Designing Efficient and Robust Caching Algorithms for Streaming-on-Demand Services on the Internet

Content Delivery Networks (CDN) have been used on the Internet to cache media content so as to reduce the load on the original media server, network congestion, and latency. Due to the large size of media content compared to normal web objects, current caching algorithms used in the Internet are no longer suitable. This paper presents a high-performance prefetch system that accommodates user time-varying behavior. A hybrid caching technique, which combines prefetch and replacement algorithms, is also introduced. The robustness of the cache system against imperfect user request information is evaluated using three request noise models. Two prefetch performance indices are also presented to help content administrators in deciding when to update the user request profile for caching algorithms.     

Preparation and optimisation of liposome‐in‐alginate beads containing oyster hydrolysate for sustained release

Oyster (Crassostrea gigas) hydrolysate shows antihypertensive effect in our previous study. Oral administration of oyster hydrolysate can loss bioactive peptides due to enzymatic degradation in vivo. To maximise its bioavailability, liposome‐in‐alginate (LA) beads were used to encapsulate the oyster hydrolysates to protect from degradation and obtain sustained release. The preparation conditions of the LA beads were optimised by response surface method using a model peptide of tyrosylalanine (YA). Their characterisation, swelling and release properties were investigated. The optimised conditions for the concentration of calcium chloride, sodium alginate and the amount of ethanol‐dissolved lecithin (EDL) were 0.5 m , 3% and 95.4 mg, respectively. The encapsulation efficiencies of YA and the oyster hydrolysate in the optimised condition were 74.9% and 84.3%, respectively. The release time of the oyster hydrolysate in the simulated gastrointestinal fluid was up to 16 h. The LA beads can be recommended to encapsulate oyster hydrolysate for bioavailability improvement.     

Effects of driver age and experience in abrupt-onset hazards

Novice drivers and older drivers are found to have the highest crash risk among all drivers and this has motivated many research studies into various aspects of novice and older drivers. Although age-related declines were expected, studies did not find older drivers to respond slower to hazards. This study examined the hazard detection and response latencies of 14 young novice drivers, 14 young experienced drivers, and 12 older experienced drivers, to abrupt-onset hazards. Older drivers were found to take longer times before fixating on an abrupt-onset road hazard but appeared to have insignificantly faster reaction times after the initial fixation. Hence, the overall response latency did not suggest any age effects. Older drivers also scanned the roadway less as compared to their younger counterparts. No effects of experience were found. The findings provided insight on age-related declines in hazard detection whose effects have been masked by other components of hazard response.     

Chemical Signals of Synthetic Disaccharide Derivatives Dominate Rhamnolipids at Controlling Multiple Bacterial Activities

Microbes secrete molecules that modify their environment. Here, we demonstrate a class of synthetic disaccharide derivatives (DSDs) that mimics and dominates the activity of naturally secreted rhamnolipids by Pseudomonas aeruginosa. The DSDs exhibit the dual function of activating and inhibiting the swarming motility through a concentration‐dependent activity reversal that is characteristic of signaling molecules. Whereas DSDs tethered with a saturated farnesyl group exhibit inhibition of both biofilm formation and swarming motility, with higher activities than rhamnolipids, a saturated farnesyl tethered with a sulfonate group only inhibits swarming motility but promote biofilm formation. These results identified important structural elements for controlling swarming motility, biofilm formation, and bacterial adhesion and suggest an effective chemical approach to control intertwined signaling processes that are important for biofilm formation and motilities.     

Network coding theory: An introduction

For a long time, store-and-forward had been the transport mode in network communications. In other words, information had been regarded as a commodity that only needs to be routed through the network, possibly with replication at the intermediate nodes. In the late 1990’s, a new concept called network coding fundamentally changed the way a network can be operated. Under the paradigm of network coding, information can be processed within the network for the purpose of transmission. It was demonstrated that compared with store-and-forward, the network throughput can generally be increased by employing network coding. Since then, network coding has made significant impact on different branches of information science. The impact of network coding has gone as far as mathematics, physics, and biology. This expository work aims to be an introduction to this fast-growing subject with a detailed discussion of the basic theoretical results.     

Developing a Fuzzy Risk Allocation Model for PPP Projects in China

Equitable allocation of risks between the government and the private sector in concession agreement is essential to the success of public-private partnership (PPP) projects. The decision-making process, based on the established risk allocation principles expressed in linguistic terms, requires qualitative judgment and experiential knowledge of construction experts. However, it is subjective, partial, and implicit in actual application. This paper aims to develop a fuzzy synthetic evaluation model for determining an equitable risk allocation between the government and the private sector. By doing so, it assists the PPP project practitioners to transform the risk allocation principles in linguistic terms into a more usable and systematic quantitative-based analysis using fuzzy set. Twenty-three principles and influencing factors for risk allocation were identified through a comprehensive literature review. Nine critical risk allocation criteria (RACs) that evaluate the risk carrying capability of project participants were further identified, validated, and compiled based on the experts’ knowledge via face-to-face interviews. On the other hand, the weighting for each critical risk allocation criterion was determined through a two-round Delphi questionnaire survey. A set of knowledge-based fuzzy inference rules was then established to set up the membership function for the nine RACs. Based on the research findings, a fuzzy synthetic evaluation model was finally established to determine an equitable risk allocation between the government and the private sector.     

One-step concentration of analytes based on dynamic change in pH in capillary zone electrophoresis

A novel strategy for one-step concentration of analytes during capillary electrophoresis (CE) is presented. A short platinum wire was inserted into the 75-microm-i.d. separation capillary. When a high voltage was applied for CE separation, a sharp pH gradient along the capillary was created dynamically by the electrolysis of water in the running buffer. Concentration of a large volume of injected analytes was accomplished by the change in analyte charge due to the dynamic pH gradient. Depending on the polarity of the applied potential and the direction of electroosmotic flow, either anions or cations can be concentrated. Several hundredfold concentration factors were achieved. Fluorescence imaging by a CCD camera was used to monitor 10 cm of the capillary near the platinum wire during the concentration process. The observations are consistent with a sweeping mechanism.