In an increasing range of research fields there is a strong demand of high-intensity tunable monochromatic X-ray sources. A promising new approach for the production of tunable high-intensity monochromatic beams in the hard X-ray region is the use of electron accelerators of moderate energy (10 MeV range). We developed at the 15 MeV linear electron accelerator of the Ghent University a monochro...

Monochromatic and quasi-monochromatic x-ray backlighting is a proven diagnostic technique with many important applications in Inertial Confinement Fusion and related research work. The quasi-monochromatic x-ray source can also be used in the x-ray absorption spectroscopy. A quasi-monochromatic x-ray backlighting system in the spectral range of 7.9 – 9.4 Å (1.32 1.57 keV) range has been develope...

for some constant C. We may want to colour every vertex uniformly at random. Then we will get m21−k many monochromatic edges in expectation. An improvement upon the basic method can be obtained by randomly recolouring all monochromatic edges after the first randomization. In a 1978 proof, Beck used this argument to show that m(k) ≥ Ω(k2). In 2000, Radhakrishnan and Srinivasan improved it to m(k...

The purpose of this study is to determine if cues within the blurred retinal image due to the Stiles-Crawford (SC) effect and the eye's monochromatic aberrations can drive accommodation with a small pupil (3 mm) that is typical of bright photopic conditions.The foveal, psychophysical SC function (17 min arc) and ocular monochromatic aberrations were measured in 21 visually normal adults. The re...

Let G be a graph whose edges are colored with k colors, and H=(H1,⋯,Hk) be a k-tuple of graphs. A monochromatic H-decomposition of G is a partition of the edge set of G such that each part is either a single edge or forms a monochromatic copy of Hi in color i, for some 1≤i≤k. Let φk(n,H) be the smallest number ϕ, such that, for every order-n graph and every k-edge-coloring, there is a monochrom...

Nowadays the term monochromatic and heterochromatic (or rainbow, multicolored) subgraphs of an edge colored graph appeared frequently in literature, and many results on this topic have been obtained. In this paper, we survey results on this subject. We classify the results into the following categories: vertex-partitions by monochromatic subgraphs, such as cycles, paths, trees; vertex partition...

n In this paper we investigate the behaviour of the solutions of equations ~i=t aix, = b, where ~--~=~ ai = 0 and b # 0, with respect to colorings of the set N of positive integers. It tunas out that for any b # 0 there exists an 8-coloring of N, admitting no monochromatic solution of x3 -x2 = x2 x l + b. For this equation, for b odd and 2-colorings, only an odd-even coloring prevents a monochr...

Let D be an edge-coloured digraph, V (D) will denote the set of vertices of D; a set N ⊆ V (D) is said to be a kernel by monochromatic paths of D if it satisfies the following two conditions: For every pair of different vertices u, v ∈ N there is no monochromatic directed path between them and; for every vertex x ∈ V (D) − N there is a vertex y ∈ N such that there is an xy -monochromatic direct...

Consider an arc-colored digraph. A set of vertices N is a kernel by monochromatic paths if all pairs of distinct vertices of N have no monochromatic directed path between them and if for every vertex v not in N there exists n ∈ N such that there is a monochromatic directed path from v to n. In this paper we prove different sufficient conditions which imply that an arc-colored tournament has a k...

The monochromatic aberrations present in the eyes of a group of 21 young myopic subjects and 16 young emmetropic subjects were measured along the visual axis at three levels of accommodation. The aberrations were measured using a modified aberroscope technique which makes use of a retinal camera to photograph the shadow image of the aberroscope grid on the retina, while accommodation levels of ...