Texture-based palmprint retrieval using a layered search scheme for personal identification

2005-2006 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

A public mesh watermarking algorithm based on addition property of Fourier transform

Author name used in this publication: David ZhangCenter for Multimedia Signal Processing and Department of ComputingVersion of RecordPublishe

Disruption of the blood-testis barrier integrity by bisphenol A in vitro: Is this a suitable model for studying blood-testis barrier dynamics?

Bisphenol A, an estrogenic environmental toxicant, has been implicated to have hazardous effects on reproductive health in humans and rodents. However, there are conflicting reports in the literature regarding its effects on male reproductive function. In this study, it was shown that in adult rats treated with acute doses of bisphenol A, a small but statistically insignificant percentage of seminiferous tubules in the testes displayed signs of germ cell loss, consistent with some earlier reports. It also failed to disrupt the blood-testis barrier in vivo. This is possibly due to the low bioavailability of free bisphenol A in the systemic circulation. However, bisphenol A disrupted the blood-testis barrier when administered to immature 20-day-old rats, consistent with earlier reports concerning the higher susceptibility of immature rats towards bisphenol A. This observation was confirmed using primary Sertoli cells cultured in vitro with established tight junction-permeability barrier that mimicked the blood-testis barrier in vivo. The reversible disruption of Sertoli cell tight junction barrier by bisphenol A was associated with an activation of ERK, and a decline in the levels of selected proteins at the tight junction, basal ectoplasmic specialization, and gap junction at the blood-testis barrier. Studies by dual-labeled immunofluorescence analysis and biotinylation techniques also illustrated declining levels of occludin, connexin 43, and N-cadherin at the cell-cell interface following bisphenol A treatment. In summary, bisphenol A reversibly perturbs the integrity of the blood-testis barrier in Sertoli cells in vitro, which can also serve as a suitable model for studying the dynamics of the blood-testis barrier. © 2009 Elsevier Ltd. All rights reserved.postprin

Fast block-based image restoration employing the improved best neighborhood matching approach

2005-2006 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Watermark extraction by magnifying noise and applying global minimum decoder

Author name used in this publication: David ZhangCenter for Multimedia Signal Processing and Department of ComputingVersion of RecordPublishe

Computerized tongue diagnosis based on Bayesian networks

2004-2005 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Soot: A review of computational models at different length scales

The computational modelling of soot formation and destruction during the combustion process is one of the most challenging topics in combustion research. This paper reviews the numerical soot models constructed at different length scales, including macroscale, mesoscale, and microscale. The four key stages of soot evolution, including nucleation, surface growth and coagulation, agglomeration, and oxidation, are first described with the generally accepted mathematical formulations in each stage explained. Different computational frameworks and their pros and cons are then reviewed, including the one-equation empirical soot model (macroscale), two-equation semi-empirical soot model (macroscale), different variations of population balance model (mesoscale), discrete element model (microscale), and molecular dynamics model (microscale). It is concluded that the accuracy required and the computational cost available are the two major influencing factors to be considered when selecting the appropriate computational model. The user needs to assess the priorities in their specific application and evaluate different modelling options to find the optimal balance between the level of accuracy and computation resources required

Optimization of swirler type dry powder inhaler device design – Numerical investigation on the effect of dimple shape, inlet configuration and mouthpiece constriction

Dry powder inhalers (DPIs) are recognized as one of the most convenient drug delivery devices via the respiratory tract. However, there is a large variation in their dispersion efficiencies due to the cohesive nature of the inhalable pharmaceutical powders. This paper presents a thorough numerical investigation of the effect of various design modifications in swirler type DPI devices. One-way coupled Computational Fluid Dynamics-Discrete Phase Modeling simulations were implemented to evaluate the flow field and particle behaviour in DPIs under 60 L/min inhalation condition. The dispersion behaviour of entrained particles in relation to the particle-wall impactions was evaluated in six different in-house designed and one commercial DPI devices, with variations in dimple shape, inlet orientation, inlet numbers, and mouthpiece pipe constriction. We found that the shape of dimples varies the swirling capability of both fluid and particles and mouthpiece pipe constriction reduced the turbulence kinetic energy. Meanwhile, the axial velocity and impaction frequency are increased as the size of particles are increased. The constriction of mouthpiece pipe did not show significant improvement on the frequency of particle-wall impactions for particles smaller than 10 μm, whilst higher impaction frequencies were observed for particles larger than 10 μm. Overall, the sphere shape dimples with mouthpiece pipe constricted design is optimal in terms of device efficiency

Helical Flow in Healthy and Diseased Patient-specific Coronary Bifurcations

Helical flow (HF) exists in healthy and diseased coronary bifurcations and was found to have a protective atherosclerotic vascular effect in other vessels. However, the role of HF in patient-specific human coronary arteries still needs further study, and is therefore the objective of this study in both healthy and diseased bifurcations. Computational studies were conducted on 16 patient-specific coronary bifurcations, including eight healthy and eight identical cases with idealized narrowing to represent disease. In general, higher HF intensity may have a favorable effect as it corelated to the reduction of the percentage vessel area exposed to adverse time averaged wall shear stress (TAWSS%) in both healthy and diseased models. The HF intensity and distribution of each model varies due to the complex shape of patient-specific models. The presence of disease appears to have an important impact on the downstream HF patterns and the TAWSS distributions. Clinical Relevance - By understanding the relationship between HF and hemodynamics, HF may be used as a predictor for the formation and progression of atherosclerotic plaque in coronary arteries instead of near-wall WSS measures, which can be determined with higher accuracy in vivo

Approximate entropy based pulse variability analysis

Author name used in this publication: David ZhangVersion of RecordPublishe