Simultaneous Extrema in the Entropy Production for Steady-State Fluid Flow in Parallel Pipes

Steady-state flow of an incompressible fluid in parallel pipes can simultaneously satisfy two contradictory extremum principles in the entropy production, depending on the flow conditions. For a constant total flow rate, the flow can satisfy (i) a pipe network minimum entropy production (MinEP) principle with respect to the flow rates, and (ii) the maximum entropy production (MaxEP) principle of Ziegler and Paltridge with respect to the choice of flow regime. The first principle - different to but allied to that of Prigogine - arises from the stability of the steady state compared to non-steady-state flows; it is proven for isothermal laminar and turbulent flows in parallel pipes with a constant power law exponent, but is otherwise invalid. The second principle appears to be more fundamental, driving the formation of turbulent flow in single and parallel pipes at higher Reynolds numbers. For constant head conditions, the flow can satisfy (i) a modified maximum entropy production (MaxEPMod) principle of \v{Z}upanovi\'c and co-workers with respect to the flow rates, and (ii) an inversion of the Ziegler-Paltridge MaxEP principle with respect to the flow regime. The interplay between these principles is demonstrated by examples.Comment: Revised version 2; 5 figure

Surface Energy Budgets of Arctic Tundra During Growing Season

This study analyzed summer observations of diurnal and seasonal surface energy budgets across several monitoring sites within the Arctic tundra underlain by permafrost. In these areas, latent and sensible heat fluxes have comparable magnitudes, and ground heat flux enters the subsurface during short summer intervals of the growing period, leading to seasonal thaw. The maximum entropy production (MEP) model was tested as an input and parameter parsimonious model of surface heat fluxes for the simulation of energy budgets of these permafrost‐underlain environments. Using net radiation, surface temperature, and a single parameter characterizing the thermal inertia of the heat exchanging surface, the MEP model estimates latent, sensible, and ground heat fluxes that agree closely with observations at five sites for which detailed flux data are available. The MEP potential evapotranspiration model reproduces estimates of the Penman‐Monteith potential evapotranspiration model that requires at least five input meteorological variables (net radiation, ground heat flux, air temperature, air humidity, and wind speed) and empirical parameters of surface resistance. The potential and challenges of MEP model application in sparsely monitored areas of the Arctic are discussed, highlighting the need for accurate measurements and constraints of ground heat flux.Plain Language SummaryGrowing season latent and sensible heat fluxes are nearly equal over the Arctic permafrost tundra regions. Persistent ground heat flux into the subsurface layer leads to seasonal thaw of the top permafrost layer. The maximum energy production model accurately estimates the latent, sensible, and ground heat flux of the surface energy budget of the Arctic permafrost regions.Key PointThe MEP model is parsimonious and well suited to modeling surface energy budget in data‐sparse permafrost environmentsPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/150560/1/jgrd55584.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/150560/2/jgrd55584_am.pd

Maximum Entropy Production Theorem for Transitions between Enzyme Functional States and Its Applications

Transitions between enzyme functional states are often connected to conformational changes involving electron or proton transport and directional movements of a group of atoms. These microscopic fluxes, resulting in entropy production, are driven by non-equilibrium concentrations of substrates and products. Maximal entropy production exists for any chosen transition, but such a maximal transitional entropy production (MTEP) requirement does not ensure an increase of total entropy production, nor an increase in catalytic performance. We examine when total entropy production increases, together with an increase in the performance of an enzyme or bioenergetic system. The applications of the MTEP theorem for transitions between functional states are described for the triosephosphate isomerase, ATP synthase, for β-lactamases, and for the photochemical cycle of bacteriorhodopsin. The rate-limiting steps can be easily identified as those which are the most efficient in dissipating free-energy gradients and in performing catalysis. The last step in the catalytic cycle is usually associated with the highest free-energy dissipation involving proton nanocurents. This recovery rate-limiting step can be optimized for higher efficiency by using corresponding MTEP requirements. We conclude that biological evolution, leading to increased optimal catalytic efficiency, also accelerated the thermodynamic evolution, the synergistic relationship we named the evolution-coupling hypothesis

Below-Ground Root Structure and Ecophysiological Controls of Plant Water Flux During Drought: From Individual to Ecosystem

Shifting patterns of precipitation and rising temperatures have highlighted forest vulnerability to heat- and drought-induced stress. For systems that face water-limitation, either from short-term, seasonal dry periods or longer-term droughts, plasticity of root system function establishes the ability of individuals to meet atmospheric demand and maintain physiological function. This functional plasticity is determined by an individual’s intrinsic properties and their interactions within the community and environment. Given limitations to in situ measurement, improved model representation of below-ground structural and functional complexity has provided means for exploring these ecophysiological feedbacks between drying soil and trees across biomes. This research addresses individual, ecosystem, and basin scale responses to water limitation by examining (i) the role of below-ground structure and ecophysiological controls on water uptake across functional gradients (i.e., low diversity vs. high diversity ecosystems); (ii) identifying and expanding the utility of novel proxies of hydraulic function; and (iii) exploring the feasibility of monitoring drought response at large scales using a parsimonious model of surface energy partitioning. Modeled root water uptake from both temperate and tropical systems highlight that independent of functional strategy, root lateral interactions at the tree scale directly impact the depth distribution of water uptake and plant hydraulic status. A newly developed index of root system interaction provides an amenable axis with which to explore the tradeoffs between structural investment and resource acquisition. Laboratory and field analysis show that conventional technologies used to measure sap flow velocity may contain hidden information regarding a tree’s hydraulic state. This low frequency signal may also serve well as a proxy for below-ground response to the drying soil, providing valuable validation for future modeling efforts. Finally, the feasibility of hourly, basin scale estimates of the land-surface energy budget partition are tested. The Maximum Entropy Production model is successfully applied to the Amazon River Basin, a highly complex region prone to strong seasonal droughts, elucidating avenues of future research needed to more fully link ecosystem and hydrologic processes. The methodologies developed and expanded in this work provide new avenues for assessing tree-scale water fluxes and hydraulic state, providing a means for observing and testing hypotheses related to ecophysiological response across spatiotemporal scales.PhDEnvironmental EngineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/153402/1/lizagee_1.pd

Relational Basis of the Organism's Self-organization A Philosophical Discussion

In this thesis, I discuss the organism’s self-organization from the perspective of relational ontology. I critically examine scientific and philosophical sources that appeal to the concept of self-organization. By doing this, I aim to carry out a thorough investigation into the underlying reasons of emergent order within the ontogeny of the organism. Moreover, I focus on the relation between universal dynamics of organization and the organization of living systems. I provide a historical review of the development of modern ideas related to self-organization. These ideas have been developed in relation to various research areas including thermodynamics, molecular biology, developmental biology, systems theory, and so on. In order to develop a systematic understanding of the concept, I propose a conceptual distinction between transitional self-organization and regulative self-organization. The former refers to the spontaneous emergence of order, whereas the latter refers to the self-maintaining characteristic of the living systems. I show the relation between these two types of organization within biological processes. I offer a critical analysis of various theories within the organizational approach. Several ideas and notions in these theories originate from the early studies in cybernetics. More recently, autopoiesis and the theory of biological autonomy asserted certain claims that were critical toward the ideas related to self-organization. I advocate a general theory of self-organization against these criticisms. I also examine the hierarchical nature of the organism’s organization, as this is essential to understand regulative self-organization. I consider the reciprocal relation between bottom-up and top-down dynamics of organization as the basis of the organism’s individuation. To prove this idea, I appeal to biological research on molecular self-assembly, pattern formation (including reaction-diffusion systems), and the self-organized characteristic of the immune system. Finally, I promote the idea of diachronic emergence by drawing support from biological self-organization. I discuss the ideas related to constraints, potentiality, and dynamic form in an attempt to reveal the emergent nature of the organism. To demonstrate the dynamicity of form, I examine research into biological oscillators. I draw the following conclusions: synchronic condition of the organism is irreducibly processual and relational, and this is the basis of the organism’s potentiality for various organizational states