Tear resistance of sparsely reinforced elastomer sheets

A family of elastomer composites has been developed which has outstanding tear resistance, and good tensile strength and elongation to failure as measured in a standard tensile test. These composites constitute a family in that they all are sparsely reinforced by a fishnet-like webbing of reinforcement. The members of the family differ in that the reinforcements can be as flexible as soft polyurethane rod or as stiff as carbon fiber with 3000 strands per fiber. All these composites produce outstanding tear strength and an increase in the elongation to failure in an ASTM Die-C type of tear test. The intersections of the polyurethane rod reinforcements prove to be effective crack arrestors.     

An Enhanced A-MSDU Frame Aggregation Scheme for 802.11n Wireless Networks

The main goal of the IEEE 802.11n standard is to achieve a minimum throughput of 100 Mbps at the MAC service access point. This high throughput has been achieved via many enhancements in both the physical and MAC layers. A key enhancement at the MAC layer is frame aggregation in which the timing and headers overheads of the legacy MAC are reduced by aggregating multiple frames into a single large frame before being transmitted. Two aggregation schemes have been defined by the 802.11n standard, aggregate MAC service data unit (A-MSDU) and aggregate MAC protocol data unit (A-MPDU). As a consequence of the aggregation, new aggregation headers are introduced and become parts of the transmitted frame. Even though these headers are small compared to the legacy headers they still have a negative impact on the network performance, especially when aggregating frames of small payload. Moreover, the A-MSDU is highly influenced by the channel condition due mainly to lack of subframes sequence control and retransmission. In this paper, we have proposed an aggregation scheme (mA-MSDU) that reduces the aggregation headers and implements a retransmission control over the individual subframes at the MSDU level. The analysis and simulations results show the significance of the proposed scheme, specifically for applications that have a small frame size such as VoIP.     

Enhancing inter-PMIPv6-domain for superior handover performance across IP-based wireless domain networks

As a network-based localized mobility management protocol, Proxy Mobile IPv6 (PMIPv6) enables a Mobile Host (MH) to roam within a localized domain without MH intervention in the mobility-related signalling. However, the PMIPv6 maintains MH mobility support in a restriction domain. Therefore, whenever the MH roams away from the PMIPv6 domain, its reachability status will be broken-down causing high handover latency and inevitable traffic loss for its communication session. This article proposes a proactive mechanism to mange the MH handover and maintain its data session continually across inter-PMIPv6-domains. The proposed mechanism introduces an intermediate global mobility anchor entity, called, which is responsible to coordinate MH handover as well as redirect its traffic across inter-PMIPv6-domains. Through various simulation evaluations, via ns-2, several experiments were conducted, revealing numerous results that verify the proposed mechanism superior performance over the conventional inter-PMIPv6-domain handover schemes in terms of handover latency, achieved throughput, protocol signalling cost and end-to-end traffic delivery latency.     

Caspase-3 is required for DNA fragmentation and morphological changes associated with apoptosis

Interleukin 1beta-converting enzyme-like proteases (caspases) are crucial components of cell death pathways. Among the caspases identified, caspase-3 stands out because it is commonly activated by numerous death signals and cleaves a variety of important cellular proteins. Studies in caspase-3 knock-out mice have shown that this protease is essential for brain development. To investigate the requirement for caspase-3 in apoptosis, we took advantage of the MCF-7 breast carcinoma cell line, which we show here has lost caspase-3 owing to a 47-base pair deletion within exon 3 of the CASP-3 gene. This deletion results in the skipping of exon 3 during pre-mRNA splicing, thereby abrogating translation of the CASP-3 mRNA. Although MCF-7 cells were still sensitive to tumor necrosis factor (TNF)- or staurosporine-induced apoptosis, no DNA fragmentation was observed. In addition, MCF-7 cells undergoing cell death did not display some of the distinct morphological features typical of apoptotic cells such as shrinkage and blebbing. Introduction of the CASP-3 gene into MCF-7 cells resulted in DNA fragmentation and cellular blebbing following TNF treatment. These results indicate that although caspase-3 is not essential for TNF- or staurosporine-induced apoptosis, it is required for DNA fragmentation and some of the typical morphological changes of cells undergoing apoptosis.     

Nonnegative matrix factorization and metamorphic malware detection

Metamorphic malware change their internal code structure by adopting code obfuscation technique while maintaining their malicious functionality during each infection. This causes change of their signature pattern across each infection and makes signature based detection particularly difficult. In this paper, through static analysis, we use similarity score from matrix factorization technique called Nonnegative Matrix Factorization for detecting challenging metamorphic malware. We apply this technique using structural compression ratio and entropy features and compare our results with previous eigenvector-based techniques. Experimental results from three malware datasets show this is a promising technique as the accuracy detection is more than 95%.

     

Trypsin Inhibitor from 3 Legume Seeds: Fractionation and Proteolytic Inhibition Study

ABSTRACT: The trypsin inhibitor from navy beans (Phaseoulus vulgaris), red kidney beans (Phaseoulus vulgaris L.), and adzuki beans (Vigna angularis) provided by the Royal Project Foundation in Thailand was isolated by heat and ammonium sulfate (AS) precipitation. Incubation at 70 °C for 10 min produced the highest trypsin inhibitor recovery for all legumes. The AS precipitation with 60% to 80% saturation (precipitate IV) resulted in 41-, 88-, and 34-fold of the purity and (−)26%, 126%, and (−)47% of percentage of activity increase for navy beans, red kidney beans, and adzuki beans, respectively. The trypsin inhibitors had a molecular weight of 132 kDa for navy beans, 118 kDa for red kidney beans, and 13 kDa for adzuki beans under nonreducing conditions. The obtained precipitate IV fraction from each legume effectively prevented the degradation of the tilapia muscle with concentration dependent. The myosin heavy chain increased as the concentration of the inhibitor fraction increased, especially at the highest level of addition. The result indicated that the precipitate IV from these legumes have potential for use as a protease inhibitor in fishery related products.     

Polypropylene‐dispersed domain as potential nucleating agent in PS and PMMA solid‐state foaming

The potential of using dispersive domains in a polymer blend as a bubble nucleating agent was investigated by exploiting its high dispersibility in a matrix polymer in the molten state and its immiscibility in the solid state. In this experiments, polypropylene (PP) was used as the nucleating agent in polystyrene (PS) and poly(methyl methacrylate) (PMMA) foams at the weight fraction of 10, 20, and 30 wt %. PP creates highly dispersed domains in PS and PMMA matrices during the extrusion processing. The high diffusivity of the physical foaming agent, i.e., CO₂ in PP, and the high interfacial tension of PP with PS and PMMA could be beneficial for providing preferential bubble nucleation sites. The experimental results of the pressure quench solid‐state foaming of PS/PP and PMMA/PP blends verified that the dispersed PP could successfully increase the cell density over 10⁶ cells/cm³ for PS/PP and 10⁷ cells/cm³ for PMMA/PP blend and reduce the cell size to 24 μm for PS/PP and 9 μm for PMMA/PP blends foams. The higher interfacial tension between PP and the matrix polymer created a unique cell morphology where dispersed PP particles were trapped inside cells in the foam. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

A Network Selection Algorithm Based on Enhanced Access Router Discovery in Heterogeneous Wireless Networks

The management process between different wireless technologies for mobile devices is very important to complete the handover operations. The handover operation needs to determine the delay and packet loss in order to be the quality of service within a certain level. Selecting the best available network at the appropriate time is very significant in the direction of realizing ubiquitous networks. In this paper a network selection approach named enhanced access router discovery (EARD) is proposed. The approach is developed to work in a heterogeneous environment including of WiMAX and WLAN networks. The EARD method utilizes the prioritized rating for multiple criteria (PRMC) proposed for selecting the target network. The proposed approach is evaluated with respect to various conditions with different traffic types. The simulation results show that our proposed approach outperform the traditional network selection methods is selecting the most appropriate network.     

An Adaptive Delayed Acknowledgment Strategy to Improve TCP Performance in Multi-hop Wireless Networks

In multi-hop wireless networks, transmission control protocol (TCP) suffers from performance deterioration due to poor wireless channel characteristics. Earlier studies have shown that the small TCP acknowledgments consume as much wireless resources as the long TCP data packets. Moreover, generating an acknowledgment (ACK) for each incoming data packet reduces the performance of TCP. The main factor affecting TCP performance in multi-hop wireless networks is the contention and collision between ACK and data packets that share the same path. Thus, lowering the number of ACKs using the delayed acknowledgment option defined in IETF RFC 1122 will improve TCP performance. However, large cumulative ACKs will induce packet loss due to retransmission time-out at the sender side of TCP. Motivated by this understanding, we propose a new TCP receiver with an adaptive delayed ACK strategy to improve TCP performance in multi-hop wireless networks. Extensive simulations have been done to prove and evaluate our strategy over different topologies. The simulation results demonstrate that our strategy can improve TCP performance significantly.