15,990 research outputs found

    Calculation of losses in 2-D photonic crystal membrane waveguides using the 3-D FDTD method

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    Game & Watch: Are "Let's Play" Gaming Videos as Immersive as Playing Games?

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    Let's Play videos, where players record themselves playing games, are a new and popular way of experiencing game content. To investigate the experience of watching Let's Play videos, we had 40 participants watch a video of someone playing a racing game. The same participants also played the racing game and watched footage of an actual racing event. After each media experience, participants completed a modified version of the Immersive Experience Questionnaire (IEQ). Results show that IEQ scores were highest after participants played the game, and lowest after passively watching the non-gaming content; watching the Let's Play video was in between. When watching the Let's Play video, participants who were familiar with the game had lower IEQ scores than participants who were new to the game. These results show that actively controlling a game generates a deeper immersive experience than passively watching others play - watching is not as immersive as playing

    The University of Hong Kong portfolio of basic research on emerging infectious diseases

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    Fast and robust generation of city scale urban ground plan

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    Since the introduction of the concept of Digital Earth, almost every major international city has been re-constructed in the virtual world. A large volume of geometric models describing urban objects has become freely available in public domain via software like Google Earth. Although mostly created for visualization, these urban models can benefit many applications beyond visualization including video games, city scale evacuation plan, traffic simulation and earth phenomenon simulations. However, these urban models are mostly loosely structured and implicitly defined and require tedious manual preparation that usually take weeks if not months before they can be used. In this paper, we present a framework that produces well-defined ground plans from these urban models, an important step in the preparation process. Designing algorithms that can robustly and efficiently handle unstructured urban models at city scale is the main technical challenge. In this work, we show both theoretically and empirically that our method is resolution complete, efficient and numerically stable. Based on our review of the related work, we believe this is the first work that attempts to create urban ground plans automatically from 3D architectural meshes at city level. With the goal of providing greater benefit beyond visualization from this large volume of urban models, our initial results are encouraging.published_or_final_versio

    Application of a meshless method in electromagnetics

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    Author name used in this publication: S. L. HoAuthor name used in this publication: J. M. MachadoAuthor name used in this publication: H. C. Wong2001-2002 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

    Genetic Code Mutations: The Breaking of a Three Billion Year Invariance

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    The genetic code has been unchanging for some three billion years in its canonical ensemble of encoded amino acids, as indicated by the universal adoption of this ensemble by all known organisms. Code mutations beginning with the encoding of 4-fluoro-Trp by Bacillus subtilis, initially replacing and eventually displacing Trp from the ensemble, first revealed the intrinsic mutability of the code. This has since been confirmed by a spectrum of other experimental code alterations in both prokaryotes and eukaryotes. To shed light on the experimental conversion of a rigidly invariant code to a mutating code, the present study examined code mutations determining the propagation of Bacillus subtilis on Trp and 4-, 5- and 6-fluoro-tryptophans. The results obtained with the mutants with respect to cross-inhibitions between the different indole amino acids, and the growth effects of individual nutrient withdrawals rendering essential their biosynthetic pathways, suggested that oligogenic barriers comprising sensitive proteins which malfunction with amino acid analogues provide effective mechanisms for preserving the invariance of the code through immemorial time, and mutations of these barriers open up the code to continuous change

    Psychophysical effects of subtle modification of the built environment: a quasi-experimental field study

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    Background: China’s rapid urban growth is associated with an increasingly unhealthy population. Urban planners can design cities to promote healthy lifestyles, but to re-engineer the existing built environment is no simple task. We assessed whether a simple modification of the built environment was associated with altered perceptions of, and ambulation in, that environment. Methods: We adjusted a single-rail stair banister (length 3 m, height 1 m) in an urban area of Hong Kong, China, to increase or decrease the convergence angle with the stairs by 10% (plus or minus 1.91°). When positioned conventionally, the banister was parallel to the stairs (2.19 m width, 26.5° incline). 92 participants (mean age 19.71 [0.79], 54 male and 38 female) who were unaware that the banister diverged from (n=32), converged with (n=30), or was parallel to the stairs (n=30), visually estimated the angle of incline of the stairs from the top by rotating a disk to match the slant of the staircase. Walking speed (metres per second) was video-recorded surreptitiously as a sub-sample of the participants (n=36) approached the stairs with the banister in each position. Data were analysed using one-way analysis of variance followed by Bonferroni comparisons. Ethical approval of the study was obtained from the University of Hong Kong Research Ethics Committee, and participants provided written informed consent to participate. Findings: Visual estimations differed between the groups (F2,70=3.11, p=0.05, ηp2=0.08); estimates of angle were smaller when the banister converged with the stairs (32.53 [8.39]°) than when it diverged (39.69 [9.50]°) (p=0.007) or was parallel (39.88 [8.92]°) (p=0.006). Walking speeds in the final three strides preceding transition to stair descent also differed (F2,70,70=3.11, p=0.05, ηp2=0.08) with mean walking speed slower when the banister diverged (1.24 [0.26] m/s) than when it converged (1.36 [0.19] m/s) (p=0.046). Interpretation: Modification of the angle of a stair banister was associated with differences in perception of the steepness of stairs and in walking behavior during approach to the stairs. Problems associated with rapid urban development, including falls in older people and physical inactivity, are high on the health agenda of the Chinese government. Future work should examine whether stairs that appear less steep are more readily climbed, thus promoting physical activity, and whether stepping parameters are improved, thus promoting fewer falls
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