Computer codes for the evaluation of thermodynamic properties, transport properties, and equilibrium constants of an 11-species air model

The computer codes developed provide data to 30000 K for the thermodynamic and transport properties of individual species and reaction rates for the prominent reactions occurring in an 11-species nonequilibrium air model. These properties and the reaction-rate data are computed through the use of curve-fit relations which are functions of temperature (and number density for the equilibrium constant). The curve fits were made using the most accurate data believed available. A detailed review and discussion of the sources and accuracy of the curve-fitted data used herein are given in NASA RP 1232

Computer codes for the evaluation of thermodynamic and transport properties for equilibrium air to 30000 K

The computer codes developed here provide self-consistent thermodynamic and transport properties for equilibrium air for temperatures from 500 to 30000 K over a temperature range of 10 (exp -4) to 10 (exp -2) atm. These properties are computed through the use of temperature dependent curve fits for discrete values of pressure. Interpolation is employed for intermediate values of pressure. The curve fits are based on mixture values calculated from an 11-species air model. Individual species properties used in the mixture relations are obtained from a recent study by the present authors. A review and discussion of the sources and accuracy of the curve fitted data used herein are given in NASA RP 1260

A review of reaction rates and thermodynamic and transport properties for an 11-species air model for chemical and thermal nonequilibrium calculations to 30000 K

Reaction rate coefficients and thermodynamic and transport properties are reviewed and supplemented for the 11-species air model which can be used for analyzing flows in chemical and thermal nonequilibrium up to temperatures of 3000 K. Such flows will likely occur around currently planned and future hypersonic vehicles. Guidelines for determining the state of the surrounding environment are provided. Curve fits are given for the various species properties for their efficient computation in flowfield codes. Approximate and more exact formulas are provided for computing the properties of partially ionized air mixtures in a high energy environment. Limitations of the approximate mixing laws are discussed for a mixture of ionized species. An electron number-density correction for the transport properties of the charged species is obtained. This correction has been generally ignored in the literature

Rhythmic expression of an egr-1 transgene in rats distinguishes two populations of photoreceptor cells in the retinal outer nuclear layer

Purpose: Nocturnal rhythms of gene expression in the retina are known to be both darkness- and circadian clock-dependent, but their role and cellular location are not well defined. In the present study we have used a new transgenic rat model (early growth response gene 1-destablized, enhanced green fluorescent protein 2; egr-1-d2EGFP) to investigate the rhythmic regulation of darkness-related gene expression. Methods: Adult transgenic rats were sampled during the light and dark phases of a standard laboratory lighting schedule. The cellular location of transgene expression in retinal sections was detected either via immunohistochemistry for green fluorescent protein (GFP) or via direct microscopy. The GFP expression pattern was compared to endogenous proteins (Egr-1, melanopsin, rhodopsin) via dual fluorophore immunohistochemistry. Day-night changes in GFP and Egr-1 expression were quantified by western blot analysis of retinal protein extracts. Results: Nocturnal transgene expression was abundant in the outer nuclear layer (ONL) of the retina, recapitulating expression of the endogenous Egr-1 protein. The transgene provided greatly enhanced visualization of the ONL cellular expression pattern, in part due to cellular filling by GFP molecules that pervade rod photoreceptor cells including inner and outer segments. The transgene was also expressed in isolated (Egr-1-positive) cells of the inner nuclear layer and the ganglion cell layer. In the ONL, a marked day-night rhythm in transgene expression was found to be predominantly within an inner zone of this retinal nuclear layer. This concentration of rhythmic GFP/Egr-1 to the inner ONL was not associated with differential localization of rhodopsin. Conclusions: Analysis of a novel transgenic rat strain has identified subpopulations of rod photoreceptor cells that differ with respect to rhythmic nocturnal expression of egr-1. These studies demonstrate the value of this genetic approach that has provided a model for the functional characterization of retinal rhythms, specifically addressing the role of Egr-1 within nocturnal transcriptional events in a rod photoreceptor population. Because the darkness-dependent induction of Egr-1 is gated by a circadian clock, this model can also provide insights into the cellular mechanisms of circadian regulation in the retina

Pulsed electric field in combination with vacuum impregnation with trehalose improves the freezing tolerance of spinach leaves

Pulsed electric fields in combination with vacuum infusion have been utilized to impregnate cells with trehalose, aiming at substantially improving the freezing tolerance of spinach leaves. Spinach samples were first treated with ten trains of bi-polar, rectangular electric field pulses with a nominal electric field strength of 580 V/cm and immediately immersed in a 40% (w/w) solution of trehalose under vacuum for 20 min. The samples were kept in the trehalose solution for 2.5 h at atmospheric pressure, immersed in deionised water at 4 ºC overnight, frozen in liquid nitrogen and thawed in water at room temperature. The leaves were evaluated for cell damage with microscopic observations and wilting tests. The results provided evidence that the impregnation with trehalose by the combined actions of electric fields and vacuum impregnation drastically improved the freezing tolerance of the spinach leaves

OPTIMISATION OF TAKEOFF TECHNIQUE FOR MAXIMUM FORWARD ROTATION IN SPRINGBOARD DIVING

The aim of this study was to optimise springboard diving takeoff technique for maximum forward rotation using a computer simulation model. A planar eight-segment model of a diver with torque generators together with a springboard model was developed. The model was evaluated by comparing simulation output with an elite diver's performance. The model was then used to optimise takeoff techniques for maximum rotational potential in the forward dive group by varying the activation timings of the torque-generators. There was a 20% increase in rotational potential in the optimised simulation compared to a performance of a forward two and one-half somersault pike (105 B) dive. The results highlight the importance of technique in springboard diving since by changing only the activation timing alone the diver can generate substantially more forward rotation

A NEW MODEL OF THE SPRINGBOARD IN DIVING

This paper presents a model which describes the vertical, horizontal and rotational movement of a diving springboard. Model parameters were determined from experimental data. The springboard model was used in conjunction with a diver model to simulate a diving takeoff. Diving performance of an elite female diver was recorded at 200 Hz and was digitised to obtain kinematic data used to drive the simulation. There was good agreement in terms ot linear and angular takeoff conditions between the performance and the simulation. It is concluded that the proposed model is an improved representation of the springboard as a simple mass-spring system. This model will be used in conjunction with a diver model to investigate takeoff techniques and optimise diving performance

CONSTRAINTS AND ROBUSTNESS CONSIDERATIONS IN THE OPTIMISATION OF SPRINGBOARD DIVING TAKEOFF TECHNIQUE: A SIMULATION STUDY

The aim of this study was to investigate the effects of imposing anatomical constraints and robustness requirements on the optimisation of springboard diving takeoff technique. A planar eight-segment model of a diver with torque generators together with a springboard model was used to optimise takeoff techniques for maximum rotational potential in the forward dive group by varying the activation timings of the torque-generators. Optimisation 1 imposed no constraints or robustness requirements. Optimisation 2 imposed anatomical constraints. Optimisation 3 imposed anatomical constraints and a requirement of robustness to perturbations in activation timing. The results showed that imposing both anatomical constraints and robustness requirements have a substantial effect on optimum simulated performance

Effect of fatigue and hypohydration on gait characteristics during treadmill exercise in the heat while wearing firefighter thermal protective clothing.

This study compared the gait characteristics of individuals walking in heat while wearing firefighting equipment in fatigued and non-fatigued states. Nineteen subjects performed a 50-min treadmill protocol in a heated room while gait patterns were recorded using a digital video camcorder. Forty gait cycles were analyzed near the beginning (9 min) and at the end (39-49 min) of exercise. Spatio-temporal gait variables including step frequency, step length, swing time, stance time, cycle time and double-support time were determined. Gait variability was quantified by the standard deviation (SD) and coefficient of variation (CV) of each variable. Left-right symmetry was calculated using the symmetry index (SI) and symmetry angle (SA). Paired t-tests (alpha = 0.05) were performed to identify difference between the beginning and the end of the protocol for each measured variable. Spatio-temporal gait characteristics did not differ between the beginning and the end of exercise. Gait variability of the double-support time increased at the end as measured by both SD (P = 0.037) and CV (P = 0.030) but no change was observed for other variables. Left-right symmetry measured using either SI or SA did not differ between sessions. In summary, spatio-temporal gait characteristics and symmetry while wearing firefighting equipment are insensitive to physiological fatigue. Prolonged walking in heat while wearing firefighting equipment may increase gait variability and therefore the likelihood of a fall. Future studies are needed to confirm the potential relationship between fatigue and gait variability and to investigate the possible influence of individual variation