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Search Results: 1 - 10 of 41 matches for " Shamala "
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Design and Implementation of a Lightweight Security Model to Prevent IEEE 802.11 Wireless DoS Attacks
Malekzadeh Mina,Abdul Ghani AbdulAzim,Subramaniam Shamala
EURASIP Journal on Wireless Communications and Networking , 2011,
Abstract: The protection offered by IEEE 802.11 security protocols such as WEP, WPA, and WPA2 does not govern wireless control frames. The control frames are transmitted in clear-text form, and there is no way to verify their validity by the recipients. The flaw of control frames can be exploited by attackers to carry out DoS attacks and directly disrupt the availability of the wireless networks. In this work, focusing on resource limitation in the wireless networks, a new lightweight noncryptographic security solution is proposed to prevent wireless DoS attacks. In order to prove the ability of the proposed model and quantify its performance and capabilities, a simulation topology is developed, and extensive experiments are carried out. Based on the acquired results, it is concluded that the model successfully prevents wireless DoS attacks, while the security cost is not remarkable compared to the model achievements.
Design of Cyberwar Laboratory Exercises to Implement Common Security Attacks against IEEE 802.11 Wireless Networks
Mina Malekzadeh,Abdul Azim Abdul Ghani,Shamala Subramaniam
Journal of Computer Networks and Communications , 2010, DOI: 10.1155/2010/218271
Abstract: In wireless network communications, radio waves travel through free space; hence, the information reaches any receiving point with appropriate radio receivers. This aspect makes the wireless networks vulnerable to various types of attacks. A true understanding of these attacks provides better ability to defend the network against the attacks, thus eliminating potential threats from the wireless systems. This work presents a series of cyberwar laboratory exercises that are designed for IEEE 802.11 wireless networks security courses. The exercises expose different aspects of violations in security such as confidentiality, privacy, availability, and integrity. The types of attacks include traffic analysis, rogue access point, MAC filtering, replay, man-in-the-middle, and denial of service attacks. For each exercise, the materials are presented as open-source tools along with descriptions of the respective methods, procedures, and penetration techniques. 1. Introduction Wireless networks have gained popularity in many critical areas such as in healthcare centers, hospitals, police departments, military facilities, and airports. Therefore, it is extremely important to enhance the network security in order to protect the information that resides within the network. To achieve this goal, different security protocols have been designed, among which are WEP, WPA, and WPA2. Despite the presence of these protocols, security is still the main concern in the wireless networks. Air transmission is a vulnerable medium, and it provides opportunity for the attackers to intercept the information that will be later used to launch different types of attacks. Consequently, it is important to know different kind of security attacks in order to defend the networks against the attacks and to guarantee the reliability of the wireless networks. Numerous hands-on courses and laboratory exercises have been developed to investigate security flaws in networks and to determine best ways to prevent the attackers from compromising the security of such systems. However, most of the existing laboratory exercises are investigating the wired networks. Meanwhile, most existing wireless laboratory exercises mainly focus on the methods to crack the WEP security protocol [1–4]. In this work, on the contrary, we design a series of laboratory exercises for IEEE 802.11 wireless network security courses. The exercises focus on the types of attacks that have not received much attention in the current wireless laboratories. The laboratory exercises are conducted for students in both graduate and
Inhibition of Dengue Virus Entry and Multiplication into Monocytes Using RNA Interference
Mohammed Abdelfatah Alhoot,Seok Mui Wang,Shamala Devi Sekaran
PLOS Neglected Tropical Diseases , 2011, DOI: 10.1371/journal.pntd.0001410
Abstract: Background Dengue infection ranks as one of the most significant viral diseases of the globe. Currently, there is no specific vaccine or antiviral therapy for prevention or treatment. Monocytes/macrophages are the principal target cells for dengue virus and are responsible for disseminating the virus after its transmission. Dengue virus enters target cells via receptor-mediated endocytosis after the viral envelope protein E attaches to the cell surface receptor. This study aimed to investigate the effect of silencing the CD-14 associated molecule and clathrin-mediated endocytosis using siRNA on dengue virus entry into monocytes. Methodology/Principal Findings Gene expression analysis showed a significant down-regulation of the target genes (82.7%, 84.9 and 76.3% for CD-14 associated molecule, CLTC and DNM2 respectively) in transfected monocytes. The effect of silencing of target genes on dengue virus entry into monocytes was investigated by infecting silenced and non-silenced monocytes with DENV-2. Results showed a significant reduction of infected cells (85.2%), intracellular viral RNA load (73.0%), and extracellular viral RNA load (63.0%) in silenced monocytes as compared to non-silenced monocytes. Conclusions/Significance Silencing the cell surface receptor and clathrin mediated endocytosis using RNA interference resulted in inhibition of the dengue virus entry and subsequently multiplication of the virus in the monocytes. This might serve as a novel promising therapeutic target to attenuate dengue infection and thus reduce transmission as well as progression to severe dengue hemorrhagic fever.
RNA Interference Mediated Inhibition of Dengue Virus Multiplication and Entry in HepG2 Cells
Mohammed Abdelfatah Alhoot, Seok Mui Wang, Shamala Devi Sekaran
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0034060
Abstract: Background Dengue virus-host cell interaction initiates when the virus binds to the attachment receptors followed by endocytic internalization of the virus particle. Successful entry into the cell is necessary for infection initiation. Currently, there is no protective vaccine or antiviral treatment for dengue infection. Targeting the viral entry pathway has become an attractive therapeutic strategy to block infection. This study aimed to investigate the effect of silencing the GRP78 and clathrin-mediated endocytosis on dengue virus entry and multiplication into HepG2 cells. Methodology/Principal Findings HepG2 cells were transfected using specific siRNAs to silence the cellular surface receptor (GRP78) and clathrin-mediated endocytosis pathway. Gene expression analysis showed a marked down-regulation of the targeted genes (87.2%, 90.3%, and 87.8% for GRP78, CLTC, and DNM2 respectively) in transfected HepG2 cells when measured by RT-qPCR. Intracellular and extracellular viral RNA loads were quantified by RT-qPCR to investigate the effect of silencing the attachment receptor and clathrin-mediated endocytosis on dengue virus entry. Silenced cells showed a significant reduction of intracellular (92.4%) and extracellular viral RNA load (71.4%) compared to non-silenced cells. Flow cytometry analysis showed a marked reduction of infected cells (89.7%) in silenced HepG2 cells compared to non-silenced cells. Furthermore, the ability to generate infectious virions using the plaque assay was reduced 1.07 log in silenced HepG2 cells. Conclusions/Significance Silencing the attachment receptor and clathrin-mediated endocytosis using siRNA could inhibit dengue virus entry and multiplication into HepG2 cells. This leads to reduction of infected cells as well as the viral load, which might function as a unique and promising therapeutic agent for attenuating dengue infection and prevent the development of dengue fever to the severe life-threatening DHF or DSS. Furthermore, a decrease of viremia in humans can result in the reduction of infected vectors and thus, halt of the transmission cycle.
Phyllanthus spp. Induces Selective Growth Inhibition of PC-3 and MeWo Human Cancer Cells through Modulation of Cell Cycle and Induction of Apoptosis
Yin-Quan Tang,Indu Bala Jaganath,Shamala Devi Sekaran
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0012644
Abstract: Phyllanthus is a traditional medicinal plant that has been used in the treatment of many diseases including hepatitis and diabetes. The main aim of the present work was to investigate the potential cytotoxic effects of aqueous and methanolic extracts of four Phyllanthus species (P.amarus, P.niruri, P.urinaria and P.watsonii) against skin melanoma and prostate cancer cells.
Studies on the interaction of Schistosoma mansoni and Leishmania major in experimentally infected Balb/c mice
DS Yole, KT Shamala, K Kithome, MM Gicheru
African Journal of Health Sciences , 2007,
Abstract: Schistosoma mansoni and Leishmania major are important tropical human parasites. It is crucial to know the effect of the two infecting man concurrently. Two groups of BALB/c mice were infected with each of the parasites separately; another group was co-infected with both parasites and there was a na ve control. Draining lymph node and spleen cells from mice infected with either of the parasites showed high proliferative responses to their specific parasite antigen. However, crossreactivity occurred between S. mansoni and L.a major. Spleen and Lymph node cells from co-infected group demonstrated high and sustained proliferative responses to schistosome soluble worm antigen preparation and killed Leishmania major antigen, respectively. There was high and sustained IgG levels for both the single and coinfected groups. At 10 weeks post-infection, co-infected mice had significantly larger nodules than mice with L. major infection alone. However, co-infected animals had less severe liver pathology and less enlarged mesenteric lymph nodes than those infected with S. mansoni only. This work shows that co-infection results in two different outcomes: protection against S. mansoni and exacerbated pathogy in L. major. We suggest that cellular responses possibly protect against S. mansoni , while high IgG levels lead to exacerbated L. majorresponse. African Journal of Health Sciences Vol. 14 (1-2) 2007: pp. 80-85
Preliminary Studies on the Development of Monoclonal Antibodies Against Mycelia of Ganoderma boninense, the Causal Pathogen of Basal Stem Rot of Oil Palm
Shamala, S.,Chris, D.,Sioban, O.,Idris, A. S.
Malaysian Journal of Microbiology , 2006,
Abstract: This study aimed to raise specific MAbs against G. boninense, the causal pathogen of basal stem rot (BSR) of oil palm. Crude mycelium extract of G. boninense was used as immunogen to generate MAbs. Mycelium was harvested from liquid culture and freeze-dried followed by re-suspension in phosphate buffer saline (PBS). Two 10-week old BALB-C mice were immunized with the mycelial extract. The mice were boosted once before harvesting their spleens for fusion. The MAbs were fused with myeloma cells from BALB-C mice. Initial screening was carried out using plate-trapped antigen enzyme-linked immunosorbent assay (PTA-ELISA) with mycelial immunogen of G. boninense. The MAbs with positive signals were verified via secondary screening and cloned for cross-reactivity test. Cross-reactivity testing was carried out with 2 other fungi namely; Trichoderma and Botrytis along with 2 different species of Ganoderma commonly found in oil palm plantations namely; G. zonatum, and G. miniatocinctum. This study found that the MAbs raised against G. boninense were not specific as the MAbs gave positive signals through the cross-reactivity test with all fungi tested in the cross-reactivity. Future work would be using these MAbs in a co-immunization program whereby the generated Ganoderma sp generic monoclonal antibody will be pre-mixed with the G. boninense mycelium immunogen to allow reduction in the potential cross-reactivity of newly generated antibodies with Ganoderma sp. Our efforts are also currently directed at optimizing the immunogen preparation for the production of MAbs specific to G. boninense.
Frame Aggregation in Wireless Networks: Techniques and Issues
Saif Anwar,Othman Mohamed,Subramaniam Shamala,Abdul Hamid Nor
IETE Technical Review , 2011,
Abstract: The timing and headers overheads of IEEE 802.11 PHY and MAC layers consume a large part of the channel time leading to performance degradation especially at higher data rates. Several enhancements at both the PHY and MAC layers have been proposed in order to reduce these overheads and increase the channel utilization. A key enhancement is frame aggregation in which the timing and headers overheads are reduced by aggregating multiple frames into a single large frame and then transmit it in a single channel access. This paper addresses the frame aggregation techniques that have been proposed for the next generation wireless networks and the aggregation techniques that are adopted by IEEE 802.11n standard. It also highlights the aggregation issues that need to be investigated in order to further enhance the frame aggregation performance.
The Delay with New-Additive Increase Multiplicative Decrease Congestion Avoidance and Control Algorithm
Hayder Natiq Jasem,Zuriati Ahmad Zukarnain,Mohamed Othman,Shamala Subramaniam
Information Technology Journal , 2010,
Abstract: As the Internet becomes increasingly heterogeneous, the issue of congestion control becomes ever more important. And the queue length and end-to-end (congestion) delays are some of the important things in term of congestion avoidance and control mechanisms. In this research we continued to study the performances of the New-Additive Increase Multiplicative Decrease (AIMD) algorithm as one of the core protocols for TCP congestion avoidance and control mechanism, we want now to evaluate the effect of using the New-AIMD algorithm to measure the queue length and end-to-end delays and we will use the NCTUns simulator to get the results after make the modification of the mechanism. And we will use the Droptail mechanism as Active Queue Management (AQM) in the bottleneck router. After implementation of our new approach with different number of flows, we will measure the delay for two types of delays (queuing delay and end-to-end delay), we expect the delay will be less with using our mechanism comparing with the mechanism in the previous study. Now and after got this results as low delay for bottleneck link case, we know the New-AIMD mechanism work as well under the network condition in the experiments.
Simple Post Quantum Scheme for Higher Key Rate Multiparty Quantum Key Distribution
Abudhahir Buhari,Zuriati Ahmad Zukarnain,Shamala K. Subramaniam,Hisham Zainuddin
International Journal of Network Security & Its Applications , 2012,
Abstract: We propose a multi-party quantum key distribution protocol which enables all the receivers can converttheir respective private shared key into common secret key without use of entanglement. The maincomponent of our protocol is a simple post quantum scheme for achieving the higher secret key rate.Efficiency of the extracted key rate is almost 100%. We assume that sender established the pre-sharedprivate secret keys and a common secret number with the receivers. Our proposed scheme sends n stringsof number to n receivers in the public channel to convert their respective shared secret key into commonsecret key in the presence of Eve. We also analyze the complexity of attack by the adversary to guess thesecret key
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