To demonstrate that crystallographic methods can be applied to index and interpret diffraction patterns from well-ordered quasicrystals that display non-crystallographic 5-fold symmetry, we have characterized the properties of a series of periodic two-dimensional lattices built from pentagons, called Fibonacci pentilings, which resemble aperiodic Penrose tilings. The computed diffraction patter...

Planar coincidence site lattices and modules with N -fold symmetry are well understood in a formulation based on cyclotomic fields, in particular for the class number one case, where they appear as certain principal ideals in the corresponding ring of integers. We extend this approach to multiple coincidences, which apply to triple or multiple junctions. In particular, we give explicit results ...

Previously we described an algorithm that can fill a region with an infinite sequence of randomly placed and progressively smaller shapes, producing a fractal pattern. If the algorithm is appropriately modified and the region is a fundamental region for one of the 17 “wallpaper” groups, one can obtain a fractal pattern with that symmetry group. This produces artistic patterns which have a pleas...

Why do proteins proteins that encircle DNA have six-fold symmetry? One important factor may be the economy in protein mass with which DNA can be encircled by six globular subunits arranged in a ring.

Recently √ 5-refinement hierarchical sampling has been studied and √ 5-refinement has been used for surface subdivision. Compared with other refinements such as the dyadic or quincunx refinement, √ 5-refinement has a special property that the nodes in a refined lattice form groups of five nodes with these five nodes having different x and y coordinates. This special property has been shown to b...

In this paper, two fluid–structure interaction (FSI) models of the discharge valve are presented to study the effect of partly covering the discharge port by the cylinder and the roller on the effective flow and force areas. One is the full FSI model and another is the simplified FSI model in which the discharge port is not covered and the cylinder shape is simplified to be cylindrical. The pre...

The influence of the nucleon-nucleon final state interaction (FSI) on properties of the meson production amplitude near threshold is discussed. For the nucleon-nucleon interaction a simple Yamaguchi potential as well as realistic potential models are considered. It is shown that FSI effects cannot be factorized from the production amplitude. The absolute magnitude of FSI effects depends on the ...

We evaluate a number of different finite-element approaches for fluid–structure (contact) interaction problems against data from physical experiments. This consists trajectories single particles falling through highly viscous fluid and rebounding off the bottom tank wall. The resulting flow is in transitional regime between creeping turbulent flows. type configuration particularly challenging n...

INTRODUCTION Sexual violence, an HIV determinant, is an integrated behavior in the D.R.Congo. We aimed to analyze the prevalence of forced sexual intercourse (FSI) among people receiving HIV Voluntary Counseling and Testing in a hospital in Kinshasa, and its association with socio-demographics, behaviors and HIV status. METHODOLOGY Case-control study (2010-2012). Two-hundred and seventy-four ...