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International audience; The attractiveness of the coasts tends to increase their exposure to erosion and marine flooding risks. This exposure is exacerbated by the effects of climate change, in particular sea level rise. To contribute to strategic thinking on the vulnerability of coastal areas, it is essential to develop, share and collectively maintain relevant knowledge on risks. This article will present the thinking behind the setting up of a coastal risks observatory in Brittany, a region located in north-western France. It relies on a conceptual approach to systemic vulnerability based on four components: hazards, assets, management, and social representations. Hazards and assets underpin the notion of risk and tend to increase the vulnerability, management tends to mitigate it, and representations can play a part in increasing or decreasing it depending on the context. To understand and analyze this system of vulnerability, our approach is based on the generation of a set of 62 indicators combined into different types of indices. A web-GIS interface was developed to navigate through and map this system of vulnerability. The difficulties associated with this type of synthetic approach will be discussed, whether they are related to data availability, to the links between scientific research and operational territorial management requirements, or to an understanding of the dynamics of all of the vulnerability components and their interactions. Ultimately, the approach developed has been successful in mobilising scientific and operational stakeholders around the co-construction of a diagnosis of territories with regard to their vulnerability to coastal risks.

International audience; The stratigraphical complex preserved at the site of Menez–Dregan I (Brittany, France) displays an alternating sequence of 17 occupation levels and of 4 marine deposits, between ca. 450 and 150,000 years (stratigraphical units 9a and 3b). The lithic industry retrieved at the site is extremely abundant, with more than 153,000 artefacts over 3 cm in length, as well as millions of knapping debris, and corresponds to a regional facies of the Acheulean, with heavy-duty tools essentially represented by choppers, as well as a few handaxes and cleavers. This paper presents a first synthesis of the data produced for almost 30 years on the site of Menez–Dregan I. The typological study of the entire lithic collection is now complete and allows us to assess the different human occupations that occurred at this site during the Lower Palaeolithic.; Le complexe stratigraphique conservé à Menez-Dregan I (Bretagne, France) présente une alternance de 17 niveaux d’occupation et de 4 dépôts marins, entre environ 450 et 300 000 ans (US 9a et 3b). L’industrie lithique retrouvée sur le site est extrêmement riche (plus de 153 000 artefacts supérieurs à 3 cm de longueur, ainsi que des millions de débris de taille), et correspond à un faciès régional de l’Acheuléen, dont le macro-outillage est essentiellement représenté par des choppers, ainsi que par quelques bifaces et hachereaux. Cet article présente une première synthèse des données produites depuis presque 30 ans sur le site de Menez-Dregan I. L’étude typologique de l’ensemble de la collection lithique est à présent achevée, et permet de faire le point sur les différentes occupations humaines qui se sont succédé sur ce site au cours du Paléolithique inférieur.

This paper addresses the data-driven identification of latent representations of partially observed dynamical systems, i.e., dynamical systems for which some components are never observed, with an emphasis on forecasting applications and long-term asymptotic patterns. Whereas state-of-the-art data-driven approaches rely in general on delay embeddings and linear decompositions of the underlying operators, we introduce a framework based on the data-driven identification of an augmented state-space model using a neural-network-based representation. For a given training dataset, it amounts to jointly reconstructing the latent states and learning an ordinary differential equation representation in this space. Through numerical experiments, we demonstrate the relevance of the proposed framework with respect to state-of-the-art approaches in terms of short-term forecasting errors and long-term behavior. We further discuss how the proposed framework relates to the Koopman operator theory and Takens' embedding theorem., This work was supported by Labex Cominlabs (grant SEACS), Region Bretagne, CNES (grant OSTST-MANATEE), and Microsoft (AI EU Ocean awards) and by MESR, FEDER, Région Bretagne, Conseil Général du Finistère, Brest Métropole, and Institut Mines Télécom in the framework of the VIGISAT program managed by “Groupement Bretagne Télédétection,” CNES (grant OSTST-MANATEE), and ANR (Melody and OceaniX grants). It benefited from HPC and GPU resources from Azure (Microsoft EU Ocean awards) and from GENCI-IDRIS (Grant No. 2020-101030).

16 pages, 12 figures, 2 tables, Knowledge of ocean surface current at high resolutions is crucial for many applications. In addition to the classic satellite altimetry retrieval from sea surface height (SSH), ocean surface currents can be retrieved from sea surface temperature (SST) observations using a transfer function between SST and SSH. Previous works showed the potential of microwave SST observations to reconstruct ocean surface currents using a synergistic approach: an optimal transfer function that combines the phase of SST with the SSH amplitude spectra. This synergistic approach revealed that surface quasi geostrophy (SQG) reconstruction can be enhanced and opened up the possibility to improve spatial resolution of ocean currents retrieved from altimeters observations if infrared SST observations are considered. However, before applying this synergistic approach to satellite observations, we need to analyze and characterize the spectral properties of the transfer function. This spectral characterization of the transfer function allows to exploit the synergy between SST and SSH observations that have different measurement topology and different spatial resolution. Here, we performed a feasibility study using the daily outputs of the operational Mercator global analysis and forecast system at (1/12)° in the western coast of Australia (27–35°S, 107–113°E) spanning from 26 November 2012 to 26 November 2016. Results showed that the mean transfer function in this region presents two well different bands: one characterized by a negative slope slightly steeper (α = −1.2) than the k−1 predicted by the SQG solution for scales smaller than 270 km and another characterized by a plateau for wavelengths larger than 270 km. In addition, the results revealed that the inhomogeneity in dynamics of the flow limits global solutions. Finally, we showed that information contained along the track is enough for a synoptic reconstruction of the flow in this region, which shows the feasibility of applying this methodology to real satellite observations, This work was mainly supported by the ESA Scientific Exploitation of Operational Missions (SEOM) Living Planet Fellowship OCEANUS. This work was also partially supported by public funds (Ministère de l'Education Nationale, de l'Enseignement Supérieur et de la Recherche, FEDER, Région Bretagne, Conseil Général du Finistère, Brest Métropole) and by Institut Mines Télécom, received in the framework of the VIGISAT project managed by “Groupement Bretagne Télédétection” (BreTel). J. I. F. acknowledges the support by the European Space Agency through the GlobCurrent Data User Element project (4000109513/13/I‐LG), by the Convocatoria Programa Estatal de I+D+i Orientada a los Retos de la Sociedad del año 2016 in the framework of COSMO project (CTM2016‐79474‐R) and from Fundación General CSIC (Programa ComFuturo). This study has been conducted using E.U. Copernicus Marine Service Information (Product identifier: GLOBAL_ANALYSIS_FORECAST_PHY_001_024), With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

International audience; This paper describes the synthesis method and implementation in 65-nm CMOS technology of a compact analog phase-shifter (PS) dedicated to 24/28 GHz applications. This PS delivers a phase shift continuously tunable from 0 to 55° and is particularly suited for on-chip or in-package phased-array antenna. The proposed topology, which is based on an all-pass circuit that includes coupled microstrip lines and varactors as tunable components is intrinsically compact and shows an interesting phase-range vs capacitance-variation ratio.

[Departement_IRSTEA]Territoires [TR1_IRSTEA]SEDYVIN; National audience; Les moyens parfois importants qui sont consacrés à la restauration ou à la réhabilitation des zones humides sont à la mesure des enjeux liés à leur conservation tant en termes de biodiversité que de préservation de la ressource en eau et d'atténuation du changement climatique. Néanmoins, une meilleure compréhension du fonctionnement des zones humides et des implications en termes de services écosystémiques est indispensable à l’amélioration des mesures de conservation et de réhabilitation, mais aussi à leur appropriation par les acteurs locaux et à la prise de conscience des enjeux de leur conservation. Ceci passe par le croisement des connaissances tant scientifiques que techniques et surtout par leur diffusion. Ce numéro spécial consacré à la réhabilitation des zones humides, à l’image du colloque « Réparer la Nature ? l’exemple des milieux humides », contribue à cet objectif en illustrant la complexité de ces milieux et la diversité des approches scientifiques et techniques qui leur sont appliqués.

The Iron Age stelae from Cornouaille (Finistère, France) display a great variety of shapes and lithological types. They are monolithic monuments, partly or entirely carved. Their morphology can result from the natural shaping of rock blocks or they may have an architectural form. In the latter case, the stelae are built around an axis. Their volume can be decomposed into three parts : top, shaft and baseplate. The shaft sides may be decorated. In the context of the inventory initiated by the Centre de l’archéologie du Conseil départemental du Finistère, the purpose of this study is to highlight the specific contributions of both petrography and rock structural analysis to the identification of extraction sites of the Cornouaille stelae, as well as to the understanding of shaping and transportation modes. The methodology is based on the comparative study, on macro-and microscopic scales, of both the monuments and the surrounding geological massifs. The latter are parts of the Variscan crystalline basement of Armorica which recorded strain, metamorphism and granitisation about 300 million years ago. Four criteria have been taken into account : 1) comparative analysis of the natural forms (as either erosional features or tectonic fabric) of the rock blocks in the inferred source massifs and the general shapes of the monuments assumed to have been extracted from them ; 2) texture of the rocks (grain size and crystal relations) ; 3) structure of the rocks (isotropic or strained — schistosity plane and lineation — presence of Z-or S-shaped stretched megacryst) ; and 4) mineralogy. Two test-zones have been selected : the Cap Sizun and Concarneau areas. Stela density is very high in the first area, where fifty-six uniformly distributed monoliths were identified. No stela has been found in an archaeological context. In the Concarneau area, with a nearly equal surface, only twenty-eight stelae are recorded. The archaeological context of two of them, adorned with fluting, is well-known. A first result is that the stela location is generally either within or near the boundaries of the massifs having a similar granitic or meta morphic lithology. The Cap Sizun stelae are characterized by a greater petrographic homogeneity than in the other area, up to more than four kilometres from the boundary of the source granitic massif. Another original result has been the demonstration that the Iron Age artisans used natural forms and that the latter result from two contrasted mechanisms : 1) various erosional processes for the small granitic stelae and 2) high tectonic strain for the tall cigar-shaped gneissic stelae. It would thus seem that the Iron Age artisans usually used pre-existing natural morphologies of stones with a view to shaping their monoliths with the least possible effort or for reasons of symbolism. Regarding the four specific stelae in Nizon orthogneiss (Concarneau area), two potential extraction zones have been identified fairly precisely, by mapping various types of highly strained orthogneisses, referred to as ‘ tectonites’ : S/ L-tectonites, dominated by both flattening and stretching (corresponding exactly to one of the gneissic stelae), and L-tectonites that no longer display any flattening plane, but instead a prominent stretching lineation (corresponding to the other three gneissic stelae). One of the two potential extraction sites (Moulin du Chef-du-Bois, La Forêt Fouesnant) includes natural cylinders with 3D-dimensions quite comparable to those of the gneissic stelae. Furthermore, the presence of an unfinished stela to the north of Cap Sizun, a few kilometres away from the northern limit of the source massif, indicates than this monument was probably shaped close to the final erection site rather than near its extraction zone. Thus, it would appear that the Cap Sizun artisans moved rough granitic blocks rather than shaped stelae. Finally, the location of two granitic stelae in the Concarneau area near a ria, away from the assumed granitic massif source, suggests that they were moved using maritime transport for a distance of about six kilometres., Les stèles de l’âge du Fer de Cornouaille (Finistère) montrent une très grande variété de formes et de lithologies. Dans le cadre de l’inventaire initié par le centre départemental de l’Archéologie du conseil départemental du Finistère, l’objectif de cette étude est de préciser les contraintes que peuvent apporter la pétrographie et l’analyse structurale des roches sur l’identification des sites d’extraction des stèles de Cornouaille, ainsi que sur la compréhension des modalités de façonnage et de transport. La méthodologie est basée sur l’étude comparative, macro-et microscopique, des monuments et des principaux massifs géologiques des secteurs géographiques considérés. Ces massifs appartiennent au vieux socle hercynien armoricain, structuré vers 300 millions d’années, et constitué, dans la zone d’étude, par des roches granitiques et métamorphiques. Deux zones tests ont été sélectionnées : les secteurs du cap Sizun et de Concarneau. Notre premier résultat est de montrer que les stèles sont en général localisées dans les limites des massifs de lithologie correspondante ou à quelques kilomètres de leur bordure. Les stèles du cap Sizun se caractérisent par une plus grande homogénéité lithologique que celles de l’autre secteur, et ce jusqu’à une distance qui peut excéder de quatre kilomètres la limite du massif source (granite de la pointe du Raz). Un autre résultat original est la mise en évidence de l’utilisation de formes naturelles par les artisans de l’âge du Fer : diverses morphologies d’érosion pour les petites stèles granitiques des deux secteurs et un débit tectonique «en cigare » pour les stèles hautes gneissiques. Pour le cas très particulier des quatre monuments en gneiss de Nizon du secteur de Concarneau, deux zones d’extraction potentielles ont pu être identifiées avec une bonne précision. Concernant les modalités de transport des monuments, la présence d’une stèle inachevée au nord du cap Sizun, à plusieurs kilomètres de la bordure septentrionale du massif granitique source, indique que ce monolithe n’a vraisemblablement pas été façonné sur son lieu d’extraction, avant transport, mais plutôt près de son lieu d’érection. Il semblerait donc que les artisans du cap Sizun aient pu déplacer les blocs granitiques bruts ou simplement ébauchés plutôt que les monuments finis. Enfin, notre étude permet d’avancer l’hypothèse que deux stèles granitiques du secteur de Concarneau ont été transportées par voie maritime., Caroff Martial, Grall Bertrand, Moysan Marine, Le Gall Bernard, Cherel Anne-Françoise. Aires d’extraction et façonnage des stèles de l’âge du Fer de Cornouaille (Finistère, France) : apports de la pétrographie et de l’analyse structurale des roches. In: Bulletin de la Société préhistorique française, tome 113, n°4, 2016. pp. 765-784.

Copper ingots and foundry waste are very common in metallic dry land hoards of the carp’s tongue sword horizon of the Late Bronze Age IIIb, especially in the Atlantic area (fig. 1). However, they have been systematically under-studied and even under-referenced. After an analysis of the various descriptions over time, this study proposes an accurate typology based on morphological descriptions. The main purpose of this work is to identify different types of copper ingots in order to determine if one or several copper origins could have been used to supply bronze artisans’ workshops at the same time in Western Europe and most particularly in the west of France. In 2009, the number of Late Bronze IIIb hoards known in the west of France was about sixty nine (Boulud & Fily, 2009). Following this inventory, it can be noted that almost all these hoards contained foundry waste or/ and ingots. This configuration is specific to western France, because in the rest of the country hoards are few, for example in the south of France (Guilaine, 1972 ; Gomez de Soto & Milcent, 2000), or they did not contain foundry waste, for example in the north of France (Blanchet, 1984), or only very little, as in Burgundy (Mordant, 2001) or in the Alps (Fischer, 2012). Previous publications clearly show that for several decades these objects were neglected, and that today it is still difficult to have precise information regarding their descriptions. The aim of this paper is to propose a new typology with appropriate terminology, so it could be used for all future studies to describe these objects with a single identification process. This work describes ingots and foundry waste from carp’s tongue sword horizon hoards in historical Brittany (Finistère, Morbihan, Côtes-d’Armor, Ille-et-Vilaine, Loire-Atlantique). Thus, several types of objects are actually described under the old name of “ plano-convex ingots” : on the one hand, bronze foundry waste such as ground flows, crucible castings, and casts of the bottom of ceramic containers which must certainly be an overflow created during the casting of objects ; and on the other hand the plano convex copper ingots which correspond to the imported raw material. Lastly, bronze “ masselottes” have also been considered in the study. They are clearly identified, but the vocabulary used is so diverse that a rigorous terminology is now indispensable. Ground flows have an overall plano-convex profile. The form of these bronze flows depends on the geometry of the cavity in which the metal is flowing. The upper surface is generally smooth but sometimes wrinkled, the lower slightly irregular and moulds the roughness of the ground. There is no porosity (fig. 2). Crucible castings also have a planoconvex profile. The upper surface is smooth as is the lower, which moulds the inner wall of the crucible. These bronze objects also lack porosity (fig. 3). Almost identical casts have been found in Devon (Needham 1980). Casts of the bottom of ceramic containers have an overall plano-convex profile. The upper surface is slightly rough or bumpy. The lower surface is smooth and corresponds to the imprint of the bottom and part of the sides of the ceramic object. These bronze objects have no porosity (fig. 4). ‘ Masselottes’ correspond to the excess metal remaining in the funnel above objects cast in a mould. They are formed by an upper reservoir corresponding to the funnel itself, and by one or several pouring streams (fig. 5). The plano-convex copper ingots generally have a circular or slightly oval shape with an average diameter of twenty centimetres (fig. 6). Porosity can be low but is usually very high. A large number of these ingots are fragmented and some are partially melted (fig. 7). Unlike the previous objects, ingots are not produced in local bronze artisans’ workshops, but are imported from producing areas. Western France has insufficient resources for the manufacture of such a large number of objects. It is very important to describe the ingots because some differences could appear. For example some smaller ingots, maybe from another production area, could exist (fig. 8). It is nevertheless certain that other forms of ingots exist for the same period in France, as shown by the example of the biscuit-shaped ingots from the hoard of Saint-Jean-aux-Bois, Oise. European comparisons show that plano-convex ingots present in large numbers in the west of France have a morphology very strongly resembling that found in England (Roberts & Veysey, 2011). Plano-convex ingots found in Spain are smaller (Gomez Ramos, 1993 ; Montero-Ruiz et al., 2011) while ingot axes are known in the east of the Iberian Peninsula (Renzi, 2010). In conclusion, an accurate description of foundry waste is extremely pertinent for our knowledge of the ancient artisans’ metallurgical technology, especially concerning the size and form of crucibles or the reconstitution of moulds. The description of copper ingots is very important for trying to identify trade routes through Europe. Indeed, metallurgical techniques can present specificities from one production area to another and ingots could be morphologically different, even if only slightly. The comparison of macroscopic aspects of copper ingots found in production areas with those of consumption areas can contribute to discussion about trade and exchange questions., Les lingots de cuivre et les déchets de fonderie sont des objets omniprésents dans les dépôts métalliques terrestres de l’horizon de l’épée à pointe en langue de carpe du Bronze final IIIb (Bronze final atlantique 3), en particulier dans les régions proches de la façade atlantique. Et pourtant, ils ont été systématiquement sous-étudiés et même sous-référencés. Après un passage en revue des différentes descriptions de ces objets depuis un siècle, ce travail propose une typologie fine basée sur leurs descriptions morphologiques. Cette étude s’attache à décrire les lingots et les déchets de fonderie des dépôts de l’horizon de l’épée à pointe en langue de carpe de la Bretagne historique (Finistère, Morbihan, Côtes-d’Armor, Ille-et-Vilaine, Loire-Atlantique). Ainsi, sous l’ancienne dénomination «lingots plano-convexes » , plusieurs types d’objets sont en réalité décrits : d’une part les déchets de fonderie en bronze que sont les coulures sur le sol, les moulages de creusets et les moulages de fond de poterie qui doivent certainement correspondre à des surplus obtenus au moment de la fonte des objets ; et d’autre part les lingots plano-convexes de cuivre qui correspondent à de la matière première importée. Enfin, les masselottes en bronze ont également été considérées. Elles sont parfaitement identifiées, mais le vocabulaire utilisé est si diversifié qu’une reprise rigoureuse de la terminologie s’est avérée indispensable. La description fine des déchets de fonderie est particulièrement pertinente lorsque l’on s’attache à reconstituer les techniques métallurgiques des bronziers de l’époque, notamment la taille et la nature des creusets ou la reconstitution des moules. La description des lingots de cuivre est quant à elle très importante pour tenter de restituer des courants d’échange à travers l’Europe. En effet, les techniques métallurgiques peuvent présenter des spécificités d’une zone de production à une autre et la morphologie des lingots peut subtilement varier. Ainsi, la comparaison des aspects macroscopiques des lingots de cuivre trouvés dans les zones de production et dans celles de consommation, peut apporter des éléments de discussion dans ces problématiques d’échanges., Le Carlier de Veslud Cécile, Edme Laura, Fily Muriel. Lingots et déchets de fonderie dans les dépôts de l’horizon de l’épée à pointe en langue de carpe (Bronze final IIIb) ; proposition de typologie. In: Bulletin de la Société préhistorique française, tome 111, n°3, 2014. pp. 509-522.

International audience; The authors provide here the review of data on the ancient populations and the coastal landscape of Bas-Léon (Finistère), during the 1st millennium BC. The analysis of the abundant results from multidisciplinary approaches can provide indicators of environmental and social developments, suggesting the identification of two clearly distinct phases during the period. This presentation leads to sketch an outline of the chronological, spatial and cultural evolution considering populations and landscapes; beyond certain limits, this synthesis allows proposing a new light on the dynamics and processes still little addressed so far in the region and which could be deepened through new geoarchaeological approaches.; Les auteurs procèdent ici au réexamen des données concernant les peuplements et les paysages du littoral du Bas-Léon (Finistère), au cours du Ier millénaire avant notre ère. L'analyse des abondants résultats issus d'approches multidisciplinaires permet de dégager des indicateurs d'évolutions sociales et environnementales, suggérant la mise en évidence de deux phases nettement différenciées au cours de la période. Cette présentation conduit à esquisser un schéma d'évolution chronologique, spatiale et culturelle des peuplements et des paysages ; au-delà de certaines limites, cette synthèse permet de proposer un nouvel éclairage sur des dynamiques et des processus encore peu abordés jusqu'ici dans la région et susceptibles d'être approfondis à travers de nouvelles démarches géoarchéologiques.