11 research outputs found
Parametric study of EEG sensitivity to phase noise during face processing
No full text<b>Background: </b>
The present paper examines the visual processing speed of complex objects, here faces, by mapping the relationship between object physical properties and single-trial brain responses. Measuring visual processing speed is challenging because uncontrolled physical differences that co-vary with object categories might affect brain measurements, thus biasing our speed estimates. Recently, we demonstrated that early event-related potential (ERP) differences between faces and objects are preserved even when images differ only in phase information, and amplitude spectra are equated across image categories. Here, we use a parametric design to study how early ERP to faces are shaped by phase information. Subjects performed a two-alternative force choice discrimination between two faces (Experiment 1) or textures (two control experiments). All stimuli had the same amplitude spectrum and were presented at 11 phase noise levels, varying from 0% to 100% in 10% increments, using a linear phase interpolation technique. Single-trial ERP data from each subject were analysed using a multiple linear regression model.
<b>Results: </b>
Our results show that sensitivity to phase noise in faces emerges progressively in a short time window between the P1 and the N170 ERP visual components. The sensitivity to phase noise starts at about 120–130 ms after stimulus onset and continues for another 25–40 ms. This result was robust both within and across subjects. A control experiment using pink noise textures, which had the same second-order statistics as the faces used in Experiment 1, demonstrated that the sensitivity to phase noise observed for faces cannot be explained by the presence of global image structure alone. A second control experiment used wavelet textures that were matched to the face stimuli in terms of second- and higher-order image statistics. Results from this experiment suggest that higher-order statistics of faces are necessary but not sufficient to obtain the sensitivity to phase noise function observed in response to faces.
<b>Conclusion: </b>
Our results constitute the first quantitative assessment of the time course of phase information processing by the human visual brain. We interpret our results in a framework that focuses on image statistics and single-trial analyses
Masks and metamorphosis
No full textThe purpose of this study is to consider the uses of the mask in ritual and theatre, and in particular the reputed influence of the mask over the wearer, and the experiences of 'trance' and 'possession' reported by anthropologists and mask practitioners and performers. The study also examines the role of the maker in creating a powerful tool for ritual and performance, and the comparatively rare phenomenon of the mask-maker who creates a mask which he or she will subsequently wear and the potential paradox of the maker 'possessed' by the object he has made. The first chapter focuses on the mask in its practical and ritualistic contexts in many cultures, and the second considers the concept of mask and transformation in ritual and theatre. The third describes a number of approaches to the use of mask in contemporary drama, in both the creation and performance of theatre. Chapter Four further investigates the effects of the mask on wearer and audience, and attempts to account for some of the experiences described by wearers. The fifth chapter examines the role of the mask maker in ritual and theatre, the relationship between mask and maker, and the maker as wearer. The sixth chapter centres on children as makers and wearers of masks, and focuses on primary school mask making and performance projects. The final chapter explores the relationship of the mask and the self, the assumed and the actual identities of the masquerader. Appendices I-XIV describe the experiences of mask makers and wearers in a variety of contexts, and provide additional evidence of the unusual sensations experienced by wearers. The thesis aims to investigate some of the causes of these phenomena and to consider strategies adopted by practitioners, directors and dramatherapists for utilising these heightened experiences to positive effect in performance
«La relation de limitation et d’exception dans le français d’aujourd’hui : excepté, sauf et hormis comme pivots d’une relation algébrique »
No full textL’analyse des emplois prépositionnels et des emplois conjonctifs d’ “excepté”, de “sauf” et d’ “hormis” permet d’envisager les trois prépositions/conjonctions comme le pivot d’un binôme, comme la plaque tournante d’une structure bipolaire. Placées au milieu du binôme, ces prépositions sont forcées par leur sémantisme originaire dûment métaphorisé de jouer le rôle de marqueurs d’inconséquence systématique entre l’élément se trouvant à leur gauche et celui qui se trouve à leur droite. L’opposition qui surgit entre les deux éléments n’est donc pas une incompatibilité naturelle, intrinsèque, mais extrinsèque, induite. Dans la plupart des cas (emplois limitatifs), cette opposition prend la forme d’un rapport entre une « classe » et le « membre (soustrait) de la classe », ou bien entre un « tout » et une « partie » ; dans d’autres (emplois exceptifs), cette opposition se manifeste au contraire comme une attaque de front portée par un « tout » à un autre « tout ». De plus, l’inconséquence induite mise en place par la préposition/conjonction paraît, en principe, tout à fait insurmontable. Dans l’assertion « les écureuils vivent partout, sauf en Australie » (que l’on peut expliciter par « Les écureuils vivent partout, sauf [qu’ils ne vivent pas] en Australie »), la préposition semble en effet capable d’impliquer le prédicat principal avec signe inverti, et de bâtir sur une telle implication une sorte de sous énoncé qui, à la rigueur, est totalement inconséquent avec celui qui le précède (si « les écureuils ne vivent pas en Australie », le fait qu’ils « vivent partout » est faux). Néanmoins, l’analyse montre qu’alors que certaines de ces oppositions peuvent enfin être dépassées, d’autres ne le peuvent pas. C’est, respectivement, le cas des relations limitatives et des relations exceptives. La relation limitative, impliquant le rapport « tout » - « partie », permet de résoudre le conflit dans les termes d’une somme algébrique entre deux sous énoncés pourvus de différent poids informatif et de signe contraire. Les valeurs numériques des termes de la somme étant déséquilibrées, le résultat est toujours autre que zéro. La relation exceptive, au contraire, qui n’implique pas le rapport « tout » - « partie », n’est pas capable de résoudre le conflit entre deux sous énoncés pourvus du même poids informatif et en même temps de signe contraire : les valeurs numériques des termes de la somme étant symétriques et égales, le résultat sera toujours équivalent à zéro
What are You Thinking? Who Has the Right to Know?:Brain Imaging and its Impact on Society
No full text3D wind measurement with a wind lidar including a quad-Mach-Zehnder interferometer developed for on-board measurement
No full textInternational audienceOn-board 3D wind measurement at all altitudes has numerous aeronautical applications (Gust Load Alleviation, HAPS, etc.) or space (wind measurement with Aeolus, calibration/validation of Aeolus data). This 3D wind measurement is particularly interesting in turbulent wind for several applications such as weather and climate forecasting, planning and safety of aircraft during their flight, transport of aerosols and pollution, monitoring of weather conditions in case disasters, wind power generation, forest fires and volcanic plume movement. (see session A.01.09). The instrument developed for this type of measurement is the direct detection UV lidar which sends a laser pulse into the atmosphere and determines, with a spectral analyzer, the wind projected on the axis of the lidar from the Doppler shift induced by the particles (low altitude) and molecules (high altitudes) of the atmosphere. To measure the radial wind, the quad Mach-Zehnder (QMZ) interferometer is, to our knowledge, the best compromise between precision and robustness [D. Bruneau and J. Pelon, ATM. Measures. Technology. 14 4375-2021 (2021)]. Additionally, such an analyzer can also be used to determine particle backscatter coefficients, extinction coefficient and can be extended with a dedicated channel for aerosol and cloud polarization analysis. This is why, at ONERA, we are developing an all-altitude wind lidar solution based on a QMZ analyzer. The 3D wind is then reconstructed by addressing the lidar axis in several directions and using an algorithm (C. Musso et al., session A.01.09) to recover the 3D wind components from the measured wind projections. This instrument includes several solutions to obtain a vibration-robust version of the different lidar components (analyzer, laser, transmission/reception, scanning system and overall instrument). The QMZ interferometer is a two-wave interferometer that provides four signals of the two-wave interference pattern, in phase quadrature, used to determine the frequency shift of backscattered light energy and derive the radial wind speed. The advantages of the QMZ interferometer, compared to other solutions, are as follows: (1) it is not sensitive to the frequency drift of the laser source, (2) it is not sensitive to the shape of the backscattered spectrum, (3) it gives a small statistical error equal to 2.35 (εvr)ISA where (εvr)ISA is the error obtained for an ideal analyzer, (4) it can include a field compensation design which allows a wide angle of incident field and facilitates their adaptation with an extended wide beam system, and (5) it uses mono-detectors which do not truncate the collected signal (compared to marginal imaging systems). In order to be on-board, two architectures of interferometers robust to vibrations are developed at ONERA: (1) a first based on commercial components and (2) a second monolithic, made up of adhesion of all the optical components. The first version is cheaper and easier to study in depth while the second version is more solid. To obtain architectures insensitive to angular misalignment, both are composed of a single separator and two retroreflective optics. An innovative calibration procedure was developed to determine the exact contrast and phase difference between the four outputs based on the Lissajou curves. The two architectures, their simulated performances and the first experimental results will be presented. In addition to the spectral analyzer, the wind lidar includes several components that must be compacted and reinforced to be able to be used on aircraft. Typically used solid-state UV lasers are very sensitive to vibrations (especially the laser cavity) and their use on board generally requires using a lot of metal to make it insensitive to vibrations, leading to very heavy and expensive solutions. To resolve this problem, we are developing a solution based on a fiber laser which has the advantage of being, in the long term, lighter and more robust to vibrations. The architecture of the system used to address/focus the laser in the probed region and collect the backscattered light from this region is generally designed in a bistatic configuration where the optical axes of the two systems are determined with different optics. However, the transmission and reception must have the same axis, which poses a problem in vibration conditions, for long distance measurements, due to the large lever arm of the two systems. To avoid this problem, we have developed a new monostatic configuration close to that commonly used for heterodyne lidars. To address the beam in different directions, we design a static system comprising several duplicated monostatic transmit/receive instruments. A time multiplexing method is developed to use a shared spectral analyzer to process all axes. The addressed angles were optimized using the 3D wind reconstruction algorithm presented in (C. Musso et al., session A.01.09). The design of all these components will be presented. The project 101101974 – UP Wing is supported by the Clean Aviation Joint Undertaking and its members. Funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or Clean Aviation Joint Undertaking. Neither the European Union nor the granting authority can be held responsible for the
3D wind measurement with a wind lidar including a quad-Mach-Zehnder interferometer developed for on-board measurement
No full textInternational audienceOn-board 3D wind measurement at all altitudes has numerous aeronautical applications (Gust Load Alleviation, HAPS, etc.) or space (wind measurement with Aeolus, calibration/validation of Aeolus data). This 3D wind measurement is particularly interesting in turbulent wind for several applications such as weather and climate forecasting, planning and safety of aircraft during their flight, transport of aerosols and pollution, monitoring of weather conditions in case disasters, wind power generation, forest fires and volcanic plume movement. (see session A.01.09). The instrument developed for this type of measurement is the direct detection UV lidar which sends a laser pulse into the atmosphere and determines, with a spectral analyzer, the wind projected on the axis of the lidar from the Doppler shift induced by the particles (low altitude) and molecules (high altitudes) of the atmosphere. To measure the radial wind, the quad Mach-Zehnder (QMZ) interferometer is, to our knowledge, the best compromise between precision and robustness [D. Bruneau and J. Pelon, ATM. Measures. Technology. 14 4375-2021 (2021)]. Additionally, such an analyzer can also be used to determine particle backscatter coefficients, extinction coefficient and can be extended with a dedicated channel for aerosol and cloud polarization analysis. This is why, at ONERA, we are developing an all-altitude wind lidar solution based on a QMZ analyzer. The 3D wind is then reconstructed by addressing the lidar axis in several directions and using an algorithm (C. Musso et al., session A.01.09) to recover the 3D wind components from the measured wind projections. This instrument includes several solutions to obtain a vibration-robust version of the different lidar components (analyzer, laser, transmission/reception, scanning system and overall instrument). The QMZ interferometer is a two-wave interferometer that provides four signals of the two-wave interference pattern, in phase quadrature, used to determine the frequency shift of backscattered light energy and derive the radial wind speed. The advantages of the QMZ interferometer, compared to other solutions, are as follows: (1) it is not sensitive to the frequency drift of the laser source, (2) it is not sensitive to the shape of the backscattered spectrum, (3) it gives a small statistical error equal to 2.35 (εvr)ISA where (εvr)ISA is the error obtained for an ideal analyzer, (4) it can include a field compensation design which allows a wide angle of incident field and facilitates their adaptation with an extended wide beam system, and (5) it uses mono-detectors which do not truncate the collected signal (compared to marginal imaging systems). In order to be on-board, two architectures of interferometers robust to vibrations are developed at ONERA: (1) a first based on commercial components and (2) a second monolithic, made up of adhesion of all the optical components. The first version is cheaper and easier to study in depth while the second version is more solid. To obtain architectures insensitive to angular misalignment, both are composed of a single separator and two retroreflective optics. An innovative calibration procedure was developed to determine the exact contrast and phase difference between the four outputs based on the Lissajou curves. The two architectures, their simulated performances and the first experimental results will be presented. In addition to the spectral analyzer, the wind lidar includes several components that must be compacted and reinforced to be able to be used on aircraft. Typically used solid-state UV lasers are very sensitive to vibrations (especially the laser cavity) and their use on board generally requires using a lot of metal to make it insensitive to vibrations, leading to very heavy and expensive solutions. To resolve this problem, we are developing a solution based on a fiber laser which has the advantage of being, in the long term, lighter and more robust to vibrations. The architecture of the system used to address/focus the laser in the probed region and collect the backscattered light from this region is generally designed in a bistatic configuration where the optical axes of the two systems are determined with different optics. However, the transmission and reception must have the same axis, which poses a problem in vibration conditions, for long distance measurements, due to the large lever arm of the two systems. To avoid this problem, we have developed a new monostatic configuration close to that commonly used for heterodyne lidars. To address the beam in different directions, we design a static system comprising several duplicated monostatic transmit/receive instruments. A time multiplexing method is developed to use a shared spectral analyzer to process all axes. The addressed angles were optimized using the 3D wind reconstruction algorithm presented in (C. Musso et al., session A.01.09). The design of all these components will be presented. The project 101101974 – UP Wing is supported by the Clean Aviation Joint Undertaking and its members. Funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or Clean Aviation Joint Undertaking. Neither the European Union nor the granting authority can be held responsible for the
3D wind measurement with a wind lidar including a quad-Mach-Zehnder interferometer developed for on-board measurement
No full textInternational audienceOn-board 3D wind measurement at all altitudes has numerous aeronautical applications (Gust Load Alleviation, HAPS, etc.) or space (wind measurement with Aeolus, calibration/validation of Aeolus data). This 3D wind measurement is particularly interesting in turbulent wind for several applications such as weather and climate forecasting, planning and safety of aircraft during their flight, transport of aerosols and pollution, monitoring of weather conditions in case disasters, wind power generation, forest fires and volcanic plume movement. (see session A.01.09). The instrument developed for this type of measurement is the direct detection UV lidar which sends a laser pulse into the atmosphere and determines, with a spectral analyzer, the wind projected on the axis of the lidar from the Doppler shift induced by the particles (low altitude) and molecules (high altitudes) of the atmosphere. To measure the radial wind, the quad Mach-Zehnder (QMZ) interferometer is, to our knowledge, the best compromise between precision and robustness [D. Bruneau and J. Pelon, ATM. Measures. Technology. 14 4375-2021 (2021)]. Additionally, such an analyzer can also be used to determine particle backscatter coefficients, extinction coefficient and can be extended with a dedicated channel for aerosol and cloud polarization analysis. This is why, at ONERA, we are developing an all-altitude wind lidar solution based on a QMZ analyzer. The 3D wind is then reconstructed by addressing the lidar axis in several directions and using an algorithm (C. Musso et al., session A.01.09) to recover the 3D wind components from the measured wind projections. This instrument includes several solutions to obtain a vibration-robust version of the different lidar components (analyzer, laser, transmission/reception, scanning system and overall instrument). The QMZ interferometer is a two-wave interferometer that provides four signals of the two-wave interference pattern, in phase quadrature, used to determine the frequency shift of backscattered light energy and derive the radial wind speed. The advantages of the QMZ interferometer, compared to other solutions, are as follows: (1) it is not sensitive to the frequency drift of the laser source, (2) it is not sensitive to the shape of the backscattered spectrum, (3) it gives a small statistical error equal to 2.35 (εvr)ISA where (εvr)ISA is the error obtained for an ideal analyzer, (4) it can include a field compensation design which allows a wide angle of incident field and facilitates their adaptation with an extended wide beam system, and (5) it uses mono-detectors which do not truncate the collected signal (compared to marginal imaging systems). In order to be on-board, two architectures of interferometers robust to vibrations are developed at ONERA: (1) a first based on commercial components and (2) a second monolithic, made up of adhesion of all the optical components. The first version is cheaper and easier to study in depth while the second version is more solid. To obtain architectures insensitive to angular misalignment, both are composed of a single separator and two retroreflective optics. An innovative calibration procedure was developed to determine the exact contrast and phase difference between the four outputs based on the Lissajou curves. The two architectures, their simulated performances and the first experimental results will be presented. In addition to the spectral analyzer, the wind lidar includes several components that must be compacted and reinforced to be able to be used on aircraft. Typically used solid-state UV lasers are very sensitive to vibrations (especially the laser cavity) and their use on board generally requires using a lot of metal to make it insensitive to vibrations, leading to very heavy and expensive solutions. To resolve this problem, we are developing a solution based on a fiber laser which has the advantage of being, in the long term, lighter and more robust to vibrations. The architecture of the system used to address/focus the laser in the probed region and collect the backscattered light from this region is generally designed in a bistatic configuration where the optical axes of the two systems are determined with different optics. However, the transmission and reception must have the same axis, which poses a problem in vibration conditions, for long distance measurements, due to the large lever arm of the two systems. To avoid this problem, we have developed a new monostatic configuration close to that commonly used for heterodyne lidars. To address the beam in different directions, we design a static system comprising several duplicated monostatic transmit/receive instruments. A time multiplexing method is developed to use a shared spectral analyzer to process all axes. The addressed angles were optimized using the 3D wind reconstruction algorithm presented in (C. Musso et al., session A.01.09). The design of all these components will be presented. The project 101101974 – UP Wing is supported by the Clean Aviation Joint Undertaking and its members. Funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or Clean Aviation Joint Undertaking. Neither the European Union nor the granting authority can be held responsible for the
Biobehavioural and cerebral hemodynamic effects of omega-3 polyunsaturated fatty acids in healthy individuals
No full textThe omega-3 polyunsaturated fatty acids (n-3 PUFAs) are a unique class of fatty acids that cannot be manufactured by the body, and must be acquired via dietary sources. In the UK, as well as in other Western nations, these ‘essential’ fatty acids are consumed in quantities that fall below government guidelines. This thesis examined the relationship between n-3 PUFAs and cognitive function and mood in healthy children (8-10 years) and adults (18-35 years), with a view to evaluate their efficacy for cognitive and mood enhancement in these populations. A second aim was to evaluate the effects of n-3 PUFAs on cerebral hemodynamics, a novel line of enquiry. Chapters 2 and 4 describe novel intervention studies that assessed the effects of n- 3 PUFA supplements on cognitive function and mood in healthy children and adults, respectively. In Chapter 3, the relationship between peripheral PUFA concentrations, a correlate of dietary PUFA intake, and cognitive and function and mood was examined for the first time in healthy adults. Chapter 5 describes a pilot trial in which Near Infrared Spectroscopy (NIRS) imaging technique was applied to investigate the cerebral hemodynamic effects of n-3 PUFA supplements. The results of this study were explored in more detail in Chapter 6, with the additional inclusion of parallel cognitive measures. Most notably, the behavioural data from the intervention studies described herein do not support the use of n-3 PUFA supplements for cognitive and mood enhancement in healthy children and adults not consuming appreciable amounts of oily fish. However, the results do suggest that supplementation with dietary n-3 PUFAs has an impact on peripheral fatty acid status and cerebral hemodynamics in healthy adults. Taken together, these findings suggest that, in healthy, cognitively intact individuals, short-term use of n-3 PUFA supplements has a minimal effect on behaviour; the impact of long-term n-3 PUFA dietary intake or supplement use over the course of the entire lifespan on behaviour should be addressed further
Subgroup-specific structural variation across 1,000 medulloblastoma genomes
No full textMedulloblastoma, the most common malignant paediatric brain tumour, is currently treated with nonspecific cytotoxic therapies including surgery, whole-brain radiation, and aggressive chemotherapy. As medulloblastoma exhibits marked intertumoural heterogeneity, with at least four distinct molecular variants, previous attempts to identify targets for therapy have been underpowered because of small samples sizes. Here we report somatic copy number aberrations (SCNAs) in 1,087 unique medulloblastomas. SCNAs are common in medulloblastoma, and are predominantly subgroup-enriched. The most common region of focal copy number gain is a tandem duplication of SNCAIP, a gene associated with Parkinson's disease, which is exquisitely restricted to Group 4 alpha. Recurrent translocations of PVT1, including PVT1-MYC and PVT1-NDRG1, that arise through chromothripsis are restricted to Group 3. Numerous targetable SCNAs, including recurrent events targeting TGF-beta signalling in Group 3, and NF-kappa B signalling in Group 4, suggest future avenues for rational, targeted therapy.CIHR Clinician-Scientist Phase II awardCIHR ClinicianScientist Phase II awardSontag FoundationSontag FoundationPediatric Brain Tumour FoundationPediatric Brain Tumour FoundationNational Institutes of Health [CA159859]National Institutes of HealthThe Family of Kathleen LoretteThe Family of Kathleen LoretteClark H. Smith Brain Tumour CentreClark H. Smith Brain Tumour CentreMontreal Childrens Hospital FoundationMontreal Children's Hospital FoundationHospital for Sick Children: Sonia and Arthur Labatt Brain Tumour Research CentreHospital for Sick Children: Sonia and Arthur Labatt Brain Tumour Research CentreChief of Research FundChief of Research FundCancer Genetics ProgramCancer Genetics ProgramGarron Family Cancer CentreGarron Family Cancer CentreB.R.A.I.N. ChildB.R.A.I.N. ChildCIHR [ATE-110814]CIHRUniversity of Toronto McLaughlin CentreUniversity of Toronto McLaughlin CentreCIHR Institute of Cancer Research [AT1-112286]CIHR Institute of Cancer ResearchBC Cancer FoundationBC Cancer FoundationChildren's Discovery InstituteChildrens Discovery InstituteRestracomp Fellowship (Hospital for Sick Children)Restracomp Fellowship (Hospital for Sick Children)Ontario Institute for Cancer ResearchOntario Institute for Cancer ResearchGovernment of OntarioGovernment of OntarioNIHNIH [CA86335, CA116804, CA138292]NCINCI [28XS100, 29XS193]Southeastern Brain Tumour FoundationSoutheastern Brain Tumour FoundationBrain Tumour Foundation for ChildrenBrain Tumour Foundation for ChildrenUK Children's Cancer and Leukaemia Group (CCLG) [BS-2007-04]UK Childrens Cancer and Leukaemia Group (CCLG)German Cancer AidGerman Cancer Aid [109252
A method to exploit the structure of genetic ancestry space to enhance case-control studies
No full textOne goal of human genetics is to understand the genetic basis of disease, a challenge for diseases of complex inheritance because risk alleles are few relative to the vast set of benign variants. Risk variants are often sought by association studies in which allele frequencies in case subjects are contrasted with those from population-based samples used as control subjects. In an ideal world we would know population-level allele frequencies, releasing researchers to focus on case subjects. We argue this ideal is possible, at least theoretically, and we outline a path to achieving it in reality. If such a resource were to exist, it would yield ample savings and would facilitate the effective use of data repositories by removing administrative and technical barriers. We call this concept the Universal Control Repository Network (UNICORN), a means to perform association analyses without necessitating direct access to individual-level control data. Our approach to UNICORN uses existing genetic resources and various statistical tools to analyze these data, including hierarchical clustering with spectral analysis of ancestry; and empirical Bayesian analysis along with Gaussian spatial processes to estimate ancestry-specific allele frequencies. We demonstrate our approach using tens of thousands of control subjects from studies of Crohn disease, showing how it controls false positives, provides power similar to that achieved when all control data are directly accessible, and enhances power when control data are limiting or even imperfectly matched ancestrally. These results highlight how UNICORN can enable reliable, powerful, and convenient genetic association analyses without access to the individual-level data
