Dynamics of Sub-urbanisation - The Growing Periphery of the Metropolis. Berlin 1890 - 2000

What controls the secular process of sub-urbanisation of Berlin to garden and satellite cities and what were the effects? Through the massive retreat of its wealthy and academic bourgeoisie from the centre, Berlin became a bipolar city. On this side of the "railway ring", stood the "stony Berlin" of tenement blocks, the "largest mietskasernen city in the world"(Julius Posener). On the other side the "largest villa city in the world" was growing. The concept of the "green" city had some positive influence and brought a long-term "moral mission" of the upper middle classes into the inner-city. The pre-war villa settlements were an effective laboratory for the middle class dream of owning a house and a garden on the green and healthy outskirts of the city. In the competition between the political systems after the War, the GDR ran with an inner-city housing development, which unlike the prevailing "spacious green city" idea in West Berlin, had to remain true to the old city structure. Recently some urban planners and sociologists, looking at suburbia in a positive sense, using concepts like 'net city' or 'edge city', have accentuated the autonomy of suburbia. Whether this suburban mix contains the future of city development, remains to be seen

Introduction

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.With this volume, the European Association of Urban Historians (EAUH) introduces itself for the first time to American readers and includes some of the results of its Fifth International Conference, which took place in August/ September 2000 in Berlin. The EAUH was founded in 1989 by English, Dutch, Belgian, and French historians. The focus of its activities is the International Conference on Urban History. It takes place every two years in a significant European city. After Amsterdam 1992, Strasbourg, Budapest, Venice, and Berlin each hosted the conference consecutively. It has become one of the biggest and most important forums for international academic exchange in the field of historic urban research

Extraction of shear viscosity in stationary states of relativistic particle systems

Starting from a classical picture of shear viscosity we construct a stationary velocity gradient in a microscopic parton cascade. Employing the Navier-Stokes ansatz we extract the shear viscosity coefficient $\eta$. For elastic isotropic scatterings we find an excellent agreement with the analytic values. This confirms the applicability of this method. Furthermore for both elastic and inelastic scatterings with pQCD based cross sections we extract the shear viscosity coefficient $\eta$ for a pure gluonic system and find a good agreement with already published calculations.Comment: 17 pages, 7 figure

Quantum fields in disequilibrium: neutral scalar bosons with long-range, inhomogeneous perturbations

Using Schwinger's quantum action principle, dispersion relations are obtained for neutral scalar mesons interacting with bi-local sources. These relations are used as the basis of a method for representing the effect of interactions in the Gaussian approximation to field theory, and it is argued that a marked inhomogeneity, in space-time dependence of the sources, forces a discrete spectrum on the field. The development of such a system is characterized by features commonly associated with chaos and self-organization (localization by domain or cell formation). The Green functions play the role of an iterative map in phase space. Stable systems reside at the fixed points of the map. The present work can be applied to self-interacting theories by choosing suitable properties for the sources. Rapid transport leads to a second order phase transition and anomalous dispersion. Finally, it is shown that there is a compact representation of the non-equilibrium dynamics in terms of generalized chemical potentials, or equivalently as a pseudo-gauge theory, with an imaginary charge. This analogy shows, more clearly, how dissipation and entropy production are related to the source picture and transform a flip-flop like behaviour between two reservoirs into the Landau problem in a constant `magnetic field'. A summary of conventions and formalism is provided as a basis for future work.Comment: 23 pages revte

Elastic Scattering and Transport Coefficients for a Quark Plasma in SUf(3)SU_f(3) at Finite Temperatures

The temperature dependence of the elastic scattering processes $qq'\to qq'$ and $q\bar q'\to q\bar q'$, with $q, q' = u, d, s$ is studied as a function of the scattering angle and the center of mass energy of the collision within the framework of the $SU_f(3)$ Nambu--Jona--Lasinio model. Critical scattering at threshold is observed in the $q\bar q'\to q\bar q'$ process, leading to an enhancement of the cross section as occurs in the phenomenon of critical opalescence. Transport properties such as viscosity, mean free paths and thermal relaxation times are calculated. Strangeness enhancement is investigated via the chemical relaxation times, which are found to be considerably higher than those calculated via perturbative QCD. A comparison with the experimental values for the strangeness enhancement in $S+S$ collisions leads to an upper limit of 4~fm/$c$ for the lifetime of the plasma.Comment: 35 pages ReVTeX, 18 PostScript figures, uufiles format, to appear in Nucl. Phys.

Large transient states in quantum field theory

A study is made of the scattering of two large composite projectiles, such as heavy ions, which are initially prepared in a pure quantum state. It is shown that the quantum field theoretic evolution equation for this system, under certain conditions, goes over in form to the master equation of classical statistical mechanics. Thus, the statistical mechanical description of heavy ion collision is viewed as an implied outcome of the Correspondence Principle, which states that in the limit of large quantum number, quantum dynamics goes over to classical dynamics. This hypothesis is explored within the master equation transcription with particular focus on the quark-gluon formation scenario.Comment: 28 pages, In Press Nuclear Physics A 200

Sound waves and solitons in hot and dense nuclear matter

Assuming that nuclear matter can be treated as a perfect fluid, we study the propagation of perturbations in the baryon density. The equation of state is derived from a relativistic mean field model, which is a variant of the non-linear Walecka model. The expansion of the Euler and continuity equations of relativistic hydrodynamics around equilibrium configurations leads to differential equations for the density fluctuations. We solve them numerically for linear and spherical perturbations and follow the time evolution of the initial pulses. For linear perturbations we find single soliton solutions and solutions with one or more solitons followed by radiation. Depending on the equation of state a strong damping may occur. Spherical perturbations are strongly damped and almost do not propagate. We study these equations also for matter at finite temperature. Finally we consider the limiting case of shock wave formation.Comment: 28 pages, 8 figure

Parton Interaction Rates in the Quark-Gluon Plasma

The transport interaction rates of elastic scattering processes of thermal partons in the quark-gluon plasma are calculated beyond the leading logarithm approximation using the effective perturbation theory for QCD at finite temperatures developed by Braaten and Pisarski. The results for the ordinary and transport interaction rates obtained from the effective perturbation theory are compared to perturbative approximations based on an infrared cut-off by the Debye screening mass. The relevance of those interaction rates for a quark-gluon plasma possibly formed in ultrarelativistic heavy ion collisions are discussed.Comment: 11 pages, 2 figures (not included), REVTex, UGI-93-0