oStream: asynchronous streaming multicast in application-layer overlay networks

Although initially proposed as the deployable alternative to Internet protocol multicast, the application-layer overlay network actually revolutionizes the way network applications can be built, since each overlay node is an end host and is able to carry out more functions than simply forwarding packets. The paper addresses the on-demand media distribution problem in the context of an overlay network. We take advantage of the strong buffering capabilities of end hosts, and propose a novel overlay multicast strategy, oStream. We have performed extensive analysis and performance evaluation with respect to the scalability and the efficiency of oStream. With respect to the required server bandwidth, we show that oStream defeats the theoretical lower bound of traditional multicast-based approaches, under both sequential and nonsequential stream access patterns. oStream is also robust against bursty requests. With respect to bandwidth consumption on the backbone network, we show that the benefit introduced by oStream overshadows the topological inefficiency (e.g., link stress and stretch) introduced by using application-layer multicast.     

Providing Fault-Tolerant Ad hoc Routing Service in Adversarial Environments

Most existing designs of ad hoc networks are based on the assumption of non-adversarial environments, where each node in the network is cooperative and well-behaved. When misbehaving nodes exist in the network, the performance of current routing protocols degrades significantly. Since ad hoc networks, consisting of autonomous nodes, are open and distributed in nature, maintaining a fault-free network environment is extremely difficult and expensive. In this paper, we propose a new routing service named best-effort fault-tolerant routing (BFTR). The design goal of BFTR is to provide packet routing service with high delivery ratio and low overhead in presence of misbehaving nodes. Instead of judging whether a path is good or bad, i.e., whether it contains any misbehaving node, BFTR evaluates the routing feasibility of a path by its end-to-end performance (e.g. packet delivery ratio and delay). By continuously observing the routing performance, BFTR dynamically routes packets via the most feasible path. BFTR provides an efficient and uniform solution for a broad range of node misbehaviors with very few security assumptions. The BFTR algorithm is evaluated through both analysis and extensive simulations. The results show that BFTR greatly improves the ad hoc routing performance in the presence of misbehaving nodes.     

Quality of Rapeseed Oil Produced by Conditioning Seeds at Modest Temperatures

Conditioning rapeseed can significantly increase the amount of bioactive compounds in the crude oil, but if the conditioning temperatures are too high, they can cause unwanted side effects such as darker color and sensory defects. Modest conditioning temperatures may be more suitable, but little is known about the effects on the quality and bioactive composition of the resulting oil. Oil was recovered from five rapeseed cultivars by cold pressing (CP) or by pressing seeds conditioned at 80 °C for 30 min (HP). Conditioning rapeseed increased oil yield without changing fatty acid composition and increased the amount of total sterols by 16 %, total tocopherols by 20 %, and the levels of polyphenols. Levels of the polyphenol canolol were up to 55-fold higher in HP oil than in CP oil. These higher levels of bioactive compounds gave HP oil higher radical scavenging activity. Although HP oil also had higher free fatty acid contents, peroxide levels, and specific UV extinctions (K values). The quality parameters of HP and CP oils were within codex limits indicating high quality. Modest conditioning temperatures can be used to produce rapeseed oil with high quality and radical scavenging activity.     

Open and closed tube method for determination of resonance frequencies of nanofibrous membrane

Nanofibrous layer performs as a membrane that vibrates at low frequencies. This property is obtained by nano dimensions of the interfiber areas. Sound waves incident on the acoustic resonance membrane make the membrane oscillate, and the maximum amplitude occurs in the case of resonance. The structures based on the nanofibrous layers are employed for low-frequency sound absorption. The resonance of the nanofibrous elements allows acoustic energy to be converted into thermal energy. In this article, a nanofibrous layer was produced by electrostatic spinning from an aqueous solution of polyvinyl alcohol and the resonance effect of nanofibrous layer was studied. For this purpose, the new method developed for determination of resonance frequencies of a membrane was employed. The ultimate objective of the study was to assess the effect of mass per unit area on resonance frequencies of the membrane placed in an open and closed tube. The results indicated that the resonance frequencies of the membrane decreased with an increase of the mass per unit area of the nanofibrous membrane. Except for the lowest frequencies (first resonance peak), the resonant behavior of the membrane was affected by the resonance of tube.     

Morphological effects on the bulk polymerization of trioxane in the solid state by γ-radiation

The solid-state polymerization by γ-radiation and postpolymerization of bulk samples of trioxane has been investigated. Different thermal treatment results in radically different initial morphologies of the melt-crystallized trioxane which in turn have a profound influence on the yield and morphology of the resulting poly(oxymethylene) (POM). The polymerization yield increases in the following series: melt-crystallized trioxane with an “opaque” (small grains) morphology, as-grown needles, trioxane with a “quasi-transparent” morphology, and finally thermally oriented crystals. Furthermore, little additional POM is formed during repeated polymerization cycles. The observation of an extensive nodulation of the polymer fibrils when the yield is high is consistent with a multiple-stage growth model for the solid-state polymerization of trioxane.     

Non-chemical approach toward 2D self-assemblies of Ag nanoparticles via cold plasma treatment of substrates

The nano-modification of selected substrates by means of atmospheric cold plasma treatment was exploited for the two-dimensional (2D) self-assembling of silver nanoparticles (Ag NPs). Such a useful combination of the cold plasma treatment of substrate surface and an immediate easy deposition of Ag NPs creating the 2D self-assemblies on the substrates is published for the first time, to the best of our knowledge. Except for the cold plasma treatment, mainly the following parameters influenced the resulting NP assemblies: the choice of solvent mixture, concentration of Ag NP dispersions, and the deposition technique. The 2D self-assemblies of Ag NPs, providing the same work function as a Ag electrode, were formed on the cold plasma-treated substrates when a drop-casting technique was employed. The possibility of an easy preparation of the Ag NP 2D self-assemblies on substrates without using any chemical agents and/or evaporating chamber could be exploited, e.g.?in photovoltaic and light-emitting diode devices.     

The co-action of osmotic and high temperature stresses results in a growth improvement of Debaryomyces hansenii cells

Debaryomyces hansenii is a salt tolerant yeast species, often isolated from sea water or found among other spoilage yeasts in several types of food. In this work, we examined the influence of temperature and increased osmotic pressure (two parameters also important in food industry) on D. hansenii growth. Several other authors showed that its growth at the normal yeast cultivation temperature (28 to 30 degrees C) is stimulated by the presence of sodium, in contrast to the growth of Saccharomyces cerevisiae, which is inhibited by the presence of sodium under the same experimental conditions. Here we show that the previously reported growth stimulation by sodium is temperature dependent in D. hansenii and can be observed under conditions that already amount to high temperature stress for D. hansenii. At a lower temperature (more convenient for D. hansenii cultivation), we found no significant improvement or even an inhibition of cell growth in the presence of Na(+). The growth of D. hansenii at high temperatures is also improved by the presence of potassium or sorbitol. Moreover, the temperature dependence of stimulatory effects of increased osmotic pressure in media does not seem to be unique for D. hansenii; similar relationships between the growth, cultivation temperature and presence of osmolytes we also observed for S. cerevisiae and Schizosaccharomyces pombe.     

Cross-Layer Design for Data Accessibility in Mobile Ad Hoc Networks

Mobile ad hoc networks (MANET) are becoming an integral part of the ubiquitouscomputing and communication environment, providing new infrastructure formultimedia applications such as video phone, multimedia-on-demand, and others.In order to access multimedia information in MANET, Quality of Service (QoS)needs to be considered, such as high success rate to access multimedia data,bounded end-to-end delay, and others. In this paper, we present a dataaccessibility service for a group of mobile users to access desired data withhigh success rate. This accessibility service is only possible if we utilizeadvanced data advertising, lookup and replication services, as well as a novelpredictive location-based QoS routing protocol in an integrated fashion. Usingcross-layer design, we illustrate how the QoS routing protocol assists dataadvertising, lookup and replication services to achieve high data accesssuccess rate. Simulation results have shown that our design is successful ina dynamic MANET.