A firm-level analysis of ICT adoption in an emerging economy: evidence from the colombian manufacturing industries

This study examines ICT adoption among 3,759 Colombian manufacturing firms, and attemptsto identify the factors that are conducive to the adoption and usage of ICT at the firm level. Ourmajor findings are (i) that the adoption of a given information and communication technology isbetter facilitated when a firm is relatively large, has large human capital, engages in moreinnovative activities, and when a firm´s organizational structure is better aligned with the giventechnology; (ii) that positive associations between the key determinants and ICT adoptions aremore pronounced for small and medium-sized firms than for large ones, and (iii) that informationspillovers within industries is also a determinant of ICT adoptions by the firms.ICT adoption, Internet, Innovation, Organizational change

Telecommunications and economic growth: an empirical analysis of sub-saharan Africa

We examine the effect on economic growth of mobile cellular phones in sub-Saharan Africa where a marked asymmetry is present between land-line penetration and mobile telecommunications expansion. This study extends previous ones along two important dimensions. First, we allow for the potential endogeneity between economic growth and telecommunications expansion by employing a special linear generalized method of moments (GMM) estimator. Second, we explicitly model for varying degrees of substitutability between mobile cellular and land-line telephony, so that greater expansion of mobile telecommunications can have a different impact whenever the level of land-line penetration differs. We find that mobile cellular phone expansion is an important determinant of the rate of economic growth in Sub-Saharan Africa. Moreover, we find that the contribution of mobile cellular phones to economic growth has been growing in importance in the region, and that the marginal impact of mobile telecommunication services is even greater wherever land-line phones are rare. Given the low cost of mobile telecommunications technology relative to other broad infrastructure projects, especially land-line infrastructure, we advocate that mobile telecommunication services be encouraged in the area.

Investigation of the Effects of Target Feature Variations on Ballistic Missile RCS

Uncertainties about certain features of target geometries can result in a loss of confidence in target signature assessment. This thesis describes the development of a general rule-of-thumb to determine how the radar signature of a target varies as a function of the target\u27s specific features. The targets of interest in this study are fictitious ballistic missiles. Four target features of these missiles are investigated: fin size, nose cone shape, panel riveting along the sides of the missile, and heat shielding on the nose cone. By varying these target features in different missile configurations, and comparing them to each other, a relationship between specific target features and their effect on radar cross section can be obtained. This method makes it possible to estimate a range of possible values of a ballistic missile\u27s radar signature. The methodology will give users of signature data a better understanding of target characteristics when complete knowledge of the target\u27s configuration is unavailable

Multi-beam range imager for autonomous operations

For space operations from the Space Station Freedom the real time range imager will be very valuable in terms of refuelling, docking as well as space exploration operations. For these applications as well as many other robotics and remote ranging applications, a small potable, power efficient, robust range imager capable of a few tens of km ranging with 10 cm accuracy is needed. The system developed is based on a well known pseudo-random modulation technique applied to a laser transmitter combined with a novel range resolution enhancement technique. In this technique, the transmitter is modulated by a relatively low frequency of an order of a few MHz to enhance the signal to noise ratio and to ease the stringent systems engineering requirements while accomplishing a very high resolution. The desired resolution cannot easily be attained by other conventional approaches. The engineering model of the system is being designed to obtain better than 10 cm range accuracy simply by implementing a high precision clock circuit. In this paper we present the principle of the pseudo-random noise (PN) lidar system and the results of the proof of experiment

Spacetime structure of 5D hypercylindrical vacuum solutions with tension

We investigate geometrical properties of 5D cylindrical vacuum solutions with a transverse spherical symmetry. The metric is uniform along the fifth direction and characterized by tension and mass densities. The solutions are classified by the tension-to-mass ratio. One particular example is the well-known Schwarzschild black string which has a curvature singularity enclosed by a horizon. We focus mainly on geometry of other solutions which possess a naked singularity. The light signal emitted by an object approaching the singularity reaches a distant observer with finite time, but is infinitely red-shifted.Comment: revtex4, 5 pages, 2 figures. To appear in the proceedings of the 10th Asia Pacific Physics Conference (APPC10), Pohang, Korea, 21-24 Aug. 2007. Submitted to J. Korean Phys. Soc. Penrose diagram has been adde

Particle-in-cell and weak turbulence simulations of plasma emission

The plasma emission process, which is the mechanism for solar type II and type III radio bursts phenomena, is studied by means of particle-in-cell and weak turbulence simulation methods. By plasma emission, it is meant as a loose description of a series of processes, starting from the solar flare associated electron beam exciting Langmuir and ion-acoustic turbulence, and subsequent partial conversion of beam energy into the radiation energy by nonlinear processes. Particle-in-cell (PIC) simulation is rigorous but the method is computationally intense, and it is difficult to diagnose the results. Numerical solution of equations of weak turbulence (WT) theory, termed WT simulation, on the other hand, is efficient and naturally lends itself to diagnostics since various terms in the equation can be turned on or off. Nevertheless, WT theory is based upon a number of assumptions. It is, therefore, desirable to compare the two methods, which is carried out for the first time in the present paper with numerical solutions of the complete set of equations of the WT theory and with two-dimensional electromagnetic PIC simulation. Upon making quantitative comparisons it is found that WT theory is largely valid, although some discrepancies are also found. The present study also indicates that it requires large computational resources in order to accurately simulate the radiation emission processes, especially for low electron beam speeds. Findings from the present paper thus imply that both methods may be useful for the study of solar radio emissions as they are complementary.Comment: 21 pages, 9 figure

Currency Substitution via Expected Exchange Rate and Domestic Money Demand: An Empirical Analysis for Japan

In this paper the currency substitution hypothesis is tested empirically on the Japanese money demand, using monthly data from January 1977 to December 1989. Under a flexible exchange rate a rational economic agent forms currency portfolios for both transaction and speculative reasons for demanding money. The nonlinear multivariate maximum likelihood estimation was used to estimate jointly the Japanese money demand and the expected exchange rate equation; possible existence of current substitution is found. The empirical results indicate that (a) the expected exchange rate for the Japanese yen/Canadian dollar shows currency substitution due to speculative demand, and (b) the expected exchange rate of the yen/US dollar shows currency substitution due to transaction demand