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Many species show changes in distribution and phenotypic trait variation in response to climatic warming. Evidence of genetically based trait responses to climate change is, however, less common. Here, we detected evolutionary variation in the landscape-scale distribution of a genetically based chemical polymorphism in Mediterranean wild thyme ( Thymus vulgaris ) in association with modified extreme winter freezing events. By comparing current data on morph distribution with that observed in the early 1970s, we detected a significant increase in the proportion of morphs that are sensitive to winter freezing. This increase in frequency was observed in 17 of the 24 populations in which, since the 1970s, annual extreme winter freezing temperatures have risen above the thresholds that cause mortality of freezing-sensitive morphs. Our results provide an original example of rapid ongoing evolutionary change associated with relaxed selection (less extreme freezing events) on a local landscape scale. In species whose distribution and genetic variability are shaped by strong selection gradients, there may be little time lag associated with their ecological and evolutionary response to long-term environmental change.

We investigate picosecond–nanosecond dynamics of the Rho-GTPase Binding Domain (RBD) of plexin-B1, which plays a key role in plexin-mediated cell signaling. Backbone 15N relaxation data of the dimeric RBD are analyzed with the model-free (MF) method, and with the slowly relaxing local structure/molecular dynamics (SRLS-MD) approach. Independent analysis of the MD trajectories, based on the MF paradigm, is also carried out. MF is a widely popular and simple method, SRLS is a general approach, and SRLS-MD is an integrated approach we developed recently. Corresponding parameters from the RBD dimer, a previously studied RBD monomer mutant, and the previously studied complex of the latter with the GTPase Rac1, are compared. The L2, L3, and L4 loops of the plexin-B1 RBD are involved in interactions with other plexin domains, GTPase binding, and RBD dimerization, respectively. Peptide groups in the loops of both the monomeric and dimeric RBD are found to experience weak and moderately asymmetric local ordering centered approximately at the C(i–1)(α)–C(i)(α) axes, and nanosecond backbone motion. Peptide groups in the α-helices and the β-strands of the dimer (the β-strands of the monomer) experience strong and highly asymmetric local ordering centered approximately at the C(i–1)(α)–C(i)(α) axes (N–H bonds). N–H fluctuations occur on the picosecond time scale. An allosteric pathway for GTPase binding, providing new insights into plexin function, is delineated.

In this paper we consider a class of piecewise-deterministic Markov processes (PDMPs) modeling the quantity of a given food contaminant in the body. On the one hand, the amount of contaminant increases with random food intakes and, on the other hand, decreases thanks to the release rate of the body. Our aim is to provide quantitative speeds of convergence to equilibrium for the total variation and Wasserstein distances via coupling methods., Comment: 20 pages

La démocratie est un système ancien, qui s’est décliné sous de nombreuses formes dans l’histoire, et notamment à l’intérieur de régimes républicains excluant plus ou moins le bas peuple du pouvoir. Les républiques ou les monarchies parlementaires occidentales actuelles, systèmes certes démocratiques mais au fonctionnement représentatif et indirect, connaissent aujourd’hui une crise profonde : le désamour des peuples. Comme remède, l’auteur propose un système démocratique direct et une déprofessionnalisation de la politi­que, qui permettraient à tous d’accéder à l’exercice du pouvoir tout en ayant des obligations envers les électeurs, sous peine d’être sanctionnés lors des nombreux scrutins organisés. Democracy is an ancient system that has declined in several ways over the years. This is particularly true of republican systems where the lower classes are more or less excluded from power. Modern-day Western republics and parliamentary monarchies, which are definitely democratic despite their use of indirect representation, face a deep crisis today in the form of popular disenchantment. To remedy this situation, the author proposes to push professional politicians out of power and to establish a system of direct democracy, which would allow all citizens to join the ranks of power while being accountable to voters. Failure to be accoun­table would entail the risk of being punished at the ballot box during one of the system’s many polls.

Proton nuclear spin relaxation has been for the first time extensively used for a structural and dynamical study of low-molecular-weight organogels. The gelator in the present study is a modified phenylalanine amino acid bearing a naphthalimide moiety. From T(1) (spin-lattice relaxation time in the laboratory frame) and T(1ρ) (spin-lattice relaxation time in the rotating frame) measurements, it is shown that the visible gelator NMR spectrum below the liquid-gel transition temperature corresponds to a so-called isotropic compartment, where gelator molecules behave as in a liquid phase but exchange rapidly with the molecules constituting the gel structure. This feature allows one to derive, from accessible parameters, information about the gel itself. Nuclear Overhauser effect spectroscopy (NOESY) experiments have been exploited in view of determining not only cross-relaxation rates but also specific longitudinal rates. The whole set of relaxation parameters (at 25 °C) leads to a correlation time of 5 ns for gelator molecules within the gel structure and 150 ps for gelator molecules in the isotropic phase. This confirms, on one hand, the flexibility of the organogel fibers and, on the other hand, the likely presence of clusters in the isotropic phase. Concerning cross-relaxation rates, a thorough theoretical investigation in multispin systems of direct and relayed correlations in a NOESY spectrum allows one to make conclusions about contacts (around 2-3 A) not only between naphtalimide moieties of different gelator molecules but also between the phenyl ring and the naphtalimide moiety again of different gelator molecules. As a result, not only is the head-to-tail structure of amino acid columns confirmed but also the entangling of nearby columns by the naphthalimide moieties is demonstrated.

At very low or low frequency, the so-called dispersion curves (longitudinal relaxation rate as a function of the measurement frequency) are obtained with a ''relaxome- ter,'' which is generally run according to the ''field-cycling'' technique. Because of the very poor field homogeneity, relaxation times of a single (broad) signal are measured. When going to higher fields, with standard nuclear magnetic resonance spectrometers (possibly with variable field capacities), different lines are resolved. We show how the relaxation rates pertaining to these lines can be connected to the results obtained via the relaxometer. Among other things, we demonstrate why the magnitude mode (generally used for process- ing the relaxometer data) must be used with caution when several lines are resolved. Actually, we could obtain accurate 1 H dispersion curves in a very broad frequency range (5 kHz-400 MHz), and we show that a decomposition into several Lorentzian curves proves to be adequate, as far as paramagnetic relaxation due to dissolved oxygen is concerned. The method will be applied i) to nondegassed liquid toluene, ii) to the same solvent involved in the formation of an organogel. In that latter case, a low frequency contribution to the dispersion curve (possibly non-Lorentzian) reveals the part of the solvent within the organogel structure. The algorithm used for analyzing these dispersion curves is described. 2012 Wiley Periodicals, Inc. Concepts Magn Reson Part A 40A: 80-89, 2012.

Combinations of experimentally derived data from nuclear magnetic resonance spectroscopy and analyses of molecular dynamics trajectories increasingly allow us to obtain a detailed description of the molecular mechanisms by which proteins function in signal transduction. This chapter provides an introduction into these two methodologies, illustrated by example of a small GTPase–effector interaction. It is increasingly becoming clear that new insights are provided by the combination of experimental and computational methods. Understanding the structural and protein dynamical contributions to allostery will be useful for the engineering of new binding interfaces and protein functions, as well as for the design/in silico screening of chemical agents that can manipulate the function of small GTPase–protein interactions in diseases such as cancer.

An unusual glucocorticoid-responsive element (called GRE A) was found to mediate the induction of the cytosolic aspartate aminotransferase gene by glucocorticoids and was bound by the glucocorticoid receptor in a DNase I footprinting assay. GRE A consists of two overlapping GREs, each comprising a conserved half-site and an imperfect half-site. The complete unit was able to confer glucocorticoid inducibility to a heterologous promoter (delta MTV-CAT). Mutation of any of the half-sites, including the imperfect ones, abolished inducibility by the hormone, demonstrating that each of the isolated GREs was inactive. In electrophoretic mobility shift assays, purified rat liver glucocorticoid receptor (GR) formed a low-mobility complex with GRE A, presumably containing a GR tetramer. When purified bacterially expressed DBD was used, low-mobility complexes as well as dimer and monomer complexes were formed. In inactive mutated oligonucleotides, no GR tetramer formation was detected. Modification of the imperfect half-sites in order to increase their affinity for GR gave a DNA sequence that bound a GR tetramer in a highly cooperative manner. This activated unit consisting of two overlapping consensus GREs mediated glucocorticoid induction with a higher efficiency than consensus GRE.

The zonation of the expression and regulation of the cytosolic aspartate aminotransferase (cAspAT) mRNAs in the liver acinus was investigated in diabetic and/or adrenalectomized rats. Dexamethasone increased cAspAT activity two- to threefold alone and up to sixfold in combination with streptozotocin-induced diabetes. Northern blot analysis showed that the cAspAT mRNAs were increased by those treatments; the effect of streptozotocin was reversed by the administration of insulin. In situ hybridization experiments showed that basal cAspAT mRNAs were uniformly distributed within the liver acinus. However, cAspAT mRNAs were induced by glucocorticoids specifically in the periportal zone and by streptozotocin in a larger area including the periportal and intermediary zone. The alpha 2u-globulin mRNAs which are specifically expressed in the perivenous hepatocytes are also induced by glucocorticoids in this zone, suggesting that the specific regulation of the cAspAT gene by glucocorticoids in the periportal zone is not due to the absence of functional glucocorticoid receptors in the other zones. We conclude that the regulation of the cAspAT housekeeping gene is zone specific in the liver. Furthermore, this zonation depends on the gene and on the type of hormonal or pharmacological treatment.

The regulation of cytosolic aspartate aminotransferase (cAspAT) gene expression by phorbol esters was investigated in the highly differentiated hepatoma cell line Fao. Phorbol 12,13-dibutyrate (PdBu) had no effect on basal activity but partially inhibited the induction of cAspAT by dexamethasone. The extent of inhibition (40%) was similar to that obtained with insulin or vanadate. The inhibitory effects of PdBu and vanadate were additive. In the case of PdBu, the inhibitory effects could be eliminated by first incubating the cells with PdBu, which down-regulates protein kinase C. In contrast, inhibition by insulin was not modified by this treatment. The molecular mechanism of PdBu action was investigated. Northern blot analysis showed that the steady-state mRNA levels of cAspAT were decreased by PdBu in the presence of dexamethasone. In addition, the transcription rate, as measured by run-on experiments, was also decreased under the same conditions. Finally, a 2.4 kb promoter fragment driving the chloramphenicol acetyltransferase gene was stably transfected into the Fao cells. The regulation of the activity of this promoter fragment by dexamethasone and PdBu was similar to the regulation of the endogenous cAspAT activity. We conclude that PdBu acts by regulating the promoter activity of the cAsPAT gene.

La democratie est un systeme ancien, qui s’est decline sous de nombreuses formes dans l’histoire, et notamment a l’interieur de regimes republicains excluant plus ou moins le bas peuple du pouvoir. Les republiques ou les monarchies parlementaires occidentales actuelles, systemes certes democratiques mais au fonctionnement representatif et indirect, connaissent aujourd’hui une crise profonde : le desamour des peuples. Comme remede, l’auteur propose un systeme democratique direct et une deprofessionnalisation de la politi­que, qui permettraient a tous d’acceder a l’exercice du pouvoir tout en ayant des obligations envers les electeurs, sous peine d’etre sanctionnes lors des nombreux scrutins organises.

An organogelation process depends on the gelator-solvent pair. This study deals with the solvent dynamics once the gelation process is completed. The first approach used is relaxometry, i.e., the measurement of toluene proton longitudinal relaxation time T(1) as a function of the proton NMR resonance frequency (here in the 5 kHz to 400 MHz range). Pure toluene exhibits an unexpected T(1) variation, which has been identified as paramagnetic relaxation resulting from an interaction of toluene with dissolved oxygen. In the gel phase, this contribution is retrieved with, in addition, a strong decay at low frequencies assigned to toluene molecules within the gel fibers. Comparison of dispersion curves of pure toluene and toluene in the gel phase leads to an estimate of the proportion of toluene embedded within the organogel (found around 40%). The second approach is based on carbon-13 T(1) and nuclear Overhauser effect measurements, the combination of these two parameters providing direct information about the reorientation of C-H bonds. It appears clearly that reorientation of toluene is the same in pure liquid and in the gel phase. The only noticeable changes in carbon-13 longitudinal relaxation times are due to the so-called chemical shift anisotropy (csa) mechanism and reflect slight modifications of the toluene electronic distribution in the gel phase. NMR diffusion measurements by the pulse gradient spin-echo (PGSE) method allow us to determine the diffusion coefficient of toluene inside the organogel. It is roughly two-thirds of the one in pure toluene, thus indicating that self-diffusion is the only dynamical parameter to be slightly affected when the solvent is inside the gel structure. The whole set of experimental observations leads to the conclusion that, once the gel is formed, the solvent becomes essentially passive, although an important fraction is located within the gel structure.

International audience; La RMN (Résonance Magnétique Nucléaire) est devenue, depuis la première expérience en 1945, un moyen d’investigation incontournable. Leschimistes organiciens ont été les premiers à s’en emparer dans le but de déterminer la structure de leurs molécules. Toute la communautéscientifique a suivi, tant cette spectroscopie aux multiples facettes présente une universalité indiscutable. L’avancée la plus spectaculaire estsans conteste l’IRM (Imagerie par Résonance Magnétique) et il faut bien comprendre qu’un examen par IRM n’est autre qu’une expérience deRMN avec marquage spatial.Dans ce petit livre, nous avons essayé d’aborder bon nombre d’aspects fondamentaux de la RMN tout en nous efforçant d’indiquer clairementles différents domaines d’application. Plutôt que de donner un aperçu qui aurait pu déstabiliser le lecteur, nous avons volontairement omis deparler de RMN du solide ou des noyaux quadrupolaires (de spin supérieur à ½). Sans prétendre à l’exhaustivité, nous avons traité ce qui noussemblait être le plus important d’un point de vue physicochimique (et concerner le plus grand nombre de lecteurs) pour la RMN de l’état liquideet l’IRM.Nous nous sommes efforcés de présenter (dans les pages de droite) des schémas et des clichés aussi clairs que possible et qui se comprennent demanière intuitive. Les développements mathématiques indispensables (qui figurent dans les pages de gauche) ont été simplifiés au maximum,notre souci primordial étant que cet ouvrage soit accessible à tous.

When a hydrogenation reaction is carried out with gaseous hydrogen enriched in its para- isomer in the earth magnetic field (prior to adiabatic insertion of the sample in the NMR magnet), enhanced proton longitudinal order (represented by 2 I z A I z B ) is created but also difference of enhanced polarizations ( I z A - I z B ). In a first part, it is shown theoretically and experimentally that the longitudinal relaxation time of this polarization difference is roughly twice the ones of individual polarizations. The second part is devoted to a pulse sequence designed for transforming this difference into net hyperpolarization. The evolution of this global hyperpolarization is studied experimentally in a third part and it is observed that a fraction of hyperpolarization possesses an effective longitudinal relaxation time similar to the one of the initial polarization difference. Those experimental results are interpreted by numerical calculations based on Solomon-type equations including the longitudinal order and possibly dipolar-csa cross correlation rates.

Owing to an extremely abundant literature making use of spin relaxation for structural studies, this review is limited to carbon-13 spectroscopy, to small or medium size molecules, to stereochemical and preferably geometrical determinations. The parameter of choice is evidently the Nuclear Overhauser effect (NOE) because it depends exclusively on the dipolar interaction mechanism, thus on 1/r6, where r is the distance between the two interacting spins. However, it depends also on the dynamical features of the system under investigation which must be characterized prior to any attempt for obtaining geometrical or stereochemical information. Therefore, this review is devoted not only to 1H–13C NOE but, more generally, to 13C longitudinal relaxation. After comprehensive theoretical developments, experimental methods presently available will be presented. The latter include the usual gated decoupling experiment and pulse experiments of the HOESY (Heteronuclear Overhauser Effect SpectroscopY) family. These pulse experiments, which imply carbon-13 observation, can be one-dimensional, selective one-dimensional or two-dimensional. The emphasis will be put on the interpretation which is different according to the occurrence or not of extreme narrowing conditions. Along with a literature survey, some selected examples will be presented in detail in order to illustrate the potentiality of the method.

The basal expression and hormonal regulation of cytosolic aspartate aminotransferase (cAspAT) were investigated in the rat kidney. In adrenalectomized animals, the basal activity was highest in the renal cortex and in the inner stripe of the outer medulla (0.1-0.15 U/mg protein). The glucocorticoid analogue dexamethasone increased cAspAT activity about twofold in the cortex and in the inner stripe of the outer medulla but not in the papilla. A half-maximal increase in the activity was achieved at doses of approximately 5 micrograms/100 g body wt. The mineralocorticoid aldosterone did not modify the cAspAT activity. The cell specificity of the hormonal regulation was analyzed by in situ hybridization. In untreated adrenalectomized rats, a cAspAT cRNA probe labeled mainly the inner stripe of the outer medulla. After dexamethasone or hydrocortisone treatment, labeling was uniformly increased in this part of the medulla and was heterogeneously increased in the renal cortex. The specific increase in labeling within the cortex was shown to be confined to the distal convoluted tubule and the thick ascending limb. We conclude that, in addition to widespread basal expression, cAspAT is regulated by glucocorticoids in a highly cell-specific manner in the renal cortex. The enzyme may thus participate in the increased energy metabolism elicited by these hormones in these cells.

Since the end of the last century, we’ve noticed in our western society an uneasiness regarding the mention of death. Whereas some mystical dimension allowed man to give death a meaning, the Hegelian-Nietzschean prophecy of the death of God made this impossible. Indeed, knowing that the promise of a Kingdom of Heaven was not assured any more, man prefered to obscure the death that haunted him. Despite the difficulty to face this ontological condition, we can see that the subject of death is more and more present on the contemporary artistic scene. The body which is central in relation to this problematic becomes for the artist the material through which death exorcizes and declines itself. However, from Body Art achievements to the exhibition of corpses, we can see that the experiment of death only seems possible through the treatment of the body as a martyr. If Body Art protagonists seem to find in it their model to experiment the human being in the limits of their own bodies and thus comprehend death, there are others for whom it’s the diagnosed death that is shaping the relationship to their own bodies. That’s the case with Bob Flanagan. Doomed since childhood by cystic fibrosis, we will see how this artist, by the detour of borderline achievements with a masochistic tendency and ritualised on a setting of Christianity, will redefine his relationship to the body experience and through this manage to exorcize the idea of an impending death., Altre Modernità, N° 4 (2010): La morte e i suoi riti nella cultura contemporanea

Spin polarization transfer from parahydrogen (p-H(2)) to another molecular entity is generally thought to be mediated by longitudinal spin order (represented by the operator product I(z)(A)I(z)(B), A and B being the two hydrogen nuclei which originate from p-H(2) after a hydrogenation reaction). The longitudinal spin order leads to antiphase patterns in the proton NMR spectrum. In addition to these antiphase patterns, in-phase patterns, arising from polarization differences (represented by (I(z)(A)-I(z)(B))), have been experimentally observed. A complete theory, based on a density operator treatment, has been worked out and applied to the two types of parahydrogen induced polarization experiments: PASADENA (PArahydrogen and Synthesis Allow Dramatically Enhanced Nuclear Alignment; hydrogenation reaction inside the NMR magnet) and (ALTADENA) (Adiabatic Longitudinal Transport After Dissociation Engenders Nuclear Alignment; hydrogenation reaction outside the NMR magnet). It is shown that polarization differences are always created in the case of a PASADENA experiment but that their amplitude depends critically on the ratio of the J coupling over the frequency difference between A and B. In the case of an ALTADENA experiment, if the sample is slowly transferred toward the NMR magnet, polarization differences are definitely created and their amplitude can be larger than the amplitude of the longitudinal spin order. Some test experiments demonstrate the validity of the proposed theory.

This study deals with the exact location of the monovalent metal cations Cs(+) and Tl(+) which are complexed by the p-sulfonatocalix[4]arene in water. This determination rests on the measurements of longitudinal relaxation times of carbon-13 not directly bonded to protons. The difference between the relaxation times of the free calixarene and of the complex definitely demonstrates that the monovalent metal cation is well inside the calixarene cavity. These features are in fact enhanced by the presence of paramagnetic species which act in a different way in the complexed form. Experimental results also show without any ambiguity that the calixarene cavity is essentially hydrophobic. Finally, it is observed that thallium is more mobile than cesium within the calixarene cavity.

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Tabletops incite people to collaborate around shared documents. We propose DigiTable, a platform for collocated and remote collaboration which attempts to preserve the fluidity of interactions and the mutual awareness of co- presence. DigiTable combines a multiuser tactile table- top, a video-communication system and a robust computer vision module for distant users' gesture visualization. From an experiment, we show that DigiTable improves the efficiency of a collaborative task in remote configuration. We also show that remote gesture visualization facilitates coordination as it provides to local participants important information such as intentionality and pointing. Thus, collocated and remote configurations are both worthwhile experiences: remote collaboration is not seen anymore as a poor ersatz of collocated collaboration, although presence feeling is not uniformly perceived by participants.

With the proliferation of digital cameras, the size of personal media data such as digital photos, videos, etc. has grown extremely large. The personal nature of the data has heightened the demands for a media management system on personal desktops. Existing solutions for media management target mostly server-based Web databases and rely on extensive metadata (i.e., labels) generation to aid retrieval. Personal media databases, on the other hand, have very limited labels generated by the end users themselves. This paper introduces a method for learning concept templates from web images to query personal image databases. The proposed method has the advantage of leveraging Web resources to ease personal photo retrieval in order to avoid costly annotation of personal image databases.

While image clustering has many important applications ranging from personal to Web image management, its use is often limited by the difficulty of extracting reliable semantics from low level image features. The image clusters can be improved by using features extracted from image regions rather than the whole image. Region segmentation can be improved in turn, by considering all images within the same cluster rather than segmenting each image independently. This observation leads to the unified Bayesian framework for image clustering and segmentation presented in this paper. The experimental results, reported using several types of visual feature extractors on a database of Web documents containing over 6000 images, illustrates a significant improvement over existing techniques.

International audience; Methionine sulfoxide reductases (Msr) reduce methionine sulfoxide (MetSO)-containing proteins, back to methionine (Met). MsrAs are stereospecific for the S epimer whereas MsrBs reduce the R epimer of MetSO. Although structurally unrelated, the Msrs characterized so far display a similar catalytic mechanism with formation of a sulfenic intermediate on the catalytic cysteine and a concomitant release of Met, followed by formation of at least one intramolecular disulfide bond (between the catalytic and a recycling cysteine), which is then reduced by thioredoxin. In the case of the MsrA from Escherichia coli, two disulfide bonds are formed, i.e. first between the catalytic Cys51 and the recycling Cys198 and then between Cys198 and the second recycling Cys206. Three crystal structures including E. coli and Mycobacterium tuberculosis MsrAs, which, for the latter, possesses only the unique recycling Cys198, have been solved so far. In these structures, the distances between the cysteine residues involved in the catalytic mechanism are too large to allow formation of the intramolecular disulfide bonds. Here structural and dynamical NMR studies of the reduced wild-type and the oxidized (Cys51-Cys198) forms of C86S/C206S MsrA from E. coli have been carried out. The mapping of MetSO substrate-bound C51A MsrA has also been performed. The data support (1) a conformational switch occurring subsequently to sulfenic acid formation and/or Met release that would be a prerequisite to form the Cys51-Cys198 bond and, (2) a high mobility of the C-terminal part of the Cys51-Cys198 oxidized form that would favor formation of the second Cys198-Cys206 disulfide bond.

With the advent and proliferation of low cost and high performance digital video recorder devices, an increasing number of personal home video clips are recorded and stored by the consumers. Compared to image data, video data is lager in size and richer in multimedia content. Efficient access to video content is expected to be more challenging than image mining. Previously, we have developed a content-based image retrieval system and the benchmarking framework for personal images. In this paper, we extend our personal image retrieval system to include personal home video clips. A possible initial solution to video mining is to represent video clips by a set of key frames extracted from them thus converting the problem into an image search one. Here we report that a careful selection of key frames may improve the retrieval accuracy. However, because video also has temporal dimension, its key frame representation is inherently limited. The use of temporal information can give us better representation for video content at semantic object and concept levels than image-only based representation. In this paper we propose a bottom-up framework to combine interest point tracking, image segmentation and motion-shape factorization to decompose the video into spatiotemporal regions. We show an example application of activity concept detection using the trajectories extracted from the spatio-temporal regions. The proposed approach shows good potential for concise representation and indexing of objects and their motion in real-life consumer video.

International audience; Spectral density mapping at multiple NMR field strengths is probably the best method to describe the dynamical behavior of a protein in solution through the analysis of 15N heteronuclear relaxation parameters. Nevertheless, such analyses are scarcely reported in the literature, probably because this method is excessively demanding in spectrometer measuring time. Indeed, when using n different magnetic fields and assuming the validity of the high frequency approximation, the discrete sampling of the spectral density function with 2n + 1 points needs the measurement of 3n 15N heteronuclear relaxation measurements (n R 1, n R 2, and n15N{1H}NOEs). Based on further approximations, we proposed a new strategy that allows us to describe the spectral density with n + 2 points, with the measurement of a total of n + 2 heteronuclear relaxation parameters. Applied to the dynamics analysis of the protein p13 MTCP1 at three different NMR fields, this approach allowed us to divide by nearly a factor of two the total measuring time, without altering further results obtained by the “model free” analysis of the resulting spectral densities. Furthermore, simulations have shown that this strategy remains applicable to any low isotropically tumbling protein ($$\uptau_{c} > 3$$ ns), and is valid for the types of motion generally envisaged for proteins.

Les Mixed Presence Groupware (MPG) désignent la connexion de plusieurs interfaces partagées en vue d'une collaboration distante. Nous essayons de répondre à la question suivante : pouvons-nous collaborer efficacement en médiatisant les interactions par MPG? Afin de réduire le fossé existant entre interactions distante et co-localisée, la plateforme DIGITABLE a été conçue. Une étude des interactions collaboratives durant une tâche d'assemblage de mosaïques sur DIGITABLE est présentée ici. Bien que DIGITABLE n'apporte pas le même sentiment de présence en situations distante et colocalisée, la collaboration à distance ne semble plus entravée par la médiatisation des interactions. Mixed Presence Groupwares (MPG) are the connection of two or more remote shared interfaces, for distant collaboration.We strive to answer to the question : does the mediation of interaction with MPG enable efficient collaboration ? We propose DigiTable, an experimental platform we hope lessen the gap between co-present and distant interaction. We present an experiment using DigiTable for a collaborative task of mosaic completion. Although DigiTable does not provide the same presence feeling in distant and or co-localized situation, it seems that mediation of interaction does not hinder collaboration anymore.

International audience; This study deals with a spin system constituted of three nonequivalent protons, two of them originating from para-hydrogen (p-H2) after a hydrogenation reaction carried out in the earth magnetic field. It is shown that three singlet states are created provided indirect (J) couplings exist between the three spins, implying hyperpolarization transfer toward the third spin. Upon insertion of the sample in the NMR (Nuclear Magnetic Resonance) high field magnet, the following events occur: (i) the longitudinal two-spin orders which are parts of the singlet states survive; (ii) the other two terms (of these singlet states) tend to be destroyed by magnetic field gradients but at the same time are partly converted into differences of longitudinal polarizations. Nuclear spin relaxation is studied by appropriate NMR measurements when evolution takes place in the high field magnet or in the earth field. In the former case, relaxation is classical although complicated by numerous relaxation rates associated with both longitudinal two-spin orders and longitudinal polarizations. In the latter case, an equilibration between the singlet states first occur, their disappearance being thereafter driven by relaxation rates which remain very small because of the absence of any dipolar contribution. Thus, even in the case of a three-spin system, long-lived states exist; this unexpected property could be very useful for many applications.

With the advent and proliferation of digital cameras and computers, the number of digital photos created and stored by consumers has grown extremely large. This created increasing demand for image retrieval systems to ease interaction between consumers and personal media content. Active learning is a widely used user interaction model for retrieval systems, which learns the query concept by asking users to label a number of images at each iteration. In this paper, we study sampling strategies for active learning in personal photo retrieval. In order to reduce human annotation efforts in a content-based image retrieval setting, we propose using multiple sampling criteria for active learning: informativeness, diversity and representativeness. Our experimental results show that by combining multiple sampling criteria in active learning, the performance of personal photo retrieval system can be significantly improved.

Many novel multimedia applications such as virtual immersive environments use multiple sensors and actuators. We present in this paper a novel approach for position calibration of visual sensors and actuators, i.e. cameras and displays, in a distributed network of general purpose computing devices. The proposed approach is very suitable for the calibration of mobile setups since (a) synchronization of the setup is not required, (b) it works fully automatic, (c) only weak restrictions are imposed on the positioning of the cameras and displays, and (d) no upper limit on the number of cameras and displays to calibrated is imposed. Corresponding points across different camera images are established automatically and found with subpixel accuracy. Cameras do not have to share one common view, only a reasonable overlap between camera subgroups is necessary. The method has been sucessfully tested in numerous multicamera environments with a varying number of cameras. It has proven itself to work extremely accurate. Performance results are reported.

Many novel multimedia, home entertainment, visual surveillance and health applications use multiple audio-visual sensors and actuators. In this paper we present a novel approach for position and pose calibration of visual sensors and actuators, i.e. cameras and displays, in a distributed network of general purpose computing devices. It complements our work on position calibration of audio sensors and actuators in a distributed computing platform [14]. The approach is suitable for a wide range of possible - even mobile - setups since (a) synchronization is not required, (b) it works automatically, (c) only weak restrictions are imposed on the positions of the cameras and displays, and (d) no upper limit on the number of cameras and displays under calibration is imposed. Corresponding points across different camera images are established automatically and found with subpixel accuracy. Cameras do not have to share one common view. Only a reasonable overlap between camera subgroups is necessary. The method has been sucessfully tested in numerous multi-camera environments with a varying number of cameras and displays and has proven itself to work extremely accurate.

It is now common to have accumulated tens of thousands of personal ictures. Efficient access to that many pictures can only be done with a robust image retrieval system. This application is of high interest to Intel processor architects. It is highly compute intensive, and could motivate end users to upgrade their personal computers to the next generations of processors. A key question is how to assess the robustness of a personal image retrieval system. Personal image databases are very different from digital libraries that have been used by many Content Based Image Retrieval Systems. 1 For example a personal image database has a lot of pictures of people, but a small set of different people typically family, relatives, and friends. Pictures are taken in a limited set of places like home, work, school, and vacation destination. The most frequent queries are searched for people, and for places. These attributes, and many others affect how a personal image retrieval system should be benchmarked, and benchmarks need to be different from existing ones based on art images, or medical images for examples. The attributes of the data set do not change the list of components needed for the benchmarking of such systems as specified in 2 : - data sets - query tasks - ground truth - evaluation measures - benchmarking events. This paper proposed a way to build these components to be representative of personal image databases, and of the corresponding usage models.

Haxaire Jean, Tamisier Jean-Philippe, Bouguet Jean-Pierre. Vespa velutina Lepeletier, 1836, une redoutable nouveauté pour la faune de France (Hym., Vespidae). In: Bulletin de la Société entomologique de France, volume 111 (2), juin 2006. p. 194.

Most programs are repetitive, where similar behavior can be seen at different execution times. Algorithms have been proposed that automatically group similar portions of a program's execution into phases, where samples of execution in the same phase have homogeneous behavior and similar resource requirements. In this paper, we examine applying these phase analysis algorithms and how to adapt them to parallel applications running on shared memory processors. Our approach relies on a separate representation of each thread's activity. We first focus on showing its ability to identify similar intervals of execution across threads for a single run. We then show that it is effective at identifying similar behavior of a program when the number of threads is varied between runs. This can be used by developers to examine how different phases scale across different number of threads. Finally, we examine using the phase analysis to pick simulation points to guide multi-threaded simulation.Pre-2018 CSE ID: CS2005-0844

This study is an extension of a recent work (Canet D, Barthe P, Mutzenhardt P, Roumestand C. 2001. A comprehensive analysis of multifield 15N relaxation parameters in proteins: Determination of 15N chemical shift anisotropies. J Am Chem Soc 123:4567–4576) dealing with the exploitation of the three classical 15N relaxation parameters (the longitudinal relaxation rate, R1, the transverse relaxation rate, R2, and the 1H-15N cross-relaxation rate, σNH) measured at several magnetic fields (at least two) in uniformly 15N-labeled proteins (the chosen example is the C12A-p8MTCP1 protein whose relaxation parameters have been measured at five different fields). R2 is iteratively corrected for exchange, so that the three parameters provide consistently the NH dipolar and 15N csa (chemical shift anisotropy) contributions. The dipolar spectral densities are analyzed, residue by residue, according to the functional form (d for dipolar), where τeff is an (effective) correlation time associated with the slow motion(s) sensed by the NH vector at the level of the residue to which it belongs. In comparison with the Lipari-Szabo approach, the coefficient bd can be identified with 2KdτeffS2, S being the generalized order parameter and Kd reflecting the amplitude of the dipolar mechanism (which, besides constants, involves ); ad is associated with fast local motions. The csa spectral densities appearing in the expressions of R1 and R2 can be analyzed according to ; bcsa; is proportional to bd (the proportionality factor depending on molecular quantities) and can yield 15N csa values from the rNH value and from the knowledge of the angle between the two relevant tensors. Uncertainties are such that it is impossible (at least with the present data) to conclude about a possible variation of 15N csa values along the protein backbone. © 2005 Wiley Periodicals, Inc. Concepts Magn Reson Part A 24A: 1–9, 2005.

In part I of this article, it was shown that protein 15N relaxation data at different magnetic fields can be fitted according to a residue-specific correlation time τeff, which is associated with slow motions sensed by the considered residue. The present article is an attempt to justify the correlation time variations along the backbone by anisotropic overall motion. When an axial rotation-diffusion tensor is assumed, it is possible to derive simple expressions for relating τeff to τ⟂ and τ// (the two correlation times defining the rotation-diffusion tensor). A consistent picture is obtained for the most organized parts of the protein C12A-p8MTCP1 which, as in part I of this article, serves here as an example. By contrast, the model of rotation-diffusion fails for other less-organized parts of the protein, suggesting a combination of several slow or intermediate motions. © 2005 Wiley Periodicals, Inc. Concepts Magn Reson Part A 24A: 10–16, 2005.

This manuscript deals with the determination and the exploitation of nitrogen-15 relaxation rates in labeled proteins. In the first part, we introduce the phenomenological aspect the heteronuclear relaxation. The second chapter is devoted to the measurement of these relaxation parameters in macromolecules. We present new methods to measure the cross correlation term coming from the interference between the dipolar (NH) and the nitrogen-15 chemical shift anisotropy relaxation mechanisms. The third chapter turns on the manner of extracting structural and dynamic information from these parameters. The strategy is based on a residue per residue analysis of the multifield nitrogen-15 relaxation; this approach is shown to be compatible with the assessment of anisotropic overall reorientation in proteins. The interest to include the cross correlation parameters in order to determine simultaneously the chemical exchange and the chemical shift anisotropy is also exposed., Les travaux présentés dans ce mémoire concernent la détermination et l'exploitation des paramètres de relaxation de l'isotope-15 de l'azote dans des protéines enrichies. La première partie introduit de manière générale les mécanismes de relaxation de spin. Le deuxième chapitre est consacré à la description des méthodes de mesure des paramètres de relaxation dans les protéines. De nouvelles méthodes permettant la mesure du terme de corrélation croisée provenant de l'interférence entre le mécanisme dipolaire (NH) et l'anisotropie de déplacement chimique (csa) de l'azote-15 sont exposées. Le troisième chapitre traite de la manière d'extraire des paramètres de relaxation des informations structurales et dynamiques. L'approche est basée sur une analyse résidu par résidu de la relaxation mesurée à plusieurs valeurs du champ magnétique statique, et s'avère compatible avec la détermination de l'anisotropie globale de réorientation des molécules. L'intérêt d'inclure les paramètres de corrélation croisée est également exposé pour la détermination simultanée du csa et de l'échange chimique.

A simple modification of the spin-state-selective excitation (S3E) pulse sequence element is proposed. The new sub-sequence, dubbed S2ED for spin-state echo differentiation, can be used in a very versatile way, in addition to the standard features of S3E. Experimental verifications were performed by editing α/β–HSQC–α/β spectra of nitrogen-15-labelled ubiquitin. Copyright © 2003 John Wiley & Sons, Ltd.