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Showing papers by "University of Mons published in 1987"


Journal ArticleDOI
TL;DR: On the basis of the agreement of theory with data for solutions of small paramagnetic complexes, large magnetite particles, and liver containing low‐density polymer‐coated magnetite agglomerates, it is argued that the theory is sufficiently reliable so that, e.g., for ferritin, it appears that diffusion through intracellular gradients determines 1/T2.
Abstract: Since 1/T2 of protons of tissue water is generally much greater than 1/T1 at typical imaging fields, small single-ion contrast agents--such as Gd(DTPA), which make comparable incremental contributions and therefore smaller fractional contributions to 1/T2 compared to 1/T1--are not as desirable for contrast-enhancement as agents that could enhance 1/T2 preferentially. In principle, such specialized agents will only be effective at higher fields because the field dependence (dispersion) of 1/T1 is such that it approaches zero at high fields whereas 1/T2 approaches a constant value. The residual 1/T2 is called the "secular" contribution and arises from fluctuations in time--as sensed by the protons of diffusing solvent or tissue water molecules--of the component of the magnetic field parallel to the static applied field. For solutions or suspensions of sufficiently large paramagnetic or ferromagnetic particles (greater than or equal to 250 A diameter), the paramagnetic contributions to the relaxation rates satisfy 1/T2 much greater than 1/T1 at typical imaging fields. We examine the theory of secular relaxation in some detail, particularly as it applies to systems relevant to magnetic resonance imaging, and then analyze the data for solutions, suspensions, or tissue containing ferritin, erythrocytes, agar-bound magnetite particles, and liver with low-density composite polymer-coated magnetite. In most cases we can explain the relaxation data, often quantitatively, in terms of the theory of relaxation of protons (water molecules) diffusing in the outer sphere environments of magnetized particles. The dipolar field produced by these particles has a strong spatial dependence, and its apparent fluctuations in time as seen by the diffusing protons produce spin transitions that contribute to both 1/T1 and /T2 comparably at low fields; for the larger particles, because of dispersion, the secular term dominates at fields of interest. On the basis of the agreement of theory with data for solutions of small paramagnetic complexes, large magnetite particles, and liver containing low-density polymer-coated magnetite agglomerates, it is argued that the theory is sufficiently reliable so that, e.g., for ferritin--for which 1/T2 is unexpectedly large--the source of its large relaxivity must reside in nonideal chemistry of the ferritin core. For blood, it appears that diffusion through intracellular gradients determines 1/T2.

360 citations


Journal ArticleDOI
TL;DR: Each component of the early SEPs was thus distinctly influenced by the gating process during active movement interference, which could be in favour of separate cortical generators in the debate on the origin of SEP components.

172 citations


Journal ArticleDOI
TL;DR: It is concluded that the p.h.n. nucleus is involved in the integration processing, and that the m.v. is involved either in the Integration processing or in the relaying of the output of the neural integrator to the oculomotoneurones.
Abstract: 1. This study was intended to test the candidature of the prepositus-vestibular nuclear complex for being the location of the oculomotor neural integrator (Robinson's integrator). 2. Microinjections of kainic acid (2 micrograms dissolved in 1 microliter) were made in awake cats. Injection sites were located either in the prepositus hypoglossi nucleus (p.h.), the medial vestibular nucleus (m.v.n.), the medial longitudinal fasciculus (m.l.f.) or in the magnocellular tegmental field of the reticular formation. 3. Theory predicts that a complete disabling of the neural integrator will cause (a) an exponential post-saccadic drift whose time constant will be 0.16 s in the dark (b) a phase lead of +93 deg as the vestibulo-ocular reflex is tested at 0.10 Hz in the dark and (c) a nearly complete abolition of the optokinetic nystagmus (o.k.n.). 4. About 1 h after a unilateral kainic acid injection in the p.h., we observed (a) a large bilateral post-saccadic drift (time constant sometimes as low as 0.2 s) (b) a large phase lead at 0.10 Hz (range: from +69 to +98 deg) (c) an abolition of the o.k.n. control injection of phosphate buffer in the p.h. did not produce any deficit. 5. A unilateral kainic acid injection in the m.v.n. induced a nystagmus followed by signs of bilateral failure of the neural integrator similar to those observed after kainic acid injection in the p.h. 6. Injection near the mid-line, between the two p.h. nuclei, induced a defect of the neural integrator less than that observed after kainic acid injection in either the p.h. or the m.v.n. Injection of kainic acid in the magnocellular tegmental field of the reticular formation did not produce any sign of failure of the neural integrator. No post-saccadic drift was observed. 7. We have concluded that (a) the p.h. nucleus is involved in the integration processing, and that (b) the m.v.n. is involved either in the integration processing or in the relaying of the output of the neural integrator to the oculomotoneurones.

143 citations


Journal ArticleDOI
TL;DR: An immunogenic protein called P32 has been purified from Sauton zinc deficient culture filtrate of Mycobacterium bovis BCG using successively hydrophobic chromatography on Phenyl-Sepharose, ion exchange on DEAE-Sephacel and molecular sieving on Sephadex G-100 to be homogeneous as based on several analyses.

114 citations


Book ChapterDOI
Serge Nicaise1
01 Jan 1987
TL;DR: In this article, Tchebychev et al. present a formule de trace de trace 4nonc~e par J.P. Roth dans [R.1] that permits de donner une interpr4tation g4om4trique aux traces des polyn6mes de Tchebyschev de premiere espace de la matrice 9.
Abstract: INTRODUCTION. Une m4thode classique pour r4soudre le probl~me de Dirichlet ou de Neumann dans un ouvert de ~n est de construire une structure variationnelle associ4e ~ ce probl~me et d'4tablir l'existence d'une solution, dite faible, pour un tel probl~me (voir J.L. Lions [Li], par exemple). Le but du pr4sent article est d'utiliser ce point de vue pour 4tudier le laplacien sur un r4seau. Lorsque le r4seau est fini, nous 4tablissons le lien existant entre le spectre de cet op4rateur et les valeurs propres d'une matrice ~ que nous appelons matrice d'adjacence des sommets. Grace ~ ce lien, nous retrouvons une formule de trace 4nonc~e par J.P. Roth dans [R.1]. Cette derni~re formule permet de donner une interpr4tation g4om4trique aux traces des polyn6mes de Tchebychev de premiere espace de la matrice 9.

30 citations



Book ChapterDOI
01 Jan 1987
TL;DR: This paper summarizes some of the proposed definitions of a fuzzy preference relation, compares them and introduces the reader to the difficult problems of ranking and choice on the basis of a preference relation.
Abstract: This paper should be considered as an introduction to the fundamental properties of binary fuzzy relations. It summarizes some of the proposed definitions of a fuzzy preference relation, compares them and introduces the reader to the difficult problems of ranking and choice on the basis of a preference relation. The last part points out an important role of fuzzy relations in multicriteria analysis.

11 citations


Journal ArticleDOI
TL;DR: New algorithms by which fast phases are detected and by which slow phase cumulative eye position is reconstructed using and iterative procedure of best least squares fit are described, useful in neurophysiological studies on normal animals, but not in clinical analysis of nystagmus.
Abstract: A digital computer program has been developed for analysis of the nystagmus which results from sinusoidal head rotation. For any sinusoidal vestibular stimulation between 0.05 Hz and 1 Hz, the program, accepts sampled records of eye position and head velocity and yields cumulative eye position as well the phase and the gain of the vestibuloocular reflex. Described in this paper are new algorithms by which fast phases are detected and by which slow phase cumulative eye position is reconstructed using and iterative procedure of best least squares fit. These algorithms are useful in neurophysiological studies on normal animals, but not in clinical analysis of nystagmus.

11 citations


Journal ArticleDOI
TL;DR: In this paper, 13C dipole-dipole spin-lattice relaxation times were used to analyse prototropic equilibria of 2-acetylbenzimidazole (1) and 4-azabenzimidrazole (2) in DMSO-d6 solutions.
Abstract: Quaternary 13C dipole–dipole spin–lattice relaxation times are used to analyse prototropic equilibria of 2-acetylbenzimidazole (1) and 4-azabenzimidazole in DMSO-d6 solutions. For the first compound, fast exchange between the two chelated structures prevails for 13C relaxation times, whereas proton and 13C chemical shifts characterize a slow exchange. For 4-azabenzimidazole, 13C and 1H spectra do not exhibit absorptions from structures in slow exchange. Analysis of the T1 values of carbons 8 and 9 before and after isotopic exchange of the labile amino hydrogen clearly show that the major component of the equilibrium is the 3H structure.

10 citations


Book ChapterDOI
01 Jan 1987
TL;DR: In this paper, the authors present necessary and sufficient axiomatic systems for the existence of ratio and interval scales of measurement related to the notion of intensity of preference, which can be obtained using comparisons of probability measures.
Abstract: This paper presents necessary and sufficient axiomatic systems for the existence of ratio and interval scales of measurement related to the notion of intensity of preference. The relationships between these scales and the ratio and interval scales which can be obtained using comparisons of probability measures are studied; some implications for decision-support are emphasized. An assessment procedure for constructing “intensity of preference functions” is also proposed.

9 citations


Journal ArticleDOI
TL;DR: In this article, several factors governing the course of aminopyrazole-4-carboxylic acid derivatives and orthoesters or amide acetals are discussed, and the introduction of a heteroalkylidene moiety on the amino group of ethyl aminoprocessor 4 carboxylates is discussed.


Journal ArticleDOI
TL;DR: In this article, the authors report on a study of π−−p interactions at 360 GeV/c, using the LEBC-EHS set-up at CERN and reconstructing about 165000 events.
Abstract: We report on a study ofρ 0 andf 2 inclusive production in π−−p interactions at 360 GeV/c, using the LEBC-EHS set-up at CERN and reconstructing about 165000 events. Theρ 0,f 2 andρ 3 0 cross sections are determined forx F >0,x F >0.4 andx F >0.6 respectively and theρ 0 andf 2 Feynman-x distributions and transverse momentum distributions are presented.

Journal ArticleDOI
TL;DR: In this paper, the ring closure mechanism is discussed and the synthesis of isomeric 2-pyrazolyl-1,3,4-oxadiazoles, as major compounds, either from triethyl orthoacetate and 1-methyl-5-aminopyrazole-4-carboxhydrazide or from dimethylacetamide dimethyl acetal and various heterocyclic precursors.


Journal ArticleDOI
M. Wautelet1
01 Oct 1987
TL;DR: From the analysis of the technical literature on ‘star wars’ and related concepts, it appears that it would most probably rely on some nuclear sub‐components, among these are orbiting nuclear reactors, nuclear explosion driven weapons, and nuclear‐armed missiles and mines.
Abstract: From the analysis of the technical literature on ‘star wars’ and related concepts, it appears that it would most probably rely on some nuclear sub‐components. Among these are orbiting nuclear reactors, nuclear explosion driven weapons, and nuclear‐armed missiles and mines. The risks associated with their deployment and use are analysed.

Book ChapterDOI
01 Jan 1987
TL;DR: In this paper, a family of coloured compounds having metallic lustre and crystallizing as needles has been synthetized by controlled oxidation of Magnus green salt [Pt(NH3)4][ PtCl4] (MGS) and PtBr4] in aqueous HClO4 or HBF4.
Abstract: A family of coloured compounds having metallic lustre and crystallizing as needles has been synthetized by controlled oxidation of Magnus green salt [Pt(NH3)4][ PtCl4] (MGS) and Magnus green-type salt [ Pt(NH3)4] [ PtBr4] in aqueous HClO4 or HBF4. Experimental evidences show that all these compounds are single-phase materials having tetragonal structure and containing two types of mixed-valence platinum chains (of class IIIb and class II respectively1) with chain axis as the c axis: (a) Class IIIb, valency delocalized Pt⋯pt chains where Pt is in a non-integral (presumably 2.33) oxidation state. These chains (α chains) are partially oxidized MGS-like chains with a Pt-Pt intrachain distance (= c/2) ranging from 2.85 to 2.92 A depending on the kind of complex; (b) Class II, with partially delocalized valencies, halogen-bridged Pt(II)⋯Y-Pt(IV) chains (Wolffram’s type β chains with Y=Cl,Br, I).


Journal ArticleDOI
TL;DR: Flash-vacuum pyrolysis of azolides of 1,2,4-triazole affords 5-monosubstituted oxazoles as mentioned in this paper.
Abstract: Flash-vacuum pyrolysis of azolides of 1,2,4-triazole affords 5-monosubstituted oxazoles.

Book ChapterDOI
J. Genard1, R. Penninckx1, B. Capel1, R. Lenoir1, R. Kramp1 
01 Jan 1987
TL;DR: Torasemide, 1-isopropyl-3-{[4-(3′-methyl-phenylamino)-pyridine]-3-sulfonyl}urea, is a novel diuretic belonging to a new chemical series derived from 4-anilino-3 pyridine-sulonylurea as discussed by the authors.
Abstract: Torasemide, 1-isopropyl-3-{[4-(3′-methyl-phenylamino)-pyridine]-3-sulfonyl}urea, is a novel diuretic belonging to a new chemical series derived from 4-anilino-3-pyridine-sulfonylurea.

Book ChapterDOI
01 Jan 1987
TL;DR: In this article, Monte Carlo simulations of surface reactions are used to give an exhaustive account of the logical consequences issued from specific assumptions, data, theory and mechanisms involved in the construction of a conceptual model.
Abstract: We present here Monte Carlo (MC) simulations of surface reactions. We consider reactions between gaseous species adsorbed on a catalytic solid surface. The reactions investigated occur in such a range of pressure and temperature that the surface remains almost entirely covered by an adsorbate which never exceeds a monolayer. The procedure of a computer experiment is very similar to that of a laboratory experiment designed to test a conceptual model within the framework of existing physical laws. However, contrary to a laboratory experiment, a MC simulation allows a complete control over the parameters that influence the operation of the model. The effect of a given physical factor on the behaviour of the model can be precisely isolated and systematically studied. A MC simulation can be used, therefore, to give an exhaustive account of the logical consequences issued from the specific assumptions, data, theory and mechanisms involved in the construction of a conceptual model.

Book ChapterDOI
J. Genard1, R. Penninckx1, B. Capel1, R. Lenoir1, R. Kramp1 
01 Jan 1987
TL;DR: Several metabolites of torasemide appear in the urine of the rat and the efficacy of two metabolites, C3534 and C3535, was tested in the present study.
Abstract: Several metabolites of torasemide appear in the urine of the rat (1). The efficacy of two metabolites, C3534 and C3535, was tested in the present study. Their effects upon urine flow (V), sodium (UNa.V), chloride (UCl.V) and potassium (UK.V) were studied after application of the metabolites upon the left renal capsule or after i.v. injection.

Journal ArticleDOI
TL;DR: In this paper, the absolute minima for the SO(3) invariant Landau potential for the nine-dimensional irreducible representation is discussed as a function of the coupling constants.