Optimization of the Collection Efficiency of a Hexagonal Light Collector using Quadratic and Cubic B\'ezier Curves

Reflective light collectors with hexagonal entrance and exit apertures are frequently used in front of the focal-plane camera of a very-high-energy gamma-ray telescope to increase the collection efficiency of atmospheric Cherenkov photons and reduce the night-sky background entering at large incident angles. The shape of a hexagonal light collector is usually based on Winston's design, which is optimized for only two-dimensional optical systems. However, it is not known whether a hexagonal Winston cone is optimal for the real three-dimensional optical systems of gamma-ray telescopes. For the first time we optimize the shape of a hexagonal light collector using quadratic and cubic B\'ezier curves. We demonstrate that our optimized designs simultaneously achieve a higher collection efficiency and background reduction rate than traditional designs.Comment: 9 pages, 9 figure

Esthétique et pratique de la conception sonore au théâtre : le cas de la compagnie de théâtre d’objets La Pire Espèce

La conception sonore au théâtre est une pratique artistique à part entière présentant des enjeux multidisciplinaires. Celle-ci joue un rôle particulier dans le cadre du théâtre d’objets, un genre théâtral où les objets de la vie quotidienne, comme une théière ou un chapeau, ne sont plus de simples accessoires de théâtre, mais servent d’effigies, évoquent des personnages ou encore créent de nouveaux espaces scéniques. L’objectif principal de ce mémoire est de mieux cerner les rôles dramaturgiques que le son peut endosser dans un théâtre marginal tel que le théâtre d’objets. Pour ce faire, nous nous intéressons au cas particulier du Théâtre de La Pire Espèce, une compagnie montréalaise créée en 1999 dont les créations ont été maintes fois primées tant au Québec qu’à l’international. La Pire Espèce constitue un riche terrain de recherche et ses conceptions sonores participent à construire son esthétique dramatique très claire et travaillée. La compagnie documente d’ailleurs sa pratique à l’aide de billets de blogs et d’extraits vidéo accessibles gratuitement en ligne. En outre, ses membres fondateurs, Olivier Ducas et Francis Monty, s’appliquent à nommer et à définir les processus qu’ils mettent au point et sont aussi formateurs en théâtre d’objets. La méthodologie adoptée par la présente recherche repose sur des analyses d’extraits de pièces (mettant l’accent sur la conception sonore), des observations du processus de création de la compagnie, ainsi que des entrevues avec des artistes collaborateur·rice·s ou membres de la compagnie. Croisant les perspectives musicologiques et théâtrologiques, ce travail vise ainsi à déterminer les caractéristiques de l’esthétique sonore de La Pire Espèce et à mettre en lumière la dynamique collaborative et interdisciplinaire qui a permis de la développer.Theater sound design is an artistic practice presenting multidisciplinary issues. It plays an essential role in objects theater, a theatrical genre in which objects of everyday life, such as a teapot or a hat, are no longer basic theater accessories. They become meaningful, evoking characters. The aim of this master’s thesis is to better understand the numerous functions of sound in a marginal theater such as objects theater. For this purpose, this research will explore the case of the theater of La Pire Espèce, a company from Montreal created in 1999. Their creations, especially their sound design, has received several awards in Canada and Europe, and represent an interesting research area. On one hand, sound design is an important element which actively participates in forming their dramatic aesthetic. On the other hand, the company maintain records of a rich documentation of their practice with blogs and video extracts available online. The artistic directors of La Pire Espèce, Olivier Ducas and Francis Monty, theorize their theatrical process and propose objects theater classes. The methodology used throught this research consists in interviews with collaborators or members of the company, in observations of the creative process and in audiovisual captations analysis extracts. At the cross of musicology and theatrology, this research aims to understand the factors contributing to the sound aesthetic of La Pire Espèce and to highlight the role of collaboration and interdisciplinarity in building it

Purification, molecular cloning, and characterization of glutathione S-transferases (GSTs) from pigmented Vitis vinifera L. cell suspension cultures as putative anthocyanin transport proteins

The ligandin activity of specific glutathione S-transferases (GSTs) is necessary for the transport of anthocyanins from the cytosol to the plant vacuole. Five GSTs were purified from Vitis vinifera L. cv. Gamay Fréaux cell suspension cultures by glutathione affinity chromatography. These proteins underwent Edman sequencing and mass spectrometry fingerprinting, with the resultant fragments aligned with predicted GSTs within public databases. The corresponding coding sequences were cloned, with heterologous expression in Escherichia coli used to confirm GST activity. Transcriptional profiling of these candidate GST genes and key anthocyanin biosynthetic pathway genes (PAL, CHS, DFR, and UFGT) in cell suspensions and grape berries against anthocyanin accumulation demonstrated strong positive correlation with two sequences, VvGST1 and VvGST4, respectively. The ability of VvGST1 and VvGST4 to transport anthocyanins was confirmed in the heterologous maize bronze-2 complementation model, providing further evidence for their function as anthocyanin transport proteins in grape cells. Furthermore, the differential induction of VvGST1 and VvGST4 in suspension cells and grape berries suggests functional differences between these two proteins. Further investigation of these candidate ligandins may identify a mechanism for manipulating anthocyanin accumulation in planta and in vitro suspension cells

DNA Metabarcoding to quantify the response of insect diversity to mountain forest die-offs in the French Pyrenees

Mountain forests suffer from an increase in frequency and severity of summer droughts and infestations of pathogens and insects. Those factors are causing high mortality of some keystone tree species (forest die-offs). Yet, how tree diebacks and associated changes in forest composition will affect local diversity and ecosystem functions remains unknown. Here, we aim at quantifying the impact of climate-induced forest decline on biodiversity by measuring changes in taxonomic structure of invertebrate communities along gradients of silver fir (Abies alba) dieback in the French Pyrenees. We use DNA metabarcoding to analyse 224 samples of Malaise traps placed on 56 silver fir dominated plots in the French Pyrenees from May to September 2017. Samples were sequenced using Illumina MiSeq and analysed using the DAMe twin-tagging pipeline approach. We conducted taxonomic assignment against reference DNA barcode libraries to streamli ne identification and recover biological information for ecological analysis. We discuss the results of our metabarcoding analysis and the utility of our approach to conduct biomonitoring across a large geographical scale

Simulation of medium-frequency response in elastic shells using VTCR and PGD methods

This paper proposes an extension of the Variational Theory of Complex Rays [1,4] (VTCR) to calculate the medium-frequency bandwidth response in elastic shells using the Proper Generalized Decomposition [2,3] (PGD) technique. The VTCR is a Trefftz-type approach for calculating vibrations of slightly damped elastic structures in the medium-frequency range. This method uses a weak variational formulation of the vibration problem which allows the shape functions to be discontinuous across element boundaries giving this strategy great flexibility and efficiency. It has been fully developed for acoustic and structural vibration problems at a fixed frequency. The PGD method is a model reduction technique which relies on the a priori construction of the separated variables representation of the solution over the frequency-space domain. At first the frequency bandwidth is discretized in test points and the bilinear and the linear form are computed. After that the whole solution over the frequency-space domain is computed in a separated variable representation using the PGD technique. This PGD approach has shown good results on other multiparametric problems. This work will show its efficiency on the considered examples which concern pyrotechnic shocks and frequency band vibration problems. References [1] Ladevèze, P. A new computational approach for structure vibrations in the medium frequency range. Comptes Rendus Académie des Sciences Paris 332, 2b (1996), 849–856. [2] Néron, D., and Ladevèze, P. Proper generalized decomposition for multiscale and multiphysics problems. Archives of Computational Methods in Engineering 17, 4 (2010), 351–372. [3] Nouy, A. A priori model reduction through Proper Generalized Decomposition for solving time-dependent partial differential equations, vol. 199. Apr. 2010. [4] Riou, H., Ladevèze, P., and Rouch, P. Extension of the variational theory of complex rays to shells for medium-frequency vibrations. Journal of Sound and Vibration 272, 1-2 (Apr. 2004), 341–360

Mathematical modelling of CAD systems in Building Engineering

[EN] There exists a wide range of CAD systems devoted to model three-dimensional objects. Based on an intuitive creation and transformation of basic geometrical objects, the mathematical foundation of such systems is generally unknown to their users. The incorporation of this kind of software in Math classes is a fundamental key to get the attention of students of those degrees for which CAD systems are not only attractive, but also extremely important in the future professional career. The current paper deals with the experience carried out in this regard during the last five years by students of the Building Engineering Degree of the University of Seville. The methodological search of mathematical models that allow them to construct virtually real buildings has improved not only the process of teaching-learning, but also their interest in the subject and their academic efficiency. A virtual tour through their constructions is a perfect excuse to deal also with the mathematical foundation on which they are based on.[ES] Existe una amplia gama de sistemas CAD destinados a modelar objetos tridimensionales. Basados en una creación y transformación intuitiva de objetos geométricos básicos, el fundamento matemático de estas herramientas es generalmente desconocido por sus usuarios. La incorporación de las mismas en el aula de Matemáticas es una pieza clave para lograr captar la atención del alumnado de aquellas titulaciones universitarias en las que los sistemas CAD no sólo son atrayentes, sino que son además de suma importancia para la futura vida profesional. El presente artículo trata acerca de la experiencia docente llevada a cabo en este sentido durante los últimos cinco años en el Grado de Ingeniería de Edificación de la Universidad de Sevilla. La búsqueda metodológica de modelos matemáticos que les permita construir virtualmente edificios reales ha mejorado no sólo el proceso de enseñanza-aprendizaje, sino también su interés en la materia y su rendimiento académico. Un recorrido virtual a través de sus construcciones es una perfecta excusa para tratar también el fundamento matemático en los que se basan los mismosFalcón Ganfornina, RM. (2015). Modelización matemática de sistemas CAD en Edificación. Modelling in Science Education and Learning. 8(2):145-194. doi:10.4995/msel.2015.3258.SWORD1451948

Climate-induced forest dieback drives compositional changes in insect communities that are more pronounced for rare species

Species richness, abundance and biomass of insects have recently undergone marked declines in Europe. We metabarcoded 211 Malaise-trap samples to investigate whether drought-induced forest dieback and subsequent salvage logging had an impact on ca. 3000 species of flying insects in silver fir Pyrenean forests. While forest dieback had no measurable impact on species richness, there were significant changes in community composition that were consistent with those observed during natural forest succession. Importantly, most observed changes were driven by rare species. Variation was explained primarily by canopy openness at the local scale, and the tree-related microhabitat diversity and deadwood amount at landscape scales. The levels of salvage logging in our study did not explain compositional changes. We conclude that forest dieback drives changes in species assemblages that mimic natural forest succession, and markedly increases the risk of catastrophic loss of rare species through homogenization of environmental conditions

Experimental and computational study of alkane dehydrogenation catalyzed by a carbazolide-based rhodium PNP pincer complex

A rhodium complex based on the bis-phosphine carbazolide pincer ligand was investigated in the context of alkane dehydrogenation and in comparison with its iridium analogue

Stoichiometric and catalytic C-C and C-H bond formation with B(C6F5)3 via cationic intermediates

This work showcases a new catalytic cyclization reaction using a highly Lewis acidic borane with concomitant C−H or C−C bond formation. The activation of alkyne‐containing substrates with B(C6F5)3 enabled the first catalytic intramolecular cyclizations of carboxylic acid substrates using this Lewis acid. In addition, intramolecular cyclizations of esters enable C−C bond formation as catalytic B(C6F5)3 can be used to effect formal 1,5‐alkyl migrations from the ester functional groups to unsaturated carbon–carbon frameworks. This metal‐free method was used for the catalytic formation of complex dihydropyrones and isocoumarins in very good yields under relatively mild conditions with excellent atom efficiency

Stöchiometrische und katalytische C-C- und C-H-Bindungsbildung mit B(C6 F5 )3 über kationische Zwischenstufen

Diese Arbeit beschreibt eine neuartige katalytische Cyclisierung unter Verwendung eines stark Lewis-sauren Borans mit einhergehender C-H- oder C-C-Bindungsbildung. Die Aktivierung von Molekülen mit C-C-Dreifachbindungen unter Verwendung von B(C6F5)3 ermöglicht erstmals eine entsprechende Lewis-Säure-katalysierte, intramolekulare Cyclisierung von Carbonsäuren. Darüber hinaus zeigen die Ester dieser Carbonsäuren mit katalytischen Mengen B(C6F5)3 eine formale 1,5-Migration der Estergruppen unter Knüpfung einer C-C-Bindung. Unter Verwendung dieser neuen metallfreien Methode konnten anspruchsvolle Dihydropyrone und Isocumarine in hohen Ausbeuten unter milden Bedingungen sowie mit hoher Atomökonomie synthetisiert werden