2,354 research outputs found
Elliptic flow due to radiation in heavy-ion collisions
In this paper we demonstrate that radiation patterns could cause flow-like
behaviour without any reference to hydrodynamic description. For that purpose
we use a statistical ensemble of radiating dipoles, motivated by the
investigation of the equivalent photon yield produced by decelerating charges.
For the elliptic asymmetry factor we find a reasonable agreement with
experimental data.Comment: 5 pages, 5 figures, v2: discussion on the physical interpretation of
the form factor F is adde
Nuclear and Quark Matter at High Temperature
We review important ideas on nuclear and quark matter description on the
basis of high- temperature field theory concepts, like resummation, dimensional
reduction, interaction scale separation and spectral function modification in
media. Statistical and thermodynamical concepts are spotted in the light of
these methods concentrating on the - partially still open - problems of the
hadronization process.Comment: Review intended for EPJ A Topical Issu
Critical exponents of the pair contact process with diffusion
We study the pair contact process with diffusion (PCPD) using Monte Carlo
simulations, and concentrate on the decay of the particle density with
time, near its critical point, which is assumed to follow . This model is known for its slow
convergence to the asymptotic critical behavior; we therefore pay particular
attention to finite-time corrections. We find that at the critical point, the
ratio of and the pair density converges to a constant,
indicating that both densities decay with the same powerlaw. We show that under
the assumption , two of the critical exponents of
the PCPD model are and , consistent with
those of the directed percolation (DP) model
A Four Country Comparision of Spite, Cooperation and Errors in Voluntary Contribution Mechanisms.
This paper presents data from experiments with a linear voluntary contributions mechanism for public goods conducted in Japan, the Netherlands, Spain and the USA. The same experimental design was used in the four countries.EXPERIMENTS ; VOLUNTARY SERVICES ; PUBLIC GOODS
SAWdoubler: a program for counting self-avoiding walks
This article presents SAWdoubler, a package for counting the total number
Z(N) of self-avoiding walks (SAWs) on a regular lattice by the length-doubling
method, of which the basic concept has been published previously by us. We
discuss an algorithm for the creation of all SAWs of length N, efficient
storage of these SAWs in a tree data structure, and an algorithm for the
computation of correction terms to the count Z(2N) for SAWs of double length,
removing all combinations of two intersecting single-length SAWs.
We present an efficient numbering of the lattice sites that enables
exploitation of symmetry and leads to a smaller tree data structure; this
numbering is by increasing Euclidean distance from the origin of the lattice.
Furthermore, we show how the computation can be parallelised by distributing
the iterations of the main loop of the algorithm over the cores of a multicore
architecture. Experimental results on the 3D cubic lattice demonstrate that
Z(28) can be computed on a dual-core PC in only 1 hour and 40 minutes, with a
speedup of 1.56 compared to the single-core computation and with a gain by
using symmetry of a factor of 26. We present results for memory use and show
how the computation is made to fit in 4 Gbyte RAM. It is easy to extend the
SAWdoubler software to other lattices; it is publicly available under the GNU
LGPL license.Comment: 29 pages, 3 figure
Social status and prosocial behavior
This paper studies the effects of social statusâa socially recognized ranking of individualsâon prosocial behavior. We use a laboratory experiment and propose a theory to address this issue. In a one-shot game, two players, whose social status is either earned or randomly assigned, jointly make effort contributions to a project. Player 1 first suggests an effort level for each player to player 2 who then determines the actual effort levels. Deviation from the proposal is costly. We find causal evidence that high-status players are less selfish than their low-status counterparts. In particular, high-status players 2 provide relatively more effort, ceteris paribus, than those with low status. The experimental results and theoretical framework suggest that a high social ranking yields more social behavior and that this can be attributed to the sense of responsibility that it gives.</p
Depression and Quality of Life in Patients with Diabetes: A Systematic Review from the European Depression in Diabetes (EDID) Research Consortium
Diabetes patients are known to have a worse quality of life than individuals without diabetes. They also have an increased risk for depressive symptoms, which may have an additional negative effect on their quality of life. This systematic review summarizes the current knowledge on the association between depressive symptoms and quality of life in individuals with diabetes. A systematic literature search using MEDLINE, Psychinfo, Social SciSearch, SciSearch and EMBASE was conducted from January 1990 until September 2007. We identified studies that compared quality of life between diabetic individuals with and without depressive symptoms. Twenty studies were identified, including eighteen cross-sectional and two longitudinal studies. Quality of life was measured as generic, diabetes specific and domain specific quality of life. All studies reported a negative association between depressive symptoms and at least one aspect of quality of life in people with diabetes. Diabetic individuals with depressive symptoms also had a severely lower diabetes specific quality of life. Generic and domain specific quality of life were found to be mild to moderately lower in the presence of depressive symptoms. Therefore, increased awareness and monitoring for depression is needed within different diabetes care settings
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