Extragradient with Positive Momentum is Optimal for Games with Cross-Shaped Jacobian Spectrum

The extragradient method has recently gained increasing attention, due to its convergence behavior on smooth games. In $n$-player differentiable games, the eigenvalues of the Jacobian of the vector field are distributed on the complex plane, exhibiting more convoluted dynamics compared to classical (i.e., single player) minimization. In this work, we take a polynomial-based analysis of the extragradient with momentum for optimizing games with \emph{cross-shaped} Jacobian spectrum on the complex plane. We show two results. First, based on the hyperparameter setup, the extragradient with momentum exhibits three different modes of convergence: when the eigenvalues are distributed $i)$ on the real line, $ii)$ both on the real line along with complex conjugates, and $iii)$ only as complex conjugates. Then, we focus on the case $ii)$, i.e., when the eigenvalues of the Jacobian have \emph{cross-shaped} structure, as observed in training generative adversarial networks. For this problem class, we derive the optimal hyperparameters of the momentum extragradient method, and show that it achieves an accelerated convergence rate

L’intégration, à la jonction du discours normatif et de l’expérience vécue : des demandeurs d’asile s’expriment

Cet article met en relief les représentations que se font des demandeurs d’asile, acceptés comme réfugiés à Montréal, du processus d’intégration et vise à intégrer leur discours dans les discussions et les débats en cours au sein des sphères académiques et institutionnelles. On y propose une réflexion sur la négociation qu’impliquent les processus d’intégration entre le discours normatif véhiculé dans la société d’accueil et les conceptions subjectives issues des expériences vécues. Nos observations permettent d’aborder quelques implications pour la pratique du travail social effectué auprès de ces populations et insiste sur l’importance pour les intervenants d’utiliser un cadre d’analyse qui privilégie une vision globale des processus d’intégration considérant, non seulement des indicateurs objectifs, mais également des indicateurs subjectifs et qualitatifs.This paper highlights the representations of asylum seekers, accepted as refugees in Montreal, on the concept of integration and seeks to integrate their narratives in the discussions and ongoing debates within the academic and institutional spheres. We propose a reflection on the negotiation involved in the integration process, between the normative discourse promoted in the host society and the subjective conceptions that emerge from lived experiences. Our observations enable us to tackle some issues for social work practice with these groups and stresses the importance of using an analytical framework that emphasizes a holistic view of integration processes that incorporates not only objective data, but also subjective and qualitative indicators

A hybrid Si@FeSiy/SiOx anode structure for high performance lithium-ion batteries via ammonia-assisted one-pot synthesis

Synthesised via planetary ball-milling of Si and Fe powders in an ammonia (NH3) environment, a hybrid Si@FeSiy/SiOx structure shows exceptional electrochemical properties for lithium-ion battery anodes, exhibiting a high initial capacity of 1150 mA h g−1 and a retention capacity of 880 mA h g−1 after 150 cycles at 100 mA g−1; and a capacity of 560 mA h g−1 at 4000 mA g−1. These are considerably high for carbon-free micro-/submicro-Si-based anodes. NH3 gradually turns into N2 and H2 during the synthesis, which facilitates the formation of highly conductive FeSiy (y = 1, 2) phases, whereas such phases were not formed in an Ar atmosphere. Milling for 20–40 h leads to partial decomposition of NH3 in the atmosphere, and a hybrid structure of a Si core of mixed nanocrystalline and amorphous Si domains, shelled by a relatively thick SiOx layer with embedded FeSi nanocrystallites. Milling for 60–100 h results in full decomposition of NH3 and a hybrid structure of a much-refined Si-rich core surrounded by a mantle of a relatively low level of SiOx and a higher level of FeSi2. The formation mechanisms of the SiOx and FeSiy phases are explored. The latter structure offers an optimum combination of the high capacity of a nanostructural Si core, relatively high electric conductivity of the FeSiy phase and high structural stability of a SiOx shell accommodating the volume change for high performance electrodes. The synthesis method is new and indispensable for the large-scale production of high-performance Si-based anode materials

Le partage de quels savoirs ? Les articles Wikipédia comme objets-frontières

Wikipédia se présente comme un projet d’encyclopédie collective, un espace auquel chacun peut contribuer dans la mesure où ses principes fondateurs et ses règles sont respectés. Dans cet article, nous réfléchissons à notre intégration et à notre contribution aux communautés éditoriales de Wikipédia. Nous avons modifié et créé une série d’articles Wikipédia reliés à la thématique du vieillissement afin qu’ils incluent les études critiques et culturelles du vieillissement. Le partage en ligne de ce type de connaissances nous semble important, voire nécessaire, puisque ces études restent souvent sous-représentées en dehors des milieux universitaires. Remarquant de telles lacunes dans Wikipédia, nous avons saisi l’occasion de contribuer à ce commun des connaissances et d’étudier les questions de gouvernance qui ont émergé au fil de nos contributions. Au-delà d’un exercice de vulgarisation, notre excursion dans le monde de Wikipédia nous a permis de constater que certaines entrées agissent comme des objets-frontières, des lieux de contestation entre différentes communautés de pratiques. Pour élaborer notre propos, nous nous concentrons sur deux cas, celui du Centre for Women, Ageing and Media dans Wikipédia en anglais et celui de Technologies et vieillissement dans Wikipédia en français.Wikipedia promotes itself as a community that anyone can join as long as they know the rules. In this paper, we reflect on our attempt to join this community and to edit entries on age and ageing so that they include an intersectional perspective. Sharing our knowledge seemed necessary because feminist and ageing studies often stay underrepresented outside the academy. Noticing such gaps in Wikipedia, we decided to contribute to this knowledge common and attend to issues of governance that came up during our interventions. Rather than being a simple exercise in making academic research “vernacular,” our excursion into the world of writing Wikipedia entries reveals how certain entries act as boundary objects, sites of contestation between different communities of practice. We analyze the discussions around the creation of entries for the Centre for Women, Ageing and Media, and for Technologies et vieillissement.Wikipedia se presenta como un proyecto de enciclopedia colectiva, un espacio en el que todos pueden contribuir, siempre y cuando respeten sus principios y reglas fundamentales. En este artículo, las autoras reflexionan sobre la integración y la contribución a las comunidades editoriales de Wikipedia. Para ello se han creado y editado y creado una serie de artículos de Wikipedia relacionados con el envejecimiento desde el punto de vista de los estudios críticos y culturales. El intercambio en línea de este tipo de conocimiento es importante, incluso necesario, ya que, a menudo, estos estudios permanecen subrepresentados en el exterior de la academia. Al notar tales deficiencias en Wikipedia, se aprovechó la oportunidad para contribuir a este conocimiento común y para estudiar los problemas de gobernabilidad que surgieron de dichas contribuciones. Más allá de un ejercicio de divulgación científica, el viaje al mundo de Wikipedia ha permitido observar que algunas entradas actúan como objetos fronterizos y lugares de disputa entre diferentes comunidades. Para realizar dicho objetivo, se analizan dos casos: el del Centre for Women, Ageing and Media, en Wikipedia en inglés, y el de Technologies et vieillissement, en Wikipedia, en francés

Board Games for Health: A Systematic Literature Review and Meta-Analysis

Nondigital board games are being used to engage players and impact outcomes in health and medicine across diverse populations and contexts. This systematic review and meta-analysis describes and summarizes their impact based on randomized and nonrandomized controlled trials. An electronic search resulted in a review of n = 21 eligible studies. Sample sizes ranged from n = 17 to n = 3110 (n = 6554 total participants). A majority of the board game interventions focused on education to increase health-related knowledge and behaviors (76%, n = 16). Outcomes evaluated included self-efficacy, attitudes/beliefs, biological health indicators, social functioning, anxiety, and executive functioning, in addition to knowledge and behaviors. Using the Cochrane Collaboration tool for assessing bias, most studies (52%, n = 11) had an unclear risk of bias (33% [n = 7] had a high risk and 14% [n = 3] had a low risk). Statistical tests of publication bias were not significant. A random-effects meta-analysis showed a large average effect of board games on health-related knowledge (d* = 0.82, 95% confidence interval; CI [0.15–1.48]), a small-to-moderate effect on behaviors (d* = 0.33, 95% CI [0.16–0.51]), and a small-to-moderate effect on biological health indicators (d* = 0.37, 95% CI [0.21–0.52]). The findings contribute to the literature on games and gamified approaches in healthcare. Future research efforts should aim for more consistent high scientific standards in their evaluation protocols and reporting methodologies to provide a stronger evidence base

Effects of Spaceflight on Human Induced Pluripotent Stem Cell-Derived Cardiomyocyte Structure and Function.

With extended stays aboard the International Space Station (ISS) becoming commonplace, there is a need to better understand the effects of microgravity on cardiac function. We utilized human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) to study the effects of microgravity on cell-level cardiac function and gene expression. The hiPSC-CMs were cultured aboard the ISS for 5.5 weeks and their gene expression, structure, and functions were compared with ground control hiPSC-CMs. Exposure to microgravity on the ISS caused alterations in hiPSC-CM calcium handling. RNA-sequencing analysis demonstrated that 2,635 genes were differentially expressed among flight, post-flight, and ground control samples, including genes involved in mitochondrial metabolism. This study represents the first use of hiPSC technology to model the effects of spaceflight on human cardiomyocyte structure and function