an increase in the amount of adenine nucleotide translocase. Therefore, adaptive thermogenesis in juvenile king penguins is linked to two separate mechanisms of uncoupling of oxidative phosphorylation in skeletal muscle mitochondria: increased proton transport activity of avian UCP (dependent on superoxide and inhibited by GDP) and increased proton transport activity of the adenine nucleotide translocase (dependent on fatty acids and inhibited by carboxyatractylate).
Programme: 131
|
Macelloni G., Paloscia S. et al. (2006). Assessment of instrument stability and calibration by using extended targets: Antarctic plateau (Dome-C) and forests.
Abstract: TUD Lingby May 15-17, 2006
available at http://www.cesbio.ups-tlse.fr/data_a
Programme: 1144
|
Casula, G.; Danesi, S.; Dubbini, M.; Vittuari, L. (2007). Tidal forcing on David Glacier and Drygalski Ice Tongue. The National Academy Press, Washington DC.
Abstract: During the 2005-06 Austral Summer, we carried out a joint observational campaign in the area of the David Glacier, South Victoria Land, with the aim of collecting simultaneous time series of geodetic and seismological data. We installed 7 temporary seismographic stations on rock outcrops surrounding the glacier and 3 temporary geodetic stations both on flowing ice and on rock. The seismic network registered a significant low-energy seismic activity, principally originated by ice creeping and basal stress at the interface between the ice and the bedrock. The geodetic stations allowed us to survey the glacier kinematics forced by the Ross Sea tides, and to infer the grounding line location. Here we show some details about data analysis and preliminary results.
Keywords: Antarctica; David Glacier; Tidal force; Geodetic observations; Seismicity
Programme: 906
|
|
Frezzotti M., Pourchet M., Flora O., Gandolfi S., Gay M., Urbini S., Vincent C., Becagli S., Gragnani R., Proposito M., Severi M.,Traversi R., Udisti R., Fily M. (2004). New estimations of precipitation and surface sublimation in East Antarctica from snow accumulation measurements,. Climate dynamics, 23, 803–813.
|
. (2004). Towards the Opening of a Magnetic Observatory at Dome C (Antarctica).
Keywords: Antarctica; Magnetic observatory; Dome C
Programme: 905
|
Schwarzenboeck, A.; Duroure, C.; Gayet, J.-F.; Herber, A.; Krecji, R.; Lefevre, R.; Minikin, A.; Neuber, R.; Shcherbakov, V.; Strm, J.; Yamagata, S.; Yamanouchi, T. (2004). Aerosol-Cloud Interaction during the Transition Time Period of Arctic Haze to Clean Summer Conditions. European Aerosol Conference 2004, 35. Budapest, (H).
Keywords: arctic aerosol; aerosol-cloud interaction; arctic mixed phase clouds; indirect aerosol effect
Programme: 430
|
Tougne, J.; Paty, B.; Meynard, D.; Martin, J.-M.; Letellier, T.; Rosnet, E. (2008). Group Problem Solving and Anxiety During a Simulated Mountaineering Ascent. Environment and behavior, 40(1), 3–23.
Abstract: Eight mountaineers were placed in a hypobaric chamber to simulate oxygen depletion accompanying a mountain ascent. The aim was to examine the evolution of individual and group efficiency in problem solving and anxiety according to simulated altitude. Relationships within the group, state and trait anxiety, and individual and collective performance in problem solving were repeatedly assessed at simulated altitudes of 5000m, 6000m, 7000m, and 8000m. The decrease of individual performance in problem solving, shown to be simultaneous to the increase of state anxiety, had little effect on collective performance in problem solving. These results suggest (a) that the collective success could be due to the emergence of a positive common goal and a positive appraisal of the situation and (b) that the state anxiety could act as a mediator between the variation in altitude and its effects on individual performance. The relevance of these results to real mountaineering expeditions is discussed.
Programme: 374;901
|
