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Search Results: 1 - 10 of 682 matches for " Subhendu Panda "
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Breathers in a Discrete Nonlinear Schr?dinger type Model : Exact Stability Results
Avijit Lahiri,Subhendu Panda,Tarun K. Roy
Physics , 2002, DOI: 10.1103/PhysRevE.66.056603
Abstract: Exact stability analysis of 1-site breathers in an NLS type model (ref. [4], see below) indicates destabilisation through a growth rate becoming positive as a stability border is crossed, while above a critical spatial decay rate ($\lambda_c$) the breather is always unstable. Similar analysis on 2-site breathers with phase difference $\pi$ (see below) indicates destabilisation through {\it Krein collision} of a pair of growth rates. All eigenmodes can be exactly calculated and conform to numerical estimates.
Standing Waves in a Non-linear 1D Lattice : Floquet Multipliers, Krein Signatures, and Stability
Subhendu Panda,Anindita Lahiri,Tarun K. Roy,Avijit Lahiri
Physics , 2004, DOI: 10.1016/j.physd.2005.07.018
Abstract: We construct a class of exact commensurate and incommensurate standing wave (SW) solutions in a piecewise smooth analogue of the discrete non-linear Schr\"{o}dinger (DNLS) model and present their linear stability analysis. In the case of the commensurate SW solutions the analysis reduces to the eigenvalue problem of a transfer matrix depending parametrically on the eigenfrequency. The spectrum of eigenfrequencies and the corresponding eigenmodes can thereby be determined exactly. The spatial periodicity of a commensurate SW implies that the eigenmodes are of the Bloch form, characterised by an even number of Floquet multipliers. The spectrum is made up of bands that, in general, include a number of transition points corresponding to changes in the disposition of the Floquet multipliers. The latter characterise the different band segments. An alternative characterisation of the segments is in terms of the Krein signatures associated with the eigenfrequencies. When one or more parameters characterising the SW solution is made to vary, one occasionally encounters collisions between the band-edges or the intra-band transition points and, depending on the the Krein signatures of the colliding bands or segments, the spectrum may stretch out in the complex plane, leading to the onset of instability. We elucidate the correlation between the disposition of Floquet multipliers and the Krein signatures, presenting two specific examples where the SW possesses a definite window of stability, as distinct from the SW's obtained close to the anticontinuous and linear limits of the DNLS model.
Black tea prevents cigarette smoke-induced apoptosis and lung damage
Shuvojit Banerjee, Palas Maity, Subhendu Mukherjee, Alok K Sil, Koustubh Panda, Dhrubajyoti Chattopadhyay, Indu B Chatterjee
Journal of Inflammation , 2007, DOI: 10.1186/1476-9255-4-3
Abstract: Guinea pigs were subjected to cigarette smoke exposure from five cigarettes (two puffs/cigarette) per guinea pig/day for seven days and given water or black tea to drink. Sham control guinea pigs were exposed to air instead of cigarette smoke. Lung damage, as evidenced by inflammation and increased air space, was assessed by histology and morphometric analysis. Protein oxidation was measured through oxyblot analysis of dinitrophenylhydrazone derivatives of the protein carbonyls of the oxidized proteins. Apoptosis was evidenced by the fragmentation of DNA using TUNEL assay, activation of caspase 3, phosphorylation of p53 as well as over-expression of Bax by immunoblot analyses.Cigarette smoke exposure to a guinea pig model caused lung damage. It appeared that oxidative stress was the initial event, which was followed by inflammation, apoptosis and lung injury. All these pathophysiological events were prevented when the cigarette smoke-exposed guinea pigs were given black tea infusion as the drink instead of water.Cigarette smoke exposure to a guinea pig model causes oxidative damage, inflammation, apoptosis and lung injury that are prevented by supplementation of black tea.Cigarette smoking is a major cause for the increased incidence of Chronic Obstructive Pulmonary Diseases (COPD), worldwide. The pathogenesis of this disease is usually characterized by abnormal enlargement of airspaces of the lung accompanied by destruction of its walls [1]. This is a major and increasing global health problem, which is currently the 4th leading cause of death, and is projected to become the 3rd commonest cause of death and the 5th commonest cause of disability in the world by the year 2020 [2]. However, the cellular and molecular mechanism of COPD is not clear and there are no effective drug therapies for such lung damage that are able to significantly reduce disease progression.Over the last few decades, inflammation and protease/antiprotease imbalance have been proposed to act a
Multigrid One-Shot Method for PDE-Constrained Optimization Problems  [PDF]
Subhendu Bikash Hazra
Applied Mathematics (AM) , 2012, DOI: 10.4236/am.2012.330216
Abstract: This paper presents a numerical method for PDE-constrained optimization problems. These problems arise in many fields of science and engineering including those dealing with real applications. The physical problem is modeled by partial differential equations (PDEs) and involve optimization of some quantity. The PDEs are in most cases nonlinear and solved using numerical methods. Since such numerical solutions are being used routinely, the recent trend has been to develop numerical methods and algorithms so that the optimization problems can be solved numerically as well using the same PDE-solver. We present here one such numerical method which is based on simultaneous pseudo-time stepping. The efficiency of the method is increased with the help of a multigrid strategy. Application example is included for an aerodynamic shape optimization problem.
Modelling Human Memory
Subhendu Das
International Journal of Engineering and Technology , 2012,
Abstract: We know that computers cannot understand the meaning of its memory. The humans who use the computers have the meaning. Humans are the originator of the computer memory data and live outside the computer box. Therefore the same should be true for human brains also. Along that line we define human memory as a physical object. Humans perform some actions on some objects to produce the data that they need. This data is physical and becomes our memory. All actions require some motivations, reasons, or purposes. This purpose provides the meaning for the data. The human memory is therefore defined as a physical object consisting of three items {data, actions, purpose}. Since we are not alone or isolated, all human actions are performed simultaneously and interactively by many people located at many different places and over many different time periods. These joint actions produce the human memory data. Therefore this global space time (GST) environment is the originator of the human memory, contains the purpose of the memory, and the memory data. Using the laws of conservation of physics we show that the GST preserves this memory for eternity. The paper combines ideas from physics, mathematics, engineering, and neuroscience.
Rethinking Embedded System Design
Subhendu Das
International Journal of Engineering , 2012,
Abstract: Embedded engineering is designed using objects of nature and it also interacts with nature.Therefore it is forced to obey the laws of nature. Nature does not make any assumptions. But allour mathematical and scientific theories do. Therefore these theories cannot be valid forembedded engineering applications. In this paper we present four new laws of nature that allembedded systems follow. These laws are (1) Boundedness (2) Finite time (3) Simultaneity and(4) Complexity. During the last fifty years embedded analog and digital engineering have evolvedand changed significantly. However our mathematical and scientific theories remained in theoriginal state. We select several theories commonly used in embedded engineering and showthat none of them satisfy these laws. As a result, when we implement these theories in ourembedded software, we are forced to add so many patches and kludges to make the engineeringwork, that our systems become very unreliable.
Finite Time Engineering
Subhendu Das
Lecture Notes in Engineering and Computer Science , 2011,
A brief introduction to Combinatorial Game Theory through the analysis of the impartial perfect information game – Nim
Subhendu Saha
Indian Journal of Computer Science and Engineering , 2012,
Abstract: Combinatorial game theory is an upcoming field with wide applications in areas of mathematics and computer science. In this paper, we try to define a combinatorial game. Then we show a very simple example of one such game. Finally we discuss about Nim that belongs to a special class of games known as impartial games and we look at the winning strategies for that game.
Advances in the Synthesis of Biologically Important 1,2,4-Trioxanes
Subhendu Chakroborty
Asian Journal of Biomedical and Pharmaceutical Sciences , 2012,
Abstract: Artemisinin and its semisynthetic daughters having 1, 2, 4-trioxane ring system has become the drugs of choice in the treatment of malariachemotherapy. The incorporation of substituents into the central peroxide ring as well as further ring annulation are efficient approaches for the preparation of other active derivatives and has attracted much attention worldwide for tackling the forthcoming problem of multi-drug resistant malaria. The present review addresses the most significant contemporary status of synthesis for 1, 2, 4-trioxane scaffolds as well as their hybrids as reported in the literature up to middle of 2012
Muon anomalous magnetic moment constrains models with excited leptons
Subhendu Rakshit
Physics , 2001,
Abstract: We explore the possibility of the existence of excited leptons in the light of recent data on muon $g - 2$ from BNL. We have been able to put stringent bounds on the relevant parameter space.
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