Showing papers by "Paul Sabatier University published in 1980"

New Results about Properties and Semantics of Fuzzy Set-Theoretic Operators

Abstract: This communication is a first step towards a general approach to fuzzy set-theoretic operators, i.e. algebraic operators which coincide with set-operators when membership values are crisp. Some properties of subclasses of such fuzzy set-theoretic operators are investigated. Specific examples are given. An attempt to discuss a possible interpretation of these operators is proposed. The choice of a good operator in a given practical situation can be crucial in decision analysis, information retrieval, pattern recognition for the purpose of aggregating several pieces of information.

Testing the arbitrariness and limits of a pseudopotential technique through calculations on the series of diatoms HF, AlH, HCl, AlF, AlCl, F2, Cl2

Abstract: The pseudopotential techniques present some degrees of freedom, the influence of which on molecular calculations must be tested to assess the stability and accuracy of the results. The present work uses a semi-local pseudopotential extracted from near Hartree-Fock atomic calculations; the shape of the inner part of the pseudoorbital, the analytic form of the pseudopotential are shown to have less influence than the choice of the valence basis set which must be optimized. The calculated molecular constants perfectly agree with the large basis set all-electron calculations, even for polar molecules.

Electron diatomic molecule weighted total cross section calculation

Abstract: In this paper, the third part in this series, improvements in the weighted total cross section (W.T.C.S.) calculation are indicated and a catalogue of the main W.T.C.S. values for nitrogen (molecule and molecular ion) is presented. These values correspond to excitation and dissociation cross sections by electron impact on N2 of N+2 assuming a 300 K target gas. Ionization cross sections are also given. W.T.C.S. have been calculated also in a two-temperature plasma with θ ≤ 12 000 K and θg≤θe,. From these values we propose approximate formulas allowing rate coefficient determination for the corresponding processes.

Histogenesis of the endocrine pancreas in newborn rats after destruction by streptozotocin. An immunocytochemical study.

Abstract: Endocrine pancreatic tissue in newborn rats was studied 1 to 17 days after the destruction of B cells by an injection of streptozotocin. Regeneration of insulin cells was observed four days after streptozotocin injection, which was followed by recovery from the diabetic state and an increased pancreatic insulin content. Regeneration was characterised by new islets budding from small ducts. The pancreas of newborn rats, like the embryonic pancreas, thus retains a capacity to form endocrine tissue, although some degree of reduplication of preexisting B cells may also be involved in the process. Newborn rats injected with streptozotocin constitute an interesting model for the study of factors which may act on the regenerative potential of pancreatic endocrine tissue in the diabetic state.

Analytical relativistic self-consistent-field calculations for atoms

Abstract: A new second-order representation of the Dirac equation is presented. This representation which is exact for a hydrogen atom is applied to approximate analytical self-consistent-field calculations for atoms. Results are given for the rare-gas atoms from helium to radon and for lead. The results compare favorably with numerical Dirac-Hartree-Fock solutions.

Electron diffraction and resistivity measurements on the one-dimensional orthorhombic and monoclinic structures of TaS3. comparison with NbSe3

Abstract: Electron diffraction patterns are obtained of the orthorhombic and monoclinic structures of TaS3. For the orthorhombic structure one set of superlattice spots is observed at (l ± 0.5) a*, (m ± ± 0.125) b*, (n ± 0.25) c* below 210 K. For the monoclinic structure two sets of superlattice spots are observed, the first one at la*, (m ± 0.253) b*, nc* below 240 K, the second one at (l ± 0.5) a*, (m ± 0.245) b*, (n ± 0.5) c* below 160 K. Diffuse scattering lines are present for the two structures. Resistivity measurements are performed on crystals with the two structures, which show strong increase of the resistivity indicating metal-semiconducting transitions at the same temperatures where the superlattice spots appear. These transitions are interpreted as successive Peierls transitions on the different types of chains of TaS3. Also electron diffraction patterns are shown of NbSe3 at very low temperatures where the two charge density waves that occur at 145 and 59 K are formed. A comparison is given between TaS3 and NbSe3. Nous avons observe, par microdiffraction electronique, les structures orthorhombique et monoclinique de TaS3. Dans le cas de la structure orthorhombique on a pu obtenir un systeme de taches de surstructure definies par (l ± 0,5) a*, (m ± 0,125) b*, (n ± 0,25) c* a des temperatures inferieures a 210 K. Dans la structure monoclinique deux systemes de taches de surstructure ont ete mis en evidence, l'un apparaǐt au-dessous de 240 K et donne des taches telles que la*, (m ± 0,253) b*, nc* tandis que l'autre, visible au-dessous de 160 K, correspond a des taches de coordonnees (l ± 0,5) a*, (m ± 0,245) b*, (n ± 0,5) c*. Des lignes diffuses ont egalement ete observees pour les deux structures. Les mesures de resistivite effectuees pour ces structures montrent une forte augmentation de la resistivite quand la temperature decroǐt au passage a la transition metal-semiconducteur ou apparaissent les taches de surstructure. L'interpretation de ces transitions peut se comprendre comme des transitions de Peierls successives relatives a differentes chaines dans TaS3. Les diagrammes de microdiffraction electronique obtenus sur NbSe3 a basse temperature montrent egalement les deux effets des ondes de densite de charge qui apparaissent a 145 K et a 59 K. Nous comparons les resultats obtenus sur TaS3 et NbSe3.

An Outline of Fuzzy or Possibilistic Models for Queuing Systems

Abstract: This short note is an exploratory paper where the difference of nature between probabilistic knowledge and possibilistic knowledge is emphasized in the framework of queuing problems. While the arrival have usually to be modelled by a stochastic process (provided that its correct identification is possible), a queuing system may also exhibit another kind of uncertainty regarding the service time or the service rule which are not always precisely known or defined. Fuzziness, rather than randomness corresponds to the deep nature of this uncertainty. Thus, it is dealt with fuzzy service time and fuzzy service rule in a queuing problem. Hints for solutions are given in various situations. Moreover, an entirely possibilistic model is discussed.

Multiple transitions in isotactic polypropylene around and above the glass transition

Abstract: Gas chromatography, thermal expansion, dynamic mechanical relaxation and thermally stimulated current measurements were used to study multiple transitions in isotactic polypropylene. The crystalline phase relaxation Tαc was decomposed into two components, Tαc1 and Tαc1, in order of decreasing temperature. The activation energy of the Tαc mode was found to be lower than that of the relaxation observed around the glass transition temperature. Thermally stimulated current (TSC) measurements revealed the existence of an apparent double liquid-liquid transition at 39°C and 68 °C in undrawn polypropylene and at 28°C and 55°C in drawn polypropylene. These TSC peaks correspond to a relaxation time following a Vogel equation whose critical temperatures let us predict an apparent double glass transition in polypropylene.

Electronic Excitations in Some Transition Metals and Their Oxides. Characteristic Energy Loss Measurements up to 50 eV

Abstract: The characteristic energy losses suffered by a 20 keV electron beam through thin films of some transition metals (Sc, Y, Zr, Hf) and of their oxides are measured using a magnetic spectrograph up to 50 eV. The energy loss function — Im 1/e and the complex dielectric constant are calculated. It is shown that the electron excitation spectra of metals contain two main contributions in this energy range: one due to collective excitations of the conduction electrons, the other to the excitation of inner p-electrons. In the case of oxides the spectra display three strong structures: there are probably two collective excitations of valence electrons followed by the excitation of inner p-electrons of the metal. Les pertes caracteristiques d'energie subies par un faisceau d'electrons de 20 keV a la traversee de films minces de quelques metaux de transitions places en debut de serie (Sc, Y, Zr, Hf) et de leurs oxydes ont ete mesurees avec un spectrographe magnetique jusqu'a 50 eV. La fonction —Im 1/e et la constante dielectrique complexe sont calculees. On montre que le spectre des excitations electroniques des metaux contient deux contributions principales dans le domaine d'energie considere: l'une due a l'excitation collective du gaz d'electrons de conduction, l'autre a l'excitation des electrons p. Dans le cas des oxydes, les spectres mettent en evidence trois structures importantes: deux excitations collectives des electrons de valence et l'excitation des electrons p du metal.

Estimation de la regression par la methode des k points les plus proches avec noyau : quelques propriétés de convergence ponctuelle

Abstract: Soient X un vecteur aleatoire de ℝp, Y une v.a.r., (Xi,Yi), i=1,n, une suite de n realisations independantes du couple (X,Y) et x un point fixe dans ℝp. On considere l’estimateur de E(Y/X=x) defini comme la moyenne des Yi, i=1,n, telles que Xi appartienne a l’ensemble des kn points Xj, j=1,n, les plus proches de x au sens de la distance euclidienne de ℝp, (kn)ℕ etant une suite entiere.

Monitoring of the Atmospheric Stability above an Urban and Suburban Site Using Sodar and Radon Measurements.

Abstract: This study presents a method of obtaining the quantitative intensity of vertical diffusion during periods of atmospheric stability. This method associates the continuous measurement of radon concentration at ground level and the use of a monostatic sodar. The value of “equivalent mixing height” he is calculated using the radon variation which can be related to the global exchange coefficient of the inversion layer. The sodar detects the thickness of the nocturnal inversion layer. Both systems operated simultaneously over several months at two sites (urban and suburban). In most cases the nocturnal layer was indicated both by sodar echoes and by a large decrease of the he value. In other cases the use of sodar alone can lead to a lack of detection of stable periods which, nevertheless, are shown clearly by radon. The comparison of measurement at two sites shows a modification of nocturnal stability above the urban site. The equivalent exchange coefficients are ∼0.3 m2 s−1 (at the urban site) and 0...

La fonction inhibitrice des reines de la fourmiPlagiolepis pygmaea Latr.: Role des pheromones

Abstract: Le pouvoir inhibiteur des reines dePlagiolepis pygmaea s'exerce dans deux voies: - la ponte des ouvrieres est empechee; - la differenciation des larves sexuees femelles est inhibee.

On identifiability of parameters in a class of parabolic distributed systems

Abstract: In this paper we obtain a number of identifiability results for a particular class of parabolic distributed parameter systems. The parameters are assumed to be constant and the difficulties are due principally to the presence of the unknown parameters in the eigenfunctions. A lemma is established which permits us to obtain a number of identifiability results under certain assumptions on the boundary, conditions.

Binding of CRP to DNA-dependent RNA polymerase from E. coli: modulation by cAMP of the interactions with free and DNA-bound holo and core enzyme.

Abstract: The regulatory protein CRP (or CAP) fromE. coli is shown to display two distinct patterns of binding interactions with DNA-dependent RNA polymerase. The free core enzyme, and both the core and the holo polymerase when bound to single-stranded DNA, can bind CRP in a cAMP-independent association reaction. Instead, the binding of CRP to free holoenzyme and to holo or core polymerase bound to native DNA was undetectable in the absence of cAMP. The specific ligand of CRP (cAMP) strengthens distinctively this class of interactions. In no case could any release of σ-factor be demonstrated. Estimates of the dissociation constants were obtained for the various binding reactions which were investigated under quasi-physiological ionic conditions. These, together with the known values of thein vivo concentrations of CRP and RNA polymerase, suggest that the interactions described may have a functional significance.

Ecdysteroid titre and caste determination in the ant,Pheidole pallidula (Nyl.) (Hymenoptera: Formicidae)

Abstract: In the antPheidole pallidula, ecdysteroid level is higher in worker-biased eggs than queen-biased eggs. Moreover queens laying worker-biased eggs exhibit a higher ecdysteroid level than queens laying queen-biased eggs.

Operations Research with Fuzzy Data

Abstract: Often in real-case problems, all the numerical data are not precisely known and the nature of the uncertainty is possibilistic14 rather than probabilistic. Then, the data are said fuzzy. The adaptation of an ordinary algorithm (appropriate to precise data) to fuzzy data is not always straightforward. Theoretically, the direct application of the extension principle of fuzzy set theory solves this problem, but not generally in a computationally attractive manner. Practically, the case of forecasting algorithms, where the result may be fuzzy is different from this of decision algorithms where the result must be precise. For an illustrative purpose, we successively deal with the PERT, assignment, travelling salesman and transportation problems. Using results about the algebraic manipulation of fuzzy numbers, computationally attractive algorithms for fuzzy data are provided.

The laying of caste-predetermined eggs by the ant Pheidole pallidula (Nyl.) (Hymenoptera-Formicidae)

Abstract: Pheidole pallidula ne possede pas de couvain dormant. Les sexues sont issus du premier couvain printanier: dans les 3/4 des societes, a la sortie de l'hibernation, les reines pondent des œufs preorientes qui evolueront en larves de sexues. Plus tard les œufs sont tous a preorientation ouvriere. Au laboratoire a 26o, les reines pondent des œufs a preorientation sexuee pendant seulement 15 jours apres la sortie d'hibernation. Passe ce delai les œufs ne donneront plus que des ouvrieres. Ces deux premieres semaines de ponte correspondent a la periode de ponte la plus intense et a celle ou les œufs sont les plus gros. La ponte des œufs a preorientation sexuee ne depend: Si la reine est retiree apres la ponte des premiers œufs, les ouvrieres meme en nombre reduit, elevent les larves sexuees jusqu'a la nymphe reine ou mâle dans pres de la moitie des cas. Si la reine est maintenue, les chances de succes sont presque nulles dans le cas de societes a faible effectif. Au-dessus de 1400 ouvrieres par contre, la reine n'est plus un obstacle: le ratio nombre d'ouvrieres/nombre de larve doit etre determinant. Pheidole pallidula presente ainsi un double determinisme des castes: au determinisme autogenique qui separe les castes royales et ouvrieres succede un determinisme trophogenique larvaire qui est a l'origine des soldats.

Radiation damage problems in electron microscopy

Abstract: A brief outline is given of the processes of knock-on damage and electronic damage in electron microscopy together with estimates of the damage probabilities. Of the various remedial techniques under investigation, that of low temperature observation seems generally the most promising. Attention is drawn to some of the outstanding problems particularly concerning the nature and behaviour of electronic excitations in molecular crystals and their role in the damage mechanism.