Fracture of femur without evidence of severe osteoporosis rarely occurs as a result of minor external force such as a gentle passive or an active range of motion exercises. We report two cases of femoral shaft fracture occurred at the tip of heterotopic ossification of femur by a minor external force, in which the involved femur shows no evidence of remarkable osteoporosis. The possible mechani...

We present systematic and detailed measurements of interparticle contact forces inside three-dimensional piles of frictionless liquid droplets. We measured long-range chainlike correlations of the directions and magnitudes of large forces, thereby establishing the presence of force chains in three dimensions. Our correlation definition provides a chain persistence length of 10 mean droplet diam...

Vibro-acoustography is a method of imaging and measurement that uses ultrasound to produce radiation force to vibrate objects. The radiation force is concentrated laterally by focusing the ultrasound beam. The radiation force is limited in depth by intersecting two beams at different frequencies so that there is interference between the beams at the difference frequency only at their intersecti...

Abstract. A thin, flexible, one side-built-in rod under a concentrated terminal force is studied in its elastic equilibrium configuration. In order to make the problem more tractable, a proper set of state variables is chosen, facing with a second order, nonlinear, but autonomous boundary value problem, in the rotation φ(s) pertaining to each s-section. The search of the free end rotation φ0, f...

The problem treated here consists in determining the simplest statistical properties of the solution of an initial-value problem for the wave equation with a nonhomogeneous term that involves the random motion of the source. There are several physical problems for which this is an appropriate mathematical model. A simple one that serves to fix ideas concerns a stretched string, initially at res...

We obtain an inequality on a measure of the spread in time of periodic functions that are concentrated in frequency, i.e. all but a fixed finite number of Fourier coefficients vanish with meansquared error up to . We characterize an extremal function and give an asymptotic formula for the measure of spread of this extremal function as approaches 0. We also consider the corresponding problem for...

Adaptive systems research is mainly concentrated around optimizing cost functions suitable to problems. Recently, Principe et al. proposed a particle interaction model for information theoretical learning. In this paper, inspired by this idea, we propose a generalization to the particle interaction model for learning and system adaptation. In addition, for the special case of supervised multi-l...