Improved techniques for measurement of nanolitre volumes of phloem exudate from aphid stylectomy

Background: When conducting aphid stylectomy, measuring accurate rates of phloem exudation is difficult because the volumes collected are in the nanolitre (nl) range. In a new method, exudate volume was calculated from optical measurement of droplet diameter as it forms on the tip of a severed aphid stylet. Evaporation was shown to decrease the accuracy of the measurement but was countered with the addition of water-saturated mineral oil. Volume measurements by optical estimation of the volume of a sphere suspended in oil was affected by the curvature of the oil surface. In contrast, measuring the exudate volume from optical measurement of droplet-diameter as formed on the tip of a severed aphid stylet, removes any inaccuracies due to oil surface curvature. A modified technique is proposed for measuring exudate volumes without oil by estimating the flow rate from photo-sequences of the collection period; a correction for evaporation is applied later. Results: A change in oil volume of ±1.75% from an optimum volume of 285 μl had a statistically significant effect on droplet measurement, under or over-estimating droplet volume due to optical effects caused by the oil surface. Using microscope image capture and measurement software, a modified method for measuring phloem volume in air was developed, by reducing air exposure during measurement to approximately 5 s for each measurement. Phloem volumes were measured using both techniques with measurements in air being on average 19.9 nl less (SD 18.87, p<0.001) than those made in oil, and there was a strong linear relationship (R2=0.942) between the techniques. This linear relationship enabled the development of a correction equation with no significant difference at the 5% level between corrected volumes and actual volumes measured under oil. Conclusions: This study showed that oil has a significant role in countering evaporation but oil volume must be carefully optimised for optical measurement of droplets to ensure measurement accuracy. A linear correction factor was generated to correct the volumes measured in air for loss due to evaporation and the method provides for a much simpler alternative to previous approaches for measuring exudation rates and volumes from a cut aphid stylet.Lachlan J Palmer, Lyndon T Palmer, Jeremy Pritchard, Robin D Graham and James CR Stangouli

Launch vehicle wind and turbulence response by nonstationary statistical methods

Nonstationary adjoint algorithm for determining launch vehicle flight loads due to winds and turbulenc

Extreme distributions of ground winds /3 to 150 meters/ at Cape Kennedy, Florida

Statistical analysis of wind distribution probabilities at Cape Kenned

Development of stitching reinforcement for transport wing panels

The NASA Advanced Composites Technology (ACT) program has the objective of providing the technology required to obtain the full benefit of weight savings and performance improvements offered by composite primary aircraft structures. Achieving the objective is dependent upon developing composite materials and structures which are damage tolerant and economical to manufacture. Researchers are investigating stitching reinforcement combined with resin transfer molding to produce materials meeting the ACT program objective. Research is aimed at materials, processes, and structural concepts for application in both transport wings and fuselages, but the emphasis to date has been on wing panels. Empirical guidelines are being established for stitching reinforcement in structures designed for heavy loads. Results are presented from evaluation tests investigating stitching types, threads, and density (penetrations per square inch). Tension strength, compression strength, and compression after impact data are reported

Excimer lasers

A theoretical and experimental investigation into the possibility of achieving CW discharge pumped excimer laser oscillation is reported. Detailed theoretical modeling of capillary discharge pumping of the XeF and KXe and K2 excimer systems was carried out which predicted the required discharge parameters for reaching laser threshold on these systems. Capillary discharge pumping of the XeF excimer system was investigated experimentally. The experiments revealed a lower excimer level population density than predicted theoretically by about an order of magnitude. The experiments also revealed a fluorine consumption problem in the discharge in agreement with theory

U.S. Climate Policy Developments

This paper outlines recent developments in U.S. climate policies. Although the United States does not participate in the Kyoto Mechanism, a number of climate policies are being implemented at state level as well as at the federal level. First, we report and compare the federal cap and trade proposals in the 110th Congress. Then, the paper illustrates the current situations of state level climate policies, such as the Regional Greenhouse Gas Initiative in the northeastern states or AB32 in California. We analyze these proposals from the viewpoint of technology policies and impacts on international markets. It is found that technology policies play important roles in the cap and trade proposals and that there is a great expectation for carbon capture and sequestration (CCS) technology. In terms of the impacts on international markets, several federal proposals as well as regional programs permit trading in international markets. As emission targets become more stringent in the future, U.S. GHG emitters are more likely to interact with these markets. Thus, despite the lack of U.S. participation in the Kyoto Protocol, U.S. markets will be linked to foreign markets, at least, in an indirect way.United States, climate policy, cap and trade, the Kyoto mechanism, technology policy

Derivation of equations - Generalized spacecraft simulation. Volume 2 - Control system equations

Equations for active control system of generalized spacecraft simulation computer progra

Missile dynamics for stability analysis. Volume I- Derivation of equations

Derivation of set of linearized dynamic equations for use in missile stability analyse

Study of a nonstationary adjoint statistical wind model for flight control systems analysis Final report

Nonstationary adjoint statistical wind model for flight control systems analysi