4,458 research outputs found
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
Functional role of TM poroelasticity in cochlear mechanics
No full textThesis: Ph. D., Harvard-MIT Program in Health Sciences and Technology, 2016.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Cataloged from student-submitted PDF version of thesis.Includes bibliographical references (pages 121-132).The tectorial membrane (TM) is an extracellular matrix that overlies the mechanically sensitive hair bundles of sensory receptor cells in the inner ear. Based on this strategic position, it has long been accepted that the TM plays a critical role in the stimulation of sensory hair cells. Early measurements demonstrated elastic properties of the TM and suggested that the TM is resonant. More recent measurements have shown that longitudinal coupling of the TM generates traveling waves that contribute to cochlear tuning. Here we show the importance of (1) viscosity in controlling the spread of excitation in TM traveling waves, as well as the importance of matrix porosity in determining (2) the viscosity of genetically modified TMs, and (3) local interactions with hair bundles. To understand the longitudinal spread of mechanical excitation via TM traveling waves, we develop chemical manipulations that systematically and reversibly alter TM stiffness and viscosity. Increasing TM viscosity or decreasing stiffness reduces longitudinal spread of mechanical excitation, thereby coupling a smaller range of best frequencies, which would sharpen tuning. In contrast, increasing viscous loss or decreasing stiffness would tend to broaden tuning in resonance based TM models. Thus, TM wave and resonance mechanisms are fundamentally different in the way they control frequency selectivity. To understand the molecular origin of TM viscosity, we investigate traveling waves in genetically modified TMs. We show that nanoscale pores of TectaY1870C/+ TMs are significantly larger than those of Tectb -/- TMs. The larger pore size reduces shear viscosity, thereby reducing traveling wave speed and increasing spread of excitation. These results demonstrate the previously unrecognized importance of TM porosity in cochlear tuning. To understand how TM porosity affects the local interaction between the TM and hair cells, we apply oscillatory forces to the TM with spherical probe tips. The effective stiffness of the TM is small at low frequencies where the porous matrix and surrounding fluid can move independently. By contrast, the effective stiffness of the TM is large at high frequencies, where these two phases are entrained by viscosity to move together. Interestingly, the transition frequency is in the audio frequency range only for hair bundle sized tips. Furthermore, the transition region is characterized by increased phase lead between the stimulus force and applied displacement that may play an essential role in the stability of micromechanical feedback paths and ultimately the sensitivity of hearing. In conclusion, these results show that traveling wave properties and local interactions with the hair bundles depend critically on TM porosity, thus fundamentally changing the way we think about molecular mechanisms underlying cochlear frequency selectivity and sensitivity.by Jonathan Blake Sellon.Ph. D
The effects of reducing worry in patients with persecutory delusions: study protocol for a randomized controlled trial
No full textBACKGROUND: Our approach to advancing the treatment of psychosis is to focus on key single symptoms and develop interventions that target the mechanisms that maintain them. In our theoretical research we have found worry to be an important factor in the development and maintenance of persecutory delusions. Worry brings implausible ideas to mind, keeps them there, and makes the experience distressing. Therefore the aim of the trial is to test the clinical efficacy of a cognitive-behavioral intervention for worry for patients with persecutory delusions and determine how the worry treatment might reduce delusions.METHODS: An explanatory randomized controlled trial - called the Worry Intervention Trial (WIT) - with 150 patients with persecutory delusions will be carried out. Patients will be randomized to the worry intervention in addition to standard care or to standard care. Randomization will be carried out independently, assessments carried out single-blind, and therapy competence and adherence monitored. The study population will be individuals with persecutory delusions and worry in the context of a schizophrenia spectrum diagnosis. They will not have responded adequately to previous treatment. The intervention is a six-session cognitive-behavioral treatment provided over eight weeks. The control condition will be treatment as usual, which is typically antipsychotic medication and regular appointments. The principal hypotheses are that a worry intervention will reduce levels of worry and that it will also reduce the persecutory delusions. Assessments will be carried out at 0 weeks (baseline), 8 weeks (post treatment) and 24 weeks (follow-up). The statistical analysis strategy will follow the intention-to-treat principle and involve the use of linear mixed models to evaluate and estimate the relevant between- and within-subjects effects (allowing for the possibility of missing data). Both traditional regression and newer instrumental variables analyses will examine mediation. The trial is funded by the UK Medical Research Council (MRC)/NHS National Institute of Health Research (NIHR) Efficacy and Mechanism Evaluation (EME) Programme.DISCUSSION: This will be the first large randomized controlled trial specifically focused upon persecutory delusions. The project will produce a brief, easily administered intervention that can be readily used in mental health services.Trial registration Current Controlled Trials ISRCTN23197625
Structural and Electronic Properties of Narrow Gap Zincblende and Chalcopyrite Compounds
No full textIndium compounds and corresponding epitaxially grown superlattices have provided good single crystals suitable for accurate experimental measurements and have added new interest to the study of the constituent bulk semiconductors and the II-IV-V2 chalcopyrite crystal phases. This paper reports results of structural and electronic properties of narrow gap binary and ternary semiconductors determined selfconsistently from first principles using both the full potential linearized augmented plane wave (FLAPW) and norm-conserving pseudopotentials (PP) total-energy methods
STRUCTURAL AND ELECTRONIC-PROPERTIES OF NARROW-BAND-GAP SEMICONDUCTORS - INP, INAS, AND INSB
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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
Understanding jumping to conclusions in patients with persecutory delusions: working memory and intolerance of uncertainty
No full textBackground. Persecutory delusions are a key psychotic experience. A reasoning style known as ‘jumping to conclusions’ (JTC) – limited information gathering before reaching certainty in decision making – has been identified as a contributory factor in the occurrence of delusions. The cognitive processes that underpin JTC need to be determined in order to develop effective interventions for delusions. In the current study two alternative perspectives were tested: that JTC partially results from impairment in information-processing capabilities and that JTC is a motivated strategy to avoid uncertainty.Method. A group of 123 patients with persistent persecutory delusions completed assessments of JTC (the 60:40 beads task), IQ, working memory, intolerance of uncertainty, and psychiatric symptoms. Patients showing JTC were compared with patients not showing JTC.Results. A total of 30 (24%) patients with delusions showed JTC. There were no differences between patients who did and did not jump to conclusions in overall psychopathology. Patients who jumped to conclusions had poorer working memory performance, lower IQ, lower intolerance of uncertainty and lower levels of worry.Working memory and worry independently predicted the presence of JTC.Conclusions. Hasty decision making in patients with delusions may partly arise from difficulties in keeping information in mind. Interventions for JTC are likely to benefit from addressing working memory performance, while in vivo techniques for patients with delusions will benefit from limiting the demands on working memory. The study provides little evidence for a contribution to JTC from top down motivational beliefs about uncertainty
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
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