Showing papers by "University of Grenoble published in 1996"

Direct Determination of Lead Speciation in Contaminated Soils by EXAFS Spectroscopy

Abstract: Direct determination of the chemical form of trace metals in soils still remains a challenge for instrumental analytical techniques. This paper examines the potential of EXAFS spectroscopy to speciate and quantify the form of trace metals in the solid fraction of soil materials using lead as a case study. Three soils contaminated by different sorts of industrial activities, including the synthesis of lead organometallics for gasoline antiknocks, Pb−Zn smelting, and recycling of lead acid battery, were investigated. In soil contaminated by alkyl-tetravalent lead compounds, lead was found to be divalent and complexed to salicylate and catechol-type functional groups of humic substances. Lead sulfate and silica-bound lead are the predominant forms in the vicinity of the battery reclamation area. Near the smelter, lead was found to be divalent and coordinated to O,OH ligands. It is present in several chemical forms, which prevented them from being identified individually. The multiplicity of lead species in s...

Control, Interdependence and Power: Understanding Social Cognition in Its Social Context

Abstract: A theory of control in interdependence and power relations is supported by a program of laboratory research Control needs are basic and predict information-seeking in social relationships Those without social power typically seek the most diagnostic information, making individuation more likely Those who do have social power seek less diagnostic information about others and are vulnerable to stereotyping them Moreover, feelings of control not only reflect individual power positions but also group power positions Remaining challenges include the impact of outcome expectations on information-seeking and continuing to remedy the power lacuna in social psychology

Performance of the DELPHI detector

Abstract: DELPHI (DEtector with Lepton, Photon and Hadron Identification) is a detector for e^+e^- physics, designed to provide high granularity over a 4\pi solid angle, allowing an effective particle identification. It has been operating at the LEP (Large Electron-Positron) collider at CERN since 1989. This article reviews its performance.

Three-dimensional reconstruction of painted human interphase chromosomes: active and inactive X chromosome territories have similar volumes but differ in shape and surface structure.

Abstract: This study provides a three-dimensional (3D) analysis of differences between the 3D morphology of active and inactive human X interphase chromosomes (Xa and Xi territories). Chromosome territories were painted in formaldehyde-fixed, three-dimensionally intact human diploid female amniotic fluid cell nuclei (46, XX) with X-specific whole chromosome compositive probes. The colocalization of a 4,6-diamidino-2-phenylindole dihydrochloride-stained Barr body with one of the two painted X territories allowed the unequivocal discrimination of the inactive X from its active counterpart. Light optical serial sections were obtained with a confocal laser scanning microscope. 3D-reconstructed Xa territories revealed a flatter shape and exhibited a larger and more irregular surface when compared to the apparently smoother surface and rounder shape of Xi territories. The relationship between territory surface and volume was quantified by the determination of a dimensionless roundness factor (RF). RF and surface area measurements showed a highly significant difference between Xa and Xi territories (P 0.1). For comparison with an autosome of similar DNA content, chromosome 7 territories were additionally painted. The 3D morphology of the chromosome 7 territories was similar to the Xa territory but differed strongly from the Xi territory with respect to RF and surface area (P < 0.001).

Abnormal involuntary movements induced by subthalamic nucleus stimulation in parkinsonian patients.

Abstract: Chronic electrical subthalamic nucleus (STN) stimulation is under investigation for alleviating parkinsonian symptoms. STN alterations may carry the risk of provoking abnormal involuntary movements (AIMs). We took advantage of the reversibility of the stimulation technique to assess the possibility of inducing AIMs, using different electrical variables with or without concomitant levodopa intake. Above a given threshold voltage, stimulation could induce contralateral distal mobile AIMs or hemiballism in the off-drug condition in two patients. AIMs occurred after a latency that varied from a few minutes up to several hours after switching on the stimulator. Hemiballism immediately disappeared upon switching off the stimulator. In these patients, levodopa had never provoked that type of AIMs before surgery. Levodopa-induced AIMs were not modified by electrical stimulation, but off-phase dystonia disappeared in one patient. Stimulation of the STN induced AIMs that resembled both those observed following spontaneous lesions of the STN and levodopa-induced diphasic AIMs in parkinsonian patients. As electrical stimulation provoked AIMs and antiparkinsonian benefit occurred with different electrical variables and different timing, the mechanisms responsible for these two effects could be distinct.

A glass box approach to adaptive hypermedia

Abstract: Utilising adaptive interface techniques in the design of systems introduces certain risks. An adaptive interface is not static, but will actively adapt to the perceived needs of the user. Unless carefully designed, these changes may lead to an unpredictable, obscure and uncontrollable interface. Therefore the design of adaptive interfaces must ensure that users can inspect the adaptivity mechanisms, and control their results. One way to do this is to rely on the user's understanding of the application and the domain, and relate the adaptivity mechanisms to domain-specific concepts. We present an example of an adaptive hypertext help system POP, which is being built according to these principles, and discuss the design considerations and empirical findings that lead to this design.

Nanoindentation investigation of the young's modulus of porous silicon

Abstract: Young’s modulus of porous silicon samples, with porosity ranging from 36% to 90%, is measured by the nanoindentation technique. The analysis of the nanoindentation data, including the specific problem linked with porous materials, is presented. The Young’s modulus values Ep thus obtained appear to be drastically dependent on the porosity and on the doping level (p or p+ type). The dependence of Ep versus the relative density (for a series of p+ type samples) is quadratic, in good agreement with the model of Gibson and Ashby developed for cellular materials. This also shows that highly porous silicon layers exhibit very low Young’s modulus (for a porosity of 90% it is about two orders of magnitude smaller than that of the nonporous material).

Tracheobronchial tree: three-dimensional spiral CT with bronchoscopic perspective.

Abstract: The purpose of this report is to describe an original 3D technique that permits bronchoscopic perspective simulations of the tracheobronchial tree on an affordable workstation. Software based on surface shading was developed to permit navigation through the central airways using spiral CT data. Multiplanar reformations are displayed simultaneously with the virtual bronchoscopy simulations to give information about tissues surrounding the airways. Two clinical examples are reported to illustrate the value of this advanced computer technique.

Increased incidence of hyperhaploid 24,XY spermatozoa detected by three-colour FISH in a 46,XY/47,XXY male

Abstract: Meiotic segregation of gonosomes from a 46,XY/47,XXY male was analysed by a three-colour fluorescence in situ hybridisation (FISH) procedure. This method allows the identification of hyperhaploid spermatozoa (with 24 chromosomes), diploid spermatozoa (with 46 chromosomes) and their meiotic origin (meiosis I or 11). Alpha satellite DNA probes specific for chromosomes X, Y and 1 were observed on 27,097 sperm nuclei. The proportions of X-and Y -bearing sperm were estimated to 52.78% and 43.88%, respectively. Disomy (24,XX, 24,YY, 24,X or Y,+1) and diploidy (46,XX, 46,YY, 46,XY) frequencies were close to those obtained from control sperm, whereas the frequency of hyperhaploid 24,XY spermatozoa (2.09%) was significantly increased compared with controls (0.36%). These results support the hypothesis that a few 47,XXY germ cells would be able to complete meiosis and to produce mature spermatozoa.

Toute variété magnifique est sphérique

Abstract: LetG be a (connected) reductive group (over C). An algebraicG-varietyX is called “wonderful”, if the following conditions are satisfied:X is (connected) smooth and complete;X containsr irreducible smoothG-invariant divisors having a non void transversal intersection;G has 2 r orbits inX. We show that wonderful varieties are necessarily spherical (i.e., they are almost homogeneous under any Borel subgroup ofG).

Study of the cracking of highly porous p+ type silicon during drying

Abstract: The origin of the cracking of highly porous silicon layers during drying is investigated. Optical and scanning electron microscopy observation allow us to observe the cracking occurrence. In situ x‐ray diffraction experiments, under controlled vapor pressure of pentane, reveal that large capillary stresses occur at a vapor pressure P* during the controlled drying. These stresses lead to the cracking of the highly porous layer, which occurs for samples thicker than a critical thickness hc. Taking into account the mechanical properties of the material, a model based on energy balance is presented. This model predicts a layer thickness hc of cracking occurrence, showing that hc varies as (1−p)3/γLV2 (where γLV is the surface tension of the drying liquid and p is the porosity). This model is in good agreement with experimental data obtained with two liquids, water, and pentane, which have very different surface tension and also for two different porosities.

Energy dependence of the differences between the quark and gluon jet fragmentation

Abstract: Three jet events arising from decays of the Z boson, collected by the DELPHI detector, were used to measure differences in quark and gluon fragmentation. Gluon jets were anti-tagged by identifying b quark jets. Unbiased quark jets came from events with two jets plus one photon. Quark and gluon jet properties in different energy ranges were compared for the first time within the same detector. Quark and gluon jets of nearly the same energy in symmetric three jet event topologies were also compared. Using three independent methods, the average value of the ratio of the mean charged multiplicities of gluon and quark jets is = 1.241 ± 0.015 (stat.) ± 0.025 (syst.). Gluon jets are broader and produce fragments with a softer energy spectrum than quark jets of equivalent energy. The string effect has been observed in fully symmetric three jet events. The measured ratio R_{gamma} of the charged particle flow in the qoverline{q} inter-jet region of the qar{q}g and qar{q}gamma samples agrees with the perturbative QCD expectation. The dependence of the mean charged multiplicity on the hadronic center-of-mass energy was analysed in photon plus n-jet events. The value for alpha_s(M_Z) determined from these data using a QCD prediction with corrections at leading and next-to-leading order is αs(MZ)= 0.116 ± 0.003 (stat.) ± 0.009 (syst.).

A longitudinal study of a harlequin infant presenting clinically as non-bullous congenital ichthyosiform erythroderma

Abstract: Over the past 8 years, we have followed a child born as a harlequin baby, who survived due to treatment with retinoids. His condition evolved clinically towards the erythrodermic form of lamellar ichthyosis (non-bullous congenital ichthyosiform erythroderma, NBCIE). According to ultrastructural and biochemical criteria, our patient originally presented with type II harlequin ichthyosis. Investigations showed an abnormal keratinosome structure and extrusion, a keratin pattern characteristic for epidermal hyperproliferation, and an absence of conversion of profilaggrin to filaggrin. Persisting keratinocyte hyperproliferation, associated with the presence of a dermal infiltrate, is in agreement with the present clinical picture of severe NBCIE. However, abnormal lamellar body production and defective filaggrin processing, which is not one of the diagnostic criteria of NBCIE, persist in the patient's skin. Further studies of the epidermal lipid composition, and of possible mutations of the keratinocyte transglutaminase gene performed on epidermal cell cultures of harlequin ichthyosis, will be necessary before type II harlequin ichthyosis can be accepted as an extremely severe form of NBCIE.

Chemical state of Cd in apatite phosphate ores as determined by EXAFS spectroscopy

Abstract: Abstract Natural apatites used in fertilizer industries often contain trace amounts of Cd, which may reach concentrations of several tens to a few hundred parts per million. Cd is not eliminated during the production of phosphate fertilizers, and its concentration in the final product can exceed environmental norms. Knowledge of the chemical state of Cd in apatite ores is a prerequisite for the design of technical processes of extraction. In the present study, Cd K-edge EXAFS spectroscopy was used to investigate the structural environment of Cd present in sedimentary apatite ores from West Africa. These apatites are fluorinated and contain goethite, quartz, and crandallite as ancillary phases detected by X-ray diffraction or EXAFS spectroscopy. Cd K-edge EXAFS spectra for two natural samples were analyzed and compared with those for Cd-containing reference minerals, including hydroxylapatite, goethite, otavite, and crandallite. A good spectral resemblance was observed between natural products and synthetic apatite containing small amounts of Cd. This spectral likeness indicates that the majority of Cd atoms are diluted in the apatitic framework and do not form Cd10(PO4)6(OH,F)2 clusters. This finding was confirmed by quantitative analysis of the EXAFS spectra, which indicated that Cd atoms are surrounded by nearest 0 atoms at 2.33 Å, next-nearest P atoms at ~3.53 Å, and a third-nearest shell of Ca atoms at ~4.02 Å. A comparison of these data with those obtained for synthetic apatites allowed us to assess that Cd occupies both Ca crystallographic sites with a slight preference for the Ca2 site.

Effective bounds for very ample line bundles

Abstract: Let \(L\) be an ample line bundle on a non singular projective\(n\) -fold \(X\). It is first shown that\(2K_X+mL\) is very ample for\(m\ge 2+{3n+1\choose n}\) . The proof develops an original idea of Y.T. Siu and is based on a combination of the Riemann-Roch theorem together with an improved Noetherian induction technique for the Nadel multiplier ideal sheaves. In the second part, an effective version of the big Matsusaka theorem is obtained, refining an earlier version of Y.T. Siu: there is an explicit polynomial bound\(m_0=m_0(L^n,L^{n-1}\cdot K_X)\) of degree\({}\le n3^n\) in the arguments, such that \(mL\) is very ample for\(m\ge m_0\) . The refinement is obtained through a new sharp upper bound for the dualizing sheaves of algebraic varieties embedded in projective space.

Management of simple snoring, upper airway resistance syndrome, and moderate sleep apnea syndrome.

Abstract: The spectrum of respiratory sleep disorders has been extended in the last years to include conditions that are less well defined than severe obstructive sleep apnea (OSA). Moderate OSA, snoring, and upper airway resistance syndrome (UARS) represent three conditions in which there are still unresolved pathophysiological, epidemiological, and clinical questions. Therefore, the therapeutic approach remains unclear. We have tried to define these entities and to review the respective indications and efficacy of pharmacological treatment, weight loss, sleep posture, oral appliances, upper airway surgery, and, finally, continuous positive airway pressure (CPAP). From these data, we also aim to define strategies of treatment for moderate OSA, snoring, and UARS. However, these conditions are likely to be particularly appropriate for randomized trials comparing different modalities of treatment that may be the only way to validate these treatment strategies.

Composite Events in NAOS

Abstract: This paper deals with composite events in active databases. It describes the syntax and semantics of NAOS composite event expressions. This semantics is based on the semantics of the proposed operators and on the notions of context of detection and validity interval These notions are central especially for event types containing negations and strict disjunctions. The paper also describes the event detection process with is modelized by event graphs.

SIGMA: application of multi-agent systems to cartographic generalization

Abstract: In this article we present the approach and the model used in the SIGMA (SemI automated Generalization using Multi-Agent systems) project, which is being developed in collaboration with the COGIT group of IGN (the French National Geographic Institute) and the LAMA group of the IGA laboratory (the Alpine Geographic Institute).

Prevalence of Borrelia burgdorferi (sensu lato) in Ixodes ricinus (L.) populations in France, according to a phytoecological zoning of the territory

Abstract: Ixodes ricinus is considered as the main vector of Lyme Borreliosis in France. The aim of our investigations was to obtain a comprehensive view of the spatial risk linked to the distribution of the species in our country. Previous studies [1] have provided strong evidence that the species populations are widely distributed, so the objective of the present work was to ascertain the bacteriological infection of the tick by the agent of the zoonosis (Borrelia burgdorferi, sensu lato), over the French territory, whatever the ecological conditions may be. For this purpose, we kept the same framework as that used in our acarological investigation, a phytoecological zoning of the territory into 54 geographically separate and ecologically distinct units distributed into three climatic zones. Batches of ticks, picked up in these different phytoecological units (only two thirds of which were sampled), were submitted for bacteriological investigation. A total of 4,673 ticks were examined, individually, for the presence of Borrelia burgdorferi, by immunofluorescence. Percentages of infection according to the various stages of Ixodes ricinus free stages, collected by flagging, were as follows: 4.95% in 3,247 nymphs, 11.2% in 699 males, 12.5% in 727 females. Larvae were ignored. Practically all the tested units harboured the bacterium. The percentage of tick samples (25 ticks or more) absolutely free of Borrelia, wherever they came from, is very low (not exceeding 10 percent of the sampled forests). Our study confirms the assessment of a widespread distribution of the zoonosis in France which was, until now, exclusively based on an approximate distribution of limited human cases observed in the country.