Thermal nucleation of cavities in liquid helium at negative pressures

1993

We have investigated the nucleation rate at which cavities are formed in $^{4}\mathrm{He}$ and $^{3}\mathrm{He}$ at negative pressures due to thermal fluctuations. To this end, we have used a density functional that reproduces the He liquid-gas interface along the coexistence line. The inclusion of thermal effects in the calculation of the barrier against nucleation results in a sizable decrease of the absolute value of the tensile strength above 1.5 K.

NUMERICAL IMPLEMENTATION OF A K.A.M. ALGORITHM

1993

We discuss a numerical implementation of a K.A.M. algorithm to determine invariant tori, for systems that are quadratic in the action variables. The method has the advantage that the iteration procedure does not produce higher order terms in the actions, allowing thus a systematic control of the convergence.

Recombinant cDNA encapsulation in small liposomes with hepatocyte access ability.

1993

Liposomal encapsulation efficiency of a recombinant cDNA was studied by several procedures. We observed that supernatant fraction of ultracentrifuged liposomes prepared by extrusion through polycarbonate filters of 400 nm pore size yielded a very homogeneous suspension of small (50 nm diameter) unilamellar liposomes with highest DNA/lipid ratio and great ability to access to hepatocytes.

2,2'-BIPYRIMIDINEOXALATOCOPPER(II) COMPLEXES - FROM THE MONONUCLEAR COMPLEX TO THE 2D SHEET-LIKE POLYMER

1993

Preconcentration of aluminium by micellar-enhanced ultrafiltration

1993

Abstract Traces of aluminium were preconcentrated in water samples by forming a complex with lumogallion, and successfully accumulated in the micellar phase obtained from cationic or non-ionic surfactants and filtered through 10 000 molecular weight cut-off ultrafiltration membranes. Studies indicated that, at pH 5.9, with 1 X 10 −3 M lumogallion and 2 X 10 −2 M cetyltrimethylamonium bromide, quantitative retention of aluminium present at μg ml −1 concentration levels was achieved. A micellar-enhanced fluorimetric procedure was employed to analyse the permeate solutions, whereas nitrous oxide-acetylene flame atomic emission spectrometry was used to determine aluminium in the retentate. The …

Long-term function of porcine islets and single cells embedded in barium-alginate matrix.

1993

The influence of alginate-embedding on the maintenance of functioning and morphological integrity in long-term culture of isolated porcine islets and islet cells was studied. Free-floating islets and islet cells served for control. Function was tested after the 1st, 2nd and 4th week. Basal and glucose-stimulated insulin secretion of embedded islets decreased slightly, but significantly after the first week (from 4.39 +/- 0.64 to 2.87 +/- 0.47 at normal and from 11.96 +/- 1.44 to 4.76 +/- 0.78 microU pro 24 h pro islet at elevated glucose concentration, p < 0.05 and < 0.01, resp.) and remained unchanged thereafter. Glucose-stimulation resulted in significant increases in insulin secretion at…

Red-green flicker resolution as a function of heterochromatic luminous modulation.

1993

Critical fusion frequencies have been evaluated in heterochromatic red-green flicker as a function of red-green luminous modulation defined by mL = (R-G)/(R+G)%, at five different mean luminance levels, two test sizes (2 degrees and 5 degrees) and square wave stimuli. The extreme values mL = +/- 100 correspond to ordinary light-dark flicker (red or green); mL = 0 corresponds to pure chromatic flicker, and any other values correspond to simultaneous luminous and chromatic flicker. To implement the stimuli we have developed a new stimuli generator (AVICO, colour vision analyser) using bicolour LEDs as the light source and electronic control of the luminances and frequencies. The results for a…

Simple high-performance liquid chromatographic assay for polyamines and their monoacetyl derivatives.

1993

A rapid reversed-phase high-performance liquid chromatographic method, using pre-column derivatization with benzoyl chloride and ultraviolet detection at 254 nm, was developed for the simultaneous measurement of polyamines and their monoacetyl derivatives. Calibration curves were linear for concentrations from 1.25 to 25 nmol/ml. The method was employed to assay these compounds in chick embryo retina explants using organic solvent extraction and 1,7-diaminoheptane as an internal standard. This simple and sensitive method can be applied to routine determinations of these compounds in various biological samples.

S-type lectins occur also in invertebrates: high conservation of the carbohydrate recognition domain in the lectin genes from the marine sponge Geodi…

1993

The marine sponge Geodia cydonium contains several lectins. The main component, called lectin-1, is composed of three to four identical subunits. The subunits of the lectins were cloned from a cDNA library; two clones were obtained. From the deduced aa sequence of one clone, LECT-1, a mol. wt of 15,313 Da is calculated; this value is in good agreement with mass spectrometric analysis of 15,453 +/- 25 Da. The sequence of another clone, LECT-2, was analysed and the aa sequence was deduced (15,433 Da). The two subunits have a framework sequence of 38 conserved aa which are characteristic for the carbohydrate-binding site of vertebrate S-type lectins. Clustering of lectin sequences of various s…

The role of obstetric complications in schizophrenia.

1993

The importance of obstetric complications in sporadic and familial psychoses was analyzed in 43 schizophrenic and 28 chronic schizoaffective patients. Patients and first-degree relatives were diagnosed using Research Diagnostic Criteria and the best-estimate procedure. Mothers of patients were interviewed for histories of pregnancy and obstetric complications in their offspring. Patients had more often suffered perinatal complications (42%) than their siblings (29%). The risk for obstetric complications and secondary cases of psychosis was enhanced in relatives of patients with a history of obstetric complications. Siblings with obstetric complications had a low incidence of psychoses; ther…

The magnetic properties of ferrocene based macromolecules

1993

Abstract Magnetic susceptibility data for conjugatively linked biferrocenes and a methylene bridged ferrocene polymer are presented. In 9,10-di((2-ferrocenyl)vinyl)anthracene a rigid divinylanthracene bridge is connecting two ferrocene units, and the oxidation of both iron centers leads to an antiferromagnetic coupling. In contrast, ferromagnetic coupling between iron centers is indicated for 2,2'-cis,trans-di((2-ferrocenyl)vinyl)biphenyl, where a twist around the phenyl-phenyl bond in the divinylbiphenyl bridging molecule is likely to occur.

Über gemischte gruppe 14-gruppe 14-bindungen

1993

Abstract The lead-tin compounds o-Tol6PbSn, o-Tol3PbSnPh3 and Mes3PbSnPh3 have been synthesized from Li and halide precursors in THF/ether at low temperatures. The crystal structures of the S4 symmetric o-Tol4Pb and of the three isomorphous title compounds have been determined (d(SnSn) 2.883 (1), d (PbSn) 2.845 (2), d (PbPb) 2.895 (2), A). The long SnSn distance is in accordance with the Raman data for the pairs of p-Tol6/o-Tol6 substituents (ν(SnSn) 131/123, ν(PbSn) 114/114, ν(PbPb) 105/103 cm−1). The sequence of the 119Sn and 207Pb chemical shifts shows clearly a polarity Pbδ−Snδ+ for all lead-tin compounds investigated. The 1J (119Sn207Pb) and 1J(119Sn119Sn) couplings of identi…

L'inauguration du musée d'art moderne et d'art contemporain de Nice en 1990

1993

The inauguration of the Nice Museum of Modem and Conteporary Art in 1990, Philippe Poirrier. On 8 April 1990, the Franco-American sculptor Annan refused to inaugurate the retrospective of his work at the new Modem and Contemporary Art Museum of Nice in company of Jacques Médecin, mayor of Nice. The reason was the mayor's complecency vis-à-vis the National Front's theses. The incident originated a local and then a national affair that in which the artists, the elected officials of the Côte d'Azur and the minister of Culture, Jack Lang, were involved. The debate clearly illustrates some of the political stakes involved in cultural policies in France.

Invariant rotational curves in Sitnikov's Problem

1993

The Sitnikov's Problem is a Restricted Three-Body Problem of Celestial Mechanics depending on a parameter, the eccentricity,e. The Hamiltonian,H(z, v, t, e), does not depend ont ife=0 and we have an integrable system; ife is small the KAM Theory proves the existence of invariant rotational curves, IRC. For larger eccentricities, we show that there exist two complementary sequences of intervals of values ofe that accumulate to the maximum admissible value of the eccentricity, 1, and such that, for one of the sequences IRC around a fixed point persist. Moreover, they shrink to the planez=0 ase tends to 1.

Timolol derivatives. I. X-ray, NMR and theoretical studies of the crystallization of (S)-timolol O,O-diacetyl-l-tartaric acid monoester

1993

Abstract The absolute configurations of (S)-timolol hemihydrate and (S)-timolol O,O-diacetyl-(R,R)-tartaric acid monoester were determined by single crystal X-ray diffraction. An NMR analysis based on the temperature dependence of vicinal coupling constants was carried out to characterize the conformational behaviour of the S,R,R- and R,R,R-forms in solution. The same conformation as in crystalline state was also found in solution, although with a rather low preference over some other conformations. Results of theoretical calculations using MNDO and AMBER force field methods are reported. An infinite chain of hydrogen bonds, along with other favourable inter- and intramolecular forces that …

Measurement of the spin-dependent structure function g1(x) of the deuteron

1993

We report on the first measurement of the spin-dependent structure function g1d of the deuteron in the deep inelastic scattering of polarised muons off polarised deuterons, in the kinematical range 0.006&lt;x&lt;0.6, 1 GeV2&lt;Q2&lt;30 GeV2. The first moment, Γ1d=sh{phonetic}01 g1d dx=0.023±0.020 (stat.) ± 0.015 (syst.), is smaller than the prediction of the Ellis-Jaffe sum rules. Using earlier measurements of g1p, we infer the first moment of the spin-dependent neutron structure function g1n. The difference Γ1p-Γ1n=0.20 ±0.05 (stat.) ± 0.04 (syst.) agrees with the prediction of the Bjorken sum rule, Γ1p-Γ1n=0.191 ±0.002.

Effects of leflunomide on immune responses and models of inflammation.

1993

Leflunomide is an antiphlogistic and immunomodulating agent that has been shown to be effective in preventing and healing autoimmune disorders and reactions leading to organ graft rejection. From our preliminary clinical data [4], we now have hopes that these effects, observed in experimental animals, can truly be transferred to humans. Although we are far from understanding the mode of action of leflunomide, we are slowly gathering some insight. A good many of the immunosuppressive effects of leflunomide can be attributed to the antagonistic effects it has on responses to many cytokines, most likely through receptor expression and signal transduction (tyrosine kinase inhibition). The inhib…

Mechanism of self-trapped hole motion in corundum crystals

1993

Abstract Atomistic simulations of the self-trapped hole eauilibrium geometry and migration in a pure corundum crystal have been carried out using the semiempirical method of intermedia te neglect of differential overlap and atom-atom potentials, as implemented in the CASCADE code. The activation energies for three different hole-hopping mechanisms are calculated. It is shown that the 60° reorientations of a self-trapped hole and hopping to the nearest O-atom triangle reauire almost the same activation energy, approximately 0.9 eV, which agrees auite well with the experi-mental value for hole migration of 0.7 eV. A new mechanism of small-polaron motion is suggested.

Stellenwert der Inhalationsanästhetika in der Neuroanästhesie - Eine Betrachtung der „Nebenwirkungen”

1993

Geometric and electronic structure of dithiapyranylidine: evolution upon oxidation

1993

Abstract We present a theoretical investigation of the modifications that successive oxidation induces on the geometric and electronic structures of the π-electron donor dithiapyranylidene. The lengthening of the double bonds and the shortening of the single bonds calculated as the molecular charge increases indicate a gain of aromaticity with oxidation. Both the geometricand the electronic structure of dithiapyranylidene show a clear evolution towards those of biphenyl as oxidation takes place.

Coherent π0 electroproduction

1993

Abstract We analyze the coherent electroproduction of neutral pions in nuclei. We find that this process does not contribute to the longitudinal response function for spin saturated nuclei and the dependence of the cross section on the azimuthal pion angle is particularly simple and given by 1− ϵ cos 2 o π . This angular dependence could be useful to isolate the coherent contribution in future experiments, offering an advantage over coherent photoproduction. The Δ-peak is considerably moved to lower pion energies and appreciably modified due to medium corrections.

Optimal dose of omeprazole in duodenal ulcer

1993

Use of carbon dioxide enrichment to obtain adult morphology of grapevinein vitro

1993

A procedure has been developed forin vitro propagation ofVitis vinifera ‘Pinot noir’ from lateral-bud cuttings under high CO2 concentration (1200 µmol mol−1). Because of inhibition of rooting by CO2, this procedure requires a rooting pre-culture of explants on medium with sucrose before the CO2-enriched culture on sucrose-free medium. Shoot growth was enhanced by CO2 enrichment as a result of both a higher rate of leaf production and greater internode elongation. Leaf expansion and tendril growth were promoted and better rooting was obtained. The more significant effect of CO2 enrichment was to promote adult morphology with, in particular, the tendril pattern. Thus, for the first time, grap…

Cell Cycle in Potentially Dedifferentiating Cereal Mesophyll Protoplasts Cultured in vitro. I. Abnormalities in Cycle Kinetics

1993

Summary Protoplasts isolated from immature and mature mesophyll of wheat and oats were cultured in vitro . The potential progression from G1 (G0) to G2, through mitosis and cytokinesis was analysed. The degree and speed of progression through the cell cycle depended on the species and the state of maturity of the tissue from which the protoplasts were derived. In all the protoplast populations that were tested at least initiation of DNA synthesis was detected by labelling nuclei with the thymidine-analogue, bromodeoxyuridine (BrdU). Protoplasts derived from mature leaf tissue of wheat appeared to be recalcitrant to reach G2. Wheat protoplasts derived from immature leaf tissue appeared to pr…

Quantum deformations of singletons and of free zero-mass fields

1993

We consider quantum deformations of the real symplectic (or anti-De Sitter) algebra sp(4), ℝ ≅ spin(3, 2) and of its singleton and (4-dimensional) zero-mass representations. For q a root of −1, these representations admit finite-dimensional unitary subrepresentations. It is pointed out that Uq(sp(4, ℝ)), unlike Uq(su(2, 2)), contains Uq(sl2) as a quantum subalgebra.

Penning-trap mass measurements of neutron-deficient Rb and Sr isotopes

1993

Abstract The Penning-trap mass spectrometer ISOLTRAP installed at the on-line mass separator ISOLDE 2 at CERN has been used for mass determination of 75–87 Rb and 78–83,87 Sr. Ions are captured in a Penning trap and their cyclotron frequency ω c = ( q m )B in the trapping field B is measured. Ratios of these frequencies lead to the determination of the atomic mass of these isotopes. A resolving power of typically m Δm = 10 6 and an accuracy of δm ≈10 keV is obtained. The mass of 78 Sr is measured for the first time and, in most cases, the mass values of the other isotopes are significantly improved. The experimental masses are compared with theoretical predictions.

Expression of inhibitory glycine receptors in postnatal rat cerebral cortex.

1993

The developmental expression of inhibitory glycine receptors was analyzed in postnatal rat cerebral cortex using the specific monoclonal antibody, MAb 4a. This antibody defines an epitope common to all known glycine receptor alpha-subunits. At birth, high levels of immunoreactivity were found, which transiently increased during the second postnatal week, but subsequently declined to low adult levels. Biochemical analysis of the MAb 4a antigen from parietal areas indicates that cortical glycine receptors correspond to the neonatal receptor isoform previously identified in spinal cord of newborn animals. Immunocytochemistry showed that, within 2 weeks after birth, MAb 4a-reactive glycine rece…

Electrical Resistivity Anisotropy of Silicon-Doped n-Indium Selenide

1993

Reaktionen von Benzothiet mit Iminen

1993

Reactions of Benzothiete with Imines A great variety of compounds 3a–w containing CN double bonds was studied in the reaction with benzothiete (1). H, alkyl, aryl, OR, SR and NR groups can be attached to the imino function. The azomethines 3a–f, the thiazolines 3g–i, the lactim 3n, the oximes 3r–t, the isoxazolinone 3u and the azine 3v show [8π + 2π] cycloaddition reactions yielding derivatives of 1,3-benzothiazine (4a–i, n, r–v). In the case of 4n, s, t secondary reactions occur, initiated by elimination processes. [8π + 2π] Cycloadditions account also for the reactions 3e 10, 11, 3o 18(I), and 3q 19; however, CC double bonds are representing the 2π component in these examples. The thiazol…

Cautionnement. Recevabilité de la déclaration de la caution pour sa créance personnelle d'indemnité

1993

International audience; (Com. 29 oct. 1991, Sté Lebanese Arab Bank et autres c/ Sté Forges Thermal et autres)

Bail commercial. Droit d'entrée restant dû par le preneur après cession du droit au bail, Créance née dès la conclusion du bail antérieurement au jug…

1993

International audience; (Com. 14 avr. 1992, SA Etablissements Deletang c/ Sté Granada distribution et autres)

Créances fiscales. Admission par le juge-commissaire, Effets, Interversion de la prescription (non)

1993

International audience; (CE 3 juin 1992, Req. n° 67-215, ministre de l'Economie, des Finances et du Budget c/ M. Drux)

Créances fiscales. Privilège du Trésor, TVA, article 1926, alinéa 3, CGI, Privilège limité aux droits et intérêts de retard des six mois précédant le…

1993

International audience; (CE Plén., 10 avr. 1992, Req. n° 93-311, Gaillard)

Optical phonons and electron-phonon interaction in quantum wires.

1993

A unified macroscopic continuum theory for the treatment of optical-phonon modes in quantum-wire structures is established. The theory is based on a Lagrangian formalism from which the equations of motion are rigorously derived. They consist of four coupled second-order differential equations for the vibrational amplitude and electrostatic potential. The matching boundary conditions are obtained from the fundamental equations. It is shown that no incompatibility exists between mechanical and electrostatic matching boundary conditions when a correct mathematical treatment of the problem is given. The particular case of a GaAs quantum wire buried in AlAs, where the phonons can be considered c…

Parametrization of scatterers in the Landauer-Büttiker transport theory.

1993

Electronic dc transport along a finite chain of scatterers that allow for elastic as well as inelastic processes is described within the Landauer-Buttiker approach. The transport channels in the chain are locally coupled via (current-conserving) side channels to electron reservoirs or heat baths that provide the phase randomization. Different choices for the parameters describing the inelastic coupling as well as the elastic (transmission and reflection) coefficients are compared. The scattering matrix of the chain is calculated with a recursive method. We show that the most general individual scatterer can be characterized by five parameters only, and that it can be represented by a subset…

Arrêt des poursuites individuelles. Sous-traitant, Action directe contre le maître de l'ouvrage, Obligation de mettre en demeure l'entrepreneur princ…

1993

International audience; (Rép. quest. écrite n° 51711 : JO Ass. nat. (Q), 25 mai 1992, p. 2356)