Measurements on the sensibility of Lepomis to very dim spectral lights have been made with the purpose of testing the hypothesis that the photosensitive retinal pigment, known as visual purple, is responsible for vision at low intensities of illumination. Since the pioneer morphological investigation of Schultze (1866), it has been known that the vertebrate eye usually contains two kinds of pho...

PURPOSE This study was performed to investigate the accuracies of the synthesized monochromatic images and effective atomic number maps obtained with the new GE Discovery CT750 HD CT scanner. METHODS A Gammex-RMI model 467 tissue characterization phantom and the CT number linearity section of a Phantom Laboratory Catphan 600 phantom were scanned using the dual energy (DE) feature on the GE CT...

Let S be a k-colored (finite) set of n points in R, d ≥ 3, in general position, that is, no (d+1) points of S lie in a common (d−1)-dimensional hyperplane. We count the number of empty monochromatic d-simplices determined by S, that is, simplices which have only points from one color class of S as vertices and no points of S in their interior. For 3 ≤ k ≤ d we provide a lower bound of Ω(nd−k+1+...

An edge-coloring of a connected graph is monochromatically-connecting if there is a monochromatic path joining any two vertices. How “colorful” can a monochromatically-connecting coloring be? Let mc(G) denote the maximum number of colors used in a monochromatically-connecting coloring of a graph G. We prove some nontrivial upper and lower bounds for mc(G) and relate it to other graph parameters...

A sequence of positive integers w1, w2, . . . , wn is called an ascending wave if wi+1 − wi ≥ wi − wi−1 for 2 ≤ i ≤ n − 1. For integers k, r ≥ 1, let AW (k; r) be the least positive integer such that under any r-coloring of [1, AW (k; r)] there exists a k-term monochromatic ascending wave. The existence of AW (k; r) is guaranteed by van der Waerden’s theorem on arithmetic progressions since an ...

Distortion inherent to a previously described system for acquisition of two-dimensional monochromatic spatial images is described. A solution is offered in the form of an improved instrument. The system uses a Czerny-Turner monochromator for spectral discrimination and a charge-coupled device (CCD) as the detector. A second Czerny-Turner monochromator, with identical dimensions, is added to cor...

Let l and k be positive integers, and let X = {0, 1, . . . , l}. Is it true that for every coloring δ : X × X → {0, 1, . . .} there either exist elements x0 < x1 < . . . < xl of X with δ(x0, x1) = δ(x1, x2) = . . . = δ(xl−1, xl), or else there exist elements y0 < y1 < . . . < yk of X with δ(yi−1, yi) 6= δ(yj−1, yj) for all 1 ≤ i < j ≤ k? We prove here that this is the case if either l ≤ 2, or k...