Role of multi-level states on quantum-dot emission in photonic-crystal cavities

Semiconductor quantum dots embedded in photonic-crystal nanostructures have been the subject of intense study. In this context, quantum dots are often considered to be simple two-level emitters, i.e., the complexities arising from the internal finestructure are neglected. We show that due to the intricate spatial variations of the electric field polarization found in photonic crystal, the two orthogonal finestructure states of quantum dots in general both couple significantly to a cavity mode, implying that the two-level description is not sufficient. As a consequence the emission dynamics and spectra, which are often recorded in experiments, are modified both in the weak- and strong-coupling regimes. The proposed effects are found to be significant for system parameters of current state-of-the-art photonic-crystal cavities

Further Evidence on Hedge Funds Performance.

In this analysis we identify dynamic hedge fund strategies quantitatively pursuing a Principal Component Analysis following Fung and Hsieh (1997). We extract five dominant hedge fund strategies each representing similar investment styles and analyse the performance of each strategy by employing a multi-factor model comprising both market indices and passive option strategies along the lines of Agerwal and Naik (2000). We find that the majority of the five homogenous strategies show superior performance. However, correcting for survivorship bias this superior performance disappears.Hedge funds; Investment in securities; Performance; Dynamic strategies; Hedge funds performance;

Integrating communication protocol selection with partitioning in hardware/software codesign

This paper presents a codesign approach which incorpo-rates communication protocol selection as a design param-eter within hardware/software partitioning. The presented approach takes into account data transfer rates depending on communication protocol types and configurations, and different operating frequencies of system components, i.e. CPUs, ASICs, and busses. It also takes into account the tim-ing and area influences of drivers and driver calls needed to perform the communication. The approach is illustrated by a number of design space exploration experiments which use models of the PCI and USB communication protocols. 1