Indian Institutes of Science Education and Research

About: Indian Institutes of Science Education and Research is a based out in . It is known for research contribution in the topics: Gravitational wave & LIGO. The organization has 584 authors who have published 731 publications receiving 40599 citations. The organization is also known as: IISERs.

Petrographic and Organic Geochemical Characterizations of Early Eocene Lignites, Cambay Basin, Western India

Abstract: Early Eocene lignite-bearing sequence from Cambay Basin was characterized by means of petrographic and organic geochemical analyses in order to assess its hydrocarbon-generating potential as well as reconstruct the palaeovegetation and palaeoenvironment. Huminite is the most abundant maceral in the samples. Subordinate amount of liptinite and inertinite is also present. The kerogen was classified, based on Rock-Eval and FTIR analyses, as mixed type II/type III with potential to generate both oil and gas upon maturation. The FTIR analysis also indicated abundance of aromatic and phenolic compounds with significant amount of aliphatic components. n–Alkanes present in the lignite samples ranged from C10 to C35, maximizing at C16, and displayed a bimodal distribution suggesting two different organic matter inputs, viz. microbes and higher plants. The triterpenoid class included ββ–hopane series ranging from C29 to C32, several hopenes, oleanenes, ursenes and some des–A–triterpenoids. The hopanes and hopenes were mainly derived from microbial components. Oleanenes, ursenes and des–A–triterpenoids were primarily derived from precursors β– and α–amyrin suggesting angiosperm contribution. Fernenes identified in the samples probably suggested pteridophytic input. The various petrographic parameters demonstrated the environment of deposition of these lignites as being wet, acidic and swampy.

Possible biases in scaling-based estimates of mountain-glacier contribution to the sea level

Abstract: . Predicting mountain-glacier contribution to sea-level rise involves computing global-scale glacier loss under a given climate-change scenario. Such calculations are usually done with low-complexity and computationally-efficient approximate models of glacier dynamics. A statistical power-law relation between glacier volume and area (and/or length) is the basis of several such models. We simulate transient response of an ensemble of 551 glaciers from Ganga basin, the Himalaya, using a scaling-based method and a two-dimensional ice-dynamical model based on shallow-ice approximation (SIA). A comparison of the model outputs suggests that the scaling-based method systematically underestimates long-term ice loss due to a violation of the assumed time-invariant scaling. We derive expressions for the response time and climate sensitivity of glaciers simulated using a time-invariant scaling assumption, and validate them with results from the scaling-based simulation of the ensemble of glacier. These expressions are modified empirically to obtain similar parameterisations of the response properties of glaciers simulated with SIA. These new parameterisation yields a linear-response model which significantly reduces the above biases, while retaining the advantage of numerical efficiency.

Modulational instability characteristics for few cycle pulse propagation in cascaded-quadratic-cubic-quintic nonlinear media

Abstract: Using phase amplitude ansatz method and standard linear stability analysis, we have investigated modulational instability (MI) for the ultrashort pulse propagation in cascaded quadratic-cubic-quintic nonlinear media. Propagation of wave has been described beyond the slowly varying envelope approximation (SVEA). Controlling the generation of frequency side-bands and hence desired pulse, through engineering of different parameters are being explored.

New minimal SO(10) GUT: A theory for all epochs

Abstract: The supersymmetric SO(10) theory (NMSO(10)GUT) based on the ${{\mathbf {210}+\mathbf {126} +\overline {\mathbf {126}}}}$ Higgs system proposed in 1982 has evolved into a realistic theory capable of fitting the known low energy particle physics data besides providing a dark matter candidate and embedding inflationary cosmology. It dynamically resolves longstanding issues such as fast dimension five-operator mediated proton decay in SUSY GUTs by allowing explicit and complete calculation of crucial threshold effects at M SUSY and M GUT in terms of fundamental parameters. This shows that SO(10) Yukawas responsible for observed fermion masses as well as operator dimension-five-mediated proton decay can be highly suppressed on a ‘Higgs dissolution edge’ in the parameter space of GUTs with rich superheavy spectra. This novel and generically relevant result highlights the need for every realistic UV completion model with a large /infinite number of heavy fields coupled to the light Higgs doublets to explicitly account for the large wave function renormalization effects on emergent light Higgs fields. The NMSGUT predicts large-soft SUSY breaking trilinear couplings and distinctive sparticle spectra. Measurable or near measurable level of tensor perturbations – and thus large inflaton mass scale – may be accommodated within the NMSGUT by supersymmetric see-saw inflation based on an LHN flat direction inflaton if the Higgs component contains contributions from heavy Higgs components. Successful NMSGUT fits suggest a renormalizable Yukawon ultraminimal gauged theory of flavour based upon the NMSGUT Higgs structure.

Anisotropic bouncing scenario in $F(X)-V(\phi)$ model

Abstract: We investigate the cosmology of a class of model with noncanonical scalar field and matter in an anisotropic time dependent background. Writing the Einstein Equations in terms of dimensionless dynamical variables appropriately defined for bouncing solutions, we find all the fixed points. While evolving the dynamical variables to their stable fixed points numerically, solutions satisfying non singular bounce are found.