448 research outputs found
Une histoire de la violence
Si on le replace dans lâhistoire des Ă©tudes portant sur lâenvironnement en Ăthiopie, telle quâelle est retracĂ©e dans lâintroduction rĂ©digĂ©e par Guillaume Blanc et GrĂ©gory Quenet, le dossier prĂ©sentĂ©, ici, pourÂrait bien marquer une nouvelle Ă©tape historioÂgraphique, celle dâune histoire environnementale « consciente dâelle-mĂȘme », de sa propre hisÂtoire, de ses enjeux, de ses cadres thĂ©oriques. Dâautant que, associĂ©e Ă James McCann, figure pionniĂšre de lâhistoire des systĂšmes agraires en Ăthi..
LâĂthiopie mĂ©diĂ©vale
Lâhistoire de lâĂthiopie entre le viie et le xiiie siĂšcle est mal connue. Des recherches historiques et archĂ©ologiques rĂ©centes sur des sites du MĂ€nz, du Gedem et de lâIfat, ainsi que de nouvelles datations au Carbone 14, ont permis notamment de rĂ©vĂ©ler lâexistence dâune nouvelle culture sur le haut plateau, caractĂ©risĂ©e par la richesse du mobilier importĂ©. Elles permettent aussi de repenser lâarriĂšre-plan historique des processus de christianisation et dâislamisation de ces rĂ©gions, de saisir ces phĂ©nomĂšnes de façon synchronique, et de remettre en question le modĂšle migratoire dominant dans lâhistoriographie.The history of Ethiopia between the 7th and the 13th Century is badly known. Recent historical and archaeological researches in MĂ€nz, Gedem and Ifat, as well as new Radiocarbon datations, have led us to describe a new culture on the highlands, characterized by a rich imported material. They also allow to reassess the historical background of christianization and islamization of these regions, to understand these processes in a synchronic way, and to question the leading migratory model in the historiography
Self-Consistent Quasi-Particle RPA for the Description of Superfluid Fermi Systems
Self-Consistent Quasi-Particle RPA (SCQRPA) is for the first time applied to
a more level pairing case. Various filling situations and values for the
coupling constant are considered. Very encouraging results in comparison with
the exact solution of the model are obtained. The nature of the low lying mode
in SCQRPA is identified. The strong reduction of the number fluctuation in
SCQRPA vs BCS is pointed out. The transition from superfluidity to the normal
fluid case is carefully investigated.Comment: 23 pages, 18 figures and 1 table, submitted to Phys. Rev.
Narcissistic self-sorting of n-acene nano-ribbons yielding energy-transfer and electroluminescence at p-n junctions
The 2,3-didecyloxy derivative of an n-type anthracene (n-BG) and a p-type tetracene (p-R) have been synthesized and their self-assembly into nano-ribbons studied. Hyperspectral fluorescence imaging revealed their narcissistic self-sorting, leading to separated nanoribbons emitting with very different colors (blue or green for n-BG, depending on the growth solvent, and red for p-R). It is unique that the usual origins of self-sorting, such as specific H-bonding, different growth kinetics, or incompatible steric hindrance can be ruled out. Hence, the narcissistic behaviour is herein proposed to originate from a sofar unconsidered cause: the discrepancy between the quadrupolar character of n-BG and dipolar character of p-R. At the p-n junctions of these nanoribbons, inter-ribbon FRET and electro-luminescence switch-on were observed by fluorescence/luminescence microscopy.The authors acknowledge the financial support of the European Research Council Marie Curie Actions (FP7-PEOPLE-2012-ITN SMARTNET Grant agreement Nr 316656); the CNRS; the French Ministry of Education and Research; the Region Aquitaine; the ANR-06-JCJC-0030; the Department of Education, Science and Universities of the Basque Country Government (postdoctoral grant and project IT1639-22); the "Arina" informatic cluster of UPV/EHU; the facilities ELORGA of UB; and the ANR-17-CE24-0033-01 RESOLVE. The authors thank Dr A. Mendez-Ardoy for the CV measurements and CESAMO for structural analyses (ISM, Univ. Bordeaux)
Fully-Renormalized QRPA fulfills Ikeda sum rule exactly
The renormalized quasiparticle-RPA is reformulated for even-even nuclei using
restrictions imposed by the commutativity of the phonon creation operator with
the total particle number operator. This new version, Fully-Renormalized QRPA
(FR-QRPA), is free from the spurious low-energy solutions. Analytical proof is
given that the Ikeda sum rule is fullfiled within the FR-QRPA.Comment: 9 page
Insulin down-regulates cardioprotective SUR2A in the heart-derived H9c2 cells:A possible explanation for some adverse effects of insulin therapy
Some recent studies associated insulin therapy with negative cardiovascular events and shorter lifespan. SUR2A, a KATP channel subunit, regulate cardioprotection and cardiac ageing. Here, we have tested whether glucose and insulin regulate expression of SUR2A/KATP channel subunits and resistance to metabolic stress in heart H9c2 cells. Absence of glucose in culture media decreased SUR2A mRNA, while mRNAs of Kir6.2, Kir6.1, SUR1 and IES SUR2B were increased. 2-deoxyglucose (50âŻmM) decreased mRNAs of SUR2A, SUR2B and SUR1, did not affect IES SUR2A and IES SUR2B mRNAs and increased Kir6.2 mRNA. No glucose and 2-deoxyglucose (50âŻmM) decreased resistance to an inhibitor of oxidative phosphorylation, DNP (10âŻmM). 50âŻmM glucose did not alter KATP channel subunits nor cellular resistance to DNP (10âŻmM). Insulin (20âŻng/ml) in both physiological and high glucose (50âŻmM) down-regulated SUR2A while upregulating Kir6.1 and Kir6.2 (in high glucose only). Insulin (20âŻng/ml) in physiological and high glucose decreased cell survival in DNP (10âŻmM). As opposed to Kir6.2, infection with SUR2A resulted in titre-dependent cytoprotection. We conclude that insulin decreases resistance to metabolic stress in H9c2 cells by decreasing SUR2A expression. Lower cardiac SUR2A levels underlie increased myocardial susceptibility to metabolic stress and shorter lifespan. Keywords: Insulin, Glucose, SUR2A, Hear
On the stability of tetrahedral relative equilibria in the positively curved 4-body problem
We consider the motion of point masses given by a natural extension of
Newtonian gravitation to spaces of constant positive curvature. Our goal is to
explore the spectral stability of tetrahedral orbits of the corresponding
4-body problem in the 2-dimensional case, a situation that can be reduced to
studying the motion of the bodies on the unit sphere. We first perform some
extensive and highly precise numerical experiments to find the likely regions
of stability and instability, relative to the values of the masses and to the
latitude of the position of three equal masses. Then we support the numerical
evidence with rigorous analytic proofs in the vicinity of some limit cases in
which certain masses are either very large or negligible, or the latitude is
close to zero.Comment: 32 pages, 6 figure
Cardiac dysfunction in cancer patients : beyond direct cardiomyocyte damage of anticancer drugs. Novel cardio-oncology insights from the joint 2019 meeting of the ESC Working Groups of Myocardial Function and Cellular Biology of the Heart
Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2020. For permissions please email: [email protected] reviewedPostprin
Interface Molecular engineering for laminated monolithic perovskite/silicon tandem solar cells with 80.4% fill factor
A multipurpose interconnection layer based on poly(3,4âethylenedioxythiophene) doped with poly(styrene sulfonate) (PEDOT:PSS), and dâsorbitol for monolithic perovskite/silicon tandem solar cells is introduced. The interconnection of independently processed silicon and perovskite subcells is a simple addâon lamination step, alleviating common fabrication complexities of tandem devices. It is demonstrated experimentally and theoretically that PEDOT:PSS is an ideal building block for manipulating the mechanical and electrical functionality of the charge recombination layer by controlling the microstructure on the nanoâ and mesoscale. It is elucidated that the optimal functionality of the recombination layer relies on a gradient in the dâsorbitol dopant distribution that modulates the orientation of PEDOT across the PEDOT:PSS film. Using this modified PEDOT:PSS composite, a monolithic twoâterminal perovskite/silicon tandem solar cell with a steadyâstate efficiency of 21.0%, a fill factor of 80.4%, and negligible open circuit voltage losses compared to singleâjunction devices is shown. The versatility of this approach is further validated by presenting a laminated twoâterminal monolithic perovskite/organic tandem solar cell with 11.7% power conversion efficiency. It is envisioned that this lamination concept can be applied for the pairing of multiple photovoltaic and other thin film technologies, creating a universal platform that facilitates mass production of tandem devices with high efficiency
Narcissistic Self-Sorting of n-Acene Nano-Ribbons yielding Energy-Transfer and Electroluminescence at p-n Junctions
The 2,3-didecyloxy-derivative of an n-type anthracene (n-BG) and a p-type tetracene (p-R) have been synthesized and their self-assembly into nano-ribbons studied. Hyperspectral fluorescence imaging revealed their narcissistic self-sorting, leading to separated nanoribbons emitting with very different colors (blue or green for n-BG, depending on the growth solvent, and red for p-R). It is unique that the usual origins of self-sorting, such as specific H-bonding, different growth kinetics, or incompatible steric hindrance can be ruled out. Hence, the narcissistic behaviour is herein proposed to originate from a sofar unconsidered cause: the discrepancy between the quadrupolar character of n-BG and dipolar character of p-R. At the pn-junctions of these nanoribbons, inter-ribbon FRET and electro-luminescence switch-on were observed by fluorescence microscopy.Modulation of Organic Optic Information InterfacesFabrication Supramoléculaire de Dispositifs OLED Haute Résolution par voie ImprimableSoft Materials Advanced Research Training Networ
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