630 research outputs found
Measuring and modelling lung microstructure with hyperpolarised gas MRI
This thesis is concerned with the development of new techniques for measuring and modelling lung microstructure with hyperpolarised gas magnetic resonance imaging (MRI). This aim was pursued in the following five chapters:
Development of a framework for lobar comparison of lung microstructure measurements derived from computed tomography (CT) and 3He diffusion-weighted MRI evaluated in an asthmatic cohort. Statistically significant linear correlations were obtained between 3He diffusion-weighted MRI and CT lung microstructure metrics in all lobar regions.
Implementation of compressed sensing (CS) to facilitate the acquisition of 3D multiple b-value 3He diffusion-weighted MRI in a single breath-hold for whole lung morphometry mapping. Good agreement between CS-derived and fully-sampled whole lung morphometry maps demonstrates that CS undersampled 3He diffusion-weighted MRI is suitable for clinical lung imaging studies.
Acquisition of whole lung morphometry maps with 129Xe diffusion-weighted MRI and CS. An empirically-optimised 129Xe diffusion time (8.5 ms) was derived and 129Xe lung morphometry values demonstrated strong agreement with 3He equivalent measurements. This indicates that 129Xe diffusion-weighted MRI is a viable alternative to 3He for whole lung morphometry mapping.
Implementation of an in vivo comparison of the stretched exponential and cylinder theoretical gas diffusion models with both 3He and 129Xe diffusion-weighted MRI. Stretched exponential model diffusive length scale was related to cylinder model mean chord length in a non-linear power relationship; while the cylinder model mean alveolar diameter demonstrated excellent agreement with diffusive length scale.
Investigation of clinical and physiological changes in lung microstructure with 3He and 129Xe diffusion-weighted MRI. Longitudinal studies with 3He and 129Xe diffusion-weighted MRI were used investigate changes in lung microstructure in cystic fibrosis and idiopathic pulmonary fibrosis. Lung inflation mechanisms at the acinar level were also investigated with 3He and 129Xe diffusion-weighted MRI acquired at two different lung volumes
Continuous Monitoring of Distributed Data Streams over a Time-based Sliding Window
The past decade has witnessed many interesting algorithms for maintaining
statistics over a data stream. This paper initiates a theoretical study of
algorithms for monitoring distributed data streams over a time-based sliding
window (which contains a variable number of items and possibly out-of-order
items). The concern is how to minimize the communication between individual
streams and the root, while allowing the root, at any time, to be able to
report the global statistics of all streams within a given error bound. This
paper presents communication-efficient algorithms for three classical
statistics, namely, basic counting, frequent items and quantiles. The
worst-case communication cost over a window is bits for basic counting and words for the remainings, where is the number of distributed
data streams, is the total number of items in the streams that arrive or
expire in the window, and is the desired error bound. Matching
and nearly matching lower bounds are also obtained.Comment: 12 pages, to appear in the 27th International Symposium on
Theoretical Aspects of Computer Science (STACS), 201
Simulation of the control method for the adaptive front lighting system
Author name used in this publication: K. W. E. ChengAuthor name used in this publication: S. L. HoVersion of RecordPublishe
Development of electric vehicle with advanced lighting system and all electric drive
Author name used in this publication: K. W. E. ChengAuthor name used in this publication: S. L. HoVersion of RecordPublishe
EXCESSIVE TIBIAL ROTATION IS RESTORED AFTER ANATOMICAL DOUBLE BUNDLE ANTERIOR CRUCIATE LIGAMENT RECONSTRUCTION
Recent studies suggested that tibial rotaion was not restored after single bundle anterior cruciate ligament (ACL) reconstruction. This study aimed to determine if excessive tibial rotation would be restored by anatomical double bundle ACL reconstruction. Ten male subjects with unilateral ACL injury were prospectively assessed with a high demanding task before and after ACL reconstruction. Knee kinematics during pivoting movement was measured by a motion analysis system. The tibial rotation was reduced in the reconstructed knee after ACL reconstruction than the deficient knee (
The Effect of Social Fathers on the Cognitive Skills of Out-of-Wedlock Children
There are two competing views regarding the presence of social fathers on childrensā cognitive ability: either the social father provides more financial need to the children or the mother with new partners may shift the focus away from the children. Previous research focused more on such effect on older children or adolescents and ignored the self-selection problem. We use data from the Fragile Families and Child Wellbeing Study (FFCWS), and a sample of younger children. Assuming that self-selection is based on observables and using ordinary least square, propensity score matching method (nonparametric methods), we find that children with social fathers scored around three points less in a cognitive ability test than children living only with biological mothers. The result remains the same when using a control-function analysis (parametric)
Sputum elastase activity correlates with clinical parameters in steady state bronchiectasis
Conference Theme: Challenges to specialists in the 21st centurypublished_or_final_versio
A targeted gene panel that covers coding, non-coding and short tandem repeat regions improves the diagnosis of patients with neurodegenerative diseases
Genetic testing for neurodegenerative diseases (NDs) is highly challenging because of genetic heterogeneity and overlapping manifestations. Targeted-gene panels (TGPs), coupled with next-generation sequencing (NGS), can facilitate the profiling of a large repertoire of ND-related genes. Due to the technical limitations inherent in NGS and TGPs, short tandem repeat (STR) variations are often ignored. However, STR expansions are known to cause such NDs as Huntington\u27s disease and spinocerebellar ataxias type 3 (SCA3). Here, we studied the clinical utility of a custom-made TGP that targets 199 NDs and 311 ND-associated genes on 118 undiagnosed patients. At least one known or likely pathogenic variation was found in 54 patients; 27 patients demonstrated clinical profiles that matched the variants; and 16 patients whose original diagnosis were refined. A high concordance of variant calling were observed when comparing the results from TGP and whole-exome sequencing of four patients. Our in-house STR detection algorithm has reached a specificity of 0.88 and a sensitivity of 0.82 in our SCA3 cohort. This study also uncovered a trove of novel and recurrent variants that may enrich the repertoire of ND-related genetic markers. We propose that a combined comprehensive TGPs-bioinformatics pipeline can improve the clinical diagnosis of NDs
- ā¦