Timetable of Gait Cycle Events in Parkinson's Disease.

The study used an algorithmic method to measure fluctuations in the timetable of gait cycle events in patients with Parkinson's disease (PD). Subjects with severe PD (n=10; age 63.6 ± 10.1 years; Hoehn & Yahr [H & Y] disability score 3 or 4), mild PD (n=10; age 65.5 ± 4.3; H & Y ≦ 2), and normal controls (n=10; age 65.1 ± 13.3) were studied. A camera was mounted on the trunk, and the subjects walked in a self-selected manner. Overhead images of the foot path were analyzed to geometrically describe motion in terms of displacement and velocity. The timing of three gait events, i.e.,¹⁾ feet adjacent,²⁾ maximum speed of swinging foot, and³⁾ the trunk climbing to its highest point in mid-stance, was determined for extracted steps during steady-state gait. In severe PD, 74.9 ± 21.7% of steps was timetabled so that the swinging leg and the stance-phase leg became side by side before the trunk rose to its highest point to achieve 'foot clearance'. This pattern was significantly less prevalent in mild PD and controls. An altered timetable of gait cycle events may provide quantitative indices of gait disability during steady-state walking in patients with PD

Chiral phase transition at high temperature and density in the QCD-like theory

The chiral phase transition at finite temperature T and/or chemical potential $\mu$ is studied using the QCD-like theory with a variational approach. The ``QCD-like theory'' means the improved ladder approximation with an infrared cutoff in terms of a modified running coupling. The form of Cornwall-Jackiw-Tomboulis effective potential is modified by the use of the Schwinger-Dyson equation for generally nonzero current quark mass. We then calculate the effective potential at finite T and/or $\mu$ and investigate the phase structure in the chiral limit. We have a second-order phase transition at $T_c=129$ MeV for $\mu=0$ and a first-order one at $\mu_c=422$ MeV for T=0. A tricritical point in the T-$\mu$ plane is found at T=107 MeV, $\mu=210$ MeV. The position is close to that of the random matrix model and some version of the Nambu-Jona-Lasinio model.Comment: 10 pages, 6 figures. Accepted for publication in Physical Review

Stability of color-flavor locked strangelets

The stability of color-flavor locked (CFL) strangelets is studied in the three-flavor Nambu--Jona-Lasinio model. We consider all quark flavors to be massless, for simplicity. By making use of the multiple reflection expansion, we explicitly take into account finite size effects and formulate the thermodynamic potential for CFL strangelets. We find that the CFL gap could be large enough so that the energy per baryon number of CFL strangelets is greatly affected. In addition, if the quark-quark coupling constant is larger than a certain critical value, there is a possibility of finding absolutely stable CFL strangelets.Comment: 7 pages, 3 figures, to appear in Int. J. Mod. Phys.

Finite-size effects on the chiral phase diagram of four-fermion models in four dimensions

We study the size dependence of the dynamical symmetry breaking in the four-dimensional Nambu-Jona-Lasinio model. We show that the presence of boundaries reduces the chiral breaking region, and this effect is strengthened for a larger number of compactified dimensions. A critical value for the length of the compactified dimensions exists, below which the dynamical symmetry breaking is not possible. Considering finite temperature and chemical potential, the chiral phase structure for the system with compactified dimensions is obtained. A gradual decreasing of the chiral breaking region with increasing of chemical potential is found. Also, at fixed chemical potential, the decreasing of the size of the system changes the order of the chiral phase transition.Comment: LATEX 14 pages 2 figure

Axisymmetric particle-element coupled method for deformation problems of geomaterial

Although grid-based particle methods are widely used for engineering deformation problems, due to their robustness in large deformation analyses, the computational cost of these methods is quite high compared with mesh-based methods. In 3D problems, the computational cost becomes even higher, whereas some mechanical systems can be regarded as axisymmetric, allowing them to be modeled as two-dimensional axisymmetric entities, resulting in a reduced computation cost. In order to decrease the computational cost further, arbitrary spatial discretization has been introduced to reduce the degrees of freedom in the system. The Particle-Element Coupled Method (PEM), the coupled method of the Material Point Method (MPM) and the Arbitrary Particle Domain Interpolation (APDI) method, enables a system to be discretized in arbitrary spatial resolutions. In this paper, PEM is extended to axisymmetric problems, whose formulation and applicability to geomaterial deformation are presented. Firstly, the axisymmetric MPM simulation of a granular column collapse experiment and its efficiency in computation are reported. Secondly, in the simulation of footing penetration, it is shown that the axisymmetric MPM and the axisymmetric PEM can be used to analyze large deformations that cannot be analyzed by mesh-based methods, such as the Finite Difference Method (FDM). The axisymmetric PEM yields equivalent average pressure–displacement relationships and shear strain distributions, realizing a reduction in the computation cost by half as much

Latent heat in the chiral phase transition

The chiral phase transition at finite temperature and density is discussed in the framework of the QCD-like gauge field theory. The thermodynamical potential is investigated using a variational approach. Latent heat generated in the first-order phase transition is calculated. It is found that the latent heat is enhanced near the tricritical point and is more than several hundred MeV per quark.Comment: 6 pages, 3 figure