Search NASA⌕ Search

SEARCH · Search NASA

Results for “action potentials”

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 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

Water acidification aggravates lithium-induced toxicity represented by energy supply, oxidative stress, and cell fate in Daphnia magna neonates

Lithium is extensively utilized in industrial energy production, particularly in lithium-ion batteries, and in pharmaceuticals for the treating clinical mood disorders. Consequently, lithium is frequently detected in various environmental matrices. It has been reported to cause a range of toxic effects on aquatic organisms including oxidative stress, neurological disorders, and reproductive suppression. Water acidification is a global issue with numerous negative impacts on aquatic organisms. It can alter the physio-chemical properties and bioavailability of metal ions. The acidic leaching process during lithium battery treatment and global water acidification both suggest that lithium contamination often occurs in acidic environments. In the present study, Daphnia magna neonates were exposed to four treatments (control, lithium alone, low pH, and combined) to investigate whether an acidic environment exacerbates the toxic effects of lithium on aquatic organisms and to explore potential toxic action mechanisms. The results indicated that low pH posed a significant threat to the growth and reproduction of D. magna. When exposed to both lithium and low pH, there was increased lithium accumulation and an energy trade-off response, leading to increased energy allocation to reproduction and reduced energy for growth. Lithium exposure stimulated D. magna activity, while low pH inhibited it, suggesting that an imbalance in energy consumption and supply. Combined exposure to lithium and low pH resulted in severe oxidative stress due to mitochondrial dysfunction, under-utilization of energy substances, and increased ionic homeostasis disturbances. Consequently, the exposed organism altered apoptosis and autophagy processes to maintain homeostasis. In conclusion, the present study demonstrated that lithium and water acidification posed a population-level threat to D. magna, and their combined exposure significantly largely exacerbated the toxic effects.

63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTAN↗
DOE OSTI2023

Structural basis for severe pain caused by mutations in the S4-S5 linkers of voltage-gated sodium channel Na V 1.7

Gain-of-function mutations in voltage-gated sodium channel Na V 1.7 cause severe inherited pain syndromes, including inherited erythromelalgia (IEM). The structural basis of these disease mutations, however, remains elusive. Here, we focused on three mutations that all substitute threonine residues in the alpha-helical S4-S5 intracellular linker that connects the voltage sensor to the pore: Na V 1.7/I234T, Na V 1.7/I848T, and Na V 1.7/S241T in order of their positions in the amino acid sequence within the S4-S5 linkers. Introduction of these IEM mutations into the ancestral bacterial sodium channel Na V Ab recapitulated the pathogenic gain-of-function of these mutants by inducing a negative shift in the voltage dependence of activation and slowing the kinetics of inactivation. Remarkably, our structural analysis reveals a common mechanism of action among the three mutations, in which the mutant threonine residues create new hydrogen bonds between the S4-S5 linker and the pore-lining S5 or S6 segment in the pore module. Because the S4-S5 linkers couple voltage sensor movements to pore opening, these newly formed hydrogen bonds would stabilize the activated state substantially and thereby promote the 8 to 18 mV negative shift in the voltage dependence of activation that is characteristic of the Na V 1.7 IEM mutants. Our results provide key structural insights into how IEM mutations in the S4-S5 linkers may cause hyperexcitability of Na V 1.7 and lead to severe pain in this debilitating disease.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2025

Electrical signaling in fungi: past and present challenges

Abstract Electrical signaling is a fundamental mechanism for integrating environmental stimuli and coordinating responses in living organisms. While extensively studied in animals and plants, the role of electrical signaling in fungi remains a largely underexplored field. Early studies suggested that filamentous fungi generate action potential-like signals and electrical currents at hyphal tips, yet their function in intracellular communication remained unclear. Renewed interest in fungal electrical activity has fueled developments such as the hypothesis that mycorrhizal networks facilitate electrical communication between plants and the emerging field of fungal-based electronic materials. Given their continuous plasma membrane, specialized septal pores, and insulating cell wall structures, filamentous fungi possess architectural features that could support electrical signaling over long distances. However, studying electrical phenomena in fungal networks presents unique challenges due to the microscopic dimensions of hyphae, the structural complexity of highly modular mycelial networks, and the limitations of traditional electrophysiological methods. This review synthesizes current evidence for electrical signaling in filamentous fungi, evaluates methodological approaches, and highlights experimental challenges. By addressing these challenges and identifying best practices, we aim to advance research in this field and provide a foundation for future studies exploring the role of electrical signaling in fungal biology.

Buffi, Matteo↗
DOE OSTI2024

Comparative nutrient drawdown capacities of farmed kelps and implications of metabolic strategy and nutrient source

Abstract Seaweed aquaculture, particularly kelp farming, is a popular topic as a potential solution for mitigating anthropogenic pollutants and enhancing coastal drawdown of carbon and nitrogen. Using a common garden approach, this study evaluated nutrient drawdown capacities of Alaria marginata (ribbon kelp) and Saccharina latissima (sugar kelp) across four commercial kelp farms in Southeast and Southcentral Alaska. Our findings show that A. marginata exhibited ~30% more carbon and 21% more nitrogen content compared to S. latissima . These results demonstrate the potential for A. marginata to serve as a more efficient species for nutrient drawdown into farmed kelp tissues (per unit biomass) for consideration of potential mitigative actions. The efficacy of this drawdown is likely to be driven by the careful pairing of kelp species with farming environment. Temporally, there was a noted increase in carbon content and a decline in nitrogen content from March to May for both species, consistent with known seasonal nutrient dynamics in coastal waters. Notably, differences in the carbon stable isotope signatures (δ 13 C) between the kelps may hint at variations in metabolic pathways and nutrient sourcing, particularly concerning the preferential assimilation of CO 2 versus , and highlight the need for further work on this topic for applied macroalgal research.

Stephens, Tiffany↗
DOE OSTI2024

Translocation of Long-Term Captive Eastern Box Turtles and the Efficacy of Soft-Release: Implications for Turtle Confiscations

Translocation, the human mediated movement of organisms, is an important tool to conserve wildlife populations, and turtles are commonly subject to this management action. One potential source stock for turtle translocations are animals confiscated from the illegal wildlife trade or otherwise held in captivity. There is limited information, however, on the post-release behavior and survival of these animals. We monitored 26 translocated long-term captive (i.e., former pet) Eastern Box Turtles (Terrapene carolina carolina) to assess their survivorship, space use, and the effects of soft-release (penning) on site fidelity. We found long-term captives displayed high first-year survivorship (88.5–92.3%) and similar space use to resident turtles, and that soft-release was effective at reducing post-release movements. Furthermore, our study indicates long-term captive turtles may be suitable for release and provides insights for how confiscated turtles may best contribute to conservation.

60 APPLIED LIFE SCIENCES↗
DOE OSTI2025

Humate Amendment Injection Viability Testing – Supplementary Batch Mixture and Soil Column Studies

Groundwater in the Lost Lake Aquifer Zone (LLAZ) in the Southern Sector of the M-Area Hazardous Waste management Facility (HWMF) is contaminated with chlorinated ethenes, including trichloroethylene (TCE) and tetrachloroethylene (PCE). Treatment of contaminated groundwater with humic acid is being evaluated as a potential corrective action for these volatile organic compounds (VOCs) in the LLAZ in Southern Sector (SRNS, 2019). Pilot scale injections of Huma-K brand humic acid for groundwater treatment were previously performed in M-Area between 2017 and 2020 (Amidon, 2023). Groundwater was extracted from the Lost Lake Aquifer Zone (LLAZ), then a solution of humate was mixed with recovered groundwater and subsequently re-injected into the same aquifer unit. Operations of the historical humate pilot testing were discontinued in 2020 due to COVID-19 restrictions, low injection rates, and recirculation fluid spillage. No further field scale or laboratory research to investigate humate amended groundwater injection was performed at the SRS until 2024. At the request of Area Completion Projects (ACP), the Savannah River National Laboratory (SRNL) performed supplementary testing to help determine the viability of further injection of humate as a remedial option for VOCs within the LLAZ in the Southern Sector of the M-Area HWMF.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗
DOE OSTI2025

Recovery Simulator and Analysis Formulation: Mathematical Framework for Enhanced Resilience and Resource Allocation

This report introduces recovery simulator and analysis (RSA), a framework aimed at enhancing the resilience of electrical grids post-disruption. The RSA model leverages an optimization problem formulation that focuses on maximizing the load served (or optionally customers served) through a coordinated and cooptimized recovery of non-black start generation, transmission lines, feeders and substations subject to labor budget constraints. By integrating advanced linear programming techniques, the simulator selects efficient reocovery pathways, optimizing both short-term and long-term grid recovery strategies. The mathematical framework guides decision-making through a comprehensive evaluation of potential recovery actions, factoring in the trade-offs between labor constraints and load (or optionally customer) restoration efficacy. This enables grid operators to simulate diverse outage scenarios and delineate optimal recovery pathways, thereby prioritizing critical repair tasks and ensuring resource allocation is both economical and effective. The intended use case of RSA is to allow planners to explore many recovery scenarios quickly and determine assets most critical across a wide range of scenarios, and therefore strong candidates for hardening or additional investment. RSA might also be used in an operational setting, following a single event, for exploring efficient recovery pathways.

24 POWER TRANSMISSION AND DISTRIBUTION↗
NASA NTRS2001

An Overview of In-Stu Treatability Studies at Marshall Space Flight Center, Huntsville, Alabama

Marshall Space Flight Center (MSFC) is located in Huntsville, Alabama (north-central Alabama), on approximately 1,840 acres near the center of the U.S. Army's Redstone Arsenal (RSA). MSFC is the National Aeronautics and Space Administration's (NASA's) principal propulsion development center. Its scientists, engineers, and support personnel play a major role in the National Space Transportation System by managing space shuttle mission activities, including the microgravity laboratory. In addition, MSFC will be a significant contributor to several of NASA's future programs, including the Reusable Launch Vehicle (X-33), International Space Station, and Advanced X-ray Astrophysics Facility, as well as research on a variety of space science applications. MSFC has been used to develop, test and manufacture space vehicles and components since 1960, when civilian rocketry and missile activities were transferred from RSA to MSFC. In 1994, MSFC was placed on the National Priority List for the management of hazardous waste sites, under the requirements of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). One requirement of the CERCLA program is to evaluate the nature and extent of environmental contamination resulting from identified CERCLA sites, assess the public health and environmental risks associated with the identified contamination, and identify potential remedial actions. A CERCLA remedial investigation (RI) for the groundwater system has identified at least five major plumes of chlorinated volatile organic compounds (CVOCs) in the groundwater beneath the facility. These plumes are believed to be the result of former management practices at 14 main facility locations (termed "source areas") where CVOCs were released to the subsurface. Trichloroethene (TCE) is the predominant CVOC and is common to all the plumes. Perchloroethene (PCE) also exists in two of the plumes. In addition to TCE and PCE, carbon tetrachloride and 1,1,2,2-tetrachloroethane are contained in one of the plumes. The CVOCs are believed to exist as dense non-aqueous phase liquids (DNAPLs) beneath many of the source areas.

McElroy, Bill↗
NASA NTRS2002

Human Factors Process Task Analysis: Liquid Oxygen Pump Acceptance Test Procedure at the Advanced Technology Development Center

This viewgraph presentation provides information on Human Factors Process Failure Modes and Effects Analysis (HF PFMEA). HF PFMEA includes the following 10 steps: Describe mission; Define System; Identify human-machine; List human actions; Identify potential errors; Identify factors that effect error; Determine likelihood of error; Determine potential effects of errors; Evaluate risk; Generate solutions (manage error). The presentation also describes how this analysis was applied to a liquid oxygen pump acceptance test.

Diorio, Kimberly A.↗
NASA NTRS2003

Development of NASA Technical Standards Program Relative to Enhancing Engineering Capabilities

The enhancement of engineering capabilities is an important aspect of any organization; especially those engaged in aerospace development activities. Technical Standards are one of the key elements of this endeavor. The NASA Technical Standards Program was formed in 1997 in response to the NASA Administrator s directive to develop an Agencywide Technical Standards Program. The Program s principal objective involved the converting Center-unique technical standards into Agency wide standards and the adoption/endorsement of non-Government technical standards in lieu of government standards. In the process of these actions, the potential for further enhancement of the Agency s engineering capabilities was noted relative to value of being able to access Agencywide the necessary full-text technical standards, standards update notifications, and integration of lessons learned with technical standards, all available to the user from one Website. This was accomplished and is now being enhanced based on feedbacks from the Agency's engineering staff and supporting contractors. This paper addresses the development experiences with the NASA Technical Standards Program and the enhancement of the Agency's engineering capabilities provided by the Program s products. Metrics are provided on significant aspects of the Program.

Gill, Paul S.↗
NASA NTRS2003

Native Peoples-Native Homelands Climate Change Workshop: Lessons Learned

The Native Peoples-Native Homelands Climate Change Workshop was held on October 28 through November 01,1998, as part of a series of workshops being held around the U.S. to improve the understanding of the potential consequences of climate variability and change for the Nation. This workshop was specifically designed by Native Peoples to examine the impacts of climate change and extreme weather variability on Native Peoples and Native Homelands from an indigenous cultural and spiritual perspective and to develop recommendations as well as identify potential response actions. The workshop brought together interested Native Peoples, representatives of Tribal governments, traditional elders, Tribal leaders, natural resource managers, Tribal College faculty and students, and climate scientists fiom government agencies and universities. It is clear that Tribal colleges and universities play a unique and critical role in the success of these emerging partnerships for decision-making in addition to the important education function for both Native and non-Native communities such as serving as a culturally-appropriate vehicle for access, analysis, control, and protection of indigenous cultural and intellectual property. During the discussions between scientists and policy-makers from both Native and non-Native communities, a number of important lessons emerged which are key to building more effective partnerships between Native and non-Native communities for collaboration and decision-making for a more sustainable future. This talk summarizes the key issues, recommendations, and lessons learned during this workshop.

Maynard, Nancy G.↗
NASA NTRS2001

A model of cerebellar computations for dynamical state estimation

The cerebellum is a neural structure that is essential for agility in vertebrate movements. Its contribution to motor control appears to be due to a fundamental role in dynamical state estimation, which also underlies its role in various non-motor tasks. Single spikes in vestibular sensory neurons carry information about head state. We show how computations for optimal dynamical state estimation may be accomplished when signals are encoded in spikes. This provides a novel way to design dynamical state estimators, and a novel way to interpret the structure and function of the cerebellum.

NASA Discipline Neuroscience↗
NASA NTRS1993

Effects of microgravity on vestibular ontogeny: direct physiological and anatomical measurements following space flight (STS-29)

Does space flight change gravity receptor development? The present study measured vestibular form and function in birds flown as embryos for 5 days in earth orbit (STS-29). No major changes in vestibular gross morphology were found. Vestibular response mean amplitudes and latencies were unaffected by space flight. However, the results of measuring vestibular thresholds were mixed and abnormal responses in 3 of the 8 flight animals raise important questions.

NASA Discipline Neuroscience↗
NASA NTRS1997

Multiple subclasses of Purkinje cells in the primate floccular complex provide similar signals to guide learning in the vestibulo-ocular reflex

The neural "learning rules" governing the induction of plasticity in the cerebellum were analyzed by recording the patterns of neural activity in awake, behaving animals during stimuli that induce a form of cerebellum-dependent learning. We recorded the simple- and complex-spike responses of a broad sample of Purkinje cells in the floccular complex during a number of stimulus conditions that induce motor learning in the vestibulo-ocular reflex (VOR). Each subclass of Purkinje cells carried essentially the same information about required changes in the gain of the VOR. The correlation of simple-spike activity in Purkinje cells with activity in vestibular pathways could guide learning during low-frequency but not high-frequency stimuli. Climbing fiber activity could guide learning during all stimuli tested but only if compared with the activity present approximately 100 msec earlier in either vestibular pathways or Purkinje cells.

Non-NASA Center↗
NASA NTRS1999

Hoffmann-reflex is delayed during 6 degree head-down tilt with balanced traction

BACKGROUND: Increased spinal height due to the lack of of axial compression on spinal structures in microgravity may stretch the spinal cord, cauda equina, nerve roots, and paraspinal tissues. HYPOTHESIS: Exposure to simulated microgravity causes dysfunction of nerve roots so that the synaptic portion of the Achilles tendon reflex is delayed. METHODS: Six healthy male subjects were randomly divided into two groups with three in each group. The subjects in the first group underwent horizontal bed rest (HBR) for three days. After a two week interval they underwent bed rest in a position of head-down tilt with balanced traction (HDT). So that each subject could serve as his own control, the second group was treated identically but in opposite order. Bilateral F waves and H-reflexes were measured daily (18:30-20:30) on all subjects placed in a prone position. RESULTS: By means of ANOVA, differences between HDT and HBR were observed only in M-latency and F-ratio, not in F-latency, central latency, and H-latency. Differences during the course of the bed rest were observed in M-latency and H-latency only. Tibial H latency was significantly lengthened in HDT group on day 2 and 3, although no significant difference between HDT and HBR was observed. CONCLUSION: The monosynaptic reflex assessed by H-reflex was delayed during 6 degree HDT with traction. The exact mechanism of this delay and whether the change was due to lengthening of the lower part of the vertebrae remain to be clarified.

Randomized Controlled Trial↗
NASA NTRS1996

Noise and neuronal populations conspire to encode simple waveforms reliably

Sensory systems rely on populations of neurons to encode information transduced at the periphery into meaningful patterns of neuronal population activity. This transduction occurs in the presence of intrinsic neuronal noise. This is fortunate. The presence of noise allows more reliable encoding of the temporal structure present in the stimulus than would be possible in a noise-free environment. Simulations with a parallel model of signal processing at the auditory periphery have been used to explore the effects of noise and a neuronal population on the encoding of signal information. The results show that, for a given set of neuronal modeling parameters and stimulus amplitude, there is an optimal amount of noise for stimulus encoding with maximum fidelity.

Neurons/physiology↗