17,120 research outputs found
Local properties and statistics of phase singularities in generic wavefields
No full textThis paper is a review and extension of recent work by Berry and Dennis (Proc R Soc Lond A456, pp2059, 2000; A457, pp141-155, 2001), where the geometric structure of phase singularities (wave dislocations) in waves is studied, particularly for singularities in isotropic random wavefields. The anisotropy ellipse of a generic dislocation is defined, and I derive an angular momentum rule for its phase. Random wavefields are discussed, and statistical results for density, anisotropy ellipse eccentricity, and planar correlation functions are stated. The properties of the correlation functions are compared to analogous features from ionic structure theory, and are discussed in those terms. The results are given explicitly for four particular spectra: monochromatic waves propagating in the plane, monochromatic waves propagating in space, a speckle pattern in the transverse plane of a paraxial beam, and the Planck spectrum for blackbody radiation
Rows of optical vortices from elliptically perturbing a high-order beam
No full textAn optical vortex (phase singularity) with a high topological strength resides on the axis of a high-order light beam. The breakup of this vortex under elliptic perturbation into a straight row of unit-strength vortices is described. This behavior is studied in helical Ince-Gauss beams and astigmatic, generalized Hermite-Laguerre-Gauss beams, which are perturbations of Laguerre-Gauss beams. Approximations of these beams are derived for small perturbations, in which a neighborhood of the axis can be approximated by a polynomial in the complex plane: a Chebyshev polynomial for Ince-Gauss beams, and a Hermite polynomial for astigmatic beams
Polarization singularities in paraxial vector fields: morphology and statistics
No full textPolarization patterns in the transverse plane generically contain singularities: points of circular polarization (C points), lines of linear polarization (L lines), instantaneous zeros (disclinations) and component zeros. We investigate the geometry of ellipse fields at these singularities, using the Stokes parameters and others to characterize the singular geometry and morphology. Comparison is made with analogous structures on random surfaces, namely umbilic points and parabolic lines. The densities and correlations of the different types of polarization singularities are calculated in random polarization fields, and compared to the statistics of phase singularities and random surfaces
Mark Twain: Mysterious stranger
No full textOne hundred years after his death, the curators of this exhibition in The Rare Book & Manuscript Library, have explored the enormous holdings of the Library to assemble and present this glimpse of Mark Twain the author, publisher, erstwhile tycoon, and world-wide celebrity … and Sam Clemens the husband, the father, and the friend.not peer reviewedSubmitted by Dennis Sears ([email protected]) on 2010-06-02T16:17:26Z
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Previous issue date: 2010-04-16published or submitted for publicatio
Early Risk, Attention, and Brain Activation in Adolescents Born Preterm
No full textThe relations among early cumulative medical risk, cumulative environmental risk, attentional control, and brain activation were assessed in 15 – 16-year-old adolescents who were born preterm. Functional magnetic resonance imaging found frontal, temporal, and parietal cortex activation during an attention task with greater activation of the left superior-temporal and left supramarginal gyri associated with better performance. Individual differences in early cumulative risk are related to patterns of brain activation such that medical risk is related to left parietal cortex activation and environmental risk is related to temporal lobe activation. The findings suggest that early risk is related to less mature patterns of brain activation, including reduced efficiency of processing and responding to stimuli.This is the accepted version of the following article: Carmody, D. P., Bendersky, M., Dunn, S. M., DeMarco, J. K., Hegyi, T., Hiatt, M. and Lewis, M. (2006), Early Risk, Attention, and Brain Activation in Adolescents Born Preterm. Child Development, 77: 384–394, which has been published in final form at http://onlinelibrary.wiley.com/doi/10.1111/j.1467-8624.2006.00877.x/abstract.Peer reviewe
Local Author Book Talk: W Dennis Keating--Cleveland and the Civil War
No full textAlthough removed from the frontlines, Cleveland played an active role in national events before, during and after the Civil War. Author W. Dennis Keating, member and past president of the Cleveland Civil War Roundtable, and CSU Emeritus Professor, creates a panoramic view of the city through one of the nation’s most troubled times.
Please register at https://forms.gle/ueW83GXg7MYS61MK8
Dennis Coughlin Interview, 7 September 2012
No full textDennis Coughlin, a life-long resident of Cleveland Heights, describes what he has seen growing up in Cleveland Heights. He discusses living in the Cedar-Fairmount Neighborhood. He recalls the various shops and stores that he would go into. He also remembers his elementary school, Roxboro School, and the various events that surrounded that school such as the Davis Cup. He then describes the Coventry Neighborhood and how it has changed over the years. After Coventry, Coughlin describes St. Paul\u27s Church and Tucker Hall before he finishes with a brief description of learning to drive on Cedar Hill
Dennis Coughlin Interview, 7 September 2012
No full textDennis Coughlin, a life-long resident of Cleveland Heights, describes what he has seen growing up in Cleveland Heights. He discusses living in the Cedar-Fairmount Neighborhood. He recalls the various shops and stores that he would go into. He also remembers his elementary school, Roxboro School, and the various events that surrounded that school such as the Davis Cup. He then describes the Coventry Neighborhood and how it has changed over the years. After Coventry, Coughlin describes St. Paul\u27s Church and Tucker Hall before he finishes with a brief description of learning to drive on Cedar Hill
Dennis Alexander, Pam Alexander, Mark Bergston, and Betsey Bach
No full textDennis Alexander (Univeristy of Utah), Pam Alexander, Mark Bergston (University of Utah), and Betsey Bach (University of Montana) at the Western State Communication Association San Francisco convention A Taste of Coffee and Progress
The Gospel on the Margins: The Ideological Function of the Patristic Tradition on the Evangelist Mark
No full textIn spite of the virtually unanimous patristic opinion that the evangelist Mark was the interpreter of Peter, one of the most prestigious apostolic founding figures in Christian memory, the Gospel of Mark was mostly neglected in the patristic period. Not only is the text of Mark the least well represented of the canonical Gospels in terms of the number of patristic citations, commentaries and manuscripts, the explicit comments about the evangelist Mark reveal some ambivalence about its literary or theological value. In my survey of the reception of Mark from Papias of Hierapolis until Clement of Alexandria, I will argue that the reason why the patristic writers were hesitant to embrace the Gospel of Mark was that they perceived the text to be amenable to the Christological beliefs and social praxis of rival Christian factions. The patristic tradition about Mark may have little historical basis, but it had an important ideological function in appropriating the text in the name of an apostolic authority from the margins or periphery
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