On Queues with Interruptions and Repeat or Resumption of Service

This thesis entitled' On Queues with Interruptions and Repeat or Resumption of Service' introduces several new concepts into queues with service interruption. It is divided into Seven chapters including an introductory chapter. The following are keywords that we use in this thesis: Phase type (PH) distribution, Markovian Arrival Process (MAP), Geometric Distribution, Service Interruption, First in First out (FIFO), threshold random variable and Super threshold random variable. In the second chapter we introduce a new concept called the 'threshold random variable' which competes with interruption time to decide whether to repeat or resume the interrupted service after removal of interruptions. This notion generalizes the work reported so far in queues with service interruptions. In chapter 3 we introduce the concept of what is called 'Super threshold clock' (a random variable) which keeps track of the total interruption time of a customer during his service except when it is realized before completion of interruption in some cases to be discussed in this thesis and in other cases it exactly measures the duration of all interruptions put together. The Super threshold clock is OIl whenever the service is interrupted and is deactivated when service is rendered. Throughout this thesis the first in first out service discipline is followed except for priority queues.

Biochemical Effect of Dicarboxylic Acids on Oxalate Metabolism in Experimental Rats and Studies on Oxalate Degrading Bacteria

The current study is an attempt to find a means of lowering oxalate concentration in individuals susceptible to recurrent calcium oxalate stone disease.The formation of renal stone composed of calcium oxalate is a complex process that remains poorly understood and treatment of idiopathic recurrent stone formers is quite difficult and this area has attracted lots of research workers. The main objective of this work are to study the effect of certain mono and dicarboxylic acids on calcium oxalate crystal growth in vitro, isolation and characterization of oxalate degrading bacteria, study the biochemical effect of sodium glycollate and dicarboxylic acids on oxalate metabolism in experimental stone forming rats and To investigate the effect of dicarboxylic acids on oxalate metabolism in experimental hyperoxaluric rats. Oxalic acid is one of the most highly oxidized organic compound widely distributed in the diets of man and animals, and ingestion of plants that contain high concentration of oxalate may lead to intoxication. Excessive ingestion of dietary oxalate may lead to hyperoxaluria and calcium oxalate stone disease.The formation of calcium oxalate stone in the urine is dependent on the saturation level of both calcium and oxalate. Thus the management of one or both of these ions in individuals susceptible to urolithiasis appears to be important. The control of endogenous oxalate synthesis from its precursors in hyperoxaluric situation is likely to yield beneficial results and can be a useful approach in the medical management of urinary stones. A variety of compounds have been investigated to curtain endogenous oxalate synthesis which is a crucial factor, most of these compounds have not proved to be effective in the in vivo situation and some of them are not free from the toxic effect. The non-operative management of stone disease has been practiced in ancient India in the three famous indigenous systems of medicine, Ayurveda, Unani and Siddha, and proved to be effective.However the efficiency of most of these substances is still questionable and demands further study. Man as well as other mammals cannot metabolize oxalic acid. Excessive ingestion of oxalic acid can arise from oxalate rich food and from its major metabolic precursors, glycollate, glyoxylate and ascorbic acid can lead to an acute oxalate toxicity. Increasedlevels of circulating oxalate, which can result in a variety of diseases including renal failure and oxalate lithiasis. The ability to enzymatically degrade oxalate to less noxious Isubstances, formate and CO2, could benefit a great number of individuals including those afflicted with hyperoxaluria and calcium oxalate stone disease.

Phase Transitions Of Trace Metals In The Aquatic Environment Of Kuttanad, Kerala

Environmental persistence, fate and interactive effects with living organisms - beneficial or toxic - of trace elements are directly related to the physico-chemical forms in which they occur. Knowledge on the association of trace metals with different environmental compartments in an aquatic system are, therefore, essential for monitoring the trace metal pollution as well as transport, fate and bio-geochemical cycles of trace metals. This thesis is a modest attempt in assessing the trace metal levels and their behaviour in the aquatic environment of Kuttanad, an aquatic system that is severely affected by man's intervention on natural processes, by seriously evaluating the levels of trace metals in dissolved and particulate phases and also in the different chemical fractions of the sediments.

"A Study Of The Performance Of The "Jeevan Saathi" And "Jeevan Mitra” Policies Offered By The L.I.C."

The main benefit of Jeevan Saathi policy is that, it is a joint life policy which covers the life of both husband and wife under a single policy. And they also get double benefit if any one of them dies during the term of the policy. The Jeevan Mitra policy is a single life policy, the main advantage of which is that the dependents get double benefit in case of normal death and triple benefit in case of accidental death during the term of policy. so both the policies have their own attractions but when compared with the annual sales of other policies, the additional increase in the sales of these policies are decreasing. It is a fact finding study concerned with market performance of these two policies by conducting a survey among the Jeevan Saathi and Jeevan Mitra policy holders, and a thorough analysis of the various information or data collected from them. This study is an attempt to present an integrated picture of the main features of the policy holders who have bought these policies, the major factors responsible for making them purchase these policies, the various difficulties faced by them at present and further modification needed in the plans of these policies according to the opinion of policy holders. For increasing accuracy of the conclusions, information is also collected from Agents and Development Officers by using interview schedule. The main purpose of this study is to draw attention of LIC to introduce new plans of policies taking into consideration the drawbacks or defects of the existing policies and present needs of policy holders. It will also help to make new plans in order to suit the needs of more people who want to buy life insurance policies