The Heisenberg product seen as a branching problem for connected reductive groups, stability properties

In this article we study, in the context of complex representations of symmetric groups, some aspects of the Heisenberg product, introduced by Marcelo Aguiar, Walter Ferrer Santos, and Walter Moreira in 2017. When applied to irreducible representations, this product gives rise to the Aguiar coefficients. We prove that these coefficients are in fact also branching coefficients for representations of connected complex reductive groups. This allows to use geometric methods already developped in a previous article, notably based on notions from Geometric Invariant Theory, and to obtain some stability results on Aguiar coefficients, generalising some of the results concerning them given by Li Ying

A Geometric Approach to the stabilisation of certain sequences of Kronecker coefficients

We give another proof, using tools from Geometric Invariant Theory, of a result due to S. Sam and A. Snowden in 2014, concerning the stability of Kro-necker coefficients. This result states that some sequences of Kronecker coefficients eventually stabilise, and our method gives a nice geometric bound from which the stabilisation occurs. We perform the explicit computation of such a bound on two examples, one being the classical case of Murnaghan's stability. Moreover, we see that our techniques apply to other coefficients arising in Representation Theory: namely to some plethysm coefficients and in the case of the tensor product of representations of the hyperoctahedral group.Comment: Manuscripta mathematica, Springer Verlag, In press, \&\#x3008;https://doi.org/10.1007/s00229-018-1021-4\&\#x300

Micelles sensibles à la chaleur, au PH et à la lumière

L'ouverture des micelles de copolymère à blocs (CPB) contrôlée par un stimulus (chaleur, pH, lumière, etc.) suscite beaucoup d'intérêts dans le domaine de la libération contrôlée de médicaments. L'amélioration du contrôle de l'ouverture des micelles à un endroit spécifique et à un temps précis est un enjeu majeur. La plupart des micelles sensibles à la chaleur utilisent la température critique inférieure (LCST) d'un bloc pour déstabiliser les micelles. Dans un premier temps, l'étude porte sur l'élaboration d'un nouveau type de micelles CPB qui sont sensibles à la chaleur via un groupement protecteur thermolabile. Le copolymère étudié est le poly(oxyde d'éthylène)-bloc-poly(méthacrylate de 2-tétrahydropyranyl) (PEO-b-PTHPMA). En effet, l'hydrolyse du groupement tétrahydropyranyl (THP) est sensible à la chaleur ainsi qu'au pH acide. Le copolymère a été synthétisé par polymérisation radicalaire par transfert d'atome (ATRP). L'analyse du CPB a été effectuée par chromatographie de perméation de gel (GPC), spectroscopie infrarouge, résonance magnétique nucléaire du proton (RMN 1H), et par calorimétrie différentielle à balayage (DSC). Pour ce qui est de l'effet de la chaleur et du pH sur les micelles du PEO-b-PTHPMA, la spectroscopie de fluorescence, la diffusion dynamique de la lumière (DLS), ainsi que la microscopie électronique à balayage (MEB) ont été utilisées. L'étude démontre que la déstabilisation des micelles est influencée par la chaleur, le pH et la longueur des blocs du copolymère. De plus, pour la première fois trois événements liés à l'ouverture des micelles ont été suivis. La seconde partie du mémoire est consacrée à l'étude de micelles photosensibles. Un deuxième nouveau CPB a été synthétisé par ATRP, soit le copolymère poly(oxyde d'éthylène)-bloc-poly(méthacrylate de [7-(diéthylamino)coumarine-4-yl]méthyl) (PEO-b-PDEACMMA). Le bloc contenant la molécule de coumarine est photosensible. Elle peut être clivée par l'absorption d'un photon UV ou de deux photons proche infrarouge, déplaçant ainsi la balance hydrophile/hydrophobe vers la déstabilisation des micelles. La caractérisation du copolymère ainsi que des micelles a été effectuée avec les mêmes méthodes que pour le premier projet. L'étude démontre une amélioration de la sensibilité des micelles à l'absorption à deux photons, ce qui est un avantage pour la libération de médicaments à l'aide de la lumière

Modes et approches du cinéma documentaire : réflexion autour du projet American Utopias

Ce mémoire de recherche-création prend comme point de départ le film documentaire American Utopias que j’ai réalisé en 2014-2015. Le film nous plonge au cœur du quotidien de cinq communautés alternatives et expérimentales des États-Unis et réfléchit aux multiples défis et enjeux que vivent leurs membres. Organisé autour du thème de l’utopie, ce récit de voyage documentaire nous fait connaître tour à tour une communauté de mini-maisons à Washington D.C., une communauté « Earthship » à Ithaca, une communauté vivant sans électricité et sans pétrole au Missouri, un laboratoire urbain dans le désert de l’Arizona et le festival Burning Man au Nevada. La portion théorique de ce mémoire s’organise quant à elle autour de la question des approches du cinéma documentaire. Prenant comme appui la typologie de Bill Nichols, il s’agit ici de voir comment chaque approche privilégiée par le créateur de documentaire renvoie au réel d’une manière qui lui est propre. Grâce à une approche autopoïétique et un travail d’analyse de films, ce mémoire cherche également à circonscrire les forces et les limites intrinsèques à chaque mode. Ce faisant, le lecteur est amené à mieux comprendre les motivations qui soutiennent certains choix de création dans American Utopias.This research-creation project explores the theories of Bill Nichols, in particular his typology of documentary modes, from a creator’s perspective. Our intention is to revisit the creative process of American Utopias, a documentary on alternative communities in United States of America, by linking some of the key creative choices of the filmmaker to Nichols’ work. Furthermore, our objective is to help defining the strengths and weaknesses of each mode described by the theoretician with concrete examples derived from movies analysis and direct experience. Created in 2014-15, American Utopias aims to show how different people have conceived and created original, ecofriendly and sustainable homes. It focuses on a three months journey made by the director through the USA to visit ecovillages, earthships, tiny house communities, the Burning Man Festival and other creative and unique places. On a philosophical and human point of view, it also reflects on the notion of utopia

Hares and rabbits at Regourdou (Montignac-sur-Vézère, Dordogne, France): paleontological and taphonomic studies of two naturally-occurring bone accumulations

Depuis la fin du XIXe siècle, l’Europe occidentale a fait l’objet de très nombreux travaux pour étudier les modes de subsistance des sociétés préhistoriques. À partir du Paléolithique moyen, les Hommes vont alors s’intéresser au petit gibier, tels que les léporidés, taxons relativement abondants sur ce territoire. Or, distinguer l’origine de leur accumulation dans un site archéologique ne constitue pas une tâche aisée tant les agents pouvant en être responsables sont nombreux (i.e. mortalité naturelle, humains, carnivores terrestres, rapaces nocturnes ou diurnes). Dans cette contribution, nous avons mené des études taphonomique et paléontologique sur les léporidés de Regourdou, gisement moustérien ayant livré le squelette d’un Néandertalien. Les indices recensés suggèrent qu’aucun prédateur n’est intervenu dans les processus d’accumulation des restes de lièvres et de lapins, mais leurs assemblages seraient dus, respectivement, à une mortalité naturelle de type accidentelle et de type attritionnelle. La mise en évidence du premier processus montre que la cavité aurait fonctionné comme un aven-piège à un moment donné de son histoire, tandis que le second révèle l’existence d’une Garenne in situ, interprétée comme la dernière occupation du site durant le MIS 4 ou 3, avant la fin du comblement sédimentaire. Les variations morphologiques et de taille corporelle des individus permettent également de préciser les changements d’ordre paléo-environnementaux depuis le début du fonctionnement du site, confirmant l’attribution des niveaux inférieurs à la période tempérée du MIS 5, et les niveaux supérieurs à une phase plus récente du MIS 4 ou 3.Since the end of the nineteenth century, a great deal of work studying subsistence patterns of prehistoric societies in Western Europe has been done. During the Middle Paleolithic, humans were interested in small game, particularly the Leporidae, taxa that were abundant in their territories. However, distinguishing the exact nature of their origin in an archaeological site is not an easy task, given that numerous agents could be responsible for their accumulation (i.e., natural mortality, acquisition by humans and/or other terrestrial carnivores, or even nocturnal or diurnal raptors). In this contribution, we put forth a new taphonomic and paleontological study of the leporids of Regourdou, a Mousterian site that has yielded a Neandertal skeleton. This study suggests that no predators were involved in the accumulation of the hare or rabbit remains, but rather that they are due to natural (accidental) mortality for the former, and natural (attritional) mortality for the latter. Specifically, the evidence suggests that at one point in its history (for the hares), the cavity functioned as a natural pitfall trap, while for the rabbits it appears to show the existence of a warren, which we interpret as having existed during the last occupation of the site during MIS 4 or 3, before the end of the accumulation of sediments in the site. Morphological variation and body size of individuals also allows us to specify the order of paleoenvironmental changes since the site’s functional beginning, confirming the attribution of the inferior levels to the MIS 5 temperate period, and the upper levels to a more recent phase in MIS 4 or 3

Spatial dependency and independency of nitrogen in lowbush blueberry commercial fields

Rhizomes of wild lowbush blueberry (Vaccinium angustifolium Aiton) extend horizontally, creating spatial dependency when fertilization trials are performed. Knowing this spatial dependency would help researchers to better design field studies. Here, we used labelled nitrogen (N) fertilizer (15N-(NH4)2SO4) to measure N translocation among blueberry stems for one old (56 year) and one younger (15 year) commercial field. Leaf 15N concentrations at the tip-dieback stage were used to monitor N acquisition. No difference between sites suggests no field age effect on N translocation. Spatial dependency and independency were reached for distances of ≤0.75 and ≥1.75 m from the fertilizer application point, respectively

Metabolic counterparts of sodium accumulation in multiple sclerosis: A whole brain 23Na-MRI and fast 1H-MRSI study

Increase of brain total sodium concentrations (TSC) is present in multiple sclerosis (MS), but its pathological involvement has not been assessed yet. To determine in vivo the metabolic counterpart of brain sodium accumulation. Whole brain Na-MR imaging and 3D- H-EPSI data were collected in 21 relapsing-remitting multiple sclerosis (RRMS) patients and 20 volunteers. Metabolites and sodium levels were extracted from several regions of grey matter (GM), normal-appearing white matter (NAWM) and white matter (WM) T lesions. Metabolic and ionic levels expressed as Z-scores have been averaged over the different compartments and used to explain sodium accumulations through stepwise regression models. MS patients showed significant Na accumulations with lower choline and glutamate-glutamine (Glx) levels in GM; Na accumulations with lower N-acetyl aspartate (NAA), Glx levels and higher Myo-Inositol (m-Ins) in NAWM; and higher Na, m-Ins levels with lower NAA in WM T lesions. Regression models showed associations of TSC increase with reduced NAA in GM, NAWM and T lesions, as well as higher total-creatine, and smaller decrease of m-Ins in T lesions. GM Glx levels were associated with clinical scores. Increase of TSC in RRMS is mainly related to neuronal mitochondrial dysfunction while dysfunction of neuro-glial interactions within GM is linked to clinical scores

Importance of field data for understanding a potential Mousterian funerary deposit : the case of the Regourdou 1 skeleton (Montignac-sur-Vézère, Dordogne, France)

Aside from the work of Bonifay (see Bonifay et al. 2007 for one of the more recent papers) and various articles following these earlier works (e.g., Binant 1991, Defleur 1993, Maureille et Vandermeersch 2007, Pettitt 2011, see also May 1986 for a more critical analysis), the in situ position of the remains of Regourdou 1 from layer 4 has never actually been discussed on the basis of available data from the salvage operation carried out in October 1957 by E. Bonifay and G. Laplace-Jauretche, under the administrative authority of François Bordes, or from the subsequent, more systematic, excavations directed by E. Bonifay between 1961 and 1964. Via the compilation of available information from a number of unpublished documents (François Bordes’ field notes, drawings made during the salvage operation, photographs taken in 1957, 1961 and 1962, as well as databases from the 1961 to 1964 excavations), and also a new inventory of human remains (both previously known and recently discovered), it is now possible to more accurately reconstruct the position of the human remains in a Cartesian system. In this, we assume that the concentration of remains uncovered during the salvage operation was in square G2, according to the preliminary systematic excavations carried out in 1961. They also bring to light that while practically no anatomical connections can be demonstrated with any certainty – and despite significant disruptions (all of the hominin remains are spread over 9 squares : G1 to G3, F1 to F3, E1 and E2, D2) – they are mainly positioned in squares G2 and G3 to some degree with respect to the anatomical logic of the human body. We therefore assume that Regourdou 1 was lying flat, with its head to the west – perhaps upon its trunk – close to the wall of the cavity. This result is different from the fetal position hypothesis proposed in Bonifay et al. (2007). Moreover many post-depositional (albeit Pleistocene) disturbances are also evident. We believe that they were likely the result of the utilization and modification of the cavity by brown bears and lagomorphs.Only new excavations at the site, and a better taphonomic understanding of Bonifay’s (1964) layer 4 (in which Regourdou 1 was found), and the exact role of humans in its formation, i.e., their anthropic impact on the layer, will allow us to discuss in more detail the nature of the deposition of the body, and, hopefully, the absence of the skull

Wafer-scale detachable monocrystalline Germanium nanomembranes for the growth of III-V materials and substrate reuse

Germanium (Ge) is increasingly used as a substrate for high-performance optoelectronic, photovoltaic, and electronic devices. These devices are usually grown on thick and rigid Ge substrates manufactured by classical wafering techniques. Nanomembranes (NMs) provide an alternative to this approach while offering wafer-scale lateral dimensions, weight reduction, limitation of waste, and cost effectiveness. Herein, we introduce the Porous germanium Efficient Epitaxial LayEr Release (PEELER) process, which consists of the fabrication of wafer-scale detachable monocrystalline Ge NMs on porous Ge (PGe) and substrate reuse. We demonstrate monocrystalline Ge NMs with surface roughness below 1 nm on top of nanoengineered void layer enabling layer detachment. Furthermore, these Ge NMs exhibit compatibility with the growth of III-V materials. High-resolution transmission electron microscopy (HRTEM) characterization shows Ge NMs crystallinity and high-resolution X-ray diffraction (HRXRD) reciprocal space mapping endorses high-quality GaAs layers. Finally, we demonstrate the chemical reconditioning process of the Ge substrate, allowing its reuse, to produce multiple free-standing NMs from a single parent wafer. The PEELER process significantly reduces the consumption of Ge during the fabrication process which paves the way for a new generation of low-cost flexible optoelectronics devices.Comment: 17 pages and 6 figures along with 3 figures in supporting informatio

Epigenetic loss of RNA‑methyltransferase NSUN5 in glioma targets ribosomes to drive stress adaptive translational program

Tumors have aberrant proteomes that often do not match their corresponding transcriptome profiles. One possible cause of this discrepancy is the existence of aberrant RNA modification landscapes in the so-called epitranscriptome. Here, we report that human glioma cells undergo DNA methylation-associated epigenetic silencing of NSUN5, a candidate RNA methyltransferase for 5-methylcytosine. In this setting, NSUN5 exhibits tumor-suppressor characteristics in vivo glioma models. We also found that NSUN5 loss generates an unmethylated status at the C3782 position of 28S rRNA that drives an overall depletion of protein synthesis, and leads to the emergence of an adaptive translational program for survival under conditions of cellular stress. Interestingly, NSUN5 epigenetic inactivation also renders these gliomas sensitive to bioactivatable substrates of the stress-related enzyme NQO1. Most importantly, NSUN5 epigenetic inactivation is a hallmark of glioma patients with long-term survival for this otherwise devastating disease