113,645 research outputs found
International Control of Civil Procedure: Who Benefits?
The work of the Hague Conference on Private International Law in the field of civil litigation is considered, focusing particularly on the Service Convention and the Evidence Convention. The international community has benefited from the work of the Hague Conference through cooperation under its auspices
Dynamical stability and evolution of the discs of Sc galaxies
We examine the local stability of galactic discs against axisymmetric density
perturbations with special attention to the different dynamics of the stellar
and gaseous components. In particular the discs of the Milky Way and of NGC
6946 are studied. The Milky Way is shown to be stable, whereas the inner parts
of NGC 6946, a typical Sc galaxy from the Kennicutt (1989) sample, are
dynamically unstable. The ensuing dynamical evolution of the composite disc is
studied by numerical simulations. The evolution is so fierce that the stellar
disc heats up dynamically on a short time scale to such a degree, which seems
to contradict the morphological appearance of the galaxy. The star formation
rate required to cool the disc dynamically is estimated. Even if the star
formation rate in NGC 6946 is at present high enough to meet this requirement,
it is argued that the discs of Sc galaxies cannot sustain such a high star
formation rate for longer periods.Comment: Latex, 11 pages, 8 figures, fig.7 available at anonymous ftp server
ftp.lsw.uni-heidelberg.de under incoming/svlinden/fig7.ps, to appear in MNRA
Multiloop functional renormalization group for general models
We present multiloop flow equations in the functional renormalization group
(fRG) framework for the four-point vertex and self-energy, formulated for a
general fermionic many-body problem. This generalizes the previously introduced
vertex flow [F. B. Kugler and J. von Delft, Phys. Rev. Lett. 120, 057403
(2018)] and provides the necessary corrections to the self-energy flow in order
to complete the derivative of all diagrams involved in the truncated fRG flow.
Due to its iterative one-loop structure, the multiloop flow is well-suited for
numerical algorithms, enabling improvement of many fRG computations. We
demonstrate its equivalence to a solution of the (first-order) parquet
equations in conjunction with the Schwinger-Dyson equation for the self-energy
Multiloop functional renormalization group that sums up all parquet diagrams
We present a multiloop flow equation for the four-point vertex in the
functional renormalization group (fRG) framework. The multiloop flow consists
of successive one-loop calculations and sums up all parquet diagrams to
arbitrary order. This provides substantial improvement of fRG computations for
the four-point vertex and, consequently, the self-energy. Using the X-ray-edge
singularity as an example, we show that solving the multiloop fRG flow is
equivalent to solving the (first-order) parquet equations and illustrate this
with numerical results
Legitimacy in conflict: concepts, practices, challenges
The study of legitimacy in situations of conflict and peacebuilding has increased in recent years. However, current work on the topic adopts many assumptions, definitions, and understandings from classical legitimacy theory, which centers on the relationship between the nation-state and its citizens. In this introduction, we provide a detailed critical overview of current theories of legitimacy and legitimation and demonstrate why they have only limited applicability in conflict and post-conflict contexts, focusing on the three main areas that the articles included in this special issue examine: audiences for legitimacy, sources of legitimacy, and legitimation. In particular, we show how conflict and post-conflict contexts are marked by the fragmentation and personalization of power; the proliferation and fragmentation of legitimacy audiences; and ambiguity surrounding legitimation strategies
Low-Temperature Expansions and Correlation Functions of the Z_3-Chiral Potts Model
Using perturbative methods we derive new results for the spectrum and
correlation functions of the general Z_3-chiral Potts quantum chain in the
massive low-temperature phase. Explicit calculations of the ground state energy
and the first excitations in the zero momentum sector give excellent
approximations and confirm the general statement that the spectrum in the
low-temperature phase of general Z_n-spin quantum chains is identical to one in
the high-temperature phase where the role of charge and boundary conditions are
interchanged. Using a perturbative expansion of the ground state for the Z_3
model we are able to gain some insight in correlation functions. We argue that
they might be oscillating and give estimates for the oscillation length as well
as the correlation length.Comment: 17 pages (Plain TeX), BONN-HE-93-1
Stable single-photon interference in a 1 km fiber-optical Mach-Zehnder interferometer with continuous phase adjustment
We experimentally demonstrate stable and user-adjustable single-photon
interference in a 1 km long fiber- optical Mach-Zehnder interferometer, using
an active phase control system with the feedback provided by a classical laser.
We are able to continuously tune the single-photon phase difference between the
interferometer arms using a phase modulator, which is synchronized with the
gate window of the single-photon detectors. The phase control system employs a
piezoelectric fiber stretcher to stabilize the phase drift in the
interferometer. A single-photon net visibility of 0.97 is obtained, yielding
future possibilities for experimental realizations of quantum repeaters in
optical fibers, and violation of Bell's inequalities using genuine energy-time
entanglementComment: 3 pages, 3 figure
Revisiting random deposition with surface relaxation: approaches from growth rules to Edwards-Wilkinson equation
We present several approaches for deriving the coarse-grained continuous
Langevin equation (or Edwards-Wilkinson equation) from a random deposition with
surface relaxation (RDSR) model. First we introduce a novel procedure to divide
the first transition moment into the three fundamental processes involved:
deposition, diffusion and volume conservation. We show how the diffusion
process is related to antisymmetric contribution and the volume conservation
process is related to symmetric contribution, which renormalizes to zero in the
coarse-grained limit. In another approach, we find the coefficients of the
continuous Langevin equation, by regularizing the discrete Langevin equation.
Finally, in a third approach, we derive these coefficients from the set of test
functions supported by the stationary probability density function (SPDF) of
the discrete model. The applicability of the used approaches to other discrete
random deposition models with instantaneous relaxation to a neighboring site is
discussed.Comment: 12 pages, 4 figure
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