28 research outputs found

    Enhanced Optical Trapping

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    Optical tweezers have contributed substantially to the advancement of micro-manipulation. However, they do have restrictions, mainly the limited range of materials that yield to optical trapping. Here we propose a method of employing optically trapped objects to manipulate the surrounding fluid and thus particles freely diffusing within it. We create and investigate a reconfigurable active-feedback system of optically trapped actuators, capable of manipulating translational and rotational motion of one or more nearby free objects

    Cavity design in woodpile based 3D photonic crystals

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    In this paper, we present a design of a three-dimensional (3D) photonic crystal (PhC) nanocavity based on an optimized woodpile structure. By carefully choosing the position of the defect at the lattice center, we can create a cavity with high symmetry which supports well confined Gaussian-like cavity modes similar to those seen in a Fabry Perot laser resonator. We could also tune the resonant frequency of the cavity and manually choose the cavity mode order by adjusting the size of the defect at a chosen position

    Enhanced UV/blue fluorescent sensing using metal-dielectric-metal aperture nanoantenna arrays

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    Subwavelength aperture antenna arrays are designed and fabricated for potential applications in fluorescence sensing in the near UV/blue range. They are designed using finite-difference time-domain (FDTD) simulation, fabricated using focused ion beam etching and characterised using angular Fourier spectroscopy. The aperture arrays are formed in the top layer of an aluminum-silica-aluminum trilayer and produce a maximum simulated field intensity enhancement of 5.8 times at 406 nm and highly directive emission with a beamwidth of 8.3 deg. The normal incidence reflection response has been measured and shows reasonable agreement with modelled results. In addition, to investigate higher field intensity enhancements, bowtie aperture arrays are simulated and the influence of parameters such as dielectric gap, position of dipole source, and aperture shape and size are discussed and show enhancements up to 67 times are possible

    Evidence of near-infrared partial photonic bandgap in polymeric rod-connected diamond structures

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    We present the simulation, fabrication, and optical characterization of low-index polymeric rod-connected diamond (RCD) structures. Such complex three-dimensional photonic crystal structures are created via direct laser writing by two-photon polymerization. To our knowledge, this is the first measurement at near-infrared wavelengths, showing partial photonic bandgaps for this structure. We characterize structures in transmission and reflection using angular resolved Fourier image spectroscopy to visualize the band structure. Comparison of the numerical simulations of such structures with the experimentally measured data show good agreement for both P- and S-polarizations

    Genome-Wide Association Study in Asian Populations Identifies Variants in ETS1 and WDFY4 Associated with Systemic Lupus Erythematosus

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    Systemic lupus erythematosus is a complex and potentially fatal autoimmune disease, characterized by autoantibody production and multi-organ damage. By a genome-wide association study (320 patients and 1,500 controls) and subsequent replication altogether involving a total of 3,300 Asian SLE patients from Hong Kong, Mainland China, and Thailand, as well as 4,200 ethnically and geographically matched controls, genetic variants in ETS1 and WDFY4 were found to be associated with SLE (ETS1: rs1128334, P = 2.33×10−11, OR = 1.29; WDFY4: rs7097397, P = 8.15×10−12, OR = 1.30). ETS1 encodes for a transcription factor known to be involved in a wide range of immune functions, including Th17 cell development and terminal differentiation of B lymphocytes. SNP rs1128334 is located in the 3′-UTR of ETS1, and allelic expression analysis from peripheral blood mononuclear cells showed significantly lower expression level from the risk allele. WDFY4 is a conserved protein with unknown function, but is predominantly expressed in primary and secondary immune tissues, and rs7097397 in WDFY4 changes an arginine residue to glutamine (R1816Q) in this protein. Our study also confirmed association of the HLA locus, STAT4, TNFSF4, BLK, BANK1, IRF5, and TNFAIP3 with SLE in Asians. These new genetic findings may help us to gain a better understanding of the disease and the functions of the genes involved

    Strongly Confining Light with Air-Mode Cavities in Inverse Rod-Connected Diamond Photonic Crystals

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    Three-dimensional dielectric optical crystals with a high index show a complete photonic bandgap (PBG), blocking light propagation in all directions. We show that this bandgap can be used to trap light in low-index defect cavities, leading to strongly enhanced local fields. We compute the band structure and optimize the bandgap of an inverse 3D rod-connected diamond (RCD) structure, using the plane-wave expansion (PWE) method. Selecting a structure with wide bandgap parameters, we then add air defects at the center of one of the high-index rods of the crystal and study the resulting cavity modes by exciting them with a broadband dipole source, using the finite-difference time-domain (FDTD) method. Various defect shapes were studied and showed extremely small normalized mode volumes (Veff) with long cavity storage times (quality factor Q). For an air-filled spherical cavity of radius 0.1 unit-cell, a record small-cavity mode volume of Veff~2.2 × 10−3 cubic wavelengths was obtained with Q~3.5 × 106

    Strongly Confining Light with Air-Mode Cavities in Inverse Rod-Connected Diamond Photonic Crystals

    No full text
    Three-dimensional dielectric optical crystals with a high index show a complete photonic bandgap (PBG), blocking light propagation in all directions. We show that this bandgap can be used to trap light in low-index defect cavities, leading to strongly enhanced local fields. We compute the band structure and optimize the bandgap of an inverse 3D rod-connected diamond (RCD) structure, using the plane-wave expansion (PWE) method. Selecting a structure with wide bandgap parameters, we then add air defects at the center of one of the high-index rods of the crystal and study the resulting cavity modes by exciting them with a broadband dipole source, using the finite-difference time-domain (FDTD) method. Various defect shapes were studied and showed extremely small normalized mode volumes (Veff) with long cavity storage times (quality factor Q). For an air-filled spherical cavity of radius 0.1 unit-cell, a record small-cavity mode volume of Veff~2.2 × 10−3 cubic wavelengths was obtained with Q~3.5 × 106

    Efectos del uso de las TIC en la producción de textos argumentativos en estudiantes del 5to. de secundaria de la Institución Educativa N° 1201 Paul Harris - La Victoria - 2017

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    Universidad Nacional de Educación Enrique Guzmán y Valle. Escuela de Posgrado.TesisLa tesis “Efectos del uso de las TIC en la producción de textos argumentativos en estudiantes del 5to. de secundaria de la Institución Educativa N° 1201 Paul Harris, La Victoria, 2017”, se inició con la formulación del problema ¿Cuáles son los efectos del uso de las TIC en la producción de textos argumentativos en estudiantes del quinto de secundaria de la Institución Educativa N° 1201 Paul Harris, La Victoria, 2017? Tuvo como objetivo determinar los efectos del uso de las TIC en la producción de textos argumentativos. El enfoque fue cuantitativo. Tipo de investigación fue aplicada. El diseño fue experimental de estudio cuasi-experimental. La población de estudio fue de 200 estudiantes, la muestra 80 (40 grupo control y 40 grupo experimental). La técnica utilizada fue la observación y el instrumento lista de cotejo (pre prueba y post prueba). La validez por Juicio de expertos fue 0,86 (86%) y la confiabilidad con KR20 de Kuder-Richardosn, resultado 0,86 (pre prueba) y 0,89 (post prueba). Los resultados en la post prueba indican una diferencia de medias de más de 5 puntos a favor del grupo experimental, es decir, el promedio de notas fue significativo en todas las dimensiones de producción de textos argumentativos. La prueba U de Mann Whitney indicó un valor de significancia menor a 0,05; entonces, se rechaza la hipótesis nula y se acepta la hipótesis alternativa, es decir existe evidencia estadística para afirmar que el uso de las TIC produce efectos significativos en la producción de textos argumentativos en estudiantes del quinto de secundaria de la Institución Educativa N° 1201 Paul Harris, La Victoria, 2017
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