Context-aware computing is an emerging computing paradigm that can provide new or improved services by exploiting user context information. In this paper, we present a wireless-localarea-network-based (WLAN-based) indoor positioning technology. The wireless device deploys a positiondetermination model to gather location information from collected WLAN signals. A model-based signal distribution training scheme is proposed to trade off the accuracy of signal distribution and training workload. A tracking-assistant positioning algorithm is presented to employ knowledge of the area topology to assist the procedure of position determination. We have set up a positioning system at the IBM China Research Laboratory. Our experimental results indicate an accuracy of 2 m with a 90% probability for static devices and, for moving (walking) devices, an accuracy of 5 m with a 90% probability. Moreover, the complexity of the training procedure is greatly reduced compared with other positioning algorithms.

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Overlap of TCR repertoires among individuals provides the molecular basis for public T cell responses. By deep-sequencing the TCRβ repertoires of CD4+CD8+ thymocytes from three individual mice, we observed that a substantial degree of TCRβ overlap, comprising ∼10–15% of all unique amino acid sequences and ∼5–10% of all unique nucleotide sequences across any two individuals, is already present at this early stage of T cell development. The majority of TCRβ sharing between individual thymocyte repertoires could be attributed to the process of convergent recombination, with additional contributions likely arising from recombinatorial biases; the role of selection during intrathymic development was negligible. These results indicate that the process of TCR gene recombination is the major determinant of clonotype sharing between individuals.

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Multimedia proxy plays an important role in multimedia streaming over wireless Internet. Since wireless network exhibits different characteristics from the Internet, multimedia proxy caching over wireless Internet faces additional challenges. In this paper, we present a study of cache replacement for a single server and server selection for multiple servers across wireless Internet. By considering multiple objectives of multimedia proxy, we design a unified cost metric to measure proxy performance in wireless Internet. Based on the defined unified cost metric, we propose a novel replacement algorithm for single-server and a new server-selection policy for multiple servers to improve the end-to-end performance such as throughput, media quality, and start-up latency. To effectively handle errors occurred on wireless link, channel-adaptive unequal error protection is deployed according to distinct quality of service requirements of layered or scalable media. Simulation results demonstrate that our approaches achieve significantly better performance than the known cache-replacement algorithms and sever selection schemes, respectively.