This article draws on several empirical regularities underlying central place theory (CPT) to enhance understanding of the uneven distribution of invention in the U.S. city system, especially the immense array of specializations that comprise national technological advance. CPT depicts city systems as collections of places in which functions expand in number as city size increases. Small cities have few functions and large cities many. A long-term hierarchical system is successively inclusive if large cities have all of the functions of smaller cities and some additional ones. The functions investigated here are 399 patent classes distributed across 366 U.S. metropolitan areas in the period from 2000 to 2011. Evidence is strong that patent classes with large numbers of awards are widely spread across the city system. This leads to the average sizes of places active in generating patents in the robust classes to be significantly smaller compared with the average sizes of areas that generate patents in unusual classes. Small cities are tied to national technological advance through the generation of patents in the most active and ubiquitous inventive specialties. Inventors in large cities are more likely to invent in unusual domains. Bigger areas are significantly more diversified compared with smaller ones. The system is not, however, strictly successively inclusive. Whereas 88.3 percent of all patent class–area pairs are generated in at least 50 percent of equally sized and bigger areas, only 20.5 percent of pairs are 100 percent strictly hierarchical.

Traditional space–time paths show the spatiotemporal trajectories of individuals in one to several days. Based on data for such short periods, these space–time paths might not be able to show regular activity patterns, which are pertinent to various types of planning and policy analysis. Travel data gathered for longer periods might capture regular activity patterns, but footprints captured by these data also include irregular activities, introducing noises or uncertainty. Our objective is to determine the representative spatiotemporal trajectories of individuals, accounting for stochastic disturbances and spatiotemporal variability, but using activity data with longer duration. Therefore, we explore using Twitter data, which have relatively low and irregular spatial and temporal resolutions. This article introduces a methodology to construct individual representative space–time paths using various aggregation and spatiotemporal clustering techniques. To depict and visualize spatiotemporal trajectories with uncertain information, we propose space–time cones of variable sizes to reflect the spatial precision of the paths and use colors on the cones to represent the confidence level. To illustrate the proposed methodology, we use the geo-tagged tweets for an extended period. Our analysis indicates that the representative space–time path reasonably describes an individual's regular activity patterns. As visual elements, cones and cone colors effectively show the varying geographical precision along the path and changing certainty levels across different path segments, respectively.

What Carl Sagan did for cosmology, Harm de Blij is doing for geography. See, hear, or read him and you will sign on for a continuing course in a subject that he has brought alive like no one else i...

There continues to be cross-disciplinary interest in the patterns, extent, and changing contexts of segregation and spatial inequality more generally. The changes are clearly context dependent but at the same time there are broad generalizations that arise from the processes of residential sorting and selection. A major question in U.S. segregation research is how the growth of Asian and Hispanic populations is influencing patterns of segregation and diversity at the neighborhood level. In this article we use a variant of a nearest neighbor approach to map, graph, and evaluate patterns of race and ethnicity at varying scales. We show that using a multiscalar approach to segregation can provide a detailed and more complete picture of segregation. The research confirms work from other studies that segregation is decreasing between some groups and increasing between others, and the patterns, and processes can be described as dynamic diversity. In a series of maps of ethnic clusters and population homogeneity we show how metropolitan areas, represented in this case by Los Angeles, now display patterns of complex living arrangements with multiple groups inhabiting both local neighborhoods and wider community spheres.

Coastal urban cities frequently face multiple hazards, including potentially disastrous extreme events. To combat this, vulnerability assessment is essential to developing an effective mitigation strategy. This study proposes a framework to assess the vulnerability of any densely populated urban area to disasters by considering both the population and the assets that are at risk. A set of indicators is also proposed to assess the vulnerability of social and socioeconomic systems, infrastructure, critical facilities, and adaptive capacity. The components of vulnerability were evaluated individually, using an accessible open source geographic information system at a fine 1-km grid scale, providing an insight into the spatial variability of the vulnerability. The optimal weight for individual indicators was assigned using data envelopment analysis to minimize subjective judgment and establish confidence in the results obtained. To decorrelate and reduce the dimensionality of the multivariate data, principal component analysis was performed. The proposed methodology was demonstrated on the twenty-four wards of Mumbai under the jurisdiction of the Municipal Corporation of Greater Mumbai and showed the mideastern part of Mumbai as the most vulnerable—mainly due to the increase in population and the marginal workers' ratio. A reduction in social vulnerability has been observed, however, across the city through improvement in the literacy rate and the main workers' ratio.

There are now more than 3 billion Internet users on our planet. The connections afforded to all of those people, in theory, allow for an unprecedented amount of communication and public participation. The goal of this article is to examine how those potentials match up to actual patterns of participation. By focusing on Wikipedia, the world's largest and most used repository of user-generated content, we are able to gain important insights into the geographies of voice and participation. This article shows that the relative democratization of the Internet has not brought about a concurrent democratization of voice and participation. Despite the fact that it is widely used around the world, Wikipedia is characterized by highly uneven geographies of participation. The goal of highlighting these inequalities is not to suggest that they are insurmountable. Our regression analysis shows that the availability of broadband is a clear factor in the propensity of people to participate on Wikipedia. The relationship is not a linear one, though. As a country approaches levels of connectivity above about 450,000 broadband Internet connections, the ability of broadband access to positively affect participation keeps increasing. Complicating this issue is the fact that participation from the world's economic peripheries tends to focus on editing about the world's cores rather than their own local regions. These results ultimately point to an informational magnetism that is cast by the world's economic cores, virtuous and vicious cycles that make it difficult to reconfigure networks and hierarchies of knowledge production.

Between 1975 and 1979, more than 2 million men, women, and children died in what has become known as the Cambodian genocide. In just under four years, approximately one quarter of the country's prewar population succumbed to arbitrary murder, torture, detention, starvation, and disease. Amidst these acts of destruction, however, the Communist Party of Kampuchea (CPK; the Khmer Rouge) advanced various pedagogical practices, including the promotion of poetry. Superficially, poems produced by the Khmer Rouge are literary forms of propaganda. Such a conclusion is incomplete. Through a reading of Khmer Rouge–era poetry, this article contributes to two themes in geography: fictive and public pedagogy. We argue that the Khmer Rouge used poetry as a form of public pedagogy. More specifically, Khmer Rouge–era poetry presented nature as the fulcrum on which society was to be transformed. The cultivation of a proper political consciousness required the nurturing of a community identity of what Democratic Kampuchea was to become. This argument is developed in five sections. First, we provide a brief overview of literary geographies. We then consider the transformative power of public education. Third, we provide an overview of educational policies under the Khmer Rouge. This is followed by a discussion of nature as conceived by the CPK. Our main empirical analysis of Khmer Rouge poetry is presented in the fifth section. Finally, we conclude with a consideration of the politics of creative interventions as a form of public pedagogy.

In this article we explore methods for tracking and disaggregating five alternately defined mean and median center points of population, measures that can help in interpreting the forces underlying shifting settlement patterns. We argue that the point that minimizes the sum of squared great circle distances is more conceptually appealing than the center point located via the method currently employed by the U.S. Census Bureau. We also suggest that the point of minimum aggregate distance—as deployed in many other geographic applications—provides an interesting alternative to the median center historically used in population analysis, which is the crossing point of the medial lines of latitude and longitude. We then propose methods to disaggregate any of the alternatively defined center points into multiple points useful for tracking and comparing the relative influences of each of the components of population change: births, deaths, domestic (or internal) migration, and immigration. Similarly, we track and examine the shifting locations of the center points of various age, sex, and race or ethnicity groups. In a final section, we suggest that the increasing average and standard distances of individuals from the median and mean centers result from the increasingly bicoastal distribution of the U.S. population. As summary measures of all of the changes in population occurring anywhere across the nation's land area, centers of population provide an interesting conceptual platform for drilling into the variegated geographic patterns and disparate demographic forces that underlie a country's population distribution.

Most world cities can now be characterized as multiethnic and multicultural in their population composition, and the residential patterning of their major component ethnic groups remains a topic of substantial research interest. Many studies of the degree of residential segregation of ethnic groups recognize that this is multiscalar in its composition, but few have incorporated this major feature into their analyses: Those that do mostly conclude that segregation is greater at the microscale than at the macroscale. This article uses a recently developed alternative procedure for assessing the degree of segregation that differs from all others in that it analyzes the geography of all groups simultaneously, providing a single, synoptic view of their relative segregation; can incorporate data for more than one date and therefore evaluate the statistical significance of the extent of any change over time; operates at several geographical scales, allowing appreciation of the extent of clustering and congregation for the various ethnic groups at different levels of spatial resolution; and—most important—is based on a firm statistical foundation that allows for robust assessments of differences in the levels of segregation for different groups between each other at different scales over time. This modeling procedure is illustrated by a three-scale analysis of ethnic residential segregation in Auckland, New Zealand, as depicted by the country's 2001, 2006, and 2013 censuses.