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Zipf's Law for All the Natural Cities around the World  [PDF]
Bin Jiang,Junjun Yin,Qingling Liu
Physics , 2014,
Abstract: Two fundamental issues surrounding research on Zipf's law regarding city sizes are whether and why this law holds. This paper does not deal with the latter issue with respect to why, and instead investigates whether Zipf's law holds in a global setting, thus involving all cities around the world. Unlike previous studies, which have mainly relied on conventional census data such as populations, and census-bureau-imposed definitions of cities, we adopt naturally (in terms of data speaks for itself) delineated cities, or natural cities, to be more precise, in order to examine Zipf's law. We find that Zipf's law holds remarkably well for all natural cities at the global level, and remains almost valid at the continental level except for Africa at certain time instants. We further examine the law at the country level, and note that Zipf's law is violated from country to country or from time to time. This violation is mainly due to our limitations; we are limited to individual countries, or to a static view on city-size distributions. The central argument of this paper is that Zipf's law is universal, and we therefore must use the correct scope in order to observe it. We further find Zipf's law applied to city numbers; the number of cities in the first largest country is twice as many as that in the second largest country, three times as many as that in the third largest country, and so on. These findings have profound implications for big data and the science of cities. Keywords: Night-time imagery, city-size distributions, head/tail division rule, head/tail breaks, big data
Zipf Law for Brazilian Cities  [PDF]
Newton J. Moura Jr.,Marcelo B. Ribeiro
Physics , 2005, DOI: 10.1016/j.physa.2005.11.038
Abstract: This work studies the Zipf Law for cities in Brazil. Data from censuses of 1970, 1980, 1991 and 2000 were used to select a sample containing only cities with 30,000 inhabitants or more. The results show that the population distribution in Brazilian cities does follow a power law similar to the ones found in other countries. Estimates of the power law exponent were found to be 2.22 +/- 0.34 for the 1970 and 1980 censuses, and 2.26 +/- 0.11 for censuses of 1991 and 2000. More accurate results were obtained with the maximum likelihood estimator, showing an exponent equal to 2.41 for 1970 and 2.36 for the other three years.
Zipf's law and cities in Serbia  [PDF]
?olak Zdravko,Dobri? Nikola
Zbornik Matice Srpske za Drustvene Nauke , 2010, DOI: 10.2298/zmsdn1031149s
Abstract: Formulated and mostly employed in linguistics, Zipf's law has been drawing attention of demographers and economists for a number of years relevant to their exploration of regional development or research within urban economy. Particularly intensive application of this law can be seen in analyzing the distribution of cities within a given country regarding the number of inhabitants living in them. The paper shows the application of Zipf's law in an analysis of the distribution of cities in Serbia according to the size of their population. Zipf's regressions have been determined based on the data provided by the 1998 and 2002 censuses, excluding the places populated by less than seven thousand inhabitants. The results arrived at are: for 1991: ln (rank) = 13,79-1,025 ln (number of inhabitants), R2 = 0,96; for 2002 ln (rank) = 13,88-1,032 ln (number of inhabitants), R2 = 0,96. The paper points out the applicability of Zipf's law on cities in Serbia having in mind the data collected the next census, as well as the factors which influence and modify the natural movements of the population and migrations spurred by economic changes. One of the most important ones is the fact that Serbia had become an independent country. Apart from that, the cities in Serbia took in the people coming from war torn and crisis enveloped neighboring regions. .
Influenza and Pneumonia Mortality in 66 Large Cities in the United States in Years Surrounding the 1918 Pandemic  [PDF]
Rodolfo Acuna-Soto, Cécile Viboud, Gerardo Chowell
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0023467
Abstract: The 1918 influenza pandemic was a major epidemiological event of the twentieth century resulting in at least twenty million deaths worldwide; however, despite its historical, epidemiological, and biological relevance, it remains poorly understood. Here we examine the relationship between annual pneumonia and influenza death rates in the pre-pandemic (1910–17) and pandemic (1918–20) periods and the scaling of mortality with latitude, longitude and population size, using data from 66 large cities of the United States. The mean pre-pandemic pneumonia death rates were highly associated with pneumonia death rates during the pandemic period (Spearman ρ = 0.64–0.72; P<0.001). By contrast, there was a weak correlation between pre-pandemic and pandemic influenza mortality rates. Pneumonia mortality rates partially explained influenza mortality rates in 1918 (ρ = 0.34, P = 0.005) but not during any other year. Pneumonia death counts followed a linear relationship with population size in all study years, suggesting that pneumonia death rates were homogeneous across the range of population sizes studied. By contrast, influenza death counts followed a power law relationship with a scaling exponent of ~0.81 (95%CI: 0.71, 0.91) in 1918, suggesting that smaller cities experienced worst outcomes during the pandemic. A linear relationship was observed for all other years. Our study suggests that mortality associated with the 1918–20 influenza pandemic was in part predetermined by pre-pandemic pneumonia death rates in 66 large US cities, perhaps through the impact of the physical and social structure of each city. Smaller cities suffered a disproportionately high per capita influenza mortality burden than larger ones in 1918, while city size did not affect pneumonia mortality rates in the pre-pandemic and pandemic periods.
Open Space Loss and Land Inequality in United States' Cities, 1990–2000  [PDF]
Robert I. McDonald,Richard T. T. Forman,Peter Kareiva
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0009509
Abstract: Urban growth reduces open space in and around cities, impacting biodiversity and ecosystem services. Using land-cover and population data, we examined land consumption and open space loss between 1990 and 2000 for all 274 metropolitan areas in the contiguous United States. Nationally, 1.4 million ha of open space was lost, and the amount lost in a given city was correlated with population growth (r(272) = 0.85, P<0.001). In 2000, cities varied in per capita land consumption by an order of magnitude, from 459 m2/person in New York to 5393 m2/person in Grand Forks, ND. The per capita land consumption (m2/person) of most cities decreased on average over the decade from 1,564 to 1,454 m 2/person, but there was substantial regional variation and some cities even increased. Cities with greater conservation funding or more reform-minded zoning tended to decrease in per capita land consumption more than other cities. The majority of developed area in cities is in low-density neighborhoods housing a small proportion of urban residents, with Gini coefficients that quantify this developed land inequality averaging 0.63. Our results suggest conservation funding and reform-minded zoning decrease per capita open space loss.
Geospatial Analysis Requires a Different Way of Thinking: The Problem of Spatial Heterogeneity  [PDF]
Bin Jiang
Physics , 2014, DOI: 10.1007/s10708-014-9537-y
Abstract: Geospatial analysis is very much dominated by a Gaussian way of thinking, which assumes that things in the world can be characterized by a well-defined mean, i.e., things are more or less similar in size. However, this assumption is not always valid. In fact, many things in the world lack a well-defined mean, and therefore there are far more small things than large ones. This paper attempts to argue that geospatial analysis requires a different way of thinking - a Paretian way of thinking that underlies skewed distribution such as power laws, Pareto and lognormal distributions. I review two properties of spatial dependence and spatial heterogeneity, and point out that the notion of spatial heterogeneity in current spatial statistics is only used to characterize local variance of spatial dependence. I subsequently argue for a broad perspective on spatial heterogeneity, and suggest it be formulated as a scaling law. I further discuss the implications of Paretian thinking and the scaling law for better understanding of geographic forms and processes, in particular while facing massive amounts of social media data. In the spirit of Paretian thinking, geospatial analysis should seek to simulate geographic events and phenomena from the bottom up rather than correlations as guided by Gaussian thinking.
UN HABITAT, State of the World’s Cities 2010/2011: Cities for All, Bridging the Urban Divide  [cached]
Juliano Geraldi
Revista Crítica de Ciências Sociais , 2012,
Abstract: O United Nations Human Settlements Programme (UN HABITAT) foi criado em 1978, dois anos após da realiza o da Habitat Conference em Vancouver, Canadá. é uma agência da Organiza o das Na es Unidas para assentamentos humanos, que “helps the urban poor by transforming cities into safer, healthier, greener places with better opportunities where everyone can live in dignity” (UN HABITAT’s Brochure, 2009). Uma das suas principais publica es é State of the World’s Cities. Iniciada em 2001, a séri...
Collective Sensing: Integrating Geospatial Technologies to Understand Urban Systems—An Overview  [PDF]
Thomas Blaschke,Geoffrey J. Hay,Qihao Weng,Bernd Resch
Remote Sensing , 2011, DOI: 10.3390/rs3081743
Abstract: Cities are complex systems composed of numerous interacting components that evolve over multiple spatio-temporal scales. Consequently, no single data source is sufficient to satisfy the information needs required to map, monitor, model, and ultimately understand and manage our interaction within such urban systems. Remote sensing technology provides a key data source for mapping such environments, but is not sufficient for fully understanding them. In this article we provide a condensed urban perspective of critical geospatial technologies and techniques: (i) Remote Sensing; (ii) Geographic Information Systems; (iii) object-based image analysis; and (iv) sensor webs, and recommend a holistic integration of these technologies within the language of open geospatial consortium (OGC) standards in-order to more fully understand urban systems. We then discuss the potential of this integration and conclude that this extends the monitoring and mapping options beyond “hard infrastructure” by addressing “humans as sensors”, mobility and human-environment interactions, and future improvements to quality of life and of social infrastructures.
Genetic Structure of the Invasive Tree Ailanthus altissima in Eastern United States Cities  [PDF]
Preston R. Aldrich,Joseph S. Briguglio,Shyam N. Kapadia,Minesh U. Morker,Ankit Rawal,Preeti Kalra,Cynthia D. Huebner,Gary K. Greer
Journal of Botany , 2010, DOI: 10.1155/2010/795735
Abstract: Ailanthus altissima is an invasive tree from Asia. It now occurs in most US states, and although primarily an urban weed, it has become a problem in forested areas especially in the eastern states. Little is known about its genetic structure. We explore its naturalized gene pool from 28 populations, mostly of the eastern US where infestations are especially severe. Five microsatellite markers were used to examine presumed neutral genetic variation. Results show a gene pool that is moderately diverse and sexually active and has significant but small genetic differences among populations and little correspondence between geographic and genetic distance. These findings are consistent with a model of multiple introductions followed by high rates of gene exchange between cities and regions. We propose movement along road and railway systems as the chief mode of range expansion. 1. Introduction Ailanthus altissima Swingle (stinking ash, Tree-of-Heaven, Chinese sumac) is a widespread member of the tropical tree family Simaroubaceae (Quassia family). Clayton et al. [1] recently clarified phylogenetic relationships within the family. The genus Ailanthus has five recognized extant species. Though four of these are geographically restricted to the Paleotropics, A. altissima is widespread in the New World [2]. Individuals of some of the other species may be present in the United States botanical gardens, but it is thought that naturalized Ailanthus is comprised mostly of the single species A. altissima (hereafter, Ailanthus), though genetic evidence is lacking at present. The first documented introduction of Ailanthus into the U.S. was through England in 1784 by William Hamilton, a Philadelphia gardener. Subsequent introductions have occurred along the east coast, and numerous introductions are thought to have occurred in the west most notably by Chinese immigrant railroad workers who used the plant as a medicinal in the 1800s [3]. The species has since spread to most states in the U.S. [4] following human disturbances [3, 5]. Ailanthus is shade intolerant and an aggressive pioneer, able to grow in the cracks in concrete [6]. It has large pinnate leaves similar to ash (Fraxinus) though the overall growth form is tropical with indeterminate leaf growth producing gently swooping leaves over a meter long. The species is dioecious [7] and pollinated mainly by bees and flies [8]. Juvenile growth is rapid accompanied with early reproduction [9]. Though clonal growth is aggressive, seed production is prolific with a single adult female producing 300,000 seed in a season
Cyber Torts: Common Law and Statutory Restraints in the United States
Gregory C. Mosier,Tara I. Fitzgerald,Tara I. Fitzgerald
Journal of International Commercial Law and Technology , 2007,
Abstract: United States state courts administer common law principles that remedy injuries that arise from tortious activities. Federal statutory restrictions and overbroad federal court rulings have created immunity for many activities in the context of cyberspace. This paper reviews a number of state court decisions in the United States and surveys several basic tort principles in regard to their application to technology enhanced activities on the Internet. Tort concepts, under traditional common law concepts can, if left unrestricted, develop to serve multiple interests.
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