Confocal microscopic analysis of optical crosstalk in GaN micro-pixel light-emitting diodes

© 2015 AIP Publishing LLC. The optical crosstalk phenomenon in GaN micro-pixel light-emitting diodes (LED) has been investigated by confocal microscopy. Depth-resolved confocal emission images indicate light channeling along the GaN and sapphire layers as the source of crosstalk. Thin-film micro-pixel devices are proposed, whereby the light-trapping sapphire layers are removed by laser lift-off. Optical crosstalk is significantly reduced but not eliminated due to the remaining GaN layer. Another design involving micro-pixels which are completely isolated is further proposed; such devices exhibited low-noise and enhanced optical performances, which are important attributes for high-density micro-pixel LED applications including micro-displays and multi-channel optical communications.published_or_final_versio

Understanding the Development of Problematic Use of Massively Multiplayer Online Game

Online gaming has become one of the most popular forms of online leisure activity today. Massively multiplayer online game (MMOG), being highly persistent and immersive, is however often presented as being potentially dangerous of leading to problematic use. Despite a rising concern over this emerging societal challenge, the theoretical understanding of problematic use of MMOG is lacking in the information systems literature. Therefore, the objective of this study is to propose and empirically test a theory-guided model that explains the development of problematic use of MMOG. We built our research model on the hedonic management model of addictions, and explained the role of mood modification and deficient self-regulation in the development of problematic use of MMOG. We will validate the research model using longitudinal survey design and structural equation modeling approach. We believe that the current work presents significant implications to both research and practice

The Excessive Use of Massively Multiplayer Online Games: A Theoretical Investigation

Online gaming has become one of the most popular forms of Internet applications and online entertainments today, and has reshaped the ways people communicate and interact. Massively multiplayer online games (MMOGs), being highly challenging, interactive, immersive and persistent, are however often presented as being potentially dangerous of leading gamers to play excessively. Despite a rising concern over this emerging global issue, the theoretical understanding of the excessive use of MMOGs is lacking in the IS literature. Therefore, the main objective of this study is to propose a research model to theoretically explain the development of excessive use of MMOGs. We tested our research model in longitudinal design using an online survey with 602 active MMOGs users. Our results suggested that mood regulation derived from using MMOGs predicts the excessive use. Motivations for playing MMOGs, achievement and immersion, are found important in determining mood regulation. This study provides a theoretical explanation of excessive use of MMOGs, and the results help researchers and practitioners understand the main drivers and mechanisms of the development of excessive use of MMOGs

Technology-Mediated Self-Regulation: An Implication for Preventing Online Gaming Addiction

Self-regulation has assumed an important role in online gaming addiction. Although the role of self-regulation has received increasing scholarly attention in the past decade, research on self-regulation remains new in the information systems literature. There is also a lack of understanding of how technological design features can enhance one’s self-regulation and thus prevent online gaming addiction. Therefore, we attempt to bridge these research gaps by identifying technological design features that can enhance one’s self-regulation in online gaming, as well as by developing a research model to explain how technological design features influence one’s online gaming addiction through the self-regulatory mechanisms. In this research-in-progress paper, we present our research model and hypotheses and describe our research design. We expect that this study contributes to our understanding of the intervention and prevention in the domain of technology addiction

Search for the intermediate Mass Higgs Signal at TeV eγe\gamma colliders

The intermediate mass Higgs (IMH) can be abundantly produced through the process $e^-\gamma \rightarrow W^-H\nu$ at TeV $e^-\gamma$ colliders, which are realized by the laser back-scattering method. We search for the signature of $W^-H \rightarrow (jj)(b\bar b)$ plus missing transverse momentum, with and without considering the $b$-tagging. We also analyse all the potential backgrounds from $e^-\gamma \rightarrow W^-Z\nu,\,W^-W^+e^-,\,ZZe^-,\, \bar t b\nu$ and $t\bar t e^-$. With our selective acceptance cuts these backgrounds are reduced to a manageable level. We find that for the entire intermediate mass range 60 -- 150~GeV the Higgs discovery should be viable. We also present detail formulas for the helicity amplitudes of these processes.Comment: Latex(Revtex), 30 pages, 8 figures in postscript format (uuencoded), NUHEP-TH-93-

Laser surface colouring of titanium for contemporary jewellery

This paper describes work which emerged through a need to understand more about the potential of laser surface engineering for use in the creative industries. The method of creation of contemporary jewellery pieces and the resultant 'Ocular' jewellery series are described from the creative point of view. The work demonstrates how laser controlled oxide growth on Ti–6Al–4V alloy under ambient conditions can be used as an artistic tool by producing precisely defined colours. Use of the method to produce regular areas of even colour and to reproduce freehand drawings on a titanium alloy surface is described. Analysis highlights interference as the main colouring mechanism and suggests a graded surface layer, progressing from an outer layer of TiO2 to lower layers rich in TiO and Ti2O. The model of research by practice presented in this paper offers a contribution to the current debate on partnerships between art and science and engineering

Hadronic Production of S-wave and P-wave Charmed Beauty Mesons via Heavy Quark Fragmentation

At hadron colliders the dominant production mechanism of $(\bar bc)$ mesons with large transverse momentum is due to parton fragmentation. We compute the rates and transverse momentum spectra for production of S-wave and P-wave $(\bar b c)$ mesons at the Tevatron via the direct fragmentation of the bottom antiquark as well as the Altarelli-Parisi induced gluon fragmentation. Since all the radially and orbitally excited $(\bar b c)$ mesons below the $BD$ flavor threshold will cascade into the pseudoscalar ground state $B_c$ through electromagnetic and/or hadronic transitions, they all contribute to the inclusive production of $B_c$. The contributions of the excited S-wave and P-wave states to the inclusive production of $B_c$ are 58 and 23\%, respectively, and hence significant.Comment: Changes are made in the Discussio

Combustion of LOX with H2(sub g) under subcritical, critical, and supercritical conditions (Task 1) and experimental observation of dense spray and mixing of impinging jets (Task 2)

The objective was to achieve a better understanding of the combustion processes of liquid oxygen and gaseous hydrogen under broad range of pressure covering subcritical, critical, and supercritical conditions. The scope of the experimental work falls into the following areas: (1) design of the overall experimental setup; (2) modification of an existing windowed high pressure chamber; (3) design of the LOX feeding system; (4) provision of the safety features in the test rig design; (5) LOX cleanliness requirements; (6) cold shock testing; (7) implementation of data acquisition systems; (8) preliminary tests for system checkout; (9) modification of LOX feeding system; and (10) evaporation tests. Progress in each area is discussed