Showing papers by "Aix-Marseille University published in 1993"
TL;DR: In this paper, the authors discuss several constructions of orthonormal wavelet bases on the interval, and introduce a new construction that avoids some of the disadvantages of earlier constructions.
1,065 citations
TL;DR: The authors analyzed prospectively the records of 188 patients with malignant pleural mesothelioma examined between 1973 and 1990 to compare the diagnostic value of thoracoscopic biopsy, fluid cytology, and Abrams needle biopsy.
Abstract: Background To compare the diagnostic value of thoracoscopic biopsy, fluid cytology, and Abrams needle biopsy, the authors analyzed prospectively the records of 188 patients with malignant pleural mesothelioma examined between 1973 and 1990. Symptoms were pleural effusion in 173 patients, empyema in 1, spontaneous pneumothorax in 1, and radiologic tumor without effusion in 13. Methods Thoracoscopy was performed using a rigid thoracoscope under local anesthesia with neuroleptanalgesia. A total of 10-20 biopsies were taken from the parietal, diaphragmatic, and visceral pleura. Each diagnosis was confirmed by the French panel of mesothelioma pathologists. To prevent parietal seeding, radiation therapy at a dose of 21 Gy was administered during a period of 3 days to all points of entry. Results Tolerance to thoracoscopy was good. The only complications were subcutaneous emphysema (1 patient), local pleural infection (4 patients), hemorrhage of less than 100 ml (3 patients), and temperature of 38-38.5 degrees C (26 patients). In 137 patients, the cavity was free, and complete endoscopic inspection was achieved. In 51 patients, inspection was limited by adhesions that were severed to obtain biopsy. Nonspecific inflammation was observed in 12 patients (6.5%), nodules in 92 (49%), thickening in 21 (11%), and mixed lesions in 63 (33.5%). Diagnosis was achieved by thoracoscopy in 98% of patients, by fluid cytology in 26%, and by needle biopsy in 21%. Conclusion In most patients, thoracoscopy allows complete visualization of the pleural cavity and provides high-quality biopsy samples. The diagnostic accuracy of thoracoscopy is similar to open thoracotomy, but the procedure is far less invasive, usually requiring that the patient remain in the hospital only 1 day.
349 citations
TL;DR: HA-91, a strain isolated from Hyalomma asiaticum bv.
Abstract: Four isolates of spotted fever group rickettsiae isolated from ticks in China were compared with all known species and strains of spotted fever group rickettsiae by immunofluorescence assay, DNA polymerase chain reaction followed by restriction endonuclease fragment length polymorphism analysis, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and Western immunoblot. The Chinese isolates belonged to three types, including a novel serotype which has not been described before. One isolate obtained from tick ova of Dermacentor nuttallii in Inner Mongolia was antigenically and genotypically identical to Rickettsia sibirica. Two isolates obtained from Dermacentor sinicus collected from Beijing were identical, different from other members of spotted fever group rickettsiae but apparently closely related to R. sibirica. HA-91, a strain isolated from Hyalomma asiaticum bv. kozlovi olenew, was antigenically and genotypically unique among spotted fever group rickettsiae, and we feel that data presented here should prompt consideration of it as a new species on the basis of current rickettsial taxonomy. Images
118 citations
TL;DR: It is suggested that human psychophysical data confirm the hypothesis that dopamine may be involved in light retinal adaptation, as light‐induced and dopamine‐induced modifications in the shape in the contrast sensitivity function are quite similar.
Abstract: A large body of experimental evidence supports the hypothesis that dopamine is a functional neuromodulator at many levels of the visual system. Intrinsic dopaminergic neurons were characterized in most mammalian retina, including man. These neurons give rise to a dendritic plexus covering the retina. Thus, dopamine seems to be involved in the organization of the ganglion cell and the bipolar cell receptive fields and modulates physiological activity of photoreceptors, both processes which underlie sensitivity and spatial selectivity of visual processing in the early stage of the visual system. Moreover, few data are now available concerning the functional significance of dopaminergic modulation of visual sensitivity in man. Parkinson's disease is a specific disorder of central dopaminergic systems. Abnormalities in the pattern-evoked potentials and electroretinogram have been found in parkinsonian patients. Contrast sensitivity, a useful tool for measuring visual spatio-temporal sensitivity in man, has also been shown to be modified due to this affection. Dynamic contrast sensitivity is primarily decreased in these patients, distinguishing them from the normal aging process. Because these modifications in shape of the contrast sensitivity function are reversed by L-Dopa, and that neuroleptic administration could reproduce them in schizophrenia patients, it was suggested that dopamine might tune the contrast sensitivity function in man. We have recently shown that subcutaneous apomorphine induces changes in contrast sensitivity in healthy volunteers, which preferentially affect motion sensitivity. These dopaminergic sensitive modifications in the shape of the contrast sensitivity function might reflect a change in the range of sensitivity of the visual system, both in dynamic and spatial properties. This could be explained by a modification in the spatial and dynamic properties of the ganglion cell responses in the retina. Moreover, we suggest both from our results and from the review of the literature that human psychophysical data confirm the hypothesis that dopamine may be involved in light retinal adaptation, as light-induced and dopamine-induced modifications in the shape in the contrast sensitivity function are quite similar.
106 citations
TL;DR: Characterization of cuticular hydrocarbons of foraging workers of the ant Leptothorax lichtensteini at regular intervals has shown a change with time in the relative proportions of some of the hydro Carbons, which constitute a part of the colony signature.
82 citations
TL;DR: This chemical vapour deposition titanium nitride coating is well tolerated by the blood despite its surface irregularities, and appears as a good candidate material after improvements.
76 citations
TL;DR: Three experiments were conducted to examine hemispheric specialization in mirror-image discrimination and mental rotation in baboons (Papio papio), and significantly lower accuracy and longer response times were found for bilateral compared with unilateral visual input.
Abstract: Three experiments, using a matching-to-sample procedure, were conducted to examine hemispheric specialization in mirror-image discrimination and mental rotation in baboons (Papio papio). In Experiment 1, no significant difference was found in discrimination of mirror-image and asymmetric pattern stimuli. In Experiment 2, orientation discrimination was assessed within the left (LVF) and right (RVF) visual half-fields. An RVF advantage was found in accuracy for asymmetric patterns, whereas an LVF advantage was found for discrimination of mirror-image stimuli. No significant relation was found between angular disparity of the stimuli and response time. Experiment 3 examined the effect of bilateral visual input on accuracy and response time. Significantly lower accuracy and longer response times were found for bilateral compared with unilateral visual input.
72 citations
TL;DR: In this paper, the authors question the axiomatic immobility of zircon in soils, and then assess the limit of mass-balance calculations in surficial weathering systems.
65 citations
TL;DR: In this article, a study of five typical weathering profiles of the most extensive iron duricrust system now known in the world indicates that saprolitization and ferruginization are sequentially involved in such processes, as reflected by kaolinite-gibbsite and hematite-goethite replacements.
62 citations
TL;DR: The reef flats of Saint-Pierre and Saint-Leu (Reunion Island, Indian Ocean) suffered badly from hurricane Firinga on 29 January 1989 as mentioned in this paper, and the high degree of silting due to increased run-off killed the coral colonies.
Abstract: The reef flats of Saint-Pierre and Saint-Leu (Reunion Island, Indian Ocean) suffered badly from hurricane Firinga on 29 January 1989. The high degree of silting due to increased run-off killed the coral colonies. Fish communities were surveyed at four periods following the hurricane (March and September 1989, March and September 1990). An increase in both species richness (31 to 47 spp. per census) and abundance (169 to 265 individuals per census) of fishes was observed with time, along with changes in their trophic structure. This positive succession may be linked to the disappearance of the silt layer from reef flats since September 1989. Nevertheless, there were differences in fluctuations and trophic structure of the fish community between back-, inner- and outer-reef flats. Finally, differences in recovery between the two reefs are related to the overall environmental degradation of the Island, chiefly by human perturbation, prior to the hurricane.
60 citations
TL;DR: In this paper, the enantioselective reduction of ketones by borane in the presence of catalytic amounts of (S )-(−)-proline or ( S )-(+)-prolinol as chiral auxiliaries has been investigated.
Abstract: The enantioselective reduction of ketones by borane in the presence of catalytic amounts of ( S )-(−)-proline or ( S )-(+)-prolinol as chiral auxiliaries has been investigated. The alcohols possess all the ( R ) configuration, and are obtained in good enantiomeric excess. A mechanistic rationale is proposed, involving an oxazaborolidine formed from ( S )-(+)-prolinol and borane.
TL;DR: In this paper, the vibrational structure of the C60/substrate interfaces is analyzed in detail by HREELS carried out in the dipole and impact scattering regimes, showing that the epitaxy of C60 on GeS(001) is induced by the weak van der Waals bonding and the peculiar corrugation of the substrate surface.
Abstract: C60 films have been grown in ultra high vacuum on various crystalline substrates and the structure of the films has been investigated by low energy electron diffraction (LEED) and high resolution electron energy loss spectroscopy (HREELS). The C60 films form randomly oriented nanocrystals on Si(100), mesoscopic polycrystals on GaSe(0001) and microscopic single crystals on GeS(001). The vibrational structure of the C60/substrate interfaces is analyzed in detail by HREELS carried out in the dipole and impact scattering regimes. It is shown that the epitaxy of C60 on GeS(001) is induced by the weak van der Waals bonding and the peculiar corrugation of the substrate surface.
TL;DR: This study demonstrates that the mouse monoclonal antibody MAb can provide a specific and simple method for detection of E. chaffeensis in clinical specimens for establishing an etiologic diagnosis of human ehrlichiosis and may also provide a tool for the investigation of immunopathologic characteristics in infected patients.
Abstract: A mouse monoclonal antibody (MAb 1A9) was produced and used in detection of Ehrlichia chaffeensis in human tissues including kidney, liver, and lung by using an indirect immunohistologic stain. MAb 1A9 was specific to E. chaffeensis and did not react with other bacteria, including Ehrlichia canis, which is the organism most closely related to E. chaffeensis. It reacted with an epitope present in two surface proteins of E. chaffeensis with molecular masses of 29 and 27 kDa. E. chaffeensis was easily detected in human tissue by immunohistology with MAb 1A9. This study demonstrates that our MAb can provide a specific and simple method for detection of E. chaffeensis in clinical specimens for establishing an etiologic diagnosis of human ehrlichiosis; it may also provide a tool for the investigation of immunopathologic characteristics in infected patients.
TL;DR: It is found that there are some invariant features of the electrotonic structure which are related to the geometry and not to the electrical parameters, while other features are changed by altering the Electrical parameters.
Abstract: We describe how the stochastic geometry of dendritic arborization of a single identified motoneuron of the rat affects the local details of its electrotonic structure. After describing the 3D dendritic geometry at high spatial resolution, we simulate the distribution of voltage gradients along dendritic branches under steady-state and transient conditions. We show that local variations in diameters along branches and asymmetric branchings determine the non-monotonous features of the heterogeneous electrotonic structure. This is defined by the voltage decay expressed as a function of the somatofugal paths in physical distances (voltage gradient). The fan-shaped electrotonic structure demonstrates differences between branches which are preserved when simulations are computed from different values of specific membrane resistivity although the absolute value of their voltages is changed. At given distances from soma and over long paths, some branches display similar voltages resulting in their grouping which is also preserved when specific membrane resistivity is changed. However, the mutual relation between branches inside the group is respecified when different values of specific membrane resistivity are used in the simulations. We find that there are some invariant features of the electrotonic structure which are related to the geometry and not to the electrical parameters, while other features are changed by altering the electrical parameters. Under transient conditions, the somatofugal invasion of the dendritic tree by a somatic action potential shifts membrane potentials (above 10 mV) of dendritic paths for unequal distances from the soma during several milliseconds. Electrotonic reconfigurations and membrane shifts might be a mechanism for postsynaptic plasticity.
TL;DR: Results indicate that the Ti6A14V alloy is well tolerated by blood.
TL;DR: Ceramics are more and more frequently under consideration for construction of blood-contacting devices, i.e. cardiac valves or cardiac assist devices, and the haemolysis was almost zero for all powders, except AlN which showed slight haenolysis and TiB2 which had high haemorytic power.
TL;DR: In this article, the efficient chiral catalyst [CoI 2 ;Zn/(L*) n ] readily promotes the homo Diels-Alder reactions between norbornadiene 1 and alkynes 2, affording tetracyclic compounds called “deltatcyclenes.
Abstract: The efficient chiral catalyst [CoI 2 ;Zn/(L*) n ] readily promotes the homo Diels-Alder reactions between norbornadiene 1 and alkynes 2 , affording tetracyclic compounds called “deltatcyclenes” 3 . In this [2+2+2) cycloadditions, stereochemical control is achieved through the presence of catalytic amount of homochiral mono and bidentate ligands leading to deltacyclenes in high chemical and optical yields.
TL;DR: In this paper, it was shown that the triplet channel induced by the presence of the nitro group is much more efficient than the singlet one for CO bond rupture in the indolinospironaphthopyrans.
Abstract: Nanosecond laser flash photolysis has been used to study the photochromic reaction of three spiro(indoline-naphthopyrans) substituted by one or two nitro groups on the two moieties of the molecule: either on the naphthopyran ring (compound I ), or on the indoline ring (compound II ), and the third compound ( III ) with a nitro group on both rings; the unsubstituted compound ( IV ) was also studied for comparison. In the present work it was found for the three nitro-substituted compounds that the photomerocyanine (the opened all-trans isomer of the spironaphthopyran) is formed partially via a triplet pathway and also to a less extent via an excited singlet pathway, according to the position of the nitro group. In contrast, the photomerocyanine of the unsubstituted compound is formed only via an excited singlet state. The quantum yields of photomerocyanine formation were determined in toluene solution: substitution by NO 2 on the naphthopyran moiety leads to a very high quantum yield (∼0.9) and proceeds essentially via the triplet pathway, while for the other two compounds ( II and III ) the yield obtained is around 0.5 and both triplet and singlet pathways are involved; in the unsubstituted compound in which only the singlet pathway is present, the coloration yield is much lower (∼0.2). The results show that the triplet channel induced by the presence of the nitro group is much more efficient than the singlet one for CO bond rupture in the indolinospironaphthopyrans. Moreover semi-empirical calculations were performed using the AM1 method; the theoretical results show the importance of the S 1 —T 1 energy gap in the closed form for coloration efficiency.
TL;DR: In this paper, the dissociation and oxidation of carbon monoxide on small rhodium particles prepared by vapour deposition of Rh on either MgO or alumina substrate has been investigated by means of static secondary ion mass spectrometry (SSIMS), and temperature programmed reaction (TPR).
Abstract: The dissociation and oxidation of carbon monoxide on small rhodium particles prepared by vapour deposition of Rh on either MgO or alumina substrate has been investigated by means of static secondary ion mass spectrometry (SSIMS), and temperature programmed reaction (TPR). The intensity ratios Rh
n
C+/Rh+
n
measured by SSIMS, have been used to monitor the build-up of surface carbon concentration. It was shown that a part of the CO molecularly adsorbed on clean particles undergoes dissociation during heating. The dissociation is more important for smaller particles. This behaviour is explained in terms of increase of CO dissociation probability in the case of CO adsorption near structural irregularities of a surface (edges, corners, steps). During the reaction of CO oxidation the intermediate carbon formation, which is more pronounced for smaller particles, is observed. The temperature dependent carbon concentration exhibits a maximum resulting from a counterbalance between CO dissociation first and carbon reaction with adsorbed oxygen consequently.
TL;DR: In this article, the authors considered the standard model in the formulation of non-commutative geometry, for a Euclidean space-time consisting of two copies, and showed that the only solutions for the minimization equations of the total potential occur in the narrow band.
TL;DR: Low pressure chemical vapor deposition processes (CVD) make diamond formation possible within a well defined domain of the phase diagram and some data is available from literature on diamond exhibits exceptional properties and is therefore intended for projects associated with the durability concept.
Abstract: Two main groups of ventricular assist devices exist: active deformable devices and blood pumps fitted out with undeformable chamber. The left ventricular assist device (LVAD) which was initially proposed by J.R. Monties et P. Havlik (1) is valveless and based on the Maillard-Wenkel rotary principle so it is a non centrifugal device which produces a partially pulsatile flow. As this system is intended to be fully implantable construction materials must meet stringent requirements. Physically they must be light but rigid, hard and have a low friction coefficient while being wear resistant and chemically inert. Physiologically they must be biocompatible (2, 3). In particular they must not a) be toxic or allergenic, b) alter the osmotic and acidlbase balance of the blood, c) damage blood cells, d) modify the quantity or quality of plasmatic porteins or e) activate the complement and hemostasis systems. The materials which fit the best these requirements belong to many categories: steels, cemented carbides, composites (C/C, C/SiC), coated materials and ceramics. If the materials presenting a high density are discarded, composites, coated materials and ceramics appeared to feature the best chemical resistance and the best tribological properties. Carbon-carbon composites have been selected along a first stage (4-6) but morphological studies revealed a too disturbed surface state; that is the main reason why such materials were given up. Coated materials were then selected. Choice of the substrate depends on bulk characteristics while that of the coating is clearly determined by its surface properties and biocompatibility. Four ceramic coatings were then considered: titanium nitride (TiN), boron carbide (B4C), diamond-like carbon (DLC) and diamond. Substrates could be either graphite or aluminium coated by vapor deposition process. At the present time, TiN has been elaborated (7) and its total qualification is on hand. Boron carbide and diamond-like carbon studies are still in progress. Although studies of pure crystalline diamonds have not yet been undertaken in our laboratory, some data are available from literature. Thus comparisons can be established between the four ceramic coatings: hardness, density, friction coefficient, wear resistance, thermal conductivity and chemical resistance (Tab. I). Diamond exhibits exceptional properties and is therefore intended for projects associated with the durability concept. What is diamond? What are its potential applications? How to elaborate diamond films and control them? Diamond (8) is an allotropic form of carbon that crystallizes in a cubic or hexagonal structure in which each carbon atom is linked by strong, rigid chemical Sp3 bonds (9) to four other carbon atoms arranged tetrahedrally around it. Each crystal is a rigid structure and diamonds is the hardest material (10). Apart from its excellent thermal conductivity (11), diamond is the most chemically inert of all known materials: diamonds are resistant to all acids Diamond is perfect for wear-resistant applications (12). Its low friction coefficient varies from 0.05 to 0.16 depending on the surface (13). Imperfections or small amounts of impurities in the diamond can effect its properties (8). Let us recall that diamonds films must not be mistaken for diamond-like carbon films (14); DLC contains mixed Sp2 and Sp3 bonds and is amorphous, hydrogen can be present at an atomic abundancy reaching 30 to 50%. Many methods allow diamond films synthesis (15). Among them we chose low pressure chemical vapor deposition processes (CVD). Such methods make diamond formation possible within a well defined domain of the phase diagram (16). Diamond can be vapor deposited by (17) Hot Filament CVD (HFCVD) (18), by Electron-Assisted CVD (EACVD) (19), by Laser Assisted CVD (LCVD), laser excited CVD and by the various plasma-assisted CVD (PACVD): dc jet chemical vapor deposition (20), discharge plasma CVD (21, 22), radiofrequency plasma assisted CVD and microwave plasma assisted CVD (MPACVD) (19, 23-29). The net chemical reaction that occurs:
TL;DR: The results showed that the form of low‐affinity for ouabain exhibited a lower turnover rate than the high affinity form, indicating this specific isoform kinetic difference could contribute to differences in the cardiac cellular function.
TL;DR: In vitro platelet adhesion was assessed with a new model: titanium nitride (TiN) deposited on Ti6A14V (TA6V) titanium alloy by a physical vapor deposition (PVD) process, which confirms its good performance as a blood-contacting biomaterial.
Abstract: In order to evaluate under dynamic circumstances the in vitro platelet adhesion induced by rigid materials such as ceramic coatings deposited on selected substrates, a new model simulating a tube has been designed. In vitro platelet adhesion was assessed with this new model: the material was titanium nitride (TiN) deposited on Ti6A14V (TA6V) titanium alloy by a physical vapor deposition (PVD) process. The results were compared to those obtained with complete titanium carbide (TiC) graphite tubes coated with TiN by a chemical vapor deposition (CVD) process. The difference observed (less than 25%) in favour of the new system, could be due to the better surface state of the construction materials of this system. In fact it is a systemic error. However TiN confirms its good performance as a blood-contacting biomaterial.
TL;DR: Wittig reactions of α-substituted ketones using a chiral phosphonate derived from mannitol afford chiral olefins by kinetic resolution as mentioned in this paper.
Abstract: Wittig reactions of α-substituted ketones using a chiral phosphonate derived from mannitol afford chiral olefins by kinetic resolution.
TL;DR: In this paper, a power-law upper bound for the decay of the correlations for Holder observables in the case of a nonuniformly hyperbolic map of the interval introduced by Gaspard and Wang as a piecewise linear approximation of the intermittent map of Manneville-Pomeau was proved.
Abstract: We prove a power-law upper bound for the decay of the correlations for Holder observables in the case of a nonuniformly hyperbolic map of the interval introduced by Gaspard and Wang as a piecewise linear approximation of the intermittent map of Manneville-Pomeau. The result is then applied to compute the Central Limit Theorem for the same class of observables.
TL;DR: The tau lepton lifetime was measured using four different methods with the DELPHI detector as mentioned in this paper, and three measurements using one prong decays were combined, accounting for correlations, resulting in ττ=298 ±7 (stat.)±4 (syst.) fs.
TL;DR: In this paper, the crystal structure of 1 has been determined by X-ray diffraction and it belongs to the cubic space group Pa 3 with Z =8, a =15.7451 A, D c =1.26 g cm −3, R =0.00395.
TL;DR: It is evident that suppressor CD8 cells do play a role inCD4 cells from proliferating against Tg and TPO; however their function alone or in combination with suppressor-inducer CD4 cells is partially disturbed, so that T cell sensitization to Tg or TPO can be identified in the AITD PBMC.
Abstract: To investigate T-cell sensitization to thyroid autoantigens in autoimmune thyroid disease (AITD), purified soluble human thyroglobulin (Tg) and thyroid peroxidase (TPO) were used. Peripheral blood mononuclear cells (PBMC) as well as CD8-depleted, CD4-enriched PBMC ("selected" PBMC) from 9 patients with Graves' disease (GD), 13 Hashimoto's thyroiditis (HT) and 10 healthy subjects, were cultured for 6 days with or without varying concentrations (0.1, 1.0 and 5.0 micrograms/ml, respectively) of Tg or TPO and their responses were evaluated using the 3H-thymidine incorporation assay. Total PBMC as well as selected PBMC from GD and HT responded to both TPO and Tg, but normal PBMC did not. This induction was more marked in "selected" PBMC; on the other hand, CD8 depletion did not permit normal PBMC to respond to either antigen. However, reactivity of selected AITD PBMC to Tg differed from that of TPO. Two way analysis of variance showed that the proliferative response was significantly greater with Tg than with TPO, (again particularly notable with the "selected" PBMC) in both GD and HT. There was no difference between control and AITD preparations when an irrelevant (renal microsomal) antigen was employed. Taken together with our previous report that CD4 cells were induced by TPO even when cultured with CD8 cells, it is evident that suppressor CD8 cells do play a role in CD4 cells from proliferating against Tg and TPO; however their function alone or in combination with suppressor-inducer CD4 cells is partially disturbed, so that T cell sensitization to Tg and TPO can be identified in the AITD PBMC.
Journal Article•
TL;DR: Two mouse homeobox genes are characterised, named Cux and Phox2, the products of which bind to and regulate the promoter of the Ncam gene in vitro, and its highly specific expression pattern suggests that Phox1, besides regulating Ncam, may be determinant of the noradrenergic phenotype.
Abstract: The orderly arrangement of neuronal cell bodies and axonal projections generated during nervous system development requires precise spatio-temporal control of the expression and activity of cell adhesion receptors. Recent evidence suggests that homeobox genes, an important class of developmental control genes, many of which are preferentially expressed in developing nervous tissue, play prominent roles in the regulation of expression of these molecules. We have characterised two mouse homeobox genes, named Cux and Phox2, the products of which bind to and regulate the promoter of the Ncam gene in vitro. Its highly specific expression pattern suggests that Phox2, besides regulating Ncam, may be determinant of the noradrenergic phenotype.