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Data broadcast is a fundamental operation in wireless sensor networks (WSNs). The existence of wireless interference makes it nontrivial to design a minimum-latency broadcast scheme, which is known to be NP-hard. Existing works all assume strict time synchronization and provide centralized TDMA scheduling algorithms. However, WSNs in practice are more likely to be distributed asynchronous systems. In this paper, we investigate the problem of data broadcast with minimum latency for distributed asynchronous WSNs. To this end, we propose a Distributed Asynchronous Broadcast (DAB) algorithm which crucially leverages an elaborately optimized carrier-sensing range together with collision-backoff schemes to coordinate the transmissions among the nodes on a predetermined broadcast backbone. Theoretical analysis shows that DAB is order-optimal and achieves constant factor approximation to the optimal delay. We then conduct extensive simulations to evaluate the practical capability of DAB in asynchronous WSNs and the results corroborate our theoretical analysis.

We study the minimum latency aggregation scheduling (MLAS) problem in wireless sensor networks (WSNs) under the physical interference model combined with successive interference cancellation (SIC). Recognized as a powerful technique of multi-packet reception (MPR) at the physical layer, SIC allows a receiver to decode several arriving signals at the same time as long as these signals differ in strength significantly, resulting in increased transmission throughput and reduced latency, potentially. We first fonnulate the problem of MLAS with SIC and prove its NP-hardness. To resolve it effectively, we then propose two heuristic polynomial-time scheduling algorithms, namely first-fit aggregation scheduling (F2AS) and shortest-fit aggregation scheduling (SFAS), through fully exploiting the new transmission opportunities offered by SIC. Both algorithms are greedy ones that try to achieve maximal possible links scheduled in each time slot, thereby minimizing the total time consumed by the data aggregation task. Theoretical analysis indicates that the schedule results of F2AS and SFAS are both interference-free. Simulations show that F2AS and SFAS outperform state-of-the-art scheduling algorithms designed for MLAS under the physical interference model without SIC in tenns of latency under various network configurations. [ABSTRACT FROM AUTHOR]

Summary: In recent years, the process of the programmed cell death has gained much interest because it has important pathophysiological consequences contributing to the deletion of unwanted cells in the vessel wall, loss of pulmonary smooth muscle cells and therefore in reversing the pulmonary pressure. For the reason that most patients with pulmonary hypertension present with limited reversibility with vasodilators, antiremodeling approach for treatment appears to be feasible. Induction or enhancement of vascular smooth muscle cells apoptosis may be targeted to develop novel therapeutic approaches for pulmonary vascular remodeling in patients with pulmonary hypertension. This review summarizes the current mechanisms, investigate the roles and provide novel insights into the potential therapeutic value of apoptosis in the pulmonary artery remodeling of pulmonary hypertension. [Copyright &y& Elsevier]