Accelerating phytoplankton phenomics through FTIR spectroscopy

University of Technology Sydney. Faculty of Science.Marine phytoplankton play a driving role in global biogeochemical cycling, providing fuel for marine and terrestrial ecosystems, and removing substantial quantities of CO₂ from the atmosphere. Phytoplankton respond to environmental change by varying their phenotypes, including photophysiology, macromolecular composition and morphology. Southern Ocean phytoplankton are subjected to one of the most extreme habitats on earth, resulting in great phenotypic variation between and within taxonomic groups. Given they provide a significant net sink of atmospheric CO₂ and support the most biologically productive ecosystem on earth, improving our ability to predict the responses of Southern Ocean phytoplankton to environmental change is of global importance. At present, our ability to predict the responses of these critical organisms to environmental change, including climate change, is limited by a bottleneck in the efficiency with which we can characterise phytoplankton phenotypes. This thesis demonstrates the feasibility of accelerating phytoplankton phenomics using Fourier Transform Infrared (FTIR) microspectroscopy, a powerful yet under-utilised frontier technology. The extensive phenotypic variation shown by Southern Ocean phytoplankton provided excellent scope for demonstrating the power of the microspectroscopic approach. Coupling the microspectroscopic approach with multivariate modeling tools enabled the characterisation of phenotypic plasticity from cell FTIR spectra. When combined with mass spectrometry data, cell FTIR spectra provided accurate estimates of multiple phenotypic parameters including cellular protein, carbon and energy. Of particular value, spectroscopic models were able to accurately estimate rates of carbon production from samples taken at a single time-point, circumventing the need to take measurements over time. Further, the high spatial resolution achievable with microspectroscopy enabled the analysis of individual cells, revealing taxon-specific responses to iron availability within samples taken from a mixed natural Southern Ocean phytoplankton bloom. This work demonstrates that incorporating FTIR microspectroscopy into the phenomics toolbox will improve the efficiency of phenotypic data collection and, in combination with multivariate modeling, will enable the development of powerful, taxon-specific predictive phenomic models

Implications of single field inflation in general cosmological scenarios on the nature of dark energy given the swampland conjectures

Swampland Conjectures have attracted quite some interest in the Cosmological Community. They have been shown to have wide ranging implications , like Constraints on Inflationary Models, Primordial Black Holes etc. to name a few. A particularly revealing insight on dark energy also shows that one can have the dark energy equation of state for a quintessence scenario to be signficantly different than -1 after one takes into account the refined dS conjecture. Another interesting issue with the swampland conjectures is that they have been shown to be incompatible with single field inflationary models in GR based cosmology. In our previous work we have, however, showed that single field inflationary models are quite compatible with swampland conjectures in their usual string theoretic form in a large class of modified cosmological scenarios. Building on that work, we now show that in modified cosmological scenarios where the early universe expansion was driven by single field inflation , one can have the dark energy equation of state to be significantly different from -1 even if we just take into account the original dS conjecture, let alone the refined form of that. We thereby show that one does not need to apply a step function approach towards inflation in order to have an observable distinction between constant and non constant dark energy models in the context of the swampland conjectures.Comment: v2, 9 pages long with added references and minor detail

Type V singularities with inhomogeneous equations of state

Interest in cosmological singularities has remarkably grown in recent times, particularly on future singularities with the discovery of late-time acceleration of the universe and dark energy. Recent work has seen a proper classification of such singularities into strong and weak based on their strength, with weak singularities being the likes of sudden, w and big freeze singularities and strong singularities like the big rip. This has led to a classification of such singularities in various types like Big rip is Type 1, w-singularity is type V etc. While singularities of type I-type IV have been discussed vividly by taking into account inhomogeneous equations of state (EOS), the same has not been attempted for type V singularities. So in this work we have discussed in detail about the formation of type V singularities in various cosmologies after considering inhomogeneous equations of state. We consider two inhomogeneous forms of the EOS in the context of four different cosmological backgrounds ; standard general relativistic cosmology, an asymptotically safe cosmology, a cosmology inspired by modified area-entropy relations, generalized uncertainty principles, holographic renormalization and Chern-Simons gravity( all of which can be coincidentally described by the same form of the modified Friedmann equation) and an f(R) gravity cosmology. We show in detail that one sees some very big differences in the occurence conditions of type V singularities when one makes such considerations. In the particular case of the f(R) gravity cosmology, we see that the type V singularities get completely removed. This work goes to show that the creation and formation of type V singularities is influenced most strongly by the form of the equation of state that one considers, way more so than what background cosmology one chooses.Comment: v2 , 20 pages with some references added, matches the published version in PL

The Exact Solution Approach to Warm Inflation

The theory of Cosmic Inflation has received a great amount of deserved attention in recent years due to it's stunning predictions about the Early Universe. Alongside the usual Cold Inflation paradigm, Warm Inflation has garnered a huge amount of interest in modern Inflationary Studies. It's peculiar features and specifically different predictions from Cold Inflation have led to a substantial amount of literature about it. Various Modified Cosmological Scenarios have also been studied in the Warm Inflationary regime. In this work, we introduce the Exact Solution Approach for Warm Inflation. This Approach allows one to directly study Warm Inflationary regime in a variety of Modified Cosmological Scenarios. We begin by outlining our method and show that it generalizes the Modified Friedmann Approach of Del Campo , and reduces to the well known Hamilton Jacobi Formalism for Inflation in particular limits. We also find the Perturbation spectra for cosmological and tensor perturbations in the Early Universe, and then apply our method to study Warm Inflation in a Tsallis Entropy Modified Friedmann Universe. We end our paper with some concluding remarks on the domain of applicability of our work

Swampland conjectures and single field inflation in modified cosmological scenarios

Swampland Conjectures have attracted quite some interest in the Cosmological Community. They have been shown to have wide ranging implications , like Constraints on Inflationary Models, Primordial Black Holes, Dark Energy to name a few. Particularly, their implications on Single Field Inflationary Models in General Relativity Based Cosmology has gathered huge attention. Swampland Conjectures in their usual form have been shown to be incompatible with these kind of Single Field Models, or have been shown to induce severe Fine Tuning in these Inflationary Models for them to be consistent with the Conjectures. In this work, we show that a Large Class of Single Field Inflationary Models can in fact bypass the problems faced by Inflationary Paradigms in GR Based Cosmology. We use the Exact Solution Approach to Inflation for the same purpose and show how String Theoretic Motivations of the Swampland Conjectures can be in perfect symphony with various Single Field Inflationary Models in Modified Cosmological Scenarios.Comment: 8 page

Rejuvenating the hope of a swampland consistent inflated multiverse with tachyonic inflation in the high energy RS-II Braneworld

The swampland conjectures from string theory have had some really interesting implications on cosmology, in particular on inflationary models. Some models of inflation have been shown to be incompatible with these criterion while some have been shown to be severely fine tuned, with most of these problems arising in single field inflationary models in a General relativistic cosmology. Recent works have although optimistically shown that single field models in more general cosmologies can be consistent with these conjectures and hence there is an optimism that not all such models lie in the swampland. However a paradigm of inflation which has been shown to not be perfectly okay with the conjectures is eternal inflation. So in this work, we discuss Tachyonic inflation in the high energy RS-II Braneworld scenario in the context of the swampland conjectures while also considering the possibility of swampland consistent eternal inflation. We show that our concerned regime evades all the prominent swampland issues for single field inflation being virtually unscathed. After this, we show that the main conflicts of eternal inflation with the swampland can easily be resolved in the considered tachyonic scenario and in particular, we also discuss the exciting prospect of a Generalized Uncertainty Principle facilitating the notion of Swampland consistent eternal inflation. Our work as a whole reignites the possibility that there can be a swampland (and possibly, quantum gravitationally) consistent picture of a "Multiverse".Comment: v2, 22 pages with some changes, matches the published version in MPL

On rips and cosmological singularities in a universe merging with baby universes

Understanding the late-time acceleration of the universe and its subtleties is one of the biggest mysteries in cosmology. A lot of different approaches have been put forward to deal with this, ranging from the conventional cosmological constant to various models of dark energy and beyond. Recently one very interesting approach to explaining the late time acceleration has been put forward, where the the expansion of the universe is driven by mergers with other "baby" universes and has been shown to be quite viable as well from the point of view of recent observational data. So in this work we examine the possibility of various rip scenarios and other future cosmological singularities in such "multiversal" scenario, probing such singularities for the first time in a multi universe scenario. We examine two models of such a baby universe merging cosmology, and show that remarkably no rip scenario or future cosmological singularity is possible in such models.Comment: 13 pages with no figures, comments are very welcome

Little Rip, Pseudo Rip and bounce cosmology with generalized equation of state in non-standard backgrounds

The discovery of universe's late-time acceleration and dark energy has overseen a great deal of research into cosmological singularities and particularly future singularities. Perhaps the most extreme of such singlarities is the big rip, which has propelled a lot of work into ways of moderating it or seeking out alternatives to it and two such alternatives to the big rip are the Little rip and Pseudo rip. Another possibility to consider the far future of the universe is through bounce cosmologies, which presents its own interesting ideas. So in this work we investigate the Little rip, Pseudo rip and Bounce cosmology in non-standard cosmological backgrounds with a generalized equation of state in the presence of a viscous fluid. In particular we discuss about Chern-Simons cosmology and the RS-II Braneworld and discuss how the exotic and non-conventional nature of gravity in such cosmologies affect universal evolution in these scenarios. We find out that there are very significant differences in the behaviour of such cosmic scenarios in these universes in comparison to how they appear in the simple general relativistic universe.Comment: 21 pages, no figures, comments are welcome