With the increasing demand of mobility and ad hoc networking, vulnerability of wireless networks ... more With the increasing demand of mobility and ad hoc networking, vulnerability of wireless networks is also becoming a crucial issue. This dissertation sheds light on the security features of wireless communication, and proposes a model with an increased integration of security features. The proposed model, a ranked neighbor discovery (RND), and a security adaptive ad-hoc on-demand distance vector (SA-AODV) routing protocol suite lays out the percept of solution for the security issues, which includes the neighbor discovery, as well as the routing protocol for transmission. The neighbor discovery phase consists of the determination of trusted neighbors, based on distance metrics, leading to a process of trust ranking. The routing protocol, using the fact of the trusted neighbors, and the required security level, then sets up a security adapted route from the source to its destination. The main advantage of this protocol pair would be the achievement to obtain a route with a user-defined level of security for a specific application. The two protocols thus provide the anchor to a package for a total solution for a secured environment for wireless transmission with an increased integration of security features.
MultiPoint Relay (MPR) selection algorithm is a flooding technique for propagating a broadcast me... more MultiPoint Relay (MPR) selection algorithm is a flooding technique for propagating a broadcast message inside an ad-hoc network which reduces the number of unnecessary broadcast messages in order to save more energy in the network, minimize the number of packet collisions, and speed up the propagation time. In this paper, we demonstrate that MPR selection is an application of Set Covering Problem (SCP). A few optimization methods are developed in this work to find the optimum solution including Simulated Annealing (SA), Tabu Search (TS), Genetic Algorithm (GA), and a new greedy algorithm. Extensive simulations are set up to evaluate the developed methods. The new algorithm is named Energy eFficient MPR or EF-MPR in short. The simulation results show that EF-MPR can reduce the number of MPR nodes up to 19%. Moreover, EF-MPR algorithm reduces the power-consumption of network up to 12% and speed up the propagation time by 9%.
Mincut-based partitioning[4] is a technique to decompose a net-work into two subnetworks so that ... more Mincut-based partitioning[4] is a technique to decompose a net-work into two subnetworks so that the size of each subnetwork is bounded and the size of the net cutset, the number of nets that connect to cells in both subnetworks, is minimized. The Fiduccia and Mattheyses ( FM ...
Statistical database management systems keep raw, elementary and/or aggregated data and include q... more Statistical database management systems keep raw, elementary and/or aggregated data and include query languages with facilities to calculate various statistics from this data. In this article we examine statistical database query languages with respect to the criteria identified and taxonomy developed in Ozsoyoglu and Ozsoyoglu (1985b). The criteria include statistical metadata and objects, aggregation features and interface to statistical packages. The taxonomy of statistical database query languages classifies them with respect to the data model used, the type of user interface and method of implementation. Temporal databases are rich sources of data for statistical analysis. Aggregation features of temporal query languages, as well as the issues in calculating aggregates from temporal data, are also examined.
Artificial Bee Colony (ABC) is a population-based algorithm that employed the natural metaphors, ... more Artificial Bee Colony (ABC) is a population-based algorithm that employed the natural metaphors, based on foraging behavior of honey bee swarm. In ABC algorithm, there are three categories of bees. Employed bees select a random solution and apply a random neighborhood structure (exploration process), onlooker bees choose a food source depending on a selection strategy (exploitation process), and scout bees involves to search for new food sources (scouting process). In this paper, firstly we introduce a disruptive selection strategy for onlooker bees, to improve the diversity of the population and the premature convergence, and also a local search (i.e. simulated annealing) is introduced, in order to attain a balance between exploration and exploitation processes. Furthermore, a self adaptive strategy for selecting neighborhood structures is added to further enhance the local intensification capability. Experimental results show that the hybrid ABC with disruptive selection strategy outperforms the ABC algorithm alone when tested on examination timetabling problems.
Today, the publication of microdata poses a privacy threat: anonymous personal records can be re-... more Today, the publication of microdata poses a privacy threat: anonymous personal records can be re-identified using third data sources. Past research has tried to develop a concept of privacy guarantee that an anonymized data set should satisfy before publication, culminating in the notion of t-closeness. To satisfy t-closeness, the records in a data set need to be grouped into Equivalence Classes (ECs), such that each EC contains records of indistinguishable quasi-identifier values, and its local distribution of sensitive attribute (SA) values conforms to the global table distribution of SA values. However, despite this progress, previous research has not offered an anonymization algorithm tailored for t-closeness. In this paper, we cover this gap with SABRE, a SA Bucketization and REdistribution framework for t-closeness. SABRE first greedily partitions a table into buckets of similar SA values and then redistributes the tuples of each bucket into dynamically determined ECs. This approach is facilitated by a property of the Earth Mover’s Distance (EMD) that we employ as a measure of distribution closeness: If the tuples in an EC are picked proportionally to the sizes of the buckets they hail from, then the EMD of that EC is tightly upper-bounded using localized upper bounds derived for each bucket. We prove that if the t-closeness constraint is properly obeyed during partitioning, then it is obeyed by the derived ECs too. We develop two instantiations of SABRE and extend it to a streaming environment. Our extensive experimental evaluation demonstrates that SABRE achieves information quality superior to schemes that merely applied algorithms tailored for other models to t-closeness, and can be much faster as well.
The Dictyostelium discoideum homolog of mammalian cyclin dependent kinase 5 (Cdk5) has previously... more The Dictyostelium discoideum homolog of mammalian cyclin dependent kinase 5 (Cdk5) has previously been shown to be required for optimal growth and differentiation in this model organism, however, the subcellular localization of the protein has not previously been studied. In this study, immunolocalizations and a GFP fusion construct localized Cdk5 predominantly to the nucleus of vegetative cells. Western blots showed that Cdk5 was present in both nuclear and non-nuclear fractions, suggesting a functional role in both cellular locales. During the early stages of mitosis, Cdk5 gradually moved from a punctate nucleoplasmic distribution to localize adjacent to the inner nuclear envelope. During anaphase and telophase, Cdk5 localized to the cytoplasm and was not detected in the nucleoplasm. Cdk5 returned to the nucleus during cytokinesis. Proteolytic activity has been shown to be a critical regulator of the cell cycle. Immunoprecipitations coupled with immunolocalizations identified puromycin-sensitive aminopeptidase A (PsaA) as a potential Cdk5 binding partner in Dictyostelium. Immunoprecipitations also identified two phosphotyrosine proteins (35 and 18 kDa) that may interact with Cdk5 in vivo. Together, this work provides new insight into the localization of Cdk5, its function during cell division, and its binding to a proteolytic enzyme in Dictyostelium.
With the increasing demand of mobility and ad hoc networking, vulnerability of wireless networks ... more With the increasing demand of mobility and ad hoc networking, vulnerability of wireless networks is also becoming a crucial issue. This dissertation sheds light on the security features of wireless communication, and proposes a model with an increased integration of security features. The proposed model, a ranked neighbor discovery (RND), and a security adaptive ad-hoc on-demand distance vector (SA-AODV) routing protocol suite lays out the percept of solution for the security issues, which includes the neighbor discovery, as well as the routing protocol for transmission. The neighbor discovery phase consists of the determination of trusted neighbors, based on distance metrics, leading to a process of trust ranking. The routing protocol, using the fact of the trusted neighbors, and the required security level, then sets up a security adapted route from the source to its destination. The main advantage of this protocol pair would be the achievement to obtain a route with a user-defined level of security for a specific application. The two protocols thus provide the anchor to a package for a total solution for a secured environment for wireless transmission with an increased integration of security features.
MultiPoint Relay (MPR) selection algorithm is a flooding technique for propagating a broadcast me... more MultiPoint Relay (MPR) selection algorithm is a flooding technique for propagating a broadcast message inside an ad-hoc network which reduces the number of unnecessary broadcast messages in order to save more energy in the network, minimize the number of packet collisions, and speed up the propagation time. In this paper, we demonstrate that MPR selection is an application of Set Covering Problem (SCP). A few optimization methods are developed in this work to find the optimum solution including Simulated Annealing (SA), Tabu Search (TS), Genetic Algorithm (GA), and a new greedy algorithm. Extensive simulations are set up to evaluate the developed methods. The new algorithm is named Energy eFficient MPR or EF-MPR in short. The simulation results show that EF-MPR can reduce the number of MPR nodes up to 19%. Moreover, EF-MPR algorithm reduces the power-consumption of network up to 12% and speed up the propagation time by 9%.
Mincut-based partitioning[4] is a technique to decompose a net-work into two subnetworks so that ... more Mincut-based partitioning[4] is a technique to decompose a net-work into two subnetworks so that the size of each subnetwork is bounded and the size of the net cutset, the number of nets that connect to cells in both subnetworks, is minimized. The Fiduccia and Mattheyses ( FM ...
Statistical database management systems keep raw, elementary and/or aggregated data and include q... more Statistical database management systems keep raw, elementary and/or aggregated data and include query languages with facilities to calculate various statistics from this data. In this article we examine statistical database query languages with respect to the criteria identified and taxonomy developed in Ozsoyoglu and Ozsoyoglu (1985b). The criteria include statistical metadata and objects, aggregation features and interface to statistical packages. The taxonomy of statistical database query languages classifies them with respect to the data model used, the type of user interface and method of implementation. Temporal databases are rich sources of data for statistical analysis. Aggregation features of temporal query languages, as well as the issues in calculating aggregates from temporal data, are also examined.
Artificial Bee Colony (ABC) is a population-based algorithm that employed the natural metaphors, ... more Artificial Bee Colony (ABC) is a population-based algorithm that employed the natural metaphors, based on foraging behavior of honey bee swarm. In ABC algorithm, there are three categories of bees. Employed bees select a random solution and apply a random neighborhood structure (exploration process), onlooker bees choose a food source depending on a selection strategy (exploitation process), and scout bees involves to search for new food sources (scouting process). In this paper, firstly we introduce a disruptive selection strategy for onlooker bees, to improve the diversity of the population and the premature convergence, and also a local search (i.e. simulated annealing) is introduced, in order to attain a balance between exploration and exploitation processes. Furthermore, a self adaptive strategy for selecting neighborhood structures is added to further enhance the local intensification capability. Experimental results show that the hybrid ABC with disruptive selection strategy outperforms the ABC algorithm alone when tested on examination timetabling problems.
Today, the publication of microdata poses a privacy threat: anonymous personal records can be re-... more Today, the publication of microdata poses a privacy threat: anonymous personal records can be re-identified using third data sources. Past research has tried to develop a concept of privacy guarantee that an anonymized data set should satisfy before publication, culminating in the notion of t-closeness. To satisfy t-closeness, the records in a data set need to be grouped into Equivalence Classes (ECs), such that each EC contains records of indistinguishable quasi-identifier values, and its local distribution of sensitive attribute (SA) values conforms to the global table distribution of SA values. However, despite this progress, previous research has not offered an anonymization algorithm tailored for t-closeness. In this paper, we cover this gap with SABRE, a SA Bucketization and REdistribution framework for t-closeness. SABRE first greedily partitions a table into buckets of similar SA values and then redistributes the tuples of each bucket into dynamically determined ECs. This approach is facilitated by a property of the Earth Mover’s Distance (EMD) that we employ as a measure of distribution closeness: If the tuples in an EC are picked proportionally to the sizes of the buckets they hail from, then the EMD of that EC is tightly upper-bounded using localized upper bounds derived for each bucket. We prove that if the t-closeness constraint is properly obeyed during partitioning, then it is obeyed by the derived ECs too. We develop two instantiations of SABRE and extend it to a streaming environment. Our extensive experimental evaluation demonstrates that SABRE achieves information quality superior to schemes that merely applied algorithms tailored for other models to t-closeness, and can be much faster as well.
The Dictyostelium discoideum homolog of mammalian cyclin dependent kinase 5 (Cdk5) has previously... more The Dictyostelium discoideum homolog of mammalian cyclin dependent kinase 5 (Cdk5) has previously been shown to be required for optimal growth and differentiation in this model organism, however, the subcellular localization of the protein has not previously been studied. In this study, immunolocalizations and a GFP fusion construct localized Cdk5 predominantly to the nucleus of vegetative cells. Western blots showed that Cdk5 was present in both nuclear and non-nuclear fractions, suggesting a functional role in both cellular locales. During the early stages of mitosis, Cdk5 gradually moved from a punctate nucleoplasmic distribution to localize adjacent to the inner nuclear envelope. During anaphase and telophase, Cdk5 localized to the cytoplasm and was not detected in the nucleoplasm. Cdk5 returned to the nucleus during cytokinesis. Proteolytic activity has been shown to be a critical regulator of the cell cycle. Immunoprecipitations coupled with immunolocalizations identified puromycin-sensitive aminopeptidase A (PsaA) as a potential Cdk5 binding partner in Dictyostelium. Immunoprecipitations also identified two phosphotyrosine proteins (35 and 18 kDa) that may interact with Cdk5 in vivo. Together, this work provides new insight into the localization of Cdk5, its function during cell division, and its binding to a proteolytic enzyme in Dictyostelium.
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Papers by Abdullah Sa'ad