A robust scheme to defend against disassociation and deauthentication DoS attacks in WLAN networks

Wireless 802.11 (also known as WLAN) has many flaws that expose the medium to numerous types of attacks. WLAN control frame consists of three major parts; data, management and control frames. Data frame is whereby data carried on, in the meantime, management and control frames are both responsible for maintaining the communication between the clients and the access point. The absence of encryption at both of these two frames exposes the medium to inevitable various types of DoS attacks at Data Link Layer. The attacker might spoof the unencrypted Deauthentication/Disassociation message together with the MAC address of the targeted access point and keep retransmitting it to all clients causing a continuous disconnection in WLAN networks. Wireless 802.11w standards has succeeded mitigating the flaw by encrypting the frames, yet only when WPA2 encryption is enforced. In this paper, we developed an enhanced proposed WLAN scheme to mitigate Deauthentication and Disassociation DoS attacks on WLAN networks. The proposed scheme is based on modifying the last twenty bits of the management frame in 802.11n standard using an enhanced version of Linear Congruential Algorithm called MAX algorithm. This is to provide a layer of authentication with no need to enforce WPA2 encryption. The proposed scheme is evaluated using CommeView Simulator and showed to be robust by slowing the attacks in an average of 3551 second on both encrypted and unencrypted networks

Prediction of plant promoters based on hexamers and random triplet pair analysis

<p>Abstract</p> <p>Background</p> <p>With an increasing number of plant genome sequences, it has become important to develop a robust computational method for detecting plant promoters. Although a wide variety of programs are currently available, prediction accuracy of these still requires further improvement. The limitations of these methods can be addressed by selecting appropriate features for distinguishing promoters and non-promoters.</p> <p>Methods</p> <p>In this study, we proposed two feature selection approaches based on hexamer sequences: the Frequency Distribution Analyzed Feature Selection Algorithm (FDAFSA) and the Random Triplet Pair Feature Selecting Genetic Algorithm (RTPFSGA). In FDAFSA, adjacent triplet-pairs (hexamer sequences) were selected based on the difference in the frequency of hexamers between promoters and non-promoters. In RTPFSGA, random triplet-pairs (RTPs) were selected by exploiting a genetic algorithm that distinguishes frequencies of non-adjacent triplet pairs between promoters and non-promoters. Then, a support vector machine (SVM), a nonlinear machine-learning algorithm, was used to classify promoters and non-promoters by combining these two feature selection approaches. We referred to this novel algorithm as PromoBot.</p> <p>Results</p> <p>Promoter sequences were collected from the PlantProm database. Non-promoter sequences were collected from plant mRNA, rRNA, and tRNA of PlantGDB and plant miRNA of miRBase. Then, in order to validate the proposed algorithm, we applied a 5-fold cross validation test. Training data sets were used to select features based on FDAFSA and RTPFSGA, and these features were used to train the SVM. We achieved 89% sensitivity and 86% specificity.</p> <p>Conclusions</p> <p>We compared our PromoBot algorithm to five other algorithms. It was found that the sensitivity and specificity of PromoBot performed well (or even better) with the algorithms tested. These results show that the two proposed feature selection methods based on hexamer frequencies and random triplet-pair could be successfully incorporated into a supervised machine learning method in promoter classification problem. As such, we expect that PromoBot can be used to help identify new plant promoters. Source codes and analysis results of this work could be provided upon request.</p

Oil palm leaf fibre and its suitability for paper-based products

Due to the shortage of wood as origin materials for paper-based production, agro-residue materials have been explored in the quest of finding the best alternative fibre. Oil palm leaf (OPL) is one of agro-residue that has potential due to its comparable characteristics with wood fibre. Studies on chemical compositions, fibre morphology, and mechanical property of OPL have been carried out aiming to evaluate its potential as a substitute raw material for pulp and paper-based production. The chemical compositions were analysed according to the TAPPI standard, Kurscher-Hoffner and chlorite methods accordingly. The mechanical property (tensile, tearing and bursting strengths) were determined as described in TAPPI test methods. Fibre dimensions were determined using Franklin method and analysed under the optical microscope. The content of cellulose in the OPL is determined to be 43.8%. Although, this result is lower than wood fibre (53%), OPL has higher hemicellulose content (36.4%) than the wood fibre (27.5%). In addition, the lignin content (19.7%) of OPL is in the low range of those in wood resources (18 - 25%). These parameters are important components to produce good quality pulp and will provide high mechanical strength of the paper-based products. The measured fibre length of oil palm leaf (1.13 mm) is shorter than the wood fibre (1.90 mm). Meanwhile, the mechanical property of OPL showed lower indexes than wood resources, however, tear (1.80 mN.m2/g) and burst (0.95 kPa.m2/g) indexes of OPL are higher than other published and successful wood resources (Eucalyptus). Based on the analyses, the oil palm leaf is indeed a suitable alternative of raw material for pulp and paper-based industries

A novel mppt technique based on mutual coordination between two pv modules/arrays

A novel maximum power point tracking (MPPT) technique based on mutual coordination of two photovoltaic (PV) modules/arrays has been proposed for distributed PV (DPV) systems. The proposed technique works in two stages. Under non-mismatch conditions between PV modules/arrays, superior performance stage 1 is active, which rectifies the issues inherited by the perturb and observe (P&O) MPPT. In this stage, the technique revolves around the perturb and observe (P&O) algorithm containing an intelligent mechanism of leader and follower between two arrays. In shading conditions, stage 2 is on, and it works like conventional P&O. Graphical analysis of the proposed technique has been presented under different weather conditions. Simulations of different algorithms have been performed in Matlab/Simulink. Simulation results of the proposed technique compliment the graphical analysis and show a superior performance and a fast response as compared to others, thus increasing the efficiency of distributed PV systems

Neighboring-Pixel-Based Maximum Power Point Tracking Algorithm for Partially Shaded Photovoltaic (PV) Systems

In this paper, a neighboring-pixel-based virtual imaging (NPBVI) technique is developed to comprehensively detect the shading conditions on PV arrays. The proposed VI technique is then merged with a probabilistic mechanism of shaded module currents. Finally, a mathematical model is presented, which predicts the current voltage (I-V) region corresponding to the global maximum (GM) of the shaded PV array. The effectiveness of the proposed NPBVI MPPT is validated through numerous experiments that were carried out using a hardware prototype with a 150 W power rating. For the experiments, a PV array consisting of 3 × 2 (Np× Ns ) 20 W PV modules was utilized. The experiments showcase agreement that the proposed method successfully identified the GM region of a partially shaded PV array

Pharmacists’ Perception of the Sale of Non-Clinically Proven Health Supplements in Penang, Malaysia

Purpose: To explore community pharmacists’ perception of the sale of non-clinically proven health supplements and over-the-counter (OTC) products available in Penang, Malaysia.Methods: A cross-sectional survey using a self-completed postal questionnaire was conducted in July 2010 among 200 community pharmacists practicing in Penang Island.Results: Fifty six pharmacists participated in the study (response rate, 28.0 %). A total of 10.7 % respondents indicated that the sale of non-clinically proven products result in high profit. Only 25.0 % of the pharmacists believed that non-clinically proven OTC products are effective, while 35.7 % thought that it is not ethical to sell these products. A majority of the respondents (94.7 %) agreed that manufacturers’ advertisement have a huge effect on positive consumers’ behaviour towards such products. Most respondents agreed that manufacturers of these products claim that their products are effective (57.1 %) and have fewor no side effects (60.7 %).Conclusions: Pharmacists who participated in the study have mixed  opinions on the efficacy and effectiveness of non-clinically proven products. There is a need for pharmacists to be well educated on the  evidence-based use of these products in order to be able to offerappropriate advice to those who come to them to purchase the items.Keywords: Perception, Health promotion, Urban poor, Health supplements

Boosted Antioxidant Effect Using a Combinatory Approach with Essential Oils from Origanum compactum, Origanum majorana, Thymus serpyllum, Mentha spicata, Myrtus communis, and Artemisia herba-alba: Mixture Design Optimization

Several studies have demonstrated the possible synergistic effect as an effective strategy to boost the bioactivity of essential oils. Using this framework, this study was conducted to effectively establish the ideal combination of six essential oils from different plants (Origanum compactum, Origanum majorana, Thymus serpyllum, Mentha spicata, Myrtus communis, and Artemisia herba-alba) that would express the best antioxidant activity. Each mixture was optimized using a mixture design approach to generate the most effective blend. The 2,2-diphenyl-1-picrylhydrazyl radical scavenging method was used as a reference method to assess the antioxidant activity. Each essential oil’s composition was identified using the GC/MS method. The single essential oil activities demonstrated variable antioxidant effects, and following the mixture design approach, the optimal antioxidant blend was revealed, as two mixtures demonstrated the best antiradical activity with 79.46% obtained with the mixture of O. majorana (28%) and M. spicata (71%) and 78.8% obtained with the mixture O. compactum (64%), O. majorana (13%), and T. serpyllum (21%). This study proposes a practical way to elaborate mixtures in the search for a boosting effect that can be oriented for the food or pharmaceutical industry