Two-dimensional fiscal competition

This paper analyses commodity tax competition between two neighboringcountries whose governments are tax-revenue maximizers in atwo-dimensional market. The results suggest three conclusionsin a geographical sense. First, a small country sets a lowertax than does a big country, and per capita revenue of the smallcountry is larger than that of the big country. Second, thesetwo countries are subject to severer competitive pressure inthe case of a more curved national border. Finally, the impactof border curvature on tax and revenue differences are alwaysopposite in sign with the impact on tax and revenue ratios.     

The Conceptual Locus of a Two-dimensional Language: Some Implications for Human Responses to Two-dimensional Displays

It is proposed that two-dimensional displays, such as maps, aerial photographs, polygons, etc., may be generated and/or described by two-dimensional languages. A simple perceptual device is posited which utilizes such a language. The device is comprised of at least two components which represent short-term and long-term memory. It is clear that its conceputal locus is in multisystem memory models. Three such models are characterized which provide the necessary and sufficient conditions for the perceptual model posited. Given this conceptual frame, three illustrative sets of implications and experiments for human responses to two-dimensional displays are suggested.     

Simulating global patterns of Pleistocene hominin morphology

The first ever simulations of global patterns of early Homo morphology are presented here. These simulations are a good match to the known patterns in the fossil record. An enhanced version of the Stepping Out model is presented which simulated global patterns of hominin morphology including genetic drift and the homogenising effects of inter-group exchange. Stepping Out is then used to examine the importance of environmental factors on hominin morphology. The most significant feature of the simulations is an emergent division between the African and Asian populations. The effect of biogeographical factors on this division and other patterning is considered. Throughout, modelling results are interpreted in the context of fossil and archaeological records in order to enhance our understanding of population histories of hominin groups.     

Neighbor-based Properties of Some Orderings of Two-dimensional Space

An ordering of a two-dimensional matrix assigns consecutive integers to the cells in that matrix. This paper evaluates such orderings by concentrating on the differences between each cell's order key and the keys of its spatial neighbors. In all, ten systematically generated orderings and two hundred random trials from a newly defined class of orderings are compared. The row-by-row (raster) ordering often used in remote sensing and in matrix ordering within computer programs minimizes the mean absolute difference, the root-mean-squared difference (and hence the Geary statistic), and the mean maximum absolute difference for both 8-by-8 and 256-by-256 matrices; of the quadrant-recursive (“quadtree-compatible”) orderings examined, the Morton order had the lowest values for both mean absolute difference measures, whereas the Hilbert order had the lowest root-mean-squared neighbor difference. The Morton order has the overall minimum value for the Moran statistic. Heuristic search procedures applied to the 8-by-8 case found orderings which had considerably “better” values for these statistics (higher for Moran; lower for the others) than did any of the above, suggesting that it will be possible to define new systematic orderings with better scores than any ordering currently in the literature.     

Simulating Sources of Uncertainty in Policy Forecasting with a Large-Scale Regional Econometric Model

Long-term forecasts may be helpful in establishing the general framework for a region's policy agenda, and a well-structured economic model offers an opportunity to identify major policy instruments affecting a region's long-term growth. Nevertheless, the uncertainty of long-term forecasts should serve to caution policymakers in interpreting and acting upon such information. To offer perspective on this aspect of forecasts, simulations of the Pittsburgh economy are performed to the year 1995 using a large-scale regional econometric model. The forecasts are based on alternative assumptions concerning the performance of the national economy and the objective conditions characterizing key industries in the region. In this way, the model is used to identify and quantify several major sources of uncertainty in long-term regional forecasts.     

The Application of SfM Photogrammetry Software for Extracting Artifact Provenience from Palaeolithic Excavation Surfaces

While photogrammetry has become popular in archaeology and heritage management as an effective, low-cost method for generating detailed three-dimensional models, it remains to be established that the accuracy of model-derived measurements is sufficient for analytical purposes. Based on an expedient, in-field model processing protocol, we report preliminary results concerning the accuracy of artifact provenience information derived from photogrammetry models of excavation surfaces at the Upper Palaeolithic site of Shuidonggou Locality 2 in China. Error in model-derived provenience can range easily into the centimeter scale; accuracy in some spatial axes are significantly, but weakly, affected by the size of the sampled surface. While the observed error range is larger than thresholds proposed for Palaeolithic excavations, it is arguably acceptable in settings where the analytical demand for provenience precision is lower. We identify possible sources of error and discuss how model accuracy can be improved by additional systematic testing.     

Reconstructing Population Density Surfaces from Areal Data: A Comparison of Tobler's Pycnophylactic Interpolation Method and Area-to-Point Kriging

We compare Tobler's pycnophylactic interpolation method with the geostatistical approach of area-to-point kriging for distributing population data collected by areal unit in 18 census tracts in Ann Arbor for 1970 to reconstruct a population density surface. In both methods, (1) the areal data are reproduced when the predicted population density is upscaled; (2) physical boundary conditions are accounted for, if they exist; and (3) inequality constraints, such as the requirement of non-negative point predictions, are satisfied. The results show that when a certain variogram model, that is, the de Wijsian model corresponding to the free-space Green's function of Laplace's equation, is used in the geostatistical approach under the same boundary condition and constraints with Tobler's approach, the predicted population density surfaces are almost identical (up to numerical errors and discretization discrepancies). The implications of these findings are twofold: (1) multiple attribute surfaces can be constructed from areal data using the geostatistical approach, depending on the particular point variogram model adopted—that variogram model need not be the one associated with Tobler's solution and (2) it is the analyst's responsibility to justify whether the smoothness criterion employed in Tobler's approach is relevant to the particular application at hand. A notable advantage of the geostatistical approach over Tobler's is that it allows reporting the uncertainty or reliability of the interpolated values, with critical implications for uncertainty propagation in spatial analysis operations.     

Simulating the impacts of distal volcanic products upon peatlands in northern Britain: an experimental study on the Moss of Achnacree,Scotland

The potential impact of prehistoric volcanism on distal areas has been the subject of some discussion in both ecology and archaeology. An experimental approach is used here to examine the potential effects of distant volcanism on a peatland environment. Simulations of different tephra and acidity loading, designed to approximately replicate the prehistoric Hekla-4 ashfall, were monitored over 2 years. Impacts on the peatland ecosystem were assessed by qualitative observations of plant health and abundance, semi-quantitative observations of flowering, measurements of peat pH, humification and testate amoebae community composition. Plots with higher acid loading showed immediate and lasting impacts on plants, although other treated plots were less affected. Changes in testate amoebae and peat humification were inconsistent both within and between plots. The experiment demonstrates the potentially severe effects of high acid loading on peatland plants, although some responses remain unclear.     

Surfaces from the Visual Past: Recovering High<Emphasis Type="Bold">-</Emphasis>Resolution Terrain Data from Historic Aerial Imagery for Multitemporal Landscape Analysis

Historic aerial images are invaluable sources of aid to archaeological research. Often collected with large-format photogrammetric quality cameras, these images are potential archives of multidimensional data that can be used to recover information about historic landscapes that have been lost to modern development. However, a lack of camera information for many historic images coupled with physical degradation of their media has often made it difficult to compute geometrically rigorous 3D content from such imagery. While advances in photogrammetry and computer vision over the last two decades have made possible the extraction of accurate and detailed 3D topographical data from high-quality digital images emanating from uncalibrated or unknown cameras, the target source material for these algorithms is normally digital content and thus not negatively affected by the passage of time. In this paper, we present refinements to a computer vision-based workflow for the extraction of 3D data from historic aerial imagery, using readily available software, specific image preprocessing techniques and in-field measurement observations to mitigate some shortcomings of archival imagery and improve extraction of historical digital elevation models (hDEMs) for use in landscape archaeological research. We apply the developed method to a series of historic image sets and modern topographic data covering a period of over 70 years in western Sicily (Italy) and evaluate the outcome. The resulting series of hDEMs form a temporal data stack which is compared with modern high-resolution terrain data using a geomorphic change detection approach, providing a quantification of landscape change through time in extent and depth, and the impact of this change on archaeological resources.