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Study of candidate Be stars in the Magellanic Clouds using near-infrared photometry and optical spectroscopy
Mennickent et al. and Sabogal et al. identified a large number of classical Be (CBe) candidates (?3500) in the Large and Small Magellanic Clouds (LMC and SMC) based on their photometric variability using the OGLEII data base. They classified these stars into four different groups based on the appearance of their variability. In order to refine and understand the nature of this large number of stars, we studied the infrared properties of the sample and the spectroscopic properties of a subsample. We cross-correlated the optical sample with the IRSF-MCPS catalogue to obtain the J, H, K s magnitudes of all the four types of stars (?2500) in the LMC and SMC. Spectra of 120 stars belonging to the types 1, 2 and 3 were analysed to study their spectral properties. Among the four types, the type 4 stars are the dominant group, with ?60 and ?65 per cent of the total sample in the LMC and SMC, respectively. The near-infrared (NIR) colour-colour diagrams suggest that the type 4 stars in the LMC have a subclass, which is not found in our Galaxy or in the SMC. This subclass is ?18 per cent of the type 4 sample. The main type 4 sample which is ?49 per cent of the total sample has NIR properties similar to the Galactic CBe stars and the SMC type 4 stars. Though the new subclass of type 4 stars have high E(B-V) ? 0.75, they are not located close to regions with high reddening. The type 3 stars (?6 per cent and 7.3 per cent in the LMC and SMC) are found to have large H? equivalent width (EW) in the SMC and some are found to have large NIR excess. This small fraction of stars are unlikely to be CBe stars. Three stars among the type 3 stars in the LMC are found to be double periodic variables. The type 2 stars are found in larger fraction in the SMC (?14.5 per cent), when compared to the LMC (?6 per cent). The spectroscopic and the NIR properties suggest that these could be CBe stars. The type 1 stars are relatively more in the LMC (?24 per cent) when compared to the SMC (?13 per cent). The SMC type 1 stars have relatively large H? EW and this class has properties similar to CBe stars. The spectroscopic sample of type 1 stars which show H? in emission and are confirmed as CBe stars are more abundant in the SMC by a factor of 2.6. If the effect of metallicity is to cause more CBe stars in the SMC, when compared to the LMC, then type 1, type 2 and type 4 stars follow this rule, with an enhancement of 2.6, 2.4 and 1.3, respectively. 2012 The Authors Monthly Notices of the Royal Astronomical Society 2012 RAS. -
Study of chaos in RayleighBard convection of a micropolar fluid
The paper considers the micropolar fluid (MPF) in a RayleighBard situation and investigates regular and periodic convection, and chaos in the fluid for a wide range of values of the scaled Rayleigh number. The fourth-order scaled Lorenz model that governs weakly non-linear convection is an energy-conserving model whose bounded solution remains within the finiteness of a three-ellipsoid. All the characteristics of the classical Lorenz model are seen in the generalized one. The scaling of the equations is done in such a way that the classical Lorenz model can be obtained as a limiting case of the generalized Lorenz model. The scaled versions of the critical Rayleigh number and the HopfRayleigh number are quantified to determine the onset-of-regular-convection and chaos. Chaotic and periodic regimes appear alternately as the scaled Rayleigh number, r, increases. It is well known from existing literature that the effect of micron-sized particles in the Newtonian fluid is to delay the onset-of-regular-convection. In the paper, it has been found that the suspended particles delay the onset of chaos and the appearance of periodic motion when compared to that in the case of a Newtonian fluid. 2025 Elsevier Ltd -
Study of chaos in the Darcy-Bard convection problem with Robin boundary condition on the upper surface
Possibility of chaos is studied in Darcy-Bard convection using the Dirichlet and the Robin boundary condition at the lower and upper boundaries, respectively. Comparison is made with the results of Dirichlet (classical-Darcy-Bard convection, CDBC) and Neumann boundary condition (Barletta-Darcy-Bard convection, BDBC). It is found that the cell size at onset is bigger in the case of BDBC compared to the generalized-Darcy-Bard convection (GDBC) and much bigger compared to CDBC. The critical-Darcy-Rayleigh number of BDBC is found to be the least and that of CDBC is the largest. Nonlinear-stability-analysis is performed leading to the scaled-generalized-Vadasz-Lorenz model (SGVLM). In deriving this model, help is sought from a local-nonlinear-stability-analysis that yields the form of the convective-mode. The SGVLM is shown to be dissipative and conservative, with its bounded solution trapped within an ellipsoid. Onset of chaos and its characteristics are studied using the Hopf-Rayleigh-number, the Lorenz-butterfly-diagram, and the plot of the amplitude of the convective-mode vs the control-parameter, R, which is the eigenvalue. Chaos sets in earlier in CDBC and much later in BDBC when compared to that in GDBC. Beyond the onset of chaos is seen a sequence of chaotic and periodic motions, with the latter sometimes being present for an extended period. 2024 Author(s). -
Study of classical Be stars in open clusters older than 100 Myr
We performed the slitless spectroscopic survey to identify classical Be (CBe) stars in open clusters older than 100 Myr. Observing a sample of 71 open clusters, we identified 13 CBe stars in 11 open clusters, one of, which (TYC 2679-432-1) is a new detection. The 13 CBe stars show both H? in emission and IR excess, which confirm that they possess gaseous circumstellar discs. Two more CBe stars are found to exhibit H? in absorption for the first time, indicating that might be passing through disc-less episode presently. The spectral-type estimation is done for all these 15 stars and it is noticed that they belong to B0.5B8 type. Moreover, we found that the distribution of our sample is peaking near late B-types as expected. 2021, Indian Academy of Sciences. -
Study of cognitive adaptiveness of isolated Plant Growth Promoting Bacteria in nutritionally stress condition
The biological processes behind bacterial memory in different species are still under terra incognita. Additionally, the ability of learning through association in prokaryotes is still unknown. Cross-fertilization between the study of multicellular creatures' cognitive capacities and that of bacteria is possible. Therefore, Plant Growth Promoting Bacteria (PGPB) can be used to analyze this cognitive adaptation of bacteria under stress because PGPB is crucial to the maintenance of plant physiology and growth under a variety of stress scenarios. This study focuses on analyzing preliminary evidence of cognitive adaptability in PGPB under nutritional stress conditions. The isolated PGPB were treated with nutritional deprivation in both periodical and non-periodical manners and their performance was compared with the control group. The characteristics of PGPB, such as ammonia production, siderophore production, phosphate solubilization and indole-3-acetic acid, as well as anti-oxidant activities such as DPPH activity, hydroxyl radical scavenging activity and hydrogen peroxide scavenging activities, were analysed and compared to periodically and non-periodically stressed PGPB with control. In the isolated PGPB post-nutrition deprivation treatment, it was evident that the periodically stressed performed better than the non-periodically stress-exposed PGPB compared to the control wherein the isolates produced as high as 2.5510 mol mL-1 ammonia, 23.0406 mgL?1 indole-3-acetic acid, 69.16 0.71 psu siderophore and 123.5780.429mgL-1 phosphate solubilised. Out of the four isolated PGPB, the two novel strains, Paenibacillus alvei SJ6 and Paenibacillus alvei SJ8, have shown to possess the supreme ability to adapt to periodic nutritional stress compared to the other isolates in our study. 2025 World Researchers Associations. All rights reserved. -
Study of correlation between optical flux and polarization variations in BL Lac objects
Polarized radiation from blazars is one key piece of evidence for synchrotron radiation at low energy, which also shows variations. We present here our results on the correlation analysis between optical flux and polarization degree (PD) variations in a sample of 11 BL Lac objects using ?10 yr of data from the Steward Observatory. We carried out the analysis on long-term (?several months) as well as on short-term time-scales (?several days). On long-term time-scales, for about 85 per cent of the observing cycles, we found no correlation between optical flux and PD. On short-term time-scales, we found a total of 58 epochs with a significant correlation between optical flux and PD, where both positive and negative correlation were observed. In addition, we also found a significant correlation between optical flux and ?-ray flux variations on long-term time-scales in 11 per cent of the observing cycles. The observed PD variations in our study cannot be explained by changes in the power-law spectral index of the relativistic electrons in the jets. The shock-in-jet scenario is favoured for the correlation between optical flux and PD, whereas the anticorrelation can be explained by the presence of multizone emission regions. The varying correlated behaviour can also be explained by the enhanced optical flux caused by the newly developed radio knots in the jets and their magnetic field alignment with the large-scale jet magnetic field. 2022 The Author(s). -
Study of Effect of Vipassana on Anxiety and Depression
International Journal of Psychology and Behavioral Sciences, Vol-2 (6), pp. 274-276. -
Study of Expression of MST3 in Myeloid Leukaemia
Myeloid leukaemia (ML) is a cancer that occurs by the accumulation of abnormally multiplied myeloid cells in bone marrow, peripheral blood, and other related tissue. MST3 is a gene of the GCK family that has a role in apoptosis, along with other cellular functions like cellular differentiation, cell cycle, metabolism, and others. Objectives: The objectives of this study were to count RBCs and WBCs, study MST3 expression in ML and control samples, and perform an in silico correlation study on the KRAS and NRAS genes. Methods: The counting of RBCs and WBCs was carried out using a hemacytometer, the expression of MST3 was studied using RT-PCR, and a correlation study was carried out using GEPIA. Results: RBC and WBC levels in ML differed from the control levels, and the expression of MST3 was found to be upregulated in ML in comparison to controls, with a 2.908.65-fold change, with a significant p-value > 0.05. A positive correlation in expression was also found between MST3 and KRAS and NRAS genes, with a significant r value correlation. Conclusions: From this study, it could be deduced that MST3 might have a role in ML pathogenesis, but further research is needed to study its role in the progression of the disease. 2025 by the authors. -
Study of generator shaft behaviour during subsynchronous resonance using finite element method
Scientific research in electric power stations includes various online monitoring and control of equipments. Turbine and generator plays a key role in generating power. Frequency response analysis of the shaft which connects turbine and generator is used to detect the steady state response. It will enable the user to understand and design the system in such a way that it can withstand resonance, fatigue and other vibrations. Subsynchronous resonance which arises during line compensation by series capacitors increases oscillations in the turbine generator shaft system. The oscillations developed at low frequency causes physical damage to the shaft. There are several real time monitoring of the rotor shaft and turbine shaft misalignment by using laser technologies. The aim of this research paper is to use frequency response and modal analysis technique to detect the stress in the shaft and improve the design of it. A viscous damper is designed in the 3D model at the point of highly stressed area to control the resonance effect caused by series capacitors. 2020, Levrotto and Bella. All rights reserved. -
Study of heat transfer in a rotating weakly electrically conducting Newtonian fluid: Primary and Kpers-Lortz regimes
In this paper, we study the primary and secondary (Kpers-Lortz) instabilities of rotating RayleighBard convection for a weakly electrically conducting Newtonian fluid with idealistic boundaries. The critical Rayleigh number is obtained for each instability. Fourth-order and ninth-order Lorenz model are derived using the truncated Fourier-Galerkin expansion and the onset of primary and secondary instabilities is studied. Using a non-linear analysis, we derive the expression for the Nusselt number for both primary and secondary instabilities. The analysis reveals that the heat transfer in the case of primary instability is an over-prediction when compared with that of the secondary instability. An increase in the strength of the magnetic field is to delay the onset of primary and secondary instabilities and decrease the heat transfer. These insights advance the understanding of magnetohydrodynamic stability in rotating convective systems and have implications for geophysical and astrophysical fluid dynamics. 2025 Elsevier Masson SAS -
Study of hybrid nanofluid flow in a stationary cone-disk system with temperature-dependent fluid properties
Cone-disk systems find frequent use such as conical diffusers, medical devices, various rheometric, and viscosimetry applications. In this study, we investigate the three-dimensional flow of a water-based Ag-MgO hybrid nanofluid in a static cone-disk system while considering temperature-dependent fluid properties. How the variable fluid properties affect the dynamics and heat transfer features is studied by Reynoldss linearized model for variable viscosity and Chiams model for variable thermal conductivity. The single-phase nanofluid model is utilized to describe convective heat transfer in hybrid nanofluids, incorporating the experimental data. This model is developed as a coupled system of convective-diffusion equations, encompassing the conservation of momentum and the conservation of thermal energy, in conjunction with an incompressibility condition. A self-similar model is developed by the Lie-group scaling transformations, and the subsequent self-similar equations are then solved numerically. The influence of variable fluid parameters on both swirling and non-swirling flow cases is analyzed. Additionally, the Nusselt number for the disk surface is calculated. It is found that an increase in the temperature-dependent viscosity parameter enhances heat transfer characteristics in the static cone-disk system, while the thermal conductivity parameter has the opposite effect. The Author(s) 2024. -
Study of Influence of Combustion on DarcyBard Convection with Inherent Local Thermal Non-equilibrium Between Phases
This work deals with a DarcyBard convection problem in the presence of combustion and with local thermal non-equilibrium between the fluid and the solid phases. The effects of combustion and local thermal non-equilibrium on the onset of convection is studied in the linear and nonlinear regimes. Unlike all reported local thermal non-equilibrium problems reported so far, the present problem has a unique situation of having thermal non-equilibrium not only in the perturbed state but also in the basic state. Further, we observe that local thermal non-equilibrium does not, under any circumstance, lead to local thermal equilibrium except in an approximate sense when the combustion is quite weak. The effect of combustion is to advance the onset of convection compared to that in its absence. The effect of local thermal non-equilibrium is to reinforce the effect of combustion. In the presence of both these effects, sub-critical instability exists. The results are obtained numerically and have implication in practical porous medium convection problems. 2022, The Author(s), under exclusive licence to Springer Nature B.V. -
Study of internal heat source generated natural convection with sinusoidal and non-sinusoidal time-periodic vertical oscillations
This study explores the effect of gravity modulation on natural convection induced by a uniform internal heat source within a fluid-saturated porous medium, a topic of growing relevance in advanced thermal management applications. Four distinct gravity waveforms, square, sinusoidal, triangular, and sawtooth, are examined under three boundary condition combinations: Rigid-Adiabatic-Rigid-Isothermal (RARI), Rigid-Adiabatic-Free-Isothermal (RAFI), and Free-Adiabatic-Free-Isothermal (FAFI). A novel analytical framework is developed by integrating a Maclaurin series expansion with a minimal FourierGalerkin approach to derive a generalized Lorenz model. Linear stability analysis, via a modified Venezian method, to determine the critical internal Rayleigh number and its correction due to modulation. A weakly nonlinear analysis based on the GinzburgLandau equation also provides closed-form expressions for the mean Nusselt number, capturing heat transfer characteristics. The findings demonstrate that square wave modulation most effectively enhances heat transport, followed by sinusoidal, triangular, and sawtooth forms. The influence of key physical parameters reveals that increasing porous parameter (?2) and Brinkman number (?) suppress heat transfer, as do higher Prandtl numbers (Pr) and modulation frequencies (?). FAFI yields the highest heat transfer among the boundary types, while RARI performs the least. The novelty of this work lies in the combined analytical treatment of diverse waveform modulations while considering a uniform internal heat source and boundary condition for natural convection. 2025 The Author(s) -
Study of Kpers?Lortz Instability in a Weakly Electrically Conducting Couple-Stress Fluid
The study aims to investigate the Kpers?Lortz instability in rotating RayleighBard convection of a weakly electrically conducting couple-stress fluid. A novel aspect of this study is the incorporation of weakly electrically conducting couple-stress fluid in a rotating RayleighBard setup to analyze Kpers?Lortz instability and examine heat transfer in both primary and secondary regimes. The main goal is to understand how the combined effects of the couple-stress, rotation, and magnetic field alter stability thresholds and impact the heat transfer. KpersLortz instability (KLI) means the roll systems obtained during the regular convection get deformed and form an angle with each other, making the system unstable. The critical Rayleigh number for regular convection is obtained using linear stability analysis. A ninth-order Lorenz model is obtained using truncated Fourier expansions to study secondary instability. A weak magnetic field (Hartmann number) and couple-stress parameter hinders the onset-of-regular convection. We also obtain the critical values at which the KLI manifests. The critical values are found at a marginal steady state. The Hartmann number and couple-stress parameters hinder the onset-of-secondary instability. Further, the Nusselt number expression is derived, and it is observed that an increase in the couple-stress parameter and Hartmann number diminishes the heat transfer. Additionally, the Nusselt number is obtained for primary and secondary regimes, showing the impact of the parameters on the efficiency of heat transfer in each regime. To validate the results on secondary instability, the study compares its findings with existing literature in the absence of a weak magnetic field and couple-stress effects. A reasonably good agreement is observed, confirming the reliability of the results. 2025 Wiley Periodicals LLC. -
Study of micro and small enterprises' readiness in implementing industry 4.0: A study in marathwada district of maharashtra, india
Industry 4.0 aims tp transform the development of global value chains and the development of a digital revolution, with intelligent machines capable of communicating via wireless connections and a connection thought system, resulting in autonomous decision-making. Although large sized firms are adopting Industry 4.0, the small and micro enterprises are facing great difficulties in adopting them. This study aims to identify the areas in which Enterprises need to focus for improving their level of readiness and develop strategies and plans to adopt Industry 4.0 technologies successfully. 219 samples were collected using snowball sampling from Marathwada District in Maharashtra, India. factor analysis was conducted using SPSS and different factors acting as barriers to implementation of Industry 4.0 technologies were identified. 2023 by IGI Global. All rights reserved. -
Study of mineral and nutritional composition of some seaweeds found along the coast of Gulf of Mannar, India
The presence of Algae on the Earth is ubiquitous. The industry that widely uses algae is food industry, where the algae are used as a food supplement and also as an addition to the nutrient rich food. This study emphasizes on the mineral and nutritional composition of the selected fourteen algal species which are abundantly found along the coast of the Gulf of Mannar. The selected species of algae belong to different algal families such as Chlorophyta, Phaeophyta and Rhodophyta. The amount of minerals such as Ca, Zn, Fe, K, Mg, Mn, and Cu were estimated by employing the method of acid digestion followed by atomic absorption spectroscopy. We estimated the nutritional content based on the assessment of total protein, carbohydrate, phenol, ash and moisture contents of the algal species. The results based on the analysis of the mineral content in the algal seaweeds depicted that the seaweeds comprised of high amount of the macro minerals and trace minerals. Estimation of nutritional composition revealed that these algal species are rich in protein and carbohydrate. The ash contents were found to be very high in Jania rubens (86.66%), Padina boergesenii (85%) and Valoniopsis pachynema (84%). Based on the present study we infer that the algal seaweeds contained high amount of the nutritional compounds, which might pave the way for a higher standard of nutritional supply to the humans in the future. Jose & Xavier (2020). This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution and reproduction in any medium, provided the original author and source are credited (https://creativecommons.org/licenses/by/4.0/). -
Study of multilayer flow of a bi-viscous Bingham fluid sandwiched between hybrid nanofluid in a vertical slab with nonlinear Boussinesq approximation
Bi-viscosity Bingham plastic fluids are used to understand the rheological characteristics of pigment-oil suspensions, polymeric gels, emulsions, heavy oil, etc. In many industrial and engineering problems involving high-temperature situation, a linear density-temperature variation is inadequate to describe the convective heat transport. Therefore, the characteristics of the nonlinear convective flow of a bi-viscous Bingham fluid (BVBF) through three layers in a vertical slab are studied. The two outer layers of the oil-based hybrid nanofluid and the intermediate layer of BVBF are considered. The thermal buoyancy force is governed by the nonlinear Boussinesq approximation. Continuity of heat flux, velocity, shear stress, and temperature are imposed on the interfaces. The governing equations are derived from the Navier-Stokes equation, conservation of energy, and conservation of mass for three layers. The nonlinear multi-point (four-point) boundary value problem is solved using the differential transform method (DTM). Converging DTM solutions are obtained, and they are validated. The entropy equation and Bejan number were also derived and analyzed. It is established that the nonlinear density-temperature variation leads to a significant improvement in the magnitude of the velocity and temperature profiles due to the increased buoyancy force, and as a result, the drag force on the walls gets reduced. The drag force on the slab gets reduced by decreasing the volume fraction of nanoparticles. Furthermore, nonlinear convection and mixed convection give rise to an advanced rate of heat transport on the walls and thereby to an enhanced heat transport situation. 2022 Author(s). -
Study of multilayer flow of non-Newtonian fluid sandwiched between nanofluids
This theoretical investigation examines the nonlinear convective heat transport and multilayer flow of a non-Newtonian fluid within a vertical slab, incorporating viscous heating effects. The middle layer of the slab contains a third-grade fluid, while the outer layers are filled with a water-based Ag-MgO hybrid nanoliquid. Continuity in temperature, heat flux, velocity, and shear stress is maintained at the interfaces of the fluid layers. The thermal buoyancy force is modeled using the nonlinear Boussinesq approximation. The governing system comprises conservation equations for mass, momentum (Navier-Stokes), and energy for each of the three layers. These differential equations are non-dimensionalized, and the resulting dimensionless four-point nonlinear boundary value problem is transformed into a two-point boundary value problem before being solved numerically. For limiting cases, analytical and semi-analytical solutions are computed and used as benchmark results to validate the numerical method employed. Entropy generation analysis indicates that higher third-grade fluid parameters reduce the magnitude of velocity and temperature fields, as well as entropy production across all regions. The third-grade fluid parameter shows a decreasing influence on velocity and temperature fields throughout the system. The continuity of interfacial conditions induces a dragging effect; despite the absence of third-grade fluid parameters in regions I and III, their influence is apparent in these regions. The Bejan number slightly decreases at the walls with increasing third-grade fluid parameters, exhibiting a dual effect in the third-grade fluid layer. Near the walls, the Bejan number decreases as the nanoparticle volume fraction increases. Findings of this work may have applications in polymer industries and processes involving high temperatures. 2024 -
Study of multilayer flow of non-Newtonian fluid sandwiched between nanofluids
This theoretical investigation examines the nonlinear convective heat transport and multilayer flow of a non-Newtonian fluid within a vertical slab, incorporating viscous heating effects. The middle layer of the slab contains a third-grade fluid, while the outer layers are filled with a water-based Ag-MgO hybrid nanoliquid. Continuity in temperature, heat flux, velocity, and shear stress is maintained at the interfaces of the fluid layers. The thermal buoyancy force is modeled using the nonlinear Boussinesq approximation. The governing system comprises conservation equations for mass, momentum (Navier-Stokes), and energy for each of the three layers. These differential equations are non-dimensionalized, and the resulting dimensionless four-point nonlinear boundary value problem is transformed into a two-point boundary value problem before being solved numerically. For limiting cases, analytical and semi-analytical solutions are computed and used as benchmark results to validate the numerical method employed. Entropy generation analysis indicates that higher third-grade fluid parameters reduce the magnitude of velocity and temperature fields, as well as entropy production across all regions. The third-grade fluid parameter shows a decreasing influence on velocity and temperature fields throughout the system. The continuity of interfacial conditions induces a dragging effect; despite the absence of third-grade fluid parameters in regions I and III, their influence is apparent in these regions. The Bejan number slightly decreases at the walls with increasing third-grade fluid parameters, exhibiting a dual effect in the third-grade fluid layer. Near the walls, the Bejan number decreases as the nanoparticle volume fraction increases. Findings of this work may have applications in polymer industries and processes involving high temperatures. 2024 -
Study of multilayer flow of two immiscible nanofluids in a duct with viscous dissipation
Numerical simulations for the mixed convective multilayer flow of two different immiscible nanofluids in a duct with viscous heating effects were performed in this study. The left and right faces of the duct are maintained to be isothermal, while other side faces are insulated. The mathematical governing system for each layer consists of an incompressibility condition equation, the Navier-Stokes momentum equation, and the conservation of energy equation. At the interface of the immiscible layer, the continuity of velocity, shear stress, temperature, and heat flux are considered. The dimensionless equations governing each layer were numerically integrated using the finite difference method and the Southwell-over-relaxation method. A mesh independence test is conducted. Furthermore, a parametric study is performed to analyze how the different nanoparticle volume fractions and viscous heating affect the transport characteristics of engine oil-copper and mineral oil-silver nanofluids. The study also examined the effects of various types of nanoparticles and base fluids. The results demonstrated that heat transport could be efficiently controlled by considering the viscous heating aspect. Moreover, the effects of different nanoparticles on heat transport were found to be more significant than those of base fluids. Finally, a point-wise comparison of our numerical results demonstrates a good agreement with existing studies in the literature. 2023 Author(s).