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Étude expérimentale de submersion de protections côtières pour des états de mer combinant houle et clapot
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Formulation stochastique des matériaux standards généralisés
No full textNational audienceCette contribution présente une formulation stochastique du comportement des matériaux dissipatifs dans le cadre des matériaux standards généralisés en présence d’incertitude. Celle-ci se base sur les concepts de la programmation stochastique et du principe variationnel incrémental associé à l’évolution des matériaux standards. On obtient alors des potentiels d’énergie et de dissipation convexes représentant le comportement effectif du matériau du point de vue statistique. Ces potentiels sont ensuite étendus via l’introduction d’une mesure de risque permettant d’obtenir un comportement, soit optimiste, soit pessimiste, pour un niveau de confiance donné
RNA inverse folding can be solved in linear time for structures without isolated stacks or base pairs
No full textInternational audienceInverse folding is a classic instance of negative RNA design which consists of finding a sequence that uniquely folds into a target secondary structure with respect to energy minimization. A breakthrough result of Bonnet et al shows that, even in simple base pairs-based (BP) models, the decision version of a mildly constrained version of inverse folding is NP-hard. In this work, we show that inverse folding can be solved in linear time for every target structure that contains no isolated BP and no isolated stack BP. (i.e. when helices have all sizes more than ).For structures featuring shorter helices, our linear algorithm is no longer guaranteed to produce a solution, but still does so for a large proportion of instances.Our approach introduces a notion of modulo -separability, generalizing a property introduced by Hales et al. Separability is a sufficient condition for the existence of a solution to the inverse folding problem. We show that, for any input secondary structure of length , a modulo -separated sequence can be produced in time anytime such a sequence exists. Meanwhile, we show that any structure such that is either trivially non-designable, or always admits a modulo- separated sequence (). Solution sequences can thus be produced in linear time, and even be uniformly generated within the set of modulo- separable sequences
A data analysis pipeline integrating ion mobility and high-resolution mass spectrometry for non-target screening in environmental studies
No full textInternational audienceNon-target analysis (NTA) based on high-resolution mass spectrometry (HRMS) allows advances in environmental analysis through the identification of unknown contaminants. Recently, ion mobility spectrometry (IMS) coupled to HRMS has gained some interest to obtain an additional separation dimension in addition to gas or liquid chromatography. Nonetheless, the analysis of the high-dimensional data generated by these techniques is often hindered by challenges related to proprietary software, including misalignment, restrictive data formats , and complications in developing customisable analytical workflows. Some efforts are being made to provide open databases, softwares and workflows but they are not always compatible with data acquired with ion mobility and the most commonly used open data format (mzML), produces large files, especially when including ion mobility (several Gb), thus requiring extensive storage space and computing resources. The goal of this study is to develop a pipeline for analysis of HRMS data including ion mobility, based on the advantages of recent open data formats and softwares, and to apply it to the detection of contaminants in complex environmental mixtures.The environmental data used in this study was acquired on a UPLC-IMS-QTOF system (Waters Vion) in Data-Independent Analysis mode (HDMSE). On this system, data can be retrieved from the UNIFI software using an API. Asynchronous HTTP requests were implemented to speed up the retrieval of large binary data streams. The collected data was then converted to tabular data and saved in the Apache Parquet format , an open-source file format providing efficient compression and fast retrieval of column-oriented data, compatible with many programming languages and data analysis packages. This makes it really fast to import and use into different analytical pipelines, e.g. in DEIMoS , a recent Python-based package allowing for efficient processing of multi-dimensional HRMS data, compatible with IMS. It provides efficient algorithms for feature detection, alignment and MS/MS spectral deconvolution. Comparisons were made between the data formats used in this pipeline with other open formats typically obtained with the ProteoWizard(MsConvert) software . The speed of conversion, data retrieval and storage space were evaluated for 10 environmental samples.The developed pipeline and the Parquet format demonstrated superior efficiency in terms of data collection and saving speed compared to other formats. Storage size was also significantly reduced with the Parquet format , with ~100-200 Mo for typical environmental samples, while mzML files reached 5-6 Go. The data filtering (e.g., MS1 vs MS2) and visualization is also easily performed with commonly used packages in the R or Python environments . The DEIMoS package's peak detection and alignment algorithms displayed a significantly faster processing speed than proprietary software. The data processed with the DEIMoS package will be further used with other open-source packages such as patRoon to enable extensive interrogation of a number of spectral libraries. The conversion package (developed in R) will be released on GitHub for public access and use, along with a data visualization application (R Shiny).The pipeline developed in this study allows substantial gains in efficiency in terms of data collection, storage and processing when dealing with large datasets of environmental samples. Current efforts are made on linking the data obtained with this pipeline with other open-source tools and workflows used for NTA of environmental samples (patRoon ). Based on this pipeline, results of contaminants detection in surface waters impacted by urban wet weather discharges will be presented. The processed data will also be used for machine-learning modeling in order to link HRMS signals with the measured ecotoxicity of environmental mixtures
Balloon-borne lidar observations of tropical cirrus cloudsand comparison with CALIOP
No full textInternational audienceKey component of the climate system, tropical cirrus clouds modulate both the Earth’s radiativebudget and the amount of water vapor transported to the stratosphere. The range of optical depth ofsuch clouds pans several orders of magnitude, from thick opaque cirrus detrained from deepconvection to ultra thin ones just below the stratosphere. Although sub-visible cirrus clouds havebeen largely documented from CALIOP space-borne lidar, its detection lower limit is an obstacle toaccurately quantify the tropical cirrus coverage. The microlidar BeCOOL (Balloon-borne Cirrus andconvective overshOOT Lidar) has been designed to tackle this issue. Between October 2021 andJanuary 2022, in the framework of Strateole-2 project, three BeCOOL microlidars have been flownonboard super-pressure balloons in the lower tropical stratosphere (~20 km). Case studies ofcollocated observations with CALIOP, along with statistical comparisons, highlight the very goodagreement between the two lidars and the enhanced sensitivity of BeCOOL to ultra thin clouds. Thishigher sensitivity is achieved thanks to the low speed of the balloons and the small distance to theobserved clouds, which allow to integrate the observations over a longer time. BeCOOL’sobservations reveal the structure and the significant coverage of optically ultra thin clouds undetectedfrom space
Equatorial modons in thermal rotating shallow water model
No full textInternational audienceExact steady eastward-moving vortex-dipole solutions, the equatorial modons, are constructed in the asymptotic limit of low divergence and small temperature variations in the thermal rotating shallow water (TRSW) model on the equatorial beta-plane. This regime is known to be relevant for the tropical atmosphere. The model itself is a generalization, allowing for horizontal temperature gradients, of the classical rotating shallow water model. The asymptotic modons can carry a temperature anomaly and exist also on the inhomogeneous temperature background. The modon configurations are then used to initialize numerical simulations, in order to check whether such coherent structures can exist in the full TRSW model. The results show that this is, indeed, the case. The parameter regimes and limitations on the structure of the temperature anomaly inside, in order for the modons to persist, are established. It is also shown that the modons keep their coherence even while evolving on the background of meridionally inhomogeneous temperature fields, or while interacting with sharp temperature fronts. A general scenario of disaggregation of the modons, if they are out of the stability domain, is exhibited and analysed
Coupled heat transfers resolution by Monte Carlo in urban geometry including direct and diffuse solar irradiations
No full textInternational audienceModelling transient combined heat transfer in complex urban geometry is a key step to predict human exposure or energy consumption and to quantify the effect of climate change mitigation and adaptation measures. A difficulty lies in the possibility for a model to scale up and integrate large and complex urban morphology. We develop a probabilistic approach to solve heat transfers with the Monte Carlo method that is insensitive to the complexity of both the urban geometry and the boundary conditions. The integral formulation that includes random walks for each heat transfer mode is presented and the computation of absorbed solar irradiations at walls with the double randomization technique is detailed. Numerical validations are given through comparisons with deterministic method results for single and two-layer slabs, but also a three-dimensional thermal bridge geometry. The developed probabilistic heat transfer model is then used in a demonstration heat wave scenario where are computed: the outdoor mean radiant temperature showing the influence of trees; and the indoor average wall temperature showing the influence of solar gains through windows
Collateral Damage? How World War One Changed the Way Women Work
No full textDrawing on individual-level data from the 1911 and 1921 population censuses and census-linking techniques, we analyze the consequences of World War I in France on female labor force participation. Our results suggest that in municipalities that experienced greater military death rates, women were more likely to declare an occupation after the war than they did before the war. These effects are driven by women moving out of waged occupations outside the home (and inactivity) into farming activities
Parcours, a modelling pedestrian tool at the station scale using OpenStreetMap
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E.T. the Exceptional Trajectories: Text-to-camera-trajectory generation with character awareness
No full textECCV 2024. Project page: https://www.lix.polytechnique.fr/vista/projects/2024_et_courant/International audienceStories and emotions in movies emerge through the effect of well-thought-out directing decisions, in particular camera placement and movement over time. Crafting compelling camera trajectories remains a complex iterative process, even for skilful artists. To tackle this, in this paper, we propose a dataset called the Exceptional Trajectories (E.T.) with camera trajectories along with character information and textual captions encompassing descriptions of both camera and character. To our knowledge, this is the first dataset of its kind. To show the potential applications of the E.T. dataset, we propose a diffusion-based approach, named DIRECTOR, which generates complex camera trajectories from textual captions that describe the relation and synchronisation between the camera and characters. To ensure robust and accurate evaluations, we train on the E.T. dataset CLaTr, a Contrastive Language-Trajectory embedding for evaluation metrics. We posit that our proposed dataset and method significantly advance the democratization of cinematography, making it more accessible to common users