Opening Agriculture: Alternative Technological Strategies for Sustainable Farming

This thesis investigates the potential for alternative technology development for the purposes of improving sustainable agriculture. By synthesizing ideological frameworks from Agroecology, Appropriate Technology and Open Source Hardware, a set of benchmarks are defined in order to gauge the sustainability of existing agricultural technology, as well as guide the development of new farm technology. Using these benchmarks, a number of practical farm technology projects envisioned by the author are discussed, with an emphasis on the design and construction of two specific projects, an egg incubator and an electric fence charger, both built with salvaged materials and open-source documentation. While the cost of each project was far less expensive than its commercial equivalent, time spent and labor costs are examined and discussed in light of other future open-source farm projects

Socially Distant Signing: Why Georgia Should Adopt Remote Will Execution in the Post-COVID World

In the wake of the COVID-19 pandemic, Georgia Governor Brian Kemp and other state governors issued emergency executive orders authorizing the attestation and execution of wills, trusts, and other testamentary documents through the use of audio-video technology. Most states have traditionally required that such testamentary documents be signed in the physical presence of two or more witnesses to be valid. Georgia’s executive order permits these witnesses to instead observe the signing via video-conferencing software, alleviating the requirement that the witnesses be physically present with the testator. This authorization, however, only exists through this executive order and could lapse or be overturned by another executive order. The Georgia General Assembly should codify a version of the governor’s executive order to permanently allow remote execution and attestation of testamentary documents. Remote execution and attestation increases access to estate planning services—particularly in Georgia’s rural communities— without sacrificing the traditional safeguards of wills formalities. This Note presents the arguments for permanently adopting remote execution and attestation, explores efforts by other jurisdictions in this area, and presents a suggested set of criteria for the Georgia General Assembly as guidance when considering such legislation

The coevolution of toxin and antitoxin genes drives the dynamics of bacterial addiction complexes and intragenomic conflict

Bacterial genomes commonly contain ‘addiction’ gene complexes that code for both a toxin and a corresponding antitoxin. As long as both genes are expressed, cells carrying the complex can remain healthy. However, loss of the complex (including segregational loss in daughter cells) can entail death of the cell. We develop a theoretical model to explore a number of evolutionary puzzles posed by toxin–antitoxin (TA) population biology. We first extend earlier results demonstrating that TA complexes can spread on plasmids, as an adaptation to plasmid competition in spatially structured environments, and highlight the role of kin selection. We then considered the emergence of TA complexes on plasmids from previously unlinked toxin and antitoxin genes. We find that one of these traits must offer at least initially a direct advantage in some but not all environments encountered by the evolving plasmid population. Finally, our study predicts non-transitive ‘rock-paper-scissors’ dynamics to be a feature of intragenomic conflict mediated by TA complexes. Intragenomic conflict could be sufficient to select deleterious genes on chromosomes and helps to explain the previously perplexing observation that many TA genes are found on bacterial chromosomes

Eco-Evolutionary Feedback and the Invasion of Cooperation in Prisoner's Dilemma Games

Unveiling the origin and forms of cooperation in nature poses profound challenges in evolutionary ecology. The prisoner's dilemma game is an important metaphor for studying the evolution of cooperation. We here classified potential mechanisms for cooperation evolution into schemes of frequency- and density-dependent selection, and focused on the density-dependent selection in the ecological prisoner's dilemma games. We found that, although assortative encounter is still the necessary condition in ecological games for cooperation evolution, a harsh environment, indicated by a high mortality, can foster the invasion of cooperation. The Hamilton rule provides a fundamental condition for the evolution of cooperation by ensuring an enhanced relatedness between players in low-density populations. Incorporating ecological dynamics into evolutionary games opens up a much wider window for the evolution of cooperation, and exhibits a variety of complex behaviors of dynamics, such as limit and heteroclinic cycles. An alternative evolutionary, or rather succession, sequence was proposed that cooperation first appears in harsh environments, followed by the invasion of defection, which leads to a common catastrophe. The rise of cooperation (and altruism), thus, could be much easier in the density-dependent ecological games than in the classic frequency-dependent evolutionary games

Tracking Sleep Times to Reduce Tiredness and Improve Sleep in College Students

The purpose of this study was to determine the effect that additional sleep health education, as well as recording amounts of nightly sleep had on the amounts of sleep and sense of daytime sleepiness, experienced by participants enrolled in a personal health class at a state university in the Pacific Northwest. Participants were divided into four groups, a control, a group that received sleep education only, a group that kept a sleep log only, and a group that received both interventions. Outcomes were assessed with a three day sleep recall, and using the Epworth Sleepiness Scale (ESS). The students who received both interventions improved their sleep by over 50 minutes per nigh

The coevolution of cooperation and dispersal in social groups and its implications for the emergence of multicellularity

<p>Abstract</p> <p>Background</p> <p>Recent work on the complexity of life highlights the roles played by evolutionary forces at different levels of individuality. One of the central puzzles in explaining transitions in individuality for entities ranging from complex cells, to multicellular organisms and societies, is how different autonomous units relinquish control over their functions to others in the group. In addition to the necessity of reducing conflict over effecting specialized tasks, differentiating groups must control the exploitation of the commons, or else be out-competed by more fit groups.</p> <p>Results</p> <p>We propose that two forms of conflict – access to resources within groups and representation in germ line – may be resolved in tandem through individual and group-level selective effects. Specifically, we employ an optimization model to show the conditions under which different within-group social behaviors (cooperators producing a public good or cheaters exploiting the public good) may be selected to disperse, thereby not affecting the commons and functioning as germ line. We find that partial or complete dispersal specialization of cheaters is a general outcome. The propensity for cheaters to disperse is highest with intermediate benefit:cost ratios of cooperative acts and with high relatedness. An examination of a range of real biological systems tends to support our theory, although additional study is required to provide robust tests.</p> <p>Conclusion</p> <p>We suggest that trait linkage between dispersal and cheating should be operative regardless of whether groups ever achieve higher levels of individuality, because individual selection will always tend to increase exploitation, and stronger group structure will tend to increase overall cooperation through kin selected benefits. Cheater specialization as dispersers offers simultaneous solutions to the evolution of cooperation in social groups and the origin of specialization of germ and soma in multicellular organisms.</p

Entrance effects on solution transport through nanoporous membranes

Solution transport across nanoporous membranes occurs in many different biologically and industrially relevant processes such as filtration of waste by the kidneys and desalination of seawater. The same theoretical framework can be used to understand both of these processes, as well as many others. In general, a flux of solution is driven across a porous membrane due to an externally applied force. This external force can be a gradient in pressure, temperature, concentration, or electrical potential. At the entrance and exit of a pore the fluid streamlines and electric field lines experience a significant constriction in going from the bulk reservoirs to the narrow pores. This effect can become significant for short pores and pores with low friction and thus must be appropriately taken into account to correctly predict solution fluxes. In the first study, continuum mechanics is used to investigate the entrance effects on charge flux of electrolytes across porous membranes. The access electrical resistance, which is the electrical resistance associated with the electric field lines bending into and out of the pores, has previously been shown to make up a significant fraction of the total electrical resistance when the fluid–pore friction is low.1 Although several papers have studied the access electrical resistance,2–5 none has explicitly considered the effect of surface charge on the surfaces of the membrane facing the bulk solution even though this charge has been shown to have a significant effect on the access electrical resistance.6 In this thesis, finite element method (FEM) calculations are carried out in order to systematically study the access electrical resistance of charged pores in charged and uncharged membranes. The results are compared with predictions from two existing continuum-based theories and a new theory derived in this thesis. It is found that the FEM results agree with different theories depending on whether or not the outer-membrane surface is charged. In the second study an existing molecular dynamics (MD) algorithm is used to simulate concentration differences across pores connected to bulk reservoirs. The algorithm is found to require a modification at high solute concentrations, which had not previously been considered. In the third study the modified MD algorithm is used to investigate possible non-continuum and non-ideal effects on concentration-gradient-driven flows at high solute concentrations. Entrance effects are considered in the context of diffusio-osmotic flows, which are flows driven by forces acting on the inhomogeneous fluid layer near the membrane pore surfaces as a result of an applied concentration gradient. The access diffusio-osmotic resistance, which is the resistance to the diffusio-osmotic flux associated with the fluid streamlines bending into and out of the pores, is calculated and compared with a new theory that is derived in this thesis. The assumptions made in deriving the new theory include, amongst others a dilute solution and continuum theory. Despite these assumptions, the theory predicts the correct scaling of the MD results at two different high solute concentrations. It is found that both electrical and diffusio-osmotic access resistances can be separated from their respective total (access and pore) resistances. Depending on whether the length scales of interest, such as the pore radius, are comparable with the pore length, the access resistance can be a significant factor in determining the total resistance of the system. This is explored in this thesis in the context of both electrical and diffusio-omsotic resistance, which affect a wide range of different systems.Thesis (MPhil) -- University of Adelaide, School of Physical Sciences, 201

Horizontal Gene Transfer and The Evolution of Bacterial Cooperation

Bacteria frequently exhibit cooperative behaviors but cooperative strains are vulnerable to invasion by cheater strains that reap the benefits of cooperation but do not perform the cooperative behavior themselves. Bacterial genomes often contain mobile genetic elements such as plasmids. When a gene for cooperative behavior exists on a plasmid, cheaters can be forced to cooperate by infection with this plasmid, rescuing cooperation in a population in which mutation or migration has allowed cheaters to arise. Here we introduce a second plasmid that does not code for cooperation and show that the social dilemma repeats itself at the plasmid level in both within-patch and metapopulation scenarios, and under various scenarios of plasmid incompatibility. Our results suggest that although plasmid carriage of cooperative genes can provide a transient defense against defection in structured environments, plasmid and chromosomal defection remain the only stable strategies in an unstructured environment. We discuss our results in the light of recent bioinformatic evidence that cooperative genes are overrepresented on mobile elements