Natural trees—neighbourhood-location in a nutshell

Abstract

We present the notion of a natural tree as an efficient method for storing spatial information for quick access. A natural tree is a representation of spatial adjacency, organised to allow efficient addition of new data, access to existing data, or deletions. The nodes of a natural tree are compound elements obtained by a particular Delaunay triangulation algorithm. Improvements to that algorithm allow both the construction of the triangulation and subsequent access to neighbourhood information to be O(N log N). Applications include geographical information systems, contouring, and dynamical systems reconstruction.     

Using Qualitative Methods in Medical Geography: Deconstructive Moments in a Subdiscipline?

As medical geography reinvents itself as health geography, the linkages between social theory and the deconstruction of central categories organizing its medical orientation are being explored. This paper discusses the contribution of qualitative research to this process. In providing access to alternative ways of understanding health concerns, and emphasizing issues of power in the production of knowledge, qualitative methodology carries the potential for reconceptualizing key issues framing investigation of the relationships between place, people, and their health. In pursuing current issues in social theory, qualitative research also contributes to the blurring of the subdiscipline's boundaries and revitalizes its agenda.     

Decrease in Danish semi-natural grassland – a social construct or a real-world change?

During the past century, the western hemisphere has seen a general trend of agricultural expansion on the behalf of semi-natural habitat types, such as heathlands and meadows. This has been documented in numerous studies of land use change. This trend is reflected in today’s European rural landscapes, which are dominated by intensive agriculture. However, many of these studies are based on cartographical sources, such as topographical and thematic maps, and thus prone to uncertainties regarding classification systems over time, variations in definitions of land use categories and lacking documentations of land use definitions. For this study, we conducted two change detection studies, covering the same four study areas in Denmark. The first study was based on topographic maps, and indicates a strong decline in the amount of semi-natural grassland (SNG). This was contrasted by the second study, which was based on an interpretation of aerial photos, and which indicated a much less pronounced reduction of SNGs. Year to year comparisons of these two analyses also revealed large discrepancies in the coverage of SNGs. Our results indicate that change detection studies must account for uncertainties in classifications and results should be interpreted with caution.     

Postindustrial Manufacturing in a Sunbelt Metropolis: Where Are Factories Located in Phoenix?

Manufacturing establishments are integral to the spatial structure of fast-growing Sunbelt metropolitan areas, but most concepts and theories of intrametropolitan location were largely developed for an earlier technological era and different spatial contexts. This article investigates the location of nine disaggregated manufacturing sectors in Phoenix, Arizona, showing varying degrees of central core concentration and metropolitan-wide clustering. Distinct sectoral co-location patterns are also evident. We interpret our results as evidence that the intrametropolitan location of postindustrial manufacturing is best understood as a series of spatial distributions with varying concentration, centralization, clustering, and other order-based characteristics. There is little evidence that randomly scattered discrete industrial zones have developed nor that spatial patterns are uniform. Enduring lock-in effects tied to transportation infrastructure are pivotal to understanding the locational distribution of manufacturing industries in metropolitan Phoenix. Results do not support a hypothesis that a positive relationship exists between establishment size and distance from sectoral mean centers.     

Bottom sediments in Ho Bugt—a wadden sea environment

Pejrup, Morten: Bottom sediments in Ho Bugt—a wadden sea environment. Geografisk Tidsskrift 81: 11–16, Copenhagen, June 1981.

Twenty eight samples of bottom sediment from Ho Bugt, located at the west coast of Jutland, have been anlysed, and the variations within the fine and the coarse fractions described in detail. A method for classifying estuarine- and wadden-sea sediments is presented. The classification together with special characteristics found for the coarse fraction is used as a basis for a sediment chart for the northern part of Ho Bugt.     

Spatial Mismatch and Employment in a Decade of Restructuring∗

Spatial barriers to employment limit women's job opportunities, but their effects differ among racial/ethnic minority groups. This study evaluates the degree of spatial mismatch for minority women and men by comparing the commuting times of African American, Latino, and white workers in the New York metropolitan region. Using Public Use Microdata for 1980 and 1990, we perform a partial decomposition analysis to assess the role of spatial mismatch in lengthening commuting times for minority workers. The results show that African American men and women living in the center of the region have poorer spatial access to employment than their white counterparts. In the suburbs, African American women and Latinas suffer no spatial mismatch; rather, their longer commuting times reflect greater reliance on mass transit. Comparison with 1980 findings reveals little change in spatial mismatch over time despite significant economic and social restructuring in the 1980s. Spatial barriers still limit employment prospects for the majority of minority women living at the core of the region.     

Stable isotope techniques in plant water sources：a review

The stable hydrogen and oxygen isotopes widely exist in various kinds of natural water.Plants have to cope with various water sources:rainwater,soil water,groundwater,sea water,and mixtures.These are usually characterized by different isotopic signatures (18O/16O and D/H ratios).Because there are relative abundance variations in water,and plant roots do not discriminate against specific water isotopes during water uptake,hydrogen and oxygen stable isotope ratios of water within plants provide new information on water sources,interactions between plant species and water use patterns under natural conditions.At present,the measurement of δD,δ18O composition of various potential water sources and stem water has become significant means to identify plant water sources.Based on previous studies,this review highlights recent advances such as theory basis,methodology,as well as different spatial and temporal scales,and existed questions and prospects.Stable isotope techniques for estimating plant water sources have provided valuable tools for conducting basic and applied research.Future studies emphasize the modification of preparing methods,isotope technique combined with other measurements,and aerial organs of plant water source should be en-couraged.     

UV-B radiation: a health risk in the Arctic?

Seasonal stratospheric ozone depletion in the Arctic has raised the question of whether the associated increases in ultraviolet-B (290-320 nm) constitute a significant health risk in Arctic populations. Increases in skin cancer in Europe and the USA from excess UV-B resulting from ozone depletion have been predicted. Skin cancer is, however, rare in Inuit populations.
UV-B also causes a selective down regulation of the immune system which may be a natural regulatory mechanism evolved to prevent autoimmune attack on sunlight-altered skin. The action spectrum for UV-B immunosuppression implicated a unique skin photoreceptor molecule, urocanic acid (UCA), which isomerizes from the trans to the cis isomer on exposure to UV-B, the cis isomer being immunosuppressive. This form of immunosuppression is important in skin cancer and possibly in infectious diseases.
The epidemiology of non-Hodgkin's lymphoma shows a relationship with UV exposure, postulated to be via the immunosuppressive effects of UV-B. Cancers which show an excess in Inuit populations include nasopharyngeal and salivary gland cancer. Genetic factors appear to be involved, but these are thought to be virally related cancers possibly associated with the high viral load in these populations. In several studies on non-Arctic populations, salivary gland cancer has been linked to ultraviolet exposure. A potential role for UV-B exposure in these cancers in the Arctic needs to be explored.
In view of the high levels of POPS in some Arctic regions, potential interactions between the immunosuppression caused by some of these pollutants and the effects of UV-B need to be investigated.     

Parallelization of a regionalization heuristic in distributed computing platforms – a case study of parallel-p-compact-regions problem

In this paper, we report efforts to develop a parallel implementation of the p-compact regionalization problem suitable for multi-core desktop and high-performance computing environments. Regionalization for data aggregation is a key component of many spatial analytical workflows that are known to be NP-Hard. We utilize a low communication cost parallel implementation technique that provides a benchmark for more complex implementations of this algorithm. Both the initialization phase, utilizing a Memory-based Randomized Greedy and Edge Reassignment (MERGE) algorithm, and the local search phase, utilizing Simulated Annealing, are distributed over available compute cores. Our results suggest that the proposed parallelization strategy is capable of solving the compactness-driven regionalization problem both efficiently and effectively. We expect this work to advance CyberGIS research by extending its application areas into the regionalization world and to make a contribution to the spatial analysis community by proposing this parallelization strategy to solve large regionalization problems efficiently.     

Land use change in Bohai Rim: a spatial-temporal analysis

Land use change is one of the important aspects of global change[1-3]. The Bohai Rim is a hot spot of economic development in China, where land use changes remarkably. Analyzing land use change in this area is significant to the research of global change and regional sustainable land use. Although there has been much work undertaken on regional land use change in China, it was mainly on urban land use change[4-11], and few researches integrated remote sensing and GIS method. Based on data f…     

Reconsidering neoliberal urban planning in times of crisis: urban regeneration policy in a “dense” space in Lisbon

In this article, I contribute to recent debates about the concept of neoliberalism and its use as an explanatory concept, through the analysis of urban planning and regeneration policy in Lisbon amidst crisis and austerity. Suggesting a look at neoliberalization from a threefold perspective—the project, governmentalities, and policymaking—I analyze how current austerity-policy responses to the European economic crisis can be understood as a renewed and coherent deployment of neoliberal stances. The article presents implications for urban planning in Lisbon and thus suggests an exploration of the negotiations and clashes of hegemonic neoliberal governmentalities and policies with the local social and spatial fabric. For this exploration, I select a “deviant” case—the Mouraria neighborhood, a “dense” space in which the consequences of policies diverge sharply from expectations. In conclusion, I suggest that neoliberalization (in times of crisis) should be understood as a coherent project compromised by a set of highly ambiguous governmentalities, which bring about contradictory policymaking at the local level.     

Geochemical processes in a Mediterranean Lake: a high-resolution study of the last 4,000 years in Zoñar Lake,southern Spain

High-resolution geochemical analysis of a 6-m-long sediment core from Zoñar Lake, southern Spain, provides a detailed characterization of major changes in lake and watershed processes during the last 4,000 years. Geochemical variables were used as paleolimnological indicators and complement Zoñar Lakes’s paleoenvironmental reconstruction based on sedimentological and biological proxies, which define periods of increasing allochthonous input to the lake and periods of dominant autochthonous sedimentation. Chemical ratios identify periods of endogenic carbonate formation (higher Ca/Al, Sr/Al and Ba/Al ratios), evaporite precipitation (higher S/Al, Sr/Al ratios), and anoxic conditions (higher Mo/Al, U/Th ratios and Eu anomaly). Higher productivity is marked by elevated organic carbon content and carbonate precipitation (Mg/Ca). Hydrological reconstruction for Zoñar Lake was based on sedimentological, mineralogical and biological proxies, and shows that lower lake levels are characterized by Sr-rich sediments (a brackish lake with aragonite) and S-rich sediments (a saline lake with gypsum), while higher lake levels are characterized by sediments enriched in elements associated with alumino-silicates (Al, K, Ti, Fe, trace and rare earth elements), reflecting fresher conditions. Geochemical indicators also mark periods of higher detrital input to the lake related to human activity in the watershed: (1) during the Iberian Roman Humid Period (650 BC–AD 300), around the onset of the Little Ice Age (AD 1400), during the relatively drier Post-Roman and Middle Ages (AD 800–1400), and over the last 50 years, due to mechanized farming practices. Heavy metal enrichment in the sediments (Cu and Ni) suggests intensification of human activities during the Iberian Roman Period, and the use of fertilizers during the last 50 years.     

Farms in a Finnish village (Levanto) 1787–1916

Kampp, Aa. H. & Rikkinen, Kalevi, 1973: Farms in a Finnish Village (Levanto) 1787–1916. Geografisk Tidsskrift 72: 18–32. København, September 30, 1973.

The paper is a case study on a South-Finnish village as to number and size of holdings from the two-course rotation system in the 18th century to full reallotment in 1916.     

From agriculture to nature – a study of drivers of land use change in a peri-urban landscape

In this article, we investigate drivers behind land use changes in a peri-urban landscape. The research focuses on the motives and factors behind landowners’ decision-making in relation to land use changes, with the objective of improving our knowledge of the dynamics of land use change processes on farmland. An actor-centred conceptual framework is developed on the basis of the concept of lenses of decision-making. Data on farm and farmer characteristics were collected through a survey conducted in Roskilde Municipality, Denmark, a peri-urban landscape with a high level of landscape dynamics. A logistic regression analysis was used to analyse the relationship between nine purposively selected farm and farmer characteristics and the landscape activities of 93 landowners in the municipality. The results indicate that small farms, farms without livestock and landowners with a basic level of education are less likely to engage in landscape activities. A cluster analysis was used to analyse patterns of motives associated with land use changes. The results correspond with the intrinsic interests and family considerations suggested in the lenses of the decision-making framework, and in addition shows that the desire to improve the qualities of the property was the dominant motive.     

Working in a Landscape of Recession and Expansion: Academic Jobs in Geography in the United States, 1990–2011

The recent economic recession brought much university hiring to a standstill in the United States. Geography, in spite of strong prerecession growth, was no exception. Without a sense of how the academic geography job market has changed over the past decades, however, it is difficult to assess any recession-related decline or the relative strength of any recovery. This article presents an analysis of academic job postings in the field of geography from 1990 through 2011. Using data aggregated from the AAG Newsletter, which acts as an informal clearinghouse for most academic openings for geographers at four-year colleges and universities in the United States, we assess changes in the overall magnitude in numbers of academic job openings, with the particular goal of placing the recession-based paucity of openings within its broader historical context. Our results indicate that, indeed, the recession led to a very sharp decline in advertisements, but compared to previous recessions, the recovery appears to have occurred very quickly. Open-rank and temporary/non-tenure-track positions appear to have been fairly robust to the poor economic conditions, whereas assistant professor openings were particularly hard hit.     

Estimating Population Attribute Values in a Table: “Get Me Started in” Iterative Proportional Fitting

Iterative proportional fitting (IPF) is a technique that can be used to adjust a distribution reported in one data set by totals reported in others. IPF is used to revise tables of data where the information is incomplete, inaccurate, outdated, or a sample. Although widely applied, the IPF methodology is rarely presented in a way that is accessible to nonexpert users. This article fills that gap through discussion of how to operationalize the method and argues that IPF is an accessible and transparent tool that can be applied to a range of data situations in population geography and demography. It offers three case study examples where IPF has been applied to geographical data problems; the data and algorithms are made available to users as supplementary material.     

New firm formation in old industrial regions – a study of entrepreneurial in-migrants in Bergslagen,Sweden

The article examines new firm formation in the old industrial region (OIR) of Bergslagen in Sweden, and in particular the role of in-migrants. The study is based on longitudinal georeferenced microdata (1993–2008) compiled by Statistics Sweden and providing information on individuals' attachments to the Swedish labour market, as well as workplaces and firms, education, income, and family composition. This specially commissioned database enabled the characterization and analysis of emerging forms of entrepreneurship and self-employment, as well as the socio-economics of the labour market. The longitudinal data allowed the authors to trace actions taken by individuals over time. The results indicate that new firm formation is related to private services, rather than to the traditional manufacturing sector and public services that currently dominate the regional labour market. Self-employed in-migrants are active in other sectors than non-migrants, and show some distinct features in terms of their lower age, better education, and more often non-Nordic background. The study showed that both in-migration and return migration had a positive, significant, and substantial effect on migrants' decision to start a business when a number of other individual characteristics had been controlled for.     

Shrubs proliferated within a six-year exclosure in a temperate grassland—Spatiotemporal relationships between vegetation and soil variables

Overgrazing has been considered one of the maj or causes that trigger shrub encroachment of grassland. Proliferation of shrubs in grassland is recognized as an important indicator of grassland degradation and desertification. In China, various conservation measures, including enclosures to reduce livestock grazing, have been taken to reverse the trend of grassland desertification, yet shrubs have been reported to increase in the grasslands over the past decades. In late 2007, we set up a 400-m-by-50-m exclosure in a long-term overgrazed temperate grassland in Inner Mongolia, with the ob- jective to quantify the spatiotemporal relationship between vegetation dynamics, soil variables, and grazing exclusion. Soil moisture was continuously monitored within the exclosure, and cover and aboveground biomass of the shrubs were measured inside the exclosure in 2007, 2009, 2010, 2012, and 2013, and outside the exclosure in 2012 and 2013. We found the average shrub cover and biomass significantly increased in the six years by 103 % and 120%, respectively. The result supported the hypothesis that releasing grazing pressure following long-term overgrazing tends to trigger shrub invasion into grassland. Our results, limited to a single gradient, suggest that any conservation measures with quick release of overgrazing pressure by enclosure or other similar means might do just the opposite to accelerate shrub en- croachment in grassland. The changes in vegetation cover and biomass were regressed on the temporal average of the soil moisture content by means of the generalized least square technique to quantify the effect of the spatial autocor- relation. The result indicates that the grass cover and biomass significantly increased with the top, but decreased with the bottom layer soil moisture. The shrub cover and biomass, on the other hand, decreased with the top, but increased with bottom soil moisture, although the regression coefficients for the shrubs were not statistically significant. Hence this study supports the two-layered soil model which assumes grasses and shrubs use belowground resources in dif- ferent depths.