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Search Results: 1 - 10 of 130428 matches for " V. Kamalakar "
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A Case Study of Mesospheric Wave Periods and Horizontal Structures over a Low Latitude Station, Allahabad (India)
N. Parihar,A. Taori,V. Kamalakar,S. V. B. Rao
Earth Science Research , 2012, DOI: 10.5539/esr.v2n1p1
Abstract: We report the measurements of short period gravity waves with the help of all sky imager operated at OH nightglow wavelenghts during 21-22 and 23-24 April 2009 from Allahabad (25.5° N, 81.9° E), India. We note persistent oscillations on both the nights with wave periods ranging from 0.4 to 1.5 hours. To quantify the zonal and meridional scales of these waves, we analyze the intensity variability noted in zenith angles 30°, 15° and 0° in East, West, North and South directions. We find the wavelengths of observed waves to vary from 40 to 100 km. We discuss these observed wave properties in connection to their importance in global circulation of upper atmosphere.
A new method to derive middle atmospheric temperature profiles using a combination of Rayleigh lidar and O2 airglow temperatures measurements
A. Taori, A. Jayaraman, K. Raghunath,V. Kamalakar
Annales Geophysicae (ANGEO) , 2012,
Abstract: The vertical temperature profiles in a typical Rayleigh lidar system depends on the backscatter photon counts and the CIRA-86 model inputs. For the first time, we show that, by making simultaneous measurements of Rayleigh lidar and upper mesospheric O2 temperatures, the lidar capability can be enhanced to obtain mesospheric temperature profile up to about 95 km altitudes. The obtained results are compared with instantaneous space-borne SABER measurements for a validation.
Synthesis, Characterization and Investigation of Electrical Transport in Metal Nanowires and Nanotubes
M. Venkata Kamalakar
Physics , 2011,
Abstract: This thesis is dedicated to the synthesis, characterization and the study of electrical transport through metal nanowires and nanotubes. The metal nanowires(Ni, Cu) and nanotubes(Cu) are synthesised by electrochemical deposition in nanoporous templates. In the synthesis front, electrochemical deposition schemes were developed to achieve single crystallinity and synthesis of tubular nanostructures. The nanostructures are characterized using structural characterization techniques such as X-ray diffraction, Scanning electron microscopy and Transmission electron microscopy. The magnetic nanowires are also characterized using VSM and SQUID magnetometers. The electrical transport measurements performed in a wide range of temperature (3K-700K) to understand the interactions of electrons with phonon, magnon and surface when the electron mean free path is limited by the dimension of these nanostructures. The measurements were performed in the wide range of temperature to encompass and study the ferromagnetic to paramagnetic phase transition in case of magnetic nanowires. We observed systematic scaling of these interactions and the characteristic temperatures such as the Debye temperature(\theta_R) and Curie temperature(T_C) as a function of diameter. We also observed how these interactions change as we move from nanowires to nanotubes of metals.
Inequity aversion and the evolution of cooperation
Asrar Ahmed,Kamalakar Karlapalem
Computer Science , 2014, DOI: 10.1103/PhysRevE.89.022802
Abstract: Evolution of cooperation is a widely studied problem in biology, social science, economics, and artificial intelligence. Most of the existing approaches that explain cooperation rely on some notion of direct or indirect reciprocity. These reciprocity based models assume agents recognize their partner and know their previous interactions, which requires advanced cognitive abilities. In this paper we are interested in developing a model that produces cooperation without requiring any explicit memory of previous game plays. Our model is based on the notion of, a concept introduced within behavioral economics, whereby individuals care about payoff equality in outcomes. Here we explore the effect of using income inequality to guide partner selection and interaction. We study our model by considering both the well-mixed and the spatially structured population and present the conditions under which cooperation becomes dominant. Our results support the hypothesis that inequity aversion promotes cooperative relationship among nonkin.
Exploiting Near Time Forecasting From Social Network To Decongest Traffic
Deepika Pathania,Kamalakar Karlapalem
Computer Science , 2015,
Abstract: Preventing traffic congestion by forecasting near time traffic flows is an important problem as it leads to effective use of transport resources. Social network provides information about activities of humans and social events. Thus, with the help of social network, we can extract which humans will attend a particular event (in near time) and can estimate flow of traffic based on it. This opens up a wide area of research which poses need to have a framework for traffic management that can capture essential parameters of real-life behaviour and provide a way to iterate upon and evaluate new ideas. In this paper, we present building blocks of a framework and a system to simulate a city with its transport system, humans and their social network. We emphasize on relevant parameters selected and modular design of the framework. Our framework defines metrics to evaluate congestion avoidance strategies. To show utility of the framework, we present experimental studies of few strategies on a public transport system.
Effective Handling of Urgent Jobs - Speed Up Scheduling for Computing Applications
Yash Gupta,Kamalakar Karlapalem
Computer Science , 2015,
Abstract: A queue is required when a service provider is not able to handle jobs arriving over the time. In a highly flexible and dynamic environment, some jobs might demand for faster execution at run-time especially when the resources are limited and the jobs are competing for acquiring resources. A user might demand for speed up (reduced wait time) for some of the jobs present in the queue at run time. In such cases, it is required to accelerate (directly sending the job to the server) urgent jobs (requesting for speed up) ahead of other jobs present in the queue for an earlier completion of urgent jobs. Under the assumption of no additional resources, such acceleration of jobs would result in slowing down of other jobs present in the queue. In this paper, we formulate the problem of Speed Up Scheduling without acquiring any additional resources for the scheduling of on-line speed up requests posed by a user at run-time and present algorithms for the same. We apply the idea of Speed Up Scheduling to two different domains -Web Scheduling and CPU Scheduling. We demonstrate our results with a simulation based model using trace driven workload and synthetic datasets to show the usefulness of Speed Up scheduling. Speed Up provides a new way of addressing urgent jobs, provides a different evaluation criteria for comparing scheduling algorithms and has practical applications.
Crowd Congestion and Stampede Management through Multi Robotic Agents
Garima Ahuja,Kamalakar Karlapalem
Computer Science , 2015,
Abstract: Crowd management is a complex, challenging and crucial task. Lack of appropriate management of crowd has, in past, led to many unfortunate stampedes with significant loss of life. To increase the crowd management efficiency, we deploy automated real time detection of stampede prone areas. Then, we use robotic agents to aid the crowd management police in controlling the crowd in these stampede prone areas. While doing so, we aim for minimum interference by robotic agents in our environment. Thereby not disturbing the ambiance and aesthetics of the place. We evaluate the effectiveness of our model in dealing with difficult scenarios like emergency evacuation and presence of localized congestion. Lastly, we simulate a multi agent system based on our model and use it to illustrate the utility of robotic agents for detecting and reducing congestion.
Subset Queries in Relational Databases
Satyanarayana R Valluri,Kamalakar Karlapalem
Computer Science , 2004,
Abstract: In this paper, we motivated the need for relational database systems to support subset query processing. We defined new operators in relational algebra, and new constructs in SQL for expressing subset queries. We also illustrated the applicability of subset queries through different examples expressed using extended SQL statements and relational algebra expressions. Our aim is to show the utility of subset queries for next generation applications.
Electrical measurements on single nanowires and nanotubes of metals and its correlation with structural characterization
A. K. Raychaudhuri,M. Venkata Kamalakar
Journal of Analytical Science & Technology , 2011,
Abstract: Electrical measurements on nanowires, in particular, single nanowires and devices, are important physical parameters. These studies along with structural characterization can be used to understand the basic science of these materials and can realize their application potentials.
Proteinuria in Hypertensive Nephropathy: A Review  [PDF]
Rishi Sharma, Surineni Kamalakar, Ellen McCarthy, Timothy A. Fields, Kamal Gupta, Rajat Barua, Virginia Savin
Open Journal of Nephrology (OJNeph) , 2014, DOI: 10.4236/ojneph.2014.42013

Hypertension defined as a systolic blood pressure of ≥140 and a diastolic blood pressure ≥90 is anextremely prevalent condition; and it is responsible for significant mortality and morbidity. NHANESdata from 2005-2006 found that nearly 30% of adult US population has HTN; and nearly 8% of the population has undiagnosed HTN. HBP mortality in 2008 was 61,005. Any mentioned mortality in 2008 was 347,689 (NHLBI tabulation of NCHS mortality data). More than 20% of patients with systemic hypertension have chronic renal insufficiency (NHANES). Hypertensive nephropathy is a leading cause of end-stage renal disease (ESRD) requiring dialysis or transplantation or leading to death. The incidence of hypertension is high but only a subset of hypertensive patients progress to frank renal failure. A subset of hypertensive patients develop proteinuria during the course of disease and manifest nephrotic syndrome. This syndrome includes marked proteinuria, edema, and low serum albumin. Neither the incidence nor the clinical significance of proteinuria in hypertension without diabetes is known. Progression to chronic renal failure in some patients is preceded by proteinuria as indicated on “dip-stick” analyses of random urine samples. It appears that proteinuria is likely to increase both prior to and during evident loss of glomerular filtration, but this clinical observation has never been formally confirmed. There is a need for large studies to answer these questions. We also need to focus on the roles that genetic and environmental factors play in development and progression of renal disease in the setting of hypertension and proteinuria.

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