631 research outputs found
Tunneling of Born-Infeld Strings to D2-Branes
A Born-Infeld theory describing a D2-brane coupled to a 4-form RR field
strength is considered, and the general solutions of the static and Euclidean
time equations are derived and discussed. The period of the bounce solutions is
shown to allow a consideration of tunneling and quantum-classical transitions
in the sphaleron region. The order of such transitions, depending on the
strength of the RR field strength, is determined. A criterion is then derived
to confirm these findings.Comment: 20 pages, 7 postscript figures, will appear in NP
Impact of external migration on changes in the Swedish religious landscape
For most of its history, Sweden has been a country dominated by the Lutheran Church, having the status of the official state religion. Starting in mid-to-late 20th century, mass immigration to Europe had a considerable impact on the confessional structure of Sweden’s population. The growing number of refugees from the Balkan Peninsula, the Middle East, and Africa has turned Sweden into a multi-religious state. Sweden has become one of the leaders among the EU countries as far as the growth rates of adherents of Islam are concerned. Immigrants are exposed to adaptation difficulties causing their social, cultural and geographical isolation and making relatively isolated migrant communities emerge. This study aims at finding correlation between the changes in the confessional structure of Swedish population (as a result of the growing number of non-Christians) and the geographical structure of migrant flows into the country. This novel study addresses the mosaic structure of the Swedish religious landscape taking into account the cyclical dynamics of replacement of Protestantism by Islam. The methods we created make it possible to identify further trends in the Sweden’s religious landscape. This study adds to results of the complex sociological and demographic studies of the confessional structure of the Swedish population
Singularities of the renormalization group flow for random elastic manifolds
We consider the singularities of the zero temperature renormalization group
flow for random elastic manifolds. When starting from small scales, this flow
goes through two particular points and , where the average value
of the random squared potential turnes negative ($l^{*}$) and where
the fourth derivative of the potential correlator becomes infinite at the
origin ($l_{c}$). The latter point sets the scale where simple perturbation
theory breaks down as a consequence of the competition between many metastable
states. We show that under physically well defined circumstances $l_{c} to negative values does not
take place.Comment: RevTeX, 3 page
Refugees from Syria and Iraq in Sweden: resettlement during the migration crisis
The vast increase in the number of forced migrants during the European migration crisis has compelled the receiving countries to concentrate on the issues of migrant reception and accommodation. This study aims to demonstrate how the patterns of settlement of Syrian and Iraqi migrants changed in 2014-2019. We propose a new methodology, building on the Herfindahl-Hirschman index, an indicator of the level and direction of the spatial concentration - deconcentration of migrants, and the Ryabtsev index, which is used to measure the proximity between the settlement structures of migrants and the Swedes. It is established there was a deconcentration of migrants during the crisis (especially in its ascendant phase), carried out by the Swedish authorities. However a reverse process took place in the descendant phase, as a result of self-arranged migrants’ resettlement. The deconcentration of Iraqis and Syrians led to the convergence between the settlement structure typical of immigrants and the Swedes, whilst concentration resulted in divergence accompanied by the emergence of close-knit immigrant communities on the outskirts of Sweden’s largest cities. The formation of such communities, seen as vulnerable by the national authorities and marked by a high crime rate, impedes the integration of Syrian and Iraqi immigrants into Swedish society
A condition for first order phase transitions in quantum mechanical tunneling models
A criterion is derived for the determination of parameter domains of first
order phase transitions in quantum mechanical tunneling models. The criterion
is tested by application to various models, in particular to some which have
been used recently to explore spin tunneling in macroscopic particles. In each
case agreement is found with previously heuristically determined domains.Comment: 13 pages, 5 figure
Metastability of (d+n)-dimensional elastic manifolds
We investigate the depinning of a massive elastic manifold with internal
dimensions, embedded in a -dimensional space, and subject to an
isotropic pinning potential The tunneling process is
driven by a small external force We find the zero temperature and
high temperature instantons and show that for the case the
problem exhibits a sharp transition from quantum to classical behavior: At low
temperatures the Euclidean action is constant up to exponentially
small corrections, while for The results are universal and do not depend on the detailed shape
of the trapping potential . Possible applications of the problem to
the depinning of vortices in high- superconductors and nucleation in
-dimensional phase transitions are discussed. In addition, we determine the
high-temperature asymptotics of the preexponential factor for the
-dimensional problem.Comment: RevTeX, 10 pages, 3 figures inserte
A description of a system of programs for mathematically processing on unified series (YeS) computers photographic images of the Earth taken from spacecraft
A description of a batch of programs for the YeS-1040 computer combined into an automated system for processing photo (and video) images of the Earth's surface, taken from spacecraft, is presented. Individual programs with the detailed discussion of the algorithmic and programmatic facilities needed by the user are presented. The basic principles for assembling the system, and the control programs are included. The exchange format within whose framework the cataloging of any programs recommended for the system of processing will be activated in the future is displayed
Thermally activated Hall creep of flux lines from a columnar defect
We analyse the thermally activated depinning of an elastic string (line
tension ) governed by Hall dynamics from a columnar defect modelled
as a cylindrical potential well of depth for the case of a small
external force An effective 1D field Hamiltonian is derived in order to
describe the 2D string motion. At high temperatures the decay rate is
proportional to with a constant of order of the
critical force and U(F) \sim{\left ({\epsilon V_{0}})}^{{1}/{2}}{V_{0}/{F}}
the activation energy. The results are applied to vortices pinned by columnar
defects in superclean superconductors.Comment: 12 pages, RevTeX, 2 figures inserte
Free-energy distribution functions for the randomly forced directed polymer
We study the -dimensional random directed polymer problem, i.e., an
elastic string subject to a Gaussian random potential and
confined within a plane. We mainly concentrate on the short-scale and
finite-temperature behavior of this problem described by a short- but
finite-ranged disorder correlator and introduce two types of
approximations amenable to exact solutions. Expanding the disorder potential
at short distances, we study the
random force (or Larkin) problem with as well as the shifted
random force problem including the random offset ; as such, these
models remain well defined at all scales. Alternatively, we analyze the
harmonic approximation to the correlator in a consistent manner.
Using direct averaging as well as the replica technique, we derive the
distribution functions and of free energies
of a polymer of length for both fixed () and free boundary
conditions on the displacement field and determine the mean
displacement correlators on the distance . The inconsistencies encountered
in the analysis of the harmonic approximation to the correlator are traced back
to its non-spectral correlator; we discuss how to implement this approximation
in a proper way and present a general criterion for physically admissible
disorder correlators .Comment: 16 pages, 5 figure
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