Développement et automatisation de méthodes de classification à partir de séries temporelles d'images de télédétection : application aux changements d'occupation des sols et à l'estimation du bilan carbone

La quantité de données de télédétection archivées est de plus en plus importante et grâce aux nouveaux et futurs satellites, ces données offriront une plus grande diversité de caractéristiques : spectrale, temporelle, résolution spatiale et superficie de l'emprise du satellite. Cependant, il n'existe pas de méthode universelle qui maximise la performance des traitements pour tous les types de caractéristiques citées précédemment; chaque méthode ayant ses avantages et ses inconvénients. Les travaux de cette thèse se sont articulés autour de deux grands axes que sont l'amélioration et l'automatisation de la classification d'images de télédétection, dans le but d'obtenir une carte d'occupation des sols la plus fiable possible. En particulier, les travaux ont portés sur la la sélection automatique de données pour la classification supervisée, la fusion automatique d'images issues de classifications supervisées afin de tirer avantage de la complémentarité des données multi-sources et multi-temporelles et la classification automatique basée sur des séries temporelles et spectrales de référence, ce qui permettra la classification de larges zones sans référence spatiale. Les méthodes ont été testées et validées sur un panel de données très variées de : capteurs : optique (Formosat-2, Spot 2/4/5, Landsat 5/7, Worldview-2, Pleiades) et radar (Radarsat,Terrasar-X), résolutions spatiales : de haute à très haute résolution (de 30 mètres à 0.5 mètre), répétitivités temporelles (jusqu'à 46 images par an) et zones d'étude : agricoles (Toulouse, Marne), montagneuses (Pyrénées), arides (Maroc, Algérie). Deux applications majeures ont été possibles grâce à ces nouveaux outils : l'obtention d'un bilan carbone à partir des rotations culturales obtenues sur plusieurs années et la cartographie de la trame verte (espaces écologiques) dans le but d'étudier l'impact du choix du capteur sur la détection de ces élémentsAs acquisition technology progresses, remote sensing data contains an ever increasing amount of information. Future projects in remote sensing like Copernicus will give a high temporal repeatability of acquisitions and will cover large geographical areas. As part of the Copernicus project, Sentinel-2 combines a large swath, frequent revisit (5 days), and systematic acquisition of all land surfaces at high-spatial resolution and with a large number of spectral bands.The context of my research activities has involved the automation and improvement of classification processes for land use and land cover mapping in application with new satellite characteristics. This research has been focused on four main axes: selection of the input data for the classification processes, improvement of classification systems with introduction of ancillary data, fusion of multi-sensors, multi-temporal and multi-spectral classification image results and classification without ground truth data. These new methodologies have been validated on a wide range of images available: various sensors (optical: Landsat 5/7, Worldview-2, Formosat-2, Spot 2/4/5, Pleiades; and radar: Radarsat, Terrasar-X), various spatial resolutions (30 meters to 0.5 meters), various time repeatability (up to 46 images per year) and various geographical areas (agricultural area in Toulouse, France, Pyrenean mountains and arid areas in Morocco and Algeria). These methodologies are applicable to a wide range of thematic applications like Land Cover mapping, carbon flux estimation and greenbelt mappin

Migration distance from birthplace and its association with relative income and employment share among heterosexual couples in Switzerland

Among heterosexual couples, employment of the female partner may suffer from household migration often driven by the job of the male partner. Most research has traditionally focused on the distance moved after couple formation and has neglected how far partners live from their birthplaces. Recent life course research has shown that staying in, leaving or returning to the place of origin of one or both partners often reflects couples’ work-family arrangements. This study contributes to this literature by examining the division of employment between partners and their relative contribution to household income according to migration distances. We analyse data from a national sample of economically active individuals living with heterosexual partners in Switzerland. When controlling for selectivity of migrant couples, the analysis confirms that long-distance household migration benefits men’s relative earnings. Among couples who migrated within the same region, employment is more equally shared between partners than among other couples, including non-migrant couples. The relative distance to birthplaces also matters. Women’s contribution to household income is higher among couples in which men migrated close to women’s birthplace and is lower among couples where women migrated close to men’s birthplace compared to women in other couples. This study suggests that future research on household migration should consider important social ties and places beyond the ‘last family move’ and the mechanisms by which these ties and places influence couples’ decisions about where to live together and economic outcomes

La stratigraphie isotopique du Strontium est-elle une méthode fiable pour dater les plates-formes carbonatées à la transition du Barrémien à l'Aptien ? Révision de cas d'études en Téthys occidentale.

Strontium-isotope measurements on Lower Cretaceous marine rocks derive from belemnite material sampled in ammonite-constrained basinal successions. A group of values with a narrow range across the Barremian/Aptian boundary does not allow the separation of the uppermost Barremian (Martelites sarasini ammonite zone) from the lower Aptian pro parte (Deshayesites oglanlensis-D. forbesi ammonite zones). Growing numbers of studies applied Sr-Isotope Stratigraphy (SIS) on Barremian-Aptian shallow-marine sequences (Urgonian facies) in order to solve controversial results obtained by using different shallow-water biological time markers. Based on re-examination of case studies, we conclude that Sr-isotope values can neither be used to prove nor to disprove the location of the putative Barremian/Aptian boundary based on biostratigraphy. Pending more data available, SIS should be used with caution for dating ammonite-free carbonate sediments in the corresponding time interval.Les mesures de l'isotope du Strontium dans des roches carbonatées marines du Crétacé inférieur proviennent de restes de bélemnites récoltés dans des séries de bassins datées directement par ammonites. Autour de la limite Barrémien/Aptien, une gamme étroite de valeurs du Strontium ne permet pas de distinguer le Barrémien supérieur (Zone d'ammonite à Martelites sarasini) de l'Aptien inférieur pro parte (zones d'ammonite à Deshayesites oglanlensis et D. forbesi). Pourtant, l’application de la Stratigraphie Isotopique du Strontium (SIS) sur des séquences marines carbonatées barrémo–aptiennes (à faciès urgonien) apparaît dans un nombre croissant d’études, essentiellement afin de résoudre les datations souvent controversées des marqueurs biologiques d’environnements peu profonds. La révision de ces cas d'étude montre que l’utilisation des valeurs de l'isotope du Strontium n’est pas un outil fiable pour prouver ou réfuter la localisation de la limite Barrémien/Aptien telle que déduite par la biostratigraphie. Dans l'attente de données complémentaires, la SIS doit être utilisée avec précaution pour dater des séries carbonatées non datées directement par ammonites dans l'intervalle de temps concerné

CHARACTERIZATION OF PAST METALLURGICAL RESIDUES USING GEOPHYSICAL IMAGING: A CASE STUDY OF DUFERCO SITE (BELGIUM)

Ancient metallurgical industries produced large amounts of residues which were typically deposited in heaps or tailing ponds. They were derived from mineral processing and metallurgical treatments that were not as efficient as the extraction processes used nowadays. On one hand, metallurgical wastes could represent a potential source of pollution, being an environmental and sanitary threat even centuries after the end of industrial activities. On the other hand, these residues may still contain valuable ferrous materials, non-ferrous metals and other elements considered as critical raw materials. In this regard, remediation strategies can be improved by integrating the valorization of metallurgical residues and potential resource recovery. To this purpose, it is crucial to have in-depth information about the composition of the metallurgical waste, and spatial information to identify and quantify volumes of these residues. Geophysical methods represent suitable non-invasive technologies for subsurface site characterization, imaging lateral and vertical variations in the physical properties of geological environments including anthropogenic deposits. Complemented with ground truth data from excavations, geophysical imagery can be quantitatively interpreted in terms of material(s) composition and zonation, volume(s) estimation, etc. In this contribution, we present the results of an integrated geophysical investigation carried out in a slag heap of the former iron and steel factory of Duferco, located in Belgium. First, we carried out a geophysical survey in the field with a 3D Electrical Resistivity Tomography (ERT) and Induced Polarization (IP) acquisition. Based on these results, we designed a targeted sampling, i.e., excavation and collection of samples at different locations and depths. In the laboratory, we measured ERT and IP in the samples and compared them with elemental chemical analyses. We investigated correlations between the laboratory data and identified different types of slags or ‘categories’, i.e., slags richer in Fe, Ca and Si. Then we used a probabilistic approach to classify or predict the categories in the whole domain of field acquisition (where no samples are available). To this aim we used the ERT and IP field data co-located with the samples and the elevation at which these samples were taken. Overall, the combination of geophysical measurements in the field, targeted sampling, geophysical measurements in the laboratory and correlations with chemical analyses, may be promising to quantify the metallic content or materials of interest with a discriminating geophysical signature.NWE-Regenerati

Map Style Formalization: Rendering Techniques Extension for Cartography

International audienceCartographic design requires controllable methods and tools to produce maps that are adapted to users' needs and preferences. The formalized rules and constraints for cartographic representation come mainly from the conceptual framework of graphic semiology. Most current Geographical Information Systems (GIS) rely on the Styled Layer Descriptor and Semiology Encoding (SLD/SE) specifications which provide an XML schema describing the styling rules to be applied on geographic data to draw a map. Although this formalism is relevant for most usages in cartography, it fails to describe complex cartographic and artistic styles. In order to overcome these limitations, we propose an extension of the existing SLD/SE specifications to manage extended map stylizations, by the means of controllable expressive methods. Inspired by artistic and cartographic sources (Cassini maps, mountain maps, artistic movements, etc.), we propose to integrate into our system three main expressive methods: linear stylization, patch-based region filling and vector texture generation. We demonstrate how our pipeline allows to personalize map rendering with expressive methods in several examples

Effect of Hydrocortisone on Mortality and Organ Support in Patients With Severe COVID-19: The REMAP-CAP COVID-19 Corticosteroid Domain Randomized Clinical Trial.

Importance: Evidence regarding corticosteroid use for severe coronavirus disease 2019 (COVID-19) is limited. Objective: To determine whether hydrocortisone improves outcome for patients with severe COVID-19. Design, Setting, and Participants: An ongoing adaptive platform trial testing multiple interventions within multiple therapeutic domains, for example, antiviral agents, corticosteroids, or immunoglobulin. Between March 9 and June 17, 2020, 614 adult patients with suspected or confirmed COVID-19 were enrolled and randomized within at least 1 domain following admission to an intensive care unit (ICU) for respiratory or cardiovascular organ support at 121 sites in 8 countries. Of these, 403 were randomized to open-label interventions within the corticosteroid domain. The domain was halted after results from another trial were released. Follow-up ended August 12, 2020. Interventions: The corticosteroid domain randomized participants to a fixed 7-day course of intravenous hydrocortisone (50 mg or 100 mg every 6 hours) (n = 143), a shock-dependent course (50 mg every 6 hours when shock was clinically evident) (n = 152), or no hydrocortisone (n = 108). Main Outcomes and Measures: The primary end point was organ support-free days (days alive and free of ICU-based respiratory or cardiovascular support) within 21 days, where patients who died were assigned -1 day. The primary analysis was a bayesian cumulative logistic model that included all patients enrolled with severe COVID-19, adjusting for age, sex, site, region, time, assignment to interventions within other domains, and domain and intervention eligibility. Superiority was defined as the posterior probability of an odds ratio greater than 1 (threshold for trial conclusion of superiority >99%). Results: After excluding 19 participants who withdrew consent, there were 384 patients (mean age, 60 years; 29% female) randomized to the fixed-dose (n = 137), shock-dependent (n = 146), and no (n = 101) hydrocortisone groups; 379 (99%) completed the study and were included in the analysis. The mean age for the 3 groups ranged between 59.5 and 60.4 years; most patients were male (range, 70.6%-71.5%); mean body mass index ranged between 29.7 and 30.9; and patients receiving mechanical ventilation ranged between 50.0% and 63.5%. For the fixed-dose, shock-dependent, and no hydrocortisone groups, respectively, the median organ support-free days were 0 (IQR, -1 to 15), 0 (IQR, -1 to 13), and 0 (-1 to 11) days (composed of 30%, 26%, and 33% mortality rates and 11.5, 9.5, and 6 median organ support-free days among survivors). The median adjusted odds ratio and bayesian probability of superiority were 1.43 (95% credible interval, 0.91-2.27) and 93% for fixed-dose hydrocortisone, respectively, and were 1.22 (95% credible interval, 0.76-1.94) and 80% for shock-dependent hydrocortisone compared with no hydrocortisone. Serious adverse events were reported in 4 (3%), 5 (3%), and 1 (1%) patients in the fixed-dose, shock-dependent, and no hydrocortisone groups, respectively. Conclusions and Relevance: Among patients with severe COVID-19, treatment with a 7-day fixed-dose course of hydrocortisone or shock-dependent dosing of hydrocortisone, compared with no hydrocortisone, resulted in 93% and 80% probabilities of superiority with regard to the odds of improvement in organ support-free days within 21 days. However, the trial was stopped early and no treatment strategy met prespecified criteria for statistical superiority, precluding definitive conclusions. Trial Registration: ClinicalTrials.gov Identifier: NCT02735707

Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome associated with COVID-19: An Emulated Target Trial Analysis.

RATIONALE: Whether COVID patients may benefit from extracorporeal membrane oxygenation (ECMO) compared with conventional invasive mechanical ventilation (IMV) remains unknown. OBJECTIVES: To estimate the effect of ECMO on 90-Day mortality vs IMV only Methods: Among 4,244 critically ill adult patients with COVID-19 included in a multicenter cohort study, we emulated a target trial comparing the treatment strategies of initiating ECMO vs. no ECMO within 7 days of IMV in patients with severe acute respiratory distress syndrome (PaO2/FiO2 <80 or PaCO2 ≥60 mmHg). We controlled for confounding using a multivariable Cox model based on predefined variables. MAIN RESULTS: 1,235 patients met the full eligibility criteria for the emulated trial, among whom 164 patients initiated ECMO. The ECMO strategy had a higher survival probability at Day-7 from the onset of eligibility criteria (87% vs 83%, risk difference: 4%, 95% CI 0;9%) which decreased during follow-up (survival at Day-90: 63% vs 65%, risk difference: -2%, 95% CI -10;5%). However, ECMO was associated with higher survival when performed in high-volume ECMO centers or in regions where a specific ECMO network organization was set up to handle high demand, and when initiated within the first 4 days of MV and in profoundly hypoxemic patients. CONCLUSIONS: In an emulated trial based on a nationwide COVID-19 cohort, we found differential survival over time of an ECMO compared with a no-ECMO strategy. However, ECMO was consistently associated with better outcomes when performed in high-volume centers and in regions with ECMO capacities specifically organized to handle high demand. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Geovisualisation of animated tides in coastal area with an OpenSource OpenGL platform

International audienceIn this paper, we present a geovisualisation system of coastal area and the animation of tides. We introduce a new methodology with data selection, data stylisation and data rendering, in 2D and 3D on an OpenSource and OpenGL platform. Finally, we discuss about architecture and results