Reinforcement learning-based trust and reputation model for spectrum leasing in cognitive radio networks

Cognitive Radio (CR), which is the next generation wireless communication system, enables unlicensed users or Secondary Users (SUs) to exploit underutilized spectrum (called white spaces) owned by the licensed users or Primary Users(PUs) so that bandwidth availability improves at the SUs, which helps to improve the overall spectrum utilization. Collaboration, which has been adopted in various schemes such distributed channel sensing and channel access, is an intrinsic characteristic of CR to improve network performance. However, the requirement to collaborate has inevitably open doors to various forms of attacks by malicious SUs, and this can be addressed using Trust and Reputation Management (TRM). Generally speaking, TRM detects malicious SUs including honest SUs that turn malicious. To achieve a more efficient detection, we advocate the use of Reinforcement Learning (RL), which is known to be flexible and adaptable to the changes in operating environment in order to achieve optimal network performance. Its ability to learn and re-learn throughout the duration of its existence provides intelligence to the proposed TRM model, and so the focus on RL-based TRM model in this paper. Our preliminary results show that the detection performance of RLbased TRM model has an improvement of 15% over the traditional TRM in a centralized cognitive radio network. The investigation in the paper serves as an important foundation for future work in this research field

Bioassay-Guided Isolation of Cytotoxic Cycloartane Triterpenoid Glycosides from the Traditionally Used Medicinal Plant Leea indica

Leea indica is a medicinal plant used traditionally to cure cancer. In this study, the cytotoxic compounds of L. indica were isolated using bioassay-guided approach. Two cycloartane triterpenoid glycosides, mollic acid arabinoside (MAA) and mollic acid xyloside (MAX), were firstly isolated from L. indica. They inhibited the growth of Ca Ski cervical cancer cells with IC50 of 19.21 μM (MAA) and 33.33 μM (MAX). MRC5 normal cell line was used to calculate selectivity index. MAA and MAX were about 8 and 4 times more cytotoxic to Ca Ski cells compared to MRC5. The cytotoxicity of MAA was characterized by both cytostatic and cytocidal effects. MAA decreased the expression of proliferative cell nuclear antigen, increased sub-G1 cells, and arrested cells in S and G2/M phases. This study provides the evidence for the ethnomedicinal use of L. indica and paves the way for future mechanism studies on the anticancer effects of MAA

Social differentiation and age-friendly characteristics : a case study in Tuen Mun

Hong Kong is one of Asia’s more demographically-aged cities, with 14% of population aged 65+ in 2012, projected to be 23% by 2025. Facilities and transport are generally good by world standards although the urban environment may not consistently be particularly ‘age-friendly’. Drawing on a range of urban sub-areas, this research investigated the ‘age-friendliness’ of Tuen Mun, a ‘new town’ of half a million population in Hong Kong. This study was also interested in socio-cultural variables and age-friendly cities (AFC) characteristics in its predominantly Chinese population, and relationships with psychological well-being (PWB). A total of 503 participants aged 50 years or above were interviewed in a face-to-face questionnaire survey in Tuen Mun. Two focus groups were held afterwards as a post facto evaluation to ascertain and explain the findings of the survey. Among the WHO’s original eight AFC domains, in this study ‘Social participation’ scored the highest AFC rating. ‘Housing’, ‘Civic participation and employment’, and ‘Community support and health services’ perhaps surprisingly scored the lowest. Interestingly, the ‘higher social group’ (i.e. respondents from private housing, with a higher education attainment and household income) tended to be less satisfied with the AFC domains than the lower social group. An important contribution of this study is therefore to show the importance of considering social variations in attitudes to AFC characteristics, as perceptions/expectations of AFC might vary across different social groups. This study also addressed the potential role of AFC characteristics in influencing older persons’ PWB. AFC, especially the ‘software’ aspects related to social support, were found to have the strongest positive correlations with PWB. A newly-proposed ‘Food and shopping’ dimension appeared to be a salient factor affecting PWB, showing such ‘lifestyle’ items should be included in AFC in Asian settings. The policy implications and the value of the AFC concept in cities such as Hong Kong are discussed

Assessment of phytochemical content, polyphenolic composition, antioxidant and antibacterial activities of Leguminosae medicinal plants in Peninsular Malaysia

Background: Many medicinal plants from Leguminosae family can be found easily in Malaysia. These plants have been used as traditional medicines by local ethnic groups, where they are prepared as decoction, pastes for wound infections, and some have been eaten as salad. This paper focused on the assessment of antioxidant potential, antibacterial activity and classes of phytochemicals of nine plants from the Leguminosae family. Methods: Acacia auriculiformis, Bauhinia kockiana, Bauhinia purpurea, Caesalpinia pulcherrima, Calliandra tergemina, Cassia surattensis, Leucaena leucocephala, Peltophorum pterocarpum, and Samanea saman were extracted with aqueous methanol and dichloromethane:methanol mixture to test for antioxidant and antibacterial activities. The Folin-Ciocalteu assay was conducted to quantify the total phenolic content and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assay was used to determine the free radical quenching capacity. Antibacterial activity was assessed using disc diffusion (Kirby-Bauer) assay. Screening for major classes of phytochemical was done using standard chemical tests. Results: B. kockiana flowers and C. pulcherrima leaves contained high total phenolic content (TPC) and strong DPPH radical scavenging ability with TPC of 8280 ± 498 mg GAE/100 g, IC50 of 27.0 ± 5.0 μg/mL and TPC of 5030 ± 602 mg GAE/100 g, IC50 of 50.0 ± 5.0 μg/mL respectively. Positive correlation was observed between TPC and free radical scavenging ability. Most extracts showed antibacterial activity against Gram positive bacteria at 1 mg, while none showed activity against Gram negative bacteria at the same dose. All extracts (except Samanea saman flower) showed antibacterial activity against two strains of methicillin resistant Staphylococcus aureus (MRSA) with MID values ranging between 100 μg/disc and 500 μg/disc. Conclusion: The potential source of antioxidant and antibacterial agents, especially for MRSA infection treatments were found in B. kockiana, C. pulcherrima, C. tergemina and P. pterocarpum. These preliminary results would be a guide in the selection of potential candidates for further pharmacological study and in search of new drug candidate in treating MRSA infections

Physico-chemical compositions of the red seedless watermelons (Citrullus Lanatus)

Changes of physico-chemical properties such as size, weight, moisture content, total soluble solid (TSS), colour, pH, total acidity and sugar content of red seedless watermelon during storage at room temperature (± 28°C; 70-80% RH) were investigated. The average weight, diameter and length of red seedless watermelon were 5.94 kg, 22.0 cm and 21.8 cm respectively. The length to diameter ratio was 1.02. The statistical analysis indicated that total soluble solids of fruit decreased significantly (p<0.01), but no significant changes were found in pH and total acidity during ripening. Weight loss, moisture content and freezing point was found to be increased significantly (p<0.01) during ripening. Colour L* was found no significant changes but colour a* and b* increased significantly (p<0.1) throughout the ripening process. For sugar analysis, significant changes (p<0.1) in fructose and glucose were obtained, but no significant changes were observed in sucrose content during storage time. From the observation, the optimum eating quality of watermelon stored in room temperature (± 28°C; 70-80% RH) was within one week after harvest, although they can be stored up to 2 weeks. The data obtained is vital in order to apply in different field, purpose and application

Trust and reputation management for securing collaboration in 5G access networks: the road ahead

Trust represents the belief or perception of an entity, such as a mobile device or a node, in the extent to which future actions and reactions are appropriate in a collaborative relationship. Reputation represents the network-wide belief or perception of the trustworthiness of an entity. Each entity computes and assigns a trust or reputation value, which increases and decreases with the appropriateness of actions and reactions, to another entity in order to ensure a healthy collaborative relationship. Trust and reputation management (TRM) has been investigated to improve the security of traditional networks, particularly the access networks. In 5G, the access networks are multi-hop networks formed by entities which may not be trustable, and so such networks are prone to attacks, such as Sybil and crude attacks. TRM addresses such attacks to enhance the overall network performance, including reliability, scalability, and stability. Nevertheless, the investigation of TRM in 5G, which is the next-generation wireless networks, is still at its infancy. TRM must cater for the characteristics of 5G. Firstly, ultra-densification due to the exponential growth of mobile users and data traffic. Secondly, high heterogeneity due to the different characteristics of mobile users, such as different transmission characteristics (e.g., different transmission power) and different user equipment (e.g., laptops and smartphones). Thirdly, high variability due to the dynamicity of the entities’ behaviors and operating environment. TRM must also cater for the core features of 5G (e.g., millimeter wave transmission, and device-to-device communication) and the core technologies of 5G (e.g., massive MIMO and beamforming, and network virtualization). In this paper, a review of TRM schemes in 5G and traditional networks, which can be leveraged to 5G, is presented. We also provide an insight on some of the important open issues and vulnerabilities in 5G networks that can be resolved using a TRM framework