PURPOSE To study the variation of cone photoreceptor packing density across the retina in healthy subjects of different ages. METHODS High-resolution adaptive optics scanning laser ophthalmoscope (AOSLO) systems were used to systematically image the retinas of two groups of subjects of different ages. Ten younger subjects (age range, 22-35 years) and 10 older subjects (age range, 50-65 years)...

T he regular tetrahedron is the simplest Platonic solid. Nevertheless, in studying its packing properties, several renowned scholars have made mistakes, and many questions about it remain unsolved. Currently no one knows the density of its densest packings, the density of its densest translative packings, or the exact value of its congruent kissing number. In this paper we recount historical de...

PURPOSE To measure the variation in human cone photoreceptor packing density across the retina, both within an individual and between individuals with different refractive errors. METHODS A high-resolution adaptive optics scanning laser ophthalmoscope was used to image the cones of 11 human eyes. Five subjects with emmetropia and six subjects with myopia were tested (+0.50 to -7.50 D). For ea...

We describe some problems, observations, and conjectures concerning thickness and packing density of knots and links in S and R. We prove the thickness of a nontrivial knot or link in S is no more than π 4 , the thickness of a Hopf link. We also give arguments and evidence supporting the conjecture that the packing density of thick links in R or S is generally less than π √ 12 , the density of ...

Finding the optimal random packing of non-spherical particles is an open problem with great significance in a broad range of scientific and engineering fields. So far, this search has been performed only empirically on a case-by-case basis, in particular, for shapes like dimers, spherocylinders and ellipsoids of revolution. Here we present a mean-field formalism to estimate the packing density ...

BACKGROUND Tight coil packing with density of at least 20%-25% is known to be important for preventing recanalization after embolization of cerebral aneurysms. However, large aneurysms sometimes recanalize regardless of the packing density, suggesting that the absolute residual volume which is determined by aneurysm volume and packing density may be more important risk factor for recanalization...