Food for All: A Challenge for the 21st Century

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L'Alimentation pour tous: un défi pour le 21eme siecle

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Phase-resolved XMM-Newton observations of the massive post-RLOF system HD 149404

peer reviewedContext. We investigated the X-ray emission of HD 149404, a 9.81-day period O-star binary in a post-Roche lobe overflow evolutionary stage. X-ray emission of O-star binaries consists of the intrinsic emission of the individual O stars and a putative additional component arising from the wind-wind interaction. Aims. Phase-locked variations in the X-ray spectra can be used to probe the properties of the stellar winds of such systems. Methods. XMM–Newton observations of HD 149404 collected at two conjunction phases and a quadrature phase were analysed. X-ray spectra were extracted and flux variations as a function of orbital phase were inferred. The flux ratios were analysed with models considering various origins for the X-ray emission. Results. The highest and lowest X-ray fluxes are observed at conjunction phases respectively with the primary and secondary star in front. The flux variations are nearly grey with only marginal energy dependence. None of the models accounting for photoelectric absorption by homogeneous stellar winds perfectly reproduces the observed variations. Whilst the overall X-ray luminosity is consistent with a pure intrinsic emission, the best formal agreement with the observed variations is obtained with a model assuming pure windwind collision X-ray emission. Conclusions. The lack of significant energy-dependence of the opacity most likely hints at the presence of optically thick clumps in the winds of HD149404

Automation of Ice Fractures and Calving Events Monitoring Using Medical Imaging Ridge Detection Algorithms

Ice shelves, i.e. the floating extension of the AIS, are playing an active role in controlling ice loss from the Antarctic ice sheet. Laterally constraint in embayment or by ice rises, they are participating as regulators of the ice discharge, by exerting a back stress to the ice flow. When losing mass, these ice shelves lose their gatekeeper property, with potential local destabilization of the AIS. Losing mass from calving is a sophisticated process that is rarely coupled with observations in ice sheet models. However, calving and damages are visible in SAR remote sensing products. In this study, we built the hypothesis that state-of-the-heart ridge detection techniques from the medical imaging field can be transposed to the cryosphere field. Looking at the local Hessian matrix in SAR acquisitions, we analyzed the eigenvectors that indicate the presence of ridges. Over ice shelves, these edges correspond to the calving front of the ice shelf, or crevasses. Using time series, we can monitor the evolution of crack propagation and calving events. Results over Pine Island Glacier and the Brunt Ice Shelf show a precise delineation of calving events, as well as the damaged areas. These encouraging results support the idea of the integration of ice damage detection from SAR remote sensing into ice sheet models

De betalingsbereidheid van de Vlaming voor het behoud van bouwkundig en landschappelijk erfgoed

De betalingsbereidheid van de Vlaming voor het behoud van bouwkundig en landschappelijk erfgoe

Accounting for product recovery potential in building life cycle assessments: a disassembly network-based approach

peer reviewedPurpose Existing life cycle assessment (LCA) methods for buildings often overlook the benefits of product recovery potential, whether for future reuse or repurposing. This oversight arises from the limited scope of such methods, which often ignore the complex interdependencies between building products. The present paper, backed by its supplementary Python library, introduces a method that addresses this gap, emphasizing the influence of product interdependencies and future recovery potential on environmental impact. Methods Implementing the proposed method requires adding a phase, the recovery potential assessment, to the four phases that constitute an LCA according to the ISO 14040/14044 guidelines. Given the disassembly sequence for each product, in the first step of the recovery potential assessment, a disassembly network (DN) is created that displays structural and accessibility dependencies. By calculating the average of the disassembly potential (DP) of each structural dependency (second step) associated with that product, we obtain the DP (0.1–1) at the product level in a third step. Because there is no empirical data available to support a specific relationship between product disassembly potential and recovery potential (RP) (0–1), we employ, in a fourth step, a flexible model specification to represent scenarios of how this relationship may look like. Ultimately, for each scenario, the resulting RP is used to enable a probabilistic material flow analysis with a binary outcome, whether to be recovered or not. The resulting product-level median material flows are then used to quantify the building’s environmental impact for a given impact category in the life cycle impact assessment (LCIA). The results are interpreted through an uncertainty, hotspot, and sensitivity analysis. Results and discussion Our results show that not considering the interdependencies between building products in building LCAs results in underestimating the embodied greenhouse gas (GHG) emissions by up to 28.29%. This discrepancy is primarily attributed to a failure to account for additional material flows stemming from secondary replacements owing to the interdependencies during the life cycle. When accounting for end-of-life recovery benefits, a zero-energy building (ZEB) design incorporating some DfD principles demonstrated up to 45.94% lower embodied GHG emissions than the ZEB design with low disassembly potential when assuming that recovered products will be reused. Conclusions Our approach provides first-of-a-kind evidence that not accounting for recovery potential may significantly distort the results of an LCA for buildings. The method and its supporting code support the semi-automated calculation of the otherwise neglected potential environmental impact, thus helping to drive the transition towards a more sustainable built environment. The supporting code allows researchers to build on the proposed framework if more data on the relationship between DP and RP become available in the future. Finally, while applied to buildings in this paper, the proposed framework is adaptable to any complex product with limited modifications in the supporting code.11. Sustainable cities and communitie

Don d'organes : la volonté d'un choix !

Master [120] en droit, Université catholique de Louvain, 201