Forced generation of simple and double emulsions in all-aqueous system

We report an easy-to-implement method that allows the direct generation of water-in-water (w/w) single emulsions. The method relies on direct perturbation of the pressure that drives the flow of the dispersed phase of the emulsions. The resultant inner jet is induced to break up into droplets due to the growth of the perturbation through Rayleigh-Plateau instability [L. Rayleigh, Proc. R. Soc. London 29, 71-97 (1879)]; this leads to the formation of monodisperse droplets. By implementing this method on a modified microfluidic device, we directly generate water-in-water-in-water (w/w/w) double emulsions with good control over the size and the number of encapsulated droplets. Our approach suggests a new route to apply droplet-based microfluidics to completely water-based systems

Fluctuation-induced dynamics of multiphase liquid jets with ultra-low interfacial tension

Control of fluid dynamics at the micrometer scale is essential to emulsion science and materials design, which is ubiquitous in everyday life and is frequently encountered in industrial applications. Most studies on multiphase flow focus on oil-water systems with substantial interfacial tension. Advances in microfluidics have enabled the study of multiphase flow with more complex dynamics. Here, we show that the evolution of the interface in a jet surrounded by a co-flowing continuous phase with an ultra-low interfacial tension presents new opportunities to the control of flow morphologies. The introduction of a harmonic perturbation to the dispersed phase leads to the formation of interfaces with unique shapes. The periodic structures can be tuned by controlling the fluid flow rates and the input perturbation; this demonstrates the importance of the inertial effects in flow control at ultra-low interfacial tension. Our work provides new insights into microfluidic flows at ultra-low interfacial tension and their potential applications

Tilings of the Sphere by Edge Congruent Pentagons

We study edge-to-edge tilings of the sphere by edge congruent pentagons, under the assumption that there are tiles with all vertices having degree 3. We develop the technique of neighborhood tilings and apply the technique to completely classify edge congruent earth map tilings.Comment: 36 pages, 34 figure

Towards a transparent, credible, evidence-based decision-making process of new drug listing on the Hong Kong Hospital Authority Drug Formulary: challenges and suggestions

The aim of this article is to describe the process, evaluation criteria, and possible outcomes of decision-making for new drugs listed in the Hong Kong Hospital Authority Drug Formulary in comparison to the health technology assessment (HTA) policy overseas. Details of decision-making processes including the new drug listing submission, Drug Advisory Committee (DAC) meeting, and procedures prior to and following the meeting, were extracted from the official Hong Kong Hospital Authority drug formulary management website and manual. Publicly-available information related to the new drug decision-making process for five HTA agencies [the National Institute of Health and Care Excellence (NICE), the Scottish Medicines Consortium (SMC), the Australia Pharmaceutical Benefits Advisory Committee (PBAC), the Canadian Agency for Drugs and Technologies in Health (CADTH), and the New Zealand Pharmaceutical Management Agency (PHARMAC)] were reviewed and retrieved from official documents from public domains. The DAC is in charge of systemically and critically appraising new drugs before they are listed on the formulary, reviewing submitted applications, and making the decision to list the drug based on scientific evidence to which safety, efficacy, and cost-effectiveness are the primary considerations. When compared with other HTA agencies, transparency of the decision-making process of the DAC, the relevance of clinical and health economic evidence, and the lack of health economic and methodological input of submissions are the major challenges to the new-drug listing policy in Hong Kong. Despite these challenges, this review provides suggestions for the establishment of a more transparent, credible, and evidence-based decision-making process in the Hong Kong Hospital Authority Drug Formulary. Proposals for improvement in the listing of new drugs in the formulary should be a priority of healthcare reforms

Social media and political participation : a case study of facebook as a plaftorm of communication, mobilization and action

Social media is increasingly used for political conversations and debate. In Hong Kong, social media has provided a convenient and accessible platform for stakeholders in the political arena to publicize their ideas and for users to be engaged in political discourse. This study aims at investigating the effects of social media on political participation among Hong Kong youth, who are generally regarded as “digital natives” and “critical citizens”. This study focuses on Facebook, the most widely-used social networking site in Hong Kong, and examines how Facebook use, connection and interactivity with political actors on Facebook, exposure to political information on Facebook and perceived information quality of Facebook relate to online and offline political participation among young people in Hong Kong. Questionnaires are collected from local post-secondary students and graduates aged between 18 and 29. Findings show that connection with political actors on Facebook and exposure to political information on Facebook mediate the impact of Facebook use on political participation, which echo the results of previous studies. Semistructured interviews are also conducted with sampled youth in order to explore the perception of Hong Kong youth on Facebook in terms of the intensity of interaction with political actors via Facebook pages and the quality of political information disseminated on Facebook. In light of the concept of public sphere and its later revisions, this research argues that social media add value to political engagement by offering alternative news and information source and facilitating a vibrant discussion of politics online. However, the effects of social media have to be qualified. Reactions to political information on Facebook and subsequent decisions on political participation also involve the expression of emotions and spontaneous response to a critical event, rather than merely depending on rational and critically informed debate. Explanations to the relationships between the variables are discussed. Sociological implications on the capabilities of social media in generating social capital and engaging users in the public sphere, as well as practical implications on the multidimensional use of social media applications and the usefulness of social media for stakeholders in socio-political aspects, are proposed. This study contributes to a greater understanding of the mobilization potential of social media in both online and offline political activism

Analysis of Fluid Queues Using Level Crossing Methods ID: 11563

This dissertation is concerned with the application of the level crossing method on fluid queues driven by a background process. The basic assumption of the fluid queue in this thesis is that during the busy period of the driving process, the fluid content fills at net rate r_1, and during the idle period of the driving process, the fluid content, if positive-valued, empties at a rate r_2. Moreover, nonempty fluid content, leaks continuously at a rate r_2. The fluid models considered are: the fluid queue driven by an M/G/1 queue in Chapter 2, the fluid queue driven by an M/G/1 queue with net input and leaking rate depending on fluid level, and type of arrivals in the driving M/G/1 queue, in chapter 3, and the fluid queue driven by an M/G/1 queue with upward fluid jumps in Chapter 4. In addition, a triangle diagram has been introduced in this thesis as a technique to visualize the proportion of time that the content of the fluid queue is increasing or decreasing during nonempty cycles. Finally, we provide several examples on how the probability density function of the fluid level is related to the probability density function of the waiting time of M/G/1 queues with different disciplines