Measurement of the light flux density patterns from luminaires proposed as photon sources for photosynthesis during space travel

Two luminaires were evaluated to determine the light flux density pattern on a horizontal plane surface. NASA supplied both luminaires; one was made by NASA and the other is commercially available. Tests were made for three combinations of luminaire height and luminaire lens material using the NASA luminaire; only one configuration of the commercial luminaire was tested. Measurements were made using four sensors with different wavelength range capabilities. The data are presented in graphical and tabular formats

Effect of atrazine on algal contamination and sugarcane shoots during photoautotrophic micropropagation

A laboratory procedure was developed for obtaining and maintaining photoautotrophic cultures ofsugarcane shoots in vitro for three generations. Algae contamination in vessels was a problem for photoautotrophic growth under septic conditions. Atrazine, a herbicide, was effective in controlling algae at a concentration of 10 ppm, but the growth of shoots in herbicide-treated sugarless Murashige and Skoog (MS) medium decreased to about half of the growth in untreated medium. As a result, atrazine was not considered to be a practical solution for algae control. Additional work is needed to optimize photoautotrophic micropropagation of sugarcane for both septic and aseptic conditions. Photoautotrophic micropropagation of sugarcane may be economical only if culture can be perfected under septic conditions

Risk Perceptions of Arsenic in Tap Water and Consumption of Bottled Water

The demand for bottled water has increased rapidly over the past decade, but bottled water is extremely costly compared to tap water. The convenience of bottled water surely matters to consumers, but are others factors at work? This manuscript examines whether purchases of bottled water are associated with the perceived risk of tap water. All of the past studies on bottled water consumption have used simple scale measures of perceived risk that do not correspond to risk measures used by risk analysts. We elicit a probability-based measure of risk and find that as perceived risks rise, expenditures for bottled water rise.Environmental Economics and Policy, Risk and Uncertainty, Q25, Q53, I12,

Recycling agricultural runoff

The recycling agricultural runoff concept is the storage of excess water from agricultural land and using this water for irrigation of the same land when moisture supplies are low. Coincidentally, the system also recycles pesticides and nutrients, keeping them out of other parts of the environment. The claypan soils of Illinois appear to be best suited for water recycling when surface storage is used. Sandy soils are best suited to interstitial water storage. A review and analysis of literature on irrigation, drainage, reservoirs, pesticides, and nutrients as it pertains to a recycling system is presented. Nutrient and pesticide recycling result in negligible cost or benefits to agricultural crops. There was insufficient information to determine the economic benefit to the environment of this recycling. A model was developed relating irrigation and drainage to crop yield using intermediate variables of soil moisture and air temperature. The model predicted that an acre-ft. of storage would be required per acre of irrigated watershed. The model was not successful at predicting the increase in yield resulting from irrigation and/or drainage. An example economic analysis reveals that under present conditions recycling agricultural runoff is not economically justifiable as a general practice in the claypan region of Illinois.U.S. Geological SurveyU.S. Department of the InteriorOpe

Surgical Infection Prophylaxis for Left Ventricular Assist Device Implantation

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86804/1/j.1540-8191.2011.01262.x.pd

Distribution of Oscillator Strengths for Recombination of Localised Excitons in Two Dimensions

We investigate the distribution of oscillator strengths for the recombination of excitons in a two dimensional sample, trapped in local minima of the confinement potential: the results are derived from a statistical topographic model of the potential. The predicted distribution of oscillator strengths is very different from the Porter-Thomas disribution which usually characterises disordered systems, and is notable for the fact that small oscillator strengths are extremely rare.Comment: Plain TeX, 11 pages, 2 of 3 Postscript figures, to appear in "Chaos, Solitons and Fractals" special issue on Mesoscopic Physics, July 199

Magnetic Dipole Absorption of Radiation in Small Conducting Particles

We give a theoretical treatment of magnetic dipole absorption of electromagnetic radiation in small conducting particles, at photon energies which are large compared to the single particle level spacing, and small compared to the plasma frequency. We discuss both diffusive and ballistic electron dynamics for particles of arbitrary shape. The conductivity becomes non-local when the frequency is smaller than the frequency \omega_c characterising the transit of electrons from one side of the particle to the other, but in the diffusive case \omega_c plays no role in determining the absorption coefficient. In the ballistic case, the absorption coefficient is proportional to \omega^2 for \omega << \omega_c, but is a decreasing function of \omega for \omega >> \omega_c.Comment: 25 pages of plain TeX, 2 postscipt figure

Cognitive work analysis : extensions and applications in command and control

'Complex sociotechnical systems' are systems made up of numerous interacting parts, both human and non-human, operating in dynamic, ambiguous and safety critical domains. The system design, and representation, has significant implications for the usability of the system, its performance, errors and reliability. Due to its formative constraint-based approach, Cognitive Work Analysis (CWA) has been frequently proposed as a framework for modelling these complex systems, further it is contended that the approach can be extended to design for interaction without significant deviation from the accepted framework. This thesis presents a number of applications in complex military domains to explore and develop the benefits of CWA. Unlike much of the previous literature, particular attention is placed on exploring the CWA framework in its entirety. This holistic approach focuses on the system environment, the activity that takes place within it, the strategies used to conduct this activity, the way in which the constituent parts of the system (both human and non-human) interact and the behaviour required. Each stage of this analysis identifies the constraints governing the system; it is contended that through this holistic understanding of constraints, recommendations can be made for the design of system interaction; increasing the ability of users to cope with unanticipated, unexpected situations. This thesis discusses the applicability of the approach in system analysis, development and evaluation. It provides process to what was previously a loosely defined framework.EThOS - Electronic Theses Online ServiceHuman Sciences Domain of the UK Ministry of Defence Scientific Research ProgrammeGBUnited Kingdo