Alignment of the attitude of teleoperators with that of a semi-autonomous android.

Studies on social robots that can communicate with humans are increasingly important. In particular, semi-aautonomous robots have shown potential for practical applications in which robot autonomy and human teleoperation are jointly used to accomplish difficult tasks. However, it is unknown how the attitude represented in the autonomous behavior of the robots affects teleoperators. Previous studies reported that when humans play a particular role, their attitudes align with that role. The teleoperators of semi-autonomous robots also play the role given to the robots and may assimilate their autonomous expression. We hypothesized that the attitude of teleoperators may align with that of robots through teleoperation. To verify this, we conducted an experiment with conditions under which a participant operated a part of the body of an android robot that autonomously expressed a preferential attitude toward a painting and a condition under which they did not. Experimental results demonstrated that the preferential attitude of participants who teleoperated the android aligned statistically significantly more with that of the robot in comparison to those who did not teleoperate it, thereby supporting our hypothesis. This finding is novel regarding attitude change in teleoperators of semi-autonomous robots and can support the implementation of effective human-robot collaboration systems.

First-principles calculations of divalent substitution of Ca(2+) in tricalcium phosphates.

First-principles calculations were carried out to reveal local atomic arrangements and thermodynamic stability of substitutional divalent cations of Mg(2+), Zn(2+), Sr(2+) and Ba(2+) in tricalcium phosphates (TCPs). There are two modifications of α-TCP and ß-TCP, and a number of inequivalent Ca sites are present in the crystal structures. It was found that each divalent cation has energetically preferential Ca sites for substitution. For instance, Mg(2+) and Zn(2+) favor the substitution at the Ca-5 site of ß-TCP while Sr(2+) and Ba(2+) tend to occupy Ca-3 and Ca-4 in the ß-type crystal structure. The calculated site preference of these cations was in reasonable agreement with available experimental data. Moreover, it was found that these cations have negative formation energies at specific Ca sites especially in ß-TCP, indicating the stabilization of the ß phase.

The effect of chemical potential on the thermodynamic stability of carbonate ions in hydroxyapatite.

First-principles calculations were performed for CO3(2-) ions in hydroxyapatite in order to investigate the atomic structures and thermodynamic stability of CO3(2-) and its related defects. Two different chemical equilibrium conditions in high-temperature and aqueous-solution environments were considered, and atomic and ionic chemical potentials for the individual chemical equilibrium conditions were evaluated to calculate defect formation energies. It was found that A-type CO3(2-) (substituting OH(-)) is energetically more favorable than B-type CO3(2-) (substituting PO4(3-)) in the high-temperature environment, whereas B-type is preferred to A-type in the aqueous solution environment. This result successfully reproduces experimentally observed trends. In the formation of A-type and B-type CO3(2-), OH(-) vacancies or protons (interstitial or substitutional) act as charge-compensating defects.