Showing papers by "University of Mons published in 1991"

Purification and characterization of a bovine pregnancy-associated glycoprotein.

Abstract: A 67000 Mr bovine pregnancy-associated glycoprotein (bPAG) has been isolated from fetal cotyledons and purified to homogeneity by HPLC. The purification was monitored by a double immunodiffusion test and by RIA in conjunction with an antiserum raised against a crude fraction of placenta-specific antigens. The molecular weight of bPAG was estimated to be 67000 by SDS-PAGE. The isoelectric points (pI) of the four isoforms, determined by high-resolution analytical electrofocusing in polyacrylamide gel, were 4.4, 4.6, 5.2, and 5.4. The carbohydrate content of the bPAG consisted of approximately 10.02 +/- 1.09% neutral sugar and variant amounts of sialic acid (from 0.29 +/- 0.06% in the most basic isoform to 2.1 +/- 0.31% in the most acidic isoform). A specific antiserum was raised against the purified bPAG. A specific RIA showed that the bPAG was antigenically unrelated to BSA, alphafetoprotein (AFP), and human schwangerschafts-spezifischen (pregnancy-specific) beta 1 glycoprotein (SP1). According to some characteristics (e.g. the molecular weight), the purified bPAG may correspond to a form of the pregnancy-specific protein B previously described by Sasser and colleagues (Biol Reprod 1986; 35:936-942).

Inclusive particle production in 400 GeV/c pp-interactions

Abstract: We report on a study of inclusive particle production in pp-interactions at 400 GeV/c. The data are based on 472 K reconstructed events recorded in the NA 27 experiment using the LEBC-EHS facility at CERN. The production cross sections are determined of pseudo scalar (π±,0, η andK±), scalar (f0(975)), vector (ρ±,0(770), ω(783), ϕ(1020),K*0(892), and\(\bar K^{ * 0} \)(892)), and tensorf0 mesons, of protons and antiprotons, and theΔ++,+,0(1232), and Λ(1520) baryon resonances in the forward hemisphere of the center of mass system, as well as longitudinal and transverse momentum distributions. The results are compared with predictions of the FRITIOF model and with other experimental data.

Comparison of forward hadrons produced in muon interactions on nuclear targets and deuterium

Abstract: Differential multiplicities of forward produced hadrons in deep inelastic muon scattering on nuclear targets have been compared with those from deuterium. The ratios are observed to increase towards unity as the virtual photon energy increases with no significant dependence on the other muon kinematic variables. The hadron transverse momentum distribution is observed to be broadened in nuclear targets. The dependence on the remaining hadron variables is investigated and the results are discussed in the framework of intranuclear interaction models and in the context of the EMC effect.

Static and dynamic third-harmonic generation in long polyacetylene and polyparaphenylene vinylene chains

Abstract: We have calculated the full spectrum of the third-order optical susceptibility ${\mathrm{\ensuremath{\chi}}}^{(3)}$-3\ensuremath{\omega};\ensuremath{\omega},\ensuremath{\omega},\ensuremath{\omega}) in long oligomers of polyacetylene and polyparaphenylene vinylene, in the framework of a simple one-electron tight-binding approach. All doubly excited states are explicitly included in a sum-over-states formulation. The damping factors associated with resonances with excited states are modulated as a function of excited-state energy. Both the length dependence and the dynamic behavior of ${\mathrm{\ensuremath{\chi}}}^{(3)}$-3\ensuremath{\omega};\ensuremath{\omega},\ensuremath{\omega},\ensuremath{\omega}) are found to be in excellent agreement with experiment. Our results thus show that, contrary to the situation in very short polyenes, a one-electron theory can provide an accurate description of the nonlinear optical response in conjugated polymers.

Forward produced hadrons in mu p and mu d scattering and investigation of the charge structure of the nucleon

Abstract: Final data measured with the EMC forward spectrometer are presented on the production of forward charged hadrons in μp and μd scattering at incident beam energies between 100 and 280 GeV. The large statistic of 373 000 events allows a study of the semi-inclusive hadron production as a function ofz,pT2 and 〈pT2〉 in smallQ2,xBj andW bins. Charge multiplicity ratios and differences as a function ofz andxBj are given forp, d andn-targets. From the differences of charge multiplicities the ratio of the valence quark distributions of the protondv(x)/uv(x) is determined for the first time in charged lepton scattering. The Gronau et al. sum rule is tested, the measured sum being 0.31±0.06 stat. ±0.05 syst., compared with the theoretical expectation of 2/7≈0.286. The measured sum corresponds to an absolute value of the ratio of thed andu quark charge of 0.44±0.10 stat.±0.08 syst.

Photoemission study of the copper/poly(ethylene terephthalate) interface.

Abstract: The metallization of poly(ethylene terephthalate) (PET) by copper has been studied by photoelectron spectroscopy (x-ray and vacuum ultraviolet) The results are interpreted in the light of a valence-effective-Hamiltonian band-structure calculation on the PET polymeric chain and by comparison with earlier work on copper oxides The theoretical valence-band density of states is in very good agreement with the photoelectron spectra of PET and allows us to present a detailed interpretation of the valence electronic structure of PET Upon metallization, we find that, for low coverages (5\ifmmode\times\else\texttimes\fi{}${10}^{14}$ Cu atoms/${\mathrm{cm}}^{2}$) copper binds preferentially to the oxygen from the carbonyl (---C---O) and the ether (---C---O---) groups of the PET At coverages near 75\ifmmode\times\else\texttimes\fi{}${10}^{14}$ Cu atoms/${\mathrm{cm}}^{2}$, the additional copper remains metallic and gives rise to a three-dimensional islandlike growth mode The low reactivity towards PET stands in sharp contrast to the case of other transition metals, like Ti and Cr

Redistribution of epidermal growth factor immunoreactivity in renal tissue after nephrotoxin-induced tubular injury.

Abstract: Tubular necrosis elicits a process of renal tissue repair characterized by an increase of cell turnover in tubular epithelium. The present study was undertaken to examine the distribution of epidermal growth factor (EGF) and/or of its larger precursor proEGF in the kidney undergoing tubular regeneration. Sprague-Dawley rats were exposed to various drugs (aminoglycosides or platinum-based anticancer agents) known to induce tubular necrosis. The proliferative response resulting from renal tissue damage was measured by the incorporation of [H-3]thymidine into DNA of renal cells. EGF immunoreactivity was evidenced by immunocytochemical staining, using anti-EGF antibody and immunogold-silver staining. Concomitantly with the increase of cell proliferation resulting from tubular injury, a redistribution of EGF immunoreactivity was observed in renal tissue (from the inner stripe of outer medulla towards renal cortex). Amazingly, EGF was detected in proximal tubules of nephrotoxin-treated rats whereas, in the kidneys of control animals, it was almost exclusively found in distal tubules and collecting ducts. Insofar as the administration of exogenous EGF has recently been shown to enhance renal tubular regeneration after ischaemic injury [Humes et al: J Clin Invest 1989; 84:1757-1761], our observations lend further support to the concept that EGF might be involved in renal tissue repair.

On the measures of fluency in the assessment of spontaneous speech production by aphasic subjects

Abstract: Traditionally, 'fluency' is used first to refer to an aphasic syndrome and second to describe only a symptom, a defining speech output feature. Both of these uses may be questioned. Different dimensions of fluency, for instance articulatory agility and use of grammatical words, may be found independent; thus fluency does not identify with a consistent association of speech characteristics. When these dimensions are considered separately, other methodological and theoretical problems arise because the several decisions which are made in assessing the rate and ease of speaking do not relate explicitly to current models of speech production. The alternatives to fluency measures are various qualitative analyses of speech on the morpheme and sentence levels. Nevertheless, the inclusion of temporal variables remains useful when combined with a description of the morphological and structural aspects of the performance, when narratives are studied on the discourse level and, in a clinical setting, when therapists have specifically to deal with changes in fluency during the treatment of single cases of aphasia.

Allowed and forbidden transitions in highly ionized neon-like atoms (Ni XIX-U LXXXIII)

Abstract: Energy levels are calculated for highly ionized atoms of the neon sequence (Ni XIX to U LXXXIII). The multiconfigurational Dirac-Fock (MCDF) method, combined with semi-empirical corrections to the ab initio values of the energy levels, has been used for the calculations. Oscillator strengths are tabulated for 2p-3s, 2p-3d, 3s-3p and 3p-3d electric dipole (E1) transitions and for some Δn = 1 forbidden (E2, M1 and M2) lines originating from the ground state.

Transition rates and wavelengths in the X-ray spectra of nickel-like ions (Ag XX-Pb LV)

Abstract: The n = 3-4 transitions observed in the X-ray spectra of nickel-like ions (Ag XX-Pb LV) have been investigated theoretically by the multiconfigurational Dirac-Fock approach. The effect of the level crossings on the transitions rates of low excitation depopulation transitions is considered both for forbidden and for allowed transitions. A comparison of the ad initio wavelengths with the available observations for the resonance transitions shows that some experimental data must be refined.

Fine structure of the spermatophore and intradermic penetration of sperm cells in Myzostoma cirriferum (Annelida, Myzostomida)

Abstract: The spermatophore ofMyzostoma cirriferum is a white V-shaped structure up to ca. 500 μm long. It is formed by a translucent matrix which includes numerous cysts of two types that are very close together and tend to form interlacing twists. According to their contents, three spermatophoral regions can be distinguished: the body with the horns, the foot and the basal disc. The body-horns region forms the upper part of the spermatophore and extends over ca. 400 μm. This region includes mature spermiocysts which are formed by one cyst cell each including one to three groups of rolled up spermatozoons. Features of these cyst cells are their great length (up to 25 μm), their euchromatic nuclei each provided with a large nucleolus, their numerous mitochondria and osmiophilic vesicles included in the cytoplasm as well as cytoplasmic remnants of the residual bodies of the spermatids. Spermatozoons appear to be well adapted to the intradermic penetration occurring in this species in that all of them possess nuclei provided with dense nuclear grains, a hairpin-bent flagellum and a microtubular palissade. The spermatophore foot is located just below the body and extends over ca. 90 μm. It contains exclusively spermiocysts which include one to three abortive germinal cells. They differ also from the previous cysts by their smaller length (ca. 6–10 μm) and their more heterochromatic nuclei. The basal disc is the lower part of the spermatophore. It extends over ca. 10 μm and contains electron-dense vesicles in its upper part and vesicles with fibrillar material in its lower part. When mature myzostomids contact each other, a spermatophore is expulsed from one seminal vesicle of the donor myzostomid to the integument of the receiver myzostomid. The vesicles with fibrillar content are the first in contact with the cuticle of the receiver myzostomid. The material they include is supposed to have a histolytic action and to be responsible for the lysis of the cuticle and epidermal cells thus providing a passage for the spermatophore contents. Afterwards, cysts move as a result of the spermatozoons' beating and pass through the receiver's integument. At the time of penetration, cytoplasmic membranes of the cyst cells merge together forming an enormous syncytium extending into the whole receiver's body. This syncytium surrounds the spermatozoons and the abortive germinal cells. The whole process of intradermic penetration (i.e. from the fixation of the spermatophore to its reduction to an empty matrix) lasts from 1–5 h.

Influence of polymerization irregularities on the electronic properties of polythiophene

Abstract: The influence of α – β’(2–4’) linkages on the electronic structure of long polythiophene chains is investigated, with particular attention devoted to the spatial localization of the π levels The results demonstrate that the presence of α – β’ linkages increases the energy gap and leads to a spatial localization of the uppermost occupied levels within segments without defect Deeper-lying extended states are also found, characterizing a mobility edge for the system

Effects of ketamine on ocular movements of the cat.

Abstract: We studied the effects of ketamine, an antagonist of the N-methyl-D-aspartate receptors, on (1) the spontaneous saccades, (2) the vestibulo-ocular reflex (VOR), and (3) the optokinetic nystagmus (OKN) in 8 cats. Ketamine was given intramuscularly at four dosages (1, 2, 8, and 16 mg/kg). Eye movements were measured using the magnetic field-search coil technique. Ketamine did not prevent the occurrence of saccades, but each of them was followed by a centripetal postsaccadic drift. The time-constant of the drift induced by ketamine was 1.0 s when the given dosage was 1 mg/kg and 0.35 s when the given dosage was 16 mg/kg. Post-saccadic drift caused by a low dosage of ketamine may reflect only a mismatch between the pulse and the step commands that create saccades. The highest used dosages of ketamine aggravated the post-saccadic drift probably by disturbing the oculomotor neural integrator. To elicit the horizontal VOR, the head was submitted either to sinusoidal rotations (+/- 20 degrees; 0.05 to 1 Hz) or to a rotation at a constant velocity (100 degrees/s during 40 s). In darkness, the VOR step gain was reduced by ketamine in a dosage-dependent manner. VOR phase lead at 0.10 Hz oscillation in darkness increased from 4.0 degrees +/- 2.4 degrees to 51.6 degrees +/- 7.5 degrees after administration of ketamine at 16 mg/kg. This suggests that ketamine, at least at higher dosages, induces a failure of the neural integrator. Chemical blockade of the vestibular commissure by ketamine may also be responsible for the reduction of the VOR gain. Horizontal OKN was tested using a step stimulus (30 degrees/s during 40 s). When ketamine was given at 1 mg/kg, the average steady-state gain of the OKN diminished from 0.6 +/- 0.2 to 0.3 +/- 0.1. After administration of ketamine at 2 mg/kg, the OKN was abolished. The sensitivity of OKN to ketamine is explained at least partly by the fact that ketamine acts against the visual pathways in the retina, in the geniculate nucleus, and in the visual cortex. The time course of the optokinetic afternstagmus (OKAN) and that of the decrease of the prerotatory and postrotatory VOR were not reduced by ketamine administered at 1 or 2 mg/kg. This shows that ketamine does not affect the velocity-storage mechanism at these dosages.

Kinetics of CW laser-induced crystallization and oxidation of thin, Sb, Se, and Sb2Se3 films in air

Abstract: Thin films of Sb, Se and Sb2Se3 are deposited onto glass and irradiated by a cw-Ar+ laser beam The kinetics of crystallization and oxidation are traced via the time dependence of optical reflectivity and temperature, T, of the irradiated zone For Sb2Se3, transformations start abruptly when T attains a critical value, Tc, independently of the laser beam power These Tc values are comparable to the ones observed under furnace annealing conditions

Ultrastructure of the Penicillate Podia of the Spatangoid Echinoid Echinocardium cordatum (Echinodermata) with Special Emphasis on the Epidermal Sensory‐Secretory Complexes

Abstract: The spatangoid echinoid Echinocardium cordatum possesses specialized penicillate podia that handle sediment particles during burrowing and feeding. Epidermal complexes, which occur on podial surfaces directly contacting the sediment, each comprise four cells: a non-ciliated secretory cell containing granules rich in mucopolysaccharides (NCS cell), a ciliated secretory cell containing granules of unknown composition (CS cell), and two ciliated non-secretory cells (CNS cells). The cilium of the CS cell is subcuticular whereas that of each CNS cell traverses the cuticle. We propose that these four cells constitute a sensory-secretory complex wherein the ciliated cells are sensory cells and the secretory cells function for adhesion and de-adhesion. More exactly, an NCS cell adhesive and a CS cell de-adhesive would be sequential and would be initiated by two successive stimulations transduced by cilia when the podium touches the sediment. Cilia that first contact the sediment are those protruding through the cuticle from the CNS cells. Their stimulation would result in the secretion of an adhesive material by the NCS cells. Subsequently, the subcuticular cilia of CS cells would be stimulated when the podial digitations closely squeeze the substrate, and this would induce the secretion of a de-adhesive. These two antagonistic secretions would allow the podium to pick up and discharge sediment repetitively during burrowing and feeding.