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Chondroblastoma located in the femoral head is one of the locations accounting for frequent recurrence. One of the reasons for this is the difficulty in obtaining appropriate surgical access to it for adequate removal of tumors. The authors present and illustrate a trapdoor procedure for the surgical treatment of chodroblastoma in the epiphysis of the femoral head. The surgical approach was made over the great trochanter and a trochanteric osteotomy was performed. The capsulotomy was made anteriorly and posteriorly, and the hip was dislocated anteriorly. Using a scalpel and an osteotome, the edges of a trapdoor segment were sharply dissected and the rectangular segment was lifted back to reveal an underlying subchondral tumor. The tumor tissue was thoroughly curetted and autologous cancellous bone was grafted. The trapdoor was replaced without any additional fixation, and the femoral head was reduced. The patient recovered good hip function without pain, and showed no recurrence of chondroblastoma at 5 years after surgery. The trapdoor procedure enabled sufficient access to complete curettage and autologous cancellous bone grafting for the chondroblastoma of the femoral head. This procedure proved to be a useful surgical approach for the treatment of chodroblastoma in the epiphysis of the femoral head in this case.

We numerically investigate the effects of correlation among stored patterns on the associative dynamics in a chaotic neural network model. In the model, there are two kinds of parameters: one is a measure of the Hopfield like behavior of the retrieval process and another controls the chaotic behavior. The parameter dependence of the associative dynamics is also examined. The following results are found. (i) Two dimensional parameter space is divided into two kinds of associative states by a distinct boundary. One is the retrieval state of the association such as the Hopfield like retrieval state, and another is the wandering state of the associative dynamics where the network retrieves stored patterns and their reverse patterns. (ii) The area of the wandering state becomes larger as the degree of correlation becomes larger. (iii) As the degree of correlation becomes larger, both the recall ratio of correlated patterns and the transition frequency between correlated patterns becomes larger in the wandering state. (iv) The whole region of the wandering state in the parameter space is not necessarily chaotic from the view point of the Lyapunov dimension, but most of the region of the wandering state is chaotic.

Stochastic resonance (SR) is numerically analyzed by the method of the stochastic energetics that enable us to analyze the energetics of non-equilibrium processes described by the Langevin equations. The work done by the external agent which drives the potential to fluctuate periodically is shown to be a good quantitative measure of SR. If the phase lag of the inter-well resonant motion before the periodic force is investigated, the good measure of SR can be devised by extracting the inter-well resonant motion. Thus, we numerically investigate the phase lag of the Brownian motion. The value of phase lag at the optimal noise intensity is found to depend on the frequency of the periodic force.

Stochastic resonance (SR) is numerically analyzed by the method of stochastic energetics. The work done by the external agent which drives the potential to fluctuate periodically is shown to be a good quantitative measure to detect SR. On the other hand, signal-to-noise ratio (SNR) is shown to be not a good quantitative measure of SR by comparison with the work.

The most important element process of the phase separation of binary alloys is the vacancy diffusion mechanism. A set of phenomenological dynamical equations for the vacancy-mediated phase separation is formulated from a mean-field free energy and the numerical simulation of the model is performed. From numerical results, vacancies form clusters along phase boundaries between two degenerate stable domains. The width of the vacancy-cluster across the interface grows with the logarithmic function of time. If effects of vacancy-clusters are not dominant, the dynamics is not different from that by the exchange dynamics. If the effects are dominant, the characteristic length proportional to the average domain size grows with the logarithmic function of time. The analytical approach shows that the logarithmic growth of the characteristic length is related to the growth law of the width of the vacancy-cluster.

Subtle spatial structures are often reflected on higher-order correlations. Fluctuation microscopy is a good method for detecting such spatial structures in disordered materials, because the method detects the contribution of the fourth-order density distribution function. We propose an improvement for fluctuation microscopy that increases its sensitivity to subtle spatial structures by enhancing the contributions of both the third- and the fourth-order density cumulant functions to the observable. We demonstrate numerically that the proposed method provides better detection of subtle structural changes than the original approach with improved stability against experimental noise. Although we illustrate the method in terms of transmission electron microscopy, it is not confined to this microscopy.

Dynamics of a traveling kink in the presence of a localized quenched impurity is investigated both numerically and analytically for one-dimensional system described by the Nagumo equation without the thermal noise. We find the following results. (i) The interaction between the traveling kink and the impurity is attractive. (ii) If the impurity effect is weak, the traveling kink passes through the impurity position and the phase shift of the trajectory of the kink position from that of the unperturbed motion takes a positive or negative value depending on both the impurity effect and the velocity of unperturbed motion. (iii) If the impurity effect is strong, the traveling kink is pinned by the impurity position. (iv) When the distance between the traveling kink and the impurity is large, a spiky defect is formed in the order parameter profile at the impurity position.

Dynamics of a kink in the presence of a quenched impurity is investigated both analytically and numerically by making use of the time dependent Ginzburg-Landau equation for the case of a scalar order parameter in a one-dimensional system without the thermal noise. We find the following results in our model. (i) The interaction between the kink and the impurity is attractive. (ii) When the distance between the kink and the impurity is larger than the width of the kink, the motion of the kink is described by the logarithmic function of time. This is similar to the growth law of dynamics of kinks and anti-kinks [K. Kawasaki and T. Ohta: Physica 116A (1982) 573.]. (iii) When the distance between the kink and the impurity is small, the distance decreases exponentially with time and finally the kink is pinned by the impurity. (iv) When the distance between the kink and the impurity is large, the order parameter field has the spiky defect at the impurity position.

We investigate the surface effects on the parallel critical field H c3 ( T ) and the pair function F 0 ( z ) of the superlattice with spatial variations of the BCS coupling constant and the diffusion constant. We make use of the lowest eigenvalues and eigenfunctions up to 30 to obtain the temperature dependence of the critical field. The effect of the BCS coupling constant appears significantly in our results. It is found that the positive curvature in H c3 (T) is related to the disappearance of the sub-peaks of F 0 ( z ).

We point out that Peierls substitution used by Estrera and Arnold [Phys. Rev. B 39, 2094 (1989)] leads to incorrect results for the eigenvalue to determine the angle dependence of the upper critical field.

Domain growth in a system with quenched random impurities for the conserved scalar order parameter is investigated using a cell‐dynamics method. We find that the growth rate of domains are reduced due to the pinning by impurities.

The temperature dependence of the upper critical field Hc2(T) perpendicular to the planes of the superconducting superlattice with magnetic layers is calculated. The results show that the phase difference ϕ(L) of the order parameter in one spatial period L changes from 0 to π with decreasing temperature for an appropriate set of the physical quantities. Further, we derive the analytic expression for the third-order term of the order parameter of the Ginzburg–Landau equation as the first step to study the stable state at (H,T) below Hc2(T).

Domain growth in a system with random impurities for both conserved and nonconserved order parameter is investigated by means of the cell-dynamical system (CDS) method. We find the following. (i) The characteristic length in domain growth obeys l ( t )∼(log t ) α where α is smaller than the value predicted by Huse and Henley [Phys. Rev. Lett. 55 (1985) 2708]. (ii) The exponent α seems to depend on the impurity concentration and temperature. (iii) Dynamical scaling of the structure factor is satisfied and the form of the scaling function depends on the impurity concentration.