Virtual reconstructions of the Théâtre de l'Athénée for archeoacoustic study

International audienceThe French ECHO project studies the use of voice in the recent history of theater. It is a multidisciplinary project which combines the efforts of historians, theater scientists, and acousticians. In the scope of this project an audiovisual simulation was created which combines auralizations with visualizations of former Théâtre de l'Athénée configurations issue from a series of renovations, enabling researchers to realistically perceive theater performances in foregone rooms. Simulations include the room, 2 actors on stage, and an audience. To achieve these simulation, architectural plans were studied from archives providing various details of the different theater configurations, from which the corresponding visual and room acoustic geometrical acoustics (GA) models were created. The resulting simulations allow for 360°audio-visual presentations at various positions in the theater using commercial standard hardware

Nü Soundworks: Using spectators smartphones as a distributed network of speakers and sensors during live performances

This paper presents the Nu ̈ framework. The objective of the framework is to provide composers with a tool to con- trol web-based audio processes on spectators smartphones during live performances. Connecting their devices to a web- page broadcasted by the performer’s laptop, spectators become part of the composition: from simple sound sources to active musicians. From a Max based interface, the performer can then control the behaviours of conceptual units, referred to as Nu ̈ modules, designed for live composition (distributed room reverb, granular synthesis, etc.). Each module is composed of a pair of JavaScript classes – one for the client, another for the server – relying on the Web Audio API for audio processing, and OSC messages for parameters control. Nu ̈ is an open source project based on the Soundworks framework

: Active Trans-Plasma Membrane Water Cycling in Yeast is Revealed by NMR

International audienceMethods and Materials Yeast suspensions with increasing [RR e ]: Yeast suspensions at 30% wet wt/vol in minimal medium were bubbled with 95% O 2 /5% CO 2 (n =2) or 95% N 2 /5% CO 2 (n=1) for 1.5 hours before the first 1 H 2 O T 1 IR measurement. In one suspension bubbled with 95% O 2 /5% CO 2 , 10 mole of the uncoupler of oxidative phosphorylation, 2,4-dinitrophenol, (DNP) was added after 1.5 hour of O 2 bubbling, just prior to the first addition of RR e. Serial addition of RR to the yeast suspensions resulted in the following [RR e ] (mM) values in the medium: 0, 0.3, 0.6, 0.9, 1.2, 1.8, 2.4, 2.9, 3.5, 4.7, 7.0, 9.3, 11.6, 16.1, and 20.5. The total volume increased by 18% by the end of the titration, which was accounted for in calculating [RR e ]. The IR data acquired at each [RR e ] were analyzed by 2SX fitting and relaxivity fitting as described below. MR Measurements and Data Analyses: The 64 t I delay increments between the 180 o (composite) pulse and 90 o RF pulses of the IR pulse sequence are as follows (s): 0. Relaxograms: A 1D Inverse Laplace Transform (ILT) written in Matlab (TwoDLaplaceInverse, Magritek Limited, Wellington New Zealand) of [(M Z (∞)-M Z (t I))/2M Z (∞)] produced the longitudinal relaxogram, the apparent relaxation time constant (T 1 ) distribution. A two peak relaxogram yielded H 2 O i T 1 ′ (T′ 1i) and H 2 O e T 1 ′ (T′ 1e) values, where the T 1 ′ was taken as the peak position. The apparent relative water mole fractions were taken as the relative peak area values. Peak positions and areas were determined using Matlab routines (MathWorks Inc, Natick, MA). Extracting exchange parameters: As noted in the main manuscript, two different approaches for extracting exchange parameters from relaxographic data were employed. The first method, "2SX fitting," substitutes Eqs. (4-6) into the right hand side of Eq. (7) [(M Z (∞)-M Z (t I))/2M Z (∞)] = a L exp(-t I R 1L) + a s exp(-t I R 1s) (7) (main manuscript) The values of τ i , p i , and r 1e with fixed values for R 1i and R 1e0 are adjusted to match the IR time-course, [(M Z (∞)-M Z (t I))/2M Z (∞)], observed at each [RR e ] value. The second method, "relaxivity fitting," adjusts Eq. (4) and/or (5) to match the [RR e ]-dependence of the R 1L and/or R 1S obtained from the relaxograms (1, 2). Matlab was used for the 2SX and relaxivity fittings

Impact of wearing a head-mounted display on localization accuracy of real sound sources

For augmented reality experiences, users wear head-mounted displays (HMD) while listening to real and virtual sound sources. This paper assesses the impact of wearing an HMD on localization accuracy of real sources. Eighteen blindfolded participants completed a localization task on 32 loudspeakers while wearing either no HMD, a bulky visor HMD, or a glass visor HMD. Results demonstrate that the HMDs had a significantly impact on participants’ localization performance, increasing local great circle angle error by 0.9°, and that the glass visor HMD demonstrably increased the rate of up–down confusions in the responses by 0.9–1.1%. These results suggest that wearing an HMD has a sufficiently small impact on real source localization that it can safely be considered as an HMD-free condition in most but the most demanding AR auditory localization studies

CAVE-based Virtual Prototyping of an Audio Radiogoniometer: Ecological Validity Assesment

Presented at the 20th International Conference on Auditory Display (ICAD2014), June 22-25, 2014, New York, NY.This paper is part of a project concerned with the improvement of audio radiogoniometer design ergonomics and sound aesthetic. It introduces a virtual prototyping implementation of a simple radiogoniometer along with a methodology to assess its ecological validity. Said methodology involves a performance comparison between two different radiogoniometer designs, both implemented as virtual prototypes. While suggested assessment achievement supposes a companion study in a real environment (based on a physical prototype), significant results have already been gathered regarding the impact of the virtual environment on the virtual prototype validity

High-Resolution 1.5-Tesla Magnetic Resonance Imaging for Tissue-Engineered Constructs: A Noninvasive Tool to Assess Three-Dimensional Scaffold Architecture and Cell Seeding

International audienceTissue-engineered scaffolds are made of biocompatible polymers with various structures, allowing cell seeding, growth, and differentiation. Noninvasive imaging methods are needed to study tissue-engineered constructs before and after implantation. Here, we show that high-resolution magnetic resonance imaging (MRI) performed on a clinical 1.5-T device is a reliable technique to assess three-dimensional structures of porous scaffolds and to validate cell-seeding procedures. A high-temperature superconducting detection coil was used to achieve a resolution of 30Â30Â30 mm 3 when imaging the scaffolds. Three types of structures with tuneable architectures were prepared from naturally derived polysaccharides and evaluated as scaffolds for mesenchymal stem cell (MSC) culture. To monitor cell seeding, MSCs were magnetically labeled using simple incubation with anionic citrate-coated iron-oxide nanoparticles for 30 min. Iron uptake was quantified using single-cell magnetophoresis, and cell proliferation was checked for 7 days after labeling. Three-dimensional (3D) microstructures of scaffolds were assessed using MRI, revealing lamellar or globular porous organization according to the scaffold preparation process. MSCs with different iron load (5, 12 and 31 pg of iron per cell) were seeded on scaffolds at low density (132 cells=mm 3) and detected on 3D gradient-echo MR images according to phase distortions and areas of intensely low signal, whose size increased with cell iron load and echo time. Overall signal loss in the scaffold correlated with the number of seeded cells and their iron load. Different organizations of cells were observed depending on the scaffold architecture. After subcutaneous implantation in mice, scaffolds seeded with labeled cells could be distinguished in vivo from scaffold with nonlabeled cells by observation of signal and phase heterogeneities and by measuring the global signal loss. High-resolution 1.5-T MRI combined with efficient intracellular contrast agents shows promise for noninvasive 3D visualization of tissue-engineered constructs before and after in vivo implantation

Molecular Magnetic Resonance and Ultrasound Imaging of Tumor Angiogenesis

International audienc

Characterization of Flexible RF Microcoil Dedicated to Surface Mri

In Magnetic Resonance Imaging (MRI), to achieve sufficient Signal to Noise Ratio (SNR), the electrical performance of the RF coil is critical. We developed a device (microcoil) based on the original concept of monolithic resonator. This paper presents the used fabrication process based on micromoulding. The dielectric substrates are flexible thin films of polymer, which allow the microcoil to be form fitted to none-plane surface. Electrical characterizations of the RF coils are first performed and results are compared to the attempted values. Proton MRI of a saline phantom using a flexible RF coil of 15 mm in diameter is performed. When the coil is conformed to the phantom surface, a SNR gain up to 2 is achieved as compared to identical but planar RF coil. Finally, the flexible coil is used in vivo to perform MRI with high spatial resolution on a mouse using a small animal dedicated scanner operating at in a 2.35 T.Comment: Submitted on behalf of TIMA Editions (http://irevues.inist.fr/tima-editions

Front Cardiovasc Med

IntroductionInterventional cardiac MRI in the context of the treatment of cardiac arrhythmia requires submillimeter image resolution to precisely characterize the cardiac substrate and guide the catheter-based ablation procedure in real-time. Conventional MRI receiver coils positioned on the thorax provide insufficient signal-to-noise ratio (SNR) and spatial selectivity to satisfy these constraints.MethodsA small circular MRI receiver coil was developed and evaluated under different experimental conditions, including high-resolution MRI anatomical and thermometric imaging at 1.5 T. From the perspective of developing a therapeutic MR-compatible catheter equipped with a receiver coil, we also propose alternative remote active detuning techniques of the receiver coil using one or two cables. Theoretical details are presented, as well as simulations and experimental validation.ResultsAnatomical images of the left ventricle at 170 µm in-plane resolution are provided on ex vivo beating heart from swine using a 2 cm circular receiver coil. Taking advantage of the increase of SNR at its vicinity (up to 35 fold compared to conventional receiver coils), real-time MR-temperature imaging can reach an uncertainty below 0.1°C at the submillimetric spatial resolution. Remote active detuning using two cables has similar decoupling efficiency to conventional on-site decoupling, at the cost of an acceptable decrease in the resulting SNR.DiscussionThis study shows the potential of small dimension surface coils for minimally invasive therapy of cardiac arrhythmia intraoperatively guided by MRI. The proposed remote decoupling approaches may simplify the construction process and reduce the cost of such single-use devices.Thermometrie cardiaque haute résolution sur une IRM clinique en utilisant des antennes intracardiaquesL'Institut de Rythmologie et modélisation CardiaqueFrance Life Imagin

Hardware considerations for preclinical magnetic resonance of the kidney

Magnetic resonance imaging (MRI) is a noninvasive imaging technology that offers unparalleled anatomical and functional detail, along with diagnostic sensitivity. MRI is suitable for longitudinal studies due to the lack of exposure to ionizing radiation. Before undertaking preclinical MRI investigations of the kidney, the appropriate MRI hardware should be carefully chosen to balance the competing demands of image quality, spatial resolution, and imaging speed, tailored to the specific scientific objectives of the investigation. Here we describe the equipment needed to perform renal MRI in rodents, with the aim to guide the appropriate hardware selection to meet the needs of renal MRI applications.This publication is based upon work from the COST Action PARENCHIMA, a community-driven network funded by the European Cooperation in Science and Technology (COST) program of the European Union, which aims to improve the reproducibility and standardization of renal MRI biomarkers. This chapter on hardware considerations for renal MRI in small animals is complemented by two separate publications describing the experimental procedure and data analysis