The Influence of Odors on Time Perception

International audienceThe effect of an olfactory stimulation on the perception of time was investigated through two different experiments based on temporal bisection tasks. In experiment 1, the durations to be classified as either short or long were centered on 400 ms while in Experiment 2 there were centered on 2000 ms. The participants were different in the two experiments (36 subjects in each one). In each experiment, half of the subjects learnt the anchor durations when smelling an unpleasant odor (decanoic acid) and the other half when smelling no odor. After the learning phase, both groups were tested with and without odor. The results showed opposite effects depending on the duration range. The subjects underestimated the time in the presence of the unpleasant odor in the short duration range while they overestimated it in the long duration range. The results have been discussed in the framework of the pacemaker-counter clock model and a potential emotional effect induced by the odor on the subjective time perception has also been considered

Électromyographie laryngée du langage intérieur dans la flexibilité mentale et la mémoire

In this thesis, we examined the role of inner speech in mental flexibility and short-term memory using laryngeal surface electromyography, a method for recording inner speech signals. Six experiments manipulating tasks complexity and age of participants were performed to study mental flexibility. Results showed a greater use of inner speech with tasks complexity, either when encoding the rules in memory or while sorting the stimuli, and especially when the participants were older. We discuss the results with reference to articulatory suppression, an alternative method for studying inner speech. To study inner speech in short-term memory, two other experiments were performed with the main objective of studying the phonological similarity effect. Results showed a greater amount of language for dissimilar letters which were also better recalled by participants. On the contrary, we observed a better recall of letters (being similar or dissimilar) by participants who resorted to language moderately. These results suggest that both motor and auditory types of interferences can affect short-term memorization.Cette thèse a pour objet l’étude du langage intérieur dans la flexibilité mentale et la mémoire à court terme à l’aide de l’électromyographie de surface, une méthode qui a permis d’enregistrer l’activité électrique des muscles laryngés. Pour étudier le rôle du langage intérieur dans la flexibilité, six expériences ont été réalisées en manipulant la complexité des tâches, ainsi que l’âge des participants. Les résultats montrent une sollicitation plus importante du langage avec la complexité des tâches, que ce soit pour encoder les règles en mémoire ou pour classer les stimuli, et ce d’autant plus que les participants sont âgés. Nous discutons ces résultats en rapport avec les études utilisant la méthode de suppression articulatoire. Concernant le rôle du langage intérieur dans la mémoire à court terme, deux expériences ont été réalisées avec pour objectif principal l’étude de l’effet de similarité phonologique. Les résultats montrent une quantité de langage plus importante pour les lettres dissimilaires, qui ont aussi été mieux restituées par les participants. A l’inverse, nous avons observé un meilleur rappel de l’ensemble des lettres pour les participants sollicitant de façon plus modérée le langage intérieur. Ces résultats sont mis en rapport avec les processus d’interférences motrice et auditive qui gouvernent la mémorisation à court terme

Yielding and flow of foamed metakaolin pastes

Metakaolin is a broadly used industrial raw material, with applications in the production of ceramics and geopolymers, and the partial replacement of Portland cement. The early stages of the manufacturing of some of these materials require the preparation and processing of a foamed metakaolin-based slurry. In this study, we propose to investigate the rheology of a foamed metakaolin-based fresh paste by performing well-controlled experiments. We work with a non-reactive metakaolin paste containing surfactant, in which we disperse bubbles of known radius at a chosen volume fraction. We perform rheometry measurements to characterize the minimum stress required for the foamed materials to flow (yield stress), and the dissipation occurring during flow. We show that the yield stress of the foamed samples is equal to the one of the metakaolin paste, and that dissipation during flow increases quadratically with the bubble volume fraction. Comparison with yielding and flow of model foamed yield stress fluids allows us to understand these results in terms of coupling between the bubbles' surface tension and the metakaolin paste's rheology

Towards New Aortic Tissues Analogue Materials: Micro-mechanical Modelling and Experiments

Human abdominal aortic tissue is a complex cylindrical soft sandwich structure, arranged in three different concentric layers. Within these layers, distribution and arrangement of all components display a double-helix architecture of wavy fibres, characterised by distinctive preferred orientations. The macroscopic mechanical behaviour of human healthy abdominal aorta (AA) and aneurysmal (AAA) tissues is highly non-linear, anisotropic and essentially hyperelastic. The global objective of this work is to design and process new artificial hy- perelastic and anisotropic membranes mimicking the macroscopic histological and mechanical features of AA and AAA tissues. These materials will be then used to build more realistic phantoms of AAA for in vitro experiments. The aim of the present study is (i) to develop a theoretical framework able to predict the optimal microstructure and mechanical behaviour of such AA/AAA analogues, and (ii) to provide experimental validation of micro-mechanical modelling

Validation of reference genes for real-time PCR of cord blood mononuclear cells, differentiating endothelial progenitor cells, and mature endothelial cells

In the last ten years, endothelial progenitor cells (EPCs) have gained interest as an attractive cell population in regenerative medicine for vascular applications. This population is defined as the precursor of endothelial mature cells (ECs) through a process of differentiation. To our knowledge, no single marker can be used to discriminate them from mature ECs. To effectively study their differentiation kinetics, gene expression must be assessed. Quantitative real-time PCR (RT-qPCR) is widely used to analyze gene expression. To minimize the impact of variances from RT-qPCR, a rigorous selection of reference genes must be performed prior to any experiments due to variations in experimental conditions. In this study, CD34+ mononuclear cells were extracted from human cord blood and differentiated into EPCs after seeding for a maximum period of 21 days. To choose the best combinations of reference genes, we compared the results of EPCs, CD34+ mononuclear cells, and mature endothelial cells to ensure that the differentiation kinetics did not affect the expression of our selected reference genes. The expression levels of seven genes, namely, YWHAZ, GAPDH, HPRT1, RPLP0, UBC, B2M, and TBP were thus compared. The algorithms geNorm, NormFinder, BestKeeper, and the Comparative ΔCt method were employed to assess the expression of each candidate gene. Overall results reveal that the expression stability of reference genes may differ depending on the statistical program used. YWHAZ, GAPDH, and UBC composed the optimal set of reference genes for the gene expression studies performed by RT-qPCR in our experimental conditions. This work can thus serve as a starting point for the selection of candidate reference genes to normalize the levels of gene expression in endothelial progenitor cell population

Archaeobotanical evidence of plant food consumption among early farmers (5700-4500 BC) in the Western Mediterranean region

Les plantes domestiquées, les plantes sauvages cueillies et les plantes cultivées qui n’étaient peut-être pas entièrement domestiquées (par exemple, le pavot), faisaient partie intégrante du régime alimentaire du Néolithique. Des données provenant de 65 sites datés du Néolithique ancien (5800-4500 cal. BC) et situés entre le Nord-Est de la péninsule Ibérique et la plaine du Pô sont utilisées pour illustrer les choix des agriculteurs dans les assemblages de cultures et les activités de cueillette de plantes. Nous concluons que la consommation de nourriture végétale était très diversifiée au Néolithique, impliquant des céréales cultivées, des légumineuses et des plantes oléagineuses ainsi que des niveaux variables de ressources cueillies, en fonction des conditions environnementales

Recruitment of Cdc42 through the GAP domain of RLIP participates in remodeling of the actin cytoskeleton and is involved in Xenopus gastrulation.

International audienceThe transduction pathways that branch out of fibroblast growth factor signaling are essential for the induction of the mesoderm and the specification of the vertebrate body plan. One of these pathways is thought to control remodeling of the actin cytoskeleton through the Ral binding protein (RLIP also known as RalBP1), an effector of the small G protein Ral. RLIP contains a region of homology with the GTPase-activating protein (GAP) domain involved in the regulation of GTPases of the Rho family. We demonstrate here that the GAP domain of RLIP is responsible for the stability of the actin cytoskeleton in Xenopus laevis embryos. We also demonstrate that the complete N-terminal domain of RLIP containing the mu2 binding domain (mu2BD) and the GAP domain induces disruption of the actin cytoskeleton when targeted to the plasma membrane. Neither domain, however, has any effect on the actin cytoskeleton when individually targeted to the plasma membrane. We also determined that Cdc42-GDP, but neither Rac-GDP nor Rho-GDP, rescues the effect of expression of the membrane-localized Xenopus RLIP on the actin cytoskeleton. We show that the GAP domain of RLIP interacts in vivo with Cdc42-GTP and Cdc42-GDP. Finally, a single mutation (K244A) in the GAP sequence prevented embryos from gastrulating. These results demonstrate that to participate in the control of the actin cytoskeleton, RLIP needs its complete N-terminal region coding for the mu2BD and the GAP domain. We suggest that RLIP, by coordinating two complementary mechanisms, the endocytosis of clathrin-coated pits and the remodeling of cortical actin, participates in the gastrulation process

Comparison between the mechanical behavior of the human healthy AA and commercial prostheses under various mechanical loadings

International audienceStandard chirurgical treatment of abdominal aortic aneurysm (AAA) involves the placement of tubular synthetic aortic prostheses. Most of these implants are made up of polyester textiles or porous expanded polytetrafluoroethylene. Normalized tests are dedicated to their assessment (ISO7198:1998). However, such experiments are not sufficient to characterize the complete mechanical performance of these implants (Le Magnen et al., 2001) and to ensure their mechanical compatibility with the host artery. Thus, the design of mechanically compatible vascular prostheses still remains a challenge. Within this context, a full comparison of the mechanical behavior of the human healthy abdominal aorta (AA) with commercial prostheses is proposed. An original numerical database on the mechanical behavior of human AA subjected to various mechanical loadings is first built and then compared with experimental data obtained from mechanical tests performed on prostheses