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Search Results: 1 - 10 of 242 matches for " ?rjan Pettersson "
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The Relevance of Cluster Initiatives in Rural Areas: Regional Policy in Sweden
Linda Lundmark,rjan Pettersson
Urbani Izziv , 2012,
Abstract: The relatively weak performance of sparsely populated areas has been given substantial attention in many regional, national and European Union initiatives. Many rural areas are struggling with development problems such as depopulation, advanced ageing, industrial restructuring and high levels of structural unemployment. In Sweden these issues are mainly associated with the difficulties in the non-metropolitan sparsely populated areas in the northern and southeastern parts. Here, the issue of implementing general cluster policies in sparsely populated regions in order to enhance their economic development is in focus. This research includes an overview of existing Swedish regional growth and development programmes that exemplify the current regional policies. It is found that the concepts of clusters and innovation systems have become important for policy on national and regional levels of government, but the understanding of the concepts is poor. In spite of regional variations in preconditions for cluster development, there are no clear regional modifications in the interpretation of clusters as described in the documents. One conclusion is that regional and local strategies to develop businesses in sparsely populated areas would benefit from using examples from non-metropolitan regions as a point of departure rather than using experiences drawn from high-tech industries located in metropolitan areas usually referenced in the international literature. The routine use of cluster and innovation systems in policy on the regional level underlines the need for more empirically based research on the preconditions for cluster development in sparsely populated areas.
Dissecting the genetic architecture of complex traits and its impact on genetic improvement programs: lessons learnt from the Virginia chicken lines
Pettersson, Mats E.;Carlborg,rjan;
Revista Brasileira de Zootecnia , 2010, DOI: 10.1590/S1516-35982010001300028
Abstract: long-term selection experiments provide a valuable resource for understanding the genetic changes that take place in animal improvement programs. the virginia chicken lines have for more than 50 years been subjected to single-trait, bi-directional, divergent selection for high and low juvenile body weight. it is one of the most well studied experimental populations in agricultural animals and has played an instrumental role in the understanding of the genetic basis of complex traits. in this paper, we summarize the findings from the more recent publications focusing on the efforts to identify the loci contributing to selection response as well as discuss the currently ongoing research. we conclude by describing some future research prospects that promise to bring new, interesting insights into the biology of complex traits in the near future and their implications for future animal improvement programs.
Restructuring and risk-reduction in mining: employment implications for northern Sweden
Erika Anna Knobblock,rjan Pettersson
Fennia : International Journal of Geography , 2010,
Abstract: In the past, employment in northern Sweden has been largely dependent on natural resources. Shifting demands and price fluctuations for raw materials have caused boom periods as well as times of crisis in local communities. During the first decade of the 21st century, increasing global demand for minerals resulted in substantial investments in the Swedish mining industry. The purpose of this article is to assess the importance of mining for employment in the county of V sterbotten, northern Sweden, by focusing on the time period after 1990. Mining employment constitutes a rather small part of all employment in the study area, due to a restructuring process that started in the 1960s. However, results show that mining employment has increased slightly, especially after 2002. Global demand for minerals and related technology and services make it reasonable to believe that this change will have a deeper significance for employment opportunities in the study area. Restructuring in mining generates new business opportunities in subcontracting, consultancy and equipment production, but also creates new challenges. Consequently, it is important to make strategic decisions on regional and local levels concerning how to make use of the development in the mining industry to stimulate long-term regional employment growth.
Inheritance Beyond Plain Heritability: Variance-Controlling Genes in Arabidopsis thaliana
Xia Shen,Mats Pettersson,Lars R?nneg?rd,rjan Carlborg
PLOS Genetics , 2012, DOI: 10.1371/journal.pgen.1002839
Abstract: The phenotypic effect of a gene is normally described by the mean-difference between alternative genotypes. A gene may, however, also influence the phenotype by causing a difference in variance between genotypes. Here, we reanalyze a publicly available Arabidopsis thaliana dataset [1] and show that genetic variance heterogeneity appears to be as common as normal additive effects on a genomewide scale. The study also develops theory to estimate the contributions of variance differences between genotypes to the phenotypic variance, and this is used to show that individual loci can explain more than 20% of the phenotypic variance. Two well-studied systems, cellular control of molybdenum level by the ion-transporter MOT1 and flowering-time regulation by the FRI-FLC expression network, and a novel association for Leaf serration are used to illustrate the contribution of major individual loci, expression pathways, and gene-by-environment interactions to the genetic variance heterogeneity.
Variance Heterogeneity in Saccharomyces cerevisiae Expression Data: Trans-Regulation and Epistasis
Ronald M. Nelson, Mats E. Pettersson, Xidan Li,rjan Carlborg
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0079507
Abstract: Here, we describe the results from the first variance heterogeneity Genome Wide Association Study (VGWAS) on yeast expression data. Using this forward genetics approach, we show that the genetic regulation of gene-expression in the budding yeast, Saccharomyces cerevisiae, includes mechanisms that can lead to variance heterogeneity in the expression between genotypes. Additionally, we performed a mean effect association study (GWAS). Comparing the mean and variance heterogeneity analyses, we find that the mean expression level is under genetic regulation from a larger absolute number of loci but that a higher proportion of the variance controlling loci were trans-regulated. Both mean and variance regulating loci cluster in regulatory hotspots that affect a large number of phenotypes; a single variance-controlling locus, mapping close to DIA2, was found to be involved in more than 10% of the significant associations. It has been suggested in the literature that variance-heterogeneity between the genotypes might be due to genetic interactions. We therefore screened the multi-locus genotype-phenotype maps for several traits where multiple associations were found, for indications of epistasis. Several examples of two and three locus genetic interactions were found to involve variance-controlling loci, with reports from the literature corroborating the functional connections between the loci. By using a new analytical approach to re-analyze a powerful existing dataset, we are thus able to both provide novel insights to the genetic mechanisms involved in the regulation of gene-expression in budding yeast and experimentally validate epistasis as an important mechanism underlying genetic variance-heterogeneity between genotypes.
Genome-Wide Effects of Long-Term Divergent Selection
Anna M. Johansson,Mats E. Pettersson,Paul B. Siegel,rjan Carlborg
PLOS Genetics , 2010, DOI: 10.1371/journal.pgen.1001188
Abstract: To understand the genetic mechanisms leading to phenotypic differentiation, it is important to identify genomic regions under selection. We scanned the genome of two chicken lines from a single trait selection experiment, where 50 generations of selection have resulted in a 9-fold difference in body weight. Analyses of nearly 60,000 SNP markers showed that the effects of selection on the genome are dramatic. The lines were fixed for alternative alleles in more than 50 regions as a result of selection. Another 10 regions displayed strong evidence for ongoing differentiation during the last 10 generations. Many more regions across the genome showed large differences in allele frequency between the lines, indicating that the phenotypic evolution in the lines in 50 generations is the result of an exploitation of standing genetic variation at 100s of loci across the genome.
Replication and Explorations of High-Order Epistasis Using a Large Advanced Intercross Line Pedigree
Mats Pettersson equal contributor,Francois Besnier equal contributor,Paul B. Siegel,rjan Carlborg
PLOS Genetics , 2011, DOI: 10.1371/journal.pgen.1002180
Abstract: Dissection of the genetic architecture of complex traits persists as a major challenge in biology; despite considerable efforts, much remains unclear including the role and importance of genetic interactions. This study provides empirical evidence for a strong and persistent contribution of both second- and third-order epistatic interactions to long-term selection response for body weight in two divergently selected chicken lines. We earlier reported a network of interacting loci with large effects on body weight in an F2 intercross between these high– and low–body weight lines. Here, most pair-wise interactions in the network are replicated in an independent eight-generation advanced intercross line (AIL). The original report showed an important contribution of capacitating epistasis to growth, meaning that the genotype at a hub in the network releases the effects of one or several peripheral loci. After fine-mapping of the loci in the AIL, we show that these interactions were persistent over time. The replication of five of six originally reported epistatic loci, as well as the capacitating epistasis, provides strong empirical evidence that the originally observed epistasis is of biological importance and is a contributor in the genetic architecture of this population. The stability of genetic interaction mechanisms over time indicates a non-transient role of epistasis on phenotypic change. Third-order epistasis was for the first time examined in this study and was shown to make an important contribution to growth, which suggests that the genetic architecture of growth is more complex than can be explained by two-locus interactions only. Our results illustrate the importance of designing studies that facilitate exploration of epistasis in populations for obtaining a comprehensive understanding of the genetics underlying a complex trait.
Natural CMT2 Variation Is Associated With Genome-Wide Methylation Changes and Temperature Seasonality
Xia Shen,Jennifer De Jonge,Simon K. G. Forsberg,Mats E. Pettersson,Zheya Sheng,Lars Hennig,rjan Carlborg
PLOS Genetics , 2014, DOI: doi/10.1371/journal.pgen.1004842
Abstract: As Arabidopsis thaliana has colonized a wide range of habitats across the world it is an attractive model for studying the genetic mechanisms underlying environmental adaptation. Here, we used public data from two collections of A. thaliana accessions to associate genetic variability at individual loci with differences in climates at the sampling sites. We use a novel method to screen the genome for plastic alleles that tolerate a broader climate range than the major allele. This approach reduces confounding with population structure and increases power compared to standard genome-wide association methods. Sixteen novel loci were found, including an association between Chromomethylase 2 (CMT2) and temperature seasonality where the genome-wide CHH methylation was different for the group of accessions carrying the plastic allele. Cmt2 mutants were shown to be more tolerant to heat-stress, suggesting genetic regulation of epigenetic modifications as a likely mechanism underlying natural adaptation to variable temperatures, potentially through differential allelic plasticity to temperature-stress.
The Economics of Power Generation Technology Choice and Investment Timing in the Presence of Policy Uncertainty  [PDF]
Robert Lundmark, Fredrik Pettersson
Low Carbon Economy (LCE) , 2012, DOI: 10.4236/lce.2012.31001
Abstract: The purpose of this study is to analyze how market and policy uncertainties affect the general profitability of new investments in the power sector, and investigate the associated investment timing and technology choices. We develop an economic model for new investments in three competing energy technologies in the Swedish electric power sector. The model takes into account the policy impacts of the EU ETS and the Swedish green certificate scheme. By simulating and modeling policy effects through stochastic prices the results suggest that bio-fuelled power is the most profitable technology choice in the presence of existing policy instruments and under our assumptions. The likelihood of choosing gas power increases over time at the expense of wind power due to the relative capital requirement per unit of output for these technologies. Overall the results indicate that the economic incentives to postpone investments into the future are significant.
Iterated function systems with a given continuous stationary distribution
rjan Stenflo
Mathematics , 2012, DOI: 10.1142/S0218348X1250017X
Abstract: For any continuous probability measure $\mu$ on ${\mathbb R}$ we construct an IFS with probabilities having $\mu$ as its unique measure-attractor.
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