On Resource Allocation for Communication Systems with Delay and Secrecy Constraints

This dissertation studies fundamental limits of modern digital communication systems in presence/absence of delay and secrecy constraints. In the first part of this dissertation, we consider a typical time-division wireless communication system wherein the channel strengths of the wireless users vary with time with a power constraint at the base station and which is not subject to any delay constraint. The objective is to allocate resources to the wireless users in an equitable manner so as to achieve a specific throughput. This problem has been looked at in different ways by previous researchers. We address this problem by developing a systematic way of designing scheduling schemes that can achieve any point on the boundary of the rate region. This allows us to map a desired throughput to a specific scheduling scheme which can then be used to service the wireless users. We then propose a simple scheme by which users can cooperate and then show that a cooperative scheduling scheme enlarges the achievable rate region. A simple iterative algorithm is proposed to find the resource allocation parameters and the scheduling scheme for the cooperative system. In the second part of the dissertation, a downlink time-division wireless sys- tem that is subject to a delay constraint is studied, and the rate region and optimal scheduling schemes are derived. The result of this study concludes that the achievable throughput of users decrease as the delay constraint is increased. Next, we consider a problem motivated by cognitive radio applications which has been proposed as a means to implement efficient reuse of the licensed spectrum. Previous research on this topic has focussed largely on obtaining fundamental limits on achievable throughput from a physical layer perspective. In this dissertation, we study the impact of im- posing Quality of Service constraints (QoS) on the achievable throughput of users. The result of this study gives insights on how the cognitive radio system needs to be operated in the low and high QoS constraint regime. Finally, the third part of this dissertation is motivated by the need for commu- nicating information not only reliably, but also in a secure manner. To this end, we study a source coding problem, wherein multiple sources needs to be communicated to a receiver with the stipulation that there is no direct channel from the transmitter to the receiver. However, there are many \agents" that can help carry the information from the transmitter to the receiver. Depending on the reliability that the transmit- ter has on each of the agents, information is securely encoded by the transmitter and given to the agents, which will be subsequently given to the receiver. We study the overhead that the transmitter has to incur for transmitting the information to the receiver with the desired level of secrecy. The rate region for this problem is found and simple achievable schemes are proposed. The main result is that, separate secure coding of sources is optimal for achieving the sum-rate point for the general case of the problem and the rate region for simple case of this problem

Padina boergessenii ameliorates carbon tetrachloride induced nephrotoxicity in Wistar rats

AbstractThis research investigates the ameliorative effect of brown alga Padina boergessenii against CCl4-induced nephrotoxicity in rats. Twenty-four Wistar albino rats were divided into four groups as follows: control group (saline), CCl4 group, CCl4+P. boergessenii extract group and P. boergessenii extract alone group. At the end of the experimental period, the animals are sacrificed and tissue samples (kidney) were collected. CCl4 at a dose of 2mL/kg, administered subcutaneously, produced significantly decreased activities of glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), and catalase (CAT). Histopathological examinations showed massive centrilobular necrosis and fat accumulation in CCl4-induced animals. In the protective test, especially in animals pretreated with P. boergessenii (150mg/kg) extract, there was a significant increase in antioxidant enzyme levels although there was no sign of abnormality in the kidney of rats pretreated with extract as evidenced by histopathological sections against CCl4-induced decrease of lipid peroxidation (TBARS). The ameliorative effect may be due to the presence of various bioactive compounds in alga. These results suggest that an extract of P. boergessenii is able to significantly alleviate the nephrotoxicity induced by CCl4 in Wistar rats

Mineral Composition of Marine Macroalgae from Mandapam Coastal Regions; Southeast Coast of India

The present study focused on the trace metal and mineral composition analysis of various seaweeds such as Chlorophyceae (Cladophora glomerata, Ulva reticulata, Halimeda macroloba, H.tuna), Phaeophyceae (Dictyota dichotoma, Padina pavonica) Rhodophyceae (Gracilaria crassa, Gelidiella acerosa, Hypnea musciformis) collected from Mandapam coastal regions, Southeast coast of India. Among these groups of seaweeds, U. reticulata belonging to the Chlorophyceae showed the maximum contents of mineral elements such as chromium, copper, and magnesium. H.tuna observed the minimum level of mineral content such as cobalt, iron, magnesium, manganese, nickel, lead and zinc

Monitoring of Noctiluca Bloom in Mandapam and Keelakarai Coastal Waters; Southeast Coast of India

Monitoring the Harmful Algal Blooms was carried out during July to December 2008 in Mandapam and Keelakarai coastal waters of Tamil Nadu, Southeast coast of India. In the month of October several fishes and shellfishes were died due to Noctiluca blooms along these two areas. The present investigation the following species of phyto and zooplankton were found to be common; phytoplankton such as Coscinodiscus sp., Skeletonema costatum, Bacillaria paradoxa, Thallassiothrix frauenfeldii, T. longisima, Leptocylindrus sp., and  zooplankton such as Paracalanus parvus, Acrocalanus gracilis, Pseudodiaptomus serricautatus, Rhincalanus cornutus, R. nasutus, Euterpina acutifrons, Nannocalanus minor, Eucalanus attenuates, E. crassus, Fish larvae, Fish eggs, Barnacle nauplii, Bivalve larvae, Gastropod larvae, Copepod nauplii  and Mysis larvae. The hydrobiological parameters also analysed during bloom and after blooms; the dissolved oxygen (2.6 – 4.9µM L-1) nutrients varied between nitrate (0.66 – 1.01µM L-1) nitrite (0.11 – 0.21µM L-1) phosphate (0.51 – 0.86µM L-1) and silicate (0.81 – 4.2µM L-1)

Antimicrobial activities of the lichen <i style="">Roccella belangeriana </i>(Awasthi) from mangroves of Gulf of Mannar

449-453The present study, attempted to test antimicrobial activity of the mangrove lichen Roccella belangeriana collected from the Gulf of Mannar Biosphere Reserve area. The lichen was extracted in different solvents: acetone, methanol, diethylether, ethanol, ethyl acetate, petroleum ether, chloroform and water and tested against 14 bacterial strains and 3 fungal strains by well diffusion assay. Regarding antibacterial activity the maximum zone of inhibition was recorded in methanol extracts against Vibrio cholerae and the minimum zone of inhibition was in ethyl acetate extract against Klebsiella pneumoniae, Enterococci sp., Salmonella sp. and Shewanella sp. Regarding the antifungal activity, the maximum zone of inhibition was recorded against Aspergillus niger, and the minimum was noted against Rhizophus sp

A Multi-Space Approach to Zero-Shot Object Detection

Object detection has been at the forefront for higher level vision tasks such as scene understanding and contextual reasoning. Therefore, solving object detection for a large number of visual categories is paramount. Zero-Shot Object Detection (ZSD) – where training data is not available for some of the target classes – provides semantic scalability to object detection and reduces dependence on large amount of annotations, thus enabling a large number of applications in real-life scenarios. In this paper, we propose a novel multi-space approach to solve ZSD where we combine predictions obtained in two different search spaces. We learn the projection of visual features of proposals to the semantic embedding space and class labels in the semantic embedding space to visual space. We predict similarity scores in the individual spaces and combine them. We present promising results on two datasets, PASCAL VOC and MS COCO. We further discuss the problem of hubness and show that our approach alleviates hubness with a performance superior to previously proposed methods

A Multi-Space Approach to Zero-Shot Object Detection

Object detection has been at the forefront for higher level vision tasks such as scene understanding and contextual reasoning. Therefore, solving object detection for a large number of visual categories is paramount. Zero-Shot Object Detection (ZSD) - where training data is not available for some of the target classes - provides semantic scalability to object detection and reduces dependence on large amount of annotations, thus enabling a large number of applications in real-life scenarios. In this paper, we propose a novel multi-space approach to solve ZSD where we combine predictions obtained in two different search spaces. We learn the projection of visual features of proposals to the semantic embedding space and class labels in the semantic embedding space to visual space. We predict similarity scores in the individual spaces and combine them. We present promising results on two datasets, PASCAL VOC and MS COCO. We further discuss the problem of hubness and show that our approach alleviates hubness with a performance superior to previously proposed methods

Morphological Evolution of Nanocluster Aggregates and Single Crystals in Alkaline Zinc Electrodeposition

The morphology of Zn electrodeposits is studied on carbon-coated transmission electron microscopy grids. At low overpotentials (η = −50 mV), the morphology develops by aggregation at two distinct length scales: ∼5 nm diameter monocrystalline nanoclusters form ∼50 nm diameter polycrystalline aggregates, and the aggregates form a branched network. Epitaxial (000̅2) growth above an overpotential of |η_c| > 125 mV leads to the formation of hexagonal single crystals up to 2 μm in diameter. Potentiostatic current transients were used to calculate the nucleation rate from Scharifker et al.’s model. The exp­(η) dependence of the nucleation rates indicates that atomistic nucleation theory explains the nucleation process better than Volmer–Weber theory. A kinetic model is provided using the rate equations of vapor solidification to simulate the evolution of the different morphologies. On solving these equations, we show that aggregation is attributed to cluster impingement and cluster diffusion while single-crystal formation is attributed to direct attachment

Clinical Prevalence and Associated Factors of Erectile Dysfunction in Patients Undergoing Haemodialysis

ANNALS ACADEMY OF MEDICINE SINGAPORE47278-8