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Jason Leung

Publications and source records attributed to Jason Leung.

6 recordsLinked to original sources
arXiv2022

Weak lensing in the blue: a counter-intuitive strategy for stratospheric observations

The statistical power of weak lensing measurements is principally driven by the number of high redshift galaxies whose shapes are resolved. Conventional wisdom and physical intuition suggest this is optimised by deep imaging at long (red or near IR) wavelengths, to avoid losing redshifted Balmer break and Lyman break galaxies. We use the synthetic Emission Line EL-COSMOS catalogue to simulate lensing observations using different filters, from various altitudes. Here were predict the number of exposures to achieve a target z > 0.3 source density, using off-the-shelf and custom filters. Ground-based observations are easily better at red wavelengths, as (more narrowly) are space-based observations. However, we find that SuperBIT, a diffraction-limited observatory operating in the stratosphere, should instead perform its lensing-quality observations at blue wavelengths.

astro-ph.IM↗
arXiv2021

EmoconLite: Bridging the Gap Between Emotiv and Play for Children With Severe Disabilities

Brain-computer interfaces (BCIs) allow users to control computer applications by modulating their brain activity. Since BCIs rely solely on brain activity, they have enormous potential as an alternative access method for engaging children with severe disabilities and/or medical complexities in therapeutic recreation and leisure. In particular, one commercially available BCI platform is the Emotiv EPOC headset, which is a portable and affordable electroencephalography (EEG) device. Combined with the EmotivBCI software, the Emotiv system can generate a model to discern between different mental tasks based on the user's EEG signals in real-time. While the Emotiv system shows promise for use by the pediatric population in the setting of a BCI clinic, it lacks integrated support that allows users to directly control computer applications using the generated classification output. To achieve this, users would have to create their own program, which can be challenging for those who may not be technologically inclined. To address this gap, we developed a freely available and user-friendly BCI software application called EmoconLite. Using the classification output from EmotivBCI, EmoconLite allows users to play YouTube video clips and a variety of video games from multiple platforms, ultimately creating an end-to-end solution for users. Through its deployment in the Holland Bloorview Kids Rehabilitation Hospital's BCI clinic, EmoconLite is bridging the gap between research and clinical practice, providing children with access to BCI technology and supporting BCI-enabled play.

cs.HC↗
arXiv2020

Integrated Wishart bridge processes and generalised Hartman-Watson law

This article is concerned with the joint law of an integrated Wishart bridge process and the trace of an integrated inverse Wishart bridge process over the interval $ \left[0,t\right] $. Its Laplace transform is obtained by studying the Wishart bridge processes and the absolute continuity property of Wishart laws.

math.PR↗
arXiv2016

Lumbar degenerative spondylolisthesis epidemiology: a systemic review with a focus on gender-specific and age-specific prevalence

The epidemiology of lumbar degenerative spondylolisthesis (DS) remains controversial. We performed a systemic review with the aim to have a better understanding of DS's prevalence in general population. The results showed the prevalence of DS is very gender specific and age specific. Both women and men have few DS before 50 years old, after 50 years old both women and men start to develop DS, with women having a faster developing rate than men. For elderly Chinese (>=65 yrs, mean age: 72.5 yrs), large population based studies (MsOS(Hong Kong) and MrOS (Hong Kong), females n=2000 and males n=2000) showed DS prevalence was for 25.0% for women and 19.1% for men, and the prevalence F:M (women:men) ratio was 1.3:1. The published data (MsOS(USA) and MrOS(USA) studies) seem to show elderly Caucasian American has a higher DS prevalence, being approximately 60-70% higher than elderly Chinese; however the prevalence F:M ratio was similar to elderly Chinese population. Patient data showed female patients more often received treatment than men; and preliminary data show the ratio of numbers of female patients received treatment compared with men did not differ between Northeast Asians (Chinese, Japanese, and Korean) and European and American Caucasians, being around 2:1 in elderly population. The existing data also suggest that menopause may be a contributing factor for the accelerated DS development in post-menopausal

q-bio.TO↗
arXiv2016

Non-contact hemodynamic imaging reveals the jugular venous pulse waveform

Cardiovascular monitoring is important to prevent diseases from progressing. The jugular venous pulse (JVP) waveform offers important clinical information about cardiac health, but is not routinely examined due to its invasive catheterisation procedure. Here, we demonstrate for the first time that the JVP can be consistently observed in a non-contact manner using a novel light-based photoplethysmographic imaging system, coded hemodynamic imaging (CHI). While traditional monitoring methods measure the JVP at a single location, CHI's wide-field imaging capabilities were able to observe the jugular venous pulse's spatial flow profile for the first time. The important inflection points in the JVP were observed, meaning that cardiac abnormalities can be assessed through JVP distortions. CHI provides a new way to assess cardiac health through non-contact light-based JVP monitoring, and can be used in non-surgical environments for cardiac assessment.

physics.med-ph↗