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In many studies, adult stem cells have been found in human periodontal ligament (PDL), but in most cases they were found in the permanent teeth. The aim of the present study was to characterize stem cells from the PDL of deciduous teeth (dPDLSCs) and compare them with those from the PDL of permanent teeth (pPDLSCs). Stem cell markers were examined by a flow cytometric analysis. The results of in vitro differentiation into adipogenic and osteogenic lineages were analyzed by histochemical staining and quantitative reverse transcription-polymerase chain reaction (RT-PCR). The results of in vivo transplantation were analyzed by histological staining, immunohistochemical staining, and quantitative RT-PCR. There were no significant differences in the proliferation rate, cell cycle distribution, expressions of stem cell markers such as Stro-1 and CD146, or in vitro differentiation. The pPDLSC transplants made more typical cementum/PDL-like tissues and expressed more cementum/PDL-related genes (CP23 and collagen XII) than did the dPDLSC transplants. Together, these results suggest that pPDLSCs are better candidates for use in reconstructing periodontium.

In this paper, we propose a joint beamforming algorithm for a multiuser wireless information and power transfer (MU-WIPT) system that is compatible with the conventional multiuser multiple input multiple output (MU-MIMO) system. The proposed joint beamforming vectors are initialized using the well established MU-MIMO zero-forcing beamforming (ZFBF) and are further updated to maximize the total harvested energy of energy harvesting (EH) users and guarantee the signal to interference plus noise ratio (SINR) constraints of the co-scheduled information decoding (ID) users. When ID and EH users are simultaneously served by joint beamforming vectors, the harvested energy can be increased at the cost of an SINR loss for ID users. To characterize the SINR loss, the target SINR ratio µ is introduced as the target SINR (i.e., SINR constraint) normalized by the received SINR achievable with ZFBF. Based on that ratio, the sum rate and harvested energy obtained from the proposed algorithm are analyzed under perfect/imperfect channel state information at the transmitter (CSIT). Through simulations and numerical results, we validate the derived analyses and demonstrate the EH and ID performance compared to both state of the art and conventional schemes.

The capacity of downlink multiple-input multipleoutput (MIMO) cellular networks is significantly limited by intercell interference (ICI), particularly at cell boundaries. Recently, two types of coordinated multiple point transmission (CoMP) technologies, joint processing and transmission (JPT) and coordinated scheduling and beamforming (CSB), were proposed. These technologies are intended for the latest cellular communication standard in order to improve the performance of cell-edge users who suffer from significant ICI. In this paper, we propose an ICI cancellation technique based on a user selection algorithm for CoMP-CSB. Under partial channel state information (CSI) and no data sharing condition, each base station (BS) concentrates more on the direction of interference to the adjacent cell's users, during the user selection process. Unlike prior concepts for a single-cell environment, in which each BS generates a precoding matrix for selected users to be served, the proposed technique considers the effects of interference to users located in adjacent cells. Although there are obvious trade-offs between ICI mitigation and the number of simultaneous scheduled users in terms of system capacity, the simulation results demonstrate that our proposed algorithm achieves higher sector throughput and is more robust against ICI if the system is limited by interference. Furthermore, through simulation we are able to obtain the preferred option for the coordination distance (R) and the number of degrees of freedom for ICI nulling ( ).Index Terms-MU-MIMO broadcast channel, SDMA, transmit beamforming, zero-forcing, coordinated multiple point transmission (CoMP), BS-cooperation.