Carlos E. Laciana

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 [1]). For a portion of the p−q domain, results from micro-simulations were consistent with aggregate-level adoption patterns reported in the literature. Induced Bass macro-level parameters p and q responded to changes in micro-parameters: (1) p increased with the number of innovators and with the rate at which innovators are introduced; (2) q 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 p and q 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.

An agent based multi-optional model for the diffusion of innovations

We propose a model for the diffusion of several products competing in a common market based on the generalization of the Ising model of statistical mechanics (Potts model). Using an agent based implementation we analyze two problems: (i) a three options case, i.e. to adopt a product A, a product B, or non-adoption and (ii) a four option case, i.e. the adoption of product A, product B, both, or none. In the first case we analyze a launching strategy for one of the two products, which delays its launching with the objective of competing with improvements. Market shares reached by each product are then estimated at market saturation. Finally, simulations are carried out with varying degrees of social network topology, uncertainty, and population homogeneity.

An Integrated Hydrodynamic-Sedimentologic-Morphologic Model for the Evolution of Alluvial Channels Cross-Sections

Abstract A practical implementation of an integrated hydrodynamic-sedimentologic-morphologic model for the evolution of the cross section of an alluvial channel is presented. It is shown that the driving hydrodynamics can be solved through a series of concatenated 1D hydrodynamic models, which reduces the mathematical complexity to its minimum. A mechanistic model for bed load transport is presented, which can be used readily by practitioners. As part of the morphologic model, a sliding algorithm is proposed to limit the lateral slope which, in particular, efficiently deals with non-cohesive bank erosion. The obtained integrated model is validated by comparing its results with experimental data and previous calculations for evolving channel cross sections. The comparison shows good agreement between these data and the numerical results. To illustrate the model capabilities, numerical experiments are performed on open channels with different radii of curvature to attain stabilized cross-section forms.

Diffusion of two brands in competition: Cross-brand effect

We study the equilibrium points of a system of equations corresponding to a Bass based model that describes the diffusion of two brands in competition. To increase the understanding of the effects of the cross-brand parameters, we perform a sensitivity analysis. Finally, we show a comparison with an agent-based model inspired in the Potts model. Conclusions include that both models give the same diffusion curves only when the cross coefficients are not null.

Agricultural Decision Making in the Argentine Pampas: Modeling the Interaction between Uncertain and Complex Environments and Heterogeneous and Complex Decision Makers

1 Rosenstiel School of Marine and Atmospheric Science, University of Miami, USA gpodesta@rsmas.miami.edu, dletson@rsmas.miami.edu 2 Columbia University, Department of Psychology and Graduate School of Business, and Center for Research on Environmental Decisions (CRED), USA euw2@columbia.edu 3 Facultad de Ingenieŕia, University of Buenos Aires, Argentina clacian@fi.uba.ar 4 Facultad de Agronomia, University of Buenos Aires, Argentina fbert@mail.agro.uba.ar

Can gravity be a thermal reservoir

It is shown, in an isotropic universe, that the quantum conformal fluctuations of the metric can play a role analogous to the fictitious field of Thermo Field Dynamics (TFD) of Takahashi and Umezawa, when a massless scalar field minimaly coupled to gravity is regarded as matter content. Moreover, by means of an extremum condition on the entropy and the energy, a planckian-like spectrum for the created particles is obtained.

Quantum field theory in curved space-time as thermo field dynamics

The strong analogy between states defined in the context of quantum field theory in curved space-time (QFT-CST) and the ones defined in the thermo field dynamics (TFD) of Takahashi and Umezawa [1] is shown. This analogy is useful in order to introduce the entropy operator in CST in the same way as in TFD. When the extremum condition in the thermodynamical potential is imposed, a family of Bogoliubov transformations that give us a planckian spectrum is found, even in “pathological” cases such as the minimally coupled scalar field.

A causal viscous cosmology without singularities

An isotropic and homogeneous cosmological model with a source of dark energy is studied. That source is simulated with a viscous relativistic fluid with minimal causal correction. In this model the restrictions on the parameters coming from the following conditions are analized: (a) energy density without singularities along time, (b) scale factor increasing with time, (c) universe accelerated at present time, (d) state equation for dark energy with “w” bounded and close to −1. It is found that those conditions are satisfied for the following two cases. (i) When the transport coefficient (

Thermal conditions for scalar bosons in a curved spacetime

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