Active Control of Silicon Nanotweezers Detects Enzymatic Reaction at the Molecular Level

International audienceThis work achieved the control of micromachined tweezers for the enhancement of the sensing of DNA molecules and related enzymatic reactions. The mechanical stiffness of the silicon nanotweezers is decreased by feedback design and the sensitivity of the system is drastically improved

Closed-loop Control of Silicon Nanotweezers for Improvement of Sensitivity to Mechanical Stiffness Measurement and Bio-Sensing on DNA Molecules

International audienceIn this work we show that implementation of closed loop control to silicon nanotweezers improves the sensitivity of the tool for mechanical characterizations of biological molecules. Micromachined tweezers have already been used for the characterizations of mechanical properties of DNA molecules as well as for the sensing of enzymatic reactions on DNA bundle. However the resolution of the experiments does not allow the sensing on single molecules. Hereafter we show theoretically and experimentally that, reducing the resonance frequency of the system by the implementation of a state feedback, the sensitivity to stiffness variation is enhanced. Such improvement leads to better resolution for detection of enzymatic reactions on DNA

Missense Mutation in the Second RNA Binding Domain Reveals a Role for Prkra (PACT/RAX) during Skull Development

Random chemical mutagenesis of the mouse genome can causally connect genes to specific phenotypes. Using this approach, reduced pinna (rep) or microtia, a defect in ear development, was mapped to a small region of mouse chromosome 2. Sequencing of this region established co-segregation of the phenotype (rep) with a mutation in the Prkra gene, which encodes the protein PACT/RAX. Mice homozygous for the mutant Prkra allele had defects not only in ear development but also growth, craniofacial development and ovarian structure. The rep mutation was identified as a missense mutation (Serine 130 to Proline) that did not affect mRNA expression, however the steady state level of RAX protein was significantly lower in the brains of rep mice. The mutant protein, while normal in most biochemical functions, was unable to bind dsRNA. In addition, rep mice displayed altered morphology of the skull that was consistent with a targeted deletion of Prkra showing a contribution of the gene to craniofacial development. These observations identified a specific mutation that reduces steady-state levels of RAX protein and disrupts the dsRNA binding function of the protein, demonstrating the importance of the Prkra gene in various aspects of mouse development

Improvement of thunderstorm hazard information for pilots through a ground based weather information and management system, The CB WIMS approach in FLYSAFE

The development and outcome from first evaluations of the thunderstorm weather information management system ‘CB WIMS’ in the EU project FLYSAFE is described. Preliminary results from a flight test campaign carried out in summer 2008 involving two research aircraft are presented. They lead to the conclusion that information about thunderstorm hazards delivered from CB WIMS through a ground based weather processor and satellite communication to an aircraft could help to improve the pilot’s awareness of the weather situation and assist in flight planning particularly in complex thunderstorm situations where the on-board radar cannot provide the pilot with the full situation awareness due to scanning geometry and radar beam attenuation

Cb Nowcasting in FLYSAFE : Improving flight safety regarding thunderstorm hazards

The FLYSAFE Project aims at defining and testing new tools and systems contributing to the safety of flights for all aircraft, and addresses weather hazards. A “Weather Information Management System” dedicated to thunderstorm hazard has been designed and developed for three geographical scales. It is ground-based, uses as main inputs radar and MSG satellite data and provides nowcasts up to one hour ahead in an object-oriented mode and in a dedicated GML format. Its evaluation involved research aircrafts, both in real time and in an offline setting. Offline evaluation results show the added value of the products, with respect to on-board data, especially regarding the cases of on-board radar return extinction by heavy rain, and regarding extended spatial coverage, most useful when the aircraft turns sharp. Additional potential value of the products show in the CB objects attributes like trend and hail occurrenc

Improved thunderstorm weather information for pilots through ground and satellite based observing systems

Today’s weather information for pilots on thunderstorm conditions on their flight path is insufficient. Weather charts provided by the World Area Forecasting Centres and taken onboard by pilots before take-off are based on forecasts of large scale weather models which are initialized only twice a day. The information of the charts is therefore outdated, at least with respect to thunderstorm occurrence, at the time of use. They can only provide a rough estimation of thunderstorm hazards for relatively large areas. In contrast, thunderstorms develop quickly within tenths of minutes up to an hour and their exact time of occurrence and location is more or less impossible to predict deterministically hours in advance. In this paper, the value of the satellite information on thunderstorm detection over the oceans is demonstrated by applying the DLR Cb-TRAM cloud tracker (Zinner et al., 2009) to last years occurrences of aircraft accident and incident over the Atlantic. In addition, two incidents over the European area with severe turbulence and hail encounter are investigated by satellite, radar and lighting data. The aim of the study is to demonstrate the improved information pilots would gain once the thunderstorm analyses and forecasts of the satellite and ground based systems would be brought, i.e. up-linked, to the cockpit during flight. Today, pilots have information on thunderstorm activity through onboard radar equipment which provides quite good indication on thunderstorm activity within the close range part in flight direction, about 50 miles or so, provided there is precipitation within the convective up-droughts, strong enough to give radar returns. However, the radar returns are strongly attenuated when precipitation cells are large and intense, or several cells behind one another, due to the short wave length of the radars which operate at 3 cm. In that case the pilot’s information of the situation is quite incomplete which makes it difficult for them to choose a proper path around thunderstorm cells or through a thunderstorm line. In addition there are cases where thunderstorm cells are just about to develop with weak or no returns on the radar, yet they can produce convective turbulence which can propagate to levels above the developing cells. In that case the aircraft might experience sudden turbulence without any pre-warning. Also, at high flight levels through tropical storms over the oceans, radar returns might be weak due to small droplet sizes, thereby giving a wrong indication of the severity of the storm. In contrast to this onboard radar information, remote sensing by satellite, ground based radar and lightning can provide a more complete picture of the thunderstorm situation. Ground based systems have been developed which use this data to inspect cells from above, below and multiple viewing angles thereby providing a more complete picture of the thunderstorm situation (e.g.; Tafferner et al., 2009; Sénési et al., 2009). Thunderstorms can well be detected from satellite due to their cold cloud tops and characteristic cloud shape at already early development stage, the precipitation they produce can well be detected by radar and lightning discharges by lightning detectors. References Sénési, S., Y. Guillou, A. Tafferner, and C. Forster, 2009: Cb nowcasting in FLYSAFE: Improving flight safety regarding thunderstorm hazards. WMO Symposium on Nowcasting , 30 August - 4 September 2009 , Whistler, B.C., Canada Tafferner, A. , C. Forster, S. Sénési, Y. Guillou, P. Tabary, P. Laroche, A. Delannoy, B. Lunnon, D. Turp, T. Hauf, and D. Markovic, 2009: Nowcasting thunderstorm hazards for flight operations: the CB WIMS approach in FLYSAFE. European Air and Space Conference (CEAS) , 26 - 29 Oct. 2009, Manchester, UK Zinner, T., Mannstein, H., Tafferner, A. , 2008: Cb-TRAM: Tracking and monitoring severe convection from onset over rapid development to mature phase using multi-channel Meteosat-8 SEVIRI data. Meteorol. Atmos. Phys. 101, 191–21

Contribution à l'étude de la conversion analogique-numérique sigma-delta intégrée dans une chaîne de réception radiofréquence pour les applications cellulaires

CAEN-BU Sciences et STAPS (141182103) / SudocSudocFranceF

Nowcasting Thunderstorm Hazards for Flight Operations: The CB WIMS Approach in FLYSAFE

This paper describes the development of the thunderstorm weather information management system “CB WIMS” within the European Integrated Project FLYSAFE and presents results from applications in case studies over the terminal manoeuvring area of airport Paris Charles de Gaulle