Résumé : (Biographical) Jorge L. Quijano is the CEO of the Panama Canal Authority, the autonomous agency that manages the Panama Canal, the leading interoceanic waterway that serves world maritime commerce. He started his career with the Panama Canal in 1975 and climbed through the professional and managerial promotion ladder to the position of Maritime Operations Director in 1999, the largest department of the Canal organization, directly involved in the operation and maintenance of the principal infrastructure and equipment of the waterway. In September 2006, was designated to manage the Panama Canal’s $5.25 billion Expansion Program; and to that effect, he was appointed Executive Vice President of the Engineering and Programs Management Department. Jorge L. Quijano is the recipient of international awards for his achievements and contributions to the world maritime industry. These are the following: The “Texas Industrial Engineering Lifetime Achievement Award” presented on February 15, 2013 by Dr. Brian Craig, chair of the Department of Industrial Engineering of the College of Engineering at Lamar University and “Honorary Citizen of Texas,” presented on February 15, 2013 by the Texas Senate.

Droits : Permission granted to University of Florida to digitize and display this item for non-profit research and educational purposes. Any reuse of this item in excess of fair use or other copyright exemptions requires permission of the copyright holder.
http://ufdc.ufl.edu/AA00024620/00001

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
TEM Study of Heavitree quartzite deformed at high temperatures and a pressure of 1.5 GPa with three different preparations: water-added, vacuum dried, and sodium doped show a wide range of dislocation microstructure. The vacuum dried sample has a very heterogeneous dislocation distribution varying from almost no dislocations to very high densities. Dislocation nucleation occurs by cross-slip mechanisms, such as Frank-Read sources and Orowan loops around hard inclusions. Shear bands develop in the basal plane composed of two closely spaced shear planes. Dislocations have straight segments and they are aligned along directions of dense packing, suggesting strong Peierls stress control due to the crystal structure. No voids, bubbles or dislocation walls where observed in the vacuum dried sample. The sodium-doped sample had a homogeneous high dislocation density. The water-added sample has a significantly lower, relatively uniform dislocation density. Bubbles associated with dislocations are seen in every grain. Dislocations were either present in loops around bubbles or as straight dislocations with small bubbles spaced along the dislocation line. Some of the long straight dislocations are aligned parallel to the c-axis. Sub-grains where very frequent, sometimes form cells of about 2 p,m in diameter with straight edges. Analysis of dislocations show 1/3 < a > and [c] dislocations in sub-grain walls and free 1/3 < a > dislocations on prism planes. There is clear evidence for dislocation climb with sub-grain walls, dislocation cells, dislocation junctions and dislocation debris of small loops. The major difference between vacuum dried and water-added samples are the homogeneity of the microstructure and evidence for climb in the water-added sample. Glide is clearly difficult, with a high Peierls stress in the vacuum dried sample as shown by areas of very low and very high dislocation density and the crystallographic control of dislocation line direction. The sodium-doped sample indicates that nucleation was easy by the high homogenous dislocation density, but no climb recovery has taken place. The density is high and the dislocations are strongly interacting causing tangles; no evidence for crystallographic control can be observed at these levels of strain. The activation energy for creep in Heavitree quartzite decreases with inferred water content of the specimens form 185 kJ mol(-1) for vacuum dried to 151 for 0.4 wt% water-added samples. Analysis of diffusion data for oxygen under hydrothermal conditions and inferred diffusion data for the hydrogarnet defect and dislocation velocity suggests activation energies for these processes are similar to the activation energy for the dislocation creep of Heavitree quartzite and other quartz aggregates. For data from the previously published experiments with the highest stress resolution there is a correlation between the A pre-factor in the power law creep equation and the activation energy for creep. It is speculated that the correlation may be due to variable hydrogarnet defect concentrations.
ISSN: 0031-9201

hal-00413112
https://hal.archives-ouvertes.fr/hal-00413112
DOI : 10.1016/j.pepi.2008.07.009

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Transmission electron microscopy observations on olivine crystals deformed at moderate (≤1273 K) temperature evidenced dislocations interactions explaining the hardening observed in the experiments, but also recovery mechanisms by the absorption or emission of point defects. Thus we investigate the possibility that, at geological strain-rates, these recovery processes allow steady-state deformation by dislocation creep at low to moderate temperatures in the lithospheric mantle. We test this hypothesis using a 2.5-D dislocation dynamics (DD) model, which combines dislocation glide and recovery by climb. This model shows that diffusion-controlled recovery processes allow for steady-state deformation by dislocation creep in the lithospheric mantle at stresses <500 MPa. For stresses of 50–200 MPa, steady-state strain-rates of 10−15 s−110−15 s−1 may be attained at temperatures as low as 900 K. Fitting of the DD model produces a flow law, which represents a lower bound for the lithospheric mantle strength, since the models describe the deformation of an olivine single crystal in an easy slip orientation. Comparison of strain-rates and Moho temperatures inferred for different geodynamic environments and the predictions of this model-based flow law implies, nevertheless, that, except in incipient rifts, most of the observed deformation may be produced by stress levels ≤200 MPa, consistent with those inferred to be produced by convection. This convergence suggests that the present models, which explicitly calculate the time-dependent dislocation dynamics, may provide a correct first order estimate of the mechanical behaviour of the lithospheric mantle, which cannot be derived directly from any existing data.
ISSN: 0012-821X

hal-01277178
https://hal.archives-ouvertes.fr/hal-01277178
https://hal.archives-ouvertes.fr/hal-01277178/document
https://hal.archives-ouvertes.fr/hal-01277178/file/Boioli.pdf
DOI : 10.1016/j.epsl.2015.10.012

Résumé : Trepadora herbácea con tallo de 5 a 6 m acostillado. Hojas biternadas, folíolos aovados o lanceolados, agudos o acuminados, dentados o lobulados. Inflorescencia umbeliforme con largos pedúnculos y flores blancas de 4 a 5 mm. Cápsula subglobosa de 3 a 4 cm; semillas negras de 4 a 5 mm.
Plante grimpante herbacée, tige 5 à 6 m, à côtes. Feuilles à 6 folioles groupées par trois ovalées ou lancéolées, aiguës ou acuminées, dentées ou lobulées. Inflorescence ombelliforme avec longs pédoncules et fleurs blanchesde 4 à 5 mm. Capsule presque arrondie de 3 à 4 cm; graines noires de 4 à 5 mm.
Climbing shrub 3 (-6 m) high.  Leaves alternate up to 12 cm long, compound, blade pellucid-dotted, leaflets 5 cm x 2.5 cm, ovate-elliptical, acute-tipped; inflorescence corymbose; flowers white, 4-petals, 4-6 mm long; fruit sub-globose, 3-angled much inflated capsule, 2.5-3 cm in length and width; seeds black, 4-5 mm long with white aril.
Ampliamente distribuida en trópicos y subtrópicos del nuevo y viejo mundo.
Largement distribuée dans les régions tropicales et subtropicales du Nouveau et de l&rsquo;Ancien Monde.
Widely distributed in tropical and subtropical regions of t

http://www.tramil.net/fototeca/plant31

Résumé : Planta trepadora, glabra con zarcillos; ramas articuladas. Hojas alternas, simples, oblongas a aovadas, de hasta 15 cm, densamente pilosas a glabras, con el margen ligeramente dentado. Cimas pedunculadas, amarillas, muy ramificadas; flores pequeñas, verdes o amarillo-verdosas. Baya ovoide o globosa, purpúrea a negra, de 8 a 10 mm, con una sola semilla.
Plante grimpante, glabre avec vrilles; branches articulées. Feuilles alternes, simples, oblongues à ovées, pouvant atteindre 15 cm, fortement pileuses à glabres, au bord légèrement denté. Cimes pédonculées, jaunes, très ramifiées; fleurs petites, vertes ou jaune-verdâtre. Baie ovoïde ou arrondie, pourpre à noire, de 8 à 10 mm, avec une seule graine.
Climbing plant up to 20 m or more, glabrous with tendril; stem cylindrical often with hanging roots, branches articulate.  Leaves alternate, simple, oblong to ovate, 5-15 cm x 7.5 cm, hairy to smooth, with slightly dentate edge. Inflorescence a cyme two-three times branched; flowers light yellow; fruits a berry, purple-black, 8-10 mm long, with a single seed.
Regiones tropicales del continente americano.
Régions tropicales du continent américain.
Tropical regions of the American continent.

http://www.tramil.net/fototeca/plant126

Résumé : Trepadora leñosa. Hojas aovadas a lanceoladas, acuminadas o agudas, de 6 a 18 cm. Inflorescencias axilares o terminales de hasta 20 cm; flores de 3 a 4 mm; sépalos blancos o verdosos, ovales a oblongos. Utrículo globoso a ovoideo de 4 a 5 mm de longitud; semilla lenticular o reniforme de color negro.
Plante grimpante ligneuse. Feuilles ovalées à lancéolées, acuminées ou en pointe, de 6 à 18 cm. Inflorescences axillaires ou terminales pouvant atteindre 20 cm; fleurs de 3 à 4 mm; sépales blancs ou verdâtres, ovales à oblongs. Fruit : utricule globuleux à ovoïde de 4 à 5 mm de longueur; graine lenticulaire ou réniforme de couleur noire.
Low weedy shrub or climbing vine up to 25 m with stem ca. 3 cm thick, older stems ribbed. Leaves alternate, elliptical to lanceolate 6-14 cm x 8 cm; inflorescence a panicle; flowers, greenish-yellow, 3-4 mm.; fruit a 1-seeded utricle (bladder- like), seeds black, discoid, enveloped in a blue translucent aril.    
América tropical.
Amérique tropicale.
Tropical America.  

http://www.tramil.net/fototeca/plant119

Résumé : Hierba trepadora de hasta 6 m, usualmente muy ramificada. Hojas alternas de 4 a 12 cm, 5-7 lobadas; lóbulos obtusos o mucronulados con márgenes dentados o crenados. Corola amarilla, segmentos obtusos o emarginados de 1.5 a 2 cm. Fruto elipsoide, tuberculado, dehiscente, de 5 a 15 cm de diámetro, de amarillo a anaranjado, con 3 valvas; pulpa de color rojo; semillas elípticas, planas, de 10 a 16 mm.
Herbe grimpante pouvant atteindre 6 m, habituellement très ramifiée. Feuilles alternes de 4 à 12 cm, avec 5-7 lobes; lobes obtus ou mucronés, bords dentés ou crénelés. Corolle jaune, segments obtus ou émargés de 1,5 à 2 cm. Fruit ellipsoïdal, tuberculé, déhiscent, de 5 à 15 cm de diamètre, jaune à orangé, avec 3 valves; pulpe de couleur rouge; graines ellipsoïdales, aplaties, de 10 à 16 mm.
Climbing dioecious herb 6 m or more, usually densely branchedwith tendrils.  Leaves alternate, simple 4-12 cm long, deeply5-7 lobed,sinuate with mucronate tips; inflorescence a raceme; female and male flowers yellow, peduncle shorter on female flower, bracts on male peduncle reniform to rounded-cordate; fruit cylindrical, narrowed at both ends, 8-15 cm long, prominent tubercles on the ribs, orange when ripe containing pendulous seeds covered in a red pulp; seed oblong 12-16 mm x 5-9 mm and 3-4 mm thick.
Originaria del Viejo Mundo y naturalizada en todos los trópicos.
Originaire de l’;Ancien Monde et naturalisée sous tous les tropiques.
Native to the Old World and naturalized in all tropical regions.

http://www.tramil.net/fototeca/plant232

Éditeur(s) : HAL CCSD Geological Society of London
Résumé : We have applied transmission electron microscopy (TEM) analyses coupled with viscoplastic self-consistent (VPSC) numerical modelling to identify the active slip systems and to better understand the crystal preferred orientation (CPO) development of the Torridon quartz mylonite (NW Scotland). TEM analyses showed evidence of activation of 1/3〈a〉{π′}, 1/3〈a〉{z} and possible 〈a〉(c) slip systems, as well as dislocation climb and dynamic recrystallization. All the CPOs generated by VPSC models share common characteristics with the Torridon quartz mylonite, but only Models 2 and 3 reproduce the [c]-axes maxima at low angle (<20°) to the foliation pole along the YZ plane, as observed in the mylonite. In Model 2, this concentration only occurs at γ≥2.6, whereas in Model 3 this maxima occurs at lower shear strains. The models that start with a previous preferred orientation acquire very strong CPOs after small-imposed strains, followed by the rapid rotation of the fabric in relation to the new imposed finite strain axes. The combined activation of 〈a〉{π′}, 〈a〉{z} and possibly 〈a〉(c) slip systems, as demonstrated by TEM analyses, suggests that the VPSC model that best predicts CPO development in the Torridon quartz mylonite is Model 2, where the critical resolved shear stress (CRSS) of 〈a〉{π/π′} is assumed to be slightly stronger than 〈a〉(c).
Deformation Mechanisms, Rheology and Tectonics: Microstructures, Mechanics and Anisotropy

hal-00688840
https://hal.archives-ouvertes.fr/hal-00688840

Éditeur(s) : HAL CCSD Springer Verlag
Résumé : International audience
Zelus annulosus is an assassin bug species mostly noted on Hirtella physophora, a myrmecophyte specifically associated with the ant Allomerus decemarticulatus known to build traps on host tree twigs to ambush insect preys. The Z. annulosus females lay egg clutches protected by a sticky substance. To avoid being trapped, the first three instars of nymphs remain grouped in a clutch beneath the leaves on which they hatched, yet from time to time, they climb onto the upper side to group ambush preys. Long-distance prey detection permits these bugs to capture flying or jumping insects that alight on their leaves. Like some other Zelus species, the sticky substance of the sundew setae on their forelegs aids in prey capture. Group ambushing permits early instars to capture insects that they then share or not depending on prey size and the hunger of the successful nymphs. Fourth and fifth instars, with greater needs, rather ambush solitarily on different host tree leaves, but attract siblings to share large preys. Communal feeding permits faster prey consumption, enabling small nymphs to return sooner to the shelter of their leaves. By improving the regularity of feeding for each nymph, it likely regulates nymphal development, synchronizing molting and subsequently limiting cannibalism.
ISSN: 0028-1042

hal-01091981
https://hal.archives-ouvertes.fr/hal-01091981
https://hal.archives-ouvertes.fr/hal-01091981/document
https://hal.archives-ouvertes.fr/hal-01091981/file/Dejean_11543.pdf
DOI : 10.1007/s00114-013-1091-9

Éditeur(s) : Cushman Foundation for Foraminiferal Research
Résumé : The objectives of this study were to observe foraminiferal colonization patterns and behavior in shrimp ponds in New Caledonia during a shrimp-growing (farming) cycle. Weekly collecting at 10 stations in 8 shrimp ponds yielded a total of 170 samples accompanied by environmental data. Seawater pumped from the nearby ocean filled the ponds at the beginning of the growth cycle and its daily renewal maintained salinity at 32-39, and supplied the ponds with influxes of smaller, mostly juvenile, foraminifera. A few days after initial filling, the pioneering species Ammonia tepida and Quinqueloculina seminula appeared, with A. tepida dominant. Their high reproduction rates increased both living and dead assemblage densities during the first 10 weeks. Populations of these two species then stabilized with higher oxygen demand (drop of redox) and consumption of living foraminifera by shrimp. Only a few colonizers subsequently appeared, which was attributed to the isolation of the pond, despite the high rate of water renewal. Only one pond had notably higher species richness, but it could not be distinguished from the others by its physicochemical parameters. The species that appeared in ponds initially barren of foraminifera also survived where there was water seepage between growing cycles, suggesting that the assemblages had already reached equilibrium with the environment. Despite the number of environmental parameters measured, only oxygen and reactive organic matter correlated with the microfauna on a weekly timescale. We assume that other parameters do not significantly affect foraminifera until they reach critical threshold. Consistent with previous studies, A. tepida was the species most tolerant of organic influx, but its relative abundance dropped once the organic matter flocculated and settled, leading to disoxic conditions in the sediment. Conversely, Q. seminula was able to climb through the floc and reach the oxygenated layer, where its relative abundance increased.
Journal of Foraminiferal Research (0096-1191) (Cushman Foundation for Foraminiferal Research), 2009-10 , Vol. 39 , N. 4 , P. 249-266

Droits : 2009 Cushman Foundation for Foraminiferal Research
http://archimer.ifremer.fr/doc/2009/publication-6954.pdf
DOI:10.2113/gsjfr.39.4.249
http://archimer.ifremer.fr/doc/00000/6954/

Éditeur(s) : HAL CCSD Public Library of Science
Résumé : International audience
Domestication can influence many functional traits in plants, from overall life-history and growth form to wood density and cell wall ultrastructure. Such changes can increase fitness of the domesticate in agricultural environments but may negatively affect survival in the wild. We studied effects of domestication on stem biomechanics in manioc by comparing domesticated and ancestral wild taxa from two different regions of greater Amazonia. We compared mechanical properties, tissue organisation and wood characteristics including microfibril angles in both wild and domesticated plants, each growing in two different habitats (forest or savannah) and varying in growth form (shrub or liana). Wild taxa grew as shrubs in open savannah but as lianas in overgrown and forested habitats. Growth form plasticity was retained in domesticated manioc. However, stems of the domesticate showed brittle failure. Wild plants differed in mechanical architecture between shrub and liana phenotypes, a difference that diminished between shrubs and lianas of the domesticate. Stems of wild plants were generally stiffer, failed at higher bending stresses and were less prone to brittle fracture compared with shrub and liana phenotypes of the domesticate. Biomechanical differences between stems of wild and domesticated plants were mainly due to changes in wood density and cellulose microfibril angle rather than changes in secondary growth or tissue geometry. Domestication did not significantly modify "large-scale" trait development or growth form plasticity, since both wild and domesticated manioc can develop as shrubs or lianas. However, "finer-scale" developmental traits crucial to mechanical stability and thus ecological success of the plant were significantly modified. This profoundly influenced the likelihood of brittle failure, particularly in long climbing stems, thereby also influencing the survival of the domesticate in natural situations vulnerable to mechanical perturbation. We discuss the different selective pressures that could explain evolutionary modifications of stem biomechanical properties under domestication in manioc.
PLoS ONE

halsde-00917926
https://hal.archives-ouvertes.fr/halsde-00917926
https://hal.archives-ouvertes.fr/halsde-00917926/document
DOI : 10.1371/journal.pone.0074727

Éditeur(s) : HAL CCSD American Geophysical Union
Résumé : During the 2003 summer monsoon, the Hi-CLIMB seismological stations deployed across the Himalayan Range detected bursts of high-frequency seismic noise that lasted several hours to days. On the basis of the cross correlation of seismic envelopes recorded at 11 stations, we show that the largest transient event on 15 August was located nearby a village partially destroyed on that day by a devastating debris flow. This consistency in both space and time suggests that high-frequency seismic noise analysis can be used to monitor debris flow generation as well as the evacuation of the sediment. A systematic study of one year of seismic noise, focusing on the detection of similar events, provides information on the spatial and temporal occurrence of mass movements at the front of the Himalayas. With a 50% probability of occurrence of a daily event, a total of 46 debris flows are seismically detected. Most of them were generated in regions of steep slopes, large gullies, and loose soils during the 2003 summer monsoon storms. These events are compared to local meteorological data to determine rainfall thresholds for slope failures, including the cumulative rainfall needed to bring the soil moisture content to failure capacity. The inferred thresholds are consistent with previous estimates deduced from soil studies as well as sediment supply investigations in the area. These results point out the potential of using seismic noise as a dedicated tool for monitoring the spatiotemporal occurrence of landslides and debris flows on a regional scale.
ISSN: 0148-0227

hal-00464177
https://hal.archives-ouvertes.fr/hal-00464177
DOI : 10.1029/2008JF001198

Éditeur(s) : HAL CCSD Taylor & Francis: STM, Behavioural Science and Public Health Titles
Résumé : International audience
The dislocation microstructures in a single crystal of olivine deformed experimentally in uniaxial compression at 1090 °C and under a confining pressure of 300 MPa, have been investigated by transmission electron tomography in order to better understand deformation mechanisms at the microscale relevant for lithospheric mantle deformations. Investigation by electron tomography reveals microstructures, which are more complex than previously described, composed of and dislocations commonly exhibiting 3D configurations. Numerous mechanisms such as climb, cross-slip, double cross-slip as well as interactions like junction formations and collinear annihilations are the source of this complexity. The diversity observed advocates for microscale deformation of olivine significantly less simple than classic dislocation creep reported in metals or ice close to melting temperature. Deciphering mechanism of hardening in olivine at temperatures where ionic diffusion is slow and is then expected to play very little role is crucial to better understand and thus model deformation at larger scale and at temperatures (900–1100 °C) highly relevant for the lithospheric mantle.
ISSN: 1478-6443

hal-01667146
https://hal.archives-ouvertes.fr/hal-01667146
DOI : 10.1080/14786435.2017.1367858

Éditeur(s) : HAL CCSD American Geophysical Union
Résumé : International audience
Analysis of continuous seismic data recorded by a dense passive seismological network (Hi-CLIMB) installed across the Himalayas reveals strong spatial and temporal variations in the ambient seismic energy produced at high frequencies (>1 Hz). From June to September 2003, the high-frequency seismic noise is observed to increase up to 20 dB (relative to (m/s)(2)/Hz) for all the stations located along a steep 30-km-long narrow and deeply incised channel of the Trisuli River, a major trans-Himalayan river. The early summer increase in high-frequency energy is modulated by a 24-h periodicity where the minimum of seismic noise level is reached around noon and the maximum is reached late in the evening. A detailed study of seismic noise amplitude reveals a clear correlation with both regional meteorological and hydrological data along the Trisuli River. Seasonal increase in ambient noise coincides with the strong monsoon rainfall and a period of rapid melting of snow and ice in the high elevations. The observed 24-h cyclicity is consistent with the daily fluctuation of the precipitation and river discharge in the region. River-induced seismic noise is partly generated by stream turbulence, but this mechanism fails to explain the observed clockwise hysteresis of seismic noise amplitude versus water level. This pattern is better explained if a significant part of the observed seismic noise is caused by ground vibrations generated by bed load transport. This points out the potential of using background seismic noise to quantify in continuous river bed load and monitor its spatial variations, which remain difficult with classical approaches.
ISSN: 2169-9313

hal-00412170
https://hal.archives-ouvertes.fr/hal-00412170
DOI : 10.1029/2007JB005034

Éditeur(s) : HAL CCSD Oxford University Press (OUP)
Résumé : International audience
Our knowledge and understanding of the 3-D lithospheric structure of the Himalayas and the Tibetan Plateau is still challenging although numerous geophysical studies have been performed in the region. The GOCE satellite mission has the ambitious goal of mapping Earth's gravity field with unprecedented precision (i.e. an accuracy of 1-2 mGal for a spatial resolution of 100 km) to observe the lithosphere and upper-mantle structure. Consequently, it gives new insights in the lithospheric structure beneath the Himalayas and the Tibetan Plateau. Indeed, the GOCE gravity data now allow us to develop a new strategy for joint gravimetry-seismology inversion. Combined with teleseismic data over a large region in a joint inversion scheme, they will lead to lithospheric velocity-density models constrained in two complementary ways. We apply this joint inversion scheme to the Hi-CLIMB (Himalayan-Tibetan Continental Lithosphere during Mountain Building) seismological network which was deployed in South Tibet and the Himalayas for a 3-yr period. The large size of the network, the high quality of the seismological data and the new GOCE gravity data set allow us to image the entire lithosphere of this active area in an innovative way. We image 3-D low velocity and density structures in the middle crust that fit the location of discontinuous low S-velocity zones revealed by receiver functions in previous geophysical studies. In the deeper parts of our velocity model we image a positive anomaly interpreted to be the heterogenous Indian lithosphere vertically descending beneath the centre of the Tibetan Plateau.
ISSN: 0956-540X

hal-00858024
https://hal.archives-ouvertes.fr/hal-00858024
DOI : 10.1093/gji/ggs110

Éditeur(s) : HAL CCSD Elsevier
Résumé : International audience
Fromthe Proterozoic to the Quaternary, the evolution of the Earthwas characterised by recurrent periods of glaciation.However, the margins of many ancient ice-sheets are poorly defined on palaeogeographic reconstructions.The extent and outlines of ancient ice sheets can be better understood through careful documentation ofsediments deposited at the ice-sheet margin. An outstanding example is provided herein based on an end-Ordovician archive in Libya (Tihemboka area, Murzuq Basin). The four sets of structures include: i) subglacialglaciotectonic structures and soft sediment deformations from flowing glacier ice, such as intraformational glacialstriae, intraformational deformation (shear planes, sheath folds), normal microfaults, and large-scaleglaciotectonic folds-and-thrusts; (ii) structures resulting from overpressured subglacial (meltwater) flowssuch as clastic dykes and tunnel valleys; (iii) proglacial depositional structures and facies related to highmagnitudemeltwater floods such as sandstone intraclasts, large-scale bedforms resulting from supercriticalflows, climbing-dune cross-stratification and kettle holes; and (iv) deformation structures resulting from freefloating and nonglacier ice such as ice-keel scours and ice-crystal marks. Such a set of structures points to anice-marginal (essentially continental) depositional setting, and provides an excellent suite of criteria to identifymargins of ancient ice sheets in the stratigraphic record. At a regional scale, a reconstruction through time andspace of the related depositional wedge is proposed. This corresponded to a seismic-scale (N120 m in thickness,40 km in length) ice-marginal wedge in front of an essentially warm-based ice-sheet inducing concomitantlarge-scale glaciotectonic deformation, glacial basin and tunnel valley downcuttings. The related ice-front wasassociated with high-energy meltwater flows feeding a network of deeply incised proglacial channels downstreamand, beyond them, a fluvioglacial deltaic system. Shallow ice-marginal permafrost most likely affectedthe depositional wedge. At a larger scale, the Tihemboka ice-marginal wedge is interpreted as related to a stillstandperiod over the Gondwana platform, developed over an estimated interval of a few thousands of years.Based on these data, the conditions that arose in a particularly favourable context for the development, the preservationand the identification of ice-marginal wedges in the geological record are reviewed. Significantmeltwater-derived sediment deposition and aggradation in an accommodation space resulting either frompreglacial inheritance, glacial downcuttings and/or glacio-isostatic lithospheric flexure, or active tectonic subsidence(>1 Myr) are required for their formation and subsequent preservation.
ISSN: 0012-8252

insu-01184739
https://hal-insu.archives-ouvertes.fr/insu-01184739
DOI : 10.1016/j.earscirev.2015.06.006

Éditeur(s) : HAL CCSD Geological Society of London
Résumé : International audience
Low-velocity zones ('bright spots') imaged by the INDEPTH seismic experiment in southern Tibet are extensively interpreted as widespread partial melt within the crust, which has given a strong support for the channel flow model. These suggest that a continuous seismic low-velocity zone underlies Tibet on the large scale. Here we take advantage of the Hi-CLIMB seismic experiment which includes a dense south-north profile and a lateral 2D seismic network to assess the vertical and the horizontal extension of low-velocity zones in southern Tibet. Several approaches including migration, amplitude analysis and waveform inversion of receiver functions are performed to detect crustal low-velocity zones using this new seismological dataset. Our results reveal localized and discontinuous low-velocity zones in Tibet. They indicate that the vertical extension of the low-velocity zones is about 10 km, and their maximum horizontal length appears to be c. 50 km. Our study suggests a partial correlation between the location of these low-velocity zones and the spatial distribution of Tibetan grabens. These results, especially the non-continuity of low-velocity zones, together with the observed regular value of mean crustal VP/VS ratio, question the existence of widespread partial melt of the southern Tibetan crust and, therefore, the viability of the channel flow model.
Growth and Collapse of the Tibetan Plateau

hal-00853971
https://hal.archives-ouvertes.fr/hal-00853971
DOI : 10.1144/SP353.6

Éditeur(s) : HAL CCSD Wiley
Résumé : Seasonal variations in environmental conditions influence the functioning of the whole ecosystem of tropical rain forests, but as yet little is known about how such variations directly influence the leaf gas exchange and transpiration of individual canopy tree species. We examined the influence of seasonal variations in relative extractable water in the upper soil layers on predawn leaf water potential, saturated net photosynthesis, leaf dark respiration, stomatal conductance, and tree transpiration of 13 tropical rain forest canopy trees (eight species) over 2yr in French Guiana. The canopies were accessed by climbing ropes attached to the trees and to a tower. Our results indicate that a small proportion of the studied trees were unaffected by soil water depletion during seasonal dry periods, probably thanks to efficient deep root systems. The trees showing decreased tree water status (i.e., predawn leaf water potential) displayed a wide range of leaf gas exchange responses. Some trees strongly regulated photosynthesis and transpiration when relative extractable water decreased drastically. In contrast, other trees showed little variation, thus indicating good adaptation to soil drought conditions. These results have important applications to modeling approaches: indeed, precise evaluation and grouping of these response patterns are required before any tree-based functional models can efficiently describe the response of tropical rain forest ecosystems to future changes in environmental conditions.
ISSN: 0006-3606

hal-01032411
https://hal.archives-ouvertes.fr/hal-01032411
DOI : 10.1111/j.1744-7429.2012.00902.x

Éditeur(s) : HAL CCSD Trans Tech Publications Inc.
Résumé : Two, high purity, Al-0.1 and 0.3wt%Mn alloys have been cold deformed in plane strain compression to strains of order 1.8 and the kinetics of subsequent recovery by sub-grain coarsening during annealing at 150-300°C measured by high resolution FEG-SEM EBSD. Accurate sub-grain size and misorientation distributions and their evolution with time and temperature have been determined. The average growth rates are then used to estimate the sub-grain boundary mobilities. Growth is analyzed by two well-known growth laws for the average sub-grain size δ (t): i) the standard relation for grain growth: where the exponent n takes values of 2-8 and ii) the relation proposed by Nes for dislocation climb in sub-grain walls: It is shown that the latter relation gives a better fit with the data in terms of the time and temperature dependence of the sub-grain sizes. In particular the activation energies for the logarithmic law are much closer to the values expected for solute-controlled movement of sub-boundaries.
Materials Science Forum

hal-00795441
https://hal.archives-ouvertes.fr/hal-00795441
DOI : 10.4028/www.scientific.net/MSF.715-716.725

Résumé : Herbácea trepadora, pubescente a tomentosa. Hojas suborbiculares o aovadas, de 3.5 a 10 cm, redondeadas a emarginadas, a menudo peltadas. Inflorescencia estaminada en corimbos de hasta 7 cm que nacen en las axilas de las hojas; flores femeninas verdes en racimos de hasta 8 cm. Drupa (fruto) subglobosa, rojiza de 3.5 a 4.5 mm de diámetro.
Herbacée grimpante, pubescente à tomenteuse. Feuilles en forme de fer à cheval ou ovées, de 3,5 à 10 cm, arrondies à émarginées, souvent peltées. Inflorescence staminée en corymbes pouvant atteindre 7 cm qui poussent dans l&rsquo;axe des feuilles; fleurs femelles vertes en grappes femelles pouvant atteindre 8 cm. Drupe (fruit) ovale, rougeâtre de 3,5 à 4,5 mm de diamètre.
Climbing shrub up to 5 m long.  Leaf alternate, simple, entire, hairy, rounded, cordate or peltate, 2-12 cm x 2-10 cm, petioles 3-7 cm long; male inflorescence a panicle, female inflorescence a simple cyme; male flowers white tinged maroon female flowers clustered in axils of rounded bracts; fruit a red drupe 4-5 mm long.
Distribuida ampliamente en las regiones tropicales del mundo.
Largement répandue dans toutes les régions tropicales.
Widely found in tropical regions in the world.

http://www.tramil.net/fototeca/plant125