Academic literature on the topic 'Problème des cyclages'
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Journal articles on the topic "Problème des cyclages"
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Seshadri, M. S., Y. L. Chan, M. R. Wilkinson, R. S. Mason, and S. Posen. "Some problems associated with adenylate cyclase bioassays for parathyroid hormone." Clinical Science 68, no. 3 (March 1, 1985): 311–19. http://dx.doi.org/10.1042/cs0680311.
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1. A renal adenylate cyclase system was assessed for its suitability in the performance of parathyroid hormone (PTH) bioassays. Membrane preparations from 1 week old chicks were found to be more sensitive to PTH than material from humans, dogs or rats. 2. Because of the presence of non-specific inhibitors and stimulators of adenylate cyclase in human serum, each serum sample was assayed in the presence and in the absence of a specific PTH inhibitor and the difference was used to calculate PTH activity. 3. Calcium, an inhibitor of adenylate cyclase, was either removed from serum samples by pretreatment with Chelex resin or chelated during assay by means of EGTA. 4. Human and bovine PTH (1-34) stimulated adenylate cyclase in this system to the same extent. The lower limit of detectability was 19.5 pg/ml (final concentration). The intra-assay coefficient of variation at a final concentration of 45 pg/ml was 18%. The index of precision was 0.08 ± 0.04 (n = 7). 5. When synthetic human PTH (1-34) was infused into three normal volunteers, the mean biological half-life of this material was found to be 3.2 min. 6. PTH-like bioactivity could be routinely detected in sera from normal rats, while such activity was significantly decreased in rats subjected to thyroparathyroidectomy.
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CIPCIGAN, Mihaiela CORNEA, and Doru PAMFIL. "Expression Effects of CHI and CHS Genes and Colchicine Treatment in Yellow Flowered Cyclamen: a Review." Bulletin of University of Agricultural Sciences and Veterinary Medicine Cluj-Napoca. Horticulture 76, no. 1 (June 12, 2019): 1. http://dx.doi.org/10.15835/buasvmcn-hort:2019.0003.
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Nowadays, the field of entirely artificial hybrids raises ethical problems in the animal world and to a lesser amount in plants. Throughout the years, yellow Cyclamen has been particularly important for both breeders and passionate growers as being a peculiar color for this species. The possibility to artificially induce hybrids between species that can never normally cross it’s now achievable. This paper describes the possibility of obtaining high ornamental yellow flowered cyclamen, through chromosome doubling. The pollen and seed sterility can be overcome by doubling the chromosomes. In this sense, there are two full sets from each parent, resulting in a fertile hybrid, by introducing the in vitro culture into colchicine supplemented medium.
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Anderson, Neil O. "Cultivar Trial Setup: A Case Study for Potted Plant Production Specialists." HortTechnology 11, no. 3 (January 2001): 481–84. http://dx.doi.org/10.21273/horttech.11.3.481.
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A case study is presented for use as an active learning tool for students in a floriculture potted plant production class. This is the second case study developed for Floratech, a potted plant finisher. Students work together in small groups to solve the proposed problems; each student role-plays as a Potted Plant Production Specialist. A memorandum from the Board of Directors is delivered in their first month on the job at Floratech. Objectives of this case study are to determine the students' fluency in terminology and crop-specific cultural requirements for potted plant production of cyclamen (Cyclamen persicum) and primrose (Primula sp.) as well as their ability to setup a scientifically rigorous and unbiased cultivar trial for Floratech personnel and selected customers. Students research the latest commercial catalogs to determine which species, series, and cultivars are available, as well as their relative merits, prior to choosing the appropriate cultivars to include in the trial. The trial setup has a space limitation of 2,000 ft2 (186 m2). This case study was tested with 20 undergraduate students during Fall Semester 1999. The case study demonstrated the students' fluency with terminology and crop-specific cultural requirements for both crops. Their ability to set up a scientifically rigorous trial varied widely, often with an inadequate sampling of cultivars and excessive replications (56 ± 37 cyclamen to 132 ± 65 primrose). A mean ± sd of 4 ± 1 cyclamen and 7 ± 3 primrose series were chosen. The number of cultivars varied from 6 ± 2 cyclamen to 9 ± 4 primrose and the number of distributors was similar for the crops. Trial design and additional questions raised by the case study were discussed in class and applied in a cultivar trial in the lab. Unanswered questions were used as learning opportunities during class tours with local growers.
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Beste, Kerstin Y., and Roland Seifert. "cCMP, cUMP, cTMP, cIMP and cXMP as possible second messengers: Development of a hypothesis based on studies with soluble guanylyl cyclase α1β1." Biological Chemistry 394, no. 2 (February 1, 2013): 261–70. http://dx.doi.org/10.1515/hsz-2012-0282.
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Abstract Adenosine 3′,5′-cyclic monophosphate and guanosine 3′,5′-cyclic monophosphate are second messengers that regulate multiple physiological functions. The existence of additional cyclic nucleotides in mammalian cells was postulated many years ago, but technical problems hampered development of the field. Using highly specific and sensitive mass spectrometry methods, soluble guanylyl cyclase has recently been shown to catalyze the formation of several cyclic nucleotides in vitro. This minireview discusses the broad substrate-specificity of soluble guanylyl cyclase and the possible second messenger roles of cyclic nucleotides other than adenosine 3′,5′-cyclic monophosphate and guanosine 3′,5′-cyclic monophosphate. We hope that this article stimulates productive and critical research in an area that has been neglected for many years.
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Hewlett, E. L., K. J. Kim, S. J. Lee, and M. C. Gray. "Adenylate cyclase toxin from Bordetella pertussis: current concepts and problems in the study of toxin functions." International Journal of Medical Microbiology 290, no. 4-5 (October 2000): 333–35. http://dx.doi.org/10.1016/s1438-4221(00)80035-1.
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JUNTUNEN, T., A. C. TSIKLIRAS, S. MANTYNIEMI, and K. I. STERGIOU. "A Bayesian population model to estimate changes in the stock size in data poor cases using Mediterranean bogue (Boops boops) and picarel (Spicara smaris) as an example." Mediterranean Marine Science 15, no. 3 (September 18, 2014): 587. http://dx.doi.org/10.12681/mms.567.
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The paper presents an effort to build a biologically realistic, age structured Bayesian model for the stock assessment of data poor fisheries where only aggregated catch data is available. The model is built using prior information from other areas and ecologically or taxonomically similar species. The modeling approach is tested with data poor fisheries on the Cyclades islands in Greek archipelago. The two most important species in the area are selected: bogue (Boops boops) and picarel (Spicara smaris). Both are hermaphroditic. The only data available is the total catch from 1950 to 2010. Information was gathered about natural mortality, recruitment, growth, body size, fecundity, and sex ratio. There were significant problems in finding reliable prior information and a uniform prior was used for fishing mortality. The models at their present stage are not used to give management advice. The biological characteristics of the species in that area should be further studied. However, the posteriors of biological parameters reflect the best available knowledge on these species and they could be used in future studies or in simpler biomass dynamics models as priors.
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Forman, Henry Jay, Jon M. Fukuto, and Martine Torres. "Redox signaling: thiol chemistry defines which reactive oxygen and nitrogen species can act as second messengers." American Journal of Physiology-Cell Physiology 287, no. 2 (August 2004): C246—C256. http://dx.doi.org/10.1152/ajpcell.00516.2003.
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Except for the role of NO in the activation of guanylate cyclase, which is well established, the involvement of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in signal transduction remains controversial, despite a large body of evidence suggestive of their participation in a variety of signaling pathways. Several problems have limited their acceptance as signaling molecules, with the major one being the difficulty in identifying the specific targets for each pathway and the chemical reactions supporting reversible oxidation of these signaling components, consistent with a second messenger role for ROS and RNS. Nevertheless, it has become clear that cysteine residues in the thiolate (i.e., ionized) form that are found in some proteins can be specific targets for reaction with H2O2 and RNS. This review focuses on the chemistry of the reversible oxidation of those thiolates, with a particular emphasis on the critical thiolate found in protein tyrosine phosphatases as an example.
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Kim, Keonhee, Youngdae Yoon, Hyukjin Cho, and Soon-Jin Hwang. "Molecular Probes to Evaluate the Synthesis and Production Potential of an Odorous Compound (2-methylisoborneol) in Cyanobacteria." International Journal of Environmental Research and Public Health 17, no. 6 (March 16, 2020): 1933. http://dx.doi.org/10.3390/ijerph17061933.
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The volatile metabolite, 2-Methylisoborneol (2-MIB) produced by cyanobacterial species, causes odor and taste problems in freshwater systems. However, simple identification of cyanobacteria that produce such off-flavors may be insufficient to establish the causal agent of off-flavor-related problems as the production-related genes are often strain-specific. Here, we designed a set of primers for detecting and quantifying 2-MIB-synthesizing cyanobacteria based on mibC gene sequences (encoding 2-MIB synthesis-catalyzing monoterpene cyclase) from various Oscillatoriales and Synechococcales cyanobacterial strains deposited in GenBank. Cyanobacterial cells and environmental DNA and RNA were collected from both the water column and sediment of a eutrophic stream (the Gong-ji Stream, Chuncheon, South Korea), which has a high 2-MIB concentration. Primer sets mibC196 and mibC300 showed universality to mibC in the Synechococcales and Oscillatoriales strains; the mibC132 primer showed high specificity for Pseudanabaena and Planktothricoides mibC. Our mibC primers showed excellent amplification efficiency (100–102%) and high correlation among related variables (2-MIB concentration with water RNA r = 689, p < 0.01; sediment DNA r = 0.794, p < 0.01; and water DNA r = 0.644, p < 0.05; cyanobacteria cell density with water RNA and DNA r = 0.995, p < 0.01). These primers offer an efficient tool for identifying cyanobacterial strains possessing mibC genes (and thus 2-MIB-producing potential) and for evaluating mibC gene expression as an early warning of massive cyanobacterial occurrence.
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Chen, Guilin, Armel Jackson Seukep, and Mingquan Guo. "Recent Advances in Molecular Docking for the Research and Discovery of Potential Marine Drugs." Marine Drugs 18, no. 11 (October 30, 2020): 545. http://dx.doi.org/10.3390/md18110545.
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Marine drugs have long been used and exhibit unique advantages in clinical practices. Among the marine drugs that have been approved by the Food and Drug Administration (FDA), the protein–ligand interactions, such as cytarabine–DNA polymerase, vidarabine–adenylyl cyclase, and eribulin–tubulin complexes, are the important mechanisms of action for their efficacy. However, the complex and multi-targeted components in marine medicinal resources, their bio-active chemical basis, and mechanisms of action have posed huge challenges in the discovery and development of marine drugs so far, which need to be systematically investigated in-depth. Molecular docking could effectively predict the binding mode and binding energy of the protein–ligand complexes and has become a major method of computer-aided drug design (CADD), hence this powerful tool has been widely used in many aspects of the research on marine drugs. This review introduces the basic principles and software of the molecular docking and further summarizes the applications of this method in marine drug discovery and design, including the early virtual screening in the drug discovery stage, drug target discovery, potential mechanisms of action, and the prediction of drug metabolism. In addition, this review would also discuss and prospect the problems of molecular docking, in order to provide more theoretical basis for clinical practices and new marine drug research and development.
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Takayama, Airi, Masayuki J. Sato, Yoshiyuki Arai, Toshio Yanagida, and Masahiro Ueda. "2P199 Intracellular dynamics of PI3-kinase- and guanylyl cyclase-dependent signaling pathways in Dictyostelium cells during electrotaxis(Cell biological problems-adhesion, motility, cytoskeleton, signaling,and membrane,Poster Presentations)." Seibutsu Butsuri 47, supplement (2007): S162. http://dx.doi.org/10.2142/biophys.47.s162_4.
Full textDissertations / Theses on the topic "Problème des cyclages"
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Maffre, Samuel. "Conjugaison et cyclage dans les groupes de Garside, applications cryptographiques." Limoges, 2005. http://aurore.unilim.fr/theses/nxfile/default/a2d5043f-56f9-490f-9b58-18c1b0f7d718/blobholder:0/2005LIMO0028.pdf.
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Ce travail s'inscrit dans la thématique de la cryptographie basée sur les tresses. Nous nous intéressons au problème de conjugaison et au problème des cyclages présentés par K. H. Ko, S. J. Lee et al. à CRYPTO 2000 (LNCS 1880) dans New public-key cryptosystem using braid groups. D'une part, nous montrons que l'inversion de la fonction cyclage admet une solution polynomiale dans les groupes de Garside, qui sont une généralisation des groupes de tresses ; ceci permet de résoudre efficacement le problème des cyclages. D'autre part, le travail réalisé sur le problème de conjugaison et ses variantes met en relief le rôle joué par les générateurs aléatoires de tresses. Nous proposons un algorithme qui donne une factorisation du secret sous la forme d'un diviseur et d'un multiple. Ceci permet de définir deux nouvelles instances dont les secrets sont de taille réduite. De plus, nous exploitons la double structure de Garside des groupes de tresses afin d'améliorer l'efficacité de cette réduction. Nous observons que le choix du générateur aléatoire influe grandement sur la sécurité d'une instance et donnons plusieurs éléments constructifs et encourageants pour de futures recherches dans la conception d'un bon générateur aléatoire de tresses. This work deals with braid based cryptography. We study the conjugacy search problem and the cycling problem presented by K. H. Ko, S. J. Lee and al. At CRYPTO 2000 (LNCS 1880) in New public-key cryptosystem using braid groups. On the one hand, we give a polynomial time algorithm to inverse the cycling function in Garside group which are a generalization of braid groups ; that allows to solve practically the cycling problem. On the other hand, our work on the conjugacy search problem and its variants emphasizes the choice of random generator of braids in protocols. We give an algorithm that factorizes the secret into a divisor and a multiple. That allows to define two new conjugacy instances with shorter secrets. Moreover, we exploit the fact that a braid group has two distinct Garside structures to improve the efficiency of the reduction. We observe that the choice of random generators influences greatly the security of an instance and we give several constructive and encouraging elements for further research in the design of good random generator of braids
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Kudawoo, Ayaovi Dzifa. "Problèmes industriels de grande dimension en mécanique numérique du contact : performance, fiabilité et robustesse." Thesis, Aix-Marseille, 2012. http://www.theses.fr/2012AIXM4771/document.
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Ce travail de thèse concerne la mécanique numérique du contact entre solides déformables. Il s'agit de contribuer à l'amélioration de la performance, de la fiabilité et de la robustesse des algorithmes et des modèles numériques utilisés dans les codes éléments finis en particulier Code_Aster qui est un code libre développé par Électricité De France (EDF) pour ses besoins en ingénierie. L'objectif final est de traiter les problèmes industriels de grande dimension avec un temps de calcul optimisé. Pour parvenir à ces objectifs, les algorithmes et formulations doivent prendre en compte les difficultés liées à la mécanique non régulière à cause des lois de Signorini-Coulomb ainsi que la gestion des non linéarités dûes aux grandes déformations et aux comportements des matériaux étudiés.Le premier axe de ce travail est dédié à une meilleure compréhension de la formulation dite de « Lagrangien stabilisé » initialement implémentée dans le code. Il a été démontré l'équivalence entre cette formulation et la formulation bien connue de « Lagrangien augmenté ». Les caractéristiques mathématiques liées aux opérateurs discrets ont été précisées et une écriture énergétique globale a été trouvéeThis work deals with computational contact mechanics between deformable solids. The aim of this work is to improve the performance, the reliability and the robustness of the algorithms and numerical models set in Code_Aster which is finite element code developped by Électricité De France (EDF) for its engineering needs. The proposed algorithms are used to solve high dimensional industrial problems in order to optimize the computational running times. Several solutions techniques are available in the field of computational contact mechanics but they must take into account the difficulties coming from non-smooth aspects due to Signorini-Coulomb laws coupled to large deformations of bodies and material non linearities. Firstly the augmented Lagrangian formulation so-called « stabilized Lagrangian » is introduced. Successively, the mathematical properties of the discrete operators are highlighted and furthermore a novel energetic function is presented. Secondly the kinematical condition with regard to the normal unknowns are reinforced through unconstrained optimization techniques which result to a novel formulation which is so-called « non standard augmented Lagrangian formulation ». Three types of strategies are implemented in the code. The generalized Newton method is developped : it is a method in which all the non linearities are solved in one loop of iterations. The partial Newton method is an hybrid technique between the generalized Newton one and a fixed point method
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Kudawoo, Ayaovi Dzifa. "Problèmes industriels de grande dimension en mécanique numérique du contact : performance, fiabilité et robustesse." Phd thesis, Université de Provence - Aix-Marseille I, 2012. http://tel.archives-ouvertes.fr/tel-00773642.
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Ce travail de thèse concerne la mécanique numérique du contact entre solides déformables. Il s'agit de contribuer à l'amélioration de la performance, de la fiabilité et de la robustesse des algorithmes et des modèles numériques utilisés dans les codes éléments finis en particulier Code_Aster qui est un code libre développé par Électricité De France (EDF) pour ses besoins en ingénierie. L'objectif final est de traiter les problèmes industriels de grande dimension avec un temps de calcul optimisé. Pour parvenir à ces objectifs, les algorithmes et formulations doivent prendre en compte les difficultés liées à la mécanique non régulière à cause des lois de Signorini-Coulomb ainsi que la gestion des non linéarités dûes aux grandes déformations et aux comportements des matériaux étudiés. Le premier axe de ce travail est dédié à une meilleure compréhension de la formulation dite de " Lagrangien stabilisé " initialement implémentée dans le code. Il a été démontré l'équivalence entre cette formulation et la formulation bien connue de " Lagrangien augmenté ". Les caractéristiques mathématiques liées aux opérateurs discrets ont été précisées et une écriture énergétique globale a été trouvée. Une réflexion a été mise en oeuvre en vue de renforcer de manière faible la condition cinématique sur la normale dans la zone de contact via les techniques d'optimisation sans contraintes. La nouvelle formulation est dite de " Lagrangien augmenté non standard ". Trois nouvelles stratégies basées sur le Lagrangien augmenté ont été implémentées. Il s'agit de la méthode de Newton généralisée : c'est une méthode d'optimisation qui permet de résoudre toutes les non linéarités du problème en une seule boucle d'itérations. La méthode de Newton partielle est une méthode hybride entre la méthode historique du code appelée méthode de point fixe et la méthode de Newton généralisée. Enfin, on a mis en place une façon originale de traiter le cyclage : ce phénomène apparaît souvent au cours de la résolution du problème et il entraîne la perte de convergence des algorithmes. La stratégie nouvelle permet d'améliorer la robustesse des algorithmes.
Book chapters on the topic "Problème des cyclages"
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Letesson, Quentin, and Carl Knappett. "Processes and Patterns at the Macro-Scale: Crete and Beyond." In Minoan Architecture and Urbanism. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198793625.003.0019.
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Zooming out, we first reach the various regions that compose Crete (e.g. west Crete, Mesara, north-central Crete, Malia-Lasithi zone, Mirabello Bay area, east Crete) and then the whole island itself. This is the macro-scale where settlement patterns can be observed and ‘which may see low-level exchange, competition, close affiliations; a whole range of potential scenarios, including “states”’ (Knappett 2012: 395). Further out, we might speak of the global scale, that of the supra-regional, with connections beyond the island to the Cyclades, Asia Minor, the Greek mainland, and so on. Although we have a general idea of how settlement patterns evolved during the Cretan Bronze Age (Driessen 2001; see also Bevan 2010 for an up-to-date synthesis), limitations at the micro- and meso-scale clearly also constrain our understanding of the macro-scale. Nevertheless, starting with Sir Arthur Evans (1928: 60–92), who was particularly interested in roads and how they connected specific settlements both in central and east Crete to support his view of Knossian overarching power (see also Warren 1994: 189, n.3), an interest in broader regional dynamics and top-down approaches to sociopolitical complexity was always prominent in Aegean archaeology (Cherry 1984; Renfrew 1972; Renfrew and Cherry 1986). This focus on site hierarchies has motivated a broad range of studies, from comparative material culture analysis (e.g. Knappett 1999) to surface surveys and associated tests which provided invaluable information on road networks (e.g. Müller 1991; Tzedakis et al. 1989; Tzedakis et al. 1990) and settlement distribution (for extensive bibliography and synthesis, see Driessen 2001; Whitelaw 2012). Although recent surveys clearly increase the temporal and spatial resolution of our data sets (e.g. Haggis 2005; Watrous 2012; Whitelaw, Bredaki, and Vasilakis 2006–7), they still have considerable gaps. For example, compared to central and east Crete, relatively few sites have been identified in the west of the island. This problem was recently tackled by Bevan and Wilson (2013), who devised a model for exploring settlement locations, hierarchies, and interconnections despite our incomplete dataset (see also chapters 12 and 15).
Conference papers on the topic "Problème des cyclages"
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Kakurina, G. V., E. S. Kolegova, O. V. Cheremisina, A. A. Zavyalov, D. A. Shishkin, I. V. Kondakova, and E. L. Choinzonov. "Adenylyl cyclase-associated protein 1 in metastasis of squamous cell carcinoma of the head and neck and non-small cell lung cancer." In PHYSICS OF CANCER: INTERDISCIPLINARY PROBLEMS AND CLINICAL APPLICATIONS (PC’16): Proceedings of the International Conference on Physics of Cancer: Interdisciplinary Problems and Clinical Applications 2016. Author(s), 2016. http://dx.doi.org/10.1063/1.4960242.
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