Institut de Recherche sur l'Architecture Antique

Abstract The search for an application of near-term quantum devices is widespread. Quantum machine learning is touted as a potential utilisation of such devices, particularly those out of reach of the simulation capabilities of classical computers. In this work, we study such an application in generative modelling, focussing on a class of quantum circuits known as Born machines. Specifically, we define a subset of this class based on Ising Hamiltonians and show that the circuits encountered during gradient-based training cannot be efficiently sampled from classically up to multiplicative error in the worst case. Our gradient-based training methods use cost functions known as the Sinkhorn divergence and the Stein discrepancy, which have not previously been used in the gradient-based training of quantum circuits, and we also introduce quantum kernels to generative modelling. We show that these methods outperform the previous standard method, which used maximum mean discrepancy (MMD) as a cost function, and achieve this with minimal overhead. Finally, we discuss the ability of the model to learn hard distributions and provide formal definitions for ‘quantum learning supremacy’. We also exemplify the work of this paper by using generative modelling to perform quantum circuit compilation.

Abstract Archaeological objects are exposed to the action of micro‐organisms when they lay in a biologically active environment. The presence of iron sulfides in the corrosion system testifies in most cases that the degradation was influenced by sulfate‐reducing bacteria. Iron sulfides and other iron/sulfur‐containing compounds were detected by micro‐Raman spectroscopy in rust layers of archaeological ferrous objects and in wet wooden fragments contaminated by iron, extracted from ancient wrecks. Although mackinawite (FeS) is very reactive towards oxygen, this phase was observed in each sample. Its crystallisation levels and oxidation states could be differentiated. Greigite (Fe 3 S 4 ) was also identified by means of X‐ray diffraction, used when possible as a complementary analytical tool. Known as the result of the oxidation of mackinawite, greigite was likely to form during the experiments carried out without any protection against air. It was then possible to describe the formation and oxidation processes of iron sulfides in archaeological iron artefacts or in organic materials contaminated by iron. Copyright © 2010 John Wiley & Sons, Ltd.

Gros Pierre. Pour une chronologie des arcs de triomphe de Gaule Narbonnaise (à propos de l'arc de Glanum). In: Gallia, tome 37, fascicule 1, 1979. pp. 55-83.

Abstract Paraloid ® is one of the most frequently used acrylic polymers, employed mainly for its adhesive and consolidating properties in the conservation of a wide range of materials. Appreciated for its reversibility, mechanical characteristics and ease of use, application of the polymer requires it to be simply dissolved in a solvent. Nevertheless, the chemical nature of the relevant solvent must be regarded as an essential parameter, due to its influence on the physico-chemical characteristics of the resulting adhesive film. The aim of this study was to evaluate the effect of the solvents used with Paraloid ® acrylic resin on adhesive film properties, and more specifically on their thermophysical characteristics. Two compounds used in conservation (Paraloid ® B72 and B44) and six solvents (ethanol, acetone, ethyl acetate, ethyl lactate, butyl acetate and toluene) were used to make adhesive film replicates. Thermogravimetry and differential scanning calorimetry (DSC) analyses allowed us to determine the value of the glass transition temperature (Tg) of solvent/Paraloid ® mixtures. Mass monitoring of the films enabled us to correlate Tg values with the quantity of residual solvent. Results showed that all the solvents remained present for a long time in Paraloid ® films when drying took place at room temperature. Moreover, DSC analysis highlighted the fact that residual solvent had a considerable impact on the value of film Tg. In fact, residual solvent significantly lowered the Tg value of Paraloid ® (by up to 30 °C below its theoretical value). This underlined the importance of taking the impact of solvent on resin properties into account.

In the general global rise of attention and research to seek greener attitudes, the field of cultural heritage (CH) makes no exception. In the last decades, an increasing number of sustainable and biologically based solutions have been proposed for the protection and care of artworks. Additionally, the safety of the target artwork and the operator must be kept as core goals. Within this scenario, new products and treatments should be explored and implemented in the common conservation praxes. Therefore, this review addressing metal heritage is aimed to report biologically derived gel formulations already proposed for this specific area as reliable tools for cleaning. Promising bio-gel-based protocols, still to be implemented in metal conservation, are also presented to promote their investigation by stakeholders in metal conservation. After an opening overview on the common practices for cleaning metallic surfaces in CH, the focus will be moved onto the potentialities of gel-alternatives and in particular of ones with a biological origin. In more detail, we displayed water-gels (i.e., hydrogels) and solvent-gels (i.e., organogels) together with particular attention to bio-solvents. The discussion is closed in light of the state-of-the-art and future perspectives.

La première connaissance que nous avons d’un tremblement de terre ayant affecté gravement Pompéi sous le règne de Néron, ne fut pas le fait des découvertes archéologiques ; celles-ci ne firent que confirmer, dès les premières années de fouilles, un événement sur lequel Sénèque et Tacite avaient apporté leur témoignage. C’est au Livre VI de ses Questions naturelles que le premier avec les termes émus d’une narration emphatique, relate la catastrophe : « Pompéi, ville célèbre de la Campanie, de...

National audience

Wet organic archaeological materials extracted from seawater may suffer damage as a result of degradation influenced by micro-organisms. One of the most common phenomena is indirectly induced by sulphate-reducing bacteria (SRB). Due to their metabolic activity in anoxic conditions, SRB generate hydrogen sulphide from sulphate ions present in seawater. When steel items are in contact with organic matter in presence of sulphides, corrosion of the metal leads to the precipitation of Fe(II) sulphides. These phases are responsible for dramatic post-excavation damage: their oxidation during storage or exhibition in museums leads to the formation of voluminous crystals, which may cause cracking and crumbling, and lead to the production of sulphuric acid. In order to characterize Fe(II) sulphides and their by-products, 13 waterlogged samples were analysed by environmental scanning electron microscopy, micro-Raman spectroscopy, and X-ray diffraction. Experiments were performed on untreated wood fragments, on a fragment of rope, and on mineral concretions scratched from the surface of wood remains, all extracted from different shipwrecks. Mackinawite was detected inside the fragments and between the fibres of the rope. Greigite was detected in scattered locations. Pyrite and sulphated phases, like gypsum and iron sulphates, were identified at the surface of the wood fragments and in the mineral concretions.

[es] Al sur de la desembocadura del río Segura, la excavación de La Rábita califal ha revelado la existencia, en el mismo lugar, de un establecimiento de época Orientalizante/Protoibérica e Ibérica Antigua. El hábitat, cuya historia empieza probablemente a finales del siglo VIII o en tomo al 700 a.C., en un momento que se puede fijar hacia el 600 a.C., fue rodeado de una potente muralla que incluye una superficie de 1,5 Ha. El asentamiento ha sido un lugar de intercambios intensos con el mundo orientalizante y fenicio-occidental. [fr] L´établissement orientalisant et ibérique ancien de "La Rábita", Guardamar del Segura (Alicante, Espagne). Campagnes de fouilles, 1996-1998. Au sud de l´embouchure du Segura, la fouille de La Rábita califale a révélé l´existence, au même emplacement, d'un établissement d'époque Orientalisante/Protoibérique et Ibérique Ancienne. L'habitat dont l'histoire commence probablement à la fin du VIIIe siècle ou aux environ de 700 avant J.-C.a été, à un moment que l´on peut situer autour de 600, entouré d'une puissante enceinte; il est alors vaste de 1,5 hectares. L'établissement a été un lieu d'échanges actifs avec le monde orientalisant et phénicien d'Occident.

International audience

We discuss the principles of static analysis by abstract interpretation and report on the automatic verification of the absence of runtime errors in large embedded aerospace software by static analysis based on abstract interpretation. The first industrial applications concerned synchronous control/command software in open loop. Recent advances consider imperfectly synchronous programs, parallel programs, and target code validation as well. Future research directions on abstract interpretation are also discussed in the context of aerospace software.

After a decade rich in giant exoplanet detections, observation techniques have now reached the sensitivity to gain information on the physical structure and chemical content of some of the detected planets and also to find planets of less than 10 M?. The detection and characterization of Earth-like planets is approaching rapidly and dedicated space observatories are already in operation (CoRoT) or in the development phase (Kepler, Darwin and TPF-I/C). In this paper, we explore the domain of terrestrial planets, emphasizing habitable worlds. We discuss the possibility of performing a spectral characterization of their properties using the next generation of astronomical instruments.

Abstract Background Archaeological silver objects from burial sites are of a grey-lavender aspect. The formation of AgCl leads to an increase in the volume of the objects, which may undergo a complete transformation into corrosion products. This degradation process has been little studied to date. In this paper, eight horn silver objects were studied by SEM and XRD. Results Analyses showed a corrosion system composed of bi-layers: a compact inner layer and a porous outer layer. Corrosion products were mainly silver chlorides (AgCl), chlorargyrite. Some objects displayed copper inclusions both in the metallic core and in the inner layer. Highly mineralized objects contained other oxygen-rich phases (with Si, Ca) in the inner layer. Soil markers were detected in the outer layer. Conclusion Based on these results, we put forward a corrosion mechanism for horn silver objects. Silver chloride is formed by the disappearance of the initial silver oxide layer. This AgCl layer is not protective and supports ion transport. Thus an outer layer of silver chloride, incorporating soil markers, is formed.

Diese Bilanz von zwei Jahrzehnten Forschung in Südwestfrankreich soll über die vorhandenen Bestandsaufnahmen deutlich hinausgehen. Ungelöste Fragen sollen neu formuliert und dazu jüngste Erkenntnisse über religiöse Vorstellungen und Praktiken im Rahmen eines umfassenden soziokulturellen Ansatzes ins Blickfeld gerückt werden. Fine ausführliche tour d'horizon der unterschiedlichen Kultstätten läβt die entscheidende Rolle der Territorien erkennen und zeigt, wie die der Siedelgemeinschaften bis zu den ersten kulturellen Veränderungen des 2. Jahrh. v. Chr. allmählich an Bedeutung gewinnt. Im beharrlichen Festhalten an Ahnen- und Heroenverehrung erweist sich für diese Region Galliens vom Beginn der Eisenzeit an deutlich das machtvolle Wirken einer gesellschaftlichen Elite bzw. (ab dem 3. Jahrh. v. Chr.) einer Reiteraristokratie. Infolgedessen ist auch der Volksglaube häufig überformt von den religiösen Ausdrucksformen des Strebens nach Rang und Ansehen. Übersetzt vom Stefan Wirth

Currently gels or dispersions are widely used in the restoration of paintings, graphic arts, stuccoworks and stones, but their use in metal restoration is less widespread. In this study, several gels and dispersions were selected for use in metal treatments. These gels and dispersions have been tested as a support for the treatment solutions usually used for chemical treatments of metals. First, the compatibility of these physical and chemical gels or dispersions with selected treatment solutions was checked. Viscous physical gels (Xanthan gum), collagen-based physical gels (nerve glue), chemical gels (Nanorestore gels®) or dispersions (polyacrylic acid, cellulose-based compound) displayed good compatibility with acid, neutral or basic solutions. Physical peelable gels (Agar or gellan gum) displayed more limited compatibility but were more easily applied on metallic objects. Test treatments were carried out on archaeological objects: silver-plated copper alloy coins. The best post-treatment results in terms of efficiency and the overall aesthetic appearance of the object were obtained with physical peelable gels (Agar or gellan gum) containing a treatment solution (2–5%w of disodium EDTA), applied hot.

Currently gels are widely used in the restoration of paintings, graphic arts, stuccowork and stonework, but their use in metal restoration is less widespread. In this study, several polysaccharide-based hydrogels (agar, gellan and xanthan gum) were selected for use in metal treatments. The use of hydrogels allows to localize a chemical or electrochemical treatment. This paper presents several examples of treatment of metal objects of cultural heritage, i.e., historical or archaeological objects. The advantages, disadvantages and limits of hydrogel treatments are discussed. The best results are obtained for the cleaning of copper alloys via associating an agar gel with a chelating agent (EDTA (ethylenediaminetetraacetic acid) or TAC (tri-ammonium citrate)). The hot application allows to obtain a peelable gel, particularly adapted for historical objects. Electrochemical treatments using hydrogels have been successful for the cleaning of silver and for the dechlorination of ferrous or copper alloys. The use of hydrogels for the cleaning of painted aluminum alloys is possible but it has to be coupled with mechanical cleaning. However, for the cleaning of archaeological lead, the cleaning using hydrogels was not very effective. This paper shows the new possibilities of using hydrogels for the treatment of metal cultural heritage objects: agar is the most promising hydrogel.

Abstract Refinements have been made to the multiple-frequency method for rejecting overlapping echoes when making target-strength measurements with split-beam echosounders described in Demer et al. (1999). The technique requires that echoes, simultaneously detected with two or more adjacent split-beam transducers of different frequencies, pass multiple-target rejection algorithms at each frequency, and characterize virtually identical three-dimensional target coordinates. To translate the coordinates into a common reference system for comparison, the previous method only considered relative transducer positions and assumed that the beam axes of the transducers were parallel. The method was improved by first, optimizing the accuracy and precision of the range and angular measurements of the individual frequency detections; and second, precisely determining acoustically the relative positions and angular orientations of the transducers, thus completely describing the reference-system transformation(s). Algorithms are presented for accurately and precisely estimating the transformation parameters, and efficiently rejecting multiple targets while retaining measurements of most single targets. These improvements are demonstrated through simulations, controlled test-tank experiments, and shipboard measurements using 38- and 120-kHz split-beam transducers. The results indicate that the improved multiple-frequency TS method can reject more than 97% of multiple targets, while allowing 99% of the resolvable single targets to be measured.

International audience

Thanks to the find in Arles of an inscription mentioning the colonia Iulia Augusta Avennio, we can establish that a colony was founded there in the Augustean age, before becoming a roman colony under Hadrian, since the authenticity of CIL, XII, 1120 (Apt) is now beyond doubts. In Plinius' list (NH, III, 36) it is included as a latin colony among the oppida latina. This gives an opportunity to scrutinize the control of the lists gathered by this author, most of which are ordered chronologically for the roman colonies, alphabetically for the latin colonies, according to the sources, and to study the different epigraphical titulatures of the latin colonies : it is possible to distinguish between the Iuliae colonies, dating from before 27 B.C., and the Augustae colonies, dating after this date, and to give them their place in a long cycle of creations which covers several stages from the times of Caesar.

International audience