Internal Focusing Telescope

A focusing telescope for gamma-ray astronomy

With the development of the Laue Lens, gamma-ray astronomy is presently realizing the step that virtually all branches of astronomy have accomplished since Lippershey’s invention 400 years ago: the focusing telescope. In a Laue lens, gamma-rays interact coherently inside a crystal via Bragg-diffraction; a large number of diffraction crystals are oriented in a way to deviate incident photons ont...

Internal wave focusing by annular forcing

A linear theory is proposed for the focusing of internal waves generated by the oscillations of a horizontal annulus that is slender, namely of large aspect ratio, but otherwise arbitrary. The theory exploits the separation of scales and is applied to two configurations: a circular torus, and circular Gaussian topography at the ocean bottom. Both complete and partial annuli are considered. Focu...

Periodic Resuspension in Baltimore Canyon by Focusing of Internal Waves

High concentrations ofparticulate matter are frequently reported in submarine canyons. This study demonstrates that in Baltimore submarine canyon, elevated concentrations result from periodic resuspension events. The sloping bottom and V-shaped topography of submarine canyons could accelerate tidal flows in the canyon axis sufficiently to cause resuspension, which occurs predominantly at tidal ...

Revitalizing Internal Medicine by Focusing on the Patient-Physician Relationship

Internal magnetic focusing in an array of ballistic cavities

We study the ballistic motion of electrons in an array of submicron circular cavities, fabricated by electron beam lithography and dry etching techniques. Pronounced magnetoresistance oscillations are observed that can be understood in terms of internal magnetic focusing or commensurability between the electron trajectories and the geometry of the cavities. The depletion distance in the two-dim...