698 research outputs found
Evolution of Cooperative Networks and the Emergence of Leadership
A generic property of biological, social and economical networks is their ability to evolve in time, creating or supressing links. We model this situation with an adaptive network of agents playing a Prisoner's Dilemma game. Each agent plays with its local neighbors, collects an aggregate payoff and imitates the strategy of its best neighbor. Furthermore we allow the agents adapt their local neighborhood according to their satisfaction level and the strategy played. Therefore each agent will have diverse environments that induces an interesting dynamics in the cooperation fraction of the whole network. In the absence of noise, a steady state is always reached, where the strategies and the neighborhoods remain stationary, and where for a wide range of parameter values, an almost full cooperative outcome is obtained. The topology of the network in these states reveals that cooperators with a large number of connections emerges. These "leaders" are shown to be very important in understanding the global stability of the final steady state. If the "leaders" are perturbated, then global cascades arise and the system oscillates between the nearly full defection network and the fully cooperative outcome, before settling again in a nearly fully cooperative outcome.Cooperation -- Evolutionary Game Theory -- Stochastic Networks -- Prisoner Dilemma
Creating green consumer loyalty; How to strategically market CSR and obtain consumer preference
Sustainability is an important social theme that is taking on increasing significance in many areas, including the supermarket sector. This report presents the findings of a literature study looking at the opportunities available to supermarkets to gain a preferential position in the eyes of consumers for their efforts regarding sustainability. Duurzaamheid is een belangrijk maatschappelijk thema, dat ook in de supermarktbranche van steeds grotere betekenis wordt. Dit rapport presenteert de bevindingen van een literatuurstudie naar de aangrijpingspunten die supermarkten hebben om voor hun duurzaamheidsinspanningen een voorkeurspositie bij de consument te verkrijgen
Een band met de duurzame klant : de rol van duurzaamheidsinspanningen van bedrijven bij het bereiken van de consument
Duurzaamheid is een belangrijk maatschappelijk thema, dat ook in de supermarktbranche van steeds grotere betekenis wordt. Dit rapport presenteert de bevindingen van een literatuurstudie naar de aangrijpingspunten die supermarkten hebben om voor hun duurzaamheidsinspanningen een voorkeurspositie bij de consument te verkrijgen. Sustainability is an important social theme that is taking on increasing significance in many areas, including the supermarket sector. This report presents the findings of a literature study looking at the opportunities available to supermarkets to gain a preferential position in the eyes of consumers for their effortsregarding sustainability
Cold atoms in a high-Q ring-cavity
We report the confinement of large clouds of ultra-cold 85-Rb atoms in a
standing-wave dipole trap formed by the two counter-propagating modes of a
high-Q ring-cavity. Studying the properties of this trap we demonstrate loading
of higher-order transverse cavity modes and excite recoil-induced resonances.Comment: 4 pages, 4 figure
Intrinsic noise-induced phase transitions: beyond the noise interpretation
We discuss intrinsic noise effects in stochastic multiplicative-noise partial
differential equations, which are qualitatively independent of the noise
interpretation (Ito vs. Stratonovich), in particular in the context of
noise-induced ordering phase transitions. We study a model which, contrary to
all cases known so far, exhibits such ordering transitions when the noise is
interpreted not only according to Stratonovich, but also to Ito. The main
feature of this model is the absence of a linear instability at the transition
point. The dynamical properties of the resulting noise-induced growth processes
are studied and compared in the two interpretations and with a reference
Ginzburg-Landau type model. A detailed discussion of new numerical algorithms
used in both interpretations is also presented.Comment: 9 pages, 8 figures, to be published in Phys. Rev.
A macroscopic multifractal analysis of parabolic stochastic PDEs
It is generally argued that the solution to a stochastic PDE with
multiplicative noise---such as , where denotes
space-time white noise---routinely produces exceptionally-large peaks that are
"macroscopically multifractal." See, for example, Gibbon and Doering (2005),
Gibbon and Titi (2005), and Zimmermann et al (2000). A few years ago, we proved
that the spatial peaks of the solution to the mentioned stochastic PDE indeed
form a random multifractal in the macroscopic sense of Barlow and Taylor (1989;
1992). The main result of the present paper is a proof of a rigorous
formulation of the assertion that the spatio-temporal peaks of the solution
form infinitely-many different multifractals on infinitely-many different
scales, which we sometimes refer to as "stretch factors." A simpler, though
still complex, such structure is shown to also exist for the
constant-coefficient version of the said stochastic PDE.Comment: 41 page
Nonequilibrium wetting transitions with short range forces
We analyze within mean-field theory as well as numerically a KPZ equation
that describes nonequilibrium wetting. Both complete and critical wettitng
transitions were found and characterized in detail. For one-dimensional
substrates the critical wetting temperature is depressed by fluctuations. In
addition, we have investigated a region in the space of parameters (temperature
and chemical potential) where the wet and nonwet phases coexist. Finite-size
scaling analysis of the interfacial detaching times indicates that the finite
coexistence region survives in the thermodynamic limit. Within this region we
have observed (stable or very long-lived) structures related to spatio-temporal
intermittency in other systems. In the interfacial representation these
structures exhibit perfect triangular (pyramidal) patterns in one (two
dimensions), that are characterized by their slope and size distribution.Comment: 11 pages, 5 figures. To appear in Physical Review
Critical exponents of directed percolation measured in spatiotemporal intermittency
A new experimental system showing a transition to spatiotemporal
intermittency is presented. It consists of a ring of hundred oscillating
ferrofluidic spikes. Four of five of the measured critical exponents of the
system agree with those obtained from a theoretical model of directed
percolation.Comment: 7 pages, 12 figures, submitted to PR
Coevolution of Glauber-like Ising dynamics on typical networks
We consider coevolution of site status and link structures from two different
initial networks: a one dimensional Ising chain and a scale free network. The
dynamics is governed by a preassigned stability parameter , and a rewiring
factor , that determines whether the Ising spin at the chosen site flips
or whether the node gets rewired to another node in the system. This dynamics
has also been studied with Ising spins distributed randomly among nodes which
lie on a network with preferential attachment. We have observed the steady
state average stability and magnetisation for both kinds of systems to have an
idea about the effect of initial network topology. Although the average
stability shows almost similar behaviour, the magnetisation depends on the
initial condition we start from. Apart from the local dynamics, the global
effect on the dynamics has also been studied. These parameters show interesting
variations for different values of and , which helps in determining
the steady-state condition for a given substrate.Comment: 8 pages, 10 figure
Experimental evidence of two-band behavior of MgB2
The break-junction tunneling has been systematically investigated in MgB2.
Two types of the break-junction contacts have been exploited on the same
samples, which demonstrated tunnel contact like (SIS) and point contact like
(SnS) behavior. Both of them have shown the existence of the two distinct
energy gaps. We have observed also the peculiarities on the I(V)-
characteristics related to Leggett's collective mode assisted tunneling. -->
Corresponding author address: [email protected]: 14 pages, 6 figures, 1 table; corrected typos and fig
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