Individual accessibility and segregation on activity spaces: an agent-based modelling approach

One of the main challenges of cities is the increasing social inequality imposed by the way population groups, jobs, amenities and services, as well as the transportation infrastructure, are distributed across urban space. In this thesis, the concepts of accessibility and segregation are used to study these inequalities. They can be defined as the interaction of individuals with urban opportunities and with individuals from other population groups, respectively. Interactions are made possible by people’s activities and movement within a city, which characterise accessibility and segregation as inherently dynamic and individual-based concepts. Nevertheless, they are largely studied from a static and place-based perspective. This thesis proposes an analytical and exploratory framework for studying individual-based accessibility and segregation in cities using individuals’ travel trajectories in space and time. An agent-based simulation model was developed to generate individual trajectories dynamically, employing standard datasets such as census and OD matrices and allowing for multiple perspectives of analysis by grouping individuals based on their attributes. The model’s ability to simulate people’s trajectories realistically was validated through systematic sensitivity tests and statistical comparison with real-world trajectories from Rio de Janeiro, Brazil, and travel times from London, UK. The approach was applied to two exploratory studies: São Paulo, Brazil, and London, UK. The first revealed inequalities in accessibility by income, education and gender and also unveiled within-group differences beyond place-based patterns. The latter explored ethnic segregation, unveiling patterns of potential interaction among ethnic groups in the urban space beyond their residential and workplace locations. Those studies demonstrated how inequality in accessibility and segregation can be studied both at large metropolitan scales and at fine level of detail, using standard datasets, with modest computational requirements and ease of operationalisation. The proposed approach opens up avenues for the study of complex dynamics of interaction of urban populations in a variety of urban contexts

Individual accessibility and segregation on activity spaces: an agent-based modelling approach

One of the main challenges of cities is the increasing social inequality imposed by the way population groups, jobs, amenities and services, as well as the transportation infrastructure, are distributed across urban space. In this thesis, the concepts of accessibility and segregation are used to study these inequalities. They can be defined as the interaction of individuals with urban opportunities and with individuals from other population groups, respectively. Interactions are made possible by people’s activities and movement within a city, which characterise accessibility and segregation as inherently dynamic and individual-based concepts. Nevertheless, they are largely studied from a static and place-based perspective. This thesis proposes an analytical and exploratory framework for studying individual-based accessibility and segregation in cities using individuals’ travel trajectories in space and time. An agent-based simulation model was developed to generate individual trajectories dynamically, employing standard datasets such as census and OD matrices and allowing for multiple perspectives of analysis by grouping individuals based on their attributes. The model’s ability to simulate people’s trajectories realistically was validated through systematic sensitivity tests and statistical comparison with real-world trajectories from Rio de Janeiro, Brazil, and travel times from London, UK. The approach was applied to two exploratory studies: São Paulo, Brazil, and London, UK. The first revealed inequalities in accessibility by income, education and gender and also unveiled within-group differences beyond place-based patterns. The latter explored ethnic segregation, unveiling patterns of potential interaction among ethnic groups in the urban space beyond their residential and workplace locations. Those studies demonstrated how inequality in accessibility and segregation can be studied both at large metropolitan scales and at fine level of detail, using standard datasets, with modest computational requirements and ease of operationalisation. The proposed approach opens up avenues for the study of complex dynamics of interaction of urban populations in a variety of urban contexts

Updated cardiovascular prevention guideline of the Brazilian Society of Cardiology: 2019

Sem informação113478788

Simulation of urban growth in cellular spaces with an accessibility measure: method and case study in southern cities of Rio Grande do Sul.

This work is committed to verify the capability of an accessibility measure to identify areas prone to high urban growth, related to the presence of higher locational advantages. This issue is addressed via urban modeling, using techniques of urban growth simulation based on cellular automata. Accessibility measures have proven effective in studies about the urbanized space and the natural landscape, with theoretical and methodological similarities. An expanded version of one of such measures is proposed, called Weighted Accessibility, considering the characteristics of the surrounding city, both natural and modified by human action. This measure was implemented in a cellular environment and used in a dynamic urban growth model. The model was tested in southern Rio Grande do Sul cities. Two types of constraints external to the city were considered: a) environmental factors, represented by the topography and hydrography b) anthropic factors, represented by the city traffic network. These conditions were grouped into four scenarios: a) absence of external factors; b) presence of anthropic factors; c) presence of environmental factors; d) simultaneous presence of environmental and anthropic factors. Evaluations were made using techniques of cell-by-cell comparison and fuzzy similarity. The best results were obtained in simulations that considered the influence of environmental factors alone or in combination with anthropic factors. These results suggest that city surroundings have an important influence on the urban growth process and that this influence can be identified by the accessibility measure at issue.Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPESEste trabalho propõe-se a verificar a capacidade de uma medida de acessibilidade para identificar áreas de maior tendência de crescimento urbano, vinculadas à presença de maiores vantagens locacionais. Esse tema é abordado através do uso de modelagem urbana, utilizando técnicas de simulação dinâmica de crescimento urbano baseadas em autômatos celulares. Medidas de acessibilidade têm se mostrado eficazes em estudos tanto do espaço urbanizado quanto da paisagem natural, que apresentam semelhanças teóricas e metodológicas. Dessa forma, propõe-se uma versão expandida da medida, chamada de Acessibilidade Ponderada, considerando as características do entorno da cidade, tanto naturais quanto modificadas pela ação humana. Esta medida foi implementada em ambiente celular e utilizada em um modelo dinâmico de simulação de crescimento urbano. O modelo foi testado em cidades do sul do Rio Grande do Sul. Foram considerados dois tipos de condicionantes externos à cidade: a) fatores ambientais, representados pela hidrografia e topografia; b) fatores antrópicos, representados pelo sistema viário de acesso à cidade. Esses condicionantes foram agrupados em quatro cenários: a) ausência de fatores externos; b) presença de fatores antrópicos; c) presença de fatores ambientais; d) presença de fatores antrópicos e ambientais simultaneamente. As avaliações foram feitas utilizando técnicas de comparação célula a célula e de comparação por semelhança difusa (fuzzy). Os melhores resultados foram obtidos nas simulações que consideraram a influência dos fatores ambientais isoladamente ou em conjunto com os fatores antrópicos. Esses resultados indicam que a área do entorno da cidade exerce importante influência no processo de crescimento urbano e que essa influência pode ser identificada pela medida de acessibilidade

COMPARATIVE ANALYSIS BETWEEN K-MEANS, FCM, AND CKMEANS ALGORITHMS FOR IMAGE SEGMENTATION: COMPARATIVE ANALYSIS BETWEEN K-MEANS, FCM, AND CKMEANS ALGORITHMS FOR IMAGE SEGMENTATION

Clustering algorithms are often used for image segmentation, aiming to group pixels by their similarity and uniformity. This process is useful to detect and highlight important areas of an image, making its analysis easier in several applications such as remote sensing and medical diagnosis. This paper have the main objective to compare the K-Means hard clustering algorithm to the FCM and ckMeans fuzzy clustering algorithms in image segmentation applications, using the R statistical programming language for analysis and visualization of the results. Uncertainty in the clustering process is discussed via the use of the alpha-cut parameter. Two experiments were conducted, using an image from an open database and an aerial image of a Catarinense city. It was found that the three methods produced similar results, when crisp clusters were considered. Fuzzy membership results of FCM and ckMeans were also compared, and it was found that, although very similar, ckMeans produced slightly lower levels of uncertainty than FCM. It was found that K-Means presents the best computational performance among the algorithms compared, which is expected due to its crisp nature. Among the fuzzy algorithms compared, ckMeans presented better performance, and FCM required less memory.Clustering algorithms are often used for image segmentation, aiming to group pixels by their similarity and uniformity. This process is useful to detect and highlight important areas of an image, making its analysis easier in several applications such as remote sensing and medical diagnosis. This paper have the main objective to compare the K-Means hard clustering algorithm to the FCM and ckMeans fuzzy clustering algorithms in image segmentation applications, using the R statistical programming language for analysis and visualization of the results. Uncertainty in the clustering process is discussed via the use of the alpha-cut parameter. Two experiments were conducted, using an image from an open database and an aerial image of a Catarinense city. It was found that the three methods produced similar results, when crisp clusters were considered. Fuzzy membership results of FCM and ckMeans were also compared, and it was found that, although very similar, ckMeans produced slightly lower levels of uncertainty than FCM. It was found that K-Means presents the best computational performance among the algorithms compared, which is expected due to its crisp nature. Among the fuzzy algorithms compared, ckMeans presented better performance, and FCM required less memory.

Should spinocerebellar ataxias be included in the differential diagnosis for Huntington's diseases-like syndromes?

In this article, we describe three patients with different spinocerebellar ataxia (SCA) subtypes presenting with unusual movement disorders predominantly characterized by choreoathetosis, which, together with their autosomal dominant pattern of inheritance, resembled the Huntington-like syndromes. From a large SCA cohort, we have observed chorea in 1/35 SCA2, 1/112 SCA3/MJD, and 1/30 SCA7 patients. Twenty-eight patients with SCA1, 11 patients with SCA6, and 3 patients with SCA10 were also evaluated, and none of them presented chorea. We provide a brief report of the three cases, with a video demonstrating chorea. Although a debate regarding the frequency of chorea in SCA patients is a fact, its occurrence, together with the autosomal dominant pattern of inheritance, clearly imposes SCA in the differentials of Huntington-like syndromes. There is some debate about what to include in a list of Huntington-like disorders, with several review articles about Huntington-like syndromes not including SCA in the differential diagnosis, except for SCA17. We believe that SCAs at least. SCA1, SCA2, SCA3/MJD, SCA7 and DRPLA should be thought in the diagnostic workout of at least the atypical cases, such as those presented in this report. (C) 2014 Elsevier B.V. All rights reserved.Universidade Federal de São Paulo, Dept Neurol, Ataxia Unit, São Paulo, BrazilHosp Clin Porto Alegre, Dept Biochem, Porto Alegre, RS, BrazilHosp Clin Porto Alegre, Med Genet Serv, Porto Alegre, RS, BrazilHosp Clin Porto Alegre, Dept Internal Med, Porto Alegre, RS, BrazilUniversidade Federal de São Paulo, Dept Neurol, Ataxia Unit, São Paulo, BrazilWeb of Scienc