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2,504 results on '"Gagnon, Jean"'

9. La bourse

Author

Gagnon, Jean-Marie

Published
2020

16. Préface

Author

Gagnon, Jean-Marie

Published
2020

17. Couverture

Author

Gagnon, Jean-Marie

Published
2020

26. Couverture

Author

Gagnon, Jean-Pierre

Published
2019

32. Avant-propos

Author

Gagnon, Jean-Pierre

Published
2019

33. Préface

Author

Gagnon, Jean-Pierre

Published
2019

36. IGLON5 Frequency in Idiopathic REM Sleep Behavior Disorder: A Multicenter Study.

Author

Postuma, Ronald, Vorasoot, Nisa, St Louis, Erik, Pelletier, Amélie, Lim, Miranda, Elliott, Jonathan, Gagnon, Jean-Francois, Gan-Or, Ziv, Forsberg, Leah, Fields, Julie, Ross, Owen, Singer, Wolfgang, Huddleston, Daniel, Bliwise, Donald, Avidan, Alon, Howell, Michael, Schenck, Carlos, McLeland, Jennifer, Davis, Albert, Criswell, Susan, Videnovic, Aleksandar, During, Emmanuel, Miglis, Mitchell, Boeve, Bradley, Ju, Yo-El, and McKeon, Andrew

Subjects
Humans, REM Sleep Behavior Disorder, Male, Female, Autoantibodies, Aged, Cell Adhesion Molecules, Neuronal, Middle Aged, Cohort Studies
Abstract

BACKGROUND AND OBJECTIVES: Idiopathic/isolated REM sleep behavior disorder (iRBD) has been strongly linked to neurodegenerative synucleinopathies such as Parkinson disease, dementia with Lewy bodies, and multiple system atrophy. However, there have been increasing reports of RBD as a presenting feature of serious and treatable autoimmune syndromes, particularly IGLON5. This studys objective was to investigate the frequency of autoantibodies in a large cohort of participants with iRBD. METHODS: Participants were enrolled in the North American Prodromal Synucleinopathy cohort with polysomnography-confirmed iRBD, free of parkinsonism and dementia. Plasma samples were systematically screened for the autoantibodies IGLON5, DPPX, LGI1, and CASPR2 using plasma IgG cell-based assay. Positive or equivocal results were confirmed by repeat testing, plus tissue-based indirect immunofluorescence assay for IGLON5. RESULTS: Of 339 samples analyzed, 3 participants (0.9%) had confirmed positive IGLON5 autoantibodies in the cell-based assay, which were confirmed by the tissue-based assay. An additional participant was positive for CASPR2 with low titer by cell-based assay only (of lower clinical certainty). These cases exhibited a variety of symptoms including dream enactment, cognitive decline, autonomic dysfunction, and motor symptoms. In 1 IGLON5 case and the CASPR2 case, evolution was suggestive of typical synucleinopathy, suggesting the possibility that findings were incidental. However, 2 participants with IGLON5 died before diagnosis was clinically suspected, with a final clinical picture highly suggestive of autoimmune disease. DISCUSSION: Our finding that nearly 1% of a large iRBD cohort may have a serious but potentially treatable autoantibody syndrome has important clinical implications. In particular, it raises the question of whether autoantibody testing for IGLON-5-IgG should be widely implemented for participants with iRBD, considering the difficulty in diagnosis of autoimmune diseases, their response to treatment, and the potential for rapid disease progression. However, any routine testing protocol will also have to consider costs and potential adverse effects of false-positive findings. TRIAL REGISTRATION INFORMATION: NCT03623672.

Published
2024

37. Anisotropic induced polarization modeling with neural networks and effective medium theory

Author

Bérubé, Charles L. and Gagnon, Jean-Luc

Subjects
Physics - Geophysics
Abstract

Accurately interpreting induced polarization (IP) data that reflects the inherent anisotropy of the Earth's crust requires anisotropic IP models. The Generalized Effective Medium Theory of Induced Polarization (GEMTIP) model effectively simulates the IP signatures of rocks containing polarizable minerals. A pivotal element of the GEMTIP model is calculating the depolarization tensor elements, an intensive task for anisotropic rocks because one must numerically solve six parametric integrals for each mineral inclusion. This study aims to streamline anisotropic IP simulations by extending the GEMTIP framework and introducing a machine learning approach to estimate the depolarization tensors. The theoretical contributions of this research are two-fold: (1) we augment the GEMTIP model to encompass anisotropic background conductivity and triaxial ellipsoidal inclusions, and (2) we reformulate the depolarization integrals to normalize their input and output variables, facilitating their estimation by neural networks. Validation against analytical solutions for spherical and spheroidal inclusions corroborates the accuracy of the neural network. Analyzing the neural network model, we find that the relationship between chargeability and polarizable inclusion content is increasingly uncertain for increasingly anisotropic rocks. A similar observation applies to the relationship between critical frequency and host rock conductivity. Moreover, the depolarization tensors are, on average, 56 % sensitive to inclusion anisotropy and 44 % sensitive to host rock conductivity anisotropy. Remarkably, our neural network drastically accelerates GEMTIP simulations--up to 100,000 times faster than numerical integration--without substantially sacrificing accuracy. This advancement is promising for efficient rock-scale IP modeling in complex and anisotropic geological settings., Comment: 25 pages, 4 tables, 11 figures, 1 appendix. Original manuscript version submitted to Geophysics

Published
2024

41. Baseline characteristics of the North American prodromal Synucleinopathy cohort.

Author

Elliott, Jonathan, Lim, Miranda, Keil, Allison, Postuma, Ronald, Pelletier, Amelie, Gagnon, Jean-François, St Louis, Erik, Forsberg, Leah, Fields, Julie, Huddleston, Daniel, Bliwise, Donald, Avidan, Alon, Howell, Michael, Schenck, Carlos, McLeland, Jennifer, Criswell, Susan, Videnovic, Aleksandar, During, Emmanuel, Miglis, Mitchell, Shprecher, David, Lee-Iannotti, Joyce, Boeve, Bradley, and Ju, Yo-El

Subjects
Female, Humans, Male, Lewy Body Disease, Longitudinal Studies, Multiple System Atrophy, Parkinson Disease, REM Sleep Behavior Disorder, Synucleinopathies
Abstract

OBJECTIVE: Rapid eye movement (REM) sleep behavior disorder (RBD) is widely considered a prodromal synucleinopathy, as most with RBD develop overt synucleinopathy within ~10 years. Accordingly, RBD offers an opportunity to test potential treatments at the earliest stages of synucleinopathy. The North American Prodromal Synucleinopathy (NAPS) Consortium has created a multisite RBD participant, primarily clinic-based cohort to better understand characteristics at diagnosis, and in future work, identify predictors of phenoconversion, develop synucleinopathy biomarkers, and enable early stage clinical trial enrollment. METHODS: Participants ≥18 years of age with overnight polysomnogram-confirmed RBD without Parkinsons disease, dementia, multiple system atrophy, or narcolepsy were enrolled from nine sites across North America (8/2018 to 4/2021). Data collection included family/personal history of RBD and standardized assessments of cognitive, motor, sensory, and autonomic function. RESULTS: Outcomes are primarily reported based on sex (361 total: n = 295 male, n = 66 female), and secondarily based on history of antidepressant use (n = 200 with, n = 154 without; with correction for sex differences) and based on extent of synucleinopathy burden (n = 56 defined as isolated RBD, n = 305 defined as RBD+ [i.e., exhibiting ≥1 abnormality]). Overall, these participants commonly demonstrated abnormalities in global cognition (MoCA; 38%), motor function (alternate tap test; 48%), sensory (BSIT; 57%), autonomic function (orthostatic hypotension, 38.8%), and anxiety/depression (BAI and PHQ-9; 39.3% and 31%, respectively). INTERPRETATION: These RBD participants, assessed with extensive history, demographic, cognitive, motor, sensory, and autonomic function demonstrated a lack of sex differences and high frequency of concomitant neurological abnormalities. These participants will be valuable for future longitudinal study and neuroprotective clinical trials.

Published
2023

43. Significance of a one-degree Celsius increase in global temperature

Author

Gagnon, Jean-Sebastien

Subjects
Physics - Atmospheric and Oceanic Physics, Physics - Physics Education, Physics - Popular Physics
Abstract

The Intergovernmental Panel on Climate Change reports indicate that the global mean temperature is about one-degree Celsius higher than pre-industrial levels, that this increase is anthropogenic, and that there is a causal relationship between this higher temperature and an increase in frequency and magnitude of extreme weather events. This causal relationship seems at odds with common sense, and may be difficult to explain to non-experts. Thus to appreciate the significance of a one-degree increase in global mean temperature, we perform back-of-the-envelope calculations relying on simple physics. We estimate the excess thermal energy trapped in the climate system (oceans, land, atmosphere) from a one-degree Celsius increase in global mean temperature, and show that it is thousands of times larger than the estimated energy required to form and maintain a hurricane. Our estimates show that global warming is forming a very large pool of excess energy that could in principle power heatwaves, heavy precipitation, droughts, and hurricanes. The arguments presented here are sufficiently simple to be presented in introductory physics classes, and can serve as plausibility arguments showing that even a seemingly small increase in global mean temperature can potentially lead to extreme weather events., Comment: 11 pages

Published
2022
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45. The neurophysiological brain-fingerprint of Parkinson’s disease

Author

Breitner, John, Poirier, Judes, Baillet, Sylvain, Bellec, Pierre, Bohbot, Véronique, Chakravarty, Mallar, Collins, Louis, Etienne, Pierre, Evans, Alan, Gauthier, Serge, Hoge, Rick, Ituria-Medina, Yasser, Multhaup, Gerhard, Münter, Lisa-Marie, Rajah, Natasha, Rosa-Neto, Pedro, Soucy, Jean-Paul, Vachon-Presseau, Etienne, Villeneuve, Sylvia, Amouyel, Philippe, Appleby, Melissa, Ashton, Nicholas, Auld, Daniel, Ayranci, Gülebru, Bedetti, Christophe, Beland, Marie-Lise, Blennow, Kaj, Westman, Ann Brinkmalm, Cuello, Claudio, Dadar, Mahsa, Daoust, Leslie-Ann, Das, Samir, Dauar-Tedeschi, Marina, De Beaumont, Louis, Dea, Doris, Descoteaux, Maxime, Dufour, Marianne, Farzin, Sarah, Ferdinand, Fabiola, Fonov, Vladimir, Gonneaud, Julie, Kat, Justin, Kazazian, Christina, Labonté, Anne, Lafaille-Magnan, Marie-Elyse, Lalancette, Marc, Lambert, Jean-Charles, Leoutsakos, Jeannie-Marie, Mahar, Laura, Mathieu, Axel, McSweeney, Melissa, Meyer, Pierre-François, Miron, Justin, Near, Jamie, NewboldFox, Holly, Nilsson, Nathalie, Orban, Pierre, Picard, Cynthia, Binette, Alexa Pichet, Poline, Jean-Baptiste, Rabipour, Sheida, Salaciak, Alyssa, Settimi, Matthew, Subramaniapillai, Sivaniya, Tam, Angela, Tardif, Christine, Théroux, Louise, Tremblay-Mercier, Jennifer, Tullo, Stephanie, Ulku, Irem, Vallée, Isabelle, Zetterberg, Henrik, Nair, Vasavan, Pruessner, Jens, Aisen, Paul, Anthal, Elena, Barkun, Alan, Beaudry, Thomas, Benbouhoud, Fatiha, Brandt, Jason, Carmo, Leopoldina, Carrier, Charles Edouard, Cheewakriengkrai, Laksanun, Courcot, Blandine, Couture, Doris, Craft, Suzanne, Dansereau, Christian, Debacker, Clément, Desautels, René, Dubuc, Sylvie, Duclair, Guerda, Eisenberg, Mark, El-Khoury, Rana, Faubert, Anne-Marie, Fontaine, David, Frappier, Josée, Frenette, Joanne, Gagné, Guylaine, Gervais, Valérie, Giles, Renuka, Gordon, Renee, Jack, Clifford, Jutras, Benoit, Khachaturian, Zaven, Knopman, David, Kostopoulos, Penelope, Lapalme, Félix, Lee, Tanya, Lepage, Claude, Leppert, Illana, Madjar, Cécile, Maillet, David, Maltais, Jean-Robert, Mathotaarachchi, Sulantha, Mayrand, Ginette, Michaud, Diane, Montine, Thomas, Morris, John, Pagé, Véronique, Pascoal, Tharick, Peillieux, Sandra, Petkova, Mirela, Pogossova, Galina, Rioux, Pierre, Sager, Mark, Saint-Fort, Eunice Farah, Savard, Mélissa, Sperling, Reisa, Tabrizi, Shirin, Tariot, Pierre, Teigner, Eduard, Thomas, Ronald, Toussaint, Paule-Joanne, Tuwaig, Miranda, Venugopalan, Vinod, Verfaillie, Sander, Vogel, Jacob, Wan, Karen, Wang, Seqian, Yu, Elsa, Beaulieu-Boire, Isabelle, Blanchet, Pierre, Bogard, Sarah, Bouchard, Manon, Chouinard, Sylvain, Cicchetti, Francesca, Cloutier, Martin, Dagher, Alain, Degroot, Clotilde, Desautels, Alex, Dion, Marie Hélène, Drouin-Ouellet, Janelle, Dufresne, Anne-Marie, Dupré, Nicolas, Duquette, Antoine, Durcan, Thomas, Fellows, Lesley K., Fon, Edward, Gagnon, Jean-François, Gan-Or, Ziv, Genge, Angela, Jodoin, Nicolas, Karamchandani, Jason, Lafontaine, Anne-Louise, Langlois, Mélanie, Leveille, Etienne, Lévesque, Martin, Melmed, Calvin, Monchi, Oury, Montplaisir, Jacques, Panisset, Michel, Parent, Martin, Pham-An, Minh-Thy, Postuma, Ronald, Pourcher, Emmanuelle, Rao, Trisha, Rivest, Jean, Rouleau, Guy, Sharp, Madeleine, Soland, Valérie, Sidel, Michael, Wing Sun, Sonia Lai, Thiel, Alexander, Vitali, Paolo, da Silva Castanheira, Jason, Wiesman, Alex I., Hansen, Justine Y., and Misic, Bratislav

Published
2024
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50. Renormalization of stochastic differential equations with multiplicative noise using effective potential methods

Author

Gagnon, Jean-Sebastien, Hochberg, David, and Perez-Mercader, Juan

Subjects
Condensed Matter - Statistical Mechanics
Abstract

We present a new method to renormalize stochastic differential equations subjected to multiplicative noise. The method is based on the widely used concept of effective potential in high energy physics, and has already been successfully applied to the renormalization of stochastic differential equations subjected to additive noise. We derive a general formula for the one-loop effective potential of a single ordinary stochastic differential equation (with arbitrary interaction terms) subjected to multiplicative Gaussian noise (provided the noise satisfies a certain normalization condition). To illustrate the usefulness (and limitations) of the method, we use the effective potential to renormalize a toy chemical model based on a simplified Gray-Scott reaction. In particular, we use it to compute the scale dependence of the toy model's parameters (in perturbation theory) when subjected to a Gaussian power-law noise with short time correlations., Comment: 11 pages, 2 figures

Published
2020
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