This thesis describes and analyzes the location and size distribution of artand entertainment establishments and metropolitan regions in the UnitedStates. The included sectors are sound recording, motion picture and video,book and newspaper publishing as well as the live performing arts. Their sizeis analyzed by total employment and brought in context to their respectivemarkets and the rank-size rule. The results are interpreted within the economictraits specific to the art and entertainment industry.The results show that most analyzed sectors are over proportionally concentratedin one location, making it the center for these activities. In addition, thesize distribution in all sectors except sound recording follows Zipfs law to agreat extend. Explanations for this can be found in lock-in mechanisms overtime and classic agglomeration advantages.

Conventionally geographic data produced and disseminated by the national mapping agencies are used for studying various urban issues. These data are not commonly available or accessible, but also are criticized for being expensive. However, this trend is changing along with the rise of Volunteered Geographic Information (VGI). VGI, known as user generated content, is the geographic data collected and disseminated by individuals at a voluntary basis. So far, a huge amount of geographic data has been collected due to the increasing number of contributors and volunteers. More importantly, they are free and accessible to anyone.   There are many formats of VGI such as Wikimapia, Flickr, GeoNames and OpenStreetMap (OSM). OSM is a new mapping project contributed by volunteers via a wiki-like collaboration, which is aimed to create free, editable map of the entire world. This thesis adopts OSM as the main data source to uncover the hidden patterns around the urban systems. We investigated some fundamental issues such as city rank size law and the measurement of urban sprawl. These issues were conventionally studied using Census or satellite imagery data.   We define the concept of natural cities in order to assess city size distribution. Natural cities are generated in a bottom up manner via the agglomeration of individual street nodes. This clustering process is dependent on one parameter called clustering resolution. Different clustering resolutions could derive different levels of natural cities. In this respect, they show little bias compared to city boundaries imposed by Census bureau or extracted from satellite imagery. Based on the investigation, we made two findings about rank size distributions. The first one is that all the natural cities in US follow strictly Zipf’s law regardless of the clustering resolutions, which is different from other studies only investigating a few largest cities. The second one is that Zipf’s law is not universal at the state level, e.g., Zipf’s law for natural cities within individual states does not hold valid.   This thesis continues to detect the sprawling based on natural cities. Urban sprawl devours large amount of open space each year and subsequently leads to many environmental problems. To curb urban sprawl with proper policies, a major problem is how to objectively measure it. In this thesis, a new approach is proposed to measure urban sprawl based on street nodes. This approach is based on the fact that street nodes are significantly correlated with population in cities. Specifically, it is reported that street nodes have a linear relationship with city sizes with correlation coefficient up to 0.97. This linear regression line, known as sprawl ruler, can partition all cities into the sprawling, compact and normal cities. This study verifies this approach with some US census data and US natural cities. Based on the verification, this thesis further applies it to three European countries: France, Germany and UK, and consequently categorizes all natural cities into three classes: sprawling, compact and normal. This categorization provides a new insight into the sprawling detection and sets a uniform standard for cross comparing sprawling level across an entire country. / QC 20101206

This study aims to find a relationship between the distribution of locals inside of Sweden and the municipalities’ relative concentration of foreigners. With the usage of data found in the website Statistics Sweden, we aim to investigate the existence of any relationship between the local population size of a municipality against the number of foreigners present in said municipalities, and see whether foreigners and immigrants are more concentrated in more populated municipalities rather than less populated ones. We aim to do this by utilizing multiple regression and dummy variables to identify whether there is a significant extra negative or positive effect on foreigners. The answer seems to be that foreigners are in fact more concentrated in more locally populated municipalities, rather than less populated ones

This dissertation undertakes an analysis of the spatial persistence of population in South Africa over the period 1911 to 2011. A comprehensive review is given of the history and development of geographical economics in order to understand the dynamics of the forces of agglomeration. In addition the history of the development of South Africa is discussed and special focus is directed to the geographical, economic and political factors that gave rise to the unequal distribution of population and wealth in the country. In the empirical analysis Zipf’s law was applied and it was found that South Africa’s population was more evenly spread in 1911. With the application of the law to the 2011 data the Pareto exponent of the OLS log-linear regression indicated that urban agglomeration was more persistent. Although this might indicate that apartheid did not influence agglomeration in South Africa it is argued that the nature of the agglomeration was in fact influenced by restrictive measures placed on the urbanisation of the population and industrial decentralisation policies. It is indicated that the apartheid policy altered the equilibrium spatial distribution of population and wealth which lead to a smaller than optimal primate and second largest magisterial districts, too many secondary cities of similar size, and also too many small and uneconomical rural settlements. / MCom (Economics), North-West University, Potchefstroom Campus, 2015

This dissertation undertakes an analysis of the spatial persistence of population in South Africa over the period 1911 to 2011. A comprehensive review is given of the history and development of geographical economics in order to understand the dynamics of the forces of agglomeration. In addition the history of the development of South Africa is discussed and special focus is directed to the geographical, economic and political factors that gave rise to the unequal distribution of population and wealth in the country. In the empirical analysis Zipf’s law was applied and it was found that South Africa’s population was more evenly spread in 1911. With the application of the law to the 2011 data the Pareto exponent of the OLS log-linear regression indicated that urban agglomeration was more persistent. Although this might indicate that apartheid did not influence agglomeration in South Africa it is argued that the nature of the agglomeration was in fact influenced by restrictive measures placed on the urbanisation of the population and industrial decentralisation policies. It is indicated that the apartheid policy altered the equilibrium spatial distribution of population and wealth which lead to a smaller than optimal primate and second largest magisterial districts, too many secondary cities of similar size, and also too many small and uneconomical rural settlements. / MCom (Economics), North-West University, Potchefstroom Campus, 2015

A pesquisa apresenta um estudo exploratório sobre a produção científica brasileira em HIV/Aids indexada na Web of Science no período 1993-2013. O estudo analisa, com base em indicadores bibliométricos de coocorrência de palavras-chave, a dimensão cognitiva da pesquisa brasileira em HIV/Aids a partir das informações obtidas no campo de metadados Descriptor (DE) dos 1798 artigos recuperados. A pesquisa procura ampliar o conhecimento das dimensões relativas às temáticas de pesquisa em HIV/Aids no cenário brasileiro, mas também demonstra o potencial dos procedimentos da análise de coocorrência de palavras. No referencial teórico apresenta aspectos gerais da comunicação científica, da bibliometria e da coocorrência de palavras. Os resultados de coocorrência ainda são amparados por um diagnóstico breve com uso de indicadores de atividade científica: produção ao longo dos anos, idiomas, periódicos científicos, áreas de pesquisa e instituições. Obteve medidas de frequência (lei de Zipf), de similaridade (cosseno de Salton), de densidade e de centralidade (Eigenvector) e identifica os principais cluster dos conjuntos textuais dos agrupamentos definidos na análise: 1993-1997, 1998-2001, 2002-2005, 2006-2009 e 2010-2013, com uso dos softwares Bibexcel, Excel, Hermetic Word Frequency Counter, Ucinet, NetDraw, VOSViewer, Google Analyzed e Google Refine. A pesquisa brasileira em HIV/Aids apresenta indícios de crescimento exponencial, com aumento das taxas de crescimento em todos os agrupamentos temporais. Descobriu-se que os periódicos líderes em publicações foram essencialmente os brasileiros da área da saúde e/ou internacionais especializados em HIV/Aids. O idioma preferido nas comunicações é a língua inglesa. As áreas de pesquisa predominantes foram “Doenças Infecciosas”, “Saúde Pública”, “Imunologia”, “Medicina Tropical” e “Virologia”, de um espectro multidisciplinar de 82 áreas distintas. As instituições de pesquisa mais prolíficas foram USP, Fiocruz e UFRJ num quadro de 470 instituições brasileiras (maioria públicas) e 717 estrangeiras, de 80 países (maioria norte-americana), aspecto indicativo da colaboração nacional e internacional da pesquisa brasileira em HIV/Aids. A análise de coocorrência de palavras utilizou 77% do resultado da busca, ou seja 1392 documentos divididos nos cinco agrupamentos temporais. Todos os agrupamentos de palavras-chave apresentaram evidências do ajustamento da frequência à lei de Zipf e sinalizaram que os autores dos artigos ampliaram o léxico do campo do HIV/Aids no decorrer dos períodos. Embora a visualização da densidade do léxico e a formação dos cluster demonstrem a diversidade de palavras-chave contidas na pesquisa, se observou uma acentuada centralidade às palavras de natureza óbvia, já que também foram expressões adotadas na estratégia de busca “Aids”; “HIV”; “HIV/Aids”; “Acquired immunodeficiency syndrome”; “Human immunodeficiency virus” e “Brazil”. Os resultados mais significativos puderam ser visualizados com a exclusão destas palavras na formação dos grafos. A pesquisa identificou as palavras-chave do núcleo básico do campo do HIV/Aids em cada período, a partir da definição de uma ocorrência mínima nos agrupamentos. O mainstream de palavraschave é definido pela similaridade dos pares de palavras associadas ao longo do tempo: “Adolescents”; “Antiretroviral therapy”; “Epidemiology”; “Haart”; “Highly active antiretroviral therapy”; “HIV infection”; “HIV infections”; “HIV-1”; “Mortality”; “Opportunistic infections”; “Prevention”; “Prevention & control”; “Socioeconomic factors”; “Tuberculosis”; e “Women”, além das expressões óbvias. O estudo conclui que as palavraschave usadas por autores podem demonstrar aspectos da evolução de uma área de pesquisa, assim como foi observado na pesquisa brasileira em HIV/Aids do período 1993-2013. / The research presents an exploratory study of the Brazilian scientific production on HIV/Aids indexed in Web of Science in the period 1993-2013. The study analyzes based on bibliometric indicators of co-occurrence of keywords, the cognitive dimension of brazilian research on HIV/Aids from the information obtained in the field of metadata Descriptor (DE) of the 1798 articles retrieved. The research seeks to expand knowledge of the dimensions relating to the themes of research on HIV/Aids in the brazilian scenario, but also demonstrates the potential of co-word analysis procedures. The theoretical framework presents general aspects of science communication, bibliometrics and co-word analysis. The results of co-occurrence are still supported by a brief diagnosis through the use of scientific activity indicators: production over the years, languages, scientific journals, research areas and institutions. Obtained frequency measures (Law of Zipf), similarity (Salton’s cocine), density and centrality (Eigenvector) and identifies the main cluster of textual sets of clusters defined in the analysis: 1993-1997, 1998-2001, 2002- 2005, 2006-2009 and 2010-2013, using the softwares Bibexcel, Excel, Hermetic Word Frequency Counter, Ucinet, NetDraw, VOSViewer, Analyzed Google and Google Refine. The brazilian research in HIV/Aids presents evidence of exponential growth, with increased growth rates at all time groupings. It turned out that the periodic leading publications were mainly brazilians of health and/or international specialize in HIV/Aids. The preferred language in communication is English. Predominant research areas were the "Infectious Diseases", "Public Health", "Immunology", "Tropical Medicine" and "Virology", a multidisciplinary spectrum of 82 different areas. The most prolific research institutions were USP, UFRJ and Fiocruz in a table of 470 brazilian institutions (majority public) and 717 foreign, from 80 countries (US majority), indicative aspect of national and international collaboration of brazilian research on HIV/Aids. The co-word analysis used 77% of the search result, namely 1392 documents divided into five time groups. All keyword groupings showed evidence of frequency adjustment to Zipf's law and signaled that the authors of the articles expanded the lexicon of the field of HIV/Aids over the periods. While viewing the density of the lexicon and the formation of the cluster show the diversity of keywords contained in the survey, there was a marked centrality to the words of obviousness, since they were also expressions adopted in the search strategy "Aids"; "HIV"; " HIV/Aids"; "Acquired immunodeficiency syndrome"; "Human immunodeficiency virus" and "Brazil". The most significant results could be viewed with the exclusion of these words in the formation of graphs. The research identified the key words of the basic core of the field of HIV/Aids in each period, from the definition of a minimum occurrence in clusters. The mainstream keyword is defined by the similarity of pairs of words associated over time, "Adolescents"; "Antiretroviral therapy"; "Epidemiology"; "Haart"; "Highly active antiretroviral therapy"; "HIV infection"; "HIV infections"; "HIV-1"; "Mortality"; "Opportunistic infections"; "Prevention"; "Prevention & Control"; "Socioeconomic factors"; "Tuberculosis"; and "Women", besides the obvious expressions. The study concludes that the keywords used by authors can demonstrate aspects of the evolution of an area of research, as was seen in the brazilian research on HIV/Aids for the period 1993-2013.

A pesquisa apresenta um estudo exploratório sobre a produção científica brasileira em HIV/Aids indexada na Web of Science no período 1993-2013. O estudo analisa, com base em indicadores bibliométricos de coocorrência de palavras-chave, a dimensão cognitiva da pesquisa brasileira em HIV/Aids a partir das informações obtidas no campo de metadados Descriptor (DE) dos 1798 artigos recuperados. A pesquisa procura ampliar o conhecimento das dimensões relativas às temáticas de pesquisa em HIV/Aids no cenário brasileiro, mas também demonstra o potencial dos procedimentos da análise de coocorrência de palavras. No referencial teórico apresenta aspectos gerais da comunicação científica, da bibliometria e da coocorrência de palavras. Os resultados de coocorrência ainda são amparados por um diagnóstico breve com uso de indicadores de atividade científica: produção ao longo dos anos, idiomas, periódicos científicos, áreas de pesquisa e instituições. Obteve medidas de frequência (lei de Zipf), de similaridade (cosseno de Salton), de densidade e de centralidade (Eigenvector) e identifica os principais cluster dos conjuntos textuais dos agrupamentos definidos na análise: 1993-1997, 1998-2001, 2002-2005, 2006-2009 e 2010-2013, com uso dos softwares Bibexcel, Excel, Hermetic Word Frequency Counter, Ucinet, NetDraw, VOSViewer, Google Analyzed e Google Refine. A pesquisa brasileira em HIV/Aids apresenta indícios de crescimento exponencial, com aumento das taxas de crescimento em todos os agrupamentos temporais. Descobriu-se que os periódicos líderes em publicações foram essencialmente os brasileiros da área da saúde e/ou internacionais especializados em HIV/Aids. O idioma preferido nas comunicações é a língua inglesa. As áreas de pesquisa predominantes foram “Doenças Infecciosas”, “Saúde Pública”, “Imunologia”, “Medicina Tropical” e “Virologia”, de um espectro multidisciplinar de 82 áreas distintas. As instituições de pesquisa mais prolíficas foram USP, Fiocruz e UFRJ num quadro de 470 instituições brasileiras (maioria públicas) e 717 estrangeiras, de 80 países (maioria norte-americana), aspecto indicativo da colaboração nacional e internacional da pesquisa brasileira em HIV/Aids. A análise de coocorrência de palavras utilizou 77% do resultado da busca, ou seja 1392 documentos divididos nos cinco agrupamentos temporais. Todos os agrupamentos de palavras-chave apresentaram evidências do ajustamento da frequência à lei de Zipf e sinalizaram que os autores dos artigos ampliaram o léxico do campo do HIV/Aids no decorrer dos períodos. Embora a visualização da densidade do léxico e a formação dos cluster demonstrem a diversidade de palavras-chave contidas na pesquisa, se observou uma acentuada centralidade às palavras de natureza óbvia, já que também foram expressões adotadas na estratégia de busca “Aids”; “HIV”; “HIV/Aids”; “Acquired immunodeficiency syndrome”; “Human immunodeficiency virus” e “Brazil”. Os resultados mais significativos puderam ser visualizados com a exclusão destas palavras na formação dos grafos. A pesquisa identificou as palavras-chave do núcleo básico do campo do HIV/Aids em cada período, a partir da definição de uma ocorrência mínima nos agrupamentos. O mainstream de palavraschave é definido pela similaridade dos pares de palavras associadas ao longo do tempo: “Adolescents”; “Antiretroviral therapy”; “Epidemiology”; “Haart”; “Highly active antiretroviral therapy”; “HIV infection”; “HIV infections”; “HIV-1”; “Mortality”; “Opportunistic infections”; “Prevention”; “Prevention & control”; “Socioeconomic factors”; “Tuberculosis”; e “Women”, além das expressões óbvias. O estudo conclui que as palavraschave usadas por autores podem demonstrar aspectos da evolução de uma área de pesquisa, assim como foi observado na pesquisa brasileira em HIV/Aids do período 1993-2013. / The research presents an exploratory study of the Brazilian scientific production on HIV/Aids indexed in Web of Science in the period 1993-2013. The study analyzes based on bibliometric indicators of co-occurrence of keywords, the cognitive dimension of brazilian research on HIV/Aids from the information obtained in the field of metadata Descriptor (DE) of the 1798 articles retrieved. The research seeks to expand knowledge of the dimensions relating to the themes of research on HIV/Aids in the brazilian scenario, but also demonstrates the potential of co-word analysis procedures. The theoretical framework presents general aspects of science communication, bibliometrics and co-word analysis. The results of co-occurrence are still supported by a brief diagnosis through the use of scientific activity indicators: production over the years, languages, scientific journals, research areas and institutions. Obtained frequency measures (Law of Zipf), similarity (Salton’s cocine), density and centrality (Eigenvector) and identifies the main cluster of textual sets of clusters defined in the analysis: 1993-1997, 1998-2001, 2002- 2005, 2006-2009 and 2010-2013, using the softwares Bibexcel, Excel, Hermetic Word Frequency Counter, Ucinet, NetDraw, VOSViewer, Analyzed Google and Google Refine. The brazilian research in HIV/Aids presents evidence of exponential growth, with increased growth rates at all time groupings. It turned out that the periodic leading publications were mainly brazilians of health and/or international specialize in HIV/Aids. The preferred language in communication is English. Predominant research areas were the "Infectious Diseases", "Public Health", "Immunology", "Tropical Medicine" and "Virology", a multidisciplinary spectrum of 82 different areas. The most prolific research institutions were USP, UFRJ and Fiocruz in a table of 470 brazilian institutions (majority public) and 717 foreign, from 80 countries (US majority), indicative aspect of national and international collaboration of brazilian research on HIV/Aids. The co-word analysis used 77% of the search result, namely 1392 documents divided into five time groups. All keyword groupings showed evidence of frequency adjustment to Zipf's law and signaled that the authors of the articles expanded the lexicon of the field of HIV/Aids over the periods. While viewing the density of the lexicon and the formation of the cluster show the diversity of keywords contained in the survey, there was a marked centrality to the words of obviousness, since they were also expressions adopted in the search strategy "Aids"; "HIV"; " HIV/Aids"; "Acquired immunodeficiency syndrome"; "Human immunodeficiency virus" and "Brazil". The most significant results could be viewed with the exclusion of these words in the formation of graphs. The research identified the key words of the basic core of the field of HIV/Aids in each period, from the definition of a minimum occurrence in clusters. The mainstream keyword is defined by the similarity of pairs of words associated over time, "Adolescents"; "Antiretroviral therapy"; "Epidemiology"; "Haart"; "Highly active antiretroviral therapy"; "HIV infection"; "HIV infections"; "HIV-1"; "Mortality"; "Opportunistic infections"; "Prevention"; "Prevention & Control"; "Socioeconomic factors"; "Tuberculosis"; and "Women", besides the obvious expressions. The study concludes that the keywords used by authors can demonstrate aspects of the evolution of an area of research, as was seen in the brazilian research on HIV/Aids for the period 1993-2013.

A pesquisa apresenta um estudo exploratório sobre a produção científica brasileira em HIV/Aids indexada na Web of Science no período 1993-2013. O estudo analisa, com base em indicadores bibliométricos de coocorrência de palavras-chave, a dimensão cognitiva da pesquisa brasileira em HIV/Aids a partir das informações obtidas no campo de metadados Descriptor (DE) dos 1798 artigos recuperados. A pesquisa procura ampliar o conhecimento das dimensões relativas às temáticas de pesquisa em HIV/Aids no cenário brasileiro, mas também demonstra o potencial dos procedimentos da análise de coocorrência de palavras. No referencial teórico apresenta aspectos gerais da comunicação científica, da bibliometria e da coocorrência de palavras. Os resultados de coocorrência ainda são amparados por um diagnóstico breve com uso de indicadores de atividade científica: produção ao longo dos anos, idiomas, periódicos científicos, áreas de pesquisa e instituições. Obteve medidas de frequência (lei de Zipf), de similaridade (cosseno de Salton), de densidade e de centralidade (Eigenvector) e identifica os principais cluster dos conjuntos textuais dos agrupamentos definidos na análise: 1993-1997, 1998-2001, 2002-2005, 2006-2009 e 2010-2013, com uso dos softwares Bibexcel, Excel, Hermetic Word Frequency Counter, Ucinet, NetDraw, VOSViewer, Google Analyzed e Google Refine. A pesquisa brasileira em HIV/Aids apresenta indícios de crescimento exponencial, com aumento das taxas de crescimento em todos os agrupamentos temporais. Descobriu-se que os periódicos líderes em publicações foram essencialmente os brasileiros da área da saúde e/ou internacionais especializados em HIV/Aids. O idioma preferido nas comunicações é a língua inglesa. As áreas de pesquisa predominantes foram “Doenças Infecciosas”, “Saúde Pública”, “Imunologia”, “Medicina Tropical” e “Virologia”, de um espectro multidisciplinar de 82 áreas distintas. As instituições de pesquisa mais prolíficas foram USP, Fiocruz e UFRJ num quadro de 470 instituições brasileiras (maioria públicas) e 717 estrangeiras, de 80 países (maioria norte-americana), aspecto indicativo da colaboração nacional e internacional da pesquisa brasileira em HIV/Aids. A análise de coocorrência de palavras utilizou 77% do resultado da busca, ou seja 1392 documentos divididos nos cinco agrupamentos temporais. Todos os agrupamentos de palavras-chave apresentaram evidências do ajustamento da frequência à lei de Zipf e sinalizaram que os autores dos artigos ampliaram o léxico do campo do HIV/Aids no decorrer dos períodos. Embora a visualização da densidade do léxico e a formação dos cluster demonstrem a diversidade de palavras-chave contidas na pesquisa, se observou uma acentuada centralidade às palavras de natureza óbvia, já que também foram expressões adotadas na estratégia de busca “Aids”; “HIV”; “HIV/Aids”; “Acquired immunodeficiency syndrome”; “Human immunodeficiency virus” e “Brazil”. Os resultados mais significativos puderam ser visualizados com a exclusão destas palavras na formação dos grafos. A pesquisa identificou as palavras-chave do núcleo básico do campo do HIV/Aids em cada período, a partir da definição de uma ocorrência mínima nos agrupamentos. O mainstream de palavraschave é definido pela similaridade dos pares de palavras associadas ao longo do tempo: “Adolescents”; “Antiretroviral therapy”; “Epidemiology”; “Haart”; “Highly active antiretroviral therapy”; “HIV infection”; “HIV infections”; “HIV-1”; “Mortality”; “Opportunistic infections”; “Prevention”; “Prevention & control”; “Socioeconomic factors”; “Tuberculosis”; e “Women”, além das expressões óbvias. O estudo conclui que as palavraschave usadas por autores podem demonstrar aspectos da evolução de uma área de pesquisa, assim como foi observado na pesquisa brasileira em HIV/Aids do período 1993-2013. / The research presents an exploratory study of the Brazilian scientific production on HIV/Aids indexed in Web of Science in the period 1993-2013. The study analyzes based on bibliometric indicators of co-occurrence of keywords, the cognitive dimension of brazilian research on HIV/Aids from the information obtained in the field of metadata Descriptor (DE) of the 1798 articles retrieved. The research seeks to expand knowledge of the dimensions relating to the themes of research on HIV/Aids in the brazilian scenario, but also demonstrates the potential of co-word analysis procedures. The theoretical framework presents general aspects of science communication, bibliometrics and co-word analysis. The results of co-occurrence are still supported by a brief diagnosis through the use of scientific activity indicators: production over the years, languages, scientific journals, research areas and institutions. Obtained frequency measures (Law of Zipf), similarity (Salton’s cocine), density and centrality (Eigenvector) and identifies the main cluster of textual sets of clusters defined in the analysis: 1993-1997, 1998-2001, 2002- 2005, 2006-2009 and 2010-2013, using the softwares Bibexcel, Excel, Hermetic Word Frequency Counter, Ucinet, NetDraw, VOSViewer, Analyzed Google and Google Refine. The brazilian research in HIV/Aids presents evidence of exponential growth, with increased growth rates at all time groupings. It turned out that the periodic leading publications were mainly brazilians of health and/or international specialize in HIV/Aids. The preferred language in communication is English. Predominant research areas were the "Infectious Diseases", "Public Health", "Immunology", "Tropical Medicine" and "Virology", a multidisciplinary spectrum of 82 different areas. The most prolific research institutions were USP, UFRJ and Fiocruz in a table of 470 brazilian institutions (majority public) and 717 foreign, from 80 countries (US majority), indicative aspect of national and international collaboration of brazilian research on HIV/Aids. The co-word analysis used 77% of the search result, namely 1392 documents divided into five time groups. All keyword groupings showed evidence of frequency adjustment to Zipf's law and signaled that the authors of the articles expanded the lexicon of the field of HIV/Aids over the periods. While viewing the density of the lexicon and the formation of the cluster show the diversity of keywords contained in the survey, there was a marked centrality to the words of obviousness, since they were also expressions adopted in the search strategy "Aids"; "HIV"; " HIV/Aids"; "Acquired immunodeficiency syndrome"; "Human immunodeficiency virus" and "Brazil". The most significant results could be viewed with the exclusion of these words in the formation of graphs. The research identified the key words of the basic core of the field of HIV/Aids in each period, from the definition of a minimum occurrence in clusters. The mainstream keyword is defined by the similarity of pairs of words associated over time, "Adolescents"; "Antiretroviral therapy"; "Epidemiology"; "Haart"; "Highly active antiretroviral therapy"; "HIV infection"; "HIV infections"; "HIV-1"; "Mortality"; "Opportunistic infections"; "Prevention"; "Prevention & Control"; "Socioeconomic factors"; "Tuberculosis"; and "Women", besides the obvious expressions. The study concludes that the keywords used by authors can demonstrate aspects of the evolution of an area of research, as was seen in the brazilian research on HIV/Aids for the period 1993-2013.

This is a dissertation about urban systems; within this broad subject I tackle three issues, one that focuses on an observed inter-city relationship and two that focus on an intra-city phenomenon. In Chapter II I adapt a model of random emergence of economic opportunities from the firm growth literature to the urban dynamics situation and present several predictions for urban system dynamics. One of these predictions is that the older the city the larger and more diversified it is going to be on average, which I proceed to verify empirically using two distinct datasets. In Chapter III I analyze the Residential Real Estate Bubble that took place in Miami-Dade County from 1999 to 2006. I adopt a Spatial-Economic model developed for the Paris Bubble episode of 1984-1993 and formulate an innovative test of the results in terms of speculative intensity on the basis of proxies of investor activity available in my dataset. My results support the idea that the best or more expensive areas are also where the greatest speculative activity takes place and where the rapid increase in prices begins. The most significant departure from previous studies that emerges in my results is the absence of a wider gap between high priced areas and low priced areas in the peak year. I develop a measure of dispersion in value among areas and contrast the Miami-Dade and Paris episodes. In Chapter IV I analyze the impact on tax equity of a Florida tax-limiting legislation known as Save Our Homes. I first compare homesteaded and non-homesteaded properties, and second, look within the subset of homesteaded properties. I find that non- homesteaded properties increase their share of taxes paid relative to homesteaded properties during an up market, but that this is reversed during a down market. For the subset of homesteaded properties I find that the impact on tax equity of SOH will depend on differential growth rates among higher and lower valued homes, but during times of rapid home price appreciation, in a scenario of no differential growth rates in property values, SOH increases progressivity relative to the prior system.

O objetivo desta tese foi analisar as várias abordagens do processo de integração econômica na América Central. No primeiro ensaio são apresentadas as causas históricas e as instituições que promoveram o processo de integração econômica regional nos últimos 54 anos. Conclui-se que as instituições têm um status eminentemente intergovernamental e não supranacional limitando assim sua autonomia e poder real em favor dos interesses e valores comuns. Os resultados sugerem que uma maior integração institucional eleva o nível de integração econômica e vice-versa. Por último, foi apresentada a proposta de criação de uma nova instituição regional denominada Sistema Centro-Americano de Inovação (SCAI). Além disso, no segundo ensaio, foi avaliada empiricamente a validade da Lei de Thirlwall para os países membros do Mercado Comum da América Central e República Dominicana (MCCA-RD). Os objetivos foram: 1) avaliar a existência de uma relação de cointegração entre as variáveis de produto interno bruto, exportações e os termos de troca e 2) estimar o modelo de correção de erros para identificar a existência de relações de longo prazo entre a produto interno bruto e as exportações e, posteriormente, incorporar termos comerciais. Para o caso MCCA-RD existe cointegração entre o produto interno bruto e as exportações, adicionando os termos de troca para essas duas variáveis as três cointegram a exceção do caso da República Dominicana. Os resultados alcançados indicam que as exportações podem influenciar positivamente o produto interno bruto, tanto a curto como a longo prazo. No caso dos termos de troca, a relação é positiva, com exceção da Costa Rica e Nicarágua. No último ensaio, é avalhiada a validade da lei Zipf (rule size rank), que postula que o tamanho de uma cidade é inversamente proporcional à sua ordem para o MCCA-RD. Ela ajuda a explicar como as forças de aglomeração favorecem a atividade econômica e, em particular, como o comércio internacional induz a criação de estruturas de sistemas urbanos mais equilibrados. O período analisado é composto de censos das cidades entre os anos 1950-2008 e outros índices de desigualdade urbana. Inicialmente no caso da MCCA-RD a validez da lei de Zipf é rejeitada. Posteriormente são avaliados outros índices desigualdade como a lei de Gibrat que mostra a existência do comportamento não-linear na distribuição de populações urbanas, ou seja, o crescimento de uma cidade é independente do seu tamanho, além de outras como a Regra Tamanho Estendida de Fan e Casseti (1994), Índice Primazia das Cidades e Index de Herfindahl-Hirschman concentração urbana (HHI). No caso de Panamá, a Lei de Gibrat é confirmada e nos outros índices de desigualdade mostram um aumento populacional até o início da década de 1980 e a partir daí, decresce gradualmente. Posteriormente, foram estimados os coeficientes de correlação de Pearson entre os índices de desigualdade e o índice de intensidade de comércio. Confirmou-se que o crescimento urbano é negativamente relacionado com o aumento do comércio internacional, com exceção apenas do caso do Panamá. Por fim, foram estimadas funções de densidade de Kernel para as populações que mostram uma mudança profunda nos anos oitenta em países como Costa Rica e El Salvador. No caso da Guatemala, a mesma mudança ocorre por volta dos anos noventa. Quando se trata de Honduras, Nicarágua e Panamá percebe-se uma forte tendência de primazia das cidades desde os anos cinquenta, isso pode causar congestião de atividades productivas. / The aim of this thesis was to analyze from several approaches the process of economic integration in Central America. The first essay introduced its historical causes and the institutions that promoted the regional economic integration process during the last 54 years. It concludes that the institutions have eminently intergovernmental status; evidently they are not supranational, thereby limiting its autonomy and real power to support common interest and values. Moreover, the hypothesis that institutional integration interacts with regional economic integration, was tested developing an institutional integration index. Subsequently a model of Autoregressive Vectors (VAR) was implemented, incorporating that index to such variables as per-capita income, exchange trading terms and trade opening. The results indicate that greater institutional integration brings a higher level of economic integration and vice versa. Finally, the proposal that promotes the establishment of a new regional institution called the Central American Innovation System (SCAI) is presented. In the second essay it was empirically evaluated the validity of Thirlwall’s Law for member countries of the Central American Common Market and Dominican Republic (CACM-RD). The objectives were to: 1) evaluate whether there is a direct correlation between the variables of gross domestic product, exports, and trading terms and 2) estimate the error correction model to identify, the existence of long term correlation between the gross domestic product and exports and subsequently to incorporate the commercial trading terms. For all of CACM-RD cases direct correlation exists between gross domestic product and exports and when these variables are related to trading terms also they have direct correlation, with the exception of Dominican Republic. These results jointly indicate that exports positively influence the gross domestic product both, in short and long term. In relation to trading terms the results are positive with the exception of Costa Rica and Nicaragua. The latter essay evaluates the empirical validity of Zipf’s Law (rank size rule) which assumes that the CACM-RD size of a city is inversely related to its ranking. It helps to explain how the agglomeration forces support the economic activity and in particular how international trade encourages the establishment of more balanced urban system structures. The period analyzed incorporated the 1950-2008 census for urban cities and additionally were analyzed others index of urban inequality. At the beginning in the CACM - RD validity of Zipf's law is rejected. After that, was evaluated others urban inequality index that: Gibrat’s law showing the existence of nonlinear behavior for urban system distribution, that is, that the growth of a city is independent of its size. Also the rule of the size of extended cities implemented by Fan and Casetti (1944) and the Primacy Cities Index from Herfindahl- Hirschman Index of urban concentration (HHI). In the case of Panama, Gibrat’s law is confirmed although other indexes generally show an increase for the countries until the early eighties, from then on, they are gradually decreasing. Later on, it was estimated the Pearson’s correlation coefficient between each one of these index as well as the trade intensity index. It was confirmed, that urban growth is negatively related with the increase of international trade with the only exception of Panama. Finally, Kernel’s density population functions were estimated, showing a deep change starting from the eighties in Costa Rica and El Salvador. For the case of Guatemala, similar adjustment took place around the nineties. In the case of Honduras, Nicaragua and Panamá, strong tendency happens to primacy cities ever since the fifties, this could lead to the cogestion the activities. / El objetivo de esta tesis fue analizar desde varios abordajes el proceso de integración económica de América Central. En el primer ensayo se presentan sus causas históricas y las instituciones que han promovido el proceso de integración económica regional en los últimos 54 años. Se concluye que las instituciones tienen un status eminentemente intergubernamental y no supranacional limitando así su autonomía y poder real a favor de intereses y valores comunes. Por otra parte, se evaluó la hipótesis que la integración institucional interactúa con la integración económica regional por medio de la elaboración del índice de integración institucional y posteriormente fue aplicado un modelo de Vectores Autoregresivos (VAR) incorporando ese índice a variables tales como ingreso per-cápita, términos de intercambio y apertura comercial. Los resultados apuntan que una mayor integración institucional ocasiona un nivel más alto de integración económica y viceversa. Por último, se presenta la propuesta de crear una nueva institución regional llamada Sistema Centroamericano de Innovaciones (SCAI). Por otra parte, en el segundo ensayo se evaluó empíricamente la validez de la Ley de Thirlwall para los países miembros del Mercado Común Centroamericano y República Dominicana (MCCA-RD). Los objetivos fueron: 1) evaluar si existe una relación de cointegración entre las variables producto, exportaciones y términos de intercambio comercial y; 2) estimar el modelo de corrección de errores para identificar la existencia de relaciones de largo plazo entre producto y exportaciones y, posteriormente incorporar los términos intercambio. Para los casos de todos los países del MCCA-RD existe una cointegración entre producto y exportaciones y cuando se agregan los términos de intercambio a estas dos variables apenas existe cointegración apenas con la excepción del caso de la República Dominicana. (Co En conjunto estos resultados indican en el MCCA-RD, que las exportaciones influencian positivamente el producto tanto en corto como en el largo plazo. En el caso de los términos de intercambio el resultado es positivo con la excepción de Costa Rica y Nicaragua. En el último ensayo se evalúa la validez empírica de la ley de Zipf (rank size rule) que postula que el tamaño de una ciudad está inversamente relacionada con su rango. De tal manera que la misma sirve para explicar cómo las fuerzas de aglomeración favorecen la actividad económica y en especial cómo el comercio internacional induce el establecimiento de estructuras de sistemas urbanos más equilibrados. El periodo analizado está comprende los censos entre los años 1950-2008 y adicionalmente se analizaron otros índices de desigualdad urbana. En el primer lugar para el MCCA-RD la validez de la ley de Zipf fue rechazada. Posteriormente se evaluaron otros índices de desigualdad tales como: la ley de Gibrat que muestra que el crecimiento de una ciudad es independiente de su tamaño, así como otras: la regla de tamaño de ciudad extendida de Fan y Casseti (1994), Índice de Primacía de ciudades e Índice Herfindahl-Hirschman de concentración urbana (IHH). En el caso de Panamá se confirma la ley de Gibrat y en el resto de índices se muestra en general para los países un incremento hasta la década de los años ochenta y caída paulatina a partir de entonces. Después se estimó el coeficiente de correlación de Pearson entre cada uno de estos índices y el índice de intensidad de comercio. En consecuencia, se corroboró que el crecimiento urbano tiene una relación negativa con el incremento del comercio internacional con la excepción apenas del caso de Panamá. Finalmente, se estimaron las funciones de densidad de Kernel para las poblaciones mostrando un cambio profundo a partir de los años ochenta en países como Costa Rica y El Salvador. Para Guatemala ese mismo cambio se dió alrededor de los años noventa y en Honduras, Nicaragua y Panamá existe aún una fuerte tendencia a primacía de ciudades desde los años cincuenta, lo que puede provocar una congestión de actividades.