Monitored background radiometer

The infrared (IR) testing of the Olympus thermal model has provided a capability to perform cost effective thermal balance testing of satellites and satellite components. A high-accuracy monitored background radiometer was developed for the measurement of absorbed radiation heat flux encountered during IR thermal vacuum testing of spacecraft. The design, development, and calibration of this radiometer is described

Illustrer le territoire québécois dans les manuels d’histoire au secondaire : étude de cas sur le paysage en tant qu’outil de médiation culturelle et ses rapports avec l’espace, le pouvoir et l’identité

Dans le présent article, nous proposons une réflexion sur l’usage du paysage dans trois manuels d’histoire québécois. Nous l’abordons premièrement en considérant le cadre de référence (ou le contexte de production) de ces documents visuels, de nature artistique, scientifique ou médiatique,relatifs à l’architecture. Nous analysons ces trois types de paysages pour discuter des rapports qu’ils entretiennent avec le réel, notamment concernant un certain effet d’authenticité et d’objectivité. Il s’agit alors de considérer le paysage en tant qu’outil de médiation culturelle. Nous poursuivons la réflexion sur l’usage du paysage par une analyse thématique de lieux associés à la ville de Montréal dans les manuels. Ensuite, nous présentons une grille de lecture des documents iconographiques qui pourrait s’appliquer à tout paysage considéré comme document iconographique pour susciter un questionnement productif sur le plan des informations que l’on peut en tirer. In this paper, we propose a reflection on the use of the landscape in three Quebec history textbooks. We turn first considering the terms of reference (or the context of production) of these visual documents, produced from an artistic, scientific or mediatic point of view. We analyze these three types of landscapes to discuss their relationship with reality, especially regarding some effect of authenticity and objectivity. It is then to consider the landscape as a tool for cultural mediation. We continue the reflection on the use of the landscape by a thematic analysis of places associated with the city of Montreal in textbooks. Thirdly, we present a reading grid of graphic materials that could be applied to any landscape considered as graphic material, in order to question it in terms of information that can be learned

Les enjeux associés à l'appropriation de ressources numériques muséales par des enseignants du secondaire du Québec : proposition d'un cadre d'analyse

Depuis 2014, le Musée des beaux-arts de Montréal développe une plateforme nommée ÉducArt, qui suggère des activités éducatives réalisées à partir de sa collection encyclopédique pour soutenir les écoles secondaires québécoises dans leur mission culturelle. Comme l’élaboration de ressources destinées au milieu scolaire demande de tenir compte des besoins et des réalités de la classe (Van der Maren, 1996, 2003) et que le gouvernement du Québec entend poursuivre le financement de plateformes muséales (Rocheleau, 2016), il apparaît important d’étudier les enjeux associés à l’appropriation de ressources numériques muséales, telles que celles diffusées sur la plateforme ÉducArt, par des enseignants du secondaire du Québec. Dans cette perspective, un cadre d’analyse visant à mieux comprendre ces enjeux semble essentiel. Cet article se veut une contribution en ce sens, car à notre connaissance, aucun modèle théorique n’existe pour comprendre les enjeux particuliers que rencontrent des enseignants du secondaire lorsqu’ils tentent de s’approprier des ressources numériques muséales.Since 2014, the Montreal Museum of Fine Arts develops a platform called ÉducArt, which offers educational activities carried out from its encyclopaedic collection to support Quebec high schools in their cultural mission. As the development of such resources for schools requires consideration of the class needs and realities (Van der Maren, 1996; 2003) and Quebec’s government intends to continue financing museum platforms (Rocheleau, 2016), it appears important to study the issues associated with the appropriation of digital museum resources, such as those published on the ÉducArt platform, by high school teachers in Quebec. In this context, an analytical framework to better understand these issues seems essential. This article is intended to be a contribution in this direction because, to our knowledge, no theoretical model exists in order to specifically understand the issues encountered by high school teachers when trying to appropriate digital museum resources

Nonlinear magnetoinductive transmission lines

Power transmission in one-dimensional nonlinear magnetic metamaterials driven at one end is investigated numerically and analytically in a wide frequency range. The nonlinear magnetic metamaterials are composed of varactor-loaded split-ring resonators which are coupled magnetically through their mutual inductances, forming thus a magnetoiductive transmission line. In the linear limit, significant power transmission along the array only appears for frequencies inside the linear magnetoinductive wave band. We present analytical, closed form solutions for the magnetoinductive waves transmitting the power in this regime, and their discrete frequency dispersion. When nonlinearity is important, more frequency bands with significant power transmission along the array may appear. In the equivalent circuit picture, the nonlinear magnetoiductive transmission line driven at one end by a relatively weak electromotive force, can be modeled by coupled resistive-inductive-capacitive (RLC) circuits with voltage-dependent capacitance. Extended numerical simulations reveal that power transmission along the array is also possible in other than the linear frequency bands, which are located close to the nonlinear resonances of a single nonlinear RLC circuit. Moreover, the effectiveness of power transmission for driving frequencies in the nonlinear bands is comparable to that in the linear band. Power transmission in the nonlinear bands occurs through the linear modes of the system, and it is closely related to the instability of a mode that is localized at the driven site.Comment: 11 pages, 11 figures, submitted to International Journal of Bifurcation and Chao

Asymmetric total synthesis of (+)-virosine a via sequential nucleophilic cyclizations onto an activated formamide

Abstract: The first synthesis of tetracyclic alkaloid virosine A is reported. The natural alkaloid was prepared in only 13 steps, in an enantioenriched form. The azabicyclo[2.2.2]octane core was efficiently assembled using a key Vilsmeier–Haack and Mannich cyclizations sequence performed in one pot

The Reelin Receptors Apoer2 and Vldlr Coordinate the Patterning of Purkinje Cell Topography in the Developing Mouse Cerebellum

The adult cerebellar cortex is comprised of reproducible arrays of transverse zones and parasagittal stripes of Purkinje cells. Adult stripes are created through the perinatal rostrocaudal dispersion of embryonic Purkinje cell clusters, triggered by signaling through the Reelin pathway. Reelin is secreted by neurons in the external granular layer and deep cerebellar nuclei and binds to two high affinity extracellular receptors on Purkinje cells-the Very low density lipoprotein receptor (Vldlr) and apolipoprotein E receptor 2 (Apoer2). In mice null for either Reelin or double null for Vldlr and Apoer2, Purkinje cell clusters fail to disperse. Here we report that animals null for either Vldlr or Apoer2 individually, exhibit specific and parasagittally-restricted Purkinje cell ectopias. For example, in mice lacking Apoer2 function immunostaining reveals ectopic Purkinje cells that are largely restricted to the zebrin II-immunonegative population of the anterior vermis. In contrast, mice null for Vldlr have a much larger population of ectopic Purkinje cells that includes members from both the zebrin II-immunonegative and -immunopositive phenotypes. HSP25 immunoreactivity reveals that in Vldlr null animals a large portion of zebrin II-immunopositive ectopic cells are probably destined to become stripes in the central zone (lobules VI–VII). A small population of ectopic zebrin II-immunonegative Purkinje cells is also observed in animals heterozygous for both receptors (Apoer2+/−: Vldlr+/−), but no ectopia is present in mice heterozygous for either receptor alone. These results indicate that Apoer2 and Vldlr coordinate the dispersal of distinct, but overlapping subsets of Purkinje cells in the developing cerebellum

Long COVID: tackling a multifaceted condition requires a multidisciplinary approach.

This is the final version. Available from Elsevier via the DOI in this record.

Influence of Ni Catalyst Layer and TiN Diffusion Barrier on Carbon Nanotube Growth Rate

Dense, vertically aligned multiwall carbon nanotubes were synthesized on TiN electrode layers for infrared sensing applications. Microwave plasma-enhanced chemical vapor deposition and Ni catalyst were used for the nanotubes synthesis. The resultant nanotubes were characterized by SEM, AFM, and TEM. Since the length of the nanotubes influences sensor characteristics, we study in details the effects of changing Ni and TiN thickness on the physical properties of the nanotubes. In this paper, we report the observation of a threshold Ni thickness of about 4 nm, when the average CNT growth rate switches from an increasing to a decreasing function of increasing Ni thickness, for a process temperature of 700°C. This behavior is likely related to a transition in the growth mode from a predominantly “base growth” to that of a “tip growth.” For Ni layer greater than 9 nm the growth rate, as well as the CNT diameter, variations become insignificant. We have also observed that a TiN barrier layer appears to favor the growth of thinner CNTs compared to a SiO2 layer

Metamaterial bricks and quantization of meta-surfaces

Controlling acoustic fields is crucial in diverse applications such as loudspeaker design, ultrasound imaging and therapy or acoustic particle manipulation. The current approaches use fixed lenses or expensive phased arrays. Here, using a process of analogue-to-digital conversion and wavelet decomposition, we develop the notion of quantal meta-surfaces. The quanta here are small, pre-manufactured three-dimensional units—which we call metamaterial bricks—each encoding a specific phase delay. These bricks can be assembled into meta-surfaces to generate any diffraction-limited acoustic field. We apply this methodology to show experimental examples of acoustic focusing, steering and, after stacking single meta-surfaces into layers, the more complex field of an acoustic tractor beam. We demonstrate experimentally single-sided air-borne acoustic levitation using meta-layers at various bit-rates: from a 4-bit uniform to 3-bit non-uniform quantization in phase. This powerful methodology dramatically simplifies the design of acoustic devices and provides a key-step towards realizing spatial sound modulators