Showing papers by "University of Mons published in 1999"
TL;DR: In this article, the effects of a particular deformed Heisenberg algebra on an energy spectrum were calculated perturbatively and the results showed that splittings of degenerate energy levels appeared.
Abstract: We propose a new approach to calculate perturbatively the effects of a particular deformed Heisenberg algebra on an energy spectrum. We use this method to calculate the harmonic oscillator spectrum and find that the corrections are in agreement with a previous calculation. Then, we apply this approach to obtain the hydrogen atom spectrum and we find that splittings of degenerate energy levels appear. Comparison with experimental data yields an interesting upper bound for the deformation parameter of the Heisenberg algebra.
462 citations
TL;DR: In this article, the spontaneous spreading of liquid droplets is studied by molecular modeling simulations, where the influence of the solid−liquid interactions on the overall wetting dynamics is investigated.
Abstract: The spontaneous spreading of liquid droplets is studied by molecular modeling simulations. By considering very large systems, we are able to study the influence of the solid−liquid interactions on the overall wetting dynamics. It is shown how microscopic parameters, such as the mobility of the molecules near the solid−liquid interface, can be measured. At the same time, relevant macroscopic parameters, such as dynamic contact angles and flow fields, are calculated from the simulations. The results strongly support the microscopic validity of the molecular-kinetic model of wetting.
344 citations
TL;DR: In this paper, it was shown that charge transfer occurs at the interface between MEH-PPV and a cyanosubstituted PPV derivative, whereas energy transfer takes place in the interface of PPV with the same cyanos-substitized polymer.
Abstract: When an exciton approaches the interface between two conjugated polymers, either energy or charge transfer can take place. We present a detailed experimental investigation of these processes in various binary polymer systems. The results are interpreted in the context of quantum-chemical calculations that provide estimates of the relative energies of intrachain versus interchain excited states in pairs of various PPV-related chains. In particular, we show that charge-transfer occurs at the interface between MEH-PPV and a cyanosubstituted PPV derivative, whereas energy transfer takes place at the interface of PPV with the same cyanosubstituted polymer. @S0163-1829~99!08031-5#
284 citations
264 citations
TL;DR: The cloning of human and rat cDNAs encoding B166 is reported, which has been renamed AOEB166 for antioxidantenzyme B166, suggesting a protective role for AoeB166 in oxidative and inflammatory processes.
244 citations
TL;DR: Results show that calretinin plays a major role at the network level in cerebellar physiology as well as in slices, indicating that marked modifications of the firing behavior in vivo can be undetectable in slice.
Abstract: In the cerebellum, the parallel fiber-Purkinje cell synapse can undergo long-term synaptic plasticity suggested to underlie motor learning and resulting from variations in intracellular calcium concentration ([Ca2+]i). Ca2+ binding proteins are enriched in the cerebellum, but their role in information processing is not clear. Here, we show that mice deficient in calretinin (Cr-/-) are impaired in tests of motor coordination. An impairment in Ca2+ homeostasis in Cr-/- Purkinje cells was supported by the high Ca2+-saturation of calbindin-D28k in these cells. The firing behavior of Purkinje cells is severely affected in Cr-/- alert mice, with alterations of simple spike firing rate, complex spike duration, and simple spike pause. In contrast, in slices, transmission at parallel fiber- or climbing fiber-Purkinje cell synapses is unaltered, indicating that marked modifications of the firing behavior in vivo can be undetectable in slice. Thus, these results show that calretinin plays a major role at the network level in cerebellar physiology.
184 citations
TL;DR: In this paper, a combination of radiative lifetimes measured using the fast-beam-laser method and experimental branching ratios deduced from Fourier transform spectrometer spectra was used to derive experimental f-values for Luii lines observed in the visible and near-ultraviolet regions.
Abstract: By a combination of radiative lifetimes measured using the fast-beam-laser method and experimental branching ratios deduced from Fourier transform spectrometer spectra, it has been possible to derive experimental f-values for Lu ii lines observed in the visible and near-ultraviolet regions. These data are compared with relativistic Hartree–Fock calculations, taking core polarization effects into account, and a set of additional oscillator strengths of astrophysical interest is presented.
174 citations
TL;DR: Conjugated organic polymers can be doped, via oxidation or reduction chemistry or via acid-base chemistry, to induce very high electrical conductivity as mentioned in this paper, and they are beginning to find use.
162 citations
TL;DR: Electrophysiological experiments revealed the presence of channels with a 105 pS conductance and no ionic selectivity that could be responsible for the translocation of Yop effectors, which were generated by mutants devoid of the effectors and by lcrG mutants, as well as by wild‐type bacteria.
Abstract: 'Type III secretion' allows extracellular adherent bacteria to inject bacterial effector proteins into the cytosol of their animal or plant host cells. In the archetypal Yersinia system the secreted proteins are called Yops. Some of them are intracellular effectors, while YopB and YopD have been shown by genetic analyses to be dedicated to the translocation of these effectors. Here, the secretion of Yops by Y.enterocolitica was induced in the presence of liposomes, and some Yops, including YopB and YopD, were found to be inserted into liposomes. The proteoliposomes were fused to a planar lipid membrane to characterize the putative pore-forming properties of the lipid-bound Yops. Electrophysiological experiments revealed the presence of channels with a 105 pS conductance and no ionic selectivity. Channels with those properties were generated by mutants devoid of the effectors and by lcrG mutants, as well as by wild-type bacteria. In contrast, mutants devoid of YopB did not generate channels and mutants devoid of YopD led to current fluctuations that were different from those observed with wild-type bacteria. The observed channel could be responsible for the translocation of Yop effectors.
158 citations
TL;DR: To model the interaction of hormones, symptoms and psychosocial factors on women's sexuality during the menopausal transition, a community-based sample of 438 Australian-born women aged 45-55 years was carried out.
Abstract: Objective To model the interaction of hormones, symptoms and psychosocial factors on women's sexuality during the menopausal transition.Design and methods A prospective, observational study was carried out of a community-based sample of 438 Australian-born women aged 45-55 years at baseline. The study comprised six annual assessments in the women's own homes utilizing a core questionnaire, with rating scales for well-being and daily hassles, and a Personal Experiences Questionnaire as a measure of sexual functioning. Levels of follicle stimulating hormone (FSH), estradiol and inhibin were measured annually. Statistical analysis was performed by structural equation modelling.Results The retention rate was 90% (final sample size after exclusions, n = 354). The normal fit index for the global model obtained was 0.92. There is a significant direct effect of menopausal status on vaginal dryness/dyspareunia, and an indirect effect on sexual responsivity via a direct effect of menopausal status on symptoms, whic...
136 citations
University of Santiago de Compostela1, Boğaziçi University2, Uppsala University3, University of Warsaw4, Bielefeld University5, Aalto University6, Ludwig Maximilian University of Munich7, University of Trieste8, Université Paris-Saclay9, University of Mainz10, University of Virginia11, Delft University of Technology12, University of California, Los Angeles13, Yale University14, Northwestern University15, University of Houston16, University of Freiburg17, Ruhr University Bochum18, Nagoya University19, CERN20, Joint Institute for Nuclear Research21, Tel Aviv University22, University of Mons23
TL;DR: In this article, the spin asymmetries of the proton and the deuteron in the kinematic region extending down to (Formula presented) and (formula presented).
Abstract: We present the results of the spin asymmetries (Formula presented) of the proton and the deuteron in the kinematic region extending down to (Formula presented) and (Formula presented) The data were taken with a dedicated low x trigger, which required hadron detection in addition to the scattered muon, so as to reduce the background at low x. The results complement our previous measurements and the two sets are consistent in the overlap region. No significant spin effects are found in the newly explored region. © 1999 The American Physical Society.
TL;DR: Correcting subtle but significant errors in the relaxation equations is shown to be significant, not only for transverse and longitudinal relaxation in aqueous superparamagnetic colloids, where the "Gueron" effect is known to be important, but even in some cases forTransverse paramagnetic relaxation.
TL;DR: In this paper, the pma-gusA genes were all expressed in root, stem, leaf and flower organs, but each in a cell-type specific manner, and their expression in these organs was confirmed at the protein level using subfamily-specific antibodies.
Abstract: The plasma membrane H+-ATPase couples ATP hydrolysis to proton transport, thereby establishing the driving force for solute transport across the plasma membrane. In Nicotiana plumbaginifolia, this enzyme is encoded by at least nine pma (plasma membrane H+-ATPase) genes. Four of these are classified into two gene subfamilies, pma1-2-3 and pma4, which are the most highly expressed in plant species. We have isolated genomic clones for pma2 and pma4. Mapping of their transcript 5' end revealed the presence of a long leader that contained small open reading frames, regulatory features typical of other pma genes. The gusA reporter gene was then used to determine the expression of pma2, pma3 and pma4 in N. tabacum. These data, together with those obtained previously for pma1, led to the following conclusions. (i) The four pma-gusA genes were all expressed in root, stem, leaf and flower organs, but each in a cell-type specific manner. Expression in these organs was confirmed at the protein level, using subfamily-specific antibodies. (ii) pma4-gusA was expressed in many cell types and notably in root hair and epidermis, in companion cells, and in guard cells, indicating that in N. plumbaginifolia the same H+-ATPase isoform might be involved in mineral nutrition, phloem loading and control of stomata aperture. (iii) The second gene subfamily is composed, in N. plumbaginifolia, of a single gene (pma4) with a wide expression pattern and, in Arabidopsis thaliana, of three genes (aha1, aha2, aha3), at least two of them having a more restrictive expression pattern. (iv) Some cell types expressed pma2 and pma4 at the same time, which encode H+-ATPases with different enzymatic properties.
TL;DR: In this paper, the decay rate of the ground state Bc meson was investigated under the relativistic constituent quark model formulated on the light front (LF) and the exclusive semileptonic and non-leptonic (NL) beauty and charm decays of the B c meson were described through vector and axial hadronic form factors.
TL;DR: In this paper, the authors investigated the geometry and the nature of optically allowed transitions in neutral and charged phenylene-based oligomers by means of Hartree-Fock calculations and showed that two subgap absorption features appear in short oligomers carrying a single charge (polaron), whereas a single intense peak is observed in the presence of two charges (bipolaron).
Abstract: We have investigated the geometry and the nature of optically allowed transitions in neutral and charged phenylene-based oligomers by means of Hartree-Fock calculations. Geometry optimizations are performed using the semiempirical Austin Model 1 (AM1) method for oligomers containing from two $(2P)$ to twelve $(12P)$ benzene rings. The transition energies and related intensities of the optical-absorption spectra are calculated by means of the intermediate neglect of differential overlap Hamiltonian that is combined with a single configuration interaction technique in order to include electron correlation effects in the description of the excited states. The calculations show that two subgap absorption features appear in short oligomers carrying a single charge (polaron), whereas a single intense peak is observed in the presence of two charges (bipolaron). These results are consistent with a wide range of experimental and theoretical data obtained for various conjugated oligomers. Interestingly, the appearance of a second subgap feature is predicted in the spectra of long doubly oxidized chains as well as for chains supporting interacting bipolarons.
TL;DR: In this article, a relativistic multiconfiguration Dirac-Fock approach has been used for calculating the ab initio values of the ionization energies, and analytical expressions for expressing the differences between the theoretical data and the compiled results available along the different sequences.
TL;DR: In this article, the ground state energies and geometries have been determined at the DFT/B3LYP level for different model compounds such as ribose, dimethyl phosphate, uridine, cytidine, 3‘-methyl phosphate−uridine, and 5‘ -methyl phosphate −uridine as a function of the most prominent conformations adopted by each of them.
Abstract: Ground state energies and geometries have been determined at the DFT/B3LYP level for different model compounds such as ribose, dimethyl phosphate, uridine, cytidine, 3‘-methyl phosphate−uridine, and 5‘-methyl phosphate−uridine as a function of the most prominent conformations adopted by each of them. The counterion used for neutralizing the phosphate negative charge was an ammonium ion (NH4+). This systematic study allowed us to analyze the stability of a ribonucleotide (base+ribose+phosphate) which is the chemical repeating unit of RNA. In the dimethyl phosphate model, the lowest energy corresponds to the gauche--gauche- conformation, as also predicted by previous calculations on this motif at different theoretical levels. In the ribose model, the C2‘-endo (S-type) conformer has a lower energy than the C3‘-endo (N-type) one. When a pyrimidine base (uracil or cytosine) is added to the ribose to form a ribonucleoside, the electronic energies of the three optimized conformers with the C3‘-endo and C2‘-endo ...
TL;DR: In this paper, infrared and collinear safe event shape distributions and their mean values are determined using the data taken at five different centre of mass energies above MZ with the DELPHI detector at LEP from the event shapes, the strong coupling αs is extracted in View the MathML source(αs2), NLLA and a combined scheme using hadronisation corrections evaluated with fragmentation model generators as well as using an analytical power ansatz
TL;DR: Introduction of amino acid substitutions which are phosphoserine mimetics at positions 300 and 301 restored the ability of a phosphorylation-defective Tax mutant to form nuclear bodies and to activate gene expression.
Abstract: The Tax transactivator protein of human T-cell leukemia virus type 1 (HTLV-1) plays a central role in the activation of viral gene expression. In addition, Tax is capable of activating the expression of specific cellular genes and is involved in the transformation of T-lymphocytes resulting in the development of adult T-cell leukemia. Tax is a phosphoprotein that colocalizes in nuclear bodies with RNA polymerase II, splicing complexes, and specific transcription factors including members of the ATF/CREB and NF-κB families. In this study, we identified adjacent serine residues at positions 300 and 301 in the carboxy terminus of Tax as the major sites for phosphorylation. Phosphorylation of at least one of these serine residues is required for Tax localization in nuclear bodies and for Tax-mediated activation of gene expression via both the ATF/CREB and NF-κB pathways. Introduction of amino acid substitutions which are phosphoserine mimetics at positions 300 and 301 restored the ability of a phosphorylation-defective Tax mutant to form nuclear bodies and to activate gene expression. These studies define sites for regulatory phosphorylation events in Tax which are critical for its ability to activate gene transcription.
TL;DR: In this paper, the authors evaluated the potential of T(2)-weighted, steady-state susceptibility-enhanced contrast magnetic resonance imaging (MRI), to characterize brain tumor heterogeneity and tumor vascularization.
Abstract: The aim of this work was to evaluate the potential of T(2)-weighted, steady-state susceptibility-enhanced contrast magnetic resonance imaging (MRI), to characterize brain tumor heterogeneity and tumor vascularization In vivo T(2)-weighted MRI experiments were carried out on normal rats (n = 11) and rats bearing C6 glioma (n = 17), before and after the injection of a remanent superparamagnetic contrast agent The DeltaR(2) variations of the transverse relaxation rate due to the injection of the contrast agent were used to generate relative cerebral blood volume (CBV) maps Contrast enhancement of the tumor was shown to reflect tissue vascularization rather than leakage of the blood-brain barrier The quantitative results clearly show the heterogeneity of tumor vascularization and reveal a high vessel density in the peripheral area (CBV(per) approximately 172 +/- 23 sec(-1)) and a low vessel density in the central area of the tumor (CBV(cen) approximately 25 +/- 05 sec(-1)) Magn Reson Med 42:754-761, 1999
TL;DR: Using molecular dynamics, it was shown that the equilibrium contact angle of a sessile drop placed on a heterogeneous substrate follows Cassie's law as discussed by the authors, and the dynamics of the associated spreading is analyzed with the molecular kinetic theory.
Abstract: Using molecular dynamics, it is shown that the equilibrium contact angle of a sessile drop placed on a heterogeneous substrate follows Cassie's law [Discuss. Faraday Soc. 57, 5041 (1952)]. The dynamics of the associated spreading is analyzed with the molecular kinetic theory. We show that the corresponding molecular parameters vary highly nonlinearly with the relative concentration of the heterogeneities. A model to explain this behavior is proposed. It is predicted that small quantities of wettable heterogeneities on a nonwettable substrate will change the spreading dynamics drastically.
11 Nov 1999-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: The SMC target system with two cells of opposite polarizations, each cell 65 cm long and 5 cm in diameter, constitutes the largest polarized target system ever built and facilitates accurate spin asymmetry measurements.
Abstract: The polarized target of the Spin Muon Collaboration at CERN was used for deep inelastic muon scattering experiments during 1993–1996 with a polarized muon beam to investigate the spin structure of the nucleon. Most of the experiments were carried out with longitudinal target polarization and 190 GeV muons, and some were done with transverse polarization and 100 GeV muons. Protons as well as deuterons were polarized by dynamic nuclear polarization (DNP) in three kinds of solid materials — butanol, ammonia, and deuterated butanol — with maximum degrees of polarization of 94%, 91% and 60%, respectively. Considerable attention was paid to the accuracies of the NMR polarization measurements and their analyses, the accuracies achieved were between 2.0% and 3.2%. The SMC target system with two cells of opposite polarizations, each cell 65 cm long and 5 cm in diameter, constitutes the largest polarized target system ever built and facilitates accurate spin asymmetry measurements. The design considerations, construction and performance of the target are reviewed.
TL;DR: In this article, the electronic and geometric properties of phenylene-based π-conjugated materials have been investigated, especially in light-emitting diodes, displays, and lasers.
TL;DR: In this paper, a detailed comparison of Relativistic Hartree-Fock calculations with recent laser lifetime measurements in Tm II was made, and it was shown that Cowan's code is adequate also for providing accurate radiative data in heavy ions and particularly in the astrophysically important singly ionized lanthanides provided configuration interaction and core-polarization effects are consistently taken into account in the adopted physical model.
Abstract: From a detailed comparison of Relativistic Hartree-Fock calculations with recent laser lifetime measurements in Tm II, it is shown that Cowan’s code, which has been widely used in the past for atomic structure calculations in light elements, is adequate also for providing accurate radiative data in heavy ions and particularly in the astrophysically important singly ionized lanthanides provided configuration interaction and core-polarization effects are consistently taken into account in the adopted physical model.
TL;DR: In this paper, a relativistic Hartree-Fock calculation, taking configuration-interaction and polarization effects into account, has been combined with a least-squares optimization procedure of the Slater and spin-orbit integrals in order to test the ability of this approach to correctly predict radiative properties of the group-IV elements.
Abstract: Using time-resolved UV laser-induced fluorescence from a laser-produced plasma, natural radiative lifetimes have been measured for 21 levels of Ge I belonging to the odd-parity $4p4d,4p5d,$ and $4p6s$ configurations. Stimulated Brillouin scattering in water has allowed us to compress Nd:YAG laser pulses pumping a dye laser (where YAG denotes yttrium aluminum garnet), thus yielding 1-ns tunable laser pulses to enable accurate measurements of short lifetimes. Branching ratios of Ge I have been measured by inductively coupled plasma emission spectrometry, the intensity calibration being performed by means of Ar lines emitted by a hollow-cathode lamp. The experimental lifetimes and branching ratios have been combined in order to provide a set of accurate transition probabilities for the $4p\ensuremath{-}5s$ and $4p\ensuremath{-}4d$ transitions. A relativistic Hartree-Fock calculation, taking configuration-interaction and polarization effects into account, has been combined with a least-squares optimization procedure of the Slater and spin-orbit integrals in order to test the ability of this approach to correctly predict radiative properties of the group-IV elements. Good agreement between experimental and theoretical transition probability values has been achieved for most of the transitions considered.
TL;DR: In this article, the minimal length uncertainty principle of Kemf, Mangano and Mann (KMM) is applied to describe the modes and wave packets of Hawking particles evaporated from a black hole, and the trans-Planckian problem is successfully confronted in that the Hawking particle no longer hugs the horizon at arbitrarily close distances.
Abstract: The minimal length uncertainty principle of Kemf, Mangano and Mann (KMM), as derived from a mutilated quantum commutator between coordinate and momentum, is applied to describe the modes and wave packets of Hawking particles evaporated from a black hole. The trans-Planckian problem is successfully confronted in that the Hawking particle no longer hugs the horizon at arbitrarily close distances. Rather the mode of Schwarzschild frequency \ensuremath{\omega} deviates from the conventional trajectory when the coordinate $r$ is given by $|r\ensuremath{-}2M|\ensuremath{\simeq}{\ensuremath{\beta}}_{H}\ensuremath{\omega}/2\ensuremath{\pi}$ in units of the nonlocal distance legislated into the uncertainty relation. Wave packets straddle the horizon and spread out to fill the whole nonlocal region. The charge carried by the packet (in the sense of the amount of ``stuff'' carried by the Klein-Gordon field) is not conserved in the non-local region and rapidly decreases to zero as time decreases. Read in the forward temporal direction, the non-local region thus is the seat of production of the Hawking particle and its partner. The KMM model was inspired by string theory for which the mutilated commutator has been proposed to describe an effective theory of high momentum scattering of zero mass modes. It is here interpreted in terms of dissipation which gives rise to the Hawking particle into a reservoir of other modes (of as yet unknown origin). On this basis it is conjectured that the Bekenstein-Hawking entropy finds its origin in the fluctuations of fields extending over the nonlocal region.
TL;DR: In this article, it was shown that at the molecular level, the mechanism of spreading can be viewed as a competition between a surface tension driving force and friction between the liquid and solid atoms.
TL;DR: In this paper, the spreading of low molecular weight silicon oils (PDMS) on heterogeneous substrates has been studied by spectroscopic ellipsometry, using different grafting times, they produced partially OTS-grafts.
Abstract: The spreading of low molecular weight silicon oils (PDMS) on heterogeneous substrates has been studied by spectroscopic ellipsometry. Using different grafting times, we produced partially OTS-graft...
TL;DR: In this paper, the relativistic Hartree-Fock approach for atomic structure calculations in the 6p1/2 and 6p3/2 levels of the La III ion is compared with the HartreeFock-based approach for the Lu III ion.
Abstract: New radiative lifetime measurements performed with time-resolved laser spectroscopy for the 6p1/2 and 6p3/2 levels of La III provide a unique opportunity for testing the adequacy of the relativistic Hartree-Fock approach for atomic structure calculations in this ion. As a consequence of the comparison, an extensive set of accurate f-values is provided for many La III and Lu III UV and visible transitions of astrophysical interest.
TL;DR: In this article, the surface coverage of partially n-octadecyltrichlorosilane (OTS) grafted silicon wafer was estimated from dynamical wetting measurements.
Abstract: We show how the surface coverage of partially n-octadecyltrichlorosilane (OTS) grafted silicon wafer can be estimated from dynamical wetting measurements. By use of the molecular kinetic theory of wetting, values of the effective jump frequency are determined from the relaxation of the contact angle of branched alkane droplets on such heterogeneous substrates. These jump frequencies are correlated to the OTS thickness measured by ellipsometry. The surface composition can then be calculated, indicating the strong influence of the transition from the expanded to the condensed liquid phase on the wetting properties of the substrate.