bluuebunny/crossref_metadata_2025 huggingface dataset:
Jean-Jacques Berzélius (1779-1848), associé de l'Académie Royale de Belgique : quelques réflexions à propos de son bicentenaire
Authors: Bruylants Albert
Published: June 2020

Joens-Jacob Berzelius, the famous swedish chemist, was born on the 20th of August 1779. He studied at Upsala, where he was granted the doctorate in medecine (1804). Short after that, he was appointed to a chair at the university of Stockholm and dedicated himself, almost entirely, to chemistry. His course, illustrated by demonstrative experiments, became reknown troughout the chemical world.

He was made a member of the Royal Academy of Sciences (1808) served as its president (1810), and was elected standing secretary (1818).

Berzelius was an expert analyst ; he performed many quantative analysis. He was the discoverer of several new elements. The atomic weights, he had determined, appeared in his table (1818), with the new chemical symbols he had devised ; his electro-dualistic theory based on experiments, he had carried out with a large Volta pile, his new classification of minerals, based upon instead of physical properties on their chemical composition, he had established himself experimentaly, made him as the dominant figure of his time, despite the fact he was geographically distant from the principal chemical centers.

Several belgians were among Berzelius's numerous pupils, colleagues and friends.

B. Valerius translated his text-book from the german edition into the french (Brussels, 1838-1844). J. B. Van Mons, the father of the belgian chemists, introduced him as a foreign member of our Royal Academy (1817).

P. Louyet, who was a young and trusty follower, wrote his biographical sketch (1849).

M. Martens, as being an electro-chemist, was very familiar with the Swedish theory in this field, brought himself a valuable contribution to it and was also involved in the controversy, J. B. Dumas versus J. J. Berzelius, about the theory of substitution processes (1840).

Last but not least, J. J. Stas and L. Melsens, two young coworkers of J. B. Dumas took an active part in this controversy, one of the most violent in the course of XIX century.
L'effet inhibiteur de l'oxygène sur le développement du cancer pulmonaire chez la souris
Authors: Duchesne Jules
Published: June 2020

The aim of this Note is to confirm the mechanism of the biochemical process governing the maligment tumours described in the author's earlier work.

The method implies the use of oxygen under high pressure which, as it has in these conditions the peculiar property to destroy antioxydant compounds, leads, as expected, to a significant decrease in the number and size of induced lung metastases.

These results consequently open up important new perspectives in the field of the therapeutic for cancer.
Systèmes hypercycliques à cercles générateurs tangents
Authors: Backès Fernand
Published: June 2020

Il s'agit de systèmes cycliques de Ribaucour dont le cercle générateur jouit en outre de la propriété en vertu de laquelle il existe une sphère (et par suite une infinité), passant par ce cercle et dont les points caractéristiques sont concycliques avec les foyers dudit cercle.
Sur un théorème de Vitali-de Possel
Authors: Lomami Okito
Published: June 2020

Le but essentiel de cette note est d'établir dans un cadre plus général et sous des conditions plus larges un théorème de dérivation de R. de Possel pour les bases de dérivation fonctionnelle de Vitali fortes.

Soient D une base de dérivation fonctionnelle de Vitali forte dans un espace mesuré (E, ℳ, φ) et ψ une mesure positive sur ℳφ- dérivable. En désignant par Dψ et Dψ respectivement la D- dérivée inférieure et la D- dérivée supérieure de ψ, et par ƒ une φ- dérivée de ψ, nous démontrons que, sous certaines conditions, on a localement presque partout Dψ > ƒ et ƒ > Dψ. Le théorème en résulte puisque Dψ < Dψ
Influence de l'introduction d'un terme d'amortissement à argument retardé dans l'équation de Van der Pol
Authors: Bastin Henri , Delchambre Monique
Published: June 2020

On étudie un système de Van der Pol à argument retardé et on montre que l'allure des courbes de réponse dans le plan d'Andronov dépend fortement du retard.

De plus, les zones de stabilité sont considérablement modifiées par rapport au système non retardé.
Bouncing Quantum Cosmologies
Authors: Demaret Jacques
Published: June 2020

Spatially homogeneous cosmological models of Bianchi types I, V and IX (as well as their isotropic counterparts : the Einstein-de Sitter, open and closed Friedmann-Robertson-Walker (FRW) models, respectively), filled with a perfect fluid with an equation of state of the type p = (γ - 1 )ρ (γ = constant comprised between 1 and 2) are quantized in the framework of an ADM-type canonical quantization scheme introduced by Demaret and Moncrief.

This method which generalizes a method due to Lund and originally restricted to space-times filled with a pressureless fluid (p = 0) is based on Schutz's Hamiltonian theory of a relativistic perfect fluid, extending to general relativity Seliger and Whitham's velocity-potential version of classical hydrodynamics. It leads to a Schrödinger-like equation for the wave function of the universe, which admits a true physical interpretation in terms of probability as in orthodox quantum mechanics.

Contrary to Misner's early results based on a different quantization scheme, our method leads to the conclusion that, apart from a set of measure zero of models comprising FRW models as well as Bianchi models filled with a fluid with a stiff equation of state (p = ρ), all Bianchi models are non-singular, in the sense that the quantum wave function becomes zero at the classical singularity. Such a non-singular model can be interpreted as a contracting universe bouncing into an expanding universe, due to quantum gravitational fluctuations. A similar conclusion of non-singularity of a quantum Bianchi I universe has recently been obtained by Narlikar by using a different method of quantization, i.e. the method of path integration.
Study of surface tension effects in thermal convection by variational methods
Authors: Lebon Georgy , Perez-Garcia C.
Published: June 2020

Variational formulations are proposed for the study of the hydrodynamic stability of an infinite fluid layer at rest heated from below. The role of a temperature dependent surface tension is more specifically emphasized. Both perturbations of small and finite amplitudes are considered : the former are investigated by means of the classical normal mode analysis while the latter are treated in the frame of Serrin-Joseph energy method. Both approaches are expressed in terms of variational principles which serve as starting points of the numerical procedure. By using very simple trial functions, namely a set of four Tchebyshev polynomes, and invoking Rayleigh-Ritz's method, approximate solutions are obtained.
Remarques sur divers problèmes de la mécanique statistique des systèmes classiques avec des interactions dépendant des vitesses. — Cas des évolutions non liouvilliennes
Authors: Maga-Mondésir Émire
Published: June 2020

Les problèmes techniques dûs à l'utilisation d'interactions dépendant des vitesses en mécanique statistique, notamment dans les situations hors d'équilibre, sont ici abordés. L'aspect des forces dérivant d'un potentiel est examiné, ainsi que le cas général où les forces ne dérivent plus d'un potentiel, ce qui conduit à des évolutions non liouvilliennes d'interprétations variées.
Why it is impossible in quantum mechanics to describe two or more separated entities
Authors: Aerts Dirk
Published: June 2020

We prove that a theory that is different from a classical theory and has the property that orthogonal states of a physical system are compatible states (a property called orthomodularity in axiomatics) cannot describe two separated entities. Quantum mechanics has this property and as a consequence it is impossible to describe two separated entities in quantum mechanics. This is essentially due to the fact that quantum mechanics is too specific a theory. We indicate the direction for a generalization where the problem could be solved.
Studies of spinels. (VIII) Synthesis and structural study of new antimonates M5II M3III SbO12 by X-ray diffraction and Mössbauer spectroscopy
Authors: Preudhomme J. , Tarte P. , Kenens R. , Grandjean F. , Gérard A.
Published: June 2020

X-ray and Mössbauer data on spinel antimonates, with formula (MII2MIII3) [MII8MIII2Sb2]O24, with MII = Mg, Zn, Ni and MIII = Fe, Ga are presented.

The cationic orderings and distributions are widely discussed and even if no long-range cationic ordering appears, the Mössbauer data show a short-range one.

Preliminary magnetic results are also obtained.
Thermal and gravitational instability of a model hydrogen plasma
Authors: Manfroid J. , Militello A.
Published: June 2020

We investigate the stability of a dilute hydrogen plasma in mechanical, thermal and ionization equilibrium. We derive sufficient and necessary criteria for instability from a linear analysis.
On the structure of the Group-ring of an elementary abelian group and a Theorem of Brauer and Nesbitt
Authors: Bhattacharya Prabir
Published: June 2020

Let G be an elementary abelian p-group generated by m elements and let F be a finite field of characteristic p. We study the structure of the group-ring FG. It is observed that FG is isomorphic to a certain quotient ring of a polynomial ring over F in m indeterminates. In this isomorphic copy, a chain of ideals is defined such that each ideal is left invariant, under the natural action of the group GL(m,p). We study the structure of these ideals and prove some results. The quotient of any two successive elements in this chain of ideals is isomorphic to the ring of homogeneous polynomials in m variables over F of a certain degree. This observation leads us to give an elementary proof of a Theorem of Brauer and Nesbitt (Annals of Math (2) 42 (1941), 556-590) that the ring of homogeneous polynomials over F in m variables of a given degree is irreducible under the natural action of the group GL(m,p).
Télescope et observation du rayonnement cosmique à Lubumbashi
Authors: Dehousse M. E.
Published: June 2020

In this work the cosmic radiation telescope which we have constructed and which is functioning at Lubumbashi is described. Due to its two orientale detectors, it counts high energy particles which go through it, and permits the most energetic radiation to be disclosed. Some of the observation results on the cutting of horizontal and vertical symetrical cosmic rays have been analysed by us, and their great energetic stability is concluded.

A few hypothesis relative to the laws which preside the behaviour of the rays and to the succession of beats in functional and coincidental gauges are put forward. The perturbations created by a magnetic screen are related and valued.
Phénomène de saut dans un oscillateur de Van der Pol du 3e ordre avec retard
Authors: Bastin Henri , Delchambre Monique
Published: June 2020

Ce travail montre que le phénomène de saut bien connu dans un oscillateur de Van der Pol peut se généraliser pour les systèmes à retard bien que l'introduction d'un argument retardé provoque des discontinuités complexes dans les courbes de réponse.
About transverse vortex rings that can be used as elements of turbulence
Authors: Sattar Md. Abdus
Published: June 2020

Vorticity and velocity distributions of several vortex rings that can principally be used as elements of turbulence are obtained and compared. The comparison emphasis is mainly given to the viscous type of D- and Q-vorticies obtained by Lee and vortex obtained by Chou & Huang. Because of the analytical complexity of Chou & Huang vortex a simpler and more compact form of solution for this latter is attained which appears to be the same as the Q-vortex. The analytical considerations compared to the solution of Chou & Huang are shown in Appendix A. The longitudinal and transversal velocity correlations of D-vortex and Q-vortex are also calculated and compared with that of Chou & Huang vortex and also with the experimental results of Batchelor and Townsend.
Ostéologie et position systématique d'Aethalionopsis robustus (Pisces, Teleostei) du Crétacé inférieur de Bernissart (Belgique) considérations sur les affinités des Gonorhynchiformes
Authors: Taverne Louis
Published: June 2020

The author describes the skeleton of Aethalionopsis robustus and proves on osteological basis that Aethalionopsis is a primitive Chanidae and not an Elopidae or a Leptolepidae as previously thought. The relationships of the Gonorhynchiformes are also discussed.
Microprocessor based data acquisition and control system for a balloon borne quadrupole mass spectrometer
Authors: Nevejans D. , Frederick P. , Arijs Etienne
Published: June 2020

A microprocessor based data acquisition and control system has been designed and constructed for use in balloon borne quadrupole mass spectrometers. It combines the capabilities of an ion counter/discriminator, a spectrum accumulator, an intelligent mass scan controller, a multiplexed ana¬ log to digital converter, a relay controller, a PCM encoder for serial digital output, multiple analog outputs and an interface to remote control signals. The system has been flown successfully in the stratosphere.
The interpretation of protons and electrons observations from ATS 6 satellite within the frame of Mcllwain's electric field model
Authors: Lemaire Joseph
Published: June 2020

The "E3H" electric field model has been deduced by Mcll-wain from dynamical proton and electron energy spectrograms measured along the geostationary orbit of ATS 5 satellite. It is shown that this empirical model, which has often been regarded with some reticence by a number of theoreticians, fits well with the measurements, also made in the equatorial region of the magnetosphere, onboard another geostationary satellite (ATS 6) during an extended period of time when the geomagnetic activity index ranged be¬ tween 1 and 2. This confirmation validates the E3H model, at least for such extended periods of time when Kp= 1 and 2+.

From the dynamical spectrograms of ATS 6 observed on 19 July 1974, some evidence for patchy or localized injection of a magnetosheath plasma cloud across the late afternoon local time sector of magnetopause has been gained.
Sur les points fixés par les involutions dans un groupe transitif : un cas particulier
Authors: Ronse Christian
Published: June 2020

Étant donné un groupe de permutations transitif G dont les involutions fixent au maximum un nombre ƒ de points (où />1), il a été démontré en [5] que soit le rang 2-sectionnel de G est borné par une fonction en f soit G a un sous-groupe normal N possédant un sous-groupe fortement plongé. Nous étudions ici ce deuxième cas.
Une base sphéroïdale pour les atomes plongés dans un champ magnétique intense
Authors: Mertens Chantal , Demeur Marcel
Published: June 2020

Une base orthogonale est proposée pour construire le spectre des atomes à un et deux électrons plongés dans un champ magnétique très intense. La base est composée de vecteurs jouissant des mêmes symétries que les systèmes étudiés ; elle est de plus optimisée par le biais de paramètres non-linéaires. De petites matrices suffisent à l'obtention d'excellents résultats dans le cas de l'Hydrogène ; dans le cas de l'Hélium les résultats sont bons mais seulement dans une gamme restreinte de champs magnétiques.
Perceptual and cognitive factors in the apparent transparency phenomenon
Authors: Hambrouck Micheline , Thinès Georges
Published: June 2020

Apparenté aux cas de remplissage figurai, le phénomène de transparence apparente se manifeste lorsque, dans certaines conditions spatiotemporelles, un objet est phénoménalement visible lorsqu'il passe derrière un écran opaque de surface homogène sous éclairement achromatique. La faible prégnance du phénomène observée chez les sujets «non avertis » et l'apparente nécessité d'une préparation de nature cognitive ont suscité cette série d'expériences dont l'objet principal est de déterminer l'influence respective de la centration perceptive, de l'information verbale et de la répétition des observations sur la fréquence des réponses mentionnant l'effet. En un premier temps, deux pré-expériences ont permis la mise au point d'une procédure de réponse répondant aux exigences d'une centration perceptive dont toute intervention cognitive de l'expérimentateur est absente. Les trois expériences menées ensuite mettent en évidence le rôle primordial de l'information verbale dans ce type de perception. En outre, l'expérience 3 montre la différence de prégnance entre ce phénomène et un cas de transparence physique comparable, et ce malgré l'intervention du langage dans la deuxième partie de cette expérience. Le manque de prégnance du phénomène est interprété en termes d'attention sélective et d'erreur de codage et de stockage du donné, ceux-ci opérant en faveur de l'effet Tunnel, nettement plus coërcitif et plus proche de l'expérience perceptive habituelle.
Sur le calcul de la torsion dans les barres à section polygonale
Authors: Lefeber Dirk , Janssens Paul
Published: June 2020

The stress-function for the torsion of bars with polygonal section is obtained by an adaptation of the large singular finite element method. The results are compared with those obtained by other techniques. It is also shown how the stresses can be calculated with the proposed method.
Prediction of the effects of surface curvature and rotation in a turbulent boundary layer
Authors: Korttkov N. , Hirsch Charles
Published: June 2020

A method has been developed to predict the effects of the surface curvature and rotation in the turbulent boundary layer. The Cebeci-eddy-viscosity model and Richardson number correction were checked for fourteen tests. The boundary layer equations are solved by the " Box " numerical procedure. The results are presented and compared with experimental data.
An interpretation of d'Inverno algorithm for Petrov classification
Authors: Moussiaux A. , Tombal P.
Published: June 2020

The purpose of this paper is to give an easy interpretation of the d'Inverno and Russel-Clark algorithm for the determination of Petrov type of general relativistic space-times starting from a quartic equation. It is shown that Petrov classification is directly connected to the zeros of the resolvent of a thirth and fourth degree equations. Petrov type may be deduced from the values of the roots of a third or second order equation.
Les niches écologiques des Carabides en milieu forestier I. Composantes spatio-temporelles
Authors: Loreau Michel
Published: June 2020

An overall study of the niches of forest carabid beetles is carried out in a beechwood close to the climax stage in Lembeek (Belgium). A comparison with two other biotopes — a pine plantation and a grassland in process of afforestation — further aims at defining general features of niche organization in forest carabid communities. Four niche components are measured : annual activity cycle, daily activity rhythm, spatial distribution, and diet. This first paper deals with the three temporal and spatial components.

Annual activity cycles are unexpectedly diversified, and thus play an important part in niche différenciation. The well marked succession of activity peaks during the course of the year separates most forest species in time. On the other hand, niche overlap is higher in the «grassland», especially among dominant species, suggesting that time organization is poorly achieved in a successional stage.

Daily activity rhythm constitutes a minor factor in niche differentiation. Most forest carabids are nocturnal ; but a few spring species are day-active.

Spatial distribution of activity does not generally allow a clear-cut niche separation either. When becoming dominant, large forest species tend to reach an homogeneous distribution of activity. In the «grassland» however, distributions are particularly heterogeneus, and point out two distinct faunas typical of different successional stages.
Théorie du champ pictural : Les facteurs spatiaux - L'ensemble du champ
Authors: Guiraud Jean , Lison Pierre
Published: June 2020

Sachant ce que sont les interactions des couleurs et les interactions des luminosités dans l'œuvre picturale, on se propose ici de leur associer les interactions de type spatial, soit celles des facteurs qui régissent la forme et la distribution des plages colorées.

(Ce texte modifie celui qui avait été publié sous ce titre et dans ce Bulletin en 1979).
Sur les groupes d'homotopie
Authors: Mathieu Philippe
Published: June 2020

Dans cette note, nous définissons une structure catégorique généralisant les groupes d'homotopie. Nous en donnons quelques propriétés et nous étudions la suite exacte d'homotopie d'une fibration.
Separation of variables and constants of the motion for the Dirac equation on curved spacetime
Authors: Kamran Niky , McLenaghan Raymond G.
Published: June 2020

It is shown that every spacetime admitting a first-order constant of the motion for the Dirac operator constructed from a rank four Pen-rose-Floyd tensor whose associated Killing tensor has no constant eigenvalue admits a separable coordinate system and spin frame for the Dirac equation. The rôle played by first-order constants of the motion in the separability of the Dirac equation is further illustrated through the study of a spacetime admitting separable massive Hamilton-Jacobi and Klein-Gordon equations and a first-order commuting operator for the Dirac operator, in which the Dirac equation is not separable unless the metric is appropriately restricted. It is shown that this commuting operator underlies the decoupling of the Dirac equation into equations separated in pairs of variables.
Acetonitrile in the earth's atmosphere : An upper limit deduced from infrared solar spectra
Authors: Muller Christian
Published: June 2020

Abstract. — An upper limit to the atmospheric acetonitrile mixing ratio of 3.2 X 10-1 is deduced from the high resolution Kitt Peak infrared atlas of the solar spectrum. The survey of the spectral region of CH3CN main absorption shows only stratospheric ozone lines and one water vapor line and does not permit any positive identification of acetonitrile.
À propos de l'effet Brody
Authors: Troquet J.
Published: June 2020

In order to recognize what comes from anyone, we have situated the Brody effect into its electrodynamical frame, and we have underlined some important potentialities that we consider as neglected : that is appendix III in the opus princeps.

Such a tool is powerful in working out the multilayer problem but, without illustration, its compactness is not attractive. We also present an other formulation from which the Brody effect may be more clearly defined.
La détection chimique de l'odeur des prédateurs chez Astyanax mexicanus (formes cavernicole et épigée)
Authors: Thinès Georges , Fraipont M. de
Published: June 2020

In the present study, the locomotor responses of the epigean and cavernicolous forms of the fish Astyanax mexicanus are compared, when presented with water samples from an aquarium containing an isolated predator or a group of predators of the species Cichlasoma fenestratum. Results show : (1) that epigean individuals tend to avoid the zone containing chemical informations of predators ; (2) that cavernicolous individuals orient themselves preferentially towards the chemical traces of predators. The ethological implications of these phenomena are discussed.
Mise en évidence d'un milieu à «double porosité » par un essai de pompage
Authors: Delmer André , Leclercq V. , Rorive Alain
Published: June 2020

Applying the pseudovariational method of M. A. Biot to an axisymmetrical flow in a body characterized by 'dubbel porosity' gives, in the case of a pumping with constant level, results that are in good accordance with the discharge curve observed in the geothermal well drilled in the region of Möns.
Automatic continuity of certain linear isomorphisms
Authors: Narici Lawrence , Beckenstein Edward
Published: June 2020

Let S and T be compact, 0-dimensional, Hausdorff spaces and let C(S) and C(T) denote the sup-normed Banach spaces of continuous maps on S. and T, respectively, into a complete nonarchimedean valued field F. If F were the reals, then S and T would be homeomorphic if and only if C(S) and C(T) were isometrically isomorphic ; moreover, the isometric isomorphism A : C(T) C(S) must be of the following type : For each x in C(T) and any s in S, Ax(s) = a(s)x(h(s)) for some homeomorphism A of S onto T and some nonva-nishing continuous map a defined on S. As we have shown earlier, there are other kinds of isometric isomorphisms when dealing with F-valued functions. In this paper we focus attention on "separating" linear maps A, maps with the property that the cozero sets of Ax and Ay must be disjoint if the cozero sets of x and y are. We develop criteria for separating maps A to be continuous, for S and T to be homeomorphic, and for such maps to be of the "change of variables" type of the Stone-Banach theorem.
Towards intelligent weapons
Authors: Jaumotte André Louis
Published: June 2020

Au moment où la réduction de la menace force à repenser la stratégie militaire et à revoir les priorités de la défense, nous sommes à la veille d'un saut qualitatif sensible conduisant à une panoplie d'armes et de systèmes d'armes intelligents.

Des capteurs performants fournissent les informations de base en filtrant l'ess¬ entiel de l'accessoire.

Les principaux senseurs sont les sonars, les radars et les caméras infrarouges. Pour chacun d'eux, des progrès importants viennent d'être accomplis. Sonar à basse fréquence. Radar à commande de phase. Caméras infrarouges avec semi-conducteurs refroidis à une température cryogénique.

Lorsque les opérations de détection, fusion et identification sont accomplies, l'arme dispose d'une représentation objective de son environnement perçu. Toutes les techniques de l'intelligence artificielle sont alors utilisées pour en déduire une conduite à tenir pour effectuer la mission.

Ces armes intelligentes sont très en avance sur la stratégie militaire faite par des hommes non formés à ces armes intelligentes.
Résolution générale des équations différentielles relatives à la cosmologie
Authors: Teyssières Michel
Published: June 2020

The problem of relativistic models of the universe is based on two differential equations, called cosmological equations.

In 1922, Alexander Friedmann gave his well known solution in a particular case. Other solutions are calculated here and an interpretation of Friedmann's solution is given.
On the measure of non-compactness for a class of singular integral operators
Authors: Nugari Rita
Published: June 2020

We study a linear integral operator over the interval (— ∞, ∞). The operator is well defined and continuous from L1 (ℝ) into L2 (ℝ) but fails to be compact. Bounds are given on its measure of noncompactness.

AMS Subject Classification -45P05 -47G05.
A Moyal type product on Hermitian symmetric spaces
Authors: Arnal Daniel , Cahen Michel , Gutt Simone , Zahir Hamid
Published: June 2020

We suggest a construction of a Moyal type * product on Hermitian symmetric spaces ; this construction is motivated by what happens for coadjoint orbits of the Heisenberg group.
Mécanismes réactionnels en électrochimie et structures dissipatives au sens de Prigogine
Authors: Brenet Jean
Published: June 2020

En considérant le cas où une réaction électrochimique correspond à la loi de Tafel, on envisage que l'on n'est plus dans le domaine de la thermodynamique linéaire et qu'il peut apparaître des structures dissipatives au sens de Prigogine.
Mathematical Foundation of a Non-linear Treshold Logic. A new Paradigm for the Technology of Neural Machines
Authors: Dubois Daniel M. , Resconi Germano
Published: June 2020

This paper deals with the foundation of a Non-linear Threshold Logic as a significative extension of the classical Threshold Logic initiated by McCulloch and Pitts 50 years ago. The mathematical theory of this new logic is based on Heaviside a Non-linear argument of the Function. The determination of the parameters is made by an algebraic learning. For the first time, we introduced the so-called Heaviside Fixed Function.

The models of the Dubois' Fractal Neural Network and the Fukushima et al Neocognitron give the original framework of the new Non-linear Threshold Logic.

The Threshold Logic, using linear argument of the Heaviside function, is not capable of resolving all Boolean functions with only one neuron.

It is demonstrated that our Non-linear Threshold Logic resolved all the Boolean functions with one single neuron for any number of inputs, ie even the XOR problem.

This is a good test for our method. Moreover it is shown that the very difficult Parity problem has also a very elegant solution for obtaining the parity of any Boolean patterns from one single neuron with any number of inputs.

In the technology of neural networks, the back-propagation methods are based on hidden neurons to resolve the Boolean functions. There are some difficulties to obtain the global minimum as the number of neurons increases and the combinatorial explosion gives many problems for practical applications.

The Non-linear Threshold Logic will permit to diminish a great quantity of neurons in the neural networks with the back-propagation.

The possibilities of bigger practical applications are so given by this Non-linear Threshold Logic in the technology of neural machines due to the diminution of the necessary number of neurons and so to avoid some combinatorial explosion problems. Turbo Brain 1.0, a package for Personal Computers, has been developped from this Non-linear Threshold Logic with a Symbolic software.
Motion of charged particles in a stochastic magnetic field with a collisional noise
Authors: Wang Haida , Balescu Radu
Published: June 2020

The diffusion of charged particles in a gaussian stochastic magnetic field characterized by finite correlation lengths λI and λ[formula] and gaussian coloured collisions with a finite correlation time τc is studied through the method of expansion with respect to a parameter ε which is introduced to denote the order of smallness. The mean square displacement in the perpendicular direction, Γ(t), is derived to the order of ε2. Several limiting cases are discussed and

shown to recover the previous results. To the order of α5 [formula], the

result is the same as that of Balescu, Misguich and Nakach, which was obtained after " Corrsin approximation It proves that the " =Corrsin approximation" is also reasonable in the short time regime.
Étude qualitative d'une équation différentielle, décrivant un processus thermique transitoire
Authors: Aprahamian Bohos , Kontrov Sava , Terzian Stépan , Aprahamian Méliné
Published: June 2020

L'objet de l'article est l'étude qualitative d'une équation différentielle du deuxième ordre, décrivant le processus thermique transitoire d'un grand nombre d'appareils électrothermiques qui possèdent un schéma substituant thermique contenant une source de flux thermique, deux capacités et trois résistances thermiques. Les zones des solutions stables autour des points fixes de l'équation sont trouvées. L'application des résultats obtenus est illustrée par un exemple concernant l'utilisation d'un nouvel élément de chauffage, qui a une caractéristique de relais de la résistance spécifique électrique dépendant de la température.

Vu les résultats obtenus, des études semblables sont à effectuer pour tout autre élément de chauffage.
An Existence Theorem of Solutions of Semilinear Equations in Reflexive Banach Spaces and Its Applications
Authors: Tang Chun-Lei
Published: June 2020

In this paper, we first obtain an existence theorem of solutions of semilinear equations in reflexive Banach spaces with the dual least action principle and the perturbation method, then apply it to Hamiltonian systems and second order systems.

Key works : subdifferential, generalized gradient, Fenchel transform, minimum, weakly lower semicontinuous.
A simple hand verification of the Bieberbach conjecture for 2 ≦ n ≦ 7
Authors: Todorov Pavel G.
Published: June 2020

In comparison with the de Branges-Gautschi computer verification of the Bieberbach conjecture for 2 ≦ n ≦ 30, we give a simple hand verification of this conjecture at least for the first values of n, namely for 2 ≦ n ≦ 7, etc.
Problèmes aux limites pour certaines équations de type non classique du troisième ordre
Authors: Bouziani Abdelfatah
Published: June 2020

Dans cet article, on étudie un problème aux limites pour certaines équations de type non-classique du troisième ordre pour une structure pluri-dimensionnelle dans un domaine quelconque. On montre l'existence et l'unicité de la solution au sens faible en utilisant une méthode d'analyse fonctionnelle sur la base des inégalités de l'énergie et sur la densité de l'ensemble des valeurs de l'opérateur engendré par le problème étudié.
Evolution récente des méthodes d'analyse des images satellitaires par télédétection numérique
Authors: Wilmet J.
Published: June 2020

This article is an attempt to sum up the evolution of remote sensing image interpretation methods during the last years. The land cover identification has made a very significant progress in different ways. The enhancement of the spectral methods proceeds from the adaptation to remote sensed data from already known techniques such as fuzzy logics as well as from new developments such as multitemporal vectors. Considerable improvements occured also among textural methods, such as conditional filtering, backpropagation neural networks or mathematical morphology.

However, the interpretation of land use patterns remains an open problem. Its comparative backwardness, as far as digital methods are considered, arises from a lack of conceptual analysis of the image structure which remains always a prevalent domain of thematic studies.
Analyse et synthèse de systèmes à dynamique chaotique en terme de circuits de rétroaction (feedback)
Authors: Thomas René
Published: June 2020

Studies on the biological role of feedback circuits were initially centered on systems with stepwise or steep sigmoidal interactions. It turned out recently that reasoning in terms of feedback circuits (rather than of individual interactions) can be used in a more general context, and, in particular, help understanding the behaviour of weakly nonlinear sys¬ tems «à la Rössler » (with a single nonlinear term) known to generate deterministic chaos. A variety of three-and four-dimensional differential systems displaying a chaotic dynamics have been built. The respective roles of the logical structure (= the network of feedback circuits) and of the nonlinearities — both essential — are discussed.
La publication électronique
Authors: Heck André
Published: June 2020

The current dramatic evolution in information technology is bringing major modifications in the way scientists work and communicate. The concept of electronic information handling -and thus of electronic publishing -encompasses the diverse types of information, the different media, as well as the various communication methodologies and technologies. The structure itself of information has become different by the introduction ofhypertextual links. Fluid information is becoming a common concept. While publication is considered here as a public announcement (no implicit assumption being made as to the medium used), it is obvious that electronic publishing will have to diverge from an electronic version of contributions on paper and will become part of a more general diversified publishing policy. The procedures for validating published material and for evaluating scientific activities will have to be adjusted too. Provision of electronic refereed informa¬ tion independently from commercial publishers is now feasible and even maybe highly recommended in view of strict copyright policies tentatively applied by some publishers to the electronic material. In other terms, scientists and scientific institutions have now the possibility to run an efficient information server with validated (refereed) material without the help of a commercial publisher.
L'efficacité des mathématiques est-elle déraisonnable
Authors: Lambert Dominique
Published: June 2020

The aim of this paper is to analyse the problem of the unreasonable effectiveness of mathematics in natural sciences. We try to identify the possible roots of the problem. We study the limits of its classical solutions from Plato to Piaget , taking into account the features of the very recent interactions between physics and mathematics. Finally we give our own hypothesis based on a comparison between the constitution of a percept and the process of generating deep mathematics.
A constructive method in degenerate perturbation calculus. I. The general formalism
Authors: George Claude D.
Published: June 2020

The results of degenerate perturbation calculus may be recovered using a procedure inspired by the methods used by the Brussels group in statistical mechanics.
A Constructive Method in Degenerate Perturbation calculus. II a. Two Levels Model System
Authors: Georges Claude D.
Published: June 2020

The general perturbative procedure proposed for dealing with degenerate systems is applied to the simple example of a two levels system with degeneracies.
A propos de la naissance de la relativité restreinte. Une suggestion concernant la «troisième hypothèse» de H. Poincaré
Authors: Reignier Jean
Published: June 2020

In several presentations of special relativity (the new mechanics, as he said), Henri Poincaré spoke of the Lorentz contraction as an essential hypothesis in order to obtain the Lorentz transformation. However, Einstein's proof of the Lorentz transformation not only doesn't require this hypothesis, but even finds the contraction as a result. This attitude of Poincaré has been severely criticised by several authors. We show that Poincaré's presentation was originally right. As a consequence, it becomes understandable from a historical and pedagogical point of view.
Potential Scattering in Single Subdynamics
Authors: De Haan Michel , George Claude D.
Published: June 2020

The authors have presented [1] a subdynamics theory in which quantities characteristic of irreversible behaviour - such as that of a collision process - appear in the generator of kinetic evolution. This theory is applied to the simple case of potential scattering. The original dynamics is first widened after incoming, outgoing and intermediate degrees of freedom are distinguished. An extended concept of vacuum state is introduced by reference to the observational situation of interest. The redundant degrees of freedom are then constrained by the requirement that the physi¬ cal evolution takes place entirely in the subdynamics associated with that vacuum. The relationship with previous treatments of the same system is analysed in some detail.

PACS numbers : 05.30 ; 02.90 ; 11.20.
Choc de cultures : l'université et l'entreprise. Les «spin-offs» universitaires
Authors: Jaumotte André Louis
Published: June 2020

Une «spin-offs» universitaire est une entreprise constituée au départ de l'Université et de membres de la communauté universitaire pour exploiter commercialement des connaissances ou des résultats de recherches issus de l'Université.

Culture universitaire et culture d'entreprise n'ont pas le même objectif. Pour l'Université, le but est l'enseignement, la recherche et le service à la communauté ; l'entreprise vise à créer de la valeur économique. Les deux cultures sont complémentaires et elles étaient quasi sans recouvrement.

Les «spin-offs» universitaires changent cette vision en liant l'Université à la création de valeur économique.

Après un panorama des «spin-offs» universitaires (au 31 janvier 1999), on en fait l'analyse au point de vue des faillites, du chiffre d'affaires, de la création d'emplois, de la valeur ajoutée et de l'autonomie financière.

On met en évidence les phases successives allant de l'idée à sa commercialisation par «spin-offs».

On observe les bonnes pratiques quant à l'évaluation d'un projet, au rôle des incubateurs, des centres d'entrepreunariat, aux partenaires financiers.

En conclusion, trois éléments ont modifié le paysage de la création d'entreprises en Europe : le développement de l'Union européenne, l'évolution du capitalisme et le développement des réseaux.

Une quatrième mission s'ajoute ainsi aux trois missions traditionnelles de l'Université, la valorisation commerciale de sa recherche. Les Universités belges s'y sont engagées à des degrés variables.
Incinérateurs, crise dioxine, et risques sanitaires pour la population belge
Authors: Bernard Alfred , Depauw Edwin , Fierens Sébastien , Mairesse Hélène , Hermans Cédric , Broeckaert Fabrice , Focant Jean-François
Published: June 2020

Incinerators, dioxin crisis and health risks for the general population in Belgium.

Bernard A., Fierens S., Mairesse H., C. Hermans, F. Broeckaert, J.-F. Focant, E. Depauw.

Since a few years, there is some concern in Belgium about the potential health risks of dioxins emitted by municipal solid waste incinerators (MSWI) and more recently by the dioxins which were introduced in the food chain during the Belgian PCB incident. This communication reports studies which have been recently carried out to assess the possible health impact of dioxins in these two sit¬ uations. Dioxins (PCDDIFs ) were determined in the blood of 85 subjects living around two MSWI, one localized in an industrial area and the other in a rural area. By comparison with an age-matched control group of 27 subjects living in an unpolluted area, an increase of dioxin body burden (36,7 vs 24,3 pg TEQlg blood fat, 34 % on average) was found only in the vicinity of the MSWI in the rural area, most likely because of a higher consumption of locally produced foods around this incinerator. However, despite this increase, all subjects had dioxin levels still in the range of values reported in unpolluted areas in Europe. As to the dioxin crisis, the contamination was too limited in time and in the food chain to have caused adverse health effects in the general popula¬ tion of Belgium even if most contaminated foods (e.g. chicken meat) had dioxin levels more than 100 times above tolerance levels. Indeed, a doubling of the PCB and dioxin burden of the young adult population would have required the consumption of respectively 10 and 20 highly contaminated meals. In view of the very limited proportion of the food chain affected by the incident (less than 2% of poultry farms and of 0.1% of all farms in Bel¬ gium), such an extreme scenario was quite improbable at the pop¬ ulation level. It was conceivable only in farmers who could have consumed their own products. But even for these farmers, this would mean that their PCB and dioxin body burden would have been increased at levels of the 80s or of subjects regularly eating contaminated seafood.
Polarization and deformation quantization
Authors: Dahmene Najla
Published: June 2020

We describe a construction of a star-product on a quantizable symplectic manifold (M, ധ) using a complex polarization F on M. In an effort to generalize this deformation method, we introduce the concept of a complex polarization on a regular Poisson manifold (M, Δ) which can be used to produce a tangential star-product on M.
Sur les traces d'Eugène Catalan
Authors: Jongmans François
Published: June 2020

The French mathematician Eugène Catalan (Bruges 1814 -Liège 1894) is here described as a "pen-pusher" in a non-pejorative sense : a man who wrote much and well about very different topics. His youth is known thanks to a late publication by himself of Literary and political crumbs, containing in particular early letters sent by him to his relatives in Flanders. The first (disastrous) stage of his professorial career, a bit mixed with his activity as a republican rioter, was interrupted in 1852, when he refused the oath of fidelity to a pres¬ ident eager to become an emperor. But his numerous pedagogical books helped him become a popular professor in private secondary schools. His following opus was more secret : an unpublished Journal d'un bourgeois de Paris (1858-1862), recording the dreary life of a republican scientist under Napoleon III. When he obtained in 1865 a professorship at the Liège University, and immediately afterwards an associate membership of the Belgian Academy, his increasing scientific production was published chiefly by this Academy, and completed by quite a lot of various reports. As for his correspondence, hundreds of letters received by him are still available in Liège, but almost all his own messages, equally numerous, are lost, with the notable exception of the "crumbs" and more than fifty letters sent to his favourite pupil Ernesto Cesàro. Among other achievements, let us mention his contribution to the Grand dictionnaire universel du 19e siècle, edited by Pierre Larousse. A true recognition of his merits in France was, at best, infinitesimal : a poor job (two hours per week) proposed in 1864 by Napoleon III, a tentative visit to his home in Liège by the past emperor in 1871, and a modest cross of the Légion d'honneur offered by the republican government in 1887.
Chlorophyll Biosynthesis : Light-dependent and light-independent protochlorophyllide reduction
Authors: Schoefs Benoît , Frank Fabrice
Published: June 2020

Protochlorophyllide reductases are key enzymes in the process of chlorophyll biosynthesis. In this review, current knowledge on the molecular organization, substrate specificity and assembly of the light-dependent NADPH : protochlorophyllide oxidoreductases are dis¬ cussed. Characteristics of light-independent enzymes are then briefly described and the possible reasons for the selection of light-dependent enzymes in the course of evolution are discussed.
Biologie computationnelle des rythmes circadiens
Authors: Goldbeter Albert
Published: June 2020

Fondés sur les données expérimentales, des modèles théoriques de plus en plus détaillés ont été proposés pour le mécanisme moléculaire des rythmes circadiens. Ces rythmes, d'une période proche de 24 h, se produisent chez presque tous les organismes vivants et permettent leur adaptation à la périodicité naturelle de l'environnement liée à l'alternance du jour et de la nuit. L'exemple des rythmes circadiens illustre le rôle de la biologie computationnelle et montre comment les modèles et les simula¬ tions numériques contribuent à mettre en lumière l'origine, les propriétés, et la fonction des rythmes cellulaires.