This paper introduces endogenous longevity into an otherwise standard overlapping generations model with capital. In the model, a young agent may increase the length of her old age by incurring investments in health. Such private health investments are assumed to be more 'productive' if accompanied by complementary tax-financed public health programs. The presence of the public input in private longevity is shown to expose the economy to aggregate endogenous fluctuations and even chaos, and such volatility is impossible in its absence. The model is capable of generating dramatic reversals in life expectancy as has been observed in many countries. r

We describe a photonic-plasmonic nanostructure, for significantly enhancing the absorption of long-wavelength photons in thin-film silicon solar cells, with the promise of exceeding the classical 4n2 limit for enhancement. We compare identical solar cells deposited on the photonic-plasmonic structure, randomly textured back reflectors and silver-coated flat reflectors. The state-of-the-art back reflectors, using annealed Ag or etched ZnO, had high diffuse and total reflectance. For nano-crystalline Si absorbers with comparable thickness, the highest absorption and photo-current of 21.5 mA/cm2 was obtained for photonic-plasmonic back-reflectors. The periodic photonic plasmonic structures scatter and reradiate light more effectively than a randomly roughened surface.

We report on the measurement of fundamental properties such as deep defects and hole mobility in poly-3-hexyl-thiophene (P3HT)/[6,6]-phenyl-C60-butyric acid methyl ester(PCBM) solar cells when the cells are exposed to solar radiation without any atmospheric exposure. It is found that the midgap defect density in P3HT and the interface density between P3HT and PCBM increase significantly upon light soaking along with a reduction in hole mobility in P3HT. The increase in defect density leads to a corresponding increase in reverse saturation current of the diode, and the corresponding decrease in open circuit voltage of the cell upon light soaking.

In models of money with an infinitely-lived representative agent (ILRA models), the optimal monetary policy is almost always the Friedman rule. Overlapping generations (OG) models are different: in this paper, we study how they are different, and why. We investigate the welfare properties of monetary policy in a simple OG model under two different types of money demand specifications and under two alternative assumptions about the generational timing of taxes for money retirement. We find that the Friedman rule is generally not the policy that maximizes steady-state utility. We conclude that the key difference between ILRA and OG monetary models is that in the latter, the standard method for constructing a monetary regime causes transactions involving money to become intergenerational transfers. Overlapping generations are different in this regard; we study how they are different and why.JEL Classifications: E31, E42, E63

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