Verification and Validation of Numerical Modelling Approaches Pertinent to Stomach Modelling

The digestive system is vital to the human body. Over many decades, scientists have been investigating the food breakdown mechanisms inside the stomach through in vivo human and animal studies and in vitro experiments. Due to recent improvements in computing speed and algorithm development, computational modelling has become a viable option to investigate in-body processes. Such in silico models are more easily controlled to investigate individual variables, do not require invasive physical experiments, and can provide valuable insights into the local physics of gastric flow. There is a huge potential for numerical approaches in stomach modelling as they can provide a comprehensive understanding of the complex flow and chemistry in the stomach. However, to make sure the numerical methods are accurate and reliable, rigorous verification and validation are essential as part of model development. A significant focus of this thesis was on verifying and validating the numerical modelling approaches pertinent to stomach modellin

Sociodemographic predictors of measles immunization exemption: Washington state, 2013-2018

Background: Measles immunization is one of the school-entry requirements in Washington State, but parents can exempt their children from immunization based on religious, personal- belief and medical reasons. Vaccine hesitancy is a growing issue in the United States. In the 2019 Washington measles outbreak, most cases were unvaccinated children. Methods: We used 2013-2018 measles immunization exemption data from the Washington Department of Public Health to examine the change over time. We used spatial lag regression models to analyze the relationship between economical, race, education and population predictors and school districts-level measles exemption rates. Results: The percentage of students with measles exemption increased to 4.10% in school year 2017-2018. In the spatial lag regression model, measles exemption rate increased with 2.94% for each 10000 USD increase in median household income ( 95%CI: 1.96%-3.41% ). Conclusions: Measles exemptions for students in Washington are more common in areas with a higher income. Public Health Relevance: The 2019 Washington measles outbreak brought concerns to measles vaccination exemptions. In recent years, the proportion of exemptions based on religious and personal belief is rising. But recent data and Washington data were little covered for research. We analyzed exemption data to help future immunization work

Quality of service for video stream over IP networks

Multimedia networking is one of the most exciting developments in today's Internet. Streaming technology; which allows the player to start playing audio/video data immediately instead of waiting for the entire file to be downloaded, presents an attractive vehicle for the distribution of multimedia content over the Internet. However, transmitting real-time streaming audio/video across a network is a very demanding task in that it mandates significant bandwidth and quality-of-service (QoS). Due to the underlying protocols, today's Internet technologies support real-time services only in a best-effort manner. The qualities of the audio/video are very sensitive to the network impairments, such as packet losses, bit-errors, delays and jitters. To understand the challenges that currently face streaming video delivery, this project investigates the impact of network conditions to video QoS. Specifically, a network traffic model to simulate the network communication problems has been established based on a 2-state Markov model - Gilbert model. Integrated with Windows Media technologies, a network impairment emulator was implemented. These software tools provide a way to better understand the relationship between transmission parameters vs. video quality of service in an emulation environment, which may not be easily analyzed over the real IP networks. These relationships would give us insights for deriving optimal criteria to improve the QoS of video streaming.Keywords and Phrases: Internet, IP networks, streaming video, quality of service, Windows Media, packet capture, network impairment emulator, Internet traffic mode

Tumor-on-a-chip model for advancement of anti-cancer nano drug delivery system

Despite explosive growth in the development of nano-drug delivery systems (NDDS) targeting tumors in the last few decades, clinical translation rates are low owing to the lack of efficient models for evaluating and predicting responses. Microfluidics-based tumor-on-a-chip (TOC) systems provide a promising approach to address these challenges. The integrated engineered platforms can recapitulate complex in vivo tumor features at a microscale level, such as the tumor microenvironment, three-dimensional tissue structure, and dynamic culture conditions, thus improving the correlation between results derived from preclinical and clinical trials in evaluating anticancer nanomedicines. The specific focus of this review is to describe recent advances in TOCs for the evaluation of nanomedicine, categorized into six sections based on the drug delivery process: circulation behavior after infusion, endothelial and matrix barriers, tumor uptake, therapeutic efficacy, safety, and resistance. We also discuss current issues and future directions for an end-use perspective of TOCs

Magnetic resonance angiography signal intensity as a marker of hemodynamic impairment in intracranial arterial stenosis.

BackgroundIntracranial arterial stenosis (ICAS) is the predominant cause of ischemic stroke and transient ischemic attack in Asia. Change of signal intensities (SI) across an ICAS on magnetic resonance angiography (MRA) may reflect its hemodynamic severity.MethodsIn-patients with a symptomatic single ICAS detected on 3D time-of-flight MRA were recruited from 2 hospitals. Baseline and 1-year follow-up data were collected. Signal intensity ratio (SIR) [ =  (mean post-stenotic SI -mean background SI)/(mean pre-stenotic SI - mean background SI)] was evaluated on baseline MRA to represent change of SIs across an ICAS. Acute infarct volume was measured on baseline diffusion-weighted images (DWI). Relationships between SIR and baseline characteristics as well as 1y outcomes were evaluated.ResultsThirty-six subjects (86.1% males, mean age 55.0) were recruited. Overall, mean SIR was 0.84±0.23. Mean SIRs were not significantly different between the 23 (63.9%) anatomically severe stenoses and the 13 (36.1%) anatomically moderate stenoses (0.80±0.23 versus 0.92±0.21, p = 0.126). SIR was significantly, linearly and negatively correlated to acute infarct volume on DWI (Spearman correlation coefficient -0.471, p = 0.011). Two patients (5.6%) had recurrent ischemic strokes at 1y, not related to SIR values.ConclusionsChange of signal intensities across an ICAS on MRA may reflect its hemodynamic and functional severity. Future studies are warranted to further verify the relationships between this index and prognosis of patients with symptomatic ICAS