NEW SELF-GRAVITATIONAL OSCILLATORY EIGENMODE PATTERNS OF SOLAR PLASMA WITH BOLTZMANN-DISTRIBUTED ELECTRONS

We attempt to propose a simplified theoretical model to study new stationary states of the nonlinear self-gravitational fluctuation dynamics of the solar plasma with the zero-inertia electrons against weakly nonlinear perturbation within the framework of the Jeans homogenization assumption. This is based on a bi-fluidic approach with the thermal electrons treated as the Boltzmann-distributed species. The joint effects of space-charge polarization, sheath-formation, and bi-layer plasma-boundary interaction through gravito-electrostatic interplay in a spherically symmetric geometry are considered. Applying a standard multiscale technique, a unique form of extended Korteweg-de Vries-Burger (e-KdVB) equation with a new selfconsistent linear sink is methodologically developed. The origin of the unique sink lies in the spherically symmetric self-gravity contributed by the massive ions. A numerical shape-analysis with multi-parameter variation depicts the co-existence of two distinct classes of new eigenmode excitations. The fluctuation patterns evolve as oscillatory soliton-like and oscillatory shock-like patterns in judicious plasma conditions under the adiabatic electronic response. Their oscillations, arising due to resonant and non-resonant coupling phenomena with the background spectral components, get gradually damped out due to the sink. This scientific study allows us to conjecture that the model supports self-gravitational solitary (shock) waves having tails (fronts) composed of a sequence of slightly overlapping solitons with smoothly varying characteristic parameters. Our results are compared with the earlier theoretical model predictions, on-board multispace satellite data and spacecraft observations highlighting tentative future scopes

New Aspects on Stability Analysis of a Planar Charge-varying Collisional Dust Molecular Cloud with Finite Thermal Inertia

A theoretical evolutionary model for the nonlinear stability analysis of a planar dust molecular cloud (DMC) in quasi-neutral hydrodynamic equilibrium on the Jeans scales of space and time is developed. It is based on a self-gravitating multi-fluid model consisting of the warm electrons and ions, and the inertial cold dust grains with partial ionization. The Jeans assumption of self-gravitating uniform medium is adopted for fiducially analytical simplification by neglecting the zero-order field. So, the equilibrium is justifiably treated initially as “homogeneous”, thereby validating nonlinear local analysis. The lowest-order finite inertial correction of the thermal species (thermal inertia, which is conventionally neglected), heavier grain-charge fluctuation and all the possible collisional dynamics are included simultaneously amid non-equilibrium plasma inhomogeneities. We apply a standard multiple scaling technique methodologically to show that the eigenmodes are collectively governed by a new electrostatic driven Korteweg-de Vries (d-KdV) equation having a self-consistent nonlinear driving source, and self-gravitational Korteweg-de Vries (KdV) equation with neither a source, nor a sink. A detailed numerical shape-analysis with judicious multi-parameter variation parametrically portrays the excitation of electrostatic eigenmodes evolving as damped oscillatory shocks (nonconservative) with the increasing global amplitude due to the source, and extended two-tail compressive solitons (conservative), when the source-strength becomes very weak. In contrast, the self-gravitational counterparts grow as bell-shaped rarefactive soliton-like structures (conservative). The correlative effect of diverse plasma parameters on the amplitudes and patterns is explicitly investigated. Interestingly, this is conjectured that the grain-mass plays a key role in the eigenmode shaping (growth and decay) through the interplaying processes of pulsating gravito-electrostatic coupling. As the grain-mass increases, a new type of shock-to-soliton transition results, and so forth. The significance of the study in space, laboratory and astrophysical environments is stressed.

Understanding sheath blight resistance in rice: the road behind and the road ahead

Rice sheath blight disease, caused by the basidiomycetous necrotroph Rhizoctonia solani, became one of the major threats to the rice cultivation worldwide, especially after the adoption of high-yielding varieties. The pathogen is challenging to manage because of its extensively broad host range and high genetic variability and also due to the inability to find any satisfactory level of natural resistance from the available rice germplasm. It is high time to find remedies to combat the pathogen for reducing rice yield losses and subsequently to minimize the threat to global food security. The development of genetic resistance is one of the alternative means to avoid the use of hazardous chemical fungicides. This review mainly focuses on the effort of better understanding the host–pathogen relationship, finding the gene loci/markers imparting resistance response and modifying the host genome through transgenic development. The latest development and trend in the R. solani–rice pathosystem research with gap analysis are provided