Zero-field miniature skyrmion crystal and chiral domain state in breathing-kagome antiferromagnets

The stability of a miniature skyrmion crystal (SkX) with only a small number of spins in the magnetic unit cell has been theoretically investigated in $J_1$-$J_3$ antiferromagnets on the breathing kagome lattice with a single-ion anisotropy $D$ at zero field. It is found by means of Monte Carlo simulations that due to the breathing bond-alternation, a zero-field triple-${\bf Q}$ miniature SkX can be stabilized not only in the specific case of $D=0$ [K. Aoyama and H. Kawamura, Phys. Rev. B 105, L100407 (2022)] but also in more general situations with easy-axis ($D0$) anisotropies which favor triple-${\bf Q}$ collinear and noncoplanar states, respectively. Since the SkX and anti-SkX each having positive or negative chirality are energetically degenerate, the topological Hall effect of alternative sign is possible at zero field. It is also found that reflecting the chiral degeneracy, the collinear and coplanar phases preempting the SkX phase possess random domain structures consisting of positive- and negative-chirality clusters.Comment: 5 pages, 3 figure

Generating functional analysis of CDMA detection dynamics

We investigate the detection dynamics of the parallel interference canceller (PIC) for code-division multiple-access (CDMA) multiuser detection, applied to a randomly spread, fully syncronous base-band uncoded CDMA channel model with additive white Gaussian noise (AWGN) under perfect power control in the large-system limit. It is known that the predictions of the density evolution (DE) can fairly explain the detection dynamics only in the case where the detection dynamics converge. At transients, though, the predictions of DE systematically deviate from computer simulation results. Furthermore, when the detection dynamics fail to convergence, the deviation of the predictions of DE from the results of numerical experiments becomes large. As an alternative, generating functional analysis (GFA) can take into account the effect of the Onsager reaction term exactly and does not need the Gaussian assumption of the local field. We present GFA to evaluate the detection dynamics of PIC for CDMA multiuser detection. The predictions of GFA exhibits good consistency with the computer simulation result for any condition, even if the dynamics fail to convergence.Comment: 14 pages, 3 figure

CLASSIFICATION OF FOUR DELIVERY STYLES OF PITCHING MOTON IN YOUNG BASEBALL PLAYERS

The purpose of this study was to examine the release positions of the throwing arm and of the trunk in four delivery styles (overarm, three-quarter arm, sidearm and underarm) of the baseball pitching motion, and to identify criteria to define the four delivery styles based upon the positions of both the trunk and throwing arm (upper arm) segments. Thirty-four pitching motions were videotaped using the 3D DLT method. These motions were qualitatively classified by coaches’ observation into 15 overarm, 7 three-quarter arm, 7 sidearm and 5 underarm deliveries. The angles for the trunk lateral tilt and upper arm elevation in the global coordinate system were quantified, and regression analysis revealed a linear relationship between the two angles. Criteria based on these angles were developed that matched the coaches’ observations well, demonstrating that the baseball pitching motion could be quantitatively classified into the four delivery styles

DIFFERENCES AMONG THE OVERHAND, THREE-QUARTER, SIDEARM AND UNDERHAND DELIVERY STYLES IN BASEBALL PITCHERS

The aim of the study was to clarify the biomechanical differences among the overhand (OS), three-quarter (TS), sidearm (SS) and underhand (US) styles of baseball pitching. About 700 pitches were videotaped using the 3D DLT method. The fastest pitch of each pitcher was used to establish criteria for the separation of the pitches into the four styles based on coaches’ observation and on trunk lateral tilt and upper arm elevation angles. Forty-nine pitches were selected for analysis, and classified into 18 OS, 10 TS, 10 SS and 11 US deliveries. Twenty-six kinematic and kinetic variables were calculated and analyzed. Trunk lateral tilt and upper arm elevation angles were significantly larger in the order OS-TS-SS-US. Ball velocity was significantly slower in the US group than in the other three. Significant differences were found among the groups in six kinematic and five kinetic variables. The slow ball velocity in the US group may have been causally linked to the significantly smaller forces and torques of the US group in relation to the other three

Mixing time and simulated annealing for the stochastic cellular automata

Finding a ground state of a given Hamiltonian on a graph $G=(V,E)$ is an important but hard problem. One of the potential approaches is to use a Markov chain Monte Carlo to sample the Gibbs distribution whose highest peaks correspond to the ground states. In this paper, we investigate a particular kind of stochastic cellular automata, in which all spins are updated independently and simultaneously. We prove that (i) if the temperature is fixed sufficiently high, then the mixing time is at most of order $\log|V|$, and that (ii) if the temperature drops in time $n$ as $1/\log n$, then the limiting measure is uniformly distributed over the ground states.Comment: 16 pages, 8 figure

The path-integral analysis of an associative memory model storing an infinite number of finite limit cycles

It is shown that an exact solution of the transient dynamics of an associative memory model storing an infinite number of limit cycles with l finite steps by means of the path-integral analysis. Assuming the Maxwell construction ansatz, we have succeeded in deriving the stationary state equations of the order parameters from the macroscopic recursive equations with respect to the finite-step sequence processing model which has retarded self-interactions. We have also derived the stationary state equations by means of the signal-to-noise analysis (SCSNA). The signal-to-noise analysis must assume that crosstalk noise of an input to spins obeys a Gaussian distribution. On the other hand, the path-integral method does not require such a Gaussian approximation of crosstalk noise. We have found that both the signal-to-noise analysis and the path-integral analysis give the completely same result with respect to the stationary state in the case where the dynamics is deterministic, when we assume the Maxwell construction ansatz. We have shown the dependence of storage capacity (alpha_c) on the number of patterns per one limit cycle (l). Storage capacity monotonously increases with the number of steps, and converges to alpha_c=0.269 at l ~= 10. The original properties of the finite-step sequence processing model appear as long as the number of steps of the limit cycle has order l=O(1).Comment: 24 pages, 3 figure

根未完成脱落歯に対するアペキシフィケーションを目的とした歯髄処置の経過報告

水酸化カルシウム製剤は,根未完成歯のアペキシフィケーションに用いる薬剤である.我々は,8歳の男児が転倒時に顔面を殴打し,右側上顎中切歯が完全脱臼した症例を経験した.脱臼歯は早急に整復固定したものの失活歯となり,同時に歯肉腫脹も認めたため,根管治療(アペキシフィケーション)が必要と診断された.根管内の失活歯髄を除去した後,市販の水酸化カルシウム製剤を適応した後,症状は速やかに改善した.今後約2～3年の経過観察の後,最終根管充填処置を行う必要があると考えられる.Calcium hydroxide is a suitable reagent for apexification procedures in immature permanent teeth. We report on a case of root apexification in a patient (8-yr, male) with a traumatic extrusion of the maxillary right central incisor. After temporary fixation of the traumatically extruded maxillary right central incisor, tooth necrosis and gingival swelling was observed , thus it was diagnosed to require an apexification procedure. The apexification procedure was successfully performed using calcium hydroxide following endodontic treatment. None of the calcium hydroxide -treated tooth showed any clinical or radiographic pathology. Additional follow-up time (2-3 years) is required to determine the final outcome of root canal therapy applied in cases of traumatized maxillary permanent incisor teeth with incomplete root formation