baradaran rafii ar, md; motevasseli t, md*; yazdizadeh f, md; ansari sh, md; karimian f, md; sadoughi mm, md; kiani h ocular tissue engineering research center, shahid beheshti university of medical sciences, tehran, iran * corresponding author: [email protected] purpose: to compare anterior segment indices measured by two scheimpflug camera; galilei and pentacam. methods: in this observa...

A solution of the sourceless Einstein's equation with infinite values for the cosmological constant Λ and for the speed of light c is discussed by using Inönü–Wigner contractions of the de Sitter groups and spaces. When Λ → ∞, spacetime becomes a four–dimensional cone, dual to Minkowski space by a spacetime inversion. This inversion relates the four–cone vertex to the infinity of Minkowski spac...

PURPOSE To compare corneal thickness measurements using Pentacam (Oculus, Germany), Sirius (CSO, Italy), Galilei (Ziemer, Switzerland), and RTVue-100 OCT (Optovue Inc., USA). METHODS Sixty-six eyes of 66 healthy volunteers were enrolled. Three consecutive measurements were performed with each device. The mean value of the three measurements was used for subsequent analysis. Central corneal th...

The Landau problem in the noncommutative plane is discussed in the context of realizations of the two-fold centrally extended planar Galilei group and the anyon theory. In 2+1 dimensions, Galilei group admits a two-fold central extension [1, 2] characterized by the algebra with the nonzero Poisson bracket relations {Ki,Pj} = mδij, {Ki,Kj} = −κǫij , (1) {Ki,H} = Pi, {J ,Pi} = ǫijPj , {J ,Ki} = ǫ...

Purpose. To compare anterior corneal keratometry (K) measurements taken by a dual Scheimpflug analyzer and an auto kerato-refractometer. Methods. Sixty-four normal eyes underwent keratometric measurements with both devices. The repeatability of the auto kerato-refractometer measurements was assessed by calculating the coefficient of variation (COV). The interdevice agreement was evaluated using...

It is well known that the Galilei algebra is a sub algebra of Poincare algebra in one space dimension more. 1 This fact allows us to relate relativistic Poincare and Galilean theories. An interesting point is that Galilei transformations in two space dimensions are contained in the usual Poincare transformations? This enables us to present Poincare spin zero wavefunctions as Fourier transforms ...

The complete list of Poisson–Lie structures on 4-d Galilei group is presented.

A vector space G is introduced such that the Galilei transformations are considered linear mappings in this manifold. The covariant structure of the Galilei Group (Y. Takahashi, Fortschr. Phys. 36 (1988) 63, 36 (1988) 83) is derived and the tensor analysis is developed. It is shown that the Euclidean space is embedded the (4,1) de Sitter space through in G. This is an interesting and useful asp...