4,476 research outputs found
Solar-Terrestrial Simulations of CMEs with a Realistic Initiation Mechanism: Case Study for Active Region 10069
Most simulations of coronal mass ejections (CMEs) to date either focus on the
interplanetary propagation of a giant plasma "blob" without paying too much
attention to its origin and to the formation process or they focus on the
complex evolution of the coronal magnetic field due to (sub-)photospheric
motions which result in an eruption. Here, we present global simulations of
CMEs where coronal motions are used to produce a realistic evolution of the
coronal magnetic field and cause an eruption. We focus on active region 10069,
which produced a number of eruptions in late August 2002, including the August
24, 2002 CME - a fast (~2000 km/s) eruption originating from W81-, as well as a
slower eruption on August 22, 2002 (originating from W62). Using a
three-dimensional magneto-hydrodynamic (MHD) simulation of these ejections with
the Space Weather Modeling Framework (SWMF), we show how a realistic initiation
mechanism enables us to study the deflection of the CME in the corona and in
the heliosphere. Reconnection of the erupting magnetic field with that of
neighboring streamers and active regions modify the solar connectivity of the
field lines connecting to Earth and change the expected solar energetic
particle fluxes. Comparing the results at 1 AU of our simulations with in situ
observations by the ACE spacecraft, we propose an alternate solar origin for
the shock wave observed at L1 on August 26.Comment: 4 pages, 2 figures, refereed proceedings for Solar Wind 1
Charge transfer transitions in the photoluminescence spectra of Zn1-xMexO (Me = Mn, Ni, Co) oxide compounds
Crystals of Zn1-xCoxO and Zn1-xNixO are studied by photoluminescence at temperatures of 8 and 90 K. By resolving the spectra into sums of gaussian distributions and using the known positions of donor and acceptor levels of 3d-impurities relative to the edges of the allowed bands, the observed peaks in the photoluminescence spectra are interpreted in terms of radiative recombination through donor and acceptor levels of nickel and cobalt ions. These results are compared with previously observed features of the photoluminescence spectra of Zn1-xMnxO crystals. © 2013 American Institute of Physics
Understanding Anomalous Transport in Intermittent Maps: From Continuous Time Random Walks to Fractals
We show that the generalized diffusion coefficient of a subdiffusive
intermittent map is a fractal function of control parameters. A modified
continuous time random walk theory yields its coarse functional form and
correctly describes a dynamical phase transition from normal to anomalous
diffusion marked by strong suppression of diffusion. Similarly, the probability
density of moving particles is governed by a time-fractional diffusion equation
on coarse scales while exhibiting a specific fine structure. Approximations
beyond stochastic theory are derived from a generalized Taylor-Green-Kubo
formula.Comment: 4 pages, 3 eps figure
Periods of activity cycles in late-type stars
The mean magnetic field dynamo theory is utilized to obtain the qualitative dependence of the period of activity on the angular velocity of rotation for stars with sufficiently extensive convective shells. The dependence of the cycle period on the spectral class is also discussed
Phase Transitions in liquid Helium 3
The phase transitions of liquid Helium 3 are described by truncations of an
exact nonperturbative renormalization group equation. The location of the first
order transition lines and the jump in the order parameter are computed
quantitatively. At the triple point we find indications for partially universal
behaviour. We suggest experiments that could help to determine the effective
interactions between fermion pairs.Comment: 4 pages, 6 figures, LaTe
Pseudo-epsilon expansion and the two-dimensional Ising model
Starting from the five-loop renormalization-group expansions for the
two-dimensional Euclidean scalar \phi^4 field theory (field-theoretical version
of two-dimensional Ising model), pseudo-\epsilon expansions for the Wilson
fixed point coordinate g*, critical exponents, and the sextic effective
coupling constant g_6 are obtained. Pseudo-\epsilon expansions for g*, inverse
susceptibility exponent \gamma, and g_6 are found to possess a remarkable
property - higher-order terms in these expansions turn out to be so small that
accurate enough numerical estimates can be obtained using simple Pade
approximants, i. e. without addressing resummation procedures based upon the
Borel transformation.Comment: 4 pages, 4 tables, few misprints avoide
Post-Socialist Transformation of Central and Eastern Europe at the Turn of the Century: Regional Development and Economic Inequality
The evolution of socio-economic systems is non-linear, it includes both the periods of smooth changes and subsequent abrupt transformational leaps. The overall structure of new prospects opens as early as at the stage of emerging evolutionary processes, and their forecast requires to analyze the historical premises and risks that are closely associated with the change of public attitudes. With the collapse of the Soviet Union, the newly independent states went through a transformational and evolutionary development stage that led them from a regional economy (since they actually had been the regions) to the national economy, while the countries in Central and Eastern Europe experienced a dramatic drift towards the European Union. This paper examines the results of almost 25-year-long transformation of these countries. The new states that emerged following the collapse of the Soviet Union went through three types of transformation. First, there were transformations on the ideological level. The transformations of the second type were purely economic. The third type can be described as institutional (including structural and financial) transformation. It has been demonstrated that one of the important reasons for modest economic performance in the post-Soviet space was the fact that the new states ignored and did not use the principles of regional policy and regional modernization in their state-building practice. A characteristic feature in the socio-economic evolution of Eastern Europe after 1990 was a sharply emphasized process of stratification and social differentiation occurring against the backdrop of insufficiently strong middle class and the polarization of income levels in different regions. The growing polarization of income levels in different regions represents the dominant trend of rising economic inequality.This research has been conducted with the support of the Russian Science Foundation (the Grant No. 14–28–00065) "Structural and Cyclical Paradigm of Economic and Technological Renewal of Macro-Social Systems (World and Russia in the First Half of the 21st century).
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