Showing papers by "Aix-Marseille University published in 1995"
15 Jun 1995-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: The performance of the ALEPH detector at the LEP e+e− collider is reviewed in this paper, where the accuracy of the tracking detectors to measure the impact parameter and momentum of charged tracks is specified.
Abstract: The performance of the ALEPH detector at the LEP e+e− collider is reviewed. The accuracy of the tracking detectors to measure the impact parameter and momentum of charged tracks is specified. Calorimeters are used to measure photons and neutral hadrons, and the accuracy obtained in energy and angle is given. An essential property of the detector is its ability to identify particles; the performance in identification of electrons, muons, neutrinos (from missing energy), charged hadrons, π0's and V0's is described.
356 citations
TL;DR: A search for its function is directed to a number of inductive epithelial-mesenchymal interactions during craniofacial development and to stomach organogenesis.
160 citations
TL;DR: The best results of patellofemoral arthroplasty were obtained in osteoarthritis after patella dislocation or patellar fracture, and this group must be restricted to lesions of the patell ofemoral joint in a knee in neutral axis evaluated preoperatively on full standing and stress radiographs.
Abstract: Indications for patellofemoral arthroplasty were studied based on a 2- to 10-year followup review. Of 183 patellofemoral prostheses implanted between 1980 and 1990, 104 were associated with unicompartmental arthroplasty, and 79 were implanted alone. Thirteen patients were lost to followup. The results of 66 patellofemoral arthroplasties are reported at an average followup of 66 months. The mean age of the patients at surgery was 57 years. Underlying causes of the osteoarthritis included patellar dislocation or dysplasia (22), patellar fracture (20), and primary osteoarthritis (24). A metallic femoral groove was associated with a polyethylene patella with no metal backing. Two (9%) prostheses were revised in the dysplasia group, 1 (5%) in the posttraumatic group, and 7 (29%) in the primary osteoarthritis group. In this latter group, the indications of patellofemoral arthroplasty must be restricted to lesions of the patellofemoral joint in a knee in neutral axis evaluated preoperatively on full standing and stress radiographs. The best results of patellofemoral arthroplasty were obtained in osteoarthritis after patellar dislocation or patellar fracture.
152 citations
TL;DR: Results suggest that a decrease in dopamine function at striatal level severely disrupts performance of a conditioned reaction time task, and may be related to similar events in Parkinson's disease.
Abstract: The present study examined the ability of rats subjected to bilateral 6-hydroxydopamine lesions of the terminal area of the nigrostriatal dopamine system to perform a prelearned reaction time task. This lesion model, the induction of a partial dopamine denervation of the striatum (74% depletion of dopamine striatal tissue content) with a retrograde degeneration of dopamine cell bodies in the substantia nigra, sparing the mesolimbic dopaminergic pathway, closely approximates the neuronal degeneration observed in human idiopathic Parkinson's disease. Rats were trained previously to release a lever, within a reaction time limit, after the presentation of a visual cue through reinforcement with food pellets. The onset of the light stimulus varied randomly after an unpredictable delay period of 0.25–1.0 s. Rats with dopaminergic lesions showed moderate to extensive performance deficits which were not compensated for the five postoperative weeks. More than half of the lesioned animals (64%) showed severe deficits, characterized by a concomitant increase in the number of anticipated (premature release of the lever before the visual cue) and delayed responses (lever release after the reaction time limit) with shortened reaction times in some cases. A smaller proportion (36%) of lesioned animals exhibited mild impairment of performance with a large increase in delayed responses and lengthening of reaction times but with no change in the number of anticipated responses. Asymmetric lesions had no effect on the reaction time performance. Examination of tyrosine hydroxylase immunostaining revealed that in the most impaired animals dopamine depletion was extensive in the medial striatum, whereas it was restricted to the dorsolateral striatum in the least impaired animals. Results suggest that a decrease in dopamine function at striatal level severely disrupts performance of a conditioned reaction time task. A partial dopamine depletion in the dorsolateral striatum induces motor initiation deficits (i.e. increases delayed response only). Larger striatal dopamine depletion may produce both motor and cognitive deficits (decrease in attentional control over response output and/or disruption of stimulus-response associations) that could be related to similar events in Parkinson's disease.
98 citations
TL;DR: In this paper, the authors conclude that cosmic ray muon-induced reactions are the most likely mechanism, and such reactions lead to 1% to 3% of 10Be production at the surface.
Abstract: Distributions of 10Be in vein quartz from a lateritic weathering profile from the Congo provide evidence for significant in situ production of 10Be by reactions other than neutron-induced spallation. After consideration of geomorphological and nuclear processes which might contribute to the observed depth variability, we conclude that cosmic ray muon-induced reactions are the most likely mechanism, and that such reactions lead to 1% to 3% of 10Be production at the surface. This small muon-induced component has only minor implications for the use of 10Be for quantification of exposure histories of surficial rocks. Nevertheless, the muogenic component has the potential to expand the utility of cosmogenic nuclides in examination of surficial processes, overcoming some of the limitations associated with the use of the neutron-produced component.
95 citations
TL;DR: In this paper, self-diffusion coefficients of undoped α-alumina in the lattice, sub-boundaries and grain boundaries were determined in the same materials and under the same experimental conditions.
Abstract: In many cases, alumina scales are assumed to grow predominantly by oxygen diffusion, but some authors have found that the growth can be controlled by aluminium diffusion. These mechanisms can be modified by active elements. The problem with alumina is that there is a lack of data about self-diffusion coefficients, and, due to the stoichiometry of alumina, diffusion data correspond to an extrinsic diffusion mechanism so that it is not possible to compare oxygen and aluminium diffusion coefficients. In order to obtain information about the alumina scale growth mechanism, oxygen (18O) and aluminium (26Al) self-diffusion coefficients in Al2O3 were determined in the same materials and in the same experimental conditions, thus allowing a direct comparison. For both isotopes, bulk and sub-boundary diffusion coefficients were determined in single crystals of undoped alumina. Grain-boundary diffusion coefficients have been computed only for oxygen diffusion in polycrystals. Oxygen diffusion has been also studied for yttria-doped α-alumina in the lattice, sub-boundaries and grain boundaries. Oxygen and aluminium bulk diffusion coefficients are of the same order of magnitude. In the sub-boundaries, aluminium diffusion is slightly faster than oxygen diffusion. Yttria doping induces a slight increase of the oxygen bulk diffusion, but decreases the grain-boundary diffusion coefficients on account of segregation phenomena. These results are compared with the oxidation constants of alumina former alloys (alloys which develop an alumina scale by oxidation). It appears that neither lattice self-diffusion nor grain boundary self-diffusion can explain the growth rate of alumina scales. Such a situation is compared to the case of Cr2O3.
85 citations
TL;DR: In this paper, the W boson mass in W − ev decays was measured using 1 fb^-1 of data collected with the D0 detector during Run II of the Fermilab Tevatron collider.
Abstract: We present a measurement of the W boson mass in W -> ev decays using 1 fb^-1 of data collected with the D0 detector during Run II of the Fermilab Tevatron collider. With a sample of 499830 W -> ev candidate events, we measure M_W = 80.401 +- 0.043 GeV. This is the most precise measurement from a single experiment.
75 citations
TL;DR: In this paper, a series of 2,2′-substituted biphenyls and derivatives of them with either one or two fluoro, chloro, bromo, amino, nitro or methoxy substituents in the para positions were synthesized by polarimetry and dynamic gas chromatography.
Abstract: We have synthesized a series of 2,2′-substituted biphenyls and particularly derivatives of 2,2′-bis(trifluoromethyl)biphenyl (4) with either one or two fluoro, chloro, bromo, amino, nitro or methoxy substituents in the para positions for investigating the influence of these substituents on the rotational energy barrier of the biphenyls by polarimetry and dynamic gas chromatography (DGC). Axially chiral biphenyls with at least two bulky substituents in the ortho positions were separated by gas chromatography on selectively modified cyclodextrins. Due to competition between resolution and enantiomerization in the gas chromatographic column 2-tert-butyl-2′-isopropyl- (2), 2-isopropyl-2′-(trifluoromethyl)biphenyl (5), and some para-substituted derivatives of 4 show temperature-dependent interconversion profiles and coalescence phenomena in analogy to dynamic NMR studies. The accelerating effect on the rate of enantiomerization of electron-donating groups in the para positions and the decelerating effect of electron-accepting groups has been determined. Dynamic gas chromatography is shown to be a useful supplement to studies of thermal enantiomerization kinetics of optically enriched or separated compounds by polarimetry for the investigation of energy barriers of atropisomeric biphenyls.
73 citations
TL;DR: In this paper, a photoluminescence study was made on thin films of Si-SO2 nanoclusters prepared by reactive laser ablation of Si targets, and the spectra were measured at ambient temperature and at liquid nitrogen temperature using 400 and 230 nm excitation from a dye laser driven by an excimer laser.
70 citations
TL;DR: In this article, an experimental evidence for the existence of orbitally excited B meson states is presented in an analysis of the Bπ and B∗π distribution of View the MathML source using Z0 decay data taken with the DELPHI detector at LEP.
61 citations
TL;DR: In this article, the dependencies of lithium niobate lattice constants on stoichiometry and concentration of K and Mg dopants were investigated with the help of X-ray powder diffraction.
TL;DR: In this paper, a study of the production of strange octet and decuplet baryons in hadronic decays of the Z recorded by the DELPHI detector at LEP is presented.
Abstract: A study of the production of strange octet and decuplet baryons in hadronic decays of the Z recorded by the DELPHI detector at LEP is presented. This includes the first measurement of the∑± average multiplicity. The total and differential cross sections, the event topology and the baryon-antibaryon correlations are compared with current hadronization models.
Journal Article•
TL;DR: The precise localization and YAC cloning of the core of the amplicon will allow to isolate a putative oncogene involved in mammary carcinogenesis as well as establish the following gene order: ADRB3-D8S105-FGFR1-ANK1-PLAT-POLB.
Abstract: Chromosomal region 8p11.2-p12 is consistently amplified in human breast cancer, We have constructed a 2.8 Mb YAC contig of this region, centered on the human Fibroblast Growth Factor Receptor 1 (FGRF1) locus and encompassing the Adrenergic beta 3 Receptor (ADRB3) focus. A smaller centromeric YAC contig spanning 1.4 Mb was also assembled, and included the Ankyrin 1 (ANK1) and Tissue-type Plasminogen Activator (FLAT) genes, Results from mapping of the contigs showed physical linkage of the ADRB3 and FGFR1 genes, which were colocalized within the same YAC clone and separated by about 900 kb, FGFR1 being in centromeric position, It also showed physical linkage of ANK1 and FLAT genes, which appear to be separated by a maximum of 700 kb. In parallel, several loci were mapped according to their amplification status in a large panel of breast tumor samples. The overall amplification pattern suggested a continuous amplicon with a core around FGFR1. Data from both the detailed physical map and the amplification status allowed to establish the following gene order, from telomere to centromere: ADRB3-D8S105-FGFR1-ANK1-PLAT-POLB. The precise localization and YAC cloning of the core of the amplicon will allow to isolate a putative oncogene involved in mammary carcinogenesis.
TL;DR: In this article, the average multiplicities of Ks0, K±, p(p), Λ(View the MathML source) and of charged particles in bb events have been measured, distinguishing the component from fragmentation and the component coming from the decay of b-hadrons.
TL;DR: In this paper, a transect across the SE Greenland seaward-dipping reflector sequence was carried out to investigate the evolution in deep crustal magma reservoirs, with a dwindling supply of primitive magma and an increasing role of crustal contamination, can account for the variation.
Abstract: ODP Leg 152 drilled a transect across the SE Greenland seaward-dipping reflector sequence. The earliest, and most landward, lava flows (Hole 917A, Lower and Middle Series) represent a pre-break-up continental sequence showing an overall variation from olivine basalt to dacite. Evolution in deep crustal magma reservoirs, with a dwindling supply of primitive magma and an increasing role of crustal contamination, can account for the variation. Eruption of picrite and olivine basalt magmas (917A, Upper Series) marked a dramatic change in the style of magmatism to one of unrestrained passage of primitive magma from the mantle to the surface during the final phase of break-up. The younger parts of the seaward-dipping reflector sequence (915A and 918D) comprise compositionally uniform basalt (7.6 ± 0.8% MgO), suggesting that an effective magmatic filtering system was established, soon after break-up, in magma chambers associated with a spreading axis. The continental to oceanic magmatic transition is marked by clear changes in composition. The continental magmas had a garnet lherzolite source (indicated by low Y/Zr) and were contaminated with continental lithospheric mantle and crust (high Ba/Zr). The majority of the break-up and oceanic volcanic rocks show no evidence for lithospheric contamination (low Ba/Zr) and appear to have had a source in progressively shallower, depleted (?MORB-source) asthenosphere (increasing Y/Zr, low Nb/Zr).
TL;DR: The results are discussed in terms of their implications for the separation of visual and biomechanical factors influencing visuo-postural control.
Abstract: How does the spatio-temporal structure of an oscillating radial optical flow affect postural stability? In order to investigate this problem, two different types of stimulus pattern were presented to human subjects. These stimuli were generated either with a constant spatial frequency or with a spatial frequency gradient providing monocular depth cues. When the stimulation was set in motion, the gain response of the antero-posterior postural changes depended upon the oscillation frequency of the visual scene. The amplitude of the postural response did not change with the amplitude of the visual scene motion. The spatial orientation of the postural sway (major axis of sway) depended strictly and solely on the structure of the visual scene. In static conditions, depth information resulting from the presence of a spatial frequency gradient enhanced postural stability. When set in motion, a visual scene with a spatial frequency gradient induced an organization of postural sway in the direction of the visual motion. Considering visual dynamic cues, postural instability depended linearly both on the logarithm of the velocity and on the logarithm of the temporal frequency. A nonlinear relationship existed between the amplitude of the fore-aft postural sway at the driving frequency and the temporal frequency, with a peak around 2–4 Hz. These results are discussed in terms of their implications for the separation of visual and biomechanical factors influencing visuo-postural control.
TL;DR: These two locations of the disease, which are easily investigated by simple methods, can help in the diagnosis of this new type of diabetes secondary to 3243 mtDNA mutation, infraclinical muscular and ocular lesions are frequent.
Abstract: OBJECTIVE A point mutation in the mitochondrial genome has been identified as a cause of diabetes and deafness. We report two pedigrees with and A-to-G transition at nucleotide 3243 of mtDNA within the tRNALeu(UUR) gene and focus our investigations on other localizations of the anomaly, particularly muscle and retina. RESEARCH DESIGN AND METHODS Muscular localization has been studied in probands by invasive and noninvasive methods, including muscle biopsy (evaluation of the proportion of mutated mtDNA in comparison to blood cells, measurement of respiratory chain complex activities and histological and histochemical aspects) and 31 P-nuclear magnetic resonance (NMR) spectroscopy. Ophthalmic and angiographic examination of retina, electroretinography, and visual evoked potentials were performed in five subjects. RESULTS This mutation, previously described in patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS), was expressed more abundantly in muscle than in nucleated blood cells. This low expression in blood cells could hamper the diagnosis for some patients. In addition, despite poor clinical expression, muscle was found to be highly affected. Ragged red fibers and dystrophic mitochondria were observed in muscle biopsy. Histochemical assays showed decreased activity of respiratory chain complexes, and 31 P-NMR in vivo data further confirmed the defect of muscle oxidative processes. Exercise-induced lactate production was increased. Finally, in both families, an atypical “salt and pepper” pigmentary retinopathy was observed without consequences on visual acuity. CONCLUSIONS In diabetes secondary to 3243 mtDNA mutation, infraclinical muscular and ocular lesions are frequent. These two locations of the disease, which are easily investigated by simple methods, can help in the diagnosis of this new type of diabetes.
TL;DR: In this paper, the DELPHI detector was used to measure three-particle correlations in e+e− annihilations at LEP using data collected by the DelphI detector.
TL;DR: The nonrelativistic ``Dirac`` equation of Levy-Leblond is used to describe a spin-1/2 particle interacting with a Chern-Simons gauge field.
Abstract: The nonrelativistic ``Dirac`` equation of Levy-Leblond is used to describe a spin-1/2 particle interacting with a Chern-Simons gauge field. Static, purely magnetic, self-dual spinor vortices are constructed. The solution can be ``exported`` to a uniform magnetic background field.
TL;DR: An alternative, topological method is proposed that makes use of a phase-plane representation of the movement that supports the constant tau-dot strategy and suggests a softening spring description for a large part of the decelerative phase, followed by a final adjustment.
Abstract: Whether a subject uses a constant tau-dot strategy to decelerate a reach to grasp an object is typically determined by performing a linear regression of tau onto real time to contact. This method has the disadvantage of requiring an assumption (on the part of the experimenter) concerning the endpoint targeted by the subject. In the present contribution, an alternative, topological method is proposed that makes use of a phase-plane representation of the movement. In two experiments, experimentally obtained movement trajectories were evaluated, using this new method, and the results were found to support the constant tau-dot strategy. At the same time, however, an alternative model, associated with dynamical systems theory, was demonstrated to fit the data even better. It is argued that the topology of the phase plane suggests a softening spring description for a large part of the decelerative phase, followed by a final adjustment. Deterioration of the functionality of the adjustment made in this latter phase was observed when visual information was not available during movement execution.
TL;DR: The enantiomers of rac-2,2′-diiodobiphenyl were separated by liquid chromatography on microcrystalline triacetylcellulose using a large separation factor α, and a suitable capacity factor k′(+) of this biphenyl allowed the racemate to be converted into 90% of enantiomerically pure (-)-2, 2′- diiodob Piphenyl and 10%.
TL;DR: In this paper, a reagent for the determination of enantiomeric excess of chiral diols and diamines with C2 symmetry is described, which can be easily prepared from PCl3 and (1R,2S,5R)-(−)-menthol.
Abstract: A new reagent for the determination of enantiomeric excess of chiral diols and diamines with C2 symmetry is described. This derivatizing agent easily prepared from PCl3 and (1R,2S,5R)-(−)-menthol allows an accurate analysis of the diastereomeric derivatives by 31P NMR spectroscopy.
TL;DR: In this paper, the growth of small supported rhodium particles on different substrates (mica, Al2O3, NaCl) was investigated and it was observed that the particle density, the mean size and the size dispersion of Rh particles are controlled by either atom diffusion or by particle migration on the substrate.
TL;DR: A comparative study of the size distribution of four fish species was performed on three geomorphological zones (back reef, inner reef flat and outer reef flat) on two comparable fringing reef areas (disturbed and non-disturbed) of Reunion Island, S.W. Indian Ocean.
Abstract: A comparative study of the size distribution of four fish species was performed on three geomorphological zones (back reef, inner reef flat and outer reef flat) on two comparable fringing reef areas (disturbed and non-disturbed) of Reunion Island, S.W. Indian Ocean. The species chosen Chaetodon trifasciatus, Dascyllus aruanus, Stethojulis albovittata and Ctenochaetus striatus were selected both for their abundance and their diverse diets. The method used is based on the estimation of fish size directly underwater by comparison to a graduated table, i.e. photographs of the species for which different size-classes were previously determined. For the two areas, the size of fishes increases from the back reef zone to the outer reef flat, except for D. aruanus which is not present in sufficient numbers on the outer reef flat to allow a statistical analysis. This suggests the existence of a nursery zone in the back reef from which these species might colonize the reef flat. On the back reef zone and the inner reef flat, there is a significant difference in the size distribution of fishes between the disturbed and non-disturbed areas, except for S. albovittata. The number of juveniles is significantly lower in the disturbed area, probably due to environmental perturbations.
TL;DR: In this paper, a sample of Z0→τ+τ− events observed in the DELPHI detector at LEP in 1991 and 1992 is analysed to measure the τ polarisation in the exclusive decay channels evvˉ, μvvˉ, πν, ρν and a1ν.
Abstract: A sample of Z0→τ+τ− events observed in the DELPHI detector at LEP in 1991 and 1992 is analysed to measure the τ polarisation in the exclusive decay channels evvˉ , μvvˉ , πν, ρν and a1ν. The τ polarisation is also measured with an inclusive hadronic analysis which benefits from a higher efficiency and a better systematic precision than the use of the exclusive decay modes. The results have been combined with those published on the 1990 data. A measurement of the τ polarisation as a function of production angle yields the values for the mean τ polarisation 〈P〉τ=−0.148±0.022 and for the Z0 polarisationP Z=−0.136±0.027. These results are used to determine the ratio of vector to axial-vector effective couplings for taus vˉτ/aˉτ=0.074±0.011 , and for electrons vˉe/aˉe=0.068±0.014 , compatible with e-τ universality. With the assumption of lepton universality, the ratio of vector to axial-vector effective couplings for leptons vˉl/aˉl=0.072±0.008 is obtained, implying a value of the effective weak mixing angle sin2θ eff lept =0.2320±0.0021.183-201
TL;DR: Efficacy of the special extract without the terpenes was comparable to that of the total extract, indicating that the nonterpenic fraction was the most active biochemical constituent in this experimental model of central nervous system (CNS) plasticity.
Abstract: Locomotor balance recovery after unilateral vestibular neurectomy has been found strongly accelerated in the cat when the animals received a postoperative treatment with Ginkgo biloba Extract (EGb 761:50 mg/kg/d, i.p.), a result due to the improvement of plasticity mechanisms involved in vestibular compensation. The aim of this study was to determine which of the two main biochemical components (terpenes vs. flavonoids) contained in the extract was the most active in the recovery process, to test the influence of the route of administration, and to look for dose-dependent effects. Experiments were performed in six experimental groups of cats that were compared with each other and with three control groups. Comparisons were done on the recovery profile and time course of equilibrium function restoration, as quantified by the rotating beam test. Four experimental groups were treated with the standardized extract EGb 761 given orally (p.o.:2 groups; 40 mg and 80 mg/kg) or intraperitoneally (i.p.: 2 groups; 50 mg and 25 mg/kg), whereas the two others received only a special extract that did not contain the terpenes (i.p. administration: 25 mg and 10 mg/kg). Treatment was always given until complete recovery of locomotor balance function. The control groups received either no treatment (untreated cats), an oral vehicle (placebo cats), or a sham i.p. injection (sham cats). Results showed that locomotor balance recovery was significantly improved in all the experimental groups as compared to the control groups of cats, which recovered similarly and more slowly. Efficacy of the special extract without the terpenes was comparable to that of the total extract, indicating that the nonterpenic fraction was the most active biochemical constituent in this experimental model of central nervous system (CNS) plasticity. Pharmacological activity of the extract was also significantly better when given i.p. as compared to the p.o. route of administration, and dose-dependent effects were evidenced with the i.p. administration of the special extract without the terpenes, with a lower efficacy for the lowest dose (10 mg/kg). These data confirm that EGb 761 treatment serves as useful therapy in supporting brain functional recovery in this animal model of vestibular compensation and lead to a more precise understanding of the biochemical component that is active in this recovery process.
TL;DR: In this paper, a measurement of the Δ++(1232) inclusive production in hadronic decays of the Z at LEP is presented, based on 1.3 million hadronic events collected by the DELPHI detector in the 1994 LEP running period.
TL;DR: It is observed that a short 1731 Gag polypeptide is associated to the cell nuclei, and consistent with the nuclear localization signal present in the Gag sequence, the largest, likely post‐translationaly‐modified Gagpolypeptides are gathered into cytoplasmic virus‐like particles.
01 Jan 1995
TL;DR: In this paper, the importance of the service de distribution physique dans the strategies de referencement deployees actuellement par les detaillants vis-a-vis de leurs marches amont.
Abstract: Les relations producteurs-distributeurs sont, en France, un sujet d’actualite. Si de nombreux travaux les ont etudiees sous l’angle singulier de la negociation commerciale, il n’en va pas de meme au niveau de la logistique. L’article souhaite oeuvrer dans cette direction en s’interrogeant sur l’importance reelle du service de distribution physique dans les strategies de referencement deployees actuellement par les detaillants vis-a-vis de leurs marches amont.
TL;DR: For the first time, multihadronic production from single tagged γγ collisions has been studied, where one of the scattered leptons was tagged at very low virtual photon absolute mass squared (〈Q2〉 = 0.06 (GeV/c2)2) as mentioned in this paper.