arXiv subjects

Prasanta K. Panigrahi

Publications and source records attributed to Prasanta K. Panigrahi.

At least 271 records · Page 15Linked to original sources

arXiv2006

Correlations and periodicities in Himalayan tree ring widths and temperature anomalies through wavelets

We have studied periodicities and correlation properties of tree ring width chronology of deodar tree from Joshimath (1584 - 1999 years) and Uttarkashi (1500 - 2002 years) in the western Himalayas and the pre-monsoon (March-April-May) temperature anomalies (1876 - 2003) relative to 1961 -1990 mean, through wavelet analysis. Periodic behavior is observed in the tree ring chronology with periodicity in the form 11, 22, and 42 years. The analysis of the self-similar nature reveals long-range correlation with a Hurst exponent, $H >0.5$. These are anti-correlated with the temperature anomalies. An interesting inversion behavior is observed around the year 1750. The power spectral analysis of the time series corroborate the results of wavelet method.

nlin.CD↗

arXiv2006

Wavelet analysis of event by event fluctuations

The temporal fluctuations of produced hadron density in heavy ion collisions, modelled by 2D Ising model at temperatures $T_c$ and below, are studied through a recently developed wavelet based fluctuation analysis method. At $T_c$, long-range correlated multifractal behavior, matching with the recently observed Hurst exponent $H\simeq 1$, is found. Below $T_c$ uncorrelated monofractal behavior is seen. The correlation behavior compares well with the results obtained from continuous wavelet based average wavelet co-efficient method, as well as with Fourier power spectral analysis.

physics.data-an↗

arXiv2006

Locally Adaptive Block Thresholding Method with Continuity Constraint

We present an algorithm that enables one to perform locally adaptive block thresholding, while maintaining image continuity. Images are divided into sub-images based some standard image attributes and thresholding technique is employed over the sub-images. The present algorithm makes use of the thresholds of neighboring sub-images to calculate a range of values. The image continuity is taken care by choosing the threshold of the sub-image under consideration to lie within the above range. After examining the average range values for various sub-image sizes of a variety of images, it was found that the range of acceptable threshold values is substantially high, justifying our assumption of exploiting the freedom of range for bringing out local details.

cs.CV↗

arXiv2006

Multilevel Thresholding for Image Segmentation through a Fast Statistical Recursive Algorithm

A novel algorithm is proposed for segmenting an image into multiple levels using its mean and variance. Starting from the extreme pixel values at both ends of the histogram plot, the algorithm is applied recursively on sub-ranges computed from the previous step, so as to find a threshold level and a new sub-range for the next step, until no significant improvement in image quality can be achieved. The method makes use of the fact that a number of distributions tend towards Dirac delta function, peaking at the mean, in the limiting condition of vanishing variance. The procedure naturally provides for variable size segmentation with bigger blocks near the extreme pixel values and finer divisions around the mean or other chosen value for better visualization. Experiments on a variety of images show that the new algorithm effectively segments the image in computationally very less time.

cs.CV↗

arXiv2005

Parametrically controlling solitary wave dynamics in modified Kortweg-de Vries equation

We demonstrate the control of solitary wave dynamics of modified Kortweg-de Vries (MKdV) equation through the temporal variations of the distributed coefficients. This is explicated through exact cnoidal wave and localized soliton solutions of the MKdV equation with variable coefficients. The solitons can be accelerated and their propagation can be manipulated by suitable variations of the above parameters. In sharp contrast with nonlinear Schrödinger equation, the soliton amplitude and widths are time independent.

nlin.SI↗

arXiv2005

A new class of exact solitary wave solutions of one dimensional Gross-Pitaevskii equation

We present a large family of {\it{exact}} solitary wave solutions of the one dimensional Gross-Pitaevskii equation, with time-varying scattering length and gain/loss, in both expulsive and regular parabolic confinement regimes. The consistency condition governing the soliton profiles is shown to map on to a {\it{linear}} Schrödinger eigenvalue problem, thereby enabling one to find analytically the effect of a wide variety of temporal variations in the control parameters, which are experimentally realizable. Corresponding to each solvable quantum mechanical system, one can identify a soliton configuration. These include soliton trains in close analogy to experimental observations of Strecker {\it{et al.,}} [Nature {\bf{417}{150}{2002}], spatio-temporal dynamics, solitons undergoing rapid amplification, collapse and revival of condensates and analytical expression of two-soliton bound states, to name a few.

cond-mat.other↗

arXiv2005

Wavelet analysis and scaling properties of time series

We propose a wavelet based method for the characterization of the scaling behavior of non-stationary time series. It makes use of the built-in ability of the wavelets for capturing the trends in a data set, in variable window sizes. Discrete wavelets from the Daubechies family are used to illustrate the efficacy of this procedure. After studying binomial multifractal time series with the present and earlier approaches of detrending for comparison, we analyze the time series of averaged spin density in the 2D Ising model at the critical temperature, along with several experimental data sets possessing multi-fractal behavior.

nlin.CD↗

arXiv2005

Deterministic Bell State Discrimination

We make use of local operations with two ancilla bits to deterministically distinguish all the four Bell states, without affecting the quantum channel containing these Bell states.

quant-ph↗

arXiv2004

Induced magnetic moment in noncommutative Chern-Simons scalar QED

We compute the one loop, $O(þ)$ correction to the vertex in the noncommutative Chern-Simons theory with scalar fields in the fundamental representation. Emphasis is placed on the parity odd part of the vertex, since the same leads to the magnetic moment structure. We find that, apart from the commutative term, a $þ$-dependent magnetic moment type structure is induced. In addition to the usual commutative graph, cubic photon vertices also give a finite $þ$ dependent contribution. Furthermore, the two two-photon vertex diagrams, that give zero in the commutative case yield finite $þ$ dependent terms to the vertex function.

hep-th↗

arXiv2004

Information Entropy and Correlation of the Hooke's Atom

We provide an algebraic procedure to find the eigenstates of two-charged particles in an oscillator potential, known as {\it{Hooke's}} atom. For the planar Hooke's atom, the exact eigenstates and single particle densities for arbitrary azimuthal quantum number, are obtained analytically. Information entropies associated with the wave functions for the relative motion are then studied systematically, since the same incorporates the effect of the Coulomb interaction. The {\it{quantum pottery}} of the information entropy density reveals a number of intricate structures, which differ significantly for the attractive and repulsive cases. We indicate the procedure to obtain the approximate eigen states. Making use of the relationship of this dynamical system with the quasi-exactly solvable systems, one can also develop a suitable perturbation theory, involving the Coulomb coupling $Z$, for the approximate wave functions.

quant-ph↗

arXiv2004

On polynomial solutions of Heun equation

By making use of a recently developed method to solve linear differential equations of arbitrary order, we find a wide class of polynomial solutions to the Heun equation. We construct the series solution to the Heun equation before identifying the polynomial solutions. The Heun equation extended by the addition of a term, $- \s/x$, is also amenable for polynomial solutions.

math-ph↗

arXiv2004

Interior gap superfluidity in a two-component Fermi gas of atoms

A new superfluid phase in Fermi matter, termed as "interior gap" (IG) or "breached pair", has been recently predicted by Liu and Wilczek [Phys.Rev.Lett. {\bf 90}, 047002 (2003)]. This results from pairing between fermions of two species having essentially different Fermi surfaces. Using a nonperturbative variational approach, we analyze the features, such as energy gap, momentum distributions, and elementary excitations associated with the predicted phase. We discuss possible realization of this phase in two-component Fermi gases in an optical trap.

cond-mat.other↗

arXiv2004

Diagnosis of human breast cancer through wavelet transform of polarized fluorescence

Wavelet transform of polarized fluorescence spectroscopic data of human breast tissues is found to reliably differentiate normal and malignant tissue types and isolate characteristic biochemical signatures of cancerous tissues, which can possibly be used for diagnostic purpose. A number of parameters capturing spectral variations and subtle changes in the diseased tissues in the visible wavelength regime are clearly identifiable in the wavelet domain. These investigations, corroborated with tissue phantoms, indicate that the observed differences between malignant tumor and normal samples are primarily ascribable to the changes in concentration of porphyrin and density of cellular organelles present in tumors.

physics.med-ph↗

arXiv2004

Quantum Hamilton-Jacobi analysis of PT symmetric Hamiltonians

We apply the quantum Hamilton-Jacobi formalism, naturally defined in the complex domain, to a number of complex Hamiltonians, characterized by discrete parity and time reversal (PT) symmetries and obtain their eigenvalues and eigenfunctions. Examples of both quasi-exactly and exactly solvable potentials are analyzed and the subtle differences, in the singularity structures of their quantum momentum functions, are pointed out. The role of the PT symmetry in the complex domain is also illustrated.

quant-ph↗

arXiv2003

Quantum information entropies of the eigenstates and the coherent state of the Pöschl-Teller potential

The position and momentum space information entropies, of the ground state of the Pöschl-Teller potential, are exactly evaluated and are found to satisfy the bound, obtained by Beckner, Bialynicki-Birula and Mycielski. These entropies for the first excited state, for different strengths of the potential well, are then numerically obtained. Interesting features of the entropy densities, owing their origin to the excited nature of the wave functions, are graphically demonstrated. We then compute the position space entropies of the coherent state of the Pöschl-Teller potential, which is known to show revival and fractional revival. Time evolution of the coherent state reveals many interesting patterns in the space-time flow of information entropy.

quant-ph↗

arXiv2003

Coherent states for exactly solvable potentials

A general algebraic procedure for constructing coherent states of a wide class of exactly solvable potentials e.g., Morse and P{ö}schl-Teller, is given. The method, {\it a priori}, is potential independent and connects with earlier developed ones, including the oscillator based approaches for coherent states and their generalizations. This approach can be straightforwardly extended to construct more general coherent states for the quantum mechanical potential problems, like the nonlinear coherent states for the oscillators. The time evolution properties of some of these coherent states, show revival and fractional revival, as manifested in the autocorrelation functions, as well as, in the quantum carpet structures.

quant-ph↗

arXiv2003

Exact solitary wave solutions of the nonlinear Schrödinger equation with a source

We use a fractional transformation to connect the traveling wave solutions of the nonlinear Schrödinger equation (NLSE), phase-locked with a source, to the elliptic functions satisfying, $f^{\prime\prime}\pm af\pm λf^{3}=0$. The solutions are {\it necessarily} of the rational form, containing both trigonometric and hyperbolic types as special cases. Bright, and dark solitons, respectively, for attractive and repuslive type of nonlinearities, as also singular solitons, are obtained in suitable range of parameter values.

nlin.SI↗

arXiv2003

Finite Temperature effects on the Induced Chern-Simons term in noncommutative geometry

The one-loop contribution to vacuum polarization is calculated for the adjoint fermions in three dimensional noncommutative spaces, both at zero and finite temperature. At zero temperature, we confirm a previously found result for the parity odd part and subsequently analyze the even parity part, which exhibits UV/IR mixing. We discuss in detail, two regimes of the high temperature behavior of the parity odd part. When the thermal wavelength is much smaller, as compared to the noncommutativity scale, we find an interesting Fermi-Bose transmutation in the nonplanar part.

hep-th↗