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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS2017

Accuracy/Computation Performance of a New Trilateration Scheme for GPS-Style Localization

We recently introduced a new geometric trilateration (GT) method for GPS-style positioning. Preliminary singlepoint analysis using simplistic error assumptions indicates that the new scheme delivers almost indistinguishable localization accuracy as the traditional Newton-Raphson (NR) approach. Also, the same computation procedure can be used to perform high-accuracy relative positioning between a reference vehicle and an arbitrary number of target vehicles. This scheme has the potential to enable a) new mission concepts in collaborative science, b) in-situ navigation services for human Mars missions, and c) lower cost and faster acquisition of GPS signals for consumer-grade GPS products. The new GT scheme differs from the NR scheme as follows: 1. The new scheme is derived from Pythagoras Theorem, whereas the NR method is based on the principle of linear regression. 2. The NR method uses the absolute locations (xi, yi, zi)’s of the GPS satellites as input to each step of the localization computation. The GT method uses the Directional Cosines Ui’s from Earth’s center to the GPS satellite Si. 3. Both the NR method and the GT method iterate to converge to a localized solution. In each iteration step, multiple matrix operations are performed. The NR method constructs a different matrix in each iterative step, thus requires performing a new set of matrix operations in each step. The GT scheme uses the same matrix in each iteration, thus requiring computing the matrix operations only once for all subsequent iterations. In this paper, we perform an in-depth comparison between the GT scheme and the NR method in terms of a) GPS localization accuracy in the GPS operation environment, b) its sensitivity with respect to systematic errors and random errors, and c) computation load required to converge to a localization solution.

Lee, Charles↗
NASA NTRSDate not supplied

Increased Treadmill Running and Lower-Body Resistance Training Intensity May Attenuate Aerobic Capacity Loss During Spaceflight

BACKGROUND: In-flight exercise training is the primary countermeasure to mitigate spaceflight-induced decrements in strength and aerobic capacity. Despite high-quality exercise capabilities and prescriptions aboard the International Space Station (ISS), most astronauts experience strength and aerobic capacity loss; however, significant individual variability exists. Recent findings suggest that greater in-flight running (i.e., distance per session) and lower-body resistance exercise intensity (i.e., load relative to body weight) help preserve strength. Whether similar variables contribute to the preservation of aerobic capacity during spaceflight is unknown. METHODS: A NASA database of exercise performance metrics was used to identify long-duration (≥ 90 days) ISS crew who completed pre- and post-flight aerobic capacity testing (VO2peak, cycle ergometry, n = 44). “Responders” (R) were classified as those that maintained or improved VO2peak (n = 13; 1.4 ± 3.3%), and “non-responders” (NR) were those with the most severe decrements (n = 13; -20.0 ± 3.4%) from pre- to post-flight. In-flight exercise records (cycling, treadmill, resistance exercise) were aggregated across flight weeks. Independent t-tests or Mann-Whitney U tests were used to compare training variables (i.e., frequency, time, intensity, volume) between R and NR. RESULTS: Consistent with the variables contributing to strength protection, in-flight running distance (R: 5.0 ± 0.7; NR: 4.2 ± 1.0 km/session, p = 0.020) and lower-body resistance exercise intensity (R: 110.9 ± 27.3; NR: 91.7 ± 16.5% body weight, p = 0.040) were greater in R than NR. Active running time was also greater in R than NR (R: 101.1 ± 20.4; NR: 82.3 ± 23.5 min/wk; p = 0.039). However, no group differences in cycling frequency, intensity, or time, as well as upper body or core resistance exercise intensity, volume, or frequency were observed. CONCLUSIONS: Although physiologically distinct stimuli, the exercise training variables contributing to the preservation of both strength and aerobic capacity during microgravity exposure appear to be consistent. Increased running time and distance, but not cycling, combined with higher-intensity lower-body resistance exercise, may help mitigate losses in both aerobic capacity and strength during long-duration spaceflight.

Alyssa N Varanoske↗
NASA NTRS1989

Synthesis and degradation of nitrate reductase during the cell cycle of Chlorella sorokiniana

Studies on the diurnal variations of nitrate reductase (NR) activity during the life cycle of synchronized Chlorella sorokiniana cells grown with a 7:5 light-dark cycle showed that the NADH:NR activity, as well as the NR partial activities NADH:cytochrome c reductase and reduced methyl viologen:NR, closely paralleled the appearance and disappearance of NR protein as shown by sodium dodecyl sulfate gel electrophoresis and immunoblots. Results of pulse-labeling experiments with [35S]methionine further confirmed that diurnal variations of the enzyme activities can be entirely accounted for by the concomitant synthesis and degradation of the NR protein.

Non-NASA Center↗
NASA NTRS1985

Develop and demonstrate manufacturing processes for fabricating graphite filament reinforced polymide (Gr/PI) composite structural elements

A study was conducted to assess the merits of using graphite/polyimide, NR-150B2 resin, for structural applications on advanced space launch vehicles. The program was divided into two phases: (1) Fabrication Process Development; and (2) Demonstration Components. The first phase of the program involved the selection of a graphite fiber, quality assurance of the NR-150B2 polyimide resin, and the quality assurance of the graphite/polyimide prepreg. In the second phase of the program, a limited number of components were fabricated before the NR-150B2 resin system was removed from the market by the supplier, Du Pont. The advancement of the NR-150B2 polyimide resin binder was found to vary significantly based on previous time and temperature history during the prepregging operation. Strength retention at 316C (600F) was found to be 50% that of room temperature strength. However, the composite would retain its initial strength after 200 hours exposure at 316C (600F). Basic chemistry studies are required for determining NR-150B2 resin binder quality assurance parameters. Graphite fibers are available that can withstand high temperature cure and postcure cycles.

Chase, V. A.↗
NASA NTRS1994

Characterization of the association of nitrate reductase with barley (Hordeum vulgare L.) root membranes

The nature of the association between nitrate reductase (NR) and membranes was examined. Nitrate reductase activity (NRA) associated with the microsomal fraction of barley (Hordeum vulgare L.) roots amounted to 0.6 to 0.8% of soluble NRA following sonication in the presence of 250 mM KI and repeated osmotic shock. This treatment removed all contaminating soluble NRA from microsomes of uninduced barley roots that had been homogenized in a soluble extract from roots of NO3(-)-induced plants. On continuous sucrose gradients, NRA co-migrated specifically with VO4(-)-sensitive ATPase activity, a plasma membrane (PM) marker; activity of glucose-6-phosphate dehydrogenase, assayed as cytosolic marker, co-migrated with NRA. Microsomal NRA was absent in barley deficient in soluble NR. Perturbation and trypsinolysis experiments with PM vesicles isolated by aqueous two-phase partitioning indicated that NR is associated with the periphery of the cytoplasmic face of the bilayer. These results demonstrate that PM and soluble NRs are essentially the same protein but that the membrane-associated form is tightly bound. Although it is possible that PM-associated NR exists in vivo, unequivocal evidence for this has yet to be shown. However, PM NR is definitely present in vitro.

Non-NASA Center↗
NASA NTRS2013

Influence of Computational Drop Representation in LES of a Droplet-Laden Mixing Layer

Multiphase turbulent flows are encountered in many practical applications including turbine engines or natural phenomena involving particle dispersion. Numerical computations of multiphase turbulent flows are important because they provide a cheaper alternative to performing experiments during an engine design process or because they can provide predictions of pollutant dispersion, etc. Two-phase flows contain millions and sometimes billions of particles. For flows with volumetrically dilute particle loading, the most accurate method of numerically simulating the flow is based on direct numerical simulation (DNS) of the governing equations in which all scales of the flow including the small scales that are responsible for the overwhelming amount of dissipation are resolved. DNS, however, requires high computational cost and cannot be used in engineering design applications where iterations among several design conditions are necessary. Because of high computational cost, numerical simulations of such flows cannot track all these drops. The objective of this work is to quantify the influence of the number of computational drops and grid spacing on the accuracy of predicted flow statistics, and to possibly identify the minimum number, or, if not possible, the optimal number of computational drops that provide minimal error in flow prediction. For this purpose, several Large Eddy Simulation (LES) of a mixing layer with evaporating drops have been performed by using coarse, medium, and fine grid spacings and computational drops, rather than physical drops. To define computational drops, an integer NR is introduced that represents the ratio of the number of existing physical drops to the desired number of computational drops; for example, if NR=8, this means that a computational drop represents 8 physical drops in the flow field. The desired number of computational drops is determined by the available computational resources; the larger NR is, the less computationally intensive is the simulation. A set of first order and second order flow statistics, and of drop statistics are extracted from LES predictions and are compared to results obtained by filtering a DNS database. First order statistics such as Favre averaged stream-wise velocity, Favre averaged vapor mass fraction, and the drop stream-wise velocity, are predicted accurately independent of the number of computational drops and grid spacing. Second order flow statistics depend both on the number of computational drops and on grid spacing. The scalar variance and turbulent vapor flux are predicted accurately by the fine mesh LES only when NR is less than 32, and by the coarse mesh LES reasonably accurately for all NR values. This is attributed to the fact that when the grid spacing is coarsened, the number of drops in a computational cell must not be significantly lower than that in the DNS.

Bellan, Josette↗
NASA NTRSDate not supplied

Inter-Individual Variability in Astronaut Strength Response to Long-Duration Spaceflight May Be Dictated by In-Flight Exercise

BACKGROUND: Deconditioning induced by prolonged microgravity exposure during spaceflight hinders physical capacity. Examination of pre- to post-flight isokinetic strength measures shows that strength decreases; however, considerable variability between crewmembers exists. As in-flight exercise differs between crew, an examination of exercise training variables contributing to strength preservation is necessary. The purpose of this analysis was to examine in-flight exercise of astronauts who maintain strength compared to those with the greatest decrements in strength from pre- to post-flight. METHODS: The database of NASA International Space Station (ISS) crew who completed pre- and post-flight knee isokinetic testing (n = 87) was used to identify “responders” (R) and “non-responders” (NR) to in-flight exercise (≥ 90-day flight duration). R were those that maintained or improved strength (mean of knee extension and flexion at 60°/sec) (n = 14; 5.6 ± 7.8%), and NR were those with the most severe decrements (n = 14; -32.8 ± 4.1%) from pre- to post-flight. In-flight daily exercise records (cycle ergometer, treadmill, resistance exercise) were aggregated on a weekly basis. Independent t-tests or Mann-Whitney U tests were used to compare groups for in-flight exercise variables (i.e., frequency, time, intensity, volume). RESULTS: In-flight cycle ergometer frequency (2.4 ± 0.8 vs. 3.3 ± 1.0 days/wk; p = 0.021), total time (78.5 ± 20.4 vs. 114.0 ± 49.3 min/wk; p = 0.021), and active time (59.3 ± 17.2 vs. 86.9 ± 44.1 min/wk; p = 0.050) were greater in NR than R, but no differences for cycle intensity were observed. Treadmill distance traveled per session was greater in R than NR (4.6 ± 0.8 vs 3.6 ± 1.3 km/sess, p = 0.031), but no differences for treadmill frequency, total time, or active time were observed. Lower body resistance exercise intensity relative to pre-flight body weight was greater in R than NR (110.0 ± 16.5 vs 88.7 ± 25.0%; p = 0.012), but no differences in upper body or core resistance exercise intensity, volume, or frequency existed. CONCLUSIONS: The unique musculoskeletal loading provided by treadmill running at the expense of cycle ergometry, combined with using higher relative lower body loads during resistance training, may contribute to preserving strength in ISS crewmembers during long-duration spaceflight.

Alyssa N. Varanoske↗
NASA NTRS1983

The NASA/GSFC hydrogen maser program: A review of recent data

Data is presented on the phase and frequency stability, over time periods extending to one week, of the new NR field operable hydrogen masers developed by the Applied Physics Laboratory (APL) and the older NX and NP field operable hydrogen masers developed by Goddard Space Flight Center and maintained and upgraded by Bendix Field Engineering Corporation (BFEC). Data is presented on the NR masers in the laboratory showing frequency stabilities well into the 10 to the -15th power range and phase stabilities well into the 100 ps range for periods of up to one day. Data is presented on upgraded NP masers in the laboratory showing that the frequency stability has been improved substantially to virtually the NR level. VLBI data is presented on the phase difference between NX-2 at Owens Valley, California and NR-2 at Fort Davis, Texas for a one week period showing, after removal of a constant frequency drift, a 350 ps RMS phase stability.

Chiu, M.↗
NASA NTRS2001

Nitrate concentration effects on NO3-N uptake and reduction, growth, and fruit yield in strawberry

Strawberries (Fragaria xananassa Duch. 'Osogrande') were grown hydroponically with three NO3-N concentrations (3.75, 7.5, or 15.0 mM) to determine effects of varying concentration on NO3-N uptake and reduction rates, and to relate these processes to growth and fruit yield. Plants were grown for 32 weeks, and NO3-N uptake and nitrate reductase (NR) activities in roots and shoots were measured during vegetative and reproductive growth. In general, NO3-N uptake rates increased as NO3-N concentration in the hydroponics system increased. Tissue NO3- concentration also increased as external NO3-N concentration increased, reflecting the differences in uptake rates. There was no effect of external NO3-N concentration on NR activities in leaves or roots during either stage of development. Leaf NR activity averaged approximately 360 nmol NO2 formed/g fresh weight (FW)/h over both developmental stages, while NR activity in roots was much lower, averaging approximately 115 nmol NO2 formed/g FW/h. Vegetative organ FW, dry weight (DW), and total fruit yield were unaffected by NO3-N concentration. These data suggest that the inability of strawberry to increase growth and fruit yield in response to increasing NO3-N concentrations is not due to limitations in NO3-N uptake rates, but rather to limitations in NO3- reduction and/or assimilation in both roots and leaves.

NASA Center KSC↗
NASA NTRS1976

Friction characteristics of 20 x 4.4, type 7, aircraft tires constructed with different tread rubber compounds

A test program was conducted at the Langley aircraft landing loads and traction facility to evaluate the friction characteristics of 20 x 4.4, type, aircraft tires constructed with experimental cut-resistant, tread rubber compounds. These compounds consisted of different blends of natural rubber (NR) and an alfin catalyzed styrene-butadiene copolymer rubber (SBR). One tire having a blend of 30 SBR and 70 NR and another having a blend of 60 SBR and 40 NR in the tread were tested together with a standard production tire with no SBR content in the tread rubber. The results of this investigation indicated that the test tires constructed with the special cut-resistant tread rubber compositions did not suffer any significant degradation in tire friction capability when compared with the standard tire. In general, tire friction capability decreased with increasing speed and surface wetness condition. As yaw angle increased, tire braking capability decreased while tire cornering capability increased. Tread-wear data based on number of brake cycles, however, suggested that the tires with alfin SBR blends experienced significantly greater wear than the standard production tire.

Dreher, R. C.↗
NASA NTRS1978

Specialized physiological studies in support of manned space flight

The effects of a diuretic (Lasix) induced dehydration on the cardiovascular and hematological responses to lower body negative pressure (LBNP) were analyzed and compared to previous observations on dehydration following exercise in the heat. During LBNP runs the subjects were monitored for changes in blood volume, heart rate, blood pressure, and variations in the volume of the left calf. It was concluded that Lasix dehydration produced a depletion of the body electrolytes at the expense of both the plasma and extravascular compartments. Striking differences were found between those subjects who were physically active (Runners: R) and those who did not engage in any regular physical activity (Non-runners: NR). Tolerance to LBNP (Torr x min) was significantly lower in the R's than the NR's before and after dehydration, however the R's lost more of their tolerance after dehydration with Lasix than after exercise in the heat for about the same fluid loss. The opposite was true for the NR's. Two factors appear to be responsible for the lower LBNP tolerance in R's: parasympathetic inhibition of cardiac activity during LBNP and a greater propensity to pool blood in the lower extremities.

Luft, U. C.↗
NASA NTRS1988

High resolution VLA-Nancay observations of the sun

The Very Large Array (VLA) and the Nancay Radioheliograph (NR) can be used in the 1990s to provide unique observations of the quiescent and active corona. The combined data can specify the evolution and magnetic structure at a variety of heights in the quiescent corona, from compact to extended structures such as loops, streamers and coronal holes. The scientific potential of simultaneous VLA-NR research is illustrated by observations of solar noise storms with hitherto unavailable resolution in space (VLA) and time (NR). Unique information will also be provided for other types of solar bursts, leading to an improved understanding of solar activity during the coming maximum.

Kerdraon, A.↗
NASA NTRS1991

Laboratory test and acoustic analysis of cabin treatment for propfan test assessment aircraft

An aircraft cabin acoustic enclosure, built in support of the Propfan Test Assessment (PTA) program, is described. Helmholtz resonators were attached to the cabin trim panels to increase the sidewall transmission loss (TL). Resonators (448) were located between the trim panels and fuselage shell. In addition, 152 resonators were placed between the enclosure and aircraft floors. The 600 resonators were each tuned to a 235 Hz resonance frequency. After flight testing on the PTA aircraft, the enclosure was tested in the Kelly Johnson R and D Center Acoustics Lab. Laboratory noise reduction (NR) test results are discussed. The enclosure was placed in a Gulfstream 2 fuselage section. Broadband (138 dB overall SPL) and tonal (149 dB overall SPL) excitations were used in the lab. Tonal excitation simulated the propfan flight test excitation. The fundamental tone was stepped in 2 Hz intervals from 225 through 245 Hz. The resonators increase the NR of the cabin walls around the resonance frequency of the resonator array. The effects of flanking, sidewall absorption, cabin adsorption, resonator loading of trim panels, and panel vibrations are presented. Increases in NR of up to 11 dB were measured.

Kuntz, H. L.↗
NASA NTRS1991

Development and testing of cabin sidewall acoustic resonators for the reduction of cabin tone levels in propfan-powered aircraft

The use of Helmholtz resonators to increase the sidewall transmission loss (TL) in aircraft cabin sidewalls is evaluated. Development, construction, and test of an aircraft cabin acoustic enclosure, built in support of the Propfan Test Assessment (PTA) program, is described. Laboratory and flight test results are discussed. Resonators (448) were located between the enclosure trim panels and the fuselage shell. In addition, 152 resonators were placed between the enclosure and aircraft floors. The 600 resonators were each tuned to a propfan fundamental blade passage frequency (235 Hz). After flight testing on the PTA aircraft, noise reduction (NR) tests were performed with the enclosure in the Kelly Johnson Research and Development Center Acoustics Laboratory. Broadband and tonal excitations were used in the laboratory. Tonal excitation simulated the propfan flight test excitation. The resonators increase the NR of the cabin walls around the resonance frequency of the resonator array. Increases in NR of up to 11 dB were measured. The effects of flanking, sidewall absorption, cabin absorption, resonator loading of trim panels, and panel vibrations are presented. Resonator and sidewall panel design and test are discussed.

Kuntz, H. L.↗
NASA NTRS1990

Gravity-dependent polarity of cytoplasmic streaming in Nitellopsis

The internodal cells of the characean alga Nitellopsis obtusa were chosen to investigate the effect of gravity on cytoplasmic streaming. Horizontal cells exhibit streaming with equal velocities in both directions, whereas in vertically oriented cells, the downward-streaming cytoplasm flows ca. 10% faster than the upward-streaming cytoplasm. These results are independent of the orientation of the morphological top and bottom of the cell. We define the ratio of the velocity of the downward- to the upward-streaming cytoplasm as the polar ratio (PR). The normal polarity of a cell can be reversed (PR < 1) by treatment with neutral red (NR). The NR effect may be the result of membrane hyperpolarization, caused by the opening of K+ channels. The K+ channel blocker TEA Cl- inhibits the NR effect. External Ca2+ is required for normal graviresponsiveness. The [Ca2+] of the medium determines the polarity of cytoplasmic streaming. Less than 1 micromole Ca2+ resulted in a PR < 1 while greater than 1 micromole Ca2+ resulted in the normal gravity response. The voltage-dependent Ca(2+)-channel blocker, nifedipine, inhibited the gravity response in a reversible manner, while treatment with LaCl3 resulted in a PR < 1, indicating the presence of two types of Ca2+ channels. A new model for graviperception is presented in which the whole cell acts as the gravity sensor, and the plasma membrane acts as the gravireceptor. This is supported by ligation and UV irradiation experiments which indicate that the membranes at both ends of the cell are required for graviperception. The density of the external medium also affects the PR of Nitellopsis. Calculations are presented that indicate that the weight of the protoplasm may provide enough potential energy to open ion channels.

NASA Discipline Plant Biology↗
NASA NTRS2005

Prometheus Project final report

This Final Report serves as an executive summary of the Prometheus Project's activities and deliverables from November 2002 through September 2005. It focuses on the challenges from a technical and management perspective, what was different and innovative about this project, and identifies the major options, decisions, and accomplishments of the Project team as a whole. However, the details of the activities performed by DOE NR and its contractors will be documented separately in accordance with closeout requirements of the DOE NR and consistent with agreements between NASA and NR.

Prometheus Project↗
NASA NTRS2007

Fast Airborne Aerosol Size and Chemistry Measurements with the High Resolution Aerosol Mass Spectrometer during the MILAGRO Campaign

The concentration, size, and composition of non-refractory submicron aerosol (NR-PM(sub l)) was measured over Mexico City and central Mexico with a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) onboard the NSF/NCAR C-130 aircraft as part of the MILAGRO field campaign. This was the first aircraft deployment of the HR-ToF-AMS. During the campaign the instrument performed very well, and provided 12 s data. The aerosol mass from the AMS correlates strongly with other aerosol measurements on board the aircraft. Organic aerosol (OA) species dominate the NR-PM(sub l) mass. OA correlates strongly with CO and HCN indicating that pollution (mostly secondary OA, SOA) and biomass burning (BB) are the main OA sources. The OA to CO ratio indicates a typical value for aged air of around 80 microg/cubic m (STP) ppm(exp -1). This is within the range observed in outflow from the Northeastern US, which could be due to a compensating effect between higher BB but lower biogenic VOC emissions during this study. The O/C atomic ratio for OA is calculated from the HR mass spectra and shows a clear increase with photochemical age, as SOA forms rapidly and quickly overwhelms primary urban OA, consistent with Volkamer et al. (2006) and Kleinman et al. (2008). The stability of the OA/CO while O/C increases with photochemical age implies a net loss of carbon from the OA. BB OA is marked by signals at m/z 60 and 73, and also by a signal enhancement at large m/z indicative of larger molecules or more resistance to fragmentation. The main inorganic components show different spatial patterns and size distributions. Sulfate is regional in nature with clear volcanic and petrochemical/power plant sources, while the urban area is not a major regional source for this species. Nitrate is enhanced significantly in the urban area and immediate outflow, and is strongly correlated with CO indicating a strong urban source. The importance of nitrate decreases with distance from the city likely due to evaporation. BB does not appear to be a strong source of nitrate despite its high emissions of nitrogen oxides, presumably due to low ammonia emissions. NR-chloride often correlates with HCN indicating a fire source, although other sources likely contribute as well. This is the first aircraft study of the regional evolution of aerosol chemistry from a tropical megacity.

DeCarlo, P. F.↗
NASA NTRS2011

Magnetic Field-Line Lengths in Interplanetary Coronal Mass Ejections Inferred from Energetic Electron Events

About one quarter of the observed interplanetary coronal mass ejections (ICMEs) are characterized by enhanced magnetic fields that smoothly rotate in direction over timescales of about 10-50 hr. These ICMEs have the appearance of magnetic flux ropes and are known as "magnetic clouds" (MCs). The total lengths of MC field lines can be determined using solar energetic particles of known speeds when the solar release times and the I AU onset times of the particles are known. A recent examination of about 30 near-relativistic (NR) electron events in and near 8 MCs showed no obvious indication that the field-line lengths were longest near the MC boundaries and shortest at the MC axes or outside the MCs, contrary to the expectations for a flux rope. Here we use the impulsive beamed NR electron events observed with the Electron Proton and Alpha Monitor instrument on the Advanced Composition Explorer spacecraft and type III radio bursts observed on the Wind spacecraft to determine the field-line lengths inside ICMEs included in the catalog of Richardson & Cane. In particular, we extend this technique to ICMEs that are not MCs and compare the field-line lengths inside MCs and non-MC ICMEs with those in the ambient solar wind outside the ICMEs. No significant differences of field-line lengths are found among MCs, ICMEs, and the ambient solar wind. The estimated number of ICME field-line turns is generally smaller than those deduced for flux-rope model fits to MCs. We also find cases in which the electron injections occur in solar active regions CARs) distant from the source ARs of the ICMEs, supporting CME models that require extensive coronal magnetic reconnection with surrounding fields. The field-line lengths are found to be statistically longer for the NR electron events classified as ramps and interpreted as shock injections somewhat delayed from the type III bursts. The path lengths of the remaining spike and pulse electron events are compared with model calculations of solar wind field-line lengths resulting from turbulence and found to be in good agreement.

Kahler, S. W.↗