منابع مشابه
Cosmic rulers
We derive general covariant expressions for the six independent observable modes of distortion of ideal standard rulers in a perturbed Friedmann-Robertson-Walker spacetime. Our expressions are gauge invariant and valid on the full sky. These six modes are most naturally classified in terms of their rotational properties on the sphere, yielding two scalars, two vector (spin-1), and two tensor (s...
متن کاملMolecular rulers?
What is a ‘molecular ruler’? The lengths of many linear polymers in biology are specified with remarkably accuracy, indicating they have very similar or the same numbers of subunits. Examples include bacteriophage tails, bacterial flagellum hooks, bacterial ‘injectisome’ needles, and the thin and thick filaments of striated muscles. Such exact assembly requires explanation, because the same sub...
متن کاملGolomb Rulers
The Math Factor podcast posed the problem of finding the smallest number of inch marks on a 12 inch ruler so that one could still measure any integer length from 1 to 12. One needs only four additional marks besides 0 and 12; for example 1, 4, 7, 10 works. This entertaining problem lead to others during the next few minutes (you can listen at mathfactor.uark.edu/2005/10) and inspired us to look...
متن کاملFolding Rulers inside Triangles
An l-ruler is a chain of n links, each of length l. The links, which are allowed to cross, are modelled by line segments whose endpoints act as joints. A given connguration of an l-ruler is said to fold if it can be moved to a connguration in which all its links coincide. We show that l-rulers connned inside an equilateral triangle of side 1 exhibit the following surprising alternation property...
متن کاملOn Disjoint Golomb Rulers
A set {ai | 1 ≤ i ≤ k} of non-negative integers is a Golomb ruler if differences ai − aj , for any i 6= j, are all distinct. A set of I disjoint Golomb rulers (DGR) each being a J-subset of {1, 2, · · · , n} is called an (I, J, n) − DGR. Let H(I, J) be the least positive n such that there is an (I, J, n) − DGR. In this paper, we propose a series of conjectures on the constructions and structure...
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ژورنال
عنوان ژورنال: Index on Censorship
سال: 1972
ISSN: 0306-4220,1746-6067
DOI: 10.1177/030642207200100102