Les ambiances dans la conception architecturale : une « histoire » de représentations

Over the years architects have tried to make representations to reveal their architecture. Therefore, they have to take account of sensations and individual experience. In this paper, we suggest a historical approach to identify main events which had consequences on the history of architectural atmosphere representations. This text presents the beginning of an ongoing work about the overall representation of architectural atmosphere in which we wonder how architects create and communicate the atmosphere that they imagine in their future buildings. How do they deal with architectural atmosphere contingent at the different steps of the architectural project? How do they represent atmosphere they want to communicate? How do users feel the atmosphere in the building?L'architecte a cherché, au cours du temps, à donner une représentation évocatrice de sensations faisant référence à l'expérience personnelle pour révéler son architecture. Nous proposons dans cet article une approche historique qui permet d'identifier des leviers (évènements, écrits, outils, ...) qui ont fait évoluer la représentation des ambiances dans les différentes représentations architecturales. Il s'agit ici des prémisses d'un travail de recherche plus global en cours interrogeant la manière dont un architecte conçoit et communique ses intentions d'ambiances et la manière dont elles sont vécues dans le bâtiment. Comment les ambiances sont abordées dans les différentes phases du projet ? Comment sont-elles représentées dans le but d'être communiquées ? Comment sont-elles ressenties par les usagers une fois le bâtiment vécu

Passive microrheology as a useful tool for milk gel analyses

Passive microrheology based on Diffusing Wave Spectroscopy (DWS) [1,2] is presented as a straightforward tool for the analysis of milk gel preparation. Diffusing Wave Spectroscopy consists of analysing the interferential images of light, which is backscattered by the sample. This so called speckles images, which are detected by a CCD camera, change in time due to the Brownian motion of the particles that scatter the light. The variation of the images as a function of time can be directly correlated to the viscoelastic properties of the sample. As it is an optical method, it is perfectly adapted to study the weak gels of milk products. Nowadays, milk gels such as yogurts or chees have attracted lots of interest due to its growing market. The milk properties, such as pH, calcium content and protein content are very important and change significantly the cheese properties. This work shows how passive microrheology can be used to follow up the milk gel formation with exact gel time determination. Gel time was determined by a new rescaling method, namely Time-Cure Superposition (TCS) [3,4]. This data processing determines the gel point according to the Winter-Chambon criterion [5]. Moreover, the viscoelastic properties of the preparation can be compared according to parameters, such as the protein enrichment, calcium ion addition or others. Results were compared to other instruments (texturometers, rheometer, Optigraph®, etc.). References: [1] D. A. Weitz et al., in Dynamic Light Scattering, W. Brown (Ed.) (Oxford Univ. Press, New York (1993), Chap. 16. [2] D. J. Pine et al., Phys. Rev. Lett. 1988, 60, 1434. [3] T. H. Larsen, E. M. Furst, Phys. Rev. Letters, 2008, 100, 14600 [4] K. M. Schultz, E. M. Furst, Soft Matter, 2012, 8, 6198 [5] H. H. Winter, F. Chambon, J. Rheology 1986, 30, 364-38

Prediction of collapse time of polymer stabilized O/W emulsions

Polymers are widely used in the industry as an ingredient to increase the stability of formulations. Depending on their concentration, they can act as depletion agents or gel agent. The stability of these systems is driven by the polymers and the structure of the network of droplets and can lead to collapse of the emulsions. In this work, Multiple Light Scattering device is used to monitor the behaviour of w/o emulsions stabilized with polymers. The heart of the optical scanning analyser is a detection head, which moves up and down along a flat-bottomed cylindrical glass cell (see figure). The detection head is composed of a pulsed near infrared light source (wavelength = 880 nm) and two synchronous detectors. The transmission detector (at 180°) receives the light, which goes through the sample, while the backscattering detector (at 45°) receives the light scattered backward by the sample. The detection head scans the entire height of the sample, acquiring transmission and backscattering data every 40 µm. Please click Additional Files below to see the full abstract

Modélisations numériques des pertes en régime variable dans des tubes supraconducteurs

Les pertes AC dans les câbles supraconducteurs générées par un environnement variable dans le temps impactent la cryogénie et donc la faisabilité industrielle des dispositifs supraconducteurs. Nexans est aujourd'hui sur le point de réaliser des fils cylindriques supraconducteurs pour des câbles de forte puissance. Aucune étude numérique n'a pour l'instant porté sur le calcul des pertes AC dans un ou plusieurs tubes. Cet article présente les étapes de création d'un modèle de calcul de pertes à l'aide d'un logiciel d'éléments finis pour une nouvelle géométrie :tube ou cylindre supraconducteur. La non-linéarité des formules E-J ainsi que les problèmes de convergence ont été traités par l'implémentation d'une formulation en H pour la résolution numérique. Les résultats ont été comparés aux formules analytiques. Dans le but de vérifier l'exactitude du modèle, une série de mesures expérimentales a aussi été réalisée sur un ruban supraconducteur industriel.</p

Causes and consequences of pronounced variation in the isotope composition of plant xylem water

Stable isotopologues of water are widely used to derive relative root water uptake (RWU) profiles and average RWU depth in lignified plants. Uniform isotope composition of plant xylem water (delta(xyl)) along the stem length of woody plants is a central assumption of the isotope tracing approach which has never been properly evaluated.Here we evaluate whether strong variation in delta(xyl) within woody plants exists using empirical field observations from French Guiana, northwestern China, and Germany. In addition, supported by a mechanistic plant hydraulic model, we test hypotheses on how variation in delta(xyl) can develop through the effects of diurnal variation in RWU, sap flux density, diffusion, and various other soil and plant parameters on the delta(xyl) of woody plants.The hydrogen and oxygen isotope composition of plant xylem water shows strong temporal (i.e., sub-daily) and spatial (i.e., along the stem) variation ranging up to 25.2 parts per thousand and 6.8 parts per thousand for delta H-2 and delta O-18, respectively, greatly exceeding the measurement error range in all evaluated datasets. Model explorations predict that significant delta(xyl) variation could arise from diurnal RWU fluctuations and vertical soil water heterogeneity. Moreover, significant differences in delta(xyl) emerge between individuals that differ only in sap flux densities or are monitored at different times or heights.This work shows a complex pattern of delta(xyl) transport in the soil-root-xylem system which can be related to the dynamics of RWU by plants. These dynamics complicate the assessment of RWU when using stable water isotopologues but also open new opportunities to study drought responses to environmental drivers. We propose including the monitoring of sap flow and soil matric potential for more robust estimates of average RWU depth and expansion of attainable insights in plant drought strategies and responses

Engineering of robust topological quantum phases in graphene nanoribbons

Here we present a flexible strategy to realize robust nanomaterials exhibiting valence electronic structures whose fundamental physics is described by the SSH-Hamiltonian. These solid-state materials are realized using atomically precise graphene nanoribbons (GNR). We demonstrate the controlled periodic coupling of topological boundary states at junctions of armchair GNRs of different widths to create quasi-1D trivial and non-trivial electronic quantum phases. Their topological class is experimentally determined by drawing upon the bulk-boundary correspondence and measuring the presence (non-trivial) or absence (trivial) of localized end states by scanning tunneling spectroscopy (STS). The strategy we propose has the potential to tune the band width of the topological electronic bands close to the energy scale of proximity induced spin-orbit coupling or superconductivity, and may allow the realization of Kitaev like Hamiltonians and Majorana type end states

Substrate transfer and ex situ characterization of on-surface synthesized graphene nanoribbons

Recent progress in the on-surface synthesis of graphene nanoribbons (GNRs) has given access to atomically precise narrow GNRs with tunable electronic band gaps that makes them excellent candidates for room-temperature switching devices such as field-effect transistors (FET). However, in spite of their exceptional properties, significant challenges remain for GNR processing and characterization. This contribution addresses some of the most important challenges, including GNR fabrication scalability, substrate transfer, long-term stability under ambient conditions and ex situ characterization. We focus on 7- and 9-atom wide armchair graphene nanoribbons (i.e, 7-AGNR; and 9-AGNR) grown on 200 nm Au(111)/mica substrates using a high throughput system. Transfer of both, 7- and 9-AGNRs from their Au growth sub-strate onto various target substrates for additional characterization is accomplished utilizing a polymer-free method that avoids residual contamination. This results in a homogeneous GNR film morphology with very few tears and wrinkles, as examined by atomic force microscopy. Raman spectroscopy indicates no significant degradation of GNR quality upon substrate transfer, and reveals that GNRs have remarkable stability under ambient conditions over a 24-month period. The transferred GNRs are analyzed using multi-wavelength Raman spectroscopy, which provides detailed insight into the wavelength dependence of the width-specific vibrational modes. Finally, we characterize the optical properties of 7- and 9-AGNRs via ultra-violet-visible (UV-Vis) spectroscopyComment: 30 pages, 14 figure

Mutations in the m-AAA proteases AFG3L2 and SPG7 are causing isolated dominant optic atrophy.

OBJECTIVE: To improve the genetic diagnosis of dominant optic atrophy (DOA), the most frequently inherited optic nerve disease, and infer genotype-phenotype correlations. METHODS: Exonic sequences of 22 genes were screened by new-generation sequencing in patients with DOA who were investigated for ophthalmology, neurology, and brain MRI. RESULTS: We identified 7 and 8 new heterozygous pathogenic variants in SPG7 and AFG3L2. Both genes encode for mitochondrial matricial AAA (m-AAA) proteases, initially involved in recessive hereditary spastic paraplegia type 7 (HSP7) and dominant spinocerebellar ataxia 28 (SCA28), respectively. Notably, variants in AFG3L2 that result in DOA are located in different domains to those reported in SCA28, which likely explains the lack of clinical overlap between these 2 phenotypic manifestations. In comparison, the SPG7 variants identified in DOA are interspersed among those responsible for HSP7 in which optic neuropathy has previously been reported. CONCLUSIONS: Our results position SPG7 and AFG3L2 as candidate genes to be screened in DOA and indicate that regulation of mitochondrial protein homeostasis and maturation by m-AAA proteases are crucial for the maintenance of optic nerve physiology