Productivity growth and product variety : gains from imitation and education

Is there a correlation between productivity and product variety? Certainly it appears that the rich countries are more productive and have more product variety than the poor nations. In fact, the relationship is quite strong when measured in levels. Does this same correlation hold up when measured in growth rates? If so, can poor countries imitate the success of the rich? Addison provides theoretical and empirical reasons to believe the answer to both questions is yes. Recent economic theory suggests that rising variety in factor inputs can help avoid diminishing marginal returns. Product variety can also sustain learning-by-doing which would otherwise be exhausted in a fixed number of products. Finally, invention or imitation adds to the stock of non-rival knowledge. There have been only two previous empirical tests of the correlation between growth in product variety and productivity growth. Both were affirmative but neither examined a wide range of developing countries and neither looked deeper to test what might drive product variety. This research is based on a cross-country sample of 29 countries (13 rich and 16 poor). The data display a statistically significant and positive relationship between growth in product variety and productivity growth when condition on other variables such as research and development (R&D) employment, macroeconomic stability, and domestic security. These results are robust to the addition and subtraction of various explanatory variables but fragile with respect to an influential data point for Venezuela. Industrial nations tend to generate most of their productivity gains through R&D employment in a stable environment that results in better production processes and product quality. In contrast, the largest source of productivity growth in developing countries is product variety imitation while instability takes away from productivity. Addison tests various explanations for growth in variety. The results show that nations furthest from the frontier of observable variety tend to imitate fastest, with the ability to imitate being improved by educational attainment and by productivity gains. This could be a source of hope for small, less developed nations. Growth in market size was not correlated with growth in variety, though this may be due to a rather short sample period of only eight years. In addition to the empirical testing, Addison also contributes to a general discussion of measurement concepts and measurement issues related to product variety and sets out an agenda for further research.Economic Theory&Research,Economic Conditions and Volatility,Environmental Economics&Policies,Public Health Promotion,Health Monitoring&Evaluation,Economic Theory&Research,Achieving Shared Growth,Environmental Economics&Policies,Inequality,Economic Growth

Synchronization Limits of Chaotic Circuits

Through system modeling with electronic circuits, two circuits were constructed that exhibit chaos over a wide ranges of initial conditions. The two circuits were one that modeled an algebraically simple “jerk” function and a resistor-inductor-diode (RLD) circuit where the diode was reverse-biased on the positive voltage cycle of the alternating current source. Using simulation data from other experiments, the waveforms, bifurcation plots, and phase space plots of the concrete circuit were verified. Identical circuits were then built containing variable components and coupled to their original, matching circuits. The variable components were used to observe a wide range of conditions to establish the desynchronization parameters and the range of synchronization

By How Much Does Conflict Reduce Financial Development?

Financial development is vulnerable to social conflict. Conflict reduces the demand for domestic currency as a medium of exchange and a store of value. Conflict also leads to poor quality governance, including weak regulation of the financial system, thereby undermining the sustainability of financial institutions. Conflict therefore reduces the social return to financial liberalization and other financial-sector reforms. This paper presents a theoretical model integrating the effects of conflict and financial liberalization, and then tests the model on data for 79 countries. Using an explanatory variable that measures the intensity of conflict (from low to high) the results show that conflict significantly reduces financial development, and that this negative effect increases as conflict intensifies. The paper concludes that conflict reduction is essential if financial reform is to have its full benefit for development

Optimizing in vitro extracellular matrix production using polymer scaffolds with targeted pore size

Extracellular matrix (ECM) has been shown to provide the framework needed for healthy tissue to grow after experiencing an injury. The optimization of growing ECM is a pressing concern in the tissue regeneration field. From prior research, an in vitro approach for harvesting ECM has been created using polyurethane (PU) foams seeded with cells. Our approach aimed at discovering if the pore size of the foams increased the amount of recovered ECM. Scaffolds of targeted pore size were created by separating sugar granules using a sieve, packing the sugar into a cylindrical mold, then pouring PU over the sugar. Three groups were created: a control of all sugar granules, sugar granules sized 250-500um, and sugar granules sized 125-250um. Cells were seeded and grown for three weeks on the foams. After three weeks, the scaffolds were dissolved and the ECM was collected. The final yields of each scaffold type produced statistically insufficient results. The control scaffolds yielded 4.15 mg ECM , the 125-250um pore scaffold yielded 3.55mg, and the 250-500um pore scaffold yielded 3.82mg. Further, the overall structures of the ECM did not appear different for each group. The results of the study show the pore size of the scaffold does not effect the overall production of ECM. Sieving sugar for specific pore size appears to have a minimal effect and is not necessary in creating the scaffolds

Characterization of Navassa National Wildlife Refuge: A preliminary report for NF-06-05 (NOAA ship "Nancy Foster", April 18-30, 2006)

Navassa is a small, undeveloped island in the Windward Passage between Jamaica and Haiti. It was designated a National Wildlife Refuge under the jurisdiction of the U.S. Fish and Wildlife Service in 1999, but the remote location makes management and enforcement challenging, and the area is regularly fished by artisanal fishermen from Haiti. In April 2006, the NOAA Center for Coastal Fisheries and Habitat Research conducted a research cruise to Navassa. The cruise produced the first high-resolution multibeam bathymetry for the area, which will facilitate habitat mapping and assist in refuge management. A major emphasis of the cruise was to study the impact of Haitian fishing gear on benthic habitats and fish communities; however, in 10 days on station only one small boat was observed with five fishermen and seven traps. Fifteen monitoring stations were established to characterize fish and benthic communities along the deep (28-34 m) shelf, as these areas have been largely unstudied by previous cruises. The fish communities included numerous squirrelfishes, triggerfishes, and parrotfishes. Snappers and grouper were also present but no small individuals were observed. Similarly, conch surveys indicated the population was in low abundance and was heavily skewed towards adults. Analysis of the benthic photoquadrats is currently underway. Other cruise activities included installation of a temperature logger network, sample collection for stable isotope analyses to examine trophic structure, and drop camera surveys to ground-truth habitat maps and overhead imagery. (PDF contains 58 pages

Self-Diffusion in Sodium Single Crystals

The objective of this investigation was the study of self-diffusion in single-crystal sodium using tracer techniques and the determination of the diffusion constant and activation energy. Precise values of these quantities can be obtained by using Fick\u27s second law of diffusion and the relation D = D₀ exp (- Q/RT) provided the concentration of the diffusing isotope is kept very small. However, in the above relation, the quanties D₀ (diffusion constant) and Q (activation energy) may vary with the composition of the crystal and with impurity content but are independent of temperature

Labour Demand Research: Towards a Better Match between Better Theory and Better Data

At first blush, most advances in labour demand were achieved by the late 1980s. Since then progress might appear to have stalled. We argue to the contrary that significant progress has been made in understanding labour market frictions and imperfections, and in modelling search behaviour and heterogeneous preferences. Perhaps most notable have been the improvements in data, in the form of longitudinal matched employer-employee data, and in techniques and algorithms (e.g. for solving heterogeneous parameter models). In short, the Cinderella status of the field is frankly overdrawn. Nevertheless, a chief lacuna remains the need for a better match between theory and data. This paper provides a critical albeit eclectic assessment of these developments, along the dimensions of the static and dynamic theory of labour demand, wage formation, and estimation, noting advances and limitations. As is conventional, somewhat greater emphasis is placed on the latter

Aid to conflict-affected countries : lessons for donors

The first section looks at the implications of conflict for aid effectiveness and selectivity. We argue that, while aid is generally effective in promoting growth and by implication reducing poverty, it is more effective in promoting growth in post-conflict countries. We then consider the implications of these findings for donor selectivity models and for assessment of donor performance in allocating development aid among recipient countries. We argue that, while further research on aid effectiveness in post-conflict scenarios is needed, existing selectivity models should be augmented with, inter alia, post-conflict variables, and donors should be evaluated on the basis, inter alia, of the share of their aid budgets allocated to countries experiencing post-conflict episodes. We also argue for aid delivered in the form of projects to countries with weak institutions in early post-conflict years. The second section focuses on policies for donors operating in conflict-affected countries. We set out five of the most important principles: (1) focus on broad-based recovery from war; (2) to achieve a broad-based recovery, get involved before the conflict ends; (3) focus on poverty, but avoid &lsquo;wish lists&rsquo;; (4) help to reduce insecurity so aid can contribute more effectively to growth and poverty reduction; and (5) in economic reform, focus on improving public expenditure management and revenue mobilisation. The third section concludes by emphasising the fact that there is no hard or fast dividing line between &lsquo;war&rsquo; and &lsquo;peace&rsquo; and that it may take many years for a society to become truly &lsquo;post&rsquo;-conflict&rsquo;. Donors, therefore, need to prepare for the long haul.<br /