21 research outputs found
Particle Creation Amplification in Curved Space due to Thermal Effects
A physical system composed by a scalar field minimally coupled to gravity and
a thermal reservoir, as in thermo field dynamics, all of them in curved space
time, is considered. When the formalism of thermo field dynamics is generalized
to the above mentioned case, an amplification in the number of created
particles is predicted.Comment: 7 pages; Plain Te
Thermal and Dynamical Particle Creation in a Curved Geometry
A generalization of ``Termo Field Dynamics'' to a curved geometry is
proposed. In particular a neutral scalar field minimally coupled to gravity is
considered as matter content in a Robertson-Walker metric. A non linear
amplification in the particle creation is obtained, due to the altogether
action of thermal and geometric effects. As a consequence the frequencies in
the system look like red shifted with respect to the case where the thermal
creation is not taken into account.Comment: 13 page
Exploring associations between micro-level models of innovation diffusion and emerging macro-level adoption patterns
A micro-level agent-based model of innovation diffusion was developed that
explicitly combines (a) an individual's perception of the advantages or
relative utility derived from adoption, and (b) social influence from members
of the individual's social network. The micro-model was used to simulate
macro-level diffusion patterns emerging from different configurations of
micro-model parameters. Micro-level simulation results matched very closely the
adoption patterns predicted by the widely-used Bass macro-level model (Bass,
1969). For a portion of the domain, results from micro-simulations were
consistent with aggregate-level adoption patterns reported in the literature.
Induced Bass macro-level parameters and responded to changes in
micro-parameters: (1) increased with the number of innovators and with the rate
at which innovators are introduced; (2) increased with the probability of
rewiring in small-world networks, as the characteristic path length decreases;
and (3) an increase in the overall perceived utility of an innovation caused a
corresponding increase in induced and values. Understanding micro to macro
linkages can inform the design and assessment of marketing interventions on
micro-variables - or processes related to them - to enhance adoption of future
products or technologies.Comment: 20 pages, 4 figures and a table of supplementary data. Accepted for
publicatio
Thermal Conditions for Scalar Bosons in a Curved Space Time
The conditions that allow us to consider the vacuum expectation value of the
energy-momentum tensor as a statistical average, at some particular
temperature, are given. When the mean value of created particles is stationary,
a planckian distribution for the field modes is obtained. In the massless
approximation, the temperature dependence is as that corresponding to a
radiation dominated Friedmann-like model.Comment: 14 pages (TeX manuscript
Ising-like agent-based technology diffusion model: adoption patterns vs. seeding strategies
The well-known Ising model used in statistical physics was adapted to a
social dynamics context to simulate the adoption of a technological innovation.
The model explicitly combines (a) an individual's perception of the advantages
of an innovation and (b) social influence from members of the decision-maker's
social network. The micro-level adoption dynamics are embedded into an
agent-based model that allows exploration of macro-level patterns of technology
diffusion throughout systems with different configurations (number and
distributions of early adopters, social network topologies). In the present
work we carry out many numerical simulations. We find that when the gap between
the individual's perception of the options is high, the adoption speed
increases if the dispersion of early adopters grows. Another test was based on
changing the network topology by means of stochastic connections to a common
opinion reference (hub), which resulted in an increment in the adoption speed.
Finally, we performed a simulation of competition between options for both
regular and small world networks.Comment: 23 pages and 5 figure