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Search Results: 1 - 10 of 36 matches for " Indrek Mandre "
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Monte-Carlo study of scaling exponents of rough surfaces and correlated percolation
Indrek Mandre,Jaan Kalda
Physics , 2011, DOI: 10.1140/epjb/e2011-20386-4
Abstract: We calculate the scaling exponents of the two-dimensional correlated percolation cluster's hull and unscreened perimeter. Correlations are introduced through an underlying correlated random potential, which is used to define the state of bonds of a two-dimensional bond percolation model. Monte-Carlo simulations are run and the values of the scaling exponents are determined as functions of the Hurst exponent H in the range -0.75 <= H <= 1. The results confirm the conjectures of earlier studies.
Efficient method of finding scaling exponents from finite-size Monte-Carlo simulations
Indrek Mandre,Jaan Kalda
Physics , 2013, DOI: 10.1140/epjb/e2012-30954-7
Abstract: Monte-Carlo simulations are routinely used for estimating the scaling exponents of complex systems. However, due to finite-size effects, determining the exponent values is often difficult and not reliable. Here we present a novel technique of dealing with the problem of finite-size scaling. This new method allows not only to decrease the uncertainties of the scaling exponents, but makes it also possible to determine the exponents of the asymptotic corrections to the scaling laws. The efficiency of the technique is demonstrated by finding the scaling exponent of uncorrelated percolation cluster hulls.
Intersections of moving fractal sets
Indrek Mandre,Jaan Kalda
Physics , 2013, DOI: 10.1209/0295-5075/103/10012
Abstract: Intersection of a random fractal or self-affine set with a linear manifold or another fractal set is studied, assuming that one of the sets is in a translational motion with respect to the other. It is shown that the mass of such an intersection is a self-affine function of the relative position of the two sets. The corresponding Hurst exponent h is a function of the scaling exponents of the intersecting sets. A generic expression for h is provided, and its proof is offered for two cases --- intersection of a self-affine curve with a line, and of two fractal sets. The analytical results are tested using Monte-Carlo simulations.
Can Physics Save Social Sciences? Book Review:Making social sciences more scientific: the need for predictive models by Rein Taagepera, 2008, Oxford
Indrek Tart
Studies of Transition States and Societies , 2009,
Mis on filosoofia?
Indrek Reiland
Studia Philosophica Estonica , 2009,
Abstract: Minu eesm rgiks antud artiklis on pakkuda üht vaadet filosoofia olemuse, eesm rgi ja rolli kohta kaasaja maailmas. Artikli esimeses osas kirjeldan lühidalt nelja t nap eva filosoofiat oluliselt m jutanud filosoofiakontseptsiooni: ideaalkeele traditsiooni filosoofiam istmist, tavakeele filosoofia arusaamu, Wittgensteini terapeutilis-deflatsionalistlikku kontseptsiooni ning kaasaegse filosoofilise naturalismi metafilosoofiat. Teises osas visandan Wilfrid Sellarsist inspireerituna filosoofiam istmise, mis v imaldab meil n ha k iki eelnevalt k sitletud filosoofiakontseptsioone t itmas ühe ja sama projekti erinevaid osi ning m ista keskset osa kaasaja filosoofiast.
Naise kujutamine eesti nüüdisanekdootides: kriitiline ülevaade
Indrek Ojam
M?etagused. Hüperajakiri , 2012,
Abstract: This article discusses the representation of woman in Estonian punch-lined jokes. After brief introduction to the problems and approaches of this field the author presents the results of the extensive research, which consisted of the survey of 1869 jokes. Jokes representing female characters had to contain one of the four most neutral keywords: woman, mother, wife and maiden (young woman in Estonian). These jokes were collected from the Internet and stem from the years 1960–2010 and are categorised using the program QDA-miner, which enables both quantitative and qualitative methods. However, the main emphasis in the approach is on the critical interpretation of the results.The jokes were divided into 4 major subcategories: 1) location of the joke; 2) the interaction partners of woman; 3) sexual content; 4) the role of the woman (active, submissive, neutral). The most frequent location for the joke was homely environment. Woman interacted in the jokes mostly with her husband, children and other family members. Surprisingly, only 27% of the material contained any kind of sex-related circumstances. The fourth and most ambiguous (open to interpretation) category was the role of the woman. It was also the focal point of my critical approach. The results show generally, that the picture of woman in Estonian jokes is rather passive and one-sided. In literally half of the jokes, woman had merely episodical role. Woman was clearly the target of the joke in 32% of the jokes and active protagonist in the rest 18%. Although it seems, that the female character had often something meaningful to say in jokes, closer look reveals that it was not the case. Even in the jokes where the woman was active, her role was still very stereotypical and reflected rather the point of view of men telling the jokes or the construction of male identity in general.These tendencies show, that the representation of woman in estonian joke material is quite static throughout the period of 1960s until the first decade of the 21st century. I maintain, that this phenomenon cannot be explained with the simple persistence of sexism and misogyny in society. One other way of explaining it, is that the inherent stability of the genre of punch-lined joke does not let new discourses appear in it. Researchers should look for other new humorous genres for more critical and complex representation of gender and femininity.
Fjodor Fjodorovits Martensi “Eraomandi igusest s ja ajal”
Indrek Olmaru
Acta Societatis Martensis , 2005,
Anatomical structure and localisation of lignin in needles and shoots of Scots pine (Pinus sylvestris L.) growing in a habitat with varying environmental characteristics
Aljona Lukjanova, Malle Mandre
Forestry Studies / Metsanduslikud Uurimused , 2008, DOI: 10.2478/v10132-011-0061-2
Abstract: We investigated the influence of a habitat with varying environmental characteristics on the anatomical structure and localisation of lignin in needles and shoots of Scots pine (Pinus sylvestris L.). A dune in South-West Estonia was chosen as the study area because it has extreme environmental characteristics: primitive sandy soil, deficiency of water, heavy winds and high light exposure. Analysis showed that the needles of all age and the current-year shoots of pines growing on the foot of the dune had the largest average cross section, mesophyll and parenchyma areas. The degree of the lignification of needles at the foot, on the slope and on the top of the dune differed distinctly. Intensive lignification of the cellular walls of the xylem was observed in needles and shoots of the pines, growing at the foot, but not in the trees growing on the top of the dune. Analysis showed that the anatomical structure and localisation of lignin, both in needles and in shoots, depend on their age, the trees location (foot, slope or top of the dune) and soil mineral composition.
Theory of Compton scattering by anisotropic electrons
Juri Poutanen,Indrek Vurm
Physics , 2010, DOI: 10.1088/0067-0049/189/2/286
Abstract: Compton scattering plays an important role in various astrophysical objects such as accreting black holes and neutron stars, pulsars, and relativistic jets, clusters of galaxies as well as the early Universe. In most of the calculations it is assumed that the electrons have isotropic angular distribution in some frame. However, there are situations where the anisotropy may be significant due to the bulk motions, or anisotropic cooling by synchrotron radiation, or anisotropic source of seed soft photons. We develop here an analytical theory of Compton scattering by anisotropic distribution of electrons that can simplify significantly the calculations. Assuming that the electron angular distribution can be represented by a second order polynomial over cosine of some angle (dipole and quadrupole anisotropy), we integrate the exact Klein-Nishina cross-section over the angles. Exact analytical and approximate formulae valid for any photon and electron energies are derived for the redistribution functions describing Compton scattering of photons with arbitrary angular distribution by anisotropic electrons. The analytical expressions for the corresponding photon scattering cross-section on such electrons as well as the mean energy of scattered photons, its dispersion and radiation pressure force are also derived. We applied the developed formalism to the accurate calculations of the thermal and kinematic Sunyaev-Zeldovich effects for arbitrary electron distributions.
Radiative Transfer Models for Gamma-Ray Bursts
Indrek Vurm,Andrei M. Beloborodov
Physics , 2015,
Abstract: We present global radiative transfer models for heated relativistic jets. The simulations include all relevant radiative processes, starting deep in the opaque zone and following the evolution of radiation to and beyond the photosphere of the jet. The transfer models are compared with three gamma-ray bursts GRB 990123, GRB 090902B, and GRB 130427A, which have well-measured and different spectra. The models provide good fits to the observed spectra in all three cases. The fits give estimates for the jet magnetization parameter $\varepsilon_{\rm B}$ and the Lorentz factor $\Gamma$. In the small sample of three bursts, $\varepsilon_{\rm B}$ varies between 0.01 and 0.1, and $\Gamma$ varies between 340 and 1200.
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