Search Results: 1 - 10 of 86 matches for " ?rjan Kardell "
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Intensive Forestry as Progress or Decay? An Analysis of the Debate about Forest Fertilization in Sweden, 1960–2010
Anna Lindkvist,?rjan Kardell,Christer Nordlund
Forests , 2011, DOI: 10.3390/f2010112
Abstract: In the mid-1960s, fertilization (with nitrogen) had a breakthrough as a promising forest management method in Swedish company owned forests. The activity grew and peaked during the 1970s but then lost ground and stabilized at a low level in the 1990s and early 2000s. Over the last five years, however, interest in fertilizing Swedish forests has increased again. In this article both the forestry industry's, and the environmental movement's, attitudes toward forest fertilization over time are investigated. Furthermore, conflicting persistent ideas about nature and future, i.e., "figures of thought", within interest groups, representing forestry and the environmental movement respectively, are identified and analyzed in relation to the debate on fertilization. The analysis reveals mainly three figures of thought that have influenced this debate during the period, "the idea of progress", "the idea of decay" and "the idea of the great chain of being". The study thus sheds light on how the relationship between forestry and the environmental movement has evolved from the 1960s until today and uncovers thought patterns that have stood, and continue to stand, in opposition to one another.
New solutions with peakon creation in the Camassa-Holm and Novikov equations
Marcus Kardell
Abstract: In this article we study a new kind of unbounded solutions to the Novikov equation, found via a Lie symmetry analysis. These solutions exhibit peakon creation, i.e., these solutions are smooth up until a certain finite time, at which a peak is created. We show that the functions are still weak solutions for those times where the peak lives. We also find similar unbounded solutions with peakon creation in the related Camassa-Holm equation, by making an ansatz inspired by the Novikov solutions. Finally, we see that the same ansatz for the Degasperis-Procesi equation yields unbounded solutions where a peakon is present for all times.
Exclusion statistics for quantum Hall states in Tao-Thouless limit
Mikael Kardell,Anders Karlhede
Physics , 2010, DOI: 10.1088/1742-5468/2011/02/P02037
Abstract: We consider spin-polarized abelian quantum Hall states in the Tao-Thouless limit, {\it ie} on a thin torus. For any filling factor $\nu=p/q$ a well-defined sector of low-energy states is identified and the exclusion statistics of the excitations is determined. We study numerically, at and near $\nu=1/3$ and $2/5$, how the low energy states develop as one moves away from the TT-limit towards the physical regime. We find that the lowest energy states in the physical regime develop from states in the low energy sector but that the exclusion statistics is modified.
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.
A general and efficient method for estimating continuous IBD functions for use in genome scans for QTL
Francois Besnier, ?rjan Carlborg
BMC Bioinformatics , 2007, DOI: 10.1186/1471-2105-8-440
Abstract: Estimation of IBD functions improved the computational efficiency and memory usage in genome scanning for QTL. We have explored two approaches to obtain continuous marker-bracket IBD-functions. By re-implementing an existing and fast deterministic IBD-estimation method, we show that this approach results in IBD functions that produces the exact same IBD as the original algorithm, but with a greater than 2-fold improvement of the computational efficiency and a considerably lower memory requirement for storing the resulting genome-wide IBD. By developing a general IBD function approximation algorithm, we show that it is possible to estimate marker-bracket IBD functions from IBD matrices estimated at marker locations by any existing IBD estimation algorithm. The general algorithm provides approximations that lead to QTL variance component estimates that even in worst-case scenarios are very similar to the true values. The approach of storing IBD as polynomial IBD-function was also shown to reduce the amount of memory required in genome scans for QTL.In addition to direct improvements in computational and memory efficiency, estimation of IBD-functions is a fundamental step needed to develop and implement new efficient optimization algorithms for high precision localization of QTL. Here, we discuss and test two approaches for estimating IBD functions based on existing IBD estimation algorithms. Our approaches provide immediately useful techniques for use in single QTL analyses in the variance component QTL mapping framework. They will, however, be particularly useful in genome scans for multiple interacting QTL, where the improvements in both computational and memory efficiency are the key for successful development of efficient optimization algorithms to allow widespread use of this methodology.Variance component analysis [1] is a flexible strategy for detecting Quantitative Trait Loci (QTLs), which is particularly useful in general populations such as humans and livest
A genetic algorithm based method for stringent haplotyping of family data
BMC Genetics , 2009, DOI: 10.1186/1471-2156-10-57
Abstract: We propose a genetic algorithm based method for haplotype estimation in family data that includes a stringency parameter. This allows the user to decide the error tolerance level when inferring parental origin of the alleles. This is a novel feature compared to existing methods for haplotype estimation. We show that using a high stringency produces haplotype data with few errors, whereas a low stringency provides haplotype estimates in most situations, but with an increased number of errors.By including a stringency criterion in our haplotyping method, the user is able to maintain the error rate at a suitable level for the particular study; one can select anything from haplotyped data with very small proportion of errors and a higher proportion of non-inferred haplotypes, to data with phase estimates for every marker, when haplotype errors are tolerable. Giving this choice makes the method more flexible and useful in a wide range of applications as it is able to fulfil different requirements regarding the tolerance for haplotype errors, or uncertain marker-phases.The average number of recombinations between two linked markers is a function of the distance between them [1,2]. Therefore, recombination events are rare between closely linked markers, and the alleles are transmitted as large haplotype blocks from parents to offspring. When tracing inheritance of alleles in multi-generation pedigrees, haplotype data is more informative that raw genotype data. This is utilized by e.g. Meuwissen and Goddard (2000) [3] to infer the co-variance of base generation individuals (i.e. founder individuals without known parents in the pedigree), at a given locus in their IBD based fine mapping strategy.As large-scale genotyping of Single Nucleotide Polymorphism (SNP) markers is now affordable, the density of marker maps used in genome studies for dissection of complex traits will increase, whereas very dense maps are already used in association studies and genomic selection. The in
SNP detection and prediction of variability between chicken lines using genome resequencing of DNA pools
Stefan Marklund, ?rjan Carlborg
BMC Genomics , 2010, DOI: 10.1186/1471-2164-11-665
Abstract: Genotyping with a 60 K SNP chip revealed polymorphisms within or between two divergently selected chicken lines for 31 363 SNPs, 48% of which were also detected using resequencing of DNA pools. SNP detection using resequencing was more powerful for positions with larger differences in allele frequency between the lines. About 50% of the SNPs with non-reference allele frequencies in the range 0.5-0.6 and 67% of those with frequencies > 0.9 could be detected. On average, ~3.7 SNPs/kb were detected by resequencing, with about 5% lower density on microchromosomes than on macrochromosomes. There was a positive correlation between the observed between-line SNP variation from the 60 K chip analysis and our proposed FSV score computed from the genome resequencing data. The strongest correlations on macrochromosomes and microchromosomes were observed when the FSV was calculated with total flanking regions of 62 kb (correlation 0.55) and 38 kb (correlation 0.45), respectively.Genome resequencing with limited coverage (~5X) using pooled DNA samples and three non-reference reads as a threshold for SNP detection, identified 50 - 67% of the 60 K SNPs with a non-reference allele frequency larger than 0.5. The SNP density was around 5% lower on the microchromosomes, most likely because of their higher gene content. Our proposed method to estimate the SNP variation (FSV) uses additional sequence information to better predict SNP informativity. The FSV scores showed higher correlations for SNPs with a larger difference in allele frequency between the populations. The correlation was strongest on macrochromosomes, probably due to a lower recombination rate.Next generation sequencing technologies and SNP-chip genotyping with genome-wide coverage are affordable high-throughput genomics tools that are now being used in many research projects. Thus, large amounts of data are being quickly generated that will increasingly require novel methods for efficient data mining and analysis. In man
Power Asymmetries in Small-Scale Fisheries: a Barrier to Governance Transformability?
Beatrice Crona,?rjan Bodin
Ecology and Society , 2010,
Abstract: Both global and local environmental problems call for the transformation of many contemporary and unsustainable governance approaches. Therefore, recent interest has sprung up around factors that facilitate and hinder societies from transforming governance of natural resources. Using a social-network approach, we study links between informal power structures and knowledge sharing and consensus building. We examine how this interaction may have affected the (in)ability of a community to move from open-access to some form of collective action for resource management. Individuals occupying central positions in a knowledge network can be instrumental in determining which knowledge and interpretation of ecological signals is most dominant. If the same individuals are also influential in other areas, they are highly likely to become opinion leaders. We use this notion of opinion leaders to frame our study. The study is set in a rural fishing community in East Africa where access to fishing equipment is of utmost importance for generating household income, but such gear ownership is not evenly distributed in the village. Hence, we use gear-exchange networks to explore power. Our results show a clear and strong relationship between centrality in the knowledge network and in-degree centrality (reflecting gear-lending capacity) in the gear-exchange network, supporting the idea that opinion leaders exist. We also indicate that a majority of these potential opinion leaders demonstrate little recognition of declining fisheries. We relate our findings to existing theories of influence and governance transformability at the community level, and explore ideas about how social networks can help identify potential change agents in communities experiencing inertia with respect to collective action for improved resource management.
What You Know is Who You Know? Communication Patterns Among Resource Users as a Prerequisite for Co-management
Abstract: The social networks is one factor determining the flow of information within communities and as such may be important in determining successful implementation of community based management. We mapped the social network used for communication of knowledge and information related to natural resource extraction among villagers in a coastal seascape in Kenya. We further identified subgroups and examined their interrelations while measuring to what extent personal attributes such as occupation can explain observed group structure. Finally, we compared the local ecological knowledge held by villagers of different occupations with the structure of the communication network to map how well this structure can explain distribution of ecological knowledge among them. Results show that communication occurs primarily between fishermen who use the same gear type, which may inhibit exchange of ecological knowledge within the community. This may partly explain why the community has been unsuccessful in regulating resource extraction, especially since potentially influential groups of nonfishermen have a limited communication with the various fisher groups. Analysis of network structure also shows that groups most central, and hence potentially most influential, are dominated in numbers by migrant deep sea fishermen, hypothetically less motivated to initiate collective action for resource management. Hence, we conclude that a lack of collective action to remedy an unsustainable situation may be attributed to various different but distinct aspects of the specific structure of the social network.
The Rethinking of the Economic Activity Based on Principles of Eco-Efficiency
Daniela V?RJAN
Theoretical and Applied Economics , 2011,
Abstract: Drought, floods, damaging storms, heat waves, acid rain, climate changes are but a few of the consequences of human action upon the environment. Can we possibly live against the environment? The answer is NO, and as such we must run an economy which respects the principles of eco-efficiency because only so can economic progress go on. Green economy is a great opportunity for all of the world's countries, and is a real economy which keeps the resource-needs and environment relation in balance, aims towards quality and not quantity, lays emphasis on regeneration, recycling, reuse and creativity. Eco-efficiency implies both innovation towards a high degree of product dematerialization, services and systems, alongside with greatly changing current production and consumption practices. If we produce based on the principle of eco-efficiency we can reduce the effects of the profound economic, ecological, socio-political and cultural-spiritual crisis which marks our planet and countries.