Showing papers by "Conservatoire national des arts et métiers published in 1993"

Gram: a graph data model and query languages

Abstract: We present a model for data organized as graphs. Regular expressions over the types of the node and edge labels are used to qualify connected subgraphs. An algebraic language based on these regular expressions and supporting a restricted form of recursion is introduced. A natural application of this model and its query language is hypertext querying.

The immune response in iron-deficient young children: effect of iron supplementation on cell-mediated immunity.

Abstract: The effects of iron deficiency on immunity remain controversial. This study was designed to assess the impact of iron supplementation on the immune status, in 81 children aged 6 months–3 years, at high risk for iron deficiency, using a longitudinal double blind randomised and placebo-controlled study. Lymphocytes of iron-deficient children produced less interleukin-2 in vitro. Iron supplementation for 2 months increased mean corpuscular volume, serum ferritin and serum transferrin, but had no effect on the parameters of T-cell mediated immunity. The lower interleukin-2 levels in iron-deficient suggest that cell-mediated immunity may be impaired in iron deficiency.

Por um trabalho, fator de equilíbrio

Abstract: The professional activity isn't only a way of life: it is also a means of social insertion where the psychic and physical aspects are strongly concerned. Working can be a factor of deterioration, of aging and serious diseases, but it can also be a factor of equilibrium and self development. The possibility of the second hypothesis is linked to a kind of work that allows each person to combine his physical needs to his desire of doing the task.

Unsteady confined buoyant plumes

Abstract: Two-dimensional time-dependent buoyancy-induced flows above a horizontal line heat source inside rectangular vessels, with adiabatic sidewalls and top and bottom walls maintained at uniform temperature, are studied numerically. Transitions to unsteady flows are performed by direct simulations for various depths of immersion of the source in the central vertical plane of air-filled vessels. For a square vessel and a line source near the bottom wall, the numerical solutions exhibit a sequence of instabilities, called natural swaying motion of confined plumes, beginning with a periodic regime having a high fundamental frequency followed by a two-frequency locked regime. Then, broadband components appearing in the spectra indicate chaotic behaviour and a weakly turbulent motion arises via an intermittent route to chaos. For rectangular vessels of aspect ratio greater than 2 and depths of immersion greater than the width, the flow undergoes a pitchfork bifurcation. This symmetry breaking is driven by the destabilization of an upper unstable layer of stagnant fluid above the plume. Then a subcritical Hopf bifurcation occurs. On the other hand, if the depth of immersion is lower than the width of the vessel, a stable layer of fluid is at rest below the line source. Then penetrative convection sets the whole air-filled vessel in motion and an oscillatory motion of very low frequency arises through supercritical Hopf bifurcation followed by a two-frequency locked state.

Towards a simplified building of time Petri Nets reachability graph

Abstract: An enumerative approach for time Petri nets (or Melin's model) analysis is presented. In this model, if a transition t is enabled at time /spl tau/, it can be fired at any time in the interval [/spl tau/+tmax(t)]. It is shown that the firing condition at the nth firing can be expressed by the means of the marking, the enabling point of enabled transitions, and the minimal and maximal elapsed time between to firings. This result leads to an attractive definition of state classes and allows a simple computation of reachable state classes. The approach presented has two main advantages. First, the computation of reachable state classes is more simple and does not require any solution of a system. Second, the graph obtained is a subgraph of that given by M. Menasche (1982). >

Pharmaceutical compositions containing 3-beta-hydroxylated 6,7-substituted steroid derivatives, and use thereof

Abstract: A pharmaceutical composition containing 7-hydroxylated derivatives of natural steroid hormones having, if necessary, a 3β hydroxyl function, for use as an immunity trigger or stimulant (hereinafter termed "immunity effector"), particularly for cell immunity. Said pharmaceutical compositions may also be used as anti-glucocorticoid agents.

Oxidative stress may contribute to the intestinal dysfunction of weanling rats fed a low protein diet.

Abstract: Intestinal function is impaired in malnutrition. Because oxidative stress is a component of gastrointestinal injury, and malnutrition may reduce antioxidant defenses, we investigated the involvement of oxidative stress in the intestinal dysfunction due to malnutrition. Weanling rats were fed either a normal protein (22% casein) or a low protein (6% casein) diet for 4 wk. In intestinal homogenates, we assessed free radical damage and enzymatic antioxidant defenses. In jejunal fragments mounted in Ussing chambers, we measured ionic transport by short-circuit current (Isc) and protein permeability by transepithelial fluxes of beta-lactoglobulin. Catalase activity and the thiobarbituric acid-reacting substances concentration were greater in intestinal mucosa of the low protein group, whereas the glutathione concentration and the activities of superoxide dismutase and Se-dependent glutathione peroxidase were the same as in the normal protein group intestinal mucosa. Both basal Isc and the delta Isc induced by glucose and forskolin, as well as beta-lactoglobulin fluxes, were higher in the low protein group. Exogenous H2O2 stress increased Isc significantly more in the low protein than the normal protein group but did not alter protein permeability. These results show that malnutrition induces both intestinal free radical damage and altered epithelial transport, suggesting that oxidative stress may contribute to the intestinal dysfunction associated with malnutrition.

Atomic beam magnetic resonance apparatus for systematic measurement of hyperfine structure anomalies (Bohr-Weisskopf effect)

Abstract: An atomic beam magnetic resonance (ABMR) apparatus has been constructed at Orsay, and has been installed at the CERN PS Booster ISOLDE mass separator facility for “on-line” work with radioactive isotopes in a program to measure hyperfine structure anomalies (the Bohr-Weisskopf effect) over long isotopic chains. The hfs anomalies result from the effect of the spatial distribution of the nuclear magnetization on the atomic hfs interaction. Constructional details of the system are described: emphasis is placed on the measurement of nuclear g-factors by a triple resonance, laser state selected, ABMR method. A precision better than 10−4 for gI values has been obtained in stable atomic beam tests, leading to hfs anomaly measurements better than 10 percent. Two types of detection systems are described: laser fluorescence and surface ionization coupled with mass spectrometry.

Radiolytic products study of dicyclohexano-18-crown-6, a selective extractant for nuclear fuel reprocessing

Abstract: The radiolytic products of the DCH18C6 obtained after γ-irradiation have been determined, and the seven main structures have been separated and analyzed. The radiolytic product yields range from about 0.01 to nearly 0.3 molecules per 100 eV absorbed by the DCH18C6 at an energy of 3290 kGy. From the viewpoint of radiation decomposition rate, the DCH18C6 presents a considerable resistance and its radiolytic products have little or no extraction power.

An Efficient Algorithm for Finding Structural Deadlocks in Colored Petri Nets

Abstract: In this paper, we present an algorithm to compute structural deadlocks in colored nets under specified conditions. Instead of applying the ordinary algorithm on the unfolded Petri net, our algorithm takes advantage of the structure of the color functions. It is obtained by iterative optimizations of the ordinary algorithm. Each optimization is specified by a meta-rule, whose application is detected during the computation of the algorithm. The application of such meta-rules speeds up a step of the algorithm with a factor proportional to the size of a color domain. We illustrate the efficiency of this algorithm compared to the classical approach on a colored net modelling the dining philosophers problem.

Alkaline solid polymer electrolyte, electrode and electrochemical generator containing such as electrolyte

Abstract: Aqueous alkaline solid electrolyte comprising a polar polymer matrix which is solid at ambient temperature, and a compound or mixture of basic compounds selected from alkaline metal, alkaline-earth or ammonium hydroxides. Preferably, the matrix is a polyether homopolymer or copolymer of different ethers or polyethers. The invention also concerns electrodes and/or electrochemical generators containing such an alkaline polymer solid electrolyte.

Determination of picomole amounts of carbonyls as luminarin hydrazones by high-performance liquid chromatography with fluorescence detection

Abstract: Fluorogenic reagents (luminarin 3, luminarin 11 and luminarin 12), having a quinolizinocoumarin moiety as fluorophore and a carboxylic acid hydrazide function as reacting group, have been developed. These reagents were found to be highly sensitive fluorescence derivatization reagents for aldehydes and ketones in high-performance liquid chromatography. The reagents readily react with carbonyl compounds in aqueous sulphuric acid solution (0.1 M) at room temperature to produce the corresponding hydrazone derivatives, which can be separated on both reversed or normal-phase column. The structures of the derivatives were studied, together with their properties in reversed and normalphase chromatographic systems. UV absorbance, corrected fluorescence spectral data and quantum yields of luminarin 3, luminarin 11 and luminarin 12 are presented. The detection limits (signal to noise ratio=3) for aldehydes and ketones were in the sub-pmol range. Luminarin 3 was also applied to the determination of hydroxymethylfurfural (HMF) in orange juices and concentrates. The method for HMF involves the solid-liquid extraction of the juice by using a C-18 cartridge prior to derivatization and normal-phase separation of the derivative with fluorimetric detection at 387 nmex., 444 nm em. The calibration curve was linear for amounts of HMF ranging from 0.1 to 10 nmol. Intrarun relative standard deviation was 12.8% for 0.1 nmol and 2.6% for 1 nmol. Recovery studies indicated an average of 98.7±1.9% for juice concentrate and 99.8±3.2% for pasteurized juice.

Détermination expérimentale des pertes de froid occasionnées par l'ouverture d'une porte de chambre froide industrielle

Abstract: Resume La porte de la chambre froide s'ouvre par glissement lateral. L'air froid lourd sort par le bas et l'air chaud leger entre par le haut de la porte. Il a ete montre que l'ecoulement de l'air est horizontal dans les parties hautes et basses de la porte. Les profils de vitesse et de temperature ont ete determines pour effectuer le bilan des transferts thermiques. L'air chaud en penetrant dans la chambre echange 3,4% de sa chaleur. Les resultats de mesure ont ete correles par une relation qui exprime le debit-masse en fonction de l'ecart de temperature. Une comparaison de ces resultats avec une approche theorique simplifiee est faite. Enfin des rideaux d'air protecteurs ont ete experimentes. Ce systeme apporte un gain de 38% sur le debit-masse d'air chaud entrant en chambre froide; ce qui rend cette technique interessante.

Port-controlled hamiltonian systems: modelling origins and systemtheoretic properties

Abstract: It is shown that the network representation (as obtained through the generalized bond graph formalism) of non-resistive physical systems in interaction with their environment leads to a well-defined class of (nonlinear) control systems, called port-controlled Hamiltonian systems. A first basic feature of these systems is that their internal dynamics is Hamiltonian with respect to a Poisson structure determined by the topology of the network and to a Hamiltonian given by the stored energy. Secondly the network representation provides automatically (intrinsically to the notation) to every port-control variable (input) a port-conjugated variable as output. This definition of port-conjugated input and output variables, based on energy considerations, is shown to have important consequences for the observability and controllability properties, as well as the external characterization of port-controlled Hamiltonian systems.

Recursive distributed programming schemes

Abstract: Distributed recursive waves, a distributed programming scheme based on a procedure that calls n (or none) concurrent executions of itself, is defined. Three kinds of recursive waves (sequential, based on a tree, based on a flooding) and the example of a distributed recursive termination, respectively, are presented. Distributed recursive programming provides a natural style for writing distributed algorithms. It does not support the overhead drawback of the centralized computer recursivity. Solutions to distributed problems using the message passing wave approach or the distributed iteration scheme can also be expressed in the distributed recursive approach with the same message complexity. >

A map editing kernel implementation: application to multiple scale display

Abstract: User interfaces are a fundamental component of applications using as a support. Geographic Information Systems (GIS) and geographic DataBase Management Systems (DBMS). We propose in this paper a model and an architecture for designing Geographic Database User Interfaces (GDUI). A GDUI kernel based on this architecture has been implemented using, at the interface programming level, X Windows, Motif and C++, and, at the database level, the GeO2 data model [DRS93b] implemented itself on top of the O2 DBMS. From the starting model, we make a first proposal for multiple scale map display.

A systolic QRD-based algorithm for adaptive filtering and its implementation

Abstract: A typical least squares algorithm based on the technique of QR decomposition (QRD) is first reviewed. Problems for direct VLSI implementation are pointed out and a modification of the algorithm to obtain a systolic version is proposed. The systolic QRD-based algorithm should be useful for applications of least squares techniques to adaptive filtering. The CORDIC-based implementation of this cascadable algorithm is presented and its robustness to the roundoff errors is discussed. >

Politics and policies in the scientific and technical information sector in France

Abstract: After an historical survey of the progressive appari tion of politics and policies in the scientific and technical information field in France, we present some of the present characteristics of French politics and policies in this field: in the private and public sectors, at the regional, national and international levels. The role of professional and scientific societies is also discussed, and some comments are made on the education and research politics and policies in the infor mation field.

Bond-graph enumeration of the configurations of power static converters

Abstract: In this paper, we propose bond-graph models and their causal analysis for the systematical enumeration of the possible configurations in the static power converters. This analysis is carried out by considering the switches as ideal (two binary states ON and OFF) and taking into account the commutations constraints. Firstly usual switches are modelled with bond-graph 1-port elements, which state induces the variable topology of the converters networks. The dynamical discrete event behaviour of the converters are described by Petri nets. The states of the Petri nets are defined locally for the ideal switches, and deduced globally for the converters by using a double causal analysis procedure. The method is applied to a voltage bridge inverter structure. >