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We describe a new technique for the preparation of reactive templates of 1,2-aminopropyltriethoxysilane on silica surfaces, based on the chemical vapour deposition of silane molecules through a PMMA mask patterned by conventional electron-beam lithography. The template thickness and width are controlled down to the monolayer and 50 nm ranges respectively. These templates are successfully used for the selective deposition of sodium dodecylsulphatecovered single walled nanotubes at controlled locations on the surface. We demonstrate that this technique allows one to contact nanotubes with metallic electrodes deposited on top of the tubes and opens the way towards the formation of controlled crossings of nanotubes. © 2000 Elsevier Science B.V. All rights reserved.

We have measured the supercurrent in aluminum atomic point contacts containing a small number of well characterized conduction channels. For most contacts, the measured supercurrent is adequately described by the opposite contributions of two thermally populated Andreev bound states per conduction channel. However, for contacts containing an almost perfectly transmitted channel $0.9\ensuremath{\le}\ensuremath{\tau}\ensuremath{\le}1$ the measured supercurrent is higher than expected, a fact that we attribute to nonadiabatic transitions between bound states.

In this paper, we investigate the modeling of dry silicon thermal oxidation in the light of the model capabilities and the trends in microelectronics. We show how a combined use of different models can be made in a way to generate process simulations that are strongly related to microscopic physical phenomena. In conjunction with experimental literature data, first principle calculations have been carried out with the objective of isolating some elementary oxidation mechanisms, i.e. basic atomic movements and their corresponding activation energies. This preliminary list of mechanisms is discussed in detail. A growth mechanism allowing the oxide defect generation is proposed. We then present Monte Carlo calculations with the implemented mechanisms where at least three silicon layers are oxidized. Finally, we introduce a macroscopic formulation of these mechanisms via the Chemical Rate Theory.

We have determined the phase coherence time, τφ, frommagnetoresistance measurements of long, narrow wires ofAu, Ag, and Cu, over the temperature range40 mK-6 K. In the Cu and Au wires, τφsaturates at low temperature. In the Ag wire,τφ continues to increase down to the lowesttemperatures measured; moreover, its temperature dependencebelow about 1 K is consistent with theoreticalpredictions of Altshuler, Aronov and Khmelnitskii published in1982. These results cast doubt on recent assertions thatsaturation of τφ at low temperature is a universalphenomenon in metal wires. We compare these results with thoseof recent experiments on energy relaxation in similar metallicwires. The results of the two experiments are stronglycorrelated, suggesting that a single (unknown) mechanism isthe cause of the enhanced phase and energy relaxation observedin some samples.

We have measured with a tunnel probe the energy distributionfunction of quasiparticles in silver diffusive wires connectedto two large pads (“reservoirs”), between which a biasvoltage was applied. From the dependence in energy and biasvoltage of the distribution function we have inferred theenergy exchange rate between quasiparticles. In contrast withpreviously obtained results on copper and gold wires, thesedata on silver wires can be well interpreted with the theoryof diffusive conductors either solely, or associated withanother mechanism, possibly the coupling to two-level systems.

We have performed an atomic-scale simulation of (100) thin films heteroepitaxial growth of semiconductors with zincblende structure by associating a Monte Carlo technique with an energy model based on the valence force field approximation. It is shown that grooves showing (111) facets are formed in the early stages of the growth owing to enhanced interlayer migrations. The strain relief can be achieved within a few atomic layers, in agreement with experimental observations.

Single electron devices are based on small normal metal electrodes called ‘islands’ separated by tunnel junctions. In such circuits, electrons can be transfered one by one when the energy of thermal fluctuations is less than the electrostatic energy necessary to add an extra electron to an island. We present here experimental results in single electron devices for which all normal-metal electrodes are replaced by superconducting ones. In such devices coherent Cooper pair tunneling (i.e. the DC-Josephson effect) combines with Coulomb blockade. These effects can be tuned in such a way that signatures of the macroscopic quantum coherence between two well-defined charge states become observable.

This paper presents a new hybrid diagnostic methodology. This new hybrid system involves statistical pre-processing, Artificial Neural Networks (ANN) and Fuzzy Logic (FL). The statistical pre-processing of data allows outliers to be eliminated (filtering) and dimensional reduction while keeping the most important data. Then, each process state is learned by one of the original constructive algorithms discussed: Multidimensional Fuzzy Sets (MFS) which fuzzyfies binary ANN or Generalized Radial Basis Functions (GRBF) learned by the Estimation Maximization (EM) algorithm. The final step is the final decision by Fuzzy Logic algorithms, in which an automatic defuzzification method is proposed. These methodologies produce some parameters which allows real-time to be performed.

First principle calculations are applied to the properties of both atomic and molecular oxygen on (100) silicon surface and in the bulk silicon. It is shown that either in the interior or on the surface, the oxidation process is promoted by the presence of atomic oxygen as the reaction is not thermally activated. In all the cases studied (at 0 K temperature), oxidation is limited by the molecular oxygen decomposition. Thus adsorption sites for atomic oxygen are described. We show how these sites give an insight in the dynamics of intrinsic interface defect generation already described in literature.

We present full ab initial calculations of both molecular and atomic oxygen reacting with hydrogen passivated Si(100) 2 × 1 reconstructed surface. The calculations are based on the density functional theory via a pseudopotential method. Preliminary results reported concern the search for the oxygen preferential setting on the surface. For molecular oxygen only physisorbed states are found. For atomic oxygen, oxidation reaction occurs and we find two preferential sites for the oxygen. In the first case we show how Si H bonds on the hydrogenated surface dimers are broken. The second case is a direct barrierless and destructive subsurface oxidation.

Mechanical micro actuators on silicon is playing a major role in the development of microsystems. In this context, many structures have been performed on electrostatic, piezo electric or pneumatic actuators. However, limitations remain when energetic micro actuations have to be created. We propose in this paper, a new original type of actuation based on the force generated by the combustion of an explosive. It consists of a micromachined silicon microheater (3 mm×3 mm×0.3 mm) on which a thin film of propellant (2 mm×2 mm×0.2 mm) is deposited. Its functioning principle is based on a hot gas emitted by the auto combustion of the propellant when its temperature reaches 300°C locally. In this paper, we present the results of a study (by modelling and experimental) of the ignition and combustion of a very small quantity of explosive onto a Si-micromachined microheater. We conclude by presenting two examples of applications showing the promising interest of this energetic actuator: the first application is the biomedical field. The second one, today is used for microspace craft attitude control.

The atomic scale understanding of silicon oxide growth is investigated to determine interface defects formation (geometry and spatial distribution) during a technology process. In this paper we present a general methodology also applicable to other atomic scale problems. This methodology is based on the use of several theoretical models used in cascade, each model giving parameters for a higher modelling level. To clarify this procedure, we give quantum calculation results and their impact on a Monte Carlo technique to investigate oxide growth dynamics.

In nanoscale Josephson junctions, the Josephson coupling energy is usually comparable with the charging energy of the junction and with the typical energy of thermal fluctuations. Under these circumstances, phase fluctuations imposed by the electromagnetic environment of the junction crucially affect the junction electrical behavior. In particular, they determine the maximum “supercurrent” the junction can sustain. We discuss this quantity in the case where the junction is not resistively shunted, so that the I V characteristics of the junction remains hysteretic. For a simple, yet realistic, unshunted junction model, we obtain detailed predictions of the shape of the supercurrent branch of the I V characteristic. Finally, we present experimental results supporting the theoretical analysis and which demonstrate that the supercurrent in an unshunted nanoscale Josephson junction can indeed be of the order of its critical current.

A metallic electrode connected to electron reservoirs by tunnel junctions has a series of charge states corresponding to the number of excess electrons in the electrode. In contrast to the charge state of an atomic or molecular ion, the charge states of such an “island” are mesoscopic states involving all the conduction electrons of the island. Island charge states bear some resemblance to the photon number states of the cavity in cavity QED, the phase conjugate to the number of electrons being analogous to the phase of the field in the cavity. For a normal island, charge states decay irreversibly into charge states of lower energies. However, the gound state of a superconducting island connected to superconducting reservoirs can be a coherent superposition of charge states differing by two electrons (i.e., a Cooper pair). We describe an experiment in which this Josephson effect involving only one Cooper pair is measured.

This paper presents a new technique for thinning down up to 10 m and handling various semiconductor devices, and transferring them onto host substrates. An optimized mechanical lapping is used to remove the wafer backside after the fabrication process by way of a cavity-wafer. The original transfer technique based on the different thermal properties of waxes or epoxy layers is described, and the electrical results obtained on test devices are presented.

We have simulated the growth of GaSb/(00l)GaAs, and we have focused our study on the defects creation at the DA and DB double steps on the substrate. A Monte Carlo scheme associated with a valence force field approximation is used to describe, respectively, the kinetic and the strain effects in the mis-matched film. These simulations indicate a strong localization of dislocation half loops at the step edges in accordance with experimental observations.

We investigate the growth of mismatched thin films by a kinetic Monte Carlo computer simulation. The strain is introduced through an elastic energy term based on a valence force field approximation and stress is relaxed along “atomic chains” at each step of the simulation. The calculations use a set of elementary atomic processes including, besides well-known standard processes, the collective incorporation of atoms. This leads us to introduce a new “hanging” position with only one bond created toward the substrate contrary to solid on solid models. This position plays a role of defects initiation, and thus an atomic dislocation nucleation mechanism is described. Finally, we present the influence of a step in the dislocations creation.

In this paper, we present a new way to perform actuation through the use of forces produced by pyrotechnic combustion. After describing the functioning of this so-called pyrotechnic actuator, we present the modelling of the combustion ignition in order to find an optimal ignition system enabling minimization of ignition energy. Good agreement between experience and simulation is obtained and characterizations of the pyrotechnic actuator give an idea of its performances in terms of gas yield and forces developed. The low cost and the use of a classic microtechnology process as well as the excellent ratio between the energy produced over the power consumption give good prospects for these actuators.

The zero-voltage state of a current biased Josephson tunnel junction is metastable and the system can switch to the voltage state by thermal activation. In the presence of a microwave current the rate of escape is resonantly activated when the microwave frequency matches the plasma frequency [M.H. Devoret et al. Phys. Rev. Lett. 53 (1984) 1260]. In accordance with theoretical predictions [S. Linkwitz and H. Grabert, Phys. Rev. B 44 (1991) 11 901] we have measured high frequency satellites of the resonant activation peak.

Temperature cycling has been used associated to FEM simulations to evaluate thermomechanical stresses in a MCM-V packaged MEMS. The places of maximum stresses have been localized by the simulations. The results are coherent with electrical measurements done on the assembly during and after the thermal cycling. Modifications are proposed (type of material , geometry of the package) in order to improve the reliability.

Simulation of heteroepitaxial growth with high lattice mismatch is reported. The dynamics of layer growth is treated using the Monte Carlo technique and the energetics aspects related to the effect of strain are accounted for in the VFF approximation. It is shown that the surface becomes rough and 3D islands, showing (111) facets, appear. The strain relaxation is shown to be almost complete after a few atomic layers. Formation of point and extended defects is observed in the deposited layers.

In this paper, the diagnostic part of the SAVE system is described. It is composed of three main diagnostic subsystems 1) behavioural diagnosis, 2) physical diagnosis and 3) critical diagnosis. Each subsystem uses different sensors on-board the vehicle and the information is placed in a hierarchical order and mixed to obtain a general diagnosis. A model (black-box), learned off line, is compared on line to the actual driver's performance. Owing to the inherent difficulty of this problem, the model is created by using Statistical and Artificial Intelligence algorithms (Neural Networks and Fuzzy Logic). Laboratory experiments were made and yielded a success rate in excess of 95%. On-line experiments have started using the SAVE demonstrators in which the system is able to differentiate between the driving behaviour of two persons with a success rate of 98% under the same real traffic conditions.

Using microfabricated break junctions, we have produced Al and Au contacts consisting of a small number of atoms. These metallic quantum point contacts accomodate a small number of conduction channels. We have determined the individual transmission coefficients in contacts containing up to six conduction channels. The determination is based on a comparison of the highly nonlinear current–voltage characteristics in the superconducting state with the predictions of the theory for a single channel superconducting contact (in the case of Au contacts superconductivity is induced by means of the proximity effect). We find that in the smallest achievable contacts usually three channels contribute to the transport in the case of Al, whereas only one does in the case of Au. These findings are consistent with the quantum chemistry point of view that the channels are determined by the valence atomic orbitals at the narrowest section of the contacts.

We present a full ab initio calculation of the oxygen atom in interaction with a (1 0 0) silicon surface. This calculation is based on the density functional theory (DFT) via the Harris functional. Preliminary results reported concern the calculation leading to the oxygen preferential setting on the surface. The total energy, angles and bond lengths are evaluated. We find two preferential sites for the oxygen which are linked in the oxidation process. One is identified as a molecular site and occurs first. The other is close to be a SiO 2 crystalline site. The effect of the oxygen density at the surface is also discussed.

There is considerable interest in thin-film microheaters for decreasing the power consumption in portable applications. In this paper, we present the study of new stacked thin membranes (SiO 2 /SiN 1.2 ) supporting the heating element (polysilicon resistor). The great interest of using SiN 1.2 deposited onto a SiO 2 layer is the improvement in mechanical properties of the membrane, leading to a fabrication yield very close to 100%. Microheaters fabricated with a 1.6 mm × 1.6 mm square and 0.7 μm thick SiO 2 /SiN 1.2 membrane give promising results in terms of power consumption; 230°C is reached with an electrical power of 50 mW.

In addition to their central role in quantum information processing, qubits have proven to be useful tools in a range of other applications such as enhanced quantum sensing and as spectrometers of quantum noise. Here we show that a superconducting qubit strongly coupled to a nonlinear resonator can act as a probe of quantum fluctuations of the intraresonator field. Building on previous work [M. Boissoneault et al., Phys. Rev. A 85, 022305 (2012)], we derive an effective master equation for the qubit which takes into account squeezing of the resonator field. We show how sidebands in the qubit excitation spectrum that are predicted by this model can reveal information about the squeezing factor $r$. The main results of this paper have already been successfully compared to experimental data [F. R. Ong et al., Phys. Rev. Lett. 110, 047001 (2013)], and we present here the details of the derivations.

Achieving individual qubit readout is a major challenge in the development of scalable superconducting quantum processors. We have implemented the multiplexed readout of a four transmon qubit circuit using non-linear resonators operated as Josephson bifurcation amplifiers. We demonstrate the simultaneous measurement of Rabi oscillations of the four transmons. We find that multiplexed Josephson bifurcation is a high-fidelity readout method, the scalability of which is not limited by the need of a large bandwidth nearly quantum-limited amplifier as is the case with linear readout resonators., 7 pages, 6 figures, and 31 references

We present measurements of superconducting flux qubits embedded in a three dimensional copper cavity. The qubits are fabricated on a sapphire substrate and are measured by coupling them inductively to an on-chip superconducting resonator located in the middle of the cavity. At their flux-insensitive point, all measured qubits reach an intrinsic energy relaxation time in the $6--20\text{ }\text{ }\ensuremath{\mu}\mathrm{s}$ range and a pure dephasing time comprised between 3 and $10\text{ }\text{ }\ensuremath{\mu}\mathrm{s}$. This significant improvement over previous works opens the way to the coherent coupling of a flux qubit to individual spins.

We present a microscopic theory for the current through a tunnel Josephson junction coupled to a non-linear environment, which consists of an Andreev two-level system coupled to a harmonic oscillator. It models a recent experiment [Bretheau, Girit, Pothier, Esteve, and Urbina, Nature (London) 499, 312 (2013)] on photon spectroscopy of Andreev bound states in a superconducting atomic-size contact. We find the eigenenergies and eigenstates of the environment and derive the current through the junction due to inelastic Cooper pair tunneling. The current-voltage characteristic reveals the transitions between the Andreev bound states, the excitation of the harmonic mode that hybridizes with the Andreev bound states, as well as multi-photon processes. The calculated spectra are in fair agreement with the experimental data., 8 pages, 6 figures

International audience; We observe the suppression of the finite frequency shot-noise produced by a voltage biased tunnel junction due to its interaction with a single electromagnetic mode of high impedance. The tunnel junction is embedded in a quarter wavelength resonator containing a dense SQUID array providing it with a characteristic impedance in the kOhms range and a resonant frequency tunable in the 4-6 GHz range. Such high impedance gives rise to a sizeable Coulomb blockade on the tunnel junction (roughly 30% reduction in the differential conductance) and allows an efficient measurement of the spectral density of the current fluctuations at the resonator frequency. The observed blockade of shot-noise is found in agreement with an extension of the dynamical Coulomb blockade theory.

The flux qubit is often considered as a major design for the future of quantum integrated circuits and its properties have triggered intense interest in the last decade [1-2]. This superconducting circuit behaves as a two-level system, each level being characterized by the direction of a macroscopic permanent current flowing in the loop of the qubit. The permanent current, typically of the order of several hundreds of nAs, generates a large magnetic dipole, which offers interesting prospects for hybrid quantum circuits [3]. However, the flux qubit suffers from limited and irreproducible lifetimes which partially prevent these potential applications. Recently, a novel architecture where qubits are placed in a three dimensional cavity was introduced for transmon qubit [4]. It was shown that coherence properties can be greatly improved.

In this paper, we model first the heating performance of a silicon micromachined microheater. The pros and cons of the use of a stacked dielectric membranes instead of p ++ -Si membranes are discussed, either in terms of electrical consumption, or in terms of emperature homogeneity. Then, we realize and characterize two examples among the simulated structures. This allows some practical problems during the fabrication, essentially due to mechanical breakdown, to be demonstrated. A general agreement between results is found. This study shows significant promise in the development of stacked dielectric membranes.

We consider a simple model of a metallic nanowire, consisting of a free electron gas confined within hard-wall boundaries and connected to banks on either side. Similar models have been widely used to discuss conductance properties of nanowires and point contacts. Here we show that the same model has implications for the mechanical stability of the wire and its work function, and that it possibly induces Jahn-Teller-type distortions in the wire cross section.

We have measured with a tunnel probe the energy distribution function of Landau quasiparticles in metallic diffusive wires connected to two reservoir electrodes, with an applied bias voltage. The distribution function in the middle of a 1.5-mm-long wire resembles the half sum of the Fermi distributions of the reservoirs. The distribution functions in 5- mm-long wires are more rounded, due to interactions between quasiparticles during the longer diffusion time across the wire. From the scaling of the data with the bias voltage, we find that the scattering rate between two quasiparticles varies as « 22 , where « is the energy transferred. [S0031-9007(97)04367-6] The present understanding of metals is based on Landau’s theory of Fermi liquids. In this model, the elementary excitations of the fluid of interacting electrons are nearly independent fermionic quasiparticles [1]. In disordered metals, residual interactions between quasiparticles lead in mesoscopic samples to measurable corrections to the density of states, and limit the phase coherence of quasiparticles [2]. These effects have been widely investigated experimentally and theoretically in the last 20 years [3]. However, the most elementary manifestation of interactions, namely, the transfer of energy between quasiparticles, has been observed only at energies of order 1 eV by time-resolved spectroscopy of a metallic film following a laser pulse [4], and in the meV range through the establishment of an electron temperature in the so-called hotelectron regime [5]. Indications as to the speed at which this thermalization proceeds were obtained in recent shot noise experiments [6]. In this Letter, we report a direct measurement of the energy transfer rates between quasiparticles in diffusive metallic wires. We have measured the energy distribution function of quasiparticles in wires in a stationary out-ofequilibrium situation, at low enough temperature so that quasiparticle-quasiparticle interaction is the dominant inelastic process. The deviations of the energy distribution function from the Fermi distribution give access to the energy transfer rates. We force the wire out of equilibrium by placing it between two reservoir electrodes [7] biased at different potentials, 0 and U, as shown in Fig. 1. The local distribution function is probed with a superconducting electrode connected to the wire by a tunnel junction. The experiment exploits the property of the distribution function to have different shapes depending on the amount of inelastic collisions a quasiparticle experiences during its diffusion time through the wire. The steady-state distribution function fsx, Ed in a metallic wire of length L, which depends on the position X › xL measured from the right electrode, and on the energy E, results from the combined action of the elastic diffusion and of interactions. It obeys the Boltzmann

We have investigated the suppression of single-electron charging effects in metallic single-electron transistors when the conductance of the tunnel junctions becomes larger than the conductance quantum ${e}^{2}/h$. We find that the Coulomb blockade of the conductance is progressively shifted at lower temperatures. The experimental results agree quantitatively with the available $1/T$ expansion at high temperature, and qualitatively with the predictions of an effective two-state model at low temperature, which predicts at $T\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}0$ a blockade of conductance for all gate voltages.

The electromagnetic environment in which a small tunnel junction circuit is embedded plays a crucial role in its transport properties. Although the theory of single-electron tunneling is well established, few analytical results are known. We use a real-time formulation to obtain new predictions for the high-temperature conductance of singleand double-junction systems in series with a resistor. We discuss the implications of our results for recently proposed metrological thermometry based on Coulomb blockade of single-electron tunneling. @S0163-1829~97!06928-2#

The isV , td curves present a series of sharp current steps at voltage values V › 2Dyne, where n is a positive integer and D is the superconducting gap. The well-known process of single quasiparticle transport corresponds to n › 1. The common phenomenon behind the other steps is multiple Andreev reflection (MAR) of quasiparticles between the two superconducting banks [14]. The order n › 2, 3, . . . , of a step corresponds to the number of electronic charges transferred in the underlying MAR process. As the transmission of the channel rises from 0 to 1, the higher order processes grow stronger and the subgap current increases progressively. This so-called “subharmonic gap structure” has already been observed in superconducting weak links and tunnel junctions with a very large number of channels [15,16]. Measurements [17] of the current-voltage characteristic ( IV ) of Nb and Pb single channel tunnel junctions with an adjustable transmission t1 have shown that the height of the successive current steps is proportional to increasing powers of t1 ,i n FIG. 1. Measured current-voltage characteristics (symbols) of four different configurations of sample #1 at 30 mK and best numerical fits (lines). The individual channel transmissions and total transmission T obtained from the fits are (a) t1 › 0.997, t2 › 0.46, t3 › 0.29, T › 1.747; (b) t1 › 0.74, t2 › 0.11, T › 0.85; (c) t1 › 0.46, t2 › 0.35, t3 › 0.07, T › 0.88; and (d) T › t1 › 0.025. Voltage and current are in reduced units. The measured superconducting gap was Dye › 182.5 6 2.0 mV. Left inset: Theoretical IVs for a single channel superconducting contact for different values of its transmission coefficient t (from bottom to top: 0.1, 0.4, 0.7, 0.9, 0.99, 1) after [12]. Right inset: Typical total transmission traces measured at V $ 5 Dye, while opening the contact at around 6 pmys, for samples #1 and #2. The bar indicates the distance scale.

We have investigated the kinetics of heteroepitaxial growth with large lattice mismatch by associating the Monte Carlo technique with an energy model based on valence force field (VFF) approximation. The energy model allows the acceleration of the atomic motions as a function of local strain energy and a relaxation of most stressed positions. We have observed the roughening of the surface followed by the formation of (111) facets, the apparition of highly mobile atoms in interstitial positions on these facets and the reaction between these atoms. The reactions are seen to lead to stabilized nuclei with dangling bonds which are at the origin of point defects or extended defects in the growing layer.

We have measured with a tunnel probe the energy distribution function of quasiparticles in the middle of a 1.5 μm-long copper wire placed between two reservoirs at different potentials. We find a distribution function close to half the sum of the Fermi distributions in the reservoirs. The deviation from this behavior is not yet understood.

We propose a non-destructive method to measure the trajectory of a single antiproton in a drift tube using position sensors based on the single electron transistor. We show that this recently developed device has sufficient sensitivity to detect the electric field of a moving charged particle. Comparing the trajectories of antiprotons and H− ions could allow a reliable determination of the gravitational mass of the antiproton.

International audience; In the process industry, fouling is considered as a complex (sometimes partially known and identified) phenomenon. In this paper, a fouling sensor (FS) based on local differential thermal analysis is scrutinized and we report the comparison of two operating modes, steady (STR) and periodic (PTR) thermal regimes. Moreover, the development of alternating technologies like direct joule effect (ohmic) heating to pasteurise and sterilise liquid food products in a continuous process is of great scientific and industrial interest. Heat treatment by direct Joule effect exhibits numerous advantages because rapid heating kinetics or homogeneous heat treatment is required. However, fouling of electrode surfaces in this kind of apparatus is much more problematic than in conventional heat exchangers. In the present study, a new continuous ohmic heating apparatus (Emmepiemme (R), Piacenza, Italy) in which an alternating electrical current is applied directly to a jet falling between two stainless steel electrodes is investigated during pasteurisation of a dairy product. Conventional fouling measurements (pressure drop, heat transfer or electrical parameters) cannot be used in such a heater. Fouling and cleaning phases are monitored with fouling sensor and fouling quantified.

International audience; AIMS/HYPOTHESIS: Alterations in white adipose tissue (WAT) function, including changes in protein (adipokine) secretion and extracellular matrix (ECM) composition, promote an insulin-resistant state. We set out to identify novel adipokines regulated by body fat mass in human subcutaneous WAT with potential roles in adipose function. METHODS: Adipose transcriptome data and secretome profiles from conditions with increased/decreased WAT mass were combined. WAT donors were predominantly women. In vitro effects were assessed using recombinant protein. Results were confirmed by quantitative PCR/ELISA, metabolic assays and immunochemistry in human WAT and adipocytes. RESULTS: We identified a hitherto uncharacterised adipokine, semaphorin 3C (SEMA3C), the expression of which correlated significantly with body weight, insulin resistance (HOMA of insulin resistance [HOMAIR], and the rate constant for the insulin tolerance test [KITT]) and adipose tissue morphology (hypertrophy vs hyperplasia). SEMA3C was primarily found in mature adipocytes and had no direct effect on human adipocyte differentiation, lipolysis, glucose transport or the expression of β-oxidation genes. This could in part be explained by the significant downregulation of its cognate receptors during adipogenesis. In contrast, in pre-adipocytes, SEMA3C increased the production/secretion of several ECM components (fibronectin, elastin and collagen I) and matricellular factors (connective tissue growth factor, IL6 and transforming growth factor-β1). Furthermore, the expression of SEMA3C in human WAT correlated positively with the degree of fibrosis in WAT. CONCLUSIONS/INTERPRETATION: SEMA3C is a novel adipokine regulated by weight changes. The correlation with WAT hypertrophy and fibrosis in vivo, as well as its effects on ECM production in human pre-adipocytes in vitro, together suggest that SEMA3C constitutes an adipocyte-derived paracrine signal that influences ECM composition and may play a pathophysiological role in human WAT.

An unshunted Josephson tunnel junction switching out of its zero-voltage state is a model system for thermal activation out of a metastable state. For small-capacitance low-critical-current junctions, this thermal activation process follows a generalized Arrhenius law involving dissipation directly in its exponent. This escape over a dissipation barrier can be computed exactly for a junction connected to a {ital RC} impedance providing large damping. The diffusion branch and the switching histograms measured for such a junction are in agreement with theory. {copyright} {ital 1996 The American Physical Society.}

Once the in board smart multisensor danger detection copilot system defined (1992). LAAS-CNRS has investigated different methodological approaches to realise the diagnosis. Three complementary directions have been identified : a. The following of the driving mistakes in terms of trafiic regulations (1992); b. The evaluation time of the reactivity capability of the driver. We have studied Autoregressive Moving Average (ARMA), (1993) and c. The driving procedural analysis on which we are working in this contribution (1994). We are now planning to introduce a pre-metric by Principal Component Analysis (PCA). Experiment : A driver realises several times the experiment which consists of negotiating a cross-roads.

We report results of atomic scale simulations used to study the dynamics of epitaxial growth of GaAs and, in particular, the oscillations of the photoemission current. We have simulated growth of GaAs using a monoatomic As source. The photoemission oscillations are found to depend on the growth conditions in the same manner as do reflection high-energy electron diffraction (RHEED) intensity oscillations.

Monte Carlo technique and Valence force field approximation are used to investigate the heteroepitaxial growth with high lattice mismatch. It is shown that the growing surface becomes rough very rapidly. Its morphology is stabilized and shows V-grooves with (111) facets. The grooves are filled with highly mobile liquid-like atoms that can be incorporated in stable solid-like positions through collective motions and reactions.

Metallic point contacts and tunnel junctions with a small and adjustable number of conduction channels have been obtained in the last few years using scanning tunneling microscope and break junction techniques. For conventional break junctions, the reported drift of the interelectrode spacing in the tunnel regime is typically of the order of 0.5 pm/min (1 pm=10−12 m). We have nanofabricated break junctions which display a drift smaller than 0.2 pm/h. The improvement results from the scaling down by two orders of magnitude of the device dimensions. We describe the nanofabrication process, which can be adapted to most metals. We have performed measurements on Al, Cu, and Nb devices. The results illustrate the ability of the technique to explore phenomenalike conductance quantization and two level fluctuations. These new adjustable atomic size contacts and tunnel junctions can be integrated in complex circuits.

We measure the excitation spectrum of a superconducting atomic contact. In addition to the usual continuum above the superconducting gap, the single particle excitation spectrum contains discrete, spin-degenerate Andreev levels inside the gap. Quasiparticle excitations are induced by a broadband on-chip microwave source and detected by measuring changes in the supercurrent flowing through the atomic contact. Since microwave photons excite quasiparticles in pairs, two types of transitions are observed: Andreev transitions, which consists of putting two quasiparticles in an Andreev level, and transitions to odd states with a single quasiparticle in an Andreev level and the other one in the continuum. In contrast to absorption spectroscopy, supercurrent spectroscopy allows detection of long-lived odd states., Comment: typos corrected

We measure the quantum fluctuations of a pumped nonlinear resonator using a superconducting artificial atom as an in situ probe. The qubit excitation spectrum gives access to the frequency and amount of excitation of the intracavity field fluctuations, from which we infer its effective temperature. These quantities are found to be in agreement with theoretical predictions; in particular, we experimentally observe the phenomenon of quantum heating.

Les AA. soulignent que les innovations technologiques affectent de facon tres importante la vie quotidienne. Ils affirment qu'elles peuvent offrir aux personnes handicapees une meilleure autonomie dans leur environnement domestique et social. Ils signalent notamment l'apport des protheses individuelles, des appareillages domotiques, des systemes de telesurveillance. Il etudie la notion de personne dependante. Ils presentent un systeme de surveillance qui permet de depister a distance les situations de risque. Ils s'efforcent de montrer le bien-fonde de ce type d'equipement