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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 775 records · Page 43
All sourcesNASA NTRSDOE OSTI
NASA NTRS1987

Influence of suction and curvature on the growth of Goertler vortices on an airfoil

Laser velocimetry (LV) was used to study the development of Goertler vortices in a laminar boundary layer on a 1.83 m chord airfoil model. The vortex pattern was visualized using a sublimating chemical technique. A fixed, essentially uniform vortex spacing was observed throughout the test region for any given freestream velocity but the vortex wavelength varied significantly with change in freestream velocity. An appreciable, abrupt decrease in streak contrast indicated vortex damping in the convex region and was confirmed by disturbance functions determined from LV measurements. Moderate variation in suction levels did not alter the vortex spacing but appreciably modified the vortex strength. The experimental results on the growth of Goertler vortices along the concave surface and the effect of suction are compared with results from linear stability theory.

Mangalam, S. M.↗
NASA NTRS2004

Exploratory Investigation of Failure Mechanisms in Transition Regions between Solid Laminates and X-cor(registered tm) Truss Sandwich

Small sub-component specimens consisting of solid laminates at the ends that transition to X-cor(R) truss sandwich in the center, were tested in a combination of three point bending, uni-axial tension, and combined tension and bending. The failure process in the transition region was documented for each loading using digital video and high-resolution cameras. For the 3-point bending tests, most of the deformation occurred in the solid laminate regions on either end of the specimen. Some pin debonding from the skin of the X-cor(R) truss sandwich was observed in the transition region and was accompanied by audible "pings" throughout the loading. Tension loaded specimens failed in the sandwich skin in the middle of the gage length, accompanied by separation of the sandwich core from the back skin and by delamination between the top skin and bottom skin at the transition region. The pinging associated with pin debonding occurred as the load was increased. However, the frequency of the pinging exceeded any visual observations of pin debonding in the video of the transition region. For specimens tested in combined tension and bending, the greatest amount of pinging occurred during initial application of the axial load. High-resolution images in the transition region indicated that the pinging corresponded to pins debonding and buckling due to the through-thickness Poisson contraction of the specimen. This buckling continued to a much smaller extent as the transverse load was applied.

OBrien, T. Kevin↗
NASA NTRS2004

Performance Effects of Display Incogruity in a Digital and Analog Clock Reading Task

In an era of increasing automation, it is important to design displays and input devices that minimize human error. In this context, information concerning the human response to the detection of incongruous information is important. Such incongruous information can be operationalized as unexpected (perhaps erroneous) information on which a decision by the human or operation by an automated system is based. In the aviation environment, decision making when faced with inadequate, incomplete, or incongruous information may occur in a failure scenario. An additional challenge facing the human operator in automated environments is maintaining alertness or vigilance. The vigilance issue is of particular concern as a factor that may interact with performance when faced with inadequate, incomplete, or incongruous information. From the literature on eye-scan behavior we know that the time spent looking at a particular display or indicator is a function of the type of information one is trying to discern from the display. For example, quick glances are all it takes for confirming that an indicator is in a normal position or range, whereas a continuous look of several seconds may be required for confirmation that a complex control input is having the desired effect. Important to consider is that while an extended look takes place, visual input from other sources may be missed. Much like an extended look, the interpretation of incongruous information may require extra time. The present experiment was designed to explore the performance consequences of a decision making task when incongruous information was presented. For this experiment a display incongruity was created on a subset of trials of a clock reading laboratory task. Display incongruity was made possible through presentation of 'impossible' times (e.g. 1:65 or 11:90). Subjects made 'same' 'different' decisions and keyboard responses to pairings of Analog-Analog (AA), Digital-Digital (DD), and Analog- Digital (AD), display combinations. For trials during which display incongruities were not presented, based on prior research comparing digital and analog clock displays, it would be expected that the Digital-Digital condition would result in the shortest response times and the Analog-Analog and Analog-Digital conditions would have longer response times. The performance consequence expected on trials with incongruous times would be very long response times.

J. Raymond Comstock, Jr.↗
NASA NTRS2004

Optimizing environmental conditions for mass application of mechano-dwarfing stimuli to Arabidopsis

Obtaining uniform mechano-dwarfing of Arabidopsis thaliana (L.) Heynh. seedlings within dense plantings is problematic. Alternative forms of mechano-stimulation were applied to seedlings in effort to obtain uniform growth reduction compared with undisturbed controls in both greenhouse and controlled growth environments. Arabidopsis grown under low photosynthetic photon flux (PPF) artificial light grew upright with limited leaf expansion, which enhanced mechano-responsiveness compared to that of rosette-growing plants under filtered sunlight or high PPF artificial light. Hypocotyls of seedlings grown at PPFs > 60 micromoles m-2 s-1 elongated less and had 6% less sensitivity to mechanical stress than seedlings grown at PPFs < 60 micromoles m-2 s-1. Fluorescent lamps alone (F) or fluorescent plus incandescent (F+I) lamps were compared for seedling responses to mechanical stress. Under F lighting, hypocotyl elongation was reduced 25% to 40% by twice-daily brush or plate treatments, and brushed seedlings exhibited more growth reduction than did plate treatments. Seedlings grown under F+I lamps exhibited similar stress-induced growth reduction compared to seedlings grown under F only, but stressed F+I seedlings lodged to a greater extent due to excessive hypocotyl elongation. Temperature-response studies using standardized F-only lighting indicated increased hypocotyl elongation but decreased leaf expansion, and decreased mechano-responsivity to brushing over the temperature range from 20 to 28 degrees C. Daylength studies indicated similar degrees of mechano-inhibition of hypocotyl elongation over the daylength range of 12, 16, 20, and 24 hours, whereas fresh weight of stressed seedling shoots declined compared to controls. A combination of environmental growth parameters that give repeatable, visual mechanical dwarfing of Arabidopsis include low-PPF fluorescent lighting from 55 to 60 micromoles m-2 s-1, ambient temperatures from 22 to 25 degrees C, and twice-daily brush treatments.

NASA Discipline Life Support Systems↗
NASA NTRS2007

Solutions Network Formulation Report. Visible/Infrared Imager/Radiometer Suite and Advanced Microwave Scanning Radiometer Data Products for National Drought Monitor Decision Support

Drought effects are either direct or indirect depending on location, population, and regional economic vitality. Common direct effects of drought are reduced crop, rangeland, and forest productivity; increased fire hazard; reduced water levels; increased livestock and wildlife mortality rates; and damage to wildlife and fish habitat. Indirect impacts follow on the heels of direct impacts. For example, a reduction in crop, rangeland, and forest productivity may result in reduced income for farmers and agribusiness, increased prices for food and timber, unemployment, reduced tax revenues, increased crime, foreclosures on bank loans to farmers and businesses, migration, and disaster relief programs. In the United States alone, drought is estimated to result in annual losses of between $6 - 8 billion. Recent sustained drought in the United States has made decision-makers aware of the impacts of climate change on society and environment. The eight major droughts that occurred in the United States between 1980 and 1999 accounted for the largest percentage of weather-related monetary losses. Monitoring drought and its impact that occurs at a variety of scales is an important government activity -- not only nationally but internationally as well. The NDMC (National Drought Mitigation Center) and the USDA (U.S. Department of Agriculture) RMA (Risk Management Agency) have partnered together to develop a DM-DSS (Drought Monitoring Decision Support System). This monitoring system will be an interactive portal that will provide users the ability to visualize and assess drought at all levels. This candidate solution incorporates atmospherically corrected VIIRS data products, such as NDVI (Normalized Difference Vegetation Index) and Ocean SST (sea surface temperature), and AMSR-E soil moisture data products into two NDMC vegetation indices -- VegDRI (Vegetation Drought Response Index) and VegOUT (Vegetation Outlook) -- which are then input into the DM-DSS.

Estep, Leland↗
NASA NTRS2017

Evaluating the Subjective Straight Ahead Before and After Spaceflight

Introduction. This joint European Space Agency/NASA pre- and post-flight study investigates the influence of exposure to microgravity on the subjective straight ahead (SSA) in crewmembers returning from long-duration expeditions to the International Space Station (ISS). The SSA is a measure of the internal representation of body orientation and to be influenced by stimulation of sensory systems involved in postural control. The use of a vibrotactile sensory aid to correct the representation of body tilted relative to gravity is also tested as a countermeasure. This study addresses the sensorimotor research gap to "determine the changes in sensorimotor function over the course of a mission and during recovery after landing." Research Plans. The ISS study will involve eight crewmembers who will participate in three pre-flight sessions (between 120 and 60 days before launch) and then three post-flight sessions on R plus 0/1 day, R plus 4 days, and R plus 8 days. Sixteen control subjects were also tested during three sessions to evaluate the effects of repeated testing and to establish normative values. The experimental protocol includes measurements of gaze and arm movements during the following tasks: (1) Near & Far Fixation: The subject is asked to look at actual targets in the true straight-ahead direction or to imagine these targets in the dark. Targets are located at near distance (arm's length) and far distance (beyond 2 meters). This task is successively performed with the subject's body aligned with the gravitational vertical, and with the subject's body tilted in pitch relative to the gravitational vertical using a tilt chair. Measures are then compared with and without a vibrotactile sensory aid that indicates how far one has tilted relative to the vertical; (2) Eye and Arm Movements: The subject is asked to look and point in the SSA direction in darkness and then make horizontal and vertical eye or arm movements, relative to Earth coordinates (allocentric) and to the subject's head/body reference (egocentric). This task is successively performed with the subject's body aligned with the gravitational vertical, and with subject's body tilted in roll using a tilt chair; (3) Linear Vestibulo-Ocular Reflex: The subject is asked to fixate actual visual targets at near and far distances in the true straight-ahead direction, and to evaluate the distance of these targets. The subject is asked to continue fixating the same imagined targets in darkness while he/she is passively accelerated up and down on a spring-loaded vertical linear accelerator. Results. In the control subject population, the perceived tilt angles, translations, and distances were remarkably close to the actual values. The pointing tasks indicated that the orientation of arm saccades was influenced by both the gravitational vertical and the body idiotropic vector. Repeating the testing did not reveal any significant changes. Preliminary results obtained in three crewmembers before and after flight will also be presented. Applications. A change in an individual's egocentric reference might have negative consequences on evaluating the direction of an approaching object or on the accuracy of reaching movements or locomotion. Consequently, investigating how microgravity affects the target location will have theoretical, operational, and even clinical implications for future space exploration missions. The use of vibrotactile feedback as a sensorimotor countermeasure is applicable to balance therapy applications for patients with vestibular loss and the elderly to mitigate risks due to loss of spatial orientation.

Campbell, D. J.↗
NASA NTRS2004

Full-Body Gaze Control Mechanisms Elicited During Locomotion: Effects Of VOR Adaptation

Control of locomotion requires precise interaction between several sensorimotor subsystems. During locomotion the performer must satisfy two performance criteria: maintain stable forward translation and to stabilize gaze (McDonald, et al., 1997). Precise coordination demands integration of multiple sensorimotor subsystems for fulfilling both criteria. In order to test the general hypothesis that the whole body can serve as an integrated gaze stabilization system, we have previously investigated how the multiple, interdependent full-body sensorimotor subsystems respond to changes in gaze stabilization task constraints during locomotion (Mulavara and Bloomberg, 2003). The results suggest that the full body contributes to gaze stabilization during locomotion, and that its different functional elements respond to changes in visual task constraints. The goal of this study was to determine how the multiple, interdependent, full-body sensorimotor subsystems aiding gaze stabilization during locomotion are functionally coordinated after the vestibulo-ocular reflex (VOR) gain has been altered. We investigated the potential of adaptive remodeling of the full-body gaze control system following exposure to visual-vestibular conflict known to adaptively reduce the VOR. Subjects (n=14) walked (6.4 km/h) on the treadmill before and after they were exposed to 0.5X manifying lenses worn for 30 minutes during self-generated sinusoidal vertical head rotations performed while seated. In this study we measured: temporal parameters of gait, full body sagittal plane segmental kinematics of the head, trunk, thigh, shank and foot, accelerations along the vertical axis at the head and the shank, and the vertical forces acting on the support surface. Results indicate that, following exposure to the 0.5X minifying lenses, there was a significant increase in the duration of stance and stride times, alteration in the amplitude of head movement with respect to space and a significant increase in the amount of knee flexion during the initial stance phase of the gait cycle. This study provides further evidence that the full body contributes to gaze stabilization during locomotion, and that different functional elements are responsive to changes in visual task constraints and are subject to adaptive alteration following exposure to visual-vestibular conflict.

Mulavara, A. P.↗
NASA NTRS1997

Annual Sea Level Variability Induced by Changes in Sea Ice Extent and Accumulation on Ice Sheets: An Assessment Based on Remotely Sensed Data

Changes of mean annual net accumulation at the surface on the grounded ice sheets of East Antarctica, West Antarctica, and Greenland in response to variations in sea ice extent are estimated using grid-point values 100 km apart. The data bases are assembled principally by bilinear interpolation of remotely sensed brightness temperature (Nimbus-5 ESMR, Nimbus-7 SMMR), surface temperature (Nimbus-7 THIR), and surface elevation (ERS-1 radar altimeter). These data, complemented by field data where remotely sensed data are not available, are used in multivariate analyses in which mean annual accumulation (derived from firn emissivity) is the dependent variable; the independent variables are latitude, surface elevation, mean annual surface temperature, and mean annual distance to open ocean (as a source of energy and moisture). The last is the shortest distance measured between a grid point and the mean annual position of the 10% sea ice concentration boundary, and is used as an index of changes in sea ice extent as well as of mean concentration. Stepwise correlation analyses indicate that variations in sea ice extent of +/-50 km would lead to changes in accumulation inversely of +/-4% on East Antarctica, +/- 10% on West Antarctica, and +4% on Greenland. These results are compared with those obtained in a previous study using visually interpolated values from contoured compilations of field data; they substantiate the findings for the Antarctic ice sheets (+/-4% on East Antarctica, +/-9% in West Antarctica), and suggest a reduction by one half of the probable change of accumulation on Greenland (from +/-8%). The results also suggest a reduction of the combined contribution to sea level variability to +/- 0.19 mm/a (from +/- 0.22 mm/a).

Zwally, H. J.↗
NASA NTRS2003

Research Participation in the Mars Orbiter Laser Altimeter Experiment

This report describes the tasks that have been completed by the Principal Investigator, Gordon Pettengill, and his team during the first year of this grant. Dr. Pettengill was assisted by Dr. Peter Ford and Ms. Joan Quigley. Our main task has been to analyze the polar clouds detected by MOLA (Mars Orbiter Laser Altimeter) during the nominal mission of the Mars Global Surveyor (MGS) in 1999-2001 and to correlate the results with other data sets, in particular that from TES, the MGS thermal emission spectrometer. Starting with the Martian cloud database that we constructed prior to the start of this grant, we have examined all TES footprints that overlap MOLA clouds in time and space, correlating the thermal signature against specific categories that we assign to MOLA clouds on the basis of visual inspection. We are particularly interested in clouds in the region of "cold spots", areas of anomalously low thermal brightness temperature that have been detected in the polar winter by several instruments beginning with IRIS on Mariner 9. They are thought to indicate regions of active CO2 sublimation or snowfall, and it is hoped that MOLA measurements may tell us more about these regions.

Pettengill, Gordon H.↗
NASA NTRS2007

Analysis of Thermal Control Coatings on MISSE for Aerospace Applications

Many different passive thermal control materials were flown as part of the Materials on International Space Station Experiment. Engineers and scientists at the Marshall Space Flight Center have analyzed a number of these materials, including: Zinc oxide/potassium silicate coating, Zinc oxide/potassium silicate/silicone coating, Zinc orthotitanate/potassium silicate coating, Electrically conductive thermal control coatings and Various coatings for part marking, automated rendezvous and capture, and astronaut visual aids These and other material samples were exposed to the low Earth orbital environment of atormc oxygen, ultraviolet radiation, thermal cycling, and hard vacuum, though atomic oxygen exposure was very limited for some samples. Solar absorptance, infrared emittance, and mass measurements indicate the durability of these materials to withstand the space environment. The effect of contamination from an active space station on the performance of white thermal control coatings is discussed.

Finckenor, Miria↗
NASA NTRS2015

Effects of Angular Frequency During Clinorotation on Mesenchymal Stem Cell Morphology and Migration

Background/Objectives: Ground-based microgravity simulation can reproduce the apparent effects of weightlessness in spaceflight using clinostats that continuously reorient the gravity vector on a specimen, creating a time-averaged nullification of gravity. In this work, we investigated the effects of clinorotation speed on the morphology, cytoarchitecture, and migration behavior of human mesenchymal stem cells (hMSCs). Methods: We compared cell responses at clinorotation speeds of 0, 30, 60, and 75 rpm over 8 hours in a recently developed lab-on-chip-based clinostat system. Time lapse light microscopy was used to visualize changes in cell morphology during and after cessation of clinorotation. Cytoarchitecture was assessed by actin and vinculin staining, and chemotaxis was examined using time lapse light microscopy of cells in NGF (100 ng/ml) gradients. Results: Among clinorotated groups, cell area distributions indicated a greater inhibition of cell spreading with higher angular frequency (p is less than 0.005), though average cell area at 30 rpm after 8 hours became statistically similar to control (p = 0.794). Cells at 75rpm clinorotation remained viable and were able to re-spread after clinorotation. In chemotaxis chambers clinorotation did not alter migration patterns in elongated cells, but most clinorotated cells exhibited cell retraction, which strongly compromised motility.

microgravity↗
NASA NTRSDate not supplied

Mapping Wetland and Riparian Areas to Support Rio Grande Cutthroat Trout Habitat Restoration

The Rio Grande cutthroat trout (Oncorhynchus clarki virginalis; RGCT) population has declined significantly over the last century due to habitat loss, competition, and hybridization with non-native trout species. The species currently occupies roughly 11% of its historic habitat. Conservation efforts led by government and private actors have succeeded in increasing RGCT populations since the early 2000s. State, federal, and private partners began the largest native trout restoration initiative in North America. Since 2002, these efforts have included wetland and riparian area restoration and RGCT reintroduction. Current restoration efforts focus on restoring the Costilla Creek Watershed located in Colorado and New Mexico to provide cool water temperatures, improve water quality, and maintain suitable habitat for the trout species. To guide these restoration efforts, the team conducted a rapid assessment to locate and characterize wetland and riparian areas in the Costilla Creek watershed. The team utilized NASA data from the Landsat 8 Operational Land Imager (OLI), as well as the Sentinel-2 MultiSpectral Instrument (MSI), and the Sentinel-1 Synthetic Aperture Radar (SAR) for May 2016 to October 2019. To produce probability maps of wetland presence, the team used the Software for Assisted Habitat Modeling (SAHM) incorporating predictor variables generated from topographic indices, spectral indices, and radar. The top three models (General Wetland model, Stream and Wetland Connectivity model, and Inclusive Wetland model) showed a strong ability to detect wetlands. They all had AUC values greater than 0.9 and had high overlap with wetland areas during visual assessment over high-resolution imagery. The General Wetland model output was converted into a wetland polygon dataset and polygons were classified by wetland type. The resulting maps and datasets will support partners in determining the extent of possible RGCT habitat and identifying where habitat restoration efforts may be needed.

NASA DEVELOP↗
NASA NTRSDate not supplied

Characterization of Reactant Refill and Detonation Wave Dynamics in a GOx/Natural-gas RDRE Using Simultaneous High Repetition-Rate OH-PLIF and Chemiluminescence

The potential application of rotating detonation engines (RDEs) in rocket combustors hinges on a fundamental understanding of detonation wave structure and injector characteristics with fuel and oxidizer compositions relevant in rocket systems. Simultaneous 300 kHz-rate broadband OH* chemiluminescence and OH-PLIF imaging is employed in a fully optically accessible Natural Gas-GOx rotating detonation rocket engine (RDRE) to visualize reactant refill dynamics and detonation wave structure. A custom-built KTP-type optical parametric oscillator (OPO) is coupled with a nanosecond high-repetition-rate burst-mode laser to output284 nm light and target excitation of the Q1(9) transition in the OH radical. Significant deflagrative burning is observed throughout the chamber as a consequence of the oxygen-rich environment. Trailing Azimuthal Reflected Shock Combustion (ARSC) system, similar to those in a H2-air RDE are observed, burning unburned reactants in the region immediately following the primary detonation wave. Contact burning, as indicated in this study, does not seem to be a primary loss mechanism. The simultaneous measurement of OH and OH* show that axial locations exist in the refill process where OH radicals are present, and produced due to shear layer induced deflagration, however, these zones do not produce excited state OH*. While a deeper understanding of the underlying physics in RDRE systems requires further investigation, this work highlights a first-of-its-kind visualization of the turbulent combustion product field and reactant refill characteristics in this highly unsteady environment.

Propulsion↗
NASA NTRS1984

Digital image filtering in visualized boundary layers

The application of two-dimensional low-pass matched filtering is presented for use in objective processing of digitized flow visualization images in order to identify instantaneous large-scale organized structures in turbulent boundary layers. The images were digitally acquired simultaneously with the outputs of a two-dimensional rake of hot-wire sensors in the field of view of the digital camera. Two-dimensional low wavenumber analysis brought out patterns in the visualization images which consisted of slender inclined structures having an average streamwise scale of 100-200 v/u (tau) and a length on the order of 1-2 delta. The similarly processed two-dimensional streamwise velocity reconstructions reveal similar features. The ensemble statistics indicate that these inclined features brought out by this processing may be a basic flow module in higher Reynolds number flows which links the so-called wall 'bursting' process and the larger outer scale motions.

Corke, T. C.↗
NASA NTRSDate not supplied

Satellite orbit predictor

An analog aid to determine satellite coverage of Emergency Locator Transmitters Emergency Position Indicating Radio Beacon (ELT/EPIRB) distress incidence is discussed. The satellite orbit predictor is a graphical aid for determining the relationship between the satellite orbit, antenna coverage of the spacecraft and coverage of the Local User Terminal. The predictor allows the user to quickly visualize if a selected position will probably be detected and is composed of a base map and a satellite track overlay for each satellite.A table of equator crossings for each satellite is included.

Friedman, Morton l.↗
NASA NTRS1993

Ultraviolet-excess selection of the counterpart to a globular cluster X-ray burster - Hubble Space Telescope images of the core of NGC 6712

Using the Planetary Camera on the Hubble Space Telescope, we have obtained high spatial resolution, multicolor images and photometry of the core of the globular cluster NGC 6712. A comparison of our blue and ultraviolet images unambiguously reveals a faint (B = 21), UV-excess object, 'star S', within the Einstein error box for the bursting X-ray source X1850-086. The unusual color of star S is immediately apparent even in a cursory visual comparison of the images, and is more quantitatively (U-B of about -1) confirmed via photometry. A variety of different candidate optical counterparts to the X-ray source have previously been suggested from ground-based work, but our images indicate that star S is almost certainly the only viable candidate brighter than U = 21. Compared with the mean values for low mass X-ray binaries in the field, star S has a typical (U-B) color, and a moderate-to-high X-ray-to-optical luminosity ratio, but its luminosity (MB = 5) is about 4 mag fainter than average.

Anderson, Scott F.↗
NASA NTRS1996

A Passive Cavity Concept for Improving the Off-Design Performance of Fixed-Geometry Exhaust Nozzles

An investigation was conducted in the model preparation area of the Langley 16-Foot Transonic Tunnel to study a passive cavity concept for improving the off-design performance of fixed-geometry exhaust nozzles. Passive cavity ventilation (through a porous surface) was applied to divergent flap surfaces and tested at static conditions in a sub-scale, nonaxisymmetric, convergent-divergent nozzle. As part of a comprehensive investigation, force, moment and pressure measurements were taken and focusing schlieren flow visualization was obtained for a baseline configuration and D passive cavity configurations. All tests were conducted with no external flow and high-pressure air was used to simulate jet-exhaust flow at nozzle pressure ratios from 1.25 to approximately 9.50. Results indicate that baseline nozzle performance was dominated by unstable shock-induced boundary-layer separation at off-design conditions, which came about through the natural tendency of overexpanded exhaust flow to satisfy conservation requirements by detaching from the nozzle divergent flaps. Passive cavity ventilation added the ability to control off-design separation in the nozzle by either alleviating separation or encouraging stable separation of the exhaust flow. Separation alleviation offers potential for installed nozzle performance benefits by reducing drag at forward flight speeds, even though it may reduce off-design static thrust efficiency as much as 3.2 percent. Encouraging stable separation of the exhaust flow offers significant performance improvements at static, low NPR and low Mach number flight conditions by improving off-design static thrust efficiency as much as 2.8 percent. By designing a fixed-geometry nozzle with fully porous divergent flaps, where both cavity location and percent open porosity of the flaps could be varied, passive flow control would make it possible to improve off-design nozzle performance across a wide operating range. In addition, the ability to encourage separation on one flap while alleviating it on the other makes it possible to generate thrust vectoring in the nozzle through passive flow control.

Asbury, Scott C.↗
NASA NTRS2003

Nitric Oxide Signaling in Hypergravity-Induced Neuronal Plasticity

The goal of this research project was to identify the neurons and circuits in the vestibular nuclei and nucleus prepositus hypoglossi that utilize nitric oxide (NO) for intercellular signaling during gravity-induced plasticity. This objective was pursued using histochemical and immunocytochemical approaches to localize NO-producing neurons and characterize the fine morphology of the cells in ground-based studies of normal rats, rats adapted to hypergravity, and rats adapted to hypergravity and then re-adapted to the 1G environment. NO-producing neurons were identified and studied using four methodologies: i) immunocytochemistry employing polyclonal antibodies directed against neuronal nitric oxide synthase (nNOS), to provide an indication of the capacity of a cell for NO production; ii) immunocytochemistry employing a monoclonal antibody directed against L-citrulline, to provide an indirect index of the enzyme's activity; iii) histochemistry based on the NADPH-diaphorase reaction, for fuI1 cytological visualization of neurons; and iv) double immunofluorescence to co-localize nNOS and L-citrulline in individual vestibular nuclei (VN) and neurons.

Holstein, Gay R.↗