Stitching IC Images

Image stitching software is used in many areas such as photogrammetry, biomedical imaging, and even amateur digital photography. However, these algorithms require relatively large image overlap, and for this reason they cannot be used to stitch the integrated circuit (IC) images, whose overlap is typically less than 60 pixels for a 4096 by 4096 pixel image. In this paper, we begin by using algorithmic graph theory to study optimal patterns for adding IC images one at a time to a grid. In the remaining sections we study ways of stitching all the images simultaneously using different optimisation approaches: least squares methods, simulated annealing, and nonlinear programming

Stock Price Dynamics and Option Valuations under Volatility Feedback Effect

According to the volatility feedback effect, an unexpected increase in squared volatility leads to an immediate decline in the price-dividend ratio. In this paper, we consider the properties of stock price dynamics and option valuations under the volatility feedback effect by modeling the joint dynamics of stock price, dividends, and volatility in continuous time. Most importantly, our model predicts the negative effect of an increase in squared return volatility on the value of deep-in-the-money call options and, furthermore, attempts to explain the volatility puzzle. We theoretically demonstrate a mechanism by which the market price of diffusion return risk, or an equity risk-premium, affects option prices and empirically illustrate how to identify that mechanism using forward-looking information on option contracts. Our theoretical and empirical results support the relevance of the volatility feedback effect. Overall, the results indicate that the prevailing practice of ignoring the time-varying dividend yield in option pricing can lead to oversimplification of the stock market dynamics.Comment: 23 pages, 7 figures, 2 table

Economic integration in an urban labor market

This study explores the relationship between migration and employment in Ouagadougou. Using both a cross-sectional and a longitudinal approach, we compare the economic integration of migrants to that of non-migrants. Contrary to most studies based on urban samples, the data used here come from a national survey. It is thus possible to reintegrate into the analysis the migration episodes to Ouagadougou of those respondents elsewhere in Burkina Faso. Results indicate that, contrary to the dominant hypothesis, with the introduction of time-dependent variables, migrants are not more disadvantaged than non-migrants in the labour market, whether we consider the situation at the time of the survey or at their time of arrival in the city hunting for their first paid job.Burkina Faso, employment, migration, urban

Electron acceleration in vacuum by ultrashort and tightly focused radially polarized laser pulses

Exact closed-form solutions to Maxwell's equations are used to investigate electron acceleration driven by radially polarized laser beams in the nonparaxial and ultrashort pulse regime. Besides allowing for higher energy gains, such beams could generate synchronized counterpropagating electron bunches.Comment: 3 pages, 3 figures. To appear in the proceedings of the Ultrafast Phenomena XVIII conferenc