1,741,314 research outputs found
Radiation characteristics of corner reflector antennas.
No full textPhDThis thesis presents a study of the radiation characteristics of corner reflector
antennas. The influence of the design parameters on the radiation characteristics are
assessed using an analytical method and the Finite Difference Time Domain (FDTD)
method.
The FDTD method for corner reflector antennas which are electrically small to
medium sized antennas is developed in detail. The important subject of the Absorbing
Boundary Conditions (ABCs) is studied including a study of Mur ABC and Perfectly
Matched Layers. It is shown that both methods reduce the reflections from the
boundaries sufficient so that the far-field radiation pattern can be computed
accurately.
An analytical solution to compute the far-field radiation pattern for infinite comer
reflector antennas is derived and used to understand the radiation mechanisms. Based
on those results, the FDTD method is used to conduct a parametric study on finite
sized comer reflector antennas. Experimental antennas have been built and measured
in order to verify the computational predictions. Very good agreement is reported
The novel idea of a variable beam-width comer reflector antenna is developed and
practical designs of such an antenna are presented. The principle is to design the
comer reflector antenna such that the beam-width of the antenna can be precisely
modified. Data on the gain and beam-width are presented. This has been done both by
computational and by an experimental model.
The influence on the performance of the comer reflector antenna when substituting
the solid reflector plates by rods has been investigated. The computational predictions
have been verified by measurements of an experimental antenna. Very good
agreement has been achieved.
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The possibility of modifying the shape of the comer reflector antenna is investigated.
It is shown that a modified comer reflector antenna with less depth produces the same
far-field pattern as a standard corner reflector antenna. It is also shown that the
performance of small aperture size corner reflector antennas is superior to a
cylindrical parabolic reflector antenna
James Comer - 1994 - (Riall Lecture Series)
No full textBegun in 1988, the E. Pauline Riall Lecture Series brings to the University and community outstanding national lecturers in the field of education. The series was established by the late Miss Riall, long-time principal and teacher of the former Salisbury University's Campus School. A generous bequest was provided by Miss Riall's will to fund this special program.
James Comer, Associate Dean, Yale University School of Medicinehttps://www.youtube.com/watch?v=KUvTRhhg3O
Subdiffusion in Membrane Permeation of Small Molecules
Full text linkCitation: Chipot, C. and Comer, J. Subdiffusion in Membrane Permeation of Small Molecules. Sci. Rep. 6, 35913; doi: 10.1038/srep35913 (2016).Within the solubility–diffusion model of passive membrane permeation of small molecules, translocation of the permeant across the biological membrane is traditionally assumed to obey the Smoluchowski diffusion equation, which is germane for classical diffusion on an inhomogeneous free-energy and diffusivity landscape. This equation, however, cannot accommodate subdiffusive regimes, which have long been recognized in lipid bilayer dynamics, notably in the lateral diffusion of individual lipids. Through extensive biased and unbiased molecular dynamics simulations, we show that one-dimensional translocation of methanol across a pure lipid membrane remains subdiffusive on timescales approaching typical permeation times. Analysis of permeant motion within the lipid bilayer reveals that, in the absence of a net force, the mean squared displacement depends on time as t0.7, in stark contrast with the conventional model, which assumes a strictly linear dependence. We further show that an alternate model using a fractional-derivative generalization of the Smoluchowski equation provides a rigorous framework for describing the motion of the permeant molecule on the pico- to nanosecond timescale. The observed subdiffusive behavior appears to emerge from a crossover between small-scale rattling of the permeant around its present position in the membrane and larger-scale displacements precipitated by the formation of transient voids
Making Our Way toward Teacher Education Programs in the Slavic Languages.
No full textReflecting on the state of the field of teacher training in Slavic language programs in the 1990s, the author recommends programs build alliances for teacher training with other programs in the Less Commonly Taught Languages. Beginning teachers should focus on three areas the continuing development of their own language skills, their ability to analyze classroom dynamics and implement changes in them, and expansion of their “pedagogical content knowledge.” Technology may be available to help teachers in all three of these areas
Private journal of George Comer while on the Relief Schooner George B. Cluett for the Crocker Land Expedition party at Etah, North Greenland, 1915-17
Full text link361 p. : 1 port. ; 28 cm.
Title on front free endpaper. The end date is corrected in pencil from "l6" to "17." A Crocker Land Expedition stationery letterhead and a photograph of Comer mounted on front pastedown.
"Crocker Land Expedition of the American Museum of Natural History and the American Geographical Society, 1913-1915. R" printed on cover; "-1917" added next to "1915" in ink. "C" stenciled on cover.
Caption title: Voyage of the Schooner George B. Cluett for the relief of the Crocker Land Expedition party, 1915.
Period covered: 1915 July 2-1917 Aug. 26.
"Up to October 1916, this book has been copied from the old book, because the other had been used to the finish."
Pages 319-361 blank.Journal kept by Comer during his participation in the Crocker Land Expedition relief effort. Loose material was originally laid in and has been rehoused as misscelanea. Includes: 3 typewritten letters, one to Comer from Edmund Otis Hovey, dated 19 March 1917 (1 leaf), one to MacMillan from Hovey dated 19 March 1917 (carbon copy, 2 leaves), one to Comer from MacMillan dated Mar. 23, 1917 (2 leaves); a holograph letter to Comer from Peter Freuchen dated July 27, 1917 (2 leaves); 3 holograph letters to Comer by Hovey and dated 1 April 1917 (4 half leaves), 4 April 1917 (2 p.), 27 April 1917 (1 half leaf); a list of goods handwritten by Hovey dated 2 April 1917 and signed upon receipt (Apr. 8, 1917) by Comer (1 half leaf); a map "drawn by a native, Oudy" (pencil, 1 leaf); a biography of Knud Rasmussen (mimeographed, 1 leaf); a paper entitled The II. Thule Expedition to North Greenland, by Rasmussen (mimeographed, 8 leaves); and an article entitled Exploration of northern Greenland (extracted from: The Field, Feb 5, 1916, p. 215)
An Arctic whaling diary the journal of Captain George Comer in Hudson Bay, 1903 - 1905
No full textJournal of George Comer, master of the American whaling schooner Era
Família, pessoa com síndrome de down e nutricionista: significando o ato de comer
Full text linkDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências da Saúde. Programa de Pós-Graduação em EnfermagemEste estudo buscou construir junto com algumas famílias com pessoas com Síndrome de Down (SD) uma sistematização metodológica de educação nutricional no processo de re-significação do ato de comer dessas famílias que foi identificado e compreendido durante a prática de cuidado nutricional, despertando para a importância da autonomia e da independência relativa na escolha alimentar de seus integrantes. Os postulados do Interacionismo Simbólico guiaram esta pesquisa, estabelecendo o processo de construção-desconstrução-reconstrução da realidade encontrada. Teve como metodologia, os preceitos da pesquisa qualitativa-participante que se interligaram com os instrumentos metodológicos da escuta e da observação sensível, além das atividades lúdicas. Esta pesquisa envolveu onze visitas domiciliares a cada uma das cinco famílias com pessoas com SD, durante um período de sete meses. Os resultados foram expressos por análise qualitativa. Para apresentá-los, o trabalho se estrutura em cinco capítulos por onde os aspectos teóricos, filosóficos e metodológicos sustentam as discussões e as reflexões do contexto explorado. Parte da compreensão até então divulgada sobre a SD, revisitando o arcabouço teórico e chega a uma compreensão sobre o significado do ato de comer que integra razão e emoção, imaginário e rede simbólica, onde o verbal e o não-verbal se complementaram. Categoriza elementos de interação entre o social e o individual na construção do significado do ato de comer, tais como: rotina e mídia: do social para o individual e vive-versa, o estigma de ser "diferente" e a permissividade alimentar, símbolos significantes do ato de comer para as famílias e evidenciando a sistematização metodológica de educação nutricional. Conclui que a família tem um papel fundamental como educadora nutricional para seus membros, como transmissora do primeiro significado do ato de comer, a partir de sua construção social e cultural. Evidencia que as pessoas com SD, repetem comportamentos alimentares idênticos aos de seus pais e, que estar com alteração de peso não é uma característica estigmatizante da SD. A predisposição genética para a obesidade nas pessoas com SD pode ser combatida pela compreensão mais ampla sobre o significado do ato de comer. Comprova a ação do tempo espiralesco no contexto familiar, determinando um ritmo familiar de interação entre o interno de cada pessoa e o seu entorno, presente no seu quotidiano. Um ritmo familiar que torna a prática da autonomia e da independência relativa das pessoas com SD na escolha de seus alimentos, uma realidade. Mostra que, estando a nutricionista no ambiente simbólico das famílias, ela pode contribuir com a re-significação do ato de comer, envolvendo todos os seus integrantes. A sistematização metodológica de educação nutricional deve ser específica às particularidades e necessidades de cada família
Determinants of Alanine Dipeptide Conformational Equilibria on Graphene and Hydroxylated Derivatives
Full text linkCitation: Poblete, H., Miranda-Carvajal, I., & Comer, J. (2017). Determinants of Alanine Dipeptide Conformational Equilibria on Graphene and Hydroxylated Derivatives. The Journal of Physical Chemistry B. https://doi.org/10.1021/acs.jpcb.7b01130Understanding the interaction of carbon nanomaterials with proteins is essential for determining the potential effects of these materials on health and in the design of biotechnology based on them. Here we leverage explicit-solvent molecular simulation and multidimensional free-energy calculations to investigate how adsorption to carbon nanomaterial surfaces affects the conformational equilibrium of alanine dipeptide, a widely used model of protein backbone structure. We find that the two most favorable structures of alanine dipeptide on graphene (or large carbon nanotubes) correspond to the two amide linkages lying in the same plane, flat against the surface, rather than the nonplanar ?-helix-like and ?-sheet-like conformations that predominate in aqueous solution. On graphenic surfaces, the latter conformations are metastable and most often correspond to amide?? stacking of the N-terminal amide. The calculations highlight the key role of amide?? interactions in determining the conformational equilibrium. Lesser but significant contributions from hydrogen bonding to the high density interfacial water layer or to the hydroxy groups of hydroxylated graphene also define the most favorable conformations. This work should yield insight on the influence of carbon nanotubes, graphene, and their functionalized derivatives on protein structure
Hugh Comer, Donald Comer, B. B. Comer, Mrs. J. Craig Smith and Mrs. Frank Lethrop
No full textThis is a portrait of Hugh Comer, Mrs. J. Craig Smith, Donald Comer, B. B. Comer, Jr., and Mrs. Frank Lethrop standing and sitting beside a portrait of B. B. Comer, Sr., around 1940
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