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579 results on '"Natesan, S."'

2. Remarkable Improvement in Am3+ and Cm3+ Separation Using a Cooperative Counter Selectivity Strategy by a Combination of Branched Diglycolamides and Hydrophilic Polyaza-heterocycles

Author

Gujar, Rajesh B., primary, Kanekar, Avinash S., additional, Bhattacharyya, Arunasis, additional, Karthikeyan, Natesan S., additional, Ravichandran, Cingaram, additional, Toleti, Subba Rao, additional, Egberink, Richard J. M., additional, Huskens, Jurriaan, additional, Verboom, Willem, additional, and Mohapatra, Prasanta K., additional

Published
2024
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16. Parallel Implementation of a Spline Based Computational Approach for Singular Perturbation Problems

Author

Bawa, Rajesh K., Natesan, S., Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Dough, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Robert, Yves, editor, Parashar, Manish, editor, Badrinath, Ramamurthy, editor, and Prasanna, Viktor K., editor

Published
2006
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18. Uniformly Convergent Computational Technique for Singularly Perturbed Self-adjoint Mixed Boundary-Value Problems

Author

Bawa, Rajesh K., Natesan, S., Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Dough, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Sunderam, Vaidy S., editor, van Albada, Geert Dick, editor, Sloot, Peter M. A., editor, and Dongarra, Jack, editor

Published
2005
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23. Alternating direction implicit method for singularly perturbed 2D parabolic convection–diffusion–reaction problem with two small parameters.

Author

B., Mrityunjoy, Natesan, S., and Sendur, A.

Subjects
*FINITE differences, *DESIGN
Abstract

In this article, we construct and analyse an Alternating Direction Implicit (ADI) scheme for singularly perturbed 2D parabolic convection–diffusion–reaction problems with two small parameters. We consider the operator-splitting ADI finite difference scheme for time stepping on a uniform mesh and a simple upwind-difference scheme for spatial discretization on a specially designed piecewise-uniform Shishkin mesh. The resulting scheme is proved to be uniformly convergent of order O (N − 1 ln ⁡ N + M − 1) , where N, M are the spatial and temporal parameters respectively. Numerical experiments confirm the theoretical results and the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

Published
2023
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30. Numerical analysis of a fully discrete stabilized FEM for system of singularly perturbed parabolic IBVPs.

Author

Avijit, D. and Natesan, S.

Subjects
*NUMERICAL analysis, *FINITE element method, *BOUNDARY layer (Aerodynamics)
Abstract

In this article, a fully discrete numerical method is studied to solve the system of singularly perturbed parabolic convection–diffusion problem. The full discretization incorporates the backward-Euler method and the streamline-diffusion finite element method (SDFEM) for the temporal and spatial discretization, respectively. In each equation, the highest ordered spatial derivatives are multiplied by distinct parameters, hence the overlapping boundary layers phenomena displayed in the solution. To capture the singularity of the solution, a layer-adapted mesh has been used for the spatial domain discretization. The stability of the numerical method has been addressed by considering an appropriate stabilization parameter. A complete error analysis has shown the first order of accuracy of the fully discrete method in the discrete L 2 (0 , T ; S D) -norm. Lastly, few numerical experiments have been addressed to justify the theoretical estimates. [ABSTRACT FROM AUTHOR]

Published
2022
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35. Evaluation of validity of scoring systems in diagnosing acute appendicitis: a single centre prospective observational study

Author

Rakesh Natesan S. and Naren Kumar A.

Abstract

Background: Acute appendicitis is a very common cause of acute abdominal pain, requiring surgical intervention with a 7% life time risk. Various clinical scoring systems like Alvarado, appendicitis inflammatory response (AIR), Tzanaki scores enables risk stratification. In this study, we have validated the diagnostic accuracy of various scoring systems like Alvarado, Tzanaki and AIR scores. Methods: We conducted a prospective observational study for patients admitted in a tertiary care hospital. A total of 81 patients were selected based on the inclusion and exclusion criteria. A detailed clinical history, physical examination, relevant blood investigations and necessary imaging were done for all the patients. Using the above data, the probability of acute appendicitis is calculated using the Alvarado, Tzanaki and AIR scores. The various scores obtained were compared with the histopathological examination (HPE) reports (reference standard) and values like sensitivity, specificity, positive and negative predictive values (PPV and NPV) were calculated.Results: With regard to scores, Alvarado scores has a sensitivity 95.24%, specificity 77.78%, PPV of 93.75%, NPV of 82.35%. Tzanaki score has a sensitivity of 100%, specificity 23.5%, PPV of 83.12% and NPV of 100%. AIR score has a sensitivity of 95%, specificity of 66.67%, PPV of 89.06% and NPV of 82.35%. Conclusions: Alvarado score (cut off 7) has the best PPV (93.75%) and hence is the best scoring system to “rule in” a positive diagnosis. However, Tzanaki score (cut off 8) has the best NPV (100%) and hence is the best score to “rule out” a diagnosis of acute appendicitis.

Published
2021

41. P.525 The relationship between synaptic density marker SV2A and glutamate: a multimodal positron emission tomography and magnetic resonance spectroscopy imaging study

Author

Onwordi, E.C., primary, Halff, E., additional, Whitehurst, T., additional, Mansur, A., additional, Statton, B., additional, Berry, A., additional, Quinlan, M., additional, O'Regan, D., additional, Rogdaki, M., additional, Marques, T. Reis, additional, Rabiner, E.A., additional, Gunn, R.N., additional, Vernon, A.C., additional, Natesan, S., additional, and Howes, O.D., additional

Published
2020
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