A special challenge arises when pursuing multi-wavelength imaging of retinal tissue in vivo, because the eye's optics must be used as the main focusing elements, and they introduce significant chromatic dispersion. Here we present an image-based method to measure and correct for the eye's transverse chromatic aberrations rapidly, non-invasively, and with high precision. We validate the techniqu...

We consider solutions of hyperbolic conservation laws regularized with vanishing diffusion and dispersion terms. Following a pioneering work by Schonbek, we establish the convergence of the regularized solutions toward discontinuous solutions of the hyperbolic conservation law. The proof relies on the method of compensated compactness in the L 2 setting. Our result improves upon Schonbek's earl...

Stochastic resonance (SR) occurs when noise improves a system performance measure such as a spectral signal-to-noise ratio or a cross-correlation measure. All SR studies have assumed that the forcing noise has finite variance. Most have further assumed that the noise is Gaussian. We show that SR still occurs for the more general case of impulsive or infinite-variance noise. The SR effect fades ...

A theoretical investigation is made of the effects of dispersion in neutral gases on the formation of white-light fringes in an ideal Mach-Zehnder interferometer. It is found that the shift of the brightest fringe is determined by the change of the group refractive index at an effective mean wavelength of the white light. However, the white-light fringe technique may be used to measure changes ...

This work reports on a study of the spatially coarse-grained velocity dispersion in cosmological N-body simulations (OCDM and ΛCDM models) as a function of time (redshifts z = 0–4) and of the coarsening length (0.6–20 hMpc). The main result is the discovery of a polytropic relationship I1 ∝ ̺ between the velocity-dispersion kinetic energy density of the coarsening cells, I1, and their mass densi...

Surface waves on fluids with wavelengths in the millimeter range are known as capillary waves. Surface tension determines the propagation and dispersion of capillary waves while gravity plays a minor role. We describe a simple method for generating standing capillary waves of known frequency on water and introduce a novel noncontact technique based on laser interferometry to measure the wavelen...

We measure the first stellar velocity dispersion of the Leo A dwarf galaxy, σ = 9.3 ± 1.3 km s. We derive the velocity dispersion from the radial velocities of ten young B supergiants and two Hii regions in the central region of Leo A. We estimate a projected mass of 8 ± 2.7 × 10 M⊙ within a radius of 2, and a mass to light ratio of at least 20± 6 M⊙/L⊙. These results imply Leo A is at least ∼8...

The measurement of dispersion and its control have become important considerations in nonlinear devices based on microcavities. A sideband technique is applied here to accurately measure dispersion in a microcavity resulting from both geometrical and material contributions. Moreover, by combining the method with finite element simulations, we show that mapping of spectral lines to their corresp...

We study the dispersion of absolute price levels for US cities since 1918. By absolute price levels, we mean price indices that measure the cost of a given consumption basket at each point in time. We find strong evidence that city price levels converge over time and that the dispersion of price levels is lower for US cities than between OECD countries. We argue that price level convergence for...

We present experimental evidence showing that an interacting Bose condensate in a shaken optical lattice develops a roton-maxon excitation spectrum, a feature normally associated with superfluid helium. The roton-maxon feature originates from the double-well dispersion in the shaken lattice, and can be controlled by both the atomic interaction and the lattice modulation amplitude. We determine ...