PRO2FLUX – A software program for profile quantification and diffusive O2 flux calculations

A new software program, PRO₂FLUX, has been developed for the treatment of the vertical distribution of O₂ concentrations measured with microsensors in aquatic sediments. The program proposes a friendly graphical user interface to visualize and quantify oxygen profiles semi-automatically. Once a data set has been selected and various parameters (e.g., diffusivity) have been set in the program, the user can convert the raw data signal in concentration units and can define the position of the sediment–water interface for obtaining the depth profiles. Then, PRO₂FLUX enables the user to make diffusive O₂ calculations using three of the most widely used models: (1) Fick's first law of diffusion, (2) a quadratic curve-fitting approach, and (3) Berg's model. The PRO₂FLUX software creates two types of output ASCII files for each calculation technique: a summary file for the first two diffusive models and an automatically generated input data file necessary for running Berg's model.     

A decentralized and fault tolerant convergence detection algorithm for asynchronous iterative algorithms

This article presents an algorithm that performs a decentralized detection of the global convergence of parallel asynchronous iterative applications. This algorithm is fault tolerant. It runs a decentralized saving procedure which enables this algorithm, after a node’s crash, to replace the dead node by a new one which will continue the computing task from the last check point. Combined with the advantages of the asynchronous iteration model, this method allows us to compute very large scale problems using highly volatile parallel architectures like Peer-to-Peer and distributed clusters architectures. We also present the implementation of this algorithm in the JaceP2P platform which is dedicated to designing and executing parallel asynchronous iterative applications in volatile environments. Numerous experiments show the robustness and the efficiency of our algorithm.     

Catalytic oxygenation ofβ,γ-unsaturated 3-ketosteroids in the presence of ruthenium tetramesitylporphyrin complexes

Cholest-5-ene-3-one1 is oxidized by air at room temperature in the presence of trans-di-oxoruthenium(VI)tetramesitylporphyrin Ru(O)₂ (tmp) to a mixture of the 6- and 6-alcohols3 and4, and of the enedione5. Similar results are obtained in the presence of carbonylruthenium(II)tetramesitylporphyrin Ru(CO) (tmp) as catalyst. Iron(III) and manganese(III) tetramesitylporphyrins are weakly active or inactive as catalysts for the aerobic oxidation of1. Similarly, 17-acetoxy-estr-5(10)-ene-3-one2 is oxidized to 17-acetoxy-10-hydroxyestr-4-ene-3-one7 in 42% yield in a highly-stereoselective manner in the presence of Ru(O)₂ (tmp).     

Codage pour modulation d’amplitude en quadrature à grand nombre d’états avec partition à plusieurs niveaux

We present a new multilevel coding technique for the quadrature amplitude modulation with a high number of states (64-QAM and 256-QAM). The constellation is partitioned into four subsets, two bits coded with the samebch code selecting the label of each subset. We show that our system, with a double error correctingbch code, gives better results, considering redundancy, decoding simplicity and performance, than the systems known bx now (using the Reed-Solomon code (64,62), the Lee-Nakamura and Hamming codes). Preliminary differential encoding of the two coded bits and utilisation of a transparentbch code can solve the phase ambiguity problem in a simple way.     

Radiocommunications et mobilité radiocommunications and mobility

Des études sont actuellement en cours pour définir la prochaine génération de systèmes, destinés à fournir les services de radiocommunication avec les mobiles du futur. Ces systèmes, identifiés par des sigles tels que UMTS, FPLMTS, IMT 2000, seront universels, multiservices, multienvironnements, et à très grande capacité. Ils font ľobjet de programmes internationaux de recherche et de normalisation. Le cnet participe à ces actions à travers le projet Rameau. Quatre chapitres portant chacun sur un domaine ďétude du projet (caractérisation du canal de propagation à large bande pour les mobiles, analyse de la technique ďaccès multiple par répartition en code (amrc ou cdma), étude portant sur la disponibilité et la capacité des futurs systèmes mobiles par satellites, développement de nouvelles classes ďalgorithmes pour la mise à jour de la localisation des mobiles dans le réseau) servent à illustrer la diversité des techniques qu’il est nécessaire ďétudier en préalable à la définition et la mise en œuvre des services futurs de radiocommunications avec les mobiles. Research is currently under way to define the next generation of systems to provide radiocommunication services with the mobiles of the future. These systems, with acronyms such as umts, fplmts and imt 2000, will be universal, multiservice, multienvironment and of very high capacity. They are the object of international research and standardization programs. The French national telecommunications research centre, cnet, is involved in these developments through the Rameau project. Four research areas of the project are examined (characterization of the wideband propagation channel for mobiles, analysis of the code distribution multiple access (cdma) technique, the availability and capacity of future satellite mobile systems and the development of new classes of algorithms for updating the locations of mobiles in the network) to illustrate the diversity of techniques that must be researched before the mobile radio services of the future can be defined and deployed.     

Electron microscopy studies of vanadium phosphorus oxide catalysts derived from VOPO4·2H2O

An electron microscopy study of vanadium phosphorus oxide (VPO) catalysts is reported. The catalyst precursor VOHPO₄·0.5H₂O was prepared from VOPO₄·2H₂O using isobutanol as the reducing agent. The catalyst was then fully activated by heating for ca. 75 h under reaction conditions (385C, GHSV 1000 h^–1, 1.5% butane in air). Scanning electron microscopy studies demonstrated that a topotactic transformation occurs between the precursor and the final catalyst. Transmission electron microscopy experiments revealed that there were three distinctive morphologies present in the final catalyst; namely (i) rosette shaped clusters composed of (VO)₂P₂O₇ crystallites, (ii) crystalline platelets of _II-VOPO₄ and (iii) disordered platelets exhibiting surface patches of (VO)₂P₂O₇. This latter morphology corresponds to the disordered remnants of hemihydrate particles which have only partially transformed to (VO)₂P₂O₇. The (VO)₂P₂O₇ platelets were found to be the majority phase making up more than 95% of the volume fraction.     

Sterol composition ofPhaeodactylum tricornutum as influenced by growth temperature and light spectral quality

In a detailed sterol analysis of the marine diatomPhaeodactylum tricornutum, free sterols as well as esterified and glycosylated conjugates were found. When the alga was grown under standard conditions (i.e., at 13°C under white light), 64% of total sterols were steryl glycosides. In all sterol classes, except steryl esters, (24S)-24-methylcholesta-5,22E--dien-3β-ol (epibrassicasterol) was the major (80 to 99%) sterol component. Eight other sterols were identified. Growth under different light spectral quality (red, blue, yellow, and green) at 13 and 23°C was examined. At 23°C, a dramatic decrease in total sterol content was observed, especially under blue light. The distribution of sterols between free and conjugated forms as well as sterol profile inside each class was found to be strongly dependent on the light spectral quality at both temperatures.     

On the spatial disposition of the fifth transmembrane helix and the structural integrity of the transmembrane binding site in the opioid and ORL1 G protein-coupled receptor family

Evidence from statistical cluster analyses of a multiple sequencealignment of G protein-coupled receptor seven-helix folds supportsthe existence of structurally conserved transmembrane (TM) ligandbinding sites in the opioid/opioid receptor-like (ORL1) andamine receptor families. Based on the expectation that functionallyconserved regions in homologous proteins will display locallyhigher levels of sequence identity compared with global sequencesimilarities that pertain to the overall fold, this approachmay have wider applications in functional genomics to annotatesequence data. Binding sites in models of the -opioid receptorseven-helix bundle built from the rhodopsin templates of Baldwinet al. (1997) [J. Mol. Biol., 272, 144–164] and Herzykand Hubbard (1998) [J. Mol. Biol., 281, 742–751] are compared.The Herzyk and Hubbard template is found to be in better accordwith experimental studies of amine, opioid and rhodopsin receptorsowing to the reduced physical separation of the extracellularparts of TM helices V and VI and differences in the rotationalorientation of the N-terminal of helix V that reveal side chainaccessibilities in the Baldwin et al. structure to be out ofphase with relative alkylation rates of engineered cysteineresidues in the TM binding site of the _2A-adrenergic receptor.TM helix V in the Baldwin et al. template has been remodelledwith a different proline kink to satisfy experimental constraints.A recent proposal that rotation of helix V is associated withreceptor activation is critically discussed.     

Anticipating aging failure using feedback data and expert judgment

This paper presents a methodology for anticipating failures in a component up to the end of its life cycle. Often, feedback data is not sufficient and must be complemented by the analysis of expert judgment. The methodology developed aims at anticipating the degradation mechanisms responsible for aging, and evaluating their relevance and related uncertainties. This is necessary information for risk analysis related to the operating of a component up to the end of its life cycle. Lastly, the methodology is applied to a nuclear component.