1
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Thekkadath G, England D, Bouchard F, Zhang Y, Kim M, Sussman B. Intensity interferometry for holography with quantum and classical light. Sci Adv 2023; 9:eadh1439. [PMID: 37406121 DOI: 10.1126/sciadv.adh1439] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 05/30/2023] [Indexed: 07/07/2023]
Abstract
As first demonstrated by Hanbury Brown and Twiss, it is possible to observe interference between independent light sources by measuring correlations in their intensities rather than their amplitudes. In this work, we apply this concept of intensity interferometry to holography. We combine a signal beam with a reference and measure their intensity cross-correlations using a time-tagging single-photon camera. These correlations reveal an interference pattern from which we reconstruct the signal wavefront in both intensity and phase. We demonstrate the principle with classical and quantum light, including a single photon. Since the signal and reference do not need to be phase-stable nor from the same light source, this technique can be used to generate holograms of self-luminous or remote objects using a local reference, thus opening the door to new holography applications.
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Affiliation(s)
- Guillaume Thekkadath
- National Research Council of Canada, 100 Sussex Drive, Ottawa, ON K1A 0R6, Canada
- Department of Physics, Imperial College London, Prince Consort Rd, London SW7 2AZ, UK
| | - Duncan England
- National Research Council of Canada, 100 Sussex Drive, Ottawa, ON K1A 0R6, Canada
| | - Frédéric Bouchard
- National Research Council of Canada, 100 Sussex Drive, Ottawa, ON K1A 0R6, Canada
| | - Yingwen Zhang
- National Research Council of Canada, 100 Sussex Drive, Ottawa, ON K1A 0R6, Canada
- Department of Physics, University of Ottawa, Ottawa, ON K1N 6N5, Canada
| | - Myungshik Kim
- Department of Physics, Imperial College London, Prince Consort Rd, London SW7 2AZ, UK
| | - Benjamin Sussman
- National Research Council of Canada, 100 Sussex Drive, Ottawa, ON K1A 0R6, Canada
- Department of Physics, University of Ottawa, Ottawa, ON K1N 6N5, Canada
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2
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Thériault R, Ismail S, Bouchard F, Tétreault-Laflamme A, Richard P, Jeldres C, Morin C, Vallières É, Tu L. Retrospective study of mid- and long-term urinary complications in patients with prostate cancer treated with radiotherapy and/or radical prostatectomy. Eur Urol 2023. [DOI: 10.1016/s0302-2838(23)00303-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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3
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Hiekkamäki M, Bouchard F, Fickler R. Photonic Angular Superresolution Using Twisted N00N States. Phys Rev Lett 2021; 127:263601. [PMID: 35029483 DOI: 10.1103/physrevlett.127.263601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 10/01/2021] [Accepted: 11/16/2021] [Indexed: 06/14/2023]
Abstract
The increased phase sensitivity of N00N states has been used in many experiments, often involving photon paths or polarization. Here we experimentally combine the phase sensitivity of N00N states with the orbital angular momentum (OAM) of photons up to 100 ℏ, to resolve rotations of a light field around its optical axis. The results show that both a higher photon number and larger OAM increase the resolution and achievable sensitivity. The presented method opens a viable path to unconditional angular supersensitivity and accessible generation of N00N states between any transverse light fields.
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Affiliation(s)
- Markus Hiekkamäki
- Tampere University, Photonics Laboratory, Physics Unit, Tampere FI-33720, Finland
| | - Frédéric Bouchard
- National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario K1A 0R6, Canada
| | - Robert Fickler
- Tampere University, Photonics Laboratory, Physics Unit, Tampere FI-33720, Finland
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4
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Malaterre C, Dussault AC, Mermans E, Barker G, Beisner BE, Bouchard F, Desjardins E, Handa IT, Kembel SW, Lajoie G, Maris V, Munson AD, Odenbaugh J, Poisot T, Shapiro BJ, Suttle CA. Corrigendum: Functional Diversity: An Epistemic Roadmap. Bioscience 2021. [DOI: 10.1093/biosci/biab078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Christophe Malaterre
- Canada Research Chair, Philosophy of the Life Sciences and professor of philosophy, Université du Québec à Montréal (UQAM). His research focuses on the analysis of explanatory schemas, biological sciences, from origins of life to biodiversity studies
| | - Antoine C Dussault
- Centre interuniversitaire de recherche sur la science et la technologie (CIRST) and philosophy instructor, Collège Lionel-Groulx. His main research interests are the philosophy of ecology and environmental ethics
| | - Ely Mermans
- Université de Montréal and at Université Paris 1 Panthéon Sorbonne, who investigates the concept of keystone species in relation to ecocentric ethics
| | - Gillian Barker
- University of Western Ontario. She specializes in environmental philosophy and broader relationship between science and values
| | - Beatrix E Beisner
- Department of Biological Sciences, UQAM and directs the Interuniversity Group in Limnology and Aquatic Environments (GRIL). Her work focuses on aquatic biodiversity and community ecology
| | - Frédéric Bouchard
- Université de Montréal. He specializes in the philosophy of biology, notably questions about individuality
| | - Eric Desjardins
- University of Western Ontario. His research focuses on developing new perspectives for understanding and building resilient social-ecological systems
| | - I Tanya Handa
- Department of biological sciences, Université du Québec à Montréal (UQAM). Her research has contributed to extending the functional trait approach to understand community assembly, biotic interactions and ecosystem functions of soil invertebrates
| | - Steven W Kembel
- Department of biological sciences, UQAM. His research focuses on understanding the ecological and evolutionary processes responsible for patterns of plant and microbial biodiversity
| | - Geneviève Lajoie
- Department of biological sciences, Université du Québec à Montréal (UQAM). Her research focuses on plant-microbe interactions
| | - Virginie Maris
- Centre d’écologie fonctionnelle et évolutive (CEFE UMR 5175), CNRS. She specializes in environmental philosophy, environmental ethics and the epistemology of ecology and conservation sciences
| | - Alison D Munson
- Département des sciences du bois et de la forêt, Université Laval, Canada. Her research explores soil-plant relations in managed and natural ecosystems, tree diversity and ecosystem function, and plant traits in relation to soil carbon stabilization
| | - Jay Odenbaugh
- Department of Philosophy, Lewis & Clark College. He specializes in philosophy of ecology and evolution
| | - Timothée Poisot
- department of biological sciences, Université de Montréal. He focuses on quantitative and computational ecology
| | - B Jesse Shapiro
- Department of biological sciences, Université de Montréal. He is a computational evolutionary biologist interested in identifying ecologically and clinically important signatures of positive natural selection in microbial genomes
| | - Curtis A Suttle
- Department of Earth, Ocean and Atmospheric Sciences, Department of Botany, Department of Microbiology and Immunology, and the Institute for the Oceans and Fisheries, University of British Columbia, Canada. His research is primarily focused on viruses and their role in the environment
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5
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Bouchard F, Sit A, Zhang Y, Fickler R, Miatto FM, Yao Y, Sciarrino F, Karimi E. Two-photon interference: the Hong-Ou-Mandel effect. Rep Prog Phys 2021; 84:012402. [PMID: 33232945 DOI: 10.1088/1361-6633/abcd7a] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Nearly 30 years ago, two-photon interference was observed, marking the beginning of a new quantum era. Indeed, two-photon interference has no classical analogue, giving it a distinct advantage for a range of applications. The peculiarities of quantum physics may now be used to our advantage to outperform classical computations, securely communicate information, simulate highly complex physical systems and increase the sensitivity of precise measurements. This separation from classical to quantum physics has motivated physicists to study two-particle interference for both fermionic and bosonic quantum objects. So far, two-particle interference has been observed with massive particles, among others, such as electrons and atoms, in addition to plasmons, demonstrating the extent of this effect to larger and more complex quantum systems. A wide array of novel applications to this quantum effect is to be expected in the future. This review will thus cover the progress and applications of two-photon (two-particle) interference over the last three decades.
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Affiliation(s)
- Frédéric Bouchard
- Department of Physics, University of Ottawa, Advanced Research Complex, 25 Templeton Street, Ottawa ON K1N 6N5, Canada
| | - Alicia Sit
- Department of Physics, University of Ottawa, Advanced Research Complex, 25 Templeton Street, Ottawa ON K1N 6N5, Canada
| | - Yingwen Zhang
- National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario K1A 0R6, Canada
| | - Robert Fickler
- Department of Physics, University of Ottawa, Advanced Research Complex, 25 Templeton Street, Ottawa ON K1N 6N5, Canada
| | - Filippo M Miatto
- Télécom Paris, LTCI, Institut Polytechnique de Paris, 19 Place Marguerite Peray, 91120 Palaiseau, France
| | - Yuan Yao
- Télécom Paris, LTCI, Institut Polytechnique de Paris, 19 Place Marguerite Peray, 91120 Palaiseau, France
| | - Fabio Sciarrino
- Dipartimento di Fisica, Sapienza Università di Roma, Piazzale Aldo Moro 5, I-00185 Roma, Italy
| | - Ebrahim Karimi
- Department of Physics, University of Ottawa, Advanced Research Complex, 25 Templeton Street, Ottawa ON K1N 6N5, Canada
- National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario K1A 0R6, Canada
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6
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Hufnagel F, Sit A, Grenapin F, Bouchard F, Heshami K, England D, Zhang Y, Sussman BJ, Boyd RW, Leuchs G, Karimi E. Characterization of an underwater channel for quantum communications in the Ottawa River. Opt Express 2019; 27:26346-26354. [PMID: 31674518 DOI: 10.1364/oe.27.026346] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2019] [Accepted: 07/23/2019] [Indexed: 06/10/2023]
Abstract
We examine the propagation of optical beams possessing different polarization states and spatial modes through the Ottawa River in Canada. A Shack-Hartmann wavefront sensor is used to record the distorted beam's wavefront. The turbulence in the underwater channel is analysed, and associated Zernike coefficients are obtained in real-time. Finally, we explore the feasibility of transmitting polarization states as well as spatial modes through the underwater channel for applications in quantum cryptography.
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7
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Malaterre C, Dussault AC, Rousseau-Mermans S, Barker G, Beisner BE, Bouchard F, Desjardins E, Handa IT, Kembel SW, Lajoie G, Maris V, Munson AD, Odenbaugh J, Poisot T, Shapiro BJ, Suttle CA. Functional Diversity: An Epistemic Roadmap. Bioscience 2019. [DOI: 10.1093/biosci/biz089] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Abstract
Functional diversity holds the promise of understanding ecosystems in ways unattainable by taxonomic diversity studies. Underlying this promise is the intuition that investigating the diversity of what organisms actually do (i.e., their functional traits) within ecosystems will generate more reliable insights into the ways these ecosystems behave, compared to considering only species diversity. But this promise also rests on several conceptual and methodological (i.e., epistemic) assumptions that cut across various theories and domains of ecology. These assumptions should be clearly addressed, notably for the sake of an effective comparison and integration across domains, and for assessing whether or not to use functional diversity approaches for developing ecological management strategies. The objective of this contribution is to identify and critically analyze the most salient of these assumptions. To this aim, we provide an epistemic roadmap that pinpoints these assumptions along a set of historical, conceptual, empirical, theoretical, and normative dimensions.
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Affiliation(s)
| | | | | | | | | | | | | | - I Tanya Handa
- Department of biological sciences, Université du Québec à Montréal
| | | | - Geneviève Lajoie
- Department of biological sciences, Université du Québec à Montréal
| | | | - Alison D Munson
- Département des sciences du bois et de la forêt, Université Laval, Canada
| | | | | | | | - Curtis A Suttle
- Department of Earth, Ocean and Atmospheric Sciences, Department of Botany, Department of Microbiology and Immunology
- Institute for the Oceans and Fisheries at the University of British Columbia, Canada
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8
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Lord E, Pathmanathan JS, Corel E, Makarenkov V, Lopez P, Bouchard F, Bhattacharya D, Antoine PO, Le Guyader H, Lapointe FJ, Bapteste E. Introducing Trait Networks to Elucidate the Fluidity of Organismal Evolution Using Palaeontological Data. Genome Biol Evol 2019; 11:2653-2665. [PMID: 31504500 PMCID: PMC6761957 DOI: 10.1093/gbe/evz182] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/03/2019] [Indexed: 11/25/2022] Open
Abstract
Explaining the evolution of animals requires ecological, developmental, paleontological, and phylogenetic considerations because organismal traits are affected by complex evolutionary processes. Modeling a plurality of processes, operating at distinct time-scales on potentially interdependent traits, can benefit from approaches that are complementary treatments to phylogenetics. Here, we developed an inclusive network approach, implemented in the command line software ComponentGrapher, and analyzed trait co-occurrence of rhinocerotoid mammals. We identified stable, unstable, and pivotal traits, as well as traits contributing to complexes, that may follow to a common developmental regulation, that point to an early implementation of the postcranial Bauplan among rhinocerotoids. Strikingly, most identified traits are highly dissociable, used repeatedly in distinct combinations and in different taxa, which usually do not form clades. Therefore, the genes encoding these traits are likely recruited into novel gene regulation networks during the course of evolution. Our evo-systemic framework, generalizable to other evolved organizations, supports a pluralistic modeling of organismal evolution, including trees and networks.
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Affiliation(s)
- Etienne Lord
- Département d'informatique, Université du Québec à Montréal, Montréal, Québec, Canada
- Département de sciences biologiques, Université de Montréal, Montréal, Québec, Canada
| | - Jananan S Pathmanathan
- Institut de Systématique, Evolution, Biodiversité (ISYEB), Sorbonne Université, CNRS, Museum National d'Histoire Naturelle, EPHE, Université des Antilles, Paris, France
| | - Eduardo Corel
- Institut de Systématique, Evolution, Biodiversité (ISYEB), Sorbonne Université, CNRS, Museum National d'Histoire Naturelle, EPHE, Université des Antilles, Paris, France
| | - Vladimir Makarenkov
- Département d'informatique, Université du Québec à Montréal, Montréal, Québec, Canada
| | - Philippe Lopez
- Institut de Systématique, Evolution, Biodiversité (ISYEB), Sorbonne Université, CNRS, Museum National d'Histoire Naturelle, EPHE, Université des Antilles, Paris, France
| | - Frédéric Bouchard
- Département de Philosophie, Université de Montreal, Montréal, Quebec, Canada
| | | | - Pierre-Olivier Antoine
- Institut des Sciences de l'Evolution, cc64, Université de Montpellier, CNRS, Université des Antilles, IRD, EPHE, Montpellier, France
| | - Hervé Le Guyader
- Institut de Systématique, Evolution, Biodiversité (ISYEB), Sorbonne Université, CNRS, Museum National d'Histoire Naturelle, EPHE, Université des Antilles, Paris, France
| | - François-Joseph Lapointe
- Département de sciences biologiques, Université de Montréal, Montréal, Québec, Canada
- Institut de Systématique, Evolution, Biodiversité (ISYEB), Sorbonne Université, CNRS, Museum National d'Histoire Naturelle, EPHE, Université des Antilles, Paris, France
| | - Eric Bapteste
- Institut de Systématique, Evolution, Biodiversité (ISYEB), Sorbonne Université, CNRS, Museum National d'Histoire Naturelle, EPHE, Université des Antilles, Paris, France
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9
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Bouchard F, Koutný D, Hufnagel F, Hradil Z, Řeháček J, Teo YS, Ahn D, Jeong H, Sánchez-Soto LL, Leuchs G, Karimi E. Compressed sensing of twisted photons. Opt Express 2019; 27:17426-17434. [PMID: 31252702 DOI: 10.1364/oe.27.017426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 05/22/2019] [Indexed: 06/09/2023]
Abstract
The ability to completely characterize the state of a system is an essential element for the emerging quantum technologies. Here, we present a compressed-sensing-inspired method to ascertain any rank-deficient qudit state, which we experimentally encode in photonic orbital angular momentum. We efficiently reconstruct these qudit states from a few scans with an intensified CCD camera. Since it only requires a small number of intensity measurements, our technique provides an easy and accurate way to identify quantum sources, channels, and systems.
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10
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Ahn D, Teo YS, Jeong H, Bouchard F, Hufnagel F, Karimi E, Koutný D, Řeháček J, Hradil Z, Leuchs G, Sánchez-Soto LL. Adaptive Compressive Tomography with No a priori Information. Phys Rev Lett 2019; 122:100404. [PMID: 30932629 DOI: 10.1103/physrevlett.122.100404] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Indexed: 06/09/2023]
Abstract
Quantum state tomography is both a crucial component in the field of quantum information and computation and a formidable task that requires an incogitable number of measurement configurations as the system dimension grows. We propose and experimentally carry out an intuitive adaptive compressive tomography scheme, inspired by the traditional compressed-sensing protocol in signal recovery, that tremendously reduces the number of configurations needed to uniquely reconstruct any given quantum state without any additional a priori assumption whatsoever (such as rank information, purity, etc.) about the state, apart from its dimension.
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Affiliation(s)
- D Ahn
- Department of Physics and Astronomy, Seoul National University, 08826 Seoul, South Korea
| | - Y S Teo
- Department of Physics and Astronomy, Seoul National University, 08826 Seoul, South Korea
| | - H Jeong
- Department of Physics and Astronomy, Seoul National University, 08826 Seoul, South Korea
| | - F Bouchard
- Physics Department, University of Ottawa, 25 Templeton Street, Ottawa, Ontario, K1N 6N5 Canada
| | - F Hufnagel
- Physics Department, University of Ottawa, 25 Templeton Street, Ottawa, Ontario, K1N 6N5 Canada
| | - E Karimi
- Physics Department, University of Ottawa, 25 Templeton Street, Ottawa, Ontario, K1N 6N5 Canada
| | - D Koutný
- Department of Optics, Palacký University, 17. listopadu 12, 77146 Olomouc, Czech Republic
| | - J Řeháček
- Department of Optics, Palacký University, 17. listopadu 12, 77146 Olomouc, Czech Republic
| | - Z Hradil
- Department of Optics, Palacký University, 17. listopadu 12, 77146 Olomouc, Czech Republic
| | - G Leuchs
- Max-Planck-Institut für die Physik des Lichts, Staudtstraße 2, 91058 Erlangen, Germany
| | - L L Sánchez-Soto
- Max-Planck-Institut für die Physik des Lichts, Staudtstraße 2, 91058 Erlangen, Germany
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11
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Zhang Y, Sit A, Bouchard F, Larocque H, Grenapin F, Cohen E, Elitzur AC, Harden JL, Boyd RW, Karimi E. Interaction-free ghost-imaging of structured objects. Opt Express 2019; 27:2212-2224. [PMID: 30732261 DOI: 10.1364/oe.27.002212] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Accepted: 12/23/2018] [Indexed: 06/09/2023]
Abstract
Quantum - or classically correlated - light can be employed in various ways to improve resolution and measurement sensitivity. In an "interaction-free" measurement, a single photon can be used to reveal the presence of an object placed within one arm of an interferometer without being absorbed by it. With a technique known as "ghost-imaging", entangled photon pairs are used for detecting an opaque object with significantly improved signal-to-noise ratio while preventing over-illumination. Here, we integrate these two methods to obtain a new imaging technique which we term "interaction-free ghost-imaging" (IFGI). With this new technique, we reduce photon illumination on the object by up to 26.5% while still maintaining at least the same image quality of conventional ghost-imaging. Alternatively, IFGI can improve image signal-to-noise ratio by 18% when given the same number of interacting photons as in standard ghost-imaging. IFGI is also sensitive to phase and polarisation changes of the photons introduced by a structured object. These advantages make IFGI superior for probing light-sensitive materials and biological tissues.
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12
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Bouchard F, Valencia NH, Brandt F, Fickler R, Huber M, Malik M. Measuring azimuthal and radial modes of photons. Opt Express 2018; 26:31925-31941. [PMID: 30650772 DOI: 10.1364/oe.26.031925] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 10/08/2018] [Indexed: 06/09/2023]
Abstract
With the emergence of the field of quantum communications, the appropriate choice of photonic degrees of freedom used for encoding information is of paramount importance. Highly precise techniques for measuring the polarisation, frequency, and arrival time of a photon have been developed. However, the transverse spatial degree of freedom still lacks a measurement scheme that allows the reconstruction of its full transverse structure with a simple implementation and a high level of accuracy. Here we show a method to measure the azimuthal and radial modes of Laguerre-Gaussian beams with a greater than 99 % accuracy, using a single phase screen. We compare our technique with previous commonly used methods and demonstrate the significant improvements it presents for quantum key distribution and state tomography of high-dimensional quantum states of light. Moreover, our technique can be readily extended to any arbitrary family of spatial modes, such as mutually unbiased bases, Hermite-Gauss, and Ince-Gauss. Our scheme will significantly enhance existing quantum and classical communication protocols that use the spatial structure of light, as well as enable fundamental experiments on spatial-mode entanglement to reach their full potential.
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13
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Sit A, Fickler R, Alsaiari F, Bouchard F, Larocque H, Gregg P, Yan L, Boyd RW, Ramachandran S, Karimi E. Quantum cryptography with structured photons through a vortex fiber. Opt Lett 2018; 43:4108-4111. [PMID: 30160728 DOI: 10.1364/ol.43.004108] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Accepted: 07/26/2018] [Indexed: 06/08/2023]
Abstract
Optical fiber links and networks are integral components within and between cities' communication infrastructures. Implementing quantum cryptographic protocols on either existing or new fiber links will provide information-theoretical security to fiber data transmissions. However, there is a need for ways to increase the channel bandwidth. Using the transverse spatial degree of freedom is one way to transmit more information and increase tolerable error thresholds by extending the common qubit protocols to high-dimensional quantum key distribution (QKD) schemes. Here we use one type of vortex fiber where the transverse spatial modes serves as an additional channel to encode quantum information by structuring the spin and orbital angular momentum of light. In this proof-of-principle experiment, we show that two-dimensional structured photons can be used in such vortex fibers in addition to the common two-dimensional polarization encryption, thereby paving the path to QKD multiplexing schemes.
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14
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Bouchard F, Sit A, Hufnagel F, Abbas A, Zhang Y, Heshami K, Fickler R, Marquardt C, Leuchs G, Boyd RW, Karimi E. Quantum cryptography with twisted photons through an outdoor underwater channel. Opt Express 2018; 26:22563-22573. [PMID: 30130947 DOI: 10.1364/oe.26.022563] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Accepted: 06/29/2018] [Indexed: 05/27/2023]
Abstract
Quantum communication has been successfully implemented in optical fibres and through free-space. Fibre systems, though capable of fast key and low error rates, are impractical in communicating with destinations without an established fibre link. Free-space quantum channels can overcome such limitations and reach long distances with the advent of satellite-to-ground links. However, turbulence, resulting from local fluctuations in refractive index, becomes a major challenge by adding errors and losses. Recently, an interest in investigating the possibility of underwater quantum channels has arisen. Here, we investigate the effect of turbulence on an underwater quantum channel using twisted photons in outdoor conditions. We study the effect of turbulence on transmitted error rates, and compare different quantum cryptographic protocols in an underwater quantum channel, showing the feasibility of high-dimensional encoding schemes. Our work may open the way for secure high-dimensional quantum communication between submersibles, and provides important input for potential submersibles-to-satellite quantum communication.
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15
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Congedo M, Rodrigues PLC, Bouchard F, Barachant A, Jutten C. A closed-form unsupervised geometry-aware dimensionality reduction method in the Riemannian Manifold of SPD matrices. Annu Int Conf IEEE Eng Med Biol Soc 2017; 2017:3198-3201. [PMID: 29060578 DOI: 10.1109/embc.2017.8037537] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Riemannian geometry has been found accurate and robust for classifying multidimensional data, for instance, in brain-computer interfaces based on electroencephalography. Given a number of data points on the manifold of symmetric positive-definite matrices, it is often of interest to embed these points in a manifold of smaller dimension. This is necessary for large dimensions in order to preserve accuracy and useful in general to speed up computations. Geometry-aware methods try to accomplish this task while respecting as much as possible the geometry of the original data points. We provide a closed-form solution for this problem in a fully unsupervised setting. Through the analysis of three brain-computer interface data bases we show that our method allows substantial dimensionality reduction without affecting the classification accuracy.
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16
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Grillo V, Harvey TR, Venturi F, Pierce JS, Balboni R, Bouchard F, Carlo Gazzadi G, Frabboni S, Tavabi AH, Li ZA, Dunin-Borkowski RE, Boyd RW, McMorran BJ, Karimi E. Observation of nanoscale magnetic fields using twisted electron beams. Nat Commun 2017; 8:689. [PMID: 28947803 PMCID: PMC5613010 DOI: 10.1038/s41467-017-00829-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2016] [Accepted: 07/31/2017] [Indexed: 11/09/2022] Open
Abstract
Electron waves give an unprecedented enhancement to the field of microscopy by providing higher resolving power compared to their optical counterpart. Further information about a specimen, such as electric and magnetic features, can be revealed in electron microscopy because electrons possess both a magnetic moment and charge. In-plane magnetic structures in materials can be studied experimentally using the effect of the Lorentz force. On the other hand, full mapping of the magnetic field has hitherto remained challenging. Here we measure a nanoscale out-of-plane magnetic field by interfering a highly twisted electron vortex beam with a reference wave. We implement a recently developed holographic technique to manipulate the electron wavefunction, which gives free electrons an additional unbounded quantized magnetic moment along their propagation direction. Our finding demonstrates that full reconstruction of all three components of nanoscale magnetic fields is possible without tilting the specimen. Beyond high resolving power, electron microscopy can be used to study both the electronic and magnetic properties of a sample. Here, Grillo et al. combine electron vortex beams with holographic detection to measure out-of-plane nanoscale magnetic fields.
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Affiliation(s)
- Vincenzo Grillo
- CNR-Istituto Nanoscienze, Centro S3, Via G Campi 213/a, I-41125, Modena, Italy.,CNR-IMEM Parco Area delle Scienze 37/A, I-43124, Parma, Italy
| | - Tyler R Harvey
- Department of Physics, University of Oregon, Eugene, OR, 97403-1274, USA
| | - Federico Venturi
- CNR-Istituto Nanoscienze, Centro S3, Via G Campi 213/a, I-41125, Modena, Italy.,Dipartimento FIM, Universitá di Modena e Reggio Emilia, Via G. Campi 213/a, I-41125, Modena, Italy
| | - Jordan S Pierce
- Department of Physics, University of Oregon, Eugene, OR, 97403-1274, USA
| | | | - Frédéric Bouchard
- Department of Physics, University of Ottawa, 25 Templeton St., Ottawa, ON, Canada, K1N 6N5
| | - Gian Carlo Gazzadi
- CNR-Istituto Nanoscienze, Centro S3, Via G Campi 213/a, I-41125, Modena, Italy
| | - Stefano Frabboni
- CNR-Istituto Nanoscienze, Centro S3, Via G Campi 213/a, I-41125, Modena, Italy.,Dipartimento FIM, Universitá di Modena e Reggio Emilia, Via G. Campi 213/a, I-41125, Modena, Italy
| | - Amir H Tavabi
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum, Jülich, 52425, Germany
| | - Zi-An Li
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum, Jülich, 52425, Germany.,Institute of Physics, Chinese Academy of Sciences (CAS), Beijing, 100190, China
| | - Rafal E Dunin-Borkowski
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum, Jülich, 52425, Germany
| | - Robert W Boyd
- Department of Physics, University of Ottawa, 25 Templeton St., Ottawa, ON, Canada, K1N 6N5.,Institute of Optics, University of Rochester, Rochester, NY, 14627, USA.,School of Physics and Astronomy, University of Glasgow, Glasgow, G12 8QQ, UK
| | | | - Ebrahim Karimi
- Department of Physics, University of Ottawa, 25 Templeton St., Ottawa, ON, Canada, K1N 6N5. .,Department of Physics, Institute for Advanced Studies in Basic Sciences, Zanjan, 45137-66731, Iran.
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17
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Larocque H, Gagnon-Bischoff J, Mortimer D, Zhang Y, Bouchard F, Upham J, Grillo V, Boyd RW, Karimi E. Generalized optical angular momentum sorter and its application to high-dimensional quantum cryptography. Opt Express 2017; 25:19832-19843. [PMID: 29041670 DOI: 10.1364/oe.25.019832] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Accepted: 07/24/2017] [Indexed: 06/07/2023]
Abstract
The orbital angular momentum (OAM) carried by optical beams is a useful quantity for encoding information. This form of encoding has been incorporated into various works ranging from telecommunications to quantum cryptography, most of which require methods that can rapidly process the OAM content of a beam. Among current state-of-the-art schemes that can readily acquire this information are so-called OAM sorters, which consist of devices that spatially separate the OAM components of a beam. Such devices have found numerous applications in optical communications, a field that is in constant demand for additional degrees of freedom, such as polarization and wavelength, into which information can also be encoded. Here, we report the implementation of a device capable of sorting a beam based on its OAM and polarization content, which could be of use in works employing both of these degrees of freedom as information channels. After characterizing our fabricated device, we demonstrate how it can be used for quantum communications via a quantum key distribution protocol.
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18
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Mohit V, Culley A, Lovejoy C, Bouchard F, Vincent WF. Hidden biofilms in a far northern lake and implications for the changing Arctic. NPJ Biofilms Microbiomes 2017; 3:17. [PMID: 28702216 PMCID: PMC5500582 DOI: 10.1038/s41522-017-0024-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2017] [Revised: 06/07/2017] [Accepted: 06/09/2017] [Indexed: 11/25/2022] Open
Abstract
Shallow lakes are common across the Arctic landscape and their ecosystem productivity is often dominated by benthic, cyanobacterial biofilms. Many of these water bodies freeze to the bottom and are biologically inactive during winter, but full freeze-up is becoming less common with Arctic warming. Here we analyzed the microbiome structure of newly discovered biofilms at the deepest site of a perennially ice-covered High Arctic lake as a model of polar microbial communities that remain unfrozen throughout the year. Biofilms were also sampled from the lake’s shallow moat region that melts out and refreezes to the bottom annually. Using high throughput small subunit ribosomal RNA sequencing, we found more taxonomic richness in Bacteria, Archaea and microbial eukaryotes in the perennially unfrozen biofilms compared to moat communities. The deep communities contained both aerobic and anaerobic taxa including denitrifiers, sulfate reducers, and methanogenic Archaea. The water overlying the deep biofilms was well oxygenated in mid-summer but almost devoid of oxygen in spring, indicating anoxia during winter. Seasonally alternating oxic-anoxic regimes may become increasingly widespread in polar biofilms as fewer lakes and ponds freeze to the bottom, favoring prolonged anaerobic metabolism and greenhouse gas production during winter darkness.
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Affiliation(s)
- Vani Mohit
- Département de biologie & Centre d'études nordiques (CEN), Université Laval, Québec, QC G1V 0A6 Canada.,Département de biochimie, de microbiologie et de bio-informatique, & Centre d'études nordiques (CEN), Université Laval, Québec, QC G1V 0A6 Canada.,Institut de biologie intégrative et des systèmes (IBIS), Université Laval, Québec, QC G1V 0A6 Canada.,Takuvik, Unité Mixte Internationale (UMI 3376) Université Laval (Canada) & Centre National de la Recherche Scientifique (France), Québec, QC GIV 0A6 Canada
| | - Alexander Culley
- Département de biochimie, de microbiologie et de bio-informatique, & Centre d'études nordiques (CEN), Université Laval, Québec, QC G1V 0A6 Canada.,Institut de biologie intégrative et des systèmes (IBIS), Université Laval, Québec, QC G1V 0A6 Canada
| | - Connie Lovejoy
- Département de biologie & Centre d'études nordiques (CEN), Université Laval, Québec, QC G1V 0A6 Canada.,Institut de biologie intégrative et des systèmes (IBIS), Université Laval, Québec, QC G1V 0A6 Canada.,Takuvik, Unité Mixte Internationale (UMI 3376) Université Laval (Canada) & Centre National de la Recherche Scientifique (France), Québec, QC GIV 0A6 Canada
| | - Frédéric Bouchard
- Centre Eau Terre Environnement, Institut national de la recherche scientifique (INRS), Centre d'études nordiques (CEN), Québec, QC G1K 9A9 Canada
| | - Warwick F Vincent
- Département de biologie & Centre d'études nordiques (CEN), Université Laval, Québec, QC G1V 0A6 Canada.,Takuvik, Unité Mixte Internationale (UMI 3376) Université Laval (Canada) & Centre National de la Recherche Scientifique (France), Québec, QC GIV 0A6 Canada
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19
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Grillo V, Tavabi AH, Venturi F, Larocque H, Balboni R, Gazzadi GC, Frabboni S, Lu PH, Mafakheri E, Bouchard F, Dunin-Borkowski RE, Boyd RW, Lavery MPJ, Padgett MJ, Karimi E. Measuring the orbital angular momentum spectrum of an electron beam. Nat Commun 2017; 8:15536. [PMID: 28537248 PMCID: PMC5458084 DOI: 10.1038/ncomms15536] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2016] [Accepted: 04/06/2017] [Indexed: 11/25/2022] Open
Abstract
Electron waves that carry orbital angular momentum (OAM) are characterized by a quantized and unbounded magnetic dipole moment parallel to their propagation direction. When interacting with magnetic materials, the wavefunctions of such electrons are inherently modified. Such variations therefore motivate the need to analyse electron wavefunctions, especially their wavefronts, to obtain information regarding the material's structure. Here, we propose, design and demonstrate the performance of a device based on nanoscale holograms for measuring an electron's OAM components by spatially separating them. We sort pure and superposed OAM states of electrons with OAM values of between −10 and 10. We employ the device to analyse the OAM spectrum of electrons that have been affected by a micron-scale magnetic dipole, thus establishing that our sorter can be an instrument for nanoscale magnetic spectroscopy. Existing methods of characterizing electron beams carrying orbital angular momentum are inefficient as they allow measuring one OAM state at a time. Here the authors demonstrate an OAM spectrometer capable of analysing multiple OAM states and a potential tool for probing magnetic materials.
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Affiliation(s)
- Vincenzo Grillo
- CNR-Istituto Nanoscienze, Centro S3, Via G Campi 213/a, I-41125 Modena, Italy.,CNR-IMEM Parco Area delle Scienze 37/A, I-43124 Parma, Italy
| | - Amir H Tavabi
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Federico Venturi
- CNR-Istituto Nanoscienze, Centro S3, Via G Campi 213/a, I-41125 Modena, Italy.,Dipartimento FIM Universitá di Modenae Reggio Emilia, Via G Campi 213/a, I-41125 Modena, Italy
| | - Hugo Larocque
- Department of Physics, University of Ottawa, 25 Templeton Street, Ottawa, Ontario, Canada K1N 6N5
| | | | - Gian Carlo Gazzadi
- CNR-Istituto Nanoscienze, Centro S3, Via G Campi 213/a, I-41125 Modena, Italy
| | - Stefano Frabboni
- CNR-Istituto Nanoscienze, Centro S3, Via G Campi 213/a, I-41125 Modena, Italy.,Dipartimento FIM Universitá di Modenae Reggio Emilia, Via G Campi 213/a, I-41125 Modena, Italy
| | - Peng-Han Lu
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Erfan Mafakheri
- Dipartimento FIM Universitá di Modenae Reggio Emilia, Via G Campi 213/a, I-41125 Modena, Italy
| | - Frédéric Bouchard
- Department of Physics, University of Ottawa, 25 Templeton Street, Ottawa, Ontario, Canada K1N 6N5
| | - Rafal E Dunin-Borkowski
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Robert W Boyd
- Department of Physics, University of Ottawa, 25 Templeton Street, Ottawa, Ontario, Canada K1N 6N5.,Institute of Optics, University of Rochester, Rochester, New York 14627, USA
| | - Martin P J Lavery
- School of Physics and Astronomy, Glasgow University, Glasgow, G12 8QQ Scotland, UK
| | - Miles J Padgett
- School of Physics and Astronomy, Glasgow University, Glasgow, G12 8QQ Scotland, UK
| | - Ebrahim Karimi
- Department of Physics, University of Ottawa, 25 Templeton Street, Ottawa, Ontario, Canada K1N 6N5.,Department of Physics, Institute for Advanced Studies in Basic Sciences, 45137-66731 Zanjan, Iran
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20
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Bouchard F, Fickler R, Boyd RW, Karimi E. High-dimensional quantum cloning and applications to quantum hacking. Sci Adv 2017; 3:e1601915. [PMID: 28168219 PMCID: PMC5291699 DOI: 10.1126/sciadv.1601915] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2016] [Accepted: 12/14/2016] [Indexed: 05/20/2023]
Abstract
Attempts at cloning a quantum system result in the introduction of imperfections in the state of the copies. This is a consequence of the no-cloning theorem, which is a fundamental law of quantum physics and the backbone of security for quantum communications. Although perfect copies are prohibited, a quantum state may be copied with maximal accuracy via various optimal cloning schemes. Optimal quantum cloning, which lies at the border of the physical limit imposed by the no-signaling theorem and the Heisenberg uncertainty principle, has been experimentally realized for low-dimensional photonic states. However, an increase in the dimensionality of quantum systems is greatly beneficial to quantum computation and communication protocols. Nonetheless, no experimental demonstration of optimal cloning machines has hitherto been shown for high-dimensional quantum systems. We perform optimal cloning of high-dimensional photonic states by means of the symmetrization method. We show the universality of our technique by conducting cloning of numerous arbitrary input states and fully characterize our cloning machine by performing quantum state tomography on cloned photons. In addition, a cloning attack on a Bennett and Brassard (BB84) quantum key distribution protocol is experimentally demonstrated to reveal the robustness of high-dimensional states in quantum cryptography.
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Affiliation(s)
- Frédéric Bouchard
- Department of Physics, University of Ottawa, 25 Templeton Street, Ottawa, Ontario K1N 6N5, Canada
| | - Robert Fickler
- Department of Physics, University of Ottawa, 25 Templeton Street, Ottawa, Ontario K1N 6N5, Canada
| | - Robert W. Boyd
- Department of Physics, University of Ottawa, 25 Templeton Street, Ottawa, Ontario K1N 6N5, Canada
- Institute of Optics, University of Rochester, Rochester, NY 14627, USA
| | - Ebrahim Karimi
- Department of Physics, University of Ottawa, 25 Templeton Street, Ottawa, Ontario K1N 6N5, Canada
- Department of Physics, Institute for Advanced Studies in Basic Sciences, 45137-66731 Zanjan, Iran
- Corresponding author.
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21
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Bouchard F, Larocque H, Yao AM, Travis C, De Leon I, Rubano A, Karimi E, Oppo GL, Boyd RW. Polarization Shaping for Control of Nonlinear Propagation. Phys Rev Lett 2016; 117:233903. [PMID: 27982639 DOI: 10.1103/physrevlett.117.233903] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Indexed: 05/28/2023]
Abstract
We study the nonlinear optical propagation of two different classes of light beams with space-varying polarization-radially symmetric vector beams and Poincaré beams with lemon and star topologies-in a rubidium vapor cell. Unlike Laguerre-Gauss and other types of beams that quickly experience instabilities, we observe that their propagation is not marked by beam breakup while still exhibiting traits such as nonlinear confinement and self-focusing. Our results suggest that, by tailoring the spatial structure of the polarization, the effects of nonlinear propagation can be effectively controlled. These findings provide a novel approach to transport high-power light beams in nonlinear media with controllable distortions to their spatial structure and polarization properties.
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Affiliation(s)
- Frédéric Bouchard
- The Max Planck Centre for Extreme and Quantum Photonics, Department of Physics, University of Ottawa, 25 Templeton, Ottawa, Ontario K1N 6N5, Canada
| | - Hugo Larocque
- The Max Planck Centre for Extreme and Quantum Photonics, Department of Physics, University of Ottawa, 25 Templeton, Ottawa, Ontario K1N 6N5, Canada
| | - Alison M Yao
- SUPA and Department of Physics, University of Strathclyde, 107 Rottenrow, Glasgow G4 0NG, Scotland, United Kingdom
| | - Christopher Travis
- SUPA and Department of Physics, University of Strathclyde, 107 Rottenrow, Glasgow G4 0NG, Scotland, United Kingdom
| | - Israel De Leon
- The Max Planck Centre for Extreme and Quantum Photonics, Department of Physics, University of Ottawa, 25 Templeton, Ottawa, Ontario K1N 6N5, Canada
- School of Engineering and Sciences, Tecnológico de Monterrey, Monterrey, Nuevo Leon 64849, Mexico
| | - Andrea Rubano
- Dipartimento di Fisica, Università di Napoli Federico II, Complesso Universitario di Monte Sant'Angelo, via Cintia, 80126 Napoli, Italy
| | - Ebrahim Karimi
- The Max Planck Centre for Extreme and Quantum Photonics, Department of Physics, University of Ottawa, 25 Templeton, Ottawa, Ontario K1N 6N5, Canada
- Department of Physics, Institute for Advanced Studies in Basic Sciences, 45137-66731 Zanjan, Iran
| | - Gian-Luca Oppo
- SUPA and Department of Physics, University of Strathclyde, 107 Rottenrow, Glasgow G4 0NG, Scotland, United Kingdom
| | - Robert W Boyd
- The Max Planck Centre for Extreme and Quantum Photonics, Department of Physics, University of Ottawa, 25 Templeton, Ottawa, Ontario K1N 6N5, Canada
- Institute of Optics, University of Rochester, Rochester, New York 14627, USA
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22
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Larocque H, Bouchard F, Grillo V, Sit A, Frabboni S, Dunin-Borkowski RE, Padgett MJ, Boyd RW, Karimi E. Nondestructive Measurement of Orbital Angular Momentum for an Electron Beam. Phys Rev Lett 2016; 117:154801. [PMID: 27768337 DOI: 10.1103/physrevlett.117.154801] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2016] [Indexed: 06/06/2023]
Abstract
Free electrons with a helical phase front, referred to as "twisted" electrons, possess an orbital angular momentum (OAM) and, hence, a quantized magnetic dipole moment along their propagation direction. This intrinsic magnetic moment can be used to probe material properties. Twisted electrons thus have numerous potential applications in materials science. Measuring this quantity often relies on a series of projective measurements that subsequently change the OAM carried by the electrons. In this Letter, we propose a nondestructive way of measuring an electron beam's OAM through the interaction of this associated magnetic dipole with a conductive loop. Such an interaction results in the generation of induced currents within the loop, which are found to be directly proportional to the electron's OAM value. Moreover, the electron experiences no OAM variations and only minimal energy losses upon the measurement, and, hence, the nondestructive nature of the proposed technique.
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Affiliation(s)
- Hugo Larocque
- The Max Planck Centre for Extreme and Quantum Photonics, Department of Physics, University of Ottawa, 25 Templeton Street, Ottawa, Ontario K1N 6N5, Canada
| | - Frédéric Bouchard
- The Max Planck Centre for Extreme and Quantum Photonics, Department of Physics, University of Ottawa, 25 Templeton Street, Ottawa, Ontario K1N 6N5, Canada
| | - Vincenzo Grillo
- CNR-Istituto Nanoscienze, Centro S3, Via G Campi 213/a, I-41125 Modena, Italy
| | - Alicia Sit
- The Max Planck Centre for Extreme and Quantum Photonics, Department of Physics, University of Ottawa, 25 Templeton Street, Ottawa, Ontario K1N 6N5, Canada
| | - Stefano Frabboni
- CNR-Istituto Nanoscienze, Centro S3, Via G Campi 213/a, I-41125 Modena, Italy
- Dipartimento FIM Universitá di Modenae Reggio Emilia, Via G Campi 213/a, I-41125 Modena, Italy
| | - Rafal E Dunin-Borkowski
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons, Forschungszentrum Jülich, Jülich 52425, Germany
| | - Miles J Padgett
- School of Physics and Astronomy, Glasgow University, Glasgow G12 8QQ, United Kingdom
| | - Robert W Boyd
- The Max Planck Centre for Extreme and Quantum Photonics, Department of Physics, University of Ottawa, 25 Templeton Street, Ottawa, Ontario K1N 6N5, Canada
- Institute of Optics, University of Rochester, Rochester, New York 14627, USA
| | - Ebrahim Karimi
- The Max Planck Centre for Extreme and Quantum Photonics, Department of Physics, University of Ottawa, 25 Templeton Street, Ottawa, Ontario K1N 6N5, Canada
- Department of Physics, Institute for Advanced Studies in Basic Sciences, 45137-66731 Zanjan, Iran
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23
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Jacques O, Bouchard F, MacDonald LA, Hall RI, Wolfe BB, Pienitz R. Distribution and diversity of diatom assemblages in surficial sediments of shallow lakes in Wapusk National Park (Manitoba, Canada) region of the Hudson Bay Lowlands. Ecol Evol 2016; 6:4526-40. [PMID: 27386094 PMCID: PMC4930999 DOI: 10.1002/ece3.2179] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Revised: 04/12/2016] [Accepted: 04/13/2016] [Indexed: 11/26/2022] Open
Abstract
The hydrology of shallow lakes (and ponds) located in the western Hudson Bay Lowlands (HBL) is sensitive to climate warming and associated permafrost thaw. However, their biological characteristics are poorly known, which hampers effective aquatic ecosystem monitoring. Located in northern Manitoba along the southwestern coast of Hudson Bay, Wapusk National Park (WNP) encompasses numerous shallow lakes representative of the subarctic zone. We analyzed the distribution and diversity of diatom (microscopic algae; class Bacillariophyceae) assemblages in surficial sediments of 33 lakes located in three different ecozones spanning a vegetation gradient, from NE to SW: the Coastal Fen (CF), the Interior Peat Plateau (IPP), and the Boreal Spruce Forest (BSF). We found significant differences (P < 0.05) in diatom community composition between CF and IPP lakes, and CF and BSF lakes, but not between IPP and BSF lakes. These results are consistent with water chemistry measurements, which indicated distinct limnological conditions for CF lakes. Diatom communities in CF lakes were generally dominated by alkaliphilous taxa typical of waters with medium to high conductivity, such as Nitzschia denticula. In contrast, several IPP and BSF lakes were dominated by acidophilous and circumneutral diatom taxa with preference for low conductivity (e.g., Tabellaria flocculosa, Eunotia mucophila, E. necompacta var. vixcompacta). This exploratory survey provides a first detailed inventory of the diatom assemblages in the WNP region needed for monitoring programs to detect changes in shallow lake ecosystems and ecozonal shifts in response to climate variations.
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Affiliation(s)
- Olivier Jacques
- Département de géographieUniversité LavalQuébec CityQCCanadaG1V 0A6
- Centre d'études nordiquesUniversité LavalQuébec CityQCCanadaG1V 0A6
| | - Frédéric Bouchard
- Département de géographieUniversité LavalQuébec CityQCCanadaG1V 0A6
- Centre d'études nordiquesUniversité LavalQuébec CityQCCanadaG1V 0A6
| | | | - Roland I. Hall
- Department of BiologyUniversity of WaterlooWaterlooONCanadaN2L 3G1
| | - Brent B. Wolfe
- Department of Geography and Environmental StudiesWilfrid Laurier UniversityWaterlooONCanadaN2L 3C5
| | - Reinhard Pienitz
- Département de géographieUniversité LavalQuébec CityQCCanadaG1V 0A6
- Centre d'études nordiquesUniversité LavalQuébec CityQCCanadaG1V 0A6
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24
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Ahangary AA, Bouchard F, Santamato E, Karimi E, Khalesifard HR. Dynamics of laser-induced radial birefringence in silver-doped glasses. Opt Lett 2015; 40:4062-4065. [PMID: 26368712 DOI: 10.1364/ol.40.004062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Silver ion-exchanged glass exhibits nonlinear optical properties upon interacting with intense light beams. The thermal effect due to the nanoparticles' light-absorption induces radial stress, and consequently, a radial birefringence on the glass surface. The induced birefringence possesses a topological charge of 1 in the transverse plane of the glass, i.e., cylindrical symmetry. Therefore, when the glass is illuminated with a circularly polarized light beam, a portion of the incoming beam flips its polarization handedness, since the plate is birefringent, and gains an orbital angular momentum of ±2 in units of the Planck constant. This is referred to as optical spin-to-orbital angular momentum conversion, and can be understood by means of the Pancharatnam-Berry phase. Here, we design a pump-probe setup to study and observe the dynamics of optical angular momentum coupling in real time. We show that this effect can be permanent or reversible, depending on the power and interaction time of the pump beam. In particular, an intrinsic power-dependent birefringence hysteresis is observed on the sample after interaction with and the relaxation of the irradiated point.
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25
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Choi BCK, Wigle DT, Johansen H, Losos J, Fair ME, Napke E, Anderson LJ, Davies JW, White K, Miller AB, Li FCK, Stachenko S, Lindsay J, Gaudette LA, Nair C, Levy I, Morrison H, Silins J, Bouchard F, Tonmyr L, Villeneuve PJ, McRae L, Johnson KC, Lane RS, Probert A. Status Report--Retracing the history of the early development of national chronic disease surveillance in Canada and the major role of the Laboratory Centre for Disease Control (LCDC) from 1972 to 2000. Health Promot Chronic Dis Prev Can 2015; 35:35-44. [PMID: 25915119 PMCID: PMC4910431 DOI: 10.24095/hpcdp.35.2.02] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Health surveillance is the ongoing, systematic
use of routinely collected health
data to guide public health action in a
timely fashion.
This paper describes the creation and
growth of national surveillance systems
in Canada and their impact on chronic
disease and injury prevention.
In 2008, the authors started a review process
to retrace the history of the early development
of national chronic disease surveillance
in Canada from 1960 to 2000. A 1967
publication describes the history of the
development of the Laboratory of Hygiene
from 1921 to 1967. This review is a sequel
to that paper and describes the history of the
development of national chronic disease
surveillance in Canada before and after the
formation of the Laboratory Centre for
Disease Control (LCDC).
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Affiliation(s)
- B C K Choi
- Public Health Agency of Canada, Ottawa, Ontario, Canada
- Health Canada, Ottawa, Ontario, Canada
| | - D T Wigle
- Health Canada, Ottawa, Ontario, Canada
| | - H Johansen
- Health Canada, Ottawa, Ontario, Canada
- Statistics Canada, Ottawa, Ontario, Canada
| | - J Losos
- Health Canada, Ottawa, Ontario, Canada
- University of Ottawa, Ottawa, Ontario, Canada
| | - M E Fair
- Statistics Canada, Ottawa, Ontario, Canada
| | - E Napke
- Health Canada, Ottawa, Ontario, Canada
| | - L J Anderson
- Health Canada, Ottawa, Ontario, Canada
- Health and Social Policy Editing Consultant, Ottawa, Ontario, Canada
| | - J W Davies
- Health Canada, Ottawa, Ontario, Canada
- University of Ottawa, Ottawa, Ontario, Canada
| | - K White
- Health Canada, Ottawa, Ontario, Canada
- Statistics Canada, Ottawa, Ontario, Canada
| | - A B Miller
- Dalla Lana School of Public Health, University of Toronto, Toronto, Ontario, Canada
| | - F C K Li
- Health Canada, Ottawa, Ontario, Canada
- Embassy of Canada, Beijing, China
| | - S Stachenko
- Public Health Agency of Canada, Ottawa, Ontario, Canada
- School of Public Health, University of Alberta, Edmonton, Alberta, Canada
| | - J Lindsay
- Health Canada, Ottawa, Ontario, Canada
- University of Ottawa, Ottawa, Ontario, Canada
| | - L A Gaudette
- Public Health Agency of Canada, Ottawa, Ontario, Canada
- Statistics Canada, Ottawa, Ontario, Canada
| | - C Nair
- Statistics Canada, Ottawa, Ontario, Canada
- Health Information Solutions, Ottawa, Ontario, Canada
| | - I Levy
- Health Canada, Ottawa, Ontario, Canada
- Ottawa Public Health, Ottawa, Ontario, Canada
| | - H Morrison
- Public Health Agency of Canada, Ottawa, Ontario, Canada
- Health Canada, Ottawa, Ontario, Canada
| | - J Silins
- Health Canada, Ottawa, Ontario, Canada
- Statistics Canada, Ottawa, Ontario, Canada
| | - F Bouchard
- Health Canada, Ottawa, Ontario, Canada
- Nunavik Regional Board of Health and Social Services, Kuujjuaq, Quebec, Canada
| | - L Tonmyr
- Public Health Agency of Canada, Ottawa, Ontario, Canada
- Health Canada, Ottawa, Ontario, Canada
| | - P J Villeneuve
- Health Canada, Ottawa, Ontario, Canada
- Carleton University, Ottawa, Ontario, Canada
| | - L McRae
- Public Health Agency of Canada, Ottawa, Ontario, Canada
- Health Canada, Ottawa, Ontario, Canada
| | - K C Johnson
- Public Health Agency of Canada, Ottawa, Ontario, Canada
- Health Canada, Ottawa, Ontario, Canada
| | - R S Lane
- Health Canada, Ottawa, Ontario, Canada
- Canadian Nuclear Safety Commission, Ottawa, Ontario, Canada
| | - A Probert
- Health Canada, Ottawa, Ontario, Canada
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Abstract
Some metagenomic studies have suggested that less than 10% of the cells that comprise our bodies are Homo sapiens cells. The remaining 90% are bacterial cells. The description of this so-called human microbiome is of great interest and importance for several reasons. For one, it helps us redefine what a biological individual is. We suggest that a human individual is now best described as a super-individual in which a large number of different species (including Homo sapiens) coexist. New concepts of biological individuality must extend beyond the traditional limitations of our own skin to include our resident microbes. Besides its important contributions to science, microbiome research raises philosophical questions that strike close to home. What is left of Homo sapiens? If most of our cells are not Homo sapiens cells, what does it mean to be an individual human being? In this paper, we argue that the biological individual is determined by the amount of functional integration among its constitutive parts, a definition that applies perfectly to Homo sapiens and its microbiome.
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Affiliation(s)
- Thiago Hutter
- />Département de philosophie, Université de Montréal, P. O. Box 6128, Station Centre-ville, Montréal, QC H3C 3J7 Canada
| | - Carine Gimbert
- />Département de sciences biologiques, Université de Montréal, P. O. Box 6128, Station Centre-ville, Montréal, QC H3C 3J7 Canada
- />Institut national des sciences appliquées de Lyon, 20 Avenue Albert Einstein, 69621 Villeurbanne CEDEX, France
| | - Frédéric Bouchard
- />Département de philosophie, Université de Montréal, P. O. Box 6128, Station Centre-ville, Montréal, QC H3C 3J7 Canada
| | - François-Joseph Lapointe
- />Département de sciences biologiques, Université de Montréal, P. O. Box 6128, Station Centre-ville, Montréal, QC H3C 3J7 Canada
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Bouchard F, Paquin J. Differential effects of retinoids and inhibitors of ERK and p38 signaling on adipogenic and myogenic differentiation of P19 stem cells. Stem Cells Dev 2013; 22:2003-16. [PMID: 23441952 DOI: 10.1089/scd.2012.0209] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
All-trans-retinoic acid (atRA) is an essential signaling molecule in embryonic development. It regulates cell differentiation by activating nuclear retinoic acid receptors (RAR) and retinoid-X receptors (RXR), which both control gene expression. In addition, atRA could act in the cytoplasm by modulating the activity of mitogen-activated protein kinases (MAPK) ERK and p38, which also have a role in cell differentiation. AtRA can induce the differentiation of P19 embryonic carcinoma stem cells into adipocytes, cardiomyocytes, and skeletal muscle cells, concurrently, in the same culture. We postulated that combinations of atRA, atRA analogs exhibiting selectivity for RAR or RXR, and inhibitors of ERK and p38 signaling (ERKi and p38i) could be used to favor one mesodermal fate over the others in the P19 model. In a first series of experiments, we replaced atRA by an agonist of RXR (LG100268) or RAR (TTNPB) to preferentially stimulate one group of receptors over the other. LG100268 was as adipogenic and myogenic as atRA, whereas TTNPB strongly induced adipogenesis, but not myogenesis. ERKi enhanced the myogenic action of atRA, and p38i increased both adipogenesis and myogenesis. In a second series of experiments, we combined atRA with an RAR or RXR antagonist (RARatg or RXRatg) to preferentially deactivate each receptor group in turn. The combinations atRA+RXRatg and atRA+RARatg, including or not ERKi, had similar mesodermal actions as atRA. In contrast, there was no myogenesis with atRA+RXRatg+p38i treatment, and there were no myogenesis and no adipogenesis with the atRA+RARatg+p38i combination. Overall, the results indicate that p38 has a role in mesodermal differentiation that depends on the retinoid context. Indeed, p38 in conjunction with RXR is important in myogenesis, and p38 and RAR in adipogenesis. Under the conditions tested, it was possible to stimulate adipogenesis with a block on myogenesis, whereas increased myogenesis was accompanied by adipogenesis.
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Affiliation(s)
- Frédéric Bouchard
- Département de chimie-biochimie and Centre BioMed, Université du Québec à Montréal, Montreal, Quebec, Canada
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Abstract
Ever since Darwin, the familiar genealogical pattern known as the Tree of Life (TOL) has been prominent in evolutionary thinking and has dominated not only systematics, but also the analysis of the units of evolution. However, recent findings indicate that the evolution of DNA, especially in prokaryotes and such DNA vehicles as viruses and plasmids, does not follow a unique tree-like pattern. Because evolutionary patterns track a greater range of processes than those captured in genealogies, genealogical patterns are in fact only a subset of a broader set of evolutionary patterns. This fact suggests that evolutionists who focus exclusively on genealogical patterns are blocked from providing a significant range of genuine evolutionary explanations. Consequently, we highlight challenges to tree-based approaches, and point the way toward more appropriate methods to study evolution (although we do not present them in technical detail). We argue that there is significant benefit in adopting wider range of models, evolutionary representations, and evolutionary explanations, based on an analysis of the full range of evolutionary processes. We introduce an ecosystem orientation into evolutionary thinking that highlights the importance of "type 1 coalitions" (functionally related units with genetic exchanges, aka "friends with genetic benefits"), "type 2 coalitions" (functionally related units without genetic exchanges), "communal interactions," and "emergent evolutionary properties." On this basis, we seek to promote the study of (especially prokaryotic) evolution with dynamic evolutionary networks, which are less constrained than the TOL, and to provide new ways to analyze an expanded range of evolutionary units (genetic modules, recombined genes, plasmids, phages and prokaryotic genomes, pangenomes, microbial communities) and evolutionary processes. Finally, we discuss some of the conceptual and practical questions raised by such network-based representation.
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Bouchard F, Francus P, Pienitz R, Laurion I. Sedimentology and geochemistry of thermokarst ponds in discontinuous permafrost, subarctic Quebec, Canada. ACTA ACUST UNITED AC 2011. [DOI: 10.1029/2011jg001675] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Séguin G, Bouchard F, Measures LN, Uhland CF, Lair S. Infections with Philometra sp. associated with mortalities in wild-hatched captive-raised striped bass, Morone saxatilis (Walbaum). J Fish Dis 2011; 34:475-481. [PMID: 21545441 DOI: 10.1111/j.1365-2761.2011.01258.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The striped bass, Morone saxatilis (Walbaum), once represented an important resource for fisheries in the St Lawrence River (Quebec, Canada). A restoration programme, involving captive propagation, was implemented with the objective of restocking the population, which had disappeared in the late 1960s. An unusually high rate of mortality was observed during the winter of 2006 in captive-raised fingerlings that were originally collected from the Miramichi River (New Brunswick, Canada) the previous summer. Post-mortem examinations revealed extensive granulomatous and hyperplastic peritonitis associated with numerous nematodes of the genus Philometra. Given the severity of the lesions, high intensity of infection by Philometra sp. was presumed to be the primary factor in the unusual mortalities reported that winter. Observations suggest that this nematode, which was acquired in the wild, cannot establish itself in a captive environment, most likely because of the absence of the obligate intermediate host. Examination of archived specimens of striped bass showed that this parasite was probably present in the St Lawrence River population prior to its extirpation. Consequently, the introduction of infected fish into this ecosystem should not be a concern. Nevertheless, infection-related mortalities of fingerlings might affect dynamics of wild striped bass populations.
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Affiliation(s)
- G Séguin
- Centre Québécois sur la Santé des Animaux Sauvages-Canadian Cooperative Wildlife Health Centre, Université de Montréal, St Hyacinthe, QC, Canada
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Abstract
Following Wallace's suggestion, Darwin framed his theory using Spencer's expression "survival of the fittest". Since then, fitness occupies a significant place in the conventional understanding of Darwinism, even though the explicit meaning of the term 'fitness' is rarely stated. In this paper I examine some of the different roles that fitness has played in the development of the theory. Whereas the meaning of fitness was originally understood in ecological terms, it took a statistical turn in terms of reproductive success throughout the 20th Century. This has lead to the ever-increasing importance of sexually reproducing organisms and the populations they compose in evolutionary explanations. I will argue that, moving forward, evolutionary theory should look back at its ecological roots in order to be more inclusive in the type of systems it examines. Many biological systems (e.g. clonal species, colonial species, multi-species communities) can only be satisfactorily accounted for by offering a non-reproductive account of fitness. This argument will be made by examining biological systems with very small or transient population structures. I argue this has significant consequences for how we define Darwinism, increasing the significance of survival (or persistence) over that of reproduction.
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Affiliation(s)
- Frédéric Bouchard
- Département de Philosophie, Université de Montréal, Centre Interuniversitaire de Recherche sur la Science et la Technologie, Canada.
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Liow LH, Simpson C, Bouchard F, Damuth J, Hallgrimsson B, Hunt G, McShea DW, Powell JR, Stenseth NC, Stoller MK, Wagner G. Pioneering paradigms and magnificent manifestos--Leigh Van Valen's priceless contributions to evolutionary biology. Evolution 2011; 65:917-22. [PMID: 21463292 DOI: 10.1111/j.1558-5646.2011.01242.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Lee Hsiang Liow
- Center for Ecological and Evolutionary Synthesis (CEES), Department of Biology, University of Oslo, Oslo, Norway.
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Abstract
P19 embryonic carcinoma cells resemble normal embryonic stem (ES) cells. They generate cardiac and skeletal myocytes in response to retinoic acid (RA) or oxytocin (OT). RA treatment followed by exposure to triiodothyronine (T3) and insulin induces ES cells differentiation into adipocytes and skeletomyocytes. On the other hand, OT (10(-7) M) was reported to inhibit 3T3 preadipocyte maturation. The present work was undertaken to determine whether P19 cells have an adipogenic potential that could be affected by OT. Cells were treated with RA (10(-6) M)/T3+insulin (adipogenic protocol) or 10(-7) M OT (cardiomyogenic protocol), and analyzed by polymerase chain reaction, immunotechniques, and cytochemistry. Oil-Red-O staining and expression of peroxisome proliferator-activated receptor-gamma (PPARgamma) and aP2 indicated the generation of adipocytes in cultures submitted to the adipogenic protocol. Contracting cells were also generated. Cells positive for sarcomeric actinin and negative for cardiac troponin inhibitor (cTpnI) indicated generation of skeletomyocytes, and cTpnI positive cells revealed generation of cardiomyocytes. Levels of cTpnI and of the skeletal marker MyoD were almost similar in both protocols, whereas no Oil-Red-O staining was associated with the cardiomyogenic protocol. Addition of 10(-7) M OT to the adipogenic protocol did not affect Oil-Red-O staining and PPARgamma expression. Interestingly, Oct3/4 pluripotency marker disappeared in the adipogenic protocol but remained expressed in the cardiomyogenic one. P19 cells thus have an adipogenic potential non affected by 10(-7) M OT. RA/T3+insulin combination generates a larger spectrum of mesodermal cell derivatives and is a more potent morphogenic treatment than OT. P19 cells could help investigating mechanisms of cell fate decision during development.
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Affiliation(s)
- Frédéric Bouchard
- Département de Chimie-Biochimie and Centre BioMed, Université du Québec à Montréal, Montréal, Québec H3C 3P8, Canada
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St-Pierre Y, Biron-Pain K, Campion C, Lavoie G, Bouchard F, Couillard J. Potential directions for drug development against galectin-7 in cancer. Expert Opin Drug Discov 2009; 4:611-20. [DOI: 10.1517/17460440902926399] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Bouchard F, Hepburn JW, McMahon TB. Pulsed-laser-ionization high-pressure mass spectrometry: a new route to gas-phase metal ion-ligand thermochemistry. J Am Chem Soc 2002. [DOI: 10.1021/ja00206a035] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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38
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Houlihan FM, Bouchard F, Frechet JMJ, Willson CG. Thermally depolymerizable polycarbonates. 2. Synthesis of novel linear tertiary copolycarbonates by phase-transfer catalysis. Macromolecules 2002. [DOI: 10.1021/ma00155a003] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Klabunde C, Bouchard F, Taplin S, Scharpantgen A, Ballard-Barbash R. Quality assurance for screening mammography: an international comparison. J Epidemiol Community Health 2001; 55:204-12. [PMID: 11160176 PMCID: PMC1731857 DOI: 10.1136/jech.55.3.204] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
STUDY OBJECTIVE In 1998, the International Breast Cancer Screening Network (IBSN) sponsored an assessment of quality assurance policies and practices to define their scope for population-based screening mammography programmes across IBSN countries. DESIGN Analysis of data from a survey designed to assess multiple elements of screening programme quality assurance, including organisation of quality assurance activities, mechanisms for site visits and accreditation, requirements for quality control and data systems, and inclusion of treatment, follow up, and programme evaluation in screening mammography quality assurance activities. PARTICIPANTS AND SETTING IBSN representatives in 23 countries completed a comprehensive questionnaire between May and December 1998. MAIN RESULTS Completed questionnaires were obtained from all 23 countries. Responses indicated that countries vary in their approaches to implementing quality assurance, although all monitor components of structure, process, and outcome. Nearly all have in place laws, surveillance mechanisms, or standards for quality assurance. In all countries, quality assurance activities extend beyond the screening mammography examination. CONCLUSIONS The assessment has enhanced understanding of the organisation of screening mammography programmes across countries, as well as the comparability of screening mammography data. All countries have established mechanisms for assuring the quality of screening mammography in population-based programmes, although these mechanisms vary across countries.
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Affiliation(s)
- C Klabunde
- National Cancer Institute (NCI), Bethesda 20892-7344, USA.
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Paquette D, Snider J, Bouchard F, Olivotto I, Bryant H, Decker K, Doyle G. Performance of screening mammography in organized programs in Canada in 1996. The Database Management Subcommittee to the National Committee for the Canadian Breast Cancer Screening Initiative. CMAJ 2000; 163:1133-8. [PMID: 11079057 PMCID: PMC80245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023] Open
Abstract
BACKGROUND The results of randomized trials show that breast cancer screening by mammography reduces breast cancer mortality by up to 40% in women aged 50-69 years. Because of these results, by 1998, 22 countries, including Canada, had established population-based organized screening programs. This paper presents the results of screening mammography in 1996 for 7 provincially organized breast cancer screening programs in Canada. METHODS Analyses of interim performance indicators for screening mammography have been calculated from data submitted to the Canadian Breast Cancer Screening database. The data set consisted of data from 7 provincial programs and was limited to mammographic screens for women aged 50-69 years (n = 203,303). Screening outcomes and performance indicators were calculated for abnormalities detected by screening mammography only. RESULTS The abnormal recall rate was 9.5% for first screens and 4.6% for subsequent screens, and the cancer detection rate per 1000 women screened was 6.9 for first screens and 3.8 for subsequent screens. The positive predictive value (i.e., the proportion of women who tested positive by mammography who were found to have breast cancer on screen-initiated diagnostic work-up) increased from 7.2% at the first screen to 8.2% at subsequent screens. Estimated participation rates within organized programs varied from 10.6% to 54.2%, depending on the province. INTERPRETATION For 1996, organized breast cancer screening programs met or exceeded many of the interim measures used in international programs. It is possible to translate the benefits of breast cancer screening by mammography, as demonstrated in randomized trials, into population-based community programs. Screening mammography through organized programs should increase to allow more comprehensive monitoring in Canada.
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Affiliation(s)
- D Paquette
- Centre for Chronic Disease Prevention and Control (Formerly the Laboratory Centre for Disease Control), Health Canada, Ottawa, Ont
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Arvieux C, Létoublon C, Bouchard F, Pasquier D, Delecour T, Barnoud D, Penillon S, Barnoud R, Sturm JM, Hodaj H, Borel E, Naud G, Pirenne J, Zarski JP. [Liver transplantation with a graft taken from a heart transplant patient who was brain-dead]. Ann Chir 2000; 125:376-9. [PMID: 10900741 DOI: 10.1016/s0003-3944(00)00210-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The shortage of organ donors has led to progressive softening of selection criteria for organ donation. We report on hepatic transplantation in a 55-year-old woman with primary biliary cirrhosis, whose donor was a 50-year-old heart transplant recipient who became brain stem dead, due to cerebral bleeding 8 months after transplantation. An orthotopic liver transplantation was performed. The postoperative course was uneventful and the recipient was alive and had normal liver function after a 42-month follow-up. Analysis of the literature included ethical consideration, potential hepatotoxic effects of immunosuppressive drugs and modification of the graft immunogenicity. It confirms that transplanted patients should not be a priori excluded from organ donation.
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Affiliation(s)
- C Arvieux
- Service de chirurgie générale et digestive, Grenoble, France
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Galland S, Le Borgne F, Bouchard F, Georges B, Clouet P, Grand-Jean F, Demarquoy J. Molecular cloning and characterization of the cDNA encoding the rat liver gamma-butyrobetaine hydroxylase. Biochim Biophys Acta 1999; 1441:85-92. [PMID: 10526231 DOI: 10.1016/s1388-1981(99)00135-3] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Carnitine biosynthesis from lysine and methionine involves five enzymatic reactions. gamma-butyrobetaine hydroxylase (BBH; EC 1.14. 11.1) is the last enzyme of this pathway. It catalyzes the reaction of hydroxylation of gamma-butyrobetaine to carnitine. The cDNA encoding this enzyme has been isolated and characterized. The cDNA contained an open reading frame of 1161 bp encoding a protein of 387 amino acids with a deduced molecular weight of 44.5 kDa. The sequence of the cDNA showed an important homology with the human cDNA recently isolated. Northern analysis showed gamma-butyrobetaine hydroxylase expression in the liver and in some extend in the testis and the epididymis. During this study, it also appeared that BBH mRNA expression was undetectable by Northern analysis during the perinatal period. During the development of the rat, the amount of BBH mRNA appeared after the weaning of the young rat and reached a maximal expression at the adult stage.
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Affiliation(s)
- S Galland
- Université de Bourgogne, Unité de Recherche en Nutrition Cellulaire et Métabolique, BP47870, F-21078, Dijon, France
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Ballard-Barbash R, Klabunde C, Paci E, Broeders M, Coleman EA, Fracheboud J, Bouchard F, Rennert G, Shapiro S. Breast cancer screening in 21 countries: delivery of services, notification of results and outcomes ascertainment. Eur J Cancer Prev 1999; 8:417-26. [PMID: 10548397 DOI: 10.1097/00008469-199910000-00007] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Following clinical trial evidence of mammography screening's efficacy and effectiveness, data are needed from organized population-based programmes to determine whether screening in these programmes results in breast cancer mortality reductions comparable to those demonstrated in controlled settings. The International Breast Cancer Screening Network (IBSN) conducted two international programme assessments: in 1990 among nine countries and in 1995 among 22 countries, obtaining information on the organization and process for screening within breast cancer screening programmes. This manuscript describes procedures for recruitment, service delivery, interpretation and communication of results, case ascertainment, and quality assurance. Practices in more established programmes are compared with pilot programmes. Each IBSN country defined a unique programme of population-based breast cancer screening. Some programmes were sub-national rather than national in scope, while others were in pilot stages of development. Screening took place in dedicated centres in established programmes and in both dedicated and general radiology centres in pilot programmes. Although most countries used personal invitation systems to recruit women to screening, other recruitment mechanisms were used. Most countries used two-view mammography in their screening programmes. About half had implemented independent double reading of mammograms, considering it a key component of high-quality mammography screening. In conclusion, diversity exists in the organization and delivery of screening mammography internationally. Quality assurance activities are a priority and are being evaluated in the IBSN.
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Arvieux-Barthelemy C, Mestrallet JP, Bouchard F, Delannoy P, Radmanesh O, Zattara A, Naud G, Faucheron JL, Eymard P, Dupré A, Létoublon C. [Surgical treatment of acute cholecystitis. A retrospective study of a series of 192 patients operated on over a period of 3 years]. Ann Chir 1999; 53:472-81. [PMID: 10427838] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/13/2023]
Abstract
Emergency conditions make laparoscopic treatment of acute cholecystitis challenging. The aim of this study is to retrospectively analyse our experience of cholecystectomy for acute cholecystitis performed between January 1995 and December 1997. In order to be included, patients had to present (i) symptoms of acute cholecystitis correlated with laboratory blood tests and ultrasonographic studies (ii) evidence of acute inflammation during the operation and (iii) histological confirmation of acute or subacute inflammation of the excised gallbladder. 192 patients were treated: 62 were totally managed laparoscopically (group CCN), 33 managed laparoscopically but required conversion to open cholecystectomy (group CCC) and 97 were managed conventionally by laparotomy (group CL). Mean age was significantly different between the three groups, (CCN: 55.6 +/- 15 years, CCC: 64.2 +/- 13 years, CL: 66.5 +/- 17 years), as was ASA score (CCN: ASA 3 and ASA 4: 16%, CCC: ASA 3 and ASA 4: 48%, CL: ASA 3 and ASA 4: 46%), and initial infectious signs (temp. > or = 38 degrees C: CCN: 35%, CCC: 39%, CL: 63%). Mean operative delay was significantly higher in the converted group [8.7 +/- 13 days (CCC) vs 4.5 +/- 8 days (CCN) and 5.4 +/- 8 days (CL)]. There were two (1%) bile duct injuries, one in the CCC group, the other in the CL group. Operative mortality was 2% (CCC: 0%, CCN: 0%, CL: 4%) and operative morbidity was 40% (CCN: 21%, CCC: 24%, CL: 57%). The mean postoperative hospital stay was shorter in the CCN group (6.5 +/- 3.5 days) and CCC group (9.6 +/- 4.4 days) vs the mean stay in the CL group (14.7 +/- 11.6 days). Appears to be beneficial for selected patients with low surgical risk to conclude laparoscopic cholecystectomy. It has yet to be shown whether this benefit can be extended to patients with a high surgical risk.
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Affiliation(s)
- C Arvieux-Barthelemy
- Service de Chirurgie Générale et Digestive, Centre Hospitalier Universitaire A.-Michallon, Grenoble.
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Dubar A, Beregi JP, Bouchard F, Warembourg H. [Long-term outcome of a false lumen after surgical correction of type A acute aortic dissection]. Arch Mal Coeur Vaiss 1998; 91:39-44. [PMID: 9749262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The long-term outcome (64.3 +/- 45 months) of 44 patients operated for acute dissection of at least the ascending aorta was assessed by regular clinical examination and annual CT scan. The diameter of the aorta at different levels was measured at each CT scan for all patients. Initially, 7 patients (16%) had acute dissection limited to the ascending aorta; none had a false lumen after surgery. No signs of aneurysmal dilatation were observed during follow-up of these patients. In the 37 other cases (84%) dissection of the aorta extended beyond the innominate artery; the false lumen remained patent distal to the prosthetic tube replacing the ascending aorta in 34 patients (92%). The false lumen was partially thrombosed in 8% of patients, leading to distal emboli in 1 patient. Moderate increases (less than 15 mm) in diameter of the false lumen were observed in 32% of patients; more severe dilatation (over 20 mm) was observed in 12% of patients. The management of dilatation of the false lumen is not standard; it depends mainly on the rate of progression and the clinical consequences. It is hoped that extension of the initial repair to the aortic arch, when the intimal tear is situated in this zone, will reduce the short and long-term progression of the false lumen.
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Affiliation(s)
- A Dubar
- Service de chirurgie cardiovasculaire B, Lille
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Larher F, Aziz A, Deleu C, Lemesle P, Ghaffar A, Bouchard F, Plasman M. Suppression of the osmoinduced proline response of rapeseed leaf discs by polyamines. Physiol Plant 1998; 102:139-147. [PMID: 35359121 DOI: 10.1034/j.1399-3054.1998.1020118.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Rapeseed leaf discs (RLD) subjected to upshock osmotic stress accumulate proline (Pro). Di- and polyamines (PA) supplied to the external medium suppressed Pro accumulation. These effects were dependent not only on diamine and PA concentrations but also on their cationic charge. The suppression of Pro accumulation required that diamine and PA be taken up and further accumulated in the leaf tissues. Glycine betaine (GB) also inhibited Pro accumulation, with the effects of GB and PA being additive. Experiments to elucidate the mechanism(s) responsible for the inhibitory effect of spermine (Spm) indicated that it could be simulated with methionine sulfoximine (MSO), a potent inhibitor of glutamine synthetase. The inhibitory effects of Spm and MSO were both alleviated by supplying glutamine to the RLD. In addition, Spm as well as MSO increased glutamate content, indicating that these compounds could inhibit the conversion of glutamate to proline. A comparison of the changes in chlorophyll and protein content of RLD osmotreated with or without added Spm indicates that this PA behaves as an antisenescent compound, preventing chlorophyll breakdown and proteolysis and hence the conversion of amino acids to Pro. Since the PA concentrations used in this work were much higher than the endogenous concentrations in RLD, the significance of PA under osmotic stress remains unclear. This study shows, however, that PA can suppress Pro accumulation.
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Affiliation(s)
- F Larher
- F. Larher (corresponding author, e-mail ) et al., Groupe de Biologie Végétale, UMR CNRS 6553, UFR S.V.E., Univ. de Rennes I, Campus de Beaulieu, F-35042 Rennes Cedex, France
| | - A Aziz
- F. Larher (corresponding author, e-mail ) et al., Groupe de Biologie Végétale, UMR CNRS 6553, UFR S.V.E., Univ. de Rennes I, Campus de Beaulieu, F-35042 Rennes Cedex, France
| | - C Deleu
- F. Larher (corresponding author, e-mail ) et al., Groupe de Biologie Végétale, UMR CNRS 6553, UFR S.V.E., Univ. de Rennes I, Campus de Beaulieu, F-35042 Rennes Cedex, France
| | - P Lemesle
- F. Larher (corresponding author, e-mail ) et al., Groupe de Biologie Végétale, UMR CNRS 6553, UFR S.V.E., Univ. de Rennes I, Campus de Beaulieu, F-35042 Rennes Cedex, France
| | - A Ghaffar
- F. Larher (corresponding author, e-mail ) et al., Groupe de Biologie Végétale, UMR CNRS 6553, UFR S.V.E., Univ. de Rennes I, Campus de Beaulieu, F-35042 Rennes Cedex, France
| | - F Bouchard
- F. Larher (corresponding author, e-mail ) et al., Groupe de Biologie Végétale, UMR CNRS 6553, UFR S.V.E., Univ. de Rennes I, Campus de Beaulieu, F-35042 Rennes Cedex, France
| | - M Plasman
- F. Larher (corresponding author, e-mail ) et al., Groupe de Biologie Végétale, UMR CNRS 6553, UFR S.V.E., Univ. de Rennes I, Campus de Beaulieu, F-35042 Rennes Cedex, France
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De Brabander J, Chateau N, Bouchard F, Guidollet S. Contrast sensitivity with soft contact lenses compensated for spherical aberration in high ametropia. Optom Vis Sci 1998; 75:37-43. [PMID: 9460785 DOI: 10.1097/00006324-199801000-00023] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND In optical systems, it is usual to compensate for longitudinal spherical aberration. In order to increase image quality, lens surfaces can be made aspheric to bring all object light rays into focus at the image plane. Theoretically, soft contact lenses with high power and spherical surfaces show significant amounts of spherical aberration. The use of spherical aberration-free soft contact lenses could therefore improve retinal image quality in the case of high ametropia. However, because of ocular aberration, accommodation effects, pupil dynamics, contact lens flexure, and positioning, the computation of the spherical aberration induced when a contact lens is placed on the eye is complicated. METHODS In this study, the spatial contrast sensitivity (CS) of 61 high ametropes wearing soft contact lenses with, and without, in-air spherical aberration compensation is measured. RESULTS A slightly better overall performance was found with the standard lenses. There was no significant influence by the type of ametropia, age, and gender. If individual results are considered, clinically significant differences between the two lens groups are observed in approximately 30% of the cases. CONCLUSIONS It seems that correcting in-air soft contact lens spherical aberration systematically is of no clinical interest. However, selective manipulation of spherical aberration could, in high power soft contact lenses, significantly improve CS in individuals.
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Affiliation(s)
- J De Brabander
- Department of Ophthalmology, Maastricht University, The Netherlands.
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Koning R, Cribier A, Eltchaninoff H, Tron C, Derumeaux G, Bouchard F, Soyer R, Letac B. [Primary treatment of left coronary artery diseases by percutaneous implantation of stents]. Arch Mal Coeur Vaiss 1997; 90:1307-12. [PMID: 9488778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Left main coronary artery (LM) stenting has only been reported in bail-out situations or absolute contraindications so surgery. The authors report the immediate and midterm results of primary Palmaz-Schatz stent implantation in two young patients without contraindication to surgery. The first patient, 58 year-old, was admitted for unstable angina in October 1994. Coronary angiography showed an isolated severe ostial lesion of the LM. After conferring with the surgical team which remained on stand-by, angioplasty and stent implantation were performed with excellent results, no complications and no restenosis on angiographic controls at 3 and 12 months. The patient remained asymptomatic 24 months later. The second patient, 38 year-old, was admitted in June 1995 for unstable angina, and coronary angiography showed a severe isolated stenosis in the middle of a long and wide LM. Primary coronary stenting was also performed with excellent results, no complication and no restenosis on angiographic controls at 4 and 8 months. This patient was still asymptomatic 16 months after stenting. These excellent immediate and medium-term results are encouraging and suggest that this form of treatment might be extended to patients with an isolated whether primary LM stent implantation could become a suitable alternative to surgery in the future.
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Affiliation(s)
- R Koning
- Service de cardiologie, hôpital Charles Nicolle, université de Rouen
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Bouchard F, Brenner V, Carra C, Hepburn JW, Koyanagi GK, McMahon TB, Ohanessian G, Peschke M. Energetics and Structure of Complexes of Al+ with Small Organic Molecules in the Gas Phase. J Phys Chem A 1997. [DOI: 10.1021/jp9703465] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- F. Bouchard
- Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1, Département de Chimie, Laboratoire des Méchanismes Réactionnels (URA 1307 CNRS), Ecole Polytechnique, 91128 Palaiseau Cedex, France, Institute de Chimie Physique, Universite de Fribourg, Perolles, Fribourg CH-1700, Switzerland, and Laboratoire de Chimie Theorique, DSM/DRECAM/SPAM, CE-CEA Saclay, 91191 Gif-sur-Yvette, France
| | - V. Brenner
- Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1, Département de Chimie, Laboratoire des Méchanismes Réactionnels (URA 1307 CNRS), Ecole Polytechnique, 91128 Palaiseau Cedex, France, Institute de Chimie Physique, Universite de Fribourg, Perolles, Fribourg CH-1700, Switzerland, and Laboratoire de Chimie Theorique, DSM/DRECAM/SPAM, CE-CEA Saclay, 91191 Gif-sur-Yvette, France
| | - C. Carra
- Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1, Département de Chimie, Laboratoire des Méchanismes Réactionnels (URA 1307 CNRS), Ecole Polytechnique, 91128 Palaiseau Cedex, France, Institute de Chimie Physique, Universite de Fribourg, Perolles, Fribourg CH-1700, Switzerland, and Laboratoire de Chimie Theorique, DSM/DRECAM/SPAM, CE-CEA Saclay, 91191 Gif-sur-Yvette, France
| | - J. W. Hepburn
- Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1, Département de Chimie, Laboratoire des Méchanismes Réactionnels (URA 1307 CNRS), Ecole Polytechnique, 91128 Palaiseau Cedex, France, Institute de Chimie Physique, Universite de Fribourg, Perolles, Fribourg CH-1700, Switzerland, and Laboratoire de Chimie Theorique, DSM/DRECAM/SPAM, CE-CEA Saclay, 91191 Gif-sur-Yvette, France
| | - G. K. Koyanagi
- Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1, Département de Chimie, Laboratoire des Méchanismes Réactionnels (URA 1307 CNRS), Ecole Polytechnique, 91128 Palaiseau Cedex, France, Institute de Chimie Physique, Universite de Fribourg, Perolles, Fribourg CH-1700, Switzerland, and Laboratoire de Chimie Theorique, DSM/DRECAM/SPAM, CE-CEA Saclay, 91191 Gif-sur-Yvette, France
| | - T. B. McMahon
- Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1, Département de Chimie, Laboratoire des Méchanismes Réactionnels (URA 1307 CNRS), Ecole Polytechnique, 91128 Palaiseau Cedex, France, Institute de Chimie Physique, Universite de Fribourg, Perolles, Fribourg CH-1700, Switzerland, and Laboratoire de Chimie Theorique, DSM/DRECAM/SPAM, CE-CEA Saclay, 91191 Gif-sur-Yvette, France
| | - G. Ohanessian
- Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1, Département de Chimie, Laboratoire des Méchanismes Réactionnels (URA 1307 CNRS), Ecole Polytechnique, 91128 Palaiseau Cedex, France, Institute de Chimie Physique, Universite de Fribourg, Perolles, Fribourg CH-1700, Switzerland, and Laboratoire de Chimie Theorique, DSM/DRECAM/SPAM, CE-CEA Saclay, 91191 Gif-sur-Yvette, France
| | - M. Peschke
- Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada N2L 3G1, Département de Chimie, Laboratoire des Méchanismes Réactionnels (URA 1307 CNRS), Ecole Polytechnique, 91128 Palaiseau Cedex, France, Institute de Chimie Physique, Universite de Fribourg, Perolles, Fribourg CH-1700, Switzerland, and Laboratoire de Chimie Theorique, DSM/DRECAM/SPAM, CE-CEA Saclay, 91191 Gif-sur-Yvette, France
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Abstract
The influence of pupil size, lens centration, and translation on multifocal contact lens performance suggests that these parameters should be accounted for in the optical design of presbyopic contact lenses. The purpose of the present article is to complete the existing experimental data with clinical measurements of pupil diameter and lens position relative to the pupil in a group of presbyopes, with controlled target luminance, stimulus distance, gaze angle, and convergence. The experiments involve an infrared video-pupillometer and ring-marked contact lenses. Results on pupil aperture show that the effect of changing target distance is comparable in magnitude to that of varying luminance within the photopic range. The measured data on lens position confirm that soft contact lenses are generally decentered from the pupillary axis, usually in inferior temporal direction, and that their average translation between primary and downward gaze is very small. It is also found that the average relative position between lens and pupil centers is slightly modified by changes of luminance in far vision. All these results provide characteristic values which are helpful for the optical modelling of presbyopic contact lenses.
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Affiliation(s)
- N Chateau
- Research and Development Center-Essilor Optique de Contact, Crétell, France
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