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Cognitive radio is emerging as a promising technique to improve the utilization of the radio frequency spectrum. In this paper, we consider the problem of spectrum sharing among primary (or "licensed") users (PUs) and secondary (or "unlicensed") users (SUs). We formulate the problem based on bandwidth auction, in which each SU makes a bid for the amount of(More)
—Cognitive Radio is a promising technology to solve the problem of increasing spectrum shortage in wireless communication. It allows secondary users(SUs) to opportunistically access idle spectrum of primary users(PUs) while ensuring collision perceived by PUs under a specific requirement. Testbed is essential to advance the development of cognitive radio(More)
In this paper, we consider a scenario where multiple secondary users search for idle frequency bands in a spectrum consisting of multiple channels. The state of each channel is modeled as a discrete-time Markov process. In each time slot, one secondary user(SU) chooses one channel to sense and decides whether to use the channel based on the sensing result.(More)
The generation of functional hepatocytes is a major challenge for regenerative medicine and drug discovery. Here we show a method that facilitates generation of induced functional hepatocytes (iHeps) from adipose-derived stem cells (ADSCs) within 9 days. iHeps express hepatocytic gene programs and display functions characteristic of mature hepatocytes,(More)
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