Constants of Motion for Constrained Hamiltonian Systems: A Particle around a Charged Rotating Black Hole

We discuss constants of motion of a particle under an external field in a curved spacetime, taking into account the Hamiltonian constraint which arises from reparametrization invariance of the particle orbit. As the necessary and sufficient condition for the existence of a constant of motion, we obtain a set of equations with a hierarchical structure, which is understood as a generalization of the Killing tensor equation. It is also a generalization of the conventional argument in that it includes the case when the conservation condition holds only on the constraint surface in the phase space. In that case, it is shown that the constant of motion is associated with a conformal Killing tensor. We apply the hierarchical equations and find constants of motion in the case of a charged particle in an electro-magnetic field in black hole spacetimes. We also demonstrate that gravitational and electro-magnetic fields exist in which a charged particle has a constant of motion associated with a conformal Killing tensor.Comment: 20 page

Implicitly and explicitly measured attitudes towards foreigners: A dual-process model perspective

Intergroup attitudes are one of the individual difference constructs which may influence motivation to learn a second language (L2) or willingness to communicate in an L2. Drawing on the APE model (a dual-process model which postulates the distinction between explicitly and implicitly measured attitudes), the current study examined 71 Japanese university students' attitudes towards foreigners by utilizing three types of attitudinal measures: self-evaluation about one's prejudice towards foreigners, verbal reports of images about foreigners, and one's implicit association scores obtained by means of the filtering unconscious matching implicit emotions (FUMIE) test. Results indicated that the participants tended to respond in a neutral way on the self-evaluation, whereas the FUMIE test indicated significantly positive attitudes towards foreigners. Further, a dissociation of implicitly and explicitly measured attitudes was found. Finally, the three measures had no significant impact on motivational intensity. The findings are discussed in terms of the dual-process model of attitudes, and implications are provided for future research on intergroup attitudes in the field ofL2 learning and communication.ArticleJABAET Journal. 14/15:39-58 (2011)journal articl

Strings in five-dimensional anti-de Sitter space with a symmetry

The equation of motion of an extended object in spacetime reduces to an ordinary differential equation in the presence of symmetry. By properly defining of the symmetry with notion of cohomogeneity, we discuss the method for classifying all these extended objects. We carry out the classification for the strings in the five-dimensional anti-de Sitter space by the effective use of the local isomorphism between \SO(4,2) and \SU(2,2). We present a general method for solving the trajectory of the Nambu-Goto string and apply to a case obtained by the classification, thereby find a new solution which has properties unique to odd-dimensional anti-de Sitter spaces. The geometry of the solution is analized and found to be a timelike helicoid-like surface

KINETIC ANALYSIS OF START MOTION ON STARTING BLOCK IN COMPETITIVE SWIMMING

The aim of this study was to investigate kinetic features of start motion with use of an instrumented starting block. This is the first study that quantified joint torques of the whole body during start motion. Six male swimmers dived from the instrumented starting block, which contains force plates and sensors. Four high-speed cameras were used to obtain kinematics data of the swimmers. Inverse dynamics calculation was carried out with use of the kinetics and kinematics data. The results showed that 1) the large pulling up forces exerted by both hands were generated by extension toques of the shoulder joints, 2) the rear side lower limb joints exerted large extension torque to obtain horizontal reaction force, and 3) the knee joint of the front side lower limb exerted large flexion torque to maintain the large vertical reaction force until 60% normalized start motion time

Object affordance as a guide for grasp-type recognition

Recognizing human grasping strategies is an important factor in robot teaching as these strategies contain the implicit knowledge necessary to perform a series of manipulations smoothly. This study analyzed the effects of object affordance-a prior distribution of grasp types for each object-on convolutional neural network (CNN)-based grasp-type recognition. To this end, we created datasets of first-person grasping-hand images labeled with grasp types and object names, and tested a recognition pipeline leveraging object affordance. We evaluated scenarios with real and illusory objects to be grasped, to consider a teaching condition in mixed reality where the lack of visual object information can make the CNN recognition challenging. The results show that object affordance guided the CNN in both scenarios, increasing the accuracy by 1) excluding unlikely grasp types from the candidates and 2) enhancing likely grasp types. In addition, the "enhancing effect" was more pronounced with high degrees of grasp-type heterogeneity. These results indicate the effectiveness of object affordance for guiding grasp-type recognition in robot teaching applications.Comment: 12 pages, 11 figures. Last updated February 27th, 202

学会抄録

<p>A. The average number of interactions decomposed by the interaction partners in 7 categories: NP, CP, MP, NCP, CMP, NCMP, and others. The full size view is shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0156455#pone.0156455.s003" target="_blank">S2 Fig</a>. B. The Venn diagram representing the interaction of NP with NCP. In total, 2,498 NP were analyzed. The NP with intra-interactions and interacting with NCP are shown by the two circles in the box. The intersection of two circles represents the shared interaction partners. Among these proteins, 1,250 NP neither intra-interact nor interact with NCP. C. The summary of interactions in terms of interaction partners. S symbols indicate that the interaction is rich (at least 0.6 interaction partners) between the protein (the left column) and the interaction partners (the top row), and the interaction partners are shared (at least 0.5) with the intra-interactions of partner proteins (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0156455#pone.0156455.s010" target="_blank">S6 Table</a>). For other symbols, see the bottom of the panel.</p