Search results for "spatial analysi"
showing 10 items of 208 documents
Diachronic variation in the Middle Paleolithic settlement of Abrigo de la Quebrada (Chelva, Spain)
2017
Abstract This paper compares levels IV and VIII of Abrigo de la Quebrada. The study includes knapping technique, raw material, fauna, and the spatial distribution of lithic and bone remains. Although both levels correspond to cumulative palimpsests, patterns of resource management and use of space that suggest changes in the rhythm of occupation and the functionality of the settlements can be discerned. A change in mobility patterns probably underpins the differences between these two levels of Quebrada, but assessing this hypothesis is made difficult by the lack of comparable documentation for other sites in the region.
On a new robust workflow for the statistical and spatial analysis of fracture data collected with scanlines (or the importance of stationarity)
2020
Abstract. We present an innovative workflow for the statistical analysis of fracture data collected along scanlines, composed of two major stages, each one with alternative options. A prerequisite in our analysis is the assessment of stationarity of the dataset, which is motivated by statistical and geological considerations. Calculating statistics on non-stationary data can be statistically meaningless, and moreover the normalization and/or sub-setting approach that we discuss here can greatly improve our understanding of geological deformation processes. Our methodology is based on performing non-parametric statistical tests, which allow detecting important features of the spatial distrib…
Predicting the environmental suitability for onchocerciasis in Africa as an aid to elimination planning
2021
Recent evidence suggests that, in some foci, elimination of onchocerciasis from Africa may be feasible with mass drug administration (MDA) of ivermectin. To achieve continental elimination of transmission, mapping surveys will need to be conducted across all implementation units (IUs) for which endemicity status is currently unknown. Using boosted regression tree models with optimised hyperparameter selection, we estimated environmental suitability for onchocerciasis at the 5 × 5-km resolution across Africa. In order to classify IUs that include locations that are environmentally suitable, we used receiver operating characteristic (ROC) analysis to identify an optimal threshold for suitabil…
Spatial information transmission using axial temporal coherence coding
2007
We present an approach that can be used for transmission of information through space-limited systems or for superresolution. The spatial information is coded with different axial temporal coherence by interfering every spatial region in the input with the same region, but with a certain known delay in the longitudinal axis. Every spatial region has different delay. After mixing all of the spatial information, it is transmitted through the space-limited system. At the detection the information is passed through a similar interference setup containing certain axial delay. By temporally scanning along the longitudinal axis, each time a different spatial region that was coded with the correspo…
Agglomeration and dispersion of economic activities in and around Paris: An exploratory spatial data analysis
2010
The agglomeration patterns of twenty-six manufacturing and service sectors in and around Paris in 1999 are analysed. The method used measures the intensity of spatial agglomeration and identifies the location patterns of economic sectors. First the locational Gini coefficient and Moran’s I statistics of global spatial autocorrelation are computed. These provide different but complementary information about the spatial agglomeration of the sectors under study. Then exploratory spatial data analysis tools are applied. Moran scatterplots and local indicators of spatial association statistics reveal great diversity in location patterns across sectors.
PMT: New analytical framework for automated evaluation of geo-environmental modelling approaches
2019
Geospatial computation, data transformation to a relevant statistical software, and step-wise quantitative performance assessment can be cumbersome, especially when considering that the entire modelling procedure is repeatedly interrupted by several input/output steps, and the self-consistency and self-adaptive response to the modelled data and the features therein are lost while handling the data from different kinds of working environments. To date, an automated and a comprehensive validation system, which includes both the cutoff-dependent and –independent evaluation criteria for spatial modelling approaches, has not yet been developed for GIS based methodologies. This study, for the fir…
Growth and Spatial Dependence in Europe
2009
The convergence of European regions has been largely discussed in the empirical literature during the last decade. Two observations are often emphasized. First, the convergence rate among European regions appears to be very slow (Barro and Sala-i-Martins 1991, 1995; Armstrong 1995, Sala-i-Martin 1996a,b). Second, the tools used in the regional science literature show that the geographical distribution of European per capita GDP is highly clustered and characterized by global and local autocorrelation (Armstrong 1995; Ertur et al. 2007; Lopez-Bazo et al. 1999; Le Gallo and Ertur 2003 with a UE15 regional database and Ertur and Koch 2006, with a UE27 enlarged regional database). Many other st…
Experimental demonstration of bistable phase locking in a photorefractive oscillator
2012
We report experimental evidence of bistable phase locking in nonlinear optics, in particular, in a photorefractive oscillator emitting in few transverse modes. Bistable phase locking is a recently proposed method for converting a laserlike system, which is phase invariant, into a phase-bistable one by injecting a suitable spatially modulated monochromatic beam, resonant with the laser emission, into the optical cavity. We experimentally demonstrate that the emission on the fundamental TEM00 mode becomes phase bistable by injection of a beam with the shape of the TEM10 mode with appropriate frequency, in accordance with recent theoretical predictions [K. Staliunas et al., Phys. Rev. A 80, 02…
Two-dimensional temporal coherence coding for super resolved imaging
2009
In this paper, we present an approach that can be used for transmission of 2D spatial information through space-limited systems capable of transmitting even only a single spatial pixel. The input 2D object is illuminated with temporally incoherent illumination. The axial coherence length is very short and it equals only a few microns. Attached to the input object spatial random phase mask generates different axial shift for every pixel of the input. The temporal delays of the encoding (axial shifts) of every pixel are longer than the coherence length of the illuminating source. Therefore no temporal correlation exists between the various pixels of the input. A lens combines all spatial pixe…
A global descriptor of spatial pattern interaction in the galaxy distribution
1997
We present the function J as a morphological descriptor for point patterns formed by the distribution of galaxies in the Universe. This function was recently introduced in the field of spatial statistics, and is based on the nearest neighbor distribution and the void probability function. The J descriptor allows to distinguish clustered (i.e. correlated) from ``regular'' (i.e. anti-correlated) point distributions. We outline the theoretical foundations of the method, perform tests with a Matern cluster process as an idealised model of galaxy clustering, and apply the descriptor to galaxies and loose groups in the Perseus-Pisces Survey. A comparison with mock-samples extracted from a mixed d…