Resolution of holograms produced by the fluid experiment system and the holography ground system

The Fluid Experiment System (FES) was developed to study low temperature crystal growth of triglycine sulfate from solution in a low gravity environment onboard Spacelab. The first flight of FES was in 1985. FES uses an optical system to take holograms of the growing crystal to be analyzed after the mission in the Holography Ground System (HGS) located in the Test Laboratory at Marshall Space Flight Center. Microscopic observation of the images formed by the reconstructed holograms is critical to determining crystal growth rate and particle velocity. FES and HGS were designed for a resolution of better than 20 micrometers, but initial observation of the flight holograms show a limit of 80 micrometers. The resolution of the FES holograms is investigated, as well as the role of beam intensity ratio and exposure time on the resolution of HGS produced holograms

Quantitative Schlieren analysis applied to holograms of crystals grown on Spacelab 3

In order to extract additional information about crystals grown in the microgravity environment of Spacelab, a quantitative schlieren analysis technique was developed for use in a Holography Ground System of the Fluid Experiment System. Utilizing the Unidex position controller, it was possible to measure deviation angles produced by refractive index gradients of 0.5 milliradians. Additionally, refractive index gradient maps for any recorded time during the crystal growth were drawn and used to create solute concentration maps for the environment around the crystal. The technique was applied to flight holograms of Cell 204 of the Fluid Experiment System that were recorded during the Spacelab 3 mission on STS 51B. A triglycine sulfate crystal was grown under isothermal conditions in the cell and the data gathered with the quantitative schlieren analysis technique is consistent with a diffusion limited growth process

Negative Ion Production Rates In Rare Gas-Halide Lasers

This paper reports on dissociative electron attachment in F2, NF3, Cl2, and I2. The principle of the method is to produce a short burst of photoelectrons from a photocathode by means of light from an argon-fluoride laser. Subsequently, by studying the motion of electrons and negative ions in a constant electric field (E) region, information is obtained about drift velocities and effective attachment cross sections. Helium, argon, and nitrogen were used as buffer gases. Of particular interest is a very strong temperature dependence of the attachment coefficient in I2. Measurements were taken from 35 to 110°C, covering an E/N range of 1-50 Townsend. An explanation based on vibrational excitation is presented. Copyright © 1979 by The Institute of Electrical and Electronics Engineers, Inc

Temperature Dependence Of The Electron Attachment Coefficient In Iodine

The attachment coefficient for iodine in a (1% I2+99% N 2) mixture, 50 Torr total pressure, has been measured in an electron swarm experiment from 1 to 50 Townsends (1 Townsend=1Td=10-17 V cm2). As the temperature was increased from 35 to 110°C, the attachment coefficient increased for any E/N (electric field intensity/gas number density) values greater than 7 Td. These results are compared to other experimental data and an explanation for the temperature dependence, based on the population of upper vibrational states, is presented. © 1979 American Institute of Physics

Electron Drift Velocities In N2, CO2, And (N 2+CO2) Laser Mixtures

A time-of-flight technique has been used to obtain electron drift velocities in N2, CO2, and N2-CO2 mixtures covering the E/N range 3-93 Td. In the case of the pure gases, excellent agreement with previous work is obtained over the entire E/N range. The mixtures, which are of laser importance, have not been studied previously

Breaking the Circularity in Circular Analyses: Simulations and Formal Treatment of the Flattened Average Approach

There has been considerable debate and concern as to whether there is a replication crisis in the scientific literature. A likely cause of poor replication is the multiple comparisons problem. An important way in which this problem can manifest in the M/EEG context is through post hoc tailoring of analysis windows (a.k.a. regions-of-interest, ROIs) to landmarks in the collected data. Post hoc tailoring of ROIs is used because it allows researchers to adapt to inter-experiment variability and discover novel differences that fall outside of windows defined by prior precedent, thereby reducing Type II errors. However, this approach can dramatically inflate Type I error rates. One way to avoid this problem is to tailor windows according to a contrast that is orthogonal (strictly parametrically orthogonal) to the contrast being tested. A key approach of this kind is to identify windows on a fully flattened average. On the basis of simulations, this approach has been argued to be safe for post hoc tailoring of analysis windows under many conditions. Here, we present further simulations and mathematical proofs to show exactly why the Fully Flattened Average approach is unbiased, providing a formal grounding to the approach, clarifying the limits of its applicability and resolving published misconceptions about the method. We also provide a statistical power analysis, which shows that, in specific contexts, the fully flattened average approach provides higher statistical power than Fieldtrip cluster inference. This suggests that the Fully Flattened Average approach will enable researchers to identify more effects from their data without incurring an inflation of the false positive rate

Electron Drift Velocities In Gas Mixtures Of He, N2, And CO 2

An electron swarm experiment has been used to obtain electron drift velocities in the He:CO2:N2 mixtures 0:1:1, 3:1:2, and 3:1:1. The E/N range of 3 to 57 Td was studied with total gas pressure varied from 50 to 200 Torr. These particular mixtures have not been previously studied experimentally. Good agreement is observed between theoretical calculations and experimental data

Enhancing Parenting Skills Among Nonresident African American Fathers as a Strategy for Preventing Youth Risky Behaviors

This study evaluated the effectiveness of a theoretically based, culturally specific family intervention designed to prevent youth risky behaviors by influencing the parenting attitudes and behaviors of nonresident African American fathers and the parent–child interactions, intentions to avoid violence, and aggressive behaviors of their preadolescent sons. A sample of 158 intervention and 129 comparison group families participated. ANCOVA results indicated that the intervention was promising for enhancing parental monitoring, communication about sex, intentions to communicate, race‐related socialization practices, and parenting skills satisfaction among fathers. The intervention was also beneficial for sons who reported more monitoring by their fathers, improved communication about sex, and increased intentions to avoid violence. The intervention was not effective in reducing aggressive behaviors among sons. Findings are discussed from a family support perspective, including the need to involve nonresident African American fathers in youth risky behavior prevention efforts.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/116964/1/ajcp9290.pd

Doppler coherence imaging and tomography of flows in tokamak plasmas

This article describes the results of spatial heterodyne Doppler "coherence imaging" of carbon ion flows in the divertor region of the DIII-D tokamak. Spatially encoded interferometric projections of doubly ionized carbon emission at 465 nm have been demodulated and tomographically inverted to obtain the spatial distribution of the carbon ion parallel flow and emissivity. The operating principles of the new instruments are described, and the link between measured properties and line integrals of the flow field are established. An iterative simultaneous arithmetic reconstruction procedure is applied to invert the interferometric phase shift projections, and the reconstructed parallel flow field amplitudes are found to be in reasonable agreement with UEDGE modeling