Beta Irradiation of a Geometrically Metastable Superconducting Strip Detector with a Magnetic Flux Penetration Read-Out

Geometrical metastability, observed in superconducting type I tin flat strips, has been previously proposed as a principle for particle detection. The energy deposition of an incoming beta-particle induces the rupture of the metastability and consequently the penetration of multiquantum flux tubes into a superconducting tin strip. We present here the first absorption spectra from two beta sources, which demonstrate the linearity and energy-resolution of these detectors (presented at the 6th International Workshop on Low Temperature Detectors for Dark Matter and Neutrinos (LTD-6), Interlaken, Switzerland, Sept. 1995)Comment: Compressed PostScript (filename.ps.Z), 8 pages, 2 figure

S-35 Beta Irradiation of a Tin Strip in a State of Superconducting Geometrical Metastability

We report the first energy loss spectrum obtained with a geometrically metastable type I superconducting tin strip irradiated by the beta-emission of S-35. (Nucl. Instr. Meth. A, in press)Comment: Compressed PostScript (filename.ps.Z), 9 pages, 2 figure

Sublogarithmic uniform Boolean proof nets

Using a proofs-as-programs correspondence, Terui was able to compare two models of parallel computation: Boolean circuits and proof nets for multiplicative linear logic. Mogbil et. al. gave a logspace translation allowing us to compare their computational power as uniform complexity classes. This paper presents a novel translation in AC0 and focuses on a simpler restricted notion of uniform Boolean proof nets. We can then encode constant-depth circuits and compare complexity classes below logspace, which were out of reach with the previous translations.Comment: In Proceedings DICE 2011, arXiv:1201.034

Linear Logic by Levels and Bounded Time Complexity

We give a new characterization of elementary and deterministic polynomial time computation in linear logic through the proofs-as-programs correspondence. Girard's seminal results, concerning elementary and light linear logic, achieve this characterization by enforcing a stratification principle on proofs, using the notion of depth in proof nets. Here, we propose a more general form of stratification, based on inducing levels in proof nets by means of indexes, which allows us to extend Girard's systems while keeping the same complexity properties. In particular, it turns out that Girard's systems can be recovered by forcing depth and level to coincide. A consequence of the higher flexibility of levels with respect to depth is the absence of boxes for handling the paragraph modality. We use this fact to propose a variant of our polytime system in which the paragraph modality is only allowed on atoms, and which may thus serve as a basis for developing lambda-calculus type assignment systems with more efficient typing algorithms than existing ones.Comment: 63 pages. To appear in Theoretical Computer Science. This version corrects minor fonts problems from v

Population-specific call order in chimpanzee greeting vocal sequences

This study was funded by the Max Planck Society and the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program awarded to C.C. (grant agreement no. 679787) and ERC (Prilang GA283871) and by Leverhulme Trust Research Leadership Award. Core funding for the Taï Chimpanzee Project has been provided by the Max Planck Society since 1997 and for Budongo Conservation Field station by the Royal Zoological Society of Scotland.Primates rarely learn new vocalisations, but they can learn to use their vocalizations in different contexts. Such ‘vocal usage learning’, particularly in vocal sequences, is a hallmark of human language, but remains understudied in non-human primates. We assess usage learning in four wild chimpanzee communities of Taï and Budongo Forests by investigating population differences in call ordering of a greeting vocal sequence. Whilst in all groups, these sequences consisted of pant-hoots (long-distance contact call) and pant-grunts (short-distance submissive call), the order of the two calls differed across populations. Taï chimpanzees consistently commenced greetings with pant-hoots whereas Budongo chimpanzees started with pant-grunts. We discuss different hypotheses to explain this pattern and conclude that higher intra-group aggression in Budongo may have led to a local pattern of individuals signalling submission first. This highlights how within-species variation in social dynamics may lead to flexibility in call order production, possibly acquired via usage learning.Publisher PDFPeer reviewe

Assessing Hafting Adhesive Efficiency in the Experimental Shooting of Projectile Points: A new Device for Instrumented and Ballistic Experiments

International audienceWith the aim of providing better control of shooting experiments performed with replicas of prehistoric projectiles, we have conducted an instrumental archaeology study on the efficiency of prehistoric projectile points by placing emphasis on their adhesion and ballistic characteristics. In order to avoid any reproducibility problems, hafting adhesives were made with controlled mixtures of commercial rosin (also called ‘colophany’) and beeswax added as a plasticizer. An original experimental device has been developed to instrument a bow, allowing the control of both the trajectories and the velocities of the different shoots. In the course of an experimental programme on Sauveterrian microliths from the Mesolithic period of the South of France, the experimental system was applied to composite replica projectile tips of Mesolithic hunters. Arrows being shot at transparent targets were filmed in order to evaluate the penetration length and residual damage. Interestingly, this study reveals that the properties of the mixture are highly dependent on the velocity of the arrows. It was shown that—contrary to previous experiments that usually used a mixture in which rosin predominates— the most efficient adhesive is made of 70 wt% beeswax with only 30 wt% rosin. This result is of great importance for improving further shooting experiments and overcoming the problems frequently mentioned due to the loss of the flint armatures before they reach the animal target, or at least before penetration. When using this appropriate mixture, the lateral armatures are resistant to most of the shots. Experiments performed on real boars’ flesh have also shown that the presence of lateral microliths allows the laceration inflicted on the target to be enlarged. Finally, a critical parameter has been identified, which is the location on the arrow of the microlithic element

Sodium hydroxide enhances extractability and analysis of proanthocyanidins in ensiled sainfoin (onobrychis viciifolia)

Little information exists on the effects of ensiling on condensed tannins or proanthocyanidins. The acetone–butanol–HCl assay is suitable for measuring proanthocyanidin contents in a wide range of samples, silages included, but provides limited information on proanthocyanidin composition, which is of interest for deciphering the relationships between tannins and their bioactivities in terms of animal nutrition or health. Degradation with benzyl mercaptan (thiolysis) provides information on proanthocyanidin composition, but proanthocyanidins in several sainfoin silages have proved resistant to thiolysis. We now report that a pretreatment step with sodium hydroxide prior to thiolysis was needed to enable their analysis. This alkaline treatment increased their extractability from ensiled sainfoin and facilitated especially the release of larger proanthocyanidins. Ensiling reduced assayable proanthocyanidins by 29%, but the composition of the remaining proanthocyanidins in silage resembled that of the fresh plants

Changes in Feed Proanthocyanidin Profiles during Silage Production and Digestion by Lamb

Proanthocyanidins are plant specialized metabolites which are beneficial to animal nutrition and health. This study determined how proanthocyanidin profiles of sainfoin (Onobrychis viciifolia) and birdsfoot trefoil (Lotus corniculatus) change during the forage conservation process and along the digestive tract of lamb. We determined soluble, protein- and fiber-bound proanthocyanidins by spectrophotometric methods and soluble proanthocyanidin profiles by UPLC-MS/MS. During the conservation process, the total proanthocyanidin contents reduced in both forages and the relative proportion of insoluble proanthocyanidins increased, especially in sainfoin. The soluble proanthocyanidins, their mean degree of polymerization and the relative prodelphinidin share declined in both feed species. In the abomasum of lambs fed sainfoin silage, most of the proanthocyanidins were in insoluble form bound to proteins and fibers, but in the small and large intestines, the proportion of soluble proanthocyanidins increased again. For lambs fed birdsfoot trefoil, the trend was not so clear as proanthocyanidins were already mainly soluble in the abomasum. Nevertheless, a large part of soluble proanthocyanidins was recovered in the digestive tract but could not be detected by the UPLC-MS/MS method used. This study suggests that proanthocyanidins have probably been metabolized in the digestive tract by the resident microbiota.</p

Caractérisations expérimentale et numérique de composites minces tramés utilisés dans les circuits imprimés pour des applications hyperfréquences

Dans un contexte de miniaturisation des systèmes électroniques, les dimensions des circuits imprimés diminuent sensiblement avec une densité d'interconnexion toujours croissante. Cette densification mène les fabricants aux limites de leur savoir-faire. Pour des applications spatiales, les circuits imprimés doivent pouvoir subir un certain nombre de cycles thermiques sans apparition de défaillances. Or les matériaux utilisés ont des comportements thermomécaniques très différents. En particulier, l'écart sur les valeurs des coefficients d'expansion thermique entre le cuivre et les substrats composites est à l'origine de certaines de ces défaillances. Pour anticiper les problèmes de fiabilité dans les cartes de circuits imprimés, le recours à la simulation numérique est une nécessité, permettant ainsi de contourner la stratégie de conception par utilisation de prototypes successifs. En simulant différentes configurations, il est possible de déterminer la solution la plus fiable et ainsi améliorer la tenue en fatigue du circuit imprimé. Au préalable, il convient d'alimenter les modèles numériques. De ce fait, le comportement des différents matériaux en jeu doit être précisément déterminé. Cela concerne à la fois le comportement élasto-plastique du cuivre, mais aussi le comportement élastique des substrats. Or les substrats utilisés sont généralement des composites constitués d'une ou plusieurs trames de fibres de verre enrobées d'une résine souvent chargée. Les résines sont sélectionnées afin d'obtenir une carte avec des propriétés électriques et magnétiques souhaitées. Le comportement global des substrats ou plis composite est orthotrope et nécessite la connaissance de neuf constantes élastiques : E1, E2, E3, ?12, ?13, ?23, G12, G13, G23. Dans le cadre de ce travail, nous nous intéressons aux circuits imprimés multicouches et les plis ont généralement une épaisseur de quelques centaines de micromètres. Des essais de traction dans le plan nous permettent de relever quatre constantes élastiques : E1, E2, ?12, G12. Cependant, la caractérisation du comportement mécanique est difficile dans la direction de l'épaisseur. L'idée est d'estimer les cinq constantes manquantes à l'aide de simulations numériques. Avant de pouvoir simuler le comportement de ces composites, des essais de microtomographie ont été réalisés, permettant de connaître la structure interne des composites : le tissage des torons, les dimensions de la maille élémentaire représentative. Des observations au microscope électronique permettent de visualiser plus précisément la géométrie des torons et leur composition : forme et dimensions du toron, taux de fibres au sein du toron. En utilisant ces informations, il est alors possible de reproduire numériquement la structure interne du composite tissé. Etant donnés la taille et le nombre de fibres dans un toron, il est impossible de toutes les représenter. C'est pourquoi le comportement effectif isotrope transverse du toron sera estimé à l'aide d'une homogénéisation fibres/résine (réalisée par les méthodes éléments finis et un modèle de Mori-Tanaka). Puis le tissage au sein du VER est représenté avec les torons trame et chaîne se croisant. Des conditions aux limites périodiques sont appliquées sur ce motif élémentaire représentatif. Les différents chargements de traction et de cisaillement sont appliqués pour retrouver les constantes recherchées. A noter que le comportement élastique des fibres de verre est connu de la littérature, en revanche le comportement des résines enrobant les fibres est inconnu et non divulgué par les fabricants. Une analyse inverse est utilisée afin de déterminer le comportement de la résine en confrontant les résultats du modèle numérique aux résultats des mesures réalisées. Cette méthode permet donc d'estimer les neuf constantes du comportement élastique orthotrope d'un composite tissé. A l'issue de cette phase de caractérisation, les propriétés viendront alimenter un modèle éléments finis du circuit imprimé afin d'identifier les potentielles zones de rupture du cuivre dans les trous métallisés