We study the self-focusing and defocusing of a light beam carrying angular momentum (called twisted light) propa- gating in a nonlinear medium. We derive a differential equation for the beam width parameter f as a function of the propagation distance, angular frequency, beam waist and intensity of the beam. The method is based on the Wentzel-Kramers-Brillouin and the paraxial approximations. An...

We examine the possibility of constraining the cosmological mean mass and dark energy densities by an application of the Alcock-Paczyński test on redshifted 21-cm maps of the epoch of reionization. The 21-cm data will be provided as a function of frequency and angular positions on the sky. The ratio of the frequency to angular distance scales can be determined by inspecting the anisotropy patte...

the angular dependent magnetoresistance oscillation (admro) of the stage-2 ibr graphiteintercalation compound (gic) was studied between 1.8 k and 110 k in magnetic fields between 1 and 9t. there was a series of peaks in the c-axis resistance as the field direction was changed from the c axisto the (001) plane. the field independence of the angular positions of the peaks, showing that theoscilla...

A method is presented for estimating the size of bearing raceway defects that are larger than the angular spacing between balls. Previous defect size estimation techniques cannot be used for such defects since they are limited to defects that are smaller than the ball angular spacing. The reason for this is that two defects that differ in size by the ball angular spacing produce the same time d...