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Search Results: 1 - 10 of 550 matches for " Petter Wabakken "
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Selection for Heterozygosity Gives Hope to a Wild Population of Inbred Wolves
Staffan Bensch, Henrik Andrén, Bengt Hansson, Hans Chr. Pedersen, H?kan Sand, Douglas Sejberg, Petter Wabakken, Mikael ?kesson, Olof Liberg
PLOS ONE , 2006, DOI: 10.1371/journal.pone.0000072
Abstract: Recent analyses have questioned the usefulness of heterozygosity estimates as measures of the inbreeding coefficient (f), a finding that may have dramatic consequences for the management of endangered populations. We confirm that f and heterozygosity is poorly correlated in a wild and highly inbred wolf population. Yet, our data show that for each level of f, it was the most heterozygous wolves that established themselves as breeders, a selection process that seems to have decelerated the loss of heterozygosity in the population despite a steady increase of f. The markers contributing to the positive relationship between heterozygosity and breeding success were found to be located on different chromosomes, but there was a substantial amount of linkage disequilibrium in the population, indicating that the markers are reflecting heterozygosity over relatively wide genomic regions. Following our results we recommend that management programs of endangered populations include estimates of both f and heterozygosity, as they may contribute with complementary information about population viability.
Effect of temperature on crossing over in the mus309 mutant, deficient in DNA double-strand break repair, of Drosophila melanogaster suggests a mechanism for crossover interference  [PDF]
Petter Portin
Open Journal of Genetics (OJGen) , 2011, DOI: 10.4236/ojgen.2011.13008
Abstract: Crossing-over frequencies, crossover interference, recombination frequencies and map distances were compared in the cv-v-f region of the X chromosome of Drosophila melanogaster in females bearing either wild type 3rd chromosomes (control) or having the DNA double-strand break repair deficient mus309D2/mus309D3 mutant constitution in the 3rd chromosomes (experiment), and raised in three different temperatures viz. 18C, 25C and 29C. In addition, the fecundity of the females was also measured. In the control crosses none of the mean values of the parameters measured was dependent on the temperature, whereas in the experimental crosses all the parameters, except for the frequency of true single crossovers in the cv-v interval, the recombination frequency of the v and f markers, and the coefficient of coincidence, changed due to the effect of temperature. When comparing the genotypes studied, a significant difference between them was observed in all the parameters measured, apart from the frequency of the true single cross-overs in the cv-v interval. These results support the counting number model of the mechanism of interference based on the genetic distance, but are in contradiction with the models based on physical distance.
The mus309 mutation, defective in DNA double-strand break repair, increases the frequency of X-ray-induced somatic crossing over in Drosophila melanogaster, but the effect is not dose-rate dependent  [PDF]
Petter Portin
Open Journal of Genetics (OJGen) , 2012, DOI: 10.4236/ojgen.2012.21004
Abstract: Effect of a 1000 R dose of hard X-rays, with two different dose-rates viz. 300 and 1000 R/min on somatic crossing over in the X chromosome of Drosophila melanogaster was studied in two different genotypes. Irradiation was given during the first-instar larval stage of the development. In the control crosses the flies carried wild-type autosomes, but in the experimental crosses the 3rd chromosomes carried a DNA double-strand break repair deficient mus309 mutant gene constitution. As expected, the frequency of X-ray-induced somatic crossing over increased in the mutant flies with both dose-rates of irradiation. As also expected, in the control flies irradiation given with the 300 R/min dose-rate caused more somatic crossovers than irradiation given with the 1000 R/ min rate. However, rather unexpectedly, in the experimental flies there was no significant difference in the frequency of somatic crossing over between the two dose-rates of irradiation. The results can be explained by assuming that X-ray-induced somatic crossing over is a two-step event, and that the mechanism which repairs the lesion caused by the irradiation is controlled by the mus309 gene. In the control flies the repairing mechanism is capable to recover if the irradiation is given with a short term high dose-rate, but is not capable to recover if the irradiation is given with a long lasting low dose-rate. However, in the experimental mutant flies the repairing mechanism is only poorly recovered irrespective of the dose-rate.
On the claimed “circularity” of the theory of natural selection  [PDF]
Petter Portin
Open Journal of Genetics (OJGen) , 2012, DOI: 10.4236/ojgen.2012.22012
Abstract: First, the numerous claims that the theory of natural selection would be a tautology, just empty circular reasoning, are shown to be erroneous, and that they follow from an essentialistic and deterministic way of thinking, which is not consistent with the dynamic theory of evolution. Secondly, it is proposed that a careful analysis applying Fisher’s Fundamental Theorem of Natural Selection of the seemingly tautologous sentence in question: “those who reproduce most, reproduce most” shows that in actual fact it is a predictive statement. Consequently, the analysis presented reduces the essence of the theory of natural selection to that one single statement.
Further evidence for the theory that crossover interference in Drosophila melanogaster is dependent on genetic rather than physical distance between adjacent crossover points  [PDF]
Petter Portin
Open Journal of Genetics (OJGen) , 2012, DOI: 10.4236/ojgen.2012.23020
Abstract: Effect of heat shock on certain meiotic parameters in Drosophila melanogaster was studied in the cv-v-f region of the X chromosome of females homozygous for mus309 mutation, deficient in DNA double-strand break repair, or being of wild type. The heat shock in the wild females caused that the frequencies of the single crossovers and all the map lengths decreased while the frequency of the double crossovers and crossover interference remained unchanged. In the mus309 mutants all parameters remained unchanged except that single crossovers in the cv-v interval were less frequent, and that crossover interference diminished. Thus, heat shock seems have two separate effects; one being independent on the mus309 gene and affecting the occurrence of crossing over itself, and the other being dependent on the mus309 gene and affecting some precondition of crossing over. This precondition is probably the choice between two routes of the repair of double-strand DNA breaks known to be controlled by the mus309 gene. The results are in accordance with the genetic models of interference in which interference depends on genetic distance between the crossover points, but in contradiction with physical models where interference is dependent on physical distance between the crossover points.
Further evidence for the theory that crossover interference in Drosophila melanogaster is dependent on genetic rather than physical distance between adjacent crossover points  [PDF]
Petter Portin
Open Journal of Genetics (OJGen) , 2013, DOI: 10.4236/ojgen.2013.32012
Abstract:

The effect of heat shock on certain meiotic parameters in Drosophila melanogaster was studied in the cv v f region of the X chromosome of females homozygous for the mus309 mutation, deficient in DNA double-strand break repair, or those of wild type. The heat shock in the wild females caused the frequencies of the single crossovers and double crossovers and all the map lengths to decrease while crossover interference remained unchanged. In the mus309 mutants all parameters, crossover interference included, remained unchanged despite the heat shock treatment. However, the mus309 mutation had a significant effect on all meiotic parameters both in the females not given the heat shock and in the heat shocked females with the exception that the recombination frequency of the v and f markers was the same in both genotypes in the females not given the heat shock. It seems that the heat shock treatment has an effect on crossing over which is independent on the mus309 gene and affecting the occurrence of crossing over itself. On the other hand, the mus309 gene has an effect on crossing over which is independent of the heat shock treatment and affects some precondition of crossing over. This precondition is probably the choice between two routes of the repair of double-strand DNA breaks known to be controlled by the mus309 gene. As explained in the discussion, the results are in accordance with the genetic models of interference in which interference depends on genetic distance between the crossover points, but in contradiction with physical models where interference is dependent on physical distance between the crossover points.

Clinical Sociology and Moral Hegemony  [PDF]
Hans Petter Sand
Advances in Applied Sociology (AASoci) , 2013, DOI: 10.4236/aasoci.2013.37034
Abstract: The article presents a critique of a dominant way of analysing gang conflict in Norwegian sociology. The research in question uses a rather crude Marxist analysis that could somehow fit any gang conflict in the country. However, this kind of analysis was gradually put in question first by professor Ottar Brox and his criticism of the moral hegemony by a group of Marxists gathered around the publication “Klassekampen” (“Class Struggle”). Then the analysis was challenged by gang-researchers who reached back to the classical study of Frederic M. Thrasher, finding the latter more fruitful for analysis. Antonio Gramsci (1891- 1937) who coined the term cultural hegemony used it to describe how a social class can manipulate the system of values in a society to establish a ruling class world-view. In my context the term moral hegemony is used to show how an intellectual group came to dominate the discourse on relations between Norwegians and immigrants, labelling other views as “racist”.
How Do Principal-Agent Effects in Delegated Portfolio Management Affect Asset Prices?  [PDF]
Petter N. Kolm
Journal of Mathematical Finance (JMF) , 2013, DOI: 10.4236/jmf.2013.34042
Abstract:

We investigate the impact of delegated portfolio management on asset prices in a noisy rational equilibrium model. Asset prices in our model are linear in fund managers’ private signals and in realized supply shocks. We show that equilibrium expected returns 1) decrease as the proportion of fund managers increase in the economy; 2) decrease as the precision of fund managers’ signals increase and 3) increase as the fund managers’ contingent fees increase.

Applied Social Anthropology in the Researcher’s Own Society  [PDF]
Hans Petter Sand
Advances in Applied Sociology (AASoci) , 2014, DOI: 10.4236/aasoci.2014.42009
Abstract:

Professor Arne Martin Klausen (1927-) is the only social anthropologist in Norway who has tried to analyse the culture of the country as a whole. In doing this, he has explored several central themes of the country’s culture; like egalitarianism, the class journey, the strong tradition for development aid to poor countries, connected to a so-called humanitarian super-power which in its turn was an extension of Christian mission, the very wide-spread newspaper reading; however self-centered to national and local issues and finally, the collision between an elitist Olympic culture with Norwegian egalitarianism. Klausen also tried to tie some threads together in editing a collection of essays on Norwegian culture.

Norwegian Sociology and the Recognition of the Saami Minority  [PDF]
Hans Petter Sand
Advances in Applied Sociology (AASoci) , 2014, DOI: 10.4236/aasoci.2014.45017
Abstract:


At a time when the Saami ethnic minority got little attention by the Norwegian public and the political authorities of the country, sociologists did much to raise public awareness about the conditions of this ethnic minority. In the postwar period of the 1950s and 1960s, sociologists of Norway focused to a large degree on social groups that fell outside the emerging welfare state. Norwegian sociology has been characterized by an approach named “problem-oriented empirism” and also by sociologists playing a vital role as public intellectuals. Sociology professor Vilhelm Aubert (1922- 88) coined the term “problem-oriented empirism” to characterize Norwegian sociology from the end of the Second World War to around 1975. Empirism refers to the importance of sociology being close to social reality. Problem-orientation refers to the importance of choosing research questions that are not only scientifically interesting, but also relevant to society. Vilhelm Aubert was also a leading figure among sociologists playing the role of public intellectuals in this period. Problem-oriented empirism and sociologists as public intellectuals have in particular been the case with regard to Saami research.


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