Search results for "Spatial"
showing 10 items of 2121 documents
Précipitations et relief en Afrique orientale et australe : modélisations statistiques et géostatistiques.
2008
By considering two examples in Eastern and Southern Africa, this work has two aims: a better understanding of the influence of topography on the spatial distribution of rainfall and an optimal interpolation of station rainfall data, taking into account topography. To this end, an original methodology is developped, partly derived from previous studies focusing on extratropical regions.First, a statistical model is defined. With the help of a multi-scalar decomposition of topographical information into descriptors, a multiple linear regression is performed. This model is used to better understand the relationship between rainfall and topography. In Eastern Africa, the spatial distribution of…
Derivation of a Distributed Unit Hydrograph Integrating GIS and Remote Sensing
2007
The paper describes the results of a study based on the integration of remote sensing and geographical information system techniques to evaluate a distributed unit hydrograph model linked to an excess rainfall model for estimating the streamflow response at the outlet of a watershed. Travel time computation, based on the definition of a distributed unit hydrograph, has been performed, implementing a procedure using (1) a cell-to-cell flow path through the landscape determined from a digital elevation model (DEM); and (2) roughness parameters obtained from remote sensing data. This procedure allows the taking into account of the differences, in terms of velocity, between the hillslopes and t…
Spatial graphs and Convolutive Models
2020
In the last two decades, many complex systems have benefited from the use of graph theory, and these approaches have shown robust applicability in the field of finance, computer circuits and in biological systems. Large scale models of brain systems make also a great use of random graph models. Graph theory can be instrumental in modeling the connectivity and spatial distribution of neurons, through a characterization of the relative topological properties. However, all approaches in studying brain function have been so far limited to use experimental constraints obtained at a macroscopic level (e.g. fMRI, EEG, MEG, DTI, DSI). In this contribution, we present a microscopic use (i.e. at the …
Determinants of macroinvertebrate diversity in headwater streams: regional and local influences
2003
Summary 1 Multiscale determinants of diversity and the relationship between regional (RSR) and local richness (LSR) have recently attracted increased attention, yet such studies on stream organisms remain scarce. We studied the relationships among RSR, β-diversity, LSR and local environmental variables in 120 headwater streams in Finland. Approximately similar-sized areas of eight drainage systems were defined as regions, and 15 stream riffles (= locality) per region were sampled. 2 RSR showed a strong positive relationship with mean LSR (R2 = 0·686), and there was no sign of curvilinearity within the observed range of RSR. RSR was also positively, although non-significantly, related to β-d…
A Spatial Econometric Analysis of Convergence Across European Regions, 1980–1995
2003
The convergence of European regions has been largely discussed in the macroeconomic and the regional science literature during the past decade. Two observations are often emphasized. First, the convergence rate among European regions appears to be very slow in the extensive samples considered (Barro and Sala-iMartin 1991, 1995; Armstrong 1995a; Sala-i-Martin 1996a, 1996b). Second, as shown in Ertur and Le Gallo (see Chap. 2), the geographical distribution of European per capita GDP is highly clustered.
Shifting of wrapped phase maps in the frequency domain using a rational number
2016
The number of phase wraps in an image can be either reduced, or completely eliminated, by transforming the image into the frequency domain using a Fourier transform, and then shifting the spectrum towards the origin. After this, the spectrum is transformed back to the spatial domain using the inverse Fourier transform and finally the phase is extracted using the arctangent function. However, it is a common concern that the spectrum can be shifted only by an integer number, meaning that the phase wrap reduction is often not optimal. In this paper we propose an algorithm than enables the spectrum to be frequency shifted by a rational number. The principle of the proposed method is confirmed b…
Gares exurbanisées et développement urbain : Le cas des gares TGV bourguignonnes
2009
Dès la mise en service de la ligne TGV Sud-Est, au début des années 80, la Bourgogne a bénéficié de la création de deux nouvelles gares TGV, aménagées en périphérie des pôles urbains du Creusot et de Mâcon. Malgré leurs fonctions réduites, ces nouvelles gares périurbaines ont suscité d’ambitieux projets d’aménagement. De nouvelles zones d’activités ont ainsi vu le jour à proximité de ces gares. Ces projets n’ont eu toutefois que des retombées limitées en matière d’implantation d’activités économiques. Since the opening of TGV south-east railway line at the beginning of the 80s Bourgogne has profited by construction of two new stations beyond the edge of Le Creusot and Mâcon. Despite their l…
Layout attributes and recall
2003
The spatial arrangement of elements such as icons in a computer interface may influence learning the interface. However, the effects of layout organization on users' information processing is relatively little studied so far. The three experiments of this paper examined two attributes of layouts: spatial grouping by proximity and semantic coherence. Learning was assessed by tasks in which 30 participants recalled icon-like items' labels, locations, or both as a series of study-recall trials. The results show that layout organization interacts with task demands. Semantic organization improves recall of labels, and spatial grouping supports recall of locations. When both labels and locations …
Macrophage migration inhibitory factor is critically involved in basal and fluoxetine-stimulated adult hippocampal cell proliferation and in anxiety,…
2011
Intensive research is devoted to unravel the neurobiological mechanisms mediating adult hippocampal neurogenesis, its regulation by antidepressants, and its behavioral consequences. Macrophage migration inhibitory factor (MIF) is a pro-inflammatory cytokine that is expressed in the CNS, where its function is unknown. Here, we show, for the first time, the relevance of MIF expression for adult hippocampal neurogenesis. We identify MIF expression in neurogenic cells (in stem cells, cells undergoing proliferation, and in newly proliferated cells undergoing maturation) in the subgranular zone of the rodent dentate gyrus. A causal function for MIF in cell proliferation was shown using genetic (M…
Regional Science Perspectives on Tourism and Hospitality
2021
This book approaches the tourism and hospitality industry from a regional science perspective. By analyzing the spatial context of tourist travels, the hospitality sector, and the regional impacts of tourist activities, it demonstrates the value of the regional science paradigm for understanding the dynamics and effects of tourism and hospitality-related phenomena. Written by leading regional science scholars from various countries as well as professionals from organizations such as OECD and AirBnB, the contributions address topics such as migration, new types of accommodation, segmentation of tourism demand, and the potential use of tracking technologies in tourism research. The content is…