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October 2012 - August 2013
IMNC Lab
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- PostDoc Position
Publications
Publications (119)
RESUME: La crise de la COVID-19 a conduit à des ruptures importantes des existences humaines. La méthodologie a été adaptée des recherches menées suite à l'accident nucléaire de Tchernobyl en 1986. Une analogie fondée sur l'invisibilité entre les contaminations radioactives par le césium 137 et les contaminations virales par SARS-CoV-2 souligne que...
In multi-photon microscopy (MPM), a recent in-vivo fluorescence microscopy system, the task of image restoration can be decomposed into two interlinked inverse problems: firstly, the characterization of the point spread function (PSF) and subsequently, the deconvolution (i.e. deblurring) to remove the PSF effect, and reduce noise. The acquired MPM...
We demonstrate how a narrowband pump and a broadband spectrum can be spatially multiplexed by selective coupling them in two distinct modes of a few-mode microstructure fiber. The first mode carries most of the input pump energy, and experiences spectral broadening. Whereas the second mode preserves the narrow bandwidth of the remaining part of the...
We demonstrate how a narrowband pump and a broadband spectrum can be spatially multiplexed by selective coupling them in two distinct modes of a few-mode microstructure fiber. The first mode carries most of the input pump energy, and experiences spectral broadening. Whereas the second mode preserves the narrow bandwidth of the remaining part of the...
According to the latest The Global Risks Report (2022) of World Economic Forum, the large-scale coronavirus disease 2019 (COVID-19) threat creates various tensions that might lead to unexpected cascading impacts in various domains. Nevertheless, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus, about 120 nm in diameter, remain...
In this work, we propose an asynchronous Majorization-Minimization (MM) algorithm for solving large scale differentiable non-convex optimization problems. The proposed algorithm runs efficient MM memory gradient updates on blocks of coordinates, in a parallel and possibly asynchronous manner. We establish the convergence of the resulting sequence o...
Current solutions for bacteria and viruses identification are based on time‐consuming technics with complex preparation procedures. In the present work, we revealed label‐free the presence of free viral particles and bacteria with a computational two‐photon fluorescence (C‐TPF) strategy. Six bacteria were tested: Escherichia coli, Staphylococcus ep...
La compréhension des modes d’actions biologiques des virus dans une cellule hôte est un sujet complexe pour lequel nous pensons que les solutions optiques pourraient apporter des éléments de réponse nouveaux. Cependant, les dimensions des particules virales sont environ 3 fois plus petites que la résolution d’un microscope optique. Nous proposons d...
Viruses are unseen enemies which tend to disarmingly spread from person-to-person, therefore causing health damages and weakens the immunity system. Their invisibility give rise to various representations, projections and imaginations that allow laypeople to tame the unseen and intangible nature of viruses. For the first time to our knowledge, we a...
RESUME: La pandémie sanitaire de COVID-19, suscité par l'invisible virus SARS-CoV-2, représente une situation aversive pour les personnes et la société. Cette situation extrême qui se caractérise principalement par la nouveauté, l'incertitude et l'ambiguïté conduit à un effondrement symbolique de la réalité auquel les personnes et la société doiven...
La complexité de la pandémie de COVID-19 révèle d’importants débats méthodologiques et des défis quant à l’articulation de différentes approches de recherche. La recherche sociétale actuelle concernant la COVID-19 met en évidence la nécessité d'une étude holistique de la situation de la pandémie de COVID-19, fondée sur une approche de recherche mul...
Nous présentons une nouvelle stratégie instrumentale et computationnelle appelée FAMOUS (pour fast algorithm for three-dimensional (3D) multiphoton microscopy of biomedical structures) basée sur une approche de microscopie multiphotonique assistée par calcul. Le but est l’amélioration visuelle des images d'échantillons biologiques épais offrant ain...
The 21st century extreme societal situations, such as the global
COVID-19 Coronavirus pandemic, represent major upheavals for people and societies. The COVID-19 pandemic breakdown that has been elicited by the invisible virus SARS-CoV-2 has led to the collapse of representations of the common reality and it has shattered many important aspects of p...
The 21st century extreme situations, such as the global COVID-19 breakdown elicited by the invisible SARS-CoV-2 virus, represent major collective upheavals for people and societies. Indeed, to date, the global COVID-19 Coronavirus pandemic has caused more than 336 790 193 confirmed cases and 5 560 718 deaths (World Health Organization: Coronavirus...
We characterize the 3D spatial distribution of the quadratic susceptibility in an optically poled graded-index multimode fiber in presence of spatial beam self-cleaning. We also show how the poling process can improve the beam self-cleaning.
La crise du Covid-19 que nous traversons nous place face à l’ennemi invisible qui contraint notre relation aux autres : ce sont tous nos repères, toutes nos valeurs qui semblent bouleversés. Pourtant, ce virus invisible est en permanence raconté, par les médias, par les pouvoirs publics. Ces récits ont ceci de commun : ils positionnent le virus dan...
The crisis of Covid-19 that we are crossing nowadays place us face-to-face with an enemy that constrains our relationship with others: the totality of our landmarks and our values seems shattered. Yet, this invisible virus is constantly an object of storytelling by mass media and authorities. These stories have a common point: they place the virus...
RESUME: La crise du Covid-19 que nous traversons nous place face à ennemi qui contraint notre relation aux autres : ce sont tous nos repères, toutes nos valeurs qui semblent bouleversés. Pourtant, ce virus invisible est en permanence raconté, par les médias, par les pouvoirs publics. Ces récits ont ceci de commun : ils positionnent le virus dans un...
The global sanitary COVID-19 pandemic represents major collective upheaval for laypeople that has shattered many aspects of their lives. Therefore, a pluri-disciplinary research approach appears necessary in order to seize the complex extraordinary societal circumstances of the global COVID-19 pandemic breakdown. The pluri-disciplinary research pro...
Extraordinary societal events, such as global sanitary pandemics that human beings are facing since the beginning of humankind represent major collective upheaval for laymen. The COVID-19 pandemic that is responsible for the Coronavirus disease has been assessed by various large-scale epidemiological indices. Further, hard sciences researchers are...
During current pandemic times, we barely convince people to protect themselves against an invisible enemy such as SARS-CoV-2. By the use of multiphoton microscopy (MPM), our aim is to show the virus in 3D in order to simplify the sample preparation and to observe the pathogen without chemical modification or marking by endogenous fluorescence. Howe...
La complexité de la pandémie de COVID-19 révèle d’importants débats méthodologiques quant à l’articulation de différentes approches de recherche. L’objectif de cette communication est de présenter le projet CoviZion, porté par les laboratoires CeReS et Xlim de l’Université de Limoges, pour mettre en évidence la nécessité d’une approche pluridiscipl...
Large-scale societal threats, such as the COVID-19 Coronavirus pandemic, are leading to the rupture of continuity between humans’ usual expectations and the reality that became suddenly unpredictable and uncertain. The SARS-CoV-2 virus causing the Coronavirus disease remains invisible to laymen and these extraordinary circumstances tend to elicit a...
We present a new instrumental and computational pipeline named FAMOUS: f ast a lgorithm for three-dimensional (3D) m ultiphoton microscopy of bi o medical str u cture s . This pipeline rests on a MPM strategy combined with an original 3D post-processing computational approach. In the present work, FAMOUS approach is devoted to the 3D imaging of the...
We hardly convince people that they are fighting against an invisible enemy with barrier gestures without proper scientific arguments. The aim of this pluri-disciplinary research program is to understand the viral strategy of SARS-CoV-2 virus that is responsible for the Coronavirus disease, and therefore rationalize the perceived biological threat...
The COVID-19 coronavirus pandemic that we are facing nowadays has shattered various aspects of people's lives worldwide. Although, SARS-CoV-2 virus that is responsible for the coronavirus disease remains invisible to people. Therefore, a pluri-disciplinary research approach appears necessary in order to challenge the invisible enemy and the related...
We demonstrate the benefit of a novel laser strategy in multiphoton microscopy (MPM). The cheap, simple, and turn‐key supercontinuum laser system with its spectral shaping module, constitutes an ideal approach for the one‐shot microscopic imaging of many fluorophores without modification of the excitation parameters: central wavelength, spectral ba...
Fitting Gaussian functions to empirical data is a crucial task in a variety of scientific applications, especially in image processing. However, most of the existing approaches for performing such fitting are restricted to two dimensions and they cannot be easily extended to higher dimensions. Moreover, they are usually based on alternating minimiz...
Supercontinuum sources are commonly based on the combination of an infrared laser and a photonic crystal fibre (PCF), along which high peak power optical pulses are propagated in highly nonlinear regime. The spectral broadening obtained by this technique ranges from the ultraviolet/visible to the deep near infrared. We introduce the potential of “l...
Multiphoton microscopy (MPM) has been the subject of major development efforts for about 25 years for imaging biological specimens at micron scale and presented as an elegant alternative to classical fluorescence methods such as confocal microscopy. In this topical review, the main interests and technical requirements of MPM are addressed with a fo...
The influence of infrared laser pulses on intracellular Ca(2+) signaling was investigated in neural cell lines with fluorescent live cell imaging. The probe Fluo-4 was used to measure Ca(2+) in HT22 mouse hippocampal neurons and non-electrically excitable U87 human glioblastoma cells exposed to 50-500 ms infrared pulses at 1470 nm. Fluorescence rec...
La stimulation optique de cibles biologiques est aujourd’hui un thème d’actualité dans la recherche de moyens curatifs de certaines maladies neurodégénératives. Mais le mécanisme mis en jeu est encore controversé et donc peu maîtrisé. Des éléments factuels manquent à sa compréhension. Parmi les hypothèses existantes, le rôle de la modification loca...
P28 : Nous montrons l’intérêt des sources pulsées nanosecondes à très large spectre dites « supercontinuum » (nsSC) pour l’imagerie multiphotonique des structures biologiques de muscles. Grâce à leur spectre très large, plusieurs substances biologiques peuvent être imagés simultanément, notamment les substances fluorescentes endogènes ou bien celle...
Nous montrons l’intérêt des sources pulsées nanosecondes à très large spectre dites « supercontinuum » (nsSC) pour l’imagerie multiphotonique des structures biologiques de muscles à l’échelle du micron. Grâce à leur spectre très large, plusieurs substances biologiques constituant les tissus biologiques peuvent être imagés simultanément, notamment l...
La stimulation optique de cibles biologiques est aujourd’hui un thème d’actualité dans la recherche de moyens curatifs de certaines maladies neurodégénératives. Mais le mécanisme mis en jeu est encore controversé et donc peu maîtrisé. Des éléments factuels manquent à sa compréhension. Parmi les hypothèses existantes, le rôle de la modification loca...
We introduce an experiment using electro-CARS, an electro-optical method based on the combination of ultrabroadband multiplex coherent anti-Stokes Raman scattering (M-CARS) spectroscopy and electric field stimulation. We demonstrate that this method can effectively discriminate the resonant CARS signal from the nonresonant background owing to a phe...
In this work, we present a detailed characterization of a small-core double-clad photonic crystal fiber, dedicated and approved for in vivo nonlinear imaging endomicroscopy. A numerical and experimental study has been performed to characterize the excitation and collection efficiencies through a 5 m-long optical fiber, including the pulse duration...
The influence of a static electric field on a non-polar molecule has been studied by means of multiplex coherent anti-Stokes Raman scattering (M-CARS). A parallel measurement of electric field induced second harmonic generation (EFISHG) has also been led. Both techniques suggest a reorientation of the molecule due to the presence of an electric fie...
Multiphoton microscopy is a well-established technique for biological imaging of several kinds of targets. It is classically based on multiphoton processes allowing two means of contrast simultaneously: two-photon fluorescence (TPF) and second harmonic generation (SHG). Today, the quasi exclusive laser technology used in that aim is femtosecond tit...
Infrared laser light radiation can be used to depolarize neurons and to stimulate neural activity. The absorption of infrared radiation and heating of biological tissue is thought to be the underlying mechanism of this phenomenon whereby local temperature increases in the plasma membrane of cells either directly influence membrane properties or act...
Particle size analyzers based on laser scattering commonly make use of light diffraction and scattering around the particle considered in its medium. For particle size below 50 μm, Fraunhofer theory must be abandoned in favor of Mie model, which requires to know the complex refractive index of both the particle and the medium. In this paper, we dem...
We demonstrate all-normal dispersion supercontinuum generation in the 1080 nm-1600 nm range by propagating subnanosecond pulses in a high numerical aperture standard optical fiber. The extreme saturation of the Raman gain provides a flat spectrum in the considered range, making this broadband source particularly suitable for coherent Raman spectros...
The absorption of infrared laser light radiation induces the heating of biological tissue, being able to lead to the stimulation of neural activity. Action potentials can be observed using fluorescence microscopy techniques using synthetic or genetically encoded calcium indicators. In this work, we studied the impact of infrared laser light on neur...
Multicolor multiphoton microscopy is experimentally demonstrated for the first time on a spectral bandwidth of excitation of 300 nm (full width half maximum) thanks to the implementation a nanosecond supercontinuum (SC) source compact and simple with a low repetition rate. The interest of such a wide spectral bandwidth, never demonstrated until now...
Today, prototypes of nonlinear endomicroscopes are appearing in order to transfer technics of multiphoton characterization of biological samples to humans in vivo in situ. But they require several optical optimizations to be adapted for a clinical use. Among them, the ideal distal lens, coupled with the ideal scanning system is not yet highlighted....
The temperature-dependent fluorescence property of Rhodamine B was used to measure changes in temperature at the cellular level induced by either infrared laser light exposure or high intensity, ultrashort pulsed electric fields. The thermal impact of these stimuli were demonstrated at the cellular level in time and contrasted with the change in te...
Interest in the interaction between laser light and biological samples has gained momentum in recent years, particularly in neurobiology, where there is significant potential to stimulate neurons with infrared laser light. Despite recent reports showing the application of infrared light for neurostimulation, the underlying mechanism is still unknow...
The use of infrared laser light (IRLL) for biomedical applications has gained momentum the potential applications in humans. The use of IRLL presents some limitations due to the dangerousness of these radiations when exceeding some safety thresholds depending on the target tissue. This position paper describes step by step a well-known technical me...
The development of a nonlinear endomicroscope is justified by the need for a non-invasive diagnosis tool to assess at the cellular level, in vivo and in live the presence of pathologies like cancer in a patient body. To do so, an important effort has to be made in the miniaturization of the distal head of the endoscope. We report in this paper our...
We report a study of gradient index (GRIN) lenses as a miniaturized micro-objective for in vivo imaging in the context of the development of a nonlinear endomicroscope. A numerical study of the parameters influencing the lateral resolution, excitation, and collection efficiency, when GRIN lens is coupled with a double clad fiber (DCF), is exposed....
The use of infrared laser light (IRLL) for biomedical applications has gained momentum the potential applications in humans. The use of IRLL presents some limitations due to the dangerousness of these radiations when exceeding some safety thresholds depending on the target tissue. This position paper describes step by step a well-known technical me...
Proteins are separated in field flow fractionation (FFF) according to a well-established mechanism described as the “Normal or Brownian” mode. In the case of the sub-technique using a hollow fiber, the focalization/relaxation position can be observed visually only with a transparent holder and using dyes as samples. Whatever the choice of instrumen...
Le projet concerne l’utilisation de champs électromagnétique pulsé nanoseconde (nsPEF) comme neuro-stimulation thérapeutique. L’objectif est de déterminer si les nsPEFs ont le pouvoir d’activer des cellules excitables comme les neurones, dans un modèle de sangsue in vivo, sans engendrer de perméabilisation ou mort cellulaire. Des techniques d’élect...
We experimentally demonstrate fiber delivery of sub-30-fs pulses in the near-infrared range achieving 1.6 nJ at the output of a 2-m-long standard single-mode fiber, starting with 150 fs pulse duration at laser output and with a standard system. It results from the compensation of linear and nonlinear effects by a grism-based stretcher giving a puls...
Several endomicroscope prototypes for nonlinear optical imaging were developed in the last decade for in situ analysis of tissue with cellular resolution by using short infrared light pulses. Fourier-transform-limited pulses at the tissue site are necessary for optimal excitation of faint endogenous signals. However, obtaining these transform-limit...
Mots clés: Cancer, champs électromagnétique, microscopie multiphotonique, vascularisation, traitements anti-tumoraux Depuis ces dernières années, le cancer est en passe de devenir un défi sociétal immense en raison de son incidence comme la cause principale de mort médicale humaine dans le monde (8.2 millions de morts en 2012, Ref. WHO). Malheureus...
Nonlinear endomicroscopic design based on GRIN lens and a double clad fiber was optimized for pulse delivery, high fluorescence collection and resolution. Grism-based stretcher compensated efficiently for linear and nonlinear effects in our system.
Linear and nonlinear optical imaging systems are currently being miniaturized to fit endoscopic size requirements of a diameter less than 2 mm. These systems are used for deep imaging and optical biopsy. We report our progress in the development of a multimodal microendoscope based on Gradient Index (GRIN) lenses and double clad fiber (DCF) for fem...
This work deals with label free multiphoton imaging of the human lung tissue extra-cellular matrix (ECM) through
optical fibers. Two devices were developed, the first one using distal scanning associated to a double clad large mode
area (LMA) air-silica microstructured fiber, the second one using proximal scanning of a miniature multicore image
gui...
