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Search Results: 1 - 10 of 297365 matches for " J. Duprat "
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Superconducting pairing and density-wave instabilities in quasi-one-dimensional conductors
J. C. Nickel,R. Duprat,C. Bourbonnais,N. Dupuis
Physics , 2005, DOI: 10.1103/PhysRevB.73.165126
Abstract: Using a renormalization group approach, we determine the phase diagram of an extended quasi-one-dimensional electron gas model that includes interchain hopping, nesting deviations and both intrachain and interchain repulsive interactions. d-wave superconductivity, which dominates over the spin-density-wave (SDW) phase at large nesting deviations, becomes unstable to the benefit of a triplet $f$-wave phase for a weak repulsive interchain backscattering term $g_1^\perp>0$, despite the persistence of dominant SDW correlations in the normal state. Antiferromagnetism becomes unstable against the formation of a charge-density-wave state when $g_1^\perp$ exceeds some critical value. While these features persist when both Umklapp processes and interchain forward scattering ($g_2^\perp$) are taken into account, the effect of $g_2^\perp$ alone is found to frustrate nearest-neighbor interchain $d$- and $f$-wave pairing and instead favor next-nearest-neighbor interchain singlet or triplet pairing. We argue that the close proximity of SDW and charge-density-wave phases, singlet d-wave and triplet $f$-wave superconducting phases in the theoretical phase diagram provides a possible explanation for recent puzzling experimental findings in the Bechgaard salts, including the coexistence of SDW and charge-density-wave phases and the possibility of a triplet pairing in the superconducting phase.
Triplet superconducting pairing and density-wave instabilities in organic conductors
J. C. Nickel,R. Duprat,C. Bourbonnais,N. Dupuis
Physics , 2005, DOI: 10.1103/PhysRevLett.95.247001
Abstract: Using a renormalization group approach, we determine the phase diagram of an extended quasi-one-dimensional electron gas model that includes interchain hopping, nesting deviations and both intrachain and interchain repulsive interactions. We find a close proximity of spin-density- and charge-density-wave phases, singlet d-wave and triplet f-wave superconducting phases. There is a striking correspondence between our results and recent puzzling experimental findings in the Bechgaard salts, including the coexistence of spin-density-wave and charge-density-wave phases and the possibility of a triplet pairing in the superconducting phase.
L’historien-bataille.
Annie Duprat
EspacesTemps.net , 2004,
Abstract: Le 11 septembre 1982 disparaissait Albert Soboul, titulaire de la chaire d’histoire de la Révolution fran aise à l’Université Paris 1 depuis la rentrée de l’année universitaire 1967-1968. L’énoncé de cette date rappelle que les débuts sorbonnards de Soboul ne furent pas placés sous le sceau du calme et de la simple recherche savante. Tous ceux qui, comme l’auteur de ces lignes, ont assisté à son cours d’agrégation en 1969 savent combien le magistère professoral ...
Les regalia au crible de la caricature du XVIe au XVIIIe siècle Regalia as seen in caricatures from the 16th to 18th century
Annie Duprat
Bulletin du Centre de recherche du chateau de Versailles , 2008, DOI: 10.4000/crcv.296
Abstract: Cet article a pour objet de montrer comment les attributs de la monarchie, les regalia, sont employés de fa on dépréciative dans les images polémiques et les caricatures depuis le xvie siècle. à travers l’exemple de trois rois de France (Henri III, Louis XIV et Louis XVI) s’ébauche une histoire de la propagande en images. The purpose of this article is to show how the attributes of the monarchy, also named regalia, are used in a negative way in polemical images and caricatures since the sixteenth century. These engravings represent an important part of the history of propaganda in France. They will be discussed through the analysis of three examples: Henry III, Louis XIV and Louis XVI.
Millennial-scale climatic variability between 340 000 and 270 000 years ago in SW Europe: evidence from a NW Iberian margin pollen sequence
S. Desprat, M. F. Sánchez Go i, J. F. McManus, J. Duprat,E. Cortijo
Climate of the Past (CP) & Discussions (CPD) , 2009,
Abstract: We present a new high-resolution marine pollen record from NW Iberian margin sediments (core MD03-2697) covering the interval between 340 000 and 270 000 years ago, a time period centred on Marine Isotope Stage (MIS) 9 and characterized by particular baseline climate states. This study enables the documentation of vegetation changes in the north-western Iberian Peninsula and therefore the terrestrial climatic variability at orbital and in particular at millennial scales during MIS 9, directly on a marine stratigraphy. Suborbital vegetation changes in NW Iberia in response to cool/cold events are detected throughout the studied interval even during MIS 9e ice volume minimum. However, they appear more frequent and of higher amplitude during the 30 000 years following the MIS 9e interglacial period and during the MIS 9a-8 transition, which correspond to intervals of an intermediate to high ice volume and mainly periods of ice growth. Each suborbital cold event detected in NW Iberia has a counterpart in the Southern Iberian margin SST record. High to moderate amplitude cold episodes detected on land and in the ocean appear to be related to changes in deep water circulation and probably to iceberg discharges at least during MIS 9d, the mid-MIS 9c cold event and MIS 9b. This work provides therefore additional evidence of pervasive millennial-scale climatic variability in the North Atlantic borderlands throughout past climatic cycles of the Late Pleistocene, regardless of glacial state. However, ice volume might have an indirect influence on the amplitude of the millennial climatic changes in Southern Europe.
Millennial-scale climatic variability between 340 000 and 270 000 years ago in SW Europe: evidence from a NW Iberian margin pollen sequence
S. Desprat,M. F. Sánchez Go?i,J. Duprat,E. Cortijo
Climate of the Past Discussions , 2008,
Abstract: We present a new high-resolution marine pollen record from NW Iberian margin sediments (core MD03-2697) covering the interval between 340 000 and 270 000 years ago a time period centred on Marine Isotope Stage (MIS) 9 and characterised by particular baseline climate states. This study enables to document the vegetation changes in north-western Iberian Peninsula and therefore the terrestrial climatic variability at orbital and in particular at millennial scales during MIS 9, directly on a marine stratigraphy. Suborbital vegetation changes in NW Iberia in response to cool/cold events are detected throughout the studied interval even during MIS 9e ice volume minimum. However, they appears more frequent and of higher amplitude during the 30 000 years following the MIS 9e interglacial period and during the MIS 9a-8 transition which correspond to intervals of an intermediate to high ice volume and mainly periods of ice growth. Each suborbital cold event detected in NW Iberia has a counterpart in the southern Iberian margin SST record. High to moderate amplitude cold episodes detected on land and in the ocean appears related to changes in deep water circulation and likely to iceberg discharges at least during MIS 9d, the mid-MIS 9c cold event and MIS 9b. This work provides therefore additional evidence of a pervasive millennial-scale climatic variability in the North Atlantic borderlands throughout past climatic cycles of the Late Pleistocene, regardless of glacial state. However, ice volume might have an indirect influence on the amplitude of the millennial climatic changes in southern Europe.
Postharvest impact bruising of apple as related to the modulus of elasticity
Y. Yuwana,F. Duprat
International Agrophysics , 1996,
Abstract: The moduli of elasticity of fruit (E p and E 7) calculated from the maximum force reading (Fp) and from the average flesh force reading at 7 mm depth (F7) were used to predict bruise volume of apple during storage. The relationship between the measured bruised volume (MBV) and the predicted bruise volume based on E p (PBVp) was linear with coefficient of proportionality (Kp) of 4.61 and coefficient of correlation (R) of 0.928 while the relationship between the measured bruise volume (MBV) and the predicted bruise volume based on E 7 (PBVj) was linear with K7 of 231 and R of 0.903. Kp linearly correlated to the average of E p with R value of 0.974 and Ky linearly correlated to the average of E 7 with R value of 0.986. The values of E as well as K drastically decreased during two months storage time and were then relatively constant for longer storage time. Utilising E p Hertz's theory was underestimated 23.37 % while employing E-j it was overestimated 36.66 % in predicting postharvest bruising of Golden Delicious apple.
Prediction of apple bruising based on the instantaneous impact shear stress and energy absorbed
Yuwana Y.,Duprat F.
International Agrophysics , 1997,
Abstract: Instantaneous impact shear stress together with the instantaneous energy absorbed were used to predict bruise volume in Golden Delicious apple. The prediction produced a linear relation between the predicted bruise volumes and the measured bruise volumes with a factor of proportionality (K) 1.08 and a coefficient of correlation (R) 0.949. Both the instantaneous impact shear stress and energy absorbed decreased during storage of the fruit, but the value of K was relatively constant. The value of K was also relatively constant for the impact with small drop heights, but it slightly increased with the variation of fruit mass.
Prediction of apple bruising based on the instantaneous impact shear stress and energy absorbed
Yuwana Y.,Duprat F.
International Agrophysics , 1998,
Abstract: Instantaneous impact shear stress together with the instantaneous energy absorbed were used to predict bruise volume in Golden Delicious apple. The prediction produced a linear relation between the predicted bruise volumes and the measured bruise volumes with a factor of proportionality (K) 1.08 and a coefficient of correlation (R) 0.949. Both the instantaneous impact shear stress and energy absorbed decreased during storage of the fruit, but the value of K was relatively constant. The value of K was also relatively constant for the impact with small drop heights, but it slightly increased with the variation of fruit mass.
Interplay between spin-density-wave and superconducting states in quasi-one-dimensional conductors
Raphael Duprat,C. Bourbonnais
Physics , 2001, DOI: 10.1007/s100510170198
Abstract: The interference between spin-density-wave and superconducting instabilities in quasi-one-dimensional correlated metals is analyzed using the renormalization group method. At the one-loop level, we show how the interference leads to a continuous crossover from a spin-density-wave state to unconventional superconductivity when deviations from perfect nesting of the Fermi surface exceed a critical value. Singlet pairing between electrons on neighboring stacks is found to be the most favorable symmetry for superconductivity. The consequences of non uniform spin-density-wave pairing on the structure of phase diagram within the crossover region is also discussed.
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