Kadomtsev–Petviashvili equation for dust ion-acoustic solitons in pair-ion plasmas

Using the reductive perturbation method, we have derived the Kadomtsev-Petviashvili (KP) equation to study the nonlinear properties of electrostatic collisionless dust ion-acoustic solitons in the pair-ion (p-i) plasmas. We have chosen the fluid model for the positive ions, the negative ions, and a fraction of static charged (both positively and negatively) dust particles. Numerical solutions of these dust ion-acoustic solitons are plotted and their characteristics are discussed. It is found that only the amplitudes of the electrostatic dust ion-acoustic solitons vary when the dust is introduced in the pair-ion plasma. It is also noticed that the amplitude and the width of these solitons both vary when the thermal energy of the positive or negative ions is varied. It is shown that potential hump structures are formed when the temperature of the negative ions is higher than that of the positive ions, and potential dip structures are observed when the temperature of the positive ions supersedes that of the negative ions. As the pair-ion plasma mimics the electron-positron plasma, thus our results might be helpful in understanding the nonlinear dust ion acoustic solitary waves in super dense astronomical bodies.     

Asymptotic Normality of a Combined Regression Estimator

In this paper, we propose a combined regression estimator by using a parametric estimator and a nonparametric estimator of the regression function. The asymptotic distribution of this estimator is obtained for cases where the parametric regression model is correct, incorrect, and approximately correct. These distributional results imply that the combined estimator is superior to the kernel estimator in the sense that it can never do worse than the kernel estimator in terms of convergence rate and it has the same convergence rate as the parametric estimator in the case where the parametric model is correct. Unlike the parametric estimator, the combined estimator is robust to model misspecification. In addition, we also establish the asymptotic distribution of the estimator of the weight given to the parametric estimator in constructing the combined estimator. This can be used to construct consistent tests for the parametric regression model used to form the combined estimator.     

Modification of the spectra of correlated charm-anticharm quark pairs in the quark-gluon plasma

Heavy quarks play an important role in probing the properties of strongly interacting quark-gluon plasma(QGP)created in ultra-relativistic heavy-ion collisions.We study the interactions of single heavy(charm)quarks and correlated charm and anticharm(ccˉ)quark pairs with the medium constituents of QGP by performing fireball+Langevin simulations of the pertinent Brownian motion with elastic collisions.Besides studying the traditional observables,the nuclear modification factor and the elliptic flow of single heavy quarks in QGP for different thermal relaxation rates,we also study the broadening of the azimuthal correlations of charm and anticharm quark pairs in the QGP medium for different relaxation rates and transverse momenta classes.We quantified the smearing of ccˉpair azimuthal correlations with an increasing thermal relaxation rate:while the(nearly)back-to-back correlations among ccˉpairs are almost completely washed out at low transverse momentum(pT),these correlations at high pT largely survive the pair diffusion.This provides a novel observable for diagnosing the properties of QGP.     

Successful computer guided planned synthesis of (4R)-thiazolidine carboxylic acid and its 2-substituted analogues as urease inhibitors

By using internal combinatorial library we were able to identify (4R)-thiazolidines carboxylic acid and its 2-substituted analogs as active inhibitors of urease. Molecular modeling and virtual screening were utilized to find out potential compounds. Computational techniques were employed at database of 90,000 ligands and selected the structure representing the low energy conformations, Grid and FlexX docking algorithms were used and the top binding ligands were synthesized and screened in wet-lab.     

Density and Correlations in Large One and Three Dimensional Systems of Fermions

The density and correlations are studied for a system of fermions moving in an average harmonic oscillator potential in one and three dimensions when the number of fermions are large. The technique is based on the use of Mehler's formula for the product of two Hermite functions and con-. tour integrations. Wigner transform is then calculated using this technique. It is shown that it becomes a step function when number of fermions become large. By integrating out momenta, an expression for the density of fermions is derived. Two-particle correlation function is studied in detail. Dyson's type of correlations for a system of nucleons is studied. The connection between one dimensional system of fermions and eigenvalues of a random Hermitean Hamiltonian is shown. The Coulomb energy difference of isobars is studied using nucleon density and correlations.     

Significance of activation energy and Wu's slip features in Cross nanofluid with motile microorganisms

The current article investigates the impact of the bioconvection in an unsteady flow of magnetized Cross nanofluid with gyrotactic microorganisms and activation energy over a linearly stretched configuration. The analysis has been performed by utilizing the realistic Wu's slip boundary and zero mass flux conditions. The effects of nonlinear thermal radiation and the activation energy are also addressed. The governing flow equations are deduced to a dimensionless form by considering suitable transformations which are numerically targeted via a shooting algorithm. The physical visualization of each physical parameter governing the flow problem has been displayed graphically for distribution of velocity, temperature, concentration and motile microorganisms. The numerical treatment for the variation of skin friction coefficient, local Nusselt number, local Sherwood number and motile density number is performed in tabular forms.     

Reply to the comment on ‘Modified perturbation series for the anharmonic oscillator using linearization technique’

It is pointed out that the value of the perturbed energy calculated in the comment by Rath and Pattnayak, is incorrect. When the coupling parameter has the value unity, the energy up to second order of perturbation theory is 0.801 compared to its exact value of 0.804. The suggested split of the Hamiltonian into an unperturbed and perturbed part does not seem to be of any use as the unperturbed part contains anharmonic terms.     

Spectroscopic studies of laser induced aluminum plasma using fundamental,second and third harmonics of a Nd:YAG laser

In the present work, we have studied the spatial evolution of the aluminum plasma produced by the fundamental (1064 nm), second (532 nm) and third (355 nm) harmonics of a Q-switched pulsed Nd:YAG laser. The experimentally observed line profiles of neutral aluminum have been used to extract the excitation temperature using Boltzmann plot method whereas the electron number density has been determined from the Stark broadened profiles. Besides we have studied the variation of excitation temperature and electron number density as a function of laser irradiance at atmospheric pressure. In addition, we have performed quantitative analysis of photon absorption and vapor ionization mechanism at three laser wavelengths and estimated the inverse bremsstrahlung (IB) absorption and photoionization (PI) coefficients. The validity of the assumption of local thermodynamic equilibrium is discussed in the light of the experimental results.