Experiment Checkout During Postmanufacturing Checkout of the Apollo Telescope Mount

The postmanufacturing checkout of the Apollo Telescope Mount (ATM) offers a real challenge for both the technology of today and the technology of tomorrow. The objective of this discussion is to explain the sequence of tests to be performed on t he ATM experiments to assure flight readiness, based on current preliminary planning information. Checkout means the verification of all operating systems. The challenge is to define tests today to check out experiments that will be built and flown tomorrow. The engineering state-ofthe art is identified today for a vehicle, including the experiments, that is scheduled to fly in 1972

Application of Fall Nitrogen Increased Spring Tall Fescue Yield

Late season nitrogen fertilization is a practice that has long been implemented in turfgrass production. This practice involves applying nitrogen from September through December and results in an extended green period in the fall without stimulating excessive shoot growth. The longer green period results in higher levels of carbohydrate reserves and enhanced root growth compared with a spring-summer fertilization program. In addition to these benefits, sods fertilized in late fall have been shown to green up two to six weeks earlier in the spring. Limited research has considered the impact of late fall nitrogen applications on grass growth in hayfields and pastures. The objective of this study was to evaluate the impact of late fall nitrogen fertilization on dry matter production of an established tall fescue stand. In 2020 and 2021, the study was conducted at the UK Research and Extension Center located in Princeton, KY. The experimental design was a random complete block with four replications. In early December 2020 and 2021, 0, 34, 67, and 101 kg ha-1 was applied as ammonium nitrate, ammonium sulfate, and Anuvia SYMTRX 20S. An additional 90 kg ha-1 was applied as urea to all plots the following spring. Plots were harvested on 13-May-2021 and 24-May-2022 using a self-propelled sickle bar type forage harvester equipped with load cells. Averaged across sources, first harvest yields ranged from 3428 to 5675 and 3929 to 5831 kg ha-1 in 2021 and 2022, respectively. Fall applied nitrogen resulted in a linear increase in dry matter yield of 25.0 and 21.2 kg ha-1 in 2021 and 2022, respectively. Nitrogen sources had no impact on dry matter yield (P \u3e 0.05). Plots receiving fall applied nitrogen also initiated growth earlier in the spring

Improving Frost Seeding Accuracy with an Entry Level GPS Unit

Guidance utilizing GPS has long been used for various operations in row crop agriculture. However, the high cost of these systems has limited their use in low-input forage and livestock operations. Reduced prices and the availability of used guidance systems have the potential to increase the use of precision agriculture in pastoral settings. In the past, frost seeding often resulted in areas that received no seed and areas that were double seeded. The objective of this experiment was to evaluate the impact of using a guidance system on the uniformity of seed dispersal. This study was conducted at the University of Kentucky’s Research and Education Center, located in Princeton, KY, USA in 2019 and 2021. The experimental design was a randomized complete block with four replications. Four pastures ranging from 2.5 to 4.3 ha were mock seeded using a UTV equipped with GPS guidance technology. The guidance system was initiated, but covered with an opaque bag, and the four pastures were driven by sight alone. This mock seeding process was then repeated utilizing the guidance system. Frost seeding without GPS guidance resulted in a 49% and 21% overlap in 2019 and 2021, respectively. At an overseeding cost of $89/ha and an average overlap of 35%, the cost of a guidance system could be recouped in as little as 48 ha. The results of this study indicate that GPS guidance systems have the potential to improve the uniformity of seed dispersal, thus reducing the cost of frost seeding for producers

Using a neural network approach to accelerate disequilibrium chemistry calculations in exoplanet atmospheres

In this era of exoplanet characterisation with JWST, the need for a fast implementation of classical forward models to understand the chemical and physical processes in exoplanet atmospheres is more important than ever. Notably, the time-dependent ordinary differential equations to be solved by chemical kinetics codes are very time-consuming to compute. In this study, we focus on the implementation of neural networks to replace mathematical frameworks in one-dimensional chemical kinetics codes. Using the gravity profile, temperature-pressure profiles, initial mixing ratios, and stellar flux of a sample of hot-Jupiters atmospheres as free parameters, the neural network is built to predict the mixing ratio outputs in steady state. The architecture of the network is composed of individual autoencoders for each input variable to reduce the input dimensionality, which is then used as the input training data for an LSTM-like neural network. Results show that the autoencoders for the mixing ratios, stellar spectra, and pressure profiles are exceedingly successful in encoding and decoding the data. Our results show that in 90% of the cases, the fully trained model is able to predict the evolved mixing ratios of the species in the hot-Jupiter atmosphere simulations. The fully trained model is ~1000 times faster than the simulations done with the forward, chemical kinetics model while making accurate predictions.Comment: 13 pages, 9 figures, accepted for publication at MNRA

Impact of Brown Midrib Trait on the Decomposition Rate of Sorghum-Sudangrass Residue in Pastures

Sorghum-sudangrass (Sorghum bicolor var. bicolor x bicolor var. sudanense) can provide high quality summer grazing. Some varieties possess the brown midrib (BMR) trait which results in reduced lignin resulting in higher digestibility and animal performance. If microbes in the rumen can digest BMR sorghum-sudangrass more completely, then soil macro/micro flora and fauna may do so as well. This could result in nutrients being returned to the soil faster from plants containing the BMR trait. The objective of this study was to determine the decomposition rate of BMR and non-BMR sorghumsudangrass. The experimental design was a random complete with four replications. Sorghum-sudangrass with and without the BMR trait was placed in litter decomposition bags as whole plants or divided into leaves and stems. A composite sample was taken when bags were loaded to determine initial dry matter. Loaded bags were then placed on the soil surface in a pasture and collected at 1, 2, 3, 4, 6, 8, 10, 12, 14, or 16 weeks after placement. Upon collection plant material was dried for 3-days at 55°C in a forced air oven. Dry weights at each collection date were subtracted from the initial dry weight to determine total DM loss. The BMR trait did not impact dry matter loss in the leaves. Stems possessing the BMR trait lost dry matter at a greater rate resulting in dry matter losses at 14 weeks of 78 and 68% and 59 and 47% for the BMR and non-BMR varieties in trials 1 and 2, respectively. Whole plants showed limited differences in dry matter loss at 14 weeks after placement

A New Understanding of the Europa Atmosphere and Limits on Geophysical Activity

Deep extreme ultraviolet spectrograph exposures of the plasma sheet at the orbit of Europa, obtained in 2001 using the Cassini Ultraviolet Imaging Spectrograph experiment, have been analyzed to determine the state of the gas. The results are in basic agreement with earlier results, in particular with Voyager encounter measurements of electron density and temperature. Mass loading rates and lack of detectable neutrals in the plasma sheet, however, are in conflict with earlier determinations of atmospheric composition and density at Europa. A substantial fraction of the plasma species at the Europa orbit are long-lived sulfur ions originating at Io, with ~25% derived from Europa. During the outward radial diffusion process to the Europa orbit, heat deposition forces a significant rise in plasma electron temperature and latitudinal size accompanied with conversion to higher order ions, a clear indication that mass loading from Europa is very low. Analysis of far ultraviolet spectra from exposures on Europa leads to the conclusion that earlier reported atmospheric measurements have been misinterpreted. The results in the present work are also in conflict with a report that energetic neutral particles imaged by the Cassini ion and neutral camera experiment originate at the Europa orbit. An interpretation of persistent energetic proton pitch angle distributions near the Europa orbit as an effect of a significant population of neutral gas is also in conflict with the results of the present work. The general conclusion drawn here is that Europa is geophysically far less active than inferred in previous research, with mass loading of the plasma sheet ≤4.5 x 10^(25) atoms s^(-1) two orders of magnitude below earlier published calculations. Temporal variability in the region joining the Io and Europa orbits, based on the accumulated evidence, is forced by the response of the system to geophysical activity at Io. No evidence for the direct injection of H_2O into the Europa atmosphere or from Europa into the magnetosphere system, as has been observed at Enceladus in the Saturn system, is obtained in the present investigation

Ghost analysis visualization techniques for complex systems: examples from the NIF Final Optics Assembly

The stray light or �ghost� analysis of the National Ignition Facility�s (NIP) Final Optics Assembly (FOA) has proved to be one of the most complex ghost analyses ever attempted. The NIF FOA consists of a bundle of four beam lines that: 1) provides the vacuum seal to the target chamber, 2) converts l(omega) to 3(omega) light, 3) focuses the light on the target, 4) separates a fraction of the 3(omega) beam for energy diagnostics, 5) separates the three wavelengths to diffract unwanted 1(omega) & 2(omega) light away from the target, 6) provides spatial beam smoothing, and 7) provides a debris barrier between the target chamber and the switchyard mirrors. The three wavelengths of light and seven optical elements with three diffractive optic surfaces generate three million ghosts through 4th order. Approximately 24,000 of these ghosts have peak fluence exceeding 1 J/cm2. The shear number of ghost paths requires a visualization method that allows overlapping ghosts on optics and mechanical components to be summed and then mapped to the optical and mechanical component surfaces in 3D space. This paper addresses the following aspects of the NIF Final Optics Ghost analysis: 1) materials issues for stray light mitigation, 2) limitations of current software tools (especially in modeling diffractive optics), 3) computer resource limitations affecting automated coherent raytracing, 4) folding the stray light analysis into the opto-mechanical design process, 5) analysis and visualization tools from simple hand calculations to specialized stray light analysis computer codes, and 6) attempts at visualizing these ghosts using a CAD model and another using a high end data visualization software approach

Predicting aflatoxin content in peanuts using ambient temperature, soil temperature and soil moisture content during pod development

Higher than acceptable aflatoxin levels in peanut kernels (Arachis hypogaea L.) and related products is a worldwide food safety concern. Strict regulatory standards by major importers of peanuts limit the marketability of peanuts for many developing tropical countries including Zambia. The incidence of preharvest aflatoxins is strongly linked to soil and weather conditions during pod-development. This study aimed to formulate statistical models to predict total aflatoxin content in peanut kernels using selected environmental factors during pod development. Field experiments were conducted for two years during which the peanut crop was exposed to 84 combinations of ambient temperature, soil temperature and soil moisture content measured during the last 30 days of pod development. These data were used to formulate regression models to predict total aflatoxin content in peanut kernels. Simple linear regression models had R2 values of 0.30 for maximum ambient temperature, 0.24 for soil temperature and 0.38 for soil moisture content. Combining soil moisture content and soil temperature in a multivariate regression model could explain 54% of the variation in total aflatoxin content while a combination of soil moisture content and maximum ambient temperature could only explain 46% of the variation in total aflatoxin content

Biphasic Elimination of Tenofovir Diphosphate and Nonlinear Pharmacokinetics of Zidovudine Triphosphate in a Microdosing Study

Objective: Phase 0 studies can provide initial pharmacokinetics (PKs) data in humans and help to facilitate early drug development, but their predictive value for standard dosing is controversial. To evaluate the prediction of microdosing for active intracellular drug metabolites, we compared the PK profile of 2 antiretroviral drugs, zidovudine (ZDV) and tenofovir (TFV), in microdose and standard dosing regimens. Study Design: We administered a microdose (100 μg) of [superscript 14]C-labeled drug (ZDV or tenofovir disoproxil fumarate) with or without a standard unlabelled dose (300 mg) to healthy volunteers. Both the parent drug in plasma and the active metabolite, ZDV-triphosphate (ZDV-TP) or TFV-diphosphate (TFV-DP) in peripheral blood mononuclear cells (PBMCs) and CD4[superscript +] cells were measured by accelerator mass spectrometry. Results: The intracellular ZDV-TP concentration increased less than proportionally over the dose range studied (100 μg–300 mg), whereas the intracellular TFV-DP PKs were linear over the same dose range. ZDV-TP concentrations were lower in CD4[superscript +] cells versus total PBMCs, whereas TFV-DP concentrations were not different in CD4[superscript +] cells and PBMCs. Conclusions: Our data were consistent with a rate-limiting step in the intracellular phosphorylation of ZDV but not TFV. Accelerator mass spectrometry shows promise for predicting the PK of active intracellular metabolites of nucleosides, but nonlinearity of PK may be seen with some drugs.Johns Hopkins University (Institute for Clinical and Translational Research CTSA Grant UL1-RR025005