3,017 research outputs found

    Sowing Organic Seeds

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    There is a growing realisation that only the adoption of ecological and sustainable farming practices can reverse the declining trend in farm productivity in the state of West Bengal, India. The paper is on how a small holding (3.8 acres) family farm in a remote dry land area in India demonstrates what can be achieved by way of love for land and nature, self-determination, innovation and hard work. The educated farm family has neatly woven traditional knowledge and modern improvements in agricultural science for developing their organic farm and sustenance of nature. The income from the farm meets their domestic and social needs. Their child goes to one of best private English medium school. There have been noticeable positive changes among the neighbouring farmers, soil and ecology

    Orbit Portraits of Unicritical Anti-polynomials

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    Orbit portraits were introduced by Milnor as a combinatorial tool to describe the patterns of all periodic dynamical rays landing on a periodic cycle of a quadratic polynomial. This encodes information about the dynamics and the parameter spaces of these maps. We carry out a similar analysis for unicritical anti-polynomials and give an explicit description of the orbit portraits that can occur for such maps in terms of their characteristic angles, which turns out to be rather restricted when compared with the holomorphic case. Finally, we prove a realization theorem for these combinatorial objects. The results obtained in this paper serve as a combinatorial foundation for a detailed understanding of the combinatorics and topology of the parameter spaces of unicritical anti-polynomials and their connectedness loci, known as the multicorns

    A real-time thermal field theoretical analysis of Kubo-type shear viscosity : Numerical understanding with simple examples

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    A real-time thermal field theoretical calculation of shear viscosity has been described in the Kubo formalism for bosonic and fermionic medium. The two point function of viscous stress tensor in the lowest order provides one-loop skeleton diagram of boson or fermion field for bosonic or fermionic matter. According to the traditional diagrammatic technique of transport coefficients, the finite thermal width of boson or fermion is introduced in their internal lines during the evaluation of boson-boson or fermion-fermion loop diagram. These thermal widths of ϕ\phi boson and ψ\psi fermion are respectively obtained from the imaginary part of self-energy for ϕΦ\phi\Phi and ψΦ\psi\Phi loops, where interactions of higher mass Φ\Phi boson with ϕ\phi and ψ\psi are governed by the simple ϕϕΦ\phi\phi\Phi and {\ov\psi}\psi\Phi interaction Lagrangian densities. A two-loop diagram, having same power of coupling constant as in the one-loop diagram, is deduced and its contribution appears much lower than the one-loop values of shear viscosity. Therefore the one-loop results of Kubo-type shear viscosity may be considered as leading order results for this simple ϕϕΦ\phi\phi\Phi and {\ov\psi}\psi\Phi interactions. This approximation is valid for any values of coupling constant and at the temperatures greater than the mass of constituent particles of the medium

    A comparative analysis of in-medium spectral functions for N(940)N(940) and N(1535)N^*(1535) in real-time thermal field theory

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    In the real-time thermal field theory, the nucleon self-energy at finite temperature and density is evaluated where an extensive set of pion-baryon (πB\pi B) loops are considered. On the other side the in-medium self-energy of N(1535)N^*(1535) for πN\pi N and ηN\eta N loops is also determined in the same framework. The detail branch cut structures for these different πB\pi B loops for nucleon N(940)N(940) and πN\pi N, ηN\eta N loops for N(1535)N^*(1535) are addressed. Using the total self-energy of N(940)N(940) and N(1535)N^*(1535), which contain the contributions of their corresponding loop diagrams, the complete structures of their in-medium spectral functions have been obtained. The Landau and unitary cut contributions provide two separate peak structures in the nucleon spectral function while N(1535)N^*(1535) has single peak structure in its unitary cuts. At high temperature, the peak structures of both at their individual poles are attenuated while at high density Landau peak structure of nucleon is completely suppressed and its unitary peak structure is tending to be shifted towards the melted peak of N(1535)N^*(1535). The non-trivial modifications of these chiral partners may indicate some association of chiral symmetry restoration

    The nucleon thermal width due to pion-baryon loops and its contribution in Shear viscosity

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    In the real-time thermal field theory, the standard expression of shear viscosity for the nucleonic constituents is derived from the two point function of nucleonic viscous stress tensors at finite temperature and density. The finite thermal width or Landau damping is traditionally included in the nucleon propagators. This thermal width is calculated from the in-medium self-energy of nucleon for different possible pion-baryon loops. The dynamical part of nucleon-pion-baryon interactions are taken care by the effective Lagrangian densities of standard hadronic model. The shear viscosity to entropy density ratio of nucleonic component decreases with the temperature and increases with the nucleon chemical potential. However, adding the contribution of pionic component, total viscosity to entropy density ratio also reduces with the nucleon chemical potential when the mixing effect between pion and nucleon components in the mixed gas is considered. Within the hadronic domain, viscosity to entropy density ratio of the nuclear matter is gradually reducing as temperature and nucleon chemical potential are growing up and therefore the nuclear matter is approaching toward the (nearly) perfect fluid nature

    Low mass enhanced probability of pion in hadronic matter due to its Landau cut contributions

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    In the real-time thermal field theory, the pion self-energy at finite temperature and density is evaluated where the different mesonic and baryonic loops are considered. The interactions of pion with the other mesons and baryons in the medium are governed by the effective hadronic Lagrangian densities whose effective strength of coupling constants have been determined from the experimental decay widths of the mesons and baryons. The detail branch cut structures of these different mesonic and baryonic loops are analyzed. The Landau cut contributions of different baryon and meson loops become only relevant around the pion pole and it is completely appeared in presence of medium. The in-medium spectral function of pion has been plotted for different values of temperature, baryon chemical potential as well as three momentum of the pion. A noticeable low mass probability in pion spectral function promise to contribute in the low mass dilepton enhancement via indirect modification of ρ\rho self-energy for ππ\pi\pi loop
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