An Empirical Comparison of Edge Effect Correction Methods Applied to K‐function Analysis

This paper explores various edge correction methods for K‐function analysis via Monte Carlo simulation. The correction methods discussed here are Ripley's circumference correction, a toroidal correction, and a guard area correction. First, simulation envelopes for a random point pattern are constructed for each edge correction method. Then statistical powers of these envelopes are analyzed in terms of the probability of detecting clustering and regularity in simulated clustering/regularity patterns. In addition to the K‐function, K(h), determined for individual distances, h, an overall statistic k is also examined. A major finding of this paper is that the K‐function method adjusted by either the Ripley or toroidal edge correction method is more powerful than what is not adjusted or adjusted by the guard area method. Another is that the overall statistic k outperforms the individual K(h) across almost the entire range of potential distances h.     

A Socio‐Geographic Perspective on Human Activities in Social Media

Location‐based social media make it possible to understand social and geographic aspects of human activities. However, previous studies have mostly examined these two aspects separately without looking at how they are linked. The study aims to connect two aspects by investigating whether there is any correlation between social connections and users' check‐in locations from a socio‐geographic perspective. We constructed three types of networks: a people–people network, a location–location network, and a city–city network from former location‐based social media Brightkite and Gowalla in the U.S., based on users' check‐in locations and their friendships. We adopted some complexity science methods such as power‐law detection and head/tail breaks classification method for analysis and visualization. Head/tail breaks recursively partitions data into a few large things in the head and many small things in the tail. By analyzing check‐in locations, we found that users' check‐in patterns are heterogeneous at both the individual and collective levels. We also discovered that users' first or most frequent check‐in locations can be the representatives of users' spatial information. The constructed networks based on these locations are very heterogeneous, as indicated by the high ht‐index. Most importantly, the node degree of the networks correlates highly with the population at locations (mostly with R² being 0.7) or cities (above 0.9). This correlation indicates that the geographic distributions of the social media users relate highly to their online social connections.     

THE MAX‐P‐REGIONS PROBLEM*

ABSTRACT In this paper, we introduce a new spatially constrained clustering problem called the max‐p ‐regions problem. It involves the clustering of a set of geographic areas into the maximum number of homogeneous regions such that the value of a spatially extensive regional attribute is above a predefined threshold value. We formulate the max‐p ‐regions problem as a mixed integer programming (MIP) problem, and propose a heuristic solution.     

SPACE–TIME MEASURES OF DEMAND FOR SERVICE: BRIDGING LOCATION MODELLING AND ACCESSIBILITY STUDIES THROUGH A TIME‐GEOGRAPHIC FRAMEWORK

Demand for service in location modelling is often evaluated based on the spatial proximity of fixed and static reference locations of demand (e.g. home) to a facility, which ignores person‐specific activity–travel patterns and the temporal changes in demand for service throughout the day. To address these limitations, this study draws upon recent developments in space–time measures of individual accessibility to explore the spatial and temporal structures of demand by considering individuals' space–time constraints and impact of existing urban structures. Based on a time‐geographic framework, eight space–time demand measures were developed and compared with three conventional location‐based demand measures for 12 hospitals through an empirical study conducted in Columbus, Ohio. The results show that geographic proximity between clients' home and facilities may not be an effective indicator for service demand, and conventional demand measures tend to underestimate potential demand for service in most situations. The study concludes that space–time demand measures that take into account people's activity‐travel patterns in space–time would lead to better estimation of demand for service in most cases.     

Anticipating the Next Half‐Century of Geographical Analysis

Prompted by a series of panel sessions at a recent American Association of Geographers annual meeting entitled “A Globe‐Shaped Crystal Ball: The Next Fifty Years of Geographical Analysis,” participants were asked to speculate on the future of the journal, which of course has broader implications for spatial and geographic analytics. In what follows, I provide my thoughts on the journal as a reader, contributor, referee, and former editor of Geographical Analysis. The major points touched upon include the following. First, application to address substantive concerns will come to dominate the field. Second, the spatial data deluge will continue unabated, but will lead to important advances because of better detail and less abstraction of reality. Third, analytical methods will evolve specifically for big data. Fourth, the point‐and‐click revolution will result in ever more use of spatial analytics, but also will lend itself to greater and more widespread abuse of these methods. Fifth, addressing assumptions and theoretical foundations of long utilized approaches will revolutionize a new generation of spatial analytics. Sixth, geographic uncertainty and bias will be more than an afterthought, and methods will emerge to support meaningful analysis. Finally, spatial optimization will have increased prominence in fundamental analysis, particularly associated with establishing and evaluating significance.     

THE VIRTUALIZATION OF URBAN YOUNG PEOPLE'S MOBILITY PRACTICES: A TIME‐GEOGRAPHIC TYPOLOGY

A time‐geographic approach, including time–space diaries and in‐depth interviews, is used to investigate the daily use and implications of information and communication technologies (ICTs) among a group of Swedish urban youth. We identify individual variations and nuances in ICT‐based practices in our respondents' social and spatial contexts. Using individual cases and detailed time‐geographic trajectories, we demonstrate how daily communicative actions – physical and virtual – are combined and integrated. From this we identify four ideal types of mobility practices: (i) home‐oriented, heavy Internet users; (ii) physically mobile, heavy mobile phone users; (iii) physically mobile, heavy Internet and mobile phone users; and (iv) home‐oriented, rarely mobile people (virtually and physically).     

An Extended K Function Method for Analyzing Distributions of Polygons with GIS

The objective of this paper is to develop a K function method for analyzing distributions of polygon-like entities in the real world by extending Ripley’s K function method. Many empirical studies using the K function method assume that entities are represented by points. If entities are small enough in comparison with a study area, this approximation may be acceptable. If not, polygon-like entities may not be approximated by points. To deal with polygon-like entities, this paper develops a K function method for analyzing distributions of polygons. First, the paper shows a method for extending the local K function of points to that of polygons. Second, the paper compares the result obtained from the K function of polygons with that of the points representing the polygons and shows a distinctive difference. Third, the paper formulates the cross K function method of polygons to analyze the relationship between two distributions of polygons of different kinds. Fourth, the paper implements the methods in GIS. Last, the paper applies the cross K function method of polygons to actual distributions of buildings of different uses in Aoyama, Tokyo.     

Mapping schools' NAPLAN results: a spatial inequality of school outcomes in Australia

This article identifies spatial dimensions of educational outcomes using maps of the 2016 Grade 5 reading results for Australia's National Assessment Program–Literacy and Numeracy for all Australian schools. A geographical information system (GIS) was used to overlay schools' results onto suburbs' advantage or disadvantage to visualise spatial patterns. We then examined the extent to which school results “cluster” in socio‐economically advantaged and disadvantaged suburbs and considered the consistency of spatial patterns for results across major cities. That work illustrates both how GIS can foreground educational inequality and how “the spatial” is more than corollary for student socio‐economic status. Results show substantial differences between urban and remote areas and towns of different size. Maps of cities visualise spatial “clustering” patterns of school results, with most schools in advantaged suburbs having high results and almost no schools in disadvantaged suburbs having high results. Educational outcomes strongly align to local socio‐demographic characteristics, and parallel host communities’ levels of advantage or disadvantage. Differences between public and private schools are less significant than within‐sector differences for schools in advantaged or disadvantaged locales. Patterns in all cities are consistent—schools in advantaged suburbs predominantly have high results, whereas non‐government schools generally perform better than government schools in disadvantaged suburbs. Most concerning is the persistent and increasing trajectory of results in advantaged, and more so in disadvantaged suburbs, of all cities since the first National Assessment Program–Literacy and Numeracy in 2008. Ameliorating spatial inequality between primary schools is one of the greatest challenges for Australians.     

GIS Methods in Time-Geographic Research: Geocomputation and Geovisualization of Human Activity Patterns

Over the past 40 years or so, human activities and movements in space‐time have attracted considerable research interest in geography. One of the earliest analytical perspectives for the analysis of human activity patterns and movements in space‐time is time geography. Despite the usefulness of time geography in many areas of geographical research, there are very few studies that actually implemented its constructs as analytical methods up to the mid‐1990s. With increasing availability of geo‐referenced individual‐level data and improvement in the geo‐computational capabilities of Geographical Information Systems (GIS), it is now more feasible than ever before to operationalize and implement time‐geographic constructs. This paper discusses recent applications of GIS‐based geo‐computation and three‐dimensional (3‐D) geo‐visualization methods in time‐geographic research. The usefulness of these methods is illustrated through examples drawn from the author's recent studies. The paper attempts to show that GIS provides an effective environment for implementing time‐geographic constructs and for the future development of operational methods in time‐geographic research.     

Contiguity Constraints for Single‐Region Site Search Problems

This paper proposes an explicit set of constraints as a general approach to the contiguity problem in site search modeling. Site search models address the challenging problem of identifying the best area in a study region for a particular land use, given that there are no candidate sites. Criteria that commonly arise in a search include a site's area, suitability, cost, shape, and proximity to surrounding geographic features. An unsolved problem in this modeling arena is the identification of a general set of mathematical programming constraints that can guarantee a contiguous solution (site) for any 0–1 integer‐programming site search formulation. The constraints proposed herein address this problem, and we evaluate their efficacy and efficiency in the context of a regular and irregular tessellation of geographic space. An especially efficient constraint form is derived from a more general form and similarly evaluated. The results demonstrate that the proposed constraints represent a viable, general approach to the contiguity problem.     

Some Remarks About the Future of Geographical Analysis: The Journal and the Sub‐Discipline

This paper expands upon a GA 50^th Anniversary panel presentation made at the 2018 New Orleans American Association of Geographers meeting. It notes that retrospectives for this topic already exist, both in terms of the journal and the sub‐discipline. This paper presents discussion about the following selected prominent transitional themes bridging the past and the future of geographical analysis: space–time data; geographic uncertainty and error; and, dimensional reduction spatial statistical modeling. It also presents discussion about the following three themes that are expected to receive considerable future attention: negative spatial autocorrelation; synergies between spatial statistics and spatial optimization; and, big spatial data. The first two of these topics essentially have been ignored in the literature to date.     

Settlement patterns,social complexity and agricultural strategies during the Chalcolithic period in the Northern Negev,Israel

Previous studies have reported a Chalcolithic site distribution pattern in the Northern Negev as clustered, exhibiting a number of characteristics that imply a chiefdom level of organization. However, a recent spatial analysis suggests that in some areas of the Northern Negev, settlement patterns were essentially random and that there is no evidence for regional chiefdom organization. We examine this controversy by closely inspecting the methods of spatial analyses employed by previous researchers, by introducing an additional multiscalar spatial technique, namely Ripley's K-function, and by using updated and modified data. Our results indicate that settlement distributions were essentially clustered, even in small areas along the wadis. Examining the relation between these spatial-dependent distributions and the landscape surroundings revealed that particular physiographic characteristics of the wadis contribute to increscent in site clusters. Furthermore, a general linear model analysis suggests that the distribution of Chalcolithic sites is determined primarily by environmental factors rather than factors related to political organization.     

A Shape‐Based Local Spatial Association Measure (LISShA): A Case Study in Maritime Anomaly Detection

The explicit consideration of the shape of geographic features has been largely ignored in existing spatial association measures. The primary contribution of this work is the development of a new local spatial association measure—a Local Indicator of Spatial and Shape Association (LISShA). The LISShA measure is modeled after local Geary's Spatial Autocorrelation measure with distance between shapes, calculated using the Small–Le metric, replacing difference between attribute values and the spatial neighborhood defined by Fréchet distance. We provide some explanation of these metrics and show, in detail, how the LISShA and proposed moments are calculated in a one‐dimensional context in a case study of maritime anomaly detection.     

Socio‐cultural innovations of the Final Umm an‐Nar period (c.2100–2000 BCE) in the Oman peninsula: new insights from Ra's al‐Jinz RJ‐2

The Early Bronze Age site of RJ‐2, located close to the coastal village of Ra's al‐Jinz on the eastern Omani coast (Niyabat Ra's al‐Hadd), was the focus of archaeological investigations for over two decades. The latest campaigns of excavation unearthed an architectural complex (Building XII) dated to the very end of the Umm an‐Nar period (Final UaN, c.2100–2000 BCE), previously attested on site by poorly preserved remains. This paper presents the remains explored during the most recent fieldwork, focusing on the stratigraphic‐structural sequence and the spatial layout. It also considers the transformations affecting structural evidence and material culture during this period, at both local and regional level, highlighting their significance for a comprehensive assessment of the last occupations related to the Early Bronze Age in south‐eastern Arabia. The paper concludes by showing how the Final Umm an‐Nar phase represents an age of substantial socio‐cultural innovations, which most likely shaped the transition towards the following Wadi Suq period.     

The K‐Function Method on a Network and Its Computational Implementation

This paper proposes two statistical methods, called the network K‐function method and the network cross K‐function method, for analyzing the distribution of points on a network. First, by extending the ordinary K‐function method defined on a homogeneous infinite plane with the Euclidean distance, the paper formulates the K‐function method and the cross K‐function method on a finite irregular network with the shortest‐path distance. Second, the paper shows advantages of the network K‐function methods, such as that the network K‐function methods can deal with spatial point processes on a street network in a small district, and that they can exactly take the boundary effect into account. Third, the paper develops the computational implementation of the network K‐functions, and shows that the computational order of the K‐function method is O(n²_Q log n_Q) and that of the network cross K‐function is O(n_Q log U3Q), where n_Q is the number of nodes of a network.     

Analyzing Regional Inequality in Post-Mao China in a GIS Environment

Regional inequality in China has attracted considerable scholarly attention, but the use of geographic information system (GIS) techniques for rigorous analysis remains limited. This paper utilizes recent data and GIS and spatial statistical techniques to analyze changing patterns of regional inequality in China from 1978 to 2000. It also identifies the changing clusters of regional development in China. We illustrate that regional inequality in China is sensitive to development trajectories of the provinces, and that conventional measures of regional inequality mask geographical clustering. Patterns of change are explained by both contextual and regression analyses. Journal of Economic Literature, Classification Numbers: F21, G32, P31. 16 figures, 3 tables, 30 references.     

Walking with preschool‐aged children to explore their local wellbeing affordances

An increasingly well‐developed body of research uses neighbourhood walks to better understand primary school children's experiences of local environments, yet virtually nothing is known about preschool‐aged children's connections to their neighbourhoods. A reason for this omission is the commonly held view that preschool children lack competency to reflect on lived environments beyond playgrounds, kindergartens, and other confined settings that dominate early childhood. However, preliterate children walk around, use, and create intimate relationships with local environments as shown by 10 children aged 3–5 years from Dunedin in New Zealand during go‐along interviews. We asked each to walk us around their locale, explaining and pointing out favourite and less beloved places and activities. In this article, we advance two arguments: first that preschoolers are knowledgeable meaning makers of place; second that walking with them is a key step to understanding their life worlds and provides a way for preliterate and preverbal children to demonstrate knowledge and understanding of their spatial worlds, including as research participants. We challenge the idea that children of this age lack large‐scale spatial competency and understanding. Walking with them generated an in‐depth appreciation of their experiences of environments and revealed deep connections they had with their locales at varied scales. The work enables us to offer novel insights into spatial competency, sociospatial complexities, and the multiple dimensions of young children's wellbeing affordances in urban environments. Such insights are highly relevant for geographers, planners, and others who shape children's urban environments.     

AN ANALYSIS OF THE GEM‐BLUE GLAZE OF YE WANG'S KOJI POTTERY*

Koji pottery is a glazed ceramic art used widely for figurines. In early Taiwan, it was employed in temple construction for decorative purposes. Ye Wang (1826–87) is the first historically documented Koji artist of Taiwan and also the most prominent Koji pottery artist, noted for his modelling and glazing skills. Unfortunately, his unique technique was lost following his death in 1887. In order to provide vital information for ongoing conservation work on Koji pottery, this study analysed the physical and chemical characteristics of Ye Wang's gem‐blue glaze, to discover the glaze formula. DSC combined with the two‐thirds rule revealed that the firing temperature of Ye Wang's works of art was most probably around 878–923°C. EPMA revealed that the gem‐blue glaze has high alkali levels, and belongs to the PbO–K₂O–B₂O₃–Na₂O–SiO₂ system, deriving its unique colour from copper, iron, manganese and cobalt. This study found high potassium levels in the gem‐blue glaze, which are generally a characteristic of traditional Chinese glazes. In addition, a unique discovery of boron, commonly used in famille rose, was also identified in the glaze. By comparing spectra of historical and reconstructed glazes and adjusting the proportion of chromophoric elements, this study found a glazing formula with colours close to those of Ye Wang's gem‐blue glaze.     

Cryogenic vitrification and 3D serial sectioning using high resolution cryo‐FIB SEM technology for brine‐filled grain boundaries in halite: first results

The structure of brine films in grain boundaries of halite has been the subject of much controversy over the past 20 years; although a number of innovative methods have been developed to study these structures, much is still unknown and fundamental information is missing. In this study, we investigated different methods of plunge‐freezing to vitrify the brine fill of grain boundaries for natural salt polycrystal. This was followed by a preliminary study of the 3D morphology of a vitrified grain boundary in a natural rock salt sample with a focused ion beam (FIB) excavation system. We have shown that brine‐filled grain boundaries in rock salt can be efficiently well frozen when dimensions are less than about 1 mm. Coupled with an ion beam tool, cryo‐SEM allows 3D observation of the well‐frozen grain boundaries in large volumes and high resolution. Initial results of brine‐filled natural halite grain boundaries show non‐faceted crystal–brine interfaces and unexpectedly low dihedral angles at room temperature and pressure.