68 research outputs found
Pleijel’s Theorem for Schrödinger Operators
No full textWe are concerned in this paper with the real eigenfunctions of Schrödinger operators.We prove an asymptotic upper bound for the number of their nodal domains, which implies in particular that the inequality stated in Courant’s theorem is strict, except for finitely many eigenvalues. Results of this type originated in 1956 with Pleijel’s theorem on the Dirichlet Laplacian and were obtained for some classes of Schrödinger operators by the first author, alone and in collaboration with B. Helffer and T. Hoffmann-Ostenhof. Using methods in part inspired by work of the second author on Neumann and Robin Laplacians, we greatly extend the scope of these previous results
Asymptotic behavior of generalized capacities with applications to eigenvalue perturbations: The higher dimensional case
No full textWe provide a full series expansion of a generalization of the so-called u-capacity related to the Dirichlet-Laplacian in dimension three and higher, extending the results of Abatangelo et al. (2021); Abatangelo, Lena and Musolino (2022) dealing with the planar case. We apply the result in order to study the asymptotic behavior of perturbed eigenvalues when Dirichlet conditions are imposed on a small regular subset of the domain of the eigenvalue problem. (c) 2023 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)
Intégration des réseaux de distribution pour l'étude de scénarios prospectifs de décarbonation du système électrique
No full textDecarbonizing the energy system is one of the major challenges of the century. It requires transforming the way energy is produced and consumed, which can take decades. To anticipate these changes, prospective models are developed to propose decarbonization pathways. These pathways are mainly based on the electrification and the massive integration of renewable energies, especially solar and wind. However, existing prospective models have an insufficient spatial resolution to consider electrical distribution grids, which are highly impacted by these transformations. Therefore, the work conducted in this thesis is based on the coupling of a long-term prospective model (POLES), and a short-term optimization model (Backbone) considering electrical distribution and transmission grids. This coupling enables a resolution never reached at a national scale by a long-term energy model. However, it is computationally demanding. Consequently, simplifications have been conducted to reach more reasonable computation times while ensuring sufficient precision. Therefore, several scenarios have been analyzed, highlighting the major role of energy sufficiency in reducing the stress on the power system, and the benefits of developing demand flexibility.La décarbonation du système énergétique est un des enjeux majeurs de ce siècle. Cela requiert la transformation de la manière dont l’énergie est produite et consommée. Ces transformations nécessitant des changements profonds, elles ne peuvent pas se faire instantanément et se font donc à l’échelle décennal. Pour anticiper les changements à venir, des modèles prospectifs sont développés afin de proposer des trajectoires de décarbonation. Ces trajectoires se basent principalement sur l’électrification combinée à l’intégration massive d’énergies renouvelables, notamment solaire et éolienne. Cependant, les modèles prospectifs existants ont une résolution spatiale insuffisante pour prendre en compte les réseaux électriques de distribution, qui sont les premiers impactés par ces transformations. Ainsi, le travail mené au cours de cette thèse se base sur le couplage d’un modèle prospectif long terme (POLES), et d’un modèle d’optimisation court terme comprenant les réseaux électriques de distribution et transport (Backbone). Ce couplage permet d’obtenir une résolution à l’échelle nationale jamais atteinte par un modèle énergétique long terme, mais est cependant très gourmand en temps de calcul. Par conséquent, des simplifications ont été opérées pour atteindre des temps de calcul plus raisonnables tout en garantissant une précision suffisante. Ainsi, plusieurs scénarios ont pu être analysés, soulignant le rôle prépondérant de la sobriété dans la réduction du stress sur le système électrique, et l’intérêt de développer les flexibilités de la demande
Intégration des réseaux de distribution pour l'étude de scénarios prospectifs de décarbonation du système électrique
No full textDecarbonizing the energy system is one of the major challenges of the century. It requires transforming the way energy is produced and consumed, which can take decades. To anticipate these changes, prospective models are developed to propose decarbonization pathways. These pathways are mainly based on the electrification and the massive integration of renewable energies, especially solar and wind. However, existing prospective models have an insufficient spatial resolution to consider electrical distribution grids, which are highly impacted by these transformations. Therefore, the work conducted in this thesis is based on the coupling of a long-term prospective model (POLES), and a short-term optimization model (Backbone) considering electrical distribution and transmission grids. This coupling enables a resolution never reached at a national scale by a long-term energy model. However, it is computationally demanding. Consequently, simplifications have been conducted to reach more reasonable computation times while ensuring sufficient precision. Therefore, several scenarios have been analyzed, highlighting the major role of energy sufficiency in reducing the stress on the power system, and the benefits of developing demand flexibility.La décarbonation du système énergétique est un des enjeux majeurs de ce siècle. Cela requiert la transformation de la manière dont l’énergie est produite et consommée. Ces transformations nécessitant des changements profonds, elles ne peuvent pas se faire instantanément et se font donc à l’échelle décennal. Pour anticiper les changements à venir, des modèles prospectifs sont développés afin de proposer des trajectoires de décarbonation. Ces trajectoires se basent principalement sur l’électrification combinée à l’intégration massive d’énergies renouvelables, notamment solaire et éolienne. Cependant, les modèles prospectifs existants ont une résolution spatiale insuffisante pour prendre en compte les réseaux électriques de distribution, qui sont les premiers impactés par ces transformations. Ainsi, le travail mené au cours de cette thèse se base sur le couplage d’un modèle prospectif long terme (POLES), et d’un modèle d’optimisation court terme comprenant les réseaux électriques de distribution et transport (Backbone). Ce couplage permet d’obtenir une résolution à l’échelle nationale jamais atteinte par un modèle énergétique long terme, mais est cependant très gourmand en temps de calcul. Par conséquent, des simplifications ont été opérées pour atteindre des temps de calcul plus raisonnables tout en garantissant une précision suffisante. Ainsi, plusieurs scénarios ont pu être analysés, soulignant le rôle prépondérant de la sobriété dans la réduction du stress sur le système électrique, et l’intérêt de développer les flexibilités de la demande
Geometric bounds for the magnetic Neumann eigenvalues in the plane
No full textWe consider the eigenvalues of the magnetic Laplacian on a bounded domain Omega of R-2 with uniform magnetic field beta > 0 and magnetic Neumann boundary conditions. We find upper and lower bounds for the ground state energy lambda(1) and we provide semiclassical estimates in the spirit of Kroger for the first Riesz mean of the eigenvalues. We also discuss upper bounds for the first eigenvalue for non-constant magnetic fields beta = beta(x) on a simply connected domain in a Riemannian surface. In particular: we prove the upper bound lambda(1) infinity and consists of the semiclassical limit 2 pi k/ |Omega| plus an oscillating term.We also construct several examples, showing the importance of the topology: in particular we show that an arbitrarily small tubular neighborhood of a generic simple closed curve has lowest eigenvalue bounded away from zero, contrary to the case of a simply connected domain of small area, for which lambda(1) is always small.(c) 2023 The Author(s). Published by Elsevier Masson SAS. This is an open access article under the CC BY license (http://creativecommons .org /licenses /by /4 .0/)
Subordonnées conditionnelles en Quechua Cochabambino
No full textThis record deals with the if-clauses in Quechua Cochabambino. This elicitation aims at elaborating a typology of these clauses.Cet enregistrement traite des subordonnées conditionnelles en Quechua Cochabambino. Il s'agit d'une élicitation cherchant à élaborer une typologie des conditionnelles dans cette langue
Fables d'Ésope 2: Les Hommes
No full textThis is a tight little book, 6 x 7¾. It contains eighty-six of Aesop's fables drawn from either Chambry's 1927 translation or a version done by Hachette in 1913 without attribution to an author. To go with those texts there are eleven full-page illustrations noted on 85 and a number of other designs along the way. Six of the full-page illustrations are colored. For an inexpensive edition, this book does a good job with the art! There is a T of C at the back. I am not sure that I have ever seen Aesop's work divided into animals and people before this! See the companion volume on animals.This is a hardbound book (hard cover)This book has a dust jacket (book cover)Language note: FrenchOriginal language: greTraduction, introduction et notes par Daniel Loayz
Point defect engineering in Ge
No full textThesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2016.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (pages 121-127).In 1947, the first transistor was made of germanium, but soon silicon became the core material of computer chips because of its processability. However, as the typical dimensions of transistors are getting closer to the atomic size, the traditional approach of scaling down transistors to improve performance is reaching its limits, and other elements need to be used in conjunction with silicon. Germanium is one of the key materials to empower silicon based devices because it possesses electronic and optoelectronic properties complementary to those of silicon, among them higher carrier mobilities and a direct band gap (G-valley) at 1.55 [mu]m (the telecom C-band, therefore adding new capabilities to silicon integrated microphotonics). Furthermore, good quality Ge layers can be grown epitaxially on a Si substrate, allowing a monolithic integration of devices. However, compared to silicon, little is known about the point defects in germanium. The goal of the present doctoral work is to remedy this gap. To this end, we have used radiation (gamma rays, alpha particles, and neutrons) to controllably introduce point defects in crystalline germanium, which were then characterized by Deep-Level Transient Spectroscopy (DLTS), a technique that allows the determination of the activation energy, capture cross-section, and concentration of the said defects. By studying their electronic properties, annealing kinetics, and introduction rates, we were able to separate vacancy-containing from interstitial-containing defects and gain insight on their physical nature and formation process. We especially identified a di-interstitial defect and a tri-interstitial defect. In addition, we proved that in the case of alpha particles and neutron irradiation, the fact that defects are generated in a collision cascade influences their carrier capture rates and annealing behaviors. We have also characterized the impact of radiation on commercial germanium-on-silicon photodetectors, and showed that point defects associate with dislocations in epitaxial Ge-on-Si layers. Finally, we have investigated the passivation of midgap states by implanting germanium with fluorine, and showed how the interaction between the halogen element, the amorphous/crystalline interface during the solid phase epitaxy, and the implantation damage is key in obtaining a high performance materialby Corentin Monmeyran.Ph. D
Dufour et al. Source Data.xlsx
No full textDataset used to create every graph of the paper "Phenotypic characterization of single CD4+ T cells harboring genetically intact and inducible HIV genomes" in Nature Communications
Author list: Caroline Dufour1, Corentin Richard1, Marion Pardons1, Marta Massanella1, Antoine Ackaoui1, Ben Murrell2, Bertrand Routy1, Réjean Thomas3, Jean-Pierre Routy4, Rémi Fromentin1, Nicolas Chomont1
1Centre de Recherche du CHUM and Department of Microbiology, Infectiology and Immunology, Université de Montréal, Montreal, H2X 0A9, Quebec, Canada
2Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet, Stockholm, 171 77, Sweden
3Clinique médicale l’Actuel, Montreal, H2L 4P9, Quebec, Canada
4Division of Hematology & Chronic Viral Illness Service, McGill University Heath Centre, Montreal, H4A 3J1, Quebec, Canada</p
Estimation of the modulation of friction from the mechanical impedance variations
No full textUltrasonic surface-haptic touchscreens produce compelling tactile sensations directly on the users' fingertips. The tactile sensations stem from the modulation of friction produced by acoustic radiation pressure, which reduces the contact between the skin and the glass plate. During this process, some of the vibrations are partly absorbed by the tissues, resulting in a conspicuous change in the vibration amplitude of the plate upon contact with the finger, which manifests as a net change in the system mechanical impedance. In this study, we leverage the observable change of impedance to estimate the acoustic levitation and the frictional force. The self-sensing method utilizes a model of the first principles governing the physical interaction between the plate and the skin, which relies on multi-scale contact theory. The model accurately describes the experimental influence of the amplitude on the observed impedance (i.e., the amount of energy absorbed and reflected) and can be used to estimate the friction coefficient (R2=0.93). These results provide additional evidence of the partial levitation mechanism at play in ultrasonic friction-modulation. This finding can be useful for designing energy-efficient devices and provide design suggestions for using ultrasonic impedance for self-sensing friction forces.Accepted Author ManuscriptHuman-Robot Interactio
- …
