Optimal Technology and Development

Skill intensive technologies seem to be adopted by rich countries rather than poor ones. Related to that observation, the ratio of wages of skilled to unskilled workers - the skill premium - shows two important features over time and across countries. In the US the skill premium decreased during the first half of the 20th century and it increased after 1950, evolving according to a U shaped pattern. On the other hand, the same measure across countries around 1990 is hump shaped when countries are ordered by GDP per worker. By modeling the decisions for factor accumulation and technology adoption, this paper gives a systematic explanation as to why we see ever more skill intensive technologies being adopted both over time in the US and across countries. The model developed here endogenously generates predictions for the skill premium that are consistent with both the US and international observations under the same set of parameter valuesskill biased technological change; skill premium,endogenous technology; inequality

Optimal Technology, Development and the role of Government

This paper highlights the effect of the presence of the goverment and its redistribution policy in the technology adoption decision. As a result it helps explain the differences in skill premium patterns across the North Atlantic between developed economies such as the US and Continental Europe.Taxes, skill biased technological change; skill premium; endogenous technology; inequality

Former Communist Countries and their transition to Capitalism

This paper uses the technology adoption general equilibrium model developed by Moscoso Boedo (2006) to analyze the transition for the countries of the former USSR and Eastern Europe. There the real output displayed a U-shapped pattern together with increases in inequality, which are features matched by the modelTransition economies, skill biased technological change; skill premium; endogenous technology; inequality

Sectoral Reallocation, Growth and Labor Income Inequality

This paper focuses on the transitory relationship between output level and Income inequality. As a result of either permanent or transitory sectoral technological shocks the economy will adjust to a new steady state equilibrium, but during the transition the dynamics of wages and workers will generate departures from the steady state level of income inequality.inequality, productivity

Evaluating the Effects of Entry Regulations and Firing Costs on International Income Differences

This paper analyzes the effects of entry regulations and firing costs on cross-country differences in income and productivity. We construct a general equilibrium industry- dynamics model and quantitatively evaluate it using the cross-country data on entry costs and firing costs. Entry costs lower overall productivity in an economy by keeping low- productivity establishments in operation and making the establishment size inefficiently large. Firing costs lower productivity by reducing the reallocation of labor from low- productivity establishments to high-productivity establishments. The linear regression of the data on the model prediction accounts for 27% of the cross-sectional variation in total factor productivity. Moving the level of entry costs and firing costs from the U.S. level to that of the average of low income countries (countries with a Gross National Income below 2% of the U.S. level) reduces TFP by 27% in the model without capital, and by 34% in the model with capital and capital adjustment costs.Entry cost, firing cost,international income differences,industry dynamics

Financial Structure, Informality and Development

This is a theory of total factor productivity based on measured capital market im- perfections and costs of creating and operating formal sector firms. We develop a firm dynamics model with endogenous formal and informal sectors where firms face a technol- ogy adoption opportunity. The model predicts that countries with a low degree of debt enforcement and high costs of formality are characterized by low allocative efficiency and a large share output produced by low productivity firms in the informal sector. We find that this mechanism is quantitatively important. When frictions are parameterized using the World Bank Doing Business database, the model explains up to 60% of total factor productivity differences between the US and developing economies.Financial Structure, Informal Sector, Productivity, Policy Distortions

Intangibles and Endogenous Firm Volatility over the Business Cycle

We are interested in the endogenous determination of firm level idiosyncratic volatility and its evolution over the business cycle. Using data from the Kauffman Firm Survey and Compustat, we find that idiosyncratic volatility at the firm level is negatively correlated with intangible expenditures (e.g. advertising, marketing, brand development, R&D). We also find that intangible expenses are highly pro-cyclical and that firm level volatility is counter-cyclical. To understand this mechanism, we propose a firm dynamics model with endogenous market participation. Firms that incur higher intangible expenses are able expand the firm and end up diversifying market-specific demand shocks by servicing more markets. The model is driven only by first moment shocks (i.e. shocks to aggregate TFP) and is able to capture the relationship between intangibles and risk as well as their cyclical properties.Endogenous idiosyncratic risk

Edge Physics Studies on the NSTX Spherical Tokamak

In this funding period, activities were focused on processing data for publication, writing code to facilitate processing of data in the future as programmatic needs arise, and closing down grant activities

SPHERICAL VS CYLINDRICAL ENGINE BEARINGS

ABSTRACT Spherical bearings have been used successfully in engines for some years. The spherical bearing geometry allows a simplified axisymmetric piston design; gradual rotation of the piston and rings results in axisymmetric sidewall wear, temperature distribution and thermal expansion. A previouslydescribed concept engine design incorporating a spherical joint piston was based on an existing production engine with a conventional cylindrical piston pin. Previously-developed finite element lubrication analysis methods are applied to both designs and predictive comparisons made. INTRODUCTION Spherical bearings have been used successfully in engines for some years. The large (400 mm bore) Sulzer Z40 series medium speed 4-stroke Diesel engine has a spherical piston bearing which has been well-documented by its maker The spherical bearing design allows a simplified axisymmetric piston design; gradual rotation of the piston and rings results in axisymmetric sidewall wear, temperature distribution and thermal expansion. Development of a low heat rejection Diesel engine sponsored by the Department of Energy (DOE) and monitored by NASA-Lewis began at Cummins Engine Company in 1989 and ended around 1995 [3-8]. The LE-55 (Low Emission, 55% thermal efficiency) concept engine design incorporating a spherical joint piston was based on an existing Cummins L10 production engine with a conventional cylindrical piston pin. The Cummins L10 was a 10 liter 6 cylinder in-line Diesel engine produced for 15 years ending around 1998. The SCE (Single-Cylinder Engine) L10 version used for test purposes formed the basis for successful life tests of LE-55 hardware

Theory-based scaling laws of near and far scrape-off layer widths in single-null L-mode discharges

Theory-based scaling laws of the near and far scrape-off layer (SOL) widths are analytically derived for L-mode diverted tokamak discharges by using a two-fluid model. The near SOL pressure and density decay lengths are obtained by leveraging a balance among the power source, perpendicular turbulent transport across the separatrix, and parallel losses at the vessel wall, while the far SOL pressure and density decay lengths are derived by using a model of intermittent transport mediated by filaments. The analytical estimates of the pressure decay length in the near SOL is then compared to the results of three-dimensional, flux-driven, global, two-fluid turbulence simulations of L-mode diverted tokamak plasmas, and validated against experimental measurements taken from an experimental multi-machine database of divertor heat flux profiles, showing in both cases a very good agreement. Analogously, the theoretical scaling law for the pressure decay length in the far SOL is compared to simulation results and to experimental measurements in TCV L-mode discharges, pointing out the need of a large multi-machine database for the far SOL decay lengths