Intensity of technology use and per capita real GDP across some African countries

African countries may have fared poorly compared to some countries in other regions, but relative to their own performance history some African countries have done quite well over the past eight years. In particular 2004 and 2005 were especially good years. How can such performance be made to stick and even expand? The answer to that question requires better understanding of the source of good performance. This paper proceeds on the assumption that technology was, at least partially, responsible. The result shows that a feeble technology undercuts per capita real GDP across African countries. However, the impacts of new technologies, measured by the intensities of internet and cell phone use are very strong. The policy implication of the findings speaks to the need for investment in new technologies for which productivity is high and the adoption and diffusion costs seem low. Further research can clarify the findings and policy by expanding and improving the data coverage, and examining effects on income of different kinds of technologies

Intermittency and roughening in the failure of brittle heterogeneous materials

Stress enhancement in the vicinity of brittle cracks makes the macro-scale failure properties extremely sensitive to the micro-scale material disorder. Therefore: (i) Fracturing systems often display a jerky dynamics, so-called crackling noise, with seemingly random sudden energy release spanning over a broad range of scales, reminiscent of earthquakes; (ii) Fracture surfaces exhibit roughness at scales much larger than that of material micro-structure. Here, I provide a critical review of experiments and simulations performed in this context, highlighting the existence of universal scaling features, independent of both the material and the loading conditions, reminiscent of critical phenomena. I finally discuss recent stochastic descriptions of crack growth in brittle disordered media that seem to capture qualitatively - and sometimes quantitatively - these scaling features.Comment: 38 pages, invited review for J. Phys. D cluster issue on "Fracture: from the Atomic to the Geophysics Scale

On the long-run determinants of real exchange rates for developing countries : Evidence from Africa, Latin America and Asia

The main goal of this paper is to tackle the empirical issues of the real exchange rate litterature by applying recently developed panel cointegration techniques to a structural long-run real exchange rate equation. We consider here a sample of 45 developing countries, divided into three groups according to geographical criteria: Africa, Latin America and Asia. Our investigations confirm that having a reference to assess the degree of distortion of real exchange rate is not as simple as it can be thought with the PPP concept. The real exchange rate is e?ectively at the centre of an economic spiral and its value depends on the economic specificities of each country. In other words, we don’t have a fixed and general norm but, for each economy, the real exchange rate trajectory depends on its development level, on the way economic policy is conducted, and on its position on the international market.http://deepblue.lib.umich.edu/bitstream/2027.42/39957/3/wp571.pd

Determinants of industry-level production capacity in Poland

The paper deals with the production capacity – innovation nexus. It focuses on development of total factor productivity (TFP), which is one of the determinants of production capacity of the economy. The analysis is carried out using 2-digit NACE rev. 2 level Polish manufacturing data covering the most recent period of 2008-2012. TFP is estimated using theoretical framework based on a Cobb-Douglas production function and an attempt is made to identify the role of innovation activities in forming TFP in case of economy of an emerging country under recent economic crisis. The findings suggest that the non-R&D innovation activities are of more importance in determining TFP of Polish manufacturing divisions than R&D expenditures

A k-deformed Model of Growing Complex Networks with Fitness

The Barab\'asi-Bianconi (BB) fitness model can be solved by a mapping between the original network growth model to an idealized bosonic gas. The well-known transition to Bose-Einstein condensation in the latter then corresponds to the emergence of "super-hubs" in the network model. Motivated by the preservation of the scale-free property, thermodynamic stability and self-duality, we generalize the original extensive mapping of the BB fitness model by using the nonextensive Kaniadakis k-distribution. Through numerical simulation and mean-field calculations we show that deviations from extensivity do not compromise qualitative features of the phase transition. Analysis of the critical temperature yields a monotonically decreasing dependence on the nonextensive parameter k