In his thesis, Kiyoun Lee describes his studies into tandem and organocatalytic oxa-conjugate addition reactions for the synthesis of complex tetrahydropyrans (THP). Readers gain insight into the new methods Lee employs for the synthesis of biologically interesting natural products including (+)-leucascandrolide A, (+)-dactylolide, and (+-)diospongin A. The reactions Lee investigates are applicable to a broad range of substrates and proceed with excellent stereoselectivity. Moreover, the methodologies allow the synthesis of a wide range of THP-containing compounds. The development of reactions, such as those discussed by Lee, has the potential to impact natural product synthesis, pharmaceutical development and chemical biology.
Single-channel hands-free teleconferencing systems are becoming popular. In order to enhance the communication quality of these systems, more and more stereophonic sound devices with two loudspeakers and two microphones are deployed. Because of the coupling between loudspeakers and microphones, there may be strong echoes, which make real-time communication very difficult. The best way we know to cancel these echoes is via a stereo acoustic echo canceller (SAEC), which can be modelled as a two-input/two-output system with real random variables. In this work, the authors recast this problem into a single-input/single-output system with complex random variables thanks to the widely linear model. From this new convenient formulation, thay re-derive the most important aspects of a SAEC, including identification of the echo paths with adaptive filters, double-talk detection, and suppression.
The state-of-the-art in stereoselective synthesis!