Morphology, lifecycles, and environmental sensitivities of tropical trimodal convection

Includes bibliographical references.2022 Fall.Convective clouds are ubiquitous in the tropics and typically follow a trimodal distribution of cumulus, congestus, and cumulonimbus clouds. Due to the crucial role each convective mode plays in tropical and global transport of heat and moisture, there has been both historical and recent interest in the characteristics, sensitivities, and lifecycles of these clouds. However, designing novel studies to further our knowledge has been challenging due to several limitations: the extensive computing resources needed to conduct modeling studies at sufficient resolution and scale to capture the trimodal distribution in detail; the lack of analysis tools which can objectively detect and track these clouds throughout their lifetime; and a need for more observational and modeling data of the tropical convective environments that produce these clouds. In this dissertation, three distinct but related studies that address these problems to advance the knowledge of our field on the morphology, lifecycles, and environmental sensitivities of tropical trimodal convection are presented. The first study examines the sensitivities of the tropical trimodal distribution and the convective environment to initial aerosol loading and low-level static stability. The Regional Atmospheric Modeling System (RAMS) configured as a Large Eddy Simulation (LES) is utilized to resolve all three modes in detail through two full diurnal cycles. Three initial static stabilities and three aerosol profiles are independently and simultaneously varied for a suite of nine simulations. This research found that (1) large aerosol loading and strong low-level static stability suppress the bulk environment and the intensity and coverage of convective clouds; (2) cloud and environmental responses to aerosol loading tend to be stronger than those from static stability; (3) the effects of aerosol and stability perturbations modulate each other substantially; (4) the deepest convection and highest dynamical intensity occur at moderate aerosol loading, rather than at low or high loading; and (5) most of the strongest feedbacks due to aerosol and stability perturbations are seen in the boundary layer (the latter being applied within the boundary layer themselves), though some are stronger above the freezing level. The second study presented seeks to further enhance an artificial intelligence analysis tool, the Tracking and Object-Based Analysis of Clouds (tobac) Python package, from both a scientific and procedural standpoint to enable a wider variety of research uses, including process-level studies of tropical trimodal convection. Scientific improvements to tobac v1.5 include an expansion of the tool from 2D to 3D analyses and the addition of a new spectral filtering tool. Procedural enhancements added include greater computational efficiency, data regridding capabilities, and treatments for processing data with singly or doubly periodic boundary conditions (PBCs). My distinct contributions to this work focused on the 2D to 3D expansion and the PBC treatment. These new capabilities are presented through figures, schematics, and discussion of the new science that tobac v1.5 facilitates, such as the analysis of large basin-scale datasets and detailed simulations of layered clouds, that would have been impossible before. Finally, the last study in this dissertation is a process-focused modeling study on the sensitivities of upscale growth of tropical trimodal convection to environmental aerosol loading. This project was enabled by the scientific and procedural improvements to tobac discussed in the second study, in particular the new abilities of tobac to detect and track objects in 3D and with model PBCs. Here, we used a subset of RAMS simulations from the first study, where only aerosol loading was changed and the upscale growth from shallow cumulus through congestus and cumulonimbus during the nighttime hours was investigated. This study revealed that moderately increasing aerosol loading enhances collision-coalescence processes in the middle of the cloud, which delays initial glaciation but promotes it later in the growth period. Greatly increasing aerosol, however, produces a cloud structure with a more extreme aspect ratio and greater entrainment aloft that rapidly loses buoyancy and vertical velocity with height, as well as exhibiting a greater amount of condensate loading towards the top of the cloud. We also found the relative timing of these processes to be especially important, with more rapid initial growth and lofting of condensate often inhibiting deeper convective growth

(Optochemical) Control of Synthetic Microbial Coculture Interactions on a Microcolony Level

Synthetic microbial cocultures carry enormous potential for applied biotechnology and are increasingly the subject of fundamental research. So far, most cocultures have been designed and characterized based on bulk cultivations without considering the potentially highly heterogeneous and diverse single-cell behavior. However, an in-depth understanding of cocultures including their interacting single cells is indispensable for the development of novel cultivation approaches and control of cocultures. We present the development, validation, and experimental characterization of an optochemically controllable bacterial coculture on a microcolony level consisting of two Corynebacterium glutamicum strains. Our coculture combines an l-lysine auxotrophic strain together with a l-lysine-producing variant carrying the genetically IPTG-mediated induction of l-lysine production. We implemented two control approaches utilizing IPTG as inducer molecule. First, unmodified IPTG was supplemented to the culture enabling a medium-based control of the production of l-lysine, which serves as the main interacting component. Second, optochemical control was successfully performed by utilizing photocaged IPTG activated by appropriate illumination. Both control strategies were validated studying cellular growth on a microcolony level. The novel microfluidic single-cell cultivation strategies applied in this work can serve as a blueprint to validate cellular control strategies of synthetic mono- and cocultures with single-cell resolution at defined environmental conditions

(Optochemical) Control of Synthetic Microbial Coculture Interactions on a Microcolony Level

Burmeister A, Akhtar Q, Hollmann L, et al. (Optochemical) Control of Synthetic Microbial Coculture Interactions on a Microcolony Level. ACS synthetic biology. 2021.Synthetic microbial cocultures carry enormous potential for applied biotechnology and are increasingly the subject of fundamental research. So far, most cocultures have been designed and characterized based on bulk cultivations without considering the potentially highly heterogeneous and diverse single-cell behavior. However, an in-depth understanding of cocultures including their interacting single cells is indispensable for the development of novel cultivation approaches and control of cocultures. We present the development, validation, and experimental characterization of an optochemically controllable bacterial coculture on a microcolony level consisting of two Corynebacterium glutamicum strains. Our coculture combines an l-lysine auxotrophic strain together with a l-lysine-producing variant carrying the genetically IPTG-mediated induction of l-lysine production. We implemented two control approaches utilizing IPTG as inducer molecule. First, unmodified IPTG was supplemented to the culture enabling a medium-based control of the production of l-lysine, which serves as the main interacting component. Second, optochemical control was successfully performed by utilizing photocaged IPTG activated by appropriate illumination. Both control strategies were validated studying cellular growth on a microcolony level. The novel microfluidic single-cell cultivation strategies applied in this work can serve as a blueprint to validate cellular control strategies of synthetic mono- and cocultures with single-cell resolution at defined environmental conditions

MOESM1 of Combinatorial optimization of synthetic operons for the microbial production of p-coumaryl alcohol with Escherichia coli

Additional file 1. Supplementary Information

Combinatorial optimization of synthetic operons for the microbial production of p-coumaryl alcohol with Escherichia coli

BACKGROUND: Microbes are extensively engineered to produce compounds of biotechnological or pharmaceutical interest. However, functional integration of synthetic pathways into the respective host cell metabolism and optimization of heterologous gene expression for achieving high product titers is still a challenging task. In this manuscript, we describe the optimization of a tetracistronic operon for the microbial production of the plant-derived phenylpropanoid p-coumaryl alcohol in Escherichia coli. RESULTS: Basis for the construction of a p-coumaryl alcohol producing strain was the development of Operon-PLICing as method for the rapid combinatorial assembly of synthetic operons. This method is based on the chemical cleavage reaction of phosphorothioate bonds in an iodine/ethanol solution to generate complementary, single-stranded overhangs and subsequent hybridization of multiple DNA-fragments. Furthermore, during the assembly of these DNA-fragments, Operon-PLICing offers the opportunity for balancing gene expression of all pathway genes on the level of translation for maximizing product titers by varying the spacing between the Shine-Dalgarno sequence and START codon. With Operon-PLICing, 81 different clones, each one carrying a different p-coumaryl alcohol operon, were individually constructed and screened for p-coumaryl alcohol formation within a few days. The absolute product titer of the best five variants ranged from 48 to 52 mg/L p-coumaryl alcohol without any further optimization of growth and production conditions. CONCLUSIONS: Operon-PLICing is sequence-independent and thus does not require any specific recognition or target sequences for enzymatic activities since all hybridization sites can be arbitrarily selected. In fact, after PCR-amplification, no endonucleases or ligases, frequently used in other methods, are needed. The modularity, simplicity and robustness of Operon-PLICing would be perfectly suited for an automation of cloning in the microtiter plate format. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12934-015-0274-9) contains supplementary material, which is available to authorized users

Connected Companies' Compensation Acknowledgements: We thank

Abstract When portfolio managers trade the stocks of companies run by people with whom they have social connections, these trades earn better returns than trades in companies with whom they have no connections (Cohen et al., 2008). We look at the effects of social connections from the firm's side, examining the compensation of firm executives. Executive compensation in connected firms is substantially higher than in unconnected firms. The channel through which this result occurs appears to be share voting-connected funds are more likely to vote against shareholder-initiated proposals on executive compensation, thereby protecting their cronies from the discipline of corporate governance. The evidence is consistent with higher compensation being the quid pro quo for information flow from firm to fund