3,693 research outputs found
Modified transmission and fluorescence in aperiodic and biomimetic photonic crystals
No full textComplete photonic bandgaps (PBGs) are more readily achieved in highly-symmetric photonic crystals (Ph Cs). Aperiodic crystals (quasicrystals) with arbitrarily high orientational order are promising candidates to lower the dielectric contrast necessary to open PBGs. This thesis in- vestigates the connection between the structural and optical properties of four PhC lattices by studying the effects on transmission and fluorescence spectra. In order of increasing structural isotropy these lattices are: hexagonal, Archimedean-like, Stampfli, and a biomimetic 'sunflower'. High structural isotropy is associated with weaker diffraction. The sunflower's Fourier spectrum is defined by a dense ring of weak reciprocal lattice vectors. Its local morphology, which is everywhere unique, continuously transforms between localised 4- or 6-fold symmetry. All other crystals are spatially uniform with pure point spectra. Although structurally similar to the Archimedean, the Starnpfli improves isotropy without sacrificing diffraction efficiency. TM gaps of high-contrast (~c = 8.61) rod-type PhCs are shown to be nearly independent of the lattice geometry by FDTD simulations. The primary gaps are sensitive to random rod sizes, which disrupts the coherent coupling between the individual rod resonances. Transmission spectra for TE polarisation or hole-type Ph Cs are more dependent on Bragg reflection due to weak or non-existent Mie resonances. In small samples, the TM gap is typically wider in less isotropic crystals. Much larger samples demonstrate the importance of structural isotropy and long-range interactions in low ~c PhCs. The sunflower's 21% TM gap is, to date, the widest TM PBG reported for ~c = 1. The Stampfli also supports a TE gap in the same range as its 14% TM gap, thus yielding a 4.6% absolute PBG. Further band diagram calculations on an 'approximant' of the sunflower reveal the presence of intrinsic dipolar and monopolar defect states. Microwave characterisation of rod-type samples (~c = 8.61) showed complete TM PBGs (> 60dB) with gap ratios ranging from 37.28% (hexagonal) to 25.85% (sunflower). Low-contrast samples (~c = 1.6) showed complete TM PBGs (> 30dB) with gap ratios rising from 10.37% (hexagonal) to an ambiguous value of either 10.48% or 20.95% for the sunflower due to the unusual spiral structuring of the transmission spectra. The Stampfli also supports a complete TE gap (> 10dB) that coincides with its 14.19% TM gap for a 3.55% absolute gap that, to the author's knowledge, represents the first conclusive demonstration of an absolute PBG for ~c = 1.6. A larger sunflower sample was shown to have an extremely large experimental (simulated) TM gap of 33.33% (23.16%), erroneously broadened by the non-parallel rods. A new approach to enhance the efficiency of up conversion pumping in RE-doped media is pro- posed based on PBG suppression of emission from intermediate levels. Preliminary results indi- cate that visible emission from hexagonal and sunflower PhC slabs in 0.2 wt% Er:GLSO pumped at 808nm is enhanced by up to 1.6x at 550nm, or up to 4.5x at 525nm. Subsequent analysis appears to rule out suppression of IR emission, and suggests modified thermal properties as the cause.EThOS - Electronic Theses Online ServiceGBUnited Kingdo
Low-contrast bandgaps of a planar parabolic spiral lattice
No full textWe show that a planar aperiodic lattice, mimicking the appearance of a sunflower, supports photonic bandgaps for weak dielectric contrast. The pattern’s high orientational order and spatially uniform modal pitch yields an isotropic Fourier space. A 2D structure of cylinders (ε=2) in air possesses a wide 21% TM bandgap, versus 5.6% for a sixfold lattice or 14% for a 12-fold fractal tiling. The isotropic gap frequencies imply flat bands, and thus application in nonlinear optics and low threshold lasers, where a reduced group velocity in all directions may be desired
Synthesis optimization and charge carrier transfer mechanism in LiLuSiO<sub>4</sub>:Ce, Tm storage phosphor
No full textLiLuSiO4:Ce and LiLuSiO4:Ce, Tm show very efficient charge carrier storage properties upon beta irradiation after samples have received treatment in vacuum. They outperform the commercial storage phosphor BaFBr(I):Eu2+ in many aspects. The influence of the synthesis conditions, Ce and Tm concentration, nonstoichiometry and codoping with Ca, Hf, Al and Ge are reported. Based on the results of the synthesis optimization, thermoluminescence (TL) emission and TL excitation spectra a mechanism of charge carrier transfer, storage, and recombination during irradiation and thermal or optical readout is proposed.Accepted Author ManuscriptRST/Fundamental Aspects of Materials and EnergyRST/Luminescence Material
GA Landsat 5 TM Analysis Ready Data Collection 3
No full textMaintenance and Update Frequency: asNeededStatement: This product is derived from the USGS Landsat Collection 1 archive.
The Moderate Resolution Imaging Spectroradiometer (MODIS) MCD43A1 Version 6 Bidirectional Reflectance Distribution Function and Albedo (BRDF/Albedo) Model Parameters dataset was provided by the National Aeronautics and Space Administration (NASA). It was produced daily using 16 days of Terra and Aqua MODIS data at 500 m resolution.
The ozone data was provided by Environment Canada.
The Aerosol Optical Thickness data was provided by the Commonwealth Scientific and Industrial Research Organisation (CSIRO).
The Precipitable Water for Entire Atmosphere data was provided by the National Oceanic and Atmospheric Administration (NOAA) / Earth System Research Laboratory (ESRL) / Physical Sciences Division (PSD).
The baseline Digital Surface Model (DSM) data produced from the Shuttle Radar Topography Mission (SRTM) was provided by the National Geospatial-Intelligence Agency (NGA).
Level 1 Collection 1 data was provided by the United States Geological Survey (USGS)'s Earth Resources Observation and Science (EROS) Center.<b>BACKGROUND</b><br/><p><br/><p>The United States Geological Survey's (USGS) Landsat satellite program has been capturing images of the Australian continent for more than 30 years. This data is highly useful for land and coastal mapping studies. <br/><p>In particular, the light reflected from the Earth’s surface (surface reflectance) is important for monitoring environmental resources – such as agricultural production and mining activities – over time. <br/><p>We need to make accurate comparisons of imagery acquired at different times, seasons and geographic locations. However, inconsistencies can arise due to variations in atmospheric conditions, sun position, sensor view angle, surface slope and surface aspect. These need to be reduced or removed to ensure the data is consistent and can be compared over time. <br/><p> </p><br/><b>WHAT THIS PRODUCT OFFERS</b><br/><p><br/><p>GA Landsat 5 TM Analysis Ready Data Collection 3 takes Landsat 5 Thematic Mapper (TM) imagery captured over the Australian continent and corrects for inconsistencies across land and coastal fringes. The result is accurate and standardised surface reflectance data, which is instrumental in identifying and quantifying environmental change. <br/><p><br/><p>The TM instrument is an advanced, multispectral scanning, Earth resources sensor which is designed to categorise the Earth's surface. It is particularly useful for agricultural applications and identification of land use. <br/><p><br/><p>This product is a single, cohesive Analysis Ready Data (ARD) package, which allows you to analyse surface reflectance data as is, without the need to apply additional corrections. <br/><p><br/><p>It contains three sub-products that provide corrections or attribution information:<br/><p><br/><p> 1) GA Landsat 5 TM NBAR Collection 3 <br/><p> 2) GA Landsat 5 TM NBART Collection 3<br/><p> 3) GA Landsat 5 TM OA Collection 3<br/><p><br/><p>The resolution is a 30 m grid based on the USGS Landsat Collection 1 archive
The dependence of light extraction improvement on optimized surface microstructure for AlGaN-based UVC-LEDs considering TM-polarized emission
No full textIn order to improve the light extraction of AlGaN-based short wavelength ultraviolet light emitting diodes (DUC-LEDs), a type of microstructure with high aspect ratio is introduced and optimized on the AlN substrate surface. And, particle swarm optimization (PSO) algorithm is used to inverse design of the surface microstructure to maximize the light extraction efficiency (LEE). Considering that the propagation characteristics of TM-polarized light are different from that of TE-polarized light, the optical field distribution and LEE is analyzed for the UVC-LEDs with different TE-polarized component when the optimized surface microstructure is applied. Furthermore, the preparation process tolerance of the high aspect ratio structure is discussed by calculating the LED's LEE when the structural deviation occurs or morphology changes. Simulation results show that, by using the optimized surface microstructure based on parabola cone array, the LEDs' LEE is increased from 4.4% to 8.7% and from 0.4% to 3.7% for TE-polarized and TM-polarized emission, respectively. In addition, it is demonstrated that the light extraction improvement by the surface microstructure has a good tolerance to the structural deviation and morphology. The results are significant for improving light extraction and realizing high efficient short wavelength AlGaN-based UVC-LEDs by designing surface microstructures.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.ImPhys/Esmaeil Zadeh grou
Rigor and relevance in empirical TM research: Key issues and challenges Author links open overlay panel
No full textThis paper aims to offer a critical reflection on the way Talent Management (TM) is investigated in practice, by addressing the key issues regarding the quality (in terms of rigor and relevance) of academic empirical TM research and therefore the critical scrutiny of TM scholars’ work. We will argue that despite the growth in the quantity, the quality of many empirical TM papers is lagging behind and hindering the progress of the academic field of TM. Based on a content analysis of 174 peer-reviewed articles published between 2006 and 2017, the paper outlines nine critical issues regarding the quality of the existent empirical TM research. In order to improve the positioning of the field as well as the impact of TM research on practice itis absolutely necessary for TM scholars to secure the quality of academic empirical TM research. Also, the collaboration between practitioners and scholars should increase.Peer ReviewedPostprint (author's final draft
Rigor and relevance in empirical TM research: Key issues and challenges Author links open overlay panel
No full textThis paper aims to offer a critical reflection on the way Talent Management (TM) is investigated in practice, by addressing the key issues regarding the quality (in terms of rigor and relevance) of academic empirical TM research and therefore the critical scrutiny of TM scholars’ work. We will argue that despite the growth in the quantity, the quality of many empirical TM papers is lagging behind and hindering the progress of the academic field of TM. Based on a content analysis of 174 peer-reviewed articles published between 2006 and 2017, the paper outlines nine critical issues regarding the quality of the existent empirical TM research. In order to improve the positioning of the field as well as the impact of TM research on practice itis absolutely necessary for TM scholars to secure the quality of academic empirical TM research. Also, the collaboration between practitioners and scholars should increase.Peer Reviewe
Dalla Biblioteca Comunale di Urbania: due raccolte musicali per un interprete
No full textIn the Library of Urbania (Marche, Italy) six musical manuscripts containing seventeenth century arias and cantatas are preserved. They belonged to an aristocratic family of Apecchio, (Marche), the Ubaldini. This article investigates two of them containing cantatas by Cossoni, Giovanni Bonaventura Viviani, Legrenzi Bassani and others, and in which there is the note “ex libris Antonij Barbarini”. This article reconstructs the origin of these two manuscripts, for whom the author individuated the probable owner, the singer Ippolito Fusai, by means the repertory identified in it. A thorough investigation of this hitherto little-known manuscripts may shed new light on the diffusion and transmission of music in Italy during the Seventeenth and early-Eighteenth centurie
Pneumococcal serotype-specific antibodies persist through early childhood after infant immunization: follow-up from a randomized controlled trial
No full textBACKGROUND: In a previous UK multi-center randomized study 278 children received three doses of 7-valent (PCV-7) or 13-valent (PCV-13) pneumococcal conjugate vaccine at 2, 4 and 12 months of age. At 13 months of age, most of these children had pneumococcal serotype-specific IgG concentrations ?0.35 µg/ml and opsonophagocytic assay (OPA) titers ?8.METHODS:Children who had participated in the original study were enrolled again at 3.5 years of age. Persistence of immunity following infant immunization with either PCV-7 or PCV-13 and the immune response to a PCV-13 booster at pre-school age were investigated.RESULTS: In total, 108 children were followed-up to the age of 3.5 years and received a PCV-13 booster at this age. At least 76% of children who received PCV-7 or PCV-13 in infancy retained serotype-specific IgG concentrations ?0.35 µg/ml against each of 5/7 shared serotypes. For serotypes 4 and 18C, persistence was lower at 22-42%. At least 71% of PCV-13 group participants had IgG concentrations ?0.35 µg/ml against each of 4/6 of the additional PCV-13 serotypes; for serotypes 1 and 3 this proportion was 45% and 52%. In the PCV-7 group these percentages were significantly lower for serotypes 1, 5 and 7F. A pre-school PCV-13 booster was highly immunogenic and resulted in low rates of local and systemic adverse effects.CONCLUSION: Despite some decline in antibody from 13 months of age, these data suggest that a majority of pre-school children maintain protective serotype-specific antibody concentrations following conjugate vaccination at 2, 4 and 12 months of age
Preferred Reporting Items for the Development of Evidence-based Clinical Practice Guidelines in Traditional Medicine (PRIDE-CPG-TM): Explanation and elaboration
No full textAbstractIntroductionThe development of evidence-based clinical practice guidelines (CPGs) in traditional medicine (TM) is an ongoing challenge as it is unique area. This study describes a unified platform with Preferred Reporting Items for the Development of Evidence-based CPGs in TM (PRIDE-CPG-TM), which has been successfully used by the evidence-based CPGs committee for TM.MethodsInitially we searched the literature and CPG handbooks, collected items from methodology references and drew on experiences gained from Korean medical physicians and methodology experts. A group of experts subsequently edited drafts of the items, identified one or more examples of good reporting for each item, and developed text that explained the rationale and discussed relevant evidence. Face to face meetings were held with experts to finalize the items with the most extensive elaboration.ResultsThe PRIDE-CPG-TM, in the form of a checklist and description of items with TM approach and TM examples, were designed to improve the reporting of CPG in TM and thereby facilitate their interpretation and replication. The PRIDE-CPG-TM included 5 domains and 40 items. The items pertain to the development methodology (22 items), Overview of diseases and symptoms (6 items), Recommendations (4 items), Implementation and dissemination (5 items) and others (3 items).ConclusionsThe completeness of CPG descriptions in TM is very poor. Therefore, a complete description of the recommendations for TM in CPGs is necessary for physicians to implement the recommendations in clinical practice areas. The PRIDE-CPG-TM will provide useful guidance for TM developers in the development of evidence-based CPGs
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