11,330 research outputs found
Functional Urban Areas as the Focus of Development Policy in Poland
This article presents the premises, current status and the prospects of using functional urban areas as the focus of Poland's development policy. For the past 10 years, cities, especially large ones, have been increasingly impacting on their surrounding areas defined as functional urban areas. The size of those areas is determined by the process of suburbanisation. The article emphasises the issue of uncoordinated development of functional urban areas surrounding core cities and on grassroot and top-down attempts to integrate their development
Architecture of Poland as the Heritage of the Past in the Present. Castles, palaces and mansions, historic cities
The present book “Poland – History, Culture and Society. Selected Readings” is the third edition of a collection of academic texts written with the intention to accompany the module by providing incoming students with teaching materials that will assist them in their studies of the course module and encourage further search for relevant information and data. The papers collected in the book have been authored by academic teachers from the University of Łódź, specialists in such fields as history, geography, literature, sociology, ethnology, cultural studies, and political science. Each author presents one chapter related to a topic included in the module or extending its contents. The book contains the extensive bibliography
Screening at finite temperature and density
We present lattice QCD results on heavy quark free energies, extract from its
temperature dependence entropy and internal energy contributions, and discuss
the onset of medium effects that lead to screening of static quark-antiquark
sources in a thermal medium. Most results are obtained in (2+1)-flavour QCD on
a line of constant physics with almost realistic quark masses and compared to
previous results from 2-flavor QCD as well as pure gauge theory. Furthermore,
we discuss results on the density dependence of screening masses that have been
obtained using a leading order Taylor expansion in the baryon chemical
potential.Comment: 10 pages, 15 figures, Presented at Critical Point and Onset of
Deconfinement 4th International Workshop, GSI Darmstadt, Germany, July 9-13
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Abstract objects: Species, Kinds, Concepts
In the paper I present Kotarbiński’s approach to abstract objects and show some mistakes in his investigations. By formal ontology I try to explain Kotarbiński’s view and proffer a new solution, a formal solution that is – I hope – in the spirit of Lvov–Warsaw (Lwów–Warsaw) School
Continuum estimate of the heavy quark momentum diffusion coefficient
Among quantities playing a central role in the theoretical interpretation of
heavy ion collision experiments at RHIC and LHC are so-called transport
coefficients. Out of those heavy quark diffusion coefficients play an important
role e.g. for the analysis of the quenching of jets containing c or b quarks (D
or B mesons) as observed at RHIC and LHC. We report on a lattice investigation
of heavy quark momentum diffusion within pure SU(3) plasma above the
deconfinement transition with the quarks treated to leading order in the heavy
mass expansion. We measure the relevant colour-electric Euclidean correlator
and based on several lattice spacings perform the continuum extrapolation. This
extends our previous studies progressing towards a removal of lattice artifacts
and a physical interpretation of the results. We find that the correlation
function clearly exceeds its perturbative counterpart which suggests that at
temperatures just above the critical one, non-perturbative interactions felt by
the heavy quarks are stronger than within the weak-coupling expansion. Using an
Ansatz for the spectral function which includes NNLO perturbative contributions
we were able to determine, for the first time, a continuum estimate for the
heavy quark momentum diffusion coefficient.Comment: 4 pages, 4 figures, to appear in the proceedings of the 24th
International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions
(Quark Matter 2014), accepted version to appear in Nucl.Phys.
Heavy quark free energies for three quark systems at finite temperature
We study the free energy of static three quark systems in singlet, octet,
decuplet and average color channels in the quenched approximation and in
2-flavor QCD at finite temperature. We show that in the high temperature phase
singlet and decuplet free energies of three quark systems are well described by
the sum of the free energies of three diquark systems plus self energy
contributions of the three quarks. In the confining low temperature phase we
find evidence for a Y-shaped flux tube in SU(3) pure gauge theory, which is
less evident in 2-flavor QCD due to the onset of string breaking. We also
compare the short distance behavior of octet and decuplet free energies to the
free energies of single static quarks in the corresponding color
representations.Comment: 11 pages, 17 figure
The Problem of Mass: Mesonic Bound States Above T_c
We discuss the problem of mass, noting that meson masses decrease with
increasing scale as the dynamically generated condensate of "soft glue" is
melted (Brown/Rho scaling). We then extend the Bielefeld LGS color singlet
interaction computed for heavy quarks in a model-dependent way by including the
Ampere law velocity-velocity interaction. Parameterizing the resulting
interaction in terms of effective strength of the potential and including
screening, we find that the masses of pi, sigma, rho and A1 excitations, 32
degrees of freedom in all, go to zero (in the chiral limit) as T goes to Tc
essentially independently of the input quark (thermal) masses in the range of
1-2 GeV, calculated also in Bielefeld. We discuss other LGS which show q-bar q
bound states, which we interpret as our chirally restored mesons, for T > Tc.Comment: 20 pages, 6 figures (Table 2 is added
Screening of heavy quark free energies at finite temperature and non-zero baryon chemical potential
We analyze the dependence of heavy quark free energies on the baryon chemical
potential (mu_b) in 2-flavour QCD using improved (p4) staggered fermions with a
bare quark mass of m/T = 0.4. By performing a 6th order Taylor expansion in the
chemical potential which circumvents the sign problem. The Taylor expansion
coefficients of colour singlet and colour averaged free energies are calculated
and from this the expansion coefficients for the corresponding screening masses
are determined. We find that for small mu_b the free energies of a static quark
anti-quark pair decrease in a medium with a net excess of quarks and that
screening is well described by a screening mass which increases with increasing
mu_b. The mu_b-dependent corrections to the screening masses are well described
by perturbation theory for T > 2 T_c. In particular, we find for all
temperatures above T_c that the expansion coefficients for singlet and colour
averaged screening masses differ by a factor 2.Comment: 14 page
Static quark anti-quark interactions in zero and finite temperature QCD. I. Heavy quark free energies, running coupling and quarkonium binding
We analyze heavy quark free energies in 2-flavor QCD at finite temperature
and the corresponding heavy quark potential at zero temperature. Static quark
anti-quark sources in color singlet, octet and color averaged channels are used
to probe thermal modifications of the medium. The temperature dependence of the
running coupling, , is analyzed at short and large distances
and is compared to zero temperature as well as quenched calculations. In parts
we also compare our results to recent findings in 3-flavor QCD. We find that
the characteristic length scale below which the running coupling shows almost
no temperature dependence is almost twice as large as the Debye screening
radius. Our analysis supports recent findings which suggest that and
are suppressed already at the (pseudo-) critical temperature and
thus give a probe for quark gluon plasma production in heavy ion collision
experiments, while may survive the transition and will dissolve at
higher temperatures.Comment: 16 pages, 15 encapsulated postscript figures, revtex
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