Showing papers by "University of Rennes published in 2003"
TL;DR: In this article, the authors present partial results of a series of studies on the granitoids from this region, aiming to understand their role in the building of new continental crust in eastern Asia.
543 citations
TL;DR: It demonstrates how three polarimetric parameters, namely the scattering entropy, the scattering anisotropy, and the alpha angle may be used in order to decouple surface roughness from moisture content estimation offering the possibility of a straightforward inversion of these two surface parameters.
Abstract: Proposes a new model for the inversion of surface roughness and soil moisture from polarimetric synthetic aperture radar (SAR) data, based on the eigenvalues and eigenvectors of the polarimetric coherency matrix. It demonstrates how three polarimetric parameters, namely the scattering entropy (H), the scattering anisotropy (A), and the alpha angle (/spl alpha/) may be used in order to decouple surface roughness from moisture content estimation offering the possibility of a straightforward inversion of these two surface parameters. The potential of the proposed inversion algorithm is investigated using fully polarimetric laboratory measurements as well as airborne L-band SAR data and ground measurements from two different test sites in Germany, the Elbe-Auen site and the Weiherbach site.
517 citations
TL;DR: In this article, the moduli space of pairs (C,ω) is considered, where C is a smooth compact complex curve of a given genus and ω is a holomorphic 1-form on C with a given list of multiplicities of zeros.
Abstract: Consider the moduli space of pairs (C,ω) where C is a smooth compact complex curve of a given genus and ω is a holomorphic 1-form on C with a given list of multiplicities of zeroes. We describe connected components of this space. This classification is important in the study of dynamics of interval exchange transformations and billiards in rational polygons, and in the study of geometry of translation surfaces.
502 citations
TL;DR: Phosphorylation of Ser10 in the tails of histone H3 has been extensively studied in many organisms and this modification is involved in both transcription and cell division, two events requiring opposite alterations in the degree of chromatin compaction.
Abstract: Eukaryotic cells must possess mechanisms for condensing and decondensing chromatin. Chromatin condensation is particularly evident during mitosis and cell death induced by apoptosis, whereas chromatin decondensation is necessary for replication, repair, recombination and transcription. Histones are among the numerous DNA-binding proteins that control the level of DNA condensation, and post-translational modification of histone tails plays a critical role in the dynamic condensation/decondensation that occurs during the cell cycle. Phosphorylation of Ser10 in the tails of histone H3 has been extensively studied in many organisms. Interestingly, this modification is involved in both transcription and cell division, two events requiring opposite alterations in the degree of chromatin compaction. How does one and the same modification of histone H3 fulfil such roles? For instance, in interphase, phosphorylation of H3 correlates with chromatin relaxation and gene expression, whereas in mitosis it correlates with chromosome condensation. What is the kinase and under what circumstances does Ser10 becomes phosphorylated? Most importantly, what are the consequences of phosphorylation of this residue?
468 citations
TL;DR: In insects, it is not only changes in mean environmental temperature and growing season length that are important, but also their responses to environmental extremes as discussed by the authors, with extremes of temperature, rates of temperature change, the numbers of freeze-thaw transitions, climatic unpredictability and the state of the surrounding microhabitat being important factors determining the cold tolerance strategy adopted by an insect.
Abstract: Modern climate change has precipitated widespread interest in the responses of organisms to the thermal environment. In insects, it is not only changes in mean environmental temperature and growing season length that are important, but also their responses to environmental extremes. Much is now known about the ways in which insects cope with the ice–water threshold, and with the low temperatures that precede it. Recent work has demonstrated a diversity of physiological responses to cooling and freezing in insects, with extremes of temperature, rates of temperature change, the numbers of freeze–thaw transitions, climatic unpredictability and the state of the surrounding microhabitat being important factors determining the cold tolerance strategy adopted by an insect. Insect low temperature biology now integrates techniques ranging from laboratory-based functional genomics to climatology, making it not only intrinsically fascinating, but also of considerable relevance to investigations of the biological implications of climate change.
423 citations
TL;DR: In this paper, the authors built empirical models to estimate the effects of land cover on stream ecosystems in the mid-Atlantic region (USA) and to evaluate the spatial scales over which such models are most effective.
Abstract: We built empirical models to estimate the effects of land cover on stream ecosystems in the mid-Atlantic region (USA) and to evaluate the spatial scales over which such models are most effective. Predictive variables included land cover in the watershed, in the streamside corridor, and near the study site, and the number and location of dams and point sources in the watershed. Response variables were annual nitrate flux; species richness of fish, benthic macroinvertebrates, and aquatic plants; and cover of aquatic plants and riparian vegetation. All data were taken from publicly available databases, mostly over the Internet. Land cover was significantly correlated with all ecological response variables. Modeled R
2 ranged from 0.07 to 0.5, but large data sets often allowed us to estimate with acceptable precision the regression coefficients that express the change in ecological conditions associated with a unit change in land cover. Dam- and point-source variables were ineffective at predicting ecological conditions in streams and rivers, probably because of inadequacies in the data sets. The spatial perspective (whole watershed, streamside corridor, or local) most effective at predicting ecological response variables varied across response variables, apparently in concord with the mechanisms that control each of these variables. We found some evidence that predictive power fell in very small watersheds (less than 1–10 km2), suggesting that the spatial arrangement of landscape patches may become critical at these small scales. Empirical models can replace, constrain, or be combined with more mechanistic models to understand the effects of land-cover change on stream ecosystems.
404 citations
TL;DR: In this article, a priori estimates and prove existence and uniqueness of solutions in L p p > 1, extending the results of El Karoui et al. to the case where the monotonicity conditions of Pardoux (Nonlinear Analysis; Differential Equations and Control (Montreal, QC, 1998), Kluwer Academic Publishers, Dordrecht, pp. 503-549) are satisfied.
403 citations
TL;DR: Direct observation by x-ray diffraction of a photoinduced paraelectric-to-ferroelectric structural phase transition using monochromatic 100-picosecond synchrotron pulses in tetrathiafulvalene-p-chloranil indicates structural changes at the molecular level.
Abstract: We report the direct observation by x-ray diffraction of a photoinduced paraelectric-to-ferroelectric structural phase transition using monochromatic 100-picosecond synchrotron pulses. It occurs in tetrathiafulvalene-p-chloranil, a charge-transfer molecular material in which electronic and structural changes are strongly coupled. An optical 300-femtosecond laser pulse switches the material from a neutral to an ionic state on a 500-picosecond time scale and, by virtue of intrinsic cooperativity, generates self-organized long-range structural order. The x-ray data indicate a macroscopic ferroelectric reorganization after the laser irradiation. Refinement of the structures before and after laser irradiation indicates structural changes at the molecular level.
372 citations
TL;DR: In this paper, the authors used geochemical and isotope data of three granitic plutons (Xinhuatun, Lamashan and Yiershi) to determine the proportion of mantle to crustal components in the generation of the voluminous granitoids.
351 citations
TL;DR: In this article, the authors present a typology of Late Archaean granitoids, based on the well-exposed Dharwar Craton, which can be extended to all over the world.
346 citations
TL;DR: In this article, a computationally efficient global optimization method, the differential evolution algorithm (DEA), is proposed for the synthesis of uniform amplitude arrays of two classes, i.e., unequally spaced arrays with equal phases and unequal phases.
Abstract: A computationally efficient global optimization method, the differential evolution algorithm (DEA), is proposed for the synthesis of uniform amplitude arrays of two classes, i.e., unequally spaced arrays with equal phases and unequal phases. Phase-only synthesis and the synthesis of uniformly exited unequally spaced arrays (position only synthesis) are compared and it is seen that, by using the unequal spacing, the number of array elements can be significantly reduced for attaining reduced sidelobe levels. From the DEA-based synthesis of unequally spaced arrays with uniform amplitudes and unequal phases, it is found that a tradeoff exists between the size of the unequally spaced arrays and the range of phases for the same radiation characteristics. The proposed synthesis technique using uniform amplitudes, unequal spacing, and unequal phases (position-phase synthesis) not only decreases the size of the array for the same sidelobe level compared to both the phase-only synthesis and position-only synthesis but also retains their advantages.
TL;DR: The equations governing the linear acoustics of composites with two isotropic porous constituents are derived from first principles using volume-averaging arguments and mesoscopic fluid transport between constituents within each averaging volume provides a distinct attenuation mechanism from the losses associated with the net Darcy flux.
Abstract: The equations governing the linear acoustics of composites with two isotropic porous constituents are derived from first principles using volume-averaging arguments. The theory is designed for modeling acoustic propagation through heterogeneous porous structures. The only restriction placed on the geometry of the two porous phases is that the overall composite remains isotropic. The theory determines the macroscopic fluid response in each porous phase in addition to the combined bulk response of the grains and fluid in the composite. The complex frequency-dependent macroscopic compressibility laws that are obtained allow for fluid transfer between the porous constituents. Such mesoscopic fluid transport between constituents within each averaging volume provides a distinct attenuation mechanism from the losses associated with the net Darcy flux within individual constituents as is quantified in the examples.
TL;DR: An overview of the synthesis and properties of linear organic π-conjugated systems featuring Group 14 and 15 moieties is presented and comparisons made with their better-known hydrocarbon, and nitrogen- and sulfur-containing analogues as mentioned in this paper.
TL;DR: In this paper, the authors quantify the plausible time scales of clastic sediment supply variations at the entrance of sedimentary basins based on the sedimentary system concept, which simplifies natural systems by dividing them into three zones of dominant processes: the erosion, the transfer, and the sedimentation subsystems.
TL;DR: In this article, heavy metals adsorbents were prepared by co-condensation of tetraethoxysilane and functionalized trialkoxysileane RSi(OR′)3.
TL;DR: In healthy elderly subjects, the 6-MWT represents a submaximal exercise, but at almost 80% of the VO2(max), so to be exploitable, two familiarization attempts are required to limit the learning effect.
Abstract: KERVIO, G, F CARRE, and N S VILLE Reliability and Intensity of the Six-Minute Walk Test in Healthy Elderly Subjects Med Sci Sports Exerc, Vol 35, No 1, pp 169–174, 2003PurposeThe 6-min walk test (6-MWT) is an easy and validated field test, generally used in patients to assess th
TL;DR: In this paper, the authors describe the development and application of Noyori's type catalysts based on ruthenium-arene complexes and simple chiral β-amino alcohols derived from ephedrine for the asymmetric transfer hydrogenation of 2-propanol to carbonyl substrates.
Abstract: This account describes the development and application of Noyori's type catalysts based on ruthenium-arene complexes and simple chiral β-amino alcohols derived from ephedrine, for the asymmetric transfer hydrogenation of 2-propanol to carbonyl substrates. The influence of key parameters of the catalyst system has been studied systematically, resulting in particular in the design of the novel ligand (4-biphenylmethyl)norephedrine. Thanks to the latter, the catalytic precursors and true active species could be isolated for the first time, enabling a complete structural description of the catalytic cycle and of probable deactivation pathways. Highly effective applications of those catalysts systems, i.e., the asymmetric reductions of simple aryl ketones and aryl β-keto esters, the synthesis of chiral phthalides and syn-β,δ-dihydroxy esters, are described.
TL;DR: Cross-correlation estimates within typical EEG sub-bands and statistical tests performed in 10 patients suffering from partial epilepsy reveal that SEEG signals are significantly de-correlated during the discharge period compared with periods that precede and follow this discharge, suggesting a functional decoupling of distant brain sites at seizure onset followed by an abnormally high re-coupling when the seizure develops.
Abstract: Low-voltage rapid discharges (or fast EEG ictal activity) constitute a characteristic electrophysiological pattern in focal seizures of human epilepsy. They are characterized by a decrease of signal voltage with a marked increase of signal frequency (typically beyond 25 Hz). They have long been observed in stereoelectroencephalographic (SEEG) signals recorded with intra-cerebral electrodes, generally occurring at seizure onset and simultaneously involving distinct brain regions. Spectral properties of rapid ictal discharges as well as spatial correlations measured between SEEG signals generated from distant sites before, during and after these discharges were studied. Cross-correlation estimates within typical EEG sub-bands and statistical tests performed in 10 patients suffering from partial epilepsy (frontal, temporal or fronto-temporal) reveal that SEEG signals are significantly de-correlated during the discharge period compared with periods that precede and follow this discharge. These results can be interpreted as a functional decoupling of distant brain sites at seizure onset followed by an abnormally high re-coupling when the seizure develops. They lead to the concept of 'disruption' that is complementary of that of 'activation' (revealed by significantly high correlations between signals recorded during seizures), both giving insights into our understanding of pathophysiological processes involved in human partial epilepsies as well as in the interpretation of clinical semiology.
TL;DR: It is demonstrated that short-term supramaximal anaerobic exercise induces an oxidative stress and that the plasma TBARS level is not a suitable marker during this type of exercise.
Abstract: It has been well demonstrated that the principal factor responsible for oxidative damage during exercise is the increase in oxygen consumption. However, other theoretical factors (acidosis, catecholamine autoxidation, ischemia-reperfusion syndrome, etc.) that are known to induce, in vitro, oxidative damage may also be operative during short-term supramaximal anaerobic exercise. Therefore, we hypothesized that short-term supramaximal anaerobic exercise (30-s Wingate test) could induce an oxidative stress. Lipid peroxidation markers [serum lipid radical production detected by electron spin resonance (ESR) spectroscopy and plasma malondialdehyde (MDA) levels detected by the thiobarbituric acid reactive substances (TBARS) method], as well as erythrocyte antioxidant enzyme activities [glutathione peroxidase (GPx), superoxide dismutase (SOD)] and erythrocyte glutathione (GSH) levels, were measured at rest, after the Wingate test and during the 40 min of recovery. The recovery of exercise was associated with a significant increase (x2.7) in lipid radical production detected by ESR spectroscopy, as well as with changes in the erythrocyte GSH level (−13.6%) and SOD activity (−11.7%). The paradoxical decrease in plasma TBARS (−23.7%) which was correlated with the peak power developed during the Wingate test (r=−0.7), strongly suggests that such exercise stimulates the elimination of MDA. In conclusion, this study demonstrates that short-term supramaximal anaerobic exercise induces an oxidative stress and that the plasma TBARS level is not a suitable marker during this type of exercise.
TL;DR: Metal workers, machinists, transport equipment operators and miners are among the major occupations contributing to occupational bladder cancer in men in Western Europe, with an increased risk for exposure to PAHs.
Abstract: Objectives: We examined which occupations and industries are currently at high risk for bladder cancer in men. Methods: We combined data from 11 case–control studies conducted between 1976–1996 in six European countries. The study comprised 3346 incident cases and 6840 controls, aged 30–79 years. Lifetime occupational and smoking histories were examined using common coding. Results: Odds ratios for eight a priori defined high-risk occupations were low, and with the exception of metal workers and machinists (OR = 1.16, 95% CI = 1.02–1.32), were not statistically significant. Higher risks were observed for specific categories of painters, metal, textile and electrical workers, for miners, transport operators, excavating-machine operators, and also for non-industrial workers such as concierges and janitors. Industries entailing a high risk included salt mining, manufacture of carpets, paints, plastics and industrial chemicals. An increased risk was found for exposure to PAHs (OR for highest exposure tertile = 1.23, 95% CI = 1.07–1.4). The risk attributable to occupation ranged from 4.2 to 7.4%, with an estimated 4.3% for exposure to PAHs. Conclusions: Metal workers, machinists, transport equipment operators and miners are among the major occupations contributing to occupational bladder cancer in men in Western Europe. In this population one in 10 to one in 20 cancers of the bladder can be attributed to occupation.
TL;DR: In this article, four ionic liquids, based on 1-alkyl-3methylimidazolium or quaternary ammonium cations, were used as reaction media for several typical electrochemical reactions with a strict control of the residual water concentration.
Abstract: Four different ionic liquids, based on 1-alkyl-3-methylimidazolium or quaternary ammonium cations, were used as reaction media for several typical electrochemical reactions with a strict control of the residual water concentration. The oxidation of organic molecules (anthracene, naphthalene, durene, 1,4-dithiafulvene, and veratrole) for which the cation radicals undergo first and second-order kinetics reactions were investigated in ionic liquids and compared with their behavior in acetonitrile. From the analysis of the voltammetric current responses, the reaction mechanism was established and the thermodynamic and kinetics parameters were extracted. The most interesting result is that the nature of investigated mechanisms is almost unchanged in ionic liquids as compared with conventional organic media. A decrease of the electron-transfer kinetics from the aromatic molecules to the electrode (around 1 order of magnitude) is observed for all of the studied molecules, indicating an higher solvent reorganizat...
TL;DR: In this article, the results of an experimental investigation of the concurrent action of tectonic uplift and climate variation on relief evolution were presented. But the results were limited to the case where the uplift rate was assumed to be constant.
Abstract: We present the results of an experimental investigation of the concurrent action of tectonic uplift and climate variation on relief evolution. We designed an experimental apparatus that allows the study of erosion of laboratory-scale topographies that evolve under given uplift and rainfall rates. For constant uplift and rainfall rates, the experimental topography evolves toward a statistical steady state defined by a mean elevation constant with time. Starting from such a steady state and keeping the input uplift rate constant, a subsequent change in the rainfall rate yields a change in the mean elevation of the landscape to a new equilibrium elevation. An increase in precipitation yields a lower mean steady-state elevation, whereas for a decrease in precipitation the surface is uplifted. We define this phenomenon as a climatically induced surface uplift, as opposed to a tectonically induced surface uplift. The climatically and tectonically induced surface uplifts correspond to different dynamics of denudation so that it is theoretically possible to differentiate between the climatic or tectonic causes of surface uplift from records of output sediment fluxes.
TL;DR: The high structural diversity of osmolytes combined with their multifunctionality and the seasonal flexibility of the metabolism in plants facing multiple stresses is discussed.
TL;DR: The Neuquen Basin this paper was formed as a rift basin in the early Mesozoic and contains some 5000 m of Triassic to Aptian sediment, mainly marine.
TL;DR: In liver cancers ADAM9 and ADAM12 expression is associated with tumor aggressiveness and progression and was correlated with an increase in matrix metalloproteinase 2 expression and activity.
TL;DR: In this paper, a scalar transport equation is derived using volume-averaging arguments and the frequency dependence of the transport coefficient is obtained, which allows for fluid flux across each phase individually and is shown to have a symmetric permeability matrix.
Abstract: For the purpose of understanding the acoustic attenuation of double-porosity composites, the key macroscopic equations are those controlling the fluid transport. Two types of fluid transport are present in double-porosity dual-permeability materials: (1) a scalar transport that occurs entirely within each averaging volume and that accounts for the rate at which fluid is exchanged between porous phase 1 and porous phase 2 when there is a difference in the average fluid pressure between the two phases and (2) a vector transport that accounts for fluid flux across an averaging region when there are macroscopic fluid-pressure gradients present. The scalar transport that occurs between the two phases can produce large amounts of wave-induced attenuation. The scalar transport equation is derived using volume-averaging arguments and the frequency dependence of the transport coefficient is obtained. The dual-permeability vector Darcy law that is obtained allows for fluid flux across each phase individually and is shown to have a symmetric permeability matrix. The nature of the cross coupling between the flow in each phase is also discussed.
TL;DR: The male reproductive tract produces defensins that most probably assume an important, innate organ defense system against pathogens, and high salt concentration or dithiothreitol-sensitive cationic extracts from human seminal plasma were found to display antimicrobial activity.
Abstract: Defensins are antimicrobial peptides that play a major role in innate immunity. Using reverse transcriptase-polymerase chain reaction, immunochemistry, or both, we performed a search of all presently known defensins in rat testis, epididymis, and isolated testicular cells; in mouse testis and epididymis; and in human testis and ejaculates. In the rat, all alpha- and beta-defensins except RNP-4 were expressed within the testis, whereas alpha-defensins RNP1-2, RNP-4, and beta-defensins RBD-1 and RBD-2 were present within the epididymis. In the mouse, the cryptdin transcripts CRS1C, mBD-1, and mBD-2 were detected in the testis and epididymis, whereas mBD-3 and mBD-4 were expressed only in the epididymis, and CRS4C was absent in both organs. In the human testis, transcripts for four known defensins were expressed with the consistent exception of HBD-2 and HBD-3. In rat interstitial tissue, resident macrophages expressed most of the defensins studied, whereas Leydig cells produced only RBD-2. In contrast, all studied defensins except RNP-4 were present in the seminiferous tubules. Within these tubules, peritubular and Sertoli cells expressed most of the studied alpha- and beta-defensins, whereas spermatogonia displayed only alpha-defensins, but at relatively high levels. Meiotic pachytene spermatocytes expressed only beta-defensins, whereas postmeiotic spermatids and their cytoplasmic lobes displayed both types. In humans, the HBD-1 peptide was expressed mainly in the germ line from pachytene spermatocytes to late spermatids. The peptide was also present in ejaculated spermatozoa and seminal plasma, where multiple soluble forms were present. Finally, high salt concentration or dithiothreitol-sensitive cationic extracts from human seminal plasma were indeed found to display antimicrobial activity. We conclude that the male reproductive tract produces defensins that most probably assume an important, innate organ defense system against pathogens.
TL;DR: In this paper, it was shown that having found a geodesic segment (saddle connection) joining a pair of conical points one can find with a nonzero probability another saddle connection on S having the same direction and the same length as the initial one.
Abstract: A holomorphic 1-form on a compact Riemann surface S naturally defines a flat metric on S with cone-type singularities. We present the following surprising phenomenon: having found a geodesic segment (saddle connection) joining a pair of conical points one can find with a nonzero probability another saddle connection on S having the same direction and the same length as the initial one. A similar phenomenon is valid for the families of parallel closed geodesics.
TL;DR: Palaeomagnetic data for the Silurian and the Devonian of the south European regions supposedly constituting the Armorica microplate remain rare and ambiguous as discussed by the authors, leading to diverging models regarding the latitudinal evolution of this continent.
TL;DR: The nested RT-PCR technique identified the presence of transcript encoding ERalpha mRNA in human skeletal muscles and revealed gender difference in deltoid muscle from men and women.
Abstract: Introduction/purpose To explain the effect of estrogen on skeletal muscle, the presence of estrogen receptor alpha mRNA (ERalpha mRNA) was investigated in human skeletal muscle. Methods The highly sensitive technique of nested reverse transcriptase-polymerase chain reaction (nested RT-PCR) was applied on a variety of tissue samples of both sexes: women (deltoid, pectoral, and uterus muscles) (N= 3) and men (deltoid muscle) (N= 3). The total ribonucleic acid was isolated from each tissue sample, reverse transcribed in a thermocycler, and nested PCR was then performed with specific primers. The by-products were analyzed by agarose gel electrophoresis. Internal standard 28S was simultaneously amplified. The ERalpha mRNA level was quantitated by using the ERalpha mRNA/28S mRNA ratio. Results The expected 204-bp product corresponding to ERalpha was amplified in all tested tissue samples, i.e., deltoid, pectoral, and uterine muscles from women and deltoid muscle from men. The ERalpha mRNA/28S mRNA ratios indicating the receptor expression levels in deltoid muscle from men and women were 0.945 +/- 0.393 (mean +/- SD) (N= 3) and 0.973 +/- 0.136 (mean +/- SD) (N= 2), respectively. Conclusions In conclusion, the nested RT-PCR technique identified the presence of transcript encoding ERalpha mRNA in human skeletal muscles. Semi-quantification did not reveal gender difference.