783 research outputs found
Introduction to the Journal of Economic Dynamics and Control special issue on Bounded Rationality, Heterogeneity and Market Dynamics
Herding model and 1/f noise
We provide evidence that for some values of the parameters a simple agent
based model, describing herding behavior, yields signals with 1/f power
spectral density. We derive a non-linear stochastic differential equation for
the ratio of number of agents and show, that it has the form proposed earlier
for modeling of 1/f^beta noise with different exponents beta. The non-linear
terms in the transition probabilities, quantifying the herding behavior, are
crucial to the appearance of 1/f noise. Thus, the herding dynamics can be seen
as a microscopic explanation of the proposed non-linear stochastic differential
equations generating signals with 1/f^beta spectrum. We also consider the
possible feedback of macroscopic state on microscopic transition probabilities
strengthening the non-linearity of equations and providing more opportunities
in the modeling of processes exhibiting power-law statistics
Origin of the fast magnetization tunneling in the single-molecule magnet [Ni(hmp)(tBuEtOH)Cl]4
We present high-frequency angle-dependent EPR data for crystals of
[NixZn1-x(hmp)(t-BuEtOH)Cl]4 (x = 1 and 0.02). The x = 1 complex behaves as a
single-molecule magnet at low temperatures, displaying hysteresis and
exceptionally fast magnetization tunneling. We show that this behavior is
related to a 4th-order transverse crystal-field interaction, which produces a
significant tunnel-splitting (~10 MHz) of the ground state of this S = 4
system. The magnitude of the 4th-order anisotropy, and the dominant axial term
(D), can be related to the single-ion interactions (Di and Ei) at the
individual NiII sites, as determined for the x = 0.02 crystals.Comment: 11 pages including 2 figure
Behavioral interviewing as part of values based recruitment for community nursing programmes
The widespread implementation of values based recruitment (VBR) has been indicated as a priority in both health settings and the recruitment of students within Higher Education Institutes (HEIâs). This opportunity prompts organisations to evaluate recruitment processes, and essentially the values, behaviours and attitudes of applicants. VBR begins at the point of advertisement, but for the purpose of this paper, the selection process will be the focus. There is an expectation that organisations will move away from âconventionalâ interview panel questions which explore hypothesised responses to a scenario (situational interviewing), in favour of behavioural interviewing. This paper explores the process of behavioural interviewing as part of VBR for post graduate community nurse programmes within a University. The University has implemented a three staged approach to selection including an unseen presentation, a group work exercise and an interview panel (behavioural interview techniques), for each candidate successfully shortlisted. This paper shares the practice of the selection process of candidates in a bid to understand the outcomes of VBR
Exploring Twitter as a game platform; strategies and opportunities for microblogging-based games
Recent years have seen the massive daily engagement of players with games that are integrated with online social networking sites, such as Facebook. However, few games have successfully created engaging experiences through integration with microblogging websites. In this paper, we explore the opportunities and challenges in using Twitter as a platform for playing games, through the case study of the game Hashtag Dungeon, a dungeon-crawling game that uses Twitter for collaborative creation of game content. Two studies were carried out. A quantitative user study with 32 participants demonstrated that players found the game engaging and rewarding. A follow-up qualitative study with 8 participants suggests that Twitter integration in this game is meaningful, but that there are concerns over the impact of the game on playersâ Twitter profiles. Based on findings from both studies, we propose strategies for the design of Microblogging-based games, and discuss wider implications of social media integration in games
How fair is an equitable distribution?
Envy is a rather complex and irrational emotion. In general, it is very
difficult to obtain a measure of this feeling, but in an economical context
envy becomes an observable which can be measured. When various individuals
compare their possessions, envy arises due to the inequality of their different
allocations of commodities and different preferences. In this paper we show
that an equitable distribution of goods does not guarantee a state of fairness
between agents and in general that envy cannot be controlled by tuning the
distribution of goods.Comment: 16 pages, 8 figures, LaTEX; typos added; minor changes in plots; two
new plots added; references added; minor changes in the acknowledgment
Theory of collective opinion shifts: from smooth trends to abrupt swings
We unveil collective effects induced by imitation and social pressure by
analyzing data from three different sources: birth rates, sales of cell phones
and the drop of applause in concert halls. We interpret our results within the
framework of the Random Field Ising Model, which is a threshold model for
collective decisions accounting both for agent heterogeneity and social
imitation. Changes of opinion can occur either abruptly or continuously,
depending on the importance of herding effects. The main prediction of the
model is a scaling relation between the height h of the speed of variation peak
and its width of the form h ~ w^{-kappa}, with kappa = 2/3 for well
connected populations. Our three sets of data are compatible with such a
prediction, with kappa ~ 0.62 for birth rates, kappa ~ 0.71 for cell phones and
kappa ~ 0.64 for clapping. In this last case, we in fact observe that some
clapping samples end discontinuously (w=0), as predicted by the model for
strong enough imitation.Comment: 11 pages, 8 figure
A complex systems approach to constructing better models for managing financial markets and the economy
We outline a vision for an ambitious program to understand the economy and financial markets as a complex evolving system of coupled networks of interacting agents. This is a completely different vision from that currently used in most economic models. This view implies new challenges and opportunities for policy and managing economic crises. The dynamics of such models inherently involve sudden and sometimes dramatic changes of state. Further, the tools and approaches we use emphasize the analysis of crises rather than of calm periods. In this they respond directly to the calls of Governors Bernanke and Trichet for new approaches to macroeconomic modelling. Graphical abstrac
Formation of Common Investment Networks by Project Establishment between Agents
We present an investment model integrated with trust-reputation mechanisms
where agents interact with each other to establish investment projects. We
investigate the establishment of investment projects, the influence of the
interaction between agents in the evolution of the distribution of wealth, as
well as the formation of common investment networks and some of their
properties. Simulation results show that the wealth distribution presents a
power law in its tail. Also, it is shown that the trust and reputation
mechanism presented leads to the establishment of networks among agents, which
present some of the typical characteristics of real-life networks like a high
clustering coefficient and short average path length
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