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This study presents a novel application of soft-computing through intelligent, neural networks backpropagated by Levenberg–Marquardt scheme (NNs-BLMS) to solve the mathematical model of unsteady thin film flow of magnetized Maxwell fluid with thermo-diffusion effects and chemical reaction (TFFMFTDECR) over a horizontal rotating disk. The expression for thermophoretic velocity is accounted. Energy expression is deliberated with the addition of non-uniform heat source. The PDEs of mathematical model of TFFMFTDECR are transformed to ODEs by the application of similarity transformations. A dataset is generated through Adams method for the proposed NNs-BLMS in case of various scenarios of TFFMFTDECR model by variation of rotation parameter, magnetic parameter, space dependent heat sink/source parameter, temperature dependent heat sink/source parameter and chemical reaction controlling parameter. The designed computational solver NNs-BLMS is implemented by performing training, testing and validation for the solution of TFFMFTDECR system for different variants. Variation of various physical parameters are designed via plots and explain in details. It is depicted that thin film thickness increases for higher values of disk rotation parameter, while it diminishes for higher magnetic parameter. Furthermore, higher values of Dufour number and the corresponding diminishing values of Soret number causes enhancement in fluid temperature profile. Further the effectiveness of NNs-BLMS is validated by comparing the results of the proposed solver and the standard solution of TFFMFTDECR model through error analyses, histogram representations and regression analyses.

Manganese ferrite spinel has been synthesized by using low grade manganese ore and ferric oxide as sources of manganese oxide and iron oxide through solid state reaction route by taking manganese and iron mole ratio of 1:2 respectively. The impact of sintering temperature on phase composition and particle size is investigated. Similarly, the impact of frequency on dielectric constant, dielectric loss, AC (alternating current) conductivity and tangent losses is also investigated. The results shows the presence of spinel structure manganese ferrite (MnFe2O4) as the major phase for the sample sintered at 1200 °C. It has been established that the crystallite size increase with rise in sintering temperature. The surface morphology of the sample sintered at 1200 °C show pyramidal and triangular shape grains. The dielectric constant (εʹ) and dielectric losses (εʹʹ) were observed to decrease with increasing the sintering temperature and frequency. Furthermore, the AC (alternating current) conductivity was found to rise with rise in applied frequency. On the other hand, the tangent losses falls considerably with rise in applied frequency.

The propagation of dust ion acoustic waves (DIAWs) for two-temperature ions with isothermal electrons in dusty plasmas has been investigated. Using the reductive perturbation method, the Gardner equation is derived. Many analytical solutions have been presented for small but finite amplitude acoustic waves, e.g. solitary and shocklike waves. The effects of many parameters on the feature of the shocklike waves have been studied for the dusty plasma system. The results of this study could be helpful for understanding the existence of nonlinear potential structures those are observed in various cosmic dust-laden plasmas, such as Saturn's E-ring, noctilucent clouds, Halley's comet and interstellar molecular clouds.

The severe disease outbreak COVID-19 pandemic impacted public health and safety and the educational systems worldwide. For fear of the further spread of diseases, most educational institutions, including Bangladesh, have postponed their face-to-face teaching. Therefore, this study explores public university student's perceptions towards online classes during the COVID-19 pandemic in Bangladesh. Data were collected among students of Islamic University, Kushtia, Bangladesh, through an online survey. The study followed both a qualitative and quantitative approach, where the survey technique was used as an instrument of data collection. Results showed that most students were facing difficulty participating in virtual classes and could not communicate with their friends correctly during online classes. They faced challenges in online schooling, and the majority of the students preferred conventional types of learning to virtual classes and did not understand the content of virtual classes easily. The study also explored that most students did not feel comfortable in online classes. Still, considering the present pandemic situation, they decided to participate in online classes to continue schooling. Besides, the study discovered that female students showed better real perceptions than male students regarding online classes, and urban students have more optimistic appreciation than rural students. Moreover, laptop or personal computer users showed more positive perceptions towards online education than mobile users. Furthermore, Broadband/ Wi-Fi users have more positive perceptions than mobile network users. These findings would be an essential guideline for governments, policymakers, technology developers, and university authorities for making better policy choices in the future.

A novel compact honeycomb spectroscopic-based PCF sensor for the detection of tuberculosis cells is proposed. A circular shape core area and tightly bound hexagonal shape air holes in the cladding area are designed for the suggested structure that exhibits ultra-high sensitivity up to 99.99% and very low loss of order 10-11 dB/m. The optical parameters such as effective area (Aeff), V-parameter or normalized frequency (Veff), spot- size (Weff), numerical aperture, along quality factor of beam have been exhibited and numerically observed. The wavelength operating region is specified as 1.2 μm to 2.5 μm. The guiding properties of this suggested tuberculosis sensor is computed with the full vector finite element method (FV-FEM) in the environment of COMSOL Multiphysics (Version5.3) for the calculation of numerical analysis. Circular shape perfectly matched layer (PML) and hexagonal lattice PCF sensor using silica as a background material is successfully designed to increase the sensitivity response compare to the prior works. Moreover, during the entire operating wavelength presented sensor achieves a single modality. With excellent sensitivity response and very low confinement loss, this proposed sensor doubtfully proves its prominent role to detect tuberculosis cells.

Changing career path can be daunting but there are big rewards for those who are brave enough to switch. M S Zobaer describes his unexpected journey from dusty plasmas to neuroscience

A physiologically based model of arousal dynamics is improved to incorporate the effects of the light spectrum on circadian phase resetting, melatonin suppression, and subjective sleepiness. To account for these nonvisual effects of light, melanopic irradiance replaces photopic illuminance that was used previously in the model. The dynamic circadian oscillator is revised according to the melanopic irradiance definition and tested against experimental circadian phase resetting dose-response and phase response data. Melatonin suppression function is recalibrated against melatonin dose-response data for monochromatic and polychromatic light sources. A new light-dependent term is introduced into the homeostatic weight component of subjective sleepiness to represent the direct alerting effect of light; the new term responds to light change in a time-dependent manner and is calibrated against experimental data. The model predictions are compared to a total of 14 experimental studies containing 26 data sets for 14 different spectral light profiles. The revised melanopic model shows on average 1.4 times lower prediction error for circadian phase resetting compared to the photopic-based model, 3.2 times lower error for melatonin suppression, and 2.1 times lower error for subjective sleepiness. Overall, incorporating melanopic irradiance allowed simulation of wavelength-dependent responses to light and could explain the majority of the observations. Moving forward, models of circadian phase resetting and the direct effects of light on alertness and sleep need to use nonvisual photoreception-based measures of light, for example, melanopic irradiance, instead of the traditionally used illuminance based on the visual system.

Using the hydrodynamic equations of positive and negative ions, Boltzmann electron density distribution for degenerate electron pressure, and Poisson equation with stationary dust, a further modified Korteweg–Vries equation is derived for small but finite amplitude dust-ion-acoustic waves. ‘ $$G'/G$$ ’ method is used to obtain a new class of solutions. The effects of physical parameters on astrophysical compact objects, and thus the nonlinear solitary and shock structures are examined corresponding to traveling waves.

Rift Valley fever is the most terrifying animal disease around the globe, which transfers through mosquitoes and caused by a virus. This infection is life-threatening and heavily affects the economic sectors. Therefore, it is valuable to conceptualize the dynamics of Rift Valley fever to understand its transmission pathway to provide better control policies. Here, we construct an epidemic model for Rift Valley fever with vaccination through fractional derivatives. Firstly, we present the proposed Rift Valley fever dynamics in the Caputo framework. The basic knowledge of fractional calculus is used to determine the rudimentary properties of the proposed fractional model, which include positivity, uniqueness, and boundedness of the solutions. We investigate our constructed model of Rift Valley fever for equilibria and determined the basic reproduction number of the system through next-generation technique, indicated by R0. The stability results are established for the infection-fee steady-state of the system. Numerical simulations are conducted and sensitivity analysis of R0 through partial rank correlation coefficient (PRCC) method is carried out to show the importance of different parameters in R0. Then the Rift Valley fever model is analyzed in the Atangana-Baleanu framework, furthermore, we present a numerical scheme for the proposed fractional model to illustrate the solution pathway of the model. We notice that the fractional-order dynamics can explain the complex system of Rift Valley fever infection more precisely and accurately rather than the integer-order dynamics. It is also observed that the Atangana-Baleanu operator provides more accurate results than the Caputo fractional derivative.

Evoked response potentials (ERPs) and other transients are modeled as impulse responses using physiology-based neural field theory (NFT) of the corticothalamic system of neural activity in the human brain that incorporates synaptic and dendritic dynamics, firing response, axonal propagation, and corticocortical and corticothalamic pathways. The properties of model-predicted ERPs are explored throughout the stability zone of the corticothalamic system, and predicted time series and wavelet spectra are also analyzed. This provides a unified treatment of predicted ERPs for both normal and abnormal states within the brain's stability zone, including likely parameters to represent abnormal states of reduced arousal.

The nonlinear propagation of the dust-acoustic (DA) waves in a strongly coupled dusty plasma containing Maxwellian electrons, nonthermal ions, and positively charged dust is theoritically investigated by a Burgers equation. The effects of the polarization force (which arises due to the interaction between electrons and highly positively charged dust grains) and nonthermal ions are studied. DA shock waves are found to exist with positive potential only. It represents that the strong correlation among the charged dust grains is a source of dissipation, and is responsible for the formation of DA shock waves. The effects of polarization force and nonthermal ions significantly modified the basic features of DA shock waves in strongly coupled dusty plasma.

This theoretical investigation has been made on dust-acoustic (DA) waves containing nonextensivity of electrons being two different temperatures, negatively charged dust grains, and Maxwellian ions. The Zakharov-Kuznetsov (Z-K) equation has been derived and numerically solved to analysis the basis features. It is observed that the characteristics of the DA solitary waves (DASWs) are significantly modified by the external magnetic field with the different temperatures for electrons followed by the nonextensive distribution. The results obtained from this analysis can be employed in understanding the nature of plasma waves both in laboratory and space plasma system.

Our objective here is to investigate a strongly coupled dusty plasma system with the presence of polarization force (PF). This plasma consists of superthermal electrons, Maxwellian ions, and negatively charged dust grains. The nonlinear propagation of dust-acoustic (DA) waves in such dusty plasma system has been theoretically investigated by employing the reductive perturbation method. The Burgers’ and K-dV equations have been derived to and numerically analyzed. It has been found that the dust-acoustic shock and solitary waves exist associated with a negative potential only, and that the effect of the dust fluid temperature significantly modifies the basic properties (amplitude and width) of such nonlinear waves’ potential structures. We hope that the results of our present investigation should help us in understanding the localized electrostatic disturbances in space and laboratory strongly coupled dusty plasmas with superthermal electrons and polarization force.

A rigorous theoretical investigation is made on the highly nonlinear propagation of electrostatic shock waves in degenerate dense two-fluid plasma with relativistic electrons and inertial ions with the additional negatively charged dust grains. 1-D evolution of electrostatic shock waves is found to exist in such a plasma system employing the reductive perturbation method. It is also found that a highly nonlinear wave can propagate in the system whose profiles are showed with the solution of modified Burgers' equation with the usual one. This is an unique finding among all the theoretical investigations made before whose probable implications are discussed in this investigation. The implications of the results obtained from this unique investigation in space and laboratory experiments are briefly discussed.

A rigorous theoretical investigation has been made on the nonlinear structures, mainly, dust-acoustic (DA) solitary and shock waves propagating in a strongly coupled dusty plasma consisting of strongly coupled correlated positively and negatively charged inertial cold dust fluid, weakly correlated inertialess Maxwellian electron and ion fluids. The presence of arbitrary (negative and positive) charged dust grains in such a plasma system causes the presence opposite potentials (positive and negative) DA solitary and shock structures and significantly modify it’s basic features. The results obtained from this analysis can be employed in understanding the nature of plasma waves both in laboratory and space plasma system.

We have studied the nonlinear propagation of dust ion-acoustic (DIA) waves in a dusty multi-ion dense plasma (with the constituents being degenerate, either non-relativistic or ultra-relativistic) and the propagation of such waves have been investigated by the reductive perturbation method. From the stationary solution of the Korteweg de-Vries (K-dV) equation and Burgers’ equation the nonlinear waves (specially, solitary and shock waves) have been found to be formed in the dusty plasma system under consideration. It has shown that the basic features of these waves are significantly modified by both the positive and negative ions and dust number densities, the degenerate of the constituents. The implications of our results have been briefly discussed.

A theoretical investigation on the nonlinear propagation of ion-acoustic waves in a degenerate dense plasma has been made by employing the reductive perturbation method. The Burger's equation has been derived, and numerically analyzed. The basic features of electrostatic shock structures have been examined. It has been shown that the plasma system under consideration supports the propagation of electrostatic shock structures. The implications of our results (obtained from this investigation) in compact astrophysical objects have been briefly discussed.

Nonlinear propagation of dust-ion-acoustic waves in a degenerate dense plasma (with the constituents being degenerate, for both the limits non-relativistic or ultra-relativistic) have been investigated by the reductive perturbation method. The Korteweg de-Vries (K-dV) equation and Burger’s equation have been derived, and the numerical solutions of those equations have been analyzed to identify the basic features of electrostatic solitary and shock structures that may form in such a degenerate dense plasma. The implications of our results in compact astrophysical objects, particularly, in white dwarfs, have been briefly discussed.

The nonlinear propagation of waves (specially solitary waves) in an ultra-relativistic degenerate dense plasma (containing ultra-relativistic degenerate electrons and positrons, cold, mobile, inertial ions, and negatively charged static dust) have been investigated by the reductive perturbation method. The linear dispersion relation and Korteweg de-Vries equation have been derived whose numerical solutions have been analyzed to identify the basic features of electrostatic solitary structures that may form in such a degenerate dense plasma. The existence of solitary structures has been also verified by employing the pseudo-potential method. The implications of our results in astrophysical compact objects have been briefly discussed.

The nonlinear propagation of the DIA (dust ion-acoustic) waves in multi-ion dense plasma system containing degener- ate electrons, both positive and negative ions, arbitrary charged dust grains has been investigated by employing the reductive perturbation method. The nonlinear waves (solitary and shock waves) have been observed to be formed in case of both positive and negative charged dust grains from the stationary solution of the Korteweg de-Vries (K-dV) equation and Burger’s equation. The fundamental properties of such nonlinear waves have been theoretically analyzed by comparing system potential for both positive and negative dust grains. It has been shown that the basic features of these waves are significantly modified by the positive and negative ions drift speed and polarities of dust grains. The implications of our results in space and laboratory plasmas are briefly discussed.

The nonlinear propagation of dust ion-acoustic (DIA) waves in a unmagnetized collisionless degenerate dense plasma (containing degenerate electron and positron, and classical ion fluids) has been theoretically investigated. The K-dV equation has been derived by employing the reductive perturbation method and by taking into account the effect of different plasma parameters in plasma fluid. The stationary solitary wave solution of K-dV equation is obtained, and numerically analyzed to identify the basic properties of DIA solitary structures. It has been shown that depending on plasma parametric values, the degenerate plasma under consideration supports compressive or rarefactive solitary structures. It has been also found that the effect of pressures on electrons, ions, and positrons significantly modify the basic features of solitary waves that are found to exist in such a plasma system. The relevance of our results in astrophysical objects such as white dwarfs and neutron stars, which are of scientific interest, is discussed briefly.

The properties of ion-acoustic shock waves and double layers propagating in a viscous degenerate dense plasma (containing inertial viscous ion fluid, non-relativistic and ultra-relativistic degenerate electron fluid, and negatively charged stationary heavy element) is investigated. A new nonlinear equation (viz. Gardner equation with additional dissipative term) is derived by the reductive perturbation method. The properties of the ion-acoustic shock waves and double layers are examined by the analysis of the shock and double layer solutions of this new equation (we would like to call it “M-Z equation”). It is found that the properties of these shock and double layer structures obtained from this analysis are significantly different from those obtained from the analysis of standard Gardner or Burgers’ equation. The implications of our results to dense plasmas in astrophysical objects (e.g., non-rotating white dwarf stars) are briefly discussed.

A rigorous theoretical investigation has been made of basic characteristics of the nonplanar dust-ion-acoustic shock and solitary waves in electronegative dusty plasma containing Boltzmann electrons, Boltzmann negative ions, inertial positive ions, and charge fluctuating (negatively charged) stationary dust. The Burgers' and Korteweg–de Vries (K-dV) equations, which is derived by reductive perturbation technique, is numerically solved to examine the effects of nonplanar geometry on the basic features of the DIA shock and solitary waves formed in the electronegative dusty plasma. The implications of the results (obtained from this investigation) in space and laboratory experiments are briefly discussed.

A theoretical investigation has been made of the nonlinear propagation of ion-acoustic waves associated with a dense plasma system consisting degenerate electron and ion fluids. This fluid model, which is valid for both the non-relativistic and ultra-relativistic limits, has been employed with the reductive perturbation method. The K-dV and modified K-dV (mK-dV) equations have been derived and numerically analyzed. The basic features of solitons have been observed. It has been shown that the plasma system under consideration supports the propagation of solitons (electrostatic solitary structures) obtained from the solutions of K-dV and mK-dV equations. The implications of our results obtained from this investigation in compact astrophysical objects have been briefly discussed.