Rakesh Kumar - Academia.edu (original) (raw)

Papers by Rakesh Kumar

Research paper thumbnail of An improved murine model of asthma: selective airway inflammation, epithelial lesions and increased methacholine responsiveness following chronic exposure to aerosolised allergen

Thorax, 1998

Background-Existing murine models of asthma lack many of the inflammatory and epithelial changes ... more Background-Existing murine models of asthma lack many of the inflammatory and epithelial changes that are typical of the human disease. Moreover, these models are frequently complicated by allergic alveolitis. Methods-High IgE responder BALB/c mice were systemically sensitised to ovalbumin and chronically challenged with low particle mass concentrations of aerosolised ovalbumin. Titres of antiovalbumin IgE in serum were measured at two weekly intervals by enzyme immunoassay, accumulation of inflammatory cells and histopathological abnormalities of the epithelium were quantified morphometrically in the trachea and the lungs, and airway reactivity was assessed by measuring bronchoconstriction following intravenous administration of methacholine. Results-Mice sensitised by two intraperitoneal injections of ovalbumin developed high titres of IgE antibodies to ovalbumin. Following exposure to low concentrations of aerosolised antigen for up to eight weeks these animals developed a progressive inflammatory response in the airways, characterised by the presence of intraepithelial eosinophils and by infiltration of the lamina propria with lymphoid/ mononuclear cells, without associated alveolitis.

Research paper thumbnail of Dye removal from aqueous solution by adsorption on treated sawdust

Bioresource Technology, 2003

Formaldehyde treated and sulphuric acid treated saw dusts were used to adsorb malachite green at ... more Formaldehyde treated and sulphuric acid treated saw dusts were used to adsorb malachite green at varying dye concentration, adsorbent dose, pH and agitation time. Similar experiments were conducted with laboratory grade activated carbon to compare the results. The adsorption efficiency of sulphuric acid treated sawdust (SD) was higher than formaldehyde treated SD. The adsorption followed first order rate expression and Lagergren equation. An initial pH in the range of 6-9 was favorable for the dye removal by both the adsorbents. Dilute solutions were effectively decolorized by the adsorbents. It is proposed that in batch or stirred tank reactors, both adsorbents can be an attractive option for dye adsorption.

Research paper thumbnail of Randomized, Double-Blind, Placebo-Controlled Trial of Fish Oil and Mustard Oil in Patients with Suspected Acute Myocardial Infarction: The Indian Experiment of Infarct Survival—4

Cardiovascular Drugs and Therapy, 1997

In a randomized, placebo-controlled trial, the effects of treatment with fish oil (eicosapentaeno... more In a randomized, placebo-controlled trial, the effects of treatment with fish oil (eicosapentaenoic acid, 1.08 g/day) and mustard oil (alpha-linolenic acid, 2.9 g/day) were compared for 1 year in the management of 122 patients (fish oil, group A), 120 patients (mustard oil, group B), and 118 patients (placebo, group C) with suspected acute myocardial infarction (AMI). Treatments were administered about (mean) 18 hours after the symptoms of AMI in all three groups. The extent of cardiac disease, rise in cardiac enzymes, and lipid peroxides were comparable among the groups at entry into the study. After 1 year total cardiac events were significantly less in the fish oil and mustard oil groups compared with the placebo group (24.5% and 28% vs. 34.7%, p > 0.01). Nonfatal infarctions were also significantly less in the fish oil and mustard oil groups compared with the placebo group (13.0% and 15.0% vs. 25.4%, p > 0.05). Total cardiac deaths showed no significant reduction in the mustard oil group; however, the fish oil group had significantly less cardiac deaths compared with the placebo group (11.4% vs. 22.0%, p > 0.05). Apart from the decrease in the cardiac event rate, the fish oil and mustard oil groups also showed a significant reduction in total cardiac arrhythmias, left ventricular enlargement, and angina pectoris compared with the placebo group. Reductions in blood lipoproteins in the two intervention groups were modest and do not appear to be the cause of the benefit in the two groups. Diene conjugates showed a significant reduction in the fish oil and mustard oil groups, indicating that a part of the benefit may be caused by the reduction in oxidative stress. The findings of this study suggest that fish oil and mustard oil, possibly due to the presence of n-3 fatty acids, may provide rapid protective effects in patients with AMI. However, a large study is necessary to confirm this suggestion.

Research paper thumbnail of The KaZaA Overlay: A Measurement Study

Both in terms of number of participating users and in traffic volume, KaZaA is one of the most im... more Both in terms of number of participating users and in traffic volume, KaZaA is one of the most important applications in the Internet today. Nevertheless, because KaZaA is proprietary and uses encryption, little is understood about KaZaA's overlay structure and dynamics, its ...

Research paper thumbnail of Pollution in P2P file sharing systems

One way to combat P2P file sharing of copyrighted content is to deposit into the file sharing sys... more One way to combat P2P file sharing of copyrighted content is to deposit into the file sharing systems large volumes of polluted files. Without taking sides in the file sharing debate, in this paper we undertake a measurement study of the nature and magnitude of pollution in KaZaA, currently the most popular P2P file sharing system. We develop a crawling platform which crawls the majority of the KaZaA 20,000+ supernodes in less than 60 minutes. From the raw data gathered by the crawler for popular audio content, we obtain statistics on the number of unique versions and copies available in a 24-hour period. We develop an automated procedure to detect whether a given version is polluted or not, and we show that the probabilities of false positives and negatives of the detection procedure are very small. We use the data from the crawler and our pollution detection algorithm to determine the fraction of versions and fraction of copies that are polluted for several recent and old songs. We observe that pollution is pervasive for recent popular songs. We also identify and describe a number of anti-pollution mechanisms.

Research paper thumbnail of Stochastic Fluid Theory for P2P Streaming Systems

We develop a simple stochastic fluid model that seeks to expose the fundamental characteristics a... more We develop a simple stochastic fluid model that seeks to expose the fundamental characteristics and limitations of P2P streaming systems. This model accounts for many of the essential features of a P2P streaming system, including the peers' realtime demand for content, peer churn (peers joining and leaving), peers with heterogeneous upload capacity, limited infrastructure capacity, and peer buffering and playback delay. The model is tractable, providing closed-form expressions which can be used to shed insight on the fundamental behavior of P2P streaming systems.

Research paper thumbnail of An improved murine model of asthma: selective airway inflammation, epithelial lesions and increased methacholine responsiveness following chronic exposure to aerosolised allergen

Thorax, 1998

Background-Existing murine models of asthma lack many of the inflammatory and epithelial changes ... more Background-Existing murine models of asthma lack many of the inflammatory and epithelial changes that are typical of the human disease. Moreover, these models are frequently complicated by allergic alveolitis. Methods-High IgE responder BALB/c mice were systemically sensitised to ovalbumin and chronically challenged with low particle mass concentrations of aerosolised ovalbumin. Titres of antiovalbumin IgE in serum were measured at two weekly intervals by enzyme immunoassay, accumulation of inflammatory cells and histopathological abnormalities of the epithelium were quantified morphometrically in the trachea and the lungs, and airway reactivity was assessed by measuring bronchoconstriction following intravenous administration of methacholine. Results-Mice sensitised by two intraperitoneal injections of ovalbumin developed high titres of IgE antibodies to ovalbumin. Following exposure to low concentrations of aerosolised antigen for up to eight weeks these animals developed a progressive inflammatory response in the airways, characterised by the presence of intraepithelial eosinophils and by infiltration of the lamina propria with lymphoid/ mononuclear cells, without associated alveolitis.

Research paper thumbnail of Dye removal from aqueous solution by adsorption on treated sawdust

Bioresource Technology, 2003

Formaldehyde treated and sulphuric acid treated saw dusts were used to adsorb malachite green at ... more Formaldehyde treated and sulphuric acid treated saw dusts were used to adsorb malachite green at varying dye concentration, adsorbent dose, pH and agitation time. Similar experiments were conducted with laboratory grade activated carbon to compare the results. The adsorption efficiency of sulphuric acid treated sawdust (SD) was higher than formaldehyde treated SD. The adsorption followed first order rate expression and Lagergren equation. An initial pH in the range of 6-9 was favorable for the dye removal by both the adsorbents. Dilute solutions were effectively decolorized by the adsorbents. It is proposed that in batch or stirred tank reactors, both adsorbents can be an attractive option for dye adsorption.

Research paper thumbnail of Randomized, Double-Blind, Placebo-Controlled Trial of Fish Oil and Mustard Oil in Patients with Suspected Acute Myocardial Infarction: The Indian Experiment of Infarct Survival—4

Cardiovascular Drugs and Therapy, 1997

In a randomized, placebo-controlled trial, the effects of treatment with fish oil (eicosapentaeno... more In a randomized, placebo-controlled trial, the effects of treatment with fish oil (eicosapentaenoic acid, 1.08 g/day) and mustard oil (alpha-linolenic acid, 2.9 g/day) were compared for 1 year in the management of 122 patients (fish oil, group A), 120 patients (mustard oil, group B), and 118 patients (placebo, group C) with suspected acute myocardial infarction (AMI). Treatments were administered about (mean) 18 hours after the symptoms of AMI in all three groups. The extent of cardiac disease, rise in cardiac enzymes, and lipid peroxides were comparable among the groups at entry into the study. After 1 year total cardiac events were significantly less in the fish oil and mustard oil groups compared with the placebo group (24.5% and 28% vs. 34.7%, p > 0.01). Nonfatal infarctions were also significantly less in the fish oil and mustard oil groups compared with the placebo group (13.0% and 15.0% vs. 25.4%, p > 0.05). Total cardiac deaths showed no significant reduction in the mustard oil group; however, the fish oil group had significantly less cardiac deaths compared with the placebo group (11.4% vs. 22.0%, p > 0.05). Apart from the decrease in the cardiac event rate, the fish oil and mustard oil groups also showed a significant reduction in total cardiac arrhythmias, left ventricular enlargement, and angina pectoris compared with the placebo group. Reductions in blood lipoproteins in the two intervention groups were modest and do not appear to be the cause of the benefit in the two groups. Diene conjugates showed a significant reduction in the fish oil and mustard oil groups, indicating that a part of the benefit may be caused by the reduction in oxidative stress. The findings of this study suggest that fish oil and mustard oil, possibly due to the presence of n-3 fatty acids, may provide rapid protective effects in patients with AMI. However, a large study is necessary to confirm this suggestion.

Research paper thumbnail of The KaZaA Overlay: A Measurement Study

Both in terms of number of participating users and in traffic volume, KaZaA is one of the most im... more Both in terms of number of participating users and in traffic volume, KaZaA is one of the most important applications in the Internet today. Nevertheless, because KaZaA is proprietary and uses encryption, little is understood about KaZaA's overlay structure and dynamics, its ...

Research paper thumbnail of Pollution in P2P file sharing systems

One way to combat P2P file sharing of copyrighted content is to deposit into the file sharing sys... more One way to combat P2P file sharing of copyrighted content is to deposit into the file sharing systems large volumes of polluted files. Without taking sides in the file sharing debate, in this paper we undertake a measurement study of the nature and magnitude of pollution in KaZaA, currently the most popular P2P file sharing system. We develop a crawling platform which crawls the majority of the KaZaA 20,000+ supernodes in less than 60 minutes. From the raw data gathered by the crawler for popular audio content, we obtain statistics on the number of unique versions and copies available in a 24-hour period. We develop an automated procedure to detect whether a given version is polluted or not, and we show that the probabilities of false positives and negatives of the detection procedure are very small. We use the data from the crawler and our pollution detection algorithm to determine the fraction of versions and fraction of copies that are polluted for several recent and old songs. We observe that pollution is pervasive for recent popular songs. We also identify and describe a number of anti-pollution mechanisms.

Research paper thumbnail of Stochastic Fluid Theory for P2P Streaming Systems

We develop a simple stochastic fluid model that seeks to expose the fundamental characteristics a... more We develop a simple stochastic fluid model that seeks to expose the fundamental characteristics and limitations of P2P streaming systems. This model accounts for many of the essential features of a P2P streaming system, including the peers' realtime demand for content, peer churn (peers joining and leaving), peers with heterogeneous upload capacity, limited infrastructure capacity, and peer buffering and playback delay. The model is tractable, providing closed-form expressions which can be used to shed insight on the fundamental behavior of P2P streaming systems.