121 research outputs found

    When I Means We: A Reading of School in French Caribbean Apprenticeship Novels

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    While most critics agree that the quest for identity which underlies much of post-colonial literature is illustrated in the thematic approaches adopted by writers, this study further the argument by suggesting that it also conditions writers\u27 selection of narrative strategies. In its representation of subjectivity in process, the apprenticeship novel seems to offer an enticing model of self-completion. This narrative strategy, however, presents particular complexities when used to portray coming of age in a society divided along ethnic lines. Simon Gikandi argues with regards to the Caribbean that the probability of a quest for identity reaching fruition is nil, but other critics take a more hopeful stand when they see the apprenticeship novel as a novel of initiation into the methods of survival in a context marked by \u27the presence of the Other\u27 (Kandé 34; my emphasis). The acquisition of the French language and reading and writing skills through school offers a salient example of these opposite stands. An analysis of several French Caribbean novels which explore the role of school reveals the emergence of a rift as school enables young characters such as José in La Rue Cases-NÚgres by Joseph Zobel or the narrator and her brother in Le Temps des Madras by Françoise Ega to achieve a certain measure of wholeness, but becomes a deadly lure for young girls such as Zétou in Le Quimboiseur l\u27avait Dit or Mélanée in Pluie et Vent sur Télumée-Miracle. Though the rift often follows gendered lines, it is predominantly attributable to the existence, or lack thereof, of a strong support system which enables characters to retain their Caribbean identity while acquiring the skills needed to function in a French-speaking world

    Probing the Ionic Dielectric Constant Contribution in the Ferroelectric Phase of the Fabre-Salts

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    In strongly correlated organic materials it has been pointed out that charge-ordering could also achieve electronic ferroelectricity at the same critical temperature TcoT_{co}. A prototype of such phenomenon are the quasi-one dimensional (TMTTF)2X_2X Fabre-salts. However, the stabilization of a long-range ferroelectric ground-state below TcoT_{co} requires the break of inversion symmetry, which should be accompanied by a lattice deformation. In this work we investigate the role of the monovalent counter-anion XX in such mechanism. For this purpose, we measured the quasi-static dielectric constant along the c∗c^{*}-axis direction, where layers formed by donors and anions alternate. Our findings show that the ionic charge contribution is three orders of magnitude lower than the intra-stack electronic response. The c∗c^{*} dielectric constant (Ï”c∗â€Č\epsilon'_{c^*}) probes directly the charge response of the monovalent anion XX, since the anion mobility in the structure should help to stabilize the ferroelectric ground-state. Furthermore, our Ï”c∗â€Č\epsilon'_{c^*} measurements %conjugated with earlier investigations of the c∗c^* lattice thermal expansion, show that the dielectric response is thermally broaden below TcoT_{co} if the ferroelectric transition occurs in the temperature range where the anion movement begin to freeze in their methyl groups cavity. In the extreme case of the PF6_6-H12_{12} salt, where TcoT_{co} occurs at the freezing point, a relaxor-type ferroelectricity is observed. Also, because of the slow kinetics of the anion sub-lattice, global hysteresis effects and reduction of the charge response upon successive cycling are observed. In this context, we propose that anions control the order-disorder or relaxation character of the ferroelectric transition of the Fabre-salts.Comment: 8 pages, 7 figures. To appear in Physical Review

    Mangrove de virtualités

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    Exploring the Charge-Ordering Transition in (TMTTF)2_2X via Thermal Expansion Measurements

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    We report results of high-resolution measurements of the \emph{c∗^*}-axis expansivity (αc∗\alpha_{c^{*}}) at the charge-ordering (CO) transition for the quasi-1D (TMTTF)2_{2}X compounds with X = SbF6_6 and Br and make a comparison with previous results for the X = PF6_6 and AsF6_6 salts. For X = SbF6_6, due to the screening of the long-range Coulomb forces, a sharp λ\lambda-type anomaly is observed at TCOT_{CO}, which contrasts with the step-like mean-field anomaly at TCOT_{CO} for PF6_6 and AsF6_6, where CO occurs in the Mott-Hubbard charge-localized regime. For the latter two salts, a negative contribution to αc∗\alpha_{c^{*}} is observed above TCOT_{CO}. This feature is assigned to the anions' rigid-unit modes, which become inactive for TT << TCOT_{CO}. Our αc∗\alpha_{c^{*}} results for the X = Br salt, where such rigid-unit modes are absent, reveal no traces of such negative contribution, confirming the model based on the anions' rigid-unit modes for the X = PF6_6 and AsF6_6 salts.Comment: Submitted to Special Issue - ISCOM 2009 - Physica B Condensed Matte

    Experimental observations of temperature effects in the near-field regime of the Casimir-Polder interaction

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    We investigate the temperature dependence of the Casimir-Polder interaction in the electrostatic limit. This unusual phenomenon relies on the coupling between a virtual atomic transition and a thermal excitation of surface polariton modes. We first focus on the scenario where a Cs(8P3/2) atom is next to a CaF2 or a BaF2 surface. Our theoretical predictions show a strong temperature dependence of the van der Waals coefficient at experimentally accessible conditions. A series of spectroscopic measurements performed in a specially designed Cs vapour cell containing a CaF2 tube is presented. Our results illustrate the sensitivity of atom surface-interaction experiments to the quality and chemical stability of the surface material and emphasize the need of using more durable materials, such as sapphire. We finally discuss selective reflection experiments on Cs(7D3/2) in an all-sapphire cell that clearly demonstrate a temperature dependent van der Waals coefficient.Comment: accepted for publication in Laser Physic

    Temperature dependence of the dielectric permittivity of CaF2, BaF2 and Al2O3: application to the prediction of a temperature dependent van der Waals surface interaction exerted onto a neighbouring Cs (8P{3/2}) atom

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    International audienceThe temperature behaviour in the range 22°C to 500 °C of the dielectric permittivity in the infrared range is investigated for CaF2, BaF2 and Al2O3 through reflectivity measurements. The dielectric permittivity is retrieved by fitting reflectivity spectra with a model taking into account multiphonon contributions. The results extrapolated from the measurements are applied to predict a temperature-dependent atom-surface van der Waals interaction. We specifically consider as the atom of interest Cs (8P3/2), the most relevant virtual couplings of which, fall in the range of thermal radiation and are located in the vicinity of the reststrahlen band of fluoride materials

    Building consensus on water use assessment of livestock production systems and supply chains: outcome and recommendations from the FAO LEAP Partnership

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    The FAO Livestock Environmental Assessment and Performance (LEAP) Partnership organised a Technical Advisory Group (TAG) to develop reference guidelines on water footprinting for livestock production systems and supply chains. The mandate of the TAG was to i) provide recommendations to monitor the environmental performance of feed and livestock supply chains over time so that progress towards improvement targets can be measured, ii) be applicable for feed and water demand of small ruminants, poultry, large ruminants and pig supply chains, iii) build on, and go beyond, the existing FAO LEAP guidelines and iv) pursue alignment with relevant international standards, specifically ISO 14040 (2006)/ISO 14044 (2006), and ISO 14046 (2014). The recommended guidelines on livestock water use address both impact assessment (water scarcity footprint as defined by ISO 14046, 2014) and water productivity (water use efficiency). While most aspects of livestock water use assessment have been proposed or discussed independently elsewhere, the TAG reviewed and connected these concepts and information in relation with each other and made recommendations towards comprehensive assessment of water use in livestock production systems and supply chains. The approaches to assess the quantity of water used for livestock systems are addressed and the specific assessment methods for water productivity and water scarcity are recommended. Water productivity assessment is further advanced by its quantification and reporting with fractions of green and blue water consumed. This allows the assessment of the environmental performance related to water use of a livestock-related system by assessing potential environmental impacts of anthropogenic water consumption (only “blue water”); as well as the assessment of overall water productivity of the system (including “green” and “blue water” consumption). A consistent combination of water productivity and water scarcity footprint metrics provides a complete picture both in terms of potential productivity improvements of the water consumption as well as minimizing potential environmental impacts related to water scarcity. This process resulted for the first time in an international consensus on water use assessment, including both the life-cycle assessment community with the water scarcity footprint and the water management community with water productivity metrics. Despite the main focus on feed and livestock production systems, the outcomes of this LEAP TAG are also applicable to many other agriculture sector
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