A novel low-cost beam-steering technique based on the extended-resonance power-dividing method
A novel phased array based on the extended-resonance power-dividing method has been presented. This method eliminates the need for separate power splitter and phase shifters in a conventional phased-array system, resulting in a substantial reduction in circuit complexity and cost. As a proof of principle, a 2-GHz extended-resonance-based phased array using varactor diodes and microstrip patch antennas has been designed, fabricated, and tested. The measured scan range is 20/spl deg/ and the measured efficiency of the extended-resonance phased-array feed is typically 80%, which corresponds to 1 dB of insertion loss.
A 24-GHz Modular Transmit Phased Array
This paper presents a 24-GHz modular transmit phased array based on the extended-resonance technique. The extended-resonance technique, capable of obviating the need for separate power divider and phase shifters, is utilized along with heterodyne mixing in the proposed phased array. Heterodyne mixing allows phase shifting to be performed at lower frequencies. A modular approach is exploited to realize a scalable phased-array design. The design complexity associated with large phased arrays can be significantly reduced by using this approach. Moreover, a modified extended-resonance circuit topology to enhance the scan range is proposed. As a proof-of-principle, the 24-GHz transmit phased array is fabricated and the measurement results are presented.
Nuclear sphingolipid metabolism.
Nuclear lipid metabolism is implicated in various processes, including transcription, splicing, and DNA repair. Sphingolipids play roles in numerous cellular functions, and an emerging body of literature has identified roles for these lipid mediators in distinct nuclear processes. Different sphingolipid species are localized in various subnuclear domains, including chromatin, the nuclear matrix, and the nuclear envelope, where sphingolipids exert specific regulatory and structural functions. Sphingomyelin, the most abundant nuclear sphingolipid, plays both structural and regulatory roles in chromatin assembly and dynamics in addition to being an integral component of the nuclear matrix. Sphingosine-1-phosphate modulates histone acetylation, sphingosine is a ligand for steroidogenic factor 1, and nuclear accumulation of ceramide has been implicated in apoptosis. Finally, nuclear membrane-associated ganglioside GM1 plays a pivotal role in Ca(2+) homeostasis. This review highlights research on the factors that control nuclear sphingolipid metabolism and summarizes the roles of these lipids in various nuclear processes.