FreeCell and Other Stories

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Exceptional Mathematics Teachers: What the Learners Think

The purpose of this study was to determine high school learners’ perceptions of what makes an exceptional mathematics teacher. The author was a pre-service teacher serving her clinical teaching internship in a high school mathematics classroom in which Precalculus, Pre-AP Precalculus, and AP Calculus were taught. For this study, data was collected through a student survey, one-on-one interviews, and focus group interviews with students. The data was analyzed using the constant comparative method. Four major themes emerged from the data, including the significance of a teacher’s attitude, the importance of a teacher’s desire to help and teach learners, whether or not a teacher teaches well, and how well teachers know their learners and have relationships with them

The Information Mapping Board Game: a Collaborative Investigation of Asylum Seekers and Refugees’ Information Practices in England, UK

Introduction. This paper discusses the use of an information mapping board game for collaboratively identifying information practices of a small group of asylum seekers and refugees in the North East of England, UK. Method. Drawing on participatory visual methods, an original information mapping board game was designed. Analysis. Qualitative results are discussed and analysed using grounded theory, constant comparative analysis, and situational mapping. Results. The use of an information mapping board game allows participants going through the asylum process to become actively involved in mapping and sharing their own information practices, sources and barriers within a playful collaborative environment. It enables participants to become aware of their acquired information literacy by sharing knowledge, and to adapt the game to reflect their needs and knowledge. Conclusion. This study indicates that participatory techniques such as the information mapping board game have the potential to engage hard to reach populations in the research process, to foster their agency, confidence, and capacities, and to inform actions at a local level

Conception et évaluation d’un nouveau système de transfection ciblée, basé sur l’utilisation du système E/Kcoil

Actuellement le polyéthylènimine (PEI) est l’agent de transfection transitoire le plus utilisé par l’industrie pharmaceutique pour la production de protéines recombinantes à grande échelle par les cellules de mammifères. Il permet la condensation de l’ADN plasmidique (ADNp) en formant spontanément des nanoparticules positives appelées polyplexes, lui procurant la possibilité de s’attacher sur la membrane cellulaire afin d’être internalisé, ainsi qu’une protection face aux nucléases intracellulaires. Cependant, alors que les polyplexes s’attachent sur la quasi-totalité des cellules seulement 5 à 10 % de l’ADNp internalisé atteint leur noyau, ce qui indique que la majorité des polyplexes ne participent pas à l’expression du transgène. Ceci contraste avec l’efficacité des vecteurs viraux où une seule particule virale par cellule peut être suffisante. Les virus ont évolués afin d’exploiter les voies d’internalisation et de routage cellulaire pour exprimer efficacement leur matériel génétique. Nous avons donc supposé que l’exploitation des voies d’internalisation et de routage cellulaire d’un récepteur pourrait, de façon similaire à plusieurs virus, permettre d’optimiser le processus de transfection en réduisant les quantités d’ADNp et d’agent de transfection nécessaires. Une alternative au PEI pour transfecter les cellules de mammifèreest l’utilisation de protéines possédant un domaine de liaison à l’ADNp. Toutefois, leur utilisation reste marginale à cause de la grande quantité requise pour atteindre l’expression du transgène. Dans cette étude, nous avons utilisé le système E/Kcoil afin de cibler un récepteur membranaire dans le but de délivrer l’ADNp dans des cellules de mammifères. Le Ecoil et le Kcoil sont des heptapeptides répétés qui peuvent interagir ensemble avec une grande affinité et spécificité afin de former des structures coiled-coil. Nous avons fusionné le Ecoil avec des protéines capables d’interagir avec l’ADNp et le Kcoil avec un récepteur membranaire que nous avons surexprimé dans les cellules HEK293 de manière stable. Nous avons découvert que la réduction de la sulfatation de la surface cellulaire permettait l’attachement ciblé sur les cellules par l’intermédiaire du système E/Kcoil. Nous démontrons dans cette étude comment utiliser le système E/Kcoil et une protéine interagissant avec l’ADNp pour délivrer un transgène de manière ciblée. Cette nouvelle méthode de transfection permet de réduire les quantités de protéines nécessaires pour l’expression du transgène.Pharmaceutical industry often employs polyethylenimine (PEI) for large scale protein production processes by transient transfection of mammalian cells. PEI condenses plasmid DNA (pDNA) by spontaneously forming positive nanoparticles known as polyplexes. Condensed pDNA is favoured for cell surface binding, internalization and protection from intracellular nucleases. While most of the cells efficiently uptake polyplexes, only 5 to 10% of captured pDNA reaches the nucleus for transgene expression. This suggests that polyplexes are hampered in their ability to route and to translocate to the nucleus necessitating large amounts of polyplexes to achieve high expression levels. By contrast, many viruses can efficiently transduce cells with only one or a few viral genome copies. Viruses have evolved to exploit cellular internalization and routing properties to express their own genetic material. We hypothesized that less pDNA would be used in an optimized transfection process if we exploited the internalization and routing properties that viruses use. DNA binding proteins could be used as an alternative to PEI to transfect mammalian cells. However, their usage is marginal due to the large protein quantities required to bind pDNA for transgene expression. If less pDNA is used less binding protein is needed. In this study, we used the E/Kcoil system to target a membrane receptor to deliver pDNA in mammalian cells. The Ecoil and Kcoil are two repeated heptapeptides which interact with a high affinity and specificity to form coiled-coil structures. We fused the Ecoil with a recombinant pDNA-binding protein. The Kcoil was fused to a stably-expressed membrane receptor in HEK293 cells. We discovered that low sulfation of the cell surface reduced non-specific binding of the pDNA:protein complex and permitted targeted binding via the E/Kcoil interaction. We demonstrate how to use recombinant pDNA-binding protein and the E/Kcoil system for targeted transgene delivery. This newly developed system provides a new transfection method, with reduced pDNA-binding protein quantities needed to achieve transgene expression

Cherchez la femme

Tandis que l\u27on s\u27interroge sur la véritable nature de l\u27appel à contribution de Wikipédia à l\u27adresse des bibliothécaires, certains d\u27entre eux à Lyon , ont déjà renversé cette proposition au profit de la bibliothèque, faisant de la participation à l\u27encyclopédie en ligne un thème d\u27atelier plébiscité

Low-Voltage Capacitor Electrical Discharge Consolidation of Iron Powder

Commercially pure iron powder has been processed by the capacitor electrical discharge consolidation technique. This consolidation technique applies an external pressure and, at the same time, heats a metallic powder mass by the Joule effect of a high-voltage and high-intensity electric current. In this work, a capacitor charged at low voltage has been used instead. The effect of the initial porosity of the Fe powder mass, i.e., of the precompaction pressure, and the number of discharges from the capacitor have been studied. The densification and remaining porosity, the sintering level, the Vickers microhardness, and the electrical resistivity of the sintered compacts have been studied. Compacts sintered by the conventional powder metallurgy route of cold pressing and furnace sintering were also prepared for comparison. Results show that a high initial porosity provides a high electrical resistance in the powder column, a necessary requisite for the Joule effect to increase densification with the number of discharges. Thus, the final porosity decreases to 0.22 after 50 discharges in the powder mass with an initial porosity of 0.30. With this initial porosity, the sintering process increases Vickers microhardness from 29 to 51 HV10 and decreases the electrical resistivity of the powder mass from 3.53 × 10−2 to 5.38 × 10−4 Ω·m. An initial porosity of 0.2 does not make the compacts densify, but a certain bond between particles is attained, increasing microhardness and decreasing electrical resistivity as the number of discharges increases. Lower initial porosities make the powder mass behave as an electrical conductor with no appreciable changes even after 50 electrical dischargesThis research was funded by Junta de Andalucía, grant to the Research Group TEP-971 and the University of Seville Research Funding Program, grant number 2020/0000064

Alexis Rappas, Cyprus in the 1930s. British Colonial Rule and the Roots of the Cyprus Conflict, Londres, I.B. Tauris, 2014, 254 p.

Dans le prolongement de sa thèse et de précédents articles portant sur l’histoire de Chypre dans les années 1930, Alexis Rappas propose une synthèse développée de ses travaux avec cet ouvrage. S’inscrivant dans une réécriture récente de l’histoire chypriote ottomane et britannique, dont il connaît parfaitement les contours et les débats, Alexis Rappas adopte, comme ses pairs et devanciers immédiats, tels Robert Holland, préfacier de son livre, une perspective résolument comparatiste en croisa..

A reading of latin american avant-garde through the decolonial lense: Alejandro Xul Solar and Joaquín Torres-García, from the ineluctable modern eurocentrism to the search for a communication "other"

This dissertation revisits modern art in Latin America. The paradoxes of the Latin American avant-garde discourse, which uses modern ideals in order to create a culturally decolonised identity freed from Eurocentrism, are confronted to the theory defended by the decolonial thinking according to which coloniality is inherent to modernity. Through the examination of the texts and paintings of Alejandro Xul Solar and Joaquín Torres-García, two artists who participated in the renewal of the vanguard scenes of Argentina and Uruguay between the 1920s and the 1940s, my aim is to understand whether modern art is – as decolonial thinkers imply – doomed to reproduce coloniality, or if it can conversely allow to undermine it. The analysis of their works first shows their discourses as entrenched in a narrative of modernity that indeed proves to be a fallacious mirror of coloniality. The focus on abstraction and on the thinking and communicating ‘other’ it produces, nevertheless leads me to question the decolonial premise. I finally conclude that the aesthetic freedom brought by the avant-garde allowed Solar and Torres-García to, in some cases, avoid reproducing coloniality, but does however not make them decolonial artists

Estudio del comportamiento a corrosión de sinterizados de aluminio con formación de carburos y nitruros in situ

Las necesidades cada vez más exigentes de materiales de alta resistencia específica, usados principalmente en la industria aeronáutica, hacen que se hayan producido grandes avances en la fabricación de materiales compuestos de alta resistencia procesados mediante aleado mecánico. Si bien en el procesado inicial de los mismos siempre ha primado obtener, con el menor peso, las mejores propiedades mecánicas, una buena combinación de estas propiedades y frente a corrosión es de gran importancia en muchas aplicaciones. La finalidad principal de este estudio es la fabricación de piezas pulvimetalúrgicas de base aluminio reforzadas por dispersión de carburos y nitruros formados in situ mediante aleado mecánico. Se han determinado las relaciones existentes entre sus propiedades mecánicas y su comportamiento a corrosión, y la composición y estructura de las mismas. Los materiales se obtienen mediante un procesado primario de molienda de alta energía, para la preparación de los polvos de distinta composición, seguido de un procesado de consolidación pulvimetalúrgico (PM). El polvo de partida base aluminio con distinta composición se obtendrá por mecanosíntesis, moliendo polvo de Al comercial y cantidades variables de cera y cobre en vacío o atmósfera nitrurante (mediante atmósfera de amoniaco gaseoso). La consolidación de los mismos se realizará mediante el proceso PM convencional de prensado uniaxial en frío seguido de un proceso de sinterización. Se pretende que la presencia de fases cerámicas, como los nitruros y carburos formados, además de favorecer las propiedades mecánicas de estos materiales, proporcione un comportamiento a corrosión similar al presentado por materiales comerciales no pulvimetalúrgicos. Con el fin de evaluar cómo afecta la composición de los materiales obtenidos a las propiedades mecánicas y la resistencia a la corrosión de los mismos, se han realizado moliendas de 10 horas a 500 rpm con contenidos variables de cera y cobre en vacío, y otras durante 5 horas con contenidos variables de cera en atmósfera de amoniaco. Los resultados obtenidos muestran una clara relación entre la composición de los mismos y las propiedades obtenidas, habiéndose conseguido materiales de alta resistencia con un comportamiento a corrosión bastante satisfactorio, más aun teniendo en cuenta que habitualmente los materiales elaborados por vía PM presentan una resistencia a la corrosión bastante mermada respecto a los obtenidos por otros métodos