35 results on '"Pereira, Vitor M."'
Search Results
2. sj-pdf-3-wso-10.1177_17474930211048768 - Supplemental material for SWIFT DIRECT: Solitaire��� With the Intention For Thrombectomy Plus Intravenous t-PA Versus DIRECT Solitaire��� Stent-retriever Thrombectomy in Acute Anterior Circulation Stroke: Methodology of a randomized, controlled, multicentre study
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Fischer, Urs, Kaesmacher, Johannes, S Plattner, Patricia, B��tikofer, Lukas, Mordasini, Pasquale, Deppeler, Sandro, Cognard, Christoph, Pereira, Vitor M, Siddiqui, Adnan H, Froehler, Michael T, Furlan, Anthony J, Chapot, Ren��, Strbian, Daniel, Wiesmann, Martin, Bressan, Jenny, Lerch, Stefanie, Liebeskind, David S, Saver, Jeffery L, and Gralla, Jan
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FOS: Clinical medicine ,Cardiology ,Medicine ,110904 Neurology and Neuromuscular Diseases - Abstract
Supplemental material, sj-pdf-3-wso-10.1177_17474930211048768 for SWIFT DIRECT: Solitaire��� With the Intention For Thrombectomy Plus Intravenous t-PA Versus DIRECT Solitaire��� Stent-retriever Thrombectomy in Acute Anterior Circulation Stroke: Methodology of a randomized, controlled, multicentre study by Urs Fischer, Johannes Kaesmacher, Patricia S Plattner, Lukas B��tikofer, Pasquale Mordasini, Sandro Deppeler, Christoph Cognard, Vitor M Pereira, Adnan H Siddiqui, Michael T Froehler, Anthony J Furlan, Ren�� Chapot, Daniel Strbian, Martin Wiesmann, Jenny Bressan, Stefanie Lerch, David S Liebeskind, Jeffery L Saver, and Jan Gralla on behalf of the SWIFT DIRECT study investigators in International Journal of Stroke
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- 2022
- Full Text
- View/download PDF
3. sj-pdf-3-wso-10.1177_17474930211048768 - Supplemental material for SWIFT DIRECT: Solitaire��� With the Intention For Thrombectomy Plus Intravenous t-PA Versus DIRECT Solitaire��� Stent-retriever Thrombectomy in Acute Anterior Circulation Stroke: Methodology of a randomized, controlled, multicentre study
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Fischer, Urs, Kaesmacher, Johannes, S Plattner, Patricia, B��tikofer, Lukas, Mordasini, Pasquale, Deppeler, Sandro, Cognard, Christoph, Pereira, Vitor M, Siddiqui, Adnan H, Froehler, Michael T, Furlan, Anthony J, Chapot, Ren��, Strbian, Daniel, Wiesmann, Martin, Bressan, Jenny, Lerch, Stefanie, Liebeskind, David S, Saver, Jeffery L, and Gralla, Jan
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FOS: Clinical medicine ,Cardiology ,Medicine ,110904 Neurology and Neuromuscular Diseases - Abstract
Supplemental material, sj-pdf-3-wso-10.1177_17474930211048768 for SWIFT DIRECT: Solitaire��� With the Intention For Thrombectomy Plus Intravenous t-PA Versus DIRECT Solitaire��� Stent-retriever Thrombectomy in Acute Anterior Circulation Stroke: Methodology of a randomized, controlled, multicentre study by Urs Fischer, Johannes Kaesmacher, Patricia S Plattner, Lukas B��tikofer, Pasquale Mordasini, Sandro Deppeler, Christoph Cognard, Vitor M Pereira, Adnan H Siddiqui, Michael T Froehler, Anthony J Furlan, Ren�� Chapot, Daniel Strbian, Martin Wiesmann, Jenny Bressan, Stefanie Lerch, David S Liebeskind, Jeffery L Saver, and Jan Gralla on behalf of the SWIFT DIRECT study investigators in International Journal of Stroke
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- 2022
- Full Text
- View/download PDF
4. sj-pdf-2-wso-10.1177_17474930211048768 - Supplemental material for SWIFT DIRECT: Solitaire��� With the Intention For Thrombectomy Plus Intravenous t-PA Versus DIRECT Solitaire��� Stent-retriever Thrombectomy in Acute Anterior Circulation Stroke: Methodology of a randomized, controlled, multicentre study
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Fischer, Urs, Kaesmacher, Johannes, S Plattner, Patricia, B��tikofer, Lukas, Mordasini, Pasquale, Deppeler, Sandro, Cognard, Christoph, Pereira, Vitor M, Siddiqui, Adnan H, Froehler, Michael T, Furlan, Anthony J, Chapot, Ren��, Strbian, Daniel, Wiesmann, Martin, Bressan, Jenny, Lerch, Stefanie, Liebeskind, David S, Saver, Jeffery L, and Gralla, Jan
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FOS: Clinical medicine ,Cardiology ,Medicine ,110904 Neurology and Neuromuscular Diseases - Abstract
Supplemental material, sj-pdf-2-wso-10.1177_17474930211048768 for SWIFT DIRECT: Solitaire��� With the Intention For Thrombectomy Plus Intravenous t-PA Versus DIRECT Solitaire��� Stent-retriever Thrombectomy in Acute Anterior Circulation Stroke: Methodology of a randomized, controlled, multicentre study by Urs Fischer, Johannes Kaesmacher, Patricia S Plattner, Lukas B��tikofer, Pasquale Mordasini, Sandro Deppeler, Christoph Cognard, Vitor M Pereira, Adnan H Siddiqui, Michael T Froehler, Anthony J Furlan, Ren�� Chapot, Daniel Strbian, Martin Wiesmann, Jenny Bressan, Stefanie Lerch, David S Liebeskind, Jeffery L Saver, and Jan Gralla on behalf of the SWIFT DIRECT study investigators in International Journal of Stroke
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- 2022
- Full Text
- View/download PDF
5. sj-pdf-2-wso-10.1177_17474930211048768 - Supplemental material for SWIFT DIRECT: Solitaire��� With the Intention For Thrombectomy Plus Intravenous t-PA Versus DIRECT Solitaire��� Stent-retriever Thrombectomy in Acute Anterior Circulation Stroke: Methodology of a randomized, controlled, multicentre study
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Fischer, Urs, Kaesmacher, Johannes, S Plattner, Patricia, B��tikofer, Lukas, Mordasini, Pasquale, Deppeler, Sandro, Cognard, Christoph, Pereira, Vitor M, Siddiqui, Adnan H, Froehler, Michael T, Furlan, Anthony J, Chapot, Ren��, Strbian, Daniel, Wiesmann, Martin, Bressan, Jenny, Lerch, Stefanie, Liebeskind, David S, Saver, Jeffery L, and Gralla, Jan
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FOS: Clinical medicine ,Cardiology ,Medicine ,110904 Neurology and Neuromuscular Diseases - Abstract
Supplemental material, sj-pdf-2-wso-10.1177_17474930211048768 for SWIFT DIRECT: Solitaire��� With the Intention For Thrombectomy Plus Intravenous t-PA Versus DIRECT Solitaire��� Stent-retriever Thrombectomy in Acute Anterior Circulation Stroke: Methodology of a randomized, controlled, multicentre study by Urs Fischer, Johannes Kaesmacher, Patricia S Plattner, Lukas B��tikofer, Pasquale Mordasini, Sandro Deppeler, Christoph Cognard, Vitor M Pereira, Adnan H Siddiqui, Michael T Froehler, Anthony J Furlan, Ren�� Chapot, Daniel Strbian, Martin Wiesmann, Jenny Bressan, Stefanie Lerch, David S Liebeskind, Jeffery L Saver, and Jan Gralla on behalf of the SWIFT DIRECT study investigators in International Journal of Stroke
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- 2022
- Full Text
- View/download PDF
6. sj-pdf-1-wso-10.1177_17474930211048768 - Supplemental material for SWIFT DIRECT: Solitaire��� With the Intention For Thrombectomy Plus Intravenous t-PA Versus DIRECT Solitaire��� Stent-retriever Thrombectomy in Acute Anterior Circulation Stroke: Methodology of a randomized, controlled, multicentre study
- Author
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Fischer, Urs, Kaesmacher, Johannes, S Plattner, Patricia, B��tikofer, Lukas, Mordasini, Pasquale, Deppeler, Sandro, Cognard, Christoph, Pereira, Vitor M, Siddiqui, Adnan H, Froehler, Michael T, Furlan, Anthony J, Chapot, Ren��, Strbian, Daniel, Wiesmann, Martin, Bressan, Jenny, Lerch, Stefanie, Liebeskind, David S, Saver, Jeffery L, and Gralla, Jan
- Subjects
FOS: Clinical medicine ,Cardiology ,Medicine ,110904 Neurology and Neuromuscular Diseases - Abstract
Supplemental material, sj-pdf-1-wso-10.1177_17474930211048768 for SWIFT DIRECT: Solitaire��� With the Intention For Thrombectomy Plus Intravenous t-PA Versus DIRECT Solitaire��� Stent-retriever Thrombectomy in Acute Anterior Circulation Stroke: Methodology of a randomized, controlled, multicentre study by Urs Fischer, Johannes Kaesmacher, Patricia S Plattner, Lukas B��tikofer, Pasquale Mordasini, Sandro Deppeler, Christoph Cognard, Vitor M Pereira, Adnan H Siddiqui, Michael T Froehler, Anthony J Furlan, Ren�� Chapot, Daniel Strbian, Martin Wiesmann, Jenny Bressan, Stefanie Lerch, David S Liebeskind, Jeffery L Saver, and Jan Gralla on behalf of the SWIFT DIRECT study investigators in International Journal of Stroke
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- 2021
- Full Text
- View/download PDF
7. sj-pdf-2-wso-10.1177_17474930211048768 - Supplemental material for SWIFT DIRECT: Solitaire��� With the Intention For Thrombectomy Plus Intravenous t-PA Versus DIRECT Solitaire��� Stent-retriever Thrombectomy in Acute Anterior Circulation Stroke: Methodology of a randomized, controlled, multicentre study
- Author
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Fischer, Urs, Kaesmacher, Johannes, S Plattner, Patricia, B��tikofer, Lukas, Mordasini, Pasquale, Deppeler, Sandro, Cognard, Christoph, Pereira, Vitor M, Siddiqui, Adnan H, Froehler, Michael T, Furlan, Anthony J, Chapot, Ren��, Strbian, Daniel, Wiesmann, Martin, Bressan, Jenny, Lerch, Stefanie, Liebeskind, David S, Saver, Jeffery L, and Gralla, Jan
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FOS: Clinical medicine ,Cardiology ,Medicine ,110904 Neurology and Neuromuscular Diseases - Abstract
Supplemental material, sj-pdf-2-wso-10.1177_17474930211048768 for SWIFT DIRECT: Solitaire��� With the Intention For Thrombectomy Plus Intravenous t-PA Versus DIRECT Solitaire��� Stent-retriever Thrombectomy in Acute Anterior Circulation Stroke: Methodology of a randomized, controlled, multicentre study by Urs Fischer, Johannes Kaesmacher, Patricia S Plattner, Lukas B��tikofer, Pasquale Mordasini, Sandro Deppeler, Christoph Cognard, Vitor M Pereira, Adnan H Siddiqui, Michael T Froehler, Anthony J Furlan, Ren�� Chapot, Daniel Strbian, Martin Wiesmann, Jenny Bressan, Stefanie Lerch, David S Liebeskind, Jeffery L Saver, Jan Gralla and on behalf of the SWIFT DIRECT study investigators in International Journal of Stroke
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- 2021
- Full Text
- View/download PDF
8. Canted Spin Texture and Quantum Spin Hall Effect in WTe2
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Garcia, Jose H., Vila, Marc, Hsu, Chuang-Han, Waintal, Xavier, Pereira, Vitor M., and Roche, Stephan
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Condensed Matter - Materials Science ,Condensed Matter - Mesoscale and Nanoscale Physics ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,Condensed Matter::Strongly Correlated Electrons ,Condensed Matter::Mesoscopic Systems and Quantum Hall Effect - Abstract
We report an unconventional quantum spin Hall phase in the monolayer T$_\text{d}$-WTe$_2$, which exhibits hitherto unknown features in other topological materials. The low-symmetry of the structure induces a canted spin texture in the $yz$ plane, which dictates the spin polarization of topologically protected boundary states. Additionally, the spin Hall conductivity gets quantized ($2e^2/h$) with a spin quantization axis parallel to the canting direction. These findings are based on large-scale quantum simulations of the spin Hall conductivity tensor and nonlocal resistances in multi-probe geometries using a realistic tight-binding model elaborated from first-principle methods. The observation of this canted quantum spin Hall effect, related to the formation of topological edge states with nontrivial spin polarization, demands for specific experimental design and suggests interesting alternatives for manipulating spin information in topological materials., For comments please contact josehugo.garcia@icn2.cat
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- 2020
9. Spin-orbit torque magnetization switching in MoTe2/permalloy heterostructures
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Liang, Shiheng, Shi, Shuyuan, Hsu, Chuang-Han, Cai, Kaiming, Wang, Yi, He, Pan, Wu, Yang, Pereira, Vitor M., and Yang, Hyunsoo
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Condensed Matter - Materials Science ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,Condensed Matter::Strongly Correlated Electrons - Abstract
The ability to switch magnetic elements by spin-orbit-induced torques has recently attracted much attention for a path towards high-performance, non-volatile memories with low power consumption. Realizing efficient spin-orbit-based switching requires harnessing both new materials and novel physics to obtain high charge-to-spin conversion efficiencies, thus making the choice of spin source crucial. Here we report the observation of spin-orbit torque switching in bilayers consisting of a semimetallic film of 1T'-MoTe2 adjacent to permalloy. Deterministic switching is achieved without external magnetic fields at room temperature, and the switching occurs with currents one order of magnitude smaller than those typical in devices using the best-performing heavy metals. The thickness dependence can be understood if the interfacial spin-orbit contribution is considered in addition to the bulk spin Hall effect. Further threefold reduction in the switching current is demonstrated with resort to dumbbell-shaped magnetic elements. These findings foretell exciting prospects of using MoTe2 for low-power semimetal material based spin devices.
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- 2020
10. Antiferromagnetism and chiral d-wave superconductivity from an effective t-J-D model for twisted bilayer graphene
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Gu, Xingyu, Chen, Chuan, Leaw, Jia Ning, Laksono, Evan, Pereira, Vitor M., Vignale, Giovanni, and Adam, Shaffique
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Superconductivity (cond-mat.supr-con) ,Superconductivity and magnetism ,Condensed Matter - Superconductivity ,Condensed Matter::Superconductivity ,FOS: Physical sciences ,Condensed Matter::Strongly Correlated Electrons - Abstract
We derive an effective tight-binding model that captures, in real space and with only two parameters, the dominant Coulomb interactions and superconducting pairing near half-filling of magic-angle twisted bilayer graphene. We show that, in an antiferromagnetic Mott insulating ground state with intervalley coherence, magnetic fluctuations and doping mediate superconducting pairing. We find the pairing wave function to have chiral d-wave symmetry and obtain a self-consistent mean-field phase diagram in line with experiments on the doping-induced insulator-to-superconductor transition. We further reveal the existence of chiral Majorana edge modes implied by the nontrivial pairing symmetry, which establishes twisted bilayer graphene as a potential platform for topological superconductivity. This effective model opens the door to systematic scrutiny of the competition between correlated states in this system.
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- 2020
11. Crowdsourcing hypothesis tests:Making transparent how design choices shape research results
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Landy, Justin F., Miaolei (Liam) Jia, Isabel, Ding, Domenico, Viganola, Warren, Tierney, Anna, Dreber, Magnus, Johannesson, Thomas, Pfeiffer, Ebersole, Charles R., Gronau, Quentin F., Alexander, Ly, Don van den Bergh, Maarten, Marsman, Eric-Jan, Wagenmakers, Bartels, Daniel M., Bauman, Christopher W., William, Brady, Felix, Cheung, Andrei, Cimpian, Simone, Dohle, Brent Donnellan, M., Adam, Hahn, Michael, Hall, William, Jiménez-Leal, Johnson, David J., Lucas, Richard E., Benoît, Monin, Andres, Montealegre, Elizabeth, Mullen, Jun, Pang, Jennifer, Ray, Reinero, Diego A., Jesse, Reynolds, Walter, Sowden, Daniel, Storage, Runkun, Su, Tworek, Christina M., Van Bavel, Jay J., Daniel, Walco, Julian, Wills, Xiaobing, Xu, Kai Chi Yam, Xiaoyu, Yang, Martin, Schweinsberg, Molly, Urwitz, Matúš, Adamkovič, Ravin, Alaei, Albers, Casper J., Aurélien, Allard, Anderson, Ian A., Andreychik, Michael R., Peter, Babinčák, Baker, Bradley J., Gabriel, Baník, Ernest, Baskin, Jozef, Bavolar, Berkers, Ruud M. W. J., Michał, Białek, Joel, Blanke, Johannes, Breuer, Ambra, Brizi, Brown, Stephanie E. V., Florian, Brühlmann, Hendrik, Bruns, Leigh, Caldwell, Jean-François, Campourcy, Chan, Eugene Y., Yen-Ping, Chang, Cheung, Benjamin Y., Alycia, Chin, Cho, Kit W., Simon, Columbus, Paul, Conway, Corretti, Conrad A., Craig, Adam W., Curran, Paul G., Danvers, Alexander F., Dawson, Ian G. J., Day, Martin V., Erik, Dietl, Doerflinger, Johannes T., Alice, Dominici, Vilius, Dranseika, Edelsbrunner, Peter A., Edlund, John E., Matthew, Fisher, Anna, Fung, Oliver, Genschow, Timo, Gnambs, Goldberg, Matthew H., Lorenz, Graf-Vlachy, Hafenbrack, Andrew C., Sebastian, Hafenbrädl, Andree, Hartanto, Heck, Patrick R., Heffner, Joseph P., Joseph, Hilgard, Felix, Holzmeister, Horchak, Oleksandr V., Huang, Tina S. -T., Joachim, Hüffmeier, Sean, Hughes, Ian, Hussey, Roland, Imhoff, Bastian, Jaeger, Konrad, Jamro, Johnson, Samuel G. B., Andrew, Jones, Lucas, Keller, Olga, Kombeiz, Krueger, Lacy E., Anthony, Lantian, Laplante, Justin P., Lazarevic, Ljiljana B., Jonathan, Leclerc, Nicole, Legate, Leonhardt, James M., Leung, Desmond W., Levitan, Carmel A., Hause, Lin, Qinglan, Liu, Marco Tullio Liuzza, Locke, Kenneth D., Albert L., Ly, Maceacheron, Melanie D., Madan, Christopher R., Harry, Manley, Silvia, Mari, Marcel, Martončik, Mclean, Scott L., Jonathon, Mcphetres, Mercier, Brett G., Corinna, Michels, Mullarkey, Michael C., Musser, Erica D., Ladislas, Nalborczyk, Gustav, Nilsonne, Otis, Nicholas G., Otner, Sarah M. G., Otto, Philipp E., Oscar, Oviedo-Trespalacios, Mariola Paruzel- Czachura, Francesco, Pellegrini, Pereira, Vitor M. D., Hannah, Perfecto, Gerit, Pfuhl, Phillips, Mark H., Ori, Plonsky, Pozzi, Maura, Purić, Danka B., Brett, Raymond-Barker, Redman, David E., Reynolds, Caleb J., Ivan, Ropovik, Lukas, Röseler, Ruessmann, Janna K., Ryan, William H., Nika, Sablaturova, Schuepfer, Kurt J., Astrid, Schütz, Miroslav, Sirota, Matthias, Stefan, Stocks, Eric L., Strosser, Garrett L., Suchow, Jordan W., Anna, Szabelska, Tey, Kian-Siong S., Leonid, Tiokhin, Jais, Troian, Till, Utesch, Alejandro, Vásquez-Echeverría, Leigh Ann Vaughn, Mark, Verschoor, Bettina von Helversen, Pascal, Wallisch, Weissgerber, Sophia C., Wichman, Aaron L., Woike, Jan K., Iris, Žeželj, Zickfeld, Janis H., Yeonsin, Ahn, Blaettchen, Philippe F., Kang, Xi, Yoo Jin Lee, Parker, Philip M., Parker, Paul A., Song, Jamie S., May-Anne, Very, Lynn, Wong, Uhlmann, Eric L., Psychometrics and Statistics, The Crowdsourcing Hypothesis Tests Collaboration [Member of the MPIB: Jan K. Woike], Laboratoire Parisien de Psychologie Sociale (LAPPS), Université Paris Nanterre (UPN)-Université Paris 8 Vincennes-Saint-Denis (UP8), Human Technology Interaction, Psychologische Methodenleer (Psychologie, FMG), Psychology Other Research (FMG), Université Paris 8 Vincennes-Saint-Denis (UP8)-Université Paris Nanterre (UPN), Organizational Psychology, Department of Social Psychology, Landy, J, Jia, M, Ding, I, Viganola, D, Tierney, W, Dreber, A, Johannesson, M, Pfeiffer, T, Ebersole, C, Gronau, Q, Ly, A, van den Bergh, D, Marsman, M, Derks, K, Wagenmakers, E, Proctor, A, Bartels, D, Bauman, C, Brady, W, Cheung, F, Cimpian, A, Dohle, S, Donnellan, M, Hahn, A, Hall, M, Jiménez-Leal, W, Johnson, D, Lucas, R, Monin, B, Montealegre, A, Mullen, E, Pang, J, Ray, J, Reinero, D, Reynolds, J, Sowden, W, Storage, D, Su, R, Tworek, C, Van Bavel, J, Walco, D, Wills, J, Xu, X, Yam, K, Yang, X, Cunningham, W, Schweinsberg, M, Urwitz, M, The Crowdsourcing Hypothesis Tests, C, Uhlmann, E, Mari, S, and Imperial College London
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Research design ,1ST OFFERS ,1702 Cognitive Sciences ,Social Sciences ,050109 social psychology ,Ciências Sociais::Psicologia [Domínio/Área Científica] ,CONCEPTUAL REPLICATIONS ,Random Allocation ,Empirical research ,Crowdsourcing Hypothesis Tests Collaboration ,Psychology ,research robustness ,Psychology(all) ,General Psychology ,ComputingMilieux_MISCELLANEOUS ,Marketing ,05 social sciences ,SCIENCE ,Settore M-PSI/05 - PSICOLOGIA SOCIALE ,scientific transparency ,Research Design ,VDP::Samfunnsvitenskap: 200::Psykologi: 260 ,[SCCO.PSYC]Cognitive science/Psychology ,Crowdsourcing ,Cognitive Sciences ,crowdsourcing ,Cognitive psychology ,Adult ,replication ,Conceptual replications ,Social Psychology ,Implicit cognition ,VDP::Social science: 200::Psychology: 260 ,Bayesian probability ,forecasting ,stimulus sampling ,INDIVIDUAL-DIFFERENCES ,Scientific transparency ,Consistency (negotiation) ,History and Philosophy of Science ,Psychology, Multidisciplinary ,IMPLICIT ,Humans ,conceptual replications, crowdsourcing, forecasting, research robustness, scientific transparency ,0501 psychology and cognitive sciences ,ATTITUDES ,1505 Marketing ,METAANALYSIS ,M-PSI/05 - PSICOLOGIA SOCIALE ,Statistical hypothesis testing ,CONSEQUENCES ,business.industry ,Crowdsourced testing ,SOCIAL-PSYCHOLOGY ,M-PSI/03 - PSICOMETRIA ,1701 Psychology ,REPLICABILITY ,Research robustness ,business ,Forecasting - Abstract
©American Psychological Association, 2020. This paper is not the copy of record and may not exactly replicate the authoritative document published in the APA journal. Please do not copy or cite without author's permission. The final article is available, upon publication, at: https://doi.apa.org/doi/10.1037/bul0000220 To what extent are research results influenced by subjective decisions that scientists make as they design studies? Fifteen research teams independently designed studies to answer five original research questions related to moral judgments, negotiations, and implicit cognition. Participants from 2 separate large samples (total N 15,000) were then randomly assigned to complete 1 version of each study. Effect sizes varied dramatically across different sets of materials designed to test the same hypothesis: Materials from different teams rendered statistically significant effects in opposite directions for 4 of 5 hypotheses, with the narrowest range in estimates being d = 0.37 to 0.26. Meta-analysis and a Bayesian perspective on the results revealed overall support for 2 hypotheses and a lack of support for 3 hypotheses. Overall, practically none of the variability in effect sizes was attributable to the skill of the research team in designing materials, whereas considerable variability was attributable to the hypothesis being tested. In a forecasting survey, predictions of other scientists were significantly correlated with study results, both across and within hypotheses. Crowdsourced testing of research hypotheses helps reveal the true consistency of empirical support for a scientific claim.
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- 2020
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12. Purely rotational symmetry-protected topological crystalline insulator $��$-Bi4Br4
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Hsu, Chuang-Han, Zhou, Xiaoting, Ma, Qiong, Gedik, Nuh, Bansil, Arun, Pereira, Vitor M, Lin, Hsin, Fu, Liang, Xu, Su-Yang, and Chang, Tay-Rong
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Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences - Abstract
Recent theoretical advances have proposed a new class of topological crystalline insulator (TCI) phases protected by rotational symmetries. Distinct from topological insulators (TIs), rotational symmetry-protected TCIs are expected to show unique topologically protected boundary modes: First, the surface normal to the rotational axis features unpinned Dirac surface states whose Dirac points are located at generic k points. Second, due to the higher-order bulk boundary correspondence, a 3D TCI also supports 1D helical edge states. Despite the unique topological electronic properties, to date, purely rotational symmetry-protected TCIs remain elusive in real materials. Using first-principles band calculations and theoretical modeling, we identify the van der Waals material $��$-Bi4Br4 as a TCI purely protected by rotation symmetry. We show that the Bi4Br4's (010) surface exhibits a pair of unpinned topological Dirac fermions protected by the two-fold rotational axis. These unpinned Dirac fermions show an exotic spin texture highly favorable for spin transport and a band structure consisting of van Hove singularities due to Lifshitz transition. We also identify 1D topological hinge states along the edges of an $��$-Bi4Br4 rod. We further discuss how the proposed topological electronic properties in $��$-Bi4Br4 can be observed by various experimental techniques.
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- 2019
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13. Nonlinear magnetotransport shaped by Fermi surface topology and convexity in WTe2
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He, Pan, Hsu, Chuang-Han, Shi, Shuyuan, Cai, Kaiming, Wang, Junyong, Wang, Qisheng, Eda, Goki, Lin, Hsin, Pereira, Vitor M., and Yang, Hyunsoo
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Condensed Matter - Materials Science ,Condensed Matter - Mesoscale and Nanoscale Physics ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,Condensed Matter::Strongly Correlated Electrons - Abstract
The nature of Fermi surface defines the physical properties of conductors and many physical phenomena can be traced to its shape. Although the recent discovery of a current-dependent nonlinear magnetoresistance in spin-polarized non-magnetic materials has attracted considerable attention in spintronics, correlations between this phenomenon and the underlying fermiology remain unexplored. Here, we report the observation of nonlinear magnetoresistance at room temperature in a semimetal WTe2, with an interesting temperature-driven inversion. Theoretical calculations reproduce the nonlinear transport measurements and allow us to attribute the inversion to temperature-induced changes in Fermi surface convexity. We also report a large anisotropy of nonlinear magnetoresistance in WTe2, due to its low symmetry of Fermi surfaces. The good agreement between experiments and theoretical modeling reveals the critical role of Fermi surface topology and convexity on the nonlinear magneto-response. These results lay a new path to explore ramifications of distinct fermiology for nonlinear transport in condensed-matter.
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- 2019
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14. Anomalous quantum metal in a 2D crystalline superconductor with intrinsic electronic non-uniformity
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Li, Linjun, Chen, Chuan, Watanabe, Kenji, Taniguchi, Takashi, Zheng, Yi, Xu, Zhuan, Pereira, Vitor M., Loh, Kian Ping, and Neto, Antonio H. Castro
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Superconductivity (cond-mat.supr-con) ,Condensed Matter::Superconductivity ,Condensed Matter - Superconductivity ,FOS: Physical sciences - Abstract
The details of the superconducting to quantum metal transition (SQMT) at T=0 are an open problem that invokes much interest in the nature of this exotic and unexpected ground state1-3. However, the SQMT was not yet investigated in a crystalline 2D superconductor with coexisting and fluctuating quantum orders. Here, we report the observation of a SQMT in 2D ion-gel gated 1T-TiSe24, driven by magnetic field. A field-induced crossover between Bose quantum metal and vortex quantum creeping with increasing field is observed. We discuss the interplay between superconducting and CDW fluctuations (discommensurations) and their relation to the anomalous quantum metal (AQM) phase. From our findings, gate-tunable 1T-TiSe2 emerges as a privileged platform to scrutinize, in a controlled way, the details of the SQMT, the role of coexisting fluctuating orders and, ultimately, obtain a deeper understanding of the fate of superconductivity in strictly two-dimensional crystals near zero temperature.
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- 2018
15. Electrons imitating light: Frustrated supercritical collapse in charged arrays on graphene
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Lu, Jiong, Tsai, Hsin-Zon, Tatan, Alpin N., Wickenburg, Sebastian, Omrani, Arash A., Wong, Dillon, Riss, Alexander, Piatti, Erik, Watanabe, Kenji, Taniguchi, Takashi, Zettl, Alex, Pereira, Vitor M., and Crommie, Michael F.
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Condensed Matter - Mesoscale and Nanoscale Physics ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,Mathematics::Analysis of PDEs ,FOS: Physical sciences ,Nonlinear Sciences::Pattern Formation and Solitons - Abstract
The photon-like electronic dispersion of graphene bestows its charge carriers with unusual confinement properties that depend strongly on the geometry and strength of the surrounding potential. Here we report bottom-up synthesis of atomically-precise one-dimensional (1D) arrays of point charges aimed at exploring supercritical confinement of carriers in graphene for new geometries. The arrays were synthesized by arranging F4TCNQ molecules into a 1D lattice on back-gated graphene devices, allowing precise tuning of both the molecular charge state and the array periodicity. Dilute arrays of ionized F4TCNQ molecules are seen to behave like isolated subcritical charges but dense arrays show emergent supercriticality. In contrast to compact supercritical clusters, extended 1D charge arrays exhibit both supercritical and subcritical characteristics and belong to a new physical regime termed frustrated supercritical collapse. Here carriers in the far-field are attracted by a supercritical charge distribution, but have their fall to the center frustrated by subcritical potentials in the near-field, similar to the trapping of light by a dense cluster of stars in general relativity.
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- 2018
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16. Stent-Retriever Thrombectomy after Intravenous t-PA vs. t-PA Alone in Stroke
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Saver, Jeffrey L, Goyal, Mayank, Bonafe, Alain, Diener, Hans Christoph, Levy, Elad I, Pereira, Vitor M, Albers, Gregory W, Cognard, Christophe, Cohen, David J, Hacke, Werner, Jansen, Olav, Jovin, Tudor G, Mattle, Heinrich P, Nogueira, Raul G, Siddiqui, Adnan H, Yavagal, Dileep R, Baxter, Blaise W, Devlin, Thomas G, Lopes, Demetrius K, Reddy, Vivek K, du Mesnil de Rochemont, Richard, Singer, Oliver C, Jahan, Reza, Devlin, T, Baxter, B, Hawk, H, Sapkota, B, Quarfordt, S, Sirelkhatim, A, Dellinger, C, Barton, K, Reddy, V K, Jovin, T G, Ducruet, A, Jadhav, A, Horev, A, Giurgiutiu, D-V, Totoraitis, V, Hammer, M, Jankowitz, B, Wechsler, L, Rocha, M, Gulati, D, Campbell, D, Star, M, Baxendell, L, Oakley, J, Siddiqui, A H, Hopkins, L N, Levy, E, Snyder, K, Sawyer, R, Hall, S, Bonafé, A, Costalat, V, Riquelme, C, Machi, P, Omer, E, Arquizan, C, Mourand, I, Charif, M, Ayrignac, X, de Champfleur, N Menjot, Leboucq, N, Gascou, G, Moynier, M, du Mesnil de Rochemont, R, Singer, O, Berkefeld, J, Foerch, C, Lorenz, M, Pfeilschifer, W, Hattingen, E, Wagner, M, You, S-J, Lescher, S, Braun, H, Nogueira, R G, Dehkharghani, S, Belagaje, S R, Anderson, A, Lima, A, Obideen, M, Haussen, D, Dharia, R, Frankel, M, Patel, V, Owada, K, Saad, A, Amerson, L, Horn, C, Doppelheuer, S, Schindler, K, Lopes, D K, Chen, M, Moftakhar, R, Anton, C, Smreczak, M, Carpenter, J S, Boo, S, Rai, A, Roberts, T, Tarabishy, A, Gutmann, L, Brooks, C, Brick, J, Domico, J, Reimann, G, Hinrichs, K, Becker, M, Heiss, E, Selle, C, Witteler, A, Al-Boutros, S, Danch, M-J, Ranft, A, Rohde, S, Burg, K, Weimar, C, Zegarac, V, Hartmann, C, Schlamann, Marc, Göricke, Sophia Luise, Ringlestein, A, Wanke, Isabel, Mönninghoff, Christoph, Dietzold, M, Budzik, R, Davis, T, Eubank, G, Hicks, W J, Pema, P, Vora, N, Mejilla, J, Taylor, M, Clark, W, Rontal, A, Fields, J, Peterson, B, Nesbit, G, Lutsep, H, Bozorgchami, H, Priest, R, Ologuntoye, O, Barnwell, S, Dogan, A, Herrick, K, Takahasi, C, Beadell, N, Brown, B, Jamieson, S, Hussain, M S, Russman, A, Hui, F, Wisco, D, Uchino, K, Khawaja, Z, Katzan, I, Toth, G, Cheng-Ching, E, Bain, M, Man, S, Farrag, A, George, P, John, S, Shankar, L, Drofa, A, Dahlgren, R, Bauer, A, Itreat, A, Taqui, A, Cerejo, R, Richmond, A, Ringleb, P, Bendszus, M, Möhlenbruch, M, Reiff, T, Amiri, H, Purrucker, J, Herweh, C, Pham, M, Menn, O, Ludwig, I, Acosta, I, Villar, C, Morgan, W, Sombutmai, C, Hellinger, F, Allen, E, Bellew, M, Gandhi, R, Bonwit, E, Aly, J, Ecker, R D, Seder, D, Morris, J, Skaletsky, M, Belden, J, Baker, C, Connolly, L S, Papanagiotou, P, Roth, C, Kastrup, A, Politi, M, Brunner, F, Alexandrou, M, Merdivan, H, Ramsey, C, Given, C, Renfrow, S, Deshmukh, V, Sasadeusz, K, Vincent, F, Thiesing, J T, Putnam, J, Bhatt, A, Kansara, A, Caceves, D, Lowenkopf, T, Yanase, L, Zurasky, J, Dancer, S, Freeman, B, Scheibe-Mirek, T, Robison, J, Roll, J, Clark, D, Rodriguez, M, Fitzsimmons, B-F M, Zaidat, O, Lynch, J R, Lazzaro, M, Larson, T, Padmore, L, Das, E, Farrow-Schmidt, A, Hassan, A, Tekle, W, Cate, C, Jansen, O, Cnyrim, C, Wodarg, F, Wiese, C, Binder, A, Riedel, C, Rohr, A, Lang, N, Laufs, H, Krieter, S, Remonda, L, Diepers, M, Añon, J, Nedeltchev, K, Kahles, T, Biethahn, S, Lindner, M, Chang, V, Gächter, C, Esperon, C, Guglielmetti, M, Lara, J F Arenillas, Galdámez, M Martínez, Sanz, A I Calleja, Garcia, E Cortijo, Bermejo, P Garcia, Perez, S, Carrillo, P Mulero, Vallejo, E Crespo, Piñero, M Ruiz, Mesonero, L Lopez, Muñoz, F J Reyes, Brekenfeld, C, Buhk, J-H, Krützelmann, A, Thomalla, G, Cheng, B, Beck, C, Hoppe, J, Goebell, E, Holst, B, Grzyska, U, Wortmann, G, Starkman, S, Duckwiler, G, Jahan, R, Rao, N, Sheth, S, Ng, K, Noorian, A, Szeder, V, Nour, M, McManus, M, Huang, J, Tarpley, J, Tateshima, S, Gonzalez, N, Ali, L, Liebeskind, D, Hinman, J, Calderon-Arnulphi, M, Liang, C, Guzy, J, Yavagal, D R, Koch, S, DeSousa, K, Gordon-Perue, G, Elhammady, M, Peterson, E, Pandey, V, Dharmadhikari, S, Khandelwal, P, Malik, A, Pafford, R, Gonzalez, P, Ramdas, K, Andersen, G, Damgaard, D, Von Weitzel-Mudersbach, P, Simonsen, C, Ayudarte, N Ruiz de Morales, Poulsen, M, Sørensen, L, Karabegovich, S, Hjørringgaard, M, Hjort, N, Harbo, T, Sørensen, K, Deshaies, E, Padalino, D, Swarnkar, A, Latorre, J G, Elnour, E, El-Zammar, Z, Villwock, M, Farid, H, Balgude, A, Cross, L, Hansen, K, Holtmannspötter, M, Kondziella, D, Hoejgaard, J, Taudorf, S, Soendergaard, H, Wagner, A, Cronquist, M, Stavngaard, T, Cortsen, M, Krarup, L H, Hyldal, T, Haring, H-P, Guggenberger, S, Hamberger, M, Trenkler, J, Sonnberger, M, Nussbaumer, K, Dominger, C, Bach, E, Jagadeesan, B D, Taylor, R, Kim, J, Shea, K, Tummala, R, Zacharatos, H, Sandhu, D, Ezzeddine, M, Grande, A, Hildebrandt, D, Miller, K, Scherber, J, Hendrickson, A, Jumaa, M, Zaidi, S, Hendrickson, T, Snyder, V, Killer-Oberpfalzer, M, Mutzenbach, J, Weymayr, F, Broussalis, E, Stadler, K, Jedlitschka, A, Malek, A, Mueller-Kronast, N, Beck, P, Martin, C, Summers, D, Day, J, Bettinger, I, Holloway, W, Olds, K, Arkin, S, Akhtar, N, Boutwell, C, Crandall, S, Schwartzman, M, Weinstein, C, Brion, B, Prothmann, S, Kleine, J, Kreiser, K, Boeckh-Behrens, T, Poppert, H, Wunderlich, S, Koch, M L, Biberacher, V, Huberle, A, Gora-Stahlberg, G, Knier, B, Meindl, T, Utpadel-Fischler, D, Zech, M, Kowarik, M, Seifert, C, Schwaiger, B, Puri, A, Hou, S, Wakhloo, A, Moonis, M, Henniger, N, Goddeau, R, Massari, F, Minaeian, A, Lozano, J D, Ramzan, M, Stout, C, Patel, A, Tunguturi, A, Onteddu, S, Carandang, R, Howk, M, University of California [Los Angeles] (UCLA), University of California, Département de Neuroradiologie[Montpellier], Hôpital Gui de Chauliac [Montpellier]-Centre Hospitalier Régional Universitaire [Montpellier] (CHRU Montpellier)-Université Montpellier 1 (UM1)-Université de Montpellier (UM), Institut des Neurosciences de Montpellier - Déficits sensoriels et moteurs (INM), Institut National de la Santé et de la Recherche Médicale (INSERM)-Université de Montpellier (UM), and CHU Toulouse [Toulouse]
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Male ,medicine.medical_specialty ,Solitaire Cryptographic Algorithm ,Randomization ,Medizin ,610 Medicine & health ,Brain Ischemia ,law.invention ,Fibrinolytic Agents ,[SDV.MHEP.CSC]Life Sciences [q-bio]/Human health and pathology/Cardiology and cardiovascular system ,Randomized controlled trial ,Modified Rankin Scale ,law ,medicine ,Humans ,Intravenous tissue plasminogen activator ,Stroke ,Aged ,Thrombectomy ,Stent retriever ,Groin ,business.industry ,Endovascular Procedures ,General Medicine ,Middle Aged ,medicine.disease ,Combined Modality Therapy ,3. Good health ,Surgery ,Treatment Outcome ,medicine.anatomical_structure ,Tissue Plasminogen Activator ,Acute Disease ,Administration, Intravenous ,Female ,Stents ,business - Abstract
BACKGROUND: Among patients with acute ischemic stroke due to occlusions in the proximal anterior intracranial circulation, less than 40% regain functional independence when treated with intravenous tissue plasminogen activator (t-PA) alone. Thrombectomy with the use of a stent retriever, in addition to intravenous t-PA, increases reperfusion rates and may improve long-term functional outcome.METHODS: We randomly assigned eligible patients with stroke who were receiving or had received intravenous t-PA to continue with t-PA alone (control group) or to undergo endovascular thrombectomy with the use of a stent retriever within 6 hours after symptom onset (intervention group). Patients had confirmed occlusions in the proximal anterior intracranial circulation and an absence of large ischemic-core lesions. The primary outcome was the severity of global disability at 90 days, as assessed by means of the modified Rankin scale (with scores ranging from 0 [no symptoms] to 6 [death]).RESULTS: The study was stopped early because of efficacy. At 39 centers, 196 patients underwent randomization (98 patients in each group). In the intervention group, the median time from qualifying imaging to groin puncture was 57 minutes, and the rate of substantial reperfusion at the end of the procedure was 88%. Thrombectomy with the stent retriever plus intravenous t-PA reduced disability at 90 days over the entire range of scores on the modified Rankin scale (PCONCLUSIONS: In patients receiving intravenous t-PA for acute ischemic stroke due to occlusions in the proximal anterior intracranial circulation, thrombectomy with a stent retriever within 6 hours after onset improved functional outcomes at 90 days. (Funded by Covidien; SWIFT PRIME ClinicalTrials.gov number, NCT01657461.).
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- 2015
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17. Cost-Effectiveness of Solitaire Stent Retriever Thrombectomy for Acute Ischemic Stroke: Results From the SWIFT-PRIME Trial (Solitaire With the Intention for Thrombectomy as Primary Endovascular Treatment for Acute Ischemic Stroke)
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Shireman, Theresa I, Wang, Kaijun, Saver, Jeffrey L, Goyal, Mayank, Bonafé, Alain, Diener, Hans-Christoph, Levy, Elad I, Pereira, Vitor M, Albers, Gregory W, Cognard, Christophe, Hacke, Werner, Jansen, Olav, Jovin, Tudor G, Mattle, Heinrich P, Nogueira, Raul G, Siddiqui, Adnan H, Yavagal, Dileep R, Devlin, Thomas G, Lopes, Demetrius K, Reddy, Vivek K, du Mesnil de Rochemont, Richard, Jahan, Reza, Vilain, Katherine A, House, John, Lee, Jin-Moo, Cohen, David J, and SWIFT-PRIME Investigators
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Male ,Aging ,Comparative Effectiveness Research ,Cost-Benefit Analysis ,Clinical Trials and Supportive Activities ,Clinical Sciences ,SWIFT-PRIME Investigators ,Cardiorespiratory Medicine and Haematology ,Brain Ischemia ,Cohort Studies ,Clinical Research ,80 and over ,Humans ,Prospective Studies ,quality-adjusted life years ,tissue-type plasminogen activator ,Thrombectomy ,Aged ,Neurology & Neurosurgery ,Endovascular Procedures ,Neurosciences ,Middle Aged ,stroke ,Brain Disorders ,Hospitalization ,Treatment Outcome ,Good Health and Well Being ,Cost Effectiveness Research ,stents ,Equipment Failure ,Female ,Follow-Up Studies - Abstract
Background and purposeClinical trials have demonstrated improved 90-day outcomes for patients with acute ischemic stroke treated with stent retriever thrombectomy plus tissue-type plasminogen activator (SST+tPA) compared with tPA. Previous studies suggested that this strategy may be cost-effective, but models were derived from pooled data and older assumptions.MethodsIn this prospective economic substudy conducted alongside the SWIFT-PRIME trial (Solitaire With the Intention for Thrombectomy as Primary Endovascular Treatment for Acute Ischemic Stroke), in-trial costs were measured for patients using detailed medical resource utilization and hospital billing data. Utility weights were assessed at 30 and 90 days using the EuroQol-5 dimension questionnaire. Post-trial costs and life-expectancy were estimated for each surviving patient using a model based on trial data and inputs derived from a contemporary cohort of ischemic stroke survivors.ResultsIndex hospitalization costs were $17 183 per patient higher for SST+tPA than for tPA ($45 761 versus $28 578; P
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- 2017
18. Reproduction of the charge density wave phase diagram in $1T$-$\mathrm{TiSe}_2$ exposes its excitonic character
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Chen, Chuan, Singh, Bahadur, Lin, Hsin, and Pereira, Vitor M.
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Condensed Matter - Materials Science ,Condensed Matter - Mesoscale and Nanoscale Physics ,Condensed Matter::Superconductivity ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences ,Condensed Matter::Strongly Correlated Electrons - Abstract
Recent experiments suggest that excitonic degrees of freedom play an important role in precipitating the charge density wave (CDW) transition in $1T$-$\mathrm{TiSe}_2$. Through systematic calculations of the electronic and phonon spectrum based on density functional perturbation theory, we show that the predicted critical doping of the CDW phase overshoots the experimental value by 1 order of magnitude. In contrast, an independent self-consistent many-body calculation of the excitonic order parameter and renormalized band structure is able to capture the experimental phase diagram in extremely good qualitative and quantitative agreement. This demonstrates that electron-electron interactions and the excitonic instability arising from direct electron-hole coupling are pivotal to accurately describe the nature of the CDW in this system. This has important implications to understand the emergence of superconductivity within the CDW phase of this and related systems.
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- 2017
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19. Charge Density Waves and the Hidden Nesting of Purple Bronze K$_{0.9}$Mo$_6$O$_{17}$
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Su, Lei, Hsu, Chuang-Han, Lin, Hsin, and Pereira, Vitor M.
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Condensed Matter - Strongly Correlated Electrons ,Strongly Correlated Electrons (cond-mat.str-el) ,FOS: Physical sciences - Abstract
We introduce the first multiorbital effective tight-binding model to describe the effect of electron-electron interactions in this system. Upon fixing all the effective hopping parameters in the normal state against an ab initio band structure, and with only the overall scale of the interactions as the sole adjustable parameter, we find that a self-consistent Hartree-Fock solution reproduces extremely well the experimental behavior of the charge density wave (CDW) order parameter in the full range $0, Comment: Published version: 5 pages + Supplementary Material (13 pages); 5 figures
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- 2016
20. 3D phase contrast MRI: Partial volume correction for robust blood flow quantification in small intracranial vessels
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Bouillot, Pierre, Delattre, Bénédicte M. A., Brina, Olivier, Ouared, Rafik, Farhat, Mohamed, Chnafa, Christophe, Steinman, David A., Lovblad, Karl-Olof, Pereira, Vitor M., and Vargas, Maria I.
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Adult ,Male ,Models, Statistical ,Hemodynamics ,Intracranial Aneurysm ,ddc:500.2 ,Cerebral Arteries ,Middle Aged ,ddc:616.0757 ,Magnetic Resonance Imaging ,Imaging, Three-Dimensional ,Cerebrovascular Circulation ,Pulsatile Flow ,Humans ,Female ,Artifacts ,Blood Flow Velocity ,Carotid Artery, Internal - Abstract
Recent advances in 3D-PCMRI (phase contrast MRI) sequences allow for measuring the complex hemodynamics in cerebral arteries. However, the small size of these vessels vs spatial resolution can lead to non-negligible partial volume artifacts, which must be taken into account when computing blood flow rates. For this purpose, we combined the velocity information provided by 3D-PCMRI with vessel geometry measured with 3DTOF (time of flight MRI) or 3DRA (3D rotational angiography) to correct the partial volume effects in flow rate assessments.The proposed methodology was first tested in vitro on cylindrical and patient specific vessels subject to fully controlled pulsatile flows. Both 2D- and 3D-PCMRI measurements using various spatial resolutions ranging from 20 to 1.3 voxels per vessel diameter were analyzed and compared with flowmeter baseline. Second, 3DTOF, 2D- and 3D-PCMRI measurements were performed in vivo on 35 patients harboring internal carotid artery (ICA) aneurysms indicated for endovascular treatments requiring 3DRA imaging.The in vitro 2D- and 3D-PCMRI mean flow rates assessed with partial volume correction showed very low sensitivity to the acquisition resolution above ≈2 voxels per vessel diameter while uncorrected flow rates deviated critically when decreasing the spatial resolution. 3D-PCMRI flow rates measured in vivo in ICA agreed very well with 2D-PCMRI data and a good flow conservation was observed at the C7 bifurcation. Globally, partial volume correction led to 10-15% lower flow rates than uncorrected values as those reported in most of the published studies on intracranial flows.Partial volume correction may improve the accuracy of PCMRI flow rate measurements especially in small vessels such as intracranial arteries. Magn Reson Med 79:129-140, 2018. © 2017 International Society for Magnetic Resonance in Medicine.
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- 2016
21. Effect of endovascular reperfusion in relation to site of arterial occlusion
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Lemmens, Robin, Hamilton, Scott A, Liebeskind, David S, Tomsick, Tom A, Demchuk, Andrew M, Nogueira, Raul G, Marks, Michael P, Jahan, Reza, Gralla, Jan, Yoo, Albert J, Yeatts, Sharon D, Palesch, Yuko Y, Saver, Jeffrey L, Pereira, Vitor M, Broderick, Joseph P, Albers, Gregory W, Lansberg, Maarten G, DEFUSE 2, IMS III, STAR, and SWIFT trialists, and DEFUSE 2 IMS III STAR and SWIFT trialists
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Male ,Middle Cerebral Artery ,Clinical Trials and Supportive Activities ,Clinical Sciences ,Arterial Occlusive Diseases ,Cardiovascular ,Clinical Research ,Humans ,Prospective Studies ,Thrombectomy ,Randomized Controlled Trials as Topic ,and SWIFT trialists ,Neurology & Neurosurgery ,STAR ,DEFUSE 2 IMS III STAR and SWIFT trialists ,Endovascular Procedures ,Neurosciences ,DEFUSE 2 ,Internal ,Brain Disorders ,IMS III ,Stroke ,Treatment Outcome ,Infarction ,Reperfusion ,Female ,Cognitive Sciences ,Carotid Artery - Abstract
ObjectiveTo assess whether the association between reperfusion and improved clinical outcomes after stroke differs depending on the site of the arterial occlusive lesion (AOL).MethodsWe pooled data from Solitaire With the Intention for Thrombectomy (SWIFT), Solitaire FR Thrombectomy for Acute Revascularisation (STAR), Diffusion and Perfusion Imaging Evaluation for Understanding Stroke Evolution Study 2 (DEFUSE 2), and Interventional Management of Stroke Trial (IMS III) to compare the strength of the associations between reperfusion and clinical outcomes in patients with internal carotid artery (ICA), proximal middle cerebral artery (MCA) (M1), and distal MCA (M2/3/4) occlusions.ResultsAmong 710 included patients, the site of the AOL was the ICA in 161, the proximal MCA in 389, and the distal MCA in 160 patients (M2 = 131, M3 = 23, and M4 = 6). Reperfusion was associated with an increase in the rate of good functional outcome (modified Rankin Scale [mRS] score 0-2) in patients with ICA (odds ratio [OR] 3.5, 95% confidence interval [CI] 1.7-7.2) and proximal MCA occlusions (OR 6.2, 95% CI 3.8-10.2), but not in patients with distal MCA occlusions (OR 1.4, 95% CI 0.8-2.6). Among patients with M2 occlusions, a subset of the distal MCA cohort, reperfusion was associated with excellent functional outcome (mRS 0-1; OR 2.2, 95% CI 1.0-4.7).ConclusionsThe association between endovascular reperfusion and better clinical outcomes is more profound in patients with ICA and proximal MCA occlusions compared to patients with distal MCA occlusions. Because there are limited data from randomized controlled trials on the effect of endovascular therapy in patients with distal MCA occlusions, these results underscore the need for inclusion of this subgroup in future endovascular therapy trials.
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- 2016
22. Time to endovascular reperfusion and degree of disability in acute stroke
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Sheth, Sunil A, Jahan, Reza, Gralla, Jan, Pereira, Vitor M, Nogueira, Raul G, Levy, Elad I, Zaidat, Osama O, Saver, Jeffrey L, and SWIFT-STAR Trialists
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Male ,Time Factors ,Internationality ,Neurology & Neurosurgery ,Endovascular Procedures ,Clinical Sciences ,Neurosciences ,Middle Aged ,SWIFT-STAR Trialists ,Brain Disorders ,Stroke ,Clinical Research ,Reperfusion ,80 and over ,Humans ,Single-Blind Method ,Disabled Persons ,Female ,Prospective Studies ,Aged - Abstract
ObjectiveFaster time from onset to recanalization (OTR) in acute ischemic stroke using endovascular therapy (ET) has been associated with better outcome. However, previous studies were based on less-effective first-generation devices, and analyzed only dichotomized disability outcomes, which may underestimate the full effect of treatment.MethodsIn the combined databases of the SWIFT and STAR trials, we identified patients treated with the Solitaire stent retriever with achievement of substantial reperfusion (Thrombolysis in Cerebral Infarction [TICI] 2b-3). Ordinal numbers needed to treat values were derived by populating joint outcome tables.ResultsAmong 202 patients treated with ET with TICI 2b to 3 reperfusion, mean age was 68 (±13), 62% were female, and median National Institutes of Health Stroke Scale (NIHSS) score was 17 (interquartile range [IQR]: 14-20). Day 90 modified Rankin Scale (mRS) outcomes for OTR time intervals ranging from 180 to 480 minutes showed substantial time-related reductions in disability across the entire outcome range. Shorter OTR was associated with improved mean 90-day mRS (1.4 vs. 2.4 vs. 3.3, for OTR groups of 124-240 vs. 241-360 vs. 361-660 minutes; p < 0.001). The number of patients identified as benefitting from therapy with shorter OTR were 3-fold (range, 1.5-4.7) higher on ordinal, compared with dichotomized analysis. For every 15-minute acceleration of OTR, 34 per 1,000 treated patients had improved disability outcome.InterpretationAnalysis of disability over the entire outcome range demonstrates a marked effect of shorter time to reperfusion upon improved clinical outcome, substantially higher than binary metrics. For every 5-minute delay in endovascular reperfusion, 1 of 100 patients has a worse disability outcome.
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- 2015
23. Time to Endovascular Reperfusion and Degree of Disability in Acute Stroke
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Sheth, Sunil A., Jahan, Reza, Gralla, Jan, Pereira, Vitor M., Nogueira, Raul G., Levy, Elad I., Zaidat, Osama O., and Saver, Jeffrey L.
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Aged, 80 and over ,Male ,Internationality ,Time Factors ,Endovascular Procedures ,Middle Aged ,Article ,Stroke ,Reperfusion ,Humans ,Disabled Persons ,Female ,Single-Blind Method ,Prospective Studies ,Aged - Abstract
Faster time from onset to recanalization (OTR) in acute ischemic stroke using endovascular therapy (ET) has been associated with better outcome. However, previous studies were based on less-effective first-generation devices, and analyzed only dichotomized disability outcomes, which may underestimate the full effect of treatment.In the combined databases of the SWIFT and STAR trials, we identified patients treated with the Solitaire stent retriever with achievement of substantial reperfusion (Thrombolysis in Cerebral Infarction [TICI] 2b-3). Ordinal numbers needed to treat values were derived by populating joint outcome tables.Among 202 patients treated with ET with TICI 2b to 3 reperfusion, mean age was 68 (±13), 62% were female, and median National Institutes of Health Stroke Scale (NIHSS) score was 17 (interquartile range [IQR]: 14-20). Day 90 modified Rankin Scale (mRS) outcomes for OTR time intervals ranging from 180 to 480 minutes showed substantial time-related reductions in disability across the entire outcome range. Shorter OTR was associated with improved mean 90-day mRS (1.4 vs. 2.4 vs. 3.3, for OTR groups of 124-240 vs. 241-360 vs. 361-660 minutes; p0.001). The number of patients identified as benefitting from therapy with shorter OTR were 3-fold (range, 1.5-4.7) higher on ordinal, compared with dichotomized analysis. For every 15-minute acceleration of OTR, 34 per 1,000 treated patients had improved disability outcome.Analysis of disability over the entire outcome range demonstrates a marked effect of shorter time to reperfusion upon improved clinical outcome, substantially higher than binary metrics. For every 5-minute delay in endovascular reperfusion, 1 of 100 patients has a worse disability outcome.
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- 2015
24. Ischemic core and hypoperfusion volumes predict infarct size in SWIFT PRIME
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Albers, Gregory W., Goyal, Mayank, Jahan, Reza, Bonafe, Alain, Diener, Hans Christoph, Levy, Elad I., Pereira, Vitor M., Cognard, Christophe, Cohen, David J., Hacke, Werner, Jansen, Olav, Jovin, Tudor G., Mattle, Heinrich P., Nogueira, Raul G., Siddiqui, Adnan H., Yavagal, Dileep R., Baxter, Blaise W., Devlin, Thomas G., Lopes, Demetrius K., Reddy, Vivek K., du Mesnil de Rochemont, Richard, Singer, Oliver C., Bammer, Roland, Saver, Jeffrey L., Hotchkiss Brain Institute, University of California [Los Angeles] (UCLA), University of California, Centre Hospitalier Régional Universitaire [Montpellier] (CHRU Montpellier), Institut des Neurosciences de Montpellier - Déficits sensoriels et moteurs (INM), Institut National de la Santé et de la Recherche Médicale (INSERM)-Université de Montpellier (UM), Universität Duisburg-Essen [Essen], Universidade do Minho, Neuroradiologie Diagnostique et Thérapeutique [Toulouse], Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-CHU Toulouse [Toulouse]-Hôpital Purpan [Toulouse], CHU Toulouse [Toulouse], Institut des Systèmes Intelligents et de Robotique (ISIR), Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Universität Heidelberg [Heidelberg], University of Pittsburgh (PITT), Pennsylvania Commonwealth System of Higher Education (PCSHE), Emory University [Atlanta, GA], University at Buffalo [SUNY] (SUNY Buffalo), State University of New York (SUNY), Cardiology Division, Massachusetts General Hospital [Boston], Stanford School of Medicine [Stanford], Stanford Medicine, Stanford University-Stanford University, University of California (UC), Institut des Neurosciences de Montpellier (INM), Universität Duisburg-Essen = University of Duisburg-Essen [Essen], Universidade do Minho = University of Minho [Braga], Service Neuroradiologie Diagnostique et Thérapeutique [CHU Toulouse], Pôle imagerie médicale [CHU Toulouse], Centre Hospitalier Universitaire de Toulouse (CHU Toulouse)-Centre Hospitalier Universitaire de Toulouse (CHU Toulouse), and Universität Heidelberg [Heidelberg] = Heidelberg University
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Aged, 80 and over ,Male ,Endovascular Procedures ,Medizin ,Contrast Media ,Cerebral Infarction ,Middle Aged ,Prognosis ,Magnetic Resonance Imaging ,Brain Ischemia ,Stroke ,Fibrinolytic Agents ,Cerebrovascular Circulation ,Tissue Plasminogen Activator ,Outcome Assessment, Health Care ,Humans ,[SDV.NEU]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC] ,Female ,Prospective Studies ,Tomography, X-Ray Computed ,[SDV.MHEP]Life Sciences [q-bio]/Human health and pathology ,Aged - Abstract
International audience; OBJECTIVE:Within the context of a prospective randomized trial (SWIFT PRIME), we assessed whether early imaging of stroke patients, primarily with computed tomography (CT) perfusion, can estimate the size of the irreversibly injured ischemic core and the volume of critically hypoperfused tissue. We also evaluated the accuracy of ischemic core and hypoperfusion volumes for predicting infarct volume in patients with the target mismatch profile.METHODS:Baseline ischemic core and hypoperfusion volumes were assessed prior to randomized treatment with intravenous (IV) tissue plasminogen activator (tPA) alone versus IV tPA + endovascular therapy (Solitaire stent-retriever) using RAPID automated postprocessing software. Reperfusion was assessed with angiographic Thrombolysis in Cerebral Infarction scores at the end of the procedure (endovascular group) and Tmax > 6-second volumes at 27 hours (both groups). Infarct volume was assessed at 27 hours on noncontrast CT or magnetic resonance imaging (MRI).RESULTS:A total of 151 patients with baseline imaging with CT perfusion (79%) or multimodal MRI (21%) were included. The median baseline ischemic core volume was 6 ml (interquartile range= 0-16). Ischemic core volumes correlated with 27-hour infarct volumes in patients who achieved reperfusion (r = 0.58, p < 0.0001). In patients who did not reperfuse ( 6-second lesion volumes correlated with 27-hour infarct volume (r = 0.78, p = 0.005). In target mismatch patients, the union of baseline core and early follow-up Tmax > 6-second volume (ie, predicted infarct volume) correlated with the 27-hour infarct volume (r = 0.73, p < 0.0001); the median absolute difference between the observed and predicted volume was 13 ml.INTERPRETATION:Ischemic core and hypoperfusion volumes, obtained primarily from CT perfusion scans, predict 27-hour infarct volume in acute stroke patients who were treated with reperfusion therapies.
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- 2015
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25. Solitaire™ with the Intention for Thrombectomy as Primary Endovascular Treatment for Acute Ischemic Stroke (SWIFT PRIME) trial: protocol for a randomized, controlled, multicenter study comparing the Solitaire revascularization device with IV tPA with IV tPA alone in acute ischemic stroke
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Saver, Jeffrey L, Goyal, Mayank, Bonafe, Alain, Diener, Hans-Christoph, Levy, Elad I, Pereira, Vitor M, Albers, Gregory W, Cognard, Christophe, Cohen, David J, Hacke, Werner, Jansen, Olav, Jovin, Tudor G, Mattle, Heinrich P, Nogueira, Raul G, Siddiqui, Adnan H, Yavagal, Dileep R, Devlin, Thomas G, Lopes, Demetrius K, Reddy, Vivek, du Mesnil de Rochemont, Richard, Jahan, Reza, and SWIFT PRIME Investigators
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Male ,medicine.medical_treatment ,Medizin ,Severity of Illness Index ,recanalization ,Brain Ischemia ,Modified Rankin Scale ,Occlusion ,80 and over ,Prospective Studies ,Thrombectomy ,Aged, 80 and over ,Cerebral infarction ,SWIFT PRIME Investigators ,clinical trial ,Thrombolysis ,Middle Aged ,X-Ray Computed ,stent retriever ,Stroke ,Treatment Outcome ,Neurology ,Tissue Plasminogen Activator ,Injections, Intravenous ,endovascular ,Stents ,Female ,Intravenous ,Perfusion ,Adult ,Solitaire Cryptographic Algorithm ,medicine.medical_specialty ,acute ischemic stroke ,thrombolysis ,Tomography Scanners, X-Ray Computed ,Adolescent ,Clinical Trials and Supportive Activities ,Clinical Sciences ,Bioengineering ,610 Medicine & health ,and over ,Revascularization ,Injections ,Young Adult ,Fibrinolytic Agents ,Clinical Research ,medicine ,Humans ,Aged ,Tomography Scanners ,Neurology & Neurosurgery ,business.industry ,Neurosciences ,medicine.disease ,Brain Disorders ,Surgery ,Clinical trial ,business ,Protocols ,Magnetic Resonance Angiography ,Follow-Up Studies - Abstract
Rationale Early reperfusion in patients experiencing acute ischemic stroke is critical, especially for patients with large vessel occlusion who have poor prognosis without revascularization. Solitaire™ stent retriever devices have been shown to immediately restore vascular perfusion safely, rapidly, and effectively in acute ischemic stroke patients with large vessel occlusions. Aim The aim of the study was to demonstrate that, among patients with large vessel, anterior circulation occlusion who have received intravenous tissue plasminogen activator, treatment with Solitaire revascularization devices reduces degree of disability 3 months post stroke. Design The study is a global multicenter, two-arm, prospective, randomized, open, blinded end-point trial comparing functional outcomes in acute ischemic stroke patients who are treated with either intravenous tissue plasminogen activator alone or intravenous tissue plasminogen activator in combination with the Solitaire device. Up to 833 patients will be enrolled. Procedures Patients who have received intravenous tissue plasminogen activator are randomized to either continue with intravenous tissue plasminogen activator alone or additionally proceed to neurothrombectomy using the Solitaire device within six-hours of symptom onset. Study Outcomes The primary end-point is 90-day global disability, assessed with the modified Rankin Scale (mRS). Secondary outcomes include mortality at 90 days, functional independence (mRS ≤ 2) at 90 days, change in National Institutes of Health Stroke Scale at 27 h, reperfusion at 27 h, and thrombolysis in cerebral infarction 2b/3 flow at the end of the procedure. Analysis Statistical analysis will be conducted using simultaneous success criteria on the overall distribution of modified Rankin Scale (Rankin shift) and proportions of subjects achieving functional independence (mRS 0–2).
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- 2015
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26. Solitaire™ with the intention for thrombectomy as primary endovascular treatment for a cute ischemic stroke (SWIFT PRIME ) trial: protocol for a randomized, controlled, multicenter study comparing the Solitaire revascularization device with IV tPA with IV tPA alone in acute ischemic stroke
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Saver, Jeffrey L., Goyal, Mayank, Bonafe, Alain, Diener, Hans-Christoph, Levy, Elad I., Pereira, Vitor M., Albers, Gregory W., Cognard, Christophe, Cohen, David J., Hacke, Werner, Jansen, Olav, Jovin, Tudor G., Mattle, Heinrich P., Nogueira, Raul G., Siddiqui, Adnan H., Yavagal, Dileep R., Devlin, Thomas G., Lopes, Demetrius K., Reddy, Vivek, Du Mesnil de Rochemont, Richard Klaus Frieder, Jahan, Reza, and SWIFT PRIME Investigators
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ddc:610 - Abstract
Rationale: Early reperfusion in patients experiencing acute ischemic stroke is critical, especially for patients with large vessel occlusion who have poor prognosis without revascularization. S olitaire™ stent retriever devices have been shown to immediately restore vascular perfusion safely, rapidly, and effectively in acute ischemic stroke patients with large vessel occlusions. Aim: The aim of the study was to demonstrate that, among patients with large vessel, anterior circulation occlusion who have received intravenous tissue plasminogen activator, treatment with S olitaire revascularization devices reduces degree of disability 3 months post stroke. Design: The study is a global multicenter, two‐arm, prospective, randomized, open, blinded end‐point trial comparing functional outcomes in acute ischemic stroke patients who are treated with either intravenous tissue plasminogen activator alone or intravenous tissue plasminogen activator in combination with the Solitaire device. Up to 833 patients will be enrolled. Procedures:Patients who have received intravenous tissue plasminogen activator are randomized to either continue with intravenous tissue plasminogen activator alone or additionally proceed to neurothrombectomy using the S olitaire device within six‐hours of symptom onset. Study Outcomes: The primary end‐point is 90‐day global disability, assessed with the modified R ankin S cale (mRS). Secondary outcomes include mortality at 90 days, functional independence (mRS ≤ 2) at 90 days, change in N ational I nstitutes of H ealth S troke S cale at 27 h, reperfusion at 27 h, and thrombolysis in cerebral infarction 2b/3 flow at the end of the procedure. Analysis:Statistical analysis will be conducted using simultaneous success criteria on the overall distribution of modified R ankin S cale (R ankin shift) and proportions of subjects achieving functional independence (mRS 0–2).
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- 2015
27. The THRIVE score strongly predicts outcomes in patients treated with the Solitaire device in the SWIFT and STAR trials
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Flint, Alexander C, Cullen, Sean P, Rao, Vivek A, Faigeles, Bonnie S, Pereira, Vitor M, Levy, Elad I, Jovin, Tudor G, Liebeskind, David S, Nogueira, Raul G, Jahan, Reza, Saver, Jeffrey L, and SWIFT and STAR trialists
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Risk ,Male ,Clinical Sciences ,SWIFT and STAR trialists ,Cardiovascular ,Neurosurgical Procedures ,Brain Ischemia ,ischemic stroke ,Humans ,Health Status Indicators ,Prospective Studies ,Retrospective Studies ,Aged ,Neurology & Neurosurgery ,treatment ,Endovascular Procedures ,Neurosciences ,acute ,Prognosis ,cerebral infarction ,reperfusion ,Brain Disorders ,Stroke ,Treatment Outcome ,Logistic Models ,Good Health and Well Being ,ROC Curve ,Multivariate Analysis ,Female ,Patient Safety ,acute stroke therapy - Abstract
BackgroundThe Totaled Health Risks in Vascular Events (THRIVE) score strongly predicts clinical outcome, mortality, and risk of thrombolytic haemorrhage in ischemic stroke patients, and performs similarly well in patients receiving intravenous tissue plasminogen activator, endovascular stroke treatment, or no acute treatment. It is not known if the THRIVE score predicts outcomes with the Solitaire endovascular stroke treatment device.AimsTo validate the relationship between the THRIVE score and outcomes after treatment with the Solitaire endovascular stroke treatment device.MethodsThe study conducted a retrospective analysis of the prospective SWIFT and STAR trials to examine the relationship between THRIVE and outcomes after treatment with the Solitaire device. We examined the relationship between THRIVE and clinical outcomes (good outcome or death at 90 days) among patients in SWIFT and STAR. Receiver-operator characteristics curve analysis was used to compare THRIVE score performance with other stroke prediction scores. Multivariable modeling was used to confirm the independence of the THRIVE score from procedure-specific predictors (successful recanalization or device used) and other predictors of functional outcome.ResultsThe THRIVE score strongly predicts good outcome and death among patients treated with the Solitaire device in SWIFT and STAR (Mantel-Haenszel chi-square test for trend P
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- 2014
28. Prospective, multicenter, single-arm study of mechanical thrombectomy using Solitaire Flow Restoration in acute ischemic stroke
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Pereira, Vitor M, Gralla, Jan, Davalos, Antoni, Bonafé, Alain, Castaño, Carlos, Chapot, René, Liebeskind, David S, Nogueira, Raul G, Arnold, Marcel, Sztajzel, Roman, Liebig, Thomas, Goyal, Mayank, Besselmann, Michael, Moreno, Antonio, Moreno, Alfredo, Schroth, Gerhard, and the STAR Investigators
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Adult ,Male ,Middle Cerebral Artery ,Clinical Sciences ,Cardiorespiratory Medicine and Haematology ,Disease-Free Survival ,Clinical Research ,80 and over ,Humans ,Prospective Studies ,Thrombectomy ,Aged ,Neurology & Neurosurgery ,Endovascular Procedures ,stroke treatment ,Neurosciences ,mechanical embolectomy ,Cerebral Infarction ,Middle Aged ,Internal ,Brain Disorders ,Survival Rate ,Stroke ,the STAR Investigators ,Good Health and Well Being ,Acute Disease ,Female ,Carotid Artery - Abstract
Background and purposeMechanical thrombectomy using stent retriever devices have been advocated to increase revascularization in intracranial vessel occlusion. We present the results of a large prospective study on the use of the Solitaire Flow Restoration in patients with acute ischemic stroke.MethodsSolitaire Flow Restoration Thrombectomy for Acute Revascularization was an international, multicenter, prospective, single-arm study of Solitaire Flow Restoration thrombectomy in patients with large vessel anterior circulation strokes treated within 8 hours of symptom onset. Strict criteria for site selection were applied. The primary end point was the revascularization rate (thrombolysis in cerebral infarction ≥2b) of the occluded vessel as determined by an independent core laboratory. The secondary end point was the rate of good functional outcome (defined as 90-day modified Rankin scale, 0-2).ResultsA total of 202 patients were enrolled across 14 comprehensive stroke centers in Europe, Canada, and Australia. The median age was 72 years, 60% were female patients. The median National Institute of Health Stroke Scale was 17. Most proximal intracranial occlusion was the internal carotid artery in 18%, and the middle cerebral artery in 82%. Successful revascularization was achieved in 79.2% of patients. Device and procedure-related severe adverse events were found in 7.4%. Favorable neurological outcome was found in 57.9%. The mortality rate was 6.9%. Any intracranial hemorrhagic transformation was found in 18.8% of patients, 1.5% were symptomatic.ConclusionsIn this single-arm study, treatment with the Solitaire Flow Restoration device in intracranial anterior circulation occlusions results in high rates of revascularization, low risk of clinically relevant procedural complications, and good clinical outcomes in combination with low mortality at 90 days.Clinical trial registration urlhttp://www.clinicaltrials.gov. Unique identifier: NCT01327989.
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- 2013
29. Engenharia de tráfego robusta usando computação evolucionária para otimização de protocolos de encaminhamento
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Pereira, Vitor M. S., Sousa, Pedro, Rocha, Miguel, and Universidade do Minho
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656.1:681.3 ,Traffic engineering ,OSPF ,656.1 [681.3] ,681.3 [656.1] ,681.3:656.1 ,Computação evolucionária ,Evolutionary computation ,Engenharia de tráfego - Abstract
Dissertação de mestrado em Redes e Serviços de Comunicações, Nos últimos anos, têm surgido várias soluções que visam alcançar configurações eficientes para o encaminhamento de tráfego OSPF (Open Shortest Path First). Este trabalho tem por intento a prossecução da investigação nessa área, com o objetivo de alcançar mecanismos de otimização eficientes que sejam resilientes a mudanças relevantes no ambiente de uma rede. Essas alterações podem resultar de vários fatores, tais como, mudanças nas necessidade de tráfego, novas restrições de Qualidade de Serviço que têm de ser consideradas, alteração de compromissos entre objetivos de otimização, mudanças na topologia de rede, que resultem de atualizações (ou falhas) na infra-estrutura de rede, entre muitas outras possibilidades. Neste contexto, este trabalho irá consistir no desenvolvimento de técnicas de otimização, inspiradas no campo da Computação Evolucionária, que procuram resolver tais problemas. Em particular, serão testados vários algoritmos e configurações com o intuito de obter métodos que sejam capazes de fornecer configurações otimizadas de pesos OSPF robustas a alterações nos requisitos de tráfego e à falha de links. Para além de métodos que recorrem a multi-topologias, serão testados métodos que procuram otimizar configurações de pesos OSPF para duas matrizes de requisitos de tráfego, bem como métodos que procuram otimizar as configurações de pesos para a falha do link com maior carga. Para obter rapidamente novas configurações de pesos ideais (ou quase), também serão abordadas questões como a inicialização da população inicial em EAs (Algoritmos Evolucionários). Estes métodos e opções de configuração serão integrados numa aplicação amigável de apoio a administradores de redes., Over the past years, several solutions have emerged with the purpose of achieving efficient OSPF (Open Shortest Path First) routing configurations. This work intends to pursue such research aiming to devise efficient optimization mechanisms resilient to relevant changes in the network environment. Those changes may result from several factors such as, changes in the considered traffic demands, new Quality of Service constraints that should be considered, new tradeoffs between the optimization goals, network topology changes resulting from updates (or failures) in the network infrastructure, among many other possibilities. Under such circumstances, this work will devise optimization techniques inspired in the field of Evolutionary Computation to address such problems. In particular, several algorithms and configurations will be tested to achieve methods that are able to provide optimized OSPF weights configurations robust to changes in traffic demands and to link failure. In addition to methods that use multi-topology, methods that attempt to optimize OSPF weights settings for two traffic demands will be tested, as well as methods that attempt to optimize weights settings for the loadest link failure. To rapidly accomplish new (near) optimal weights, issues such as the seeding of the initial population in EAs (Evolutionary Algorithms) will be addressed. These methods and configuration options will be integrated into a user friendly application to support network administrators.
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- 2012
30. Polarization Charge Distribution in Gapped Graphene
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Kotov, Valeri N., Pereira, Vitor M., and Uchoa, Bruno
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Condensed Matter - Strongly Correlated Electrons ,Strongly Correlated Electrons (cond-mat.str-el) ,Condensed Matter - Mesoscale and Nanoscale Physics ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,FOS: Physical sciences - Abstract
We study the distribution of vacuum polarization charge induced by a Coulomb impurity in massive graphene. By analytically computing the polarization function, we show that the charge density is distributed in space in a non-trivial fashion, and on a characteristic length-scale set by the effective Compton wavelength. The density crosses over from a logarithmic behavior below this scale, to a power law variation above it. Our results in the continuum limit are confirmed by explicit diagonalization of the corresponding tight-binding model on a finite-size lattice. Electron-electron interaction effects are also discussed., 6 pages, 4 figures; expanded version
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- 2008
31. All-graphene integrated circuits via strain engineering
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Pereira, Vitor M. and Neto, Antonio H. Castro
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Condensed Matter - Materials Science ,Condensed Matter - Mesoscale and Nanoscale Physics ,Mesoscale and Nanoscale Physics (cond-mat.mes-hall) ,Materials Science (cond-mat.mtrl-sci) ,FOS: Physical sciences - Abstract
We propose a route to all-graphene integrated electronic devices by exploring the influence of strain on the electronic structure of graphene. We show that strain can be easily tailored to generate electron beam collimation, 1D channels, surface states and confinement, the basic elements for all-graphene electronics. In addition this proposal has the advantage that patterning can be made on substrates rather than on the graphene sheet, thereby protecting the integrity of the latter., Comment: Minor changes
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- 2008
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32. Double Exchange Model at Low Densities: Magnetic Polarons and Coulomb Suppressed Phase Separation
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Pereira, Vitor M., Santos, J. M. B. Lopes dos, and Neto, Antonio H. Castro
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Condensed Matter - Strongly Correlated Electrons ,Strongly Correlated Electrons (cond-mat.str-el) ,FOS: Physical sciences ,Condensed Matter::Strongly Correlated Electrons - Abstract
We consider the double exchange model at very low densities. The conditions for the formation of self-trapped magnetic polarons are analyzed using an independent polaron model. The issue of phase separation in the low density region of the temperature-density phase diagram is discussed. We show how electrostatic and localization effects can lead to the substantial suppression of the phase separated regime. By examining connections between the resulting phase and the polaronic phase, we conclude that they reflect essentially the same physical situation of a ferromagnetic droplet containing one single electron. In the ultra diluted regime, we explore the possible stabilization of a Wigner crystal of magnetic polarons. Our results are compared with the experimental evidence for a polaronic phase in europium hexaboride, and we are able to reproduce the experimental region of stability of the polaronic phase. We further demonstrate that phase-separation is a general feature expected in metallic ferromagnets whose bandwidth depends on the magnetization., Comment: This paper is a long version of arXiv:cond-mat/0505741
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- 2008
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33. The Double Exchange Model at Low Densities
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Pereira, Vitor M., Santos, J. M. B. Lopes dos, and Neto, A. H. Castro
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Condensed Matter - Strongly Correlated Electrons ,Strongly Correlated Electrons (cond-mat.str-el) ,FOS: Physical sciences ,Condensed Matter::Strongly Correlated Electrons - Abstract
We obtain the phase diagram of the double-exchange model at low electronic densities in the presence of electron-electron interactions. The single particle problem and its extension to low electronic densities, when a Wigner crystal of magnetic polarons is generated due to unscreened Coulomb interactions, is studied. It is argued that the Wigner crystal is the natural alternative to phase separation when the Coulomb interaction is taken into account. We discuss the thermal and quantum stability of the crystalline phase towards a polaronic Fermi liquid and a homogeneous, metallic, ferromagnetic phase. The relevance and application of our results to EuB_6 is also considered., Comment: 4 pages, 2 figures
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- 2005
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34. ADAPT technique with ACE68 and ACE64 reperfusion catheters in ischemic stroke treatment: results from the PROMISE study
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Schramm, Peter, Navia, Pedro, Papa, Rosario, Zamarro, Joaquin, Tomasello, Alejandro, Weber, Werner, Fiehler, Jens, Michel, Patrik, Pereira, Vitor M, Krings, Timo, Gralla, Jan, Santalucia, Paola, Pierot, Laurent, and Lo, T H
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610 Medicine & health ,3. Good health - Abstract
BACKGROUND AND PURPOSE The recent randomized trials demonstrated the benefit of mechanical thrombectomy in stroke therapy. However, treatment using different strategies is an ongoing area of investigation. The PROMISE study analyzed the safety and effectiveness of the Penumbra System with the ACE68 and ACE64 reperfusion catheters in aspiration thrombectomy of stroke, using A Direct Aspiration First Pass Technique (ADAPT). METHODS PROMISE was a prospective study which enrolled 204 patients with intracranial anterior circulation large vessel occlusion (LVO) ischemic stroke in 20 centers from February 2016 to May 2017. Initial treatment was with the ACE68/ACE64 catheters within 6 hours of symptom onset. Imaging and safety review was performed by an independent Core Laboratory and a Clinical Events Committee. The primary angiographic outcome was revascularization to mTICI 2b-3 at immediate post-procedure and the primary clinical outcome was 90-day modified Rankin Scale (mRS) score ≤2. Safety assessment included device- and procedure-related serious adverse events (SAEs), symptomatic intracranial hemorrhage (sICH), mortality, and embolization of new territory (ENT). RESULTS Enrolled patients had a median age of 74 (IQR 65-80) years and a median admission NIHSS of 16 (IQR 11-20). The post-procedure mTICI 2b-3 revascularization rate was 93.1% and the 90-day mRS 0-2 rate was 61%. Device- and procedure-related SAEs at 24 hours occurred in 1.5% and 3.4%, respectively, 90-day mortality was 7.5%, sICH occurred in 2.9% while ENT occurred in 1.5%. CONCLUSIONS For frontline therapy of LVO stroke, the ACE68/ACE64 catheters for aspiration thrombectomy were found to be safe and showed similar efficacy to randomized trials using other revascularization techniques. CLINICAL TRIAL REGISTRATION NCT02678169;Pre-results.
35. Epidemiology, pathophysiology, diagnosis, and management of intracranial artery dissection
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Ducros, Anne, Lyrer, Philippe A, Kloss, Manja, Arnold, Marcel, Jung, Simon, Grond-Ginsbach, Caspar, Sarikaya, Hakan, Chabrier, Stéphane, Bousser, Marie-Germaine, Reiner, Peggy, Pezzini, Alessandro, Metso, Tina M, Uyttenboogaart, Maarten, Worrall, Bradford B, Tatlisumak, Turgut, Engelter, Stefan T, Markus, Hugh S, Goeggel, Barbara, Giacalone, Giacomo, Martin, Juan J, Southerland, Andrew M, Baumgartner, Ralph, Minematsu, Kazuo, Brandt, Tobias, Debette, Stéphanie, Pereira, Vitor M, Kappelle, L Jaap, Mizutani, Tohru, Bersano, Anna, Majersik, Jennifer J, Thijs, Vincent, Stapf, Christian, Cole, John W, Meschia, James F, Béjot, Yannick, Welleweerd, Janna C, Bonati, Leo H, Leys, Didier, Naggara, Olivier, Schilling, Sabrina, Labeyrie, Marc-Antoine, Touzé, Emmanuel, Compter, Annette, De Borst, Gert Jan, Bijlenga, Philippe, and Chabriat, Hugues
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610 Medicine & health ,3. Good health
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