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6036Background: Vorinostat (Zolinza) is a potent HDAC inhibitor that sensitizes head and neck squamous cell carcinoma (HNSCC) to cytotoxic therapy while sparing normal epithelium The primary object...

The Ushant thermal front is a seasonal phenomenon which occurs from May to October in a shallow water environment (100m) of the Iroise Sea (off the coast of the north-western France). It corresponds to the boundary separating a well mixed inner shelf water from an open sea stratified water. To determine the dynamic of the front -or more basically the presence of a stratified or homogeneous water column- the possibility to use a shipping lane as a continuous acoustic source is studied. The originality of this work is to use a single receiver. Simulation results of sounds radiated by a shipping lane in a shallow water environment are presented, both for stratified and homogeneous water column. The corresponding pressure fields show a mean level difference in the frequency band 50-300 Hz. This feature will be used in the future as an observable to differentiate both environments, and thus passively detect the Ushant thermal front. One of the issue to get the mean level offset is to record the shipping lane noise without isolated ship interferences. As a consequence, an optimum mooring position to track the thermal front is suggested by the analysis of the vessel traffic from AIS data (Automatic Identification System).

International audience

Research focused on cilia as extremely important cellular organelles has flourished in recent years. A thorough understanding of cilia regulation and function is critical, as disruptions of cilia structure and/or function have been linked to numerous human diseases and disorders. The tropical freshwater zebrafish is an excellent model organism in which to study cilia structure and function. We can readily image cilia and their motility in embryonic structures including Kupffer's vesicle during somite stages and the pronephros from 1 day postfertilization onward. Here, we describe how to image cilia by whole-mount immunofluorescence, transverse cryosection/immunohistochemistry, and transmission electron microscopy. We also describe how to obtain videos of cilia motility in living embryos.

Research focused on cilia as extremely important cellular organelles has flourished in recent years. A thorough understanding of cilia regulation and function is critical, as disruptions of cilia structure and/or function have been linked to numerous human diseases and disorders. The tropical freshwater zebrafish is an excellent model organism in which to study cilia structure and function. We can readily image cilia and their motility in embryonic structures including Kupffer's vesicle during somite stages and the pronephros from 1 day postfertilization onward. Here, we describe how to image cilia by whole-mount immunofluorescence, transverse cryosection/immunohistochemistry, and transmission electron microscopy. We also describe how to obtain videos of cilia motility in living embryos.

Directed Selected Mapping (dSLM) is a well known Peak-to-Average Power Ratio (PAPR) reduction scheme for Multiple-Input Multiple-Output (MIMO) Orthogonal Frequency Division Multiplexing (OFDM) systems. Although such technique provides an extremely effective PAPR reduction, the receiver has not been previously considered in previous research under the assumption of no side information. The transmission data with side information is considered as a drawback, especially when this technique increases the data rate due to the use of channel codes. This also results in a high system complexity and transmission delay. In this proposal, dSLM recovery is modified for Zero-Forcing (ZF) and Zero-Forcing-Vertical Bell Labs Layered Space-Time (ZF-V-BLAST) schemes. The contribution in this paper is twofold; firstly, the transmitted phase vector is recovered without side information whilst maintaining bit error rate performance. Secondly, receiver complexity is reduced.

Significant results on steady state control of the plasma parameters have been obtained with RF systems on Tore Supra. A sustained effort is under way to improve power transmission reliability. Developments of sources and antennas are in progress for future operation on Tore Supra with pulse length in the range of several hundreds of seconds.

The flow of information through a biological network can greatly influence the operation and behavior of the system. The synthetic transcriptional cascades of various lengths and study of their dynamic and steady state behavior both experimentally and through a stochastic model are presented. These systems are used to analyze sensitivity and noise propagation as a function of synthetic network complexity. The steady state switching behavior that becomes sharper with longer cascades is demonstrated experimentally. The experimental results demonstrating the network properties correlate well with the simulated model.

National audience

The precise nature of information flow through a biological network, which is governed by factors such as response sensitivities and noise propagation, greatly affects the operation of biological systems. Quantitative analysis of these properties is often difficult in naturally occurring systems but can be greatly facilitated by studying simple synthetic networks. Here, we report the construction of synthetic transcriptional cascades comprising one, two, and three repression stages. These model systems enable us to analyze sensitivity and noise propagation as a function of network complexity. We demonstrate experimentally steady-state switching behavior that becomes sharper with longer cascades. The regulatory mechanisms that confer this ultrasensitive response both attenuate and amplify phenotypical variations depending on the system's input conditions. Although noise attenuation allows the cascade to act as a low-pass filter by rejecting short-lived perturbations in input conditions, noise amplification results in loss of synchrony among a cell population. The experimental results demonstrating the above network properties correlate well with simulations of a simple mathematical model of the system.

One of the important challenges in the emerging field of synthetic biology is designing artificial networks that achieve coordinated behavior in cell communities. Here we present a synthetic multicellular bacterial system where receiver cells exhibit transient gene expression in response to a long-lasting signal from neighboring sender cells. The engineered sender cells synthesize an inducer, an acyl-homoserine lactone (AHL), which freely diffuses to spatially proximate receiver cells. The receiver cells contain a pulse-generator circuit that incorporates a feed-forward regulatory motif. The circuit responds to a long-lasting increase in the level of AHL by transiently activating, and then repressing, the expression of a GFP. Based on simulation models, we engineered variants of the pulse-generator circuit that exhibit different quantitative responses such as increased duration and intensity of the pulse. As shown by our models and experiments, the maximum amplitude and timing of the pulse depend not only on the final inducer concentration, but also on its rate of increase. The ability to differentiate between various rates of increase in inducer concentrations affords the system a unique spatiotemporal behavior for cells grown on solid media. Specifically, receiver cells can respond to communication from nearby sender cells while completely ignoring communication from senders cells further away, despite the fact that AHL concentrations eventually reach high levels everywhere. Because of the resemblance to naturally occurring feed-forward motifs, the pulse generator can serve as a model to improve our understanding of such systems.

The field of multiphoton microscopy has undergone significant advances since its beginning just over a decade ago. One of these was the development of coherent multiphoton techniques, which typically image intrinsic properties of the sample, without resorting to staining or labeling. Here we describe some recent technological developments in the two leading coherent multiphoton techniques: third-harmonic generation and coherent anti-Stokes Raman spectroscopy. These techniques are applied for visualization of a variety of biological and other samples.

Source localization with a single sensor explores the time spread of the received signal as it travels from the emitter to the receiver. In shallow water, and for ranges larger than a few times the water depth, the received signal typically exhibits a large number of closely spaced arrivals. However, not all the arrivals are equally important for estimating the source position since a number of them convey redundant information. Theoreticaly, identifying the non-redundant arrivals is feasible in a isovelocity range independent waveguide. In previous work, the number of non-redundant arrivals and the dimension of the data sample signal subspace have been related in a range-independent case. This paper addresses the problem of determining the number of significant arrivals for localizing a sound source over a range-dependent environment on the West coast of Portugal during the INTIMATE'96 sea trial. SACLANTCEN

A simple and fast approach to retrieve equivalent geoacoustic parameters is presented in this paper. The method is based upon the processing of 300-800 Hz broadband signals on a single hydrophone.Two stable characteristics of the impulse response of the shallow water waveguide are estimated: the time dispersion and the bottom reflection amplitudes. This two features are analytically linked to the compressional speed and to the attenuation coefficient of the medium. The inversion of the two latter geoacoustic parameters is straightforward since it relies on an analytical expression. The method is tested on INTIMATE96 data. The results show an excellent agreement between the reflection of the true medium and the reflection coefficient of the equivalent medium. The partners of the INTIMATE project wish to thank the staff of NRP ANDROMEDA, the staff of BO D’ENTRECASTEAUX and people of Mission Océanographique de l’Atlantique (aboard D’ENTRECASTEAUX). We also wish to thank the SACLANT Undersea Research Center for lending the Portable Array System and Roberto Chiarabini (SACLANTCEN) for his participation in the array preparation, deployment and use. Thanks to T. Folegot and G. Bonnaillie (CMO) for their active contribution in this work. The study was jointly sponsored by SHOM (exploratory program 95901), the Portuguese Ministery of Research (PRAXIS XXI) and ONR (contract N00014-95-1-0558).

One of the currently exciting areas in SONAR research is in the use of acoustic channel models to improve SONAR systems. In this paper, we use the echo pattern at a single phone to localise a sound source in both range and depth in the ocean. To make the localisation robust, the signal processing is set-up with particular regard to which acoustic features are reliable and clear encoders of the source position. The resulting algorithm was tested using experimental data collected during INTIMATE’96- a shallow water experiment conducted on the Portuguese continental shelf[1]. The results show successful tracking over a period of several days encompassing two fixed 25-hour stations and an 18-hour period of ship manoeuvres. This work was supported in part by ONR Grant N00014-95-0558. One of us (M.B.P) gratefully acknowledges support under the PRAXIS program as a visiting Professor at the Universidade o Algarve and by the New Jersey Institute of Technology under the sabbatical program. The data was collected on a portable array lent to us by the SACLANT Undersea Research Centre.

Using hydrodynamic and thermodynamic equations appropriate for modelling internal tides, one can predict the current and temperature distributions associated with the ocean's dynamic modes. Comparing such predictions with observations from the INTIMATE'96 experiment, we nd a high degree of correlation between the rst 3 theoretically calculated dynamic modes and corresponding empirical orthogonal functions (EOF's) derived from an ensemble of temperature and current pro les. The implications are twofold. First, this implies that the dominant variability in the INTIMATE'96 experiment is indeed associated with internal tides. Secondly, it suggests that in future tidal experiments a theoretically generated basis may be used as e ectively as an EOF basis (which requires more extensive oceanographic measurements). We have also used the set of dynamic modes to simulate the e ect of the tides on acoustic propagation to understand the relative importance of the usual surface tide (barotropic) and the internal (baroclinic) tides.

Internal tides commonly occur along ocean coasts. They are internal waves driven by the usual tidal force and generated by scattering at a sharp bottom feature such as the shelf break. The internal tides are dramatic features with crests typically 10-30 km apart and wave heights of 20 m. On the ocean surface they cause only a gentle ripple about 10 cm high but they affect the shine of the surface. As a result, astronauts often see them as the tides propagate away from the shelf break. In June 1996, a shallow-water tomography experiment (INTIMATE 96) was conducted off the coast of Portugal to observe these internal tides and learn about their acoustic effects. A source was towed around a vertical hydrophone array to produce acoustic sections along several slices. The experiment also provided an ideal opportunity for testing model-based source tracking. Acoustic sections taken parallel to the Portuguese coast allowed us to understand the propagation physics in a range-independent area. With this we have been able to develop a matched-field algorithm suitable for use in the far more complicated downslope direction which, being perpendicular to the crests of the internal tides, also experiences strong ocean-temperature variations. We will discuss both the approach and the source tracking. ONR, New Jersey Institute of Technology, SCALANT Undersea research

Modelling sound propagation in shallow water is notoriously difficult. The main difficulties are, of course, ocean variability characteristic of coastal waters and the typpicaly downward refracting profiles that make the acoustic field extremely sensitive to the bottom characteristics. Meanwhile accurate prediction of transimission loss curves at a single frequency requires that the relative phase of each surface and bottom echo is predicted with precision. PRAXIS XXI

The INTIMATE (INternal Tide Investigation by Means of Acoustic Tomography Experiment) project is devoted to the study of internal tides by use of acoustic tomography. The first exploratory experiment was carried out in June 1996 on the continental shelf off the west coast of Portugal. A towed broadband acoustic source and a 4-hydrophone vertical array were used. Acoustic data were collected for 5 days, including legs where the source ship was moving and legs with the ship on station. The purpose of this paper is to briefly discuss some effects of the environment on acoustic fluctuations. PRAXIS XXI PRAXIS XXI program under project 2./2.1/MAR/1695/95.

Dans un cristal liquide cholesterique pris en sandwich entre deux lames de verres conductrices avec des conditions d'ancrage homeotrope, l'apparition de structures spatiales isolees, appelees doigts cholesteriques de premiere espece, est maintenant bien comprise. Quand on soumet le cristal liquide a un champ electrique vertical, on observe alors que ces doigts cholesteriques se mettent a bouger perpendiculairement a son grand axe avec une vitesse V⊥. Dans ce papier, on montre analytiquement que cette vitesse pourrait etre reliee a l'effet Lehmann, et que sa mesure permettrait alors d'estimer la valeur du coefficient de couplage electromecanique.

The acoustic data shows a clean multipath structure warped in time by the tides. Ray, mode, FFP models all provide a precise prediction of the arrival structure. The source is tracked continuously over several days as it moves to and from the array both cross−slope and down− slope. Tides cause a small wobble in apparent target range. Flat−bottom model leads to a small range error when the source moves down−slope. ONR/Ocean Acoustics; NICT Portable array from SACLANTCEN