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Showing papers by "Aix-Marseille University published in 2003"


Journal ArticleDOI
TL;DR: A crucial role is established for 14-3-3ε in neuronal development by sustaining the effects of CDK5 phosphorylation and providing a molecular explanation for the differences in severity of human neuronal migration defects with 17p13.3 deletions.
Abstract: Heterozygous deletions of 17p13.3 result in the human neuronal migration disorders isolated lissencephaly sequence (ILS) and the more severe Miller–Dieker syndrome (MDS). Mutations in PAFAH1B1 (the gene encoding LIS1) are responsible for ILS and contribute to MDS, but the genetic causes of the greater severity of MDS are unknown. Here, we show that the gene encoding 14-3-3e (YWHAE), one of a family of ubiquitous phosphoserine/threonine–binding proteins, is always deleted in individuals with MDS. Mice deficient in Ywhae have defects in brain development and neuronal migration, similar to defects observed in mice heterozygous with respect to Pafah1b1. Mice heterozygous with respect to both genes have more severe migration defects than single heterozygotes. 14-3-3e binds to CDK5/p35-phosphorylated NUDEL and this binding maintains NUDEL phosphorylation. Similar to LIS1, deficiency of 14-3-3e results in mislocalization of NUDEL and LIS1, consistent with reduction of cytoplasmic dynein function. These results establish a crucial role for 14-3-3e in neuronal development by sustaining the effects of CDK5 phosphorylation and provide a molecular explanation for the differences in severity of human neuronal migration defects with 17p13.3 deletions.

365 citations


Journal ArticleDOI
TL;DR: Genetic guidelines for the classification of rickettsial isolates at the genus, group, and species levels are proposed by using sequences of the 16S rRNA (rrs) gene and four protein-coding genes, the gltA, ompA, and ompB genes and gene D.
Abstract: We propose genetic guidelines for the classification of rickettsial isolates at the genus, group, and species levels by using sequences of the 16S rRNA (rrs) gene and four protein-coding genes, the gltA, ompA, and ompB genes and gene D. To be classified as a member of the genus Rickettsia, an isolate should exhibit degrees of rrs and gltA homology with any of the 20 Rickettsia species studied of ≥98.1 and ≥86.5%, respectively. A member of the typhus group should fulfill at least two of the following four criteria: pairwise nucleotide sequence homologies with rrs, gltA, ompB, and gene D of either Rickettsia typhi or Rickettsia prowazekii of ≥99.4, ≥96.6, ≥92.4, and ≥91.6%, respectively. A member of the spotted fever group should either possess the ompA gene or fulfill at least two of the following four criteria: pairwise nucleotide sequence homologies with rrs, gltA, ompB, and gene D of any member of this group of ≥98.8, ≥92.7, ≥85.8, and ≥82.2%, respectively. The existence of a distinct “ancestral” group should be questioned. To be classified as a new Rickettsia species, an isolate should not exhibit more than one of the following degrees of nucleotide similarity with the most homologous validated species: ≥99.8 and ≥ 99.9% for the rrs and gltA genes, respectively, and, when amplifiable, ≥98.8, ≥99.2, and ≥99.3% for the ompA and ompB genes and gene D, respectively. By use of our classification scheme, “Rickettsia heilongjiangii” belongs to a new species for which we officially propose the name Rickettsia heilongjiangensis sp. nov.

361 citations


Journal ArticleDOI
TL;DR: In this paper, a synthesis of articles dealing with the rheological characterisation of biological wastewater treatment plant sludges (activated or concentrated ones) and some other concentrated suspensions such as microorganism ones is presented.

246 citations


Journal ArticleDOI
TL;DR: In this article, an inter-laboratory slide-scoring exercise was performed among 34 laboratories from 21 countries with a total of 51 slide scorers involved, and the results of these studies indicate clearly that even after standardizing culture and scoring conditions it will be necessary to calibrate scorers and laboratories if MN, MNed cell and nucleoplasmic bridge frequencies are reliably compared among laboratories and among populations.
Abstract: One of the objectives of the HUman MicroNucleus (HUMN) project is to identify the methodological variables that have an important impact on micronucleus (MN) or micronucleated (MNed) cell frequencies measured in human lymphocytes using the cytokinesis-block micronucleus assay. In a previous study we had shown that the scoring criteria used were likely to be an important variable. To determine the extent of residual variation when laboratories scored cells from the same cultures using the same set of standard scoring criteria, an inter-laboratory slide-scoring exercise was performed among 34 laboratories from 21 countries with a total of 51 slide scorers involved. The results of this study show that even under these optimized conditions there is a great variation in the MN frequency or MNed cell frequency obtained by individual laboratories and scorers. All laboratories ranked correctly the MNed cell frequency in cells from cultures that were unirradiated, or exposed to 1 or 2Gy of gamma rays. The study also estimated that the intra-scorer median coefficient of variation for duplicate MNed cell frequency scores is 29% for unexposed cultures and 14 and 11% for cells exposed to 1 and 2Gy, respectively. These values can be used as a standard for quality or acceptability of data in future studies. Using a Poisson regression model it was estimated that radiation dose explained 67% of the variance, while staining method, cell sample, laboratory, and covariance explained 0.6, 0.3, 6.5, and 25.6% of the variance, respectively, leaving only 3.1% of the variance unexplained. As part of this exercise, nucleoplasmic bridges were also estimated by the laboratories; however, inexperience in the use of this biomarker of chromosome rearrangement was reflected in the much greater heterogeneity in the data and the unexplained variation estimated by the Poisson model. The results of these studies indicate clearly that even after standardizing culture and scoring conditions it will be necessary to calibrate scorers and laboratories if MN, MNed cell and nucleoplasmic bridge frequencies are to be reliably compared among laboratories and among populations.

187 citations


Journal ArticleDOI
TL;DR: A database of magnetic susceptibility measurements on different non-ordinary chondrites (C, E, R, and ungrouped) populations is presented and compared to our previous similar work on ordinary chondites as discussed by the authors.
Abstract: A database of magnetic susceptibility (χ) measurements on different non-ordinary chondrites (C, E, R, and ungrouped) populations is presented and compared to our previous similar work on ordinary chondrites. It provides an exhaustive study of the amount of iron-nickel magnetic phases (essentially metal and magnetite) in these meteorites. In contrast with all the other classes, CM and CV show a wide range of magnetic mineral content, with a two orders of magnitude variation of ?. Whether this is due to primary parent body differences, metamorphism or alteration, remains unclear. C34 and C2 yield similar χ values to the ones shown by CK and CM, respectively. By order of increasing χ, the classes with well-grouped χ are: R << CO < CK ≈ CI < Kak < CR < E ≈ CH < CB. Based on magnetism, EH and EL classes have indistinguishable metal content. Outliers that we suggest may need to have their classifications reconsidered are Acfer 202 (CO), Elephant Moraine (EET) 96026 (C45), Meteorite Hills (MET) 01149, and Northwest Africa (NWA) 521 (CK), Asuka (A)-88198, LaPaz Icefield (LAP) 031156, and Sahara 98248 (R). ? values can also be used to define affinities of ungrouped chondrites, and propose pairing, particularly in the case of CM and CV meteorites.

179 citations


Journal ArticleDOI
TL;DR: The novel mutations corresponding to residues involved in Kir2.1 channel–PIP2 interactions presented here as well as the overall frequency of mutations occurring in these residues indicate that defects in PIP2 binding constitute a major pathogenic mechanism of ATS.
Abstract: Background: Mutations in KCNJ2 , the gene encoding the inward-rectifying K + channel Kir2.1, cause the cardiac, skeletal muscle, and developmental phenotypes of Andersen–Tawil syndrome (ATS; also known as Andersen syndrome). Although pathogenic mechanisms have been proposed for select mutations, a common mechanism has not been identified. Methods: Seventeen probands presenting with symptoms characteristic of ATS were evaluated clinically and screened for mutations in KCNJ2 . The results of mutation analysis were combined with those from previously studied subjects to assess the frequency with which KCNJ2 mutations cause ATS. Results: Mutations in KCNJ2 were discovered in nine probands. These included six novel mutations (D71N, T75R, G146D, R189I, G300D, and R312C) as well as previously reported mutations R67W and R218W. Six probands possessed mutations of residues implicated in binding membrane-associated phosphatidylinositol 4,5-bisphosphate (PIP 2 ). In total, mutations in PIP 2 -related residues accounted for disease in 18 of 29 (62%) reported KCNJ2 -based probands with ATS. Also reported is that mutation R67W causes the full clinical triad in two unrelated males. Conclusions: The novel mutations corresponding to residues involved in Kir2.1 channel–PIP 2 interactions presented here as well as the overall frequency of mutations occurring in these residues indicate that defects in PIP 2 binding constitute a major pathogenic mechanism of ATS. Furthermore, screening KCNJ2 in patients with the complex phenotypes of ATS was found to be invaluable in establishing or confirming a disease diagnosis as mutations in this gene can be identified in the majority of patients.

177 citations


Journal ArticleDOI
TL;DR: It is shown that intrinsic disorder is a widespread property within Paramyxovirinae N and P, using a combination of different computational approaches relying on different physico-chemical concepts.
Abstract: The existence and extent of disorder within the replicative complex (N, P and the polymerase, L) of Paramyxovirinae were investigated, drawing on the discovery that the N-terminal moiety of the phosphoprotein (P) and the C-terminal moiety of the nucleoprotein (N) of measles virus are intrinsically unstructured. We show that intrinsic disorder is a widespread property within Paramyxovirinae N and P, using a combination of different computational approaches relying on different physico-chemical concepts. Notably, experimental support that has often gone unnoticed for most of the predictions has been found in the literature. Identification of disordered regions allows the unveiling of a common organization in all Paramyxovirinae P, which are composed of six modules defined on the basis of structure or sequence conservation. The possible functional significance of intrinsic disorder is discussed in the light of experimental data, which show that unstructured regions of P and N are involved in numerous interactions with several protein and protein-RNA partners. This study provides a contribution to the rather poorly investigated field of intrinsically disordered proteins and helps in targeting protein domains for structural studies.

167 citations


Journal ArticleDOI
TL;DR: It is shown that the red-shifted absorption originates from chlorophyll-chlorophyll (Chl) excitonic interactions involving Chl A5 in each of the four Lhca antenna complexes, and it is suggested that coordination by Asn of ChL A5 holds it at the correct distance with Chl B5.

160 citations


Journal ArticleDOI
TL;DR: The crystal structure of the extreme C-terminal domain (XD) of measles virus phosphoprotein is reported, presenting the first measles virus protein structure, and light is shed on the function of the phosphop protein at the molecular level and on the process of induced folding.

156 citations


Journal ArticleDOI
TL;DR: In this paper, the authors derived a multiphase model of compressible fluids, where each fluid has a different average translational velocity, density, pressure, internal energy as well as the energies related to rotation and vibration.
Abstract: The aim of this paper is the derivation of a multiphase model of compressible fluids. Each fluid has a different average translational velocity, density, pressure, internal energy as well as the energies related to rotation and vibration. The main difficulty is the description of these various translational, rotational and vibrational motions in the context of a one-dimensional model. The second difficulty is the determination of closure relations for such a system: the 'drag' force between inviscid fluids, pressure relaxation rate, vibration and rotation creation rates, etc. The rotation creation rate is particularly important for turbulent flows with shock waves. In order to derive the one-dimensional multiphase model, two different approaches are used. The first one is based on the Hamilton principle. We use the second approach, in which the pure fluid equations are discretized at the microscopic level and then averaged. In this context, the flow is considered to be the annular flow of two turbulent fluids. We also derive the continuous limit of this model which provides explicit formulae for the closure laws

141 citations


Journal ArticleDOI
TL;DR: In this paper, the authors used cosmogenic 10Be measurements to date alluvial terraces in the French western Alps, in order to estimate river incision rates and to infer river response to climatic fluctuations and tectonic forcing.

Journal ArticleDOI
TL;DR: In this article, a thermal desorption chemical ionization mass spectrometer was developed for real-time quantitative chemical analysis of ultrafine particles, which combines recently developed nanoparticle separation and collection techniques with highly sensitive chemical analysis provided by selected ion chemical ionisation mass analyzer.
Abstract: A thermal desorption chemical ionization mass spectrometer has been developed for real time, quantitative chemical analysis of ultrafine particles. The technique combines recently developed nanoparticle separation and collection techniques with highly sensitive chemical analysis provided by selected ion chemical ionization mass spectrometry. Sensitivity tests using laboratory-generated ammonium sulfate particles in the diameter range 10-16 nm show that sulfate and ammonium can be quantified with as little as 1 pg of collected aerosol mass. Such sensitivity makes this instrument suitable for real time measurements of the chemical composition of sub-10 nm particles reported recently from nucleation events.

Book ChapterDOI
TL;DR: In this article, the authors used a panel of 312 French banks observed quarterly over the period 1993-2000 to check the possible existence of a bank lending channel in France and found some asymmetry between liquid and illiquid banks, the latter being more sensitive to monetary policy tightening.
Abstract: The aim of this paper is to check the possible existence of a bank lending channel in France. For that purpose, we have estimated a dynamic reduced form model allowing for asymmetries in loan supply across banks, depending on their size, liquidity and capitalization. We have used a panel of 312 French banks observed quarterly over the period 1993-2000. We find some asymmetry between liquid and illiquid banks, the latter being more sensitive to a monetary policy tightening. This result is in accordance with that obtained for several other countries of the Euro area. It constitutes an indication that, as far as they can, French banks sell part of their liquid assets in order to shield their loan portfolio from the effects of increases in the interest rate. Contrary to what has been found for the US (e.g., see Kashyap and Stein (1995, 2000) and Kishan and Opiela (2000)), we do not find the two other banks' characteristics we consider (size and capitalization) to have any significant impact on bank lending.

Journal ArticleDOI
TL;DR: Progress in neuroimaging has aided the approach to brain malformations associated with mental retardation hence allowing a new classification of conditions previously described as non-syndromic, based on very similar brain mal Formations in affected subjects.
Abstract: A number of apparently non-syndromic X linked mental retardation syndromes are associated with subtle but characteristic phenotypic manifestations. Such manifestations can be dysmorphic features but they potentially also extend to abnormal brain morphology. In this latter field, progress in neuroimaging has aided the approach to brain malformations associated with mental retardation hence allowing a new classification of conditions previously described as non-syndromic. This classification is based on very similar brain malformations in affected subjects. Among the many brain malformations that can be associated with mental retardation in affected children, rhombencephalic anomalies are being recognised with increasing frequency. Accordingly, the classification of malformations of the posterior fossa has evolved considerably during the last decade.1–3 The cerebellum is known to be involved in movement coordination. However, besides its role in the control and integration of motor activity, the cerebellum also represents an essential node in the neural network subserving higher order behaviour.4,5 An abundant circuitry links the cerebellum with associative and paralimbic areas of the cerebral cortex and cerebellar lesions are known to underlie a cognitive syndrome combining impaired affective regulation, fine motor coordination, language fluency, verbal memory, and the ability to plan.4,5 These fascinating characteristics have led researchers to search for genetic determinants controlling cerebellar development. One way of addressing the genetics of cerebellar development in humans is to study families in which this brain region is abnormally developed. A number of families with X linked congenital cerebellar hypoplasia (CCH) have been reported,6–8 but no disease causing gene has been identified so far. We have studied several families with X linked congenital cerebellar hypoplasia (CCH) and mental retardation and we have found different mutations in the oligophrenin-1 ( OPHN1 ) gene. Carrier females are mildly affected and, accordingly, we found that they have a random …

Journal ArticleDOI
TL;DR: The xanthophyll exchange rate is determined by the structure of individual Lhc gene products and it is specifically controlled by the lumenal pH independently from the activation state of the violaxanthin deepoxidase enzyme.
Abstract: Plant thylakoids have a highly conserved xanthophyll composition, consisting of β-carotene, lutein, neoxanthin and a pool of violaxanthin that can be converted to antheraxanthin and zeaxanthin in excess light conditions. Recent work has shown that xanthophylls undergo dynamic changes, not only in their composition but also in their distribution among Lhc proteins. Xanthophylls are released from specific binding site in the major trimeric LHCII complex of photosystem II and are subsequently bound to different sites into monomeric Lhcb proteins and dimeric Lhca proteins. In this work we review available evidence from in vivo and in vitro studies on the structural determinants that control xanthophyll exchange in Lhc proteins. We conclude that the xanthophyll exchange rate is determined by the structure of individual Lhc gene products and it is specifically controlled by the lumenal pH independently from the activation state of the violaxanthin deepoxidase enzyme. The xanthophyll exchange induces important modifications in the organization of the antenna system of Photosystem II and, possibly of Photosystem I. Major changes consist into a modulation of the light harvesting efficiency and an increase of the protection from lipid peroxidation. The xanthophyll cycle thus appears to be a signal transduction system for co-ordinated regulation of the photoprotection mechanisms under persistent stress from excess light.

Journal ArticleDOI
TL;DR: The Torpedo marmorata a1 isoform was found to be addressed specifically to nerve endings, whereas VATPases in the neuron cell bodies contain a different a-subunit isoform.
Abstract: Vacuolar H+ATPase (V-ATPase) accumulates protons inside various intracellular organelles, generating the electrochemical proton gradient required for many vital cellular processes. V-ATPase is a complex enzyme with many subunits that are organized into two domains. The membrane domain that translocates protons contains a proteolipid oligomer of several c subunits and a 100 kDa a subunit. Several a-subunit isoforms have been described that are important for tissue specificity and targeting to different membrane compartments, and could also result in the generation of V-ATPases with different functional properties. In the present report, we have cloned the Torpedo marmorata a1 isoform. This isoform was found to be addressed specifically to nerve endings, whereas VATPases in the neuron cell bodies contain a different a-subunit isoform. In nerve terminals, the V-ATPase membrane domain is present not only in synaptic vesicles but also in the presynaptic plasma membrane, where its density could reach 200 molecules microm(-2). This V-ATPase interacts with VAMP-2 and with the SNARE complexes involved in synaptic vesicle docking and exocytosis.

Journal ArticleDOI
TL;DR: In this paper, European vegetation during representative “warm” and “cold” intervals of stage-3 was inferred from pollen analytical data, and the inferred vegetation differs in character and spatial pattern from that of both fully glacial and fully interglacial conditions and exhibits contrasts between warm and cold intervals.

Journal ArticleDOI
TL;DR: A comprehensive description of the gene products composing the Photosystem I light harvesting system of A. thaliana is shown, with beta-carotene specifically bound to Lhca3 in addition to the xanthophylls violaxanthin and lutein, indicating a peculiar structure of carotenoid binding sites.
Abstract: In this study, two gene products (Lhca2 and Lhca3), encoding higher plants (Arabidopsis thaliana) Photosystem I antenna complexes, were overexpressed in bacteria and reconstituted in vitro with purified chloroplast pigments. The chlorophyll-xanthophyll proteins thus obtained were characterized by biochemical and spectroscopic methods. Both complexes were shown to bind 10 chlorophyll (a and b) molecules per polypeptide, Lhca2 having higher chlorophyll b content as compared to Lhca3. The two proteins differed for the number of carotenoid binding sites: two and three for Lhca2 and Lhca3, respectively. beta-carotene was specifically bound to Lhca3 in addition to the xanthophylls violaxanthin and lutein, indicating a peculiar structure of carotenoid binding sites in this protein since it is the only one so far identified with the ability of binding beta-carotene. Analysis of the spectroscopic properties of the two pigment proteins showed the presence of low energy absorption forms (red forms) in both complexes, albeit with different energies and amplitudes. The fluorescence emission maximum at 77 K of Lhca2 was found at 701 nm, while in Lhca3 the major emission was at 725 nm. Reconstitution of Lhca3 without Chl b reveals that Chl b is not involved in originating the low energy absorption forms of this complex. The present data are discussed in comparison to the properties of the recombinant Lhca1 and Lhca4 complexes and of the native LHCI preparation, previously analyzed, thus showing a comprehensive description of the gene products composing the Photosystem I light harvesting system of A. thaliana.

Journal ArticleDOI
TL;DR: The three oligomers were found to be degraded mainly under acidic conditions, and at the highest temperature value (120 degrees C), a quick and complete acid degradation of each FOS was observed.
Abstract: High-performance anion exchange chromatography coupled with a pulsed amperometric detection system (HPAEC−PAD) was used to evaluate the extent of chemical hydrolysis of three fructooligosaccharides (FOS) including 1-kestose (β-D-Fru-(2→1)2-α-D-glucopyranoside, GF2), nystose (β-D-Fru-(2→1)3-α-D-glucopyranoside, GF3), and fructofuranosylnystose (β-D-Fru-(2→1)4-α-D-glucopyranoside, GF4). A kinetic study was carried out at 80, 90, 100, 110, and 120 °C in aqueous solutions buffered at pH values of 4.0, 7.0, and 9.0. Under each experimental condition, the determination of the respective amounts of reactants and hydrolysis products showed that FOS hydrolysis obeyed pseudo-first-order kinetics as the extent of hydrolysis, which decreased at increasing pH values, increased with temperature. The three oligomers were found to be degraded mainly under acidic conditions, and at the highest temperature value (120 °C), a quick and complete acid degradation of each FOS was observed. Using the Arrhenius equation, rate con...

Journal ArticleDOI
TL;DR: The interactions between climatic and volcanic forcing on diatom communities contained in a 50,000-year sedimentary sequence from Lake Massoko, Tanzania, were examined in this paper.

Journal ArticleDOI
TL;DR: In this paper, the authors describe the crustal structure of the Coast Mountains batholith between 54° and 55°N, within the Canadian Cordillera, with emphasis on emplacement of the 7 km thick Kasiks sill complex (KSC).
Abstract: [1] We describe the crustal structure of the Coast Mountains batholith between 54° and 55°N, within the Canadian Cordillera, with emphasis on emplacement of the 7 km thick Kasiks sill complex (KSC). Kinematic patterns that developed during emplacement of the KSC are the result of interactions between magma transport, magma accumulation and regional deformation. The sills were emplaced during NW directed normal shearing and flattening of country rocks that host the KSC. A ∼2 km thick shallowly NE dipping mylonite zone cuts the eastern side of the KSC. Kinematic indicators within the mylonite zone record top to the east normal displacements. Structural analysis shows that mylonite formation occurred during subvertical shortening and east-northeast, subhorizontal extension. U/Pb zircon age dates show that ENE directed normal shearing along the eastern side of the KSC and WNW directed normal shearing within the KSC occurred contemporaneously between ∼54 and 51 Ma, indicating strong strain partitioning between the mylonite and the KSC. This pattern of strain partitioning is interpreted to have been driven by return flow of melt-laden crust in response to tectonic denudation of the upper crust. Seismic profiling shows that many of these structures extend to mid and lower crustal depths. Comparison of our results with other regions within the Canadian Cordillera indicates that orogen-scale right-lateral strike-slip faults deformed synchronously with wide spread magmatism and formation of extensional gneiss domes. Thus the crustal structure of the Coast Mountains batholith was the result of early Tertiary batholith construction during dextral oblique convergence and synorogenic collapse.

Journal ArticleDOI
TL;DR: In this article, the growth of Fe species is strongly dependent on the Si concentration: at Si/Fe 1, the predominance of edge linkages corresponds to a two dimensional growth.

Journal ArticleDOI
TL;DR: In this article, the authors modeled tree mortality three months after a wildfire in the mixed-wood boreal forest (Quebec, Canada) using data from 1963 trees in 36 stands burned under a wide range of fire behavior conditions during the 1997 Val Paradis fire.
Abstract: We modeled tree mortality three months after a wildfire in the mixed-wood boreal forest (Quebec, Canada) using data from 1963 trees in 36 stands burned under a wide range of fire behavior conditions during the 1997 Val Paradis fire. Stand composition influenced the char height: height of burn was lower in deciduous stands than mixed or coniferous stands. Analysis of species mortality rates revealed that Populus tremuloides Michx. was the least fire-resistant species, whereas Picea mariana Moench and Pinus banksiana Lamb. were the most resistant species. Efficient interactions for conifers exist between crown and cambial resistance to injury and fire behavior, as diameter at breast height (DBH), total tree height (TOTH), and mean bark thickness are characteristic variables through- out the fire behavior range. The best logistic regressions, relating probability of wildfire- induced mortality to morphology and fire variables, always entered char height (CH) at the first step of the stepwise procedure, followed by a morphological variable (DBH or TOTH). The Kappa coefficient used for model validations revealed that logistic regressions using morpho- logic and fire variables were very efficient as compared to logistic regressions based only on morphologic variables. Potential applications of these results by land managers are discussed. FOR. SCI. 49(4):566-576.

Journal ArticleDOI
TL;DR: In this paper, the authors investigate the dynamics of the collisional process that follows the closure of an oceanic basin and show that the amount of continental material that subducts before the onset of collision depends on the slab pull exerted by the subducted oceanic lithosphere.
Abstract: [1] Using laboratory experiments, we investigate the dynamics of the collisional process that follows the closure of an oceanic basin. The evolution of these experiments systematically shows four successive episodes of deformation, which correspond to (1) the initiation of oceanic subduction, (2) a mature period of oceanic subduction, (3) an episode of continental subduction, during which the trench absorbs all the convergence and the superficial tectonic regime does not change significantly within the continental plates, and (4) continental collision that starts when the trench locks and convergence is absorbed by a system of thrust faults and folds. We observe that the amount of continental material that subducts before the onset of collision depends on the slab pull exerted by the subducted oceanic lithosphere. The slab-pull force, in turn, depends on the amount of subducted oceanic material, on the thickness of the convective mantle, and also on the rheology of the slab. Our experiments, indeed, suggest that parts of the oceanic slab may separate from the superficial slab to sink rapidly in the mantle, decreasing the slab-pull level and triggering the rapid onset of collision. We observe two possible modes of slab deformation: slab break-off and development of viscous instabilities. We define two dimensionless rheological numbers to characterize the possible occurrence of these modes of deformation. In all cases, oceanic closure is followed by episode of continental subduction during which the continental lithosphere may reach depths varying between 50 and 450 km, prior to the onset of continental collision.

Journal ArticleDOI
TL;DR: In this article, a cement-based grout formulation was investigated to immobilize low-level radioactive evaporator concentrates with widely variable chemical composition, and the results showed that high contents of phosphate in the waste (>25 g·l−1) were shown to improve most properties of the elaborated materials.

Journal ArticleDOI
TL;DR: The species-specific compound composition provides insight into taxonomy and species origin of European Reticulitermes termite taxa and demonstrates the limits for this analytical approach.
Abstract: Sixteen terpene compounds were isolated from the soldier defensive secretions of seven European termite taxa of the genus Reticulitermes (Isoptera, Rhinotermitidae). We describe species-specific mixtures of monoterpenes (α-pinene, β-pinene, limonene), sesquiterpenes (germacrene C, germacrene A, germacrene B, β-selinene, δ-selinene, γ-selinene, (E)-β-farnesene, γ-cadinene, nerolidol), diterpenes (geranyl linalool, geranyl geraniol, geranyl geranial), and one sesterterpene (geranyl farnesol). Compounds were purified by HPLC and their structures determined by means of MS spectrometry, or 1D and 2D NMR spectroscopy. Comparison of two different analytical approaches, GC-MS and HPLC with subsequent NMR spectroscopy, revealed Cope rearrangement of germacrene A, germacrene B, and germacrene C to the respective β-elemene, γ-elemene, and δ-elemene under GC conditions, thus demonstrating the limits for this analytical approach. The species-specific compound composition provides insight into taxonomy and species origin of European Reticulitermes. The biological significance of the species-specific composition of Reticulitermes defensive secretions is briefly discussed.

Journal ArticleDOI
TL;DR: In this article, the relationship between calcite dissolution and paleoproductivity over the past three glacial-interglacial cycles was evaluated in a deep-sea sediment core recovered from a site lying well above the local lysocline.

Journal ArticleDOI
TL;DR: The model enabled the quantification of the contribution and the characteristic time of reactions that took place on the global partitioning between particulate and dissolved phases during sorption and desorption and to determine the extent to which these reactions were modified by the salinity.

Journal ArticleDOI
TL;DR: In this paper, a short core in a small tropical crater lake ( Lake Masoko, SW Tanzania) reveals changes in charred-particle deposition and properties, consistent with high climatic variability for the last 4200 years.
Abstract: Charcoal analysis from a short core in a small tropical crater lake (Lake Masoko, SW Tanzania) reveals changes in charred-particle deposition and properties, consistent with high climatic variability for the last 4200 years. This is evidenced by automated image analysis of charcoal size distributions, thermal resistant carbon (soot) and black carbon elemental analysis. Charcoal-particle transport in the lake decreases during dry spells, and increases with stronger runoff regime in the catchment area under humid periods and/or during abrupt low-stands of the lake. However, between 1830 and 1560 cal. yr BP, charcoal-distribution variability and an abrupt increase in particulate carbonaceous particles testify to regional emissions from forest fires and atmospheric transport. This event was followed by a prolonged period of material accumulation but regional climatic drying. After 1560 cal. yr BP, large charcoal fragment accumulation and a rise in the length:width ratio of microcharcoal indicate fires closer ...

Journal ArticleDOI
TL;DR: In this paper, a review of the geology of the epicentral area combined with detailed field mapping and structural analysis al- lows constraining the tectonic and geomorphic evolution of the Trevaresse ridge anticline and associated fault that rup- tured during the 1909 event.
Abstract: Keywords. - SE France, Reverse faulting, Folding, Neogene-Quaternary, Seismotectonics. Abstract. - The 06/11/1909, Lambesc, M=6 earthquake is the strongest instrumental seismic event recorded in French history. A review of the geology of the epicentral area combined with detailed field mapping and structural analysis al- lows constraining the tectonic and geomorphic evolution of the Trevaresse ridge anticline and associated fault that rup- tured during the 1909 event. The Trevaresse fold is a WNW-trending, southerly-verging forced ramp anticline developed above the Trevaresse reverse fault during late Miocene and Pliocene times, and possibly after the early Pleistocene. Over the last 11 Ma, the Trevaresse reverse fault records an average reverse slip rate of 0.03 ± 0.02 mm/yr consistent with a homogeneous N005 - N010 trending shortening direction. The fault is segmented into two major segments (the eastern one being linked to a possibly active frontal blind thrust fault) separated by a relay fault zone associated with an en-echelon fold pattern con- sistent with a slight left-lateral component on the easternmost segment. Our structural analysis combined with recent es- timates of the source parameters of the Lambesc earthquake indicates that the fault has to reach at least the basement- cover interface, at a minimum depth of 6 km. The westward longitudinal decrease in morphological maturity of the re- lief of the Trevaresse ridge anticline and its associated fault scarp suggests a westward propagation of the fold during partly diachronous activation of the two segments of the fault.