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Où vont nos vêtements ? À propos de : Emmanuelle Durand, L’envers des fripes. Les vêtements dans les plis de la mondialisation, Premier Parallèle
No full textMaximal elements in the Hurwitz graph
No full textThe Hurwitz graph has for vertices maximal chains in the lattice of non-crossing partitions, with an edge between two chains which differ at exactly one place. Adin and Roichman introduced an order on this graph by choosing a base element and showed that the maximal elements are counted by the Catalan numbers. We show that this set of maximal elements is connected in the Hurwitz graph and is in natural bijection with non-crossing partitions, so that the graph structure corresponds to that of the permutahedron, restricted to non-crossing partitions
The Anthropocene as Age
No full textInternational audienceReintroduced in a short article entitled "Geology of Mankind" (Nature, 2002), the term "Anthropocene" is much debated, far from unanimous among geologists and stratigraphers. It is a vertigo-inducing term, equating terrestrial metamorphoses with a new geological epoch shaped by humans. The chrono-stratigraphical dispute surrounding the Anthropocene gets even more controversial when it comes to looking not just at the causes, but at the human reasons for global change. The term itself opens up a whole field of representations whose emergence and significance need to be scrutinized like a semantic kaleidoscope of the many faces it covers, making it impossible to grasp it from a single perspective. Among the epistemological challenges of the Anthropocene is the question of time, with which history and historians have a close and complex relationship. What does the prism of Anthropocene do to history as a science of time. In addition to being the story of the "awareness" or "unawareness" of a latent movement whose long trace is both anterior and posterior (whatever the position and duration of reference), the Anthropocene is that of a "moment" of retrospective reading of a process whose unfolding "we" did not simultaneously think. In other words, it's a long duration (dilation) of a historical time that would enable to understand the point at which we are, set against the precipitation (compression) of a historical present that requires us to branch off. These anthropological upheavals affect our own research, its objects, positions and epistemologies. In particular, the history of urbanism as an ecology of inhabitation
L’adaptation des logements au changement climatique. Une équation impossible ?
No full textNational audienceIn France, with 11% of emissions in 2021, the building sector is the fourth largest producer of greenhouse gases (GHGs, behind transport, agriculture and industry). Logically, this sector is particularly targeted by a succession of regulations and laws aimed at combating global warming and the loss of biodiversity. They concern first of all the thermal regulations adopted since forty years (RT 1979, 1988, 2000, 2012, 2020 [Environmental Regulation]) aiming at both the quality and the life cycle of new dwellings (from the extraction of materials for their construction, their construction, their life until their destruction) and the reduction of «thermal strainers». These are combined, within a legislative framework, with the obligation to carry out energy performance diagnostics ("DPE", 2006) of dwellings and buildings. They label their energy quality "from labels ranging from A for the least energy-hungry to F and G for thermal strainers". This chapter examines the effects of these measures on residential building GHGs emissions, design and environment.En France, avec 11% des émissions en 2021, le bâtiment représente le quatrième secteur le plus émetteur de gaz à effet de serre (GES, derrière le transport, l’agriculture et l’industrie). Logiquement, ce secteur est particulièrement ciblé par une succession de réglementations et de lois ayant pour objectif de lutter contre le réchauffement climatique et la perte de la biodiversité. Elles concernent tout d’abord les réglementations thermiques adoptées depuis une quarantaine d’années (RT 1979, 1988, 2000, 2012, 2020 [Réglementation Environnementale]) visant à la fois la qualité et le cycle de vie des logements neufs (de l’extraction des matériaux pour leur construction, leur mise en chantier, leur vie en œuvre jusqu’à leur destruction) et la réduction des « passoires thermiques ». A celles-ci se cumulent, dans un cadre législatif, l’obligation de réaliser des diagnostics de performance énergétique (DPE, 2006) des logements et des bâtiments. Ils labélisent leur qualité énergétique à partir d’étiquettes allant de A pour les moins énergivores à F et G pour les passoires thermiques. Ce chapitre interroge les effets de ces mesures sur les émissions de GES des bâtiments résidentiels, leur conception et leur environnement
Minimizing the carbon footprint of 3D printing concrete: Leveraging parametric LCA and neural networks through multiobjective optimization
No full textInternational audienceConcrete 3D printing proposes an off-site industrial process allowing to deposit material only where required. However, most mixture design methods struggle to perform, which is why a majority of 3D printing materials display high clinker contents. This study proposes a reproducible methodology for tailor-made 3D printing materials. Applied to a low-clinker quaternary blend, an iterative optimization process leads to a significant reduction of labor in material tuning. It involves life cycle assessment and artificial neural networks as objective functions in the Pareto selection of best-performing solutions. Following the constitution of an 18-mixture database with 6 independent variables and 5 objective functions, printable mortars of different strength classes are designed within 2 to 4 active learning runs. Consequently, this optimum-driven technique allows to rapidly converge toward low-carbon solutions for 3D printing, using local materials and custom characterization procedures
Toward more robust net primary production projections in the North Atlantic Ocean
No full textInternational audiencePhytoplankton plays a crucial role in both climate regulation and marine biodiversity, yet it faces escalating threats due to climate change. Understanding future changes in phytoplankton biomass and productivity under climate change requires the utilization of Earth system models capable of resolving marine biogeochemistry. These models often differ significantly from one another, and most studies typically use the average response across an ensemble of models as the most reliable projection. However, in the North Atlantic, this straightforward method falls short of providing robust projections of phytoplankton net primary production (NPP) over the 21st century. A new inter-comparison approach was therefore developed and applied to eight models from the sixth phase of the Coupled Model Intercomparison Project (CMIP6) exhibiting substantial divergence in their NPP projections in the North Atlantic. The basin was first divided into three bioregions tailored to the characteristics of each model using a novel method based on a clustering procedure. The mechanisms controlling NPP projections were then identified in each model and in each bioregion, revealing two mechanisms responsible for a large part of model divergence: diazotrophy in the subtropical region and the presence of an ammonium pool in the subpolar region. This allowed for an informed selection of models in each region based on the way they represent these two mechanisms, resulting in reduced projection uncertainty, enhanced total NPP decrease in the subtropical region, and a strengthened increase in small phytoplankton NPP in the subpolar North Atlantic. These model selections enhanced the decreases in carbon export and phytoplankton biomass but had no impact on zooplankton biomass. This innovative approach has strong synergies with other widely used inter-comparison techniques, such as emergent constraints, and their combination would provide valuable insights into the future trajectory of the Earth's climate syste
Measurements of He-collision-induced line-shape parameters of CO2 lines in the ν3 band
No full textInternational audienceHe-collision-induced line-shape parameters of CO2 lines were measured in the 3 band using Fourier transform spectra recorded at room temperature and with pressures ranging from 263 mbar to 1106 mbar. The measured transmission spectra were analyzed with the Voigt profile combined with the first-order line-mixing approximation, accounting for the instrument lineshape function. The He-broadening coefficients, pressure shifts, and first-order line-mixing parameters were determined for 51 lines, from the P(50) to the R(51). The obtained Hebroadening coefficients are in excellent agreement with various literature values. These broadening coefficients, together with data for higher J lines, extrapolated from available hightemperature measurements, allowed us to propose an improved dataset for He-broadening coefficients of CO2 lines. We demonstrated that accounting for line-mixing effects is essential to accurately determine the pressure shifts. The latter, measured for the first time for the 3 band, exhibited a weak rotational dependence, in contrast to the strong dependence observed for air-and self-pressure shifts for CO2. The obtained line-mixing coefficients agree well with those calculated using the Energy Corrected Sudden model. The results of this study significantly enhance the line-shape parameters dataset for CO2 perturbed by He, providing improved data for spectroscopic databases and for studies of planetary and exoplanetary atmospheres
Is OSSO a Significant Contributor to the Unknown UV Absorber in Venus' Atmosphere?
No full textInternational audienceIt has been proposed that two isomers of the SO dimer (cis-and trans-OSSO) are candidates for the unknown UV absorber in Venus' atmosphere because they have a good spectral match with the absorber, despite the low concentrations predicted by 1D photochemical models. Here OSSO chemistry (production from SO and loss by photolysis, thermal decomposition, and reaction with O and Cl) has been included in the photochemistry scheme of a 3D planetary climate model (PCM-Venus) along with sulfur injection due to meteoric ablation. 1D multiple scattering radiative transfer modeling is then used to predict the resulting top-ofthe-atmosphere reflectance produced by OSSO. The modeled OSSO concentrations are shown to be ∼3 orders of magnitude too low to explain the observed absorbance levels, and the predicted ratio of the OSSO isomers provides an unsatisfactory match to the spectral shape of the unknown absorber
The Percolation of Knowledge across Space
No full textInternational audienceThis paper shows that the negative effect of geographical distance on knowledge flows stems from how firms gain sources of knowledge through their existing network. We start by documenting two stylized facts. First, in aggregate, the distance elasticity of patent citations flows is sizable and has remained constant since the 1980s, despite the rise of the internet. Second, at the micro level, firms’ network of knowledge sources expands through existing knowledge sources. We introduce a framework featuring the latter phenomenon, and generating a negative distance elasticity in aggregate. The model predicts Pareto-distributed innovator sizes, and citation distances increasing with innovator size. These predictions hold well empirically. We investigate changes of the underlying parameters and geographical composition effects over the period. While the distance effect should have decreased with constant country composition, the rise of East Asian economies, associated to large distance elasticities, compensated lower frictions in other countries
Moving open repositories out of the blind spot of initiatives to correct the scholarly record
No full textInternational audienceOpen repositories were created to enhance access and visibility of scholarly publications, driven by open science ideals emphasizing transparency and accessibility. However, they lack mechanisms to update the status of corrected or retracted publications, posing a threat to the integrity of the scholarly record. To explore the scope of the problem, a manually verified corpus was examined: we extracted all the entries in the Crossref x Retraction Watch database for which the publication date of the corrected or retracted document ranged from 2013 to 2023. This corresponded to 24,430 entries with a DOI, which we use to query Unpaywall and identify their possible indexing in HAL, an open repository (second largest institutional repository worldwide). In most cases (91%), HAL does not mention corrections.While the study needs broader scope, it highlights the necessity of improving the role of open repositories in correction processes with better curation practices. We discuss how harvesting operations and the interoperability of platforms can maintain the integrity of the entire scholarly record. Not only will the open repositories avoid damaging its reliability through ambiguous reporting, but on the contrary, they will also strengthen it