Showing papers by "Paul Sabatier University published in 1992"
TL;DR: In this paper, the authors implique l'accord avec les conditions générales d'utilisation (http://www.numdam.org/legal.php).
Abstract: © Publications mathématiques de l’I.H.É.S., 1992, tous droits réservés. L’accès aux archives de la revue « Publications mathématiques de l’I.H.É.S. » ( http://www. ihes.fr/IHES/Publications/Publications.html), implique l’accord avec les conditions générales d’utilisation (http://www.numdam.org/legal.php). Toute utilisation commerciale ou impression systématique est constitutive d’une infraction pénale. Toute copie ou impression de ce fichier doit contenir la présente mention de copyright.
1,260 citations
01 Jan 1992
TL;DR: It is argued that fuzzy sets and rough sets aim to different purposes and that it is more natural to try to combine the two models of uncertainty (vagueness for fuzzy set and coarseness for rough sets) in order to get a more accurate account of imperfect information.
Abstract: In this paper we argue that fuzzy sets and rough sets aim to different purposes and that it is more natural to try to combine the two models of uncertainty (vagueness for fuzzy sets and coarseness for rough sets) in order to get a more accurate account of imperfect information. First, the upper and lower approximations of a fuzzy set are defined, when the universe of discourse of a fuzzy sets is coarsened by means of an equivalence relation. We then come close to Caianiello’s C-calculus. Shafer’s concept of coarsened belief functions also belongs to the same line of thought and is reviewed here. Another idea is to turn the equivalence relation relation into a fuzzy similarity relation, for a more expressive modeling of coarseness. New results on the representation of similarity relations by means of a fuzzy partition of fuzzy clusters of more or less indiscernible points are surveyed. The properties of upper and lower approximations of fuzzy sets by similarity relations are thoroughly studied. Lastly the potential usefulness of the fuzzy rough set notions for logical inference in the presence of both fuzzy predicates and graded indiscernibility is indicated. Especially fuzzy rough sets may provide a nice semantic background for modal logic involving fuzzy modalities and/or fuzzy sentences.
656 citations
TL;DR: It is shown that the Infinite Symmetric Exponential Filter (ISEF), derived from the well-known mono-step edge model, is optimal for both mono- and multiedge detection.
410 citations
TL;DR: In this paper, the problem of combining possibility distributions viewed as upper probabilities is investigated, and the basic fuzzy set intersections are justified in this framework, and approximate approximations of upper probabilities by possibility measures are discussed.
321 citations
TL;DR: In this paper, a variational procedure to calculate singlet-triplet energy differences in diradical systems is described, which includes all the differential second-order contributions, based on the theory of effective Hamiltonians.
267 citations
TL;DR: A representation of gradual inference rules of the form “The more X is F , the more Y is G ” by means of fuzzy sets turns out to be based on a special implication function already considered in multiple-valued logic.
251 citations
TL;DR: In this article, the authors studied the effect of mechanical interactions between rigid particles on the development of preferred orientations of rigid particles in two-dimensional (2.5D) meshes.
175 citations
TL;DR: In this article, a palynological investigation has been carried out in the southern, northern and Mediterranean part of the Pyrenean chain and the results show that the steppe and semi-desert vegetation of the end of the last glacial period are described, as well as the plant communities of the period 15-13 ka.
168 citations
TL;DR: The history of research on avascular necrosis of the femoral head during the past 30 years includes clinical and radiologic data, etiology and epidemiology, histopathology, and other methods of exploration, pathophysiology and pathogenesis, and treatments.
Abstract: The history of research on avascular necrosis of the femoral head during the past 30 years includes clinical and radiologic data, etiology and epidemiology, histopathology, and other methods of exploration, pathophysiology and pathogenesis, and treatments. Preradiologic stages of the disease, its association with corticosteroid treatment, the use of core biopsy and magnetic resonance imaging for an early diagnosis, the pathogenetic significance of increased intramedullary pressure and of lipid metabolism and fat cell changes, and conservative surgical procedures such as core decompression and rotational osteotomy constitute important areas for further investigation as outlined in detail in this review.
154 citations
01 Jan 1992
TL;DR: The problem of combining pieces of evidence issued from several sources of information, encountered in expert systems when several production rules conclude on the value of the same variable, but also in robotics when information coming from different sensors is to be aggregated.
Abstract: The problem of combining pieces of evidence issued from several sources of information turns out to be a very important issue in artificial intelligence. It is encountered in expert systems when several production rules conclude on the value of the same variable, but also in robotics when information coming from different sensors is to be aggregated. Solutions proposed in the literature so far have often been unsatisfactory because relying on a single theory of uncertainty, a unique mode of combination, or the absence of analysis of the reasons for uncertainty. Besides dependencies and redundancies between sources must be dealt with especially in knowledge bases, where sources correspond to production rules.
135 citations
TL;DR: Two distinct isoforms of cinnamyl alcohol dehydrogenase, CAD 1 and CAD 2, have been purified to homogeneity from xylem-enriched fractions of Eucalyptus gunii Hook and partially characterized, indicating their involvement in specific pathways of monolignol utilisation.
Abstract: Two distinct isoforms of cinnamyl alcohol dehydrogenase, CAD 1 and CAD 2, have been purified to homogeneity from xylem-enriched fractions of Eucalyptus gunii Hook and partially characterized. They differ greatly in terms of both physical and biochemical properties, and can be separated by hydrophobic interaction chromatography on Phenyl Sepharose CL-4B. The native molecular weight of of CAD 1 is 38 kDa as determined by gel-filtration chromatography on Superose 6, and this isoform is likely to be a monomer since it yields a polypeptide of 35 kDa upon sodium dodecyl sulfatepolyacrylamide gel electrophoresis. It has a low substrate affinity for coniferyl and p-coumaryl alcohols and their corresponding aldehydes. No activity with sinapyl aldehyde and alcohol was detected. The more abundant isoform is CAD 2, which has a native molecular weight of 83 kDa and is a dinier composed of two subunits of slightly different molecular weights (42-43 kDa). These subunits show identical peptide patterns after digestion with N-chlorosuccinimide. The isoform, CAD 2, has a high substrate affinity for all the substrates tested. The two isoforms are immunologically distinct as polyclonal antibodies raised against CAD 2 do not cross-react with CAD 1. The characterization of two forms of CAD exhibiting such marked differences indicates their involvement in specific pathways of monolignol utilisation.
TL;DR: A model based on a particle-in-cell Monte Carlo simulation has been developed to study the physical properties of nonthermal dusty plasmas and the plasma-dust particle interactions.
Abstract: Nonthermal dusty plasmas can be found in plasma-processing applications as well as in space phsyics. A model based on a particle-in-cell Monte Carlo simulation has been developed to study the physical properties of such plasmas and the plasma-dust particle interactions. Assuming a uniform dusty plasma with a given size and concentration of dust particles, the model provides self-consistently the average electric field necessary to sustain the plasma for a given current density flowing through it, the charge and floating potential of the dust particles, the potential distribution, and the velocity distribution functions of electrons and positive ions. The model has been applied to situations where the distance between dust particles is much smaller than the electron Debye length (particulates interact electrostatically with each other) as well as situations where the distance between dust particles is larger than the Debye length (particulates are isolated electrostatically from each other). Questions concerning the momentum and energy transfer from electrons and ions to dust particles are also discussed. Simple scaling laws are also derived and compared with the numerical results.
TL;DR: In this paper, a hydrodynamic theory is presented to describe the phenomenon of limiting flux in membrane processe, based on a development of film theory, which shows that the variation of viscosity with concentration will, by its very nature, lead to a limiting flux.
TL;DR: In this paper, the ionization potentials of Lin clusters were obtained by photoionization and shell effects were observed at n = 8 and n = 20, as well as strong odd/even alternations.
TL;DR: It appears that the phase shift between current and voltage is very sensitive to the presence of powders, which could be useful for the detection of powder formation in a processing plasma.
Abstract: Self-consistent fluid and particle-in-cell Monte Carlo (PIC-MC) models in conjunction with experimental measurements have been used to study the electrical characteristics of rf discharges in pure argon and in argon contaminated with dust particles (at 0.11 torr argon, 13.56 MHz). In the experiments, the dust particles were first created in a silane-argon rf discharge and subsequently trapped in an argon discharge in order to stop the growth process. The concentration and radius of the dust particles were measured experimentally and found equal to ${10}^{8}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}3}$ and 0.05 \ensuremath{\mu}m, respectively. The PIC-MC discharge model has been used to check the validity of the fluid model in pure argon. The discharge in dusty argon has been described with a fluid model modified to account for the presence of dust particles. This model uses as input data the number of negative charges carried by the dust particles and the frequency of electron loss to the particles deduced from a two-dimensional particle-in-cell Monte Carlo simulation of a dusty dc plasma. The results show good agreement between experiments and models within the whole range of rf voltages considered and for the pure and dusty argon plasmas. The presence of dust particles in the plasma modifies considerably the discharge impedance, which becomes much more resistive. The electron number density in the plasma is much smaller than the positive ion density and than the number density of negative charges carried by the dust particles. It appears that the phase shift between current and voltage is very sensitive to the presence of powders. This property could be useful for the detection of powder formation in a processing plasma.
TL;DR: Drosophila melanogaster flies climb up the sides of their vial after having been submitted to a mechanical stimulation; that ability is impaired at older ages, and older flies kept in hypergravity displayed lower scores than flies kept at 1 g.
Abstract: Drosophila melanogaster flies climb up the sides of their vial after having been submitted to a mechanical stimulation; that ability is impaired at older ages. The climbing activity (CLI) of flies kept at various gravity levels (1, 3 and 5 g) has been measured throughout life, in cross-sectional studies. Hypergravity had no effect on CLI at young age, but older flies kept in hypergravity displayed lower scores than flies kept at 1 g. Results are discussed in relation with the hypothesis of increased aging rate in hypergravity.
TL;DR: In this paper, it was shown that fγ is convex, polyconvex, quasiconvex and rank-one convex if and only if ¦γ¦≦ 2/3 √2, 1, 1+1+1, 1 + 1+√1, 2/√3, respectively.
Abstract: We study the different notions of convexity for the function fγ(ξ) = |ξ|2 (|ξ|2 − 2γ det ξ) where ξ e ℝ2×2, introduced by Dacorogna & Marcellini. We show that fγ is convex, polyconvex, quasiconvex, rank-one convex, if and only if ¦γ¦≦ 2/3 √2, 1, 1+ɛ (for some ɛ>0), 2/√3, respectively.
TL;DR: This article addresses most of the questions raised by Pearl in the 1990 special issue of the International Journal of Approximate Reasoning on belief functions and belief maintenance in artificial intelligence.
TL;DR: In this paper, a one-dimensional version of a multilevel mesoscale model is used to represent the cloud-topped boundary layer (CTBL), which is parameterized with a prognostic equation for the turbulent kinetic energy and an improved length-scale formulation.
Abstract: A one-dimensional version of a multilevel mesoscale model is used to represent the cloud-topped boundary layer (CTBL). Turbulent exchanges are parameterized with a prognostic equation for the turbulent kinetic energy and an improved length-scale formulation. Furthermore, the scheme is extended to give a statistical description of the subgrid-scale condensation with a one-and-a-half-order closure.Several observed reference cases are simulated in order to test the model against observational data and results obtained with a higher-order turbulence model. The latter one is used as a powerful approach for testing the closure of the second-order moments involved in the partial cloudiness scheme. Two of the reference cases are extracted from stratocumulus (Sc) observations off the coast of the United Kingdom with a purely buoyancy-driven and a purely shear-driven CTBL, respectively. The third experiment tries to reproduce a case of Californian Sc clouds where both turbulent effects are important. Final...
06 Jul 1992
TL;DR: This paper presents a methodological approach to the management of symbolic preferences in integration with classical pure logical reasoning problems and investigates two selection modes for choosing preferred sets of assumptions: democratism and elitism.
Abstract: This paper presents a methodological approach to the management of symbolic preferences in integration with classical pure logical reasoning problems. We investigate two selection modes for choosing preferred sets of assumptions: democratism and elitism.
TL;DR: Caution should be exercised in inferring multiple inseminations, as is frequently done in eusocial insects, from the observation of multiple copulations in the Argentine ant Iridomyrmex humilis.
Abstract: In ants, because males have a finite sperm supply and females mate only at the beginning of their reproductive lives, it is possible to infer which is the limiting sex from a few parameters: the amount of sperm produced by males, the amount of sperm stored by females, and the numerical sex ratio. In the Argentine ant Iridomyrmex humilis mating takes place in the nest. Laboratory experiments and field data showed that the numerical sex ratio is heavily male-biased (10.1:1) and that the maximum number of sperm a female can store is similar to the number of sperm a male possesses. Thus females are the limiting sex in this species. In a set of mating experiments, one queen was presented with 1–20 males. The highest proportion of successful matings occurred when females were presented with two males. There was a significant negative correlation between the amount of sperm queens stored and the number of males present in the mating arena. This relationship most likely resulted from male interference during the copulation process. When several males were present in the arena, the mating pair was frequently disturbed by other males trying to copulate. Newly mated queens collected from the field stored 172,000 ± 76,000 sperm, a quantity most similar to that measured in laboratory mating experiments with a ratio of 5 or 10 males per queen. Because the operational sex ratio in I. humilis is highly male-biased, male interference may also decrease the amount of sperm queens store in the field. In many ants, fewer sperm stored by queens should decrease their reproductive success because they would run out of sperm earlier in their reproductive lifetimes. However, comparison of the amount of sperm present in young and old I. humilis queens collected in the field suggests that most use only a small proportion of their sperm supply during their lifetimes. Males mate once and discharge all their sperm during a single mating. Females may mate with several males but dissection of these males indicated that in most cases only one of them had empty seminal vesicles thus suggesting that a single male is responsible for most of the sperm transfer. Thus caution should be exercised in inferring multiple inseminations, as is frequently done in eusocial insects, from the observation of multiple copulations.
TL;DR: In this article, a criterion of stability for PCA scatterplots is defined based on a classical distance between projectors, which is constructed as a risk function and can be estimated by bootstrap or jackknife methods.
TL;DR: Numerical calculations of the quantum diffusion over an octagonal quasiperiodic tiling are presented and it is found that unlimited diffusion occurs with anomalous exponents both in the hopping regime, where the spectrum has a band structure, and in the strong-coupling regime, which has a Cantor structure.
Abstract: We present numerical calculations of the quantum diffusion over an octagonal quasiperiodic tiling. We have studied a one-parameter family of Hamiltonians including the pure hopping case, the Laplacian, and a regime where atomic potentials prevail. We have found that unlimited diffusion occurs with anomalous exponents both in the hopping regime, where the spectrum has a band structure, and in the strong-coupling regime, where the spectrum has a Cantor structure. Upon introducing disorder in the lattice through phasonic fluctuations, the diffusion exponent increases in the pure hopping regime, while localization appears in the strong-coupling regime. The consequences on the conductivity of real quasicrystals are considered.
TL;DR: The reaction of sodium β-naphthoxide with benzyl halides in molten tetraalkylammonium or phosphonium halides (at 110°C or below) leads to a highly regioselective O-alkylation as discussed by the authors.
TL;DR: In this article, the effect of the presence of volatiles (N2, CH4, CO2) on tungsten speciation and scheelite solubility in aqueous solations buffered by the calc-silicate gneisses and by the micaschists assemblages was investigated.
Abstract: Scheelite-bearing calc-silicate gneisses (CSG) oceur in the Montagne Noire within a series of dominant micaschists. Detailed petrographical and mineralogical studies reveal three successive stages of metamorphism and hydrothermal alteration: (1) stage 1, a regional metamorphism at 550°C and 4.5 kb where no mineralization is formed; (2) stage 2a, a hydrothermal alteration at 500 to 450°C and 4 to 3 kb which is characterized by an intense sericitization of feldpars and deposition of Sn in Sn-bearing cale-silicates; and (3) stage 2b, a hydrothermal alteration characterized by the crystallization of idocrasegrossular in CSG with concomittant precipitation of scheelite. Tungsten was transported through the micaschist environment and deposited as scheelite only in the CSG of stage 2b at relatively low pressures. To characterize the mechanism of tungsten transport, tungsten speciation at high P-T and scheelite solubility in aqueous solations buffered by the CSG and by the micaschists assemblages were calculated. It was found that H2WO
0
4
, HWO
-
4
and WO
2-
4
are the dominant tungsten aqueous species in H2O−NaCl (one molal) solutions at 500°C and 2–4 kb. Calculations also indicate that scheelite deposition is controlled by decreasing pressure and increasing activity of aqueous calcium in this system. This is consistent with the petrographical and mineralogical observations. The consequences of the presence of volatiles (N2, CH4, CO2) in the regional fluids were examined by determining the effect of N2 on tungsten speciation and scheelite solubility. The addition of N2 (up to 10 mol%) to the mineralizing fluids results in a marked increase in H2WO
0
4
and HWO
-
4
concentrations relative to WO
2-
4
and in a large decrease of scheelite solubility. This mechanism favours scheelite precipitation and accounts for the commonly observed association of W (and Sn) deposits with graphitic series generating mixed volatiles fluids.
TL;DR: In this article, the authors define four different dressings of the singles and doubles CI matrix which take into account the dominant effect of triple and quadruple excitations, and discuss the relative advantages of the different versions.
TL;DR: In this article, the authors review multiscattering models for spherical particles, quasistatic mixture laws, effective medium theories, percolation equations, and finally the general effect.
Abstract: The purpose of this paper is to review the multiscattering models for spherical particles, quasistatic mixture laws, effective medium theories, percolation equations, and finally the general effect...
TL;DR: The growth model established allows estimation of the growth rate of Porphyridium cruentum within the ranges of temperature 5–35°C and light intensities 0 to 1100 μmol photons m −2 s −1 .
01 Jan 1992
TL;DR: Four distinct types of rules with different semantics involving gradedness and uncertainty are introduced and the combination operations which appear for taking advantage of the available knowledge are all derived from the intended semantics of the rules.
Abstract: The paper starts with ideas of possibility qualification and certainty qualification for specifying the possible range of a variable whose value is ill-known. The notion of possibility which is used for that purpose is not the standard one in possibility theory, although the two notions of possibility can be related. Based on these considerations four distinct types of rules with different semantics involving gradedness and uncertainty are then introduced. The combination operations which appear for taking advantage of the available knowledge are all derived from the intended semantics of the rules. The processing of these four types of rules is studied in detail. Fuzzy rules modelling preference in decision processes are also discussed.
TL;DR: These impurities were found to be degradation products of FU that are formed in the basic medium employed to dissolve this compound and should be avoided to avoid chemical degradation of this antineoplastic drug.
Abstract: The cardiotoxicity of 5-fluorouracil (FU) was attributed to impurities present in the injected vials. One of these impurities was identified as fluoroacetaldehyde which is metabolised by isolated perfused rabbit hearts into fluoroacetate (FAC), a highly cardiotoxic compound. FAC was also detected in the urine of patients treated with FU. These impurities were found to be degradation products of FU that are formed in the basic medium employed to dissolve this compound. To avoid chemical degradation of this antineoplastic drug, the solution of FU that will be injected should be prepared immediately before use.