Search

Your search keyword '"Mellet, N."' showing total 46 results
Start Over Author "Mellet, N."
46 results on '"Mellet, N."'

1. Thermal stability and long term hydrogen/deuterium release from soft to hard amorphous carbon layers analyzed using in-situ Raman spectroscopy. Comparison with Tore Supra deposits

Author

Pardanaud, C., Martin, C., Giacometti, G., Mellet, N., Pégourié, B., and Roubin, P.

Subjects
Physics - Chemical Physics
Abstract

The thermal stability of 200 nm thick plasma enhanced chemical vapor deposited a-C:H and a-C:D layers ranging from soft to hard layers has been studied and compared to that of deposits collected on the Tore Supra tokamak plasma facing components by means of in-situ Raman spectroscopy. Linear ramp heating and long term isotherms (from several minutes to 21 days) have been performed and correlations between spectrometric parameters have been found. The information obtained on the sp 2 clustering has been investigated by comparing the G band shift and the 514 nm photon absorption evolution due to the thermal treatment of the layer. The effects of isotopic substitution have also been investigated., Comment: appears in Thin Solid Films, Elsevier, 2014

Published
2015
Full Text
View/download PDF

5. Parallelization of the LEMan Code with MPI and OpenMP

Author

Mellet, N., Cooper, W. A., Hutchison, David, Series editor, Kanade, Takeo, Series editor, Kittler, Josef, Series editor, Kleinberg, Jon M., Series editor, Mattern, Friedemann, Series editor, Mitchell, John C., Series editor, Naor, Moni, Series editor, Nierstrasz, Oscar, Series editor, Pandu Rangan, C., Series editor, Steffen, Bernhard, Series editor, Sudan, Madhu, Series editor, Terzopoulos, Demetri, Series editor, Tygar, Doug, Series editor, Vardi, Moshe Y., Series editor, Weikum, Gerhard, Series editor, Dou, Yong, editor, Gruber, Ralf, editor, and Joller, Josef M., editor

Published
2009
Full Text
View/download PDF

8. Implementation of drift velocities and currents in SOLEDGE2D-EIRENE

Author

Bufferand, Hugo, Baudoin, C, Bucalossi, J, Ciraolo, G, Denis, Julien, Fedorczak, Nicolas, Galassi, D, Ghendrih, Philippe, Leybros, R, Marandet, Y, Mellet, N, Morales, J, Nace, N, Serre, E, Tamain, Patrick, Valentinuzzi, M, Institut de Recherche sur la Fusion par confinement Magnétique (IRFM), Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Laboratoire de Mécanique, Modélisation et Procédés Propres (M2P2), Centre National de la Recherche Scientifique (CNRS)-École Centrale de Marseille (ECM)-Aix Marseille Université (AMU), Physique des interactions ioniques et moléculaires (PIIM), Aix Marseille Université (AMU)-Centre National de la Recherche Scientifique (CNRS), Ecole Polytechnique Fédérale de Lausanne (EPFL), ANR-10-EQPX-0029,EQUIP@MESO,Equipement d'excellence de calcul intensif de Mesocentres coordonnés - Tremplin vers le calcul petaflopique et l'exascale(2010), European Project: 633053,H2020,EURATOM-Adhoc-2014-20,EUROfusion(2014), and Aix Marseille Université (AMU)-École Centrale de Marseille (ECM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Edge plasma, [PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], Edge modeling, Edge plasma, Drifts, Edge modeling, Drifts
Abstract

International audience; In order to improve cross-field transport description, drifts and currents have been implemented in SOLEDGE2D-EIRENE. The derivation of an equation for the electric potential is recalled. The resolution of current equation is tested in a simple slab case. WEST divertor simulations in forward-B and reverse-B fields are also discussed. A significant increase of ExB shear is observed in the forward-B configuration that could explain a favorable L-H transition in this case.

Published
2017

9. Plasma–wall interaction studies within the EUROfusion consortium: progress on plasma-facing components development and qualification

Author

Brezinsek, S., primary, Coenen, J.W., additional, Schwarz-Selinger, T., additional, Schmid, K., additional, Kirschner, A., additional, Hakola, A., additional, Tabares, F.L., additional, van der Meiden, H.J., additional, Mayoral, M.-L., additional, Reinhart, M., additional, Tsitrone, E., additional, Ahlgren, T., additional, Aints, M., additional, Airila, M., additional, Almaviva, S., additional, Alves, E., additional, Angot, T., additional, Anita, V., additional, Arredondo Parra, R., additional, Aumayr, F., additional, Balden, M., additional, Bauer, J., additional, Ben Yaala, M., additional, Berger, B.M., additional, Bisson, R., additional, Björkas, C., additional, Bogdanovic Radovic, I., additional, Borodin, D., additional, Bucalossi, J., additional, Butikova, J., additional, Butoi, B., additional, Čadež, I., additional, Caniello, R., additional, Caneve, L., additional, Cartry, G., additional, Catarino, N., additional, Čekada, M., additional, Ciraolo, G., additional, Ciupinski, L., additional, Colao, F., additional, Corre, Y., additional, Costin, C., additional, Craciunescu, T., additional, Cremona, A., additional, De Angeli, M., additional, de Castro, A., additional, Dejarnac, R., additional, Dellasega, D., additional, Dinca, P., additional, Dittmar, T., additional, Dobrea, C., additional, Hansen, P., additional, Drenik, A., additional, Eich, T., additional, Elgeti, S., additional, Falie, D., additional, Fedorczak, N., additional, Ferro, Y., additional, Fornal, T., additional, Fortuna-Zalesna, E., additional, Gao, L., additional, Gasior, P., additional, Gherendi, M., additional, Ghezzi, F., additional, Gosar, Ž., additional, Greuner, H., additional, Grigore, E., additional, Grisolia, C., additional, Groth, M., additional, Gruca, M., additional, Grzonka, J., additional, Gunn, J.P., additional, Hassouni, K., additional, Heinola, K., additional, Höschen, T., additional, Huber, S., additional, Jacob, W., additional, Jepu, I., additional, Jiang, X., additional, Jogi, I., additional, Kaiser, A., additional, Karhunen, J., additional, Kelemen, M., additional, Köppen, M., additional, Koslowski, H.R., additional, Kreter, A., additional, Kubkowska, M., additional, Laan, M., additional, Laguardia, L., additional, Lahtinen, A., additional, Lasa, A., additional, Lazic, V., additional, Lemahieu, N., additional, Likonen, J., additional, Linke, J., additional, Litnovsky, A., additional, Linsmeier, Ch., additional, Loewenhoff, T., additional, Lungu, C., additional, Lungu, M., additional, Maddaluno, G., additional, Maier, H., additional, Makkonen, T., additional, Manhard, A., additional, Marandet, Y., additional, Markelj, S., additional, Marot, L., additional, Martin, C., additional, Martin-Rojo, A.B., additional, Martynova, Y., additional, Mateus, R., additional, Matveev, D., additional, Mayer, M., additional, Meisl, G., additional, Mellet, N., additional, Michau, A., additional, Miettunen, J., additional, Möller, S., additional, Morgan, T.W., additional, Mougenot, J., additional, Mozetič, M., additional, Nemanič, V., additional, Neu, R., additional, Nordlund, K., additional, Oberkofler, M., additional, Oyarzabal, E., additional, Panjan, M., additional, Pardanaud, C., additional, Paris, P., additional, Passoni, M., additional, Pegourie, B., additional, Pelicon, P., additional, Petersson, P., additional, Piip, K., additional, Pintsuk, G., additional, Pompilian, G.O., additional, Popa, G., additional, Porosnicu, C., additional, Primc, G., additional, Probst, M., additional, Räisänen, J., additional, Rasinski, M., additional, Ratynskaia, S., additional, Reiser, D., additional, Ricci, D., additional, Richou, M., additional, Riesch, J., additional, Riva, G., additional, Rosinski, M., additional, Roubin, P., additional, Rubel, M., additional, Ruset, C., additional, Safi, E., additional, Sergienko, G., additional, Siketic, Z., additional, Sima, A., additional, Spilker, B., additional, Stadlmayr, R., additional, Steudel, I., additional, Ström, P., additional, Tadic, T., additional, Tafalla, D., additional, Tale, I., additional, Terentyev, D., additional, Terra, A., additional, Tiron, V., additional, Tiseanu, I., additional, Tolias, P., additional, Tskhakaya, D., additional, Uccello, A., additional, Unterberg, B., additional, Uytdenhoven, I., additional, Vassallo, E., additional, Vavpetič, P., additional, Veis, P., additional, Velicu, I.L., additional, Vernimmen, J.W.M., additional, Voitkans, A., additional, von Toussaint, U., additional, Weckmann, A., additional, Wirtz, M., additional, Založnik, A., additional, and Zaplotnik, R., additional

Published
2017
Full Text
View/download PDF

12. H-mode WEST tungsten divertor operation: deuterium and nitrogen seeded simulations with SOLEDGE2D-EIRENE

Author

Ciraolo, G., primary, Bufferand, H., additional, Bucalossi, J., additional, Ghendrih, Ph., additional, Tamain, P., additional, Marandet, Y., additional, Valentinuzzi, M., additional, Denis, J., additional, Fedorczak, N., additional, Hodille, E., additional, Mellet, N., additional, Pegourie, B., additional, Grisolia, C., additional, Bourdelle, C., additional, Tsitrone, E., additional, Galassi, D., additional, Leybros, R., additional, Giorgiani, G., additional, and Serre, E., additional

Published
2017
Full Text
View/download PDF

20. Integrated modeling for ion cyclotron resonant heating in toroidal systems

Author

Jucker, M., Graves, J. P., Cooper, W. A., Mellet, N., Johnson, Thomas, Brunner, S., Jucker, M., Graves, J. P., Cooper, W. A., Mellet, N., Johnson, Thomas, and Brunner, S.

Abstract

An integrated model capable of self-consistent Ion Cyclotron Resonant Heating (ICRH) simulations has been developed. This model includes both full shaping and pressure effects, warm contributions to the dielectric tensor, pressure anisotropy and finite orbit width. It evolves the equilibrium, wave field and full hot particle distribution function until a self-consistent solution is found. This article describes the workings of the three codes VMEC, LEMan and VENUS and how they are linked for iterated computations in a code package we have named SCENIC. The package is thoroughly tested and it is demonstrated that a number of iterations have to be performed in order to find a consistent solution. Since the formulation of the problem can treat general 3D systems, we show a quasi-axisymmetric stellarator low power test case, and then concentrate on experimentally relevant Joint European Torus (JET) 2D configurations., QC 20110524

Published
2011
Full Text
View/download PDF

21. Science and technology research and development in support to ITER and the Broader Approach at CEA

Author

Bécoulet, A., primary, Hoang, G.T., additional, Abiteboul, J., additional, Achard, J., additional, Alarcon, T., additional, Alba-Duran, J., additional, Allegretti, L., additional, Allfrey, S., additional, Amiel, S., additional, Ané, J.M., additional, Aniel, T., additional, Antar, G., additional, Argouarch, A., additional, Armitano, A., additional, Arnaud, J., additional, Arranger, D., additional, Artaud, J.F., additional, Audisio, D., additional, Aumeunier, M., additional, Autissier, E., additional, Azcona, L., additional, Back, A., additional, Bahat, A., additional, Bai, X., additional, Baiocchi, B., additional, Balaguer, D., additional, Balme, S., additional, Balorin, C., additional, Barana, O., additional, Barbier, D., additional, Barbuti, A., additional, Basiuk, V., additional, Baulaigue, O., additional, Bayetti, P., additional, Baylard, C., additional, Beaufils, S., additional, Beaute, A., additional, Bécoulet, M., additional, Bej, Z., additional, Benkadda, S., additional, Benoit, F., additional, Berger-By, G., additional, Bernard, J.M., additional, Berne, A., additional, Bertrand, B., additional, Bertrand, E., additional, Beyer, P., additional, Bigand, A., additional, Bonhomme, G., additional, Borel, G., additional, Boron, A., additional, Bottereau, C., additional, Bottollier-Curtet, H., additional, Bouchand, C., additional, Bouquey, F., additional, Bourdelle, C., additional, Bourg, J., additional, Bourmaud, S., additional, Brémond, S., additional, Bribiesca Argomedo, F., additional, Brieu, M., additional, Brun, C., additional, Bruno, V., additional, Bucalossi, J., additional, Bufferand, H., additional, Buravand, Y., additional, Cai, L., additional, Cantone, V., additional, Cantone, B., additional, Caprin, E., additional, Cartier-Michaud, T., additional, Castagliolo, A., additional, Belo, J., additional, Catherine-Dumont, V., additional, Caulier, G., additional, Chaix, J., additional, Chantant, M., additional, Chatelier, M., additional, Chauvin, D., additional, Chenevois, J., additional, Chouli, B., additional, Christin, L., additional, Ciazynski, D., additional, Ciraolo, G., additional, Clairet, F., additional, Clapier, R., additional, Cloez, H., additional, Coatanea-Gouachet, M., additional, Colas, L., additional, Colledani, G., additional, Commin, L., additional, Coquillat, P., additional, Corbel, E., additional, Corre, Y., additional, Cottet, J., additional, Cottier, P., additional, Courtois, X., additional, Crest, I., additional, Dachicourt, R., additional, Dapena Febrer, M., additional, Daumas, C., additional, de Esch, H.P.L., additional, De Gentile, B., additional, Dechelle, C., additional, Decker, J., additional, Decool, P., additional, Deghaye, V., additional, Delaplanche, J., additional, Delchambre-Demoncheaux, E., additional, Delpech, L., additional, Desgranges, C., additional, Devynck, P., additional, Dias Pereira Bernardo, J., additional, Dif-Pradalier, G., additional, Doceul, L., additional, Dong, Y., additional, Douai, D., additional, Dougnac, H., additional, Dubuit, N., additional, Duchateau, J.-L., additional, Ducobu, L., additional, Dugue, B., additional, Dumas, N., additional, Dumont, R., additional, Durocher, A., additional, Duthoit, F., additional, Ekedahl, A., additional, Elbeze, D., additional, Escarguel, A., additional, Escop, J., additional, Faïsse, F., additional, Falchetto, G., additional, Farjon, J., additional, Faury, M., additional, Fedorzack, N., additional, Féjoz, P., additional, Fenzi, C., additional, Ferlay, F., additional, Fiet, P., additional, Firdaouss, M., additional, Francisquez, M., additional, Franel, B., additional, Frauche, J., additional, Frauel, Y., additional, Futtersack, R., additional, Garbet, X., additional, Garcia, J., additional, Gardarein, J., additional, Gargiulo, L., additional, Garibaldi, P., additional, Garin, P., additional, Garnier, D., additional, Gauthier, E., additional, Gaye, O., additional, Geraud, A., additional, Gerome, M., additional, Gervaise, V., additional, Geynet, M., additional, Ghendrih, P., additional, Giacalone, I., additional, Gibert, S., additional, Gil, C., additional, Ginoux, S., additional, Giovannangelo, L., additional, Girard, S., additional, Giruzzi, G., additional, Goletto, C., additional, Goncalves, R., additional, Gonde, R., additional, Goniche, M., additional, Goswami, R., additional, Grand, C., additional, Grandgirard, V., additional, Gravil, B., additional, Grisolia, C., additional, Gros, G., additional, Grosman, A., additional, Guigue, J., additional, Guilhem, D., additional, Guillemaut, C., additional, Guillerminet, B., additional, Guimaraes Filho, Z., additional, Guirlet, R., additional, Gunn, J. P., additional, Gurcan, O., additional, Guzman, F., additional, Hacquin, S., additional, Hariri, F., additional, Hasenbeck, F., additional, Hatchressian, J.C., additional, Hennequin, P., additional, Hernandez, C., additional, Hertout, P., additional, Heuraux, S., additional, Hillairet, J., additional, Honore, C., additional, Hornung, G., additional, Houry, M., additional, Hunstad, I., additional, Hutter, T., additional, Huynh, P., additional, Icard, V., additional, Imbeaux, F., additional, Irishkin, M., additional, Isoardi, L., additional, Jacquinot, J., additional, Jacquot, J., additional, Jiolat, G., additional, Joanny, M., additional, Joffrin, E., additional, Johner, J., additional, Joubert, P., additional, Jourd'Heuil, L., additional, Jouve, M., additional, Junique, C., additional, Keller, D., additional, Klepper, C., additional, Kogut, D., additional, Kubič, M., additional, Labassé, F., additional, Lacroix, B., additional, Lallier, Y., additional, Lamaison, V., additional, Lambert, R., additional, Larroque, S., additional, Latu, G., additional, Lausenaz, Y., additional, Laviron, C., additional, Le, R., additional, Le Luyer, A., additional, Le Niliot, C., additional, Le Tonqueze, Y., additional, Lebourg, P., additional, Lefevre, T., additional, Leroux, F., additional, Letellier, L., additional, Li, Y., additional, Lipa, M., additional, Lister, J., additional, Litaudon, X., additional, Liu, F., additional, Loarer, T., additional, Lombard, G., additional, Lotte, P., additional, Lozano, M., additional, Lucas, J., additional, Lütjens, H., additional, Magaud, P., additional, Maget, P., additional, Magne, R., additional, Mahieu, J.-F., additional, Maini, P., additional, Malard, P., additional, Manenc, L., additional, Marandet, Y., additional, Marbach, G., additional, Marechal, J.-L., additional, Marfisi, L., additional, Marle, M., additional, Martin, C., additional, Martin, V., additional, Martin, G., additional, Martinez, A., additional, Martino, P., additional, Masset, R., additional, Mazon, D., additional, Mellet, N., additional, Mercadier, L., additional, Merle, A., additional, Meshcheriakov, D., additional, Messina, P., additional, Meyer, O., additional, Millon, L., additional, Missirlian, M., additional, Moerel, J., additional, Molina, D., additional, Mollard, P., additional, Moncada, V., additional, Monier-Garbet, P., additional, Moreau, D., additional, Moreau, M., additional, Moreau, P., additional, Morel, P., additional, Moriyama, T., additional, Motassim, Y., additional, Mougeolle, G., additional, Moulton, D., additional, Moureau, G., additional, Mouyon, D., additional, Naim Habib, M., additional, Nardon, E., additional, Négrier, V., additional, Nemeth, J., additional, Nguyen, C., additional, Nguyen, M., additional, Nicolas, L., additional, Nicolas, T., additional, Nicollet, S., additional, Nilsson, E., additional, N'Konga, B., additional, Noel, F., additional, Nooman, A., additional, Norscini, C., additional, Nouailletas, R., additional, Oddon, P., additional, Ohsako, T., additional, Orain, F., additional, Ottaviani, M., additional, Pagano, M., additional, Palermo, F., additional, Panayotis, S., additional, Parrat, H., additional, Pascal, J.-Y., additional, Passeron, C., additional, Pastor, P., additional, Patterlini, J., additional, Pavy, K., additional, Pecquet, A.-L., additional, Pégourié, B., additional, Peinturier, C., additional, Pelletier, T., additional, Peluso, B., additional, Petrzilka, V., additional, Peysson, Y., additional, Pignoly, E., additional, Pirola, R., additional, Pocheau, C., additional, Poitevin, E., additional, Poli, V., additional, Poli, S., additional, Pompon, F., additional, Porchy, I., additional, Portafaix, C., additional, Preynas, M., additional, Prochet, P., additional, Prou, M., additional, Ratnani, A., additional, Raulin, D., additional, Ravenel, N., additional, Renard, S., additional, Ricaud, B., additional, Richou, M., additional, Ritz, G., additional, Roche, H., additional, Roubin, P., additional, Roux, C., additional, Ruiz, K., additional, Sabathier, F., additional, Sabot, R., additional, Saille, A., additional, Saint-Laurent, F., additional, Sakamoto, R., additional, Salasca, S., additional, Salmon, T., additional, Samaille, F., additional, Sanchez, S., additional, Santagiustina, A., additional, Saoutic, B., additional, Sarazin, Y., additional, Sardain, P., additional, Schlosser, J., additional, Schneider, M., additional, Schwob, J., additional, Segui, J., additional, Seguin, N., additional, Selig, G., additional, Serret, D., additional, Signoret, J., additional, Simonin, A., additional, Soldaini, M., additional, Soler, B., additional, Soltane, C., additional, Song, S., additional, Sourbier, F., additional, Sparagna, J., additional, Spitz, P., additional, Spuig, P., additional, Storelli, A., additional, Strugarek, A., additional, Tamain, P., additional, Tena, M., additional, Theis, J., additional, Thomine, O., additional, Thouvenin, D., additional, Torre, A., additional, Toulouse, L., additional, Travère, J., additional, Tsitrone, E., additional, Turck, B., additional, Urban, J., additional, Vallet, J.-C., additional, Vallory, J., additional, Valognes, A., additional, Van Helvoirt, J., additional, Vartanian, S., additional, Verger, J.-M., additional, Vermare, L., additional, Vermare, C., additional, Vezinet, D., additional, Vicente, K., additional, Vidal, J., additional, Vignal, N., additional, Vigne, T., additional, Villecroze, F., additional, Villedieu, E., additional, Vincent, B., additional, Volpe, B., additional, Volpe, D., additional, Volpe, R., additional, Wagrez, J., additional, Wang, H., additional, Wauters, T., additional, Wintersdorff, O., additional, Wittebol, E., additional, Zago, B., additional, Zani, L., additional, Zarzoso, D., additional, Zhang, Y., additional, Zhong, W., additional, and Zou, X.L., additional

Published
2013
Full Text
View/download PDF

22. Screening of resonant magnetic perturbations by flows in tokamaks

Author

Becoulet, M., primary, Orain, F., additional, Maget, P., additional, Mellet, N., additional, Garbet, X., additional, Nardon, E., additional, Huysmans, G.T.A., additional, Casper, T., additional, Loarte, A., additional, Cahyna, P., additional, Smolyakov, A., additional, Waelbroeck, F.L., additional, Schaffer, M., additional, Evans, T., additional, Liang, Y., additional, Schmitz, O., additional, Beurskens, M., additional, Rozhansky, V., additional, and Kaveeva, E., additional

Published
2012
Full Text
View/download PDF

23. Contribution of Tore Supra in preparation of ITER

Author

Saoutic, B., primary, Abiteboul, J., additional, Allegretti, L., additional, Allfrey, S., additional, Ané, J.M., additional, Aniel, T., additional, Argouarch, A., additional, Artaud, J.F., additional, Aumenier, M.H., additional, Balme, S., additional, Basiuk, V., additional, Baulaigue, O., additional, Bayetti, P., additional, Bécoulet, A., additional, Bécoulet, M., additional, Benkadda, M.S., additional, Benoit, F., additional, Berger-by, G., additional, Bernard, J.M., additional, Bertrand, B., additional, Beyer, P., additional, Bigand, A., additional, Blum, J., additional, Boilson, D., additional, Bonhomme, G., additional, Bottollier-Curtet, H., additional, Bouchand, C., additional, Bouquey, F., additional, Bourdelle, C., additional, Bourmaud, S., additional, Brault, C., additional, Brémond, S., additional, Brosset, C., additional, Bucalossi, J., additional, Buravand, Y., additional, Cara, P., additional, Catherine-Dumont, V., additional, Casati, A., additional, Chantant, M., additional, Chatelier, M., additional, Chevet, G., additional, Ciazynski, D., additional, Ciraolo, G., additional, Clairet, F., additional, Coatanea-Gouachet, M., additional, Colas, L., additional, Commin, L., additional, Corbel, E., additional, Corre, Y., additional, Courtois, X., additional, Dachicourt, R., additional, Dapena Febrer, M., additional, Davi Joanny, M., additional, Daviot, R., additional, De Esch, H., additional, Decker, J., additional, Decool, P., additional, Delaporte, P., additional, Delchambre, E., additional, Delmas, E., additional, Delpech, L., additional, Desgranges, C., additional, Devynck, P., additional, Dittmar, T., additional, Doceul, L., additional, Douai, D., additional, Dougnac, H., additional, Duchateau, J.L., additional, Dugué, B., additional, Dumas, N., additional, Dumont, R., additional, Durocher, A., additional, Duthoit, F.X., additional, Ekedahl, A., additional, Elbeze, D., additional, El Khaldi, M., additional, Escourbiac, F., additional, Faisse, F., additional, Falchetto, G., additional, Farge, M., additional, Farjon, J.L., additional, Faury, M., additional, Fedorczak, N., additional, Fenzi-Bonizec, C., additional, Firdaouss, M., additional, Frauel, Y., additional, Garbet, X., additional, Garcia, J., additional, Gardarein, J.L., additional, Gargiulo, L., additional, Garibaldi, P., additional, Gauthier, E., additional, Gaye, O., additional, Géraud, A., additional, Geynet, M., additional, Ghendrih, P., additional, Giacalone, I., additional, Gibert, S., additional, Gil, C., additional, Giruzzi, G., additional, Goniche, M., additional, Grandgirard, V., additional, Grisolia, C., additional, Gros, G., additional, Grosman, A., additional, Guigon, R., additional, Guilhem, D., additional, Guillerminet, B., additional, Guirlet, R., additional, Gunn, J., additional, Gurcan, O., additional, Hacquin, S., additional, Hatchressian, J.C., additional, Hennequin, P., additional, Hernandez, C., additional, Hertout, P., additional, Heuraux, S., additional, Hillairet, J., additional, Hoang, G.T., additional, Honore, C., additional, Houry, M., additional, Hutter, T., additional, Huynh, P., additional, Huysmans, G., additional, Imbeaux, F., additional, Joffrin, E., additional, Johner, J., additional, Jourd'Heuil, L., additional, Katharria, Y.S., additional, Keller, D., additional, Kim, S.H., additional, Kocan, M., additional, Kubic, M., additional, Lacroix, B., additional, Lamaison, V., additional, Latu, G., additional, Lausenaz, Y., additional, Laviron, C., additional, Leroux, F., additional, Letellier, L., additional, Lipa, M., additional, Litaudon, X., additional, Loarer, T., additional, Lotte, P., additional, Madeleine, S., additional, Magaud, P., additional, Maget, P., additional, Magne, R., additional, Manenc, L., additional, Marandet, Y., additional, Marbach, G., additional, Maréchal, J.L., additional, Marfisi, L., additional, Martin, C., additional, Martin, G., additional, Martin, V., additional, Martinez, A., additional, Martins, J.P., additional, Masset, R., additional, Mazon, D., additional, Mellet, N., additional, Mercadier, L., additional, Merle, A., additional, Meshcheriakov, D., additional, Meyer, O., additional, Million, L., additional, Missirlian, M., additional, Mollard, P., additional, Moncada, V., additional, Monier-Garbet, P., additional, Moreau, D., additional, Moreau, P., additional, Morini, L., additional, Nannini, M., additional, Naiim Habib, M., additional, Nardon, E., additional, Nehme, H., additional, Nguyen, C., additional, Nicollet, S., additional, Nouilletas, R., additional, Ohsako, T., additional, Ottaviani, M., additional, Pamela, S., additional, Parrat, H., additional, Pastor, P., additional, Pecquet, A.L., additional, Pégourié, B., additional, Peysson, Y., additional, Porchy, I., additional, Portafaix, C., additional, Preynas, M., additional, Prou, M., additional, Raharijaona, J.M., additional, Ravenel, N., additional, Reux, C., additional, Reynaud, P., additional, Richou, M., additional, Roche, H., additional, Roubin, P., additional, Sabot, R., additional, Saint-Laurent, F., additional, Salasca, S., additional, Samaille, F., additional, Santagiustina, A., additional, Sarazin, Y., additional, Semerok, A., additional, Schlosser, J., additional, Schneider, M., additional, Schubert, M., additional, Schwander, F., additional, Ségui, J.L., additional, Selig, G., additional, Sharma, P., additional, Signoret, J., additional, Simonin, A., additional, Song, S., additional, Sonnendruker, E., additional, Sourbier, F., additional, Spuig, P., additional, Tamain, P., additional, Tena, M., additional, Theis, J.M., additional, Thouvenin, D., additional, Torre, A., additional, Travère, J.M., additional, Tsitrone, E., additional, Vallet, J.C., additional, Van Der Plas, E., additional, Vatry, A., additional, Verger, J.M., additional, Vermare, L., additional, Villecroze, F., additional, Villegas, D., additional, Volpe, R., additional, Vulliez, K., additional, Wagrez, J., additional, Wauters, T., additional, Zani, L., additional, Zarzoso, D., additional, and Zou, X.L., additional

Published
2011
Full Text
View/download PDF

24. Modelling of (2,1) NTM dynamics with flow in JET advanced scenarios

Author

Maget, P., primary, Lütjens, H., additional, Brix, M., additional, Buratti, P., additional, Buttery, R.J., additional, Coelho, R., additional, Halpern, F., additional, Hawkes, N., additional, Jenkins, I., additional, Challis, C., additional, Giroud, C., additional, Litaudon, X., additional, Mailloux, J., additional, Mellet, N., additional, and Meshcheriakov, D., additional

Published
2011
Full Text
View/download PDF

30. A Full-Wave Solution of the Maxwell’s Equations in 3D Plasmas.

Author

Popovich, P., Mellet, N., Villard, L., and Cooper, W. A.

Subjects
*MAXWELL equations, *ELECTROMAGNETIC theory, *WAVE equation, *PARTIAL differential equations, *DIELECTRICS, *CYCLOTRONS
Abstract

We present a new global solver for the Maxwell’s equations in stellarator plasmas (LEMan). The 3D geometrical effects are fully taken into account, no assumption on the wavelength is made. The full cold plasma dielectric tensor including finite electron mass is implemented, extension to the kinetic model is under development. The wave equation is discretised with finite elements (linear or cubic) radially and Fourier decomposition in the poloidal and toroidal angles. Special care is taken to correctly treat the problem near the magnetic axis. Unicity of the solution, gauge condition and the energy conservation are ensured. Some results and benchmarks for the Alfvén and ion cyclotron frequency ranges are presented. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

Published
2005
Full Text
View/download PDF

31. Recent JET Experiments on Alfven Eigenmodes with Intermediate Toroidal Mode Numbers: Measurements and Modelling

Author

Testa, D., Mellet, N., Panis, T., Sharapov, S. E., Spong, D., Blanchard, P., Carfantan, H., Fasoli, A., Goodyear, A., and Contributors, JET-EFDA

Subjects
JET tokamak, Physics::Plasma Physics, Alfven Eigenmodes
Abstract

This paper reports the results of recent experiments performed on the JET tokamak on Alfven Eigenmodes (AEs) with toroidal mode number (n) in the range n=3-15. The stability properties and the use of these medium-n AEs for diagnostic purposes is investigated experimentally using a new set of compact in-vessel antennas, providing a direct and real-time measurement of the frequency, damping rate and amplitude for each individual toroidal mode number. First, we report on the development of a new algorithm for mode detection and discrimination using the Sparse Signal Representation theory. The speed and accuracy of this algorithm has made it possible to use it in our plant control software, allowing real-time tracking of individual modes during the evolution of the plasma background on a 1ms time scale. Second, we report the first quantitative analysis of the measurements of the damping rate for stable n=3 and n=7 Toroidal AEs as function of the plasma elongation. The damping rate for these modes increases for increasing elongation, as previously found in JET for n=0-2 AEs. A theoretical analysis of these JET data has been performed with the LEMan, CASTOR and TAEFL codes. The LEMan and TAEFL results are in good agreement with the measurements for all magnetic configurations where there is only a minor up/down asymmetry in the plasma poloidal cross-section. The CASTOR results indicate that continuum damping is not the only mechanism affecting the stability of these medium-n AEs. The diagnostic potential of these modes has being confirmed during the recent gas change-over experiment, where independent measurements of the effective plasma isotope ratio AEFF have been provided in addition to the more routinely employed spectroscopic and gas-balance ones. These data shows a slight difference in the measurement of AEFF when using n7 modes, suggesting a radial dependence in the effective plasma isotope ratio.

32. Plasma-wall interaction studies within the EUROfusion consortium

Author

Brezinsek, S., Coenen, J. W., Schwarz-Selinger, T., Schmid, K., Kirschner, A., Hakola, A., Tabares, F. L., Meiden, H. J., Mayoral, M. L., Reinhart, M., Tsitrone, E., Ahlgren, T., Aints, M., Airila, M., Almaviva, S., Alves, E., Angot, T., Anita, V., Arredondo Parra, R., Aumayr, F., Balden, M., Bauer, J., Ben Yaala, M., Berger, B. M., Bisson, R., Björkas, C., Bogdanovic Radovic, I., Borodin, D., Bucalossi, J., Butikova, J., Butoi, B., Čadež, I., Caniello, R., Caneve, L., Cartry, G., Catarino, N., Čekada, M., Ciraolo, G., Ciupinski, L., Colao, F., Corre, Y., Costin, C., Craciunescu, T., Cremona, A., Angeli, M., Castro, A., Dejarnac, R., Dellasega, D., Dinca, P., Dittmar, T., Dobrea, C., Hansen, P., Drenik, A., Eich, T., Elgeti, S., Falie, D., Fedorczak, N., Ferro, Y., Fornal, T., Fortuna-Zalesna, E., Gao, L., Gasior, P., Gherendi, M., Ghezzi, F., Gosar, Greuner, H., Grigore, E., Grisolia, C., Groth, M., Gruca, M., Grzonka, J., Gunn, J. P., Hassouni, K., Heinola, K., Höschen, T., Huber, S., Jacob, W., Jepu, I., Jiang, X., Jogi, I., Kaiser, A., Karhunen, J., Kelemen, M., Köppen, M., Koslowski, H. R., Kreter, A., Kubkowska, M., Laan, M., Laguardia, L., Lahtinen, A., Lasa, A., Lazic, V., Lemahieu, N., Likonen, J., Linke, J., Litnovsky, A., Linsmeier, Ch, Loewenhoff, T., Lungu, C., Lungu, M., Maddaluno, G., Maier, H., Makkonen, T., Manhard, A., Marandet, Y., Markelj, S., Marot, L., Martin Oberkofler, Martin-Rojo, A. B., Martynova, Y., Mateus, R., Matveev, D., Mayer, M., Meisl, G., Mellet, N., Michau, A., Miettunen, J., Möller, S., Morgan, T. W., Mougenot, J., Mozetič, M., Nemanič, V., Neu, R., Nordlund, K., Oberkofler, M., Oyarzabal, E., Panjan, M., Pardanaud, C., Paris, P., Passoni, M., Pegourie, B., Pelicon, P., Petersson, P., Piip, K., Pintsuk, G., Pompilian, G. O., Popa, G., Porosnicu, C., Primc, G., Probst, M., Räisänen, J., Rasinski, M., Ratynskaia, S., Reiser, D., Ricci, D., Richou, M., Riesch, J., Riva, G., Rosinski, M., Roubin, P., Rubel, M., Ruset, C., Safi, E., Sergienko, G., Siketic, Z., Sima, A., Spilker, B., Stadlmayr, R., Steudel, I., Ström, P., Tadic, T., Tafalla, D., Tale, I., Terentyev, D., Terra, A., Tiron, V., Tiseanu, I., Tolias, P., Tskhakaya, D., Uccello, A., Unterberg, B., Uytdenhoven, I., Vassallo, E., Vavpetič, P., Veis, P., Velicu, I. L., Vernimmen, J. W. M., Voitkans, A., Toussaint, U., Weckmann, A., Wirtz, M., Založnik, A., Zaplotnik, R., Jülich Research Centre, Max Planck Institute for Plasma Physics, VTT Technical Research Centre of Finland, CIEMAT, Dutch Institute for Fundamental Energy Research, Culham Science Centre, CEA, University of Helsinki, University of Tartu, Agenzia nazionale per le nuove tecnologie, l'energia e lo sviluppo economico sostenibile, Instituto Superior Tecnico Lisboa, CNRS, Al. I. Cuza University, Vienna University of Technology, Swiss Federal Institute of Technology Lausanne, Ruder Boskovic Institute, University of Latvia, National Institute for Laser, Plasma and Radiation Physics, J. Stefan Institute, National Research Council of Italy, Warsaw University of Technology, Czech Academy of Sciences, Polytechnic University of Milan, Soltan Institute for Nuclear Studies, Department of Applied Physics, University of Innsbruck, KTH Royal Institute of Technology, Belgian Nuclear Research Centre, Comenius University in Bratislava, Aalto-yliopisto, and Aalto University

Subjects
power exhaust, tungsten, particle exhaust, plasma-facing components, beryllium, plasma-surface interaction
Abstract

The provision of a particle and power exhaust solution which is compatible with first-wall components and edge-plasma conditions is a key area of present-day fusion research and mandatory for a successful operation of ITER and DEMO. The work package plasma-facing components (WP PFC) within the European fusion programme complements with laboratory experiments, i.e. in linear plasma devices, electron and ion beam loading facilities, the studies performed in toroidally confined magnetic devices, such as JET, ASDEX Upgrade, WEST etc. The connection of both groups is done via common physics and engineering studies, including the qualification and specification of plasma-facing components, and by modelling codes that simulate edge-plasma conditions and the plasma-material interaction as well as the study of fundamental processes. WP PFC addresses these critical points in order to ensure reliable and efficient use of conventional, solid PFCs in ITER (Be and W) and DEMO (W and steel) with respect to heat-load capabilities (transient and steady-state heat and particle loads), lifetime estimates (erosion, material mixing and surface morphology), and safety aspects (fuel retention, fuel removal, material migration and dust formation) particularly for quasi-steady-state conditions. Alternative scenarios and concepts (liquid Sn or Li as PFCs) for DEMO are developed and tested in the event that the conventional solution turns out to not be functional. Here, we present an overview of the activities with an emphasis on a few key results: (i) the observed synergistic effects in particle and heat loading of ITER-grade W with the available set of exposition devices on material properties such as roughness, ductility and microstructure; (ii) the progress in understanding of fuel retention, diffusion and outgassing in different W-based materials, including the impact of damage and impurities like N; and (iii), the preferential sputtering of Fe in EUROFER steel providing an in situ W surface and a potential first-wall solution for DEMO.

34. ERO and PIC simulations of gross and net erosion of tungsten in the outer strike-point region of ASDEX Upgrade

Author

Hakola, A., Airila, M. I., Mellet, N., Groth, M., Karhunen, Juuso, Kurki-Suonio, T., Makkonen, T., Sillanpää, Heikki, Meisl, G., Oberkofler, M., ASDEX Upgrade Team, ASDEX Upgrade Team, Max Planck Institute for Plasma Physics, Max Planck Society, VTT Technical Research Centre of Finland, Aix-Marseille Université, Department of Applied Physics, Max-Planck-Institut für Plasmaphysik, Aalto-yliopisto, and Aalto University

Subjects
Nuclear and High Energy Physics, Materials Science (miscellaneous), Tungsten erosion, chemistry.chemical_element, Flux, Tungsten, 01 natural sciences, 010305 fluids & plasmas, PIC simulations, ASDEX Upgrade, Particle drifts, 0103 physical sciences, Diffusion (business), 010306 general physics, Line (formation), Physics, ta114, Cross-field diffusion, Plasma, lcsh:TK9001-9401, Computational physics, Magnetic field, ERO modelling, Nuclear Energy and Engineering, chemistry, Erosion, lcsh:Nuclear engineering. Atomic power, Atomic physics
Abstract

We have modelled net and gross erosion of W in low-density l-mode plasmas in the low-field side strike point region of ASDEX Upgrade by ERO and Particle-in-Cell (PIC) simulations. The observed net-erosion peak at the strike point was mainly due to the light impurities present in the plasma while the noticeable net-deposition regions surrounding the erosion maximum could be attributed to the strong E ×B drift and the magnetic field bringing eroded particles from a distance of several meters towards the private flux region. Our results also imply that the role of cross-field diffusion is very small in the studied plasmas. The simulations indicate net/gross erosion ratio of 0.2–0.6, which is in line with the literature data and what was determined spectroscopically. The deviations from the estimates extracted from post-exposure ion-beam-analysis data (∼0.6–0.7) are most likely due to the measured re-deposition patterns showing the outcomes of multiple erosion-deposition cycles. Keywords: ASDEX Upgrade, Tungsten erosion, ERO modelling, PIC simulations, Particle drifts, Cross-field diffusion

Full Text
View/download PDF

35. Measurement and Theoretical Modeling of the Damping Rate of Medium-N Toroidal Alfven Eigenmodes in JET

Author

Testa, D., Panis, T., Fasoli, A., Blanchard, P., Carfantan, H., Goodyear, A., Mellet, N., Sharapov, S. E., Spong, D., and JET-EFDA contributors

Subjects
Physics::Plasma Physics, Toroidal Alfven Eigenmodes, damping rate
Abstract

This paper reports on the results of recent experiments performed on the JET tokamak on Alfven Eigenmodes (AEs) with toroidal mode number (n) in the range |n|=3-15. The stability properties of these medium-n AEs are investigated experimentally using a set of compact in-vessel antennas, providing a direct and real-time measurement of the frequency, damping rate and amplitude for each individual toroidal mode number. First, we describe the development of a new algorithm for real-time mode detection and discrimination using the Sparse Signal Representation theory. Second, we present measurements of the dependence of the damping rate for Toroidal AEs with |n

36. Monte Carlo ICRH simulations in fully shaped anisotropic plasmas

Author

Jucker, M., Graves, J.P., Cooper, W.A., Mellet, N., Brunner, S., Garbet, X., Sauter, O., and Sindoni, E.

Subjects
Physics::Plasma Physics
Abstract

This work shows a self-consistent numerical model of ion cyclotron resonant heating (ICRH) in a plasma of arbitrary (2D or 3D) geometry. Effects of anisotropy and full shaping on both MHD equilibrium and the dielectric tensor are explored. In particular, it is shown that the dielectric tensor becomes dependent on poloidal angle. Also, the anisotropic effects dominate the dielectric tensor. Using single particle simulations it is demonstrated that anisotropy develops due to ICRH. The changing of the equilibrium was successfully fed back into the equilibrium.

37. Integrated modelling of Ion Cyclotron Resonant Heating in toroidal system

Author

Jucker, M., Graves, J. P., Cooper, W. A., Mellet, N., Johnson, T., and Brunner, S.

Subjects
stellarators, tokamaks, ICRH
Abstract

An integrated model capable of self-consistent Ion Cyclotron Resonant Heating (ICRH) simulations has been developed. This model includes both full shaping and pressure effects, warm contributions to the dielectric tensor, pressure anisotropy and finite orbit width. It evolves the equilibrium, wave field and full hot particle distribution function until a self-consistent solution is found. This article describes the workings of the three codes VMEC, LEMan and VENUS and how they are linked for iterated computations in a code package we have named SCENIC. The package is thoroughly tested and it is demonstrated that a number of iterations have to be performed in order to find a consistent solution. Since the formulation of the problem can treat general 3D systems, we show a quasi-axisymmetric stellarator low power test case, and then concentrate on experimentally relevant Joint European Torus (JET) 2D configurations. (C) 2010 Elsevier B.V. All rights reserved.

40. The Influence of Plasma Shaping on the Damping of Toroidal Alfven Eigenmodes

Author

Borba, D., Fasoli, A., Gorelenkov, N. N., Gunter, S., Lauber, Ph, Mellet, N., Nazikian, R., Panis, T., Pinches, S. D., Spong, D., Testa, D., and Contributors, JET-EFDA

Subjects
Physics::Plasma Physics, Alfven Eigenmodes, numerical modelling
Abstract

The dependence of the damping of toroidal Alfven Eigenmodes (TAEs) on various plasma parameters and shapes is analysed with numerical models ranging from perturbative MHD codes like CASTOR-K and NOVA-K, via a warm dielectric tensor model like LEMan to gyrofluid (TAEFL) and linear gyrokinetic codes (LIGKA). Joint European Torus (JET) well diagnosed discharges are used to compare the theoretical models against the experiment. The measurement of TAE damping rates by active in-vessel antennas at JET allows for a direct comparison of both frequency and damping rate with theory.

41. Convolution and iterative methods applied to low frequency waves in 3D configurations

Author

Mellet, N., Cooper, W. A., Popovich, P., Villard, L., and Brunner, S.

Subjects
Plasma, ICRF, Three-dimensional geometry, Physics::Plasma Physics, Parallel wave vector, Warm model, Alfvén
Abstract

Kinetic effects have been implemented in the three-dimensional full-wave code LEMan. These allow modeling Landau damping as well as the Kinetic Alfvén Wave (KAW). Special attention has been taken on the exact computation of the parallel wave vector as it can have a strong impact on the results. Due to numerical specificities, two techniques have been used depending on the frequency domain under investigation. The damping of global modes like Toroidally-induced Alfvén Eigenmodes (TAE), which is a key issue for future reactors as they can be driven by fast ions, can then be determined. Multiple couplings are shown to lead to an increase of the damping value and thus to a stabilization of the mode. In the Ion Cyclotron Range of Frequencies (ICRF), a Large Helical Device (LHD) configuration has been investigated. For this specific case, the difference between the results obtained with an accurate determination of the parallel wave vector and the approximation kparallel=n/R has been shown to be insignificant.

42. The Dependence of the Damping Rate of Medium-n Toroidal Alfvén Eigenmodes on the Edge Plasma Elongation in JET

Author

Testa, D., Mellet, N., Panis, T., Blanchard, P., Carfantan, H., Fasoli, A., Goodyear, A., Pinches, S., and EFDA-JET collaborators

Subjects
Physics::Plasma Physics, Alfven Eigenmodes stability
Abstract

This paper reports the first quantitative analysis of the measurements of the damping rate (gamma/omega) for stable Alfvén Eigenmodes (AEs) with toroidal mode number (n) in the range |n|=3-15 as function of the edge plasma elongation (kappa95). We find that the damping rate gamma/omega vs. kappa95 for medium-n Toroidal AEs, with n=3 and n=7, increases for increasing elongation, i.e. its scaling vs. kappa95 follows the same trend previously measured and explained theoretically for the n=1 and n=2 TAE modes. Theoretical analysis of the measurements for the n=3 TAEs has been performed using the LEMan code. The results are in good agreement (within a factor 2) for all the magnetic configurations where there is only a very minor up/down asymmetry in the poloidal cross-section of the plasma. These experimental results further confirm the possibility of using the edge shape parameters as a real-time actuator for control of the stability of alpha-particles driven AEs in burning plasma experiments, such as ITER.

43. Behavioral, metabolic, and lipidomic characterization of the 5xFADxTg30 mouse model of Alzheimer's disease.

Author

Marshall JPS, Huynh K, Lancaster GI, Ng J, Collins JM, Pernes G, Liang A, Featherby T, Mellet NA, Drew BG, Calkin AC, King AE, Meikle PJ, Febbraio MA, Adlard PA, and Henstridge DC

Abstract

Alzheimer's disease (AD) is associated with both extracellular amyloid-β (Aβ) plaques and intracellular tau-containing neurofibrillary tangles (NFT). We characterized the behavioral, metabolic and lipidomic phenotype of the 5xFADxTg30 mouse model which contains overexpression of both Aβ and tau. Our results independently reproduce several phenotypic traits described previously for this model, while providing additional characterization. This model develops many aspects associated with AD including frailty, decreased survival, initiation of aspects of cognitive decline and alterations to specific lipid classes and molecular lipid species in the plasma and brain. Notably, some sex-specific differences exist in this model and motor impairment with aging in this model does compromise the utility of the model for some movement-based behavioral assessments of cognitive function. These findings provide a reference for individuals interested in using this model to understand the pathology associated with elevated Aβ and tau or for testing potential therapeutics for the treatment of AD., Competing Interests: The authors declare no competing interests., (© 2024 The Author(s).)

Published
2024
Full Text
View/download PDF

44. Lipoatrophic diabetes in familial partial lipodystrophy type 2: From insulin resistance to diabetes.

Author

Treiber G, Guilleux A, Huynh K, Bonfanti O, Flaus-Furmaniuk A, Couret D, Mellet N, Bernard C, Le-Moullec N, Doray B, Jéru I, Maiza JC, Domun B, Cogne M, Meilhac O, Vigouroux C, Meikle PJ, and Nobécourt E

Subjects
Adult, Humans, Adiponectin, Insulin, Glucose, Blood Glucose metabolism, Insulin Resistance, Lipodystrophy, Familial Partial, Diabetes Mellitus, Lipoatrophic, Prediabetic State, Diabetes Mellitus, Type 2
Abstract

Aim: Subjects with Familial Partial Lipodystrophy type 2 (FPLD2) are at high risk to develop diabetes. To better understand the natural history and variability of this disease, we studied glucose tolerance, insulin response to an oral glucose load, and metabolic markers in the largest cohort to date of subjects with FPLD2 due to the same LMNA variant., Methods: A total of 102 patients aged > 18 years, with FPLD2 due to the LMNA 'Reunionese' variant p.(Thr655Asnfs*49) and 22 unaffected adult relatives with normal glucose tolerance (NGT) were enrolled. Oral Glucose Tolerance Tests (OGTT) with calculation of derived insulin sensitivity and secretion markers, and measurements of HbA1c, C-reactive protein, leptin, adiponectin and lipid profile were performed., Results: In patients with FPLD2: 65% had either diabetes (41%) or prediabetes (24%) despite their young age (median: 39.5 years IQR 29.0-50.8) and close-to-normal BMI (median: 25.5 kg/m 2 IQR 23.1-29.4). Post-load OGTT values revealed insulin resistance and increased insulin secretion in patients with FPLD2 and NGT, whereas patients with diabetes were characterized by decreased insulin secretion. Impaired glucose tolerance with normal fasting glucose was present in 86% of patients with prediabetes. Adiponectin levels were decreased in all subjects with FPLD2 and correlated with insulin sensitivity markers., Conclusions: OGTT reveals early alterations of glucose and insulin metabolism in patients with FPLD2, and should be systematically performed before excluding a diagnosis of prediabetes or diabetes to adapt medical care. Decreased adiponectin is an early marker of the disease. Adiponectin replacement therapy warrants further study in FPLD2., Competing Interests: Declaration of Competing Interest The authors declare no conflict of interest., (Copyright © 2022 Elsevier Masson SAS. All rights reserved.)

Published
2023
Full Text
View/download PDF

45. Short-term inhibition of autophagy benefits pancreatic β-cells by augmenting ether lipids and peroxisomal function, and by countering depletion of n-3 polyunsaturated fatty acids after fat-feeding.

Author

Chu KY, Mellet N, Thai LM, Meikle PJ, and Biden TJ

Subjects
Animals, Autophagy-Related Protein 7 genetics, Cell Line, Diet, High-Fat, Fatty Acids, Omega-3 analysis, Fatty Acids, Omega-3 metabolism, Fatty Acids, Omega-3 pharmacology, Insulin metabolism, Insulin Secretion drug effects, Insulin-Secreting Cells physiology, Islets of Langerhans metabolism, Lipid Metabolism physiology, Lipids physiology, Mice, Mice, Knockout, Obesity metabolism, Peroxisomes physiology, Autophagy physiology, Glucose metabolism, Insulin-Secreting Cells metabolism
Abstract

Objective: Investigations of autophagy in β-cells have usually focused on its homeostatic function. More dynamic roles in inhibiting glucose-stimulated insulin secretion (GSIS), potentially involving remodelling of cellular lipids, have been suggested from in vitro studies but not evaluated in vivo., Methods: We employed temporally-regulated deletion of the essential autophagy gene, Atg7, in β-cells. Mice were fed chow or high-fat diets (HFD), in conjunction with deletion of Atg7 for the last 3 weeks (short-term model) or 9 weeks (long-term model). Standard in vivo metabolic phenotyping was undertaken, and 450 lipid species in islets quantified ex vivo using mass spectroscopy (MS). MIN6 cells were also employed for lipidomics and secretory interventions., Results: β-cell function was impaired by inhibiting autophagy in the longer-term, but conversely improved by 3-week deletion of Atg7, specifically under HFD conditions. This was accompanied by augmented GSIS ex vivo. Surprisingly, the HFD had minimal effect on sphingolipid and neutral lipid species, but modulated >100 phospholipids and ether lipids, and markedly shifted the profile of polyunsaturated fatty acid (PUFA) sidechains from n3 to n6 forms. These changes were partially countered by Atg7 deletion, consistent with an accompanying upregulation of the PUFA elongase enzyme, Elovl5. Loss of Atg7 separately augmented plasmalogens and alkyl lipids, in association with increased expression of Lonp2, a peroxisomal chaperone/protease that facilitates maturation of ether lipid synthetic enzymes. Depletion of PUFAs and ether lipids was also observed in MIN6 cells chronically exposed to oleate (more so than palmitate). GSIS was inhibited by knocking down Dhrs7b, which encodes an enzyme of peroxisomal ether lipid synthesis. Conversely, impaired GSIS due to oleate pre-treatment was selectively reverted by Dhrs7b overexpression., Conclusions: A detrimental increase in n6:n3 PUFA ratios in ether lipids and phospholipids is revealed as a major response of β-cells to high-fat feeding. This is partially reversed by short-term inhibition of autophagy, which results in compensatory changes in peroxisomal lipid metabolism. The short-term phenotype is linked to improved GSIS, in contrast to the impairment seen with the longer-term inhibition of autophagy. The balance between these positive and negative inputs could help determine whether β-cells adapt or fail in response to obesity., (Copyright © 2020 The Authors. Published by Elsevier GmbH.. All rights reserved.)

Published
2020
Full Text
View/download PDF

46. Oleate disrupts cAMP signaling, contributing to potent stimulation of pancreatic β-cell autophagy.

Author

Chu KY, O'Reilly L, Mellet N, Meikle PJ, Bartley C, and Biden TJ

Subjects
Animals, Cyclic AMP metabolism, Guanine Nucleotide Exchange Factors antagonists & inhibitors, Guanine Nucleotide Exchange Factors deficiency, Guanine Nucleotide Exchange Factors metabolism, Mice, Mice, Inbred C57BL, Tumor Cells, Cultured, Apoptosis drug effects, Cyclic AMP antagonists & inhibitors, Insulin-Secreting Cells drug effects, Oleic Acid pharmacology, Signal Transduction drug effects
Abstract

Autophagy is critical for maintaining cellular function via clearance of excess nutrients and damaged organelles. In pancreatic β-cells, it helps counter the endoplasmic reticulum (ER) stress that impairs insulin secretory capacity during Type 2 diabetes. Chronic exposure of β-cells to saturated fatty acids (FAs) such as palmitate stimulates ER stress and modulates autophagy, but the effects of unsaturated FAs such as oleate, which are also elevated during obesity, are less well understood. We therefore treated MIN6 cells and mouse islets for 8-48 h with either palmitate or oleate, and then monitored autophagic flux, signaling pathways, lysosomal biology, and phospholipid profiles. Compared with palmitate, oleate more effectively stimulated both autophagic flux and clearance of autophagosomes. The flux stimulation occurred independently of ER stress, nutrient-sensing (mTOR) and signaling pathways (protein kinases A, C, and D). Instead the mechanism involved the exchange factor directly activated by cAMP 2 (EPAC2). Oleate reduced cellular cAMP, and its effects on autophagic flux were reproduced or inhibited, respectively, by Epac2 knockdown or activation. Oleate also increased lysosomal acidity and increased phospholipid saturation, consistent with improved autophagosomal fusion with lysosomes. We conclude that a potent stimulation of autophagy might help explain the known benefits of unsaturated FAs in countering the toxicity of saturated FAs in β-cells during obesity and lipid loading., (© 2019 Chu et al.)

Published
2019
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results