1,225 results on '"Chattopadhyay, A. K."'
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2. The Impact of Foreign Players in the English Premier League: A Mathematical Analys
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Chattopadhyay, Amit K, Abdul, A., and Jain, Sudhir
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Statistics - Other Statistics ,Condensed Matter - Statistical Mechanics - Abstract
We undertake extensive analysis of English Premier League data over the period 2009/10 to 2017/18 to identify and rank key factors affecting the economic and footballing performances of the teams. Alternative end-of-season league tables are generated by re-ranking the teams based on five different descriptors - total expenditure, total funds spent on players, total funds spent on foreign players, the ratio of foreign to British players and the overall profit. The unequal distribution of resources and expenditure between the clubs is analyzed through Lorenz curves. A comparative analysis of the differences between the alternative tables and the conventional end-of-season league table establishes the most likely factors to influence the performances of the teams that we also rank using Principal Component Analysis. We find that the top teams in the league are also those that tend to have the highest expenditure overall, for all players, including foreign players; they also have the highest ratios of foreign to British players. Our statistical and machine learning study also indicates that successful performance on the field may not guarantee healthy profits at the end of the season., Comment: Graphical Abstract & 8 figures in the main text, 3 Appendices with additional figures and tables
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- 2024
3. Predicting the Progression of Cancerous Tumors in Mice: A Machine and Deep Learning Intuition
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Chattopadhyay, Amit K, Unkundiye, Aimee Pascaline N, Pearce, Gillian, and Russell, Steven
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Physics - Biological Physics ,Condensed Matter - Soft Condensed Matter ,Condensed Matter - Statistical Mechanics - Abstract
The study explores Artificial Intelligence (AI) powered modeling to predict the evolution of cancer tumor cells in mice under different forms of treatment. The AI models are analyzed against varying ambient and systemic parameters, e.g. drug dosage, volume of the cancer cell mass, and time taken to destroy the cancer cell mass. The data required for the analysis have been synthetically extracted from plots available in both published and unpublished literature (primarily using a Matlab architecture called "Grabit"), that are then statistically standardized around the same baseline for comparison. Three forms of treatment are considered - saline (multiple concentrations used), magnetic nanoparticles (mNPs) and fluorodeoxyglycose iron oxide magnetic nanoparticles (mNP-FDGs) - analyzed using three Machine Learning (ML) algorithms, Decision Tree (DT), Random Forest (RF), Multilinear Regression (MLR), and a Deep Learning (DL) module, the Adaptive Neural Network (ANN). The AI models are trained on 60-80% data, the rest used for validation. Assessed over all three forms of treatment, ANN consistently outperforms other predictive models. Our models predict mNP-FDG as the most potent treatment regime that kills the cancerous tumor completely in ca 13 days from the start of treatment. The models can be generalized to other forms of cancer treatment regimens., Comment: 7 figures, 24 pages
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- 2024
4. MHD activity induced coherent mode excitation in the edge plasma region of ADITYA-U Tokamak
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Singh, Kaushlender, Dolui, Suman, Hegde, Bharat, Lachhvani, Lavkesh, Patel, Sharvil, Hoque, Injamul, Kumawat, Ashok K., Kumar, Ankit, Macwan, Tanmay, Raj, Harshita, Banerjee, Soumitra, Yadav, Komal, Kanik, Abha, Gautam, Pramila, Kumar, Rohit, Aich, Suman, Pradhan, Laxmikanta, Patel, Ankit, Galodiya, Kalpesh, Raju, Daniel, Jha, S. K., Jadeja, K. A., Patel, K. M., Pandya, S. N., Chaudhary, M. B., Tanna, R. L., Chattopadhyay, P. K., Pal, R., Saxena, Y. C., Sen, Abhijit, and Ghosh, Joydeep
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Physics - Plasma Physics - Abstract
In this paper, we report the excitation of coherent density and potential fluctuations induced by magnetohydrodynamic (MHD) activity in the edge plasma region of ADITYA-U Tokamak. When the amplitude of the MHD mode, mainly the m/n = 2/1, increases beyond a threshold value of 0.3-0.4 %, coherent oscillations in the density and potential fluctuations are observed having the same frequency as that of the MHD mode. The mode numbers of these MHD induced density and potential fluctuations are obtained by Langmuir probes placed at different radial, poloidal, and toroidal locations in the edge plasma region. Detailed analyses of these Langmuir probe measurements reveal that the coherent mode in edge potential fluctuation has a mode structure of m/n = 2/1 whereas the edge density fluctuation has an m/n = 1/1 structure. It is further observed that beyond the threshold, the coupled power fraction scales almost linearly with the magnitude of magnetic fluctuations. Furthermore, the rise rates of the coupled power fraction for coherent modes in density and potential fluctuations are also found to be dependent on the growth rate of magnetic fluctuations. The disparate mode structures of the excited modes in density and plasma potential fluctuations suggest that the underlying mechanism for their existence is most likely due to the excitation of the global high-frequency branch of zonal flows occurring through the coupling of even harmonics of potential to the odd harmonics of pressure due to 1/R dependence of the toroidal magnetic field.
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- 2024
5. Maximum mass of an anisotropic compact object admitting the modified Chaplygin equation of state in Buchdahl-I metric
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Bhattacharjee, D. and Chattopadhyay, P. K.
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General Relativity and Quantum Cosmology - Abstract
In this article, a new class of exact solutions for anisotropic compact objects is presented. Admitting the modified Chaplygin equation of state $p=H\rho-\frac{K}{\rho^{n}}$, where $H$, $K$ and $n$ are constants with $0
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- 2023
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6. A comparative study on maximum mass and radius of compact star from Heintzmann geometry and TOV approach
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Das, B., Goswami, K. B., and Chattopadhyay, P. K.
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General Relativity and Quantum Cosmology - Abstract
In this article a class of anisotropic compact star is analysed in Heintzmann geometry. We have introduced the pressure anisotropy parameter ($\alpha$) and solved Einstein field equations to obtain stellar model. We have considered $g_{tt}$ component as proposed by Heintzmann and by solving Einstein field equation, the $g_{rr}$ component is evaluated in presence of pressure anisotropy. It is noted that for isotropic star ($\alpha=0$), the maximum mass lies within the range $1.87-3.04~ M_{\odot}$ for radii ranges between $8-13$ Km. For anisotropic compact stars maximum mass increases with $\alpha$ and lies within the range $1.99-3.23~ M_{\odot}$ for anisotropy parameter $\alpha=0.5$. The physical viability of the model is examined by applying our model to study the properties of few known compact objects. It is noted that all the stability conditions are fulfilled in the proposed model. It is interesting to note that maximum mass calculated from our model and from solving TOV equation are approximately same and also the predicted radius of few newly observed pulsars and companion star of GW events GW 190814 and GW 170817 from our model comply with the estimated value of radius from observation., Comment: 27 pages, 21 figures
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- 2023
7. Ambient Temperature Growth and Superconducting Properties of Ti-V Alloy Thin Films
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Pandey, Shekhar Chandra, Sharma, Shilpam, Khandelwal, Ashish, and Chattopadhyay, M. K.
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Condensed Matter - Superconductivity - Abstract
A study on the optimization of ambient temperature growth and superconducting properties of Ti-V alloy thin films grown on SiO2-coated Si substrate is reported here. These films have been synthesized by co-sputtering of Ti and V targets, and films having different Ti concentrations were deposited to get the optimized critical temperature (TC) of thin films close to the bulk value. The maximum TC of 5.2 K has been obtained in the Ti40V60 composition, which is further increased to 6.2 K when a 10 nm thick Ti underlayer is added below the Ti-V film. GIXRD measurements confirm the formation of Ti-V alloys in the desired crystal structure. The upper critical field (HC2) of the thin films has been estimated with the help of magnetotransport measurements. The utility of Ti-V alloy thin films in superconducting radiation detection applications is ascertained., Comment: 4 pages, 6 figures
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- 2023
8. Structural and Magnetic Properties of V-Ti-Si Alloy Superconductors
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Khandelwal, Asi, Chandra, L. S. Sharath, Sagdeo, Archna, Singh, Rashmi, and Chattopadhyay, M. K.
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Condensed Matter - Superconductivity - Abstract
The structural and magnetic properties of the as-cast and annealed V$_{0.6-x}$Si$_x$Ti$_{0.4}$ ($x$ = 0, 0.05, 0.10, 0.15) alloy superconductors are reported here. It is found that addition of silicon to the V-Ti alloys results in eutectic precipitation of Ti$_{5}$Si$_3$-phase in the body centred cubic (bcc) $\beta$-V-Ti matrix. In the as-cast V$_{0.6-x}$Si$_x$Ti$_{0.4}$ alloys, the superconducting transition temperature (T$_{C}$) changes non-monotonically with increasing silicon content whereas after annealing, it is about 7.7 K for all the alloys. On the other hand, the upper critical field decreases and the coherence length increases after annealing in the x = 0.10 alloy. The variations in the superconducting properties in the alloys are related to the solubility of 6 at.% Si in the V$_{0.60}$Ti$_{0.40}$ alloy and the vanadium enrichment in the $\beta$ matrix due to the precipitation of Ti$_{5}$Si$_3$ phase., Comment: 4 pages, 8 figures
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- 2023
9. A new mass limit ($3.61~M_{\odot}$) of strange star admitting CFL equation of state
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Goswami, K. B., Saha, A., Chattopadhyay, P. K., and Karmakar, S.
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General Relativity and Quantum Cosmology - Abstract
A class of strange star is analyzed in the present article in hydrostatic equilibrium whose state is defined by a CFL phase equation of state. We compare our result with those obtained from MIT bag equation of state for strange quark matter which are regarded as free particles. We note that if we consider quarks to form cooper pair and their description is made by CFL equation of state, the maximum mass of strange star assumes value as high as 3.61 $M_{\odot}$ which is well above the value 2.03 $M_{\odot}$ obtained by considering MIT bag equation of state for massless free quarks. Both the maximum masses are determined by solving TOV equation for different values of strange quark mass $m_s$. Thus inclusion of possibility of quark pair formation in the theory permits us to accommodate a wider class of compact objects like 4U 1820-30, PSR J1614-2230, PSR J0030+0451, PSR J1903+0327, PSR J0740+6620, PSR J0952-0607 and mass of the companion star in GW170817 and GW190814 events in our model. The consideration of such high value of mass is hardly obtainable theoretically from normal strange star models in General Relativity even with fast rotation effect. The object PSR J0952-0607 is found to be the fastest and heaviest pulsar in the disk of Milky Way Galaxy having mass 2.59 $M_{\odot}$ may be predicted in our model as observational evidence supports the existence of strange quark matter in its composition., Comment: 12 pages, 20 figures
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- 2023
10. Stable Charged Gravastar model in Cylindrically Symmetric Space-time
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Bhattacharjee, D. and Chattopadhyay, P. K.
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General Relativity and Quantum Cosmology - Abstract
In this paper, we have extended the idea of gravitational Bose-Einstein condensate star (gravastar) to charged gravastar system and explored the role of charge in gravastar formation and its properties. We have used the most general line element in cylindrically symmetric space-time. In this approach the existence of singularity at the center of gravastar is removed and the event horizon is replaced by the thin shell approximation. The proper length of the shell is calculated along with the energy of the thin shell. A mass limit for thin shell has also been evaluated. The entropy calculation shows that the entropy of the configuration is smaller than that of a quasi-black hole system and even smaller than that of a classical black hole. Unlike black hole, the gravastar system is a stable configuration and there is no information paradox., Comment: 12 pages, 4 figures
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- 2023
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11. Maximum mass and radius of strange stars in Finch-Skea geometry in dimensions $D\geq4$
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Das, B., Goswami, K. B., Saha, A., and Chattopadhyay, P. K.
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General Relativity and Quantum Cosmology - Abstract
In this article, we demonstrated a stellar model for compact star in presence of strange matter embedded in $D\ge4$ dimensional space-time defind by Finch-Skea metric. To study the relevant physical properties of the interior matter, we consider the equation of state $(henceforth~EOS)$ as proposed in MIT bag model given by $p=\frac{1}{3}(\rho-4B)$, where $B$ is termed as bag constant. The Mass-Radius relationships in four and higher dimensions are determined using the range of values of surface density through the relation $\rho_{s}=4B$ for which bulk strange matter may be a viable issue for compact objects. Here we choose the range of $B$ such that stable strange matter may exist at zero external pressure relative to neutron. We note that a maximum value of the stellar radius is exist when $B$ is fixed at a given allowed value for which metric functions considered here to be real. This is the maximum allowed radius $(b_{max})$ in this model which depends on surface density of a strange star. In four dimensions the compactness of a star is found to be greater than 0.33. In case of higher dimensions ($D>4$), we observed different values of compactness. Causality conditions are satisfied interior to the star upto maximum allowed radius $(b_{max})$ for which metric function is real. The validity of energy conditions, surface red-shift and other parameters of the stellar configuration are studied and found new results. Stability of the system is also studied., Comment: 36 pages, 31 figures
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- 2023
12. Stable Gravastar model in Cylindrically Symmetric Space-time
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Bhattacharjee, D., Chattopadhyay, P. K., and Paul, B. C.
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General Relativity and Quantum Cosmology - Abstract
We represent a class of new Gravastar solutions as obtained by Mazur and Mottola in a gravitational Bose-Einstein condensate (GBEC) in a cylindrical symmetric space-time. A stable gravastar with three distinct regions namely, (i) Interior de-Sitter space, (ii) Intermediate thin shell with a slice of finite length and (iii) exterior vacuum region. The interior region is characterised by positive energy density and negative pressure $(p=-\rho)$, which exerts a repulsive outward force at all points on the thin shell. The thin shell separating the interior and exterior is supposed to be consisting of ultra-relativistic stiff fluid having equation of state $p=\rho$, which satisfies the Zel'dovich's criteria. This thin shell, which is considered as the critical surface for the quantum phase transition, replaces both the classical de-Sitter and Schwarzschild event horizons. The new solution is free from any singularities as well as any information paradox. The energy density, total energy, proper length, mass and entropy of the shell region are explored in this model and the gravastar model is stable and physically viable., Comment: 14 pages, 8 figures
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- 2023
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13. Behaviour of Ion Acoustic Soliton in a two-electron temperature plasmas of Multi-pole line cusp Plasma Device (MPD)
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Shaikh, Zubin, Patel, A. D., Chattopadhyay, P. K., Ghosh, Joydeep, Joshi, H. H., and Ramasubramanian, N.
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Physics - Plasma Physics - Abstract
This article presents the experimental observations and characterization of Ion Acoustic Soliton (IAS) in a unique Multi-pole line cusp Plasma Device (MPD) device in which the magnitude of the pole-cusp magnetic field can be varied. And by varying the magnitude of the pole-cusp magnetic field, the proportions of two-electron-temperature components in the filament-produced plasmas of MPD can be varied. The solitons are experimentally characterized by measuring their amplitude-width relation and Mach numbers. The nature of the solitons is further established by making two counter-propagating solitons interact with each other. Later, the effect of the two-temperature electron population on soliton amplitude and width is studied by varying the magnitude of the pole cusp-magnetic field. It has been observed that different proportions of two-electron-temperature significantly influence the propagation of IAS. The amplitude of the soliton has been found to be following inversely with the effective electron temperature (Teff), Comment: arXiv admin note: text overlap with arXiv:2208.00279
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- 2023
14. Temperature and terahertz frequency dependence of the dielectric properties of Fe3O4 thin films deposited on Si substrate
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Khandelwal, Ashish, Chandra, L. S. Sharath, Sharma, Shilpam, Sagdeo, Archna, Jayabalan, J., Choudhary, R. J., and Chattopadhyay, M. K.
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Condensed Matter - Materials Science - Abstract
The Fe$_3$O$_4$/Si films are considered to be promising materials for THz spintronic applications due to their high temperature magnetic transition and semiconducting properties. In this article, we present the real part of the dielectric constant ($\epsilon_1$) and the optical conductivity ($\sigma_1$) of Fe$_3$O$_4$ films of different thicknesses deposited on Si substrate (Fe$_3$O$_4$/Si) in the THz range at temperatures 2- 300 K. Although the magnetization of the films with thickness $\geq$ 115 nm shows a clear change at the Verwey transition temperature T$_v$ = 121 K, their optical properties in the THz frequency range are drastically different from each other. We have shown that $\sigma_1$ is maximum and $\epsilon_1$ is minimum when the Fe$^{+2}$/Fe$^{+3}$ ratio is equal to 0.54 which is the ratio of Fe+2/Fe+3 for pure Fe$_3$O$_4$. The $\sigma_1$ reduces and $\epsilon_1$ increases at all temperatures when the Fe$^{+2}$/Fe$^{+3}$ ratio deviates from 0.54. We have shown that a slight change in the Fe$^{+2}$/Fe$^{+3}$ ratio can induce large changes in the optical properties which shall have implications in the application of the Fe3O4 films in THz spintronics., Comment: 18 pages, 6 figures
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- 2022
15. Time Evolution of a Supply Chain Network: Kinetic Modeling
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Debnath, Biswajit, El-Hassani, Rihab, Chattopadhyay, Amit K, Kumar, T Krishna, Ghosh, Sadhan K, and Baidya, Rahul
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Condensed Matter - Statistical Mechanics ,Quantitative Finance - Computational Finance ,Quantitative Finance - Mathematical Finance - Abstract
Resilient supply chains are often inherently dependent on the nature of their complex interconnected networks that are simultaneously multi-dimensional and multi-layered. This article presents a Supply Chain Network (SCN) model that can be used to regulate downstream relationships towards a sustainable SME using a 4-component cost function structure - Environmental (E), Demand (D), Economic (E), and Social (S). As a major generalization to the existing practice of using phenomenological interrelationships between the EDES cost kernels, we propose a complementary time varying model of a cost function, based on Lagrangian mechanics (incorporating SCN constraints through Lagrange multipliers), to analyze the time evolution of the SCN variables to interpret the competition between economic inertia and market potential. Multicriteria decision making, based on an Analytic Hierarchy Process (AHP), ranks performance quality, identifying key business decision makers. The model is first solved numerically and then validated against real data pertaining to two Small and Medium Enterprises (SMEs) from diverse domains, establishing the domain-independent nature of the model. The results quantify how increases in a production line without appropriate consideration of market volatility can lead to bankruptcy, and how high transportation cost together with increased production may lead to a break-even state. The model also predicts the time it takes a policy change to reinvigorate sales, thereby forecasting best practice operational procedure that ensures holistic sustainability on all four sustainability fronts., Comment: 8 figures, 1 table, 2 appendices. arXiv admin note: text overlap with arXiv:2003.00884
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- 2022
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16. Stellar model with non-zero strange quark mass (ms≠0) and Mak–Harko density profile admitting observational results
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Roy, R., Goswami, K. B., Saha, A., Hakim, A., and Chattopadhyay, P. K.
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- 2024
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17. Nonlinear coherent light-matter interaction in 2D MoSe$_2$ nanoflakes for all-optical switching and logic applications
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Kalimuddin, Sk, Das, Biswajit, Chakraborty, Nabamita, Samanta, Madhupriya, Bera, Satyabrata, Bera, Arnab, Roy, Deep Singha, Pradhan, Suman Kalyan, Chattopadhyay, Kalyan K., and Mondal, Mintu
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Physics - Optics ,Condensed Matter - Strongly Correlated Electrons - Abstract
We report a strong nonlinear optical response of 2D MoSe$_2$ nanoflakes (NFs) through spatial self-phase modulation (SSPM) and cross-phase modulation (XPM) induced by nonlocal coherent light-matter interactions. The coherent interaction of light and MoSe$_2$ NFs creates the SSPM of laser beams, forming concentric diffraction rings. The nonlinear refractive index ($n_2$) and the third-order broadband nonlinear optical susceptibility ($\chi^{(3)}$) of MoSe$_2$ NFs are determined from the self diffraction pattern at different exciting wavelengths of 405, 532, and 671 nm with varying the laser intensity. The evolution and deformation of diffraction ring patterns are observed and analyzed by the `wind-chime' model and thermal effect. By taking advantage of the reverse saturated absorption of 2D SnS$_2$ NFs compared to MoSe$_2$, an all-optical diode has been designed with MoSe$_2$/SnS$_2$ hybrid structure to demonstrate the nonreciprocal light propagation. Also a few other optical devices based on MoSe$_2$ and other semiconducting materials such as Bi$_2$Se$_3$, CuPc, and graphene have been investigated. The all-optical logic gates and all-optical information conversion have been demonstrated through the XPM technique using two laser beams. The proposed optical scheme based on MoSe$_2$ NFs has been demonstrated as a potential candidate for all-optical nonlinear photonic devices such as all-optical diodes and all-optical switches., Comment: 20 pages, 6 figures, accepted in advanced optical materials
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- 2022
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18. A model of conflict and leadership: Is there a hawkish drift in politics?
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Bandyopadhyay, Siddhartha, Chattopadhyay, Amit K, and Oak, Mandar
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Physics - Physics and Society - Abstract
We analyze conflict between a citizenry and an insurgent group over a fixed resource such as land. The citizenry has an elected leader who proposes a division such that, the lower the land ceded to the insurgents, the higher the cost of conflict. Leaders differ in ability and ideology such that the higher the leader's ability, the lower the cost of conflict, and the more hawkish the leader, the higher his utility from retaining land. We show that the conflict arises from the political process with re-election motives causing leaders to choose to cede too little land to signal their ability. We also show that when the rents of office are high, the political equilibrium and the second best diverge; in particular, the policy under the political equilibrium is more hawkish compared to the second best. When both ideology and ability are unknown, we provide a plausible condition under which the probability of re-election increases in the leader's hawkishness, thereby providing an explanation for why hawkish politicians may have a natural advantage under the electoral process., Comment: 2 figures, 1 table, accepted in PLOS One
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- 2022
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19. Transmissibility in Interactive Nanocomposite Diffusion: The Nonlinear Double-Diffusion Model
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Chattopadhyay, Amit K, Kundu, Bidisha, Nath, Sujit Kumar, and Aifantis, Elias C
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Physics - Biological Physics ,Mathematics - Dynamical Systems ,Quantitative Biology - Quantitative Methods - Abstract
Model analogies and exchange of ideas between physics or chemistry with biology or epidemiology have often involved inter-sectoral mapping of techniques. Material mechanics has benefitted hugely from such interpolations from mathematical physics where dislocation patterning of platstically deformed metals [1,2,3] and mass transport in nanocomposite materials with high diffusivity paths such as dislocation and grain boundaries, have been traditionally analyzed using the paradigmatic Walgraef-Aifantis (W-A) double-diffusivity (D-D) model [4,5,6,7,8,9]. A long standing challenge in these studies has been the inherent nonlinear correlation between the diffusivity paths, making it extremely difficult to analyze their interdependence. Here, we present a novel method of approximating a closed form solution of the ensemble averaged density profiles and correlation statistics of coupled dynamical systems, drawing from a technique used in mathematical biology to calculate a quantity called the {\it basic reproduction number} $R_0$, which is the average number of secondary infections generated from every infected. We show that the $R_0$ formulation can be used to calculate the correlation between diffusivity paths, agreeing closely with the exact numerical solution of the D-D model. The method can be generically implemented to analyze other reaction-diffusion models., Comment: 5 two-pannelled figures, 13 pages
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- 2022
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20. Enhancement of functional properties of V$_{0.6}$Ti$_{0.4}$ alloy superconductor by the addition of yttrium
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Ramjan, SK., Chandra, L. S. Sharath, Singh, Rashmi, Ganesh, P., Sagdeo, Archna, and Chattopadhyay, M. K.
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Condensed Matter - Superconductivity ,Condensed Matter - Materials Science - Abstract
We show here that the yttrium is immiscible and precipitates with various sizes in the body centred cubic V$_{0.6}$Ti$_{0.4}$ alloy superconductor. The number and size of the precipitates are found to depend on the amount of yttrium added. Precipitates with various sizes up to 30~$\mu$m are found in the V$_{0.6}$Ti$_{0.4}$ alloy containing 5 at.\% yttrium. The large amount of line disorders generated by the addition of yttrium in this alloy are found to be effective in pinning the magnetic flux lines. While the superconducting transition temperature increases with the increasing amount of yttrium in the V$_{0.6}$Ti$_{0.4}$ alloy, the critical current density is maximum for the alloy containing 2 at. \% yttrium, where it is more than 7.5 times the parent alloy in fields higher than 1~T. We found that the effectiveness of each type of defect in pinning the flux lines is dependent on the temperature and the applied magnetic filed., Comment: 10 pages, 14 figures, 3 tables
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- 2021
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21. Temperature induced first order electronic topological transition in $\beta$-Ag$_2$Se
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Chandra, L. S. Sharath, Ramjan, SK., Banik, Soma, Sagdeo, Archna, and Chattopadhyay, M. K.
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Condensed Matter - Materials Science - Abstract
$\beta$-Ag$_2$Se is a promising material for room temperature thermoelectric applications and magneto-resistive sensors. However, no attention was paid earlier to the hysteresis in the temperature dependence of resistivity ($\rho$($T$)). Here, we show that a broad hysteresis above 35 K is observed not only in $\rho$($T$), but also in other electronic properties such as Hall coefficient ($R_H$($T$)), Seebeck coefficient, thermal conductivity and ultraviolet photoelectron spectra (UPS). We also show that the hysteresis is not associated with a structural transition. The $\rho$($T$) and $R_H$($T$) show that $\beta$-Ag$_2$Se is semiconducting above 300 K, but metallicity is retained below 300 K. While electronic states are absent in the energy range from the Fermi level ($E_F$) to 0.4 eV below the $E_F$ at 300 K, a distinct Fermi edge is observed in the UPS at 15 K suggesting that the $\beta$-Ag$_2$Se undergoes an electronic topological transition from a high temperature semiconducting state to a low temperature metallic state. Our study reveals that a constant and moderately high thermoelectric figure of merit ($ZT$) in the range 300-395 K is observed due to the broad semiconductor to metal transition in $\beta$-Ag$_2$Se., Comment: 6 pages, 4 figures, 1 table
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- 2021
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22. terraFlow, a high-parameter analysis tool, reveals T cell exhaustion and dysfunctional cytokine production in classical Hodgkin’s lymphoma
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Freeman, Daniel, Diefenbach, Catherine, Lam, Linda, Le, Tri, Alexandre, Jason, Raphael, Bruce, Grossbard, Michael, Kaminetzky, David, Ruan, Jia, and Chattopadhyay, Pratip K.
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- 2024
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23. Low frequency dust acoustic drift instability in the equatorial electrojet
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Sarkar, Sanjib, Atul, Jyoti K., Laishram, Modhuchandra, Saha, Anirban, and Chattopadhyay, Prabal K.
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- 2024
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24. Maximum mass of an anisotropic compact object admitting the modified Chaplygin equation of state in Buchdahl-I metric
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Bhattacharjee, D. and Chattopadhyay, P. K.
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- 2024
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25. VIRDOCD: a VIRtual DOCtor to Predict Dengue Fatality
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Chattopadhyay, Amit K and Chattopadhyay, Subhagata
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Quantitative Biology - Quantitative Methods ,Computer Science - Machine Learning ,Physics - Biological Physics - Abstract
Clinicians make routine diagnosis by scrutinizing patients' medical signs and symptoms, a skill popularly referred to as "Clinical Eye". This skill evolves through trial-and-error and improves with time. The success of the therapeutic regime relies largely on the accuracy of interpretation of such sign-symptoms, analyzing which a clinician assesses the severity of the illness. The present study is an attempt to propose a complementary medical front by mathematically modeling the "Clinical Eye" of a VIRtual DOCtor, using Statistical and Machine Intelligence tools (SMI), to analyze Dengue epidemic infected patients (100 case studies with 11 weighted sign-symptoms). The SMI in VIRDOCD reads medical data and translates these into a vector comprising Multiple Linear Regression (MLR) coefficients to predict infection severity grades of dengue patients that clone the clinician's experience-based assessment. Risk managed through ANOVA, the dengue severity grade prediction accuracy from VIRDOCD is found higher (ca 75%) than conventional clinical practice (ca 71.4%, mean accuracy profile assessed by a team of 10 senior consultants). Free of human errors and capable of deciphering even minute differences from almost identical symptoms (to the Clinical Eye), VIRDOCD is uniquely individualized in its decision-making ability. The algorithm has been validated against Random Forest classification (RF, ca 63%), another regression-based classifier similar to MLR that can be trained through supervised learning. We find that MLR-based VIRDOCD is superior to RF in predicting the grade of Dengue morbidity. VIRDOCD can be further extended to analyze other epidemic infections, such as COVID-19., Comment: 17 pages, 5 figures, 8 tables
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- 2021
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26. Interesting magnetic response of the nuclear fuel material UO2
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Pal, Sudip, Chandra, L. S. Sharath, Chattopadhyay, M. K., and Roy, S. B.
- Subjects
Condensed Matter - Strongly Correlated Electrons ,Condensed Matter - Materials Science - Abstract
Magnetic response of uranium dioxide (UO2) has been investigated through temperature and magnetic field dependent dc magnetization measurements. UO2 is a paramagnet at room temperature. The magnetic susceptibility, however, deviates from Curie-Weiss (CW) like paramagnetic behavior below T = 280 K. Further down the temperature UO2 undergoes phase transition to an antiferromagnetic state below TN = 30.6 K. The zero field cooled (ZFC) and field cooled (FC) magnetizations exhibit some distinct thermomagnetic irreversibility below TN. The temperature dependence of the FC magnetization is more like a ferromagnet, whereas ZFC magnetization exhibits distinct structures not usually observed in the antiferromagnets. In low applied magnetic field this thermomagnetic irreversibility in magnetization exists in a subtle way even in the paramagnetic regime above TN up to a fairly high temperature, but vanishes in high applied magnetic fields. Deviation from CW law and irreversibility between ZFC and FC magnetization indicate that the paramagnetic state above TN is not a trivial one. Magnetic response below TN changes significantly with the increase in the applied magnetic field. Thermomagnetic irreversibility in magnetization initially increases with the increase in the strength of applied magnetic field, but then gets reduced in the high applied fields. A subtle signature of a magnetic field induced phase transition is also observed in the isothermal magnetic field vartaion of magnetization. All these experimetal results highlight the non-trivial nature of the antiferromagnetic state in UO2, Comment: 11 pages and 4 figures
- Published
- 2021
27. Coexisting superconductivity and ferromagnetism in the (V$_{0.60}$Ti$_{0.40}$)-Gd alloys
- Author
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Paul, Sabyasachi, Ramjan, SK., Chandra, L. S. Sharath, and Chattopadhyay, M. K.
- Subjects
Condensed Matter - Superconductivity ,Condensed Matter - Materials Science - Abstract
We present here, the effect of microstructure on the magnetic, electrical and thermal properties of (V$_{0.60}$Ti$_{0.40}$)-Gd alloys. The gadolinium is found to be immiscible and precipitates with a size $<$1.2~$\mu$m in the (V$_{0.60}$Ti$_{0.40}$)-Gd alloys. These precipitates enhance the grain boundary density. The (V$_{0.60}$Ti$_{0.40}$)-Gd alloys become ferromagnetic below $T_{mc}$ = 295~K with an increase in the superconducting transition temperature ($T_{sc}$). Though the disorder increases with increasing Gd content, the electronic thermal conductivity ($\kappa_{e} (H = 0)$) reduces by at most 15\% which is in contrast with the 80\% decrease of the phononic thermal conductivity ($\kappa_{l} (H = 0)$). Our analysis suggests that the magnetic moments of Gd precipitates polarize the conduction electrons along and around the grain boundaries leading to increase in the mean free path of the electrons. The partial suppression of spin fluctuations in the (V$_{0.60}$Ti$_{0.40}$)-Gd alloy by the conduction electron polarization enhances the $T_{sc}$., Comment: 11 pages, 11 figures, 2 tables
- Published
- 2021
28. Understanding the working of a B-dot probe
- Author
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Bose, Sayak, Kaur, Manjit, Barada, Kshitish K, Ghosh, Joydeep, Chattopadhyay, Prabal K, and Pal, Rabindranath
- Subjects
Physics - Applied Physics ,Physics - Physics Education ,Physics - Instrumentation and Detectors ,Physics - Plasma Physics - Abstract
Magnetic pickup loops or B-dot probes are one of the oldest known sensors of time-varying magnetic fields. The operating principle is based on Faraday's law of electromagnetic induction. However, obtaining accurate measurements of time-varying magnetic fields using these kinds of probes is a challenging task. A B-dot probe and its associated circuit are prone to electrical oscillations. As a result, the measured signal may not faithfully represent the magnetic field sampled by the B-dot probe. In this paper, we have studied the transient response of a B-dot probe and its associated circuit to a time-varying magnetic field. Methods of removing the oscillations pertaining to the detector structure are described. After removing the source of the oscillatory signal, we have shown that the time-integrated induced emf measured by the digitiser is linearly proportional to the magnetic field sampled by the B-dot probe, thus verifying the faithfulness of the measured signal.
- Published
- 2020
- Full Text
- View/download PDF
29. Infection Kinetics of Covid-19: Is Lockdown a Potent Containment Tool?
- Author
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Chattopadhyay, Amit k, Choudhury, Debajyot, Ghosh, Goutam, Kundu, Bidisha, and Nath, Sujit Kumar
- Subjects
Quantitative Biology - Quantitative Methods ,Physics - Physics and Society ,Quantitative Biology - Populations and Evolution - Abstract
Covid-19 is raging a devastating trail with the highest mortality-to-infected ratio ever for a pandemic. Lack of vaccine and therapeutic has rendered social exclusion through lockdown as the singular mode of containment. Harnessing the predictive powers of Machine Learning within a 6 dimensional infection kinetic model, depicting interactive evolution of 6 infection stages - healthy susceptible ($H$), predisposed comorbid susceptible ($P$), infected ($I$), recovered ($R$), herd immunized ($V$) and mortality ($D$) - the model, PHIRVD, provides the first accurate mortality prediction of 18 countries at varying stages of strategic lockdown, up to 30 days beyond last data training. PHIRVD establishes mortality-to-infection ratio as the correct pandemic descriptor, substituting reproduction number, and highlights the importance of early and prolonged but strategic lockdown to contain secondary relapse. Significance Statement: 1. Accurate prediction of the day-by-day mortality profiles of 18 countries, 30 days beyond the last data of data training. 2. Precise quantification of the impact of early-vs-later lockdown impositions. 3. Accurate prediction of secondary relapse timelines/ 4. Establishment of mortality-to-infected ratio as the correct pandemic descriptor substituting the popular choice of reproduction number, a proven failure in predicting future infection kinetics and secondary surge. The outcomes have potential to redefine healthy policy landscape, particularly in light of secondary relapse and possible future SARS-COV/Ebola group incursion., Comment: 13 pages main text (8figures, 2 tables), 20 pages of appendices (21 figures, 5 tables)
- Published
- 2020
30. Studies on DC transport and terahertz conductivity of granular molybdenum thin films for microwave radiation detector applications
- Author
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Sharma, Shilpam, Khandelwal, Ashish, Amaladass, E. P., Abhirami, S., Ramjan, SK., Jayabalan, J., Mani, Awadhesh, and Chattopadhyay, M. K.
- Subjects
Condensed Matter - Superconductivity - Abstract
The morphological, transport and terahertz optical properties of DC magnetron sputtered granular molybdenum thin-films with nano-grains embedded in an amorphous matrix have been studied in the normal and superconducting states. The superconducting transition temperatures of these films are much higher than that of bulk molybdenum. The optical properties of these thin-films have been studied using terahertz time-domain spectroscopy. Their properties have been compared with the existing materials used for the development of radiation detectors. The resistivity of the films lies in >100 micro-Ohm-cm range which is ideal for making highly sensitive radiation detectors. The Hall measurements indicate the presence of holes as the dominant carriers with very small mean free path and mobility. In the normal state, the films are disordered bad metal but they have large superfluid density and stiffness in their superconducting state. The normal state and superconducting properties of the films are very promising for their use in cryogenic radiation detectors for microwave, terahertz, and far IR frequency ranges., Comment: 27 pages, 9 figures
- Published
- 2020
- Full Text
- View/download PDF
31. Localization of electronic states resulting from electronic topological transitions in the Mo$_{1-x}$Re$_x$ alloys: A photoemission study
- Author
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Chandra, L. S. Sharath, Sundar, Shyam, Banik, Soma, Ramjan, SK., Chattopadhyay, M. K., Jha, S. N., and Roy, S. B.
- Subjects
Condensed Matter - Superconductivity ,Condensed Matter - Materials Science - Abstract
We present the results of resonant photoemission spectroscopy experiments on the Mo$_{1-x}$Re$_{x}$ alloy compositions spanning over two electronic topological transitions (ETT) at the critical concentrations $x_{C1}$ = 0.05 and $x_{C2}$ = 0.11. The photoelectrons show an additional resonance ($R3$) in the constant initial state (CIS) spectra of the alloys along with two resonances ($R1$ and $R2$) which are similar to those observed in molybdenum. All the resonances show Fano-like line shapes. The asymmetry parameter $q$ of the resonances $R1$ and $R3$ of the alloys is observed to be large and negative. Our analysis suggests that the origin of large negative q is associated with phonon assisted inter band scattering between the Mo-like states and the narrow band that appeared due to the ETT., Comment: 14 pages, 3 figures, 1 table
- Published
- 2020
- Full Text
- View/download PDF
32. Stochastic Stabilization of Transient Axisymmetric Taylor-Couette Flow
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Godwin, Larry E., Generalis, Sotos C., and Chattopadhyay, Amit K.
- Subjects
Physics - Fluid Dynamics ,Mathematics - Dynamical Systems - Abstract
Structured on the paradigmatic Navier-Stokes flow model, we study a stochastically forced Taylor-Couette system in the narrow gap limit, in order to analyze the simultaneous impact of a non-conserved (Gaussian) force and a nonlinear perturbation, in determining linear stability. Our analysis identifies key parametric windows within which the model remarkably retains its linear stability, even against jointly varying stochastic forcing and nonlinear fluctuations. We identify this feature as a {\it latent universality}, that we then utilize to answer the elusive question as to how a recent groundbreaking accretion flow model retains its stability, even in presence of nonlinear perturbations and non-conserved stochastic forcing. Our analytical outline goes beyond the immediate model studied and lays a generic foundation of analyzing stability for nonlinear sheared models acted on by external forces and subjected to boundary layer instability. presence of nonlinear perturbations and non-conserved stochastic forcing. Our analytical outline goes beyond the immediate model studied and lays a generic foundation of analyzing stability for nonlinear sheared models acted on by external forces and subjected to boundary layer instability., Comment: 24 pages, 33 figures
- Published
- 2020
33. CHD Risk Minimization through Lifestyle Control: Machine Learning Gateway
- Author
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He, Xi, Matam, B Rajeswari, Bellary, Srikanth, Ghosh, Goutam, and Chattopadhyay, Amit K
- Subjects
Physics - Medical Physics ,Physics - Biological Physics ,Quantitative Biology - Populations and Evolution - Abstract
Studies on the influence of a modern lifestyle in abetting Coronary Heart Diseases (CHD) have mostly focused on deterrent health factors, like smoking, alcohol intake, cheese consumption and average systolic blood pressure, largely disregarding the impact of a healthy lifestyle in mitigating CHD risk. In this study, 30+ years' World Health Organization (WHO) data have been analyzed, using a wide array of advanced Machine Learning techniques, to quantify how regulated reliance on positive health indicators, e.g. fruits/vegetables, cereals can offset CHD risk factors over a period of time. Our research ranks the impact of the negative outliers on CHD and then quantifies the impact of the positive health factors in mitigating the negative risk-factors. Our research outcomes, presented through simple mathematical equations, outline the best CHD prevention strategy using lifestyle control only. We show that a 20% increase in the intake of fruit/vegetable leads to 3-6% decrease in SBP; or, a 10% increase in cereal intake lowers SBP by 3%; a simultaneous increase of 10% in fruit-vegetable can further offset the effects of SBP by 6%. Our analysis establishes gender independence of lifestyle on CHD, refuting long held assumptions and unqualified beliefs. We show that CHD risk can be lowered with incremental changes in lifestyle and diet, e.g. fruit-vegetable intake ameliorating effects of alcohol-smoking-fatty food. Our multivariate data model also estimates functional relationships amongst lifestyle factors that can potentially redefine the diagnostics of Framingham score-based CHD-prediction., Comment: 10 pages, 7 tables, 2 figures together with a detailed online supplementary section including another 9 tables and 4 figures
- Published
- 2020
34. Cleaner Production in Optimized Multivariate Networks: Operations Management through a Roll of Dice
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Chattopadhyay, Amit K, Debnath, Biswajit, El-Hassani, Rihab, Ghosh, Sadhan Kumar, and Baidya, Rahul
- Subjects
Quantitative Finance - General Finance ,Quantitative Finance - Computational Finance ,Quantitative Finance - Portfolio Management - Abstract
The importance of supply chain management in analyzing and later catalyzing economic expectations while simultaneously prioritizing cleaner production aspects is a vital component of modern finance. Such predictions, though, are often known to be less than accurate due to the ubiquitous uncertainty plaguing most business decisions. Starting from a multi-dimensional cost function defining the sustainability of the supply chain (SC) kernel, this article outlines a 4-component SC module - environmental, demand, economic, and social uncertainties - each ranked according to its individual weight. Our mathematical model then assesses the viability of a sustainable business by first ranking the potentially stochastic variables in order of their subjective importance, and then optimizing the cost kernel, defined from a utility function. The model will then identify conditions (as equations) validating the sustainability of a business venture. The ranking is initially obtained from an Analytical Hierarchical Process; the resultant weighted cost function is then optimized to analyze the impact of market uncertainty based on our supply chain model. Model predictions are then ratified against SME data to emphasize the importance of cleaner production in business strategies., Comment: 18 pages, 9 figures; 3 additional appendices (14 pages)
- Published
- 2020
35. Unprecedented confinement time of electron plasmas with a purely toroidal magnetic field in SMARTEX-C
- Author
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Lachhvani, Lavkesh, Pahari, Sambaran, Goswami, Rajiv, Yeole, Yogesh G., and Chattopadhyay, Prabal K.
- Subjects
Physics - Plasma Physics - Abstract
Confinement time of electron plasmas trapped using a purely toroidal magnetic field has been extended to $\sim 100$ s in a small aspect ratio ($R_{o}/{a} \sim {1.59}$, $R_o$ and $a$ are device major and minor radius, respectively), partial torus. It surpasses the previous record by nearly two orders of magnitude. Lifetime is estimated from the frequency scaling of the linear diocotron mode launched from sections of the wall, that are also used for mode diagnostics. Confinement improves enormously with reduction in neutral pressure in the presence of a steady state magnetic field. In addition, confinement is seen to be independent of the magnetic field, a distinguishing feature of Magnetic Pumping Transport (MPT) theory. Since MPT predicts an upper limit to confinement comparisons have been made between our experiments and MPT estimates.
- Published
- 2020
36. Unprecedented confinement time of electron plasmas with a purely toroidal magnetic field in SMARTEX-C
- Author
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Lachhvani, Lavkesh, Pahari, Sambaran, Goswami, Rajiv, Yeole, Yogesh G., Shah, Minsha, Mohurle, Nikhil, and Chattopadhyay, Prabal K.
- Published
- 2023
- Full Text
- View/download PDF
37. New mass limit of a strange star admitting a colour flavor locked equation of state
- Author
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Goswami, K. B., Saha, A., Chattopadhyay, P. K., and Karmakar, S.
- Published
- 2023
- Full Text
- View/download PDF
38. Structural stability of mechanically alloyed amorphous (FeCoNi)70Ti10B20 under high-temperature and high-pressure
- Author
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Avar, Baris, Simsek, Tuncay, Ozcan, Sadan, Chattopadhyay, Arun K, and Kalkan, Bora
- Subjects
Engineering ,Materials Engineering ,Mechanical alloying ,Amorphous ,High-pressure ,Alloy ,Soft magnetic behavior ,Condensed Matter Physics ,Resources Engineering and Extractive Metallurgy ,Materials ,Materials engineering ,Condensed matter physics - Abstract
Nanostructured (FeCoNi)70Ti10B20 (at%) alloy was synthesized by mechanical alloying from elemental powder mixture of Fe, Co, Ni, Ti and B using ball milling. The effect of ball milling time on the evolution of structure and morphology was investigated by X-ray diffraction, scanning and transmission electron microscopy and differential thermal analysis. It was observed that the formation of solid solution of (FeCoNi)70Ti10B20 started from the very onset of the milling process. Crystallite size and lattice strains seemed to be leveled off after 20 h of milling with no further major changes. The milling process for longer periods introduced severe plastic deformations causing formation of amorphous phase of (FeCoNi)70Ti10B20. The amorphous alloy composition was confirmed by energy dispersive X-ray spectroscopy analysis that showed an excellent homogeneity of the alloying elements. The phase stability of the mechanically alloyed amorphous sample was further verified by employing high-temperature and high-pressure studies. The alloy samples heat-treated at 700 °C revealed crystallization of the amorphous phase. However, synchrotron-based high-pressure ambient temperature X-ray diffraction studies confirmed that the amorphous phase of the alloy remained stable up to the pressure of 30 GPa. The 50 h milled sample after being annealed at 350 °C showed improvement in the soft magnetic properties of the alloy, which was due to the probable elimination of the residual stress in the amorphous phase of the alloy powders.
- Published
- 2021
39. Grain refinement and enhancement of critical current density in the V_0.60Ti_0.40 alloy superconductors with Gd addition
- Author
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Paul, Sabyasachi, Ramjan, SK, Venkatesh, R, Chandra, L S Sharath, and Chattopadhyay, M K
- Subjects
Condensed Matter - Superconductivity - Abstract
The V-Ti alloys are promising materials as alternate to the commercial Nb-based superconductors for high current-high magnetic field applications. However, the critical current density (J_c) of these alloys are somewhat low due to their low grain-boundary density. We show here that grain refinement of the V-Ti alloys and enhancement of the J_c can be achieved by the addition of Gd into the system, which precipitates as clusters along the grain boundaries. Both the J_c and the pinning force density (F_P) increase with the increasing Gd content up to 1 at. % Gd, where they are more than 20 times higher than those of the parent V_0.60Ti_0.40 alloy. Introduction of Gd into the system also leads to ferromagnetic (FM) correlations, and the alloys containing more than 0.5 at. % Gd exhibit spontaneous magnetization. In spite of the FM correlations, the superconducting transition temperature increases slightly with Gd-addition.
- Published
- 2019
40. Two channel heat conduction in the superconducting state of the as-cast V$_{1-x}$Zr$_x$ alloys
- Author
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Paul, Sabyasachi, Chandra, L. S. Sharath, and Chattopadhyay, M. K.
- Subjects
Condensed Matter - Superconductivity - Abstract
We present here the temperature dependence of heat capacity ($C$($T$)) and thermal conductivity ($\kappa$($T$)) in the superconducting state as well as in the normal state of as-cast V$_{1-x}$Zr$_x$ alloys. Distinct jumps in the $C$($T$) of the alloys indicate the presence of three superconducting phases with transition temperatures $T_{C1}$ = 5.4~K, $T_{C2}$ = 8.2~K and $T_{C3}$ = 8.5~K. From the metallography micrographs, these three phases are identified to be $\beta$-V, $\gamma$-ZrV$_2$, and $\gamma'$-ZrV$_2$ respectively. Apart from these phases, $\alpha$-Zr and $\beta$-Zr phases are also detected in these samples. The experimental $\kappa$($T$) in the superconducting state of these alloys is observed to be significantly higher than that expected theoretically. Our analysis suggests that the above observation is due to the coexistence of multiple superconducting and non superconducting phases which resulted in the two-parallel channels for the conduction of heat., Comment: 11 pages, 4 figures
- Published
- 2019
- Full Text
- View/download PDF
41. Superconductivity in V$_{1-x}$Zr$_x$ alloys]{Evolution of high field superconductivity and high critical current density in the as-cast V$_{1-x}$Zr$_x$ alloys
- Author
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Chandra, L. S. Sharath, Paul, Sabyasachi, Khandelwal, Ashish, Sagdeo, Archna, Venkatesh, R., Kumar, Kranti, Banerjee, A., and Chattopadhyay, M. K.
- Subjects
Condensed Matter - Superconductivity - Abstract
We report here the structural, electrical and magnetic properties of as-cast V$_{1-x}$Zr$_x$ alloys ($x$ =0 - 0.4) at low temperatures. We observe that all the alloys undergo successive peritectic and eutectic reactions during cooling from the melt which leads to the formation of five phases, namely, a body centred cubic $\beta$-V phase, two phases with slightly different compositions having face centred cubic ZrV$_2$ structure, a hexagonal closed packed $\alpha$-Zr phase, and the $\beta$-Zr precipitates. The amount of each phase is found to be dependent on the concentration of zirconium in vanadium. The $\beta$-V and ZrV$_2$ phases show superconductivity below 5.3~K and 8.5~K respectively. We show that the critical current density is large for V-rich V$_{1-x}$Zr$_x$ alloys with $x >$ 0.1. The grain boundaries generated from the eutectic reaction, and the point defects formed due to the variation in the composition are found to be responsible for the pinning of flux lines in low and high magnetic fields respectively. Our studies reveal that the choice of the composition and the heat treatment which leads to eutectic reaction are important in improving the critical current density in this alloy system., Comment: 8 pages, 7 figures
- Published
- 2019
42. Effect of Inhomogeneous magnetic field on Plasma generation in a low magnetic field helicon discharge
- Author
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Yadav, Sonu, Chattopadhyay, Prabal K, Barada, Kshitish K., Ghosh, Soumen, and Ghosh, Joydeep
- Subjects
Physics - Plasma Physics - Abstract
The ionization efficiency of helicon plasma discharge is explored by changing the low axial magnetic field gradients near the helicon antenna. The highest plasma density is found for a most possible diverging field near the antenna by keeping the other operating condition constant. Measurement of axial wave number together with estimated radial wavenumber suggests the oblique mode propagation of helicon wave along the resonance cone boundary. Propagation of helicon wave near the resonance cone angle boundary can excite electrostatic fluctuations which subsequently can deposit energy in the plasma. This process has been shown to be responsible for peaking in density in low field helicon discharges, where the helicon wave propagates at an angle with respect to the applied uniform magnetic field. The increased efficiency can be explained on the basis of multiple resonances for multimode excitation by the helicon antenna due to the availability of a broad range of magnetic field values in the near field of the antenna when a diverging magnetic field is applied in the source.
- Published
- 2019
- Full Text
- View/download PDF
43. Validity of IL-6 and Arthrocentesis in the Cause and Management of Internal Derangement of TMJ
- Author
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Balasundaram, T., Roy Chowdhury, S. K., Chattopadhyay, P. K., Desai, Ajay P., Kamalpathey, K., and Menon, Rahul P.
- Published
- 2022
- Full Text
- View/download PDF
44. Hormesis: A Fundamental Concept in Biology
- Author
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Chattopadhyay, M. K.
- Published
- 2022
- Full Text
- View/download PDF
45. Cache controlled cluster networking protocol
- Author
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Sunhare, Priyank and Chattopadhyay, Manju K.
- Published
- 2023
- Full Text
- View/download PDF
46. Radiation Analysis and Design Study of Unified Cooling and Baking Scheme for SMARTEX-C
- Author
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Srivastava, Ritesh Kumar, Gupta, Manoj Kumar, Lachhvani, Lavkesh T., Bajpai, Manu, Yeole, Yogesh, Doshi, Bharat R., and Chattopadhyay, Prabal K.
- Published
- 2023
- Full Text
- View/download PDF
47. Influence of indium and selenium co-doping on structural and thermoelectric properties of Bi2Te3 alloys
- Author
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Hegde, Ganesh Shridhar, Prabhu, A. N., and Chattopadhyay, M. K.
- Published
- 2023
- Full Text
- View/download PDF
48. Bisphosphonate Osteonecrosis in a Case of Langerhans Cell Histiocytosis: Report of a Case and Review of Literature
- Author
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Rajkumar, K., Viswambaran, M., Sen, Arijit, and Chattopadhyay, P. K.
- Published
- 2022
- Full Text
- View/download PDF
49. Thermal conductivity of strong coupling V$_{1-x}$Ti$_x$ superconductors in the Mott-Ioffe-Regel limit
- Author
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Paul, Sabyasachi, Chandra, L. S. Sharath, and Chattopadhyay, M. K.
- Subjects
Condensed Matter - Superconductivity - Abstract
We report an enhancement of thermal conductivity ($\kappa$) below the superconducting transition temperature ($T_C$) in the high carrier density $\beta$-V$_{1-x}$Ti$_x$ alloys. We find that the point defects generated when Ti is added to V reduce the electron mean free path down to the inter-atomic distances and make the high frequency phonons ineffective in carrying heat. In this Mott-Ioffe-Regel limit, the phonon thermal conductivity is dominated by the low frequency phonons limited by the scattering due to the electrons. The formation of Cooper pairs below the $T_C$ re-normalizes the phonon mean free path and enhances the $\kappa$., Comment: 11 pages, 3 figures
- Published
- 2018
- Full Text
- View/download PDF
50. Epidemiological impact of waning immunization on a vaccinated population
- Author
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Grela, Ewa, Stich, Michael, and Chattopadhyay, Amit K
- Subjects
Quantitative Biology - Populations and Evolution - Abstract
This is an epidemiological SIRV model based study that is designed to analyze the impact of vaccination in containing infection spread, in a 4-tiered population compartment comprised of susceptible, infected, recovered and vaccinated agents. While many models assume a lifelong protection through vaccination, we focus on the impact of waning immunization due to conversion of vaccinated and recovered agents back to susceptible ones. Two asymptotic states exist, the "disease-free equilibrium" and the "endemic equilibrium"; we express the transitions between these states as function of the vaccination and conversion rates using the basic reproduction number as a descriptor. We find that the vaccination of newborns and adults have different consequences in controlling epidemics. We also find that a decaying disease protection within the recovered sub-population is not sufficient to trigger an epidemic at the linear level. Our simulations focus on parameter sets that could model a disease with waning immunization like pertussis. For a diffusively coupled population, a transition to the endemic state can be initiated via the propagation of a traveling infection wave, described successfully within a Fisher-Kolmogorov framework., Comment: Published version In EPJB has 11 pages (2-columned), 1 Table, 10 figures
- Published
- 2018
- Full Text
- View/download PDF
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