Rigorous Numerical Verification of Uniqueness and Smoothness in a Surface Growth Model

Based on numerical data and a-posteriori analysis we verify rigorously the uniqueness and smoothness of global solutions to a scalar surface growth model with striking similarities to the 3D Navier--Stokes equations, for certain initial data for which analytical approaches fail. The key point is the derivation of a scalar ODE controlling the norm of the solution, whose coefficients depend on the numerical data. Instead of solving this ODE explicitly, we explore three different numerical methods that provide rigorous upper bounds for its solutio

Germination rates of old and fresh seeds and their implications on invasiveness of the ornamental Canary Islands date palm (Phoenix canariensis)

In many countries, Canary Islands Date Palms (Phoenix canariensis) have escaped their horticulturally managed settings and have commenced to colonise surrounding natural bushland. While dispersed by various vectors, both birds and canids such as foxes, fluctuating environmental conditions may inhibit germination in the season of deposition. The potential of old, previous season’s seeds to germinate when conditions turn favourable has direct implications on the plant’s ability to establish viable, colonising populations. Nothing is known about the ability of older, previous season’s seeds to successfully germinate. Based in experimental data, this paper shows that that the seeds of Phoenix canariensis exhibit both substantial inter-specimen and inter-seasonal variations in their germination potential. The observed variability is caused by the high genetic diversity inherent in a given palm population, as well as by range of environmental factors. At the present stage it is impossible to separate these two. Directions for further research are outlined

The Global Financial Crisis, LDC Exports and Welfare: Analysis with a World Trade Model

Changes in international trade flows and world prices are major channels through which the global financial crisis will hit developing countries. The recession in the ‘global North’ triggered by the financial crisis and the resulting slowdown of growth in China and other major emerging economies will generate declines in demand for exports from developing countries, along with a reversal of the beneficial terms-of-trade trends that have favoured net exporters of primary commodities over the last few years. How these trade shocks and terms-of-trade trends affect economic performance and welfare in low-income countries depends on country-specific characteristics and requires a differentiated analysis across countries. This study uses a multi-region computable general equilibrium (CGE) world trade model to gauge the impact of a slowdown in economic activity in the OECD on trade performance, world prices, and aggregate welfare in the rest of the world with a particular focus on the least developed countries (LDCs) in sub-Saharan Africa and Asia. The results of the simulation analysis indicate the degree of vulnerability of different developing countries and regions distinguished in the model to impacts arising from the recession via the trade channel

The global financial crisis, LDC exports and welfare: analysis with a world trade model

Changes in international trade flows and world prices are major channels through which the global financial crisis will hit developing countries. The recession in the "global North" triggered by the financial crisis and the resulting slowdown of growth in China and other major emerging economies will generate declines in demand for exports from developing countries, along with a reversal of the beneficial terms-of-trade trends that have favoured net exporters of primary commodities over the last few years. How these trade shocks and terms-of-trade trends affect economic performance and welfare in low-income countries depends on country-specific characteristics and requires a differentiated analysis across countries. This study uses a multi-region computable general equilibrium (CGE) world trade model to gauge the impact of a slowdown in economic activity in the OECD on trade performance, world prices, and aggregate welfare in the rest of the world with a particular focus on the least developed countries (LDCs) in sub-Saharan Africa and Asia. The results of the simulation analysis indicate the degree of vulnerability of different developing countries and regions distinguished in the model to impacts arising from the recession via the trade channel

The Global Financial Crisis, LDC Exports and Welfare: Analysis with a World Trade Model

Changes in international trade flows and world prices are major channels through which the global financial crisis will hit developing countries. The recession in the ‘global North’ triggered by the financial crisis and the resulting slowdown of growth in China and other major emerging economies will generate declines in demand for exports from developing countries, along with a reversal of the beneficial terms-of-trade trends that have favoured net exporters of primary commodities over the last few years. How these trade shocks and terms-of-trade trends affect economic performance and welfare in low-income countries depends on country-specific characteristics and requires a differentiated analysis across countries. This study uses a multi-region computable general equilibrium (CGE) world trade model to gauge the impact of a slowdown in economic activity in the OECD on trade performance, world prices, and aggregate welfare in the rest of the world with a particular focus on the least developed countries (LDCs) in sub-Saharan Africa and Asia. The results of the simulation analysis indicate the degree of vulnerability of different developing countries and regions distinguished in the model to impacts arising from the recession via the trade channel

An optically activated cantilever using photomechanical effects in dye-doped polymer fibers

We report on what we believe is the first demonstration of an optically activated cantilever due to photomechanical effects in a dye-doped polymer optical fiber. The fiber is observed to bend when light is launched off-axis. The displacement angle monotonically increases as a function of the distance between the illumination point and the fiber axis, and is consistent with differential light-induced length changes. The photothermal and photo-reorientation mechanisms, each with its own distinct response time, are proposed to explain the observed time dependence. The measured degree of bending is consistent with a model that we have proposed which includes coupling between photoisomerization and heating. Most importantly, we have discovered that at high light intensity, a cooperative release of stress results in cis-to-trans isomerization that yields a large and abrupt length change.Comment: 13 pages, 16 figure

Minimal Pathway for the Regeneration of Redox Cofactors

[Image: see text] Effective metabolic pathways are essential for the construction of in vitro systems mimicking the biochemical complexity of living cells. Such pathways require the inclusion of a metabolic branch that ensures the availability of reducing equivalents. Here, we built a minimal enzymatic pathway confinable in the lumen of liposomes, in which the redox status of the nicotinamide cofactors NADH and NADPH is controlled by an externally provided formate. Formic acid permeates the membrane where a luminal formate dehydrogenase uses NAD(+) to form NADH and carbon dioxide. Carbon dioxide diffuses out of the liposomes, leaving only the reducing equivalents in the lumen. A soluble transhydrogenase subsequently utilizes NADH for reduction of NADP(+) thereby making NAD(+) available again for the first reaction. The pathway is functional in liposomes ranging from a few hundred nanometers in diameter (large unilamellar vesicles) up to several tens of micrometers (giant unilamellar vesicles) and remains active over a period of 7 days. We demonstrate that the downstream biochemical process of reduction of glutathione disulfide can be driven by the transfer of reducing equivalents from formate via NAD(P)H, thereby providing a versatile set of electron donors for reductive metabolism

Climate Change and Economic Growth: An Intertemporal General Equilibrium Analysis for Egypt

Due to the high concentration of economic activity along the low-lying coastal zone of the Nile delta and its dependence on Nile river streamflow, Egypt's economy is highly exposed to adverse climate change. Adaptation planning requires a forward-looking assessment of climate change impacts on economic performance at economy-wide and sectoral level and a cost-benefit assessment of conceivable adaptation investments. This study develops a multisectoral intertemporal general equilibrium model with forward-looking agents, population growth and technical progress to analyse the long-run growth prospects of Egypt in a changing climate. Based on a review of existing estimates of climate change impacts on agricultural productivity, labor productivity and the potential losses due to sea-level rise for the country, the model is used to simulate the effects of climate change on aggregate consumption, investment and welfare up to 2050. Available cost estimates for adaptation investments are employed to explore adaptation strategies. On the methodological side, the present study overcomes the limitations of existing recursive-dynamic computable general models for climate change impact analysis by incorporating forward-looking expectations. Moreover, it extends the existing family of discrete-time intertemporal computable general equilibrium models to which our model belongs by incorporating population growth and technical progress. On the empirical side, the model is calibrated to a social accounting matrix that reflects the observed current structure of the Egyptian economy, and the climate change impact and adaptation scenarios are informed by a close review of existing quantitative estimates for the size order of impacts and the costs of adaptation measures. The simulation analysis suggests that in the absence of policy-led adaptation investments, real GDP towards the middle of the century will be nearly 10 percent lower than in a hypothetical baseline without climate change. A combination of adaptation measures, that include coastal protection investments for vulnerable sections along the low-lying Nile delta, support for changes in crop management practices and investments to raise irrigation efficiency, could reduce the GDP loss in 2050 to around 4 percent

Climate Change and Economic Growth: An Intertemporal General Equilibrium Analysis for Egypt

Due to the high concentration of economic activity along the low-lying coastal zone of the Nile delta and its dependence on Nile river streamflow, Egypt's economy is highly exposed to adverse climate change. Adaptation planning requires a forward-looking assessment of climate change impacts on economic performance at economy-wide and sectoral level and a cost-benefit assessment of conceivable adaptation investments. This study develops a multisectoral intertemporal general equilibrium model with forward-looking agents, population growth and technical progress to analyse the long-run growth prospects of Egypt in a changing climate. Based on a review of existing estimates of climate change impacts on agricultural productivity, labor productivity and the potential losses due to sea-level rise for the country, the model is used to simulate the effects of climate change on aggregate consumption, investment and welfare up to 2050. Available cost estimates for adaptation investments are employed to explore adaptation strategies. On the methodological side, the present study overcomes the limitations of existing recursive-dynamic computable general models for climate change impact analysis by incorporating forward-looking expectations. Moreover, it extends the existing family of discrete-time intertemporal computable general equilibrium models to which our model belongs by incorporating population growth and technical progress. On the empirical side, the model is calibrated to a social accounting matrix that reflects the observed current structure of the Egyptian economy, and the climate change impact and adaptation scenarios are informed by a close review of existing quantitative estimates for the size order of impacts and the costs of adaptation measures. The simulation analysis suggests that in the absence of policy-led adaptation investments, real GDP towards the middle of the century will be nearly 10 percent lower than in a hypothetical baseline without climate change. A combination of adaptation measures, that include coastal protection investments for vulnerable sections along the low-lying Nile delta, support for changes in crop management practices and investments to raise irrigation efficiency, could reduce the GDP loss in 2050 to around 4 percent