The Great Wars, The Great Crash, and the Unit Root Hypothesis: Some New Evidence About an Old Stylized Fact

For decades, the prevailing sentiment among economists was that growth rates remain constant over the long run. Kaldor considered this to be one of the six important 'stylized facts' that theory should address, and until the emergence of endogenous growth models, this was a fundamental feature of growth theory. This paper uses an endogenous trend break model to investigate the unit root hypothesis for 16 countries, using annual GDP data spanning up to 130 years. Rejection of the unit root, which is facilitated by the inclusion of a trend break, introduces the possibility of examining the long run behavior of growth rates. We find that most countries exhibited fairly steady growth for a period lasting several decades. The termination of this period was usually characterized by a significant, and sudden, drop in GDP levels. But rather than simply returning to their previous steady state path, as predicted by the standard neoclassical growth model, most countries continued to grow at roughly double their prebreak rates for many decades, even after their original growth path had been surpassed.

Ion-Specific Hydration Effects: Extending the Poisson-Boltzmann Theory

In aqueous solutions, dissolved ions interact strongly with the surrounding water, thereby modifying the solution properties in an ion-specific manner. These ion-hydration interactions can be accounted for theoretically on a mean-field level by including phenomenological terms in the free energy that correspond to the most dominant ion-specific interactions. Minimizing this free energy leads to modified Poisson-Boltzmann equations with appropriate boundary conditions. Here, we review how this strategy has been used to predict some of the ways ion-specific effects can modify the forces acting within and between charged interfaces immersed in salt solutions.Comment: 11 pages, 2 figure

Interaction between Heterogeneously Charged Surfaces: Surface Patches and Charge Modulation

When solid surfaces are immersed in aqueous solutions, some of their charges can dissociate and leave behind charge patches on the surface. Although the charges are distributed heterogeneously on the surface, most of the theoretical models treat them as homogeneous. For overall non-neutral surfaces, the assumption of surface charge homogeneity is rather reasonable, since the leading terms of two such interacting surfaces depend on the non-zero average charge. However, for overall neutral surfaces, the nature of the surface charge distribution is crucial in determining the inter-surface interaction. In the present work we study the interaction between two charged surfaces across an aqueous solution for several charge distributions. The analysis is preformed within the framework of the linearized Poisson-Boltzmann theory. For periodic charge distributions the interaction is found to be repulsive at small separations, unless the two surface distributions are completely out-of-phase with respect to each other. For quenched random charge distributions we find that due to the presence of the ionic solution in between the surfaces, the inter-surface repulsion dominates over the attraction in the linear regime of the Poisson-Boltzmann theory. The effect of quenched charge heterogeneity is found to be particularly substantial in the case of large charge domains.Comment: 11 pages, 4 figure

Trade and the Rate of Income Convergence

To the extent that trade policy affects trade flows between countries, the ramifications can be far-reaching from an economic growth perspective. This paper examines one aspect of these ramifications, namely the impact of changes in the extent of trade between countries on changes in the rate of reduction in the size of the income gap that exists between them. Export and import data are used as the criteria for determining bilateral trade between major trade partners, resulting in the creation of 127 pairs of countries on the basis of export data and 134 pairs on the basis of import data. An increase in trade between major trade partners - and in particular, increased exports by poorer countries to their wealthier partners - is shown to be related to an increase in the rate of convergence between the countries.

Commerce international, disparites des revenues et pauvrete

Le professeur Dan Ben-David de l'Université de Tel Aviv présente un examen approfondi des liens entre le commerce, la croissance économique et la disparité des revenus entre les pays. Le professeur L. Alan Winters de l'Université du Sussex décrit les divers moyens par lesquels le commerce peut influer sur les possibilités de revenu des personnes pauvres. Cette publication contient également un aperçu non technique des deux rapports d'experts.Professor Dan Ben-David of Tel Aviv University takes an in-depth look at the linkages between trade, economic growth, and income disparity among nations. Professor L. Alan Winters of the University of Sussex discusses the various channels by which trade may affect the income opportunities of poor people. The publication also includes a non-technical overview of the two expert reports

Trade, income disparity and poverty

Professor Dan Ben-David of Tel Aviv University takes an in-depth look at the linkages between trade, economic growth, and income disparity among nations. Professor L. Alan Winters of the University of Sussex discusses the various channels by which trade may affect the income opportunities of poor people. The publication also includes a non-technical overview of the two expert reports

Revisiting the Poisson-Boltzmann theory: charge surfaces, multivalent ions and inter-plate forces

The Poisson-Boltzmann (PB) theory is extensively used to gain insight on charged colloids and biological systems as well as to elucidate fundamental properties of intermolecular forces. Many works were devoted in the past to study PB related features and to confirm them experimentally. In this work we explore the properties of inter-plate forces in terms of different boundary conditions. We treat the cases of constant surface charge, constant surface potential and mixed boundaries. The interplay between electrostatic interactions, attractive counter-ions release, and repulsive van 't Hoff contribution are discussed separately for each case. Finally, we discuss how the crossover between attractive and repulsive interactions for constant surface charge case is influenced by the presence of multivalent counter-ions, where it is shown that the range of the attractive interaction grows with the valency

The influence of remote aerosol forcing from industrialised economies on the future evolution of East and West African rainfall

Past changes in global industrial aerosol emissions have played a significant role in historical shifts in African rainfall and yet assessment of the impact on African rainfall of near term (10-40 year) potential aerosol emission pathways remains largely unexplored. Whilst existing literature links future aerosol declines to a northward shift of Sahel rainfall, existing climate projections rely on RCP scenarios that do not explore the range of air quality drivers. Here we present projections from two emission scenarios that better envelope the range of potential aerosol emissions. More aggressive emission cuts results in northward shifts of the tropical rain-bands whose signal can emerge from expected internal variability on short, 10-20 year, time horizons. We also show for the first time that this northward shift also impacts East Africa, with evidence of delays to both onset and withdrawal of the Short Rains. However, comparisons of rainfall impacts across models suggest that only certain aspects of both the West and East African model responses may be robust, given model uncertainties. This work motivates the need for wider exploration of air quality scenarios in the climate science community to assess the robustness of these projected changes and to provide evidence to underpin climate adaptation in Africa. In particular, revised estimates of emission impacts of legislated measures every 5-10 years would have a value in providing near term climate adaptation information for African stakeholders

Mixture-of-Parents Maximum Entropy Markov Models

We present the mixture-of-parents maximum entropy Markov model (MoP-MEMM), a class of directed graphical models extending MEMMs. The MoP-MEMM allows tractable incorporation of long-range dependencies be- tween nodes by restricting the conditional distribution of each node to be a mixture of distributions given the parents. We show how to efficiently compute the exact marginal posterior node distributions, regardless of the range of the dependencies. This enables us to model non-sequential correlations present within text documents, as well as between in- terconnected documents, such as hyperlinked web pages. We apply the MoP-MEMM to a named entity recognition task and a web page classification task. In each, our model shows significant improvement over the basic MEMM, and is competitive with other long- range sequence models that use approximate inference. 1 Introductio