Although it is known that mechanical stress to osteoblast and periodontal ligament cells suppresses osteoclast differentiation, little is known about the direct effect of mechanical stress on osteoclast differentiation. In this study, we examined the role of mechanical stress on osteoclast differentiation using murine pre-osteoclastic RAW264.7 cells treated with receptor activator of nuclear factor-κB ligand (RANKL). RAW cells were cultured with RANKL, and mechanical stress was applied for a given period. We counted the number of osteoclast cells which were tartrate-resistant acid phosphatase (TRAP)-positive and multinucleated (2 nuclei or more), and measured mRNA by RT-PCR. There was a decrease in the number of osteoclasts under mechanical stress compared with the number under no mechanical stress. The number of nuclei per osteoclast also decreased compared to the number of nuclei per osteoclast cultured with the application of mechanical stress. As the cells were cultured for a period of 1-7 days and/or for different periods of mechanical stress application, osteoclast differentiation decreased with mechanical stress and increased after removing mechanical stress. Expression of mRNA for the osteoclast-specific genes, TRAP, matrix metalloproteinase-9, cathepsin-K and calcitonin receptor, decreased with mechanical stress and was associated with the number of osteoclasts. Inducible nitric oxide synthase mRNA which inhibits osteoclast differentiation, increased with mechanical stress. In spite of the decrease in osteoclast number with mechanical stress, nuclear factor of activated T cell cytoplasmic 1 (NFATc1) and NFATc2 mRNA expression increased with mechanical stress. These findings indicate that mechanical stress directly suppresses osteoclast differentiation and increases NFATc1 and NFATc2 suggesting delayed differentiation.

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We demonstrate physical implementation of information-theoretic secure oblivious transfer based on bounded observability using optical correlated randomness in semiconductor lasers driven by common random light broadcast over optical fibers. We demonstrate that the scheme can achieve one-out-oftwo oblivious transfer with effective key generation rate of 110 kb/s. The results show that this scheme is a promising approach to achieve information-theoretic secure oblivious transfer over long distances for future applications of secure computation such as privacy-preserving database mining, auctions and electronic-voting.With the rapid evolution of big data and cloud computing systems there is increasing interest in practical schemes for secure operations on information on large scales. One example is secure computation which would allow computation of functions over data without revealing the data [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] . Practical large scale implementations of secure computation are needed to realize applications such as private information retrieval, privacy preserving database mining, auctions, and electronic voting systems.A key component for secure computation is oblivious transfer. Oblivious transfer is message transfer in which a sender sends encoded messages in such a way that the receiver can only decode some of the messages and the sender does not know which messages were decoded. The original notion of oblivious transfer using an erasure channel was given by Rabin 16 . Later, one-out-of-two oblivious transfer was considered by Even et al. 17 . Naor and Pinkas 18, 19 gave an oblivious transfer protocol based on the Diffie-Hellman assumption, where the protocol relies on computational complexity. It has been known that the Naor-Pinkas protocol is time-consuming, and large amount of computation is required. The oblivious transfer extension technique of Ishai et al. 20 and follow up work has been aimed at achieving faster and more efficient oblivious transfer.Various schemes for oblivious transfer based on information-theoretic security have also been proposed. Information-theoretic oblivious transfer can be secure with respect to adversaries that are computationally unbounded. Moreover, information-theoretic oblivious transfer can be future proof in the sense that secrets will not be revealed by future advances in computational power. Information-theoretic schemes are based on the idea of distilling a secret bit, or string of secret bits, from a statistical advantage in correlation of bits acquired from a probabilistic system. Different models can be distinguished based on specific features of the probabilistic model of the system. Following the original notion of the erasure channel 16 , there have been schemes proposed based on noisy channels [21][22][23][24] , bounded storage 25 , wireless communication systems 26 , quantum mechanical systems [27][28][29][30] , and network behaviors 31,32 . In the noisy channel model, users observe a random sequence from a common source (such...