19 research outputs found
MedShapeNet -- A Large-Scale Dataset of 3D Medical Shapes for Computer Vision
Prior to the deep learning era, shape was commonly used to describe the
objects. Nowadays, state-of-the-art (SOTA) algorithms in medical imaging are
predominantly diverging from computer vision, where voxel grids, meshes, point
clouds, and implicit surface models are used. This is seen from numerous
shape-related publications in premier vision conferences as well as the growing
popularity of ShapeNet (about 51,300 models) and Princeton ModelNet (127,915
models). For the medical domain, we present a large collection of anatomical
shapes (e.g., bones, organs, vessels) and 3D models of surgical instrument,
called MedShapeNet, created to facilitate the translation of data-driven vision
algorithms to medical applications and to adapt SOTA vision algorithms to
medical problems. As a unique feature, we directly model the majority of shapes
on the imaging data of real patients. As of today, MedShapeNet includes 23
dataset with more than 100,000 shapes that are paired with annotations (ground
truth). Our data is freely accessible via a web interface and a Python
application programming interface (API) and can be used for discriminative,
reconstructive, and variational benchmarks as well as various applications in
virtual, augmented, or mixed reality, and 3D printing. Exemplary, we present
use cases in the fields of classification of brain tumors, facial and skull
reconstructions, multi-class anatomy completion, education, and 3D printing. In
future, we will extend the data and improve the interfaces. The project pages
are: https://medshapenet.ikim.nrw/ and
https://github.com/Jianningli/medshapenet-feedbackComment: 16 page
DĂ©tection des Ă©vĂšnements exceptionnels Ă partir des observations IASI
The IASI (Infrared Atmospheric Sounding Interferometer) instruments aboard the Metop-A, -B and -C satellites have been measuring the infrared radiation (IR) emitted by the Earth-atmosphere system since 2006. Every day, several million spectra are recorded by IASI, which constitutes a large volume of data. One of the problems inherent to this amount of data is the search for extreme events. Indeed, it is possible to observe extreme events from level 2 data (L2), i.e. gas concentrations, but the retrieval is generally only possible under clear sky conditions. Moreover, it is difficult to search for these events from L2 data and to characterize them in real time. This thesis work addresses the need to implement an innovative detection algorithm to directly process the radiance spectra (level 1 data â L1C). An optimized method for the detection of extreme events has been developed from PCA (Principal Component Analysis) on IASI radiances, which allows both the compression of the data but also the reduction of instrumental noise. This method relies on the creation of a training database representative of the atmospheric variability, allowing to keep all the information during the compression/reconstruction of IASI radiances. However, extreme events are outside the normal atmospheric variability and will be ill-reconstructed. By taking into account the extreme values resulting from the ill-reconstructed IASI spectra, we can study the anomalous atmospheric signal. In order to allow a systematic, automatic and accurate analysis allowing the detection and characterization of anomalies, the analysis is performed on sets of radiance spectra observed during 3 min time steps (IASI granule). In addition, the characterization of absorbing trace species is performed using different thresholds and fine spectral indicators defined from radiative transfer simulations and spectroscopic database. This method called IASI-PCA-GE (GE for granule extrema) allows then to detect and characterize in quasi real time the atmospheric anomalies associated with extreme events such as fires, volcanic eruptions or anthropic pollution episodes. A first part of this thesis work consisted in analyzing different past extreme events documented during the IASI period. Then the IASI-PCA-GE method was applied to IASI data for several study cases and the results were compared with existing L2 data. Furthermore, extreme event archives of volcanic eruptions and fire episodes were generated from the results of this method, which was applied to the complete IASI-B time series (2013-2022). The method is able to detect the presence of numerous molecules and the comparison with the L2 data shows a good agreement between the two datasets. However, some limitations remain and are discussed. The method developed during this thesis can also be applied to future missions, such as the IASI-NG/Metop-SG mission and the MTG-IRS geostationary mission, which are scheduled to be launched in 2024.Les instruments IASI (InterfĂ©romĂštre AtmosphĂ©rique de Sondage dans l'Infrarouge) Ă bord des satellites Metop-A, -B et -C mesurent le rayonnement infrarouge (IR) Ă©mis par le systĂšme Terre-atmosphĂšre depuis 2006. Chaque jour plusieurs millions de spectres sont enregistrĂ©s par IASI, ce qui constitue un volume important de donnĂ©es. Une des problĂ©matiques inhĂ©rentes Ă cette quantitĂ© de donnĂ©es rĂ©side dans la recherche dâĂ©vĂšnements extrĂȘmes. En effet, il est possible dâobserver des Ă©vĂšnements extrĂȘmes Ă partir des donnĂ©es chimiques de niveau 2 (L2), câest-Ă -dire les concentrations de gaz mais lâinversion nâest gĂ©nĂ©ralement possible que pour des conditions de ciel clair. De plus il est difficile de rechercher ces Ă©vĂšnements Ă partir des donnĂ©es L2 et de les caractĂ©riser en temps rĂ©el. Ce travail de thĂšse rĂ©pond Ă la nĂ©cessitĂ© de mettre en place un algorithme de dĂ©tection innovant et opĂ©rationnel afin de traiter directement les spectres de radiances (donnĂ©es de niveau 1 â L1C). Une mĂ©thode optimisĂ©e pour la dĂ©tection dâĂ©vĂšnements extrĂȘmes a Ă©tĂ© dĂ©veloppĂ©e Ă partir de la mĂ©thode dâanalyse en composantes principales (ACP ou en anglais PCA pour principal component analysis) sur les luminances IASI qui permet Ă la fois la compression des donnĂ©es mais aussi la rĂ©duction du bruit instrumental. Cette mĂ©thode repose sur la crĂ©ation dâune base dâapprentissage reprĂ©sentative de la variabilitĂ© atmosphĂ©rique permettant alors de conserver toute lâinformation lors de la compression/reconstruction des luminances IASI. Les Ă©vĂšnements extrĂȘmes sortant de la variabilitĂ© atmosphĂ©rique normale sont caractĂ©risĂ©s par une mauvaise reconstruction. En prenant en compte les valeurs extrĂȘmes issues de la mauvaise reconstruction des spectres IASI on peut alors Ă©tudier le signal atmosphĂ©rique anormal. Les donnĂ©es IASI L1C Ă©tant disponibles toutes les 3 minutes sous forme de granule, il est naturel dâappliquer la mĂ©thode directement sur les granules IASI pour permettre une dĂ©tection en temps rĂ©el. De plus, la caractĂ©risation des espĂšces traces absorbantes est rĂ©alisĂ©e Ă partir de diffĂ©rentes combinaisons de raies intenses ou de bandes dâabsorption (appelĂ©s « indicateurs » spectraux) qui ont Ă©tĂ© dĂ©finies Ă partir de simulations de transfert radiatif et de bases de donnĂ©es spectroscopiques. Cette mĂ©thode de dĂ©tection, appelĂ©e IASI-PCA-GE (GE pour granule extrema), permet alors de dĂ©tecter en quasi temps rĂ©el les anomalies atmosphĂ©riques associĂ©es Ă des Ă©vĂšnements extrĂȘmes comme les feux, Ă©ruptions volcaniques ou les Ă©pisodes de pollution anthropique. Une premiĂšre partie de ce travail de thĂšse a consistĂ© Ă analyser diffĂ©rents Ă©vĂ©nements extrĂȘmes passĂ©s et documentĂ©s pendant la pĂ©riode IASI. Ensuite la mĂ©thode IASI-PCA-GE a Ă©tĂ© appliquĂ©e aux donnĂ©es IASI pour des plusieurs cas dâĂ©tude, et les rĂ©sultats ont Ă©tĂ© comparĂ©s avec les donnĂ©es L2 existants. Par ailleurs, une archive dâĂ©vĂ©nements extrĂȘmes dâĂ©ruptions volcaniques et dâĂ©pisodes de feux a Ă©tĂ© gĂ©nĂ©rĂ©e Ă partir des rĂ©sultats de cette mĂ©thode qui a Ă©tĂ© appliquĂ©e Ă la sĂ©rie temporelle IASI-B complĂšte (2013-2022). La mĂ©thode est capable de dĂ©tecter la prĂ©sence de nombreuses molĂ©cules et la comparaison avec les donnĂ©es L2 montre un bon accord entre les deux jeux de donnĂ©es. Cependant certaines limitations subsistent et sont discutĂ©es. La mĂ©thode dĂ©veloppĂ©e pendant cette thĂšse pourra par ailleurs ĂȘtre appliquĂ©e Ă des futures missions, telles que la mission IASI-NG/Metop-SG et la mission gĂ©ostationnaire MTG-IRS dont les lancements sont prĂ©vus en 2024
DĂ©tection des Ă©vĂšnements exceptionnels Ă partir des observations IASI
The IASI (Infrared Atmospheric Sounding Interferometer) instruments aboard the Metop-A, -B and -C satellites have been measuring the infrared radiation (IR) emitted by the Earth-atmosphere system since 2006. Every day, several million spectra are recorded by IASI, which constitutes a large volume of data. One of the problems inherent to this amount of data is the search for extreme events. Indeed, it is possible to observe extreme events from level 2 data (L2), i.e. gas concentrations, but the retrieval is generally only possible under clear sky conditions. Moreover, it is difficult to search for these events from L2 data and to characterize them in real time. This thesis work addresses the need to implement an innovative detection algorithm to directly process the radiance spectra (level 1 data â L1C). An optimized method for the detection of extreme events has been developed from PCA (Principal Component Analysis) on IASI radiances, which allows both the compression of the data but also the reduction of instrumental noise. This method relies on the creation of a training database representative of the atmospheric variability, allowing to keep all the information during the compression/reconstruction of IASI radiances. However, extreme events are outside the normal atmospheric variability and will be ill-reconstructed. By taking into account the extreme values resulting from the ill-reconstructed IASI spectra, we can study the anomalous atmospheric signal. In order to allow a systematic, automatic and accurate analysis allowing the detection and characterization of anomalies, the analysis is performed on sets of radiance spectra observed during 3 min time steps (IASI granule). In addition, the characterization of absorbing trace species is performed using different thresholds and fine spectral indicators defined from radiative transfer simulations and spectroscopic database. This method called IASI-PCA-GE (GE for granule extrema) allows then to detect and characterize in quasi real time the atmospheric anomalies associated with extreme events such as fires, volcanic eruptions or anthropic pollution episodes. A first part of this thesis work consisted in analyzing different past extreme events documented during the IASI period. Then the IASI-PCA-GE method was applied to IASI data for several study cases and the results were compared with existing L2 data. Furthermore, extreme event archives of volcanic eruptions and fire episodes were generated from the results of this method, which was applied to the complete IASI-B time series (2013-2022). The method is able to detect the presence of numerous molecules and the comparison with the L2 data shows a good agreement between the two datasets. However, some limitations remain and are discussed. The method developed during this thesis can also be applied to future missions, such as the IASI-NG/Metop-SG mission and the MTG-IRS geostationary mission, which are scheduled to be launched in 2024.Les instruments IASI (InterfĂ©romĂštre AtmosphĂ©rique de Sondage dans l'Infrarouge) Ă bord des satellites Metop-A, -B et -C mesurent le rayonnement infrarouge (IR) Ă©mis par le systĂšme Terre-atmosphĂšre depuis 2006. Chaque jour plusieurs millions de spectres sont enregistrĂ©s par IASI, ce qui constitue un volume important de donnĂ©es. Une des problĂ©matiques inhĂ©rentes Ă cette quantitĂ© de donnĂ©es rĂ©side dans la recherche dâĂ©vĂšnements extrĂȘmes. En effet, il est possible dâobserver des Ă©vĂšnements extrĂȘmes Ă partir des donnĂ©es chimiques de niveau 2 (L2), câest-Ă -dire les concentrations de gaz mais lâinversion nâest gĂ©nĂ©ralement possible que pour des conditions de ciel clair. De plus il est difficile de rechercher ces Ă©vĂšnements Ă partir des donnĂ©es L2 et de les caractĂ©riser en temps rĂ©el. Ce travail de thĂšse rĂ©pond Ă la nĂ©cessitĂ© de mettre en place un algorithme de dĂ©tection innovant et opĂ©rationnel afin de traiter directement les spectres de radiances (donnĂ©es de niveau 1 â L1C). Une mĂ©thode optimisĂ©e pour la dĂ©tection dâĂ©vĂšnements extrĂȘmes a Ă©tĂ© dĂ©veloppĂ©e Ă partir de la mĂ©thode dâanalyse en composantes principales (ACP ou en anglais PCA pour principal component analysis) sur les luminances IASI qui permet Ă la fois la compression des donnĂ©es mais aussi la rĂ©duction du bruit instrumental. Cette mĂ©thode repose sur la crĂ©ation dâune base dâapprentissage reprĂ©sentative de la variabilitĂ© atmosphĂ©rique permettant alors de conserver toute lâinformation lors de la compression/reconstruction des luminances IASI. Les Ă©vĂšnements extrĂȘmes sortant de la variabilitĂ© atmosphĂ©rique normale sont caractĂ©risĂ©s par une mauvaise reconstruction. En prenant en compte les valeurs extrĂȘmes issues de la mauvaise reconstruction des spectres IASI on peut alors Ă©tudier le signal atmosphĂ©rique anormal. Les donnĂ©es IASI L1C Ă©tant disponibles toutes les 3 minutes sous forme de granule, il est naturel dâappliquer la mĂ©thode directement sur les granules IASI pour permettre une dĂ©tection en temps rĂ©el. De plus, la caractĂ©risation des espĂšces traces absorbantes est rĂ©alisĂ©e Ă partir de diffĂ©rentes combinaisons de raies intenses ou de bandes dâabsorption (appelĂ©s « indicateurs » spectraux) qui ont Ă©tĂ© dĂ©finies Ă partir de simulations de transfert radiatif et de bases de donnĂ©es spectroscopiques. Cette mĂ©thode de dĂ©tection, appelĂ©e IASI-PCA-GE (GE pour granule extrema), permet alors de dĂ©tecter en quasi temps rĂ©el les anomalies atmosphĂ©riques associĂ©es Ă des Ă©vĂšnements extrĂȘmes comme les feux, Ă©ruptions volcaniques ou les Ă©pisodes de pollution anthropique. Une premiĂšre partie de ce travail de thĂšse a consistĂ© Ă analyser diffĂ©rents Ă©vĂ©nements extrĂȘmes passĂ©s et documentĂ©s pendant la pĂ©riode IASI. Ensuite la mĂ©thode IASI-PCA-GE a Ă©tĂ© appliquĂ©e aux donnĂ©es IASI pour des plusieurs cas dâĂ©tude, et les rĂ©sultats ont Ă©tĂ© comparĂ©s avec les donnĂ©es L2 existants. Par ailleurs, une archive dâĂ©vĂ©nements extrĂȘmes dâĂ©ruptions volcaniques et dâĂ©pisodes de feux a Ă©tĂ© gĂ©nĂ©rĂ©e Ă partir des rĂ©sultats de cette mĂ©thode qui a Ă©tĂ© appliquĂ©e Ă la sĂ©rie temporelle IASI-B complĂšte (2013-2022). La mĂ©thode est capable de dĂ©tecter la prĂ©sence de nombreuses molĂ©cules et la comparaison avec les donnĂ©es L2 montre un bon accord entre les deux jeux de donnĂ©es. Cependant certaines limitations subsistent et sont discutĂ©es. La mĂ©thode dĂ©veloppĂ©e pendant cette thĂšse pourra par ailleurs ĂȘtre appliquĂ©e Ă des futures missions, telles que la mission IASI-NG/Metop-SG et la mission gĂ©ostationnaire MTG-IRS dont les lancements sont prĂ©vus en 2024
DĂ©tection des Ă©vĂšnements exceptionnels Ă partir des observations IASI
The IASI (Infrared Atmospheric Sounding Interferometer) instruments aboard the Metop-A, -B and -C satellites have been measuring the infrared radiation (IR) emitted by the Earth-atmosphere system since 2006. Every day, several million spectra are recorded by IASI, which constitutes a large volume of data. One of the problems inherent to this amount of data is the search for extreme events. Indeed, it is possible to observe extreme events from level 2 data (L2), i.e. gas concentrations, but the retrieval is generally only possible under clear sky conditions. Moreover, it is difficult to search for these events from L2 data and to characterize them in real time. This thesis work addresses the need to implement an innovative detection algorithm to directly process the radiance spectra (level 1 data â L1C). An optimized method for the detection of extreme events has been developed from PCA (Principal Component Analysis) on IASI radiances, which allows both the compression of the data but also the reduction of instrumental noise. This method relies on the creation of a training database representative of the atmospheric variability, allowing to keep all the information during the compression/reconstruction of IASI radiances. However, extreme events are outside the normal atmospheric variability and will be ill-reconstructed. By taking into account the extreme values resulting from the ill-reconstructed IASI spectra, we can study the anomalous atmospheric signal. In order to allow a systematic, automatic and accurate analysis allowing the detection and characterization of anomalies, the analysis is performed on sets of radiance spectra observed during 3 min time steps (IASI granule). In addition, the characterization of absorbing trace species is performed using different thresholds and fine spectral indicators defined from radiative transfer simulations and spectroscopic database. This method called IASI-PCA-GE (GE for granule extrema) allows then to detect and characterize in quasi real time the atmospheric anomalies associated with extreme events such as fires, volcanic eruptions or anthropic pollution episodes. A first part of this thesis work consisted in analyzing different past extreme events documented during the IASI period. Then the IASI-PCA-GE method was applied to IASI data for several study cases and the results were compared with existing L2 data. Furthermore, extreme event archives of volcanic eruptions and fire episodes were generated from the results of this method, which was applied to the complete IASI-B time series (2013-2022). The method is able to detect the presence of numerous molecules and the comparison with the L2 data shows a good agreement between the two datasets. However, some limitations remain and are discussed. The method developed during this thesis can also be applied to future missions, such as the IASI-NG/Metop-SG mission and the MTG-IRS geostationary mission, which are scheduled to be launched in 2024.Les instruments IASI (InterfĂ©romĂštre AtmosphĂ©rique de Sondage dans l'Infrarouge) Ă bord des satellites Metop-A, -B et -C mesurent le rayonnement infrarouge (IR) Ă©mis par le systĂšme Terre-atmosphĂšre depuis 2006. Chaque jour plusieurs millions de spectres sont enregistrĂ©s par IASI, ce qui constitue un volume important de donnĂ©es. Une des problĂ©matiques inhĂ©rentes Ă cette quantitĂ© de donnĂ©es rĂ©side dans la recherche dâĂ©vĂšnements extrĂȘmes. En effet, il est possible dâobserver des Ă©vĂšnements extrĂȘmes Ă partir des donnĂ©es chimiques de niveau 2 (L2), câest-Ă -dire les concentrations de gaz mais lâinversion nâest gĂ©nĂ©ralement possible que pour des conditions de ciel clair. De plus il est difficile de rechercher ces Ă©vĂšnements Ă partir des donnĂ©es L2 et de les caractĂ©riser en temps rĂ©el. Ce travail de thĂšse rĂ©pond Ă la nĂ©cessitĂ© de mettre en place un algorithme de dĂ©tection innovant et opĂ©rationnel afin de traiter directement les spectres de radiances (donnĂ©es de niveau 1 â L1C). Une mĂ©thode optimisĂ©e pour la dĂ©tection dâĂ©vĂšnements extrĂȘmes a Ă©tĂ© dĂ©veloppĂ©e Ă partir de la mĂ©thode dâanalyse en composantes principales (ACP ou en anglais PCA pour principal component analysis) sur les luminances IASI qui permet Ă la fois la compression des donnĂ©es mais aussi la rĂ©duction du bruit instrumental. Cette mĂ©thode repose sur la crĂ©ation dâune base dâapprentissage reprĂ©sentative de la variabilitĂ© atmosphĂ©rique permettant alors de conserver toute lâinformation lors de la compression/reconstruction des luminances IASI. Les Ă©vĂšnements extrĂȘmes sortant de la variabilitĂ© atmosphĂ©rique normale sont caractĂ©risĂ©s par une mauvaise reconstruction. En prenant en compte les valeurs extrĂȘmes issues de la mauvaise reconstruction des spectres IASI on peut alors Ă©tudier le signal atmosphĂ©rique anormal. Les donnĂ©es IASI L1C Ă©tant disponibles toutes les 3 minutes sous forme de granule, il est naturel dâappliquer la mĂ©thode directement sur les granules IASI pour permettre une dĂ©tection en temps rĂ©el. De plus, la caractĂ©risation des espĂšces traces absorbantes est rĂ©alisĂ©e Ă partir de diffĂ©rentes combinaisons de raies intenses ou de bandes dâabsorption (appelĂ©s « indicateurs » spectraux) qui ont Ă©tĂ© dĂ©finies Ă partir de simulations de transfert radiatif et de bases de donnĂ©es spectroscopiques. Cette mĂ©thode de dĂ©tection, appelĂ©e IASI-PCA-GE (GE pour granule extrema), permet alors de dĂ©tecter en quasi temps rĂ©el les anomalies atmosphĂ©riques associĂ©es Ă des Ă©vĂšnements extrĂȘmes comme les feux, Ă©ruptions volcaniques ou les Ă©pisodes de pollution anthropique. Une premiĂšre partie de ce travail de thĂšse a consistĂ© Ă analyser diffĂ©rents Ă©vĂ©nements extrĂȘmes passĂ©s et documentĂ©s pendant la pĂ©riode IASI. Ensuite la mĂ©thode IASI-PCA-GE a Ă©tĂ© appliquĂ©e aux donnĂ©es IASI pour des plusieurs cas dâĂ©tude, et les rĂ©sultats ont Ă©tĂ© comparĂ©s avec les donnĂ©es L2 existants. Par ailleurs, une archive dâĂ©vĂ©nements extrĂȘmes dâĂ©ruptions volcaniques et dâĂ©pisodes de feux a Ă©tĂ© gĂ©nĂ©rĂ©e Ă partir des rĂ©sultats de cette mĂ©thode qui a Ă©tĂ© appliquĂ©e Ă la sĂ©rie temporelle IASI-B complĂšte (2013-2022). La mĂ©thode est capable de dĂ©tecter la prĂ©sence de nombreuses molĂ©cules et la comparaison avec les donnĂ©es L2 montre un bon accord entre les deux jeux de donnĂ©es. Cependant certaines limitations subsistent et sont discutĂ©es. La mĂ©thode dĂ©veloppĂ©e pendant cette thĂšse pourra par ailleurs ĂȘtre appliquĂ©e Ă des futures missions, telles que la mission IASI-NG/Metop-SG et la mission gĂ©ostationnaire MTG-IRS dont les lancements sont prĂ©vus en 2024
Detection of exceptional events from IASI observations
Les instruments IASI (InterfĂ©romĂštre AtmosphĂ©rique de Sondage dans l'Infrarouge) Ă bord des satellites Metop-A, -B et -C mesurent le rayonnement infrarouge (IR) Ă©mis par le systĂšme Terre-atmosphĂšre depuis 2006. Chaque jour plusieurs millions de spectres sont enregistrĂ©s par IASI, ce qui constitue un volume important de donnĂ©es. Une des problĂ©matiques inhĂ©rentes Ă cette quantitĂ© de donnĂ©es rĂ©side dans la recherche dâĂ©vĂšnements extrĂȘmes. En effet, il est possible dâobserver des Ă©vĂšnements extrĂȘmes Ă partir des donnĂ©es chimiques de niveau 2 (L2), câest-Ă -dire les concentrations de gaz mais lâinversion nâest gĂ©nĂ©ralement possible que pour des conditions de ciel clair. De plus il est difficile de rechercher ces Ă©vĂšnements Ă partir des donnĂ©es L2 et de les caractĂ©riser en temps rĂ©el. Ce travail de thĂšse rĂ©pond Ă la nĂ©cessitĂ© de mettre en place un algorithme de dĂ©tection innovant et opĂ©rationnel afin de traiter directement les spectres de radiances (donnĂ©es de niveau 1 â L1C). Une mĂ©thode optimisĂ©e pour la dĂ©tection dâĂ©vĂšnements extrĂȘmes a Ă©tĂ© dĂ©veloppĂ©e Ă partir de la mĂ©thode dâanalyse en composantes principales (ACP ou en anglais PCA pour principal component analysis) sur les luminances IASI qui permet Ă la fois la compression des donnĂ©es mais aussi la rĂ©duction du bruit instrumental. Cette mĂ©thode repose sur la crĂ©ation dâune base dâapprentissage reprĂ©sentative de la variabilitĂ© atmosphĂ©rique permettant alors de conserver toute lâinformation lors de la compression/reconstruction des luminances IASI. Les Ă©vĂšnements extrĂȘmes sortant de la variabilitĂ© atmosphĂ©rique normale sont caractĂ©risĂ©s par une mauvaise reconstruction. En prenant en compte les valeurs extrĂȘmes issues de la mauvaise reconstruction des spectres IASI on peut alors Ă©tudier le signal atmosphĂ©rique anormal. Les donnĂ©es IASI L1C Ă©tant disponibles toutes les 3 minutes sous forme de granule, il est naturel dâappliquer la mĂ©thode directement sur les granules IASI pour permettre une dĂ©tection en temps rĂ©el. De plus, la caractĂ©risation des espĂšces traces absorbantes est rĂ©alisĂ©e Ă partir de diffĂ©rentes combinaisons de raies intenses ou de bandes dâabsorption (appelĂ©s « indicateurs » spectraux) qui ont Ă©tĂ© dĂ©finies Ă partir de simulations de transfert radiatif et de bases de donnĂ©es spectroscopiques. Cette mĂ©thode de dĂ©tection, appelĂ©e IASI-PCA-GE (GE pour granule extrema), permet alors de dĂ©tecter en quasi temps rĂ©el les anomalies atmosphĂ©riques associĂ©es Ă des Ă©vĂšnements extrĂȘmes comme les feux, Ă©ruptions volcaniques ou les Ă©pisodes de pollution anthropique. Une premiĂšre partie de ce travail de thĂšse a consistĂ© Ă analyser diffĂ©rents Ă©vĂ©nements extrĂȘmes passĂ©s et documentĂ©s pendant la pĂ©riode IASI. Ensuite la mĂ©thode IASI-PCA-GE a Ă©tĂ© appliquĂ©e aux donnĂ©es IASI pour des plusieurs cas dâĂ©tude, et les rĂ©sultats ont Ă©tĂ© comparĂ©s avec les donnĂ©es L2 existants. Par ailleurs, une archive dâĂ©vĂ©nements extrĂȘmes dâĂ©ruptions volcaniques et dâĂ©pisodes de feux a Ă©tĂ© gĂ©nĂ©rĂ©e Ă partir des rĂ©sultats de cette mĂ©thode qui a Ă©tĂ© appliquĂ©e Ă la sĂ©rie temporelle IASI-B complĂšte (2013-2022). La mĂ©thode est capable de dĂ©tecter la prĂ©sence de nombreuses molĂ©cules et la comparaison avec les donnĂ©es L2 montre un bon accord entre les deux jeux de donnĂ©es. Cependant certaines limitations subsistent et sont discutĂ©es. La mĂ©thode dĂ©veloppĂ©e pendant cette thĂšse pourra par ailleurs ĂȘtre appliquĂ©e Ă des futures missions, telles que la mission IASI-NG/Metop-SG et la mission gĂ©ostationnaire MTG-IRS dont les lancements sont prĂ©vus en 2024.The IASI (Infrared Atmospheric Sounding Interferometer) instruments aboard the Metop-A, -B and -C satellites have been measuring the infrared radiation (IR) emitted by the Earth-atmosphere system since 2006. Every day, several million spectra are recorded by IASI, which constitutes a large volume of data. One of the problems inherent to this amount of data is the search for extreme events. Indeed, it is possible to observe extreme events from level 2 data (L2), i.e. gas concentrations, but the retrieval is generally only possible under clear sky conditions. Moreover, it is difficult to search for these events from L2 data and to characterize them in real time. This thesis work addresses the need to implement an innovative detection algorithm to directly process the radiance spectra (level 1 data â L1C). An optimized method for the detection of extreme events has been developed from PCA (Principal Component Analysis) on IASI radiances, which allows both the compression of the data but also the reduction of instrumental noise. This method relies on the creation of a training database representative of the atmospheric variability, allowing to keep all the information during the compression/reconstruction of IASI radiances. However, extreme events are outside the normal atmospheric variability and will be ill-reconstructed. By taking into account the extreme values resulting from the ill-reconstructed IASI spectra, we can study the anomalous atmospheric signal. In order to allow a systematic, automatic and accurate analysis allowing the detection and characterization of anomalies, the analysis is performed on sets of radiance spectra observed during 3 min time steps (IASI granule). In addition, the characterization of absorbing trace species is performed using different thresholds and fine spectral indicators defined from radiative transfer simulations and spectroscopic database. This method called IASI-PCA-GE (GE for granule extrema) allows then to detect and characterize in quasi real time the atmospheric anomalies associated with extreme events such as fires, volcanic eruptions or anthropic pollution episodes. A first part of this thesis work consisted in analyzing different past extreme events documented during the IASI period. Then the IASI-PCA-GE method was applied to IASI data for several study cases and the results were compared with existing L2 data. Furthermore, extreme event archives of volcanic eruptions and fire episodes were generated from the results of this method, which was applied to the complete IASI-B time series (2013-2022). The method is able to detect the presence of numerous molecules and the comparison with the L2 data shows a good agreement between the two datasets. However, some limitations remain and are discussed. The method developed during this thesis can also be applied to future missions, such as the IASI-NG/Metop-SG mission and the MTG-IRS geostationary mission, which are scheduled to be launched in 2024
Soil and Aboveground Carbon Stocks in a Planted Tropical Mangrove Forest (Can Gio, Vietnam)
International audienceCan Gio mangrove is the largest mangrove forest in Vietnam, covering approximately 35,000 hectares. This forest was partially destroyed during the war, and restored between the late 1970s and the early 1990s. Currently, the Can Gio mangrove forest regenerates naturally, and presents a specific species zonation along the intertidal elevation gradient with Rhizophora apiculata trees dominating the inner forest, and Avicennia alba trees colonizing riverbanks at lower elevation. Mangroves are considered as having a key role in climate change mitigation, because of their capacity to store large quantities of carbon. Along with climate and tree species, the position in the intertidal zone affects mangrove carbon storage capacity. The objectives of this study were to determine the aboveground biomass, the quality and the quantity of the organic matter (OM) stored beneath each mangrove zone, as well as the soil physicochemical characteristics, that may influence soil OM. C stocks in the aboveground biomass increased landward, from 24.3 ± 5.1 Mg C/ha in the fringe A. alba zone to 118.8 ± 9.5 Mg C/ha in the R. apiculata zone. The specific zonation resulted in soil physicochemical gradients, with higher carbon content, lower pH, and lower redox values, from the mudflat to the inner forest. In addition, Ύ 13 C values and C/N ratio suggested a higher contribution of mangrove-derived OM in the inner forest compared to the fringe forest. Soil carbon stocks in the R. apiculata forest, down to one meter, represented almost three times the stock in the aboveground biomass. However, when considering only the upper soil, down to 40 cm depth, which was related to forest plantation as evidenced by Ύ 13 C values and C/N ratios, stocks in the soil and in the aboveground biomass were similar, and the carbon burial rate was lower than 1 Mg C/ha/yr
What IASI can tell about the exceptional Hunga Tonga eruption
info:eu-repo/semantics/nonPublishe
Principal Component Analysis of IASI measurements for the detection of extreme events: methodology and application to the detection of rare spectral signatures
International audienceWe have implemented and tested the feasibility and performances of a systematic and global processing of IASI L1 measurements based on the Principal Component Analysis (PCA) of the spectra, for the fast detection, identification and monitoring of atmospheric extreme events
Principal Component Analysis of IASI measurements for the detection of extreme events: methodology and application to the detection of rare spectral signatures
International audienceWe have implemented and tested the feasibility and performances of a systematic and global processing of IASI L1 measurements based on the Principal Component Analysis (PCA) of the spectra, for the fast detection, identification and monitoring of atmospheric extreme events
Mannitol protects hair cells against tumor necrosis factor α-induced loss
Mannitol has otoprotective effects against tumor necrosis factor (TNF) α-induced auditory hair cell (HC) loss.
Mannitol has been demonstrated to possess cytoprotective effects in several organ systems. Its protective effect on postischemic hearing loss has also been shown. Mannitol's otoprotective mechanism and site of action are at present unknown.
Organ of Corti (OC) explants were dissected from 3 day-old rat pups. The safety (nonototoxicity) of mannitol was assessed at 4 different concentrations (1-100 mM). Three experimental arms were designed including: a control group, TNFα group, and TNFα + mannitol group. Cell viability was determined by counts of fluorescein isothiocyanate (FITC) phalloidin stained HC. Immunofluorescence assay of phospho-c-Jun and the proapoptotic mediators, cleaved caspase-3, apoptosis inducing factor (AIF), and endonuclease G (Endo G) were performed.
Analysis of HC density confirmed the safety of mannitol at concentration ranges of 1 to 100 mM. The ototoxic effect of TNFα was demonstrated (p < 0.05). The otoprotective effect of 100 mM mannitol in TNFα-challenged OC explants was also demonstrated (p < 0.001). Mannitol treatment reduced the high levels of phospho-c-Jun observed in the TNFα-challenged group. AIF cluster formation and EndoG translocation into the nuclei of HCs were also reduced by mannitol treatment.
Mannitol significantly reduces the ototoxic effects of TNFα against auditory HC's potentially by inhibiting c-Jun N terminal kinase (JNK) activation pathway and AIF, EndoG nuclear translocation. This local otoprotective effect may have therapeutic implications in inner ear surgery, for example, cochlear implants, protection of residual hearing, as well as implications for postischemic inner ear insults