Broadcast is a fundamental operation of wireless ad hoc networks (WANET) and has been widely studied in the last decade. However, very few existing broadcasting strategies has considered the scenarios with sleeping schedule, which is a prevalent power-saving method in wireless networks. In this paper we study the sleeping schedule-aware minimum latency broadcast (MLB-SA) problem in WANETs and prove its NPhardness. By constructing a Shortest Path Tree (SPT) defined with the latency function on the network, we derive a lower bound on the broadcast latency theoretically. Following the topdown layered approach and using the D2-coloring solution, we proposed two progressively improved algorithms: the Simple LAyered Coloring algorithm (SLAC) and the Enhanced LAyered Coloring algorithm (ELAC) for the MLB-SA problem. The SLAC has an approximation ratio of O(Δ 2 + 1) where Δ is maximum degree of the network, while the ELAC has constant approximation ratio of 24|T |+1 where |T | is the number of timeslots in a scheduling period. The two algorithms have O(n 2 ) and O(n 3 ) time complexities respectively. The performance of the proposed algorithms are evaluated by simulations.

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An undoped GaN homoepitaxial layer has been grown by metalorganic chemical vapour deposition on a conductive free-standing bulk GaN substrate. The dislocation density of the homoepitaxial layer characterised by cathodoluminescence mapping technique is about 6 Â 10 6 cm 22 . By fabricating a vertical Schottky diode structure, the resistivity of the homoepitaxial layer is estimated in the order of 10 9 Vcm at room temperature. This study indicates that highly-resistive GaN can be produced by a homoepitaxy approach.

By using hologram quantitative structure-activity relationship (HQSAR) and comparative molecular field analysis (CoMFA) methods, the relationships between the structures of 49 gallic acid derivatives and their analgesic activity have been investigated to yield statistically reliable models with considerable predictive power. The best HQSAR model was generated using atoms, bond and connectivity as fragment distinction parameters and fragment size 5-7 from a hologram length of 307 with 3 components. High conventional r2 (r2 = 0.825) and cross-validation r2 (r2(cv) = 0.726) values were obtained. CoMFA analyses varying lattice size and location, grid spacing, probe charges and using, Tripos standard and Indicator force field were performed. The best model was developed with 4 components using sp3-hybridized carbon atom with +1.0 charge as probe, grid spacing (2 A), lattice offset (1.0, 3.0, -2.5). The CoMFA model showed a conventional correlation coefficient r2 of 0.889 and across-validation r2(cv) equals to 0.633. The robustness and predictive ability of the HQSAR and CoMFA models have been validated by means of an external test set. The results indicate that both models possess high statistical quality in the prediction of analgesic potency of novel gallic acid analogs.