We study a quantum point contact in a quantum spin Hall insulator. It has recently been shown that the Luttinger liquid theory of such a structure maps to the theory of a weak link in a Luttinger liquid with spin with Luttinger liquid parameters g =1 /g =g 1. We show that for weak interactions, 1 /2 g 1, the pinch-off of the point contact as a function of gate voltage is controlled by a novel q...

Compressibility measurements are performed on a quantum point contact (QPC). Screening due to mobile charges in the QPC is measured quantitatively, using a second point contact. These measurements are performed from pinch-off through the opening of the first few modes in the QPC. While the measured signal closely matches a Thomas-Fermi-Poisson prediction, deviations from the classical behavior ...

We propose a method for treating the boundary conditions at the exposed surface of semiconductor nanostructures, and compare the results from simulations based on such a method with experimental measurements on test devices defined electrostatically by metal gates on AlGaAs/GaAs heterostructures. In particular, we show that the pinch-off voltage of quantum point contacts realized with split gat...

Due to various upstream beam manipulations, the longitudinal bunch shape at the interaction point of the Stanford Linear Collider (SLC) is highly non-Gaussian. In this paper, we report beam-beam simulations with realistic longitudinal bunch shapes for the present SLC parameters and for the SLC-2000 luminosity upgrade. The simulation results allow us to estimate the luminosity enhancement due to...

The purpose of this study was to establish normative data for 6- to 19-year-olds on four tests of hand strength. The Jamar dynamometer was used to measure grip strength and a pinch gauge was used to measure tip, key, and palmar pinch. A sample of 231 males and 240 females from the seven-county Milwaukee area was tested, using standardized positioning and instructions. Results of this study indi...

BACKGROUND Grip size of a tennis racquet has been reported to influence performance, but clear evidence of a correlation has yet to be established. HYPOTHESIS Hitting force during a soft tennis forehand stroke correlates with grip size. STUDY DESIGN Controlled clinical study. METHODS A total of 40 healthy volunteers (20 men and 20 women) with a mean age of 21.9 years were enrolled. Of the...

Time-varying nonlinear oscillatory systems produce phenomena of resonance crossing and trapping of particles in resonance islands. Traditionally, such processes have been analyzed in terms of adiabatic conditions. Considering, as an example, a simplified one-dimensional model describing the "electron-cloud pinch" during a bunch passage in a particle accelerator, here we present an approach to r...

BACKGROUND Measuring grip and pinch strength is an important part of hand injury evaluation. Currently, there are no standardized values of normal grip and pinch strength among the Korean population, and lack of such data prevents objective evaluation of post-surgical recovery in strength. This study was designed to establish the normal values of grip and pinch strength among the healthy Korean...

This study was designed to establish norms of hand function, and to identify developmental characteristics of hand function among the Korean children. 712 elementary school children participated in measurement of grip strength, three kinds of pinch strength, and dexterity. The hand strength of the Korean children appeared to be weaker than that of western children. The grip strength of boys was...

The classical theorem of general projection for surfaces says that a general projection in P of a smooth complex projective surface S of P is a surface F with ordinary singularities i.e. its singular locus is either empty or is a curve γ such that (i) γ is either non singular or has at most a finite number of ordinary triple points; (ii) every smooth point of γ is either a nodal point or a pinc...