3,766 research outputs found
Organic phototransistor based on poly(3-hexylthiophene)/TiOâ nanoparticle composite
2008-2009 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe
A computer-enhanced pH study of the formaldehydeâsulphite clock reaction
The formaldehyde-sulphite clock reaction was studied using an
Orion SA 720 pH/ISE meter interfaced to an IBM PC. The
laboratory software âASYSTâ was employed to facilitate data
acquisition and data treatment. Experimental pH profiles thus
obtained for the first time were simulated by invoking a theoretical
model based on the reaction mechanism suggested by Burnett [1].
The variation of rate constants with compositions of reaction
mixtures was also discuseed in light of the empirical expression
proposed by Bell and Evans [2] for instantaneous rate constant of
the clock reaction
Highly photosensitive thin film transistors based on a composite of poly(3-hexylthiophene) and titania nanoparticles
2009-2010 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe
Fostering interest in reading and strengthening reading comprehension ability of primary school students using a childrenâs literature e-quiz bank on the cloud
Theme: Learning through Gamification: Cultivating a Love of Reading in Primary StudentsReading proficiency and frequency is directly and positively related to studentsâ academic performance. An online e-quiz bank of children literature, Reading Battle, is developed to enhance studentsâ reading comprehension ability and interest in reading. Students are invited to read from a collection of children literature then attempt quizzes on the e-quiz bank to evaluate their understanding on the texts. The quizzing process is gamified into a âchallengeâ for their peers. This article presents the projectâs implementation in a Hong Kong primary school over 2 academic years, and discusses findings on the e-quiz platformâs effectiveness. Survey and interview with students and teachers show that there is a perceived improvement in studentsâ reading comprehension ability and related grades in school assessments, and that gamification of reading books and taking comprehension quizzes has effectively fostered studentsâ interest in reading.postprin
Lyman alpha line formation in starbursting galaxies II. Extremely Thick, Dustless, and Static HI Media
The Lya line transfer in an extremely thick medium of neutral hydrogen is
investigated by adopting an accelerating scheme in our Monte Carlo code to skip
a large number of core or resonant scatterings. This scheme reduces computing
time significantly with no sacrifice in the accuracy of the results. We applied
this numerical method to the Lya transfer in a static, uniform, dustless, and
plane-parallel medium. Two types of photon sources have been considered, the
midplane source and the uniformly distributed sources. The emergent profiles
show double peaks and absorption trough at the line-center. We compared our
results with the analytic solutions derived by previous researchers, and
confirmed that both solutions are in good agreement with each other. We
investigated the directionality of the emergent Lya photons and found that limb
brightening is observed in slightly thick media while limb darkening appears in
extremely thick media. The behavior of the directionality is noted to follow
that of the Thomson scattered radiation in electron clouds, because both Lya
wing scattering and Thomson scattering share the same Rayleigh scattering phase
function. The mean number of wing scatterings just before escape is in exact
agreement with the prediction of the diffusion approximation. The Lya photons
constituting the inner part of the emergent profiles follow the relationship
derived from the diffusion approximation. We present a brief discussion on the
application of our results to the formation of Lya broad absorption troughs and
P-Cygni type Lya profiles seen in the UV spectra of starburst galaxies.Comment: 24 papges, 12 figures, The revised version submitted to Ap
N-Body Simulations of Compact Young Clusters near the Galactic Center
We investigate the dynamical evolution of compact young star clusters (CYCs)
near the Galactic center (GC) using Aarseth's Nbody6 codes. The relatively
small number of stars in the cluster (5,000-20,000) makes real-number N-body
simulations for these clusters feasible on current workstations. Using
Fokker-Planck (F-P) models, Kim, Morris, & Lee (1999) have made a survey of
cluster lifetimes for various initial conditions, and have found that clusters
with a mass <~ 2x10^4 Msun evaporate in ~10 Myr. These results were, however,
to be confirmed by N-body simulations because some extreme cluster conditions,
such as strong tidal forces and a large stellar mass range participating in the
dynamical evolution, might violate assumptions made in F-P models. Here we find
that, in most cases, the CYC lifetimes of previous F-P calculations are 5-30%
shorter than those from the present N-body simulations. The comparison of
projected number density profiles and stellar mass functions between N-body
simulations and HST/NICMOS observations by Figer et al. (1999) suggests that
the current tidal radius of the Arches cluster is ~1.0 pc, and the following
parameters for the initial conditions of that cluster: total mass of 2x10^4
Msun and mass function slope for intermediate-to-massive stars of 1.75 (the
Salpeter function has 2.35). We also find that the lower stellar mass limit,
the presence of primordial binaries, the amount of initial mass segregation,
and the choice of initial density profile (King or Plummer models) do not
significantly affect the dynamical evolution of CYCs.Comment: 20 pages including 6 figures, To appear in ApJ, Dec 20 issu
A population-based study of juvenile disc degeneration and its association with overweight and obesity, low back pain, and diminished functional status
Background: Little is known regarding juvenile disc degeneration in individuals with normal spinal alignment. Consequently, the purpose of this study was to assess the prevalence, determinants, and clinical relevance associated with juvenile disc degeneration of the lumbar spine in individuals without spinal deformities. Methods: A cross-sectional assessment of disc degeneration in juveniles was performed as part of a population-based study of 1989 Southern Chinese volunteers. Adolescents and young adults from thirteen to twenty years of age were defined as "juveniles." Juvenile subjects with no spinal deformity (n = 83) were stratified into two groups, those with and those without juvenile disc degeneration. Sagittal T2-weighted magnetic resonance images (MRI) were evaluated for the presence and extent of disc degeneration as well as other spinal findings. Demographics were assessed and clinical profiles were collected with use of standardized questionnaires. Results: Juvenile disc degeneration was present in 35% (twenty-nine) of the juveniles without spinal deformity. Disc bulging or extrusion (p < 0.001), high-intensity zones on MRI (p = 0.040), and greater weight (p < 0.001) and height (p = 0.002) were significantly more prevalent in subjects with juvenile disc degeneration. Adjusted multivariate logistic regression modeling demonstrated that Asian-modified body-mass index (BMI) values in the overweight or obese range had a significant association with juvenile disc degeneration (odds ratio = 14.19; 95% confidence interval = 1.44 to 140.40; p = 0.023). Overweight and obese individuals had greater severity of disc degeneration than underweight and normal-weight individuals (p = 0.036). Furthermore, individuals with juvenile disc degeneration had an increased prevalence of low back pain and/or sciatica (p = 0.002), greater low back pain intensity (p < 0.001), diminished social functioning (p = 0.049), and greater physical disability (p < 0.05) than individuals without disc degeneration. The p value of <0.05 for physical disability represents both the physical function (p = 0.006) and the physical component (p = 0.032) of the SF-36. Conclusions: This study demonstrated that the presence of juvenile disc degeneration was strongly associated with overweight and obesity, low back pain, increased low back pain intensity, and diminished physical and social functioning. Furthermore, an elevated BMI was significantly associated with increased severity of disc degeneration. This study has public health implications regarding overweight and obesity and the development of lumbar disc disease. Copyright © 2011 by the journal of bone and joint surgery, incorporated.published_or_final_versio
- âŠ