Tiago França - Academia.edu (original) (raw)

Papers by Tiago França

Physical Review D

We study black hole binary mergers in certain cubic Horndeski theories of gravity, treating them ... more We study black hole binary mergers in certain cubic Horndeski theories of gravity, treating them fully non-linearly. In the regime of validity of effective field theory, the mismatch of the gravitational wave strain between Horndeski and general relativity (coupled to a scalar field) can be as large as 10 − 13% in the Advanced LIGO mass range. The initial data and coupling constants are chosen such the theory remains in the weakly coupled regime throughout the evolution. In all cases that we have explored, we observe that the waveform in the Horndeski theory is shifted by an amount much larger than the smallness parameter that controls the initial data. This effect is generic and may be present in other theories of gravity involving higher derivatives.

Classical and Quantum Gravity

We demonstrate the flexibility and utility of the Berger–Rigoutsos adaptive mesh refinement (AMR)... more We demonstrate the flexibility and utility of the Berger–Rigoutsos adaptive mesh refinement (AMR) algorithm used in the open-source numerical relativity (NR) code GRChombo for generating gravitational waveforms from binary black-hole (BH) inspirals, and for studying other problems involving non-trivial matter configurations. We show that GRChombo can produce high quality binary BH waveforms through a code comparison with the established NR code Lean. We also discuss some of the technical challenges involved in making use of full AMR (as opposed to, e.g. moving box mesh refinement), including the numerical effects caused by using various refinement criteria when regridding. We suggest several ‘rules of thumb’ for when to use different tagging criteria for simulating a variety of physical phenomena. We demonstrate the use of these different criteria through example evolutions of a scalar field theory. Finally, we also review the current status and general capabilities of GRChombo.

Journal of Open Source Software, 2021

O ecossistema de Startups e um ambiente criativo que visa promover o empreendedorismo e o nascime... more O ecossistema de Startups e um ambiente criativo que visa promover o empreendedorismo e o nascimento de negocios inovadores. Nesta complexa rede social, as atividades derivam da relacao de interdependencia e coevolucao entre atores com diferentes propositos, que compartilham recursos para atingir objetivos comuns. A dinâmica deste ambiente requer a compreensao dos interesses e capacidades de cada participante como forma de identificar convergencias e possiveis parcerias que possam ajudar no desenvolvimento de novos negocios. Este artigo apresenta um metodo para auxiliar na identificacao de interesses e vocacoes a partir de relacoes extraidas de interacoes em ferramentas de redes sociais em ecossistemas de startups.

2020 IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining (ASONAM), 2020

The 2018 Brazilian presidential elections were marked by a massive use of social media. Promising... more The 2018 Brazilian presidential elections were marked by a massive use of social media. Promising to improve user's quality of experience, social media recommend, filter and reorder the posts that will be shown to users. These social media filtering and personalization algorithms determine the flow of posts on the network and shape users' information diets. In this paper, we report measurements and findings from Facebook in the 2018 Brazilian presidential elections. To this aim, a reproducible methodology encompassing a method to identify publishers and candidates alignment and measurements to evaluate the posts selection carried out by Facebook filtering algorithms. The obtained results leverage the understanding of social media influence on the Brazilian elections. This knowledge can be useful in future elections around the world to ensure that the population exercises their right to choose their representatives in a democratic way.

Startups ecosystem is a creative environment to aim promoting entrepreneurship and the birth of i... more Startups ecosystem is a creative environment to aim promoting entrepreneurship and the birth of innovative business. In this complex social network, the activities derive from the relationship of interdependence and co-evolution between actors with different purposes, who share resources to achieve common goals. The dynamic of this environment requires understanding the interests and capacities of each participant as a way to identify convergences and possible partnerships that can help in the development of new businesses. This paper presents a method to assist the identification interests and vocations from relationships extracted from interactions in social network tools in startups ecosystems. To verify applicability, an empirical study was conducted from a conversation group by Whatsapp held by managers of technology business incubators from Brazilian federal institutes of education and research.

Classical and Quantum Gravity, 2020

We study spherically symmetric gravitational collapse in cubic Horndeski theories of gravity. By ... more We study spherically symmetric gravitational collapse in cubic Horndeski theories of gravity. By varying the coupling constants and the initial amplitude of the scalar field, we determine the region in the space of couplings and amplitudes for which it is possible to construct global solutions to the Horndeski theories. Furthermore, we identify the regime of validity of effective field theory as the sub-region for which a certain weak field condition remains small at all times. We evolve the initial data using the CCZ4 formulation of the Einstein equations and horizon penetrating coordinates without assuming spherical symmetry.

Anais do Brazilian Workshop on Social Network Analysis and Mining (BraSNAM), 2015

A área de Análise de Redes Sociais (ARS) é uma área multidisciplinar. Recentemente, temos presenc... more A área de Análise de Redes Sociais (ARS) é uma área multidisciplinar. Recentemente, temos presenciado a grande inserção e contribuição da comunidade de Ciência da Computação devido ao crescente número de dados sociais disponíveis e o aumento do uso de ferramentas de interação. Apesar disto, ainda há poucos registros quantitativos desse crescimento. O objetivo deste trabalho é mostrar esse movimento nas pesquisas científicas brasileiras, tendo como base a comunidade científica brasileira no domínio de Computação. Com esta análise é possível enxergar o crescimento da ARS no Brasil, assim como os principais pesquisadores e os eventos reconhecidos pelos pesquisadores da área.

Proceedings of the 31st Annual ACM Symposium on Applied Computing - SAC '16, 2016

Online social networks (OSN) have become very popular in the last years. People use it to tell wh... more Online social networks (OSN) have become very popular in the last years. People use it to tell what they are thinking and feeling. As these OSN became bigger and its content propagation is fast, they are commonly used as personal-update mechanism. Sometimes, the quantity, variety and quality of information spread in OSN are a problem when a person tries to use this kind of system to keeping yourself updated. Aiming to find relevant news related to users' current interests or news that could explain an event, we present a recommender system based on Twitter.

In the near future the number of physical devices (also called smart objects) connected to the in... more In the near future the number of physical devices (also called smart objects) connected to the internet will be massive. Those devices can be wireless sensors, mobile phones or any other electronic device of people's daily lives. The Web of Things (WoT) proposal is to integrate smart objects into the Web so that user will be able to access those physical objects via URLs, browse them, and reuse the resources provided by them in the building of composite Web applications, called mashups. This short course introduces the concepts and technologies involved in the WoT. Following, we present the underlying software architecture currently employed in WoT projects. Finally, we present practical examples of application development using the Sun SPOT platform.

This paper presents the Web2Compile WebIDE for Wireless Sen-sor Networks Application development ... more This paper presents the Web2Compile WebIDE for Wireless Sen-sor Networks Application development using TinyOS and NesC. Using Web2Compile, an user is able to generate a sensor image and to simulate their behaviour through TOSSIM simulator only using an updated browser. Web2Compile intends to eliminate the need of complex install procedures re-quired nowadays by Wireless Sensor Networks development environments. Resumo. Este trabalho apresenta a WebIDE Web2Compile para o desenvolvi-mento de aplicações para redes de sensores sem fio usando TinyOS e NesC. Usando Web2Compile, um usuário é capaz de gerar uma imagem do sensor e simular o seu comportamento através do simulador TOSSIM usando apenas um navegador atualizado. Web2Compile pretende eliminar necessidade de proce-dimentos de instalação complexos utilizados atualmente por ambientes de de-senvolvimento para Redes de Sensores sem fio.

IV Congresso Internacional de História, 2009

No século XIX, História e Literatura eram disciplinas próprias e com objetivos específicos. A His... more No século XIX, História e Literatura eram disciplinas próprias e com objetivos específicos. A História, influenciada pelo positivismo, trataria do factual em busca de uma verdade que pudesse ser detectada no interior do horizonte das fontes escritas. A crítica literária se ...

Cornea, 2002

Purpose. To describe the ocular lesions that occur after stings from hymenopteran insects. Method... more Purpose. To describe the ocular lesions that occur after stings from hymenopteran insects. Methods. We examined the ocular alterations in five patients who suffered ocular trauma from hymenopteran insect stings. Results. In 4 cases where the insect was identified as a wasp, all the patients presented with persistent corneal decompensation and two presented with total cataract, requiring surgical treatment. In the case of trauma by a bee sting, the patient presented with corneal edema and an inflammatory reaction of the anterior chamber with total regression of these alterations after clinical treatment. Conclusion. Although a rare occurrence, ocular trauma caused by hymenopteran insects can result in severe ocular alterations in humans.

Arquivos Brasileiros de Oftalmologia, 2002

Objetivo: Mostrar os resultados de avaliação, conduta e evolução com a população de pacientes por... more Objetivo: Mostrar os resultados de avaliação, conduta e evolução com a população de pacientes portadores de melanoma de coróide atendidos no período de 01/01/1994 a 01/01/2000 no Ambulatório de Retina e Vítreo da Universidade Federal de Uberlândia-MG. Métodos: Análise retrospectiva de 7 prontuários de pacientes com diagnóstico de melanoma de coróide, analisando: idade, sexo, cor, sintomas e duração, métodos de diagnóstico, tratamento realizado, tamanho e tipo do tumor e evolução. Resultados: Não existiu diferença em relação ao sexo e a idade média dos pacientes foi de 58,5 anos. O tumor predominou em brancos (66,5%) e baixa de acuidade visual foi o sintoma mais freqüente (66,5%). O diagnóstico deveu-se principalmente à oftalmoscopia indireta (66,5%) e todos realizaram ultrasonografia (USG). Todos pacientes foram submetidos a tratamento cirúrgico, pois apresentavam tumores grandes (maior diâmetro basal superior a 12 mm à USG). O tipo mais freqüente foi o de celularidade mista (50%) e o tamanho médio dos tumores foi de 20,50 mm de maior diâmetro basal e 15,16 mm de espessura. O seguimento variou entre 8 meses e 5 anos. Dois pacientes apresentaram metástase à distância e evoluíram a óbito. Conclusões: Todos pacientes foram diagnosticados com o tumor em um estádio avançado, necessitando tratamento cirúrgico, com 2 pacientes desenvolvendo metástase à distância e evoluindo a óbito. Ressaltamos a importância da oftalmoscopia indireta em função da malignidade do tumor e da possibilidade do diagnóstico precoce, ampliando as opções de tratamento e melhorando seus resultados.

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1 Programa de Pós-Graduação em Análise e Modelagem de Sistemas Ambientais Universidade Federal de... more 1 Programa de Pós-Graduação em Análise e Modelagem de Sistemas Ambientais Universidade Federal de Minas Gerais - IGC/UFMG Belo Horizonte - MG, Brasil tiagofmlyahoo.com.br ... 2 Departamento de Cartografia Universidade Federal de Minas Gerais UFMG Belo ...