LM rendezvous procedures - F mission, AS-505/CSM-106/LM-4 Final report

Rendezvous procedures for LM-4 and CSM for use in crew training and flight plannin

Vertical Coherence of Turbulence in the Atmospheric Surface Layer: Connecting the Hypotheses of Townsend and Davenport

Statistical descriptions of coherent flow motions in the atmospheric boundary layer have many applications in the wind engineering community. For instance, the dynamical characteristics of large-scale motions in wall-turbulence play an important role in predicting the dynamical loads on buildings, or the fluctuations in the power distribution across wind farms. Davenport (Quarterly Journal of the Royal Meteorological Society, 1961, Vol. 372, 194-211) performed a seminal study on the subject and proposed a hypothesis that is still widely used to date. Here, we demonstrate how the empirical formulation of Davenport is consistent with the analysis of Baars et al. (Journal of Fluid Mechanics, 2017, Vol. 823, R2) in the spirit of Townsend's attached-eddy hypothesis in wall turbulence. We further study stratification effects based on two-point measurements of atmospheric boundary-layer flow over the Utah salt flats. No self-similar scaling is observed in stable conditions, putting the application of Davenport's framework, as well as the attached eddy hypothesis, in question for this case. Data obtained under unstable conditions exhibit clear self-similar scaling and our analysis reveals a strong sensitivity of the statistical aspect ratio of coherent structures (defined as the ratio of streamwise and wall-normal extent) to the magnitude of the stability parameter

The Effects of Invasion by Reed Canarygrass (Phalaris arundinacea) on Avian Communities and Nesting Success in Minnesota Wetlands

Invasive plants are a primary contributor to loss of biodiversity worldwide. In southern Minnesota, many wetlands have been invaded by reed canarygrass (Phalaris arundinacea). The current perception among ecologists and resource managers is that these wetlands are of little value to wildlife, yet little is known about the effects on birds of the widespread conversion of diverse wetlands to apparent monocultures of P. arundinacea. The purpose of this study was to determine the effects of P. arundinaceamediated changes in the wetland plant community on avian communities and nesting success. During 2006 and 2007, I studied four diverse sedge wetlands paired with four wetlands dominated by P. arundinacea in the farmland region of southern Minnesota. I measured vegetative structure and composition, surveyed birds year-round via the fixedradius point count technique, and conducted nest searching and monitoring to assess nesting success of Red-winged Blackbirds (Agelaius phoeniceus). Vegetation in wetlands invaded by P. arundinacea was taller and had greater visual obstruction readings than vegetation in sedge wetlands, but sedge wetlands had greater plant species richness and number of woody stems/100 m2 that were \u3c two meters tall. Plant species diversity, litter depth, horizontal heterogeneity, and number of woody stems/100 m2 that were \u3e two meters were not different between habitat types. Bird species richness was greater in wetlands invaded by P. arundinacea during the breeding season but did not differ between habitat types during the non-breeding season. Bird species diversity was not different between habitat types during either season. The abundance of individual species, including rare and listed species, also was not different between habitat types for either season, with one exception. The Ring-necked Pheasant (Phasianus colchicus) was more abundant in wetlands dominated by P. arundinacea during the non-breeding season. Rare species collectively contributed similar percent composition to the bird communities of each habitat type. Furthermore, nesting success and density of nests/10 hectares of Red-winged Blackbirds was not different between habitat types. Results of this study did not indicate that invasion by P. arundinacea has a negative effect on bird communities or nesting success of Red-winged Blackbirds in wetlands of southern Minnesota. The invasion by P. arundinacea does not appear to have altered the structure of wetland vegetation in a way that negatively affects birds and may provide better avian habitat than is currently perceived. Although invasion by P. arundinacea had mixed effects on the plant community in this study, it has had marked negative effects on other native plant communities and is likely to be a continual problem in the restoration and management of wetlands in Minnesota

Acute pulmonary pathology and sudden death in rats following the intravenous administration of the plasticizer, DI (2-ethylhexyl) phthalate, solubilized with Tween surfactants

Intravenous administration of 200-300 mg/kg of di(2-ethylhexyl)phthalate (DEHP) solubilized in aqueous solutions of several Tween surfactants caused respiratory distress in rats. There was a dose-dependent lethality with death generally occurring within 90 minutes after injection. The lungs from DEHP:Tween treated animals were enlarged, generally darkened, and in some cases showed hemorrhagic congestion. Neither the overt symptoms nor the morphologic alterations resulting from DEHP:Tween administration could be reproduced by intravenous administration of aqueous Tween solutions alone. The absence of pulmonary abnormalities following the intravenous administration of DEHP as an aqueous emulsion given either alone or even as soon as 2 minutes after pretreatment with Tween 80, suggests that the specific in vivo interaction between DEHP and Tween surfactants depends on the prior formation of water-soluble micelles of DEHP

Semi-Markov adjunction to the Computer-Aided Markov Evaluator (CAME)

The rule-based Computer-Aided Markov Evaluator (CAME) program was expanded in its ability to incorporate the effect of fault-handling processes into the construction of a reliability model. The fault-handling processes are modeled as semi-Markov events and CAME constructs and appropriate semi-Markov model. To solve the model, the program outputs it in a form which can be directly solved with the Semi-Markov Unreliability Range Evaluator (SURE) program. As a means of evaluating the alterations made to the CAME program, the program is used to model the reliability of portions of the Integrated Airframe/Propulsion Control System Architecture (IAPSA 2) reference configuration. The reliability predictions are compared with a previous analysis. The results bear out the feasibility of utilizing CAME to generate appropriate semi-Markov models to model fault-handling processes

Draxin alters laminin organization during basement membrane remodeling to control cranial neural crest EMT

Premigratory neural crest cells arise within the dorsal neural tube and subsequently undergo an epithelial-to-mesenchymal transition (EMT) to leave the neuroepithelium and initiate migration. Draxin is a Wnt modulator that has been shown to control the timing of cranial neural crest EMT. Here we show that this process is accompanied by three stages of remodeling of the basement membrane protein laminin, from regression to expansion and channel formation. Loss of Draxin results in blocking laminin remodeling at the regression stage, whereas ectopic maintenance of Draxin blocks remodeling at the expansion stage. The latter effect is rescued by addition of Snail2, previously shown to be downstream of Draxin. Our results demonstrate an essential function for the Wnt modulator Draxin in regulating basement membrane remodeling during cranial neural crest EMT