Showing papers by "École Normale Supérieure published in 1983"
TL;DR: The Lagrangian and transformation laws of the coupled Yang-Mills-matter-supergravity system for unextended n = 1 local supersymmetry were derived in this article.
834 citations
TL;DR: In this paper, the choice of a particular class of Einstein spaces for the Kahler manifold of the hidden sector leads to a vanishing cosmological constant without unnatural fine tuning, and the resulting low energy softly broken globl supersymmetry for the matter fields is the same as in the case of factorized superpotential models with a flat Kahler metric.
823 citations
TL;DR: The notion of spectral dimensionality of a self-similar (fractal) structure is recalled and its value for the family of Sierpinski gaskets derived via a scaling argument is derived in this paper.
Abstract: The notion of spectral dimensionality of a self-similar (fractal) structure is recalled, and its value for the family of Sierpinski gaskets derived via a scaling argument. Various random walk properties such as the probability of closed walks and the mean number of visited sites are shown to be governed by this spectral dimension. It is suggested that the number SN of distinct sites visited during an N-step random walk on an infinite cluster at percolation threshold varies asymptotically as : SN ∼ N2/3, in any dimension.
740 citations
01 Jan 1983
TL;DR: It is the experience that this way of penetrating a cell inflicts much less damage on the cell than the standard microelectrode impalement.
Abstract: Although patch pipettes were originally developed for the recording of single channels, they can be of great advantage for more conventional recordings from whole cells, particularly when the cells under study are small. As described by Hamill et al. (1981), a membrane patch can be broken by a short pulse of suction after a gigaseal has been formed. Very often, this manipulation does not damage the pipette-membrane seal, so that a conductive pathway is established between the pipette and the cell interior, which is well insulated from the bath. It is our experience that this way of penetrating a cell inflicts much less damage on the cell than the standard microelectrode impalement.
730 citations
TL;DR: It has been observed that the spontaneous-emission lifetime of Rydberg atoms is shortened by a large ratio when these atoms are crossing a high-Q$ superconducting cavity tuned to resonance with a millimeter-wave transition between adjacent Ryd Berg states as mentioned in this paper.
Abstract: It has been observed that the spontaneous-emission lifetime of Rydberg atoms is shortened by a large ratio when these atoms are crossing a high-$Q$ superconducting cavity tuned to resonance with a millimeter-wave transition between adjacent Rydberg states.
689 citations
TL;DR: In this paper, the synchronization of noise-induced transition processes is studied with the help of a simple electronic bistable system and it is shown that stochastic resonance occurs when the Kramers characteristic transition time equals the external forcing period.
683 citations
TL;DR: In this paper, the authors investigated when patent races will be characterized by vigorous competition and when they will degenerate into a monopoly and showed that a firm with an arbitrarily small headstart can preempt its rivals.
557 citations
TL;DR: The Prony-Pisarenko estimator is adapted to this nonstationary context, the signal considered in this case being the output of a zero-input time-varying system corrupted by an additive white noise.
Abstract: Modeling of nonstationary signals can be achieved through time-dependent autoregressive moving-average models and lattices, by the use of a limited series expansion of the time-varying coefficients in the models. This method leads to an extension of several well-known techniques of stationary spectral estimation to the nonstationary case. Time-varying AR models are identified by means of a fast (Levinson) algorithm which is also suitable for the AR part of a mixed ARMA model. An alternative to this method is given by the extension of Cadzow's method. Lattices with time-dependent reflection coefficients are identified through an algorithm which is similar to Burg's. Finally, the Prony-Pisarenko estimator is adapted to this nonstationary context, the signal considered in this case being the output of a zero-input time-varying system corrupted by an additive white noise. In all these methods the estimation is global in the sense that the parameters are estimated over a time interval [0, T], given the observations [y 0 ... y T ]. The maximum likelihood method which falls within the same framework is also briefly studied in this paper. Simulations of these algorithms on chirp signals and on transitions between phonemes in speech conclude the paper.
461 citations
TL;DR: In this article, the authors describe a simple two-person, two-period bargaining game, and solve it using the concept of perfect Bayesian equilibrium, in which the actions of each player convey information which is used by his opponent.
Abstract: This paper describes a simple two-person, two-period bargaining game, and solves it using the concept of perfect Bayesian equilibrium, in which the actions of each player convey information which is used by his opponent. The paper examines the effects of changes in bargaining costs, the size of the "contract zone", and the length of the bargaining process on such aspects of the solution as the probability of impasse and the likelihood of concessions. The combination of information transfer and the lack of pre-commitment embodied in perfectness yields many surprising results. Common perceptions about the effects of parameter changes on bargaining processes are suspect, and should be checked in the particular game being discussed.
377 citations
TL;DR: In this article, a collection of Rydberg atoms and a resonant millimeter-wave cavity were shown to exchange energy back and forth at a rate of 2π(n σ(n) σ + σ 2 σ − σ σ n/n/n), where n is the electric dipole matrix element of the atomic transition and σ is the field per photon in the cavity.
Abstract: A collection of $N$ Rydberg atoms and a resonant millimeter-wave cavity are shown to exchange energy back and forth at a rate $2(\frac{d}{\ensuremath{\hbar}}){\mathcal{E}}_{0}\sqrt{N}$, where $d$ is the electric dipole matrix element of the atomic transition and ${\mathcal{E}}_{0}$ the "field per photon" in the cavity. This experiment is a demonstration of self-induced Rabi oscillations in a two-level atom system coupled to a single electromagnetic field mode and can also be considered as a very simple illustration of "ringings" in superradiant emission.
362 citations
01 Aug 1983
TL;DR: This work uses column generation on a set partitioning problem solved by simplex and branch-and-bound to determine the number of vehicles required, together with their routes and schedules, so that each trip begins within its given time interval, while the fixed costs related to thenumber of vehicles, and the travel costs between trips, are minimized.
Abstract: Consider a set of trips where each trip is specified a priori by a place of origin, a destination, a duration, a cost, and a time interval within which the trip must begin. The trips may include visits to one or more specific points. Our problem is to determine the number of vehicles required, together with their routes and schedules, so that each trip begins within its given time interval, while the fixed costs related to the number of vehicles, and the travel costs between trips, are minimized. The problem is a generalization of the m-traveling salesman problem. We use column generation on a set partitioning problem solved by simplex and branch-and-bound; columns are generated by a shortest path algorithm with time windows on the nodes. Numerical results for several school bus transportation problems with up to 151 trips are discussed.
TL;DR: In this paper, a photothermal displacement spectroscopy (PDS) was proposed for determining the optical and thermal properties of solids, surfaces and thin films, based on the detection of the thermal expansion of a sample upon absorption of electromagnetic radiation.
Abstract: We present a sensitive technique for determining the optical and thermal properties of solids, surfaces and thin films. This technique, photothermal displacement Spectroscopy, is based on the detection of the thermal expansion of a sample upon absorption of electromagnetic radiation. The technique is well suited for in situ ultrahigh vacuum studies and for experiments where wide temperature ranges are required. We show that surface and bulk optical absorption can be distinguished and that surface absorptions of αL=10−6/W of incident power can be measured. The theoretical basis of the signal generation is given, and excellent experimental and theoretical agreement is demonstrated. The implications of our findings to imaging and microscopy are discussed.
TL;DR: The geodesic distance d x provides rigorous definitions of topological transformations, which can be performed by automatic image analysers with the help of parallel iterative algorithms.
TL;DR: The Nambu string model with fixed ends was solved exactly in this article, and the corresponding static potential was found to be: V(R) = [R 2 /(2πα′) 2 − (D − 2)/24α′] 1/2.
TL;DR: In this article, an off-shell version of the hypermultiplet, without a central charge or gauge antisymmetric tensors, is presented, which allows an N = 2 superspace formulation of the N = 4 super-Yang-Mills theory.
TL;DR: In this paper, the density of states for thermal vibrations on a fractal is calculated with careful attention paid to the normalization condition, and a set of missing modes is identified which may be the origin of the two-level systems hypothesized for amorphous structures.
Abstract: The density of states for thermal vibrations on a fractal is calculated with careful attention paid to the normalization condition. It is found that at the crossover between Debye-type excitations (long wavelength) and "fracton" excitations (short-length scale) the density of states is discontinuous. The size of the discontinuity is related to the ratio of the fracton dimensionality to the Euclidean dimensionality. Application is made to percolating structures. A set of missing modes is identified which may be the origin of the two-level systems hypothesized for amorphous structures. The specific heat of epoxy resin exhibits a crossover from a Debye-type region ($Tl8$ K) to a region (8-50 K) where the vibrational density of states depends linearly on the frequency. Over the same frequency regime, the thermal conductivity exhibits an effective phonon mean free path of the order of (or less than) a lattice constant. We interpret this behavior in terms of quantized fractons, with an energy range 8-50 K, and we suggest that these fracton states are localized. This is consistent with the usual interpretation of a precipitous drop in the phonon mean free path at the crossover energy of 8 K. Analogous behavior is argued for the thermal properties of glasses which exhibit a similar structure in the thermal conductivity. Recent neutron-irradiated quartz experiments tend to confirm this interpretation.
TL;DR: In this paper, the authors reported that the temperatures obtained from the geothermometers based upon the distribution of the major elements are in good agreement with the data from trace element geithermometers.
TL;DR: In this article, the Hamiltonian of a two-dimensional system of up to six interacting electrons, in the lowest Landau level, in a rectangular box with "periodic" boundary conditions, was diagonalized numerically.
Abstract: The authors have diagonalized numerically the Hamiltonian of a two-dimensional system of up to six interacting electrons, in the lowest Landau level, in a rectangular box with "periodic" boundary conditions. They find that the ground state has a pair correlation function quite different from that of a Wigner crystal, and its energy is significantly lower. They also find some indications of a downward cusp in the energy at $\frac{1}{3}$ filling.
TL;DR: The binding properties to rat brain membranes of [3H]TCP, a PCP derivative, are described and it is found that it has a better affinity for PCP binding sites than PCP itself.
TL;DR: In this article, a branch and bound algorithm is used for the solution of the Travelling Salesman Problem, where the main feature of the algorithm lies in the relaxation of the subtour elimination constraints.
Abstract: This paper deals with a generalized version of the Travelling Salesman Problem, which consists of finding the shortest Hamiltonian cycle through n sets of nodes. The problem is formulated as an integer linear program including degree constraints, subtour elimination constraints, and integrality constraints. A branch and bound algorithm is used for the solution of the problem; the main feature of the algorithm lies in the relaxation of the subtour elimination constraints. Computational results for Euclidean and non-Euclidean problems are reported.
TL;DR: In this article, the authors considered a version of the vehicle routing problem in which a non-negative weight is assigned to each city to be visited and where all vehicles are identical and have the same capacity.
Abstract: This paper considers a version of the vehicle routing problem in which a non-negative weight is assigned to each city to be visited and where all vehicles are identical and have the same capacityD. The weight assigned to a vehicle on a given route may not exceed this capacity. The problem is formulated as an integer program: integrality is obtained by means of a branch and bound procedure; capacity constraints are first relaxed, and introduced only when they are found to be violated. Three variants of this basic algorithm are examined. Exact solutions are obtained for problems ranging from 15 to 50 cities.
Diese Arbeit befaβt sich mit einer Variante des Fahrzeugroutenproblems, bei der jeder zu besuchenden Stadt ein nichtnegatives Gewicht zugeordnet ist und bei der alle Fahrzeuge gleich sind und die gleiche KapazitatD haben. Das Problem wird als ganzzahliges lineares Programm formuliert: Ganzzahligkeit wird uber ein Branch und Bound-Verfahren erreicht. Dabei werden die Kapazitatsbeschrankungen zunachst relaxiert und nur dann wieder einbezogen, wenn sie verletzt werden. Drei Varianten dieses Basisverfahrens werden untersucht. Exakte Losungen werden fur Probleme mit 15 bis 50 Stadten erhalten.
Proceedings Article•
01 Jan 1983TL;DR: In this article, the benefits of computer-based applications for data processing departments are considered, and the authors find that in no instances were these factors cited by senior data processing managers as primary success considerations.
Abstract: User development of computer-based applications (UDA) is a new phenomenon in organizations, and can provide benefits for both users and data processing departments. The benefits of UDA for DP departments are considered in this article. The UDA literature suggests that DP departments can expect to receive two major types of benefits: a decrease in the backlog of DP application development projects in the proportion of DP resources spent on application maintenance. However, this study, which was carried out in ten large Canadian business firms, found that in no instances were these factors cited by senior DP managers as primary success considerations.
TL;DR: In this article, the authors analyzed 18 Cenozoic melilitite samples from Spain, France, West Germany and Czechoslovakia for major and trace elements (including REE) together with their Sr and Nd isotopic compositions.
Abstract: Eighteen Cenozoic melilitite samples from Spain, France, West Germany and Czechoslovakia have been analyzed for major and trace elements (including REE) together with their Sr and Nd isotopic compositions. Leaching experiments produced significant shifts of their87Sr/86Sr ratio indicative of a contamination by a crustal component. Most samples fall within the Sr-Nd mantle array with ɛNd values in the 1.5–6 range. These values are considered as minimum for the melilitite mantle source hence demonstrating its time integrated LRE depletion. The Ni and Cr contents of the samples are typical of primary magmas and exclude extensive crystallization of olivine and pyroxene in a closed system. However, the chemical relationships suggest that dilution of the liquids by mafic minerals of the conduits during their ascent has been important. The REE patterns show some variations which are interpreted by this dilution effect. Once normalized to Yb they are closely similar and perfectly distinguishable from those of alkali basalts and kimberlites. All of these rocks have Ce/Yb ratios which are high but distinctive for each rock type: 40 to 200 times the chondritic ratio for kimberlites, 20 to 30 for melilitites, 8 to 15 for alkali basalts. As contamination is likely to have modified somewhat the isotopic characteristics of most of these rocks, there is no overwhelming evidence that their source is chemically different. The Ba and Rb contents together with the REE patterns of the melilitites would constrain the degree of melting to be very small (<0.2%). The calculation of batch melting and steady zone refining models suggests that kimberlites, melilitites and alkali basalts may have been derived by equilibration of deep melts with different upper mantle levels characterized by decreasing garnet/clinopyroxene ratios. The strongly incompatible elements are enriched in the melt during its ascent by leaching of the wall rocks. For the steady zone refining model, the degree of melting concept loses its significance and the difficult requirement of extracting small liquid fractions from a molten source disappears. Within the frame of this model, the preenrichment of the kimberlite, melilitite and alkali basalts source in incompatible elements by metasomatic fluids is no longer necessary.
TL;DR: The results for 34 college students confirmed previous data showing high performance in identification of all emotions, although there were some important differences between emotions.
Abstract: The aim of the experiment was to study the relation between accuracy of judgment of facial expressions of emotions and time for judgment The results for 34 college students confirmed previous data showing high performance in identification of all emotions, although there were some important differences between emotions Also, times for judgment were longer for the emotions which were more difficult to identify
TL;DR: The mesomorphic behavior of octa (dodecyloxymethyl) phthalocyanine was studied with DSC, optical microscopy, and X-ray diffraction.
Abstract: The mesomorphic behavior of octa (dodecyloxymethyl) phthalocyanine was studied with DSC, optical microscopy, and X-ray diffraction. Two discotic mesophases were observed as a function of temperature. Their structure corresponds to the piling up of the flat molecules in columns which are laterally assembled according to a two-dimensional hexagonal lattice (D = 31.2 A). The repeat distance of the molecules along the columns was found to be of about 4.5 A. The low-temperature discotic phase showed an extra sharp reflection at 20.5 A, indicating a further ordering of the molecules.
TL;DR: The results of a study on the effects of several macrolide antibiotics including oleandomycin, erythromycin derivatives, josamycin, methymycin, tylosin, spiramycin and rifampicin as well as antibiotics of other series, such as tetracycline and lincomycin on rat liver cytochromes P-450 in vivo and in vitro are reported.
01 Mar 1983
TL;DR: In this paper, a facon didactique le calcul de la capacitance complexe de charges d'espace constituees de porteurs libres pouvant se deplacer entre electrodes plus ou moins bloquantes.
Abstract: Apres avoir rappele l'origine de la relation de Debye pour la relaxation dipolaire, on presente d'une facon didactique le calcul de la capacitance complexe de charges d'espace constituees de porteurs libres pouvant se deplacer entre electrodes plus ou moins bloquantes. On discute alors l'analogie formelle existant entre la relaxation d'un ensemble de dipoles permanents et celle d'une charge d'espace, et on propose des verifications experimentales du modele.
TL;DR: In this article, the authors studied the routes to chaos for a Rayleigh-Benard experiment in mercury, as a function of two parameters, the Rayleigh number (R ) and the Chandrasekhar number (Q ).
TL;DR: In this paper, high precision nuclear reaction resonance width measurement techniques were applied to the 429 keV resonance in 15N(p, αγ) 12C yielding a result which may be stated at present as: Γ=120±30) eV.