We reconstructed the electron density profile of the alamethicin-induced transmembrane pore by x-ray diffraction. We prepared fully hydrated multiple bilayers of alamethicin-lipid mixtures in a condition where pores were present, as established previously by neutron in-plane scattering in correlation with oriented circular dichroism. At dehydrated conditions, the interbilayer distance shortened...

We carry out a complete spatio-temporal characterization of the electric field of an ultrashort laser pulse after passing through a diffractive optical element composed of several binary amplitude concentric rings. Analytical expressions for the total diffraction field in the time and spectral domain are provided, using the Rayleigh-Sommerfeld formulation of the diffraction. These expressions a...

The inclusion of edge diffraction has long been recognized as an improvement to geometrical-acoustics (GA)modeling techniques, particularly for acoustic simulations of complex environments that are represented as collections of finite-sized planar surfaces. One particular benefit of combining edge diffraction with GA components is that the resulting total sound field is continuous when an acous...

Geometric Acoustics (GA) techniques based on the image-source method, ray tracing, beam tracing, and ray-frustum tracing, are widely used to compute sound propagation paths. In this paper, we highlight the connection between these propagation techniques with the research on visibility computation in computer graphics and computational geometry. We give a brief overview of visibility algorithms ...

In this paper, radio wave propagation over irregular terrain is investigated in 200–600MHz (VHF/UHF band). Measured results are compared with different path loss models such as Fresnel knife edge diffraction and uniform theory of diffraction (UTD). It is shown that, for low antenna heights, using a combination of the two-ray path loss model and knife-edge diffraction, great improvement in path ...

The aim of the present paper is to reveal the effect of motion on the scattering by an edge. To this end one considers a canonical structure formed by a perfectly conducting half-plane illuminated by a time-harmonic and uniformly moving infinitely long line source. The relevant line source is located parallel to the edge and moves with a constant velocity which is also parallel to the half-plan...

Closed-form solutions have been derived for the diffraction patterns at the focal plane of (1) a convergent wave of unit amplitude illuminating a segment of a circular aperture and (2) a convergent wave of Gaussian amplitude diffracted by an infinite edge. Photographs showing the main features of these edge transform patterns are presented together with computer-generated graphs.

Monte Carlo ray tracing programs are now being used to solve many optical analysis problems in which the entire optomechanical system must be considered. In many analyses, it is desired to consider the effects of diffraction by mechanical edges. Smoothly melding the effects of diffraction, a wave phenomenon, into a ray-tracing program is a significant technical challenge. This paper discusses t...