Richard C. Seagrave

Water and heat exchange between parchment-shelled reptile eggs and their surroundings

important effect on the exchange of heat and water by the eggs. Differences in the patterns of water exchange reported for reptile eggs can be attributed to quantitative differences in the thermal regimes in which the eggs are incubated. The greater the thermal conductivity of the substrate in which eggs are incubating, the more water the eggs will take up under wet conditions and the less water they will lose under dry conditions. Large eggs will be more strongly buffered against water exchange than small eggs and, in similar conditions, they will exchange relatively less water than small eggs. The effect is due to the relationships between egg mass, surface area and water vapor conductance. In this respect, an egg clutch may be viewed as a very large egg which will be much less sensitive to its hydric environment than a single, smaller egg. Temperature and water vapor pressure differences existing inside egg clutches will determine the exchange of heat and water within the clutch and influence the exchange between the clutch and the substrate surrounding it.

Information theoretic subset selection for neural network models

In this work, an information theoretic input variable subset selection (ITSS) scheme for neural network based modeling of chemical processes is proposed. In recent years, artificial neural network models have been shown to be useful empirical models for modeling complex nonlinear chemical processes. ITSS selects an informative subset to be used as input data for constructing a neural network model. ITSS can select appropriate subsets for neural network model development, regardless of the dependencies between the process outputs and inputs. The power of the ITSS method is illustrated through its application to three example problems. Results obtained show that ITSS is capable of identifying subsets for developing viable artificial neural network models. As it uses a smaller set of input variables, ITSS can help identify simpler neural models with better generalization and ease of interpretability.

Mass transfer in laminar falling liquid films with accompanying heat transfer and interfacial shear

Abstract An analysis is made of mass transfer into a laminar finite falling film with accompanying heat transfer and interfacial shear. The analysis is extended to include chemical reaction with linear reaction kinetics. Variations of the liquid physical properties and kinetic rate constants with temperature are explicitly taken into account. Results are compared with the isothermal zero interfacial shear case. Average isothermal and nonisothermal enhancement factors are presented for first- and zero-order reactions. The analysis shows that the heat transfer and gas shear can have a profound influence on the mass transfer rate.

Energy transformation and entropy production in living systems I. Applications to embryonic growth

Generalized material and energy balances are presented for biological systems that experience negligible kinetic, elastic, and potential energy changes. The balances are used to characterize the mass changes and energy transformations that occur in the developing avian embryo, using as an example a consistent set of data for the chicken egg. It is shown that the rate of total chemical energy turnover by the embryo is a quantity of interest and that this rate is not necessarily equivalent to the metabolic rate that is predicted from heat transfer measurements or oxygen consumption rates. The energy required for evaporative water loss is accounted for in the overall energy balance. Using the results of the energy calculations and a generalized expression for the rates of internal and total entropy production, the Prigogine-Wiame hypothesis is examined for the developing embryo with two different assumptions regarding the efficiency of biomass conversion. An order of magnitude analysis of the internal heat-conduction term is performed to show that the chemical reaction term dominates the entropy production relation. The constant efficiency case is shown to be in agreement with the Prigogine-Wiame hypothesis for the data used in the analysis.

The energetics of embryonic growth and development. I. Oxygen consumption, biomass growth, and heat production.

A quantitative phenomenological model to describe the relationships between biomass growth rate, oxygen consumption, and heat production in developing embryos has been developed and tested using a wide range of experimental data. The model employs generalized material and energy balances, principles of enzyme kinetics, and an overall metabolic model scheme based on known biochemical principles. The phosphorylation concentration ratio of ATP and ADP occurs naturally and becomes a significant parameter in the analysis. The model is applied to the growth of Escherichia coli, Oryzias latipes, chick spinal cord, and whole chicken eggs. Excellent agreement between the model and the experimental data is obtained. In a succeeding paper (Part II) environmental effects and growth efficiency are discussed.

PARENT-EGG INTERACTIONS: EGG TEMPERATURE AND WATER LOSS

The avian egg is encased in a hard, calcareous shell and deposited outside the body of the parent. The embryo develops and grows, separated by the shell from the ambient atmosphere surrounding the egg. The chief role of the parent appears to be to attend the egg, moderating and modifying the thermal environment around the egg and controlling the energy exchanged between the egg and surroundings. Control may be exercised in several ways. Eggs are typically deposited during the most appropriate season. The micro-climate of the egg may be influenced by the selection of an appropriate site for egg deposition or by the construction of a nest which acts to separate the egg or some part of it physically from the surroundings. Finally, most birds intervene directly in the process of egg energy exchange by applying a specialized area of skin, the brood patch, to the surface of the egg. Since adult birds maintain body temperatures constant at 38–41 °C and brood patch temperatures are slightly cooler than this (Drent, 1970), energy may be transferred to the egg when the egg is losing heat to the surroundings and absorbed from the egg when the egg is gaining heat from the surroundings.

Analysis of chemically induced growth with one-dimensional mass transfer

Investigations of the transport and reaction phenomena of a growth inducing agent within a dimensionally growing medium provide the first characterizations of a broad class of cellular systems. One-dimensional growth induced by an agent that acts either as a direct growth-inducing catalyst or as a consumed reactant in a growth-inducing reaction can be mechanistically modelled by a linear differential equation describing growth of the medium (by either mechanism) coupled with a nonlinear PDE describing the mass balance in Lagrangian coordinates. Approximations incorporated into the two parallel models state that the dilute agent is transported by Fickian diffusion in a continuum of constant cross-sectional area, that growth of the medium is a linear function of either reaction rate or concentration, and that the apical end of the medium contacts a source of the growth agent while the basal end contacts a sink. Numerical solutions to the models reveal two significant phases of growth: a non-diffusion-limited phase in which the agent approaches a typical steady-state-like distribution and a phase of diffusion-limited growth in which the effects of dilution and consumption predominate over diffusion, significantly decreasing the concentration of the growth agent. The latter phase is a result of rapid growth of the medium or of restrictively long diffusion paths occurring at long times. The model solutions confirm that the phenomena that contribute to the agent concentration changes include diffusive transport, dilution due to growth of the medium, and, in the reaction-growth mechanism, consumption by reaction. Further, results from the use of these approximations show no second-order oscillatory behavior, which experimental data indicate may occur in the coleoptile of corn, a system representative of this class. Specific applications to the corn coleoptile indicate the models will approximately describe the behavior of the coleoptile in early growth—before adaptation, autoregulation, or other higher order processes of the corn plant manifest themselves.

An Experimental and Theoretical Study of Temperature Regulation in the Immersed Dog

An experimental and theoretical study of the canine thermoregulatory system is described in order to obtain a better understanding of how the heat exchange network is employed by the canine to control brain temperature. Particular attention is paid to the nasal heat exchange system.

EXPERIMENTAL DETERMINATION OF HEPATIC BLOOD FLOW USING AN IMPROVED MATHEMATICAL MODEL

Publisher Summary This chapter discusses the development of a mathematical model of indocyanine green (ICG) clearance and excretion and the data handling system designed to control the animal experiments. The predicted blood and bile concentrations of indocyanine green determined by the mathematical model are within limits. Although detailed analysis of the in vivo data is incomplete, there is close agreement to the mathematical model. This suggests the mathematical model is giving a close approximation to the living system. There is close agreement between the model and the in vivo dye concentration curve for blood and bile, suggesting a close approximation of the living system. As the product of the bile concentration curve and the bile flow curve is equal to the dose of dye injected, a comparison will be made to the injected dose to ensure all the dye is being transported into the bile.