Particle interactions mediated by dynamical networks: assessment of macroscopic descriptions

We provide a numerical study of the macroscopic model of [3] derived from an agent-based model for a system of particles interacting through a dynamical network of links. Assuming that the network remodelling process is very fast, the macroscopic model takes the form of a single aggregation diffusion equation for the density of particles. The theoretical study of the macroscopic model gives precise criteria for the phase transitions of the steady states, and in the 1-dimensional case, we show numerically that the stationary solutions of the microscopic model undergo the same phase transitions and bifurcation types as the macroscopic model. In the 2-dimensional case, we show that the numerical simulations of the macroscopic model are in excellent agreement with the predicted theoretical values. This study provides a partial validation of the formal derivation of the macroscopic model from a microscopic formulation and shows that the former is a consistent approximation of an underlying particle dynamics, making it a powerful tool for the modelling of dynamical networks at a large scale

Millimeter-Wave Line Ratios and Sub-beam Volume Density Distributions

We explore the use of mm-wave emission line ratios to trace molecular gas density when observations integrate over a wide range of volume densities within a single telescope beam. For observations targeting external galaxies, this case is unavoidable. Using a framework similar to that of Krumholz and Thompson (2007), we model emission for a set of common extragalactic lines from lognormal and power law density distributions. We consider the median density of gas producing emission and the ability to predict density variations from observed line ratios. We emphasize line ratio variations, because these do not require knowing the absolute abundance of our tracers. Patterns of line ratio variations have the prospect to illuminate the high-end shape of the density distribution, and to capture changes in the dense gas fraction and median volume density. Our results with and without a high density power law tail differ appreciably; we highlight better knowledge of the PDF shape as an important area. We also show the implications of sub-beam density distributions for isotopologue studies targeting dense gas tracers. Differential excitation often implies a significant correction to the naive case. We provide tabulated versions of many of our results, which can be used to interpret changes in mm-wave line ratios in terms of changes in the underlying density distributions.Comment: 24 pages, 16 figure, Accepted for publication in the Astrophysical Journal, two online tables temporarily available at http://www.astronomy.ohio-state.edu/~leroy.42/densegas_table2.txt and http://www.astronomy.ohio-state.edu/~leroy.42/densegas_table3.tx

Dynamic Nonlocal Dielectric Metasurfaces: Tuning Collective Lattice Resonances via Substrate–Superstrate Permittivity Contrast

Contrary to local resonances of single nanostructures, collective (or nonlocal) resonances in periodic metasurfaces, such as surface lattice resonances (SLRs), can significantly enhance light–matter interaction, leading to higher spectral selectivity. The dynamic control of such nonlocal response represents an emerging field of research. While tuning of SLRs has been demonstrated in plasmonic metasurfaces, the use of dielectric metasurfaces provides additional conditions to control both reflectance and transmittance, with minimum absorption effects. A close-to-homogeneous environment is usually required to guarantee the excitation of SLRs. Here, we propose theoretically and demonstrate experimentally a practical strategy for the tuning of SLRs in dielectric metasurfaces when an arbitrary index mismatch is considered between substrate and superstrate. The approach is based on a generalized lattice sum theory that accounts for the presence of a substrate. Dynamic tuning of the SLRs in silicon metasurfaces placed on a substrate is achieved with a changeable superstrate via an optofluidic process. Two tuning mechanisms are revealed corresponding to shifting and damping of the SLR, depending on the superstrate–substrate refractive index contrast. The demonstrated dynamic manipulation of transmission and reflection may be exploited in dielectric metasurfaces for tunable spectral selectivity, sensing, or novel display technologies

Dynamic dielectric metasurfaces via control of surface lattice resonances in non-homogeneous environment

Dynamic control of metamaterials and metasurfaces is crucial for many photonic technologies, such as flat lenses, displays, augmented reality devices, and beam steering, to name a few. The dynamic response is typically achieved by controlling the phase and/or amplitude of individual meta-atom resonances using electro-optic, phase-change or nonlinear effects. Here, we propose and demonstrate a new practical strategy for the dynamic control of the resonant interaction of light with dielectric metasurfaces, exploiting the dependence of the interaction between meta-atoms in the array on the inhomogeneity of the surrounding medium. The revealed tuning mechanisms are based on the concept of the surface lattice resonance (SLR), the development of which strongly depends on the difference between permittivities of superstrate and substrate materials. We experimentally demonstrate surface lattice resonances in dielectric (Si) metasurfaces, and reveal two tuning mechanisms corresponding to shifting or damping of the SLR in optofluidic environment. The demonstrated dynamic tuning effect with the observed vivid colour changes may provide a dynamic metasurface approach with high spectral selectivity and enhanced sensitivity for sensors, as well as high-resolution for small pixel size displays.Comment: Main text: 10 pages, 4 figures. Supplementary information: 18 pages, 14 figure

Case report of ablative magnetic resonance-guided stereotactic body radiation therapy for oligometastatic mesenteric lymph nodes from bladder cancer

Several randomized trials have demonstrated that stereotactic body radiation therapy (SBRT) can significantly improve long-term clinical outcomes for patients with oligometastatic (OM) cancer, commonly defined as 1–5 metastatic lesions. Some lesions, especially those in the abdomen and pelvis, may not be appropriate candidates for receiving ablative dose if daily on-board computed tomography (CT) is used because of limited target lesion and normal anatomy visualization. Magnetic resonance imaging (MRI) inherently provides superior soft tissue delineation as compared to CT and only recently have MR-guided linear accelerators (LINACs) become commercially available. MR-LINACs can also perform daily online adaptive replanning based on the current day’s anatomy, further positioning this novel technology as a preferred means to safely deliver ablative dose, even to targets in anatomically challenging locations. Here we present the case of a 49-year-old man with bladder cancer who underwent cystectomy and developed metachronous disease in 2 mesenteric lymph nodes for which he received MR-guided SBRT with daily online adaptive replanning to a prescription dose of 50 Gy in 5 fractions. He achieved a significant radiographic response and did not experience significant treatment-related toxicity. We discuss unique advantages of MR guidance and novel applications, especially in the context of OM disease. Keywords: Bladder cancer; magnetic resonance imaging (MRI); radiosurgery; radiotherap

A Multi-Agent System Architecture for Smart Grid Management and Forecasting of Energy Demand in Virtual Power Plants

[EN] Recent technological advances in the power generation and information technologies areas are helping to change the modern electricity supply system in order to comply with higher energy efficiency and sustainability standards. Smart grids are an emerging trend that introduce intelligence in the power grid to optimize resource usage. In order for this intelligence to be effective, it is necessary to retrieve enough information about the grid operation together with other context data such as environmental variables, and intelligently modify the behavior of the network elements accordingly. This article presents a multi-agent system model for virtual power plants, a new power plant concept in which generation no longer occurs in big installations, but is the result of the cooperation of smaller and more intelligent elements. The proposed model is not only focused on the management of the different elements, but includes a set of agents embedded with artificial neural networks for collaborative forecasting of disaggregated energy demand of domestic end users, the results of which are also shown in this article.We would like to express our thanks to the coordinators of the project OptimaGrid for the information provided on MAS-based micro-grids, and the creators of a MAS INGENIAS methodology. This article has been partially funded by the project SociAAL (Social Ambient Assisted Living), supported by Spanish Ministry for Economy and Competitiveness, with grant TIN2011-28335-C02-01, by the Programa de Creacion y Consolidacion de Grupos de Investigacion UCM-Banco Santander for the group number 921354 (GRASIA group).Hernández, L.; Baladrón Zorita, C.; Aguiar Pérez, JM.; Carro, B.; Sanchez-Esguevillas, A.; Lloret, J.; Chinarro, D.... (2013). A Multi-Agent System Architecture for Smart Grid Management and Forecasting of Energy Demand in Virtual Power Plants. IEEE Communications Magazine. 51(1):106-113. https://doi.org/10.1109/MCOM.2013.6400446S10611351

Le portrait du roi : entre art, histoire, anthropologie et sémiologie

Dans la théorie des arts à l’époque moderne, le portrait du roi a un statut singulier : en tant que portrait, il dépend du dictat de la ressemblance au modèle naturel, qui l’éloigne de la noble quête de l’idéal, mais en tant que représentation du souverain, donc d’un personnage hors norme à la perfection incomparable, il a vocation d’être un chef-d’œuvre. De ce fait, le portrait du roi échappe, du moins dans la littérature encomiastique, au discrédit qui frappe progressivement le genre du por..

Por uma literatura antirracista: uma análise dos contos “no seu pescoço” e “os casamenteiros” de Chimamanda Ngozi Adichie

 No livro de contos intitulado No seu pescoço (2017), a escritora nigeriana Chimamanda Ngozi Adichie apresenta narrativas que abordam diversos problemas sociais, entre eles destacam-se a desigualdade de gênero, de classe, o racismo e a diáspora, temas que se entrelaçam ao longo dos contos compondo assim personagens plurais. Teremos como principal foco, a análise da representação feminina, visto que a mulher negra é duplamente marcada por opressões raciais e de gênero, dessa forma nos propomos a investigar como a escritora produziu personagens femininas que rompem com os estereótipos da mulher negra comumente retratados na literatura. Temos, como corpus de análise os contos “casamenteiros” e “no seu pescoço”. Para essa análise utilizaremos como embasamento teórico a crítica literária feminista de teóricas como Zolin (2009) Duarte (2003) Sholwalter (1994) e Spivak (2010) acrescentando também o pensamento de filosofas e teóricas sobre o feminismo negro como Djamila Ribeiro (2018) Carla Akotirene (2019) e Grada Kilomba (2020). Através dessa pesquisa buscamos ouvir as vozes das mulheres negras construídas a partir das vivências e locais de fala dessas mulheres, ampliando assim a multiplicidade de representações. Através dessa pesquisa foi possível concluir que os contos produzidos por Adichie suscita a reflexão sobre o racismo estrutural ao questionar e explorar situações comuns e cotidianas que geralmente apresentam o racismo de forma naturalizada, dessa forma os contos além de valorizarem a cultura africana, fornecem representatividade cultural e identitária contribuindo assim para a luta antirracista por meio dessa arma tão potente que é a literatura