Investigation of photocurrents resulting from a living unicellular algae suspension with quinones over time

International audiencePlants, algae, and some bacteria convert solar energy into chemical energy by using photosynthesis. In light of the current energy environment, many research strategies try to benefit from photosynthesis in order to generate usable photobioelectricity. Among all the strategies developed for transferring electrons from the photosynthetic chain to an outer collecting electrode, we recently implemented a method on a preparative scale (high surface electrode) based on a Chlamydomonas reinhardtii green algae suspension in the presence of exogenous quinones as redox mediators. While giving rise to an interesting performance (10-60 mA cm À2) in the course of one hour, this device appears to cause a slow decrease of the recorded photocurrent. In this paper, we wish to analyze and understand this gradual fall in performance in order to limit this issue in future applications. We thus first show that this kind of degradation could be related to over-irradiation conditions or side-effects of quinones depending on experimental conditions. We therefore built an empirical model involving a kinetic quenching induced by incubation with quinones, which is globally consistent with the experimental data provided by fluorescence measurements achieved after dark incubation of algae in the presence of quinones

Radiotherapy in breast cancer: current standards of treatment, prediction of local recurrence and open questions

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Vers une agrégation en sciences : images d'une collaboration

Bilan d'une collaboration entre les didacticiens des sciences physiques, biologiques et chimiques dans le cadre de la réforme de l'agrégation de l'enseignement secondaire supérieur. Deux expériences de formation sont racontées et analysées : représentations et démarche expérimentale sur les fruits et légumes en biologie et sur le fonctionnement d'une pile en chimi

DS6_mT_EEG frequency tagging to track the processing of vibrotactile contrasts.v1.0

EEG frequency spectra. See README file for description of experimental conditions and variables

La démarche d’évaluation des pratiques professionnelles de conduite d’entretien au service de la professionnalisation des personnels d’éducation

International audienc

Measuring oddball responses to vibrotactile textures

Using a fast-periodic oddball paradigm, together with EEG frequency-tagging, we aimed to assess the possibility of measuring periodic responses to rapid changes in a vibrotactile texture. Sequences consisting of standard (A) and oddball stimuli (B) were presented in an AAAAB pattern, with a base and oddball presentation rate of 8 Hz and 1.6 Hz (8/5 Hz), respectively. A and B stimuli either differed in frequency and intensity, or in terms of their complex spectrotemporal composition. Preliminary results suggest that the protocol can be successfully used to record EEG correlates of the cortical processing of haptic textures

Does visual experience shape body schema?

The representation of touch on our body is not veridical. For instance, tactile distances across the limb (mediolateral) are always perceived as larger than those running along the limb (proximodistal). This tactile anisotropy reflects distortions in body-shape representation, such that the arms are perceived wider than they are. It has been suggested that such an effect may arise because the primary somatosensory representation of touch is rescaled into an object-centered space according to the visual experience of the body. To causally test the role of visual experience on body map representation, we investigated tactile distance perception in sighted and early blind individuals comparing mediolateral and proximodistal tactile distances of stimuli presented on the ventral and dorsal part of their arm, wrist, and hand. Overestimation of distances in mediolateral over proximodistal body axes was found in both sighted and blind people. However, the magnitude of the anisotropy was significantly reduced in the arms of blind people. We conclude that tactile distance perception is mediated by similar mechanisms in both sighted and blind people; but that vision partly affects the transformation of somatosensory representations into an object-centered space

Does visual experience shape body schema?

The representation of touch on our body is not veridical. For instance, tactile distances across the limb (mediolateral) are always perceived as larger than those running along the limb (proximodistal). This tactile anisotropy reflects distortions in body-shape representation, such that the arms are perceived wider than they are. It has been suggested that such an effect may arise because the primary somatosensory representation of touch is rescaled into an object-centered space according to the visual experience of the body. To causally test the role of visual experience on body map representation, we investigated tactile distance perception in sighted and early blind individuals comparing mediolateral and proximodistal tactile distances of stimuli presented on the ventral and dorsal part of their arm, wrist, and hand. Overestimation of distances in mediolateral over proximodistal body axes was found in both sighted and blind people. However, the magnitude of the anisotropy was significantly reduced in the arms of blind people. We conclude that tactile distance perception is mediated by similar mechanisms in both sighted and blind people; but that vision partly affects the transformation of somatosensory representations into an object-centered space