Internet network externalities

Abstract: A driving force behind the emergence of the ‘new’ or information economy is the growth of the internet network capacity. A fundamental problem in mapping this dynamic is the lack of an acceptable theoretical framework through which to direct empirical investigations. Most of the models in the literature on network externalities have been developed in a static framework, with the externalities viewed as instantaneous or self-fulfilling. The model specified here builds on the received theory from several sources to extend these features and develops a dynamic model that is both capable of econometric estimation and which provides as an output a direct measure of the network effect. Accordingly, the main goal of this paper is to find the magnitude of the external effect on internet network growth. In addition, this paper illustrates the ability of the panel data to generate estimates of structural parameters capable of explaining internet host growth.Information; network externalities; internet; growth

Estimating components of ICT expenditure: a model-based approach with applicability to short time-series

This paper develops a microeconomic model-based approach to forecast national information and communications technology expenditure that is helpful when only very short time-series are available. The model specification incorporates parameters for network effects and national e-readiness. Finally, the model allows for observed non-homotheticity and ‘noise’ found in sample data, with the latter attributed to country-specific influences.ICT forecasts; short time-series; microeconomic modeling

Determination of the zeta potential for highly charged colloidal suspensions

We compute the electrostatic potential at the surface, or zeta potential $\zeta$, of a charged particle embedded in a colloidal suspension using a hybrid mesoscopic model. We show that for weakly perturbing electric fields, the value of $\zeta$ obtained at steady state during electrophoresis is statistically indistinguishable from $\zeta$ in thermodynamic equilibrium. We quantify the effect of counterions concentration on $\zeta$. We also evaluate the relevance of the lattice resolution for the calculation of $\zeta$ and discuss how to identify the effective electrostatic radius.Comment: 8 pages, 3 figures with 2 panel

A Study of the Educational and Occupational Information Services of the Member Schools of the Accrediting Association of Bible Colleges

The world scene has changed greatly in the last few years. Because of changes in the occupational field, the educational field and others, the need for guidance services has increased. Never before have there been so many occupational choices available and never before have they demanded so much education for entry into the occupation. the member schools of the Accrediting Association of the Bible Colleges have also felt these changes and have reacted not only in the courses of study offered but also in increased efforts in the field of guidance and counseling

Direct numerical simulations for non-Newtonian rheology of concentrated particle dispersions

The non-Newtonian behavior of a monodisperse concentrated dispersion of spherical particles was investigated using a direct numerical simulation method, that takes into account hydrodynamic interactions and thermal fluctuations accurately. Simulations were performed under steady shear flow with periodic boundary conditions in the three directions. The apparent shear viscosity of the dispersions was calculated at volume fractions ranging from 0.31 to 0.56. Shear-thinning behavior was clearly observed at high volume fractions. The low- and high-limiting viscosities were then estimated from the apparent viscosity by fitting these data into a semi-empirical formula. Furthermore, the short-time motions were examined for Brownian particles fluctuating in concentrated dispersions, for which the fluid inertia plays an important role. The mean square displacement was monitored in the vorticity direction at several different Peclet numbers and volume fractions so that the particle diffusion coefficient is determined from the long-time behavior of the mean square displacement. Finally, the relationship between the non-Newtonian viscosity of the dispersions and the structural relaxation of the dispersed Brownian particles is examined

Influence of shear stress applied during flow stoppage and rest period on the mechanical properties of thixotropic suspensions

We study the solid mechanical properties of several thixotropic suspensions as a function of the shear stress history applied during their flow stoppage and their aging in their solid state. We show that their elastic modulus and yield stress depend strongly on the shear stress applied during their solid-liquid transition (i.e., during flow stoppage) while applying the same stress only before or only after this transition may induce only second-order effects: there is negligible dependence of the mechanical properties on the preshear history and on the shear stress applied at rest. We also found that the suspensions age with a structuration rate that hardly depends on the stress history. We propose a physical sketch based on the freezing of a microstructure whose anisotropy depends on the stress applied during the liquid-solid transition to explain why the mechanical properties depend strongly on this stress. This sketch points out the role of the internal forces in the colloidal suspensions' behavior. We finally discuss briefly the macroscopic consequences of this phenomenon and show the importance of using a controlled-stress rheometer

Local structure of percolating gels at very low volume fractions

The formation of colloidal gels is strongly dependent on the volume fraction of the system and the strength of the interactions between the colloids. Here we explore very dilute solutions by the means of numerical simulations, and show that, in the absence of hydrodynamic interactions and for sufficiently strong interactions, percolating colloidal gels can be realised at very low values of the volume fraction. Characterising the structure of the network of the arrested material we find that, when reducing the volume fraction, the gels are dominated by low-energy local structures, analogous to the isolated clusters of the interaction potential. Changing the strength of the interaction allows us to tune the compactness of the gel as characterised by the fractal dimension, with low interaction strength favouring more chain-like structures

Remote sensing applications in forestry. The development of an earth resources information system using aerial photographs and digital computers photographs and digital computers

Remote aerial sensing and automatic mapping for forest resources information syste