1,362 research outputs found

    A Rhetorical Analysis of The Preaching of N. B. Hardeman

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    In a free society the sermon is a prevalent type of public speech. Its wide usage as a means of propagating ideas has been a powerful force in making and keeping this nation predominantly religious. The importance of pulpit oratory is further appreciated when viewed from a numerical standpoint. There are over 15 million sermons preached each year in the 866,000 congregations of church members in this nation

    Focusing Light through Random Photonic Media by Binary Amplitude Modulation

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    We study the focusing of light through random photonic materials using wavefront shaping. We explore a novel approach namely binary amplitude modulation. To this end, the light incident to a random photonic medium is spatially divided into a number of segments. We identify the segments that give rise to fields that are out of phase with the total field at the intended focus and assign these a zero amplitude, whereas the remaining segments maintain their original amplitude. Using 812 independently controlled segments of light, we find the intensity at the target to be 75 +/- 6 times enhanced over the average intensity behind the sample. We experimentally demonstrate focusing of light through random photonic media using both an amplitude only mode liquid crystal spatial light modulator and a MEMS-based spatial light modulator. Our use of Micro Electro-Mechanical System (MEMS)-based digital micromirror devices for the control of the incident light field opens an avenue to high speed implementations of wavefront shaping

    Foliations and Chern-Heinz inequalities

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    We extend the Chern-Heinz inequalities about mean curvature and scalar curvature of graphs of C2C^{2}-functions to leaves of transversally oriented codimension one C2C^{2}-foliations of Riemannian manifolds. That extends partially Salavessa's work on mean curvature of graphs and generalize results of Barbosa-Kenmotsu-Oshikiri \cite{barbosa-kenmotsu-Oshikiri} and Barbosa-Gomes-Silveira \cite{barbosa-gomes-silveira} about foliations of 3-dimensional Riemannian manifolds by constant mean curvature surfaces. These Chern-Heinz inequalities for foliations can be applied to prove Haymann-Makai-Osserman inequality (lower bounds of the fundamental tones of bounded open subsets Ω⊂R2\Omega \subset \mathbb{R}^{2} in terms of its inradius) for embedded tubular neighborhoods of simple curves of Rn\mathbb{R}^{n}.Comment: This paper is an improvment of an earlier paper titled On Chern-Heinz Inequalities. 8 Pages, Late

    Exploiting speckle correlations to improve the resolution of wide-field fluorescence microscopy

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    Fluorescence microscopy is indispensable in nanoscience and biological sciences. The versatility of labeling target structures with fluorescent dyes permits to visualize structure and function at a subcellular resolution with a wide field of view. Due to the diffraction limit, conventional optical microscopes are limited to resolving structures larger than 200 nm. The resolution can be enhanced by near-field and far-field super-resolution microscopy methods. Near-field methods typically have a limited field of view and far-field methods are limited by the involved conventional optics. Here, we introduce a combined high-resolution and wide-field fluorescence microscopy method that improves the resolution of a conventional optical microscope by exploiting correlations in speckle illumination through a randomly scattering high-index medium: Speckle correlation resolution enhancement (SCORE). As a test, we collect two-dimensional fluorescence images of 100-nm diameter dye-doped nanospheres. We demonstrate a deconvolved resolution of 130 nm with a field of view of 10 x 10 \text{\mu m}^2

    Learning at Highlander: A Template for Transformative Adult Education

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    This study takes a retrospective look at Highlander Research and Education Center through the eyes of several adult educators who participated, over the years, in Highlander workshops and events. Their collective experiences are summarized and analyzed and form the basis for a comparison to modern day transformative adult education

    BL Lacertae are probable sources of the observed ultra-high energy cosmic rays

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    We calculate angular correlation function between ultra-high energy cosmic rays (UHECR) observed by Yakutsk and AGASA experiments, and most powerful BL Lacertae objects. We find significant correlations which correspond to the probability of statistical fluctuation less than 10−410^{-4}, including penatly for selecting the subset of brightest BL Lacs. We conclude that some of BL Lacs are sources of the observed UHECR and present a list of most probable candidates.Comment: Replaced with the version accepted for publication in JETP Let
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