5,726 research outputs found

    High performance computation of landscape genomic models integrating local indices of spatial association

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    Since its introduction, landscape genomics has developed quickly with the increasing availability of both molecular and topo-climatic data. The current challenges of the field mainly involve processing large numbers of models and disentangling selection from demography. Several methods address the latter, either by estimating a neutral model from population structure or by inferring simultaneously environmental and demographic effects. Here we present Samβ\betaada, an integrated approach to study signatures of local adaptation, providing rapid processing of whole genome data and enabling assessment of spatial association using molecular markers. Specifically, candidate loci to adaptation are identified by automatically assessing genome-environment associations. In complement, measuring the Local Indicators of Spatial Association (LISA) for these candidate loci allows to detect whether similar genotypes tend to gather in space, which constitutes a useful indication of the possible kinship relationship between individuals. In this paper, we also analyze SNP data from Ugandan cattle to detect signatures of local adaptation with Samβ\betaada, BayEnv, LFMM and an outlier method (FDIST approach in Arlequin) and compare their results. Samβ\betaada is an open source software for Windows, Linux and MacOS X available at \url{http://lasig.epfl.ch/sambada}Comment: 1 figure in text, 1 figure in supplementary material The structure of the article was modified and some explanations were updated. The methods and results presented are the same as in the previous versio

    The Influence of Role Models on Immigrant Self-Employment: A Spatial Analysis for Switzerland

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    Theoretical and empirical research suggests a connection between the presence of role models and the emergence of entrepreneurs. Existing entrepreneurs may act as role models for self-employment candidates by providing successful examples. By explicitly considering the self-employment rates of the natives, which may influence locally the decisions of immigrants towards entrepreneurship, we develop a simple model that explains immigrant self-employment rates for a sample of 2,490 Swiss municipalities. In addition, we accommodate for the presence of spatial spillovers in the distribution of rates, and test a spatial autoregressive model which takes into account the average self-employment rates of immigrants living in nearby municipalities. Our evidence shows a significant (positive) effect of such spatial network effects, which are characterized by a quick distance decay, suggesting spatial spillovers at the household and social network level. Additionally, we show that local conditions and immigrant pool characteristics differ, with respect to self-employment choices, when examining separately urban and rural contexts.immigrants, self-employment, role models, Switzerland, spatial lag

    The Influence of Role Models on Immigrant Self-Employment: A Spatial Analysis for Switzerland

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    Theoretical and empirical research suggests a connection between the presence of role models and the emergence of entrepreneurs. Existing entrepreneurs may act as role models for self-employment candidates by providing successful examples. By explicitly considering the self-employment rates of the natives, which may influence locally the decisions of immigrants towards entrepreneurship, we develop a simple model that explains immigrant self-employment rates for a sample of 2,490 Swiss municipalities. In addition, we accommodate for the presence of spatial spillovers in the distribution of rates, and test a spatial autoregressive model which takes into account the average self-employment rates of immigrants living in nearby municipalities. Our evidence shows a significant (positive) effect of such spatial network effects, which are characterized by a quick distance decay, suggesting spatial spillovers at the household and social network level. Additionally, we show that local conditions and immigrant pool characteristics differ, with respect to self-employment choices, when examining separately urban and rural contexts.immigrants, self-employment, role models, Switzerland, spatial lag

    Using geographically weighted regression to explore the spatially heterogeneous spread of bovine tuberculosis in England and Wales

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    An understanding of the factors that affect the spread of endemic bovine tuberculosis (bTB) is critical for the development of measures to stop and reverse this spread. Analyses of spatial data need to account for the inherent spatial heterogeneity within the data, or else spatial autocorrelation can lead to an overestimate of the significance of variables. This study used three methods of analysis—least-squares linear regression with a spatial autocorrelation term, geographically weighted regression (GWR) and boosted regression tree (BRT) analysis—to identify the factors that influence the spread of endemic bTB at a local level in England and Wales. The linear regression and GWR methods demonstrated the importance of accounting for spatial differences in risk factors for bTB, and showed some consistency in the identification of certain factors related to flooding, disease history and the presence of multiple genotypes of bTB. This is the first attempt to explore the factors associated with the spread of endemic bTB in England and Wales using GWR. This technique improves on least-squares linear regression approaches by identifying regional differences in the factors associated with bTB spread. However, interpretation of these complex regional differences is difficult and the approach does not lend itself to predictive models which are likely to be of more value to policy makers. Methods such as BRT may be more suited to such a task. Here we have demonstrated that GWR and BRT can produce comparable outputs

    Dynamics of Change in Spatial Dependencies in Blood Donation System in Poland

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    Blood donation allows to obtain blood and its components from healthy people in a bid to help treatment of anonymous individuals, relying on timely and sufficient supplies of matching blood. Being a social initiative, it depends on multiple factors. Those factors are possible to be shaped and are subject to research. This paper aims to present the dynamics of change in spatial dependencies determining development of blood donation in Poland from 2005 to 2010. Spatial analysis of data enables identification of similarities and differences between voivodeships in a given period. Testing of hypothesis concerning spatial autocorrelation was carried out using tools of spatial statistics. This paper's subject matter concentrates on pointing towards the direction and extent of changes illustrated with an example of analysis investigating the number of blood donations per hospital bed in wards with high demand on blood and its components. The number of blood donors per 1000 residents in 18 - 65 age was also analysed.Krwiodawstwo jest sposobem pozyskiwania krwi i jej składników od osób zdrowych na rzecz anonimowych osób, których leczenie jest uwarunkowane podaniem właściwej krwi w odpowiednim czasie oraz ilości. Jako akcja społeczna uwarunkowana jest od wielu czynników, będących przedmiotem kształtowania oraz badania. Celem niniejszego opracowania jest przedstawienie dynamiki zmian zależności przestrzennej w zakresie poziomu rozwoju krwiodawstwa w Polsce w latach 2005 - 2010. Analiza przestrzenna danych umożliwia określenie podobieństw i różnic między województwami w badanym okresie. Za pomocą narzędzi statystyki przestrzennej została zweryfikowana hipoteza o występowaniu autokorelacji przestrzennej. Przedmiotem opracowania jest wskazanie kierunku oraz zakresu zmian na przykładzie analizy zróżnicowania liczby donacji krwi przypadającej na łóżko szpitalne w oddziałach o wysokim zapotrzebowaniu na krew i jej składniki oraz liczby dawców przypadających na 1000 mieszkańców w wieku 18 -65

    Spatial spillovers in public expenditure on a municipal level in Spain

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    A key function of local governments is to provide a wide array of public services. The supply of these services has been found to create spatial spillovers among neighbouring municipalities. Although it is generally agreed that spillovers are present in models that explain government expenditures, their type—whether endogenous, exogenous or residual—and sign—whether positive or negative—remain ambiguous. In most cases, a subjective process is used to select the type of spatial regression model used in analysis, with mixed results. Per capita expenditures of ten subprogrammes (Security, Housing, Welfare, Environment, Social services, Employment promotion, Health, Education, Culture and Sport) are analysed for all Spanish municipalities with more than 5000 inhabitants in the 2010–2012 period. A Spatial Seemingly Unrelated Regression methodology in a panel framework is used to incorporate correlation between different subprogrammes and spatial dependence. Our results show that the three types of spatial effects are present. Furthermore, substantive dependence is positive in most cases, while negative residual dependence is observed in some.We gratefully acknowledge the contribution of three anonymous reviewers in helping us improve the quality of this paper. Prof. Fernando A. López , grateful for the financial support offered by the projects from Programa de Ayudas a Grupos de Excelencia de la Región de Murcia, Fundación Seneca (#19884-GERM-15) and Ministry of Economy and Competiveness (ECO2015-651758)

    Spatial autocorrelation and non-farm rural enterprises in Indonesia

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    Non-farm rural enterprises (NFRE) are increasingly studied because of their role in poverty reduction. However, existing studies of the effects of infrastructure on NFRE may give incorrect inferences because they typically fail to account for spatial effects. Such effects could reflect either spatial errors due to excluded local effects or spatial lags due to excluded interactions, such as between households switching out of farm work. We use rural investment climate survey data from Indonesia that allow distances between each household to be measured so that spatial effects can be modeled to assess the bias from ignoring such effects.Infrastructure, Non-farm enterprises, Spatial statistics, Indonesia, Community/Rural/Urban Development,

    Mapping the European regional educational distribution: Educational attainment and inequality

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    The geography of education, especially at sub-national level, is a huge black box. Basically nothing is known about the distribution of educational attainment and inequality across regions in Europe. This paper addresses this gap in the literature by mapping educational attainment and inequality in 102 regions in western Europe, using data extracted from the European Community Household Panel (ECHP) covering more than 100,000 individuals over the period 1995-2000. The results of this Exploratory Spatial Data Analysis (ESDA) reveal a strong correlation between levels of educational attainment and inequality across regions in Europe. Regions with similar educational conditions tend to cluster, often within national borders. In addition a North-South and an urban-rural dimension is evident. Northern regions and large European metropoli have not only the most educated labour force, but also the lowest levels of inequality. Educational inequality seems to be, in any case, a fundamentally within region phenomenon. 90 percent of the educational inequality in Europe takes place among individuals living in the same region.educational attainment; educational inequality; regions; exploratory spatial data analysis; Europe; urbanisation; EU North-South divide

    After “Raising the Bar”: applied maximum likelihood estimation of families of models in spatial econometrics.

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    Elhorst (2010) shows how the recent publication of LeSage and Pace (2009) in his expression “raises the bar” for our fitting of spatial econometrics models. By extending the family of models that deserve attention, Elhorst reveals the need to explore how they might be fitted, and discusses some alternatives. This paper attempts to take up this challenge with respect to implementation in the R spdep package for the maximum likelihood case, using a smaller data set to see whether earlier conclusions would be changed when newer techniques are used, and two larger data sets to examine model fitting issues.Models; Econometrics;

    The Application Of Local Indicators For Categorical Data (LICD) In The Spatial Analysis Of Economic Development

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    Firstly, we identify classes of regions presenting different economic development levels using taxonomic methods of multivariate data analysis. Secondly, we apply a join-count test to examine spatial dependencies between regions. It examines the tendency to form the spatial clusters. The global test indicates general spatial interactions between regions, while local tests give detailed results separately for each region. The global test detects spatial clustering of economically poor regions but is statistically insignificant as regards well-developed regions. Thus, the local tests are also applied. They indicate the occurrence of five spatial clusters and three outliers in Poland. There are three clusters of wealth. Their development is based on a diffusion impact of regional economic centres. The areas of eastern and north western Poland include clusters of poverty. The first one is impeded by the presense of three indiviual growth centres, while the second one is out of range of diffusion influence of bigger agglomerations
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