Capture of the gaze does not capture the mind

Sudden visual changes attract our gaze, and related eye movement control requires attentional resources. Attention is a limited resource that is also involved in working memory-for instance, memory encoding. As a consequence, theory suggests that gaze capture could impair the buildup of memory respresentations due to an attentional resource bottleneck. Here we developed an experimental design combining a serial memory task (verbal or spatial) and concurrent gaze capture by a distractor (of high or low similarity to the relevant item). The results cannot be explained by a general resource bottleneck. Specifically, we observed that capture by the low-similar distractor resulted in delayed and reduced saccade rates to relevant items in both memory tasks. However, while spatial memory performance decreased, verbal memory remained unaffected. In contrast, the high-similar distractor led to capture and memory loss for both tasks. Our results lend support to the view that gaze capture leads to activation of irrelevant representations in working memory that compete for selection at recall. Activation of irrelevant spatial representations distracts spatial recall, whereas activation of irrelevant verbal features impairs verbal memory performance

A Highly Efficient, Angle-Insensitive Solar Quantum Concentrator Based on Microstructured Plastic Optical Fiber

International audienceA new device made of very specific microstructured fluorescent plastic optical fibers, capable of concentrating solar radiation towards photovoltaic solar cells is studied in the QUYOS project. This device transforms a multidirectionnal and polychromatic flux of solar light to a monochromatic and monodirectionnal intense flux of light with a high conversion efficiency. The very specific behaviour of these fibers is due to the convergence of several quantum phenomena. Mainly the coincidence of the fluorescent band of the dye with the forbidden band of the photonic crystal from the microstructured fiber restricts the phase space of desexcitation only along the axis of the fiber. Moreover, a coupling of the fluorescence with the allowed modes of the central waveguide of the fiber does enhance the radiative desexcitation thanks to the Purcell effect

Fabrication of ultra-low radioactivity detector holders for Edelweiss-II

International audienceIn its first stage, the EDELWEISS-II dark matter experiment will use 21×320 g ionization-heat bolometers with NTD thermal sensors. To improve the present sensitivity of EDELWEISS to WIMP interactions by a further factor 100, ultra-low radioactivity detector holders exclusively made of copper and Teflon have been designed. The new design is using the relative expansion coefficients of copper, Teflon and germanium to hopefully ensure a dissipation-free detector holding. In order to validate this new holder, we need to compare the vibration behavior of the old holder and the new one. The amplitude of the bolometer vibrations is measured using the variation of capacitance between electrodes sputtered on the Ge crystal and reference electrodes fixed above the detector holders. We present noise measurements and compare them to the equivalent measurements using the detector holders of the Edelweiss-I experiment, which gave very satisfying results

MOR-based uncertainty quantification in transcranial magnetic stimulation

Field computation for Transcranial Magnetic Stimulation requires the knowledge of the electrical conductivity profiles in the human head. Unfortunately, the conductivities of the different tissue types are not exactly known and vary from person to person. Consequently, the computation of the electric field in the human brain should incorporate the uncertainty in the conductivity values. In this paper, we compare a non-intrusive polynomial chaos expansion and a new intrusive parametric Model Order Reduction approach for the sensitivity analysis in Transcranial Magnetic Stimulation computations. Our results show that compared to the non-intrusive method, the new intrusive method provides similar results but shows two orders of magnitude reduced computation time. We find monotonically decreasing errors for increasing state-space dimensions, indicating convergence of the new method. For the sensitivity analysis, both Sobol coefficients and sensitivity coefficients indicate that the uncertainty of the white matter conductivity has the largest influence on the uncertainty in the field computation, followed by gray matter and cerebrospinal fluid. Consequently, individual white matter conductivity values should be used in Transcranial Magnetic Stimulation field computations

CaLIPSO: An Novel Detector Concept for PET Imaging

International audienceThe CaLIPSO project focuses on the development of an innovative energetic-photon detector. The detector uses a "heavy" organometallic liquid: the TriMethyl Bismuth (TMBi), 82% by weight of Bismuth. TMBi efficiently converts through the photo-electric effect photons of energies below 1 MeV. The ionisation signal and light produced in the liquid are both detected. Beyond the measurement of gamma photon energies, this detector will allow locating photon interactions in the detector in three dimensions down to 1 mm3 and a sub nanosecond timing accuracy. All these desirable properties can be obtained simultaneously with liquid TMBi detector

Trimethyl Bismuth Optical Properties for Particle Detection and the CaLIPSO Detector

International audienceTrimethyl bismuth (TMBi) is a "heavy" transparent and dielectric organometallic liquid. This paper focuses on the measurement of TMBi's optical properties relevant for particle detection. We measured the TMBi transmission curve and refraction index versus wavelength, as well as the light production yield and the timing performance on a small size cell