The relationship between polar magnetic activity DP and growth of the geomagnetic ring current.
Polar magnetic disturbance activity and geomagnetic ring current growth relation noting small time lag
Davis, T. N.↗
SEARCH · Engineering Papers
Results for “activity relationship”
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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Relation between monthly variations of global ozone and solar activity
Monthly averaged variations of global ozone determined from infrared interferometer spectrometer measurements aboard Nimbus 4 are shown to be consistently in agreement with monthly averaged variations of solar activity. The relationship between monthly changes of ozone and solar activity are found to be generally consistent with the longer-term variations of ozone over the last solar cycle and can be accounted for by assuming monthly solar flux variations near 0.2 micron of about 2%.
Keating, G. M.↗
On the relationship between early solar activity and the evolution of terrestrial planet atmospheres
Mass fractionation during hydrodynamic escape of hydrogen-rich primordial atmospheres form Venus, earth, and Mars can account for most of the salient features of mass distributions in their present-day atmospheres. The principal assumptions and results of an escape-fractionation model for the evolution of terrestrial planet atmospheres from primary to final states are qualitatively described, with emphasis on the astrophysical conditions needed to enable the loss process. A substantial and rapidly declining flux of energetic solar radiation into atmospheric exospheres is required, initially (at solar ages of about 1-10 million years) two to three orders of magnitude more intense than that supplied by extreme-ultraviolet emission from the contemporary sun. The solar accretion disk must have dissipated if such radiation is to penetrate the system midplane to planetray distances. On both criteria, hydrodynamic escape from planets appears plausible in the astrophysical environment of the naked T-Tauri stars.
Repin, Robert O.↗
The relationship between star formation activity and galaxy structural properties in CANDELS and a semi-analytic model
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Ryan Brennan↗
The sun as a star - 1982 June 14-August 13
During a 60-day period in the summer of 1982, a joint observing project between the High Altitude Observatory and the University of Hawaii was undertaken to collect a set of solar photospheric, chromospheric, and coronal data. From these data, the relationships between quantities recognized to be related to solar activity are specified. The amplitude of rotational modulation of the diagnostic parameters derived for the full disk was approximately equal to the modulation observed over an entire solar cycle. Those integrated solar data have been used as diagnostics of generalized stellar activity. A relationship between the Ca II line K flux and total inferred coronal mass of the sun existed during this observation period, and this fact leads to the hypothesis that ca II flux modulation in other stars may be used to infer stellar coronal conditions.
Fisher, R.↗
Relationship Between Ecosystem Productivity and Photosynthetically Active Radiation for Northern Peatlands
We analyzed the relationship between net ecosystem exchange of carbon dioxide (NEE) and irradiance (as photosynthetic photon flux density or PPFD), using published and unpublished data that have been collected during midgrowing season for carbon balance studies at seven peatlands in North America and Europe, NEE measurements included both eddy-correlation tower and clear, static chamber methods, which gave very similar results. Data were analyzed by site, as aggregated data sets by peatland type (bog, poor fen, rich fen, and all fens) and as a single aggregated data set for all peatlands. In all cases, a fit with a rectangular hyperbola (NEE = alpha PPFD P(sub max)/(alpha PPFD + P(sub max) + R) better described the NEE-PPFD relationship than did a linear fit (NEE = beta PPFD + R). Poor and rich fens generally had similar NEE-PPFD relationships, while bogs had lower respiration rates (R = -2.0 micro mol m(exp -2) s(exp -1) for bogs and -2.7 micro mol m(exp -2) s(exp -1)) for fens) and lower NEE at moderate and high light levels (P(sub max)= 5.2 micro mol m(exp -2) s(exp -1) for bogs and 10.8 micro mol m(exp -2) s(exp -1) for fens). As a single class, northern peatlands had much smaller ecosystem respiration (R = -2.4 micro mol m(exp -2) s(exp -1)) and NEE rates (alpha = 0.020 and P(sub max)= 9.2 micro mol m(exp -2) s(exp -1)) than the upland ecosystems (closed canopy forest, grassland, and cropland). Despite this low productivity, northern peatland soil carbon pools are generally 5-50 times larger than upland ecosystems because of slow rates of decomposition caused by litter quality and anaerobic, cold soils.
Frolking, S. E.↗
Lymphocyte Functions in Microgravity
To understand the mechanism of immunity impairment in space it is important to analyze the direct effects of space-related conditions on different lymphocytes functions. Since 1992, we are investigating the effect of modeled and true microgravity (MG) on numerous lymphocyte functions. We had shown that modeled (MMG) and true microgravity inhibit lymphocyte locomotion through type I collagen. Modeled microgravity also suppresses polyclonal and antigen-specific lymphocyte activation. Polyclonal activation of lymphocytes prior to exposure to MMG abrogates the MG-induced inhibition of lymphocyte locomotion. The relationship between activation deficits and the loss of locomotion in MG was investigated using PKC activation by phorbol ester (PMA) and calcium ionophore (ionomycin). Direct activation of PKC by PMA substantially restored the MMG-inhibited lymphocyte locomotion and PHA-induced lymphocyte activation lonomycin by itself did not restore either locomotion or activation of the lymphocytes, indicating that these changes are not related to the impairment in the calcium flux in MMG. Treatment of lymphocytes with PMA before exposure to MMG prevented the loss of locomotion. It was observed that DNA synthesis is not necessary for restoration of locomotion since mitomicin C treated and untreated cells recovered their locomotion to the same level after PKC activation. Our recent data indicate that microgravity may selectively effect the expression of novel Ca2+ independent isoforms of PKC, in particularly PKC sigma and delta. This provides a new insight in understanding of the mechanisms of MG-sensitive cellular functions.
Pellis, Neal R.↗
Summary of the workshop on active galaxies and quasars
The paper reports highlights of discussions carried out at the Tenth Texas Symposium on Relativistic Astrophysics concerning BL Lacertae objects and quasars and their relationship to active galactic nuclei. The discussions considered X-ray, optical and radio observations of active galaxies and quasars showing features which may be interpreted as jets or beams, and X-ray and VLBI observations of core-jet structures exhibiting apparent supraluminal expansion. Attention was also given to the properties of the energy source in the center of the active galaxies and quasars, the nature of quasar emission line regions, the production of the continuum in quasars and active galactic nuclei, and evidence for the association of quasars and BL Lac objects with galaxies.
Weistrop, D.↗
Intramolecular activation of a Ca(2+)-dependent protein kinase is disrupted by insertions in the tether that connects the calmodulin-like domain to the kinase
Ca(2+)-dependent protein kinases (CDPK) have a calmodulin-like domain (CaM-LD) tethered to the C-terminal end of the kinase. Activation is proposed to involve intramolecular binding of the CaM-LD to a junction sequence that connects the CaM-LD to the kinase domain. Consistent with this model, a truncated CDPK (DeltaNC) in which the CaM-LD has been deleted can be activated in a bimolecular interaction with an isolated CaM-LD or calmodulin, similar to the activation of a calmodulin-dependent protein kinase (CaMK) by calmodulin. Here we provide genetic evidence that this bimolecular activation requires a nine-residue binding segment from F436 to I444 (numbers correspond to CPK-1 accession number L14771). Two mutations at either end of this core segment (F436/A and VI444/AA) severely disrupted bimolecular activation, whereas flanking mutations had only minor effects. Intramolecular activation of a full-length kinase was also disrupted by a VI444/AA mutation, but surprisingly not by a F436/A mutation (at the N-terminal end of the binding site). Interestingly, intramolecular but not bimolecular activation was disrupted by insertion mutations placed immediately downstream of I444. To show that mutant enzymes were not misfolded, latent kinase activity was stimulated through binding of an antijunction antibody. Results here support a model of intramolecular activation in which the tether (A445 to G455) that connects the CaM-LD to the kinase provides an important structural constraint and is not just a simple flexible connection.
NASA Discipline Plant Biology↗
Seasonal variation of the 11 year solar cycle effect on the middle atmosphere: Role of the quasi biennial oscillation
Before the introduction of the Quasi Biennial Oscillation (Q.B.O.) in the study of the solar atmosphere relationship by Labitzke (1987) and Labitzke and Van Loon (1988), the only region of the atmosphere where an effect of a change in solar activity was generally admitted was the mesosphere. The response of the mesosphere, in phase with the solar activity, was found to be about one order of magnitude above model expectancy (around 10 to 20 Kelvin). It was observed independently of the season and maximized around 70 km (Chanin et al. 1987). However, from the same study, it was shown that the response of the stratosphere of opposite sign, clearly seen during winter and autumn, was at the threshold of detection in spring and summer. In the stratosphere, it was shown later that the separation of the data taking into account the sign of the Q.B.O. amplifies the negative correlation of the stratospheric temperature with solar activity in winter; it then becomes more significantly negative for the East phase of the Q.B.O. than when the data are all mixed (Labitzke and Chanin 1988). The studies of the seasonal response of the atmosphere to solar effect is crucial to understand the possible mechanism responsible of such a solar activity Q.B.O. relationship, knowing that the global dynamic circulation is quite different according to the seasons. The question is examined as to whether such separation of the data according to the phase of the Q.B.O. has any impact on the solar response of the middle atmosphere for seasons other than winter.
Keckhut, P.↗
Torsional Eye Movements Evoked by Unilateral Labyrinthine Galvanic Polarizations in the Squirrel Monkey
Electrical stimulation of vestibular-nerve afferents innervating the semicircular canals has been used to identify the extraocular muscles receiving activation or inhibition by individual ampullary nerves. This technique was originally developed by Szentagothai (1950) and led to the description of three neuron reflex arcs that connect each semicircular canal through an interneuron traversing in the region of the medial longitudinal fasciculus to one ipsilateral and one contralateral eye muscle. Selective ampullary nerve stimulation was subsequently used by Cohen and colleagues (Cohen and Suzuki, 1963; Cohen et al., 1964; Suzuki et al., 1964; Cohen et al., 1966) to study movements of the eyes and activation of individual extraocular muscles in response to stimulation of combinations of ampullary nerves. This work led to a description of the now familiar relationships between activation of a semicircular canal ampullary nerves and the anticipated movement in each eye. Disconjugacy of eye movements induced by individual vertical canal stimulation and dependence of the pulling direction of vertical recti and oblique muscles on eye position were also defined in these experiments. Subsequent studies have defined the mechanisms by which externally applied galvanic currents result in a change in vestibular-nerve afferent discharge. The currents appear to act at the spike trigger site. Perilymphatic cathodal currents depolarize the trigger site and lead to excitation whereas anodal currents hyperpolarize and result in inhibition. Afferents innervating all five vestibular endorgans appear to be affected equally by the currents (Goldberg et al., 1984). Irregularly discharging afferents are about 5-10 times more sensitive than regularly discharging ones because of the steeper slope of the former's faster postspike recovery of excitability in encoder sensitivity (Smith and Goldberg, 1986). Response adaptation similar to that noted during acceleration steps is apparent for longer periods of current administration. This adaptation is manifested as a perstimulus return toward resting discharge and poststimulus after-response in the opposite direction (Goldberg et al., 1984; Minor and Goldberg, l991). Cathodal currents (with respect to the perilymphatic space of the vestibule) are excitatory whereas anodal currents are inhibitory. Horizontal eye movements evoked by unilateral galvanic polarizations administered through chronically implanted labyrinthine stimulating electrodes have been studied in alert squirrel monkeys (Minor and Goldberg, 1991). We sought to extend this analysis by recording three-dimensional eye movements during galvanic stimulation. As predicted based upon roughly equal stimulation of ampullary nerves innervating the vertical canals, a substantial torsional component to the nystagmus is noted. The trajectory of torsional slow phases and nystagmus profile after the polarization provide insight into the central mechanisms that influence these responses.
Minor, Lloyd B.↗
Revisiting the Relationship between Atlantic Dust and Tropical Cyclone Activity using Aerosol Optical Depth Reanalyses: 2003-2018
Previous studies have noted a relationship between African dust and Atlantic tropical cyclone (TC) activity. However, due to the limitations of past dust analyses, the strength of this relationship remains uncertain. The emergence of aerosol reanalyses, including the Navy Aerosol Analysis and Prediction System (NAAPS) aerosol optical depth (AOD) reanalysis, NASA Modern-Era Retrospective analysis for Research and Applications, Version 2 (MERRA-2), and ECMWF Copernicus Atmosphere Monitoring Service reanalysis (CAMSRA), enables an investigation of the relationship between African dust and TC activity over the tropical Atlantic and Caribbean in a consistent temporal and spatial manner for 2003–2018. Although June–July–August (JJA) 550 nm dust AOD (DAOD) from all three reanalysis products correlates significantly over the tropical Atlantic and Caribbean, the difference in DAOD magnitude between products can be as large as 60 % over the Caribbean and 20 % over the tropical North Atlantic. Based on the three individual reanalyses, we have created an aerosol multi-reanalysis consensus (MRC). The MRC presents overall better root mean square error over the tropical Atlantic and Caribbean compared to individual reanalyses when verified with ground-based AErosol RObotic NETwork (AERONET) AOD measurements. Each of the three individual reanalyses and the MRC have significant negative correlations between JJA Caribbean DAOD and seasonal Atlantic accumulated cyclone energy (ACE), while the correlation between JJA tropical North Atlantic DAOD and seasonal ACE is weaker. Possible reasons for this regional difference are provided. A composite analysis of 3 high-JJA-Caribbean-DAOD years versus 3 low-JJA-Caribbean-DAOD years reveals large differences in overall Atlantic TC activity. We also show that JJA Caribbean DAOD is significantly correlated with large-scale fields associated with variability in interannual Atlantic TC activity including zonal wind shear, mid-level moisture, and sea surface temperature (SST), as well as the El Niño–Southern Oscillation (ENSO) and the Atlantic Meridional Mode (AMM), implying confounding effects of these factors on the dust–TC relationship. We find that seasonal Atlantic DAOD and the AMM, the leading mode of coupled Atlantic variability, are inversely related and intertwined in the dust–TC relationship. Overall, DAOD in both the tropical Atlantic and Caribbean is negatively correlated with Atlantic hurricane frequency and intensity, with stronger correlations in the Caribbean than farther east in the tropical North Atlantic.
Dust particles↗
Methodologies for building robust schedules
COMPASS is the name of a Computer Aided Scheduling System designed and built for NASA. COMPASS can be used to develop schedule of activities based upon the temporal relationships of the activities and their resource requirements. COMPASS uses this information, and guided by the user, develops precise start and stop times for the activities. In actual practice however, it is impossible to know with complete certainty what the actual durations of the scheduled activities will really be. The best that one can hope for is knowledge of the probability distribution for the durations. This paper investigates methodologies for using a scheduling tool like COMPASS that is based upon definite values for the resource requirements, while building schedules that remain valid in the face of the schedule execution perturbations. Representations for the schedules developed by these methodologies are presented, along with a discussion of the algorithm that could be used by a computer onboard a spacecraft to efficiently monitor and execute these schedules.
Dean, John H.↗
Design strategies and functionality of the Visual Interface for Virtual Interaction Development (VIVID) tool
Development of interactive virtual environments (VE) has typically consisted of three primary activities: model (object) development, model relationship tree development, and environment behavior definition and coding. The model and relationship tree development activities are accomplished with a variety of well-established graphic library (GL) based programs - most utilizing graphical user interfaces (GUI) with point-and-click interactions. Because of this GUI format, little programming expertise on the part of the developer is necessary to create the 3D graphical models or to establish interrelationships between the models. However, the third VE development activity, environment behavior definition and coding, has generally required the greatest amount of time and programmer expertise. Behaviors, characteristics, and interactions between objects and the user within a VE must be defined via command line C coding prior to rendering the environment scenes. In an effort to simplify this environment behavior definition phase for non-programmers, and to provide easy access to model and tree tools, a graphical interface and development tool has been created. The principal thrust of this research is to effect rapid development and prototyping of virtual environments. This presentation will discuss the 'Visual Interface for Virtual Interaction Development' (VIVID) tool; an X-Windows based system employing drop-down menus for user selection of program access, models, and trees, behavior editing, and code generation. Examples of these selection will be highlighted in this presentation, as will the currently available program interfaces. The functionality of this tool allows non-programming users access to all facets of VE development while providing experienced programmers with a collection of pre-coded behaviors. In conjunction with its existing, interfaces and predefined suite of behaviors, future development plans for VIVID will be described. These include incorporation of dual user virtual environment enhancements, tool expansion, and additional behaviors.
Nguyen, Lac↗
Relationship of peroxyacetyl nitrate to active and total odd nitrogen at northern high latitudes: influence of reservoir species on NOx and O3
Measurements of peroxyacetyl nitrate (PAN), NO, NO2, HNO3, NOy (total odd nitrogen), and O3 were made in the high-latitude troposphere over North America and Greenland (35 degrees to 82 degrees N) during the Arctic Boundary Layer Expedition (ABLE 3A) (July-August 1988) throughout 0-to 6-km altitudes. These data are analyzed to quantitatively describe the relationships between various odd nitrogen species and assess their significance to global tropospheric chemistry. In the free troposphere, PAN was as much as 25 times more abundant than NOx. PAN to NOx ratio increased with increasing altitude and latitude. PAN was found to be the single most abundant reactive nitrogen species in the free troposphere and constituted a major fraction of NOy, PAN to NOy ratios were about 0.1 in the boundary layer and increased to 0.4 in the free troposphere. A 2-D global photochemical model with C1-C3 hydrocarbon chemistry is used to compare model predictions with measured results. A sizable portion (approximately 50%) of the gaseous reactive nitrogen budget is unaccounted for, and unknown organic nitrates and pernitrates are expected to be present. Model calculations (August 1, 70 degrees N) show that a major fraction of the observed NOx (50 to 70% of median) may find its source in the available PAN reservoir. PAN and the unknown reservoir species may have the potential to control virtually the entire NOx availability of the high latitude troposphere. It is predicted that the summer NOx and O3 mixing ratios in the Arctic/sub-Arctic troposphere would be considerably lower in the absence of the ubiquitous PAN reservoir. Conversely, this PAN reservoir may be responsible for the observed temporal increase in tropospheric O3 at high latitudes.
NASA Center ARC↗
Relationship of the cosmic ray intensity to the magnetic activity and radio emission of the sun
Relationship of cosmic ray intensity to magnetic activity and radio emission of sun
RADIO EMISSION↗
Elastic model for crimped collagen fibrils
A physiologic constitutive expression is presented in algorithmic format for the nonlinear elastic response of wavy collagen fibrils found in soft connective tissues. The model is based on the observation that crimped fibrils in a fascicle have a three-dimensional structure at the micron scale that we approximate as a helical spring. The symmetry of this wave form allows the force/displacement relationship derived from Castigliano's theorem to be solved in closed form: all integrals become analytic. Model predictions are in good agreement with experimental observations for mitral-valve chordae tendinece.
Evaluation Studies↗
Active regions and the interplanetary magnetic field.
Solar active region relationship to large scale sector interplanetary field structure
Ness, N. F.↗