This paper examines the feasibility of implementing video trapdoor-based client puzzle in the current Internet protocol as a strategy to reduce or eliminate the severity of DoS attacks. The study attempts to determine whether trapdoor-based client puzzle is computationally efficient and applicable to the current Internet protocol, and to investigate the security, practicality, and feasibility of visual trapdoor-based client puzzle scheme. The findings demonstrate the feasibility of the proposed model considering the computation cost, security, and implementation in existing infrastructure.
In non-cooperative environments such as ad hoc, nodes may deviate from following the standard medium access protocol CSMA/CA to obtain an unfair bandwidth share. This will severely degrade the performance of the normal nodes and the performance of the network as well. In this paper, we define the MAC layer misbehavior in IEEE 802.11 in ad hoc networks. We also conduct a simulation in order to show the impact of adopting such behavior in a network. Moreover, a review of several detection schemes proposed in the literature to detect the selfish nodes is highlighted.
Adsorption of dyes as a remediation technique for dye-loaded wastewater remains an area of interest. Adsorption using bio-derived, renewable sorbent materials can be seen as environmentally friendly, trouble-free, commercially cheap operation. The main objective of this work is adsorption of Crystal Violet (CV) and Nile Blue (NB) dyes on activated carbon derived from date palm leaf wastes. For this purpose, activated carbon was prepared via chemical treatment of palm leaf wastes with H2SO4, H3PO4, and HNO3, respectively, with subsequent carbonization through thermal treatment. Dye adsorption studies were carried out under different conditions, and the influence of different parameters such as temperature, time, pH, dye concentration, dose and particle size of activated carbon (AC) was investigated in batch experiments. Furthermore, dynamic sorption experiments were performed successively. The present study found AC from date palm leaves to be a promising low cost adsorbent to remove CV and NB from aqueous solutions.
Microwave assisted synthesis methods guided by the principles of green chemistry has been employed to synthesize a series of 2-mercaptopyridines (3a-j) and their related glycosides (9a-j). By comparison with traditional conditions, microwave irradiation provides a powerful tool that leads to rise yields and minimize reaction time. Chemical structures of the new products were confirmed on the basis of their elemental analysis and spectroscopic data (FT-IR, 1D, 2D-NMR) as well as alternative synthetic routes. The activity against a verity of cancer cells and different bacteria strains has been studied.
Enzyme-based degradation of organic pollutants is a promising remediation approach due to the promiscuous nature of the technique and the wide range of available enzymes. Oxidoreductases, specifically, peroxidases are the most popular class of enzymes that have been used for the degradation of organic pollutants. However, it is generously assumed that all peroxidases behave similarly and produce similar degradation products. In the present study, we have carried out detailed degradation studies on a model thiazole compound (Thioflavin T dye) using two of the most commonly used peroxidases - Soybean peroxidase (SBP) and Chloroperoxidase (CPO). Our studies show that these two enzymes have very different optimum conditions for the decoloration of Thioflavin T such as their needs to redox mediator, H2O2 tolerance and thermal stabilities. The results show that the two peroxidases have different optimum reactions conditions, suggesting that SBP and CPO behave differently in organic pollutants degradation.
Habitat loss and, increased predator and hunting, threats, negatively impact the populations of Socotra cormorants, Phalacrocorax nigrogularis, in UAE islands. Habitat loss and fragmentation reduces connectivity among wildlife populations and ultimately could drive populations to extinction. Such isolated populations are known to suffer from reduced genetic diversity that can limit the species' evolutionary potential resulting in inbreeding depression. The dearth of information, increased threats, and reduced breeding colony size, warrants an urgent investigation of the Socotra Cormorant population in the UAE. The aim of this research is to investigate the subpopulation structure of this regionally endemic seabird in the UAE, using molecular population genetic analysis. Understanding the genetic structure of the cormorants' subpopulations could (i) improve the conservation management efforts and(ii) help to predict future population status and viability.
This study aims to determine the climatology of cloudiness over the Arabian Peninsula. Time series of total, high, middle and low cloud amounts from the International Satellite Cloud Climatology Project (ISCCP) database from 1983 through 2009 are analyzed. Initial results show significant decreasing trends in the total and low cloud amounts, at a 95% confidence interval. Significant correlations are found for the cloud amounts and total column water vapor. Inferred cloudiness data is compared to in situ rainfall measurements across the UAE, for the same time period. Significant correlation is present for average rainfall over the UAE and total, middle and low cloud amounts. Total cloud amounts over the UAE in the seasons of fall, winter and spring exhibit decreasing trends, at a 95% confidence interval.
Desalination plays a central role in the UAE's economy and water security aspects. Membrane based Desalination techniques are a promising alternative to conventional flash distillation, but are afflicted with biofouling, which is currently not fully understood. Recent advances in biotechnology have enabled the characterization of biofouling biofilms through marker gene (16S rRNA) profiling. We here strive to see an emerging pattern in biofouling processes through a multi-study meta-analysis of 16S rRNA profiles. For the first time we compare microbial communities in biofouling in the region and contextualize by global samples. As a result, we observe a strong variance amongst Reverse Osmosis and other biofouling membranes across different studies, suggesting that biofilm formation in desalination is driven by complex environmental and random forces. Yet, we could identify the least common denominators for biofilm formation, which in turn can inform anti-fouling strategies.
Coral reefs of the Arabian Gulf are subject to several pressures, thus requiring conservation actions. Well-designed conservation plans involve efficient mapping and monitoring systems. Satellite remote sensing is a cost-effective tool for seafloor mapping at large scales. Multispectral remote sensing of coastal habitats, like those of the Arabian Gulf, presents a special challenge due to their complexity and heterogeneity. The present study evaluates the potential of multispectral sensor DubaiSat-2 in mapping benthic communities of United Arab Emirates. We propose to use a spectral-spatial method that includes multilevel segmentation, nonlinear feature analysis and ensemble learning methods. Support Vector Machine (SVM) is used for comparison of classification performances. Comparative data were derived from the habitat maps published by the Environment Agency-Abu Dhabi. The spectral-spatial method produced 96.41% mapping accuracy. SVM classification is assessed to be 94.17?curate. The adaptation of these methods can help achieving well-designed coastal management plans in the region.
Ground deformation phenomena occur in many regions due to groundwater resources depletion caused by their excessive exploitation. For the past fifteen years groundwater is massively extracted in the Al Ain region, but the aquifer is also artificially recharged. SAR interferometry is one of the few techniques that can provide estimations of the land surface displacements with millimeter accuracy in large scales. In this study the two-pass interferometry method was applied in the city of Al Ain with the use of ENVISAT satellite images by composing interferometric pairs based on the perpendicular and temporal baselines of the scenes. From these pairs a series of Line- Of-Sight displacement maps were produced depicting the surface displacements at independent time intervals with the use of NEST/Sentinel1-toolbox/SNAP software. Using the same criteria small single-reference stacks were implemented in order to estimate the surface LOS movement velocities with partial elimination of noise and atmospheric error components.
