University of Calcutta (informally known as Calcutta University or CU) is a collegiate public state university located in Kolkata, West Bengal, India.&nbsp;Within India it is recognized as a &quot;Five-Star University&quot; and accredited &quot;A&quot; Grade by National Assessment and Accreditation Council.

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The University of Calcutta has secured the Fifth position among the Universities of India in the prestigious &quot;Indian University Ranking 2019&quot; list, released by the NIRF of the Ministry of Human Resource Development, Government of India.

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It was established on 24 January 1857, and was one of the first institutions in Asia to be established as a multidisciplinary and Western-style university. Its alumni and faculty include several heads of state, heads of government, social reformers, prominent artists, only academy award winner and Dirac medal winner in India, many Fellows of the Royal Society and five Nobel laureates as of 2019 which is highest in South Asia.

University Of Calcutta

Applied Mathematics

Source-independent quantum networks are considered as a natural generalization to the Bell scenario where we investigate the nonlocal properties of quantum states distributed and measured in a network. Considering the simplest network of entanglement swapping, recently Gisin et al. [Phys. Rev. A 96, 020304(R) (2017)10.1103/PhysRevA.96.020304] and Andreoli [New. J. Phys. 19, 113020 (2017)10.1088/1367-2630/aa8b9b] independently provided a systematic characterization of the set of quantum states leading to violation of the so-called bilocality inequality. In this work, we consider the complexities in quantum networks with an arbitrary number of parties distributed in chain-shaped and star-shaped networks. We derive the maximal violation of the "n-local"inequality that can be achieved by arbitrary two-qubit states for such chain- and star-shaped networks. This would further provide a deeper understanding of quantum correlations in complex structures. © 2020 American Physical Society.

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Physical Review A

Maximal qubit violation of n -local inequalities in a quantum network

Experimental demonstration of entanglement needs to have a precise control of experimentalist over the system on which the measurements are performed as prescribed by an appropriate entanglement witness. To avoid such trust problem, recently, device-independent entanglement witnesses (DIEWs) for genuine tripartite entanglement have been proposed where witnesses are capable of testing genuine entanglement without precise description of Hilbert space dimension and measured operators i.e. apparatus are treated as black boxes. Here, we design a protocol for enhancing the possibility of identifying genuine tripartite entanglement in a device independent manner. We consider three mixed tripartite quantum states none of whose genuine entanglement can be detected by applying certain DIEWs, but their genuine tripartite entanglement can be detected by applying the same when distributed in some suitable entanglement swapping network. © 2020, Springer Science+Business Media, LLC, part of Springer Nature.

Quantum Information Processing

Detection of genuine tripartite entanglement in quantum network scenario

The dynamical behaviour of weakly nonlinear, low-frequency sound waves are investigated in a plasma composed of only positive and negative ions incorporating the effects of a weak external uniform magnetic field. In the plasma model the mass (temperature) of the positive ions is smaller (larger) than that of the negative ions. The dynamics of the nonlinear wave is shown to be governed by a novel nonlinear equation. The stationary plane wave (analytical and numerical) nonlinear analysis on the basis of experimental parameters reveals that the nonlinear wave does have quasi-periodic and chaotic solutions. The Poincarè return map analysis confirms these observed complex structures. Copyright © The Author(s), 2020. Published by Cambridge University Press.

Journal of Plasma Physics

Chaos in positive ion-negative ion magnetized plasmas

Dispersal-induced pattern formation is important from both fundamental and application points of view. Spatial pattern in an ecological system can strongly depend on exogenous factors like arrangement of the natural and artificial physical features of the habitat (topography) and distribution of resources. It is also influenced by endogenous factors (intrinsic biological forces) such as the ecological interactions of individuals. Here, we consider a discrete space–time host–parasitoid metapopulation model in the presence of both self-diffusion (due to endogenous factors) and cross-diffusion (due to exogenous factors). Dynamics of a metapopulation system consists of a dispersal stage and a reaction stage. In the dispersal stage, populations from an individual site can disperse to the nearest neighboring sites via dispersal and may cause variation in the host and parasitoid biomass of the node. In the reaction stage, hosts and parasitoids interact in each site and their local interaction is governed by the modified Nicholson–Bailey-type interaction. The conditions for the existence of pattern-forming instabilities (like Turing, Hopf and Hopf–Turing) in the reaction–diffusion discrete metapopulation model have been determined analytically, and the patterns have been visualized numerically. A wide range of complex spatiotemporal patterns (like periodic, quasi-periodic, chaotic) is observed with respect to the variation of diffusion coefficients and other local interacting parameters of the model. © 2020, Springer Nature B.V.

Nonlinear Dynamics

Dispersal-induced pattern-forming instabilities in host–parasitoid metapopulations

Based upon the Lord and Shulman theory of thermoelasticity, the new governing equations of thermoelasticity with nonlocal heat conduction are formulated. The above model is then employed to study the transient responses of a thermoelastic rod of finite length when subjected to a moving heat source. Both ends of the rod are assumed to be fixed and thermally insulated. The Laplace transform technique is used to obtain the analytical solutions for the field variables such as temperature, displacement, and stress. The inverse Laplace transform based on the Zakian algorithm is numerically implemented to obtain the solutions of the above physical variables in the space–time domain. Specific attention is paid to the study of the effect of the thermal nonlocal parameter on the distributions of the field variables and the speed of the moving heat source. © 2019, Springer-Verlag GmbH Austria, part of Springer Nature.

Acta Mechanica

Thermoelastic responses of a finite rod due to nonlocal heat conduction

A novel model of the generalized magneto-thermoelasticity with two-temperature theory is investigated. The memory-depended derivative (MDD) during the excitation processes by pulsed laser is established for a time-dependent material. The overlapping between an isotropic homogeneous thermoelastic half-space medium and the non-Gaussian laser pulse in one-dimensional space with time delay is obtained. The semi-infinite bounding surface of the elastic medium is taken as traction free and subject to a thermal shock problem in a time-dependent case. Laplace transformation technique is used to obtain the initial solutions of the main physical field which defined in the governing equations. The temporal complete solutions in Laplace time domain obtained by using the inversion method of the Laplace transform, to obtain the general solution (exact solution) for some physical quantities. Numerical results are performed with discussed for suitable elastic medium and illustrated graphically, taken into consideration the time-delay parameters. © 2020 Informa UK Limited, trading as Taylor & Francis Group.

Waves in Random and Complex Media

Memory-dependent derivatives (MDD) of magneto-thermal-elastic waves excited by laser pulses for two-temperature theory

The present study is concerned with the reflection of magneto-thermoelastic plane waves from stress free and thermally insulated surface in a homogeneous isotropic thermally conducting elastic half-space medium. The modified Green–Lindsay (MGL) theory of generalized thermoelasticity has employed with two temperatures (2 T). The thermoelastic coupling effect creates two types of coupled longitudinal waves which are dispersive as well as exhibit attenuation. There exist also due to the thermoelastic coupling one independent vertically shear (SV-wave) wave. In contrast to the classical Green–Lindsay (GL) and Lord–Shulman (LS) theories of generalized thermoelasticity, the SV-wave is not only dispersive in nature but also experiences attenuation. Analytical expressions for the reflection coefficients and their respective energy ratios for reflected thermoelastic waves have been determined when the coupled longitudinal wave incident on the free surface. A numerical result on the reflection coefficients and their respective energy ratios for the specific parameter has been calculated. Various graphs have been plotted to analyze the behavior of these quantities. The characteristics of employing the 2TMGL model are discussed by comparing the numerical results obtained for the present model with those in the classical GL model. © 2020, © 2020 Taylor & Francis Group, LLC.

Journal of Thermal Stresses

Reflection of magneto-thermoelastic waves at a solid half-space under modified Green–Lindsay model with two temperatures

In this paper, we have considered a discrete prey-predator model with square-root functional response and optimal harvesting policy. This type of functional response is used to study the dynamics of the prey-predator model where the prey population exhibits herd behavior, i.e., the interaction between prey and predator occurs along the boundary of the population. The considered population model has three fixed points; one is trivial, the second one is axial and the last one is an interior fixed point. The first two fixed points are always feasible but the last one depends on the parameter value. The interior fixed point experiences the flip and Neimark-Sacker bifurcations depending on the predator harvesting coefficient. Finally, an optimal harvesting policy has been introduced and the optimal value of the harvesting coefficient is determined. © 2020 World Scientific Publishing Company.

Journal of Biological Systems

STABILITY and BIFURCATION ANALYSIS of A DISCRETE PREY-PREDATOR MODEL with SQUARE-ROOT FUNCTIONAL RESPONSE and OPTIMAL HARVESTING

Electron acoustic waves are found to be susceptible to various structure formation. Distinct appearance of structures depend on parameter space. We have shown that weakly nonlinear electron acoustic wave in presence of an external uniform weak magnetic field is governed by a generalized three-dimensional Korteweg-de Vries equation. The Painlevé analysis shows that this equation is conditionally integrable. Exact solutions with the help of Bäcklund transformation reveal that the nonlinear electron acoustic wave does support breather, bursts, soliton and periodic structures. The results are discussed in the context of experiments and observations. © 2020 IOP Publishing Ltd.

Physica Scripta

Nonlinear structure formation of electron acoustic waves in plasmas

A theoretical model is presented to study the characteristics of dust acoustic shock in a viscous, magnetized, rotating dusty plasma at both fast and slow time scales. By employing the reductive perturbation technique, the non-linear Zakharov–Kuznetsov–Burger (ZKB) equation is derived for both cases when the dust is inactive and dynamic (fast and slow time scales). Both electrons and ions are considered to follow the kappa/Cairns distribution. It is observed that in both cases, i.e. when dust is in the background and active, viscosity plays a key role in dissipation for the propagation of acoustic shock. Magnetic field and rotation are responsible for the dispersive term. Superthermality is found to affect significantly the formation of the shock wave along with viscous nature of plasma, whereas the dust charge affects the non-linear coefficient of the ZKB equation. The present investigation may be beneficial to the understanding of the rotating plasma, in particular the experiments being carried out. © 2020 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim