Search NASA⌕ Search

SEARCH · Search NASA

Results for “Loss function”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 199 records · Page 11
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

The extent of multiallelic, co‐editing of LIGULELESS1 in highly polyploid sugarcane tunes leaf inclination angle and enables selection of the ideotype for biomass yield

Summary Sugarcane ( Saccharum spp. hybrid) is a prime feedstock for commercial production of biofuel and table sugar. Optimizing canopy architecture for improved light capture has great potential for elevating biomass yield. LIGULELESS1 ( LG1 ) is involved in leaf ligule and auricle development in grasses. Here, we report CRISPR/Cas9‐mediated co‐mutagenesis of up to 40 copies/alleles of the putative LG1 in highly polyploid sugarcane (2 n = 100–120, x = 10–12). Next generation sequencing revealed co‐editing frequencies of 7.4%–100% of the LG1 reads in 16 of the 78 transgenic lines. LG1 mutations resulted in a tuneable leaf angle phenotype that became more upright as co‐editing frequency increased. Three lines with loss of function frequencies of ~12%, ~53% and ~95% of lg1 were selected following a randomized greenhouse trial and grown in replicated, multi‐row field plots. The co‐edited LG1 mutations were stably maintained in vegetative progenies and the extent of co‐editing remained constant in field tested lines L26 and L35. Next generation sequencing confirmed the absence of potential off targets. The leaf inclination angle corresponded to light transmission into the canopy and tiller number. Line L35 displaying loss of function in ~12% of the lg1 NGS reads exhibited an 18% increase in dry biomass yield supported by a 56% decrease in leaf inclination angle, a 31% increase in tiller number, and a 25% increase in internode number. The scalable co‐editing of LG1 in highly polyploid sugarcane allows fine‐tuning of leaf inclination angle, enabling the selection of the ideotype for biomass yield.

59 BASIC BIOLOGICAL SCIENCES↗
DOE OSTI2025

A Role for the Plastidial GPT2 Translocator in the Modulation of Lignin Biosynthesis

ABSTRACT Engineering plants with reduced lignin content can result in pleiotropic growth defects. In stems of Arabidopsis plants with reduced expression of hydroxycinnamoyl CoA: shikimate hydroxycinnamoyl transferase (HCT), the plastidial glucose 6‐phosphate: phosphate co‐transporter GPT2 is highly overexpressed, and this coincides with reduced lignin levels and extensive transcriptional and metabolic reprogramming. To explore the potential relationship between GPT2 expression and lignin accumulation, GPT2 transcript levels were evaluated in a suite ofArabidopsis thalianaandMedicago truncatulalignin‐defective lines. We also examined lignin levels and composition, and transcriptomic and metabolic profiles in GPT2 loss‐of‐function, GPT2 overexpression, and wild‐type Arabidopsis plants. Loss of GPT2 had no effect on lignin, but its overexpression caused a decrease in stem lignin levels due to reduced accumulation of both guaiacyl and syringyl lignins and their associated monolignol pools.HCTtranscript levels were diminished in 35S‐GPT2 lines, indicating a potential transcriptional regulatory connection between lignin biosynthesis and GPT2. Based on our transcriptomic and metabolomic analyses, we suggest that GPT2 operates to balance the flux between the biosynthesis of lignin and light‐protective phenylpropanoid derivatives.

Plant Sciences↗
NASA NTRS2003

Evaporation Loss of Light Elements as a Function of Cooling Rate: Logarithmic Law

Knowledge about the evaporation loss of light elements is important to our understanding of chondrule formation processes. The evaporative loss of light elements (such as B and Li) as a function of cooling rate is of special interest because recent investigations of the distribution of Li, Be and B in meteoritic chondrules have revealed that Li varies by 25 times, and B and Be varies by about 10 times. Therefore, if we can extrapolate and interpolate with confidence the evaporation loss of B and Li (and other light elements such as K, Na) at a wide range of cooling rates of interest based upon limited experimental data, we would be able to assess the full range of scenarios relating to chondrule formation processes. Here, we propose that evaporation loss of light elements as a function of cooling rate should obey the logarithmic law.

Xiong, Yong-Liang↗
NASA NTRS2019

Update: Antarctic Winterover as an Analog for Spaceflight Immune Dysregulation

Orbital spaceflight perturbs the human immune system significantly; Natural Killer (NK) and T-lymphocyte (T) cell functions are most susceptible to spaceflight-induced impairment. This loss of function may manifest in persistent latent virus reactivation (CMV, EBV, VZV), which does occur at a higher frequency in astronauts compared to earthlings.

Makedonas, George↗
NASA NTRS1999

Activation of the Saccharomyces cerevisiae filamentation/invasion pathway by osmotic stress in high-osmolarity glycogen pathway mutants

Mitogen-activated protein kinase (MAPK) cascades are frequently used signal transduction mechanisms in eukaryotes. Of the five MAPK cascades in Saccharomyces cerevisiae, the high-osmolarity glycerol response (HOG) pathway functions to sense and respond to hypertonic stress. We utilized a partial loss-of-function mutant in the HOG pathway, pbs2-3, in a high-copy suppressor screen to identify proteins that modulate growth on high-osmolarity media. Three high-copy suppressors of pbs2-3 osmosensitivity were identified: MSG5, CAK1, and TRX1. Msg5p is a dual-specificity phosphatase that was previously demonstrated to dephosphorylate MAPKs in yeast. Deletions of the putative MAPK targets of Msg5p revealed that kss1delta could suppress the osmosensitivity of pbs2-3. Kss1p is phosphorylated in response to hyperosmotic shock in a pbs2-3 strain, but not in a wild-type strain nor in a pbs2-3 strain overexpressing MSG5. Both TEC1 and FRE::lacZ expressions are activated in strains lacking a functional HOG pathway during osmotic stress in a filamentation/invasion-pathway-dependent manner. Additionally, the cellular projections formed by a pbs2-3 mutant on high osmolarity are absent in strains lacking KSS1 or STE7. These data suggest that the loss of filamentation/invasion pathway repression contributes to the HOG mutant phenotype.

Non-NASA Center↗
NASA NTRS2005

Electroporation System for Sterilizing Water

A prototype of an electroporation system for sterilizing wastewater or drinking water has been developed. In electroporation, applied electric fields cause transient and/or permanent changes in the porosities of living cells. Electroporation at lower field strengths can be exploited to increase the efficiency of chemical disinfection (as in chlorination). Electroporation at higher field strengths is capable of inactivating and even killing bacteria and other pathogens, without use of chemicals. Hence, electroporation is at least a partial alternative to chlorination. The transient changes that occur in micro-organisms at lower electric-field strengths include significantly increased uptake of ions and molecules. Such increased uptake makes it possible to achieve disinfection at lower doses of chemicals (e.g., chlorine or ozone) than would otherwise be needed. Lower doses translate to lower costs and reduced concentrations of such carcinogenic chemical byproducts as trichloromethane. Higher electric fields cause cell membranes to lose semipermeability and thereby become unable to function as selective osmotic barriers between the cells and the environment. This loss of function is the cause of the cell death at higher electric-field intensities. Experimental evidence does not indicate cell lysis but, rather, combined leaking of cell proteins out of the cells as well as invasion of foreign chemical compounds into the cells. The concept of electroporation is not new: it has been applied in molecular biology and genetic engineering for decades. However, the laboratory-scale electroporators used heretofore have been built around small (400-microliter) cuvettes, partly because the smallness facilitates the generation of electric fields of sufficient magnitude to cause electroporation. Moreover, most laboratory- scale electroporators have been designed for testing static water. In contrast, the treatment cell in the present system is much larger and features a flow-through geometry, such that electric fields strong enough to effect 99.9- percent disinfection can be applied to water flowing in a pipe.

Schlager, Kenneth J.↗
NASA NTRS2011

Reliability Impacts in Life Support Architecture and Technology Selection

Equivalent System Mass (ESM) and reliability estimates were performed for different life support architectures based primarily on International Space Station (ISS) technologies. The analysis was applied to a hypothetical 1-year deep-space mission. High-level fault trees were initially developed relating loss of life support functionality to the Loss of Crew (LOC) top event. System reliability was then expressed as the complement (nonoccurrence) this event and was increased through the addition of redundancy and spares, which added to the ESM. The reliability analysis assumed constant failure rates and used current projected values of the Mean Time Between Failures (MTBF) from an ISS database where available. Results were obtained showing the dependence of ESM on system reliability for each architecture. Although the analysis employed numerous simplifications and many of the input parameters are considered to have high uncertainty, the results strongly suggest that achieving necessary reliabilities for deep-space missions will add substantially to the life support system mass. As a point of reference, the reliability for a single-string architecture using the most regenerative combination of ISS technologies without unscheduled replacement spares was estimated to be less than 1%. The results also demonstrate how adding technologies in a serial manner to increase system closure forces the reliability of other life support technologies to increase in order to meet the system reliability requirement. This increase in reliability results in increased mass for multiple technologies through the need for additional spares. Alternative parallel architecture approaches and approaches with the potential to do more with less are discussed. The tall poles in life support ESM are also reexamined in light of estimated reliability impacts.

Lange, Kevin E.↗
DOE OSTI2024

The first intron and promoter of Arabidopsis DIACYLGLYCEROL ACYLTRANSFERASE 1 exert synergistic effects on pollen and embryo lipid accumulation

Summary Accumulation of triacylglycerols (TAGs) is crucial during various stages of plant development. In Arabidopsis , two enzymes share overlapping functions to produce TAGs, namely acyl‐CoA:diacylglycerol acyltransferase 1 (DGAT1) and phospholipid:diacylglycerol acyltransferase 1 (PDAT1). Loss of function of both genes in a dgat1‐1/pdat1‐2 double mutant is gametophyte lethal. However, the key regulatory elements controlling tissue‐specific expression of either gene has not yet been identified. We transformed a dgat1‐1/dgat1‐1//PDAT1/pdat1‐2 parent with transgenic constructs containing the Arabidopsis DGAT1 promoter fused to the AtDGAT1 open reading frame either with or without the first intron. Triple homozygous plants were obtained, however, in the absence of the DGAT1 first intron anthers fail to fill with pollen, seed yield is c . 10% of wild‐type, seed oil content remains reduced (similar to dgat1‐1/dgat1‐1 ), and non‐Mendelian segregation of the PDAT1/pdat1‐2 locus occurs. Whereas plants expressing the AtDGAT1pro:AtDGAT1 transgene containing the first intron mostly recover phenotypes to wild‐type. This study establishes that a combination of the promoter and first intron of AtDGAT1 provides the proper context for temporal and tissue‐specific expression of AtDGAT1 in pollen. Furthermore, we discuss possible mechanisms of intron mediated regulation and how regulatory elements can be used as genetic tools to functionally replace TAG biosynthetic enzymes in Arabidopsis .

McGuire, Sean T.↗
DOE OSTI2024

Targeted modulation of pennycress lipid droplet proteins impacts droplet morphology and seed oil content

SUMMARY Lipid droplets (LDs) are unusual organelles that have a phospholipid monolayer surface and a hydrophobic matrix. In oilseeds, this matrix is nearly always composed of triacylglycerols (TGs) for efficient storage of carbon and energy. Various proteins play a role in their assembly, stability and turnover, and even though the major structural oleosin proteins in seed LDs have been known for decades, the factors influencing LD formation and dynamics are still being uncovered mostly in the “model oilseed” Arabidopsis. Here we identified several key LD biogenesis proteins in the seeds of pennycress, a potential biofuel crop, that were correlated previously with seed oil content and characterized here for their participation in LD formation in transient expression assays and stable transgenics. One pennycress protein, the lipid droplet associated protein‐interacting protein (LDIP), was able to functionally complement the Arabidopsis ldip mutant, emphasizing the close conservation of lipid storage among these two Brassicas. Moreover, loss‐of‐function ldip mutants in pennycress exhibited increased seed oil content without compromising plant growth, raising the possibility that LDIP or other LD biogenesis factors may be suitable targets for improving yields in oilseed crops more broadly.

Guzha, Athanas↗
NASA NTRS1988

A self-injection locked, Q-switched, line-narrowed Ti:Al2O3 laser

Line-narrowing, Q-switched, and self-injection locking are studied independently and as a system. Line narrowing is shown both theoretically and experimentally to depend on the inverse square root of the pulse evolution time interval. Q switching of the Ti:Al2O3 laser is demonstrated and the laser output energy as a function of the Q-switch delay is investigated. Self-injection is demonstrated and the operation of the laser is explored as a function of loss and the Q-switch delay. Self-injection locking is demonstrated and the performance as a function of the Q-switch delay is determined.

Barnes, Norman P.↗
NASA NTRS1963

A Hypergeometric Mean Value

Generalization of hypergeometric mean value from hypergeometric function without loss of homogeneity - derivation and properties of hypergeometric mean value

HYPERGEOMETRIC FUNCTION↗
DOE OSTI2025

CalTestBed - Delphire - Testing and Evaluation of Delphire Sentinel System (CRADA Final Report)

The Delphire Sentinel is a modular fire detection and communications system operating as a mobile field unit, with low voltage DC power supplied by onboard photovoltaics (PV) and batteries. The Sentinel addresses several aspects of fire detection, communications and data analysis. The Sentinel's mobility enables it to be rapidly deployed and operate independently of existing power and communications networks. The duration of independent operation depends critically on the energy consumption of the systems and performance of the onboard PV and battery. The purpose of this testing is to ascertain the power draw and energy consumption of the Delphire Sentinel prototype system under several operational states, including various data transfer packet sizes, transmission time and frequencies, and communication pathways (Wi-Fi, cellular, satellite) expected to be encountered in field deployments. It will also include procedures to test the ability of the Sentinel to operate for extended periods without loss of functionality. Based on results from energy and power measurements, and anticipated duty cycles in field deployments, we will model annual system autonomy (e.g. loss of load probability) for off-grid operation in representative locations.

47 OTHER INSTRUMENTATION↗
NASA NTRS2001

ISS And Space Environment Interactions Without Operating Plasma Contactor

The International Space Station (ISS) will be the largest, highest power spacecraft placed in orbit. Because of this the design of the electrical power system diverged markedly from previous systems. The solar arrays will operate at 160 V and the power distribution voltage will be 120 V. The structure is grounded to the negative side of the solar arrays so under the right circumstances it is possible to drive the ISS potential very negative. A plasma contactor has been added to the ISS to provide control of the ISS structure potential relative to the ambient plasma. The ISS requirement is that the ISS structure not be greater than 40 V positive or negative of local plasma. What are the ramifications of operating large structures with such high voltage power systems? The application of a plasma contactor on ISS controls the potential between the structure and the local plasma, preventing degrading effects. It is conceivable that there can be situations where the plasma contactor might be non-functional. This might be due to lack of power, the need to turn it off during some of the build-up sequences, the loss of functionality for both plasma contactors before a replacement can be installed, similar circumstances. A study was undertaken to understand how important it is to have the contactor functioning and how long it might be off before unacceptable degradation to ISS could occur. The details of interaction effects on spacecraft have not been addressed until driven by design. This was true for ISS. If the structure is allowed to float highly negative impinging ions can sputter exposed conductors which can degrade the primary surface and also generate contamination due to the sputtered material. Arcing has been known to occur on solar arrays that float negative of the ambient plasma. This can also generate electromagnetic interference and voltage transients. Much of the ISS structure and pressure module surfaces exposed to space is anodized aluminum. The anodization thickness is very thin to provide the required solar absorptance and emittance. For conditions where ISS structure can charge negative a large percentage of the array voltage, the dielectric strength of this layer is low, and dielectric breakdown (arcing) can occur. The energy stored capacitively in the structure can be delivered to the arc. The mechanisms by which this energy is delivered and how much of the energy is available hasn't been fully quantified. Questions have been raised regarding the possibility of whether a sustained arc might result due to current collected by the solar arrays from local plasma. It was postulated that even if dielectric breakdown didn't occur, impacts due to micrometeoroids and space debris could penetrate thin layers of dielectric on ISS and initiate an arc due to the coupling provided by the dense local plasma produced by the impact. This was proven in experiments conducted jointly by MSFC and Auburn University. A target chamber with a simulated ionospheric plasma and a biased, anodized aluminum plate and a 1-microfarad capacitor was used. The plate was then impacted by 75-micron particles accelerated to orbital velocity. Arc discharges were sustained for higher voltages but a threshold appears below which no discharge was initiated. Most items without an exposed power system will float electrically near the local plasma potential. This is true of the Space Shuttle, an Astronaut on EVA, and similar items. The structure of ISS might be at a large negative voltage. Therefore, capacitively stored energy can be transferred during docking, installing external boxes and equipment and Astronaut contact with ISS structure. The circumstances of when this can happen and the resulting effects are evaluated in this study. Also, a crewmember on EVA might be in the vicinity of an arc. All safety aspects of such an encounter including charging, molten particles from the arc site and EMI have been evaluated. This paper will report on the total results of this study focussed on the 4A configuration, scheduled to be complete in November, 2000. Interactions such as arcing, debris induced arcs, sustained arcs, sputtering, contamination from sputtering and arcing, docking interactions and Astronaut safety issues will all be addressed.

Carruth, M. R., Jr.↗
NASA NTRS2000

ISS and Space Environment Interactions in Event of Plasma Contactor Failure

The International Space Station (ISS), illustrated in Figure 1, will be the largest, highest power spacecraft placed in orbit. Because of this the design of the electrical power system diverged markedly from previous systems. The solar arrays will operate at 160 V and the power distribution voltage will be 120 V. The structure is grounded to the negative side of the solar arrays so under the right circumstances it is possible to drive the ISS potential very negative. A plasma contactor has been added to the ISS to provide control of the ISS structure potential relative to the ambient plasma. The ISS requirement is that the ISS structure not be greater than 40 V positive or negative of local plasma. What are the ramifications of operating large structures with such high voltage power systems? The application of a plasma contactor on ISS controls the potential between the structure and the local plasma, preventing degrading effects. It is conceivable that there can be situations where the plasma contactor might be non-functional. This might be due to lack of power, the need to turn it off during some of the build-up sequences, the loss of functionality for both plasma contactors before a replacement can be installed, and similar circumstances. A study was undertaken to understand how important it is to have the contactor functioning and how long it might be off before unacceptable degradation to ISS could occur.

Carruth, M. R., Jr.↗
NASA NTRS2015

Smart Multifunctional Coatings for Corrosion Detection and Control in the Aerospace Industry

Nearly all metals and their alloys are subject to corrosion that causes them to lose their structural integrity or other critical functionality. It is essential to detect corrosion when it occurs, and preferably at its early stage, so that action can be taken to avoid structural damage or loss of function. Protective coatings are the most commonly used method of corrosion control. However, progressively stricter environmental regulations have resulted in the ban of many commercially available corrosion protective coatings due to the harmful effects of their solvents or corrosion inhibitors. This work concerns the development of a multifunctional, smart coating for the autonomous control of corrosion. This coating is being developed to have the inherent ability to detect the chemical changes associated with the onset of corrosion and respond autonomously to indicate it and control it.

Corrosion↗