Rapport intermédiaire

Les acteurs de la filière céréale wallonne sont actuellement confrontés à une série de modifications comprenant notamment : l’évolution de la législation, l’arrivée en fin de validité des permis d’environnement ou d’exploiter d’une série de sites de stockage, l’augmentation des volumes stockés au sein de ces sites, l’urbanisation à proximité de ceux-ci…. Ces éléments pourraient impliquer la fermeture de certains sites de stockage. Simultanément, la localisation de nouveaux sites de stockage est confrontée à des défis tels que la croissance du phénomène NIMBY, l’entrée en vigueur du Code de Développement Territorial (CoDT) et la protection du paysage. Pourtant, traditionnellement, la production céréalière occupe une place importante dans la production agricole belge. Cette filière s’est développée au cours du temps au point de faire de la Belgique un leader européen dans la production de céréales. Afin de concentrer une production initialement dispersée dans l’espace, des infrastructures de stockage sont nécessaires pour le développement de la filière. Ces espaces de stockage sont d’autant plus importants pour la filière que les demandes en céréales portent sur de grands volumes. Le calendrier agronomique et les conditions météorologiques impliquent une proximité entre les sites de collecte de céréales et les zones de production. Ce besoin de sites de stockage de proximité avec des volumes importants a entrainé la mutualisation de ressources entre agriculteurs et donné naissance aux coopératives agricoles spécialisées dans ce stockage. Ces organismes coexistent avec des négociants qui remplissent le même rôle. En s’adaptant au développement de la filière, ces entreprises se sont diversifiées et ont accru leurs capacités de stockage. Nombre d’entre elles fournissent maintenant des engrais ou des produits phytosanitaires, réalisent des activités de transforma-tion… Elles sont devenues des acteurs clés de la filière à l’interface entre les agriculteurs et le monde agro-industriel (localisés respectivement en amont et en aval de la production de céréales). Ces évolutions doivent être confrontées aux objectifs politiques décrits dans le Code Wallon de l’Agriculture (CWA) et du CoDT. Le CWA prévoit que les politiques agricoles wallonnes doivent « encourager et soutenir la structuration des agriculteurs afin de renforcer leur pouvoir de négociation au sein des filières et d'obtenir une meilleure appropriation par les agriculteurs de la valeur ajoutée aux produits agricoles » et « favoriser l'autonomie des agriculteurs et des exploitations agricoles, individuellement ou collectivement, en termes de production, de transformation et de commercialisation, en ce compris en favorisant le modèle coopératif ». En parallèle, le CoDT a pour objectif « d’assurer un développement durable et attractif du territoire ». Il décrit aussi les objectifs régionaux suivants : « la lutte contre l’étalement urbain et l’utilisation rationnelle des territoires et des ressources », « le développement socio-économique et de l’attractivité territoriale », « la gestion qualitative du cadre de vie » et « la maîtrise de la mobilité ». Dans ce contexte, et pour assurer l’atteinte des objectifs des deux codes précités, il est nécessaire d’: • objectiver les risques et les nuisances causés par l’activité de stockage de céréales ; • objectiver les besoins en sites de stockage ; • identifier des zones autorisant ce type d’activité à proximité des zones de production ; • identifier les critères de localisation optimale des sites de stockage de céréales. La recherche est donc composée de deux parties. La première partie, plus exploratoire, réalise un examen de la filière, ainsi que des conditions administratives et pratiques liées aux sites de stockage de céréales, afin de déboucher sur une liste de critères et types de localisation envisageables. La deuxième partie recensera les sites qui risquent de ne plus pouvoir être exploités, testera, dans ces zones, les critères et conditions mis en évidence dans la première partie et aboutira à une méthodologie applicable à toutes les zones. Ce rapport intermédiaire présente l’état d’avancement de la première partie, ainsi que les résultats préliminaires du workshop, qui réalise l’articulation entre les deux parties de la recherche. Le rapport est structuré en six chapitres. Les cinq premiers chapitres présentent les avancements réalisés dans les cinq phases de la première partie. Le premier chapitre décrit la structuration de la filière céréalière wallonne ainsi que les activités de stockage et leurs nuisances. Le deuxième chapitre éclaire la position des différents acteurs par rapport à la problématique étudiée. Le chapitre 3 décortique les conditions administratives influençant la localisation des sites de stockage de céréales. Le chapitre 4 décrit la localisation des cultures céréalières en Wallonie et, donc, le besoin en sites de stockage. Le chapitre 5 caractérise les sites de stockage de céréales présents dans les données en notre possession. Il décrit donc l’offre en stockage de céréales. Le sixième chapitre présente la manière dont a été réalisé le workshop et ses premiers résultats.Localisation des zones pouvant accueillir des activités agro-économiques de proximit

Instability zones for satellites of asteroids. The example of the (87) Sylvia system

We study the stability of the (87) Sylvia system and of the neighborhood of its two satellites. We use numerical integrations considering the non-sphericity of Sylvia, as well as the mutual perturbation of the satellites and the solar perturbation. Two numerical models have been used, which describe respectively the short and long-term evolution of the system. We show that the actual system is in a deeply stable zone, but surrounded by both fast and secular chaotic regions due to resonances. We then investigate how tidal and BYORP effects modify the location of the system over time with respect to the instability zones. Finally, we briefly generalize this study to other known triple systems and to satellites of asteroids in general, and discuss about their distance from mean-motion and evection resonances.Comment: 25 pages, 11 figures. Submitted to Icaru

A resource-based game theoretical approach for the paradox of the plankton

PRAC and VM are partially supported by the Brazilian research agencies CNPq. PRAC received financial support from Fundação de Amparo à Ciência e Tecnologia do Estado de Pernambuco (FACEPE) Proj. No. APQ-0464-1.05/15. FFF is supported by Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Proj. No. 2013/18942-2. WH received funding from Cancer Research UK (No. TBYG1P5R) and the Max Planck Society. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Laser-Induced Electron Diffraction in Chiral Molecules

Strong laser pulses enable probing molecules with their own electrons. The oscillating electric field tears electrons off a molecule, accelerates them, and drives them back toward their parent ion within a few femtoseconds. The electrons are then diffracted by the molecular potential, encoding its structure and dynamics with angstrom and attosecond resolutions. Using elliptically polarized laser pulses, we show that laser-induced electron diffraction is sensitive to the chirality of the target. The field selectively ionizes molecules of a given orientation and drives the electrons along different sets of trajectories, leading them to recollide from different directions. Depending on the handedness of the molecule, the electrons are preferentially diffracted forward or backward along the light propagation axis. This asymmetry, reaching several percent, can be reversed for electrons recolliding from two ends of the molecule. The chiral sensitivity of laser-induced electron diffraction opens a new path to resolve ultrafast chiral dynamics

How to Quantify the Temporal Storage Effect Using Simulations Instead of Math

The storage effect, originally a theoretical hypothesis to explain how ecologically similar species could coexist by responding differently to environmental variability (Chesson & Warner, 1981; Shmida & Ellner, 1984), has developed into a core concept in community ecology (Mittelbach 2012)with empirical support from communities of prairie grasses (Adler et al., 2006), desert annual plants (Pake & Venable, 1995; Angert et al., 2009), tropical trees (Usinowicz et al., 2012) and zooplankton(Caceres, 1997). An essential step in this maturation was mathematical analysis (Chesson, 1994, 2000a) that identified the conditions required for the storage effect to help stabilize coexistence of competitors. For the temporal storage effect, the focus of this paper, those conditions include (1)species-specific responses to environmental variability, (2) density-dependent covariance between environment and competition, and (3) buffered population growth

Vaccine breakthrough hypoxemic COVID-19 pneumonia in patients with auto-Abs neutralizing type I IFNs

Life-threatening `breakthrough' cases of critical COVID-19 are attributed to poor or waning antibody response to the SARS- CoV-2 vaccine in individuals already at risk. Pre-existing autoantibodies (auto-Abs) neutralizing type I IFNs underlie at least 15% of critical COVID-19 pneumonia cases in unvaccinated individuals; however, their contribution to hypoxemic breakthrough cases in vaccinated people remains unknown. Here, we studied a cohort of 48 individuals ( age 20-86 years) who received 2 doses of an mRNA vaccine and developed a breakthrough infection with hypoxemic COVID-19 pneumonia 2 weeks to 4 months later. Antibody levels to the vaccine, neutralization of the virus, and auto- Abs to type I IFNs were measured in the plasma. Forty-two individuals had no known deficiency of B cell immunity and a normal antibody response to the vaccine. Among them, ten (24%) had auto-Abs neutralizing type I IFNs (aged 43-86 years). Eight of these ten patients had auto-Abs neutralizing both IFN-a2 and IFN-., while two neutralized IFN-omega only. No patient neutralized IFN-ss. Seven neutralized 10 ng/mL of type I IFNs, and three 100 pg/mL only. Seven patients neutralized SARS-CoV-2 D614G and the Delta variant (B.1.617.2) efficiently, while one patient neutralized Delta slightly less efficiently. Two of the three patients neutralizing only 100 pg/mL of type I IFNs neutralized both D61G and Delta less efficiently. Despite two mRNA vaccine inoculations and the presence of circulating antibodies capable of neutralizing SARS-CoV-2, auto-Abs neutralizing type I IFNs may underlie a significant proportion of hypoxemic COVID-19 pneumonia cases, highlighting the importance of this particularly vulnerable population

PLoS One

Quantitative analysis of the vascular network anatomy is critical for the understanding of the vasculature structure and function. In this study, we have combined microcomputed tomography (microCT) and computational analysis to provide quantitative three-dimensional geometrical and topological characterization of the normal kidney vasculature, and to investigate how 2 core genes of the Wnt/planar cell polarity, Frizzled4 and Frizzled6, affect vascular network morphogenesis. Experiments were performed on frizzled4 (Fzd4-/-) and frizzled6 (Fzd6-/-) deleted mice and littermate controls (WT) perfused with a contrast medium after euthanasia and exsanguination. The kidneys were scanned with a high-resolution (16 μm) microCT imaging system, followed by 3D reconstruction of the arterial vasculature. Computational treatment includes decomposition of 3D networks based on Diameter-Defined Strahler Order (DDSO). We have calculated quantitative (i) Global scale parameters, such as the volume of the vasculature and its fractal dimension (ii) Structural parameters depending on the DDSO hierarchical levels such as hierarchical ordering, diameter, length and branching angles of the vessel segments, and (iii) Functional parameters such as estimated resistance to blood flow alongside the vascular tree and average density of terminal arterioles. In normal kidneys, fractal dimension was 2.07±0.11 (n = 7), and was significantly lower in Fzd4-/- (1.71±0.04; n = 4), and Fzd6-/- (1.54±0.09; n = 3) kidneys. The DDSO number was 5 in WT and Fzd4-/-, and only 4 in Fzd6-/-. Scaling characteristics such as diameter and length of vessel segments were altered in mutants, whereas bifurcation angles were not different from WT. Fzd4 and Fzd6 deletion increased vessel resistance, calculated using the Hagen-Poiseuille equation, for each DDSO, and decreased the density and the homogeneity of the distal vessel segments. Our results show that our methodology is suitable for 3D quantitative characterization of vascular networks, and that Fzd4 and Fzd6 genes have a deep patterning effect on arterial vessel morphogenesis that may determine its functional efficiency

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/)

COVID-19 symptoms at hospital admission vary with age and sex: results from the ISARIC prospective multinational observational study

Background: The ISARIC prospective multinational observational study is the largest cohort of hospitalized patients with COVID-19. We present relationships of age, sex, and nationality to presenting symptoms. Methods: International, prospective observational study of 60 109 hospitalized symptomatic patients with laboratory-confirmed COVID-19 recruited from 43 countries between 30 January and 3 August 2020. Logistic regression was performed to evaluate relationships of age and sex to published COVID-19 case definitions and the most commonly reported symptoms. Results: ‘Typical’ symptoms of fever (69%), cough (68%) and shortness of breath (66%) were the most commonly reported. 92% of patients experienced at least one of these. Prevalence of typical symptoms was greatest in 30- to 60-year-olds (respectively 80, 79, 69%; at least one 95%). They were reported less frequently in children (≤ 18 years: 69, 48, 23; 85%), older adults (≥ 70 years: 61, 62, 65; 90%), and women (66, 66, 64; 90%; vs. men 71, 70, 67; 93%, each P &lt; 0.001). The most common atypical presentations under 60 years of age were nausea and vomiting and abdominal pain, and over 60 years was confusion. Regression models showed significant differences in symptoms with sex, age and country. Interpretation: This international collaboration has allowed us to report reliable symptom data from the largest cohort of patients admitted to hospital with COVID-19. Adults over 60 and children admitted to hospital with COVID-19 are less likely to present with typical symptoms. Nausea and vomiting are common atypical presentations under 30 years. Confusion is a frequent atypical presentation of COVID-19 in adults over 60 years. Women are less likely to experience typical symptoms than men

Etude et optimisation des performances du calorimètre électromagnétique de l'expérience CMS pour la physique au LHC

The CMS experiment (Compact Muon Solenoid) is one of the two multi-purpose experiments of the proton-proton collider LHC (Large Hadron Collider) currently starting at CERN (Geneva). One of the main goals of CMS is the search for the Higgs boson. Because of the LHC challenging environment, the collaboration have chosen an electromagnetic calorimeter made of about 75000 scintillating lead tungstate crystals P bW O4 , at the same time fast, radiation hard, and extremely precise, especially in the energy range for the Higgs boson search, in the channel where it decays in two photons. The five first chapters of this thesis present the LHC, the CMS detector and notably the electro- magnetic calorimeter (ECAL). The sixth chapter presents a test beam analysis realized in 2004 at CERN with an electron beam of different energies (20-250 GeV) incident on a part (1/36) of the calorimeter barrel called “ supermodule ”. A study of the energy measurement variation within 9 (3×3) and 25 (5×5) crystals matrices as function of the impact position of the initial electron was done to infer a correction method of the energy measured as function of different parameters. This method has improved very significantly the energy resolution of the calorimeter in the test beam configuration. The last chapter of this thesis presents an application of this correction method for the electrons and photons in the full simulation chain of CMS. The energy reconstruction of photons and electrons is more complicated compared to the test beam case, because of an important amount of matter in front of the calorimeter and of the strong magnetic field in the central part of the CMS detector. The photons have a non negligible probability to convert into an electron-positron pair before the calorimeter, while the electrons (and positrons), whose trajectory is bended in the transverse plan, lose energy in the matter and can emit a random number of bremsstrahlung photons. A reconstruction algorithm of the electrons and photons energy has been developed to take into account this issue and to apply the correction method studied in the test beam. This new algorithmic approach for an optimal reconstruction of the electromagnetic particles in the ECAL has been tested with physics events Z 0 → e+ e− , H → Z 0 Z 0 → e+ e− e+ e− et H → γγ, simulated with a LHC luminosity of 1033 cm−2 s−1