| Abstract: | The resurgence of the enteric pathogen Vibrio cholerae, the causative organism of epidemic cholera, remains a major health problem in many developing countries like India. The southern Indian state of Kerala is endemic to cholera. The outbreaks of cholera follow a seasonal pattern in regions of endemicity. Marine aquaculture settings and mangrove environments of Kerala serve as reservoirs for V. cholerae. The non-O1/non-O139 environmental isolates of V. cholerae with incomplete ‘virulence casette’ are to be dealt with caution as they constitute a major reservoir of diverse virulence genes in the marine environment and play a crucial role in pathogenicity and horizontal gene transfer. The genes coding cholera toxin are borne on, and can be infectiously transmitted by CTXΦ, a filamentous lysogenic vibriophages. Temperate phages can provide crucial virulence and fitness factors affecting cell metabolism, bacterial adhesion, colonization, immunity, antibiotic resistance and serum resistance. The present study was an attempt to screen the marine environments like aquafarms and mangroves of coastal areas of Alappuzha and Cochin, Kerala for the presence of lysogenic V. cholerae, to study their pathogenicity and also gene transfer potential. Phenotypic and molecular methods were used for identification of isolates as V. cholerae. The thirty one isolates which were Gram negative, oxidase positive, fermentative, with or without gas production on MOF media and which showed yellow coloured colonies on TCBS (Thiosulfate Citrate Bile salt Sucrose) agar were segregated as vibrios. Twenty two environmental V. cholerae strains of both O1 and non- O1/non-O139 serogroups on induction with mitomycin C showed the presence of lysogenic phages. They produced characteristic turbid plaques in double agar overlay assay using the indicator strain V. cholerae El Tor MAK 757. PCR based molecular typing with primers targeting specific conserved sequences in the bacterial genome, demonstrated genetic diversity among these lysogen containing non-O1 V. cholerae . Polymerase chain reaction was also employed as a rapid screening method to verify the presence of 9 virulence genes namely, ctxA, ctxB, ace, hlyA, toxR, zot,tcpA, ninT and nanH, using gene specific primers. The presence of tcpA gene in ALPVC3 was alarming, as it indicates the possibility of an epidemic by accepting the cholera. Differential induction studies used ΦALPVC3, ΦALPVC11, ΦALPVC12 and ΦEKM14, underlining the possibility of prophage induction in natural ecosystems, due to abiotic factors like antibiotics, pollutants, temperature and UV. The efficiency of induction of prophages varied considerably in response to the different induction agents. The growth curve of lysogenic V. cholerae used in the study drastically varied in the presence of strong prophage inducers like antibiotics and UV. Bacterial cell lysis was directly proportional to increase in phage number due to induction. Morphological characterization of vibriophages by Transmission Electron Microscopy revealed hexagonal heads for all the four phages. Vibriophage ΦALPVC3 exhibited isometric and contractile tails characteristic of family Myoviridae, while phages ΦALPVC11 and ΦALPVC12 demonstrated the typical hexagonal head and non-contractile tail of family Siphoviridae. ΦEKM14, the podophage was distinguished by short non-contractile tail and icosahedral head. This work demonstrated that environmental parameters can influence the viability and cell adsorption rates of V. cholerae phages. Adsorption studies showed 100% adsorption of ΦALPVC3 ΦALPVC11, ΦALPVC12 and ΦEKM14 after 25, 30, 40 and 35 minutes respectively. Exposure to high temperatures ranging from 50ºC to 100ºC drastically reduced phage viability. The optimum concentration of NaCl required for survival of vibriophages except ΦEKM14 was 0.5 M and that for ΦEKM14 was 1M NaCl. Survival of phage particles was maximum at pH 7-8. V. cholerae is assumed to have existed long before their human host and so the pathogenic clones may have evolved from aquatic forms which later colonized the human intestine by progressive acquisition of genes. This is supported by the fact that the vast majority of V. cholerae strains are still part of the natural aquatic environment. CTXΦ has played a critical role in the evolution of the pathogenicity of V. cholerae as it can transmit the ctxAB gene. The unusual transformation of V. cholerae strains associated with epidemics and the emergence of V. cholera O139 demonstrates the evolutionary success of the organism in attaining greater fitness. Genetic changes in pathogenic V. cholerae constitute a natural process for developing immunity within an endemically infected population. The alternative hosts and lysogenic environmental V. cholerae strains may potentially act as cofactors in promoting cholera phage ‘‘blooms’’ within aquatic environments, thereby influencing transmission of phage sensitive, pathogenic V. cholerae strains by aquatic vehicles. Differential induction of the phages is a clear indication of the impact of environmental pollution and global changes on phage induction. The development of molecular biology techniques offered an accessible gateway for investigating the molecular events leading to genetic diversity in the marine environment. Using nucleic acids as targets, the methods of fingerprinting like ERIC PCR and BOX PCR, revealed that the marine environment harbours potentially pathogenic group of bacteria with genetic diversity. The distribution of virulence associated genes in the environmental isolates of V. cholerae provides tangible material for further investigation. Nucleotide and protein sequence analysis alongwith protein structure prediction aids in better understanding of the variation inalleles of same gene in different ecological niche and its impact on the protein structure for attaining greater fitness of pathogens. The evidences of the co-evolution of virulence genes in toxigenic V. cholerae O1 from different lineages of environmental non-O1 strains is alarming. Transduction studies would indicate that the phenomenon of acquisition of these virulence genes by lateral gene transfer, although rare, is not quite uncommon amongst non-O1/non-O139 V. cholerae and it has a key role in diversification. All these considerations justify the need for an integrated approach towards the development of an effective surveillance system to monitor evolution of V. cholerae strains with epidemic potential. Results presented in this study, if considered together with the mechanism proposed as above, would strongly suggest that the bacteriophage also intervenes as a variable in shaping the cholera bacterium, which cannot be ignored and hinting at imminent future epidemics. |
| Description: | Microbial Genetics laboratory, Department of Biotechnology |
| URI: | http://dyuthi.cusat.ac.in/purl/5032 |
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| Dyuthi-T2100.pdf | (5.569Mb) |
| Abstract: | Three species of cephalopod molluacs collected from the waters in and around cochin area of the Arabian Sea, of south India formed the subject of the present study. The Species are loligo duvauceli, _Sepia_ aculeata and sepiella inermis, their food and feeding habits, morphology and histology of the gut as well as the physiology of digestion have been described |
| Description: | Department of Marine Science, Cochin University of Science & Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3344 |
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| Dyuthi-T1326.pdf | (4.763Mb) |
| Abstract: | Hindi |
| Description: | Departrnent of Hindi, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/4839 |
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| Dyuthi-T1936.pdf | (3.961Mb) |
| Abstract: | HINDI |
| Description: | DEPARTMENT OF HINDI COCHIN UNIVERSITY OF SCIENCE AND TECHNOLOGY |
| URI: | http://dyuthi.cusat.ac.in/purl/4753 |
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| Dyuthi-T1850.pdf | (6.545Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/5451 |
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| Dyuthi T-2492.pdf | (35.50Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/1027 |
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| Thresiamma T k 1986.pdf | (257.9Kb) |
| Abstract: | The object of this thesis is to formulate a basic commutative difference operator theory for functions defined on a basic sequence, and a bibasic commutative difference operator theory for functions defined on a bibasic sequence of points, which can be applied to the solution of basic and bibasic difference equations. in this thesis a brief survey of the work done in this field in the classical case, as well as a review of the development of q~difference equations, q—analytic function theory, bibasic analytic function theory, bianalytic function theory, discrete pseudoanalytic function theory and finally a summary of results of this thesis |
| Description: | Department of Mathematics and Statistics, Cochin University of Science & Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3341 |
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| Dyuthi-T1325.pdf | (3.438Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/5427 |
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| Dyuthi T-2468.pdf | (2.089Mb) |
| Abstract: | In everyday life different flows of customers to avail some service facility or other at some service station are experienced. In some of these situations, congestion of items arriving for service, because an item cannot be serviced Immediately on arrival, is unavoidable. A queuing system can be described as customers arriving for service, waiting for service if it is not immediate, and if having waited for service, leaving the system after being served. Examples Include shoppers waiting in front of checkout stands in a supermarket, Programs waiting to be processed by a digital computer, ships in the harbor Waiting to be unloaded, persons waiting at railway booking office etc. A queuing system is specified completely by the following characteristics: input or arrival pattern, service pattern, number of service channels, System capacity, queue discipline and number of service stages. The ultimate objective of solving queuing models is to determine the characteristics that measure the performance of the system |
| Description: | Department of Mathematics, Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3210 |
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| Dyuthi-T1184.pdf | (506.5Kb) |
| URI: | http://dyuthi.cusat.ac.in/purl/1312 |
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| Chandrasekharan N S 1983.PDF | (517.1Kb) |
| Abstract: | This is a study in labour law.. Dismissal of workmen in private lndustrial sector is the area of this study. Confined within the framework of the Industrial Disputes act 1947, the study is an analytical assessment of the decisions of the supreme Court of India. on dismissal in industrial employment. Few attempts were made in the past to analyse on identical lines the problems in this area. Hence what is| written in this thesis is ones own. Dismissal carries a stigma. the dismissed employee may find it difficult to get alternative employment especially in a land of severe unemployment. The need for law with built in safeguards against arbitrary dismissal cannot be overemphasized. From this perspective the study examines to what extent the industrial disputes act 1947 provides protection and how far the protection is adequate. |
| Description: | School of legal studies, Cochin University of Science And Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3343 |
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| Dyuthi-T1304.pdf | (29.53Mb) |
| URI: | http://dyuthi.cusat.ac.in/purl/2303 |
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| Dyuthi-T0595.pdf | (8.391Mb) |
| Abstract: | This thesis Entitled distribution ,diversity and biology of deep-sea fishes the indian Eez.Fishing rights and responsibilities it entails in the deep-sea sector has been a vexed issue since the mid-nineties and various stakeholders have different opinion on the modalities of harnessing the marine fisheries wealth, especially from the oceanic and deeper waters. The exploitation and utilization of these esources requires technology development and upgradation in harvest and post-harvest areas; besides shore infrastructure for berthing, handling, storing and processing facilities. At present, although deep-sea fishes don’t have any ready market in our country it can be converted into value added products. Many problems have so far confronted the deep-sea fishing sector not allowing it to reach its full potential. Hence, there should be a sound deep-sea fishing policy revolving round the upgradation of the capabilities of small scale fishermen, who have the inherent skills but do not have adequate support to develop themselves and to acquire vessels having the capability to operate in farther and deeper waters. Prospects for the commercial exploitation and utilization of deep-sea fishes were analyzed using SWOL analysis. |
| Description: | Central Marine Fisheries Research Institute |
| URI: | http://dyuthi.cusat.ac.in/purl/3056 |
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| Dyuthi-T1030.pdf | (10.65Mb) |
| Abstract: | The thesis deals with the prevalence and distribution of motile aeromonads in selected ornamental fishes. The presence of motile aeromonads in ornamental fishes and associated carriage water is well documented. Though aeromonads are a part of autochthonous flora of natural waters, disease outbreak occurs as a result of environmental stress on the cultured species and virulence of the pathogens. While ornamental aquaculture in many parts of the world is highly organized and practiced scientifically, it is highly unorganized in India. The culture ponds/tanks are often maintained in very poor manner and the fishes are subjected to high degree of stress during transportation from the production facility to retail vendors. The situation is no better at retail outlets, where fishes are maintained in crowded condition without proper aeration or food. All these could result in high prevalence of diseases caused by motile aeromonads. No systematic study has been carried out to understand the prevalence of motile aeromonads in ornamental fishes and carriage water . It also gives an account of the production of extracellular virulence factors and the antibiogram of the different species of motile aeromonads isolated. The growth characteristics and virulence potential of a representative strain of Aeromonas hydrophila is also studied. The nucleotide sequencing of the strain was carried out and sequences deposited in Genbank. Survival and immune response of Cyprinus carpio under different stress conditions and on probiotic treatment with Bacillus NL110, when challenged with A. hydrophila is also dealt within this thesis. |
| URI: | http://dyuthi.cusat.ac.in/purl/4924 |
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| Dyuthi-T2003.pdf | (18.94Mb) |
| Abstract: | The study revealed stress and localized impact of industrial waste on the biota, predominance of stress tolerant species and low diversity in the vicinity of the effluent discharge point. These studies on impact of environmental parameters on the distribution of macrobenthos thus indicate the quantum of endurance warranted by the infauna to tide over the wide range of environmental stress. Low diversity and lower number of benthic fauna near discharge site can be attributed to the stress caused by cumulative toxic effects of effluents. The results of the physico-chemical parameters highlight the effects of pollution. The results of the study indicated the changes due to the large-scale movements of the estuarine water under the influence of tide, monsoon and land runoff coupled with its heterogenous nature owing to the effluent discharge from the industries |
| URI: | http://dyuthi.cusat.ac.in/purl/105 |
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| Dyuthi-T0045.pdf | (9.530Mb) |
| Description: | Department of Chemical Oceanography,Cochin University of Science and Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/2335 |
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| Dyuthi-T0609.pdf | (6.924Mb) |
| Abstract: | When we consider Kerala and Karnataka States according to their levels of decentralisation. Kerala is at the beginning of the scale of decentralisation whereas Kamataka has moved far ahead along this scale. Therefore I in order to conduct a comparative study of the SUbject under analysis t Kamataka has been selected owing to the fact that it is in an advanced stage in the experience of district planning compared to Kerala , Karnataka could successfully implement district planning and it is me of the pioneering states in this regard. But Kerala has not gained much experience in the field of decentralised district planning till now. Furthermore Kerala and Kamataka states are selected for the present study due to operational reasons I besides the author I s familiarity with the socia-economic conditions of these states. Thus. an analysis of the district planning experience of Kamataka will provide constructive and valuable information. which will be of great importance to Kerala State, which is now aspiring to introduce ful.I-f'Iedge district planning by constituting elected District Coancils in every district of Kerala. Moreover. the findings and policy implications of the present study will be of immense help to planners, politicians. administrators, academicians and people at large. |
| Description: | School of Management Studies, Cochin University of Science & Technology |
| URI: | http://dyuthi.cusat.ac.in/purl/3387 |
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| Dyuthi-T1364.pdf | (13.63Mb) |
| Abstract: | The basic objective of the present study has been to observe the process and pattern of employment diversification among the rural women workers in Ernakulam district. The evidences are that the women workers in the rural areas of the state are being increasingly diversified into the tertiary sector. The clear cut evidence for the fact that in Kerala non-agricultural employment of rural women is increasing with more and more of them getting diversified into the tertiary sector. The women get more self esteem and recognition in terms of the work being done by them. In the urban areas of the state as a poverty eradicating measure the Kerala government has already introduced a new scheme under the banner of Kudumbasree. Another fact noticed in the study that the sectoral shift of women workers has posed a grave problem to the agricultural sector. The reluctance of workers to do manual jobs on land and the prevalence of high wages among the agricultural labours has left many a cultivable area fallow or has induced farmers to shift to less labour –intensive crops. The situation is expected to worsen in future as even the high wages fail to attract the young generation to this sector. To conclude the study has fulfilled all its objectives, viz; highlighting the rural employment structure in Kerala, examining the process, pattern, determinants and consequences of diversification among rural women workers in the sample villages. Being the first of its kind at the micro level in the state it contributes to the available literature in the area enriching the database that is crucially lacking for devising projects at the village and block-level. There exists ample scope for future research of similar nature in an urban background where the secondary data-sources are hinding towards a reversal of trends from non-agriculture to agriculture. |
| URI: | http://dyuthi.cusat.ac.in/purl/50 |
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| Dyuthi-T0040.pdf | (4.475Mb) |
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