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DOE OSTI2016

SUMOylation of KLF4 acts as a switch in transcriptional programs that control VSMC proliferation

The regulation of vascular smooth muscle cell (VSMC) proliferation is an important issue due to its major implications for the prevention of pathological vascular conditions. The objective of this work was to assess the function of small ubiquitin-like modifier (SUMO)ylated Krϋppel-like transcription factor 4 (KLF4) in the regulation of VSMC proliferation in cultured cells and in animal models with balloon injury. We found that under basal conditions, binding of non-SUMOylated KLF4 to p300 activated p21 (p21{sup WAF1/CIP1})transcription, leading to VSMC growth arrest. PDGF-BB promoted the interaction between Ubc9 and KLF4 and the SUMOylation of KLF4, which in turn recruited transcriptional corepressors to the p21 promoter. The reduction in p21 enhanced VSMC proliferation. Additionally, the SUMOylated KLF4 did not affect the expression of KLF4, thereby forming a positive feedback loop enhancing cell proliferation. These results demonstrated that SUMOylated KLF4 plays an important role in cell proliferation by reversing the transactivation action of KLF4 on p21 induced with PDGF-BB.

60 APPLIED LIFE SCIENCES↗

NASA NTRS1985

Accelerated stress testing of thin film solar cells: Development of test methods and preliminary results

If thin film cells are to be considered a viable option for terrestrial power generation their reliability attributes will need to be explored and confidence in their stability obtained through accelerated testing. Development of a thin film accelerated test program will be more difficult than was the case for crystalline cells because of the monolithic construction nature of the cells. Specially constructed test samples will need to be fabricated, requiring committment to the concept of accelerated testing by the manufacturers. A new test schedule appropriate to thin film cells will need to be developed which will be different from that used in connection with crystalline cells. Preliminary work has been started to seek thin film schedule variations to two of the simplest tests: unbiased temperature and unbiased temperature humidity. Still to be examined are tests which involve the passage of current during temperature and/or humidity stress, either by biasing in the forward (or reverse) directions or by the application of light during stress. Investigation of these current (voltage) accelerated tests will involve development of methods of reliably contacting the thin conductive films during stress.

Lathrop, J. W.↗

NASA NTRS2003

Developmental gene regulatory network architecture across 500 million years of echinoderm evolution

Evolutionary change in morphological features must depend on architectural reorganization of developmental gene regulatory networks (GRNs), just as true conservation of morphological features must imply retention of ancestral developmental GRN features. Key elements of the provisional GRN for embryonic endomesoderm development in the sea urchin are here compared with those operating in embryos of a distantly related echinoderm, a starfish. These animals diverged from their common ancestor 520-480 million years ago. Their endomesodermal fate maps are similar, except that sea urchins generate a skeletogenic cell lineage that produces a prominent skeleton lacking entirely in starfish larvae. A relevant set of regulatory genes was isolated from the starfish Asterina miniata, their expression patterns determined, and effects on the other genes of perturbing the expression of each were demonstrated. A three-gene feedback loop that is a fundamental feature of the sea urchin GRN for endoderm specification is found in almost identical form in the starfish: a detailed element of GRN architecture has been retained since the Cambrian Period in both echinoderm lineages. The significance of this retention is highlighted by the observation of numerous specific differences in the GRN connections as well. A regulatory gene used to drive skeletogenesis in the sea urchin is used entirely differently in the starfish, where it responds to endomesodermal inputs that do not affect it in the sea urchin embryo. Evolutionary changes in the GRNs since divergence are limited sharply to certain cis-regulatory elements, whereas others have persisted unaltered.

NASA Program Fundamental Space Biology↗

DOE OSTI2021

Explaining and predicting human behavior and social dynamics in simulated virtual worlds: reproducibility, generalizability, and robustness of causal discovery methods

Ground Truth program was designed to evaluate social science modeling approaches using simulation test beds with ground truth intentionally and systematically embedded to understand and model complex Human Domain systems and their dynamics Lazer et al. (Science 369:1060–1062, 2020). Our multidisciplinary team of data scientists, statisticians, experts in Artificial Intelligence (AI) and visual analytics had a unique role on the program to investigate accuracy, reproducibility, generalizability, and robustness of the state-of-the-art (SOTA) causal structure learning approaches applied to fully observed and sampled simulated data across virtual worlds. In addition, we analyzed the feasibility of using machine learning models to predict future social behavior with and without causal knowledge explicitly embedded. In this paper, we first present our causal modeling approach to discover the causal structure of four virtual worlds produced by the simulation teams—Urban Life, Financial Governance, Disaster and Geopolitical Conflict. Our approach adapts the state-of-the-art causal discovery (including ensemble models), machine learning, data analytics, and visualization techniques to allow a human-machine team to reverse-engineer the true causal relations from sampled and fully observed data. We next present our reproducibility analysis of two research methods team’s performance using a range of causal discovery models applied to both sampled and fully observed data, and analyze their effectiveness and limitations. We further investigate the generalizability and robustness to sampling of the SOTA causal discovery approaches on additional simulated datasets with known ground truth. Our results reveal the limitations of existing causal modeling approaches when applied to large-scale, noisy, high-dimensional data with unobserved variables and unknown relationships between them. We show that the SOTA causal models explored in our experiments are not designed to take advantage from vasts amounts of data and have difficulty recovering ground truth when latent confounders are present; they do not generalize well across simulation scenarios and are not robust to sampling; they are vulnerable to data and modeling assumptions, and therefore, the results are hard to reproduce. Finally, when we outline lessons learned and provide recommendations to improve models for causal discovery and prediction of human social behavior from observational data, we highlight the importance of learning data to knowledge representations or transformations to improve causal discovery and describe the benefit of causal feature selection for predictive and prescriptive modeling.

97 MATHEMATICS AND COMPUTING↗

NASA NTRS1983

The use of thematic mapper data for land cover discrimination: Preliminary results from the UK SATMaP programme

The principal objectives of the UK SATMaP program are to determine thematic mapper (TM) performance with particular reference to spatial resolution properties and geometric characteristics of the data. So far, analysis is restricted to images from the U.S. and concentrates on spectra and radiometric properties. The results indicate that the data are inherently three dimensional compared with the two dimensional character of MSS data. Preliminary classification results indicate the importance of the near infrared band (TM 4), at least one middle infrared band (TM 5 or TM 6) and at least one of the visible bands (preferably either TM 3 or TM 1). The thermal infrared also appears to have discriminatory ability despite its coarser spatial resolution. For band 4 the forward and reverse scans show somewhat different spectral responses in one scene but this effect is absent in the other analyzed. From examination of the histograms it would appear that the full 8-bit quantization is not being effectively utilized for all the bands.

Jackson, M. J.↗

NASA NTRS1985

The Use of Thematic Mapper Data for Land Cover Discrimination: Preliminary Results from the UK Satmap Programme

The principal objectives of the UK SATMaP program are to determine thematic mapper (TM) performance with particular reference to spatial resolution properties and geometric characteristics of the data. So far, analysis is restricted to images from the U.S. and concentrates on spectra and radiometric properties. The results indicate that the data are inherently three dimensional compared with the two dimensional character of MSS data. Preliminary classification results indicate the importance of the near infrared band (TM 4), at least one middle infrared band (TM 5 or TM 6) and at least one of the visible bands (preferably either TM 3 or TM 1). The thermal infrared also appears to have discriminatory ability despite its coarser spatial resolution. For band 4 the forward and reverse scans show somewhat different spectral responses in one scene but this effect is absent in the other analyzed. From examination of the histograms it would appear that the full 8 bit quantization is not being effectively utilized for all the bands.

Jackson, M. J.↗

DOE OSTI2016

Lifetime Extension Report: Progress on the SAVY-4000 Lifetime Extension Program

The 3-year accelerated aging study of the SAVY-4000 O-ring shows very little evidence of significant degradation to samples subjected to aggressive elevated temperature and radiation conditions. Whole container thermal aging studies followed by helium leakage testing and compression set measurements were used to establish an estimate for a failure criterion for O-ring compression set of ≥65 %. The whole container aging studies further show that the air flow and efficiency functions of the filter do not degrade significantly after thermal aging. However, the degradation of the water-resistant function leads to water penetration failure after four months at 210°C, but does not cause failure after 10 months at 120°C (130°C is the maximum operating temperature for the PTFE membrane). The thermal aging data for O-ring compression set do not meet the assumptions of standard time-temperature superposition analysis for accelerated aging studies. Instead, the data suggest that multiple degradation mechanisms are operative, with a reversible mechanism operative at low aging temperatures and an irreversible mechanism dominating at high aging temperatures. To distinguish between these mechanisms, we have measured compression set after allowing the sample to physically relax, thereby minimizing the effect of the reversible mechanism. The resulting data were analyzed using two distinct mathematical methods to obtain a lifetime estimate based on chemical degradation alone. Both methods support a lifetime estimate of greater than 150 years at 80°C. Although the role of the reversible mechanism is not fully understood, it is clear that the contribution to the total compression set is small in comparison to that due to the chemical degradation mechanism. To better understand the chemical degradation mechanism, thermally aged O-ring samples have been characterized by Fourier Transform Infrared (FTIR), Electron Paramagnetic Resonance (EPR), Gel Permeation Chromatography (GPC), and Differential Scanning Calorimetry (DSC). These experiments detect no significant O-ring degradation below 80°C. Furthermore, durometer measurements indicate that there is no significant change in O-ring hardness at all aging conditions examined. Therefore, our current conservative lifetime estimate for the O-ring and the filter is 10 years at 80°C. In FY17, we will continue to probe the chemical degradation mechanism using oxygen consumption measurements under accelerated aging conditions to reveal temperatures at which oxidation occurs, along with any differences in oxidation rate at the low vs. high aging temperatures. We will also refine the failure criteria and finalize the radiation/thermal synergistic studies to determine a final design lifetime.

42 ENGINEERING↗

DOE OSTI2018

Energy-efficient resin wafer electrodeionization for impaired water reclamation

Explore the source record for details and available documents.

water desalination, electrodeionization, imparied ↗

NASA NTRS1987

On the nature and origin of the calcium asymmetry arising during gravitropic response in etiolated pea epicotyls

Seven day old etiolated pea epicotyls were loaded symmetrically with 3H-indole 3-acetic acid (IAA) or 45Ca2+, then subjected to 1.5 hours of 1g gravistimulation. Epidermal peels taken from top and bottom surfaces after 90 minutes showed an increase in IAA on the lower side and of Ca2+ on the upper side. Inhibitors of IAA movement (TIBA, 9-hydroxyfluorene carboxylic acid) block the development of both IAA and Ca2+ asymmetries, but substances known to interfere with normal Ca2+ transport (nitrendipine, nisoldipine, Bay K 8644, A 23187) do not significantly alter either IAA or Ca2+ asymmetries. These substances, however, are active in modifying both Ca2+ uptake and efflux through oat and pea leaf protoplast membranes. We conclude that the 45Ca2+ fed to pea epicotyls occurs largely in the cell wall, and that auxin movement is primary and Ca2+ movement secondary in gravitropism. We hypothesize that apoplastic Ca2+ changes during graviresponse because it is displaced by H+ secreted through auxin-induced proton release. This proposed mechanism is supported by localized pH experiments, in which filter paper soaked in various buffers was applied to one side of a carborundum-abraded epicotyls. Buffer at pH 3 increases calcium loss from the side to which it is applied, whereas pH 7 buffer decreases it. Moreover, 10 micromolar IAA and 1 micromolar fusicoccin, which promote H+ efflux, increase Ca2+ release from pea epicotyl segments, whereas cycloheximide, which inhibits H+ efflux, has the reverse effect. We suggest that Ca2+ does not redistribute actively during gravitropism: the asymmetry arises because of its release from the wall adjacent to the region of high IAA concentration, proton secretion, and growth. Thus, the asymmetric distribution of Ca2+ appears to be a consequence of growth stimulation, not a critical step in the early phase of the graviresponse.

NASA Discipline Number 40-10↗

NASA NTRS1992

Measurement of Attachment-Line Location in a Wind-Tunnel and in Supersonic Flight

As a part of the supersonic laminar flow control research program, experiments are being conducted to measure the attachment-line flow characteristics and its location on a highly swept aircraft wing. Initially, subsonic wind tunnel tests were performed on two-dimensional models to develop sensors and techniques for the flight application. The wind tunnel test results suggest that, under certain conditions at the leading edge there are low frequency streamwise velocity fluctuations present in the laminar boundary layer which undergo a phase change at the stagnation point Therefore, if present in flight, this distinct change in phase, i.e., time shift of signals from either side of the stagnation point, can be used to determine the stagnation-line or attachment-line location. The phase-reversal phenomenon was examined to determine the attachment-line location on a highly swept wing. Test results indicate that the phase-reversal phenomenon may not be applicable in flight. Additional data analyses is continuing to account for phase differences introduced by the recording system. A final determination on the existence of phase-reversal in flight will require the results of further analysis and possibly additional flight testing. Some representative attachment-line data are presented and discussed as well as the results from the wind tunnel investigation.

Flight Testing↗

NASA NTRS1993

Up-down asymmetry of vertical optokinetic nystagmus and after-nystagmus elicited in microgravity

Vertical optokinetic nystagmus (OKN) and optokinetic after-nystagmus (OKAN) studied in 4 subjects during parabolic flights were compared with data obtained on 2 subjects before, during, and after a 7-day space shuttle flight. In parabolic flight, the vertical OKAN following upgoing optokinetic stimulation increased during the 0 g phase, and decreased during the 1.8 g phase. In spaceflight, the vertical OKN gain asymmetry showed a reversal during early exposure to microgravity. This asymmetry reversal is likely the same effect seen in parabolic flight and could be a direct response to the change in otolithic output. However, if asymmetry changes were due only to the otolithic sensory input, we would also expect large changes upon return to normal gravity. Instead, there were large OKN and OKAN changes at the beginning of the flight, but the deviation from the original vertical OKN gain asymmetry constantly decreased throughout the flight and continued post-flight until pre-flight asymmetry value was restored. This suggests one adaptive goal which reinstates the original pre-flight gain and asymmetry value regardless of changing inputs. This adaptation resembles mechanisms seen in posture experiments where the motor programs on Earth are reinstated in microgravity after a period of adjustment.

Clement, Gilles↗

NASA NTRS1997

Sensitivity of Runway Occupancy Time (ROT) to Various Rollout and Turnoff (ROTO) Factors: Complete Set of Plotted Data - Volume 2

The Terminal Area Productivity (TAP) research program was initiated by NASA to increase the airport capacity for transport aircraft operations. One element of the research program is called Low Visibility Landing and Surface Operations (LVLASO). A goal of the LVLASO research is to develop transport aircraft technologies which reduce Runway Occupancy Time (ROT) so that it does not become the limiting factor in the terminal area operations that determine the capacity of a runway. Under LVLASO, the objective of this study was to determine the sensitivity of ROT to various factors associated with the Rollout and Turnoff (ROTO) operation for transport aircraft. The following operational factors were studied and are listed in the order of decreasing ROT sensitivity: ice/flood runway surface condition, exit entrance ground speed, number of exits, high-speed exit locations and spacing, aircraft type, touchdown ground speed standard deviation, reverse thrust and braking method, accurate exit prediction capability, maximum reverse thrust availability, spiral-arc vs. circle-arc exit geometry, dry/slush/wet/snow runway surface condition, maximum allowed deceleration, auto asymmetric braking on exit, do not stow reverse thrust before the exit, touchdown longitudinal location standard deviation, flap setting, anti-skid efficiency, crosswind conditions, stopping on the exit and touchdown lateral offset.

Goldthorpe, S. H.↗

NASA NTRS1997

Sensitivity of Runway Occupancy Time (ROT) to Various Rollout and Turnoff (ROTO) Factors

Goldthorpe, S. H.↗

DOE OSTI2017

Using Modeling and Simulation to Complement Testing for Increased Understanding of Weapon Subassembly Response.

As part of Sandia’s nuclear deterrence mission, the B61-12 Life Extension Program (LEP) aims to modernize the aging weapon system. Modernization requires requalification and Sandia is using high performance computing to perform advanced computational simulations to better understand, evaluate, and verify weapon system performance in conjunction with limited physical testing. The Nose Bomb Subassembly (NBSA) of the B61-12 is responsible for producing a fuzing signal upon ground impact. The fuzing signal is dependent upon electromechanical impact sensors producing valid electrical fuzing signals at impact. Computer generated models were used to assess the timing between the impact sensor’s response to the deceleration of impact and damage to major components and system subassemblies. The modeling and simulation team worked alongside the physical test team to design a large-scale reverse ballistic test to not only assess system performance, but to also validate their computational models. The reverse ballistic test conducted at Sandia’s sled test facility sent a rocket sled with a representative target into a stationary B61-12 (NBSA) to characterize the nose crush and functional response of NBSA components. Data obtained from data recorders and high-speed photometrics were integrated with previously generated computer models in order to refine and validate the model’s ability to reliably simulate real-world effects. Large-scale tests are impractical to conduct for every single impact scenario. By creating reliable computer models, we can perform simulations that identify trends and produce estimates of outcomes over the entire range of required impact conditions. Sandia’s HPCs enable geometric resolution that was unachievable before, allowing for more fidelity and detail, and creating simulations that can provide insight to support evaluation of requirements and performance margins. As computing resources continue to improve, researchers at Sandia are hoping to improve these simulations so they provide increasingly credible analysis of the system response and performance over the full range of conditions.

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEF↗

NASA NTRSDate not supplied

Integrated laboratory, modeling and observational investigations of the condensation of benzene on Titan's stratospheric aerosols

Aerosols in Titan’s atmosphere play an important role in determining its thermal structure and can act as condensation nuclei for the formation of clouds. The global circulation of Titan’s atmosphere reversed within the two years following the northern spring equinox in August 2009, increasing the mixing ratios of benzene (C6H6) and other species at the South pole. A simultaneous strong cooling above the south pole (dropping temperatures below 120 K) resulted in conditions where molecules could condense at unusually high altitudes (>250 km). C6H6 and HCN ices have been detected by the Composite Infrared Spectrometer (CIRS) and the Visible and Infrared Mapping Spectrometer (VIMS), respectively, in the South polar cloud system, but the existing laboratory data is insufficient to allow models to reproduce the formation of the observed cloud system. We will present the preliminary results and the overall scope of a newly funded NASA SMD Cassini Data Analysis Program (CDAP) project which proposes to combine laboratory, modeling and observational studies to investigate the condensation of benzene on Titan’s aerosol as an important component of the cloud system that appeared during the autumn at 300 km above Titan’s South pole.

E. Sciamma-O’Brien↗

NASA NTRS1997

Cryogenics and the Human Exploration of Mars

Current plans within NASA involve extending the human exploration of space from low earth orbit into the solar system, with the first human exploration of Mars presently planned in 2011. Integral to all hum Mars mission phases is cryogenic fluid management. Cryogenic fluids will be required both as propellant and for In-Situ Resource Utilization (ISRU). Without safe and efficient cryogen storage human Mars missions will not be possible. Effective control and handling of cryogenic fluids is the key to affordable Mars missions, and advancing active thermal control technology is synergistic with all of NASA's exploration initiatives and with existing and future instrument cooling programs, including MTPE and Origins. Present mission scenarios for human exploration require cryogenic propellant storage for up to 1700 days and for up to 60 metric tons. These requirements represent increases of an order of magnitude over previous storage masses and lifetimes. The key cryogenic terminology areas to be addressed in human Mars missions are long-term propellant storage, cryogenic refrigeration, cryogenic liquefaction, and zero gravity fluid management. Long-term storage for the thermal control of cryogenic propellants is best accomplished with a mix of passive and active technologies. Passive technologies such as advanced multilayer insulation (MLI) concepts will be combined with the development of active coolers (cryogenic refrigerators). Candidates for long-life active cooling applications include Reverse Turbo-Brayton, Stirling, and Pulse-Tube coolers. The integration of passive and active technologies will form a hybrid system optimized to minimize the launch mass while preserving the cryogenic propellants. Since cryogenic propellants are the largest mass that Mars missions must launch from earth, even a modest reduction in the percentage of propellant carried results in a significant weight saving. This paper will present a brief overview of cryogenic fluid management technology as it applies to the current human Mars mission scenarios.

Salerno, Louis J.↗

NASA NTRS1985

Mutant Peas as Probes in the Understanding of Growth and Gravitropism

One mutant of Pism sativum CREEP grows normally up to the first internode stage, and then begins to grow plagiotropically. The upper internodes bend slowly downward according to a programmed sequence which follows circumnutation of the previous internode and opening of the previous leaves, but preceeds expansion of the previous leaves. The bending is partially inhibited by excission of the opposing stipules. The second mutant, AGEOTROPUM is gravitropically incompetant when grown etiolated, in the dark. When etiolated plants are illuminated with white light, the stems become gravitropically competant, but the roots do not. If the plants are grown in the light in particulate medium, some secondary roots, growing randomly, emerge into the air, and turn and grow downward toward moist soil. When etiolated AGEOTROPUM plants are illuminated, the shoots then become able to respond to gravity in a normal, negatively orthogravitropic manner. The response is to red light and is reversed by far red light. The mutation may involve one or more of the following: (1) release of sequestered calcium for redistribution; (2) radial transport of released calcium; or (3) net calcium flux in the upward direction.

Jaffe, M. J.↗

NASA NTRS1993

Plasma transport in the equatorial ionosphere during the great magnetic storm of March 1989

We have modeled plasma transport in the low-latitude and equatorial ionosphere during the great magnetic storm of March 1989. Our goal was to provide a consistent explanation for the DMSP (Defense Meteorological Satellite Program) observations of dramatic decreases in ion density and rapid ion drifts in the low latitude ionosphere over South America during the storm. The modeling effort supports the hypothesis that abnormally large upward drifts lifted F region plasma above the satellite's altitude and created the density depletions observed by DMSP. Modeled O(+) densities at the satellite's altitude have a strong qualitative resemblance to DMSP observations. Both the model and the observations indicate a deep density trough with extremely sharp boundaries surrounding the equator. The widths of both the modeled and the observed equatorial troughs increase with time. Vertical ion drifts predicted by the model also have been compared with DMSP measurements. Like the observed vertical drifts, the modeled drifts reversed sign near the trough boundaries. The modeled vertical drifts are of the same order and direction as the vertical component of E x B convection near the equator, but of opposite direction (downward) near the trough boundaries and outside of the trough.

Rasmussen, C. E.↗