CELLS v1.0 : updated and parallelized version of an electrical scheme to simulate multiple electrified clouds and flashes over large domains.

International audienceThe paper describes the fully parallelized electrical scheme CELLS which is suitable to simulate explicitly electrified storm systems on parallel computers. Our motivation here is to show that a cloud electricity scheme can be developed for use on large grids with complex terrain. Large computational domains are needed to perform real case meteorological simulations with many independent convective cells. The scheme computes the bulk electric charge attached to each cloud particle and hydrometeor. Positive and negative ions are also taken into account. Several parametrizations of the dominant non-inductive charging process are included and an inductive charging process as well. The electric field is obtained by inverting the Gauss equation with an extension to terrain-following coordinates. The new feature concerns the lightning flash scheme which is a simplified version of an older detailed sequential scheme. Flashes are composed of a bidirectional leader phase (vertical extension from the triggering point) and a phase obeying a fractal law (with horizontal extension on electrically charged zones). The originality of the scheme lies in the way the branching phase is treated to get a parallel code. The complete electrification scheme is tested for the 10 July 1996 STERAO case and for the 21 July 1998 EULINOX case. Flash characteristics are analysed in detail and additional sensitivity experiments are performed for the STERAO case. Although the simulations were run for flat terrain conditions, they show that the model behaves well on multiprocessor computers. This opens a wide area of application for this electrical scheme with the next objective of running real meterological case on large domains

Activité électrique et variations d'intensité des systèmes convectifs tropicaux dans le sud-ouest de l'océan Indien (observations et modélisation)

Depuis une vingtaine d'années, la qualité de la prévision de la trajectoire des cyclones tropicaux a fortement progressé mais peu d'améliorations ont été apportées à la prévision de l'intensité. Cette thèse s'intéresse aux changements d'intensité des cyclones tropicaux du sud-ouest de l'océan Indien sous l'angle original de l'activité électrique.Une première étude climatologique s'appuyant sur les données du réseau de détection d'éclairs World Wide Lightning Location Network (WWLLN) a permis de valider la qualité de ces données et de montrer que les cyclones tropicaux pouvaient être une source importante de production d'éclairs à l'échelle du bassin. À partir de ce résultat, une étude ciblée a été menée en considérant la spécificité du bassin et trois régions ont été définis (océan ouvert, région à proximité de la côte est de Madagascar et Canal du Mozambique). L'activité électrique des cyclones tropicaux dépend de la région où ils se trouvent ainsi que de leur stade d'intensité. Les éclairs semblent être un marqueur des phases d'intensification et d'affaiblissement dans certains situations. La troisième étape de cette thèse a consisté à simuler de manière idéalisée un cyclone tropical mature et a tenté d'expliquer les processus physiques à l'origine de l'activité électrique. Le modèle reproduit bien le comportement sporadique des éclairs habituellement observé. Des bilans montrent que ce cyclone présente trois phases caractéristiques, chacune associée à un comportement dynamique, microphysique et électrique différent. Enfin, une deuxième étude purement numérique a tenté d'identifier des estimateurs de l'activité électrique. Pourcelà deux approches ont été adoptées : une étude globale et une étude par cellule. Dans les deux cas, les meilleurs estimateurs sont la masse totale de graupel, le volume d'updraft et le produit des flux des masses de glace précipitante et non précipitante.Tropical cyclone track forecast has improved over the past two decades but little improvement have been done in intensity changes forecast. This thesis focuses on the intensity changes of tropical cyclones in the southwest Indian ocean through the original aspect of lightning activity. A climatology of lightning activity in the southwest Indian ocean using data from the World Wide Lightning Location Network (WWLLN) is first proposed. Results showed that the WWLLN was able to locate and capture the lightning activity in the basin and that tropical cyclones can be considered as a major source of lightning flashes in some oceanic parts of this region. From this result, study of lightning activity in tropical cyclones of the southwest Indian ocean has been done considering the basin configuration. Thus, three regions were defined: open ocean, region near the eastern coast of Madagascar and the Mozambique Channel. The location and intensity of lightning activity depend on the region and the intensity stage. Lightning flashes seem to be a proxy of intensification or weakening under some conditions. The third step of this thesis was to simulate in an idealized framework a mature tropical cyclone. The model was first able to reproduce the sporadic behavior of lightning activity as observed. Budgets have shown that the presence of three distinctive phases characterized by different dynamical, microphysical and electrical behaviors. Finally, another purely numerical work tried to identify some proxies of lightning activity according two approaches : a global analysis anda per-cell analysis. In both cases, the best proxies are the total graupel mass, the updraft volume and the product of precipitating and non-precipitating ice mass fluxes.SAINT DENIS/REUNION-Droit Lettre (974112101) / SudocSudocFranceF

LE CONSEIL AGRICOLE AU CARREFOUR DU DEVELOPPEMENT SECTORIEL ET DU DEVELOPPEMENT TERRITORIAL :ACCOMPAGNER L'ACTIVITE AGRICOLE EN SITUATIONE

N° ISBN - 978-2-7380-1284-5International audienceThis paper provides a framework to analyse the undergoing changes in agricultural and rural development. As a result of these changes, agricultural extension is faced with the challenge of standing at the crossroads between sector development and territorial development, which is the issue analysed here. This paper contributes to a new conceptualization of agricultural activity, reaching beyond its technical, economic, and productive aspects so as to include cultural and political factors, as well as the spatial and time dimensions related to local and daily life activities. This leads to the establishment of a new approach of agricultural changes and their accompaniment, and of public policy guidelines, which places collective actions, together with their situated dimension, purposes, and knowledge, at the heart of the analysis. The subsequent conceptual framework has being tested in a number of French studies, which first results, reported in Part 2, can be synthesized as three major trends: territorial factors are progressively being integrated in agricultural advice, including in traditional farming sectors; the public and the objects of agricultural extension are diversifying; extension agents need to cooperate with the development agents of non-agricultural sector. All in all, the skills of the extension agents, and their ability to facilitate collective actions, are the most sensitive issues brought about by these new challenges

The role of intermediate cities in Argentinan Pampa in the province of Buenos Aires regarding the structuration of Agrarian areas: an analysis of governance process in three municipalities

La région pampéenne argentine a depuis l’Europe une image de vastes étendues agricoles très faiblement peuplées où se pratiquent l’élevage bovin et les grandes cultures (essentiellement le soja) sur de grandes exploitations. Pourtant, dans la Province de Buenos-Aires, au sud de la capitale, les villes maillent fortement un territoire qui représente près de la moitié de la France. Les périmètres de gestion combinent des villes moyennes ou des petites villes chefs-lieux d’un district (partido) siège du gouvernement local (intendencia) et de l’administration municipale (municipio) avec des villages (pueblos)’. Dans un contexte de forte centralisation du pouvoir, la thématique de la décentralisation est au cœur des débats politiques : les municipalités revendiquent davantage de compétences, mais elles disposent de marges de manœuvre réduites. Pourtant, une analyse détaillée de différentes situations conduit à repérer des modèles de gestion contrastés : d’une part, deux municipios qui se contentent de gérer les affaires courantes en lien direct avec le gouvernement central (Necochea et Villarino). D’autre part, un municipio acteur du développement territorial qui essaie de construire un projet de territoire (Tandil). En appui à ces processus de développement territorial, deux systèmes, l’un à dimension sociale et l’autre à dimension économique, ont un rôle essentiel dans la recherche de solutions aux lourdes problématiques économiques et sociales que connaît le pays.The Argentinan Pampa has an image of vast and expanded fields structured around large farms of cereals production or breeding units. However, in the Province of Buenos Aires, around the south of the capital, the urban network structures an area of the size of nearly half of France. These areas are managed around medium-sized cities, chief towns of the district (partido) seat of local government (intendancia) and municipal (municipio) with what they call «pueblos». In a context of centralized government, the theme of decentralization is at the heart of the political debate: Municipalities ask for more responsibilities but they have very low budget. But a detailed analysis of different situations illustrates patterns of a contrasting management: First municipios who merely deal with the affairs directly related to the central government (Necochea et Villarino). On the other hand, we can observe a municipio which acts as a main character of local development (Tandil). In this perspective, they try to build a regional project by supporting two systems: One with a social dimension and another one around economic dimension to resolve serious social and economic problems.Facultad de Ciencias Agrarias y Forestale

Table ronde : la matérialité des collections : formes d’archives et de pratiques

Éléonore Kissel, Philippe Peltier, Christine Barthe et Christophe Moulherat © musée du quai Branly - Jacques Chirac, photo Cyril Zannettacci Mme Éléonore KISSEL Le musée du quai Branly a fait un choix tout à fait fondamental de constituer un pôle comportant trois secteurs d’activité, la conservation préventive, les analyses et la conservation-restauration, ce qui nous permet d’avoir une approche très structurée de la préservation. Cette table ronde sera centrée sur un aspect spécifique de la..

The role of intermediate cities in Argentinan Pampa in the province of Buenos Aires regarding the structuration of Agrarian areas: an analysis of governance process in three municipalities

La région pampéenne argentine a depuis l’Europe une image de vastes étendues agricoles très faiblement peuplées où se pratiquent l’élevage bovin et les grandes cultures (essentiellement le soja) sur de grandes exploitations. Pourtant, dans la Province de Buenos-Aires, au sud de la capitale, les villes maillent fortement un territoire qui représente près de la moitié de la France. Les périmètres de gestion combinent des villes moyennes ou des petites villes chefs-lieux d’un district (partido) siège du gouvernement local (intendencia) et de l’administration municipale (municipio) avec des villages (pueblos)’. Dans un contexte de forte centralisation du pouvoir, la thématique de la décentralisation est au cœur des débats politiques : les municipalités revendiquent davantage de compétences, mais elles disposent de marges de manœuvre réduites. Pourtant, une analyse détaillée de différentes situations conduit à repérer des modèles de gestion contrastés : d’une part, deux municipios qui se contentent de gérer les affaires courantes en lien direct avec le gouvernement central (Necochea et Villarino). D’autre part, un municipio acteur du développement territorial qui essaie de construire un projet de territoire (Tandil). En appui à ces processus de développement territorial, deux systèmes, l’un à dimension sociale et l’autre à dimension économique, ont un rôle essentiel dans la recherche de solutions aux lourdes problématiques économiques et sociales que connaît le pays.The Argentinan Pampa has an image of vast and expanded fields structured around large farms of cereals production or breeding units. However, in the Province of Buenos Aires, around the south of the capital, the urban network structures an area of the size of nearly half of France. These areas are managed around medium-sized cities, chief towns of the district (partido) seat of local government (intendancia) and municipal (municipio) with what they call «pueblos». In a context of centralized government, the theme of decentralization is at the heart of the political debate: Municipalities ask for more responsibilities but they have very low budget. But a detailed analysis of different situations illustrates patterns of a contrasting management: First municipios who merely deal with the affairs directly related to the central government (Necochea et Villarino). On the other hand, we can observe a municipio which acts as a main character of local development (Tandil). In this perspective, they try to build a regional project by supporting two systems: One with a social dimension and another one around economic dimension to resolve serious social and economic problems.Facultad de Ciencias Agrarias y Forestale

High-assurance zeroization

In this paper we revisit the problem of erasing sensitive data from memory and registers during return from a cryptographic routine. While the problem and related attacker model is fairly easy to phrase, it turns out to be surprisingly hard to guarantee security in this model when implementing cryptography in common languages such as C/C++ or Rust. We revisit the issues surrounding zeroization and then present a principled solution in the sense that it guarantees that sensitive data is erased and it clearly defines when this happens. We implement our solution as extension to the formally verified Jasmin compiler and extend the correctness proof of the compiler to cover zeroization. We show that the approach seamlessly integrates with state-of-the-art protections against microarchitectural attacks by integrating zeroization into Libjade, a cryptographic library written in Jasmin with systematic protections against timing and Spectre-v1 attacks. We present benchmarks showing that in many cases the overhead of zeroization is barely measurable and that it stays below 2% except for highly optimized symmetric crypto routines on short inputs

Formally verifying Kyber Episode IV: Implementation Correctness

In this paper we present the first formally verified implementations of Kyber and, to the best of our knowledge, the first such implementations of any post-quantum cryptosystem. We give a (readable) formal specification of Kyber in the EasyCrypt proof assistant, which is syntactically very close to the pseudocode description of the scheme as given in the most recent version of the NIST submission. We present high-assurance open-source implementations of Kyber written in the Jasmin language, along with machine-checked proofs that they are functionally correct with respect to the EasyCrypt specification. We describe a number of improvements to the EasyCrypt and Jasmin frameworks that were needed for this implementation and verification effort, and we present detailed benchmarks of our implementations, showing that our code achieves performance close to existing hand-optimized implementations in C and assembly

Lightning activity in tropical cyclones in the South-West Indian Ocean

International audienc