MHD discontinuity ve slunečním větru a jejich vztah k procesům v zemské magnetosféře

Název práce: MHD discontinuity ve slunečním větru a jejich vztah k procesům v zemské magnetosféře Autor: Oleksandr Goncharov Katedra / Ústav: Katedra fyziky povrchů a plazmatu, MFF UK Vedoucí doktorské práce: Prof. RNDr. Jana Šafránková, DrSc. Abstrakt: Rázové vlny v bezesrážkovém plazmatu jsou přítomné v celé heliosféře od sluneční korony do terminátorové rázové vlny. Rázové vlny hrají podstatnou roli v interakci slunečního větru s planetami, protože účinně konvertují energii orientovaného iontového toku do ohřevu iontů a elektronů, do zvýšení magnetického pole a do urychlování nabitých částic. Dominantním cílem předložené disertační práce je výzkum vývoje výrazných struktur slunečního větru, zaměřený hlavně na meziplanetární rázové vlny, jejich interakci s vnějšími hranicemi magnetosféry (okolozemní rázová vlna a magnetopauza) a na sledování modifikace výsledných produktů této interakce v magnetosféře a jejím chvostu. Metodika výzkumu je založena jak na statistických studiích využívajících více-družicová pozorování, tak na analýze jednotlivých případových událostí. Některé experimentální studie jsou doplněny počítačovým modelováním. Rychlá měření parametrů plazmatu uskutečněná družicí Spektr-R nám umožňují i podrobné studium vlastní jemné struktury meziplanetární rázové vlny a jejích variací. Klíčová...1 Title: MHD discontinuities in the solar wind and their relation to processes in the Earth magnetosphere Author: Oleksandr Goncharov Department / Institute: Department of Surface and Plasma Science, Faculty of Mathematics and Physics, Charles University Supervisor of the doctoral thesis: Prof. RNDr. Jana Safrankova, DrSc Abstract: Collisionless shocks are ubiquitous in the heliosphere from the outer corona to the termination shock. They play an important role in the interaction of the solar wind with the planets because they efficiently convert the energy of the directed ion flow into the energy of heated ions and electrons, the energy of the enhanced magnetic field, and the energy of the accelerated particles. The leading idea of the thesis is to investigate evolution of distinct solar wind features, predominantly interplanetary shocks, within the solar wind, their interaction with the outer magnetospheric boundaries (magnetopause and bow shock), and to follow a path of resulting discontinuities through the magnetosphere up to its far tail. The methodology is based on the statistical evaluation of multispacecraft observations as well as on case studies of particular events. Some experimental investigations are supported with computer modeling. Moreover, an application of fast plasma measurements of the...Katedra fyziky povrchů a plazmatuDepartment of Surface and Plasma ScienceMatematicko-fyzikální fakultaFaculty of Mathematics and Physic

Hydrology and parasites : What divides the fish community of the lower Dniester and Dniester estuary into three?

Acknowledgments This research was carried out under the framework of research activities funded by the Ministry of Education and Science of Ukraine(2003–2013) and European FP7 projects No. 226740 EnviroGrids (Building Capacity for a Black Sea Catchment Observation and Assessment System supporting Sustainable Development), No. 287600 PERSEUS “Policy-oriented marine Environmental Research for the Southern European Seas”, TACIS CBC Programme Technical Assistance for Lower Dniester basin water management planning (2006–2007) and the "Cross-border cooperation and sustainable management in the Dniester River basin: Phase III - Implementation of the Action Programme", OSCE, UNEP (2011)Peer reviewedPublisher PD

Superhardness Effect in TransitionMetal Diborides Films

The structure, composition, and properties of transitionmetal diboride films have been studied. It was shown that they are characterized by a wide range of structural states, namely from amorphouslike to nanocrystalline with crystallite sizes of 1–50 nm. The characteristic peculiarity of the structure of film transitionmetal diborides with high physical and mechanical properties is the formation of a nanocrystalline (columnar) structure with the growth texture in plane [00.1] and a nanocrystallite size of 20–50 nm. The element composition of a superhard highly textured film transitionmetal diborides was studied by ion mass spectrometry and Auger electron spectroscopy. The overstoichiometry effect in nanocrystalline transition metal diboride films is explained. It was shown that this effect is related to the formation of an additional B⎯B covalent bond, which is realized at subgrain boundaries and leads to the appearance of superhardness in the formed coatings. Keyw

Superhardness Effect in TransitionMetal Diborides Films

The structure, composition, and properties of transitionmetal diboride films have been studied. It was shown that they are characterized by a wide range of structural states, namely from amorphouslike to nanocrystalline with crystallite sizes of 1–50 nm. The characteristic peculiarity of the structure of film transitionmetal diborides with high physical and mechanical properties is the formation of a nanocrystalline (columnar) structure with the growth texture in plane [00.1] and a nanocrystallite size of 20–50 nm. The element composition of a superhard highly textured film transitionmetal diborides was studied by ion mass spectrometry and Auger electron spectroscopy. The overstoichiometry effect in nanocrystalline transition metal diboride films is explained. It was shown that this effect is related to the formation of an additional B⎯B covalent bond, which is realized at subgrain boundaries and leads to the appearance of superhardness in the formed coatings. Keyw

Measurement of the top quark forward-backward production asymmetry and the anomalous chromoelectric and chromomagnetic moments in pp collisions at √s = 13 TeV

Abstract The parton-level top quark (t) forward-backward asymmetry and the anomalous chromoelectric (d̂ t) and chromomagnetic (μ̂ t) moments have been measured using LHC pp collisions at a center-of-mass energy of 13 TeV, collected in the CMS detector in a data sample corresponding to an integrated luminosity of 35.9 fb−1. The linearized variable AFB(1) is used to approximate the asymmetry. Candidate t t ¯ events decaying to a muon or electron and jets in final states with low and high Lorentz boosts are selected and reconstructed using a fit of the kinematic distributions of the decay products to those expected for t t ¯ final states. The values found for the parameters are AFB(1)=0.048−0.087+0.095(stat)−0.029+0.020(syst),μ̂t=−0.024−0.009+0.013(stat)−0.011+0.016(syst), and a limit is placed on the magnitude of | d̂ t| < 0.03 at 95% confidence level. [Figure not available: see fulltext.

Measurement of t(t)over-bar normalised multi-differential cross sections in pp collisions at root s=13 TeV, and simultaneous determination of the strong coupling strength, top quark pole mass, and parton distribution functions

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An embedding technique to determine ττ backgrounds in proton-proton collision data

An embedding technique is presented to estimate standard model tau tau backgrounds from data with minimal simulation input. In the data, the muons are removed from reconstructed mu mu events and replaced with simulated tau leptons with the same kinematic properties. In this way, a set of hybrid events is obtained that does not rely on simulation except for the decay of the tau leptons. The challenges in describing the underlying event or the production of associated jets in the simulation are avoided. The technique described in this paper was developed for CMS. Its validation and the inherent uncertainties are also discussed. The demonstration of the performance of the technique is based on a sample of proton-proton collisions collected by CMS in 2017 at root s = 13 TeV corresponding to an integrated luminosity of 41.5 fb(-1).Peer reviewe

Measurement of the Splitting Function in &ITpp &ITand Pb-Pb Collisions at root&ITsNN&IT=5.02 TeV

Data from heavy ion collisions suggest that the evolution of a parton shower is modified by interactions with the color charges in the dense partonic medium created in these collisions, but it is not known where in the shower evolution the modifications occur. The momentum ratio of the two leading partons, resolved as subjets, provides information about the parton shower evolution. This substructure observable, known as the splitting function, reflects the process of a parton splitting into two other partons and has been measured for jets with transverse momentum between 140 and 500 GeV, in pp and PbPb collisions at a center-of-mass energy of 5.02 TeV per nucleon pair. In central PbPb collisions, the splitting function indicates a more unbalanced momentum ratio, compared to peripheral PbPb and pp collisions.. The measurements are compared to various predictions from event generators and analytical calculations.Peer reviewe

MUSiC : a model-unspecific search for new physics in proton-proton collisions at root s=13TeV

Results of the Model Unspecific Search in CMS (MUSiC), using proton-proton collision data recorded at the LHC at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb(-1), are presented. The MUSiC analysis searches for anomalies that could be signatures of physics beyond the standard model. The analysis is based on the comparison of observed data with the standard model prediction, as determined from simulation, in several hundred final states and multiple kinematic distributions. Events containing at least one electron or muon are classified based on their final state topology, and an automated search algorithm surveys the observed data for deviations from the prediction. The sensitivity of the search is validated using multiple methods. No significant deviations from the predictions have been observed. For a wide range of final state topologies, agreement is found between the data and the standard model simulation. This analysis complements dedicated search analyses by significantly expanding the range of final states covered using a model independent approach with the largest data set to date to probe phase space regions beyond the reach of previous general searches.Peer reviewe