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Your search keyword '"Ferreira, Antoine"' showing total 20 results
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20 results on '"Ferreira, Antoine"'

3. Study of the effectiveness of incentive measures on Covid-19 vaccination in the United States of America

Author

De Pomereu, Théodore, Ferreira, Antoine Lopes, Leforestier, Lucas, Vinayagame, Vishnou, Bonnefoi, Hector, and Charpignon, Marie-Laure

Subjects
Statistics - Applications
Abstract

With COVID-19 having emerged as the most widespread human pandemic disease in a century, the need to control its spread to avoid massive loss of life became more than necessary, and extremely fast. Several vaccines were developed and the task of policy makers was suddenly to convince the reluctant population to be vaccinated by various means. While some countries have chosen a policy of mandatory vaccination or punitive incentives, many states in the United States have adopted various incentives to try to increase vaccination coverage. A study we conducted in recent months quantified the effect of these measures on the proportion of the population vaccinated, using the synthetic control method, by simulating what would have happened without these measures. The aim now is to generalize this study to smaller scales, to improve the results of our previous study, to quantify their robustness and to provide a tool that can be used by policy makers to adapt their behavior in light of the results obtained.

Published
2023

13. Motion Analysis and Real-Time Trajectory Prediction of Magnetically Steerable Catalytic Janus Micromotors

Author

Wu, Jiaen, Folio, David, Zhu, Jiawei, Jang, Bumjin, Chen, Xiangzhong, Feng, Junxiao, Gambardella, Pietro, Sort Viñas, Jordi, Puigmartí-Luis, Josep, Ergeneman, Olgac, Ferreira, Antoine, and Pané i Vidal, Salvador

Subjects
Bubble recoil propulsion, Directionality control, Magnetic Janus particles, Real-time trajectory prediction, bubble recoil propulsion, catalytic swimmers, directionality control, magnetic Janus particles, real-time trajectory prediction, Catalytic swimmers
Abstract

Chemically driven micromotors display unpredictable trajectories due to the rotational Brownian motion interacting with the surrounding fluid molecules. This hampers the practical applications of these tiny robots, particularly where precise control is a requisite. To overcome the rotational Brownian motion and increase motion directionality, robots are often decorated with a magnetic composition and guided by an external magnetic field. However, despite the straightforward method, explicit analysis and modeling of their motion have been limited. Here, catalytic Janus micromotors are fabricated with distinct magnetizations and a controlled self-propelled motion with magnetic steering is shown. To analyze their dynamic behavior, a dynamic model that can successfully predict the trajectory of micromotors in uniform viscous flows in real time by incorporating a form of state-dependent-coefficient with a robust two-stage Kalman filter is theoretically developed. A good agreement is observed between the theoretically predicted dynamics and experimental observations over a wide range of model parameter variations. The developed model can be universally adopted to various designs of catalytic micro-/nanomotors with different sizes, geometries, and materials, even in diverse fuel solutions. Finally, the proposed model can be used as a platform for biosensing, detecting fuel concentration, or determining small-scale motors' propulsion mechanisms in an unknown environment., Advanced Intelligent Systems, 4 (11), ISSN:2640-4567

Published
2022

19. Optimal Design of a Multipole-Electromagnet Robotic Platform for Ophthalmic Surgery.

Author

Chen, Ruipeng, Folio, David, and Ferreira, Antoine

Subjects
OPHTHALMIC surgery, ELECTROMAGNETS, ROBOTICS, MAGNETIC fields, DESIGN
Abstract

The aim of this study was to design a multipole-electromagnet robotic platform named OctoRob. This platform provides a minimally invasive means for targeted therapeutic interventions in specific intraocular areas. OctoRob is capable of generating both appropriate magnetic fields and gradients. The main scientific objectives were: (i) To propose an optimal reconfigurable arrangement of electromagnets suitable for ophthalmic interventions. (ii) To model, design and implement a one-degree-of-freedom robotic arm connected with an electromagnet in order to optimize the generation of magnetic fields and gradients. (iii) To evaluate the magnetic performances of the OctoRob platform, including different tilted angles. The results show that OctoRob platform has great potential to be applied for ophthalmic surgery. [ABSTRACT FROM AUTHOR]

Published
2023
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20. Catalytic Locomotion of Core–Shell Nanowire Motors

Author

Jang, Bumjin, Wang, Wei, Wiget, Samuel, Petruska, Andrew J., Chen, Xiangzhong, Hu, Chengzhi, Hong, Ayoung, Folio, David, Ferreira, Antoine, Pané, Salvador, and Nelson, Bradley J.

Abstract

We report Au/Ru core–shell nanowire motors. These nanowires are fabricated using our previously developed electrodeposition-based technique, and their catalytic locomotion in the presence of H2O2is investigated. Unlike conventional bimetallic nanowires that are self-electroosmotically propelled, our open-ended Au/Ru core–shell nanowires show both a noticeable decrease in rotational diffusivity and increase in motor speed with increasing nanowire length. Numerical modeling based on self-electroosmosis attributes decreases in rotational diffusivity to the formation of toroidal vortices at the nanowire tail, but fails to explain the speed increase with length. To reconcile this inconsistency, we propose a combined mechanism of self-diffusiophoresis and electroosmosis based on the oxygen gradient produced by catalytic shells. This mechanism successfully explains not only the speed increase of Au/Ru core–shell nanomotors with increasing length, but also the large variation in speed among Au/Ru, Au/Rh, and Rh/Au core–shell nanomotors. The possible contribution of diffusiophoresis to an otherwise well-established electroosmotic mechanism sheds light on future designs of nanomotors, at the same time highlighting the complex nature of nanoscale propulsion.

Published
2024
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