Oskar Bordeaux
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From Preservation to Transformation: Taphonomic Analysis of Archaeological Insect Remains from the French Atlantic Coastline
No full textInsect remains can provide unique insights into past environments, yet their preservation and post-depositional alterations – particularly chromatic changes – remain poorly understood. Recent excavations along the French Atlantic coastline uncovered numerous archaeological structures dating from the Neolithic to Late Antiquity. Archaeoentomological samples collected from these structures reveal significant variations in the preserved insect remains. The frequency of morphological alterations, degree of fragmentation, and quantity of subfossil insects recovered vary between samples, influenced by the type of archaeological structure, the embedding substrate, the storage methods, and the taxa considered. Chromatic alterations, visible to the naked eye, appeared more uniform. This pilot study initially aimed to determine whether fibre-optic reflectance spectroscopy could detect original colouration no longer visible to the naked eye, by comparing archaeological specimens with modern reference material. Spectral analyses showed colour differences correspond to taphonomic alterations rather than hidden original hues. By documenting these changes and assessing spectroscopy’s applicability to archaeoentomological material, this study establishes a methodological baseline and reference dataset, opening new avenues for insect taphonomy research and improving palaeoenvironmental reconstructions
The production of salt on the Aquitaine coast, an activity closely dependent on its environment
No full textLa côte sableuse aquitaine a été le théâtre d’une importante exploitation du sel marin depuis le Néolithique jusqu’au début de l’Antiquité romaine, à l’instar du reste de la façade Manche-Atlantique française. Les lieux de production se répartissent entre l’estuaire de la Gironde et la côte océanique depuis la pointe de Grave jusqu’à la Dune du Pilat (La Teste-de-Buch). Les indices de cette production ont été identifiés anciennement grâce aux éléments de briquetage découverts en prospection (fragments d’augets, de pilettes de fours, de soles perforées, de parois en terre crue), ainsi qu’aux niveaux rubéfiés qui les accompagnent parfois. Plusieurs opérations archéologiques en cours permettent d’étudier finement les zones de production, leur chronologie, les aménagements et occupations associés, et surtout les conditions environnementales qui ont permis l’implantation des ateliers puis leur abandon.Les plus anciennes traces de production de sel ignigène datent du Néolithique final à la Lagune (La Teste-de-Buch). La production continue à l’âge du Bronze et au Premier âge du Fer à la Dune du Pilat et dans le nord du Médoc (Soulac-sur-Mer). Au Second âge du Fer, plusieurs établissements sauniers sont répertoriés sur huit communes de la rive droite de l’estuaire de la Gironde et la présence de céramique antique interroge sur la continuité éventuelle de l’activité salicole.Deux ateliers ont été quasi intégralement explorés sur la Dune du Pilat (Pr4 et Pr13). Ils ont livré de grandes quantités de fragments de briquetage, des fosses et de vastes zones rubéfiées. Aucun four n’a pour l’instant été découvert sans doute parce que les aires de chauffe étaient peu excavées et de petites dimensions. Cette observation semble confortée par la présence, sur la plage de l’Amélie (Soulac-sur-Mer), de plusieurs petites plaques-foyères incluant des fragments de briquetage associés à des charbons de bois, très rapidement érodées par les marées. Dans l’estuaire, des prospections géophysiques menées sur le site de la Patte d’Oie (Anglade) montrent des anomalies magnétiques qui pourraient indiquer la présence de fours ou de fosses de travail.Les environnements qui ont favorisé l’implantation des sites sont à présent mieux connus. Dans le nord du Médoc et dans l’estuaire de la Gironde, les ateliers se situent dans des marais intertidaux parcourus de multiples chenaux reconnus en prospection pédestres et géophysiques. La divagation de ces chenaux, voire leur envasement, peut expliquer le déplacement des activités au cours du temps. Dans le secteur de la Dune du Pilat et des plages océanes, les observations stratigraphiques montrent que les sites sauniers s’implantent à proximité de dépressions humides. Le développement et l’abandon des activités est corrélé avec l’évolution du milieu qui voit l’alternance de sols forestiers et de phases d’accumulation de sables éoliens.The sandy Aquitaine coast has been the site of significant marine salt exploitation from the Neolithic period to the early Roman Antiquity, similar to the rest of the French Manche-Atlantic coastline. The production sites are distributed between the estuary of the Gironde and the oceanic coast, from the Pointe de Grave to the Dune du Pilat (La Teste-de-Buch). Evidence of this production has been identified in the past through the discovery of briquetage elements during surveys (fragments of salt pans, furnace bricks, perforated soles, and raw earth walls), as well as the reddened layers that sometimes accompany them. Several ongoing archaeological operations allow for a detailed study of the production areas, their chronology, associated structures and occupations, and especially the environmental conditions that enabled the establishment of the workshops and their subsequent abandonment. The earliest traces of ignigenous salt production date back to the final Neolithic period at the Lagune (La Teste-de-Buch). Production continued into the Bronze Age and the Early Iron Age at the Dune du Pilat and in the northern Médoc (Soulac-sur-Mer). In the Second Iron Age, several salt production sites are recorded in eight municipalities on the right bank of the Gironde estuary, and the presence of ancient ceramics raises questions about the potential continuity of salt production activities. Two workshops have been almost entirely explored at the Dune du Pilat (Pr4 and Pr13). They yielded large quantities of briquetage fragments, pits, and extensive reddened areas. No furnace has yet been discovered, likely because the heating areas were minimally excavated and small in size. This observation seems to be supported by the presence of several small hearth plates on the Amélie beach (Soulac-sur-Mer), which include fragments of briquetage associated with charcoal, quickly eroded by the tides. In the estuary, geophysical surveys conducted at the Patte d’Oie site (Anglade) show magnetic anomalies that could indicate the presence of furnaces or working pits. The environments that favored the establishment of the sites are now better understood. In the northern Médoc and the Gironde estuary, the workshops are located in intertidal marshes traversed by multiple channels identified through pedestrian and geophysical surveys. The wandering of these channels, or even their silting, may explain the shifting of activities over time. In the area of the Dune du Pilat and the ocean beaches, stratigraphic observations show that the salt production sites are located near wet depressions. The development and abandonment of activities correlate with the evolution of the environment, which sees the alternation of forest soils and phases of wind-blown sand accumulation
Cirque et vedettariat, du XIXe siècle à nos jours : entre industrialisation et artification
No full textCultiver la capacité de mentalisation : Les effets d'un programme CPS implanté en école primaire
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Lentilles géodésiques pour le THz
Get PDFNous présentons une nouvelle approche pour adapter les lentilles de Luneburg au domaine térahertz (THz) en utilisant des lentilles géodésiques entièrement métalliques, évitant ainsi les limitations dues à la porosité des matériaux diélectriques. Ces lentilles sont composées de deux plaques métalliques courbes, permettant une trajectoire de propagation similaire à une lentille à gradient d'indice. L'étude démontre leur utilisation à 130 GHz pour l'inspection non destructive d'objets courbes, tels que des réservoirs d'hydrogène. Les résultats expérimentaux montrent une bonne capacité à détecter et à localiser des marqueurs métalliques, avec un contraste significatif. Ces développements ouvrent des perspectives pour des systèmes compacts, multi-faisceaux et à faibles pertes, avec des applications potentielles dans divers domaines, notamment spatial.We introduce- a novel method to adapt Luneburg lenses to the terahertz (THz) frequency range by using fully metallic geodesic lenses, thus overcoming limitations caused by porous dielectric materials. These lenses consist of two curved metallic plates, enabling propagation trajectories similar to those in gradient-index lenses. The study demonstrates their use at 130 GHz for non-destructive inspection of curved objects, such as hydrogen tanks. Experimental results illustrate the system's strong capability to detect and localize metallic markers, showing significant contrast. These advancements open opportunities for compact, multi-beam, low-loss THz systems with potential applications in various fields, particularly in space technologies
Targeted design of organic Janus particles for improved photocatalytic hydrogen evolution
Get PDFOrganic bulk heterojunction particles are decorated in a well-controlled way with metals by using light-assisted bipolar electrodeposition to yield Janus particles. Their asymmetric character leads to significantly enhanced photocatalytic hydrogen evolution reaction. The organic particles are first synthesized via miniemulsion, tuning their size by carefully controlling various preparation parameters. Subsequently, the synergistic effect of an electric field and light is explored for the site-selective bipolar electrochemical deposition of different metals (Pt, Au or Pd). Photocatalytic tests reveal that in the case of platinum, the resulting Janus particles significantly outperform particles randomly covered with metal, as well as unmodified particles, showing an increase in hydrogen evolution efficiency by up to 500%. This superior performance is attributed to an enhanced charge carrier separation in the Janus structure, where Pt, confined at one side, facilitates more efficient electron shuttling and transfer. This work constitutes the first study reporting a promising approach for designing novel metal-organic Janus particles to boost photocatalytic hydrogen evolution and opens up new perspectives for optimizing the design of various other hybrid systems for sustainable energy conversion
Excipients risk assessment by risk analysis
No full textLes excipients pharmaceutiques sont les composants majoritaires en volume dans le médicament. Malgré la place primordiale qu’ils occupent dans le médicament, ils ont pendant longtemps été négligés, notamment du point de vue d’exigences réglementaires. Du fait de différentes problématiques de santé liée aux excipients, ils ont vu leur contexte réglementaire évoluer au cours du temps. Ainsi la publication des lignes directrices du 19 mars 2015 vient encadrer leur fabrication et leur distribution en stipulant que des Bonnes pratiques de fabrication appropriées doivent encadrer leur fabrication et leur distribution. Ces lignes directrices ont été le point de départ au développement d’un outil de gestion de risque, une analyse de risque utilisée pour la qualification des excipients et permettant de déterminer les BPF qui doivent leur être appliquéesPharmaceutical excipients are the main component in drug products. Nevertheless, they have been neglected for a while, especially regarding regulatory requirements. After different health issues occurred these past few years related to excipient, the regulatory context evolved over time. Thus, the publication of Mars 19th, 2015 guidelines provide a framework for the manufacturing and distribution of excipients. They stipulate that appropriate good manufacturing practices must be applied. These guidelines were the starting point for the development of a risk management tool, a risk analysis used for the assessment of excipients and to determine the GMP to be applied to them
Deciphering the singularity of autophagic membranes: key lipids in autophagy
No full textAutophagy is an intracellular mechanism that enables eukaryotes to respond adaptively to environmental stress by promoting degradation and recycling of cell components. This process relies on intense membrane remodeling events, including the de novo formation of specialized membrane vesicles called autophagosome, which engulf and deliver cargo to the lytic vacuole. In recent years, a few studies have supported the critical role of certain lipids in the autophagic machinery; yet, the exact nature and function of the various lipids involved in autophagosome formation remains largely unexplored in plants. To provide insight into the molecular signature of autophagic membranes in Arabidopsis thaliana, our group has established a method combining purification of autophagic structures with proteomic and lipidomic analysis. This work has enabled us to reveal the singularity of the lipid composition of autophagosomes compared to other membrane compartments, and to identify candidate lipid species currently undergoing in-depth functional analysis to determine their role in membrane remodeling events taking place during autophagy