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Sample records for van allen radiation

  1. Wave acceleration of electrons in the Van Allen radiation belts.

    Science.gov (United States)

    Horne, Richard B; Thorne, Richard M; Shprits, Yuri Y; Meredith, Nigel P; Glauert, Sarah A; Smith, Andy J; Kanekal, Shrikanth G; Baker, Daniel N; Engebretson, Mark J; Posch, Jennifer L; Spasojevic, Maria; Inan, Umran S; Pickett, Jolene S; Decreau, Pierrette M E

    2005-09-08

    The Van Allen radiation belts are two regions encircling the Earth in which energetic charged particles are trapped inside the Earth's magnetic field. Their properties vary according to solar activity and they represent a hazard to satellites and humans in space. An important challenge has been to explain how the charged particles within these belts are accelerated to very high energies of several million electron volts. Here we show, on the basis of the analysis of a rare event where the outer radiation belt was depleted and then re-formed closer to the Earth, that the long established theory of acceleration by radial diffusion is inadequate; the electrons are accelerated more effectively by electromagnetic waves at frequencies of a few kilohertz. Wave acceleration can increase the electron flux by more than three orders of magnitude over the observed timescale of one to two days, more than sufficient to explain the new radiation belt. Wave acceleration could also be important for Jupiter, Saturn and other astrophysical objects with magnetic fields.

  2. Electron acceleration and loss caused by wave-particle interactions in the Van Allen radiation belts

    OpenAIRE

    Kersten, Tobias

    2016-01-01

    Modern society relies substantially on satellite technology as it is involved in vital services like telecommunication services, Earth observation, navigation, and many more. There are more than 1000 operational satellites in Earth orbit and most of these spend at least some of their time in the harsh environment of the Van Allen radiation belts. The radiation belts are usually split into two regions, the inner and the outer radiation belt. While the inner belt is considered stable, the flux ...

  3. Electron acceleration in the heart of the Van Allen radiation belts.

    Science.gov (United States)

    Reeves, G D; Spence, H E; Henderson, M G; Morley, S K; Friedel, R H W; Funsten, H O; Baker, D N; Kanekal, S G; Blake, J B; Fennell, J F; Claudepierre, S G; Thorne, R M; Turner, D L; Kletzing, C A; Kurth, W S; Larsen, B A; Niehof, J T

    2013-08-30

    The Van Allen radiation belts contain ultrarelativistic electrons trapped in Earth's magnetic field. Since their discovery in 1958, a fundamental unanswered question has been how electrons can be accelerated to such high energies. Two classes of processes have been proposed: transport and acceleration of electrons from a source population located outside the radiation belts (radial acceleration) or acceleration of lower-energy electrons to relativistic energies in situ in the heart of the radiation belts (local acceleration). We report measurements from NASA's Van Allen Radiation Belt Storm Probes that clearly distinguish between the two types of acceleration. The observed radial profiles of phase space density are characteristic of local acceleration in the heart of the radiation belts and are inconsistent with a predominantly radial acceleration process.

  4. Explaining occurrences of auroral kilometric radiation in Van Allen radiation belts

    Science.gov (United States)

    Xiao, Fuliang; Zhou, Qinghua; Su, Zhenpeng; He, Zhaoguo; Yang, Chang; Liu, Si; He, Yihua; Gao, Zhonglei

    2016-12-01

    Auroral kilometric radiation (AKR) is a strong terrestrial radio emission and dominates at higher latitudes because of reflection in vicinities of the source cavity and plasmapause. Recently, Van Allen Probes have observed occurrences of AKR emission in the equatorial region of Earth's radiation belts but its origin still remains an open question. Equatorial AKR can produce efficient acceleration of radiation belt electrons and is a risk to space weather. Here we report high-resolution observations during two small storm periods 4-6 April and 18-20 May 2013 and show, using a 3-D ray tracing simulation, that AKR can propagate downward all the way into the equatorial plane in the radiation belts under appropriate conditions. The simulated results can successfully explain the observed AKR's spatial distribution and frequency range, and the current results have a wide application to all other magnetized astrophysical objects in the universe.

  5. Automated Identification and Shape Analysis of Chorus Elements in the Van Allen Radiation Belts

    Science.gov (United States)

    Sen Gupta, Ananya; Kletzing, Craig; Howk, Robin; Kurth, William; Matheny, Morgan

    2017-12-01

    An important goal of the Van Allen Probes mission is to understand wave-particle interaction by chorus emissions in terrestrial Van Allen radiation belts. To test models, statistical characterization of chorus properties, such as amplitude variation and sweep rates, is an important scientific goal. The Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) instrumentation suite provides measurements of wave electric and magnetic fields as well as DC magnetic fields for the Van Allen Probes mission. However, manual inspection across terabytes of EMFISIS data is not feasible and as such introduces human confirmation bias. We present signal processing techniques for automated identification, shape analysis, and sweep rate characterization of high-amplitude whistler-mode chorus elements in the Van Allen radiation belts. Specifically, we develop signal processing techniques based on the radon transform that disambiguate chorus elements with a dominant sweep rate against hiss-like chorus. We present representative results validating our techniques and also provide statistical characterization of detected chorus elements across a case study of a 6 s epoch.

  6. Electron acceleration in the Van Allen radiation belts by fast magnetosonic waves

    OpenAIRE

    Horne, Richard B.; Thorne, Richard M.; Glauert, Sarah A.; Meredith, Nigel P.; Pokhotelov, Dimitry; Santolik, Ondrej

    2007-01-01

    Local acceleration is required to explain electron flux increases in the outer Van Allen radiation belt during magnetic storms. Here we show that fast magnetosonic waves, detected by Cluster 3, can accelerate electrons between ∼10 keV and a few MeV inside the outer radiation belt. Acceleration occurs via electron Landau resonance, and not Doppler shifted cyclotron resonance, due to wave propagation almost perpendicular to the ambient magnetic field. Using quasi-linear theory, pitch angle and ...

  7. Explaining the dynamics of the ultra-relativistic third Van Allen radiation belt

    OpenAIRE

    Mann, I. R.; Ozeke, L. G.; Murphy, K. R.; Claudepierre, S. G.; Turner, D. L.; Baker, D. N.; Rae, I. J.; Kale, A.; Milling, D. K.; Boyd, A. J.; Spence, H. E.; Reeves, G. D.; Singer, H. J.; Dimitrakoudis, S.; Daglis, I. A.

    2016-01-01

    Since the discovery of the Van Allen radiation belts over 50 years ago, an explanation for their complete dynamics has remained elusive. Especially challenging is understanding the recently discovered ultra-relativistic third electron radiation belt. Current theory asserts that loss in the heart of the outer belt, essential to the formation of the third belt, must be controlled by high-frequency plasma wave-particle scattering into the atmosphere, via whistler mode chorus, plasmaspheric hiss,...

  8. Radiation Belt Electron Intensity Variations: Van Allen Probes era vs. Previous two Solar Cycles

    Science.gov (United States)

    Li, X.; Baker, D. N.; Zhao, H.; Zhang, K.; Jaynes, A. N.; Schiller, Q.; Kanekal, S. G.; Blake, J. B.

    2016-12-01

    Long term (>2 solar cycles) measurements of solar wind speed, geomagnetic storm index (Dst), >2MeV electrons at geostationary orbit, 2MeV electrons in different L-shells measured at and normalized to low earth orbit show that the solar wind speed and the geomagnetic activity have been extremely low, so have been the MeV electron fluxes, during this current solar cycle, including years before and during Van Allen Probes era. There have been no 2MeV electrons enhancements deep inside L 2.6 since 2009, while numerous deep penetrations of MeV electrons into Lsolar wind conditions (high solar wind speed and sustained southward Bz) and thus stronger geomagnetic activity existed. We note that results from Van Allen Probes, which have been providing the finest measurements but in operation during an extremely quiet solar activity period, may not represent the overall radiation belt dynamics during other solar cycle phases.

  9. Radiation belt electron dynamics at low L (Van Allen Probes era versus previous two solar cycles

    Science.gov (United States)

    Li, X.; Baker, D. N.; Zhao, H.; Zhang, K.; Jaynes, A. N.; Schiller, Q.; Kanekal, S. G.; Blake, J. B.; Temerin, M.

    2017-05-01

    Long-term (>2 solar cycles) measurements reveal that MeV electron fluxes, solar wind speed, and geomagnetic activity have been extremely low during this current solar cycle, including years before and during the Van Allen Probes era. This study examines solar wind speed, the geomagnetic storm index (Dst), >2 MeV electrons at geostationary orbit, and 2 MeV electrons across various L shells measured by Solar Anomalous Magnetospheric Particle Explorer in low Earth orbit (LEO) and by the Van Allen Probes/Relativistic Electron and Proton Telescope (REPT) in a geotransfer-like orbit; the latter measurements are normalized to LEO based on comparison with Colorado Student Space Weather Experiment/Relativistic Electron and Proton Telescope integrated little experiment (REPTile) measurements in LEO. The average ratio of REPTile/REPT varies in a systematic manner with L, 16% at L = 2.7, decreasing with L and reaching 0.7% at L = 4.7, and increasing again with L though with greater uncertainty. We show that there have been no 2 MeV electron enhancements inside L 2.6 since 2006, prior to which numerous penetrations of 2 MeV electrons into L Van Allen Probes, which have been providing the finest measurements but in operation during a quiet solar activity period, may not be representative of radiation belt dynamics, particularly for the inner edge of the outer belt, during other solar cycle phases.

  10. An impenetrable barrier to ultrarelativistic electrons in the Van Allen radiation belts.

    Science.gov (United States)

    Baker, D N; Jaynes, A N; Hoxie, V C; Thorne, R M; Foster, J C; Li, X; Fennell, J F; Wygant, J R; Kanekal, S G; Erickson, P J; Kurth, W; Li, W; Ma, Q; Schiller, Q; Blum, L; Malaspina, D M; Gerrard, A; Lanzerotti, L J

    2014-11-27

    Early observations indicated that the Earth's Van Allen radiation belts could be separated into an inner zone dominated by high-energy protons and an outer zone dominated by high-energy electrons. Subsequent studies showed that electrons of moderate energy (less than about one megaelectronvolt) often populate both zones, with a deep 'slot' region largely devoid of particles between them. There is a region of dense cold plasma around the Earth known as the plasmasphere, the outer boundary of which is called the plasmapause. The two-belt radiation structure was explained as arising from strong electron interactions with plasmaspheric hiss just inside the plasmapause boundary, with the inner edge of the outer radiation zone corresponding to the minimum plasmapause location. Recent observations have revealed unexpected radiation belt morphology, especially at ultrarelativistic kinetic energies (more than five megaelectronvolts). Here we analyse an extended data set that reveals an exceedingly sharp inner boundary for the ultrarelativistic electrons. Additional, concurrently measured data reveal that this barrier to inward electron radial transport does not arise because of a physical boundary within the Earth's intrinsic magnetic field, and that inward radial diffusion is unlikely to be inhibited by scattering by electromagnetic transmitter wave fields. Rather, we suggest that exceptionally slow natural inward radial diffusion combined with weak, but persistent, wave-particle pitch angle scattering deep inside the Earth's plasmasphere can combine to create an almost impenetrable barrier through which the most energetic Van Allen belt electrons cannot migrate.

  11. The Van Allen Probes mission

    CERN Document Server

    Burch, James

    2014-01-01

    This collection of articles provides broad and detailed information about NASA’s Van Allen Probes (formerly known as the Radiation Belt Storm Probes) twin-spacecraft Earth-orbiting mission. The mission has the objective of achieving predictive understanding of the dynamic, intense, energetic, dangerous, and presently unpredictable belts of energetic particles that are magnetically trapped in Earth’s space environment above the atmosphere. It documents the science of the radiation belts and the societal benefits of achieving predictive understanding. Detailed information is provided about the Van Allen Probes mission design, the spacecraft, the science investigations, and the onboard instrumentation that must all work together to make unprecedented measurements within a most unforgiving environment, the core of Earth’s most intense radiation regions.
 This volume is aimed at graduate students and researchers active in space science, solar-terrestrial interactions and studies of the up...

  12. Understanding the Mechanisms of Radiation Belt Dropouts Observed by Van Allen Probes

    Science.gov (United States)

    Xiang, Zheng; Tu, Weichao; Li, Xinlin; Ni, Binbin; Morley, S. K.; Baker, D. N.

    2017-10-01

    To achieve a better understanding of the dominant loss mechanisms for the rapid dropouts of radiation belt electrons, three distinct radiation belt dropout events observed by Van Allen Probes are comprehensively investigated. For each event, observations of the pitch angle distribution of electron fluxes and electromagnetic ion cyclotron (EMIC) waves are analyzed to determine the effects of atmospheric precipitation loss due to pitch angle scattering induced by EMIC waves. Last closed drift shells (LCDS) and magnetopause standoff position are obtained to evaluate the effects of magnetopause shadowing loss. Evolution of electron phase space density (PSD) versus L* profiles and the μ and K (first and second adiabatic invariants) dependence of the electron PSD drops are calculated to further analyze the dominant loss mechanisms at different L*. Our findings suggest that these radiation belt dropouts can be classified into distinct classes in terms of dominant loss mechanisms: magnetopause shadowing dominant, EMIC wave scattering dominant, and combination of both mechanisms. Different from previous understanding, our results show that magnetopause shadowing can deplete electrons at L* 4. Compared to the magnetopause standoff position, it is more reliable to use LCDS to evaluate the impact of magnetopause shadowing. The evolution of electron PSD versus L* profile and the μ, K dependence of electron PSD drops can provide critical and credible clues regarding the mechanisms responsible for electron losses at different L* over the outer radiation belt.

  13. Explaining the Dynamics of the Ultra-relativistic Third Van Allen Radiation Belt

    Science.gov (United States)

    Mann, I. R.; Ozeke, L.; Murphy, K. R.; Claudepierre, S. G.; Turner, D. L.; Baker, D. N.; Rae, J.; Kale, A.; Milling, D. K.; Boyd, A. J.; Spence, H. E.; Reeves, G. D.; Singer, H. J.; Dimitrakoudis, S.; Daglis, I. A.; Honary, F.

    2016-12-01

    Since the discovery of the Van Allen radiation belts over 50 years ago, an explanation for their complete dynamics has remained elusive. Especially challenging is understanding losses deep in the heart of the belt which lead to the recently discovered ultra-relativistic third electron radiation belt. Prior theory asserted that loss in the heart of the outer belt, essential to the formation of the third belt, must be controlled by high-frequency plasma wave-particle scattering into the atmosphere, via whistler mode chorus, plasmaspheric hiss, or electromagnetic ion cyclotron waves. However, this has failed to accurately reproduce the third belt. Using a data driven, time-dependent specification of ultra-low-frequency (ULF) waves we show for the first time how the third radiation belt can be established as a simple, elegant consequence of storm-time extremely fast outward ULF wave transport. High-frequency wave-particle scattering loss into the atmosphere is not needed in this case. When rapid ULF wave transport coupled to a dynamic boundary is accurately specified, the sensitive dynamics controlling the enigmatic ultra-relativistic third radiation belt are naturally explained.

  14. Modeling the Proton Radiation Belt With Van Allen Probes Relativistic Electron-Proton Telescope Data

    Science.gov (United States)

    Selesnick, R. S.; Baker, D. N.; Kanekal, S. G.; Hoxie, V. C.; Li, X.

    2018-01-01

    An empirical model of the proton radiation belt is constructed from data taken during 2013-2017 by the Relativistic Electron-Proton Telescopes on the Van Allen Probes satellites. The model intensity is a function of time, kinetic energy in the range 18-600 MeV, equatorial pitch angle, and L shell of proton guiding centers. Data are selected, on the basis of energy deposits in each of the nine silicon detectors, to reduce background caused by hard proton energy spectra at low L. Instrument response functions are computed by Monte Carlo integration, using simulated proton paths through a simplified structural model, to account for energy loss in shielding material for protons outside the nominal field of view. Overlap of energy channels, their wide angular response, and changing satellite orientation require the model dependencies on all three independent variables be determined simultaneously. This is done by least squares minimization with a customized steepest descent algorithm. Model uncertainty accounts for statistical data error and systematic error in the simulated instrument response. A proton energy spectrum is also computed from data taken during the 8 January 2014 solar event, to illustrate methods for the simpler case of an isotropic and homogeneous model distribution. Radiation belt and solar proton results are compared to intensities computed with a simplified, on-axis response that can provide a good approximation under limited circumstances.

  15. Estimates of trapped radiation encountered on low-thrust trajectories through the Van Allen belts

    Science.gov (United States)

    Karp, I. M.

    1973-01-01

    Estimates were made of the number of trapped protons and electrons encountered by vehicles on low-thrust trajectories through the Van Allen belts. The estimates serve as a first step in assessing whether these radiations present a problem to on-board sensitive components and payload. The integrated proton spectra and electron spectra are presented for the case of a trajectory described by a vehicle with a constant-thrust acceleration A sub c equal to 0.001 meter/sq sec. This value of acceleration corresponds to a trip time of about 54 days from low earth orbit to synchronous orbit. It is shown that the time spent in the belts and hence the radiation encountered vary nearly inversely with the value of thrust acceleration. Thus, the integrated spectral values presented for the case of A sub c = 0.001 meter/sq sec can be generalized for any other value of thrust acceleration by multiplying them by the factor 0.001/A sub c.

  16. Van Allen Probes Mission Space Academy: Educating middle school students about Earth's mysterious radiation belts

    Science.gov (United States)

    Butler, L.; Turney, D.; Matiella Novak, A.; Smith, D.; Simon, M.

    2013-12-01

    How's the weather in space? Why on Earth did NASA send two satellites above Earth to study radiation belts and space weather? To learn the answer to questions about NASA's Van Allen Probes mission, 450 students and their teachers from Maryland middle schools attended Space Academy events highlighting the Van Allen Probes mission. Sponsored by the Applied Physics Laboratory (APL) and Discovery Education, the events are held at the APL campus in Laurel, MD. Space Academies take students and teachers on behind-the-scenes exploration of how spacecraft are built, what they are designed to study, and introduces them to the many professionals that work together to create some of NASA's most exciting projects. Moderated by a public relations representative in the format of an official NASA press conference, the daylong event includes a student press conference with students as reporters and mission experts as panelists. Lunch with mission team members gives students a chance to ask more questions. After lunch, students don souvenir clean room suits, enjoy interactive science demonstrations, and tour APL facilities where the Van Allen Probes were built and tested before launch. Students may even have an opportunity to peek inside a clean room to view spacecraft being assembled. Prior to the event, teachers are provided with classroom activities, lesson plans, and videos developed by APL and Discovery Education to help prepare students for the featured mission. The activities are aligned to National Science Education Standards and appropriate for use in the classroom. Following their visit, student journalists are encouraged to write a short article about their field trip; selections are posted on the Space Academy web site. Designed to engage, inspire, and influence attitudes about space science and STEM careers, Space Academies provide an opportunity to attract underserved populations and emphasize that space science is for everyone. Exposing students to a diverse group of

  17. Statistical properties of plasmaspheric hiss derived from Van Allen Probes data and their Effects on radiation belt electron dynamics

    OpenAIRE

    Li, W; Ma, Q; Thorne, RM; Bortnik, J; Kletzing, CA; Kurth, WS; Hospodarsky, GB; Nishimura, Y

    2015-01-01

    ©2015. American Geophysical Union. Plasmaspheric hiss is known to play an important role in controlling the overall structure and dynamics of radiation belt electrons inside the plasmasphere. Using newly available Van Allen Probes wave data, which provide excellent coverage in the entire inner magnetosphere, we evaluate the global distribution of the hiss wave frequency spectrum and wave intensity for different levels of substorm activity. Our statistical results show that observed hiss peak ...

  18. Generation of extremely low frequency chorus in Van Allen radiation belts

    Science.gov (United States)

    Xiao, Fuliang; Liu, Si; Tao, Xin; Su, Zhenpeng; Zhou, Qinghua; Yang, Chang; He, Zhaoguo; He, Yihua; Gao, Zhonglei; Baker, D. N.; Spence, H. E.; Reeves, G. D.; Funsten, H. O.; Blake, J. B.

    2017-03-01

    Recent studies have shown that chorus can efficiently accelerate the outer radiation belt electrons to relativistic energies. Chorus, previously often observed above 0.1 equatorial electron gyrofrequency fce, was generated by energetic electrons originating from Earth's plasma sheet. Chorus below 0.1 fce has seldom been reported until the recent data from Van Allen Probes, but its origin has not been revealed so far. Because electron resonant energy can approach the relativistic level at extremely low frequency, relativistic effects should be considered in the formula for whistler mode wave growth rate. Here we report high-resolution observations during the 14 October 2014 small storm and firstly demonstrate, using a fully relativistic simulation, that electrons with the high-energy tail population and relativistic pitch angle anisotropy can provide free energy sufficient for generating chorus below 0.1 fce. The simulated wave growth displays a very similar pattern to the observations. The current results can be applied to Jupiter, Saturn, and other magnetized planets.

  19. Innermost Van Allen Radiation Belt for High Energy Protons at Saturn

    Science.gov (United States)

    Cooper, John F.

    2008-01-01

    The high energy proton radiation belts of Saturn are energetically dominated by the source from cosmic ray albedo neutron decay (CRAND), trapping of protons from beta decay of neutrons emitted from galactic cosmic ray nuclear interactions with the main rings. These belts were originally discovered in wide gaps between the A-ring, Janus/Epimetheus, Mimas, and Enceladus. The narrow F and G rings significant affected the CRAND protons but did not produce total depletion. Voyager 2 measurements subsequently revealed an outermost CRAND proton belt beyond Enceladus. Although the source rate is small, the trapping times limited by radial magnetospheric diffusion are very long, about ten years at peak measured flux inwards of the G ring, so large fluxes can accumulate unless otherwise limited in the trapping region by neutral gas, dust, and ring body interactions. One proposed final extension of the Cassini Orbiter mission would place perikrone in a 3000-km gap between the inner D ring and the upper atmosphere of Saturn. Experience with CRAND in the Earth's inner Van Allen proton belt suggests that a similar innermost belt might be found in this comparably wide region at Saturn. Radial dependence of magnetospheric diffusion, proximity to the ring neutron source, and northward magnetic offset of Saturn's magnetic equator from the ring plane could potentially produce peak fluxes several orders of magnitude higher than previously measured outside the main rings. Even brief passes through such an intense environment of highly penetrating protons would be a significant concern for spacecraft operations and science observations. Actual fluxes are limited by losses in Saturn's exospheric gas and in a dust environment likely comparable to that of the known CRAND proton belts. The first numerical model of this unexplored radiation belt is presented to determine limits on peak magnitude and radial profile of the proton flux distribution.

  20. Saturation of Van Allen's belts

    CERN Document Server

    Le Bel, E

    2002-01-01

    The maximum number of electrons that can be trapped in van Allen's belts has been evaluated at CEA-DAM more precisely than that commonly used in the space community. The modelization that we have developed allows to understand the disagreement (factor 50) observed between the measured and predicted electrons flux by US satellites and theory. This saturation level allows sizing-up of the protection on a satellite in case of energetic events. (authors)

  1. Van Allen Probes show that the inner radiation zone contains no MeV electrons: ECT/MagEIS data

    Science.gov (United States)

    Fennell, J. F.; Claudepierre, S. G.; Blake, J. B.; O'Brien, T. P.; Clemmons, J. H.; Baker, D. N.; Spence, H. E.; Reeves, G. D.

    2015-03-01

    We present Van Allen Probe observations of electrons in the inner radiation zone. The measurements were made by the Energetic Particle, Composition, and Thermal Plasma/Magnetic Electron Ion Spectrometer (MagEIS) sensors that were designed to measure electrons with the ability to remove unwanted signals from penetrating protons, providing clean measurements. No electrons >900 keV were observed with equatorial fluxes above background (i.e., >0.1 el/(cm2 s sr keV)) in the inner zone. The observed fluxes are compared to the AE9 model and CRRES observations. Electron fluxes electrons in the inner zone while current radiation belt models and previous publications do.

  2. James Van Allen The First Eight Billion Miles

    CERN Document Server

    Foerstner, Abigail

    2009-01-01

    Astrophysicist and space pioneer James Van Allen (1914-2006), for whom the Van Allen radiation belts were named, was among the principal scientific investigators for twenty-four space missions, including Explorer I in 1958, the first successful U.S. satellite; Mariner 2's 1962 flyby of Venus, the first successful mission to another planet; and the 1970's Pioneer 10 and Pioneer 11, missions that surveyed Jupiter and Saturn. Abigail Foerstner blends space science, drama, military agenda's, cold war politics, and the events of Van Allen's lengthy career to create the first biography of this highl

  3. Van Allen Probes observations of prompt MeV radiation belt electron acceleration in nonlinear interactions with VLF chorus

    Science.gov (United States)

    Foster, J. C.; Erickson, P. J.; Omura, Y.; Baker, D. N.; Kletzing, C. A.; Claudepierre, S. G.

    2017-01-01

    Prompt recovery of MeV (millions of electron Volts) electron populations in the poststorm core of the outer terrestrial radiation belt involves local acceleration of a seed population of energetic electrons in interactions with VLF chorus waves. Electron interactions during the generation of VLF rising tones are strongly nonlinear, such that a fraction of the relativistic electrons at resonant energies are trapped by waves, leading to significant nonadiabatic energy exchange. Through detailed examination of VLF chorus and electron fluxes observed by Van Allen Probes, we investigate the efficiency of nonlinear processes for acceleration of electrons to MeV energies. We find through subpacket analysis of chorus waveforms that electrons with initial energy of hundreds of keV to 3 MeV can be accelerated by 50 keV-200 keV in resonant interactions with a single VLF rising tone on a time scale of 10-100 ms.

  4. Signatures of Ultrarelativistic Electron Loss in the Heart of the Outer Radiation Belt Measured by Van Allen Probes

    Science.gov (United States)

    Aseev, N. A.; Shprits, Y. Y.; Drozdov, A. Y.; Kellerman, A. C.; Usanova, M. E.; Wang, D.; Zhelavskaya, I. S.

    2017-10-01

    Up until recently, signatures of the ultrarelativistic electron loss driven by electromagnetic ion cyclotron (EMIC) waves in the Earth's outer radiation belt have been limited to direct or indirect measurements of electron precipitation or the narrowing of normalized pitch angle distributions in the heart of the belt. In this study, we demonstrate additional observational evidence of ultrarelativistic electron loss that can be driven by resonant interaction with EMIC waves. We analyzed the profiles derived from Van Allen Probe particle data as a function of time and three adiabatic invariants between 9 October and 29 November 2012. New local minimums in the profiles are accompanied by the narrowing of normalized pitch angle distributions and ground-based detection of EMIC waves. Such a correlation may be indicative of ultrarelativistic electron precipitation into the Earth's atmosphere caused by resonance with EMIC waves.

  5. Plasma Wave Measurements from the Van Allen Probes

    OpenAIRE

    Hospodarsky, George B.; Kurth, W. S.; Kletzing, C. A.; Bounds, S. R.; Santolik, O.; Wygant, J. R.; Bonnell, J. W.

    2014-01-01

    The twin Van Allen Probes spacecraft were launched on August 30, 2012 to study the Earth's Van Allen radiation belts. The Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) investigation includes a plasma wave instrument (Waves) that simultaneously measures three orthogonal components of the wave magnetic field from ~10 Hz to 12 kHz and, with the support of the Electric Fields and Waves (EFW) instrument sensors, three components of the wave electric field from ~10 H...

  6. Statistical study of the storm time radiation belt evolution during Van Allen Probes era: CME- versus CIR-driven storms

    Science.gov (United States)

    Shen, Xiao-Chen; Hudson, Mary K.; Jaynes, Allison N.; Shi, Quanqi; Tian, Anmin; Claudepierre, Seth G.; Qin, Mu-Rong; Zong, Qiu-Gang; Sun, Wei-Jie

    2017-08-01

    Coronal mass ejection (CME)-driven or corotating interaction region (CIR)-driven storms can change the electron distributions in the radiation belt dramatically, which can in turn affect the spacecraft in this region or induce geomagnetic effects. The Van Allen Probes twin spacecraft, launched on 30 August 2012, orbit near the equatorial plane and across a wide range of L∗ with apogee at 5.8 RE and perigee at 620 km. Electron data from Van Allen Probes MagEIS and REPT instruments have been binned every 6 h at L∗=3 (defined as 2.5 < L∗<3.5), 4 (3.5 < L∗<4.5), 5 (4.5 < L∗<5.5). The superposed epoch analysis shows that (1) CME storms induce more electron flux enhancement at L∗=3 for energy channels below 1 MeV than CIR storms; (2) CME storms induce more electron flux enhancement at L∗=4 and 5 in the energy channels above 1 MeV than CIR storms; (3) CIR storms induce more electron flux enhancement at L∗=4 and 5 in the energy channels below 1 MeV than CME storms; (4) intense CME induce more than 50 times flux enhancement for the energy channel around 400 keV at L∗=3; (5) intense CIR induce more than 50 times flux enhancement for the energy channel around 200 keV at L∗=4. These results are consistent with a general picture of enhanced convection over a longer period for CIR storms which increased flux closer to geosynchronous orbit consistent with earlier studies, while CME storms likely produce deeper penetration of enhanced flux and local heating which is greater at higher energies at lower L∗.

  7. On the Effect of Geomagnetic Storms on Relativistic Electrons in the Outer Radiation Belt: Van Allen Probes Observations

    Science.gov (United States)

    Moya, Pablo S.; Pinto, Víctor A.; Sibeck, David G.; Kanekal, Shrikanth G.; Baker, Daniel N.

    2017-11-01

    Using Van Allen Probes Energetic Particle, Composition, and Thermal Plasma-Relativistic Electron-Proton Telescope (ECT-REPT) observations, we performed a statistical study on the effect of geomagnetic storms on relativistic electrons fluxes in the outer radiation belt for 78 storms between September 2012 and June 2016. We found that the probability of enhancement, depletion, and no change in flux values depends strongly on L and energy. Enhancement events are more common for ˜2 MeV electrons at L ˜ 5, and the number of enhancement events decreases with increasing energy at any given L shell. However, considering the percentage of occurrence of each kind of event, enhancements are more probable at higher energies, and the probability of enhancement tends to increases with increasing L shell. Depletion are more probable for 4-5 MeV electrons at the heart of the outer radiation belt, and no-change events are more frequent at L 4.5 the probability of enhancement, depletion, or no-change response presents little variation for all energies. Because these probabilities remain relatively constant as a function of radial distance in the outer radiation belt, measurements obtained at geosynchronous orbit may be used as a proxy to monitor E≥1.8 MeV electrons in the outer belt.

  8. Obituary: James Alfred Van Allen, 1914-2006

    Science.gov (United States)

    Ludwig, George H.; McIlwain, Carl Edwin

    2006-12-01

    successful field expeditions from 1952 through 1957. As the prospect for launching Earth satellites began to materialize, Van Allen became an enthusiastic participant in planning and executing the U.S. program. After gaining a spot on the short list of initial experiments for the Vanguard satellite program, development of the cosmic ray instrument that he had proposed became a high laboratory priority. That instrument was launched in abbreviated form by an Army Jupiter C vehicle as Explorer I on 31 January 1958, and the full version was launched less than two months later as Explorer III. The two satellites resulted in what Van Allen considered the crowning event of his long and distinguished career — the discovery, with his university associates, of the bands of intense radiation that surround the Earth, now known as the "Van Allen Radiation Belts." Van Allen continued to take a leading role in extending space research beyond Earth's orbit. His group sent instruments to the Moon, Venus, Mars, Jupiter, Saturn, and throughout interplanetary space. During his outstandingly productive career, Van Allen served as principal investigator on more than twenty-five space science missions. James Van Allen was the consummate teacher and mentor. Years ago, when asked how he would most like to be remembered, he replied simply, "As a teacher." He supervised the preparation of forty-eight master's and thirty-four doctor's theses by sixty different individuals. He gave those graduate students extraordinary freedom and responsibility in the conduct of their projects. He always treated his students, both undergraduate and graduate, with respect, listening to them, learning from them, and guiding them with wisdom and kindness. The folksy, pipe-smoking scientist worked from 1951 until 1964 in a modest office on the second floor of the old Physics and Mathematics building. He maintained his own private laboratory, where he continued to spend many hours with hands-on work at the bench. When the

  9. Wave-induced loss of ultra-relativistic electrons in the Van Allen radiation belts.

    Science.gov (United States)

    Shprits, Yuri Y; Drozdov, Alexander Y; Spasojevic, Maria; Kellerman, Adam C; Usanova, Maria E; Engebretson, Mark J; Agapitov, Oleksiy V; Zhelavskaya, Irina S; Raita, Tero J; Spence, Harlan E; Baker, Daniel N; Zhu, Hui; Aseev, Nikita A

    2016-09-28

    The dipole configuration of the Earth's magnetic field allows for the trapping of highly energetic particles, which form the radiation belts. Although significant advances have been made in understanding the acceleration mechanisms in the radiation belts, the loss processes remain poorly understood. Unique observations on 17 January 2013 provide detailed information throughout the belts on the energy spectrum and pitch angle (angle between the velocity of a particle and the magnetic field) distribution of electrons up to ultra-relativistic energies. Here we show that although relativistic electrons are enhanced, ultra-relativistic electrons become depleted and distributions of particles show very clear telltale signatures of electromagnetic ion cyclotron wave-induced loss. Comparisons between observations and modelling of the evolution of the electron flux and pitch angle show that electromagnetic ion cyclotron waves provide the dominant loss mechanism at ultra-relativistic energies and produce a profound dropout of the ultra-relativistic radiation belt fluxes.

  10. Long-term radiation belt relativistic electron simulations with the VERB code using new wave parameterizations derived from Van Allen Probes measurements

    Science.gov (United States)

    Zhu, H.; Shprits, Y. Y.; Spasojevic, M.; Kellerman, A. C.; Drozdov, A.

    2016-12-01

    New wave frequency and amplitude models for nightside and dayside chorus waves are developed based on measurement from the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) instrument on board Van Allen Probes. New paremetrizations can be used for quiet, moderate and disturbed conditions. The corresponding 3D diffusion coefficients are calculated using the Full Diffusion Code. The new parameterizations result in differences in the diffusion coefficients as a function of both electron energy and pitch angle. Furthermore, one-year 3D simulations are performed using the Versatile Electron Radiation Belt (VERB) code. Simulations with new parametrizations show better agreement with observations.

  11. Analysis of the passage of a spacecraft between the Van Allen belts considering a low and high solar activity

    Science.gov (United States)

    da Silva, M. R.; Rocco, E. M.

    2017-10-01

    The radiation in the Van Allen belts, produced by electrically charged particles, can cause damages to the electrical equipments of a satellite in orbit of Earth. In this paper, the Van Allen belts are modeled using the data from the space mission Van Allen Probes Mission. With this model, a study was made taking into account the passage of a spacecraft through the Van Allen belts estimating the absorbed radiation dose and the time that spacecraft remained in the radiation zones, considering the effects of a low and high solar activity.

  12. Generation of lower and upper bands of electrostatic electron cyclotron harmonic waves in the Van Allen radiation belts

    Science.gov (United States)

    Zhou, Qinghua; Xiao, Fuliang; Yang, Chang; Liu, Si; He, Yihua; Baker, D. N.; Spence, H. E.; Reeves, G. D.; Funsten, H. O.

    2017-06-01

    Electrostatic electron cyclotron harmonic (ECH) waves generated by the electron loss cone distribution can produce efficient scattering loss of plasma sheet electrons, which has a significant effect on the dynamics in the outer magnetosphere. Here we report two ECH emission events around the same location L≈ 5.7-5.8, MLT ≈ 12 from Van Allen Probes on 11 February (event A) and 9 January 2014 (event B), respectively. The spectrum of ECH waves was centered at the lower half of the harmonic bands during event A, but the upper half during event B. The observed electron phase space density in both events is fitted by the subtracted bi-Maxwellian distribution, and the fitting functions are used to evaluate the local growth rates of ECH waves based on a linear theory for homogeneous plasmas. ECH waves are excited by the loss cone instability of 50 eV-1 keV electrons in the lower half of harmonic bands in the low-density plasmasphere in event A, and 1-10 keV electrons in the upper half of harmonic bands in a relatively high-density region in event B. The current results successfully explain observations and provide a first direct evidence on how ECH waves are generated in the lower and upper half of harmonic frequency bands.

  13. A Comparison of Van Allen Belt Radiation Environment Modeling Programs: AE8/AP8 Legacy, AE9/AP9, and SPENVIS

    Science.gov (United States)

    Reed, Evan; Pellish, Jonathan

    2016-01-01

    In the space surrounding Earth there exists an active radiation environment consisting mostly of electrons and protons that have been trapped by Earths magnetic field. This radiation, also known as the Van Allen Belts, has the potential to damage man-made satellites in orbit; thus, proper precautions must be taken to shield NASA assets from this phenomenon. Data on the Van Allen Belts has been collected continuously by a multitude of space-based instruments since the beginning of space exploration. Subsequently, using theory to fill in the gaps in the collected data, computer models have been developed that take in the orbital information of a hypothetical mission and output the expected particle fluence and flux for that orbit. However, as new versions of the modeling system are released, users are left wondering how the new version differs from the old. Therefore, we performed a comparison of three different editions of the modeling system: AE8/AP8 (legacy), which is included in the model 9 graphical user interface as an option for ones calculations, AE9/AP9, and the Space Environment Information System (SPENVIS), which is an online-based form of AE8/AP8 developed by NASA and the European Space Agency that changed the code to allow the program to extrapolate data to predict fluence and flux at higher energies. Although this evaluation is still ongoing, it is predicted that the model 8 (legacy) and SPENVIS version will have identical outputs with the exception of the extended energy levels from SPENVIS, while model 9 will provide different fluences than model 8 based on additional magnetic field descriptions and on-orbit data.

  14. On the ultra-low frequency wave contributions to the relativistic electron flux dynamics in the outer Van Allen radiation belt

    Science.gov (United States)

    Dal Lago, A.; Marchezi, J. P.; Alves, L. R.; da Silva, L.; Dallaqua, R.; Medeiros, C.; Souza, V. M. C. E. S.; Rockenbach, M.; Vieira, L.; Mendes, O., Jr.; Sibeck, D. G.; Kanekal, S. G.; Kletzing, C.; Baker, D. N.; Wygant, J. R.

    2016-12-01

    Various physical processes can contribute to loss and acceleration of energetic electrons in the Earth's radiation belts. In the range of 1 mHz to 10 Hz, ultra-low frequency (ULF) waves are known to cause significant changes in the energetic particle flux in the radiation belts. On board the Van Allen Probes, the Relativistic Electron Proton Telescope (REPT) measures the relativistic electron flux in the outer radiation belts in the energy range from 1.8 MeV up to 20 MeV. We selected events that have significant electron flux dropouts, classified into two categories regarding the time elapsed between the outer radiation belt dropout and the refurbishing, namely events that time scale had taken (i) a few hours and, (ii) some days. This work aims to investigate the presence of ULF waves using the radial and azimuthal magnetic and electric field components recorded by the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS). The evaluation of the power spectral density of those components unravels the poloidal and toroidal characteristc of the rapid compressional waves. We discuss how these modes can contribute to modifications of the relativistic electron fluxes considering the (i) and (ii) cases.

  15. Science Goals and Overview of the Radiation Belt Storm Probes (RBSP) Energetic Particle, Composition, and Thermal Plasma (ECT) Suite on NASA's Van Allen Probes Mission

    Science.gov (United States)

    Spence, H. E.; Reeves, G. D.; Baker, D. N.; Blake, J. B.; Bolton, M.; Bourdarie, S.; Chan, A. A.; Claudepierre, S. G.; Clemmons, J. H.; Cravens, J. P.; Elkington, S. R.; Fennell, J. F.; Friedel, R. H. W.; Funsten, H. O.; Goldstein, J.; Green, J. C.; Guthrie, A.; Henderson, M. G.; Horne, R. B.; Hudson, M. K.; Jahn, J.-M.; Jordanova, V. K.; Kanekal, S. G.; Klatt, B. W.; Larsen, B. A.; Li, X.; MacDonald, E. A.; Mann, I. R.; Niehof, J.; O'Brien, T. P.; Onsager, T. G.; Salvaggio, D.; Skoug, R. M.; Smith, S. S.; Suther, L. L.; Thomsen, M. F.; Thorne, R. M.

    2013-11-01

    The Radiation Belt Storm Probes (RBSP)-Energetic Particle, Composition, and Thermal Plasma (ECT) suite contains an innovative complement of particle instruments to ensure the highest quality measurements ever made in the inner magnetosphere and radiation belts. The coordinated RBSP-ECT particle measurements, analyzed in combination with fields and waves observations and state-of-the-art theory and modeling, are necessary for understanding the acceleration, global distribution, and variability of radiation belt electrons and ions, key science objectives of NASA's Living With a Star program and the Van Allen Probes mission. The RBSP-ECT suite consists of three highly-coordinated instruments: the Magnetic Electron Ion Spectrometer (MagEIS), the Helium Oxygen Proton Electron (HOPE) sensor, and the Relativistic Electron Proton Telescope (REPT). Collectively they cover, continuously, the full electron and ion spectra from one eV to 10's of MeV with sufficient energy resolution, pitch angle coverage and resolution, and with composition measurements in the critical energy range up to 50 keV and also from a few to 50 MeV/nucleon. All three instruments are based on measurement techniques proven in the radiation belts. The instruments use those proven techniques along with innovative new designs, optimized for operation in the most extreme conditions in order to provide unambiguous separation of ions and electrons and clean energy responses even in the presence of extreme penetrating background environments. The design, fabrication and operation of ECT spaceflight instrumentation in the harsh radiation belt environment ensure that particle measurements have the fidelity needed for closure in answering key mission science questions. ECT instrument details are provided in companion papers in this same issue. In this paper, we describe the science objectives of the RBSP-ECT instrument suite on the Van Allen Probe spacecraft within the context of the overall mission objectives

  16. Automated bow shock and radiation belt edge identification methods and their application for Cluster, THEMIS/ARTEMIS and Van Allen Probes data

    Science.gov (United States)

    Facsko, Gabor; Sibeck, David; Balogh, Tamas; Kis, Arpad; Wesztergom, Viktor

    2017-04-01

    The bow shock and the outer rim of the outer radiation belt are detected automatically by our algorithm developed as a part of the Boundary Layer Identification Code Cluster Active Archive project. The radiation belt positions are determined from energized electron measurements working properly onboard all Cluster spacecraft. For bow shock identification we use magnetometer data and, when available, ion plasma instrument data. In addition, electrostatic wave instrument electron density, spacecraft potential measurements and wake indicator auxiliary data are also used so the events can be identified by all Cluster probes in highly redundant way, as the magnetometer and these instruments are still operational in all spacecraft. The capability and performance of the bow shock identification algorithm were tested using known bow shock crossing determined manually from January 29, 2002 to February 3,. The verification enabled 70% of the bow shock crossings to be identified automatically. The method shows high flexibility and it can be applied to observations from various spacecraft. Now these tools have been applied to Time History of Events and Macroscale Interactions during Substorms (THEMIS)/Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon's Interaction with the Sun (ARTEMIS) magnetic field, plasma and spacecraft potential observations to identify bow shock crossings; and to Van Allen Probes supra-thermal electron observations to identify the edges of the radiation belt. The outcomes of the algorithms are checked manually and the parameters used to search for bow shock identification are refined.

  17. Estimates of Total Radiation Belt Electron Content (TRBEC) and its Time Evolution using the RBSP-ECT Instrument Suite on the Van Allen Probes Mission

    Science.gov (United States)

    Spence, H.; Boyd, A. J.; Huang, C.; Smith, S. S.; Henderson, M. G.; Friedel, R. H.; Larsen, B.; Reeves, G. D.; Blake, J. B.; Claudepierre, S. G.; Fennell, J. F.; Baker, D. N.; Kanekal, S. G.

    2013-12-01

    Using measurements from the two-spacecraft Van Allen Probes mission we estimate the total radiation belt electron content (TRBEC) as a simple, global quantitative measure of radiation belt intensity. The two identically-instrumented spacecraft provide comprehensive energy and pitch angle coverage of radiation belt electrons near the magnetic equator throughout the inner magnetosphere, an advantage over earlier studies by Baker et al. (2004) and Selesnick and Kanekal (2009) that estimated similar quantities in LEO or in high-altitude polar orbits. We use electron measurements from the Radiation Belt Storm Probes (RBSP) Energetic Particle, Composition, and Thermal Plasma (ECT) suite to identify both the electron seed populations (a few 10's to a few 100's keV) as well as radiation belt electron populations (> ~ 500 keV) with the Magnetic Electron Ion Spectrometer (MagEIS) and the Relativistic Electron Proton Telescope (REPT) sensors. MagEIS provides the electron seed population measurements; MagEIS and REPT together provide the core radiation belt and ultra-relativistic electron populations. Using energy-resolved, locally-measured pitch angle distributions of electrons as a function of L, we estimate the equatorial distribution and then integrate the electrons over energy and pitch angle throughout the spatial volume to establish the TRBEC for both the electron seed and the core populations. Finally, we show how TRBEC varies as a function of time over the course of the mission, compare these variations to other quantitative measures of inner magnetospheric dynamism (e.g., Dst) and solar wind drivers, compare the seed to core TRBEC values and its time evolution, as well as compare to prior quantitative estimates of radiation belt electron content.

  18. Typical values of the electric drift E × B/B2 in the inner radiation belt and slot region as determined from Van Allen Probe measurements

    Science.gov (United States)

    Lejosne, Solène; Mozer, F. S.

    2016-12-01

    The electric drift E × B/B2 plays a fundamental role for the description of plasma flow and particle acceleration. Yet it is not well-known in the inner belt and slot region because of a lack of reliable in situ measurements. In this article, we present an analysis of the electric drifts measured below L 3 by both Van Allen Probes A and B from September 2012 to December 2014. The objective is to determine the typical components of the equatorial electric drift in both radial and azimuthal directions. The dependences of the components on radial distance, magnetic local time, and geographic longitude are examined. The results from Van Allen Probe A agree with Van Allen Probe B. They show, among other things, a typical corotation lag of the order of 5 to 10% below L 2.6, as well as a slight radial transport of the order of 20 m s-1. The magnetic local time dependence of the electric drift is consistent with that of the ionosphere wind dynamo below L 2 and with that of a solar wind-driven convection electric field above L 2. A secondary longitudinal dependence of the electric field is also found. Therefore, this work also demonstrates that the instruments on board Van Allen Probes are able to perform accurate measurements of the electric drift below L 3.

  19. Saturation of Van Allen's belts; Saturation des ceintures de Van Allen

    Energy Technology Data Exchange (ETDEWEB)

    Le Bel, E.; Simonet, F. [CEA Bruyeres-le-Chatel, 91 (France)

    2002-12-01

    The maximum number of electrons that can be trapped in van Allen's belts has been evaluated at CEA-DAM more precisely than that commonly used in the space community. The modelization that we have developed allows to understand the disagreement (factor 50) observed between the measured and predicted electrons flux by US satellites and theory. This saturation level allows sizing-up of the protection on a satellite in case of energetic events. (authors)

  20. Scattering of Ultra-relativistic Electrons in the Van Allen Radiation Belts Accounting for Hot Plasma Effects.

    Science.gov (United States)

    Cao, Xing; Shprits, Yuri Y; Ni, Binbin; Zhelavskaya, Irina S

    2017-12-18

    Electron flux in the Earth's outer radiation belt is highly variable due to a delicate balance between competing acceleration and loss processes. It has been long recognized that Electromagnetic Ion Cyclotron (EMIC) waves may play a crucial role in the loss of radiation belt electrons. Previous theoretical studies proposed that EMIC waves may account for the loss of the relativistic electron population. However, recent observations showed that while EMIC waves are responsible for the significant loss of ultra-relativistic electrons, the relativistic electron population is almost unaffected. In this study, we provide a theoretical explanation for this discrepancy between previous theoretical studies and recent observations. We demonstrate that EMIC waves mainly contribute to the loss of ultra-relativistic electrons. This study significantly improves the current understanding of the electron dynamics in the Earth's radiation belt and also can help us understand the radiation environments of the exoplanets and outer planets.

  1. Scattering of Ultra-relativistic Electrons in the Van Allen Radiation Belts Accounting for Hot Plasma Effects

    OpenAIRE

    Cao, Xing; Shprits, Yuri Y.; Ni, Binbin; Zhelavskaya, Irina S.

    2017-01-01

    Electron flux in the Earth’s outer radiation belt is highly variable due to a delicate balance between competing acceleration and loss processes. It has been long recognized that Electromagnetic Ion Cyclotron (EMIC) waves may play a crucial role in the loss of radiation belt electrons. Previous theoretical studies proposed that EMIC waves may account for the loss of the relativistic electron population. However, recent observations showed that while EMIC waves are responsible for the signific...

  2. Space Weather Operation at KASI with Van Allen Probes Beacon Signals

    Science.gov (United States)

    Lee, J.; Kim, K. C.; Romeo, G.; Ukhorskiy, S.; Sibeck, D. G.; Kessel, R.; Mauk, B.; Giles, B. L.; Gu, B. J.; Lee, H.

    2016-12-01

    The Van Allen Probes are the first NASA mission broadcasting real time data in the Earth's radiation belts for space weather operation. Korea Astronomy and Space Science Institute has contributed in data receiving from Van Allen Probes with 7 m satellite tracking antenna since 2012 and used the data for space weather operation. It takes approximately 15 minutes from measurements to produce Level 1 data. In this study, we show how the Van Allen Probes data is handled for monitoring space weather conditions at geostationary orbit (GEO) by highlighting the Saint Patrick's Day storm occurred in 2015. During storm time, Probe-A data shows a significant increase of relativistic electron flux at L=3. The electrons diffuse out and results in large increase of > 2MeV electron flux on GEO. By monitoring the radial distribution of energetic electrons, we could predict relativistic electron enhancement events that potentially threat satellite operation. We conclude that the combination of Van Allen Probes and NOAA-GOES data can provide improved space environment information to geostationary satellite operators. In addition, the lessons learned from Van Allen Probes are that more data receiving sites are necessary and data connections should be monitored for operational data service.

  3. Unusual refilling of the slot region between the Van Allen radiation belts from November 2004 to January 2005

    Science.gov (United States)

    Yang, Xiaochao; Ni, Binbin; Yu, Jiang; Zhang, Yang; Zhang, Xiaoxin; Sun, Yueqiang

    2017-06-01

    Using multisatellite measurements, a uniquely strong and long-lived relativistic electron slot region refilling event from November 2004 to January 2005 is investigated. This event occurred under remarkable interplanetary and magnetospheric conditions. Both empirically modeled and observationally estimated plasmapause locations demonstrate that the plasmasphere eroded significantly prior to the enhancement phase of this event. The estimated diffusion coefficients indicate that the radial diffusion due to ULF waves is insufficient to account for the observed enhancement of slot region electrons. However, the diffusion coefficients evaluated using the distribution of chorus wave intensities derived from low-altitude POES electron observations indicate that the local acceleration induced by chorus could account for the major feature of observed enhancement outside the plasmapause. When the plasmasphere recovered, the refilled slot region was enveloped inside the plasmapause. In the plasmasphere, while the efficiency of hiss scattering loss increases by including unusually low frequency hiss waves, the interaction with hiss alone cannot fully explain the decay of this event, especially at higher energies, which suggests that electromagnetic ion cyclotron waves contribute to the relativistic electron loss process at such low L shells for this refilling event. Through a comprehensive analysis on the basis of data analyses and numerical calculations, the present study sheds light on the underlying physics responsible for the unusual slot refilling by relativistic electrons, which exhibits the complexity of both radiation belt electron dynamics and associated wave-particle interactions.

  4. New global loss model of energetic and relativistic electrons based on Van Allen Probes measurements

    OpenAIRE

    Ksenia Orlova; Yuri Shprits; Maria Spasojevic

    2016-01-01

    The Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) instrument on the Van Allen Probes provides a vast quantity of fully resolved wave measurements below L = 5.5, a critical region for radiation belt acceleration and loss. EMFISIS data show that plasmaspheric hiss waves can be observed at frequencies as low as 20 Hz and provide three-component magnetic field measurements that can be directly used for electron scattering calculations. Updated models of hiss proper...

  5. Wave-driven butterfly distribution of Van Allen belt relativistic electrons

    OpenAIRE

    Xiao, Fuliang; Yang, Chang; Su, Zhenpeng; Zhou, Qinghua; He, Zhaoguo; He, Yihua; Baker, D. N.; Spence, H. E.; Funsten, H. O.; Blake, J. B.

    2015-01-01

    Van Allen radiation belts consist of relativistic electrons trapped by Earth's magnetic field. Trapped electrons often drift azimuthally around Earth and display a butterfly pitch angle distribution of a minimum at 90° further out than geostationary orbit. This is usually attributed to drift shell splitting resulting from day–night asymmetry in Earth's magnetic field. However, direct observation of a butterfly distribution well inside of geostationary orbit and the origin of this phenomenon h...

  6. Gradual Diffusion and Punctuated Phase Space Density Enhancements of Highly Relativistic Electrons: Van Allen Probes Observations

    Science.gov (United States)

    Baker, D. N.; Jaynes, A. N.; Li, X.; Henderson, M. G.; Kanekal, S. G.; Reeves, G. D.; Spence, H. E.; Claudepierre, S. G.; Fennell, J. F.; Hudson, M. K.

    2014-01-01

    The dual-spacecraft Van Allen Probes mission has provided a new window into mega electron volt (MeV) particle dynamics in the Earth's radiation belts. Observations (up to E (is) approximately 10MeV) show clearly the behavior of the outer electron radiation belt at different timescales: months-long periods of gradual inward radial diffusive transport and weak loss being punctuated by dramatic flux changes driven by strong solar wind transient events. We present analysis of multi-MeV electron flux and phase space density (PSD) changes during March 2013 in the context of the first year of Van Allen Probes operation. This March period demonstrates the classic signatures both of inward radial diffusive energization and abrupt localized acceleration deep within the outer Van Allen zone (L (is) approximately 4.0 +/- 0.5). This reveals graphically that both 'competing' mechanisms of multi-MeV electron energization are at play in the radiation belts, often acting almost concurrently or at least in rapid succession.

  7. Multipoint observations of energetic electron injections with MMS and Van Allen Probes

    Science.gov (United States)

    Turner, D. L.; Fennell, J. F.; Blake, J. B.; Claudepierre, S. G.; Jaynes, A. N.; Baker, D. N.; Reeves, G. D.; Cohen, I. J.; Mauk, B.; Li, W.; Kletzing, C.; Torbert, R. B.; Burch, J. L.

    2016-12-01

    Between March and September of 2016, the orbits of NASA's Magnetospheric Multiscale (MMS) and Van Allen Probes missions overlapped on the dawn side of the near-equatorial magnetosphere, a region ideal for studying injections of 10s to 100s of keV electrons from the plasma sheet into the inner magnetosphere. During this period, the four MMS spacecraft also underwent a series of conjunctions with both Van Allen Probes, including several in which all six spacecraft were within 1 Earth radii of each other. From such multipoint observations, we investigate the connection between Earth's magnetotail and inner magnetosphere via dipolarization events and the energetic particle injections associated with them. Using the multipoint MMS data, we show how dipolarization fronts surge earthwards through the tail at 100s of kilometers per second, corresponding to strong electric fields that accelerate energetic particles and transport them earthward. Combining MMS with Van Allen Probes, we are able to estimate the transport of particles over larger spatial scales (macroscopic view) and multipoint observations of wave activity during close conjunctions (microscopic view). With such observations, we examine and report on new perspectives concerning the role of energetic electron injections as the seed populations of Earth's outer radiation belt electrons as well as the relationship between freshly injected electrons and chorus and ultra-low frequency (ULF) wave activity.

  8. Science Highlights from the RBSP-ECT Particle Instrument Suite on NASA's Van Allen Probes Mission

    Science.gov (United States)

    Spence, Harlan

    2014-05-01

    The NASA Van Allen Probes mission includes an instrument suite known as the Radiation Belt Storm Probes (RBSP) - Energetic Particle, Composition, and Thermal Plasma (ECT) suite. RBSP-ECT contains a well-proven complement of particle instruments to ensure the highest quality measurements ever made in the radiation belts and the inner magnetosphere. The coordinated RBSP-ECT particle measurements, analyzed in combination with fields and waves observations and state of-the-art theory and modeling, provide new understanding on the acceleration, global distribution, and variability of radiation belt electrons and ions, key science objectives of NASA's Living With a Star program and the Van Allen Probes mission. The RBSP-ECT suite consists of three highly-coordinated instruments: the Helium Oxygen Proton Electron (HOPE) spectrometer, the Magnetic Electron Ion Spectrometer (MagEIS), and the Relativistic Electron Proton Telescope (REPT). Collectively these three instrument types cover comprehensively the full electron and ion spectra from one eV to 10's of MeV with sufficient energy resolution, pitch angle coverage and resolution, and with composition measurements in the critical energy range up to 50 keV and also from a few to 50 MeV/nucleon. All three instruments are based on measurement techniques proven in the radiation belts, then optimized to provide unambiguous separation of ions and electrons and clean energy responses even in the presence of extreme penetrating background environments. In this presentation, we summarize overall ECT science goals and then show scientific results derived from the ECT suite on the dual Van Allen Probes spacecraft to date. Mission operations began only in late October 2012, and we have now achieved significant results. Results presented here will include substantial progress toward resolving primary Van Allen Probes science targets, such as: the relative role of localized acceleration versus transport-generated particle acceleration

  9. Early Science Results From the NASA Van Allen Probes Mission RBSP-ECT Instrument Suite

    Science.gov (United States)

    Spence, Harlan; Reeves, Geoff; Rbspect Team

    2013-04-01

    The NASA Van Allen Probes mission includes an instrument suite known as the Radiation Belt Storm Probes (RBSP) - Energetic Particle, Composition, and Thermal Plasma (ECT) suite. RBSP-ECT contains a well-proven complement of particle instruments to ensure the highest quality measurements ever made in the radiation belts and the inner magnetosphere. The coordinated RBSP-ECT particle measurements, analyzed in combination with fields and waves observations and state of-the-art theory and modeling, provide new understanding on the acceleration, global distribution, and variability of radiation belt electrons and ions, key science objectives of NASA's Living With a Star program and the Van Allen Probes mission. The RBSP-ECT suite consists of three highly-coordinated instruments: the Helium Oxygen Proton Electron (HOPE) spectrometer, the Magnetic Electron Ion Spectrometer (MagEIS), and the Relativistic Electron Proton Telescope (REPT). Collectively these three instrument types cover comprehensively the full electron and ion spectra from one eV to 10's of MeV with sufficient energy resolution, pitch angle coverage and resolution, and with composition measurements in the critical energy range up to 50 keV and also from a few to 50 MeV/nucleon. All three instruments are based on measurement techniques proven in the radiation belts, then optimized to provide unambiguous separation of ions and electrons and clean energy responses even in the presence of extreme penetrating background environments. In this presentation, we summarize overall ECT science goals and then show early scientific results derived from the ECT suite on the dual Van Allen Probes spacecraft. Mission operations began only in late October 2012, but we have already achieved significant early results. Results presented here will include substantial progress toward resolving primary Van Allen Probes science targets, such as: the relative role of localized acceleration versus transport-generated particle

  10. Cross-scale observations of the 2015 St. Patrick's day storm: THEMIS, Van Allen Probes, and TWINS

    Science.gov (United States)

    Goldstein, J.; Angelopoulos, V.; De Pascuale, S.; Funsten, H. O.; Kurth, W. S.; LLera, K.; McComas, D. J.; Perez, J. D.; Reeves, G. D.; Spence, H. E.; Thaller, S. A.; Valek, P. W.; Wygant, J. R.

    2017-01-01

    We present cross-scale magnetospheric observations of the 17 March 2015 (St. Patrick's Day) storm, by Time History of Events and Macroscale Interactions during Substorms (THEMIS), Van Allen Probes (Radiation Belt Storm Probes), and Two Wide-angle Imaging Neutral-atom Spectrometers (TWINS), plus upstream ACE/Wind solar wind data. THEMIS crossed the bow shock or magnetopause 22 times and observed the magnetospheric compression that initiated the storm. Empirical models reproduce these boundary locations within 0.7 RE. Van Allen Probes crossed the plasmapause 13 times; test particle simulations reproduce these encounters within 0.5 RE. Before the storm, Van Allen Probes measured quiet double-nose proton spectra in the region of corotating cold plasma. About 15 min after a 0605 UT dayside southward turning, Van Allen Probes captured the onset of inner magnetospheric convection, as a density decrease at the moving corotation-convection boundary (CCB) and a steep increase in ring current (RC) proton flux. During the first several hours of the storm, Van Allen Probes measured highly dynamic ion signatures (numerous injections and multiple spectral peaks). Sustained convection after ˜1200 UT initiated a major buildup of the midnight-sector ring current (measured by RBSP A), with much weaker duskside fluxes (measured by RBSP B, THEMIS a and THEMIS d). A close conjunction of THEMIS d, RBSP A, and TWINS 1 at 1631 UT shows good three-way agreement in the shapes of two-peak spectra from the center of the partial RC. A midstorm injection, observed by Van Allen Probes and TWINS at 1740 UT, brought in fresh ions with lower average energies (leading to globally less energetic spectra in precipitating ions) but increased the total pressure. The cross-scale measurements of 17 March 2015 contain significant spatial, spectral, and temporal structure.

  11. Energetic Proton Spectra Measured by the Van Allen Probes

    Science.gov (United States)

    Summers, Danny; Shi, Run; Engebretson, Mark J.; Oksavik, Kjellmar; Manweiler, Jerry W.; Mitchell, Donald G.

    2017-10-01

    We test the hypothesis that pitch angle scattering by electromagnetic ion cyclotron (EMIC) waves can limit ring current proton fluxes. For two chosen magnetic storms, during 17-20 March 2013 and 17-20 March 2015, we measure proton energy spectra in the region 3 ≤ L ≤ 6 using the RBSPICE-B instrument on the Van Allen Probes. The most intense proton spectra are observed to occur during the recovery periods of the respective storms. Using proton precipitation data from the POES (NOAA and MetOp) spacecraft, we deduce that EMIC wave action was prevalent at the times and L-shell locations of the most intense proton spectra. We calculate limiting ring current proton energy spectra from recently developed theory. Comparisons between the observed proton energy spectra and the theoretical limiting spectra show reasonable agreement. We conclude that the measurements of the most intense proton spectra are consistent with self-limiting by EMIC wave scattering.

  12. Van Allen Probe Charging During the St. Patrick's Day Event

    Science.gov (United States)

    Parker, L. Neergaard; Minow, J. I.

    2015-01-01

    The geomagnetic storms on and around March 17, 2015 marked the largest storms seen in the declining phase of the solar cycle to date. We use the Helium Oxygen Proton Electron (HOPE) mass spectrometer on board the Van Allen Probe - A and B satellites to study in detail the charging effects seen on these spacecraft during this time. Ion particle flux data provides information on the magnitude of the charging events using the ion line charging signature due to low energy ions accelerated by the spacecraft potential. Electron flux observations are used to correlate the charging environment with variations in spacecraft potential through the event. We also investigate the density and temperature of ions and electrons during the time of the charging event.

  13. Effect of the orbital debris environment on the high-energy Van Allen proton belt

    Science.gov (United States)

    Konradi, Andrei

    1988-01-01

    The lifetimes of high-energy (greater than 55 MeV) protons in the Van Allen radiation belt are calculated, assuming that in time the protons will collide with and be absorbed by particulate orbiting material. The calculations are based on the NASA/DoD Civil Needs Database for orbital debris (Gaines, 1966) and moderate assumptions of future space traffic. It is found that the lifetimes of high-energy protons below 1500 km will decrease, leading to a noticeable redution in their fluxes.

  14. The Flux and Energy Spectra of the Protons in the Inner Van Allen Belt

    Science.gov (United States)

    Naugle, John E.; Kniffen, Donald A.

    1961-01-01

    A cylindrical stack of G-5 nuclear emulsions housed in the payload section of a four-stage research rocket was flown into the northern edge of the inner Van Allen belt on September 19, 1960. The experimental design permitted, for the first time, measurements of the particle fluxes and energy spectra as functions of position along the rocket trajectory. Eight points along the trajectory have been selected for analysis. Results are presented herein for three of these points, and they are discussed in the light of various theories on the trapped radiation.

  15. Explaining the diverse response of ultra-relativistic Van Allen belt electrons to solar wind forcing

    Science.gov (United States)

    Mann, Ian; Ozeke, Louis; Murphy, Kyle; Claudepierre, Seth; Rae, Jonathan; Milling, David; Kale, Andy; Baker, Daniel

    2017-04-01

    The NASA Van Allen Probes have opened a new window on the dynamics of ultra-relativistic electrons in the Van Allen radiation belts. Under different solar wind forcing the outer belt is seen to respond in a variety of apparently diverse and sometimes remarkable ways. For example, sometimes a third radiation belt is carved out (e.g., September 2012), or the belts can remain depleted for 10 days or more (September 2014). More usually there is a sequential response of a strong and sometimes rapid depletion followed by a re-energization, the latter increasing outer belt electron flux by orders of magnitude on hour timescales during some of the strongest storms of this solar cycle (e.g., March 2013, March 2015). Such dynamics also appear to be always bounded at low-L by an apparently impenetrable barrier below L 2.8 through which ultra-relativistic electrons do not penetrate. Many studies in the Van Allen Probes era have sought explanations for these apparently diverse features, often incorporating the effects from multiple plasma waves. In contrast, we show how this apparently diverse behaviour can instead be explained by one simple dominant process: ULF wave radial transport. Once ULF wave transport rates are accurately specified by observations, and coupled to the dynamical variation of the outer boundary condition at the edge of the outer belt, the observed diverse responses can all be explained. In order to get good agreement with observations, the modeling reveals the importance of still currently unexplained fast loss in the main phase which decouples pre- and post-storm ultra-relativistic electron flux on hour timescales. Similarly, varying plasmasheet source populations are seen to be of critical importance such that near-tail dynamics likely play a crucial role in Van Allen belt dynamics. Nonetheless, simple models incorporating accurate transport rates derived directly from ULF wave measurements are shown to provide a single natural and compelling explanation

  16. Magnetohydrodynamic modeling of three Van Allen Probes storms in 2012 and 2013

    Directory of Open Access Journals (Sweden)

    J. Paral

    2015-08-01

    Full Text Available Coronal mass ejection (CME-shock compression of the dayside magnetopause has been observed to cause both prompt enhancement of radiation belt electron flux due to inward radial transport of electrons conserving their first adiabatic invariant and prompt losses which at times entirely eliminate the outer zone. Recent numerical studies suggest that enhanced ultra-low frequency (ULF wave activity is necessary to explain electron losses deeper inside the magnetosphere than magnetopause incursion following CME-shock arrival. A combination of radial transport and magnetopause shadowing can account for losses observed at radial distances into L = 4.5, well within the computed magnetopause location. We compare ULF wave power from the Electric Field and Waves (EFW electric field instrument on the Van Allen Probes for the 8 October 2013 storm with ULF wave power simulated using the Lyon–Fedder–Mobarry (LFM global magnetohydrodynamic (MHD magnetospheric simulation code coupled to the Rice Convection Model (RCM. Two other storms with strong magnetopause compression, 8–9 October 2012 and 17–18 March 2013, are also examined. We show that the global MHD model captures the azimuthal magnetosonic impulse propagation speed and amplitude observed by the Van Allen Probes which is responsible for prompt acceleration at MeV energies reported for the 8 October 2013 storm. The simulation also captures the ULF wave power in the azimuthal component of the electric field, responsible for acceleration and radial transport of electrons, at frequencies comparable to the electron drift period. This electric field impulse has been shown to explain observations in related studies (Foster et al., 2015 of electron acceleration and drift phase bunching by the Energetic Particle, Composition, and Thermal Plasma Suite (ECT instrument on the Van Allen Probes.

  17. An extreme distortion of the Van Allen belt arising from the 'Hallowe'en' solar storm in 2003.

    Science.gov (United States)

    Baker, D N; Kanekal, S G; Li, X; Monk, S P; Goldstein, J; Burch, J L

    2004-12-16

    The Earth's radiation belts--also known as the Van Allen belts--contain high-energy electrons trapped on magnetic field lines. The centre of the outer belt is usually 20,000-25,000 km from Earth. The region between the belts is normally devoid of particles, and is accordingly favoured as a location for spacecraft operation because of the benign environment. Here we report that the outer Van Allen belt was compressed dramatically by a solar storm known as the 'Hallowe'en storm' of 2003. From 1 to 10 November, the outer belt had its centre only approximately 10,000 km from Earth's equatorial surface, and the plasmasphere was similarly displaced inwards. The region between the belts became the location of high particle radiation intensity. This remarkable deformation of the entire magnetosphere implies surprisingly powerful acceleration and loss processes deep within the magnetosphere.

  18. An extreme distortion of the Van Allen belt arising from the `Hallowe'en' solar storm in 2003

    Science.gov (United States)

    Baker, D. N.; Kanekal, S. G.; Li, X.; Monk, S. P.; Goldstein, J.; Burch, J. L.

    2004-12-01

    The Earth's radiation belts-also known as the Van Allen belts-contain high-energy electrons trapped on magnetic field lines. The centre of the outer belt is usually 20,000-25,000km from Earth. The region between the belts is normally devoid of particles, and is accordingly favoured as a location for spacecraft operation because of the benign environment. Here we report that the outer Van Allen belt was compressed dramatically by a solar storm known as the `Hallowe'en storm' of 2003. From 1 to 10 November, the outer belt had its centre only ~10,000km from Earth's equatorial surface, and the plasmasphere was similarly displaced inwards. The region between the belts became the location of high particle radiation intensity. This remarkable deformation of the entire magnetosphere implies surprisingly powerful acceleration and loss processes deep within the magnetosphere.

  19. EMIC wave scale size in the inner magnetosphere: Observations from the dual Van Allen Probes

    Science.gov (United States)

    Blum, L. W.; Bonnell, J. W.; Agapitov, O.; Paulson, K.; Kletzing, C.

    2017-02-01

    Estimating the spatial scales of electromagnetic ion cyclotron (EMIC) waves is critical for quantifying their overall scattering efficiency and effects on thermal plasma, ring current, and radiation belt particles. Using measurements from the dual Van Allen Probes in 2013-2014, we characterize the spatial and temporal extents of regions of EMIC wave activity and how these depend on local time and radial distance within the inner magnetosphere. Observations are categorized into three types—waves observed by only one spacecraft, waves measured by both spacecraft simultaneously, and waves observed by both spacecraft with some time lag. Analysis reveals that dayside (and H+ band) EMIC waves more frequently span larger spatial areas, while nightside (and He+ band) waves are more often localized but can persist many hours. These investigations give insight into the nature of EMIC wave generation and support more accurate quantification of their effects on the ring current and outer radiation belt.

  20. Van Allen Probe Measurements of the Scale Sizes and Detailed Properties of EMIC Waves

    Science.gov (United States)

    Blum, L. W.; Bonnell, J. W.; Agapitov, O. V.; Mozer, F.

    2016-12-01

    Electromagnetic ion cyclotron (EMIC) waves are able to resonate with MeV electrons and cause precipitation loss of radiation belt electrons. EMIC waves can provide a strong source of electron pitch angle diffusion, but the waves are often quite localized - thus the spatial extents of these waves can have a large effect on their overall scattering efficiency. Using measurements from the dual Van Allen Probes, we characterize the spatial and temporal extents of EMIC wave active regions and how these depend on local time, radial distance, and wave properties (e.g. amplitude, frequency). Analysis of the detailed wave properties is also performed; we estimate the active region and coherence scales of EMIC waves and examine nonlinear features and parallel electric fields present in some events. These investigations help determine the nature of EMIC wave-particle interactions and support more accurate quantification of their effects on the outer radiation belt.

  1. Observation of Chorus Waves by the Van Allen Probes: Dependence on Solar Wind Parameters and Scale Size

    Science.gov (United States)

    Aryan, Homayon; Sibeck, David; Balikhin, Michael; Agapitov, Oleksiy; Kletzing, Craig

    2016-01-01

    Highly energetic electrons in the Earths Van Allen radiation belts can cause serious damage to spacecraft electronic systems and affect the atmospheric composition if they precipitate into the upper atmosphere. Whistler mode chorus waves have attracted significant attention in recent decades for their crucial role in the acceleration and loss of energetic electrons that ultimately change the dynamics of the radiation belts. The distribution of these waves in the inner magnetosphere is commonly presented as a function of geomagnetic activity. However, geomagnetic indices are nonspecific parameters that are compiled from imperfectly covered ground based measurements. The present study uses wave data from the two Van Allen Probes to present the distribution of lower band chorus waves not only as functions of single geomagnetic index and solar wind parameters but also as functions of combined parameters. Also the current study takes advantage of the unique equatorial orbit of the Van Allen Probes to estimate the average scale size of chorus wave packets, during close separations between the two spacecraft, as a function of radial distance, magnetic latitude, and geomagnetic activity, respectively. Results show that the average scale size of chorus wave packets is approximately 13002300 km. The results also show that the inclusion of combined parameters can provide better representation of the chorus wave distributions in the inner magnetosphere and therefore can further improve our knowledge of the acceleration and loss of radiation belt electrons.

  2. Observation of chorus waves by the Van Allen Probes: dependence on solar wind parameters and scale size

    Science.gov (United States)

    Aryan, H.; Sibeck, D. G.; Balikhin, M. A.; Agapitov, O. V.; Kletzing, C.

    2016-12-01

    Highly energetic electrons in the Earth's Van Allen radiation belts can cause serious damage to spacecraft electronic systems, and affect the atmospheric composition if they precipitate into the upper atmosphere. Whistler mode chorus waves have attracted significant attention in recent decades for their crucial role in the acceleration and loss of energetic electrons that ultimately change the dynamics of the radiation belts. The distribution of these waves in the inner magnetosphere is commonly presented as a function of geomagnetic activity. However, geomagnetic indices are non-specific parameters that are compiled from imperfectly covered ground based measurements. The present study uses wave data from the two Van Allen Probes to present the distribution of lower band chorus waves not only as functions of single geomagnetic index and solar wind parameters, but also as functions of combined parameters. Also the current study takes advantage of the unique equatorial orbit of the Van Allen Probes to estimate the average scale size of chorus wave packets, during close separations between the two spacecraft, as a function of radial distance, magnetic latitude, and geomagnetic activity respectively. Results show that the average scale size of chorus wave packets is approximately 1300 - 2300 km. The results also show that the inclusion of combined parameters can provide better representation of the chorus wave distributions in the inner magnetosphere, and therefore can further improve our knowledge of the acceleration and loss of radiation belt electrons.

  3. Synthetic Empirical Chorus Wave Model From Combined Van Allen Probes and Cluster Statistics

    Science.gov (United States)

    Agapitov, O. V.; Mourenas, D.; Artemyev, A. V.; Mozer, F. S.; Hospodarsky, G.; Bonnell, J.; Krasnoselskikh, V.

    2018-01-01

    Chorus waves are among the most important natural electromagnetic emissions in the magnetosphere as regards to their potential effects on electron dynamics. They can efficiently accelerate or precipitate electrons trapped in the outer radiation belt, producing either fast increases of relativistic particle fluxes or auroras at high latitudes. Accurately modeling their effects, however, requires detailed models of their wave power and obliquity distribution as a function of geomagnetic activity in a particularly wide spatial domain, rarely available based solely on the statistics obtained from only one satellite mission. Here we seize the opportunity of synthesizing data from the Van Allen Probes and Cluster spacecraft to provide a new comprehensive chorus wave model in the outer radiation belt. The respective spatial coverages of these two missions are shown to be especially complementary and further allow a good cross calibration in the overlap domain. We used 4 years (2012-2016) of Van Allen Probes VLF data in the chorus frequency range up to 12 kHz at latitudes lower than 20°, combined with 10 years of Cluster VLF measurements up to 4 kHz in order to provide a full coverage of geomagnetic latitudes up to 45° in the chorus frequency range 0.1fce-0.8fce. The resulting synthetic statistical model of chorus wave amplitude, obliquity, and frequency is presented in the form of analytical functions of latitude and Kp in three different magnetic local time sectors and for two ranges of L shells outside the plasmasphere. Such a synthetic and reliable chorus model is crucially important for accurately modeling global acceleration and loss of electrons over the long run in the outer radiation belt, allowing a comprehensive description of electron flux variations over a very wide energy range.

  4. Empirical modeling of whistler-mode chorus and hiss in the inner magnetosphere using measurements of the Van Allen Probes

    Science.gov (United States)

    Santolik, Ondrej; Hospodarsky, George B.; Kurth, William S.; Kletzing, Craig A.

    2017-04-01

    Recent studies of the dynamics of energetic in the Earth radiation belts show that whistler mode chorus and hiss play an important role. This especially concerns the slot region and the outer Van Allen radiation belts where empirical wave models are used as a component of existing approaches. We analyze these whistler-mode waves using a database of survey measurements of the Waves instruments of the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) onboard the Van Allen Probes. We use multicomponent data to estimate wave polarization and propagation parameters and to asses variability of wave amplitudes as a function of position and geomagnetic activity. Four years of Van Allen Probes EMFISIS Waves survey data give a good orbital coverage in L, latitude, and MLT. Average amplitudes increase with geomagnetic activity but the observed amplitude variations are still much larger than this effect. Statistics of planarity and wave vector directions are strongly linked to wave amplitudes. The planarity of magnetic field polarization is high for strong chorus and its wave normal directions are well defined. We obtain low planarities of the magnetic field polarization for a substantial fraction of plasmaspheric hiss. This invalidates the assumption of a single plane wave for these whistler mode emissions.

  5. Evidence for Nonlinear VLF Wave Physics from Van Allen Probe Data

    Science.gov (United States)

    Crabtree, C. E.; Tejero, E. M.; Ganguli, G.; Hospodarsky, G. B.; Kletzing, C.

    2015-12-01

    VLF waves in the whistler mode branch in the Earth's radiation belts play a critical role in both the acceleration and loss of energetic electrons. VLF waves are often observed with magnetic field amplitudes that are a significant fraction of the background magnetic field suggesting that nonlinear effects may be important. We develop new Bayesian time-series analysis tools to investigate magnetic and electric field data from the EMFISIS instrument on board the Van Allen Probes. We also validate the analysis techniques through laboratory experiments. We apply these tools to Chorus waves to show that the picture of a single coherent plane wave is insufficient to explain EMFISIS data and that nonlinear collective wave interactions play an important role in moderating Chorus wave growth. We also apply these techniques to show that nonlinear induced scattering by thermal electrons can play a significant role in controlling the propagation of large amplitude lightning generated whistlers inside the plasmasphere.

  6. Statistical distribution of EMIC wave spectra: Observations from Van Allen Probes

    Science.gov (United States)

    Zhang, X.-J.; Li, W.; Thorne, R. M.; Angelopoulos, V.; Bortnik, J.; Kletzing, C. A.; Kurth, W. S.; Hospodarsky, G. B.

    2016-12-01

    It has been known that electromagnetic ion cyclotron (EMIC) waves can precipitate ultrarelativistic electrons through cyclotron resonant scattering. However, the overall effectiveness of this mechanism has yet to be quantified, because it is difficult to obtain the global distribution of EMIC waves that usually exhibit limited spatial presence. We construct a statistical distribution of EMIC wave frequency spectra and their intensities based on Van Allen Probes measurements from September 2012 to December 2015. Our results show that as the ratio of plasma frequency over electron gyrofrequency increases, EMIC wave power becomes progressively dominated by the helium band. There is a pronounced dawn-dusk asymmetry in the wave amplitude and the frequency spectrum. The frequency spectrum does not follow the commonly used single-peak Gaussian function. Incorporating these realistic EMIC wave frequency spectra into radiation belt models is expected to improve the quantification of EMIC wave scattering effects in ultrarelativistic electron dynamics.

  7. Wave-driven butterfly distribution of Van Allen belt relativistic electrons.

    Science.gov (United States)

    Xiao, Fuliang; Yang, Chang; Su, Zhenpeng; Zhou, Qinghua; He, Zhaoguo; He, Yihua; Baker, D N; Spence, H E; Funsten, H O; Blake, J B

    2015-10-05

    Van Allen radiation belts consist of relativistic electrons trapped by Earth's magnetic field. Trapped electrons often drift azimuthally around Earth and display a butterfly pitch angle distribution of a minimum at 90° further out than geostationary orbit. This is usually attributed to drift shell splitting resulting from day-night asymmetry in Earth's magnetic field. However, direct observation of a butterfly distribution well inside of geostationary orbit and the origin of this phenomenon have not been provided so far. Here we report high-resolution observation that a unusual butterfly pitch angle distribution of relativistic electrons occurred within 5 Earth radii during the 28 June 2013 geomagnetic storm. Simulation results show that combined acceleration by chorus and magnetosonic waves can successfully explain the electron flux evolution both in the energy and butterfly pitch angle distribution. The current provides a great support for the mechanism of wave-driven butterfly distribution of relativistic electrons.

  8. Van Allen Probes observations of oxygen cyclotron harmonic waves in the inner magnetosphere

    Science.gov (United States)

    Usanova, M.; Malaspina, D.; Jaynes, A. N.; Bruder, R.; Mann, I. R.; Wygant, J. R.; Ergun, R.

    2016-12-01

    Waves with frequencies in the vicinity of the oxygen cyclotron frequency and its harmonics have been regularly observed on the Van Allen Probes satellites during geomagnetic storms. We focus on properties of these waves and present events from the main phase of two storms on November 1, 2012 and March 17, 2013 and associated dropouts of few MeV electron fluxes. They are electromagnetic, in the frequency range 0.5 - several Hz, and amplitude 0.1- a few nT in magnetic and 0.1- a few mV/m in electric field, with both the wave velocity and the Poynting vector directed almost parallel to the background magnetic field. These properties are very similar to those of electromagnetic ion cyclotron (EMIC) waves, which are believed to contribute to loss of ring current ions and radiation belt electrons and therefore can be also important for inner magnetosphere dynamics.

  9. New results from the Colorado CubeSat and comparison with Van Allen Probes data

    Science.gov (United States)

    Li, X.

    2013-05-01

    The Colorado Student Space Weather Experiment (CSSWE) is a 3-unit (10cm x 10cm x 30cm) CubeSat mission funded by the NSF, launched into a highly inclined (650) low-Earth (490km x 790km) orbit on 09/13/12 as a secondary payload under NASA's Educational Launch of Nanosatellites (ELaNa) program. CSSWE contains a single science payload, the Relativistic Electron and Proton Telescope integrated little experiment (REPTile), which is a simplified and miniaturized version of the Relativistic Electron and Proton Telescope (REPT) built at the Laboratory for Atmospheric and Space Physics (LASP) of University of Colorado for NASA/Van Allen Probes mission, which consists of two identical spacecraft, launched on 08/30/12, that traverse the heart of the radiation belts in a low inclination (100) orbit. REPTile is designed to measure the directional differential flux of protons ranging from 9 to 40 MeV and electrons from 0.5 to >3.3 MeV. Three-month science mission (full success) was completed on 1/05/13. We are now into the extended mission phase, focusing on data analysis and modeling. REPTile measures a fraction of the total population that has small enough equatorial pitch angles to reach the altitude of CSSWE, thus measuring the precipitating population as well as the trapped population. These measurements are critical for understanding the loss of outer radiation belt electrons. New results from CSSWE and comparison with Van Allen Probes data will be presented. The CSSWE is also an ideal class project, involving over 65 graduate and undergraduate students and providing training for the next generation of engineers and scientists over the full life-cycle of a satellite project.

  10. EMIC waves covering wide L shells: MMS and Van Allen Probes observations

    Science.gov (United States)

    Yu, Xiongdong; Yuan, Zhigang; Huang, Shiyong; Wang, Dedong; Li, Haimeng; Qiao, Zheng; Yao, Fei

    2017-07-01

    During 04:45:00-08:15:00 UT on 13 September in 2015, a case of Electromagnetic ion cyclotron (EMIC) waves covering wide L shells (L = 3.6-9.4), observed by the Magnotospheric Multiscale 1 (MMS1) are reported. During the same time interval, EMIC waves observed by Van Allen Probes A (VAP-A) only occurred just outside the plasmapause. As the Van Allen Probes moved outside into a more tenuous plasma region, no intense waves were observed. Combined observations of MMS1 and VAP-A suggest that in the terrestrial magnetosphere, an appropriately dense background plasma would make contributions to the growth of EMIC waves in lower L shells, while the ion anisotropy, driven by magnetospheric compression, might play an important role in the excitation of EMIC waves in higher L shells. These EMIC waves are observed over wide L shells after three continuous magnetic storms, which suggests that these waves might obtain their free energy from those energetic ions injected during storm times. These EMIC waves should be included in radiation belt modeling, especially during continuous magnetic storms. Moreover, two-band structures separated in frequencies by local He2+ gyrofrequencies were observed in large L shells (L > 6), implying sufficiently rich solar wind origin He2+ likely in the outer ring current. It is suggested that multiband-structured EMIC waves can be used to trace the coupling between solar wind and the magnetosphere.tract type="synopsis">le type="main">Plain Language SummaryThe spatial distribution of EMIC waves is an opening question. With combined observations of MMS and Van Allen Probes, this paper has reported EMIC waves covering wide L shells. Moreover, two-band structures separated in frequencies by local He2+ gyrofrequencies were observed in large L shells (L > 6), implying sufficiently rich solar wind origin He2+ likely in the outer ring current. The result is helpful to revealing the spatial distribution and role of He2+ in excitation of EMIC waves.

  11. Near?Earth injection of MeV electrons associated with intense dipolarization electric fields: Van Allen Probes observations

    OpenAIRE

    Dai, Lei; Wang, Chi; Duan, Suping; He, Zhaohai; Wygant, John R.; Cattell, Cynthia A.; Tao, Xin; Su, Zhenpeng; Kletzing, Craig; Baker, Daniel N.; Li, Xinlin; Malaspina, David; Blake, J. Bernard; Fennell, Joseph; Claudepierre, Seth

    2015-01-01

    Abstract Substorms generally inject tens to hundreds of keV electrons, but intense substorm electric fields have been shown to inject MeV electrons as well. An intriguing question is whether such MeVelectron injections can populate the outer radiation belt. Here we present observations of a substorm injection of MeV electrons into the inner magnetosphere. In the premidnight sector at L ? 5.5, Van Allen Probes (Radiation Belt Storm Probes)?A observed a large dipolarization electric field (50?m...

  12. Precipitation of relativistic electrons of the Van Allen belts into the proton aurora

    Energy Technology Data Exchange (ETDEWEB)

    Jordanova, Vania K [Los Alamos National Laboratory; Miyoshi, Y [NAGOYA UNIV; Sakaguchi, K [NAGOYA UNIV; Shiokawa, K [NAGOYA UNIV; Evans, D S [SEC/NOAA; Albert, Jay [AFRL; Connors, M [UNIV OF ATHABASCA

    2008-01-01

    The Van Allen electron belts consist of two regions encircling the earth in which relativistic electrons are trapped in the earth's magnetic field. Populations of relativistic electrons in the Van Allen belts vary greatly with geomagnetic disturbance and they are a major source of damage to space vehicles. In order to know when and by how much these populations of relativistic electrons increase, it is important to elucidate not only the cause of acceleration of relativistic electrons but also the cause of their loss from the Van Allen belts. Here we show the first evidence that left-hand polarized electromagnetic ion cyclotron (EMIC) plasma waves can cause the loss of relativistic electrons into the atmosphere, on the basis of results of an excellent set of ground and satellite observations showing coincident precipitation of ions with energies of tens of keV and of relativistic electrons into an isolated proton aurora. The proton aurora was produced by precipitation of ions with energies of tens of keV due to EMIC waves near the plasma pause, which is a manifestation of wave-particle interactions. These observations clarify that ions with energies of tens of keV affect the evolution of relativistic electrons in the Van Allen belts via parasitic resonance with EMIC waves, an effect that was first theoretically predicted in the early 1970's.

  13. Van Allen Probes observations of unusually low frequency whistler mode waves observed in association with moderate magnetic storms: Statistical study

    OpenAIRE

    Cattell, C. A.; Breneman, A. W.; Thaller, S. A.; Wygant, J. R.; Kletzing, C. A.; Kurth, W. S.

    2015-01-01

    Abstract We show the first evidence for locally excited chorus at frequencies below 0.1?f ce (electron cyclotron frequency) in the outer radiation belt. A statistical study of chorus during geomagnetic storms observed by the Van Allen Probes found that frequencies are often dramatically lower than expected. The frequency at peak power suddenly stops tracking the equatorial 0.5?f ce and f/f ce decreases rapidly, often to frequencies well below 0.1?f ce (in situ and mapped to equator). These ve...

  14. Observations Directly Linking Relativistic Electron Microbursts to Whistler Mode Chorus: Van Allen Probes and FIREBIRD II

    Science.gov (United States)

    Breneman, A. W.; Crew, A.; Sample, J.; Klumpar, D.; Johnson, A.; Agapitov, O.; Shumko, M.; Turner, D. L.; Santolik, O.; Wygant, J. R.; Cattell, C. A.; Thaller, S.; Blake, B.; Spence, H.; Kletzing, C. A.

    2017-11-01

    We present observations that provide the strongest evidence yet that discrete whistler mode chorus packets cause relativistic electron microbursts. On 20 January 2016 near 1944 UT the low Earth orbiting CubeSat Focused Investigations of Relativistic Electron Bursts: Intensity, Range, and Dynamics (FIREBIRD II) observed energetic microbursts (near L = 5.6 and MLT = 10.5) from its lower limit of 220 keV, to 1 MeV. In the outer radiation belt and magnetically conjugate, Van Allen Probe A observed rising-tone, lower band chorus waves with durations and cadences similar to the microbursts. No other waves were observed. This is the first time that chorus and microbursts have been simultaneously observed with a separation smaller than a chorus packet. A majority of the microbursts do not have the energy dispersion expected for trapped electrons bouncing between mirror points. This confirms that the electrons are rapidly (nonlinearly) scattered into the loss cone by a coherent interaction with the large amplitude (up to ˜900 pT) chorus. Comparison of observed time-averaged microburst flux and estimated total electron drift shell content at L = 5.6 indicate that microbursts may represent a significant source of energetic electron loss in the outer radiation belt.

  15. Van Allen Probes observations of whistler-mode chorus with long-lived oscillating tones

    Science.gov (United States)

    Gao, Zhonglei; Su, Zhenpeng; Chen, Lunjin; Zheng, Huinan; Wang, Yuming; Wang, Shui

    2017-06-01

    Whistler-mode chorus plays an important role in the radiation belt electron dynamics. In the frequency-time spectrogram, chorus often appears as a hiss-like band and/or a series of short-lived (up to ˜1 s) discrete elements. Here we present some rarely reported chorus emissions with long-lived (up to 25 s) oscillating tones observed by the Van Allen Probes in the dayside (MLT ˜9-14) midlatitude (|MLAT|>15°) region. An oscillating tone can behave either regularly or irregularly and can even transform into a nearly constant tone (with a relatively narrow frequency sweep range). We suggest that these highly coherent oscillating tones were generated naturally rather than being related to some artificial VLF transmitters. Possible scenarios for the generation of the oscillating tone chorus are as follows: (1) being nonlinearly triggered by the accompanying hiss-like bands or (2) being caused by the modulation of the wave source. The details of the generation and evolution of such a long-lived oscillating tone chorus need to be investigated both theoretically and experimentally in the future.

  16. Chorus whistler wave source scales as determined from multipoint Van Allen Probe measurements

    Science.gov (United States)

    Agapitov, Oleksiy; Mozer, Forrest; Blum, Lauren; Bonnell, John; Wygant, John

    2017-04-01

    Whistler-mode chorus waves are a particularly important process in outer radiation belt dynamics due to their key role in controlling the acceleration and scattering of electrons over a very wide energy range. The key parameters for both nonlinear and quasi-linear treatment of wave-particle interactions are the temporal and spatial scales of the wave source region and coherence of the wave field perturbations. Both of these scales, the source scale and the coherence scale, are not well-established experimentally, mostly because of a lack of VLF waveform data. We present an unprecedentedly long interval of coordinated VLF waveform measurements (sampled at 16384 s-1) aboard the two Van Allen Probes spacecraft. The cross spacecraft distance varied from about 100 up to 5000 km. Using time-domain correlation techniques, the chorus source regions have been determined to be about 450-550 km for upper band chorus waves with amplitude less than 100 pT and up to 1000 km for larger amplitude lower band chorus waves. The ratio between wave amplitudes measured on the two spacecraft is also examined and reveals that the wave amplitude distribution within a region of chorus element generation can be well approximated by the Gaussian with the characteristic distance r0 around 300 km. This work was supported by the JHU/APL contract 922613 (RBSP-EFW) and NASA Grant NNX16AF85G.

  17. A long-lived relativistic electron storage ring embedded in Earth's outer Van Allen belt.

    Science.gov (United States)

    Baker, D N; Kanekal, S G; Hoxie, V C; Henderson, M G; Li, X; Spence, H E; Elkington, S R; Friedel, R H W; Goldstein, J; Hudson, M K; Reeves, G D; Thorne, R M; Kletzing, C A; Claudepierre, S G

    2013-04-12

    Since their discovery more than 50 years ago, Earth's Van Allen radiation belts have been considered to consist of two distinct zones of trapped, highly energetic charged particles. The outer zone is composed predominantly of megaelectron volt (MeV) electrons that wax and wane in intensity on time scales ranging from hours to days, depending primarily on external forcing by the solar wind. The spatially separated inner zone is composed of commingled high-energy electrons and very energetic positive ions (mostly protons), the latter being stable in intensity levels over years to decades. In situ energy-specific and temporally resolved spacecraft observations reveal an isolated third ring, or torus, of high-energy (>2 MeV) electrons that formed on 2 September 2012 and persisted largely unchanged in the geocentric radial range of 3.0 to ~3.5 Earth radii for more than 4 weeks before being disrupted (and virtually annihilated) by a powerful interplanetary shock wave passage.

  18. ACE EPAM and Van Allen Probes RBSPICE measurements of interplanetary oxygen injection to the inner magnetosphere

    Science.gov (United States)

    Patterson, J. D.; Manweiler, J. W.; Gerrard, A. J.; Lanzerotti, L. J.

    2015-12-01

    On March 17, 2015, a significant oxygen-rich interplanetary event was measure by the Advanced Composition Explorer (ACE) Electron Proton Alpha Monitor (EPAM) instrument. At the same time the Van Allen Probes Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) instrument recorded significant enhancements of oxygen in the inner magnetosphere. We present a detailed analysis of this event utilizing a new method of exploiting the EPAM Pulse Height Analyzer (PHA) data to precisely resolve helium and oxygen spectra within the 0.5 to 5 MeV/nuc range. We also present the flux, partial particle pressures, and pitch angle distributions of the ion measurements from RBSPICE. During this event, both EPAM and RBSPICE measured O:He ratios greater than 10:1. The pitch angle distributions from RBSPICE-B show a strong beam of oxygen at an L ~ 5.8 early on March 17th during orbit. The timing between the observations of the oxygen peak at ACE and the beam observed at RBSPICE-B is consistent with the travel-time required for energetic particle transport from L1 to Earth and access to the magnetosphere. We assert that the oxygen seen by RBSPICE during the initial phase of this event is the result of direct injection from the interplanetary medium of energetic ions. This poster contains the observations and detailed calculations to support this assertion.

  19. Space Geoengineering: James A. Van Allen's Role in Detecting and Disrupting the Magnetosphere, 1958-1962 (Invited)

    Science.gov (United States)

    Fleming, J. R.

    2010-12-01

    James A. Van Allen’s celebrated discovery of Earth’s radiation belts in 1958 using Explorer 1 and 3 satellites was immediately followed by his agreement to monitor tests of nuclear weapons in space aimed at disrupting the magnetosphere. This is “space geoengineering” on a planetary scale. “Space is radioactive,” noted Van Allen’s colleague Eric Ray, and the military wanted to make it even more radioactive by nuclear detonations that, in time of war might disrupt enemy radio communications from half a world away and damage or destroy enemy intercontinental ballistic missiles. This study of Van Allen’s participation in Project Argus (1958) and Project Starfish (1962) is based on new posthumous accessions to the Van Allen Papers. At the time radio astronomers protested that, “No government has the right to change the environment in any significant way without prior international study and agreement.” Van Allen later regretted his participation in experiments that disrupted the natural magnetosphere. In a larger policy framework, the history of these space interventions and the protests they generated serve as a cautionary tale for today’s geoengineers who are proposing heavy-handed manipulation of the planetary environment as a response to future climate warming. Anyone claiming that geoengineering has not yet been attempted should be reminded of the planetary-scale engineering of these nukes in space. N. Christofilos describing the intended effect of the Argus nuclear explosions on the magnetosphere, which would direct a stream of radioactive particles along magnetic lines of force half a world away.

  20. Correlation of dose rate and spectral measurements in the Inner Van Allen Belt.

    Science.gov (United States)

    Thede, A L; Radke, G E

    1968-01-01

    Dose rate measurements and the charged particle environment of the Inner Van Allen Belt have been correlated using recent data obtained from the radiation research satellite, OV3-4. Six tissue equivalent ionization chambers, constructed of a material which simulates the muscle tissue response to ionizing radiation, measured the dose rate behind various types and thicknesses of material. The specific shields used for several of the chambers were 0.192 g/cm2 aluminum, 0.797 g/cm2 Lucite and 4.485 g/cm2 brass. The proton and electron spectra were determined with an omnidirectional spectrometer using solid state detectors. The spectral measurements discussed here include geomagnetically trapped protons with energies in the range of 15 to 200 MeV. The proton spectra and dose rates are presented as profiles in terms of the McIlwain parameters of L (1.5, 2.0 and 2.5 earth radii) and the magnetic field B (0.050 to 0.250 gauss). The excellent agreement between the measured dose rate and the theoretically predicted dose rate based on the measured spectra provides justification for the radiation transport techniques now being employed to predict the doses to be encountered during future manned space missions. It was found, however, that a more adequate description of the proton fluxes for energies greater than 50 MeV will be necessary to predict dose rate accurately behind shields of 2.5 g/cm2 thickness or greater.

  1. Multi-Spacecraft Data Assimilation and Reanalysis During the THEMIS and Van Allen Probes Era

    Science.gov (United States)

    Kellerman, A. C.; Shprits, Y.; Kondrashov, D. A.; Podladchikova, T.; Drozdov, A.; Subbotin, D.

    2013-12-01

    consideration of the innovation vector may lead to a new physical understanding of the radiation belt system, which can later be used to improve our model forecasts. In the current study, we explore the radiation belt dynamics of the current era including data from the THEMIS, Van Allen Probes, GPS satellites, Akebono, NOAA and Cluster spacecraft. Intercalibration is performed between spacecraft on an individual energy channel basis, and in invariant coordinates. The global reanalysis allows an unprecedented analysis of the source-acceleration-transport-loss relationship in Earth's radiation belts. This analysis is used to refine our model capabilities, and to prepare the 3-D reanalysis for real-time data. The global 3-D reanalysis is an important step towards full-scale modeling and operational forecasting of this dynamic region of space.

  2. A Neural Network Approach for Identifying Particle Pitch Angle Distributions in Van Allen Probes Data

    Science.gov (United States)

    Souza, V. M.; Vieira, L. E. A.; Medeiros, C.; Da Silva, L. A.; Alves, L. R.; Koga, D.; Sibeck, D. G.; Walsh, B. M.; Kanekal, S. G.; Jauer, P. R.; hide

    2016-01-01

    Analysis of particle pitch angle distributions (PADs) has been used as a means to comprehend a multitude of different physical mechanisms that lead to flux variations in the Van Allen belts and also to particle precipitation into the upper atmosphere. In this work we developed a neural network-based data clustering methodology that automatically identifies distinct PAD types in an unsupervised way using particle flux data. One can promptly identify and locate three well-known PAD types in both time and radial distance, namely, 90deg peaked, butterfly, and flattop distributions. In order to illustrate the applicability of our methodology, we used relativistic electron flux data from the whole month of November 2014, acquired from the Relativistic Electron-Proton Telescope instrument on board the Van Allen Probes, but it is emphasized that our approach can also be used with multiplatform spacecraft data. Our PAD classification results are in reasonably good agreement with those obtained by standard statistical fitting algorithms. The proposed methodology has a potential use for Van Allen belt's monitoring.

  3. Prompt Injections of Highly Relativistic Electrons Induced by Interplanetary Shocks: A Statistical Study of Van Allen Probes Observations

    Science.gov (United States)

    Schiller, Q.; Kanekal, S. G.; Jian, L. K,; Li, X.; Jones, A.; Baker, D. N.; Jaynes, A.; Spence, H. E.

    2016-01-01

    We conduct a statistical study on the sudden response of outer radiation belt electrons due to interplanetary (IP) shocks during the Van Allen Probes era, i.e., 2012 to 2015. Data from the Relativistic Electron-Proton Telescope instrument on board Van Allen Probes are used to investigate the highly relativistic electron response (E greater than 1.8 MeV) within the first few minutes after shock impact. We investigate the relationship of IP shock parameters, such as Mach number, with the highly relativistic electron response, including spectral properties and radial location of the shock-induced injection. We find that the driving solar wind structure of the shock does not affect occurrence for enhancement events, 25% of IP shocks are associated with prompt energization, and 14% are associated with MeV electron depletion. Parameters that represent IP shock strength are found to correlate best with highest levels of energization, suggesting that shock strength may play a key role in the severity of the enhancements. However, not every shock results in an enhancement, indicating that magnetospheric preconditioning may be required.

  4. Dayside response of the magnetosphere to a small shock compression: Van Allen Probes, Magnetospheric MultiScale, and GOES‐13

    Science.gov (United States)

    Breneman, A.; Colpitts, C.; Dombeck, J.; Thaller, S.; Tian, S.; Wygant, J.; Fennell, J.; Hudson, M. K.; Ergun, Robert; Russell, C. T.; Torbert, Roy; Lindqvist, Per‐Arne; Burch, J.

    2017-01-01

    Abstract Observations from Magnetospheric MultiScale (~8 Re) and Van Allen Probes (~5 and 4 Re) show that the initial dayside response to a small interplanetary shock is a double‐peaked dawnward electric field, which is distinctly different from the usual bipolar (dawnward and then duskward) signature reported for large shocks. The associated E × B flow is radially inward. The shock compressed the magnetopause to inside 8 Re, as observed by Magnetospheric MultiScale (MMS), with a speed that is comparable to the E × B flow. The magnetopause speed and the E × B speeds were significantly less than the propagation speed of the pulse from MMS to the Van Allen Probes and GOES‐13, which is consistent with the MHD fast mode. There were increased fluxes of energetic electrons up to several MeV. Signatures of drift echoes and response to ULF waves also were seen. These observations demonstrate that even very weak shocks can have significant impact on the radiation belts. PMID:29104327

  5. Prompt injections of highly relativistic electrons induced by interplanetary shocks: A statistical study of Van Allen Probes observations

    Science.gov (United States)

    Schiller, Q.; Kanekal, S. G.; Jian, L. K.; Li, X.; Jones, A.; Baker, D. N.; Jaynes, A.; Spence, H. E.

    2016-12-01

    We conduct a statistical study on the sudden response of outer radiation belt electrons due to interplanetary (IP) shocks during the Van Allen Probes era, i.e., 2012 to 2015. Data from the Relativistic Electron-Proton Telescope instrument on board Van Allen Probes are used to investigate the highly relativistic electron response (E > 1.8 MeV) within the first few minutes after shock impact. We investigate the relationship of IP shock parameters, such as Mach number, with the highly relativistic electron response, including spectral properties and radial location of the shock-induced injection. We find that the driving solar wind structure of the shock does not affect occurrence for enhancement events, 25% of IP shocks are associated with prompt energization, and 14% are associated with MeV electron depletion. Parameters that represent IP shock strength are found to correlate best with highest levels of energization, suggesting that shock strength may play a key role in the severity of the enhancements. However, not every shock results in an enhancement, indicating that magnetospheric preconditioning may be required.

  6. Dayside response of the magnetosphere to a small shock compression: Van Allen Probes, Magnetospheric MultiScale, and GOES-13

    Science.gov (United States)

    Cattell, C.; Breneman, A.; Colpitts, C.; Dombeck, J.; Thaller, S.; Tian, S.; Wygant, J.; Fennell, J.; Hudson, M. K.; Ergun, Robert; Russell, C. T.; Torbert, Roy; Lindqvist, Per-Arne; Burch, J.

    2017-09-01

    Observations from Magnetospheric MultiScale ( 8 Re) and Van Allen Probes ( 5 and 4 Re) show that the initial dayside response to a small interplanetary shock is a double-peaked dawnward electric field, which is distinctly different from the usual bipolar (dawnward and then duskward) signature reported for large shocks. The associated E × B flow is radially inward. The shock compressed the magnetopause to inside 8 Re, as observed by Magnetospheric MultiScale (MMS), with a speed that is comparable to the E × B flow. The magnetopause speed and the E × B speeds were significantly less than the propagation speed of the pulse from MMS to the Van Allen Probes and GOES-13, which is consistent with the MHD fast mode. There were increased fluxes of energetic electrons up to several MeV. Signatures of drift echoes and response to ULF waves also were seen. These observations demonstrate that even very weak shocks can have significant impact on the radiation belts.

  7. Results from the magnetic electron ion spectrometer (MagEIS) instruments aboard the Van Allen Probes spacecraft

    Science.gov (United States)

    Fennell, Joseph; O'Brien, Paul; Roeder, James; Reeves, Geoffrey; Claudepierre, Seth; Clemmons, James; Spence, Harlan; Blake, Bernard

    The Magnetic Electron Ion Spectrometer (MagEIS) instruments aboard the Van Allen Probes Spacecraft (formerly RBSP) measure electrons and ions in the Earth's inner and outer radiation belts. The MagEIS instruments are part of the Energetic Particle, Composition, and Thermal Plasma Suite (ECT), which also includes the Relativistic Electron Proton Telescope (REPT) and the Helium Oxygen Proton Electron (HOPE) analyzer. MagEIS consists of four magnetic electron spectrometers aboard each of the two Van Allen Probes spacecraft that measure the differential fluxes, energies, and angular distributions of electrons from 20 keV to 4 MeV. The MagEIS suite also contains a silicon-detector telescope that measures the differential fluxes, energies, and angular distributions of protons from 60 keV to 20 MeV, and helium and oxygen ions above a hundred keV/AMU. We briefly describe the instrument design and measurement technique and present a set of results from the MagEIS observations, including ultra-low frequency (ULF) modulations of energetic electron flux, and observations of electron flux enhancements associated with the recent BARREL x-ray observations.

  8. Initial Results from the Magnetic Electron Ion Spectrometer (MagEIS) Instruments Aboard the Van Allen Probes Spacecraft

    Science.gov (United States)

    Claudepierre, S. G.; Blake, J. B.; Fennell, J. F.; Clemmons, J. H.; Roeder, J. L.; Spence, H. E.; Reeves, G. D.; Van Allen Probes ECT Team

    2013-05-01

    The Magnetic Electron Ion Spectrometer (MagEIS) instruments aboard the Van Allen Probes Spacecraft (formerly RBSP) measure electrons and ions in the Earth's inner and outer radiation belts. The MagEIS instruments are part of the Energetic Particle, Composition, and Thermal Plasma Suite (ECT), which also includes the Relativistic Electron Proton Telescope (REPT) and the Helium Oxygen Proton Electron (HOPE) analyzer. MagEIS consists of four magnetic electron spectrometers aboard each of the two Van Allen Probes spacecraft that measure the differential fluxes, energies, and angular distributions of electrons from 20 keV to 4 MeV. The MagEIS suite also contains a silicon-detector telescope that measures the differential fluxes, energies, and angular distributions of protons from 60 keV to 20 MeV, and helium and oxygen ions above a hundred keV/AMU. We briefly describe the instrument design and measurement technique and present a set of initial results from the MagEIS observations, including ultra-low frequency (ULF) modulations of energetic electron flux, and observations of electron flux enhancements associated with the recent BARREL x-ray observations.

  9. Electron acceleration through wave-particle interactions in the Van Allen belts: results of the MAARBLE project

    Science.gov (United States)

    Daglis, Ioannis A.; Turner, Drew; Balasis, Georgios; Papadimitriou, Constantinos; Georgiou, Marina; Katsavrias, Christos

    Wave-particle interactions in the inner magnetosphere play a critical role in the acceleration of electrons to high energies characteristic of the Van Allen belts. In the MAARBLE project we have been investigating the properties of ultra-low-frequency electromagnetic waves in the magnetosphere and the particular ways in which these waves can influence electron acceleration. For a number of selected intense magnetic storms, we studied the variations of energetic electron fluxes in the outer Van Allen belt along with variations of the power of Pc 4-5 waves and their earthward penetration, using multi-point observations both from a number of spacecraft and from ground-based magnetometer arrays. We present and discuss the results of this study. The work leading to this paper has received funding from the European Union’s Seventh Framework Programme (FP7-SPACE-2011-1) under grant agreement no. 284520 for the MAARBLE (Monitoring, Analyzing and Assessing Radiation Belt Energization and Loss) collaborative research project. This paper reflects only the authors’ views and the Union is not liable for any use that may be made of the information contained therein.

  10. Calculated limits for particle fluxes in Jupiter's Van Allen belts

    Science.gov (United States)

    Haffner, J.

    1972-01-01

    Electron and proton fluxes in Jupiter's radiation belts are calculated, along with the envelopes of dose rates. The following assumptions are made: the particles in the Jupiter belts are influenced only by the magnetic field of the planet; the particles act correspondingly to the particles in the Earth's belts and the Earth's belts can be used as a model; the magnetic field of Jupiter is essentially a dipole; the radiation of a decimetric nature received from Jupiter is synchrotron radiation due to the electrons, and to a first approximation it is emitted isotropically; and the strength of the emission in the decimetric wavelength range gives an upper bound considering how strong the field can be and how many electrons there are. The point dose rates for tissue and 0.1 gram/cm aluminum shielding at about 3 Jupiter radii are 10000 rads/hr for electrons and 1000 rads/hr for protons.

  11. James A. Van Allen: The Trip to Jupiter

    Science.gov (United States)

    Jacobsen, Sally

    1973-01-01

    Discusses the research purposes and activities of the Pioneer mission, including the instruments used, data on Jupiter's radiation belt, and information about cosmic ray intensity. Included is a description of the scientist's view about the value of the space program. (CC)

  12. Van Allen Probes Observations of Second Harmonic Poloidal Standing Alfvén Waves

    Science.gov (United States)

    Takahashi, Kazue; Oimatsu, Satoshi; Nosé, Masahito; Min, Kyungguk; Claudepierre, Seth G.; Chan, Anthony; Wygant, John; Kim, Hyomin

    2018-01-01

    Long-lasting second-harmonic poloidal standing Alfvén waves (P2 waves) were observed by the twin Van Allen Probes (Radiation Belt Storm Probes, or RBSP) spacecraft in the noon sector of the plasmasphere, when the spacecraft were close to the magnetic equator and had a small azimuthal separation. Oscillations of proton fluxes at the wave frequency (˜10 mHz) were also observed in the energy (W) range 50-300 keV. Using the unique RBSP orbital configuration, we determined the phase delay of magnetic field perturbations between the spacecraft with a 2nπ ambiguity. We then used finite gyroradius effects seen in the proton flux oscillations to remove the ambiguity and found that the waves were propagating westward with an azimuthal wave number (m) of ˜-200. The phase of the proton flux oscillations relative to the radial component of the wave magnetic field progresses with W, crossing 0 (northward moving protons) or 180° (southward moving protons) at W ˜ 120 keV. This feature is explained by drift-bounce resonance (mωd ˜ ωb) of ˜120 keV protons with the waves, where ωd and ωb are the proton drift and bounce frequencies. At lower energies, the proton phase space density (FH+) exhibits a bump-on-tail structure with ∂FH+/∂W>0 occurring in the 1-10 keV energy range. This FH+ is unstable and can excite P2 waves through bounce resonance (ω ˜ ωb), where ω is the wave frequency.

  13. Deterministic methods for the relativistic Vlasov-Maxwell equations and the Van Allen belts dynamics; Methodes deterministes de resolution des equations de Vlasov-Maxwell relativistes en vue du calcul de la dynamique des ceintures de Van Allen

    Energy Technology Data Exchange (ETDEWEB)

    Le Bourdiec, S

    2007-03-15

    Artificial satellites operate in an hostile radiation environment, the Van Allen radiation belts, which partly condition their reliability and their lifespan. In order to protect them, it is necessary to characterize the dynamics of the energetic electrons trapped in these radiation belts. This dynamics is essentially determined by the interactions between the energetic electrons and the existing electromagnetic waves. This work consisted in designing a numerical scheme to solve the equations modelling these interactions: the relativistic Vlasov-Maxwell system of equations. Our choice was directed towards methods of direct integration. We propose three new spectral methods for the momentum discretization: a Galerkin method and two collocation methods. All of them are based on scaled Hermite functions. The scaling factor is chosen in order to obtain the proper velocity resolution. We present in this thesis the discretization of the one-dimensional Vlasov-Poisson system and the numerical results obtained. Then we study the possible extensions of the methods to the complete relativistic problem. In order to reduce the computing time, parallelization and optimization of the algorithms were carried out. Finally, we present 1Dx-3Dv (mono-dimensional for x and three-dimensional for velocity) computations of Weibel and whistler instabilities with one or two electrons species. (author)

  14. Near-Earth injection of MeV electrons associated with intense dipolarization electric fields: Van Allen Probes observations.

    Science.gov (United States)

    Dai, Lei; Wang, Chi; Duan, Suping; He, Zhaohai; Wygant, John R; Cattell, Cynthia A; Tao, Xin; Su, Zhenpeng; Kletzing, Craig; Baker, Daniel N; Li, Xinlin; Malaspina, David; Blake, J Bernard; Fennell, Joseph; Claudepierre, Seth; Turner, Drew L; Reeves, Geoffrey D; Funsten, Herbert O; Spence, Harlan E; Angelopoulos, Vassilis; Fruehauff, Dennis; Chen, Lunjin; Thaller, Scott; Breneman, Aaron; Tang, Xiangwei

    2015-08-16

    Substorms generally inject tens to hundreds of keV electrons, but intense substorm electric fields have been shown to inject MeV electrons as well. An intriguing question is whether such MeVelectron injections can populate the outer radiation belt. Here we present observations of a substorm injection of MeV electrons into the inner magnetosphere. In the premidnight sector at L ∼ 5.5, Van Allen Probes (Radiation Belt Storm Probes)-A observed a large dipolarization electric field (50 mV/m) over ∼40 s and a dispersionless injection of electrons up to ∼3 MeV. Pitch angle observations indicated betatron acceleration of MeV electrons at the dipolarization front. Corresponding signals of MeV electron injection were observed at LANL-GEO, THEMIS-D, and GOES at geosynchronous altitude. Through a series of dipolarizations, the injections increased the MeV electron phase space density by 1 order of magnitude in less than 3 h in the outer radiation belt ( L > 4.8). Our observations provide evidence that deep injections can supply significant MeV electrons.

  15. Subauroral Polarization Streams (SAPS) Duration as Determined From Van Allen Probe Successive Electric Drift Measurements

    Science.gov (United States)

    Lejosne, Solène; Mozer, F. S.

    2017-09-01

    We examine a characteristic feature of the magnetosphere-ionosphere coupling, namely, the persistent and latitudinally narrow bands of rapid westward ion drifts called the subauroral polarization streams (SAPS). Despite countless works on SAPS, information relative to their durations is lacking. Here we report on the first statistical analysis of more than 200 near-equatorial SAPS observations based on more than 2 years of Van Allen Probe electric drift measurements. First, we present results relative to SAPS radial locations and amplitudes. Then, we introduce two different ways to estimate SAPS durations. In both cases, SAPS activity is estimated to last for about 9 h on average. However, our estimates for SAPS duration are limited either by the relatively long orbital periods of the spacecraft or by the relatively small number of observations involved. Fifty percent of the events fit within the time interval [0;18] hours.

  16. Transitional behavior of low energy protons based on Van Allen Probes observation

    Science.gov (United States)

    Yue, C.; Bortnik, J.; Ma, Q.; Thorne, R. M.

    2016-12-01

    The low energy ( 1 eV - 50 keV) plasma dynamics in the Earth's inner magnetosphere are regulated by the large-scale electric and magnetic fields, yet there have been only few direct observational demonstrations of the drift behaviors of different energy ions on the magnetic equatorial plane before the launch of the Van Allen Probes. In this study, we have statistically analyzed proton differential flux distributions near the equatorial plane by using HOPE measurements onboard of the Van Allen Probes from October 2012 to December 2015, to investigate the dynamics of H+ with energies from 1 eV to 50 keV under the regulation of electric and magnetic fields. Our survey clearly indicates three types of H+ behaviors within different energy ranges: (1) Dayside ionospheric outflowing H+ is the main contribution to the low energy (E observed in the near-Earth equatorial region (L observed around the post-midnight sector; (2) Eastward drifting H+ with energies between 6 eV to 5 keV coming from the tail plasma sheet, probably originate from the ionosphere or solar wind, are regulated mainly by the large-scale co-rotational and convectional electric fields with highest number flux around the dawn sector; (3) H+ with E > 5 keV exhibit peak fluxes in the dusk sector due to their magnetic field gradient and curvature drift paths. Using simple electric and magnetic field models in the UBK coordinates, we have further constrained the source regions of different energy particles and their drift directions.

  17. VLF waves from ground-based transmitters observed by the Van Allen Probes: Statistical model and effects on plasmaspheric electrons

    Science.gov (United States)

    Ma, Qianli; Mourenas, Didier; Li, Wen; Artemyev, Anton; Thorne, Richard M.

    2017-07-01

    Whistler mode very low frequency (VLF) waves from powerful ground-based transmitters can resonantly scatter energetic plasmaspheric electrons and precipitate them into the atmosphere. A comprehensive 4 year statistics of Van Allen Probes measurements is carried out to assess their consequences on the dynamics of the inner radiation belt and slot region. Statistical models of the measured wave electric field power and of the inferred full wave magnetic amplitude are provided as a function of L, magnetic local time, season, and Kp over L = 1-3, revealing the localization of VLF wave intensity and its variation with geomagnetic activity over 2012-2016. Since this VLF wave model can be directly used together with existing hiss and lightning-generated wave models in radiation belt simulation codes, we perform numerical calculations of the corresponding quasi-linear pitch angle diffusion rates, allowing us to demonstrate the crucial role played by VLF waves from transmitters in energetic electron loss at L < 2.5.

  18. Van Allen Probes observations of unusually low frequency whistler mode waves observed in association with moderate magnetic storms: Statistical study.

    Science.gov (United States)

    Cattell, C A; Breneman, A W; Thaller, S A; Wygant, J R; Kletzing, C A; Kurth, W S

    2015-09-28

    We show the first evidence for locally excited chorus at frequencies below 0.1  f ce (electron cyclotron frequency) in the outer radiation belt. A statistical study of chorus during geomagnetic storms observed by the Van Allen Probes found that frequencies are often dramatically lower than expected. The frequency at peak power suddenly stops tracking the equatorial 0.5  f ce and f / f ce decreases rapidly, often to frequencies well below 0.1  f ce (in situ and mapped to equator). These very low frequency waves are observed both when the satellites are close to the equatorial plane and at higher magnetic latitudes. Poynting flux is consistent with generation at the equator. Wave amplitudes can be up to 20 to 40 mV/m and 2 to 4 nT. We conclude that conditions during moderate to large storms can excite unusually low frequency chorus, which is resonant with more energetic electrons than typical chorus, with critical implications for understanding radiation belt evolution.

  19. Analysis of plasmaspheric hiss wave amplitudes inferred from low-altitude POES electron data: Validation with conjunctive Van Allen Probes observations

    Science.gov (United States)

    Soria-Santacruz, M.; Li, W.; Thorne, R. M.; Ma, Q.; Bortnik, J.; Ni, B.; Kletzing, C. A.; Kurth, W. S.; Hospodarsky, G. B.

    2015-10-01

    Plasmaspheric hiss plays an important role in controlling the overall structure and dynamics of the Earth's radiation belts. The interaction of plasmaspheric hiss with radiation belt electrons is commonly evaluated using diffusion codes, which rely on statistical models of wave observations that may not accurately reproduce the instantaneous global wave distribution or the limited in situ satellite wave measurements. This paper evaluates the performance and limitations of a novel technique capable of inferring wave amplitudes from low-altitude electron flux observations from the Polar Orbiting Environmental Satellites (POES), which provide extensive coverage in shell and magnetic local time (MLT). We found that, within its limitations, this technique could potentially be used to build a dynamic global model of the plasmaspheric hiss wave intensity. The technique is validated by analyzing the conjunctions between the POES spacecraft and the Van Allen Probes from September 2012 to June 2014. The technique performs well for moderate-to-strong hiss activity (≥30 pT) with sufficiently high electron fluxes. The main source of these limitations is the number of counts of energetic electrons measured by the POES spacecraft capable of resonating with hiss waves. For moderate-to-strong hiss events, the results show that the wave amplitudes from the EMFISIS instruments on board the Van Allen Probes are well reproduced by the POES technique, which provides more consistent estimates than the parameterized statistical hiss wave model based on CRRES data.

  20. Van Allen Probes observation of a 360° phase shift in the flux modulation of injected electrons by ULF waves

    Science.gov (United States)

    Chen, X.-R.; Zong, Q.-G.; Zhou, X.-Z.; Blake, J. Bernard; Wygant, J. R.; Kletzing, C. A.

    2017-02-01

    We present Van Allen Probe observation of drift-resonance interaction between energetic electrons and ultralow frequency (ULF) waves on 29 October 2013. Oscillations in electron flux were observed at the period of ˜450 s, which is also the dominant period of the observed ULF magnetic pulsations. The phase shift of the electron fluxes (˜50 to 150 keV) across the estimated resonant energy (˜104 keV) is ˜360°. This phase relationship is different from the characteristic 180° phase shift as expected from the drift-resonance theory. We speculate that the additional 180° phase difference arises from the inversion of electron phase space density (PSD) gradient, which in turn is caused by the drift motion of the substorm injected electrons. This PSD gradient adjusts the characteristic particle signatures in the drift-resonance theory, which indicates a coupling effect between the magnetotail and the radiation belt and helps to better understand the wave-particle interaction in the magnetosphere.

  1. Pi2 Pulsations During Extremely Quiet Geomagnetic Condition: Van Allen Probe Observations

    Directory of Open Access Journals (Sweden)

    Essam Ghamry

    2017-06-01

    Full Text Available A ultra low frequency (ULF wave, Pi2, has been reported to occur during periods of extremely quiet magnetospheric and solar wind conditions. And no statistical study on the Pi2 has been performed during extremely quiet conditions, using satellite observations to the author’s knowledge. Also Pi2 pulsations in the space fluxgate magnetometers near perigee failed to attract scientist’s attention previously. In this paper, Pi2 pulsations detected by the Van Allen probe satellites (VAP-A & VAP-B were investigated statistically. During the period from October 2012 to December 2014, ninety six Pi2 events were identified using VAP when Kp = 0 while using Kakioka (KAK, L = 1.23 as a reference ground station. Seventy five events had high coherence between VAP-Bz and H components at KAK station. As a result, it was found that 77 % of the events had power spectra between 5 and 12 mHz, which differs from the regular Pi2 band range of from 6.7 to 25 mHz. In addition, it was shown that it is possible to observe Pi2 pulsations from space fluxgate magnetometers near perigee. Twenty two clean Pi2 pulsations were found where L < 4 and four examples of Pi2 oscillations at different L shells are presented in this paper.

  2. Bayesian spectral analysis of chorus subelements from the Van Allen Probes

    Science.gov (United States)

    Crabtree, Chris; Tejero, Erik; Ganguli, Gurudas; Hospodarsky, George B.; Kletzing, Craig A.

    2017-06-01

    We develop a Bayesian spectral analysis technique that calculates the probability distribution functions of a superposition of wave modes each described by a linear growth rate, a frequency, and a chirp rate. The Bayesian framework has a number of advantages, including (1) reducing the parameter space by integrating over the amplitude and phase of the wave, (2) incorporating the data from each channel to determine the model parameters such as frequency which leads to high-resolution results in frequency and time, (3) the ability to consider the superposition of waves where the wave parameters are closely spaced, (4) the ability to directly calculate the expectation value of wave parameters without resorting to ensemble averages, and (5) the ability to calculate error bars on model parameters. We examine one rising-tone chorus element in detail from a disturbed time on 14 November 2012 using burst mode waveform data of the three components of the electric and magnetic field from the EMFISIS instrument on board NASA's Van Allen Probes. The results demonstrate that subelements are likely composed of almost linear waves that are nearly parallel propagating with continuously changing wave parameters such as frequency and wave vector. Between subelements the wave parameters of the dominant mode undergoes a discrete change in frequency and wave vector. Near the boundary of subelements multiple waves are observed such that the evolution of the waves is reminiscent of wave-wave processes such as parametric decay or nonlinear induced scattering by particles. These nonlinear processes may affect the saturation of the whistler mode chorus instability.

  3. Upcoming observations of whistler-mode waves in the outer Van Allen belt: multicomponent wave analyzer ELMAVAN for the Resonance mission

    Science.gov (United States)

    Santolik, Ondrej; Korepanov, Valery; Chugunin, Dmitriy; Kolmasova, Ivana; Uhlir, Ludek; Pronenko, Vira; Mogilevsky, Mikhail; Lan, Radek; Boychev, Boycho

    The instrument ELMAVAN is being prepared at the Institute of Atmospheric Physics, Prague in the frame of the Russian Resonance project with international participation. The aim of this four-spacecraft mission is to investigate properties of wave-particle interactions and plasma dynamics in the inner magnetosphere of the Earth with the focus on phenomena occurring within the same flux tube of the Earth's magnetic field. The wave emissions attract increasing attention because of their influence on the dynamics of the Earth’s radiation belts. The Resonance project therefore represents an excellent opportunity for the magnetospheric research, and together with the recently launched two-spacecraft US mission Van Allen Probes, it will contribute to our understanding of the Earth’s Van Allen radiation belts and the inner magnetosphere. ELMAVAN will measure intensity, polarization, coherence, and propagation properties of waves in magnetospheric plasmas. Three orthogonal magnetic search coil antennas and four electric monopoles will be used for the measurements. The instrument will measure fluctuations of the electric and magnetic field in the frequency range 10 Hz - 20 kHz. The scientific motivation is to investigate properties of whistler-mode chorus and hiss, and both equatorial and auroral emissions. Nonlinear wave-particle interactions will be the main target of these measurements. The input signals of ELMAVAN will consist of 3 analog signals from orthogonal magnetic search coil antennas and 4 analog signals from electric monopoles. The instrument ELMAVAN uses the state of the art electronics and mechanical design taking into account specific requirements for the orbit inside the radiation belts. From this point of view this instrument will also be important as a technological experiment. Engineering model of the analyzer was developed and tested in 2012-2013. Qualification model and the flight models are under preparation.

  4. A Telescopic and Microscopic Examination of Acceleration in the June 2015 Geomagnetic Storm: Magnetospheric Multiscale and Van Allen Probes Study of Substorm Particle Injection

    Science.gov (United States)

    Baker, D. N.; Jaynes, A. N.; Turner, D. L.; Nakamura, R.; Schmid, D.; Mauk, B. H.; Cohen, I. J.; Fennell, J. F.; Blake, J. B.; Strangeway, R. J.; hide

    2016-01-01

    An active storm period in June 2015 showed that particle injection events seen sequentially by the four (MagnetosphericMultiscale) MMS spacecraft subsequently fed the enhancement of the outer radiation belt observed by Van Allen Probes mission sensors. Several episodes of significant southward interplanetary magnetic field along with a period of high solar wind speed (Vsw 500kms) on 22 June occurred following strong interplanetary shock wave impacts on the magnetosphere. Key events on 22 June 2015 show that the magnetosphere progressed through a sequence of energy-loading and stress-developing states until the entire system suddenly reconfigured at 19:32 UT. Energetic electrons, plasma, and magnetic fields measured by the four MMS spacecraft revealed clear dipolarization front characteristics. It was seen that magnetospheric substorm activity provided a seed electron population as observed by MMS particle sensors as multiple injections and related enhancements in electron flux.

  5. Acceleration and loss of relativistic and ultra-relativistic electrons in the outer Van Allen belt during intense storms: a statistical study.

    Science.gov (United States)

    Katsavrias, Christos; Daglis, Ioannis A.; Li, Wen; Dimitrakoudis, Stavros; Georgiou, Marina; Papadimitriou, Constantinos

    2017-04-01

    We present electron phase space density (PSD) calculations as well as concurrent Pc5 and chorus wave activity observations in the outer radiation belt during 18 intense geospace magnetic storms by employing multi-point particle and field observations (both in-situ and through ground-based remote sensing), including the THEMIS, Van Allen Probes, NOAA POES and GOES constellations, the XMM and INTEGRAL spacecraft, and the CARISMA and IMAGE ground magnetometer arrays. The data provide a broad range of particle energies and a wide radial and azimuthal spatial coverage. Observations show that different acceleration and loss mechanisms act simultaneously on different electron populations, depending on the values of the electrons' 1st and 2nd adiabatic invariants. This work has been supported by the NOA/IAASARS SOLPLA project.

  6. Radiation Belt Dynamics

    Science.gov (United States)

    2015-12-27

    Distributions Recent analysis of Van Allen Probes observations has forced a reevaluation of models and our understanding of the inner electron radiation belt ...challenge” studies of four chosen recent events well-observed by the Van Allen Probes satellites, with participation by the radiation belt research...work, recently augmented by observations made by the currently orbiting NASA Van Allen Probes satellites, has revealed unexpected behavior and

  7. Radial Diffusion Caused by Pitch Angle Scattering and Drift Shell Splitting - Simulation and Van Allen Probes Observations

    Science.gov (United States)

    Henderson, M. G.; Morley, S.; Cunningham, G.; Tu, W.; Reeves, G. D.; Fennell, J. F.; Claudepierre, S. G.; Blake, J. B.; Spence, H.; Baker, D. N.

    2013-12-01

    In realistic asymmetric magnetic fields, particles with different pitch angles starting on the same field line will trace out different drift shells. As a result of this drift shell splitting, pitch angle scattering automatically leads to additional radial diffusion. At a given position on a drift shell, the instantaneous DLL associated with this process is related to the gradient of L* with respect to equatorial pitch angle and the local value of the bounce averaged Daa diffusion coefficient. The final DLL associated with pitch angle scattering is then obtained by drift averaging. We show initial results of computed DLL coefficients and simulations using the DREAM diffusion code. The results are compared with Phase Space Densities measured with the recently launched Van Allen Probes.

  8. The Characteristic Pitch Angle Distributions of 1 eV to 600 keV Protons Near the Equator Based On Van Allen Probes Observations

    Science.gov (United States)

    Yue, Chao; Bortnik, Jacob; Thorne, Richard M.; Ma, Qianli; An, Xin; Chappell, C. R.; Gerrard, Andrew J.; Lanzerotti, Louis J.; Shi, Quanqi; Reeves, Geoffrey D.; Spence, Harlan E.; Mitchell, Donald G.; Gkioulidou, Matina; Kletzing, Craig A.

    2017-09-01

    Understanding the source and loss processes of various plasma populations is greatly aided by having accurate knowledge of their pitch angle distributions (PADs). Here we statistically analyze 1 eV to 600 keV hydrogen (H+) PADs near the geomagnetic equator in the inner magnetosphere based on Van Allen Probes measurements, to comprehensively investigate how the H+ PADs vary with different energies, magnetic local times (MLTs), L shells, and geomagnetic conditions. Our survey clearly indicates four distinct populations with different PADs: (1) a pancake distribution of the plasmaspheric H+ at low L shells except for dawn sector; (2) a bidirectional field-aligned distribution of the warm plasma cloak; (3) pancake or isotropic distributions of ring current H+; (4) radiation belt particles show pancake, butterfly, and isotropic distributions depending on their energy, MLT, and L shell. Meanwhile, the pancake distribution of ring current H+ moves to lower energies as L shell increases, which is primarily caused by adiabatic transport. Furthermore, energetic H+ (>10 keV) PADs become more isotropic following the substorm injections, indicating wave-particle interactions. The radiation belt H+ butterfly distributions are identified in a narrow energy range of 100 5), which are less significant during quiet times and extend from dusk to dawn sector through midnight during substorms. The different PADs near the equator provide clues of the underlying physical processes that produce the dynamics of these different populations.

  9. First direct evidence of a one-one correspondence of chorus wave packets and microbursts: Van Allen Probes EFW and FIREBIRD

    Science.gov (United States)

    Breneman, A. W.; Crew, A. B.; Klumpar, D. M.; Agapitov, O. V.; Wygant, J. R.; Kletzing, C.; Hospodarsky, G. B.

    2016-12-01

    Chorus waves are a major controlling factor in the loss of ring current and radiation belt electrons during active times. One form in which this loss is thought to occur is microbursts, which are observed on low altitude satellites and balloons as impulsive electron precipitation events. Past observations have shown a broad correlation in time and MLT of chorus and microbursts. In addition, nonlinear theories of chorus/electron interactions provide a possible mechanism through which this loss occurs. However, due to the small scale size of chorus wave (phase) coherence - on the order of 10-100 km across a magnetic field line - a direct comparison of chorus and microbursts requires a near perfect magnetic conjunction of an equatorial satellite traversing the chorus source and a low altitude payload capable of observing loss cone electrons. We present fortuitous simultaneous observations on Van Allen Probe A and the FIREBIRD II cubesat showing a clear one-one correspondence of chorus wave packets and microbursts. A comparison of observations to theory suggests that Landau resonance is likely the cause for the electron scattering, observed from 250 keV (the lower limit of FIREBIRD II) up to 620 keV. Our results confirm and provide insight to the idea that chorus waves cause electron microbursts, which constitute a major loss mechanism of the radiation belts.

  10. Multipoint Observations of Energetic Particle Injections and Substorm Activity During a Conjunction Between Magnetospheric Multiscale (MMS) and Van Allen Probes

    Science.gov (United States)

    Turner, D. L.; Fennell, J. F.; Blake, J. B.; Claudepierre, S. G.; Clemmons, J. H.; Jaynes, A. N.; Leonard, T.; Baker, D. N.; Cohen, I. J.; Gkioulidou, M.; Ukhorskiy, A. Y.; Mauk, B. H.; Gabrielse, C.; Angelopoulos, V.; Strangeway, R. J.; Kletzing, C. A.; Le Contel, O.; Spence, H. E.; Torbert, R. B.; Burch, J. L.; Reeves, G. D.

    2017-11-01

    This study examines multipoint observations during a conjunction between Magnetospheric Multiscale (MMS) and Van Allen Probes on 7 April 2016 in which a series of energetic particle injections occurred. With complementary data from Time History of Events and Macroscale Interactions during Substorms, Geotail, and Los Alamos National Laboratory spacecraft in geosynchronous orbit (16 spacecraft in total), we develop new insights on the nature of energetic particle injections associated with substorm activity. Despite this case involving only weak substorm activity (maximum AE electron injections was observed throughout the system. Intriguingly, only one corresponding ion injection was clearly observed. All ion and electron injections were observed at electron injection. A relationship between injected electrons with energy injection boundary locations as a function of universal time, magnetic local time, and L shell. The analysis reveals that at least five electron injections, which were localized in magnetic local time, preceded a larger injection of both electrons and ions across nearly the entire nightside of the magnetosphere near geosynchronous orbit. The larger ion and electron injection did not penetrate to L electron injections penetrated to L electron versus ion injections, this event presents challenges to the current conceptual models of energetic particle injections.

  11. Empirical Modeling of the Storm Time Innermost Magnetosphere Using Van Allen Probes and THEMIS Data: Eastward and Banana Currents

    Science.gov (United States)

    Stephens, G. K.; Sitnov, M. I.; Ukhorskiy, A. Y.; Roelof, E. C.; Tsyganenko, N. A.; Le, G.

    2016-01-01

    The structure of storm time currents in the inner magnetosphere, including its innermost region inside 4R(sub E), is studied for the first time using a modification of the empirical geomagnetic field model TS07D and new data from Van Allen Probes and Time History of Events and Macroscale Interactions during Substorms missions. It is shown that the model, which uses basis-function expansions instead of ad hoc current modules to approximate the magnetic field, consistently improves its resolution and magnetic field reconstruction with the increase of the number of basis functions and resolves the spatial structure and evolution of the innermost eastward current. This includes a connection between the westward ring current flowing largely at R > or approx. 3R(sub E) and the eastward ring current concentrated at R < or approx. 3R(sub E) resulting in a vortex current pattern. A similar pattern coined 'banana current' was previously inferred from the pressure distributions based on the energetic neutral atom imaging and first-principles ring current simulations. The morphology of the equatorial currents is dependent on storm phase. During the main phase, it is complex, with several asymmetries forming banana currents. Near SYM-H minimum, the banana current is strongest, is localized in the evening-midnight sector, and is more structured compared to the main phase. It then weakens during the recovery phase resulting in the equatorial currents to become mostly azimuthally symmetric.

  12. Magnetohydrodynamic modeling of three Van Allen Probes storms in 2012 and 2013

    OpenAIRE

    J. Paral; J. Paral; M. K. Hudson; B. T. Kress; M. J. Wiltberger; J. R. Wygant; H. J. Singer

    2015-01-01

    Coronal mass ejection (CME)-shock compression of the dayside magnetopause has been observed to cause both prompt enhancement of radiation belt electron flux due to inward radial transport of electrons conserving their first adiabatic invariant and prompt losses which at times entirely eliminate the outer zone. Recent numerical studies suggest that enhanced ultra-low frequency (ULF) wave activity is necessary to explain electron losses deeper inside the magnetosphere ...

  13. Van Allen Probes Measurements of Energetic Particle Deep Penetration Into the Low L Region (L < 4) During the Storm on 8 April 2016

    Science.gov (United States)

    Zhao, H.; Baker, D. N.; Califf, S.; Li, X.; Jaynes, A. N.; Leonard, T.; Kanekal, S. G.; Blake, J. B.; Fennell, J. F.; Claudepierre, S. G.; Turner, D. L.; Reeves, G. D.; Spence, H. E.

    2017-12-01

    Using measurements from the Van Allen Probes, a penetration event of tens to hundreds of keV electrons and tens of keV protons into the low L shells (L electric field represented by the Volland-Stern model or a uniform dawn-dusk electric field model based on the electric field measurements. It suggests that the underlying physical mechanism responsible for energetic electron deep penetration, which is very important for fully understanding energetic electron dynamics in the low L shells, should be MLT localized.

  14. Space Radiation

    Energy Technology Data Exchange (ETDEWEB)

    Corliss, William R.

    1968-01-01

    This booklet discusses three kinds of space radiation, cosmic rays, Van Allen Belts, and solar plasma. Cosmic rays are penetrating particles that we cannot see, hear or feel, which come from distant stars. Van Allen Belts, named after their discoverer are great belts of protons and electrons that the earth has captured in its magnetic trap. Solar plasma is a gaseous, electrically neutral mixture of positive and negative ions that the sun spews out from convulsed regions on its surface.

  15. What Can Be Learned from the Van Allen Probe Measurements of the Electric Drift ExB/B2 in the Inner Magnetosphere

    Science.gov (United States)

    Lejosne, S.; Mozer, F.

    2016-12-01

    Although electric fields play a fundamental role in space physics, they are difficult to observe experimentally. This is particularly true closest to Earth, where the electric field induced by the spacecraft motion around perigee is very large. As a result, the traditional assumption is that spacecraft cannot deliver reliable measurements of the electric drift velocity ExB/B2 close to Earth. Yet, it has recently been shown that the Van Allen Probes had an accuracy such that even the electric fields due to the ionosphere dynamo could be detected around the magnetic equator at L = 1.4. Since the electric drift velocity is common to all particles, it plays a fundamental role in many situations and its description is key. With this in mind, we have developed a unique database spanning several years of inner magnetospheric electric drifts measured by both Van Allen Probes around magnetic equator and its analysis is underway. We report on the first results of the work with a focus on identifying the different drivers of the electric drift. We also address possible consequences with respect to particle dynamics.

  16. What have we learned about the energetic particle dynamics in the inner belt and slot region from Van Allen Probes and CSSWE missions?

    Science.gov (United States)

    Li, Xinlin; Selesnick, Richard; Zhao, Hong; Baker, Dan; Jaynes, Allison; Kanekal, Shrikanth; Bern Blake, J.

    2017-04-01

    Comprehensive measurements of energetic protons (10s of MeV) in the inner belt (LVan Allen Probes, in a geo-transfer-like orbit, revealed new features of these energetic protons in terms of their spectrum distribution, spatial distribution, pitch angle distribution, and their different dynamic variations associated with their different source populations. Measurements from the Relativistic Electron-Proton Telescope integrated little experiment (REPTile) on board Colorado Student Space Weather Experiment (CSSWE) CubeSat, in a highly inclined low Earth orbit, demonstrated that there exist sub-MeV electrons in the inner belt and their flux level is orders of magnitude higher than the background associated with the inner belt protons, while higher energy electron (>1.6 MeV) measurements cannot be distinguished from the background. Analysis on sub-MeV electrons data in the inner belt and slot region from the Magnetic Electron Ion Spectrometer (MagEIS) on board Van Allen Probes revealed rather complex pitch angle distribution of these energetic electrons, with the 90 deg-minimum (butterfly) pitch angle distribution dominating near the magnetic equator, which has inspired a great deal of theoretical interest in an attempt to explain such a peculiar pitch angle distribution. These are part of a summary of the most recent measurements and understanding of the dynamics of energetic particles in the inner zone and slot region to be exhibited and discussed in this presentation.

  17. Relativistic Electron Response to the Combined Magnetospheric Impact of a Coronal Mass Ejection Overlapping with a High-Speed Stream: Van Allen Probes Observations

    Science.gov (United States)

    Kanekal, S. G.; Baker, D. N.; Henderson, M. G.; Li, W.; Fennell, J. F.; Zheng, Y.; Richardson, I. G.; Jones, A.; Ali, A. F.; Elkington, S. R.; hide

    2015-01-01

    During early November 2013, the magnetosphere experienced concurrent driving by a coronal mass ejection (CME) during an ongoing high-speed stream (HSS) event. The relativistic electron response to these two kinds of drivers, i.e., HSS and CME, is typically different, with the former often leading to a slower buildup of electrons at larger radial distances, while the latter energizing electrons rapidly with flux enhancements occurring closer to the Earth. We present a detailed analysis of the relativistic electron response including radial profiles of phase space density as observed by both Magnetic Electron and Ion Sensor (MagEIS) and Relativistic Electron Proton Telescope instruments on the Van Allen Probes mission. Data from the MagEIS instrument establish the behavior of lower energy (electrons which span both intermediary and seed populations during electron energization. Measurements characterizing the plasma waves and magnetospheric electric and magnetic fields during this period are obtained by the Electric and Magnetic Field Instrument Suite and Integrated Science instrument on board Van Allen Probes, Search Coil Magnetometer and Flux Gate Magnetometer instruments on board Time History of Events and Macroscale Interactions during Substorms, and the low-altitude Polar-orbiting Operational Environmental Satellites. These observations suggest that during this time period, both radial transport and local in situ processes are involved in the energization of electrons. The energization attributable to radial diffusion is most clearly evident for the lower energy (electrons, while the effects of in situ energization by interaction of chorus waves are prominent in the higher-energy electrons.

  18. Initial measurements of O-ion and He-ion decay rates observed from the Van Allen probes RBSPICE instrument.

    Science.gov (United States)

    Gerrard, Andrew; Lanzerotti, Louis; Gkioulidou, Matina; Mitchell, Donald; Manweiler, Jerry; Bortnik, Jacob; Keika, Kunihiro

    2014-11-01

    H-ion (∼45 keV to ∼600 keV), He-ion (∼65 keV to ∼520 keV), and O-ion (∼140 keV to ∼1130 keV) integral flux measurements, from the Radiation Belt Storm Probe Ion Composition Experiment (RBSPICE) instrument aboard the Van Allan Probes spacecraft B, are reported. These abundance data form a cohesive picture of ring current ions during the first 9 months of measurements. Furthermore, the data presented herein are used to show injection characteristics via the He-ion/H-ion abundance ratio and the O-ion/H-ion abundance ratio. Of unique interest to ring current dynamics are the spatial-temporal decay characteristics of the two injected populations. We observe that He-ions decay more quickly at lower L shells, on the order of ∼0.8 day at L shells of 3-4, and decay more slowly with higher L shell, on the order of ∼1.7 days at L shells of 5-6. Conversely, O-ions decay very rapidly (∼1.5 h) across all L shells. The He-ion decay time are consistent with previously measured and calculated lifetimes associated with charge exchange. The O-ion decay time is much faster than predicted and is attributed to the inclusion of higher-energy (> 500 keV) O-ions in our decay rate estimation. We note that these measurements demonstrate a compelling need for calculation of high-energy O-ion loss rates, which have not been adequately studied in the literature to date. We report initial observations of ring current ionsWe show that He-ion decay rates are consistent with theoryWe show that O-ions with energies greater than 500 keV decay very rapidly.

  19. Inferring electromagnetic ion cyclotron wave intensity from low altitude POES proton flux measurements: A detailed case study with conjugate Van Allen Probes observations

    Science.gov (United States)

    Zhang, Yang; Shi, Run; Ni, Binbin; Gu, Xudong; Zhang, Xianguo; Zuo, Pingbing; Fu, Song; Xiang, Zheng; Wang, Qi; Cao, Xing; Zou, Zhengyang

    2017-03-01

    Electromagnetic ion cyclotron (EMIC) waves play an important role in the magnetospheric particle dynamics and can lead to resonant pitch-angle scattering and ultimate precipitation of ring current protons. Commonly, the statistics of in situ EMIC wave measurements is adopted for quantitative investigation of wave-particle interaction processes, which however becomes questionable for detailed case studies especially during geomagnetic storms and substorms. Here we establish a novel technique to infer EMIC wave amplitudes from low-altitude proton measurements onboard the Polar Operational Environmental Satellites (POES). The detailed procedure is elaborated regarding how to infer the EMIC wave intensity for one specific time point. We then test the technique with a case study comparing the inferred root-mean-square (RMS) EMIC wave amplitude with the conjugate Van Allen Probes EMFISIS wave measurements. Our results suggest that the developed technique can reasonably estimate EMIC wave intensities from low-altitude POES proton flux data, thereby providing a useful tool to construct a data-based, near-real-time, dynamic model of the global distribution of EMIC waves once the proton flux measurements from multiple POES satellites are available for any specific time period.

  20. Applying the cold plasma dispersion relation to whistler mode chorus waves: EMFISIS wave measurements from the Van Allen Probes.

    Science.gov (United States)

    Hartley, D P; Chen, Y; Kletzing, C A; Denton, M H; Kurth, W S

    2015-02-01

    Most theoretical wave models require the power in the wave magnetic field in order to determine the effect of chorus waves on radiation belt electrons. However, researchers typically use the cold plasma dispersion relation to approximate the magnetic wave power when only electric field data are available. In this study, the validity of using the cold plasma dispersion relation in this context is tested using Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) observations of both the electric and magnetic spectral intensities in the chorus wave band (0.1-0.9 f ce ). Results from this study indicate that the calculated wave intensity is least accurate during periods of enhanced wave activity. For observed wave intensities >10 -3 nT 2 , using the cold plasma dispersion relation results in an underestimate of the wave intensity by a factor of 2 or greater 56% of the time over the full chorus wave band, 60% of the time for lower band chorus, and 59% of the time for upper band chorus. Hence, during active periods, empirical chorus wave models that are reliant on the cold plasma dispersion relation will underestimate chorus wave intensities to a significant degree, thus causing questionable calculation of wave-particle resonance effects on MeV electrons.

  1. Formation and Decay of the Inner Electron Radiation Belt

    Science.gov (United States)

    2017-01-09

    Wave acceleration of electrons in the Van Allen radiation belts , Nature, 437, 227–230, doi:10.1038/nature03939. Kessel, R. L., N. J. Fox...prime mission of the Van Allen Probes Key Points: • Quantified upper limit of MeV electrons in the inner belt • Actual MeV electron intensity likely...have not happened yet since the launch of Van Allen Probes, significant enhancements of MeV electrons do not occur in the inner belt even

  2. Using Jupiter's Synchrotron Radiation as a Probe into Jupiter's Inner Radiation Belts

    Science.gov (United States)

    Bolton, S. J.; Gulkis, S.; Klein, M. J.; Thorne, R. M.

    1995-01-01

    The Jovian decimetric emission is caused by the combined emission of synchrotron radiation originating from the relativistic electrons trapped in Jupiter's 'Van Allen radiation belts' and thermal emission from the planet's atmosphere. Synchrotron radiation characteristics and variations (which provides insight into the physical properties of Jupiter's inner radiation belts) will be amplified and discussed.

  3. Woody Allen kimpus arhitektuuriga

    Index Scriptorium Estoniae

    2000-01-01

    Woody Allen protesteerib oma uue lühifilmiga kavatsuse vastu ehitada 16-korruseline ärihoone tema New Yorgi kodu lähedale. W. Allen hindab New Yorgi ajaloolisi rajoone, mida näitab ka oma filmides

  4. Limitations on space flight due to cosmic radiations.

    Science.gov (United States)

    CURTIS, H J

    1961-02-03

    These conclusions (10) may be summarized as follows: 1) Flight below the Van Allen belts seems reasonably safe without radiation shielding. 2) It is probably impractical to shield a rocket sufficiently to permit a man to remain in the inner Van Allen belt for more than about an hour, but it should be possible for him to go through it without serious harm. 3) Shielding for the outer Van Allen belt is possible but would have to be quite heavy if a stay of more than a few hours were contemplated. 4) The primary cosmic radiation is not intense enough to deliver a serious radiation dose, even for exposures of a few weeks, and the heavy cosmic ray primaries do not seem to present an unusual hazard.

  5. Radiation dose to surgeons in theatre | van der Merwe | South ...

    African Journals Online (AJOL)

    Objectives. To evaluate the effects of ionising radiation and radiation limits, and measure radiation doses received by surgeons in theatre. Design. Thermoluminescent dosimeter measurements of accumulated dose to specific anatomical regions of a neurosurgeon, gastroenterologist and orthopaedic surgeon performing ...

  6. Effects of ionizing radiation; Effecten van ioniserende straling

    Energy Technology Data Exchange (ETDEWEB)

    Loos, M.; Hardeman, F.; Holmstock, L.; Hurtgen, C.; Mahieu, L.; Sohier, A.; Vandecasteele, C.; Vanhavere, F.; Vanmaercke, H.; Zeevaert, T

    1998-12-01

    Starting with a brief introduction to radiation protection, the report gives an overview of exposure to ionising radiation in Belgium due to activities in relation to the nuclear fuel cycle, processing and disposal of radioactive waste and other artificial or natural sources. Where appropriate, the Belgian situation discussed from an international perspective. The radiological impact of reprocessing and non-reprocessing are compared. The biological effects of ionizing radiation, epidemiological studies as well as surveillance programmes on the Belgian territory are reported on.

  7. Van Allen probes, NOAA, GOES, and ground observations of an intense EMIC wave event extending over 12 h in magnetic local time

    OpenAIRE

    Engebretson, M. J.; Posch, J. L.; Wygant, J. R.; Kletzing, C. A.; Lessard, M. R.; Huang, C.-L.; Spence, H. E.; Smith, C. W.; Singer, H. J.; Omura, Y.; Horne, R. B.; Reeves, G. D.; Baker, D. N.; Gkioulidou, M.; Oksavik, K.

    2015-01-01

    Although most studies of the effects of EMIC waves on Earth's outer radiation belt have focused on events in the afternoon sector in the outer plasmasphere or plume region, strong magnetospheric compressions provide an additional stimulus for EMIC wave generation across a large range of local times and L shells. We present here observations of the effects of a wave event on February 23, 2014 that extended over 8 hours in UT and over 12 hours in local time, stimulated by a gradual 4-hour rise ...

  8. Allen Ginsberg kirjutab Ameerikast

    Index Scriptorium Estoniae

    2003-01-01

    Arvustus: Ginsberg, Allen. Ameerika : valik luuletusi 1947-1996 / koostanud ja toimetanud Hasso Krull ; inglise keelest tõlkinud Contra, Lauri Kitsnik, Hasso Krull, Andres Langemets, Margit Langemets, Jürgen Rooste, Tõnu Õnnepalu. Tallinn : Perioodika, 2003

  9. A comparison of outer electron radiation belt dropouts during solar ...

    Indian Academy of Sciences (India)

    O Ogunjobi

    2017-06-06

    Jun 6, 2017 ... study identifies radiation belt electron dropouts which are ultimately triggered when solar wind stream interfaces (SI) arrived at ... (Plasmapause); indicating a combination of electron cyclotron harmonic (ECH) and whistler mode waves as the contributing ... density known as the slot (Van-Allen 1959). Elec-.

  10. Survey of the Frequency Dependent Latitudinal Distribution of the Fast Magnetosonic Wave Mode from Van Allen Probes Electric and Magnetic Field Instrument and Integrated Science Waveform Receiver Plasma Wave Analysis

    Science.gov (United States)

    Boardsen, Scott A.; Hospodarsky, George B.; Kletzing, Craig A.; Engebretson, Mark J.; Pfaff, Robert F.; Wygant, John R.; Kurth, William S.; Averkamp, Terrance F.; Bounds, Scott R.; Green, Jim L.; hide

    2016-01-01

    We present a statistical survey of the latitudinal structure of the fast magnetosonic wave mode detected by the Van Allen Probes spanning the time interval of 21 September 2012 to 1 August 2014. We show that statistically, the latitudinal occurrence of the wave frequency (f) normalized by the local proton cyclotron frequency (f(sub cP)) has a distinct funnel-shaped appearance in latitude about the magnetic equator similar to that found in case studies. By comparing the observed E/B ratios with the model E/B ratio, using the observed plasma density and background magnetic field magnitude as input to the model E/B ratio, we show that this mode is consistent with the extra-ordinary (whistler) mode at wave normal angles (theta(sub k)) near 90 deg. Performing polarization analysis on synthetic waveforms composed from a superposition of extra-ordinary mode plane waves with theta(sub k) randomly chosen between 87 and 90 deg, we show that the uncertainty in the derived wave normal is substantially broadened, with a tail extending down to theta(sub k) of 60 deg, suggesting that another approach is necessary to estimate the true distribution of theta(sub k). We find that the histograms of the synthetically derived ellipticities and theta(sub k) are consistent with the observations of ellipticities and theta(sub k) derived using polarization analysis.We make estimates of the median equatorial theta(sub k) by comparing observed and model ray tracing frequency-dependent probability occurrence with latitude and give preliminary frequency dependent estimates of the equatorial theta(sub k) distribution around noon and 4 R(sub E), with the median of approximately 4 to 7 deg from 90 deg at f/f(sub cP) = 2 and dropping to approximately 0.5 deg from 90 deg at f/f(sub cP) = 30. The occurrence of waves in this mode peaks around noon near the equator at all radial distances, and we find that the overall intensity of these waves increases with AE*, similar to findings of other studies.

  11. Remembering Julius C. Allen.

    Science.gov (United States)

    Pressley, Thomas A

    2007-06-03

    Our respected colleague and friend, Dr. Julius C. Allen, passed away on Thursday, February 10, 2005. Known to his friends and family as "Julie," Dr. Allen was an internationally-recognized investigator in cardiovascular science and an early contributor to the biochemistry of the Na,K-pump. His work was inevitably multi-disciplinary, with contributions to biochemistry, physiology, and pharmacology. He helped develop and later directed the Graduate Program for Cardiovascular Sciences at Baylor College of Medicine. Beyond his science, Dr. Allen was a strong advocate of progressive social and political reform, as well as a passionate sports enthusiast. With his sense of humor, it was impossible not to have a good time when he was around. His friendship, wise advice, and experience will be sorely missed.

  12. Askey, Prof. Richard Allen

    Indian Academy of Sciences (India)

    Fellow Profile. Elected: 1988 Honorary. Askey, Prof. Richard Allen. Date of birth: 4 June 1933. Address: 5915, American Parkway, Apt. 228, Madison, WI 43718, U.S.A.. Contact: Office: (+1-608) 262 2880. Residence: (+1-608) 233 7900. Fax: (+1-608) 263 8891. Email: askey@math.wisc.edu. YouTube; Twitter; Facebook ...

  13. Pattern-free thermal modulator via thermal radiation between Van der Waals materials

    Science.gov (United States)

    Liu, Xianglei; Shen, Jiadong; Xuan, Yimin

    2017-10-01

    Modulating heat flux provides a platform for a plethora of emerging devices such as thermal diodes, thermal transistors, and thermal memories. Here, a pattern-free noncontact thermal modulator is proposed based on the mechanical rotation between two Van der Waals films with optical axes parallel to the surfaces. A modulation contrast can reach a value higher than 5 for hexagonal Boron Nitride (hBN) films separated by a nanoscale gap distance. The dominant radiative heat exchange comes from the excitation of both Type I and Type II hyperbolic surface phonon polaritons (HSPhPs) at the vacuum-hBN interface for different orientations, while the large modulation contrast is mainly attributed to the mismatching Type I HSPhPs induced by rotation. This work opens the possibility to design cheap thermal modulators without relying on nanofabrication techniques, and paves the way to apply natural Van der Waals materials in manipulating heat currents in an active way.

  14. Space Flight Ionizing Radiation Environments

    Science.gov (United States)

    Koontz, Steve

    2017-01-01

    The space-flight ionizing radiation (IR) environment is dominated by very high-kinetic energy-charged particles with relatively smaller contributions from X-rays and gamma rays. The Earth's surface IR environment is not dominated by the natural radioisotope decay processes. Dr. Steven Koontz's lecture will provide a solid foundation in the basic engineering physics of space radiation environments, beginning with the space radiation environment on the International Space Station and moving outward through the Van Allen belts to cislunar space. The benefits and limitations of radiation shielding materials will also be summarized.

  15. Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE)

    Science.gov (United States)

    Mitchell, D. G.; Lanzerotti, L. J.; Kim, C. K.; Stokes, M.; Ho, G.; Cooper, S.; Ukhorskiy, A.; Manweiler, J. W.; Jaskulek, S.; Haggerty, D. K.; Brandt, P.; Sitnov, M.; Keika, K.; Hayes, J. R.; Brown, L. E.; Gurnee, R. S.; Hutcheson, J. C.; Nelson, K. S.; Paschalidis, N.; Rossano, E.; Kerem, S.

    2013-11-01

    The Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) on the two Van Allen Probes spacecraft is the magnetosphere ring current instrument that will provide data for answering the three over-arching questions for the Van Allen Probes Program: RBSPICE will determine "how space weather creates the storm-time ring current around Earth, how that ring current supplies and supports the creation of the radiation belt populations," and how the ring current is involved in radiation belt losses. RBSPICE is a time-of-flight versus total energy instrument that measures ions over the energy range from ˜20 keV to ˜1 MeV. RBSPICE will also measure electrons over the energy range ˜25 keV to ˜1 MeV in order to provide instrument background information in the radiation belts. A description of the instrument and its data products are provided in this chapter.

  16. enkele aantekeninge by die debat oor die uitleg van die dordtse ...

    African Journals Online (AJOL)

    Test

    verwerpen en dat Gods arbeid om den mensch tot bekeering te brengen in vele gevallen werkelijk door deze verijdelt wordt. 4. Gij leert, dat God de zaligheid van allen wil en diensvolgens Jezus. Christus ten behoeve en ter behoudenis van allen in de wereld gezonden heeft. Aangesien die eerste drie punte van Ds. Kotzé ...

  17. Allen's astrophysical quantities

    CERN Document Server

    2000-01-01

    This new, fourth, edition of Allen's classic Astrophysical Quantities belongs on every astronomer's bookshelf. It has been thoroughly revised and brought up to date by a team of more than ninety internationally renowned astronomers and astrophysicists. While it follows the basic format of the original, this indispensable reference has grown to more than twice the size of the earlier editions to accommodate the great strides made in astronomy and astrophysics. It includes detailed tables of the most recent data on: - General constants and units - Atoms, molecules, and spectra - Observational astronomy at all wavelengths from radio to gamma-rays, and neutrinos - Planetary astronomy: Earth, planets and satellites, and solar system small bodies - The Sun, normal stars, and stars with special characteristics - Stellar populations - Cataclysmic and symbiotic variables, supernovae - Theoretical stellar evolution - Circumstellar and interstellar material - Star clusters, galaxies, quasars, and active galactic nuclei ...

  18. Space Weather Effects in the Earth's Radiation Belts

    Science.gov (United States)

    Baker, D. N.; Erickson, P. J.; Fennell, J. F.; Foster, J. C.; Jaynes, A. N.; Verronen, P. T.

    2018-02-01

    The first major scientific discovery of the Space Age was that the Earth is enshrouded in toroids, or belts, of very high-energy magnetically trapped charged particles. Early observations of the radiation environment clearly indicated that the Van Allen belts could be delineated into an inner zone dominated by high-energy protons and an outer zone dominated by high-energy electrons. The energy distribution, spatial extent and particle species makeup of the Van Allen belts has been subsequently explored by several space missions. Recent observations by the NASA dual-spacecraft Van Allen Probes mission have revealed many novel properties of the radiation belts, especially for electrons at highly relativistic and ultra-relativistic kinetic energies. In this review we summarize the space weather impacts of the radiation belts. We demonstrate that many remarkable features of energetic particle changes are driven by strong solar and solar wind forcings. Recent comprehensive data show broadly and in many ways how high energy particles are accelerated, transported, and lost in the magnetosphere due to interplanetary shock wave interactions, coronal mass ejection impacts, and high-speed solar wind streams. We also discuss how radiation belt particles are intimately tied to other parts of the geospace system through atmosphere, ionosphere, and plasmasphere coupling. The new data have in many ways rewritten the textbooks about the radiation belts as a key space weather threat to human technological systems.

  19. Ultra-low-frequency wave-driven diffusion of radiation belt relativistic electrons

    OpenAIRE

    Su, Zhenpeng; Zhu, Hui; Xiao, Fuliang; Zong, Q.-G.; Zhou, X.-Z.; Zheng, Huinan; Wang, Yuming; Wang, Shui; Hao, Y.-X.; Gao, Zhonglei; He, Zhaoguo; Baker, D. N.; Spence, H. E.; Reeves, G. D.; Blake, J. B.

    2015-01-01

    Van Allen radiation belts are typically two zones of energetic particles encircling the Earth separated by the slot region. How the outer radiation belt electrons are accelerated to relativistic energies remains an unanswered question. Recent studies have presented compelling evidence for the local acceleration by very-low-frequency (VLF) chorus waves. However, there has been a competing theory to the local acceleration, radial diffusion by ultra-low-frequency (ULF) waves, whose importance ha...

  20. Solar wind conditions leading to efficient radiation belt electron acceleration: A superposed epoch analysis

    OpenAIRE

    Li, W; Thorne, RM; Bortnik, J; Baker, DN; Reeves, GD; Kanekal, SG; Spence, HE; Green, JC

    2015-01-01

    ©2015. American Geophysical Union. All Rights Reserved. Determining preferential solar wind conditions leading to efficient radiation belt electron acceleration is crucial for predicting radiation belt electron dynamics. Using Van Allen Probes electron observations ( > 1 MeV) from 2012 to 2015, we identify a number of efficient and inefficient acceleration events separately to perform a superposed epoch analysis of the corresponding solar wind parameters and geomagnetic indices. By directly c...

  1. Frances Allen Wins Turing Award

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 12; Issue 8. Frances Allen Wins Turing Award. Priti Shankar. Article-in-a-Box Volume 12 Issue 8 August 2007 pp 5-5. Fulltext. Click here to view fulltext PDF. Permanent link: http://www.ias.ac.in/article/fulltext/reso/012/08/0005-0005. Author Affiliations.

  2. Onderzoek betreffende de lotgevallen van verplegenden, die een klinische vorm van tuberculose hebben gehad (medisch zowel als sociaal bezien)

    NARCIS (Netherlands)

    Oordt, Pieter van

    1961-01-01

    Het voorkomen van tuberculose onder verplegenden heeft zeer lang de aandacht gehad van allen, die bij de bestrijding betrokken waren. Diagnostische en therapeutische mogelijkheden waren echter slechts in beperkte mate aanwezig en verschilden niet veel van die, welke voor de gehele bevolking golden.

  3. On the relation between radiation belt electrons and solar wind parameters/geomagnetic indices: dependence on the first adiabatic invariant and L*

    OpenAIRE

    Zhao, H.; Baker, D. N.; Jaynes, A. N.; Li, X.; Elkington, S. R.; Kanekal, S. G.; Spence, H. E.; Boyd, A. J.; Huang, C-L; Forsyth, C.

    2017-01-01

    The relation between radiation belt electrons and solar wind/magnetospheric processes is of particular interest due to both scientific and practical needs. Though many studies have focused on this topic, electron data from Van Allen Probes with wide L shell coverage and fine energy resolution, for the first time, enabled this statistical study on the relation between radiation belt electrons and solar wind parameters/geomagnetic indices as a function of first adiabatic invariant μ and L*. Goo...

  4. Calculations of synchrotron emission from the terrestrial radiation belts

    Science.gov (United States)

    Johnson, R.

    1972-01-01

    A theoretical model was developed to allow for the calculation of the synchrotron emission arising from high energy electrons trapped in the Van Allen belts of a planet with a dipole magnetic field. The model is general enough to allow for the calculation of the intensity of radiation received by an observer at any distance from and any latitude about the planet. The model is used to compute the emission from the earth's Van Allen belts that one should expect at various latitudes at a distance of 1.92 earth radii, the position of the Radio Astronomy Explorer satellite that was launched in 1968, for the frequencies 1.3 MHz and 2.2 MHz.

  5. Greenhouse with integrated conversion of heat radiation to electricity. Electricity producing greenhouse (ELKAS); Kas met geintegreerde omzetting van warmtestraling naar elektrische energie. Elektriciteits Leverende Kas (ELKAS)

    Energy Technology Data Exchange (ETDEWEB)

    Sonneveld, P.J.; Swinkels, G.L.A.M.; Bot, G.P.A.

    2007-05-15

    A new development has started in a second generation of energy-supplying greenhouses. The objective of this study is to develop the technology that converts the heat from solar energy into high quality electrical energy with photovoltaic (PV) cells. The PV cells require extra cooling due to the heat load of the concentrated radiation. This heat can also be used for storage in an aquifer of heat buffer. The characteristics of different solar cell materials have been examined for this application. All parts referred to in this article will be integrated in a new type of greenhouse of approximately 75 m{sup 2} on the premises of Plant Research International (PRI). (mk) [Dutch] Er is een nieuwe ontwikkeling gestart in een tweede generatie energieleverende kassen. Doel van dit project is een technologie te ontwikkelen die het warmtedeel van de zonne-energie omzet in hoogwaardige elektrische en thermische energie. Gereflecteerde straling wordt omgezet in elektrische energie met photovoltaische (PV) cellen. De PV cellen vereisen extra koeling door de hoge warmtelast van de geconcentreerde straling. Deze warmte kan eventueel gebruikt worden voor opslag in een aquifer of warmtebuffer. De eigenschappen van verschillende zonnecel materialen zijn onderzocht voor deze toepassing. Alle in dit artikel genoemde onderdelen worden geintegreerd in een nieuw type kas van ongeveer 75 m{sup 2} op het terrein van Plant Research International (PRI)

  6. 49 ALLEN'S DEFENCE OF THE EXTENDED ORDERING ...

    African Journals Online (AJOL)

    "Why can forms such as air-conch t ion anu tape-record occur as verbs, while the forms water- ition and ...... Allen's (1978:238-240) reanalysis of the counterexamples 1n (39) above is not without problems, however. ... examples presented by Allen (1978;240) in support of the claim that. -ness, -ish and -y attach to lexicalized ...

  7. Radiation level measurements around the site of the EPZ nuclear power plant at Borssele in 2006; Stralingsniveaumetingen rond het terrein van de EPZ kerncentrale te Borssele in 2006

    Energy Technology Data Exchange (ETDEWEB)

    Farahmand, M.; Goerts, P.C.

    2009-07-01

    In 2006, the radiation level at the site boundary of the Borssele nuclear power plant (NPP) was below the maximum permitted level. This is the conclusion of this report based on field measurements carried out by the RIVM. Dutch legislation on the use of nuclear energy requires that the maximum effective dose received by persons outside the site boundary of the NPP Borssele does not exceed 40 microsievert annually. Control measurements of the radiation level were therefore carried out at eight locations at the site boundary, within the framework of the MONET monitoring network, which falls under the administrative management of the RIVM. The measurements are processed by first subtracting the natural background value from the measured value and then translating the result into the effective radiation dose for an individual, by applying the so-called ABC-factor (actual exposure correction factor). ABC-factors are closely linked with the specific use of the site where the effective radiation dose can be incurred. An ABC-factor of 0.2 for the site boundary of the NPP Borssele has been set by legislation. By order of the Department of Nuclear Safety, Security and Safeguards of the Ministry of Housing, Spatial Planning and the Environment of the Netherlands, the RIVM reports annually on whether the NPP Borssele meets this criterion for maintaining its license. Both the daily averages of the eight MONET-monitors around the NPP Borssele and an explanation of how the background level at each measuring location was determined are provided in the report. In 2006, the highest value, following the correction for the natural background level, amounted to 85.1 microsievert. This was translated into a maximum effective dose of 17 microsievert following the application of the ABC-factor. [Dutch] Het stralingsniveau aan de terreingrens van kerncentrale Borssele lag in 2006 onder het toegestane maximum. Dit blijkt uit controlemetingen van het RIVM. Volgens de Kernenergiewetvergunning

  8. H. Julian Allen: An Appreciation

    Science.gov (United States)

    Vincenti, Walter G.; Boyd, John W.; Bugos, Glenn E.

    2007-01-01

    Harvey Allen is best known as the genius behind the blunt-body concept, published in 1953, which enables spacecraft to return safely home through Earth's dense atmosphere. He was also an extraordinary research leader, who led a world-class research program in hypersonics at the NACA Ames Aeronautical Laboratory. This paper reviews his career as one of America's leading theorists and experimenters, including his engineering education at Stanford, his work on the inverse problem of calculating the airfoil profile to obtain a desired pressure distribution, his hand in constructing wind tunnels and experimental facilities at Ames, and his pioneering and wide-ranging work on atmospheric re-entry. It concludes with an appreciation of his uniquely inspirational style of research management, and of his magnetic personality.

  9. Evidence for Degradation of the Chrome Yellows in Van Gogh's Sunflowers: A Study Using Noninvasive In Situ Methods and Synchrotron-Radiation-Based X-ray Techniques.

    Science.gov (United States)

    Monico, Letizia; Janssens, Koen; Hendriks, Ella; Vanmeert, Frederik; Van der Snickt, Geert; Cotte, Marine; Falkenberg, Gerald; Brunetti, Brunetto Giovanni; Miliani, Costanza

    2015-11-16

    This paper presents firm evidence for the chemical alteration of chrome yellow pigments in Van Gogh's Sunflowers (Van Gogh Museum, Amsterdam). Noninvasive in situ spectroscopic analysis at several spots on the painting, combined with synchrotron-radiation-based X-ray investigations of two microsamples, revealed the presence of different types of chrome yellow used by Van Gogh, including the lightfast PbCrO4 and the sulfur-rich PbCr1-x Sx O4 (x≈0.5) variety that is known for its high propensity to undergo photoinduced reduction. The products of this degradation process, i.e., Cr(III) compounds, were found at the interface between the paint and the varnish. Selected locations of the painting with the highest risk of color modification by chemical deterioration of chrome yellow are identified, thus calling for careful monitoring in the future. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  10. Radiation level measurements around the site of the EPZ nuclear power plant at Borssele in 2007; Stralingsniveaumetingen rond het terrein van de EPZ kerncentrale te Borssele in 2007

    Energy Technology Data Exchange (ETDEWEB)

    Farahmand, M.; Goerts, P.C.

    2009-07-01

    Dutch legislation on the use of nuclear energy requires that the maximum effective dose received by persons outside the site boundary of the NPP Borssele does not exceed 40 microsievert annually. Control measurements of the radiation level were therefore carried out at eight locations at the site boundary, within the framework of the MONET monitoring network, which falls under the administrative management of the RIVM. The measurements are processed by first subtracting the natural background value from the measured value and then translating the result into the effective radiation dose for an individual, by applying the so-called ABC-factor (actual exposure correction factor). ABC-factors are closely linked with the specific use of the site where the effective radiation dose can be incurred. An ABC-factor of 0.2 for the site boundary of the NPP Borssele has been set by legislation. By order of the Department of Nuclear Safety, Security and Safeguards of the Ministry of Housing, Spatial Planning and the Environment of the Netherlands, the RIVM reports annually on whether the NPP Borssele meets this criterion for maintaining its license. Both the daily averages of the eight MONET monitors around the NPP Borssele and an explanation of how the background level at each measuring location was determined are provided in the report. In 2006, the highest value, following the correction for the natural background level, amounted to 85.1 microsievert. This was translated into a maximum effective dose of 17 microsievert following the application of the ABC-factor. [Dutch] Het stralingsniveau aan de terreingrens van kerncentrale Borssele lag in 2006 onder het toegestane maximum. Dit blijkt uit controlemetingen van het RIVM. Volgens de Kernenergiewetvergunning moet de centrale ervoor zorgen dat personen buiten de terreingrens een effectieve stralingsdosis ontvangen van ten hoogste 40 microsievert per jaar. Om dit te controleren wordt op acht punten op de terreingrens het

  11. Radiation Belt Storm Probe (RBSP) Mission

    Science.gov (United States)

    Sibeck, D. G.; Fox, N.; Grebowsky, J. M.; Mauk, B. H.

    2009-01-01

    Scheduled to launch in May 2012, NASA's dual spacecraft Living With a Star Radiation Belt Storm Probe mission carries the field and particle instrumentation needed to determine the processes that produce enhancements in radiation belt ion and electron fluxes, the dominant mechanisms that cause the loss of relativistic electrons, and the manner by which the ring current and other geomagnetic phenomena affect radiation belt behavior. The two spacecraft will operate in low-inclination elliptical lapping orbits around the Earth, within and immediately exterior to the Van Allen radiation belts. During course of their two year primary mission, they will cover the full range of local times, measuring both AC and DC electric and magnetic fields to 10kHz, as well as ions from 50 eV to 1 GeV and electrons with energies ranging from 50 eV to 10 MeV.

  12. ALLEN BUCKNER KANAVELFOUNDER OF HAND SURGERY

    Directory of Open Access Journals (Sweden)

    K. A. Egiazaryan

    2012-01-01

    Full Text Available Allen Bakner Kanavela's biography - the surgeon who has brought the invaluable contribution of a world scale in development of the general surgery and of hand surgery is presented.

  13. Decarbonylative cycloaddition of phthalic anhydrides with allenes.

    Science.gov (United States)

    Ochi, Yosuke; Kurahashi, Takuya; Matsubara, Seijiro

    2011-03-18

    The decarbonylative cycloadditions of phthalic anhydrides with allenes were performed by using nickel catalyst. The asymmetric variant of the cycloaddition was also achieved by using chiral phosphine ligands to provide δ-lactones enantioselectively.

  14. Modeling inward diffusion and slow decay of energetic electrons in the Earth's outer radiation belt

    OpenAIRE

    Ma, Q; Li, W; Thorne, RM; Ni, B; Kletzing, CA; Kurth, WS; Hospodarsky, GB; Reeves, GD; Henderson, MG; Spence, HE; Baker, DN; Blake, JB; Fennell, JF; Claudepierre, SG; Angelopoulos, V

    2015-01-01

    ©2015. American Geophysical Union. All Rights Reserved. A new 3-D diffusion code is used to investigate the inward intrusion and slow decay of energetic radiation belt electrons ( > 0.5MeV) observed by the Van Allen Probes during a 10day quiet period on March 2013. During the inward transport, the peak differential electron fluxes decreased by approximately an order of magnitude at various energies. Our 3-D radiation belt simulation including radial diffusion and pitch angle and energy diffus...

  15. Palladium-catalyzed asymmetric silaboration of allenes.

    Science.gov (United States)

    Ohmura, Toshimichi; Taniguchi, Hiroki; Suginome, Michinori

    2006-10-25

    An enantioselective silaboration of allenes was achieved using an achiral silylborane in the presence of a palladium catalyst bearing a chiral monodentate phosphine ligand. (R)-2-Bis(3,5-dimethylphenyl)phosphino-1,1'-binaphthyl gave the highest enantioselectivities in the addition of (diphenylmethylsilyl)pinacolborane to the internal C=C bond of terminal allenes at 0 degrees C, giving the corresponding beta-borylallylsilanes in high yields with high enantiomeric excesses. The enantioselectivity depended on the bulkiness of substituents of allenes: the enantiomeric excesses were found to be 91-93% ee (R = tert- and sec-alkyl), 88-90% ee (R = aryl), and 80-82% ee (R = prim-alkyl and Me) at 0 degrees C. Perfect chirality transfer was observed in the intramolecular cyclization reactions of the functionalized allylsilanes, affording highly enantioenriched cyclic alkenylboranes, which underwent Suzuki-Miyaura coupling with aryl halides.

  16. Study the Precipitation of Radiation Belt Electrons during the Rapid Dropout Events

    Science.gov (United States)

    Tu, W.; Cunningham, G.; Li, X.; Chen, Y.

    2015-12-01

    During the main phase of storms, the relativistic electron flux in the radiation belt can drop by orders of magnitude on timescales of a few hours. Where do the electrons go? This is one of the most important outstanding questions in radiation belt studies. Radiation belt electrons can be lost either by transport across the magnetopause into interplanetary space or by precipitation into the atmosphere. In this work we first conduct a survey of the MeV electron dropouts using the Van Allen Probes data in conjunction with the low-altitude measurements of precipitating electrons by 6 NOAA/POES satellites. The dropout events are categorized into three types: precipitation-loss dominant, outward radial diffusion dominant, or with contributions from both mechanisms. The survey results suggest the relative importance of precipitation and outward radial diffusion to the fast dropouts of radiation belt electrons, and their extent in L-shell and electron energy. Then, for specific events identified as dominated by precipitation loss, we use the Drift-Diffusion model, which includes the effects of azimuthal drift and pitch angle diffusion, to simulate both the electron dropout observed by Van Allen Probes and the distributions of drift-loss-cone electrons observed by multiple low-earth-orbit satellites (6 POES and the Colorado Student Space Weather Experiment). The model quantifies the electron precipitation loss and pitch angle diffusion coefficient, Dxx, with high temporal and spatial resolution. Finally, by comparing the Dxx derived from the model with those estimated from the quasi-linear theory using wave data from Van Allen Probes and other event-specific wave models, we are able to test the validity of quasi-linear theory and seek direct evidence of the wave-particle interactions during the dropouts.

  17. NASA's Radiation Belt Storm Probe Mission

    Science.gov (United States)

    Sibeck, David G.

    2011-01-01

    NASA's Radiation Belt Storm Probe (RBSP) mission, comprising two identically-instrumented spacecraft, is scheduled for launch in May 2012. In addition to identifying and quantifying the processes responsible for energizing, transporting, and removing energetic particles from the Earth's Van Allen radiation, the mission will determine the characteristics of the ring current and its effect upon the magnetosphere as a whole. The distances separating the two RBSP spacecraft will vary as they move along their 1000 km altitude x 5.8 RE geocentric orbits in order to enable the spacecraft to separate spatial from temporal effects, measure gradients that help identify particle sources, and determine the spatial extent of a wide array of phenomena. This talk explores the scientific objectives of the mission and the manner by which the mission has been tailored to achieve them.

  18. Influence of lightning generated whistlers on radiation belt losses in the plasmasphere.

    Science.gov (United States)

    Santolik, O.; Ripoll, J. F.; Farges, T.; Kolmasova, I.; Kurth, W. S.; Hospodarsky, G. B.; Kletzing, C.

    2016-12-01

    It is widely accepted that the slot region of the Van Allen radiation belts is sculpted by the presence of whistler mode waves, especially by plasmaspheric hiss emissions. Substantial evidence exists that plasmaspheric hiss itself can arise from strong emissions of whistler-mode chorus, generated in the outer zone equatorial region and propagated to high latitudes and inward, filling thus the plasmasphere and forming hiss. However the debate on the origin of hiss is still open to other possibilities: local generation and accumulation or triggering by lightning generated whistlers. We show evidence that the latter possibility can play a role and that lightning generated whistlers can, at least in some cases, influence the radiation belt dynamics. We use multicomponent measurements of whistlers and hiss by the Waves instrument of Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) onboard the Van Allen Probes spacecraft as our primary data source. We combine this data set with local measurements of the plasma density based on the determination of the upper hybrid resonance frequency and with the data of the World Wide Lightning Location Network which are used to localize the source lightning discharges and their radiated energy. Using these unique data sets we model the coefficients of quasi-linear pitch angle diffusion and we estimate effects of these waves on the decay rates of radiation belt electrons.

  19. Ultra-low-frequency wave-driven diffusion of radiation belt relativistic electrons.

    Science.gov (United States)

    Su, Zhenpeng; Zhu, Hui; Xiao, Fuliang; Zong, Q-G; Zhou, X-Z; Zheng, Huinan; Wang, Yuming; Wang, Shui; Hao, Y-X; Gao, Zhonglei; He, Zhaoguo; Baker, D N; Spence, H E; Reeves, G D; Blake, J B; Wygant, J R

    2015-12-22

    Van Allen radiation belts are typically two zones of energetic particles encircling the Earth separated by the slot region. How the outer radiation belt electrons are accelerated to relativistic energies remains an unanswered question. Recent studies have presented compelling evidence for the local acceleration by very-low-frequency (VLF) chorus waves. However, there has been a competing theory to the local acceleration, radial diffusion by ultra-low-frequency (ULF) waves, whose importance has not yet been determined definitively. Here we report a unique radiation belt event with intense ULF waves but no detectable VLF chorus waves. Our results demonstrate that the ULF waves moved the inner edge of the outer radiation belt earthward 0.3 Earth radii and enhanced the relativistic electron fluxes by up to one order of magnitude near the slot region within about 10 h, providing strong evidence for the radial diffusion of radiation belt relativistic electrons.

  20. Star tracker and vision systems performance in a high radiation environment

    DEFF Research Database (Denmark)

    Jørgensen, John Leif; Riis, Troels; Betto, Maurizio

    1999-01-01

    A part of the payload of the second Ariane 5 prototype vehicle to be launched by Arianespace, was a small technology demonstration satellite. On October 30th, 1997, this test satellite, dubbed Teamsat, was launched into Geostationary Transfer Orbit and would as such pass the Van Allen radiation...... belts twice per orbit. One of the experiments onboard Teamsat was the so-called Autonomous Vision System (AVS). The AVS instrument is a fully autonomous star tracker with several advanced features for non-stellar object detection and tracking, real-time image compression and transmission. The objectives...

  1. UK-5 Van Allen belt radiation exposure: A special study to determine the trapped particle intensities on the UK-5 satellite with spatial mapping of the ambient flux environment

    Science.gov (United States)

    Stassinopoulos, E. G.

    1972-01-01

    Vehicle encountered electron and proton fluxes were calculated for a set of nominal UK-5 trajectories with new computational methods and new electron environment models. Temporal variations in the electron data were considered and partially accounted for. Field strength calculations were performed with an extrapolated model on the basis of linear secular variation predictions. Tabular maps for selected electron and proton energies were constructed as functions of latitude and longitude for specified altitudes. Orbital flux integration results are presented in graphical and tabular form; they are analyzed, explained, and discussed.

  2. Chorus Wave Energy Budget Analysis in the Earth's Radiation Belts

    Science.gov (United States)

    Blancarte, J.; Agapitov, O. V.; Mozer, F.

    2016-12-01

    Whistler-mode chorus emissions are important electromagnetic waves in the Earth's magnetosphere, where they continuously scatter and accelerate electrons of the outer radiation belt, controlling radiation hazards to satellites and astronauts. Here, we present an analysis of Van Allen Probes electric and magnetic field VLF waveform data, evaluating the wave energy budget, and show that a significant fraction of the energy corresponds to very oblique waves. Such waves, with a generally much smaller (up to 10 times) magnetic power than parallel waves, typically have comparable or even larger total energy. Very oblique waves may turn out to be a crucial agent of energy redistribution in the Earth's radiation belts and also provide nonlinear effects due to wave-particle interaction through the Landau resonance due to the significant electric field component parallel to the background magnetic field.

  3. Bound state in positron scattering by allene

    Science.gov (United States)

    Barbosa, Alessandra Souza; Sanchez, Sergio d'Almeida; Bettega, Márcio H. F.

    2017-12-01

    We report integral and differential cross sections for positron collisions with allene, calculated with the Schwinger multichannel method. The cross sections were computed in the static-polarization approximation for energies up to 7 eV. We have tested a series of single-particle basis sets and different polarization schemes to improve the description of low-energy positron scattering by the allene molecule. We have found that the use of extra centers with no net charge with additional single-particle s - and p -type functions centered at them are essential in order to accurately reproduce the polarization potential and, hence, obtain proper scattering cross sections. The choice of the allene molecule was due to the fact that it is a highly symmetric molecule with no permanent dipole moment and would allow several different calculations. Our cross sections are compared to the available experimental data for the total cross section with a reasonable agreement after correcting their results due to the low angular discrimination of their apparatus. Also, a virtual state was observed in the integral cross section that became a bound state when the description of the polarization potential is improved. We also observed a Ramsauer-Townsend minimum in the cross section whose location varies from 2.7 to 3.4 eV, depending on the polarization scheme used in the calculations.

  4. Novel Asymmetric Wittig Reaction: Synthesis of Chiral Allenic Esters

    OpenAIRE

    Melo, Teresa M. V. D. Pinho e; Cardoso, Ana L.; Gonsalves, António M. D'A Rocha; Pessoa, João Costa; José A. Paixão; Beja, Ana M

    2004-01-01

    Wittig reactions between 10-(phenylsulfonyl)isobornyl (triphenylphosphoranylidene)acetates (1 and 6) and ketenes resulted in asymmetric induction, with the selective synthesis of allenes with axial chirality. Use of the (1R)-(-)-10-(phenylsulfonyl)isoborneol unit allows the synthesis of allenes with S configuration, whereas use of the (1S)-(+)-10-(phenylsulfonyl)isoborneol unit produces allenes with R configuration. The structure of (1R)-(-)-10-(phenylsulfonyl)isobornyl (S)-5,5-dimethylhexa-2...

  5. Nonlinear local parallel acceleration of electrons through Landau trapping by oblique whistler mode waves in the outer radiation belt

    OpenAIRE

    Agapitov, O. V.; Artemyev, A. V.; Mourenas, D.; Mozer, F. S.; Krasnoselskikh, V.

    2015-01-01

    International audience; Simultaneous observations of electron velocity distributions and chorus waves by the Van Allen Probe B are analyzed to identify long-lasting (more than 6 h) signatures of electron Landau resonant interactions with oblique chorus waves in the outer radiation belt. Such Landau resonant interactions result in the trapping of ˜1-10 keV electrons and their acceleration up to 100-300 keV. This kind of process becomes important for oblique whistler mode waves having a signifi...

  6. Woody Allen, serial schlemiel ?

    Directory of Open Access Journals (Sweden)

    Frédérique Brisset

    2011-04-01

    Full Text Available Woody Allen a développé au fil des années une persona cinématographique de schlemiel new-yorkais aisément reconnaissable par le spectateur. Elle marque nombre de ses films, qu’il y apparaisse en tant qu’acteur ou y dirige des substituts comédiens comme déclinaisons de lui-même. Si cette figure prototypique est le fondement de la sérialité dans sa filmographie, il est des traits stylistiques qui en portent trace tout au long de son œuvre : la récurrence annuelle de ses réalisations, la signature formelle symbolisée par ses génériques à la typographie singulière, le rythme de ses dialogues ponctués d’interjections et l’usage de l’autocitation sont autant de procédés qui marquent son cinéma d’un sceau très personnel. Ils fonctionnent comme des clins d’œil au spectateur qui reçoit dès lors LE Woody Allen millésimé comme une invitation à retrouver son microcosme. Ainsi la sérialité se pose comme à la fois initiale et conséquentielle de son système filmique, processus de création unique dans le cinéma américain.Woody Allen has long constructed a cinematographic persona of schlemiel New- Yorker that the audience can easily identify. It impacts most of his films, whether he stars in them or directs “substitute” actors to impersonate his character. If this prototypical figure is the basis of seriality in his cinematography, serial stylistic features can also be found all along his career: the annual recurrence of his productions, the formal signature symbolised by the typography of his singular credit titles, his rhythmical interjection-punctuated dialogues and the use of self-quotation imprint a very personal seal upon his movies. They all work as a recognition signals for the audience who thus receive THE Woody Allen vintage as an invitation to re-enter his microcosm. Seriality is then both initial and consequential to his cinematographic system, a unique creative process in American film history.

  7. Chorus Emission Source Spatial Scales in the Terrestrial Radiation Belts

    Science.gov (United States)

    Agapitov, O. V.; Mozer, F.; Blum, L. W.; Wygant, J. R.; Bonnell, J. W.; Shastun, V.

    2016-12-01

    The key parameters for either non-linear wave particle interactions or for the quasi-linear approach are the temporal and spatial scales of the wave source region and coherence of the oscillations in a wave package. Both of these scales (the source scale and the coherence scale) are not well-established experimentally. We investigated both of these scales using coordinated multi-point measurements from the THEMIS and Van Allen Probes missions. To accomplish these objectives, we collected long intervals of six components VLF wave measurements (16384 s-1) aboard the Van Allen Probes in the outer radiation belt during close lapping events. The spatial scales of the chorus wave source region have been found to be around 400-600 km in transverse to the background magnetic field direction for L-shells from 4 to 6. The coherence spatial and temporal scales for chorus has been found to be less/about 100 km. The results obtained from the high resolution waveform analysis have been confirmed by the THEMIS continuous measurements (FBK and FFT)

  8. Macular pseudohaemorrhage secondary to Allen Dot artefact.

    Science.gov (United States)

    Michaels, Luke; Alexander, Philip; Newsom, Richard

    2015-01-05

    A 34-year-old highly myopic (-11.00 D) woman presented to eye clinic with a 3 day history of right eye paracentral blurring. Visual acuities were 6/6 bilaterally. Clinical examination was normal. Fundus photography showed the classic appearance of a macular haemorrhage. This is a recognised complication of high myopia and would have accounted for the patient's symptoms. However, further photography showed that the haemorrhage seemed to 'jump' around the fundus and was even present in the fellow eye. The apparent haemorrhage was revealed to be an imaging artefact. The 'Allen Dot' is a 6 mm black mask incorporated into retinal cameras to reduce reflection. Rarely, in highly myopic eyes, optical artefact can result. To the best of our knowledge, we are the first in the literature to report artefacts from the Allen Dot masquerading as ophthalmic disease. This case re-iterates the importance of clinical examination, especially in high myopes, given the current trend towards virtual clinics. 2015 BMJ Publishing Group Ltd.

  9. Anatomical models for space radiation applications: an overview.

    Science.gov (United States)

    Atwell, W

    1994-10-01

    Extremely detailed computerized anatomical male (CAM) and female (CAF) models that have been developed for use in space radiation analyses are discussed and reviewed. Recognizing that the level of detail may currently be inadequate for certain radiological applications, one of the purposes of this paper is to elicit specific model improvements or requirements from the scientific user-community. Methods and rationale are presented which describe the approach used in the Space Shuttle program to extrapolate dosimetry measurements (skin doses) to realistic astronaut body organ doses. Several mission scenarios are presented which demonstrate the utility of the anatomical models for obtaining specific body organ exposure estimates and can be used for establishing cancer morbidity and mortality risk assessments. These exposure estimates are based on the trapped Van Allen belt and galactic cosmic radiation environment models and data from the major historical solar particle events.

  10. Upper hybrid waves and energetic electrons in the radiation belt

    Science.gov (United States)

    Yoon, Peter H.; Kim, Sunjung; Hwang, Junga; Shin, Dae-Kyu

    2017-05-01

    Van Allen radiation belt is characterized by energetic electrons and ions trapped in the Earth's dipolar magnetic field lines and persisting for long periods. It is also permeated by high-frequency electrostatic fluctuations whose peak intensity occurs near the upper hybrid frequency. Such a phenomenon can be understood in terms of spontaneous emission of electrostatic multiple harmonic electron cyclotron waves by thermal plasmas. In the literature, the upper hybrid fluctuations are used as a proxy for determining the electron number density, but they also contain important information concerning the energetic electrons in the radiation belt and possibly the ring current electrons. The companion paper analyzes sample quiet time events and demonstrates that the upper hybrid fluctuations are predominantly emitted by tenuous population of energetic electrons. The present paper supplements detailed formalism of spontaneous thermal emission of multiple-harmonic cyclotron waves that include upper hybrid fluctuations.

  11. On the Role of Solar Wind Discontinuities in the ULF Power Spectral Density at the Earth's Outer Radiation Belt: a Case Study

    Science.gov (United States)

    Lago, A.; Alves, L. R.; Braga, C. R.; Mendonca, R. R. S.; Jauer, P. R.; Medeiros, C.; Souza, V. M. C. E. S.; Mendes, O., Jr.; Marchezi, J.; da Silva, L.; Vieira, L.; Rockenbach, M.; Sibeck, D. G.; Kanekal, S. G.; Baker, D. N.; Wygant, J. R.; Kletzing, C.

    2016-12-01

    The solar wind incident upon the Earth's magnetosphere can produce either enhancement, depletion or no change in the flux of relativistic electrons at the outer radiation belt. During geomagnetic storms progress, solar wind parameters may change significantly, and occasionally relativistic electron fluxes at the outer radiation belt show dropouts in a range of energy and L-shells. Wave-particle interactions observed within the Van Allen belts have been claimed to play a significant role in energetic particle flux changes. The relation between changes on the solar wind parameters and the radiation belt is still a hot topic nowadays, particularly the role played by the solar wind on sudden electron flux decreases. The twin satellite Van Allen Probes measured a relativistic electron flux dropout concurrent to broad band Ultra-low frequency (ULF) waves, i.e. from 1 mHz to 10 Hz, on October 2, 2013. Magnetic field and plasma data from both ACE and WIND satellites allowed the characterization of this event as being an interplanetary coronal mass ejection in conjunction with shock. The interaction of this event with the Earth's magnetosphere was modeled using a global magnetohydrodynamic simulation and the magnetic field perturbation deep in magnetosphere could be analyzed from the model outputs. Results show the contribution of time-varying solar wind parameters to the generation of ULF waves. The power spectral densities, as a function of L-shell, were evaluated considering changes in the input parameters, e.g. magnitude and duration of dynamic pressure and magnetic field. The modeled power spectral densities are compared with Van Allen Probes data. The results provide us a clue on the solar wind characteristics that might be able to drive ULF waves in the inner magnetosphere, and also which wave modes are expected to be excited under a specific solar wind driving.

  12. 33 CFR 80.1440 - Port Allen, Kauai, HI.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Port Allen, Kauai, HI. 80.1440 Section 80.1440 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INTERNATIONAL NAVIGATION RULES COLREGS DEMARCATION LINES Pacific Islands § 80.1440 Port Allen, Kauai, HI. A line drawn from...

  13. Wave-Particle Interactions involving Whistler/Chorus Waves in the Earth's Radiation Belt

    Science.gov (United States)

    Echterling, N.; Schriver, D.; Roeder, J. L.; Fennell, J. F.

    2016-12-01

    Whistler mode chorus and electron cyclotron harmonic (ECH) waves are common in the Earth's radiation belt and have been detected by the Van Allen Probes at L 4-6 during the recovery of substorm plasma injections. During an event on January 13, 2013, quasi-periodic bursts of 16-40 keV electrons in very narrow, oblique ranges of pitch angles (75-80° and 100-105°) were observed by MagEIS, which were correlated with simultaneous bursts of upper-band, whistler-mode chorus waves. ECH emissions were also detected, but exhibited little correlation with the electron bursts. To understand the generation of these different wave emissions a linear theory and particle in cell (PIC) simulation study is being carried out using the observed velocity distribution functions as the starting point. Anisotropies and gradients in the distributions can lead to the generation of both whistler and ECH waves and the PIC simulations will be used to understand how these waves interact with the electrons non-linearly, which can lead to energy diffusion and pitch angle scattering. Comparisons between the simulation results and the Van Allen probe data will be made to determine acceleration, heating and transport of electrons in the radiation belt region due to wave-particle interactions.

  14. Electrostatic upper-hybrid waves and energetic electrons in the Earth's radiation belt

    Science.gov (United States)

    Hwang, J.; Shin, D. K.; Yoon, P. H.

    2016-12-01

    Electrostatic fluctuations near upper-hybrid frequency, which are sometimes accompanied by multiple-harmonic electron cyclotron frequencies above and below the upper-hybrid frequency, are common occurrences in the Earth's radiation belt, as revealed through Van Allen Probe observations. Such a feature is analogous to the quasi-thermal noise, or enhanced Langmuir frequency fluctuations, detected in the solar wind. Generally upper-hybrid emissions are used for estimating the background electron density, but the physical mechanism for generating such fluctuations or their possible influence on the energetic electrons has not been discussed in detail. The present paper carries out detailed analyses of data from the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) suite onboard Van Allen Probes, as well as theoretical calculation of spontaneous thermal emission. It is found that peak intensity associated with the upper-hybrid fluctuations is determined largely by tenuous energetic electrons, and that dense background electrons do not contribute much to the peak intensity. This finding implies that upper-hybrid fluctuations may not only be useful for electron density measurement, but also such a spectrum of electrostatic fluctuations may contribute to the steady-state energy spectrum of radiation belt electrons via wave-particle resonant interaction.

  15. Allenes in Asymmetric Catalysis. Asymmetric Ring-Opening of Meso-Epoxides Catalyzed by Allene-Containing Phosphine Oxides

    Science.gov (United States)

    Pu, Xiaotao; Qi, Xiangbing; Ready, Joseph M.

    2009-01-01

    Unsymmetrically substituted allenes (1,2 dienes) are inherently chiral and can be prepared in optically pure form. Nonetheless, to date the allene framework has not been incorporated into ligands for asymmetric catalysis. Since allenes project functionality differently than either tetrahedral carbon or chiral biaryls, they may create complementary chiral environments. This study demonstrates that optically active C2 symmetric allene-containing bisphosphine oxides can catalyze the addition of SiCl4 to meso epoxides with high enantioselectivity. The epoxide-opening likely involves generation of a Lewis acidic, cationic (bisphosphine oxide)SiCl3 complex. The fact that high asymmetric induction is observed suggests that allenes may represent a new platform for the development of ligands and catalysts for asymmetric synthesis. PMID:19722613

  16. Validation of three-dimensional data assimilation and reanalysis of radiation belt electrons

    Science.gov (United States)

    Cervantes-Villa, Juan Sebastian; Shprits, Yuri Y.

    2017-04-01

    Satellite observations are often incomplete and inaccurate and may have only limited spatial coverage. However, through data assimilation they can be blended with information from physics-based models, in order to fill gaps and lead to a better understanding of the underlying dynamical processes. Data assimilation methods have been extensively used to analyze and predict meteorological, oceanographic, and climate processes. With the advent of space-borne observational data and the development of more sophisticated space-physics models, dynamical processes in the Earth's radiation belts can be analyzed and assessed using data assimilation methods. In this study, reanalysis of radiation belt electrons is achieved through data assimilation of Van Allen Probes mission and Geostationary Operational Environmental Satellite with the 3D Versatile Electron Radiation Belt using a split-operator Kalman filter technique. Results are statistically validated for several field models and boundary conditions. Sensitivity of the reanalysis electron flux to available spacecraft data is also assessed.

  17. Mitigation of Space Radiation Effects

    Science.gov (United States)

    Atwell, William

    2012-02-01

    During low earth orbit and deep space missions, humans and spacecraft systems are exposed to high energy particles emanating from basically three sources: geomagnetically-trapped protons and electrons (Van Allen Belts), extremely high energy galactic cosmic radiation (GCR), and solar proton events (SPEs). The particles can have deleterious effects if not properly shielded. For humans, there can be a multitude of harmful effects depending on the degree of exposure. For spacecraft systems, especially electronics, the effects can range from single event upsets (SEUs) to catastrophic effects such as latchup and burnout. In addition, some materials, radio-sensitive experiments, and scientific payloads are subject to harmful effects. To date, other methods have been proposed such as electrostatic and electromagnetic shielding, but these approaches have not proven feasible due to cost, weight, and safety issues. The only method that has merit and has been effective is bulk or parasitic shielding. In this paper, we discuss in detail the sources of the space radiation environment, spacecraft, human, and onboard systems modeling methodologies, transport of these particles through shielding materials, and the calculation of the dose effects. In addition, a review of the space missions to date and a discussion of the space radiation mitigation challenges for lunar and deep space missions such as lunar outposts and human missions to Mars are presented.

  18. THE ALLEN TELESCOPE ARRAY SEARCH FOR ELECTROSTATIC DISCHARGES ON MARS

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, Marin M.; Siemion, Andrew P. V.; Bower, Geoffrey C.; De Pater, Imke [Department of Astronomy and Radio Astronomy Laboratory, University of California, Berkeley, CA (United States); Barott, William C. [Department of Electrical Engineering, Embry-Riddle Aeronautical University, Daytona Beach, FL (United States); Delory, Gregory T.; Werthimer, Dan, E-mail: marinanderson@berkeley.edu [Space Sciences Laboratory, University of California, Berkeley, CA (United States)

    2012-01-01

    The Allen Telescope Array was used to monitor Mars between 2010 March 9 and June 2, over a total of approximately 30 hr, for radio emission indicative of electrostatic discharge. The search was motivated by the report from Ruf et al. of the detection of non-thermal microwave radiation from Mars characterized by peaks in the power spectrum of the kurtosis, or kurtstrum, at 10 Hz, coinciding with a large dust storm event on 2006 June 8. For these observations, we developed a wideband signal processor at the Center for Astronomy Signal Processing and Electronics Research. This 1024 channel spectrometer calculates the accumulated power and power-squared, from which the spectral kurtosis is calculated post-observation. Variations in the kurtosis are indicative of non-Gaussianity in the signal, which can be used to detect variable cosmic signals as well as radio frequency interference (RFI). During the three-month period of observations, dust activity occurred on Mars in the form of small-scale dust storms; however, no signals indicating lightning discharge were detected. Frequent signals in the kurtstrum that contain spectral peaks with an approximate 10 Hz fundamental were seen at both 3.2 and 8.0 GHz, but were the result of narrowband RFI with harmonics spread over a broad frequency range.

  19. Observations of a broad and dynamic region of radiation in geospace

    Science.gov (United States)

    Chen, Jiasheng; Lyu, Ling-Hsiao

    2012-10-01

    The solar wind particles can directly access the high-altitude cusp. They could create large diamagnetic cavities with a size of 6RE (Earth radii) in the latitudinal direction and >10RE in the longitudinal direction at an altitude of 7-8RE, and up to 10.5RE in the depth; they could depress the field from more than 260 nT to near 0 nT. Energetic charged particles with energies from 20 keV up to 15 MeV have been detected there, and their intensities are observed to increase by as much as four orders of magnitude during the diamagnetic cavity crossings. Strong electromagnetic fluctuations are measured there as well. The power spectral density of the magnetic fluctuations inside the cavities shows increases by up to five orders of magnitude at O+ gyro-frequency in comparison to the outer Van Allen radiation belt. The cavity electric fields have an amplitude of up to 350 mV/m, and its perpendicular component varies from -300 to 350 mV/m. The phase space densities of both the He++ and O+ ion species in the diamagnetic cavities could be more than two orders of magnitude higher than that in the outer radiation belt at a given magnetic moment. These in situ observations reveal a broad and dynamic region of radiation centered at the Earth's magnetospheric cusp, which is different from the Van Allen radiation belt centered at the Earth's magnetic equator with relatively stable magnetic field. The region of radiation is observed on both open and closed geomagnetic field lines. It can extend to low latitude to reach L-shell values of 7-12.5, providing a direct particle source for the outer radiation belt/ring current.

  20. Combined Radiation Belt - Plasma Sheet System Modeling

    Science.gov (United States)

    Aseev, Nikita; Shprits, Yuri; Kellerman, Adam; Drozdov, Alexander; Zhu, Hui

    2017-04-01

    Recent years have given rise to numerous mathematical models of the Earth's radiation belt dynamics. Driven by observations at geosynchronous orbit (GEO) where satellites (e.g. GOES and LANL) provide extensive in-situ measurements, radiation belt models usually take into account only diffusion processes in the energetic electron belts (100 keV and greater), leaving aside the dynamics of colder source population (tens of keV). Such models are able to reconstruct the radiation belt state, but they are not capable of predicting the electron dynamics at GEO, where many communication and navigation satellites currently operate. In this work we present combined four-dimensional electron radiation belt - plasma sheet model accounting for adiabatic advective transport, radial diffusion due to interaction with ULF waves, local acceleration of electrons, scattering into the atmosphere, magnetopause shadowing, and adiabatic effects due to contraction and expansion of the magnetic field. The developed model is applicable to energetic, relativistic and ultrarelativistic electrons as well as to source electron population. The model provides spatial particle distribution allowing us to compare and validate the model with multiple satellite measurements at different MLT sectors (e.g. Van Allen Probes, GOES, LANL, THEMIS). The model can be helpful for the prediction of crucial for satellite operators geosynchronous electron fluxes and electron radiation belt dynamics including the heart of the outer belt, slot region and inner belt.

  1. Simultaneous event-specific estimates of transport, loss, and source rates for relativistic outer radiation belt electrons

    Science.gov (United States)

    Schiller, Q.; Tu, W.; Ali, A. F.; Li, X.; Godinez, H. C.; Turner, D. L.; Morley, S. K.; Henderson, M. G.

    2017-03-01

    The most significant unknown regarding relativistic electrons in Earth's outer Van Allen radiation belt is the relative contribution of loss, transport, and acceleration processes within the inner magnetosphere. Detangling each individual process is critical to improve the understanding of radiation belt dynamics, but determining a single component is challenging due to sparse measurements in diverse spatial and temporal regimes. However, there are currently an unprecedented number of spacecraft taking measurements that sample different regions of the inner magnetosphere. With the increasing number of varied observational platforms, system dynamics can begin to be unraveled. In this work, we employ in situ measurements during the 13-14 January 2013 enhancement event to isolate transport, loss, and source dynamics in a one-dimensional radial diffusion model. We then validate the results by comparing them to Van Allen Probes and Time History of Events and Macroscale Interactions during Substorms observations, indicating that the three terms have been accurately and individually quantified for the event. Finally, a direct comparison is performed between the model containing event-specific terms and various models containing terms parameterized by geomagnetic index. Models using a simple 3/Kp loss time scale show deviation from the event-specific model of nearly 2 orders of magnitude within 72 h of the enhancement event. However, models using alternative loss time scales closely resemble the event-specific model.

  2. A Summing Up. Allen Memorial Art Museum Addition, Oberlin, Ohio

    Science.gov (United States)

    Progressive Architecture, 1977

    1977-01-01

    Venturi and Rauch's addition to the Allen Art Museum at Oberlin College is in two separate parts: a loft that houses new facilities for the art department and a gallery for contemporary art. (Author/MLF)

  3. Substituent effects on dynamics at conical intersections: Allene and methyl allenes

    Energy Technology Data Exchange (ETDEWEB)

    Neville, Simon P. [Department of Chemistry, University of Ottawa, 10 Marie Curie, Ottawa, Ontario K1N 6N5 (Canada); Wang, Yanmei [State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071 (China); Boguslavskiy, Andrey E.; Stolow, Albert, E-mail: albert.stolow@nrc-cnrc.gc.ca [Department of Chemistry, University of Ottawa, 10 Marie Curie, Ottawa, Ontario K1N 6N5 (Canada); National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario K1A 0R6 (Canada); Department of Physics, University of Ottawa, 150 Louis Pasteur, Ottawa ON K1N 6N5 (Canada); Schuurman, Michael S., E-mail: michael.schuurman@nrc-cnrc.gc.ca [Department of Chemistry, University of Ottawa, 10 Marie Curie, Ottawa, Ontario K1N 6N5 (Canada); National Research Council of Canada, 100 Sussex Drive, Ottawa, Ontario K1A 0R6 (Canada)

    2016-01-07

    We report a joint experimental and theoretical study on the ultrafast excited state dynamics of allene and a series of its methylated analogues (1,2-butadiene, 1,1-dimethylallene, and tetramethylallene) in order to elucidate the conical intersection mediated dynamics that give rise to ultrafast relaxation to the ground electronic state. We use femtosecond time-resolved photoelectron spectroscopy (TRPES) to probe the coupled electronic-vibrational dynamics following UV excitation at 200 nm (6.2 eV). Ab initio multiple spawning (AIMS) simulations are employed to determine the mechanistic details of two competing dynamical pathways to the ground electronic state. In all molecules, these pathways are found to involve as follows: (i) twisting about the central allenic C–C–C axis followed by pyramidalization at one of the terminal carbon atoms and (ii) bending of allene moiety. Importantly, the AIMS trajectory data were used for ab initio simulations of the TRPES, permitting direct comparison with experiment. For each molecule, the decay of the TRPES signal is characterized by short (30 fs, 52 fs, 23 fs) and long (1.8 ps, 3.5 ps, [306 fs, 18 ps]) time constants for 1,2-butadiene, 1,1-dimethylallene, and tetramethylallene, respectively. However, AIMS simulations show that these time constants are only loosely related to the evolution of electronic character and actually more closely correlate to large amplitude motions on the electronic excited state, modulating the instantaneous vertical ionization potentials. Furthermore, the fully substituted tetramethylallene is observed to undergo qualitatively different dynamics, as displacements involving the relatively massive methyl groups impede direct access to the conical intersections which give rise to the ultrafast relaxation dynamics observed in the other species. These results show that the branching between the “twisting” and “bending” pathways can be modified via the selective methylation of the terminal

  4. Datagebaseerde aspekte van Afrikaanse reduplikasies | van ...

    African Journals Online (AJOL)

    Die doel van hierdie artikel is om aandag te skenk aan twee leemtes in Van Huyssteen (2000), te wete om sy bevindinge te verifieer en te verfyn aan die hand van 'n korpus van geskrewe Afrikaans, asook om die fonologiese pool van die Afrikaanse reduplikasiekonstruksie beter te beskryf. Binne 'n gebruiksgebaseerde ...

  5. Radiations and space flight; Quand les radiations font partie du voyage

    Energy Technology Data Exchange (ETDEWEB)

    Maalouf, M.; Vogin, G.; Foray, N. [Groupe de Radiobiologie, Inserm U836, Institut des Neurosciences, 38 - Grenoble (France); Maalouf [CNES, Dept. des Sciences de la Vie, 75 - Paris (France); Vogin, G. [Laboratoire de Radiobiologie, EA3738, Faculte de Medecine de Lyon Sud, 69- Oullins (France)

    2011-02-15

    A space flight is submitted to 3 main sources of radiation: cosmic radiation (4 protons/cm{sup 2}/s and 10000 times less for the heaviest particles), solar radiation (10{sup 8} protons/cm{sup 2}/s in the solar wind), the Van Allen belt around the earth: the magnetosphere traps particles and at an altitude of 500 km the proton flux can reach 100 protons/cm{sup 2}/s. If we take into account all the spatial missions performed since 1960, we get an average dose of 400 {mu}Gray per day with an average dose rate of 0.28 {mu}Gray/mn. A significant risk of radiation-induced cancer is expected for missions whose duration is over 250 days.The cataract appears to be the most likely non-cancerous health hazard due to the exposition to comic radiation. Its risk appears to have been under-estimated, particularly for doses over 8 mGray. Some studies on astronauts have shown for some a very strong predisposition for radio-induced cancers: during the reparation phase of DNA breaking due to irradiation, multiple new damages are added by the cells themselves that behave abnormally. (A.C.)

  6. Radiation measurements aboard the fourth Gemini flight.

    Science.gov (United States)

    Janni, J F; Schneider, M F

    1967-01-01

    Two special tissue-equivalent ionization chambers and 5 highly sensitive passive dosimetry packages were flown aboard the recent Gemini 4 flight for the purpose of obtaining precise values of instantaneous dose rate, accumulated dose. and shielding effectiveness. This experiment marked the first time that well-defined tissue dose and radiation survey measurements have been carried out in manned spaceflight operations. Since all measurements were accomplished under normal spacecraft environmental conditions, the biological dose resulted primarily from trapped inner Van Allen Belt radiation encountered by the spacecraft in the South Atlantic Anomaly. The experiment determined the particle type, ionizing and penetrating power, and variation with time and position within the Gemini spacecraft. Measured dose rates ranged from 100 mrad/hr for passes penetrating deeply into the South Atlantic Anomaly to less than 0.1 mrad/hr from lower latitude cosmic radiation. The accumulated tissue dose measured by the active ionization chambers, shielded by 0.4 gm/cm2 for the 4-day mission, was 82 mrad. Since the 5 passive dosimetry packages were each located in different positions within the spacecraft, the total mission surface dose measured by these detectors varied from 73 to 27 mrad, depending upon location and shielding. The particles within the spacecraft were recorded in nuclear emulsion, which established that over 90% of the tissue dose was attributable to penetrating protons. This experiment indicates that the radiation environment under shielded conditions at Gemini altitudes was not hazardous.

  7. Roles of hot electrons in generating upper-hybrid waves in the earth's radiation belt

    Science.gov (United States)

    Hwang, J.; Shin, D. K.; Yoon, P. H.; Kurth, W. S.; Larsen, B. A.; Reeves, G. D.; Lee, D. Y.

    2017-06-01

    Electrostatic fluctuations near upper-hybrid frequency, which are sometimes accompanied by multiple-harmonic electron cyclotron frequency bands above and below the upper-hybrid frequency, are common occurrences in the Earth's radiation belt, as revealed through the twin Van Allen Probe spacecrafts. It is customary to use the upper-hybrid emissions for estimating the background electron density, which in turn can be used to determine the plasmapause locations, but the role of hot electrons in generating such fluctuations has not been discussed in detail. The present paper carries out detailed analyses of data from the Waves instrument, which is part of the Electric and Magnetic Field Instrument Suite and Integrated Science suite onboard the Van Allen Probes. Combined with the theoretical calculation, it is shown that the peak intensity associated with the upper-hybrid fluctuations might be predominantly determined by tenuous but hot electrons and that denser cold background electrons do not seem to contribute much to the peak intensity. This finding shows that upper-hybrid fluctuations detected during quiet time are not only useful for the determination of the background cold electron density but also contain information on the ambient hot electrons population as well.

  8. Optimalisering van die omskakeling van matrieksimbole vir ...

    African Journals Online (AJOL)

    Erna Kinsey

    die gevolglike matrieksimboolpunttotaal (MST) aangetref. Die geldig- heid van matriekprestasie as voorspeller van universiteitsprestasie word dan gewoonlik ondersoek deur die MST met die gemiddelde van die persentasiepunte oor die gekose universiteitsvakke in die eerste akademiese semester of jaar te korreleer.

  9. Chorus Wave Modulation of Langmuir Waves in the Radiation Belts

    Science.gov (United States)

    Li, Jinxing; Bortnik, Jacob; An, Xin; Li, Wen; Thorne, Richard M.; Zhou, Meng; Kurth, William S.; Hospodarsky, George B.; Funsten, Herbert O.; Spence, Harlan E.

    2017-12-01

    Using high-resolution waveforms measured by the Van Allen Probes, we report a novel observation in the radiation belts. Namely, we show that multiband, discrete, rising-tone whistler mode chorus emissions exhibit a one-to-one correlation with Langmuir wave bursts. Moreover, the periodic Langmuir wave bursts are generally observed at the phase location where the chorus wave E|| component is oriented opposite to its propagation direction. The electron measurements show a beam in phase space density at the particle velocity that matches the parallel phase velocity of the chorus waves. Based on this evidence, we conclude that the chorus waves accelerate the suprathermal electrons via Landau resonance and generate a localized electron beam in phase space density. Consequently, the Langmuir waves are excited locally and are modulated by the chorus wave phase. This microscale interaction between chorus waves and high-frequency electrostatic waves provides a new insight into the nonlinear wave-particle interaction process.

  10. Nonlinear evolution of oblique whistler waves in radiation belts

    Science.gov (United States)

    Sharma, R. P.; Nandal, P.; Yadav, N.; Sharma, Swati

    2017-02-01

    Magnetic power spectrum and formation of coherent structures have been investigated in the present work applicable to Van Allen radiation belt. The nonlinear interaction of high frequency oblique whistler wave and low frequency magnetosonic wave has been investigated. Simulation was performed of the coupled equation of these two waves. The nonlinear interaction of these waves leads to the formation of the localized structures. These resulting localized structures are of complex nature. The associated magnetic power spectrum has also been studied. Dispersive nonlinear processes account for the high frequency part of the spectrum. The resulting magnetic power spectrum shows a scaling of k^{ - 4.5}. The energy transfer process from injection scales to smaller scales is explained by the results.

  11. The AE9/AP9 Next Generation Radiation Specification Models - Progress Report

    Science.gov (United States)

    O'Brien, Paul; Johnston, William Robert; Ginet, Gregory; Huston, Stuart

    The AE9/AP9 model has now been released to the global satellite design community. Since the release of version 1.0, we have been focused on documenting the model so that it is suitable for consideration as an international standard. We are also working on incorporating new data sources, such as THEMIS, TACSAT-4, and NASA’s Van Allen Probes. Finally, we are scoping out architectural improvements to enable improvements requested by industry: improved stitching between the plasma and radiation models, local time dependence in the plasma model, longitude dependence in the electron radiation model, and solar cycle variation in the low altitude protons. We provide a brief update on the status of the model, plans for the future, and progress on international agreements.

  12. : The AE9/AP9 Next Generation Radiation Specification Models - Progress Report

    Science.gov (United States)

    OBrien, Paul; Johnston, W. Robert; Huston, Stuart; Ginet, Gregory

    2015-04-01

    The AE9/AP9 model has now been released to the global satellite design community. Since the release of version 1.0, we have been focused on documenting the model so that it is suitable for consideration as an international standard. We are also working on incorporating new data sources, such as THEMIS, TACSAT-4, and NASA's Van Allen Probes. Finally, we are scoping out architectural improvements to enable improvements requested by industry: improved stitching between the plasma and radiation models, local time dependence in the plasma model, longitude dependence in the electron radiation model, and solar cycle variation in the low altitude protons. We provide a brief update on the status of the model, plans for the future, and progress on international agreements.

  13. Subcritical Growth of Electron Phase-space Holes in Planetary Radiation Belts

    Science.gov (United States)

    Osmane, Adnane; Turner, Drew L.; Wilson, Lynn B.; Dimmock, Andrew P.; Pulkkinen, Tuija I.

    2017-09-01

    The discovery of long-lived electrostatic coherent structures with large-amplitude electric fields (1≤slant E ≤slant 500 mV/m) by the Van Allen Probes has revealed alternative routes through which planetary radiation belts’ acceleration can take place. Following previous reports showing that small phase-space holes, with qφ /{T}ec≃ {10}-2{--}{10}-3, could result from electron interaction with large-amplitude whistlers, we demonstrate one possible mechanism through which holes can grow nonlinearly (I.e., γ \\propto \\sqrt{φ }) and subcritically as a result of momentum exchange between hot and cold electron populations. Our results provide an explanation for the common occurrence and fast growth of large-amplitude electron phase-space holes in the Earth’s radiation belts.

  14. Very Oblique Whistler Mode Propagation in the Radiation Belts: Effects of Hot Plasma and Landau Damping

    Science.gov (United States)

    Ma, Q.; Artemyev, A. V.; Mourenas, D.; Li, W.; Thorne, R. M.; Kletzing, C. A.; Kurth, W. S.; Hospodarsky, G. B.; Reeves, G. D.; Spence, H. E.; Wygant, J.

    2017-12-01

    Satellite observations of a significant population of very oblique chorus waves in the outer radiation belt have fueled considerable interest in the effects of these waves on energetic electron scattering and acceleration. However, corresponding diffusion rates are extremely sensitive to the refractive index N, controlled by hot plasma effects including Landau damping and wave dispersion modifications by suprathermal (15-100 eV) electrons. A combined investigation of wave and electron distribution characteristics obtained from the Van Allen Probes shows that peculiarities of the measured electron distribution significantly reduce Landau damping, allowing wave propagation with high N ˜ 100-200. Further comparing measured refractive indexes with theoretical estimates incorporating hot plasma corrections to the wave dispersion, we provide the first experimental demonstration that suprathermal electrons indeed control the upper limit of the refractive index of highly oblique whistler mode waves. Such results further support the importance of incorporating very oblique waves into radiation belt models.

  15. Experimental measurements of the radiation hazards associated with manned space flights.

    Science.gov (United States)

    Clark, B C; Adams, D A

    1965-01-01

    Tissue-equivalent ionization chambers of special design have been flown on U.S. satellites to determine dose-rate levels in space. A chamber shielded by 4.7 g/cm2 measured doses from energetic protons in the inner Van Allen belt and bremsstrahlung radiation produced by relativistic electrons from the artificial radiation belt formed in July 1962. In November 1962, the maximum dose-rate in space for this shield was 30 rad/hr. Behind 0.4 g/cm2 shielding, the dose-rate peak was 20000 rad/hr. These doses have been determined to be due to artificial electrons in most regions of space, masking the dose arising from energetic protons.

  16. Science Highlights from the Balloon Array for Radiation belt Electron Losses (BARREL)

    Science.gov (United States)

    Millan, R. M.

    2016-12-01

    In the inner magnetosphere where the plasmasphere, ring current and radiation belts overlap, energy and momentum are exchanged between different plasma populations by plasma waves. Resonant interaction with these waves can lead to rapid loss of radiation belt and ring current electrons to the atmosphere. Over the past four years, more than 50 BARREL balloons have been launched, making observations of energetic ( 20 keV - 10 MeV) electron precipitation in both hemispheres. The combination of BARREL multi-point balloon measurements with measurements from equatorial spacecraft (e.g. Van Allen Probes, LANL, THEMIS, GOES), LEO spacecraft (POES, CSSWE, FIREBIRD, AC-6), and ground-based instruments is providing a unique opportunity to quantify the spatial scale of energetic precipitation and to study the wave-particle interactions that cause precipitation. This presentation will focus on science results from recent BARREL campaigns, shedding light on outstanding questions about energetic electron precipitation.

  17. Effectieve bestrijding van varroa

    OpenAIRE

    Cornelissen, B.; Blacquiere, T.; Steen, van, M.R.

    2010-01-01

    De varroa mijtziekte (Varroa destructor) is de belangrijkste bedreiging van de Europese honingbij. Wintersterfte van honingbijen is in de meeste gevallen toe te schrijven aan deze ziekte. Deze brochure van de WUR biedt informatie over de biologie van varroa, de effecten van varroa op honingbijen en de bestrijding van varroa.

  18. Verwerking van Nederlands fruit

    NARCIS (Netherlands)

    Peppelman, G.; Groot, M.J.

    2002-01-01

    Het doel van dit onderzoek is inzicht te geven in de verwerking van fruit in Nederland, zowel grootschalig als kleinschalig en beoordelen van een aantal cases van kleinschalige verwerkers op hun score op verschillende beleidsthema’s van het ministerie van LNV. Tevens wordt een inschatting gegeven

  19. De planning van ontgrondingen

    NARCIS (Netherlands)

    Ike, Paul

    2000-01-01

    Dit onderzoek is gericht op de afstemming van vraag en aanbod van oppervlaktedelfstoffen. De afstemmingsproblematiek wordt geanalyseerd vanuit een perspectief van planning en besluitvorming. Doel van deze studie is het verkrijgen van nieuwe inzichten om de planning van ontgrondingen op rijksniveau

  20. Radiation environment at LEO orbits: MC simulation and experimental data.

    Science.gov (United States)

    Zanini, Alba; Borla, Oscar; Damasso, Mario; Falzetta, Giuseppe

    The evaluations of the different components of the radiation environment in spacecraft, both in LEO orbits and in deep space is of great importance because the biological effect on humans and the risk for instrumentation strongly depends on the kind of radiation (high or low LET). That is important especially in view of long term manned or unmanned space missions, (mission to Mars, solar system exploration). The study of space radiation field is extremely complex and not completely solved till today. Given the complexity of the radiation field, an accurate dose evaluation should be considered an indispensable part of any space mission. Two simulation codes (MCNPX and GEANT4) have been used to assess the secondary radiation inside FO-TON M3 satellite and ISS. The energy spectra of primary radiation at LEO orbits have been modelled by using various tools (SPENVIS, OMERE, CREME96) considering separately Van Allen protons, the GCR protons and the GCR alpha particles. This data are used as input for the two MC codes and transported inside the spacecraft. The results of two calculation meth-ods have been compared. Moreover some experimental results previously obtained on FOTON M3 satellite by using TLD, Bubble dosimeter and LIULIN detector are considered to check the performances of the two codes. Finally the same experimental device are at present collecting data on the ISS (ASI experiment BIOKIS -nDOSE) and at the end of the mission the results will be compared with the calculation.

  1. Herstructurering Stageprocessen Van Hall Larenstein

    NARCIS (Netherlands)

    Schelvis-Smit, A.A.M.

    2009-01-01

    Verslag van de herstructurering van het stageproces bij het Onderwijsbureau van Hogelschool VanHall Larenstein. Uitgangspunt hierbij was het onderling uitwisselbaar worden van personeel bij het uitvoeren van werkzaamheden met betrekking tot stages.

  2. Stralenbehandeling van 'germinal tumors' van de testis

    NARCIS (Netherlands)

    Keijser, Sijbrand Pieter

    1957-01-01

    Na een kotte inleiding wordt in het eerste hoofdstuk een beknopt overzicht gegeven van de ontwikkeling van de testis bij het embryo. In het tweede hoofdstuk wordt de anatomie van de testis en zijn afvoersvsteem besproken, waarbij speciale aandacht wordt geschonken aan de afvoerende lymphvaten van de

  3. Karakterisering van het "Etimologiewoordeboek van Afrikaans" (EWA)

    African Journals Online (AJOL)

    Zesendertig jaar na Afrikaanse etimologieë van Boshoff en Nienaber verscheen er in 2003 een nieuw etymologisch woordenboek van het Afrikaans: het Etimologiewoordeboek van Afrikaans (EWA). Tussen die twee woordenboeken bestaat een wezenlijk verschil. Het werk van Boshoff en Nienaber is vrijwel alleen ...

  4. De Psychiatrische Ziektegeschiedenis van Vincent van Gogh

    NARCIS (Netherlands)

    Griffioen, R.W.; de Jongh, Franciscus H.C.

    2001-01-01

    Over het ziektebeeld van Vincent van Gogh is veel geschreven. De meeste auteurs baseren de diverse diagnosen op de verschijnselen die hij vertoonde in zijn laatste levensjaren. Van Gogh had echter gedurende een veel groter deel van zijn leven symptomen die het best passen bij een

  5. The role of the convection electric field in filling the slot region between the inner and outer radiation belts

    Science.gov (United States)

    Califf, S.; Li, X.; Zhao, H.; Kellerman, A.; Sarris, T. E.; Jaynes, A.; Malaspina, D. M.

    2017-02-01

    The Van Allen Probes have reported frequent flux enhancements of 100s keV electrons in the slot region, with lower energy electrons exhibiting more dynamic behavior at lower L shells. Also, in situ electric field measurements from the Combined Release and Radiation Effects Satellite, Time History of Events and Macroscale Interactions during Substorms (THEMIS), and the Van Allen Probes have provided evidence for large-scale electric fields at low L shells during active times. We study an event on 19 February 2014 where hundreds of keV electron fluxes were enhanced by orders of magnitude in the slot region and electric fields of 1-2 mV/m were observed below L = 3. Using a 2-D guiding center particle tracer and a simple large-scale convection electric field model, we demonstrate that the measured electric fields can account for energization of electrons up to at least 500 keV in the slot region through inward radial transport.

  6. Civiele toepassingen van defensieonderzoek

    NARCIS (Netherlands)

    Belderbos, C.M.N.

    1987-01-01

    Als een van de oorzaken van de zich verbredende technologiekloof tussen Europa enerzijds en de VS en Japan anderzijds, wordt het tekort schietende commerciele gebruik van militaire research aangemerkt. Zij er voorbeelden te geven van civiele toepassingen van defensieonderzoek? Ja zegt Ir. Belderbos

  7. Effectieve bestrijding van varroa

    NARCIS (Netherlands)

    Cornelissen, B.; Blacquiere, T.; Steen, van der J.J.M.

    2010-01-01

    De varroa mijtziekte (Varroa destructor) is de belangrijkste bedreiging van de Europese honingbij. Wintersterfte van honingbijen is in de meeste gevallen toe te schrijven aan deze ziekte. Deze brochure van de WUR biedt informatie over de biologie van varroa, de effecten van varroa op honingbijen en

  8. De afzetstructuur van pootaardappelen

    NARCIS (Netherlands)

    Baris, D.B.; Graaff, de G.C.

    1982-01-01

    Een beknopt verslag van een onderzoek naar de afzetstructuur van pootaardappelen op grond van een enquete in 1979 onder groothandelaren en in 1980 onder telers. Van de afzet van de 4000 telers is 75% vastgelegd bij 800 groothandelaars, waardoor de prijsvorming in hoge mate is vastgelegd.

  9. DIE SLAG VAN BLOEDRIVIER~

    African Journals Online (AJOL)

    van die betekenis watdie Slag van Bloedriviervir die Suid-Afrikaansemilitere geskiedenis inhou, is Bloedrivier een van die slagvelde in die land wat die volledigste gerekonstrueer is. Voetnote. 1. J. J. Oberholster: Die Historiese Monumente van Suid-Afrika, p. 279. 2. H. J. Hofstede: Geschiedenis van den Oranje-Vrijstaat,.

  10. Reproducing the energy-dependent structure of Earth's electron radiation belts during quiet times

    Science.gov (United States)

    Ripoll, J. F.; Reeves, G. D.; Santolik, O.; Cunningham, G.; Loridan, V.; Denton, M.; Kurth, W. S.; Turner, D. L.; Kletzing, C.; Henderson, M. G.; Ukhorskiy, S.

    2016-12-01

    We present and discuss dynamic simulations of energy-dependent losses in the radiation belt "slot region" and the formation of the two-belt structure for the quiet days after the 1 March storm. The simulations combine radial diffusion with a realistic scattering model, based data-driven spatially and temporally resolved whistler-mode hiss wave observations from the Van Allen Probes satellites. We will describe how the latter is generated from massively parallel computations of pitch angle diffusion at a scale never achieved in the past. The simulations reproduce Van Allen Probes observations for all energies and L shells (2-6) including (a) the strong energy dependence to the radiation belt dynamics (b) an energy-dependent outer boundary to the inner zone that extends to higher L shells at lower energies and (c) an "S-shaped" energy-dependent inner boundary to the outer zone that results from the competition between diffusive radial transport and losses. We find that the characteristic energy-dependent structure of the radiation belts and slot region is dynamic and can be formed gradually in 15 days, although the "S shape" can also be reproduced by assuming equilibrium conditions. But we will show that equilibrium states are usually not reachable as it requires very long times for most energy electrons and L-shells. The highest-energy electrons (E>300 keV) of the inner region of the outer belt (L 4-5) also constantly decay, demonstrating that hiss wave scattering affects the outer belt during times of extended plasmasphere. Through these simulations, we explain the full structure in energy and L shell of the belts and the slot formation by hiss scattering during storm recovery. We show the power and complexity of looking dynamically at the effects over all energies and L shells and the need for using data-driven and event-specific conditions.

  11. Book review of Allen & Bekoff (1997) on Cognitive Ethology

    OpenAIRE

    Dittrich, W.H.

    1998-01-01

    In this review of Allen & Bekoff's Species of Mind (1997), underlying theoretical assumptions of cognitive ethology are examined from a biological and philosophical viewpoint. In particular, the aim of the book to constitute a foundational concept for cognitive ethology is addressed. The ambiguity of theory-of-mind approaches in animal cognition is discussed as a major problem for causal explanations in behavioural biology.

  12. Commentary on Sowcik and Allen: Getting Down to Business

    Science.gov (United States)

    Murphy, Susan Elaine

    2013-01-01

    Sowcik and Allen's paper, "Getting Down to Business: A Look at Leadership Education in Business Schools," identifies a number of compelling issues in improving leadership education in business schools and provides a thorough overview of how these efforts could benefit from the considerations present in the National Leadership Educators…

  13. De behandeling van loodintoxicaties

    NARCIS (Netherlands)

    Spaans E; Vries I de; Dijk A van; Savelkoul TJF; VIC

    1996-01-01

    Regelmatig worden het Nationaal Vergiftigingen Informatie Centrum van het Rijksinstituut voor Volksgezondheid en Milieu en de polikliniek Medische Toxicologie van het Academisch Ziekenhuis Utrecht geconfronteerd met vragen van artsen die te maken hebben met personen met een verhoogde

  14. Collectie Van den Bree

    NARCIS (Netherlands)

    Voerman, Gerrit; van den Bree, R.A.P.; Koole, Ruud

    1988-01-01

    Plaatsingslijst behorende bij het persoonlijke archief van R.A.P. van den Bree, betrekking hebbende op de Evangelische Volkspartij {EVP) (1979-1986), opgesteld door R.A.P. van den Bree en G. Voerman, 1987

  15. Bewaring van knolvenkel

    NARCIS (Netherlands)

    Wijk, van C.A.P.; Ligthart, J.

    1993-01-01

    Ter verlenging van de aanvoerperiode van knolvenkel zijn van 1990 t/m '92 bewaarproeven uitgevoerd. Bewaard is bij normale luchtsamenstelling, een hoge relatieve luchtvochtigheid en lage temperatuur (0 tot +1 graden Celsius)

  16. Tellen en meten, de pijlers onder het weten (interview met Martin Poot, Cindy van Damme en Corina Hinrichs)

    NARCIS (Netherlands)

    Bijnsdorp, R.; Poot, M.C.; Damme, van C.J.G.; Hinrichs, C.S.

    2013-01-01

    Alles wat op en in de zee gebeurt, is de moeite van het weten waard. Maar er is ook een soort kennis die niet allen nice to know is, maar ‘verplicht ‘voor elk land dat aan zee grenst. Kennis om te kunnen beoordelen of economische of maatschappelijke activiteiten schade (kunnen) toebrengen aan het

  17. Monitoring milieuhygienische kwaliteit van bouwstoffen

    NARCIS (Netherlands)

    Wilde PGM de; Peekel AF; Buykx SEJ; LAC

    2002-01-01

    Het doel van dit onderzoek is de beschrijving van de milieuhygienische kwaliteit van bouwstoffen na medio 1998 en de evaluatie van: - de toepasbaarheid van bouwstoffen onder de voorwaarden van het Bouwstoffenbesluit, - de consequenties van de normstelling voor het (her)gebruik van bouwstoffen, -

  18. Ziekte van Lyme : nasleep van een tekenbeet

    NARCIS (Netherlands)

    Broek, P.; Takken, W.

    2012-01-01

    Dit themanummer beschrijft de Ziekte van Lyme en geeft een overzicht over de stand van kennis over deze complexe ziekte in Nederland. De lymeziekte is uniek omdat zij veroorzaakt wordt door een bacterie die een teek als tussengastheer (vector) gebruikt.

  19. die invloed van omgewingsfaktore op speeneienskappe van ...

    African Journals Online (AJOL)

    1967), Lombard (1971) en Mostert (1972). Gestandaardiseerde beramings van koneksiefaktore sal dus vanselfsprekend nie op venkil- lende streke en kuddes van toepassing wees nie. Omdat daar nog groot behoefte bestaan vir meer inligting ...

  20. Een geschiedenis van vleesloos eten

    NARCIS (Netherlands)

    Dagevos, H.

    2009-01-01

    Recensie van de populaire editie van het proefschrift van Dirk-Jan Verdonk: Het dierloze gerecht: een vegetarische geschiedenis in Nederland. Hierin wordt de geschiedenis van het vegetarisme vanaf de tweede helft van de 19e eeuw tot nu beschreven

  1. Effects of ultraviolet-B radiation on phytoplankton - zooplankton interactions = [Effecten van ultraviolet-B straling op interacties tussen fytoplankton en zooplankton

    NARCIS (Netherlands)

    Lange, de H.J.

    1999-01-01

    The decrease in stratospheric ozone concentration has received wide attention because the ozone layer protects the earth from harmful ultraviolet-B radiation (UVB, 280-320 nm). UVB radiation is harmful for organisms, and therefore scientific research into how UVB radiation affects organisms

  2. A world of nuclear and radiation literature. Database INIS exists 25 year; Een wereld van nucleaire en stralingsliteratuur. Database INIS bestaat 25 jaar

    Energy Technology Data Exchange (ETDEWEB)

    Verkroost, H. [Netherlands Energy Research Foundation ECN, Petten (Netherlands). Unit ECN Policy Studies

    1995-09-01

    On the occasion of the 25th birthday of the database INIS a brief overview is given of the contents of INIS, its products and services, and the future of INIS. For the readers of this magazine an indication is given of the literature that is available in INIS in the subject categories for external radiation, internal radiation, radiation protection and dosimetry. 1 tab.

  3. Space Radiation Analysis for the Mark III Spacesuit

    Science.gov (United States)

    Atwell, Bill; Boeder, Paul; Ross, Amy

    2013-01-01

    NASA has continued the development of space systems by applying and integrating improved technologies that include safety issues, lightweight materials, and electronics. One such area is extravehicular (EVA) spacesuit development with the most recent Mark III spacesuit. In this paper the Mark III spacesuit is discussed in detail that includes the various components that comprise the spacesuit, materials and their chemical composition that make up the spacesuit, and a discussion of the 3-D CAD model of the Mark III spacesuit. In addition, the male (CAM) and female (CAF) computerized anatomical models are also discussed in detail. We combined the spacesuit and the human models, that is, we developed a method of incorporating the human models in the Mark III spacesuit and performed a ray-tracing technique to determine the space radiation shielding distributions for all of the critical body organs. These body organ shielding distributions include the BFO (Blood-Forming Organs), skin, eye, lungs, stomach, and colon, to name a few, for both the male and female. Using models of the trapped (Van Allen) proton and electron environments, radiation exposures were computed for a typical low earth orbit (LEO) EVA mission scenario including the geostationary (GEO) high electron environment. A radiation exposure assessment of these mission scenarios is made to determine whether or not the crew radiation exposure limits are satisfied, and if not, the additional shielding material that would be required to satisfy the crew limits.

  4. Review of GEM Radiation Belt Dropout and Buildup Challenges

    Science.gov (United States)

    Tu, Weichao; Li, Wen; Morley, Steve; Albert, Jay

    2017-04-01

    In Summer 2015 the US NSF GEM (Geospace Environment Modeling) focus group named "Quantitative Assessment of Radiation Belt Modeling" started the "RB dropout" and "RB buildup" challenges, focused on quantitative modeling of the radiation belt buildups and dropouts. This is a community effort which includes selecting challenge events, gathering model inputs that are required to model the radiation belt dynamics during these events (e.g., various magnetospheric waves, plasmapause and density models, electron phase space density data), simulating the challenge events using different types of radiation belt models, and validating the model results by comparison to in situ observations of radiation belt electrons (from Van Allen Probes, THEMIS, GOES, LANL/GEO, etc). The goal is to quantitatively assess the relative importance of various acceleration, transport, and loss processes in the observed radiation belt dropouts and buildups. Since 2015, the community has selected four "challenge" events under four different categories: "storm-time enhancements", "non-storm enhancements", "storm-time dropouts", and "non-storm dropouts". Model inputs and data for each selected event have been coordinated and shared within the community to establish a common basis for simulations and testing. Modelers within and outside US with different types of radiation belt models (diffusion-type, diffusion-convection-type, test particle codes, etc.) have participated in our challenge and shared their simulation results and comparison with spacecraft measurements. Significant progress has been made in quantitative modeling of the radiation belt buildups and dropouts as well as accessing the modeling with new measures of model performance. In this presentation, I will review the activities from our "RB dropout" and "RB buildup" challenges and the progresses achieved in understanding radiation belt physics and improving model validation and verification.

  5. Teologiese idiome van gister en van vandag

    African Journals Online (AJOL)

    eksponente van respektiewelik spesifieke paradigmas. Die term 'paradigma' verwys na die totaliteit van denke, persepsies en waardes wat lei tot 'n ..... werklikheid gehad het, beskryf aan die hand van Thomas Kuhn se paradigmateorie. Martin (1987:372, 376, 377) verwys na Capra saam met ander geleerdes wat (baie.

  6. Loss of the relativistic and ultra-relativistic radiation belt electrons

    Science.gov (United States)

    Shprits, Yuri; Drozdov, Alexander; Kellerman, Adam; Usanova, Maria; Aseev, Nikita; Spasovevich, Maria

    2017-04-01

    Recent observations and modeling provided significant improvements in our understanding of the energization mechanisms for the electrons in the radiation belts. However, loss processes remain poorly understood. In this study we present analysis of the evolution of electron radial profiles of fluxes, pitch angle and energy distributions. Our modeling and observational results show that different loss mechanisms are operational at different energies. Global simulations at all energies, radial distances, and pitch angels are compared to Van Allen Probes observations of electron fluxes. VERB 3D model including various waves is capable of reproducing the dynamics of pitch angle distributions and energy spectra, demonstrating which loss mechanisms dominate at different energies. Analysis of the profiles of phase space density provides additional confirmation for our conclusion and presents a novel technique that identifies the region of intense local loss due to EMIC wave scattering.

  7. Thermal electron acceleration by localized bursts of electric field in the radiation belts

    Science.gov (United States)

    Artemyev, A. V.; Agapitov, O. V.; Mozer, F.; Krasnoselskikh, V.

    2014-08-01

    In this paper we investigate the resonant interaction of thermal ˜10-100 eV electrons with a burst of electrostatic field that results in electron acceleration to kilovolt energies. This single burst contains a large parallel electric field of one sign and a much smaller, longer-lasting parallel field of the opposite sign. The Van Allen Probe spacecraft often observes clusters of spatially localized bursts in the Earth's outer radiation belts. These structures propagate mostly away from the geomagnetic equator and share properties of soliton-like nonlinear electron acoustic waves: a velocity of propagation is about the thermal velocity of cold electrons (˜3000-10,000 km/s), and a spatial scale of electric field localization along the field lines is about the Debye radius of hot electrons (˜5-30 km). We model the nonlinear resonant interaction of these electric field structures and cold background electrons.

  8. Space Radiation Effect on Si Solar Cells

    Directory of Open Access Journals (Sweden)

    Jae-Jin Lee

    2008-12-01

    Full Text Available High energy charged particles are trapped by geomagnetic field in the region named Van Allen Belt. These particles can move to low altitude along magnetic field and threaten even low altitude spacecraft. Space Radiation can cause equipment failures and on occasions can even destroy operations of satellites in orbit. Sun sensors aboard Science and Technology Satellite (STSAT-1 was designed to detect sun light with silicon solar cells which performance was degraded during satellite operation. In this study, we try to identify which particle contribute to the solar cell degradation with ground based radiation facilities. We measured the short circuit current after bombarding electrons and protons on the solar cells same as STSAT-1 sun sensors. Also we estimated particle flux on the STSAT-1 orbit with analyzing NOAA POES particle data. Our result clearly shows STSAT-1 solar cell degradation was caused by energetic protons which energy is about 700 keV to 1.5 MeV. Our result can be applied to estimate solar cell conditions of other satellites.

  9. Metaalcomplexen van enige geneeesmiddelen; een methode ter bepaling van samenstelling en stabiliteit van metaalcomplexen

    NARCIS (Netherlands)

    Doornbos, Durk Antonius

    1965-01-01

    SAMENVATTING Dit proefschrift is gewijd aan de ontwikkeling van een nauwkeurige potemiometrische methode ter bepaling van stabiliteitsconstamen van protoncomplexen en metaalcomplexen van enige fysiologisch voorkomende metalen met organische liganden en de toepassing van deze methode op enkele

  10. Economische gevolgen van ontwapening

    NARCIS (Netherlands)

    Duisenberg, Willem Frederik

    1965-01-01

    Samenvatting van de gehele studie 4.1. Economie en ontwapening Ontwapening betekent in deze studie de algehele, snelle afschaffing van alle militaire maatregelen in aIle landen. Het negeren van de politieke waarschijnlijkheden die veeleer wijzen op een zeer geleidelijke afschaffing van slechts

  11. Verbetering van strovertering

    NARCIS (Netherlands)

    Spits, H.G.

    2010-01-01

    Stoppelresten en stro van tarwe kunnen een bron voor infectie door Septoria, DTR en (aar)fusarium zijn. In het kader van de beheersing van deze ziekten kan het belangrijk zijn om de gewasresten zo te bewerken dat ze als ziektebron geminimaliseerd worden. Doel van dit onderzoek is om een effectief en

  12. Nitraatinname van de Nederlandse bevolking op basis van de voedselconsumptiepeiling

    NARCIS (Netherlands)

    Loon, van A.J.M.; Klaveren, van J.D.; Herstel, H.

    1990-01-01

    Om een beeld te krijgen van de nitraatbelasting van de Nederlandse bevolking is door het RIKILT, op verzoek van de Directie Voedings- en Kwaliteitsaangelegenheden van het Ministerie van Landbouw, Natuurbeheer en Visserij, de nitraatinname van de consument berekend. Daarbij is gebruik gemaakt van

  13. Performing Allen's test in immobile hand: The Esmarch bandage method

    Directory of Open Access Journals (Sweden)

    Nebil Yesiloglu

    2015-12-01

    Full Text Available In this study, an alternative method of assessing hand vascular flow using a modification of Allen's test is presented. This technique may be helpful for patients who have immobile hands due to severe trauma, patients scheduled for free tissue transfer reconstruction, patients under general anesthesia in intensive care units that require serial arterial blood gas analyses, and emergency coronary by-pass candidates who decided to receive radial arterial grafts. [Hand Microsurg 2015; 4(3.000: 83-85

  14. Secondary bifurcation for a nonlocal Allen-Cahn equation

    Science.gov (United States)

    Kuto, Kousuke; Mori, Tatsuki; Tsujikawa, Tohru; Yotsutani, Shoji

    2017-09-01

    This paper studies the Neumann problem of a nonlocal Allen-Cahn equation in an interval. A main result finds a symmetry breaking (secondary) bifurcation point on the bifurcation curve of solutions with odd-symmetry. Our proof is based on a level set analysis for the associated integral map. A method using the complete elliptic integrals proves the uniqueness of secondary bifurcation point. We also show some numerical simulations concerning the global bifurcation structure.

  15. Estimates of radiation doses in space on the basis of current data.

    Science.gov (United States)

    Foelsche, T

    1963-01-01

    A gross survey of data on Van Allen belt radiations, galactic cosmic radiation, and solar cosmic radiation is presented. On the basis of these data that are, in part, fragmentary and uncertain, upper and lower limits of rad doses under different amounts of mass shielding are estimated. The estimates are preliminary especially in the cases of chance encounter with solar flare protons. Generally, the relative biological effectiveness of the high energetic space radiations and their secondaries appear insufficiently known to give detailed biological or rem doses. The overall ionization dosage of the low level galactic cosmic radiation in free space is estimated to be even in solar minimum years equivalent to less than 50 rem/year or 1 rem/week. Mass shielding up to 80 g/cm2 would not reduce the ionization dosage but would shield against heavy primaries and heavy ionizing secondaries, thus reducing the biological dose. The flux of energetic protons in the maximum intensity zone of the inner Van Allen belt is by about four orders of magnitude higher, their energy and penetration power, of course, lower. A shield of 25 g/cm2 would reduce the dose rate from 20 rad/hour under 2 g/cm2 to 5 rad/hour. These proton dose rates and also the electron and X-radiation dose rates under some g/cm2 shielding of low z-number material will not constitute a radiation hazard for flights straight through the inner and outer belt in about two hours. Staying within the maximum of the inner belt for two days would, however, lead even within 25 g/cm2 depth of outer shield and body itself to a dose of 200 rad which is on the permissible limit. Extreme solar cosmic ray events or proton showers of high intensity and a duration of days occurred with a frequency of 1-4 per year during the last highly active cycle. For the penetrating, most intense high energy event of February 23, 1956, the dose within 25 g/cm2 is estimated to have been in the order of 50 rad. In most cases the dose decreased more

  16. Obituary: John Allen Eddy (1931-2009)

    Science.gov (United States)

    Gingerich, Owen

    2011-12-01

    , "This Mercury is Hot! Red Shift, Black Body, and a Perfect Radiator." Ironically, within a few years he was laid off from his HAO position as a result of budget cuts at its parent organization, the National Center for Atmospheric Research (NCAR). In an interview a quarter of a century later Eddy remarked, "I found out how hard it is for a person with a Ph.D. to get another job at that time, and often wished I didn't have one, for I was often told, true or not, that I was overqualified for the few jobs that turned up." Eddy found a temporary job writing a book for NASA as part of a series on the Skylab spacecraft; the book, The New Sun, was published in 1979. Again, working on his own time, he revived an earlier finding, namely, that between 1645 and 1715 the sun was almost devoid of spots, and he greatly extended the previous work of Gustav Spörer and Walter Maunder by showing during that period a dearth of aurorae and atmospheric carbon-14, a diminution of the solar corona during eclipses, and probably a correlation with cooling of the earth. For onomatopoiec reasons, the rhythm of the m's, Eddy chose the title "the Maunder Minimum" for the phenomenon, and for his unusually long cover story in the 18 June 1976 issue of Science. The paper was well received, and for a while Eddy was an invited speaker fifty times a year. In 1977, Eddy scored yet again, with his third cover story in Science, a jointly authored paper on solar rotation in the early 17th century. In 1977-78 Eddy had a fellowship at the Harvard-Smithsonian Center for Astrophysics in Cambridge, and during that time Ken Brecher and I had a series of conversations with Jack in which we worked out a proposal for a historical astronomy division within the AAS; since I had just been an AAS Councilor, I negotiated with the Society for its actualization, and Eddy became the first HAD president, in 1981-83. He introduced the logo, Dürer's ancient astronomer, and at the end of his term, the plaque with the motto "Ich

  17. Effect of microwave radiation on seed viability, survival of Aspergillus niger van Tieghem and oil quality of oilseeds crops canola, soybean and safflower

    Directory of Open Access Journals (Sweden)

    Ahad MOTALLEBI

    2016-04-01

    Full Text Available The effect of microwave's radiation on seed viability of three different oilseed crops, spores of Aspergillus niger and quality of extracted oil from treated seeds over various exposure times was evaluated. The seeds were exposed to 2450 MHz. at five different power levels of 0, 100, 200, 400, 600 and 800 W for two exposure times of three and five minutes. At a given time, a direct negative relationship between seed viability and microwave's radiation power level was detected. Substantial variation in the lethality of tested seeds to microwave's power levels was apparent in the fiducial limits of the estimated LD50 values in probit analysis approach. A similar trend of A. niger spores’ susceptibility to microwave radiation was detected. The microwaves' radiation and exposure time did not impact one another and a significant interaction was not detected. Short term fungal infection did not cause substantial quantitative and qualitative damage to the oilseeds. The oil quality was generally unaffected by microwave radiation and fungal infestation for tested oilseeds. Moreover, microwave radiation decreased seed germination percentage and vigor index. The microwave radiation could provide an effective and friendly environmental treatment technique for improving the dietary consumption of the oil in any seed disinfestation program.

  18. De klinische betekenis van de serumconcentraties van isonicotinezuurhydrazide en streptomycine

    NARCIS (Netherlands)

    Graaff, J.L. de

    1965-01-01

    SAMENVATTING EN CONCLUSIES In dit proefschrift worden de resultaten beschreven van een onderzoek naar de invloed van de serumconcentraties van isonicotine- zuurhydrazide (INH) op de therapeutische resultaten bij patienten met longtuberculose. Ook de serumconcentraties van streptomycine (SM) zijn het

  19. Helium, Oxygen, Proton, and Electron (HOPE) Mass Spectrometer for the Radiation Belt Storm Probes Mission

    Science.gov (United States)

    Funsten, H. O.; Skoug, R. M.; Guthrie, A. A.; MacDonald, E. A.; Baldonado, J. R.; Harper, R. W.; Henderson, K. C.; Kihara, K. H.; Lake, J. E.; Larsen, B. A.; Puckett, A. D.; Vigil, V. J.; Friedel, R. H.; Henderson, M. G.; Niehof, J. T.; Reeves, G. D.; Thomsen, M. F.; Hanley, J. J.; George, D. E.; Jahn, J.-M.; Cortinas, S.; De Los Santos, A.; Dunn, G.; Edlund, E.; Ferris, M.; Freeman, M.; Maple, M.; Nunez, C.; Taylor, T.; Toczynski, W.; Urdiales, C.; Spence, H. E.; Cravens, J. A.; Suther, L. L.; Chen, J.

    2013-11-01

    The HOPE mass spectrometer of the Radiation Belt Storm Probes (RBSP) mission (renamed the Van Allen Probes) is designed to measure the in situ plasma ion and electron fluxes over 4 π sr at each RBSP spacecraft within the terrestrial radiation belts. The scientific goal is to understand the underlying physical processes that govern the radiation belt structure and dynamics. Spectral measurements for both ions and electrons are acquired over 1 eV to 50 keV in 36 log-spaced steps at an energy resolution Δ E FWHM/ E≈15 %. The dominant ion species (H+, He+, and O+) of the magnetosphere are identified using foil-based time-of-flight (TOF) mass spectrometry with channel electron multiplier (CEM) detectors. Angular measurements are derived using five polar pixels coplanar with the spacecraft spin axis, and up to 16 azimuthal bins are acquired for each polar pixel over time as the spacecraft spins. Ion and electron measurements are acquired on alternate spacecraft spins. HOPE incorporates several new methods to minimize and monitor the background induced by penetrating particles in the harsh environment of the radiation belts. The absolute efficiencies of detection are continuously monitored, enabling precise, quantitative measurements of electron and ion fluxes and ion species abundances throughout the mission. We describe the engineering approaches for plasma measurements in the radiation belts and present summaries of HOPE measurement strategy and performance.

  20. Comparison of lighting activity and inner radiation belt particle fluxes perturbations

    Science.gov (United States)

    Martinez Calderon, C.; Bortnik, J.; Li, W.; Spence, H. E.; Rodger, C. J.

    2016-12-01

    Lightning discharges are known to inject whistlers into the inner magnetosphere over a wide range of latitudes around their source. When a discharge occurs, it radiates electromagnetic energy, some of which propagates in the whistler-mode wave through the ionospheric plasma travelling away from the Earth. Previous studies have discussed the effects of whistler-induced electron precipitation and radiation belt losses associated with lightning but there has been little research on the long term effects of these precipitation on the inner radiation belts [Rodger et al. (2004), Clilverd et al. (2004)].Here, we use data from the World Wide Lightning Location Network (WWLLN), which has continuously monitored global lightning since 2004, to examine one year of lightning data and locate the L-shells with high lighting activity. We use Van Allen Probes' Energetic Particle, Composition, and Thermal Plasma Suite (ECT) from both satellites (RBSP-A/B) to measure electron fluxes in the inner radiation belt at the L-shells of interest. We compare these fluxes to a globally-integrated count of lightning strikes and investigate the relationship between global lightning occurrence and RBSP electron fluxes. We examine several factors, such as different energy ranges, timescales ranging from a few weeks to the entire year and seasonal changes in order to quantify the loss process driven by lightning in the inner radiation belts.

  1. De mechanisering van het wereldbeeld

    NARCIS (Netherlands)

    Dijksterhuis, Eduard J.

    2006-01-01

    De mechanisering van het wereldbeeld is het standaardwerk van Dijksterhuis waarin hij op glasheldere wijze de ontwikkeling van het wetenschappelijk denken analyseert - van de Grieke natuurfilosofen tot de wijsgeren op wier denkbeelden de moderne natuurwetenschappen steunen: Huygens, Descartes,

  2. Exergetische duurzaamheidsanalyse van zinkrecyclageprocessen

    OpenAIRE

    Klaasen, Bart

    2008-01-01

    Eindwerk ingediend ter verkrijging van de graad van Burgerlijk Materiaalkundig Ingenieur (Katholieke Universiteit Leuven, 2008) Promotoren: Prof. dr. ir. B. BLANPAIN (Katholieke Universiteit Leuven), Prof. dr. ir. P. WOLLANTS (Katholieke Universiteit Leuven) en Prof. dr. ir. J. DEWULF (Universiteit Gent)

  3. OM LYNING VAN DIEREPRODUKSIESTRATEGTEd

    African Journals Online (AJOL)

    , Suidoos-Transvaal en die Suidelike kusstreek met 5 miljoen GVE verhoog word deur die introduksie van slegs peulgewasse. Theron en Harwin (1976) bespreek die verskillende teg- nieke van radikale veldverbetering. Hulle vind dat. 'n.

  4. Baanbrekende verpakkingsconcepten van karton

    NARCIS (Netherlands)

    Reuvers, M.; Wienk, I.

    2005-01-01

    Binnen 35 onderzoekspartners in 13 EU-lidstaten loopt het grootste onderzoek naar duurzame verpakkingen van hernieuwbare grondstoffen (Sustainpack) ooit. Het gaat hierbij voornamelijk om verpakkingen van papier, karton en biopolymeren uit hout- en plantenvezels. Uitleg over de deelprojecten met

  5. De teelt van hazelnoten

    NARCIS (Netherlands)

    Wertheim, S.J.; Goedegebure, J.

    1988-01-01

    Teelthandleiding van hazelnoten en lambertsnoten met de onderdelen: soorten; naamgeving; van bloem tot vrucht; klimaat en standplaats; grond; rassen; vermeerdering; planten; plantafstanden en -systemen; snoei en boomvormen; bemesting; gebreksziekten; bodembehandeling; ziekten en plagen; oogst en

  6. Die metodiek van kultuurhulpbronbestuur (KHB) | Van Vollenhoven ...

    African Journals Online (AJOL)

    Die metodiek van kultuurhulpbronbestuur (KHB). Anton C Van Vollenhoven. Abstract. A Cultural Resources Management (CRM) survey may consist of three phases. The phase 1 investigation aims at getting an overview of cultural resources in a given area. A phase 2 investigation aims at determining the impact of ...

  7. Verlagen van de pottemperatuur van boomkwekerijgewassen

    NARCIS (Netherlands)

    Hop, M.E.C.M.

    2008-01-01

    Om een goede plantengroei mogelijk te maken, moeten alle omstandigheden toerijkend zijn voor de plant. Bij de teelt van planten in pot staan de potten vaak op een teeltvloer, wat geen natuurlijke situatie is voor de plant. De temperatuur van de vollegrond, waar de plant normaal gesproken in staat,

  8. Collisional-Radiative Modeling In Flow Simulations

    Science.gov (United States)

    2008-09-08

    model validation of shock layer radiation in air. In AIAA, pages AIAA 2008–1246, Reno, Nevada. [7] Bose, D., Wright, M., Bogdanoff, D., Raiche , G., and...220. [8] Bose, D., Wright, M. J., Bogdanoff, D. W., Raiche , G. A., and Allen, G. A. (2006b). Mod- eling and experimental assessement of cn radiation

  9. Ecologische kenmerken van weidevogeljongen en de invloed van beheer op overleving. Kennisoverzicht en effectiviteit van maatregelen

    NARCIS (Netherlands)

    Oosterveld, E.B.; Kleijn, D.; Schekkerman, H.

    2008-01-01

    Rapport over de effectiviteit van beheersmaatregelen voor overleving van primaire weidevogelkuikens in graslanden, op basis van wetenschappelijke en niet-wetenschappelijke literatuur. Per sprake komen: Ecoprofielen weidevogeljongen van: Kievit (Vanellus vanellus); Grutto (Limosa limosa); Tureluur

  10. Prognose van de metaalgehalten in de landbodem onder invloed van het verspreiden van baggerspecie

    NARCIS (Netherlands)

    Dijk S van; Kramer PRG; Beurskens JEM; LWD; Rijkswaterstaat - directie Limburg; Waterschap De Maaskant

    1998-01-01

    Deze rapportage bevat de resultaten van een modelleringsproject. Er worden beelden geschetst van de kwaliteitsontwikkeling van de landbodem met betrekking tot de vier metalen cadmium, koper, lood en zink bij verspreiding van baggerspecie. Het model beschrijft een vereenvoudigde en gemiddelde

  11. DOSIS & DOSIS 3D: radiation measurements with the DOSTEL instruments onboard the Columbus Laboratory of the ISS in the years 2009–2016

    Directory of Open Access Journals (Sweden)

    Berger Thomas

    2017-01-01

    Full Text Available The natural radiation environment in Low Earth Orbit (LEO differs significantly in composition and energy from that found on Earth. The space radiation field consists of high energetic protons and heavier ions from Galactic Cosmic Radiation (GCR, as well as of protons and electrons trapped in the Earth’s radiation belts (Van Allen belts. Protons and some heavier particles ejected in occasional Solar Particle Events (SPEs might in addition contribute to the radiation exposure in LEO. All sources of radiation are modulated by the solar cycle. During solar maximum conditions SPEs occur more frequently with higher particle intensities. Since the radiation exposure in LEO exceeds exposure limits for radiation workers on Earth, the radiation exposure in space has been recognized as a main health concern for humans in space missions from the beginning of the space age on. Monitoring of the radiation environment is therefore an inevitable task in human spaceflight. Since mission profiles are always different and each spacecraft provides different shielding distributions, modifying the radiation environment measurements needs to be done for each mission. The experiments “Dose Distribution within the ISS (DOSIS” (2009–2011 and “Dose Distribution within the ISS 3D (DOSIS 3D” (2012–onwards onboard the Columbus Laboratory of the International Space Station (ISS use a detector suite consisting of two silicon detector telescopes (DOSimetry TELescope = DOSTEL and passive radiation detector packages (PDP and are designed for the determination of the temporal and spatial variation of the radiation environment. With the DOSTEL instruments’ changes of the radiation composition and the related exposure levels in dependence of the solar cycle, the altitude of the ISS and the influence of attitude changes of the ISS during Space Shuttle dockings inside the Columbus Laboratory have been monitored. The absorbed doses measured at the end of May 2016

  12. DOSIS & DOSIS 3D: radiation measurements with the DOSTEL instruments onboard the Columbus Laboratory of the ISS in the years 2009-2016

    Science.gov (United States)

    Berger, Thomas; Burmeister, Sönke; Matthiä, Daniel; Przybyla, Bartos; Reitz, Günther; Bilski, Pawel; Hajek, Michael; Sihver, Lembit; Szabo, Julianna; Ambrozova, Iva; Vanhavere, Filip; Gaza, Ramona; Semones, Edward; Yukihara, Eduardo G.; Benton, Eric R.; Uchihori, Yukio; Kodaira, Satoshi; Kitamura, Hisashi; Boehme, Matthias

    2017-03-01

    The natural radiation environment in Low Earth Orbit (LEO) differs significantly in composition and energy from that found on Earth. The space radiation field consists of high energetic protons and heavier ions from Galactic Cosmic Radiation (GCR), as well as of protons and electrons trapped in the Earth's radiation belts (Van Allen belts). Protons and some heavier particles ejected in occasional Solar Particle Events (SPEs) might in addition contribute to the radiation exposure in LEO. All sources of radiation are modulated by the solar cycle. During solar maximum conditions SPEs occur more frequently with higher particle intensities. Since the radiation exposure in LEO exceeds exposure limits for radiation workers on Earth, the radiation exposure in space has been recognized as a main health concern for humans in space missions from the beginning of the space age on. Monitoring of the radiation environment is therefore an inevitable task in human spaceflight. Since mission profiles are always different and each spacecraft provides different shielding distributions, modifying the radiation environment measurements needs to be done for each mission. The experiments "Dose Distribution within the ISS (DOSIS)" (2009-2011) and "Dose Distribution within the ISS 3D (DOSIS 3D)" (2012-onwards) onboard the Columbus Laboratory of the International Space Station (ISS) use a detector suite consisting of two silicon detector telescopes (DOSimetry TELescope = DOSTEL) and passive radiation detector packages (PDP) and are designed for the determination of the temporal and spatial variation of the radiation environment. With the DOSTEL instruments' changes of the radiation composition and the related exposure levels in dependence of the solar cycle, the altitude of the ISS and the influence of attitude changes of the ISS during Space Shuttle dockings inside the Columbus Laboratory have been monitored. The absorbed doses measured at the end of May 2016 reached up to 286

  13. Certificering van biologische restaurants

    NARCIS (Netherlands)

    Soethoudt, J.M.

    2006-01-01

    In Nederland zijn meer dan 100 restaurants, die zichzelf als biologisch restaurant presenteren. Echter, de betekenis van 'biologisch restaurant' is niet gedefinieerd, zodat de consument niet weet waar hij op kan rekenen. Het idee, ontstaan bij Eric van Veluwen van Kasteel Rhederoord, tot verkenning

  14. DIE OPTIMUM INSLUITINGSPEIL VAN ...

    African Journals Online (AJOL)

    Aan elkeen is een van die 35 diete ewekansig toegese. Elke vark het ad lib toegang gehad tot die dieet vanaf 8 weke ouderdom tot op 'n lewende massa van ongeveer 50 kg. Die varke is afsonderlik in hokkies van ongeveer 1,5 m X 1 m, toegerus met selfvoerders en drinktepels, aangehou. Voerinname en lewende massa.

  15. van der Waals

    Indian Academy of Sciences (India)

    The title of his thesis was Over de Continuïteit van den Gas- en. Vloeistoftoestand (On the continuity of the gas and liquid state). It is not surprising that van der. Waals' thesis has become a classic in physics literature though he lacked expertise in classical languages. In his thesis, van der Waals introduced the equation of ...

  16. Benaderingen van over

    NARCIS (Netherlands)

    Boer, M.G. de

    2010-01-01

    SAMENVATTING In dit hoofdstuk wordt de relatie tussen de betekenissen van het Nederlandse voorzetsel over en een aantal corpora bestudeerd. Het hoofdstuk begint met een analyse van de voorbeelden uit Uit het leven van Dik Trom (1891); daarna wordt de woordenboekinformatie behandeld en vergeleken

  17. Het telefoonnummer van God

    NARCIS (Netherlands)

    Jansen, J.J.G.

    2004-01-01

    Er zijn duizenden moslims die twijfelen. Die er aan twijfelen of de verschrikkingen van de Hel wel echt bestaan. Die niet zeker weten of de Koran wel precies het letterlijke woord van God is. Die zich afvragen op de profeet van de islam, Mohammed (570-632), nog wel een goed voorbeeld vormt voor de

  18. Chroniqueur van het kwaad

    NARCIS (Netherlands)

    Melching, W.

    2010-01-01

    De dagboeken van Joseph Goebbels vormen een unieke bron over het Derde Rijk. Hitlers minister van Propaganda beschrijft daarin het reilen en zeilen van de nazitop. Uit Goebbels’ aantekeningen blijkt hoezeer de nazileiders elkaar wantrouwden en tegen beter weten in doorvochten. Dit voorjaar

  19. Van hamsterburcht tot rattenhol

    NARCIS (Netherlands)

    Haye, la M.J.J.

    2006-01-01

    Het waarnemen van een hamster (Cricetus cricetus) is erg lastig, omdat de schuwe dieren voornamelijk voorkomen op onoverzichtelijke plekken. Daarom wordt vaak gezocht naar hamsterburchten. Bij graanakkers is dat mogelijk direct na de oogst van het gewas. Maar ook het herkennen van een hamsterburcht

  20. Die Hermeneutiek van Calvyn

    Directory of Open Access Journals (Sweden)

    L. Floor

    1980-06-01

    Full Text Available Wanneer ons Calvyn bestudeer dan is dit nie alleen belangrik om te luister na wat Calvyn sê nie, ons moet ook daarop let hoe hy die dinge sê. By die vak hermeneutiek is ons geneig om te spreek van ’n hermeneutiese metode. Daar word selfs gepraat van die tegniek van die eksegese.

  1. Investigating Time and Spectral Dependence in Neutron Radiation Environments for Semiconductor Damage Studies

    Science.gov (United States)

    2014-09-18

    satellite. Charged particles from the Earth’s Van Allen belt , gamma photons and protons from the sun, and exotic cosmic particles from space are a constant...a region of the world where the Earth’s magnetic field and, thus, the Van Allen belts dip to less than 200 km from the surface [40]. For fiscal and...the end of their track, the device being tested can be probed for sensitivity in different areas. However, a disadvantage is that, because the

  2. Generation of High Power 1.54 Micrometers Radiation by Stimulated Raman Scattering in Methane (Opwekking van Hoogvermogen 1.54 Micrometers Straling m.b. v. Gestimuleerde Raman Verstrooiing in Methaan)

    Science.gov (United States)

    1990-08-01

    diafragma van 2 mm de puls single mode (TEMoo), de divergentie 0.5 mrad. en de pulsenergie 30 mW. Bij een diafragma van 5 mm is de puls multi-mode, de...metingen met een diafragma van 2 mm en een pulsenergie van 18 mJ en TNO r~apport Pagina 29 de 150 wmm lens (zie, tabel 8 en fig. 20) nain bet rendement...met het laser diafragma 4 - 5 mm) maximaal is, terwijl bij de sferische lens (zie tabel 3) het hoogste rendement bij 70 mJ werd gehaald. De toename van

  3. Upper limit on the inner radiation belt MeV electron intensity

    Science.gov (United States)

    Li, X; Selesnick, RS; Baker, DN; Jaynes, AN; Kanekal, SG; Schiller, Q; Blum, L; Fennell, J; Blake, JB

    2015-01-01

    No instruments in the inner radiation belt are immune from the unforgiving penetration of the highly energetic protons (tens of MeV to GeV). The inner belt proton flux level, however, is relatively stable; thus, for any given instrument, the proton contamination often leads to a certain background noise. Measurements from the Relativistic Electron and Proton Telescope integrated little experiment on board Colorado Student Space Weather Experiment CubeSat, in a low Earth orbit, clearly demonstrate that there exist sub-MeV electrons in the inner belt because their flux level is orders of magnitude higher than the background, while higher-energy electron (>1.6 MeV) measurements cannot be distinguished from the background. Detailed analysis of high-quality measurements from the Relativistic Electron and Proton Telescope on board Van Allen Probes, in a geo-transfer-like orbit, provides, for the first time, quantified upper limits on MeV electron fluxes in various energy ranges in the inner belt. These upper limits are rather different from flux levels in the AE8 and AE9 models, which were developed based on older data sources. For 1.7, 2.5, and 3.3 MeV electrons, the upper limits are about 1 order of magnitude lower than predicted model fluxes. The implication of this difference is profound in that unless there are extreme solar wind conditions, which have not happened yet since the launch of Van Allen Probes, significant enhancements of MeV electrons do not occur in the inner belt even though such enhancements are commonly seen in the outer belt. Key Points Quantified upper limit of MeV electrons in the inner belt Actual MeV electron intensity likely much lower than the upper limit More detailed understanding of relativistic electrons in the magnetosphere PMID:26167446

  4. Upper limit on the inner radiation belt MeV electron intensity.

    Science.gov (United States)

    Li, X; Selesnick, R S; Baker, D N; Jaynes, A N; Kanekal, S G; Schiller, Q; Blum, L; Fennell, J; Blake, J B

    2015-02-01

    No instruments in the inner radiation belt are immune from the unforgiving penetration of the highly energetic protons (tens of MeV to GeV). The inner belt proton flux level, however, is relatively stable; thus, for any given instrument, the proton contamination often leads to a certain background noise. Measurements from the Relativistic Electron and Proton Telescope integrated little experiment on board Colorado Student Space Weather Experiment CubeSat, in a low Earth orbit, clearly demonstrate that there exist sub-MeV electrons in the inner belt because their flux level is orders of magnitude higher than the background, while higher-energy electron (>1.6 MeV) measurements cannot be distinguished from the background. Detailed analysis of high-quality measurements from the Relativistic Electron and Proton Telescope on board Van Allen Probes, in a geo-transfer-like orbit, provides, for the first time, quantified upper limits on MeV electron fluxes in various energy ranges in the inner belt. These upper limits are rather different from flux levels in the AE8 and AE9 models, which were developed based on older data sources. For 1.7, 2.5, and 3.3 MeV electrons, the upper limits are about 1 order of magnitude lower than predicted model fluxes. The implication of this difference is profound in that unless there are extreme solar wind conditions, which have not happened yet since the launch of Van Allen Probes, significant enhancements of MeV electrons do not occur in the inner belt even though such enhancements are commonly seen in the outer belt. Quantified upper limit of MeV electrons in the inner beltActual MeV electron intensity likely much lower than the upper limitMore detailed understanding of relativistic electrons in the magnetosphere.

  5. Versterking van de loopbaanladder van leraren : wat kunnen we leren van Singapore?

    NARCIS (Netherlands)

    Elffers, L.

    2015-01-01

    In de Lerarenagenda 2013-2020 is een aantal doelstellingen geformuleerd ten aanzien van de bevordering van de loopbaan en professionele ontwikkeling van leraren. Enerzijds wordt ingezet op het stimuleren van professionalisering van leraren na hun initiële opleiding, anderzijds op het versterken van

  6. Synthesis and ligand properties of a persistent, all-carbon four-membered-ring allene.

    Science.gov (United States)

    Melaimi, Mohand; Parameswaran, Pattiyil; Donnadieu, Bruno; Frenking, Gernot; Bertrand, Guy

    2009-01-01

    A single donor substituent at each terminus is sufficient to make the CCC skeleton of allenes very flexible and give carbon(0) character to the central carbon atom. This allows the synthesis of a four-membered carbocyclic allene, which can be doubly protonated and behaves as a very strong eta(1)-donor ligand for transition metals (see scheme).

  7. Q & A with Ed Tech Leaders: Interview with Michael W. Allen

    Science.gov (United States)

    Shaughnessy, Michael F.

    2014-01-01

    Michael W. Allen, the Chairman and CEO of Allen Interactions, is an architect of interactive multimedia learning and is recognized for his many insights, inventions, and presentations. With over 50 years of experience in e-learning, both in academic and corporate settings, he is known for his role in creating Authorware and overseeing the work of…

  8. The Reliability and Validity of Bem and Allen's Measure of Cross-Situational Consistency.

    Science.gov (United States)

    Greaner, Jackie L.; Penner, Louis A.

    1982-01-01

    Investigated the reliability and validity of Bem and Allen's cross-situational consistency measuring technique. Results showed low reliability for Bem and Allen's test-retest, high reliability for Snyder's Self-Monitoring Scale, and significant correlation between self-reported academic behavior variability and actual grade variability. (WAS)

  9. Die ontwikkeling van 'n meetinstrument van werkstres

    Directory of Open Access Journals (Sweden)

    E. S. Van Zyl

    1994-06-01

    Full Text Available The development of an instrument for work stress. The aim of the investigation was to develop a valid and reliable job stress measuring instrument. As part of the technical analysis of the "Experience of Work and Life Circumstances Questionnaire" (WLQ, it is pointed out that reliability coefficients vary between 0,62 and 0,92, and that the questionnaire proves to have content as well as construct validity. Opsomming Die doelstelling van hierdie ondersoek was om 'n geldige en betroubare werkstresmeetinstrument te ontwikkel. As deel van die tegniese ontleding van die "Ervaring van Werk- en Lewensomstandighedevraelys" (WLV, is onder meer uitgewys dat die betroubaarheidskoeffisiente daarvan tussen 0,62 en 0,92 wissel en dat die vraelys oor inhouds en konstrukgeldigheid beskik.

  10. A. VAN SELMS. LUKAS SE SEGSMAN VIR DIE GESKIEDENIS VAN ...

    African Journals Online (AJOL)

    Test

    wek dit die gewaarwording by die leser dat een van die Emmaüsgangers. -self hierdie geskiedenis aan die skrywer van die derde Evangelie vertel het. Hierdie gewaarwording van die onmiddellikheid van die oorlewe- ring berus op verskillende gronde. Die eerste is die merkwaardige palestynse kleur van die geskiedenis ...

  11. Het effect van substraat structuur op groei van schimmels

    NARCIS (Netherlands)

    Baars, J.J.P.; Sonnenberg, A.S.M.

    2011-01-01

    Champignons worden geteeld op een complex van voedingsstoffen ontstaan na fermentatie van strorijke paarden mest, kuikenmest, stro, gips en water. Voor de productie van champignons breekt het mycelium slechts 25% van het organische materiaal in de compost af. Dat is weinig voor iets dat ca. 40% van

  12. Thales van Milete en het begin van de filosofie

    NARCIS (Netherlands)

    Poorthuis, Marcel

    2016-01-01

    Het water als oorsprong van alles is niet alleen een natuurkundige of biologische gedachte, maar tevens een metafysisische idee over de oorsprong van alle dingen. Deze uitspraak van Thales van Milete markeert het begin van de filosofie. Zowel kerkvaders als moderne filosofen onder wie Nietzsche en

  13. Karakterisering van de zuurgevoeligheid van Salmonella typhimurium faagtype DT104

    NARCIS (Netherlands)

    de Jonge R; van Leusden FM; Dufrenne JB; Ritmeester WS; Delfgou-van Asch EHM; van Pelt W; LBG

    1999-01-01

    Het aantal gevallen van salmonellosis in Nederland veroorzaakt door Salmonella typhimurium faagtype DT104 is toegenomen van 10 in 1985 tot 163 in 1997 (10% van alle gevallen van salmonellosis). De stam lijkt zijn oorsprong te hebben in het Verenigd Koninkrijk. Daar wordt inmiddels 20% van alle

  14. Die wonder van Afrikaans

    Directory of Open Access Journals (Sweden)

    H. Venter

    1959-03-01

    Full Text Available In die Januarie-Februarie-uitgawe van Koers het die hoofredakteur daarop gewys dat 1959 ’n gedenkjaar is, en onde randere ook vermeld dat dit die jaar is van die goue jubileum van die Suid-Afrikaanse Akademie vir Wetenskap en Kuns (gestig op 2 Julie 1909. Daarby moet ons nie vergeet dat die P.A.K. (gestig19 Desember 1929 in hierdie jaar sy dertigste bestaansjaar voltooi nie. Dit is dan ook heeltemal gepas dat ons in hierdie gedenkjaar, op versoek van hierdie twee liggame wat so ontsaglik baie gedoen het vir die handhaaf en bou van ons taal, ons aandag sal saamtrek rondom die wonder van Afrikaans.

  15. De auteursrechtelijke groeipijnen van Google

    NARCIS (Netherlands)

    Hugenholtz, P.B.

    2011-01-01

    Het succesverhaal van Google behoort tot de canon van de geschiedenis van onze informatiemaatschappij. In 1998 begonnen in een studentenkamer op de campus van Stanford University, groeide Google in enkele jaren uit tot het orakel van het internet. Zo werd ‘googelen’ de gebruikelijke term voor zoeken

  16. Detection of DNA damage by space radiation in human fibroblasts flown on the International Space Station

    Science.gov (United States)

    Lu, Tao; Zhang, Ye; Wong, Michael; Feiveson, Alan; Gaza, Ramona; Stoffle, Nicholas; Wang, Huichen; Wilson, Bobby; Rohde, Larry; Stodieck, Louis; Karouia, Fathi; Wu, Honglu

    2017-02-01

    Although charged particles in space have been detected with radiation detectors on board spacecraft since the discovery of the Van Allen Belts, reports on the effects of direct exposure to space radiation in biological systems have been limited. Measurement of biological effects of space radiation is challenging due to the low dose and low dose rate nature of the radiation environment, and due to the difficulty in distinguishing the radiation effects from microgravity and other space environmental factors. In astronauts, only a few changes, such as increased chromosome aberrations in their lymphocytes and early onset of cataracts, are attributed primarily to their exposure to space radiation. In this study, cultured human fibroblasts were flown on the International Space Station (ISS). Cells were kept at 37 °C in space for 14 days before being fixed for analysis of DNA damage with the γ-H2AX assay. The 3-dimensional γ-H2AX foci were captured with a laser confocal microscope. Quantitative analysis revealed several foci that were larger and displayed a track pattern only in the Day 14 flight samples. To confirm that the foci data from the flight study was actually induced from space radiation exposure, cultured human fibroblasts were exposed to low dose rate γ rays at 37 °C. Cells exposed to chronic γ rays showed similar foci size distribution in comparison to the non-exposed controls. The cells were also exposed to low- and high-LET protons, and high-LET Fe ions on the ground. Our results suggest that in G1 human fibroblasts under the normal culture condition, only a small fraction of large size foci can be attributed to high-LET radiation in space.

  17. Detection of DNA Damage by Space Radiation in Human Fibroblasts Flown on the International Space Station

    Science.gov (United States)

    Lu, Tao; Zhang, Ye; Wong, Michael; Feiveson, Alan; Gaza, Ramona; Stoffle, Nicholas; Wang, Huichen; Wilson, Bobby; Rohde, Larry; Stodieck, Louis; hide

    2017-01-01

    Although charged particles in space have been detected with radiation detectors on board spacecraft since the discovery of the Van Allen Belts, reports on the effects of direct exposure to space radiation in biological systems have been limited. Measurement of biological effects of space radiation is challenging due to the low dose and low dose rate nature of the radiation environment, and due to the difficulty in distinguishing the radiation effects from microgravity and other space environmental factors. In astronauts, only a few changes, such as increased chromosome aberrations in their lymphocytes and early onset of cataracts, are attributed primarily to their exposure to space radiation. In this study, cultured human fibroblasts were flown on the International Space Station (ISS). Cells were kept at 37 degrees Centigrade in space for 14 days before being fixed for analysis of DNA damages with the gamma-H2AX assay. The 3-dimensional gamma-H2AX foci were captured with a laser confocal microscope. Quantitative analysis revealed several foci that were larger and displayed a track pattern only in the Day 14 flight samples. To confirm that the foci data from the flight study was actually induced from space radiation exposure, cultured human fibroblasts were exposed to low dose rate gamma rays at 37 degrees Centigrade. Cells exposed to chronic gamma rays showed similar foci size distribution in comparison to the non-exposed controls. The cells were also exposed to low- and high-LET (Linear Energy Transfer) protons, and high-LET Fe ions on the ground. Our results suggest that in G1 human fibroblasts under the normal culture condition, only a small fraction of large size foci can be attributed to high-LET radiation in space.

  18. Bepaling van kwaliteitskenmerkende parameters in aspergestengels met behulp van NIRA

    NARCIS (Netherlands)

    Ammerlaan, A.W.S.; Frankhuizen, R.; Veen, van der N.G.

    1986-01-01

    Nagaan of met behulp van Nabij Infrarood reflectie spectroscopie lignine en andere kwaliteitskenmerkende parameters in aspergestengels bepaald kunnen worden. In het kader van doctoraalonderzoek (dhr A.W.S. Ammerlaan, vakgroep Tuinbouwplantenteelt van de LH) wordt onderzoek uitgevoerd naar de

  19. Effecten van temperatuur op de fotosynthese van Cymbidium

    NARCIS (Netherlands)

    Schapendonk, A.H.C.M.; Kromwijk, J.A.M.

    2005-01-01

    Dit onderzoek is uitgevoerd naar aanleiding van een onderzoeksvraag van de LTOcommissie Cymbidium naar optimale teeltomstandigheden in relatie tot de fotosynthese. Door metingen op een praktijkbedrijf is meer inzicht verkregen in optimale en limiterende omstandigheden van de groeifactoren licht,

  20. Geostatistische opschaling van concentraties van gewasbeschermingsmiddelen in het Nederlandse oppervlaktewater

    NARCIS (Netherlands)

    Heuvelink, G.B.M.; Kruijne, R.; Musters, C.J.M.

    2011-01-01

    Metingen van concentraties van gewasbeschermingsmiddelen in het Nederlandse oppervlaktewater worden met een geostatistische methode opgeschaald naar landelijke waarden. De methode maakt gebruik van ruimte-tijd regressie-kriging, waarbij zowel informatie in de metingen zelf als in landsdekkende

  1. HELLE: Health Effects of Low Level Exposures/ Gezondheidseffecten van lage blootstellingniveaus [International workshop: Influence of low level exposures to chemicals and radiation on human and ecological health

    Energy Technology Data Exchange (ETDEWEB)

    Schoten, Eert

    1998-11-26

    The Health Council is closely involved in establishing the scientific foundation of exposure limits for substances and radiation in order to protect public health. Through the years, the Council has contributed to the formulation of principles and procedures, both for carcinogenic and for noncarcinogenic agents. As a rule, the discussion with regard to the derivation of health-based recommended exposure limits centers around the appropriateness of extrapolation methods (What can be inferred from data on high exposure levels and on experimental animals?). Generally speaking, there is a lack of direct information on the health effects of low levels of exposure. Effects at these levels cannot usually be detected by means of traditional animal experiments or epidemiological research. The capacity of these analytical instruments to distinguish between ''signal'' and ''noise'' is inadequate in most cases. Annex B of this report contains a brief outline of the difficulties and the established methods for tackling this problem. In spite of this, the hope exists that the posited weak signals, if they are indeed present, can be detected by other means. The search will have to take place on a deeper level. In other words, effort must be made to discover what occurs at underlying levels of biological organization when organisms are exposed to low doses of radiation or substances. Molecular and cell biology provide various methods and techniques which give an insight into the processes within the cell. This results in an increase in the knowledge about the molecular and cellular effects of exposure to agents, or stated differently, the working mechanisms which form the basis of the health effects. Last year, the Health Council considered that the time was ripe to take stock of the state of knowledge in this field. To this end, an international working conference was held from 19 to 21 October 1997, entitled ''Health Effects of

  2. Teelt van knolvenkel

    NARCIS (Netherlands)

    Buishand, T.; Jonge, de P.

    1984-01-01

    Herziene teelthandleiding over plantkundige eigenschappen, grond, bemesting, ervaringen met rassen in Nederland, zaaien en planten, onkruidbestrijding, ziekten en plagen, oogst, bewaring, aflevering, voorbeelden van arbeidsbehoefte en saldoberekeningen

  3. Voorspelling van die akademiese sukses van eerstejaarstudente

    Directory of Open Access Journals (Sweden)

    M. M. Rademeyer

    1998-06-01

    Full Text Available Prediction of academic success of first year students. The recent amalgamation of the various regional education systems in South Africa and as a result/ the restructuring of the education dispensation, led to a number of problems which impacted negatively on the examination process. Against this backdrop, the present study attempted to find a valid altermative for matric marks as a predictor of academic success. Multiple regression analyses and canonical discriminant analyses were performed to construct a comprehensive model, which can be used to predict the academic achievement of students, and serve as an alternative for matric marks. Regression analyses with average exam mark as criterion were performed on the data of the three largest faculties. Multiple correlations of 0,59, 0,56 and 0,52 were obtained. Discriminant analyses were done against a promotion criterion (promoted,not promoted, for each of the faculties. According to the results of the discriminant analyses the percentage correct classifications varied from 62,7% to 81,1%. Opsomming Die onlangse samesmelting van die onderskeie streeksonderwysstelsels in Suid-Afrika en die gevolglike herstrukturering van die onderwys, het sy eie kwota probleme opgelewer wat 'n negatiewe impak op matriekeksaminering gehad het. Teen hierdie agtergrond het die huidige studie gepoog om 'n geldige alternatief vir matriekpunte as voorspeller van akademiese prestasie te vind. Meervoudige regressie-ontledings asook kanoniese diskriminantontledings is op die datastel uitgevoer ten einde 'n omvattende model daar te stel waarmee die akademiese prcstasie van studente voorspel kan word, en wat as plaasvervanger vir matriekpunte kan dien. regressie- ontledings vir die drie grootste fakulteite is gedoen met die gemiddelde eksamenpunt as kriterium. Meervoudige korrelasies van 0,59, 0,56 en 0,52 is verkry. Diskriminantontledings is vir elke fakulteit teenoor 'n promosiekriterium (promoveer/nie-promo-veer uitgevoer

  4. Die Romeinse nastrewing van onsterflikheid deur middel van memoria

    Directory of Open Access Journals (Sweden)

    D. R. Fouché

    1985-05-01

    Full Text Available Benewens die omvangryke en nasionale manifestasies van die oorspronklike onsterflikheidsgedagte in die Romeinse gemeenskap, vind ons by die Romein op kleiner skaal in groepe of indiwidueel ’n strewe na onsterflikheid langs die weg van memoria. Soos aangetoon sal word, verskil die pogings van die verskillende groepe radikaal van mekaar, hoewel die strewe en einddoel dieselfde bly, naamlik om deur die daarstelling van memoria op die gebied van woord of daad onsterflikheid te bekom.

  5. De Afscheiding van 1834 herdacht

    Directory of Open Access Journals (Sweden)

    G.J. Schutte

    1986-01-01

    Full Text Available W. Bakker, De Afscheiding van 1834 en haar geschiedenis A.P. Crom, Anderhalve eeuw gereformeerden in stad en land P. van de Breevaart, De vereniging van 1907. De vereniging van de Ledeboeriaanse gemeenten en de gereformeerde gemeenten onder het kruis D. Deddens, J. Kamphuis, Afscheiding-wederkeer. Opstellen over de Afscheiding van 1834 M. Drayer, W. van't Spijker, In trouw gescheiden C. de Gast, De Afscheiding van 1835 in Almkerk en Emmichoven. Godsdiensttwisten in het land van Heusden en Altena A. de Groot, Hermanus Willem Witteveen en zijn zendingsgemeente te Ermelo A.M. Lindeboom, Om de grondslagen van het christendom. Overpeinzingen bij het honderdvijftigjarig jubileum van de Afscheiding B. Coster, Om de zuiverheid van het Woord. Historische en genealogische bijdragen betreffende de afscheiding van 1834 in Drenthe F. Pereboom, 'Van scheurmakers, onruststokers en geheime opruijers...' De Afscheiding in Overijssel C. van Rijswijk, De kruisdrager van Ulrum. Levensbeschrijving van ds. H. de Cock T.N. Schelhaas, De afgescheidenen van 1834 en hun nageslacht C. Smits, De Afscheiding van 1834, V, Documenten uit het archief ds. H. P. Scholte, bewaard te Pella, Iowa, USA (vervolg C. Smits, De Afscheiding van 1834, VI, Het Réveil en ds. H. P. Scholte. Correspondentie W. van 't Spijker, Anthony Brummelkamp. Een terugblik op de Afscheiding H. Veldman, De Afscheiding van 1834 J. Vree, De Groninger godgeleerden. De oorsprong en de eerste periode van hun optreden (1820-1843 J. Wesseling, De Afscheiding van 1834 in Friesland, III, De classes Sexbierum (Franeker, Sneek en Tjalleberd (Heerenveen van de Afgescheiden kerken J. Wesseling, De Afscheiding van 1834 in Overijssel 1834-'69, I, De classis Zwolle R.P. Zijp, Anderhalve eeuw gereformeerden 1834-1984

  6. De invloed van meerwaarde van biologische producten op consumentenaankopen : consumentenperceptie van biologische producten in de supermarkt

    NARCIS (Netherlands)

    Tacken, G.M.L.; Winter, de M.A.; Wertheim-Heck, S.C.O.

    2007-01-01

    In-store consumentenonderzoek naar de perceptie van prijs en meerwaarde van biologische producten ten opzichte van gangbare producten onder wekelijkse kopers en incidentele kopers van biologische producten en kopers van gangbare voedingsmiddelen. Het onderzoek is uitgevoerd in tien plaatsen in

  7. Karakterisering van het Etimologiewoordeboek van Afrikaans (EWA

    Directory of Open Access Journals (Sweden)

    Fons Moerdijk

    2011-10-01

    Full Text Available

    Samenvatting: Zesendertig jaar na Afrikaanse etimologieë van Boshoff en Nienaber verscheener in 2003 een nieuw etymologisch woordenboek van het Afrikaans: het Etimologiewoordeboek vanAfrikaans (EWA. Tussen die twee woordenboeken bestaat een wezenlijk verschil. Het werk vanBoshoff en Nienaber is vrijwel alleen toegankelijk voor specialisten en niet specifiek bedoeld vooreen breed publiek. EWA is juist allereerst bestemd voor de leek die zich interesseert voor de oorsprongen de geschiedenis van de eigen taal. Daarnaast biedt het ook de etymoloog en historischtaalkundige een hoop gegevens en inspiratie voor nader onderzoek. Als etymologisch woordenboekbezit EWA een aantal bijzondere, eigen kenmerken. De selectie van de woorden is bepaalddoor het beoogde gebruikerspubliek. Als gevolg daarvan bevat EWA verscheidene typen woordendie in traditionele etymologische woordenboeken doorgaans veronachtzaamd worden, zoals afleidingen,samenstellingen, neologismen en gemeenzame spreektaalwoorden. De artikelstructuurwordt gekenmerkt door een hoge graad van uniformiteit en consistentie. Het accent ligt op dezogenaamde etymologia proxima, de etymologie waarbij men één stap teruggaat en de meestdirecte herkomst van het woord biedt. Voorts is speciale aandacht besteed aan polysemie: nietalleen de herkomst van de dominante betekenis van een woord wordt gegeven, maar ook die vanzijn eventuele andere betekenis(sen. Benoemingsmotieven komen ook veelvuldig aan bod. In eeneventuele tweede druk zouden opvallende verschillen in vorm of betekenis altijd verklaard of inieder geval besproken moeten worden. Dat blijft nu nogal eens achterwege. Ook zou voorafgaandaan zo'n volgende editie meer onderzoek naar woordhistorisch materiaal uit primaire bronnenvoor met name de 17de–19de eeuw verricht moeten worden. Het zou mooi zijn als deze eersteuitgave van EWA de aanleiding tot een dergelijk onderzoek zou vormen.

    Sleutelwoorden: BENOEMINGSMOTIEF, ETYMOLOGIA PROXIMA

  8. Dialyse van citraatbloed voor transfusie

    NARCIS (Netherlands)

    Huizinga, Tekke

    1957-01-01

    Na 1943 is een aantal publikaties verschenen, waarin melding wordt gemaakt van citraatintoxicaties tengevolge van snelle transfusies van grote hoeveelheden citraatbloed. Deze publikaties zijn uitganspunt geweest voor een aantal dierproeven, waarin de klinische ervaringen experimenteel werden

  9. Anterieure discusverplaatsing van het kaakgewricht

    NARCIS (Netherlands)

    Kalaykova, S.I.; Lobbezoo, F.; Naeije, M.

    2009-01-01

    Functiestoornissen van het kaakgewricht, zoals knappende gewrichtsgeluiden en/of gelimiteerde onderkaakbewegingen, worden vaak veroorzaakt door een anterieure discusverplaatsing (anterior disc displacement, ADD). Afhankelijk van de vraag of er herstel optreedt van de condylus-discusrelatie tijdens

  10. On the Connection Between Microbursts and Nonlinear Electronic Structures in Planetary Radiation Belts

    Science.gov (United States)

    Osmane, Adnane; Wilson, Lynn B., III; Blum, Lauren; Pulkkinen, Tuija I.

    2016-01-01

    Using a dynamical-system approach, we have investigated the efficiency of large-amplitude whistler waves for causing microburst precipitation in planetary radiation belts by modeling the microburst energy and particle fluxes produced as a result of nonlinear wave-particle interactions. We show that wave parameters, consistent with large amplitude oblique whistlers, can commonly generate microbursts of electrons with hundreds of keV-energies as a result of Landau trapping. Relativistic microbursts (greater than 1 MeV) can also be generated by a similar mechanism, but require waves with large propagation angles Theta (sub k)B greater than 50 degrees and phase-speeds v(sub phi) greater than or equal to c/9. Using our result for precipitating density and energy fluxes, we argue that holes in the distribution function of electrons near the magnetic mirror point can result in the generation of double layers and electron solitary holes consistent in scales (of the order of Debye lengths) to nonlinear structures observed in the radiation belts by the Van Allen Probes. Our results indicate a relationship between nonlinear electrostatic and electromagnetic structures in the dynamics of planetary radiation belts and their role in the cyclical production of energetic electrons (E greater than or equal to 100 keV) on kinetic timescales, which is much faster than previously inferred.

  11. Subcritical Growth of Electron Phase-space Holes in Planetary Radiation Belts

    Science.gov (United States)

    Osmane, A.; Wilson, L. B., III; Turner, D. L.; Dimmock, A. P.; Pulkkinen, T. I.

    2017-12-01

    The discovery of self-sustained coherent structures with large-amplitude electric fields (E ˜ 10 - 100 mV/m) by the Van Allen Probes has revealed alternative routes through which energy-momentum exchange can take place in planetary radiation belts. When originating from energetic electrons in Landau resonance with large-amplitude whistlers, phase-space electron holes form with small amplitudes of the order of the hot to cold electron density, i.e., qφ/T_e≃ n_h/n_c ≃ 10^{-3}, and orders of magnitude smaller than observed values of the largest phase-space holes amplitude, i.e., qφ /T_e ≃ 1. In this report we present a mechanism through which electron holes can grow nonlinearly (i.e. γ ∝ √{φ}) and subcritically as a result of momentum exchange with passing (untrapped) electrons. Growth rates are computed analytically for plasma parameters consistent with those measured in the Earth's radiation belts under quiet and disturbed conditions. Our results provide an explanation for the fast growth of electron phase-space holes in the Earth's radiation belts from small initial values qφ/T_c ≃ 10^{-3}, to larger values of the order qφ /T_e ≃ 1.

  12. Investigating the source of near-relativistic and relativistic electrons in Earth's inner radiation belt

    Science.gov (United States)

    Turner, D. L.; O'Brien, T. P.; Fennell, J. F.; Claudepierre, S. G.; Blake, J. B.; Jaynes, A. N.; Baker, D. N.; Kanekal, S.; Gkioulidou, M.; Henderson, M. G.; Reeves, G. D.

    2017-01-01

    Using observations from NASA's Van Allen Probes, we study the role of sudden particle enhancements at low L shells (SPELLS) as a source of inner radiation belt electrons. SPELLS events are characterized by electron intensity enhancements of approximately an order of magnitude or more in less than 1 day at L belt electrons under quiet/average conditions. During SPELLS events, the evolution of electron distributions reveals an enhancement of phase space density that can exceed 3 orders of magnitude in the slot region and continues into the inner radiation belt, which is evidence that these events are an important—and potentially dominant—source of inner belt electrons. Electron fluxes from September 2012 through February 2016 reveal that SPELLS occur frequently ( 2.5/month at 200 keV), but the number of observed events decreases exponentially with increasing electron energy for ≥100 keV. After SPELLS events, the slot region reforms due to slow energy-dependent decay over several day time scales, consistent with losses due to interactions with plasmaspheric hiss. Combined, these results indicate that the peaked phase space density distributions in the inner electron radiation belt result from an "on/off," geomagnetic-activity-dependent source from higher radial distances.

  13. The effects of magnetospheric processes on relativistic electron dynamics in the Earth's outer radiation belt

    Science.gov (United States)

    Tang, C. L.; Wang, Y. X.; Ni, B.; Su, Z. P.; Reeves, G. D.; Zhang, J.-C.; Baker, D. N.; Spence, H. E.; Funsten, H. O.; Blake, J. B.

    2017-10-01

    Using the electron phase space density (PSD) data measured by Van Allen Probe A from January 2013 to April 2015, we investigate the effects of magnetospheric processes on relativistic electron dynamics in the Earth's outer radiation belt during 50 geomagnetic storms. A statistical study shows that the maximum electron PSDs for various μ (μ = 630, 1096, 2290, and 3311 MeV/G) at L* 4.0 after the storm peak have good correlations with storm intensity (cc 0.70). This suggests that the occurrence and magnitude of geomagnetic storms are necessary for relativistic electron enhancements at the inner edge of the outer radiation belt (L* = 4.0). For moderate or weak storm events (SYM-Hmin > -100 nT) with weak substorm activity (AEmax 0.77). For storm events with intense substorms after the storm peak, relativistic electron enhancements at L* = 4.5 and 5.0 are observed. This shows that intense substorms during the storm recovery phase are crucial to relativistic electron enhancements in the heart of the outer radiation belt. Our statistics study suggests that magnetospheric processes during geomagnetic storms have a significant effect on relativistic electron dynamics.

  14. Substorm Injected Energetic Electrons and Ions Deeply into the Inner Magnetosphere Observed by BD-IES and Van Allan Probes

    Science.gov (United States)

    Zong, Qiugang

    2017-04-01

    When substorm injections are observed simultaneously with multiple spacecraft, they help elucidate potential mechanisms for particle transport and energization, a topic of great importance for understanding and modeling the magnetosphere. In the present paper, by using the data return from the BeiDa- IES (BD-IES) instrument onboard an inclined (55◦) geosynchronous orbit (IGSO) satellite together with geo-transfer orbit (GTO) Van Allen Probe A&B satellite, we analysis a substorm injection event occurred on Oct 16, 2015. During the substorm injection, the IES onboard IGSO is outbound while both Van Allen Probe A&B satellites are inbound. This configuration of multiple satellite trajectories provides a unique opportunity to investigate the inward and outward radial propagation of the substorm injection simultaneously. This substorm as indicated by AE/AL indices is closely related an IMF/solar wind discontinuity with a sharp change in the IMF Bz direction (northward turning). The innermost signature of this substorm injection has been detected by the Van Allen Probes A & B at L 3.7. The outermost signature, observed by the BD-IES, is found to be at L 10. This indicated that this substorm have a rather global effect rather than just a local effect. Further, we suggest that the electric fields carried by fast-mode compressional waves around the substorm injection are the most likely mechanism candidate for the injection signatures of electrons observed in the innermost and outermost inner magnetosphere.

  15. Radial Propagation of Magnetospheric Substorm Injected Energetic Electrons Observed by BD-IES and Van Allan Probes

    Science.gov (United States)

    Zong, Q.

    2016-12-01

    When substorm injections are observed simultaneously with multiple spacecraft, they help elucidate potential mechanisms for particle transport and energization, a topic of great importance for understanding and modeling the magnetosphere. In the present paper, by using the data return from the BeiDa- IES (BD-IES) instrument onboard an inclined (55°) geosynchronous orbit (IGSO) satellite together with geo-transfer orbit (GTO) Van Allen Probe A&B satellite, we analysis a substorm injection event occurred on Oct 16, 2015. During the substorm injection, the IES onboard IGSO is outbound while both Van Allen Probe A&B satellites are inbound. This configuration of multiple satellite trajectories provides a unique opportunity to investigate the inward and outward radial propagation of the substorm injection simultaneously. This substorm as indicated by AE/AL indices is closely related an IMF/solar wind discontinuity with a sharp change in the IMF Bz direction (northward turning). The innermost signature of this substorm injection has been detected by the Van Allen Probes A & B at L 3.7. The outermost signature, observed by the BD-IES, is found to be at L 10. This indicated that this substorm have a rather global effect rather than just a local effect. Further, we suggest that the electric fields carried by fast-mode compressional waves around the substorm injection are the most likely mechanism candidate for the injection signatures of electrons observed in the innermost and outermost inner magnetosphere.

  16. De teelt van walnoten

    NARCIS (Netherlands)

    Wertheim, S.J.

    1981-01-01

    De laatste jaren is er weer een toenemende belangstelling voor walnoten te constateren. Deze interesse komt in een enkel geval van een grondeigenaar die met noteteelt zijn grond rendabel wil maken. Meestal gaat het echter om de beplanting van erven, overhoeken, wegbermen en dijken. Vanwege deze

  17. Voorbehandeling van freesia

    NARCIS (Netherlands)

    Sytsema, W.; Elfering - Koster, K.G.

    1984-01-01

    Resultaten van een zestal proeven in de periode eind 1982 tot juni 1983. In vier proeven is de invloed onderzocht van zilverthiosulfaat op de uitbloei, waarbij tevens de faktoren snijstadium en afzetsimulatie (korte bewaring) zijn betrokken. In twee proeven is een reeks rassen voorbehandeld met

  18. De magie van plekken

    NARCIS (Netherlands)

    Hospers, Gerrit J.

    2015-01-01

    Maakt het in deze tijd eigenlijk nog uit waar we ons bevinden? Sommige experts beweren van niet. Ze bespeuren een death of distance: onder invloed van informatie- en communicatietechnologie zou afstand steeds minder relevant worden. Door mobiele telefonie, internet, Facebook en Skype lijkt het niet

  19. Milieucondities van aquatische beheertypen

    NARCIS (Netherlands)

    Loeb, R.; Verdonschot, P.F.M.

    2010-01-01

    Voor de beheertypen van Index-NL is invulling gegeven aan de kwaliteitsaspecten van de aquatische typen. De kwaliteit in de Index-NL typen wordt afgemeten aan de (1) biotische natuur, (2) milieucondities, (3) ruimtelijke samenhang, (4) structuur en beheer, en (5) natuurlijke processen. In deze

  20. Communicatiekaart van Nederland

    NARCIS (Netherlands)

    Dr. Piet Bakker; Otto Scholten

    2011-01-01

    De mogelijkheden om met de medemens te communiceren en/of op de hoogte te blijven van wat zich in de wereld afspeelt, zijn de afgelopen decennia sterk veranderd en toegenomen. Zo sterk dat ze nu vrijwel grenzeloos zijn. Er zijn tal van nieuwe media bijgekomen: gratis dagbladen, iPads, smart phones,

  1. Sociale vergelijking van salarissen.

    NARCIS (Netherlands)

    Grumbkow, Jasper von

    1980-01-01

    Het onderwerp van het onderzoeksverslag is de nieuwsgierigheid van mensen naar salarisgegevens. Centraal in deze studie staat de sociale vergelijkingstheorie (Festinger, 1954) op grond waarvan aangenomen wordt dat mensen twee doelen op het oog hebben wanneer ze hun aandacht richten op

  2. Ornamenten van het vergeten

    NARCIS (Netherlands)

    2007-01-01

    Ornamenten van het vergeten, zo typeert Walter Benjamin in Zum Bilde Prousts de typische vertelstructuur van diens grote werk A la recherche du temps perdu. Op zoek naar de verloren tijd orchestreert Proust het vergeten. Dit vergeten is "de zwarte muur waartegen zich enkele motieven vertonen, en het

  3. Samenstelling van rundergehakt

    NARCIS (Netherlands)

    Cazemier, G.

    1991-01-01

    In oktober 1989 werden 100 monsters rundergehakt onderzocht op de chemische samenstelling. Dertien van de honderd monsters waren ingekocht als mager rundergehakt. De monsters werden onderzocht op de gehalten aan vocht, vet, eiwit, collageen en op de toevoeging van varkensvlees. Uit de

  4. Grondbeginselen van de methode

    NARCIS (Netherlands)

    Pestalozzi, Johann Heinrich

    1995-01-01

    In opvoeding en onderwijs gaat het volgens Pestalozzi om de ontwikkeling van hoofd, hart en handen (‘Pädagogik des Kopfes, des Herzens und der Hand’). Het beste geschiedt dat door middel van de ‘natuurlijke opvoeding’. Hij noemde dit zijn ‘methode’.

  5. Late effecten van kankerbehandeling

    NARCIS (Netherlands)

    Langeveld, Nelia E.

    2004-01-01

    In dit artikel wordt ingegaan op de lange termijn effecten van kanker op de kinderleeftijd. Vervolgens wordt een kort overzicht gegeven van de belangrijkste late gevolgen die kunnen optreden na een oncologische behandeling met radio- en/of chemotherapie toegepast in de kinderleeftijd. Er wordt kort

  6. Erosie van rivieroevers

    NARCIS (Netherlands)

    Mosselman, E.

    1987-01-01

    Oevers staan sinds kart in het middelpunt van de belangstellingbij beheerders van oppervlaktewateren in Nederland. Niet langerbeschouwt men oevers slechts als randverschijnsel, maar alsobjecten met een duidelijk eigen plaats en functie.Het streven om te komen tot een integraal waterbeleid

  7. Voorspelling van de invloed van splenectomie op het verloop van de ziekte van Werlhof

    NARCIS (Netherlands)

    Fontein, Dirk Leonard

    1971-01-01

    De in dit proefschrift beschreven methode maakt het mogelijk, bij patienten lijdende aan de ziekte van Werlhof, in een aantal gevallen reeds voor de operatie een uitspraak te doen over de invloed van splenectomie op het aantal trombocyten. Indien vervracht wordt dat de ingreep niet tot een complete

  8. Kroniek van het mededingingsrecht

    NARCIS (Netherlands)

    Wesseling, R.; Truijens Martinez, J.

    2015-01-01

    Waar liggen de grenzen van het bereik van het mededingingsrecht? Die vraag komt steeds vaker op. Buiten het mededingingsrecht heeft de Europese Commissie beperkte handhavingsbevoegdheden. Voor de Commissie is een probleem dus al snel een mededingingsrechtelijke kwestie. De Libor-affaire en

  9. Het mesten van beren

    NARCIS (Netherlands)

    Peet-Schwering, van der C.M.C.; Swinkels, P.

    1987-01-01

    Door de Europese Commissie is vastgesteld dat vanaf 1 januari 1985 vlees van beren, dat voorzien is van een speciaal streepjesstempel, binnen de EG verhandeld mag worden, mits dit vlees bestemd is voor de vleeswarenproduktie. Op het Varkensproefbedrijf te Sterksel zijn twee proeven uitgevoerd om de

  10. Het geheim van Alibaba

    NARCIS (Netherlands)

    den Butter, F.A.G.; Wu, X.

    2016-01-01

    Alibaba is in korte tijd uitgegroeid tot het grootste internet handelsplatform in de wereld. Volgens de Amsterdamse hoogleraar Frank den Butter en de Chinese studente Xiaoyi Wu weet Alibaba uitstekend in te spelen op de Chinese cultuur en instituties bij het omlaag brengen van de kosten van

  11. Voorkomen van blessures

    NARCIS (Netherlands)

    Weelink, G.

    2014-01-01

    André Dias werkt inmiddels zes jaar als fysiotherapeut bij Benfica. Bij de club uit Lissabon is hij een van de vijf fysiotherapeuten die fulltime op het jeugdcomplex van ‘As Aguias’ (De Adelaars) werken. Dias zelf is nauw betrokken bij het team voor spelers onder 19 jaar. Bij die leeftijdscategorie

  12. Moontlike oorsake van werkskuheid

    Directory of Open Access Journals (Sweden)

    G. v. d. M. Sieberhagen

    1992-06-01

    Full Text Available Possible causes of work-shyness. From a literature survey possible contributing factors to work-shyness are extracted. Hypotheses as to how the work-shy differs from the working person regarding these factors are then formulated and tested empirically. Results indicate that the work-shy differs significantly from the working individual in terms of childhood and work experiences. Opsomming Aan die hand van 'n literatuurstudie word 'n beeld opgebou van en hipoteses ontwikkel oor die moontlike oorsake van werkskuheid deur te verwys na ondervindings waaraan werkskuwes blootgestel word. Hierdie ondervindings word dan empirics vergelyk met die van die normaalwerkende persoon. Die resultate toon aan dat Suid-Afrikaanse werkskuwes beduidend van normaal-werkende persone verskil wat betref kinderjare- en werksondervindings.

  13. Privacy-aspecten van het Internet berichtenverkeer

    NARCIS (Netherlands)

    Nouwt, J.

    2000-01-01

    In opdracht van ITeR, het Nationaal Programma Informatietechnologie en Recht, onderzocht Sjaak Nouwt de stand van zaken rond de toepassing van privacyregels op Internetberichten. Dit artikel bevat een kort verslag van de resultaten van het onderzoek.

  14. Satellite Anomalies: Benefits of a Centralized Anomaly Database and Methods for Securely Sharing Information Among Satellite Operators

    Science.gov (United States)

    2014-01-01

    electrons are concentrated in the inner and outer electron 14 Satellite Anomalies Satellite Anomalies 15 Van Allen belts , making high LEO orbits and...Inside the magnetosphere, high-energy charged particles are con- centrated in the Van Allen radiation belts , which extend from ~1,500 km altitude out...Earth’s magnetosphere, with several regions labeled where satellite anomalies often occur, including the Van Allen Radiation Belts (Inner and Outer

  15. Prozaci asemel GTD ehk getting things done / David Allen ; interv. Endrik Randoja

    Index Scriptorium Estoniae

    Allen, David

    2007-01-01

    Konsultant ja koolitaja David Allen oma aja- ja enesejuhtimise meetodist GTD - getting things done. Vt. samas: Väikesed nipid, et tõhusam olla; Milles seisneb Alleni meetod; Kuidas ma oma ülesannet täitsin - logiraamat

  16. Miks meil on kogu aeg kiire? / David Allen ; interv. Endrik Randoja

    Index Scriptorium Estoniae

    Allen, David

    2006-01-01

    Produktiivsuse ekspert vastab küsimustele ettevõetud tegevuste tulemuslikumalt lõpule viimise kohta. Lisa: Aja paremaks kasutamiseks pakub David Allen lisaks veel kolm tõhusat ja lihtsasti rakendatavat põhimõtet

  17. Active and passive microwave measurements in Hurricane Allen

    Science.gov (United States)

    Delnore, V. E.; Bahn, G. S.; Grantham, W. L.; Harrington, R. F.; Jones, W. L.

    1985-01-01

    The NASA Langley Research Center analysis of the airborne microwave remote sensing measurements of Hurricane Allen obtained on August 5 and 8, 1980 is summarized. The instruments were the C-band stepped frequency microwave radiometer and the Ku-band airborne microwave scatterometer. They were carried aboard a NOAA aircraft making storm penetrations at an altitude of 3000 m and are sensitive to rain rate, surface wind speed, and surface wind vector. The wind speed is calculated from the increase in antenna brightness temperature above the estimated calm sea value. The rain rate is obtained from the difference between antenna temperature increases measured at two frequencies, and wind vector is determined from the sea surface normalized radar cross section measured at several azimuths. Comparison wind data were provided from the inertial navigation systems aboard both the C-130 aircraft at 3000 m and a second NOAA aircraft (a P-3) operating between 500 and 1500 m. Comparison rain rate data were obtained with a rain radar aboard the P-3. Evaluation of the surface winds obtained with the two microwave instruments was limited to comparisons with each other and with the flight level winds. Two important conclusions are drawn from these comparisons: (1) the radiometer is accurate when predicting flight level wind speeds and rain; and (2) the scatterometer produces well behaved and consistent wind vectors for the rain free periods.

  18. Mathematics Intervention Supporting Allen, a Latino EL: A Case Study

    Directory of Open Access Journals (Sweden)

    Marialuisa Di Stefano

    2017-05-01

    Full Text Available This research discusses a single case study of a first-grade Latino English Learner (EL student, Allen (pseudonym, from a larger inquiry-based intervention on inversion and mental reversibility development. The purpose of this case study was to develop a better understanding of the relationship between Allen’s English language proficiency and his ability to solve inversion and compensation mathematics tasks. The integration of multiple paradigms confronting radical constructivism and sociocultural theory of learning via culturally relevant pedagogy provided us with a multi-faceted set of perspectives in understanding the interconnection between Allen’s cultural and linguistic background and his development of algebraic reasoning. Through conceptual and retrospective analyses, we found that Allen’s language features are highly correlated with the development of his thinking strategies and his ability to solve mathematics tasks. Implications of this study include the development of teaching strategies that address critical issues in mathematics, such as the individual differences of learners, specifically ELs from Latino background. We suggest further research is needed in the field of language acquisition and access to STEM related concepts.

  19. SETI OBSERVATIONS OF EXOPLANETS WITH THE ALLEN TELESCOPE ARRAY

    Energy Technology Data Exchange (ETDEWEB)

    Harp, G. R.; Richards, Jon; Tarter, Jill C.; Dreher, John; Jordan, Jane; Shostak, Seth; Smolek, Ken; Kilsdonk, Tom; Wilcox, Bethany R.; Wimberly, M. K. R.; Ross, John; Barott, W. C.; Ackermann, R. F.; Blair, Samantha [SETI Institute, Mountain View, CA 94043 (United States)

    2016-12-01

    We report radio SETI observations on a large number of known exoplanets and other nearby star systems using the Allen Telescope Array (ATA). Observations were made over about 19000 hr from 2009 May to 2015 December. This search focused on narrowband radio signals from a set totaling 9293 stars, including 2015 exoplanet stars and Kepler objects of interest and an additional 65 whose planets may be close to their habitable zones. The ATA observations were made using multiple synthesized beams and an anticoincidence filter to help identify terrestrial radio interference. Stars were observed over frequencies from 1 to 9 GHz in multiple bands that avoid strong terrestrial communication frequencies. Data were processed in near-real time for narrowband (0.7–100 Hz) continuous and pulsed signals with transmitter/receiver relative accelerations from −0.3 to 0.3 m s{sup −2}. A total of 1.9 × 10{sup 8} unique signals requiring immediate follow-up were detected in observations covering more than 8 × 10{sup 6} star-MHz. We detected no persistent signals from extraterrestrial technology exceeding our frequency-dependent sensitivity threshold of 180–310 × 10{sup −26} W m{sup −2}.

  20. Toward an integrated route to the vernonia allenes and related sesquiterpenoids

    Directory of Open Access Journals (Sweden)

    Da Xu

    2011-07-01

    Full Text Available The synthesis of a model endocyclic allene related to the vernonia allenes is described. Fragmentation of a suitable decalin derivative gave the simplified germacrane scaffold. Computational analysis of this and related substrates provides insight into the stereoelectronic requirements of C–C fragmentation. The overall strategy to access these and other sesquiterpenes and the key steps in the present sequence are also discussed.

  1. ʼn Kritiese evaluering van wetgewing wat die gesondheid van ...

    African Journals Online (AJOL)

    User

    regte ingevolge die Menseregtehandves, die maatstaf van die beste belang van die. 74. Artikel 2(d) en (i) Kinderwet 38 van 2005. 75. Hierdie artikel sluit nie 'n bespreking van kindermishandeling en verwaarlosing in nie. 76. Sloth-Nielsen 2003 ESR Rev 2. 77. Skelton en Proudlock "Interpretation, Objects, Application and ...

  2. Analyse van handhavingsrisico's : Het opzetten van een systematiek

    NARCIS (Netherlands)

    Bouwman, E.C.J.

    1999-01-01

    Dit onderzoek heeft betrekking op de mogelijkheid om op structurele wijze de fraudegevoeligheid voor nieuwe regelgeving te bepalen. Dit onderzoek is verricht aan de hand van twee cases, te weten:bouw- en sloopafval, regelgeving van het ministerie van VROM;gecontaineriseerd vervoer van verpakte

  3. De ontwikkeling van onderwijsopvattingen van lio’s

    NARCIS (Netherlands)

    de Vries, Siebrich; Jansen, Ellen

    2015-01-01

    In deze studie staat de vraag centraal of en hoe onderwijsopvattingen van lio’s zich ontwikkelen, en of er een verband is met al dan niet in het beroep gaan. Het 2012-cohort lio’s (N = 118 ) van de lerarenopleiding van de RUG is anderhalf jaar gevolgd bij de ontwikkeling van hun

  4. Karakterisering van het Etimologie- woordeboek van Afrikaans (EWA)

    African Journals Online (AJOL)

    rbr

    Samenvatting: Zesendertig jaar na Afrikaanse etimologieë van Boshoff en Nienaber verscheen er in 2003 een nieuw etymologisch woordenboek van het Afrikaans: het Etimologiewoordeboek van. Afrikaans (EWA). Tussen die twee woordenboeken bestaat een wezenlijk verschil. Het werk van. Boshoff en Nienaber is ...

  5. Die ontwikkeling van menslike potensiaal in die Republiek van Suid ...

    African Journals Online (AJOL)

    Erna Kinsey

    :93). Die “Poverty Index Report” van die huidige rege- ring dui aan dat nagenoeg 50% van alle Suid-Afrikaners in armoede leef. Meer as 70% van alle armes word in die plattelandse gebiede aangetref en 61% van alle swartes is armes (Paton ...

  6. Lewenskwaliteit te midde van 'n erge stressor: 'n studie van ...

    African Journals Online (AJOL)

    Die rol van hulle persepsie van lewensgebeure as verstaanbaar, beheerbaar en betekenisvol, die drie elemente van Antonovsky se Koherensiesin, is toegelig. Volgens die ondersoek het ๋n sosiale ondersteuningsnetwerk en ๋n spirituele geloofsisteem ook betekenisvol bygedra tot die handhawing van hulle lewenskwaliteit ...

  7. Hogere verwachtingen van technologie dan van elkaar?

    NARCIS (Netherlands)

    Dr. Stijn Verhagen

    2012-01-01

    Boekbespeking van Sherrie Turkle, 2011, Alone Together: Why We Expect More from Technology and Less from Each Other. New York: Basic Books. Mails, sms’jes, instant messages, tweets, Skype, voicemails, Facebookberichten – via smartphones en andere apparaten zijn we vrijwel non-stop in contact met

  8. Didactische ICT bekwaamheid van docenten

    NARCIS (Netherlands)

    Voogt, Joke; Heitink, Maaike Christine; Fisser, Petra; van Braak, Johan; Verplanken, Liesbet; Walraven, Amber

    2013-01-01

    Met de snelle ontwikkeling in het gebruik van informatie en communicatie technologie (ICT) in onze samenleving kan het onderwijs het gebruik van ICT niet meer negeren. Leerlingen moeten worden voorbereid op een samenleving waarin het gebruik van ICT-toepassingen deel van het dagelijks leven zijn.

  9. Microbewerking met behulp van lasers

    NARCIS (Netherlands)

    Ezendam, M.M.M.

    1994-01-01

    Het bewerken van materialen met behulp van lasers staat momenteel enorm in de belangstelling, en terecht. De ontwikkeling van bestaande en nieuwe typen lasers staat alles behalve stil. Ontwikkelingen bevinden zich met name in het gebied van hogere vermogens, betere bundelkwaliteit en hogere

  10. Ingredienten voor kwaliteitsborging van modelonderzoek

    NARCIS (Netherlands)

    Grinsven JJM van; Haan BJ de; Braat LC; MNV; LBG; CIM

    1995-01-01

    In dit rapport wordt een aanzet gepresenteerd tot harmonisatie van de kwaliteitsborging van modelonderzoek in het RIVM. Het rapport komt voort uit initiatieven van leden van het Intersectoraal Modellen Overleg. Het rapport is in eerste instantie bedoeld voor onderzoekers die modellen

  11. Burnout : de stand van zaken

    NARCIS (Netherlands)

    Taris, T.; Houtman, I.L.D.; Schaufeli, W.

    2013-01-01

    Dit artikel geeft een overzicht van de stand van zaken in het onderzoek naar burnout. Burnout is een syndroom van extreme vermoeidheid (uitputting), afstand nemen van het werk (distantie) en weinig vertrouwen in het eigen kunnen (verminderde competentie), waarbij de oorzaken voor deze aspecten

  12. Formation and decay of the inner electron radiation belt

    Science.gov (United States)

    Su, Y. J.; Selesnick, R.

    2016-12-01

    The inner electron radiation belt was found, early in the space age, to be highly variable with rapid injections followed by slower decay. Highly structured energy spectra were also observed (now known in energy-time spectrograms as "zebra stripes"). Inner belt formation was explained by inward diffusion. However, even the fastest diffusion is expected to require a period of many days, while observations show frequent rapid injections across the entire inner belt (as low as L=1.2) during periods of belt. In this presentation, we will explain the rapid injections, slow decay, and structured energy spectra, as observed from Van Allen Probes for electrons with energies of 100-400 keV, by the action of large-scale electric fields. In addition, a case study of a non-diffusive fast injection event that occurred on March 17, 2013, is simulated by a test particle code which demonstrates the sensitivity of electron intensity to the selected electric field model.

  13. The Radiation Belt Storm Probes (RBSP): Using A Fundamental Physics Mission to Support Practical Applications

    Science.gov (United States)

    Fox, N. J.; Mauk, B. H.; Weiss, M.; Barnes, R. J.; Kessel, R.; Sibeck, D. G.

    2010-12-01

    This presentation provides an overview of the Living With a Star (LWS) Radiation Belt Storm Probes (RBSP) mission and its planned contributions to space weather activities. The RBSP mission targets Earth’s space radiation belts that comprise multiple components of high energy, penetrating charged particles. These belts are hazardous to spacecraft and astronauts alike and are controlled by dynamic processes that govern particle radiation mechanisms occurring throughout the universe. The two RBSP spacecraft will make measurements in low-inclination, elliptical, lapping orbits around the Earth to quantify mechanisms for energetic particle acceleration, transport, and loss in space environments. The RBSP instrument investigations provide the measurements needed to characterize and quantify the processes that supply and remove energetic particles from the Earth's Van Allen radiation belts. The radiation belts are now part of our technology infrastructure, and if we can understand them, we can improve our mission planning, spacecraft operation and system design, and replace average or worst case design assumptions by actual values of solar cycle radiation. Space weather forecasting ideally requires specification and prediction of impacts on satellite operations. The RBSP spacecraft will characterize the space environment and also provide satellite state of health data, thereby providing a great opportunity to study the spacecraft interaction with the local space environment. In addition to the space weather modeling efforts, the RBSP mission will provide real-time support for the user community. The spacecraft will broadcast real-time space weather data which will be used for monitoring and analyzing current environmental conditions, anomaly resolution and to forecast natural environmental changes.

  14. Van de Graaff Irradiation of Materials

    Energy Technology Data Exchange (ETDEWEB)

    Quigley, Kevin [Argonne National Lab. (ANL), Argonne, IL (United States); Chemerisov, Sergey [Argonne National Lab. (ANL), Argonne, IL (United States); Tkac, Peter [Argonne National Lab. (ANL), Argonne, IL (United States); Vandegrift, George F. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-10-01

    Through irradiations using our 3 MeV Van de Graaf accelerator, Argonne is testing the radiation stability of components of equipment that are being used to dispense molybdenum solutions for use as feeds to 99mTc generators and in the 99mTc generators themselves. Components have been irradiated by both a direct electron beam and photons generated from a tungsten convertor.

  15. Mathematics and Humor: John Allen Paulos and the Numeracy Crusade

    Directory of Open Access Journals (Sweden)

    Paul H. Grawe

    2015-07-01

    Full Text Available John Allen Paulos at minimum gave the Numeracy movement a name through his book Innumeracy: Mathematical Illiteracy and Its Consequences. What may not be so obvious was Paulos’ strong interest in the relationship between mathematics and mathematicians on the one hand and humor and stand-up-comedian joke structures on the other. Innumeracy itself could be seen as a typically mathematical Gotcha joke on American culture generally. In this perspective, a Minnesotan acculturated to Minnesota-Nice Humor of Self-Immolation Proclivities (SImP looks at the more raw-boned, take-no-prisoners humor style Paulos outlined in Mathematics and Humor and implemented in Innumeracy. Despite the difference in humor styles, there is much to applaud in Paulos’ analysis of the relationship between certain types of humor and professional interests of mathematicians in Mathematics and Humor. Much humor relies on the sense of incongruity which Paulos’ claims to be central to all humor and key to mathematical reductio ad absurdum. Mathematics is rightfully famous for a sense of combinatorial playfulness in its most elegant proofs, as humor often relies on clashing combinations of word play. And a great range of mathematical lore is best understood within a concept of a sudden drop from one sense of certainty to another (essentially a Gotcha on the audience. Innumeracy repeatedly exemplifies Gotchas on the great unwashed and unmathematical majority. Extensive empirical evidence over the last quarter century allows us to synthesize these Paulos observations into the idea that inculcated mathematical humor has strong propensities to complex Intellectual, Advocate, and Crusader humor forms. However, the Paulos humors do not include the Sympathetic Pain humor form, the inclusion of which may increase teaching effectiveness.

  16. Notitie Bemestingswaarde van digestaten

    NARCIS (Netherlands)

    Schroder, J.J.

    2016-01-01

    ‘Digestaat’ is een algemene benaming voor meststoffen afkomstig uit vergistingsinstallaties. Teneinde de biogasproductie te vergroten, kunnen, naast dierlijke mest, koolstofrijke producten worden toegevoegd. Omdat de samenstelling en afbreekbaarheid van die toegevoegde co-producten betekenisvol

  17. Van storytelling naar storyconversation

    NARCIS (Netherlands)

    René Boonstra

    2014-01-01

    De toepassing van storytelling als communicatie instrument heeft de laatste jaren een sterke ontwikkeling doorgemaakt bij corporate identity vraagstukken. Een verhaal is een verhaal. Daarover bestaat wereldwijd geen twijfel. Structuur, opbouw en narratieve elementen zijn altijd te herkennen. Of het

  18. Effectief leren van multimedia

    NARCIS (Netherlands)

    Kester, Liesbeth

    2013-01-01

    Kester, L. (2012, March). Effectief leren van multimedia [Effective learning from multimedia]. Keynote presented at a miniconference Learning Sciences of the Open University of the Netherlands, Eindhoven, the Netherlands.

  19. Die Institusie van Calvyn.

    Directory of Open Access Journals (Sweden)

    J. C. Coetzee

    1951-03-01

    Full Text Available Ek wil hier geen verhandeling oor Calvyn se onderwysing in die Christelike godsdiens skrywe nie maar net die aandag vestig op die feit dat hierdie werk van Calvyn nou ook in Afrikaans verkrygbaar is.

  20. De ontdekking van Antarctica

    NARCIS (Netherlands)

    Beintema, A.J.

    2004-01-01

    Aristoteles bedacht de naam Antarctica, maar wie ontdekte het zevende continent? Dit eerste artikel binnen het thema Antarctica beantwoordt die vraag. Ontdekkingsreizigers als Cook, Biscoe, Amundsen en Scott komen ter sprake, naast het kartografisch werk van Finnaeus

  1. Beheersing van Sclerotinia

    NARCIS (Netherlands)

    Janmaat, L.; Hamont, van J.; Lamers, J.G.

    2010-01-01

    Sclerotinia (rattenkeutelziekte) wordt veroorzaakt door de schimmel Sclerotinia sclerotiorum. Deze komt voor op zeer veel gewassen en overleeft lang in de bodem. Onder veelal vochtige omstandigheden na droogte ontstaan vruchtlichamen (paddestoelen) van waaruit sporen zich verspreiden. Ze infecteren

  2. Ondersteuning van mobiele hulpverleners

    NARCIS (Netherlands)

    Huis in 't Veld, M.M.A.; Streefkerk, J.W.

    2007-01-01

    TNO onderzoekt hoe mobiele hulpverleners beter ondersteund kunnen worden. Wat is de visie van TNO? Twee praktijkvoorbeelden geven inzicht. In het project "Decision Support Tools" zijn twee typen beslisondersteuningsconcepten ontwikkeld en getest, een Simulatie tool (CFSim) en een Critical Thinking

  3. Een vergelijking van de voorjaarstrek van drie populaties Brandganzen met behulp van GPS-satellietzenders

    NARCIS (Netherlands)

    De Boer, R.; Bauer, Silke; Van der Jeugd, Henk; Ens, B.J.; Griffin, L.; Cabot, D.; Exo, K-M.; Nolet, Bart A.; Kölzsch, Andrea

    2014-01-01

    Onderzoek naar trekvogels heeft een grote vlucht genomen sinds de introductie van draagbare apparatuur met ingebouwde GPS-ontvangers, omdat we hiermee de trek van individuele vogels in groot detail kunnen volgen. In dit artikel brengen we met behulp van GPS-satellietzenders de voorjaarstrek van drie

  4. Ecologische kenmerken van weidevogeljongen en de invloed van beheer op overleving. Kennisoverzicht en effectiviteit van maatregelen

    OpenAIRE

    Oosterveld, E.B.; Kleijn, D.; Schekkerman, H.

    2008-01-01

    Rapport over de effectiviteit van beheersmaatregelen voor overleving van primaire weidevogelkuikens in graslanden, op basis van wetenschappelijke en niet-wetenschappelijke literatuur. Per sprake komen: Ecoprofielen weidevogeljongen van: Kievit (Vanellus vanellus); Grutto (Limosa limosa); Tureluur (Tringa totanus); Scholekster (Haematopus ostralegus); Watersnip (Gallinago gallinago); Kemphaan (Philomachus pugnax); Slobeend (Anas clypeata); Zomertaling (Anas querquedula); Kuifeend (Aythya fulig...

  5. Het effect van het calciumgehalte van pootgoed opm de groei en opbrengst van zetmeelaardappelen

    NARCIS (Netherlands)

    Velema, R.; Griend, van de P.; Velvis, H.

    2001-01-01

    In het kader van het deelproject ‘Nutriëntenvoorziening’ van de deelcluster ‘Innovatie Aardappelteelt’ van Agrobiokon is door HLB onderzoek uitgevoerd naar de calciumvoorziening in pootaardappelen. In het onderzoek dat in dit rapport wordt beschreven, is gekeken naar het effect van het

  6. Van implementering tot verwesentliking: Aanwending van resultate van internasionaal vergelykende studies

    Directory of Open Access Journals (Sweden)

    Surette van Staden

    2016-02-01

    Full Text Available Die prestasies van Suid-Afrikaanse leerders in internasionaal vergelykende studies bly voortdurend swak, wat vrae laat ontstaan oor die kwaliteit van onderwys wat aan SuidAfrikaanse kinders gebied word in die verskillende grade en fases van formele skoolonderrig. Ernstige kommer oor leerders se swak prestasies oorheers navorsing en opvoedkundige debatte in Suid-Afrika. Ondanks goeie oogmerke, soos die hersiening van beleid en leerplanne, en die fokus op implementering, deur middel van kurrikulêre voorsiening en ondersteuning aan onderwysers, bly die verwesentliking in terme van leerders se prestasie teleurstellend swak. Hierdie studie ondersoek data verkry uit die preProgress in International Reading Literacy Study (prePIRLS van 2011. Die prestasie van Suid-Afrikaanse Graad 4-leerders is op ’n punt van 461 bereken, wat beduidend laer is as die internasionale gemiddeld van 500 (SE = 3.7. Resultate van die prePIRLS 2011-studie word gebruik as bewys van die bereiking van kurrikulêre doelwitte op die Graad 4-vlak, oor die spektrum van 11 Suid-Afrikaanse landstale. Norme of maatstawwe, soos afgelei uit die resultate, word verder ondersoek om moontlike verbeteringe aan te wys in die implementering van leerplanne in die klaskamer. Gevolgtrekkings sluit voorstelle in oor hoe onderwyspraktyk voordeel kan trek uit die bevindings van internasionaal vergelykende studies.

  7. Berekening van de relatieve dichtheid van de grond ten behoeve van het sportveldenonderzoek

    NARCIS (Netherlands)

    Zwiers, J.S.

    1976-01-01

    Bij de bespeelbaarheid van de sportvelden speelt de stevigheid van de toplaag een belangrijke rol. De stevigheid is van verschillende factoren afhankelijk, zoals het organische-stofgehalte, het slibgehalte, de ontwateringstoestand, de regenval, de grasmat, het bodemleven en mogelijk de dichtheid van

  8. De trek van kruiden van volgroeid wortelmateriaal : handleiding van A tot Z in beknopte vorm

    NARCIS (Netherlands)

    Wijk, van C.A.P.

    2005-01-01

    Deze teelthandleiding richt zich op de trek van vooral dragon, krulpeterselie, rucola en munt, uitgaande van wortelmateriaal dat in de vollegrond wordt geteeld. Deze forcering richt zich zowel op aanbod van kruiden in potjes als de meermalige oogst van het gesneden product in een kas of een

  9. Ellis Van Creveld syndrome

    Directory of Open Access Journals (Sweden)

    Shilpy S

    2007-05-01

    Full Text Available Ellis Van Creveld syndrome is a rare disorder and is a form of short-limbed dwarfism. It is an autosomal recessive disorder characterized by tetrad of disproportionate dwarfism, post-axial polydactyly, ectodermal dysplasia and heart defects. This case report presents a classical case of a seven-year-old boy with Ellis Van Creveld syndrome presented with discrete clinical findings.

  10. Space Van system update

    Science.gov (United States)

    Cormier, Len

    1992-07-01

    The Space Van is a proposed commercial launch vehicle that is designed to carry 1150 kg to a space-station orbit for a price of $1,900,000 per flight in 1992 dollars. This price includes return on preoperational investment. Recurring costs are expected to be about $840,000 per flight. The Space Van is a fully reusable, assisted-single-stage-to orbit system. The most innovative new feature of the Space Van system is the assist-stage concept. The assist stage uses only airbreathing engines for vertical takeoff and vertical landing in the horizontal attitude and for launching the rocket-powered orbiter stage at mach 0.8 and an altitude of about 12 km. The primary version of the orbiter is designed for cargo-only without a crew. However, a passenger version of the Space Van should be able to carry a crew of two plus six passengers to a space-station orbit. Since the Space Van is nearly single-stage, performance to polar orbit drops off significantly. The cargo version should be capable of carrying 350 kg to a 400-km polar orbit. In the passenger version, the Space Van should be able to carry two crew members - or one crew member plus a passenger.

  11. Highly relativistic radiation belt electron acceleration, transport, and loss: Large solar storm events of March and June 2015.

    Science.gov (United States)

    Baker, D N; Jaynes, A N; Kanekal, S G; Foster, J C; Erickson, P J; Fennell, J F; Blake, J B; Zhao, H; Li, X; Elkington, S R; Henderson, M G; Reeves, G D; Spence, H E; Kletzing, C A; Wygant, J R

    2016-07-01

    Two of the largest geomagnetic storms of the last decade were witnessed in 2015. On 17 March 2015, a coronal mass ejection-driven event occurred with a Dst (storm time ring current index) value reaching -223 nT. On 22 June 2015 another strong storm ( Dst reaching -204 nT) was recorded. These two storms each produced almost total loss of radiation belt high-energy ( E  ≳ 1 MeV) electron fluxes. Following the dropouts of radiation belt fluxes there were complex and rather remarkable recoveries of the electrons extending up to nearly 10 MeV in kinetic energy. The energized outer zone electrons showed a rich variety of pitch angle features including strong "butterfly" distributions with deep minima in flux at α  = 90°. However, despite strong driving of outer zone earthward radial diffusion in these storms, the previously reported "impenetrable barrier" at L  ≈ 2.8 was pushed inward, but not significantly breached, and no E  ≳ 2.0 MeV electrons were seen to pass through the radiation belt slot region to reach the inner Van Allen zone. Overall, these intense storms show a wealth of novel features of acceleration, transport, and loss that are demonstrated in the present detailed analysis.

  12. Effects of ULF wave power on relativistic radiation belt electrons: 8-9 October 2012 geomagnetic storm

    Science.gov (United States)

    Pokhotelov, D.; Rae, I. J.; Murphy, K. R.; Mann, I. R.

    2016-12-01

    Electromagnetic ultralow-frequency (ULF) waves are known to play a substantial role in radial transport, acceleration, and loss of relativistic particles trapped in the Earth's outer radiation belt. Using in situ observations by multiple spacecraft operating in the vicinity of outer radiation belts, we analyze the temporal and spatial behavior of ULF waves throughout the geomagnetic storm of 8-9 October 2012 and compare with the dynamics of relativistic electron fluxes on board the twin Van Allen Probes spacecraft. The analysis shows that the relativistic electron fluxes reduce from their prestorm levels during the first phase of the storm and rapidly increase during the second phase of the storm. We demonstrate that the behavior of ULF wave power changes throughout the storm, from ULF oscillations being a mixture of compressional and shear magnetic components during the first phase of the storm to ULF oscillations being dominated by transverse (shear) components during the second phase. We analyze the parameters of ULF-driven radial diffusion throughout the storm and compare the observed diffusion coefficients with their statistical averages. We demonstrate that the observed diffusion coefficients are strong enough to impact the redistribution of relativistic electron fluxes from and to the outer boundary of radiation belts and the diffusion might influence the effects of any local electron acceleration by transporting fluxes inward or outward according to phase space density gradients.

  13. Highly Relativistic Radiation Belt Electron Acceleration, Transport, and Loss: Large Solar Storm Events of March and June 2015

    Science.gov (United States)

    Baker, D. N.; Jaynes, A. N.; Kanekal, S. G.; Foster, J.C.; Erickson, P. J.; Fennell, Joseph; Blake, J. B.; Zhao, H.; Li, X.; Elkington, S. R.; hide

    2016-01-01

    Two of the largest geomagnetic storms of the last decade were witnessed in 2015. On 17 March 2015, a coronal mass ejection-driven event occurred with a Dst (Disturbance Storm Time Ring Current Index) value reaching 223 nanoteslas. On 22 June 2015 another strong storm (Dst reaching 204 nanoteslas) was recorded. These two storms each produced almost total loss of radiation belt high-energy (E (Energy) greater than or approximately equal to 1 millielectronvolt) electron fluxes. Following the dropouts of radiation belt fluxes there were complex and rather remarkable recoveries of the electrons extending up to nearly 10 millielectronvolts in kinetic energy. The energized outer zone electrons showed a rich variety of pitch angle features including strong butterfly distributions with deep minima in flux at alpha equals 90 degrees. However, despite strong driving of outer zone earthward radial diffusion in these storms, the previously reported impenetrable barrier at L (L-shell magnetic field line value) approximately equal to 2.8 was pushed inward, but not significantly breached, and no E (Energy) greater than or approximately equal to 2.0 millielectronvolts electrons were seen to pass through the radiation belt slot region to reach the inner Van Allen zone. Overall, these intense storms show a wealth of novel features of acceleration, transport, and loss that are demonstrated in the present detailed analysis.

  14. Het geheim van de Messias bij Josephus

    Directory of Open Access Journals (Sweden)

    T. Middendorp

    1983-09-01

    Full Text Available Heeft Josephus kennis gehad van de jonge christelijke kerk? Wat wist hij van Jezus van Nazareth? Kan hij als getuige voor de historiciteit van Jezus aangehaald worden? Dit zijn oude vragen. Hier wordt opnieuw een antwoord gezocht-niet op grond van een bepaalde tekst van deze schrijver - maar met behulp van het kader van diens wereldbeschouwing, die in het geheel van zijn oeuvre tot uitdrukking komt.

  15. Plaatsen van beschaafd vertier

    Directory of Open Access Journals (Sweden)

    James Kennedy

    2014-09-01

    Full Text Available Plaatsen van beschaafd vertier [Places of civilised amusement] by Jan Hein Furnée, which appeared as a PhD thesis in 2007 and was adapted and extended into a book in 2012, is regarded by historians of the Low Countries as an impressive tour de force. In a stimulating manner Furnée demonstrates with this profound urban history that for the elite of The Hague leisure activities played an important role in acquiring status and maintaining their position. His study is based on extensive and systematic research into a great variety of sources, from census registers, membership lists of clubs and societies to address books. This gives the reader an extraordinarily detailed picture of the changing social relations in the upper echelons of society in The Hague in the latter half of the nineteenth century. The sophisticated use of both qualitative and quantitative methods can serve as a model for other historians in the field of urban history. In a lively fashion Furnée shows that the inhabitants of The Hague grasped at all kinds of pastimes in order to distinguish themselves from others, and when possible to increase their own status through their participation in elegant societies, theatre visits or supporting the proposed zoo: but the book also makes statements about status and class, the history of gender and of politics at the end of the nineteenth century. Plaatsen van beschaafd vertier van Jan Hein Furnée dat in 2007 als proefschrift en in 2012 bewerkt en uitgebreid als boek verscheen, staat onder historici van de Lage Landen bekend als een imponerende tour de force. Op prikkelende wijze laat Furnée in deze diepgravende stadsgeschiedenis zien dat vrijetijdsbesteding voor Haagse elites een belangrijke rol speelde in standsvorming en handhaving van hun positie. Zijn studie is gebaseerd op uitgebreid en systematisch onderzoek van veelsoortige bronnen, van volkstellingsregisters, ledenlijsten van verenigingen en sociëteiten tot adresboeken

  16. Event-Specific Quantification of Radiation Belt Radial Diffusion

    Science.gov (United States)

    Tu, W.; Sarris, T. E.; Ozeke, L.

    2016-12-01

    Recently, there has been a great emphasis on developing event-specific inputs for radiation belt models, since they are proven critical for reproducing the observed radiation belt dynamics during strong events. For example, our DREAM3D simulation of the 8-9 October 2012 storm demonstrates that event-specific chorus wave model and seed population are critical to reproduce the strong enhancement of MeV electrons in this event. However, the observed fast electron dropout preceding the enhancement was not captured by the simulation, which could be due to the combined effects of fast outward radial diffusion of radiation belt electrons with magnetopause shadowing and enhanced electron precipitation. Without an event-specific quantification of radial diffusion, we cannot resolve the relative contribution of outward radial diffusion and precipitation to the observed electron dropout or realistically reproduce the dynamics during the event. In this work, we provide physical quantification of radial diffusion specific to the October 2012 event by including both real-time and global distributions of ULF waves from a constellation of wave measurements and event-specific estimation of ULF wave mode structure. The global maps of ULF waves during the event are constructed by combining the real-time measurements from the Van Allen Probes, THEMIS, and GOES satellites in space and a large array of ground magnetometers. The real-time ULF wave mode structure is then estimated using the new Cross-Wavelet Transform technique, applied to various azimuthally aligned pairs of ULF wave measurements that are located at the same L shells. The cross power and phase differences between the time series are calculated using the technique, based on which the wave power per mode number is estimated. Finally, the physically estimated radial diffusion coefficients specific to the event are applied to the DREAM3D model to quantify the relative contribution of radial diffusion to the electron dynamics

  17. Different NMR approaches to the chiral analysis of trisubstituted allenes devoid of polar functional groups and aromatic hydrocarbons.

    Science.gov (United States)

    Uccello-Barretta, G; Balzano, F; Salvadori, P; Lazzaroni, R; Caporusso, A M; Menicagli, R

    1996-01-01

    The use of permethylated beta-cyclodextrin as chiral solvating agent for NMR spectroscopy allowed us to determine the enantiomeric purity of chiral aromatic hydrocarbons as well as the enantiomeric purity and absolute configuration of chiral trisubstituted allenes devoid of polar functional groups. The enantiomeric excesses of the trisubstituted allenes have been also determined by 195Pt NMR spectroscopy of the diastereoisomeric trans-dichloro[(S)-alpha-phenylethyl-amine](allene)Pt(II) complexes.

  18. Quantifying Extremely Rapid Flux Enhancements of Radiation Belt Relativistic Electrons Associated With Radial Diffusion

    Science.gov (United States)

    Liu, Si; Yan, Qi; Yang, Chang; Zhou, Qinghua; He, Zhaoguo; He, Yihua; Gao, Zhonglei; Xiao, Fuliang

    2018-02-01

    Previous studies have revealed a typical picture that seed electrons are transported inward under the drive of radial diffusion and then accelerated via chorus to relativistic energies. Here we show a potentially different process during the 2-3 October 2013 storm when Van Allen Probes observed extremely rapid (by about 50 times in 2 h) flux enhancements of relativistic (1.8-3.4 MeV) electrons but without distinct chorus at lower L-shells. Meanwhile, Time History of Events and Macroscale Interactions during Substorms satellites simultaneously measured enhanced chorus and fluxes of energetic (˜100-300 keV) seed electrons at higher L-shells. Numerical calculations show that chorus can efficiently accelerate seed electrons at L ˜ 8.3. Then radial diffusion further increased the phase space density of relativistic electrons throughout the outer radiation belts, with a remarkable agreement with the observation in magnitude and timescale. The current results provide a different physical scenario on the interplay between radial diffusion and local acceleration in outer radiation belt.

  19. Resonant Scattering of Radiation Belt Electrons by Off-Equatorial Magnetosonic Waves

    Science.gov (United States)

    Ni, Binbin; Zou, Zhengyang; Fu, Song; Cao, Xing; Gu, Xudong; Xiang, Zheng

    2018-02-01

    Fast magnetosonic (MS) waves are commonly regarded as electromagnetic waves that are characteristically confined within ±3° of the geomagnetic equator. We report two typical off-equatorial MS events observed by Van Allen Probes, that is, the 8 May 2014 event that occurred at the geomagnetic latitudes of 7.5°-9.2° both inside and outside the plasmasphere with the wave amplitude up to 590 pT and the 9 January 2014 event that occurred at the latitudes of—(15.7°-17.5°) outside the plasmasphere with a smaller amplitude about 81 pT. Detailed test particle simulations quantify the electron resonant scattering rates by the off-equatorial MS waves to find that they can cause the pitch angle scattering and momentum diffusion of radiation belt electrons with equatorial pitch angles belt electron butterfly distributions for a broad energy range from 100 keV to >1 MeV within an hour. Our study clearly demonstrates that the presence of off-equatorial MS waves, in addition to equatorial MS waves, can contribute importantly to the dynamical variations of radiation belt electron fluxes and their pitch angle distribution.

  20. Psigologiese benadering van pastorale arbeid

    Directory of Open Access Journals (Sweden)

    D. J. Strümpfer

    1969-03-01

    Full Text Available In die spreektaal van ons Afrikaanse kerke is ons lief om die bedienaar van die Woord aan te dui as „die predikant”, „die leraar” of „die dominee”. Miskien plaas ons met hierdie semantiese gebruik van terme wat lering en proklamering impliseer, ’n ongelukkige klem op die preekamp. Daarteenoor, het ons semanties miskien iets te leer van die Pinkstersektes wat die benaming „pastoor” verkies, of die Amerikaanse ge­ bruik van die term „the pastor”. Ons is wel lief om te praat van „ons herder en leraar”. Veelal word die herderlike, of pastorale, deel van die taak van die bedienaar van die Woord egter in sy eie gedagtes, asook in die gedagtes van sy gemeentelede, deur die leraarskap op die agtergrond gedwing. Al te dikwels word hy deur gemeentelede beskou as iemand wat op Sondag op die kansel gesien moet word en wat niks met die res van hul lewens te doen het nie. Herstel van die pastoraat sal deel moet wees van die proses om die ontkerstening van die hedendaagse lewe teen te gaan.

  1. Bestrijding van de wortelvlieg door middel van zaadcoating in peen, 2004 : toetsen van insecticiden en entomofage nematoden op de wortelvlieglarve

    NARCIS (Netherlands)

    Putter, de H.; Ester, A.

    2004-01-01

    Effectiviteit van de onderzochte middelen in verschillende doseringen toegepast als zaadcoating tegen aantasting van de peen door de wortelvliegmade in een peenteelt. Daarnaast wordt de effectivieit van een granulaat en toediening van Nemaplus 50 nematoden getoetst.

  2. Die instelling van die doop

    Directory of Open Access Journals (Sweden)

    J. L. Venter

    1989-06-01

    Full Text Available Die eerste plek in die evangeliebeskrywings waar daar van die doop as ’n opdrag van Jesus Christus gepraat word en waar die betekenis die duidelikste uitkristalliseer, staan in Matteus 28 : 16 - 20. Heilshistories gesien, is dit die begin van kerklike inlywing van die wat gehoor het hoedat Jesus sy koninkryk proklameer, die evangelie aanvaar en tot bekering kom. Vir die doel van hierdie artikel word hierdie gedeelte ondersoek om te sien hoe die instelling geskied het, wat die plek en betekenis van die Christelike doop is.

  3. Review of radiation effects on ReRAM devices and technology

    Science.gov (United States)

    Gonzalez-Velo, Yago; Barnaby, Hugh J.; Kozicki, Michael N.

    2017-08-01

    A review of the ionizing radiation effects on resistive random access memory (ReRAM) technology and devices is presented in this article. The review focuses on vertical devices exhibiting bipolar resistance switching, devices that have already exhibited interesting properties and characteristics for memory applications and, in particular, for non-volatile memory applications. Non-volatile memories are important devices for any type of electronic and embedded system, as they are for space applications. In such applications, specific environmental issues related to the existence of cosmic rays and Van Allen radiation belts around the Earth contribute to specific failure mechanisms related to the energy deposition induced by such ionizing radiation. Such effects are important in non-volatile memory as the current leading technology, i.e. flash-based technology, is sensitive to the total ionizing dose (TID) and single-event effects. New technologies such as ReRAM, if competing with or complementing the existing non-volatile area of memories from the point of view of performance, also have to exhibit great reliability for use in radiation environments such as space. This has driven research on the radiation effects of such ReRAM technology, on both the conductive-bridge RAM as well as the valence-change memories, or OxRAM variants of the technology. Initial characterizations of ReRAM technology showed a high degree of resilience to TID, developing researchers’ interest in characterizing such resilience as well as investigating the cause of such behavior. The state of the art of such research is reviewed in this article.

  4. The Living with a Star Radiation Belt Storm Probes Mission and Related Missions of Opportunity

    Science.gov (United States)

    Sibeck, David G.; Mauk, Barry H.; Grebowsky, Joseph M.; Fox, Nicola J.

    2006-01-01

    This presentation provides an overview of the Living With a Star (LWS) Radiation Belt Storm Probes (RBSP) mission in the context of the broader Geospace program. Missions to Geospace offer an opportunity to observe in situ the fundamental processes that operate throughout the solar system and in particular those that generate hazardous space weather effects in the vicinity of Earth. The recently selected investigations on NASA's LWS program's RBSP will provide the measurements needed to characterize and quantify the processes that supply and remove energetic particles from the Earth's Van Allen radiation belts. Instruments on the RBSP spacecraft will observe charged particles that comprise the Earth's radiation belts over the full energy range from 1 eV to more than 10 MeV (including composition), the plasma waves which energize them, the electric fields which transport them, and the magnetic fields which guide their motion. The two-point measurements by the RBSP spacecraft will enable researchers to discriminate between spatial and temporal effects, and therefore between the various proposed mechanisms for particle acceleration and loss. The measurements taken by the RBSP spacecraft will be used in data modeling projects in order to improve the understanding of these fundamental processes and allow better predictions to be made. NASA's LWS program has also recently selected three teams to study concepts for Missions of Opportunity that will augment the RBSP program, by (1) providing an instrument for a Canadian spacecraft in the Earth's radiation belts, (2) quantifying the flux of particles precipitating into the Earth's atmosphere from the Earth's radiation belts, and (3) remotely sensing both spatial and temporal variations in the Earth's ionosphere and thermosphere.

  5. Evaluering van Suid-Afrikaanse protelenbronne: Gebruik van ...

    African Journals Online (AJOL)

    kondensasieprodukte en kruisbindings gevorm het, die kleur- bindingswaarde sal neig om die basiese aminosuurinhoud te onderskat. Benewens die invloed van die bogenoemde reaksieprodukte op die kleurbindingskapasiteit, bestaan die moontlikheid dat die verhouding van die basiese aminosure by Kaapse- en.

  6. Kwantitatieve massaspectrometrie van Clenbuterol met behulp van isotoopverdunning

    NARCIS (Netherlands)

    Traag, W.A.; Bennekom, van E.O.; Weseman, J.M.; Kienhuis, P.G.M.; Tuinstra, L.G.M.Th.

    1989-01-01

    Om de toepassing van massaspectrometrie met behulp van isotoopverdunning in urine, vlees en lever te onderzoeken is een aantal experimenten uitgevoerd met de 'Hewlett-Packard Hass Selective Detector' (Electron Impact). Ook zijn met Finnigan 4500 aanvullende experimenten (Chemical Ionisation)

  7. Erythropoietine : enkele aspecten van de humorale regulatie van de erythropoiese

    NARCIS (Netherlands)

    G. Wagemaker (Gerard)

    1976-01-01

    textabstractDe regulatie van de erythropoiese verloopt in belangrijke mate via een humorale regulator. Deze wordt erythropoietine genoemd, en heeft een specifieke stimulerende werking op de erythropoiese, waarschiinliik in hoofdzaak door de inductie van erythroide differentiatie in een

  8. Prestatiekenmerken van de bepaling van formaldehyde en 8-hydroxychinolinesulfaat

    NARCIS (Netherlands)

    Cleven RFMJ; Graaf M de; LAC

    1996-01-01

    Een aantal prestatiekenmerken voor de bepaling van een tweetal componenten waarvan de gehaltes regelmatig worden bepaald in voornamelijk sera en vaccins, is nader vastgelegd. Het betreft juistheid, precisie en nauwkeurigheid, de lineariteit van de kalibratiecurven, aantoonbaarheidsgrens, en

  9. Aspekte van die ververing, morfologie en anatomie van kransduivve

    Directory of Open Access Journals (Sweden)

    A. C. Kok

    1989-03-01

    Full Text Available Ondersoek is ingestel na aspekte van die morfologie en anatomie van kransduiwe (Columba guinea in Suider-Afrika. Ververing geskied klaarblyklik dxvarsdeur die jaar teen n lae intensiteit. Duidelike ververingspieke kon slegs hy die primere en sekondêre slagvere en stertvere van mannetjies onderskei word. By wyfies vind die ververingsproses op 'n onreëlmatiger wyse plaas. Afgesien van die snawelafmetings is alle standaardliggaamsafmetings van volwasse mannetjies betekenisvol groter as die van wyfies. Die teenoorgestelde neiging kom by onvolwassenes voor. Seisoensvariasie in lewer- en liggaamsmassa asook die sigbare vetinhoud van volwasse indiwidue Iwu waarskynlik met broeiaktiwiteite en die beskikbaarheid van seisoenaaloorvloedige voedselbronne verband. In vergelyking met die ander gemonsterde bevolkings is beduidende verskille in liggaamsmassa en vetinhoud vir die kransduiwe vanaf Suidwes-Afrika waargeneem.

  10. n Analise van die gemeente as deel van hierdie proses

    African Journals Online (AJOL)

    reer dat hy daardeur, na die beste van sy vermoë, die heil van God kan oordra. In 'n poging om dit te kan doen, vind die bediening van die kerk binne 'n bepaalde struk- tuur, genoem die bedieningstruktuur, plaas. 'n Vraag wat oor 'n wye spektrum gevra word, is die vraag in waiter mate die kerk nog kerk volgens die wil van ...

  11. De distributiestructuur van varkens in Nederland

    NARCIS (Netherlands)

    Driel, van J.A.

    1988-01-01

    Onderzoek naar de structuur van de afzet van levende varkens en biggen op basis van enquetes onder ruim 1000 varkenshouders en 150 veehandelaren. Het rapport beschrijft de situatie in 1986 en vergelijkt deze met die van 1973

  12. Biologische landbouw en mestwetgeving : Inventarisatie van knelpunten

    NARCIS (Netherlands)

    Boer, M.

    2000-01-01

    Om na te gaan in hoeverre biologische boeren onder de huidige omstandigheden hinder ondervinden van nationale en Europese mestwetgeving is op verzoek van de Federatie van Biologische Boeren en het Platform Biologica bij de Wetenschapswinkel van Wageningen Universiteit een onderzoeksvoorstel

  13. Voorspeense groei van Bonsmarakalwers onder verskillende agro ...

    African Journals Online (AJOL)

    Tabel 1) dui op die belang van rekordhouding ten opsigte van ... in die lig van die matig ho€ erfbaarheid van geboortemassa (Preston & Willis,. 1970). Lentekalwers was betekenisvol (P<0,05) swaarder by geboorte as winterkalwers (Tabel 1).

  14. Big data en handschriften van Christiaan Huygens

    NARCIS (Netherlands)

    Damen, J.C.M.

    2013-01-01

    In de achtste aflevering van een serie combinatiebesprekingen (digitaalandspeciaal) schenkt Jos Damen aandacht aan een onderzoek naar big data van bibliotheekcatalogi en een catalogus van het werk van het Nederlandse genie Christiaan Huygens.

  15. Exsodus van die Boerevolk

    Directory of Open Access Journals (Sweden)

    A. J. H. van der Walt

    1938-03-01

    Full Text Available Die Groot Trek het in sekere sin begin toe in die begin van die 18e eeu die eerste veeboer-pionier sy gesin, sy huisraad en sy plaasgereedskap op sy kakebeenwaens gelaai het en na sy veepos, voortaan sy leningsplaas, verhuis het. Want alhoewel die Groot Trek nóg logies nóg histories ’n voortsetting van die 18e eeuse trekbeweging is nie, is die eerste sonder die laaste tog ondenkbaar. Die 18e eeuse verspreiding het die geharde Afrikaanse baanbreker gevorm, ’n mens met weinig behoeftes, en met die selfstandigheid en die handigheid om in daardie behoeftes self grotendeels te voorsien uit die betreklik skrale materiaal wat die bodem hom gebied het. Dit het die Afrikaanse binnelandbewoner fisies en psigologies mobiel gemaak en in hierdie mobielmaking lê die noodwendige voorwaarde vir die moontlikheid van die latere groot volksbeweging.

  16. Samenstelling van de vluchtige olie van Origanum vulgare L. ssp. vulgare gedurende de ontwikkeling van de plant

    NARCIS (Netherlands)

    Maarse, Henk

    1971-01-01

    INLEIDING EN DOEL VAN HET ONDERZOEK Vele onderzoekers hebben de laatste jaren de vorming van de verbindingen in vluchtige olien van planten bestudeerd door het bepalen van de verandering in de samenstelling van de vluchtige olie tijdens de groei van de plant. Lemli (68) wees als eerste op de

  17. Gaschromatografisch onderzoek naar de samenstelling van de vluchtige olie van Mentha piperita L. gedurende de ontwikkeling van de plant

    NARCIS (Netherlands)

    Malingré, Theodorus Maria

    1966-01-01

    SAMENVATTING Het doel van het beschreven onderzoek was door middel van gaschromatografie, gecombineerd met andere analysemethoden, de samenstelling van de vluchtige olie van Mentha piperita L. en de veranderingen hierin gedurende de ontwikkeling van de plant, te bepalen en uit de resultaten van het

  18. De betrouwbaarheid van het vagina-uitstrijkje van de rat als middel om de fase van de bronstcyclus te detecteren

    NARCIS (Netherlands)

    van Velsen FL; Loeber JG; Franken MAM; Liefde AD

    1985-01-01

    De betrouwbaarheid van het vagina-uitstrijkje bij de rat als indicator van de fase van de cyclus is onderzocht bij 60 dieren van 250 g. Gedurende 4 achtereenvolgende weken is op de werkdagen een uitstrijkje gemaakt ter beoordeling van de regelmaat van de cyclus. Daarna zijn de dieren geseceerd na

  19. Implementatie van de Surviving Sepsis Campaign bundels : Monitoring van ervaringen

    NARCIS (Netherlands)

    Lilian Vloet; J. Schouten; N. Stevens; A. Rensen; A. Willems; F. Zeegers

    2011-01-01

    Sepsis komt vaak voor in ziekenhuizen. Ernstige sepsis is verantwoordelijk voor 10 - 20% van alle Intensive Care (IC) opnames en is de belangrijkste doodsoorzaak op niet-cardiale IC?s. De gemiddelde mortaliteit van volwassenen met ernstige sepsis op de IC is 33% en van volwassenen met septische

  20. die effek van speenouderdom op die produksievermoe van die sog

    African Journals Online (AJOL)

    lonsequcntty the early weaned sows produced significantly more piglets per annum (22,5 vs 20,1). OPSOMIIiING: Die effek van speenouderdom, toegepas vir die eerste vyf agtereenvolgende laktasieperiodes van die sog, op die produksievermod van ...

  1. DIE GEESTESSTRUKTUUR VAN DIE ONGELOOF In die studie van ...

    African Journals Online (AJOL)

    Test

    KARL MARX (1818-1883) en FRtEDRiCH ENGELS (1820-1895) aan vaar hierdie standpunt van FEUERBACH ten opsigte van die godsdiens as onomstootlik. FEUERBACH gaan egter nie ver genoeg nie; hy moes ook gevra het: waarom überhaupt projekteer die mens sy wese in die gestalte van 'n God? Die godsdiens is ...

  2. DIE EFFEK VAN VROEGSPEEN OP GROEf EN PUBERTEIT VAN ...

    African Journals Online (AJOL)

    Volgens Poe et aL (J 969) egter, kan hierdie probleem grootliks oorkom word deur die stimulering van rumino-retikulere weefsel-vorming by die jong lam. In die huidige proef isgeen speenskok in enige van die vroeg- speengroepe ondervind nie en dit kan moontlik toege- skryf word aan die vroee inname van kruipvoer. Die.

  3. Vervanging insecticiden : bestrijding van ritnaalden in de teelt van gladiool

    NARCIS (Netherlands)

    Conijn, C.G.M.; Breedeveld, M.E.

    2004-01-01

    Van alle schadelijke bodeminsecten bij bloembollen vormen ritnaalden bij de teelt van gladiolen de grootste bedreiging. Minder massaal, doch voor de teler desastreus, komen bonenvlieg, aardrupsen en emelten als plaag voor of worden bestrijdingsmaatregelen daartegen getroffen. Alleen aan de hand van

  4. die rol van die unieverdedigingsmag in die onderdrukking van die ...

    African Journals Online (AJOL)

    DIE ROL VAN DIE UNIEVERDEDIGINGSMAG. IN DIE ONDERDRUKKING VAN DIE. NYWERHEIDSONLUSTE. VAN JANUARIE. 1914. Maj C.J. Jacobs. During the Railways and Mineworkers strike which commenced on the 18th of January 1914, the. Union Defence Force, enlarged by the Active Citizen Force and assisted ...

  5. Toepassing van de basisvrachtbenadering op fosfaat van compost; advies

    NARCIS (Netherlands)

    Ehlert, P.A.I.

    2005-01-01

    Bij het vormgeven van het stelsel van gebruiksnormen is een maatschappelijke discussie ontstaan over de aanvoer van fosfaat met grond in compost en zwarte grond. Deze deskstudie gaat in op vragen die hierbij gesteld zijn. Het aandeel grond in compost en zwarte grond en de hoeveelheid fosfaat daarin

  6. Die gebruik van Afrikaans vir die notulering van hofverrigtinge ...

    African Journals Online (AJOL)

    Daar word tans nog van beide Afrikaans en Engels vir die notulering van verrigtinge in Suid-Afrikaanse howe gebruik gemaak. Sowel regeringswoordvoerders as die Minister van Justisie het egter te kenne gegee dat 'n eentalige Engelse bedeling ingevoer mag word. Hierdie artikel ontleed die saak vir en teen so 'n ...

  7. Enkele aspekte van kerklike dissipline uit die Kerkorde van die ...

    African Journals Online (AJOL)

    p1243322

    1989:431). Die appèlartikel staan in die Kerkorde van die Sinode van. Dordrecht 1578 as Artikel 19 en word in die Kerkorde van Middelburg 1581 en daarna, gekombineer met Artikel 23 wat by Dordrecht 1578 nog 'n afsonderlike plek inneem. Laasgenoemde Artikel handel daaroor dat die meerderheid stemme bindend sal ...

  8. Onderrig van Generasie Y

    Directory of Open Access Journals (Sweden)

    Elza Venter

    2016-02-01

    Full Text Available Generasie Y-leerders is jongmense wat ongeveer tussen 1977 en 2000 gebore is. Hierdie leerders het voor skerms grootgeword, ongeag of dit televisie-, rekenaar- of selfoonskerms was. Hulle is gebore in ’n samelewing waar inligting, opvoeding en vermaak net ’n klik ver was. Navorsers meen dat dié leerders se kritiese denke en ander kognitiewe vaardighede geaffekteer is omdat hulle ’n aansienlike hoeveelheid tyd daaraan bestee het om woorde en beelde passief te absorbeer, eerder as om met insig te lees. Leerders uit die generasie is dikwels ongemotiveerd en onbetrokke by hul eie leerervaring omdat hulle hul gelyktydig op ’n menigte digitale toestelle vermaak, terwyl die opvoeder hulle aandag probeer kry. Hulle verkies multitaakverrigting eerder as om op een taak of persoon op ’n slag te fokus en stel dikwels meer belang in wat op die skerm voor hulle aangaan as in wat die onderwyser hulle kan bied. Opvoeders op sekondêre en tersiêre vlak moet kennis hiervan neem en opnuut dink oor hulle onderrig- en leerstrategieë. Die klem in hierdie navorsing val op leerders, studente en opvoeders op sekondêre en tersiêre vlak. Die navorsing is deur die toepassing van ’n literatuuroorsig gedoen. Die hoofnavorsingsvraag van die studie is: ‘Hoe kan Generasie Y-leerders beter deur opvoeders by hulle eie leer in die klaskamer of lesinglokaal betrek word?’ Die twee subvrae is: (1 ‘Wat is sommige van die eienskappe van Generasie Y-leerders wat leer beïnvloed?’ en (2 ‘Watter onderrigstrategieë kan gebruik word om Generasie Y-leerders meer by hulle eie leer te betrek?’ Die outeur van hierdie artikel wil poog om opvoeders deur die literatuurstudie van riglyne in hierdie verband te voorsien.

  9. Aard en oorsprong van bipedalisme by primate

    OpenAIRE

    P. A. J. Ryke

    1987-01-01

    Die verskille en ooreenkomste wat ape en mense kenmerk, is die onvermydelike en voorspelbare gevolg van afstamming van ’n gemeenskaplike voorouer. ’n Belangrike vraag om in hierdie verband te vra, is wat tot verandering van kwadrupedalisme na bipedalisme, waarskynlik ten tye van die divergering van aap- en hominiedstamlyne, aanleiding gegee het? Of het dit voor die splitsing geskied? Wat is die voordele en nadele van bipedale voortbeweging? ’n Evaluering van die oorsprong van bipedalisme verg...

  10. Herman Van Rompuy visiit Eestisse

    Index Scriptorium Estoniae

    2009-01-01

    Euroopa Ülemkogu eesistuja Herman Van Rompuy' visiidist Eestisse 9. detsembril 2009, kohtumistest president Toomas Hendrik Ilvese ja peaminister Andrus Ansipiga. Ingl. k. lk. 10, pealk.: Herman Van Rompuy visits Estonia

  11. Genetische analyse van het Markiesje

    NARCIS (Netherlands)

    Doekes, H.P.; Oldenbroek, J.K.; Windig, J.J.

    2016-01-01

    Het Markiesje is een van de negen oorspronkelijke Nederlandse hondenrassen. Het vervult een belangrijke rol in het Fairfok-programma. De SZH ondersteunt dat programma door de rasverenigingen van kennis en advies te voorzien.

  12. Integratie van GIS en rekenmodellen

    NARCIS (Netherlands)

    Bulens, J.D.; Bregt, A.K.; Diepen, van K.

    1995-01-01

    Koppeling tussen geografische informatiesystemen (GIS) en rekenmodellen biedt nieuwe mogelijkheden voor de analyse van onze omgeving. De technische implementatie varieert van een niet-geontegreerde koppeling, waarbij GIS en model twee losse entiteitenzijn en het gegevenstransport tussen beide

  13. Analise van die Tswanaraaisel

    Directory of Open Access Journals (Sweden)

    S. A. Swanepoel

    1984-05-01

    Full Text Available ’n Strukturele, stilistiese en funksionele bcskrywing van die Twanaraaisel bring mee dat daar aan die volgende aspekte aandag gegee moet word: •\tWat is ’n raaisel en lioe word dit in Tswana genoem. •\tTot watter studiegebied en literere genre hoort die raaisel en watter subvorme kan vir Tswana onderskei word. •\tHoe sien die struktuur van Tswanaraaisels daar uit. •\tDeur wie, waar, wanneer en hoe word Tswanaraaisels voorgedra. •\tWatter stilistiese kenmcrke kan in Tswanaraaisels onderskei word. •\tWatter funksies vervul raaisels in ’n Tswanagcmeenskap.

  14. Memory and Nostalgia in Woody Allen’s "Midnight in Paris" (Memoria y nostalgia en "Medianoche en París" de Woody Allen

    Directory of Open Access Journals (Sweden)

    Peter Eubanks

    2015-06-01

    Full Text Available Abstract: Woody Allen´s recent "Midnight in Paris" describes a Paris that has as many identities as there are observers to ascribe them. Indeed, there is no one, true Paris that everyone objectively shares; Paris, in Allen´s film, exists only in the phenomenology of the observer’s perception, a perception often marred and made unreliable by an escapist need to withdraw from the present in order to take shelter in a glorified, utopian past. Allen thus criticizes the nostalgic impulse, the "Golden-Age thinking" (as it is called in the film that forces various characters simultaneously to inhabit two worlds, that of a prelapsarian past and that of the fallen present. His protagonist´s journey back and forth between the present and the idealized Roaring Twenties is everyman´s journey, the sometimes surreal voyage between reality and imagination, between the world actually inhabited and the world artificially constructed for oneself. Yet it is when Allen´s protagonist finally discovers nostalgia within his nostalgia, a longing within his longing, that he recognizes the flawed thinking behind his almost mythologized perception of the past, reflecting everyman´s realization that the past is ultimately the expression of our present needs.Resumen: Uno de los films recientes de Woody Allen, "Midnight in Paris", describe un París que tiene tantas identidades como observadores hay a quienes atribuirlos. De hecho, no hay un París auténtico que compartan todos. París, en el film de Allen, solo existe en la fenomenología de la percepción del observador, una percepción con frecuencia dañada/arruinada y realizada poco fidedigna por una necesidad escapista a retirarse del presente para refugiarse en un pasado glorificado, utópico. Así Allen critica el impulso nostálgico, la idea del "pensamiento del siglo de oro" (tal y como viene a ser llamado en el film que obliga a que varios personajes residan en dos mundos al mismo tiempo: el de un mundo

  15. Cooperative Metal–Ligand Catalyzed Intramolecular Hydroamination and Hydroalkoxylation of Allenes Using a Stable Iron Catalyst

    KAUST Repository

    El-Sepelgy, Osama

    2018-01-18

    A new iron-catalyzed chemoselective intramolecular hydroamination and hydroalkoxylation of the readily available α-allenic amines and alcohols to valuable unsaturated 5-membered heterocycles, 2,3-dihydropyrrole and 2,3-dihydrofuran, is reported. Effective selectivity control is achieved by a metal–ligand cooperative activation of the substrates. The mild reaction conditions and the use of low amounts of an air and moisture stable iron catalyst allow for the hydrofunctionalization of a wide range of allenes bearing different functional groups in good yields in the absence of base or any sensitive additives.

  16. Reflexiones existenciales a través del humor de Woody Allen

    OpenAIRE

    Berbel López, Àngel

    2016-01-01

    El presente trabajo pretende ofrecer un análisis sobre la postura de Woody Allen ante la muerte y sus reflexiones desde el humor acerca de la exitencia humana y del sentido de la vida en sus películas y relatos, dedicando tambíen unos breves capítulos a las diferentes perspectivas y funciones del humor, y a las características de la posmodernidad, pues éstas se reflejan en la obra del autor neoyorquino. El present treball pretén oferir una anàlisi sobre la postura de Woody Allen davant la ...

  17. Replacement of two amino acids of 9R-dioxygenase-allene oxide synthase of Aspergillus niger inverts the chirality of the hydroperoxide and the allene oxide.

    Science.gov (United States)

    Sooman, Linda; Wennman, Anneli; Hamberg, Mats; Hoffmann, Inga; Oliw, Ernst H

    2016-02-01

    The genome of Aspergillus niger codes for a fusion protein (EHA25900), which can be aligned with ~50% sequence identity to 9S-dioxygenase (DOX)-allene oxide synthase (AOS) of Fusarium oxysporum, homologues of the Fusarium and Colletotrichum complexes and with over 62% sequence identity to homologues of Aspergilli, including (DOX)-9R-AOS of Aspergillus terreus. The aims were to characterize the enzymatic activities of EHA25900 and to identify crucial amino acids for the stereospecificity. Recombinant EHA25900 oxidized 18:2n-6 sequentially to 9R-hydroperoxy-10(E),12(Z)-octadecadienoic acid (9R-HPODE) and to a 9R(10)-allene oxide. 9S- and 9R-DOX-AOS catalyze abstraction of the pro-R hydrogen at C-11, but the direction of oxygen insertion differs. A comparison between twelve 9-DOX domains of 9S- and 9R-DOX-AOS revealed conserved amino acid differences, which could contribute to the chirality of products. The Gly616Ile replacement of 9R-DOX-AOS (A. niger) increased the biosynthesis of 9S-HPODE and the 9S(10)-allene oxide, whereas the Phe627Leu replacement led to biosynthesis of 9S-HPODE and the 9S(10)-allene oxide as main products. The double mutant (Gly616Ile, Phe627Leu) formed over 90% of the 9S stereoisomer of HPODE. 9S-HPODE was formed by antarafacial hydrogen abstraction and oxygen insertion, i.e., the original H-abstraction was retained but the product chirality was altered. We conclude that 9R-DOX-AOS can be altered to 9S-DOX-AOS by replacement of two amino acids (Gly616Ile, Phe627Leu) in the DOX domain. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. EMPLOYABILITY van UM-afgestudeerden

    OpenAIRE

    van Eldert, Peter; Künn, Annemarie; Mommers, Ardi

    2017-01-01

    De voor u liggende studie is een weerslag van het project ‘Employability onder UM afgestudeerden’. Het rapport geeft eerst een samenvatting van de uitgevoerde literatuurstudie op het gebied van ‘employability’ in het hoger onderwijs. Vervolgens wordt de ‘employability’ van UM afgestudeerden vijf jaar na afstuderen anno 2015 in kaart gebracht. Hiertoe rapporteren we zeven indicatoren voor ‘employability’. Naast de gebruikelijke UM brede en faculteitsspecifieke statistieken laten we ook statist...

  19. Nasionale beplanning en kodrdinering van veekundige

    African Journals Online (AJOL)

    volgende en bymekaaraanskakelende aksies waannee die doel- witte nagestreef word, 'n eerste funksie van die .... siebepaling, formulering van doelwitte en evaluering van doel- witte. Die eerste groep is die komitees van die ... biometriese beplanning, ens. van navorsingsfasette wan- neer hulle deur die direkteur van die ...

  20. GESLAGSAKTIWITEIT VAN ROMANOV-KARAKOELKRUISINGS ...

    African Journals Online (AJOL)

    geword wat 'n verskil in die liggaamsmassa van gemid- deld 6,6 kg verteenwoordig. Dit is ook van belang dat slegs 60 % van die Karakoele bronstigheid vertoon het gedurende die eerste teelseisoen na geboorte terwyl die ooreenstemmende waardes vir die 87,5 en 75% Ro- manov-kruisings 96 en 94 % onderskeidelik is.

  1. -Die leksikografiese hantering van woordgroepstamme

    African Journals Online (AJOL)

    buite die behandelingsterrein van die heersende leksikografiese praktyk val. Ondanks hierdie implikasies hoef die ~~ntering van woordgroepstamme nie vir die leksikograaf problema ties te wees nie. Die Afrikaanse leksikon bevat 'n relatief klein aantal woordgroepstamme. Hulle sal nie 'n beduidende deel van. R ep rod u.

  2. De floristiek van oude muren

    NARCIS (Netherlands)

    Segal, Sam

    1962-01-01

    Van de Plantencommissie van de Nederlandse Jeugdbond voor Natuurstudie is in 1947 een eerste poging uitgegaan tot een gericht onderzoek van de plantengroei op oude muren in Nederland. De verzamelde gegevens werden besproken in een vroegere publicatie (3). Zeer incidenteel is vóór die tijd ook wel

  3. Dirk van der Hoff: Skeurmaker?

    African Journals Online (AJOL)

    Dirk van dcr HofT. Erasmus, F W L 1950. Ds Dirk van der Hoff, 'n kritiese beoordeling van sy werk- saamhede in die Zuid-Afrikaanse Republiek. Ongepubliseerde MA verhande- ling, Potchefstroomse Universiteit vir Christelike Hoer Onderwys. Jooste, J P 1846. Die verhouding tussen kerk en stoat aan die Kaap tot die helfte ...

  4. Die eenheid van die universiteit

    Directory of Open Access Journals (Sweden)

    W. N. Coetzee

    1969-03-01

    Full Text Available Dit lyk na ’n teenstrydigheid otn te besin oor die eenheid van ’n universiteit. Die naam „universiteit” is tog afgelei van die Latynse woord „universitas”, wat in die amptelike stukke van die meeste Europese lande vandag nog gebruik word. Hierdie woord beteken „die geheel” en dit veronderstel natuurlik dadelik eenheid.

  5. Residuen van thiram in appel

    NARCIS (Netherlands)

    van den Broek HH; Greve PA; van Harten DC; Nieboer R; van Zoonen P

    1989-01-01

    Appelen van het ras Golden Delicious werden bespoten op 2 proefvelden, n.l. te Oudenbosch en te Welsum. Er werden 4 concentraties aan thiram in de spuitvloeistof uitgetest, n.l. 0,2, 0,25, 2,0 en 2,5% ; van de eerste 2 concentraties werd 1500 l/ha gespoten, van de laatste 2 concentraties 150

  6. Factoren van invloed op voedselveiligheid

    NARCIS (Netherlands)

    Deneux, S.D.C.; Fels-Klerx, van der H.J.; Tromp, S.O.; Vlieger, de J.J.

    2005-01-01

    In dit rapport van Agrotechnology & Food Innovations, Rikilt en het LEI wordt ingegaan op de factoren die van invloed zijn op de veiligheid van voedingsmiddelen. Deze factoren zijn onderverdeeld in twee hoofdgroepen, namelijk productaspecten en bedrijfsaspecten. Bij deze laatste zijn ook

  7. De dagindeling van Nederlandse managers

    NARCIS (Netherlands)

    Rob van Tulder; Ad Breukel

    2004-01-01

    De effectiviteit van managers is recentelijk weer volop in de aandacht gekomen. Dit onderzoek wil een bijdrage leveren aan deze discussie door de tijdbesteding van Nederlandse managers empirisch in kaart te brengen. De effectiviteit, de toegevoegde waarde die managers leveren door het aansturen van

  8. Maatskaplike aspekte van geriatriese sorg

    Directory of Open Access Journals (Sweden)

    D. Louw

    1979-09-01

    Full Text Available Dit is maar enkele dekades gelede dat Westerse gemeenskappe bewus geword het van die besondere behoeftes van die relatief groot en nog steeds groeiende persentasie bejaardes in hulle midde. Nie alleen het die liggaamlike behoeftes van liggaamlike afgetakelde bejaardes die aandag getrek nie maar die gemeenskappe het ook bewus geword van die maatskaplike behoeftes van ouerwordendes in ’n tydperk wat gekenmerk is deur die dramatiese veranderings in die lewenswyses van ons mense — veranderinge wat in baie opsigte ’n negatiewe invloed gehad het op die lewensomstandighede van ’n groot groep bejaardes. Welsynsbeplanners het besef dat hulle in hulle beplanning spesiale voorsiening moes maak vir die lewensbehoeftes van hierdie groep in die gemeenskap en dat hulle in die verband ’n groot agterstand het om in te haal. Geneeshere wat belang begin stel het in die gesondheidsbehoeftes van bejaardes het ook besef dat gevestigde geneeskundige praktyke geensins voldoen aan die spesifieke behoeftes van ’n groot groep bejaardes nie en dat groot aanpassings gemaak moes word met betrekking tot hulle benaderings en metodes van behandeling van hierdie pasiente.

  9. The effectiveness of the Allen Carr smoking cessation training in companies tested in a quasi-experimental design

    NARCIS (Netherlands)

    Dijkstra, Arie; Zuidema, Rixt; Vos, Diederick; van Kalken, Marike

    2014-01-01

    Background: The Allen Carr training (ACt) is a popular one-session smoking cessation group training that is provided by licensed organizations that have the permission to use the Allen Carr method. However, few data are available on the effectiveness of the training. Methods: In a quasi-experimental

  10. A Critique of Mark D. Allen's "The Preservation of Verb Subcategory Knowledge in a Spoken Language Comprehension Deficit"

    Science.gov (United States)

    Kemmerer, David

    2008-01-01

    Allen [Allen, M. (2005). "The preservation of verb subcategory knowledge in a spoken language comprehension deficit." "Brain and Language, 95", 255-264.] reports a single patient, WBN, who, during spoken language comprehension, is still able to access some of the syntactic properties of verbs despite being unable to access some of their semantic…

  11. Optimaliseren van biotoetsen voor het meten van bodemweerbaarheid van Verticillium dahliae en Pythium spp.

    NARCIS (Netherlands)

    Schreuders, H.; Wurff, van der A.W.G.

    2009-01-01

    In de grondgebonden teelten is de bestrijding van ziektes een lastig probleem doordat steeds meer chemische bestrijdingsmiddelen niet meer gebruikt mogen worden. Daarnaast zijn milieuvriendelijke oplossingen belangrijk. De competentie van de bodem om ziekten en plagen te onderdrukken wordt hierdoor

  12. Onderzoek naar de optimalisering van de toepassing van plantenextracten ter bestrijding van de champignonvlieg

    NARCIS (Netherlands)

    Baar, J.; Rutjens, A.J.; Kogel, de W.J.

    2007-01-01

    Optimalisatie van toepassing plantenextracten (dosering, toepassingstijdstip en toediening) voor het bestrijden van de champignonvlieg. Champignonvliegen, Megaselia halterata (Diptera: Phoridae), vormen een continu probleem in de champignon doordat zij ziekten kunnen verspreiden, die aanzienlijke

  13. Voedselveiligheid van nieuwe eiwitten

    NARCIS (Netherlands)

    Spiegel, van der M.; Noordam, M.Y.; Fels-Klerx, van der H.J.

    2013-01-01

    De consumptie van dierlijke eiwitten is sterk toegenomen door een stijgende wereldbevolking en opgekomen economieën als China en India. Dit heeft grote gevolgen voor de voedselvoorziening en het milieu. Om land- en energieverbruik terug te dringen moet een eiwittransitie plaatsvinden waarbij minder

  14. Van Bahrein tot Bitcoin

    NARCIS (Netherlands)

    Lodder, A.R.

    2014-01-01

    Door het internet kan de burger rechtstreeks contact krijgen met zijn publiek zonder hulp van derden als omroepen, kranten, uitgevers, muziekindustrie, etc. Bij al deze communicaties is prominent (Youtube) of minder prominent (Wordpress) een derde partij betrokken die de communicatie faciliteert.

  15. DIE OPENBARINGSLEER VAN SCHILDER

    African Journals Online (AJOL)

    23 Volgens Schilder: ...maar God wil geen openbaring geven, die den mensch als't ware onder hypnose brengt en hem in dien zin overweldig (Om Woord en kerk III 1951:11). 24 Volgens Schilder: Maar de onuitputtelijkheid van het teeken komt u herinneren, dat heden Gods zelfopenbaring haar voltooiing begint; dat ge nu ...

  16. Pythagoras Meets Van Hiele.

    Science.gov (United States)

    Flores, Alfinio

    1993-01-01

    Develops the Pythagorean Theorem in the context of the Van Hiele levels by presenting activities appropriate for each level. Activities point to preparatory development (level 0), give 3 different versions of Euclid's proof (levels 1, 2, and 3), give some generalizations of the theorem (level 3), and explore the Pythagorean relationship in other…

  17. Het importeren van honingbijen

    NARCIS (Netherlands)

    Cornelissen, B.

    2007-01-01

    Er wordt in de wereld volop gehandeld in bijen en bijenproducten. De globalisering is niet aan de bijenteelt voorbij gegaan. Producten als honing en propolis, maar ook raszuivere koninginnen worden over heel de wereld gemaakt en verspreid. Met deze wereldwijde verplaatsing van bijen kunnen ook

  18. Implementatie van kwaliteitssystemen.

    NARCIS (Netherlands)

    Sluijs, E.M.; Bakker, D.H. de

    1995-01-01

    Het implementeren of invoeren van een kwaliteitssysteem verloopt niet zelden met vallen en opstaan. Er valt menige hindernis te nemen, zo hebben instellingen en beroepsbeoefenaren die hier al enkele jaren ervaring mee hebben opgedaan ondervonden. Toch zijn de ervaringen overwegend positief en wordt

  19. Heath Van Essen

    Science.gov (United States)

    The EPA is providing notice of a proposed Administrative Penalty Assessment against Heath Van Essen, Respondent, an individual who owns or operates an animal feeding operation (“Facility”) that is located in Section 27 of Township 98 North, Range 47 West,

  20. De vereniging van eigenaars

    NARCIS (Netherlands)

    Vegter, Noortje

    2012-01-01

    An owners’ association (in Dutch Vereniging van Eigenaars or VvE) manages the common areas of an apartment complex. The owners’ association is a body linked to titles to apartments for the purpose of facilitating decision-making regarding the management, use and maintenance of the common areas and

  1. Impact van onderwaterlawaai onderzocht

    NARCIS (Netherlands)

    Winter, H.V.

    2012-01-01

    Vroeger was de enige menselijke activiteit op zee de scheepvaart. Maar de Noordzee krijgt steeds meer windmolenparken, pijpleidingen en olieplatforms, en er wordt bijvoorbeeld gebaggerd en seismisch onderzoek gedaan. Over de effecten van geluiden onder water op het leven in zee is echter nog weinig

  2. Casus. Herstel van jeneverbesstruwelen

    NARCIS (Netherlands)

    Hommel, P.W.F.M.; Griek, M.; Haveman, R.; Ouden, den J.; Waal, de R.W.; Verberk, W.

    2009-01-01

    Jeneverbesstruwelen komen in Europa voor op heel verschillende soorten bodem, variërend van zure, voedselarme zandgronden tot kalksteenrotsen met een leemdekje. Het gaat echter altijd om plekken waar in het verleden gedurende lange tijd, met wisselende intensiteit, begrazing heeft plaats gevonden.

  3. De staat van Dalton

    NARCIS (Netherlands)

    D. de Haan

    2005-01-01

    “Geef jouw onderwijskracht een richting: kies de daltonvariant.” Met deze aanmoediging aan studenten om zich in te schrijven als deelnemer aan de studievariant ‘daltononderwijs’ begon ik in 2002 mijn carrière als daltoncoördinator van de Theo Thijssen Academie, de opleiding voor leraar primair

  4. Versterking van het vestingkarakter van Wageningen : verkenning van de mogelijkheden voor herstel van de stadsgracht

    NARCIS (Netherlands)

    During, R.

    2013-01-01

    Wageningen is nog vrijwel geheel door een stadsgracht omgeven. Vrijwel, maar niet helemaal... Aan de oostkant van de stad, tussen Bergpoort en Plantsoen, is in 1967 een stukje stadsgracht gedempt. Het Platform Stadsgracht Wageningen wil de gracht hier graag herstellen. De gemeentelijke overheid laat

  5. Verbeteren eetkwaliteit van stierenvlees

    NARCIS (Netherlands)

    Os, van M.; Heeres-van der Tol, J.J.; Kranen, R.W.; Eikelenboom, G.

    2001-01-01

    Deze eisen zullen de uniformiteit verbeteren, maar wat het effect is van deze factoren op de eetkwaliteit is echter minder bekend. Om hier inzicht in te krijgen heeft het Praktijkonderzoek Veehouderij in samenwerking met het ID-Lelystad een onderzoek uitgevoerd.

  6. Van Gogh's Sunflowers

    Science.gov (United States)

    Daddino, Michelle

    2010-01-01

    In this article, the author describes an art project wherein kindergarten students painted sunflowers. These beautiful and colorful sunflowers were inspired by the book "Camille and the Sunflowers" by Laurence Anholt, which does an amazing job of introducing young children to the art and life of Vincent van Gogh.

  7. Bacteriologisch Onderzoek van slachtdieren

    NARCIS (Netherlands)

    Engel HWB; van Leusden FM; Erne EHW

    1986-01-01

    Door zes vleeskeuringsdiensten en het RIVM werd gezamenlijk onderzoek verricht naar het in de Vleeskeuringswet omschreven "Bacteriologisch Onderzoek" (BO) bij slachtdieren. Doel was na te gaan of er verschillen zouden zijn in de aantallen positieve resultaten van het BO tussen de diensten

  8. Invloed van minerale olie op de bestrijding van Phytophthora infestans in pootaardappelen

    NARCIS (Netherlands)

    Spits, H.G.; Bus, C.B.

    2003-01-01

    De invloed van toevoeging van olie aan een fungicide op de werking van het fungicide is afhankelijk van het gebruikte fungicide. Gezamenlijk spuiten van olie en Aviso DF, Curzate M en mogelijk ook Acrobat, verhoogt de curatieve werking van deze fungiciden. Gezamenlijk spuiten van olie en Aviso DF,

  9. Het bepalen van de plasma renine activiteit door middel van de radioimmunochemische bepaling van angiotensine I

    NARCIS (Netherlands)

    Elvers LH; Somers HHJ; Loeber JG

    1986-01-01

    De plasma renine activiteit (PRA) wordt gemeten door de radioimmunochemische bepaling (RIA) van het angiotensine I (AI) dat gevormd wordt tijdens incubatie van het renine met zijn substraat (angiotensinogeen). Om degradatie van het gevormde AI door peptidases te voorkomen worden als angiotensinases

  10. Temporal and Spatial Characterization of ULF power and its relation to relativistic electrons in the radiation belts during geomagnetic storms

    Science.gov (United States)

    Vinas, A. F.; Moya, P. S.; Pinto, V. A.; Sibeck, D. G.; Kanekal, S.; Kletzing, C.

    2015-12-01

    The response of the inner magnetosphere to different geomagnetic storm and solar wind conditions is still not fully understood. For example, electron fluxes in the outer radiation belt can be enhanced or depleted depending on the energy of the particles, and the phase or driver of the storm. In addition, the time scale of the process can vary from minutes to several days. Wave-particle interactions (such as stochastic diffusion or resonant acceleration) are believed to play an important role regulating the dynamics of the particles. However, despite decades of intense theoretical and observational studies, a definitive framework for the wave-particle interactions and the resulting effects in the magnetospheric dynamics remains an open problem. To progress towards a better understanding of the inner magnetosphere dynamics, we need a complete characterization of the electromagnetic fluctuations during storms. Here, using Van Allen Probe magnetic field and relativistic electron observations, we present an statistical study of the relationship between ULF wave power and relativistic electron fluxes in the outer radiation belt during several geomagnetic storms between 2012 and 2015, depending on local time, geocentric distance and storm phase.

  11. Roles of whistler mode waves and magnetosonic waves in changing the outer radiation belt and the slot region

    Science.gov (United States)

    Li, L. Y.; Yu, J.; Cao, J. B.; Yang, J. Y.; Li, X.; Baker, D. N.; Reeves, G. D.; Spence, H.

    2017-05-01

    Using the Van Allen Probe long-term (2013-2015) observations and quasi-linear simulations of wave-particle interactions, we examine the combined or competing effects of whistler mode waves (chorus or hiss) and magnetosonic (MS) waves on energetic (0.5 MeV) electrons inside and outside the plasmasphere. Although whistler mode chorus waves and MS waves can singly or jointly accelerate electrons from the hundreds of keV energy to the MeV energy in the low-density trough, most of the relativistic electron enhancement events are best correlated with the chorus wave emissions outside the plasmapause. Inside the plasmasphere, intense plasmaspheric hiss can cause the net loss of relativistic electrons via persistent pitch angle scattering, regardless of whether MS waves were present or not. The intense hiss waves not only create the energy-dependent electron slot region but also remove a lot of the outer radiation belt electrons when the expanding dayside plasmasphere frequently covers the outer zone. Since whistler mode waves (chorus or hiss) can resonate with more electrons than MS waves, they play dominant roles in changing the outer radiation belt and the slot region. However, MS waves can accelerate the energetic electrons below 400 keV and weaken their loss inside the plasmapause. Thus, MS waves and plasmaspheric hiss generate different competing effects on energetic and relativistic electrons in the high-density plasmasphere.

  12. Energy transfer from lower energy to higher-energy electrons mediated by whistler waves in the radiation belts

    Science.gov (United States)

    Shklyar, D. R.

    2017-01-01

    We study the problem of energy exchange between waves and particles, which leads to energization of the latter, in an unstable plasma typical of the radiation belts. The ongoing Van Allen Probes space mission brought this problem among the most discussed in space physics. A free energy which is present in an unstable plasma provides the indispensable condition for energy transfer from lower energy particles to higher-energy particles via resonant wave-particle interaction. This process is studied in detail by the example of electron interactions with whistler mode wave packets originated from lightning-induced emission. We emphasize that in an unstable plasma, the energy source for electron energization is the energy of other particles, rather than the wave energy as is often assumed. The way by which the energy is transferred from lower energy to higher-energy particles includes two processes that operate concurrently, in the same space-time domain, or sequentially, in different space-time domains, in which a given wave packet is located. In the first process, one group of resonant particles gives the energy to the wave. The second process consists in wave absorption by another group of resonant particles, whose energy therefore increases. We argue that this mechanism represents an efficient means of electron energization in the radiation belts.

  13. Effects of over-expression of allene oxide cyclase on camptothecin ...

    African Journals Online (AJOL)

    Camptothecin (CPT) is an anticancer and antiviral monoterpene-derived indole alkaloid which can be induced by plant hormone, jasmonates. To improve the production of the pharmaceuticals, the jasmonate biosynthesis related gene allene oxide cyclase from Camptotheca acuminate was transferred back into C.

  14. A generalized solution to a Cahn-Hilliard/Allen-Cahn system

    Directory of Open Access Journals (Sweden)

    Jose Luiz Boldrini

    2004-10-01

    Full Text Available We study a system consisting of a Cahn-Hilliard and several Allen-Cahn type equations. This system was proposed by Fan, L.-Q. Chen, S. Chen and Voorhees for modelling Ostwald ripening in two-phase system. We prove the existence of a generalized solution whose concentration component is in $L^{infty}$.

  15. Book Review: Vivien Allen, "Lady Trader – A biography of Mrs Sarah ...

    African Journals Online (AJOL)

    VIVIEN ALLEN Lady Trader – A biography of Mrs Sarah Heckford (Second Edition) Protea Book House, Pretoria 2010. Soft cover, index, foreword, index of names of persons and places, 307 pp. Illustrations – photographs, paintings and drawings, 12 pp. ISBN 978-1-86919-337-7. R225 ...

  16. Bis-phosphine allene ligand: coordination chemistry and preliminary applications in catalysis.

    Science.gov (United States)

    Vanitcha, Avassaya; Damelincourt, Cecilia; Gontard, Geoffrey; Vanthuyne, Nicolas; Mouriès-Mansuy, Virginie; Fensterbank, Louis

    2016-05-21

    A 1,3-bis-diphenylphosphine allene can give rise to new coordination complexes with palladium, platinum and gold metals. These complexes were fully characterized by NMR, HRMS and X-ray diffraction analysis. For gold(i), the corresponding dinuclear complex has been used in a series of diagnostic catalytic reactions and gave promising preliminary results in asymmetric catalysis.

  17. Well-posedness for one-dimensional anisotropic Cahn-Hilliard and Allen-Cahn systems

    Directory of Open Access Journals (Sweden)

    Ahmad Makki

    2015-01-01

    Full Text Available Our aim is to prove the existence and uniqueness of solutions for one-dimensional Cahn-Hilliard and Allen-Cahn type equations based on a modification of the Ginzburg-Landau free energy proposed in [8]. In particular, the free energy contains an additional term called Willmore regularization and takes into account strong anisotropy effects.

  18. Preparation and properties of polyallenes. Part I Polymerization of allene by Ziegler-type catalysts

    NARCIS (Netherlands)

    Havinga, R.; Schors, A.

    1968-01-01

    The polymerization of allene induced by organoaluminum-vanadium oxytrichloride catalysts has been investigated in aliphatic hydrocarbons and at normal pressure. For the catalysts investigated, the polymerization activity decreases at decreasing order of alkylation of the aluminum alkyl: AIR3 > AIR2X

  19. Tim Allen, one of Hollywood's top comedy actors with Rolf Landua from CERN

    CERN Document Server

    Laurent Guiraud

    2000-01-01

    Tim Allen ('Galaxy Quest', 'For Richer and Poorer', 'The Santa Clause', Voice of 'Buzz Lightyear', in Toy Story 1 and 2), visited CERN in July 2000. He has a keen interest in modern physics. In his last book "I'm not really here" he contemplates the funny and the intriguing aspects of quantum physics in his daily life.

  20. Mysterious Illnesses of Human Commodities in Woody Allen and Franz Kafka

    Directory of Open Access Journals (Sweden)

    Iris Bruce

    1998-01-01

    Full Text Available The article examines correspondences between Woody Allen's film Zelig and texts by Franz Kafka. Both Leonard Zelig and Gregor Samsa ( The Metamorphosis suffer from mysterious illnesses which are multi-determined. Twentieth-century racial stereotypes are partially responsible for them; other causes lie in the commercialization of life in early twentieth-century society. Zelig's illness parallels the cultural trends and political movements of his time and becomes full-blown in the fascist movement. Zelig is therefore also a commentary on the cultural climate which helped bring about the rise of fascism. Kafka could not benefit from Allen's hindsight, but Kafka's representation of what turns human beings into commodities with no identity of their own nonetheless complements Allen's picture. Further parallels are drawn between Zelig and Kafka's hunger artist, the performing ape Rotpeter ("A Report to an Academy", and Karl Rossmann ( Amerika . All of these protagonists fail to retain a sense of selfhood in a commodified world. Yet the causes for their illnesses lie not in themselves but in society on the whole, and for this reason there is no cure for these human commodities. Unlike Kafka, though, Woody Allen grants Zelig a cure in the end, a cure which is possible only in the realm of fantasy.

  1. Substituent effects on the ring-opening mechanism of lithium bromocyclopropylidenoids to allenes.

    Science.gov (United States)

    Azizoglu, Akin; Balci, Metin; Mieusset, Jean-Luc; Brinker, Udo H

    2008-11-07

    The ring-opening reactions of lithium bromocyclopropylidenoids to allenes have been investigated computationally at the B3LYP/6-31G(d) level of theory. Formally, two pathways can be considered: the reaction may either proceed in a concerted fashion or stepwise with the intermediacy of a free cyclopropylidene. In both cases, the loss of the bromide ion determines the kinetic of the reaction. The stability of the reactive intermediate, i.e., the carbene, is dependent on the substituent. Cyclopropylidenes bearing an electron-donating group (+M) are extremely unstable and ring-open readily to the allene. In contrast, bromocyclopropylidenoids with electron-withdrawing groups are particularly stable species. Here, a high energy barrier needs to be overcome in order to split off bromide and to generate the corresponding carbene or allene. Still, for most of the monosubstituted cyclopropylidenes investigated during this study, the activation energy for the cyclopropylidene to allene rearrangement is lower than the energy required for parent compound (X = H) except for X = -SiH3 and -CF3.

  2. Application of allenylsilver(I) compounds in organic synthesis. A simple route to substituted allenes

    NARCIS (Netherlands)

    Westmijze, H.; Kleijn, H.; Bos, H.J.T.; Vermeer, P.

    1980-01-01

    Allenylsilver(I) compounds, prepared in situ by addition of alkylsilver(I)-lithium bromide complexes to butenynes, readily react with a variety of electrophiles. The produced compounds are usually almost pure allenes, but in some cases substantial amounts of the isomeric acetylenes are also formed.

  3. Free Pulp Transfer for Fingertip Reconstruction-The Algorithm for Complicated Allen Fingertip Defect.

    Science.gov (United States)

    Spyropoulou, Georgia-Alexandra; Shih, Hsiang-Shun; Jeng, Seng-Feng

    2015-12-01

    We present a review of all the cases of free toe pulp transfer and an algorithm for application of free pulp transfer in complicated Allen fingertip defect. Seventeen patients underwent free toe pulp transfer for fingertip reconstruction by the senior author. Twelve cases were Allen type II with oblique pulp defect, 4 were Allen type III, and 1 patient had 2 fingertip injuries classified both as type IV. According to the algorithm presented, for the type III defects where the germinal matrix is still preserved, we use free pulp transfer and nail bed graft to preserve the nail growth instead of toe to hand transfer. For the type IV injuries with multiple defects, a combination of web flap from both big toe and second toe is possible for 1-stage reconstruction. All pulp flaps survived completely. Static 2-point discrimination ranged from 6 to 15 mm (mean: 10.5 mm). No patient presented dysesthesia, hyperesthesia, pain at rest, or cold intolerance. The donor site did not present any nuisances apart from partial skin graft loss in 3 cases. We tried to classify and modify the defects' reconstruction according to Allen classification. Free toe pulp transfer is a "like with like" reconstruction that provides sensate, glabrous skin with good color and texture match for fingertip trauma, and minimal donor site morbidity compared with traditional toe to hand transfer.

  4. Over de toegvoegde waarde van management en managers

    NARCIS (Netherlands)

    F.A.J. van den Bosch (Frans)

    1995-01-01

    textabstractBedrijven en andere organisaties lijken plat gewalst te worden. Verplatting van organisaties,- de opkomst van netwerken als concurrenten voor organisaties; schrappen van managementlagen; verdwijnen van banen voor het leven en de opkomst van autonome taakgroepen; afschaffen van de

  5. Epidemiologie van Corynespora cassiicola in Saintpaulia : literatuurstudie en labproeven

    NARCIS (Netherlands)

    Wubben, J.P.; Lanser, C.J.

    2004-01-01

    Het epidemiologische onderzoek concentreerde zich op eigenschappen van Corynespora die van belang zijn voor ontstaan en ontwikkeling van een aantasting van Saintpaulia. Op basis van de resultaten hiervan kunnen klimaat maatregelen en teeltomstandigheden vastgesteld worden om aantasting van

  6. Die gebruik van parallelplaatreologie vir die bepaling van die intrinsieke viskositeit van poli-etileentereftalaat

    Directory of Open Access Journals (Sweden)

    O. C. Vorster

    2005-09-01

    Full Text Available Die bepaling van die intrinsieke viskositeit van poli-etileentereftalaat word bemoeilik deur die feit dat daar tans slegs twee metodes in gebruik is. In die eerste metode word die bepaling deur middel van oplossingsviskometrie gedoen, maar die toksisiteit van die oplosmiddel, asook die tydperk wat dit neem om die bepaling te doen, is ’n probleem. Die tweede metode word beperk deur die kompleksiteit en beskikbaarheid van die apparatuur in Suid-Afrika. In hierdie studie word ’n alternatiewe metode, gebaseer op parallelplaatreologie, voorgestel wat albei hierdie probleme oorkom en die resultate sodoende verkry, word vergelyk met dié wat met bestaande metodes verkry is.

  7. The Los Alamos.confEic Radiation Environment Assimilation Model (DREAM) for Space Weather Specification and Forecasting

    Science.gov (United States)

    Reeves, G.; Freidel, R.; Chen, Y.; Koller, J.; Henderson, M.

    The Dynamic Radiation Environment Assimilation Model (DREAM) was developed at Los Alamos.confEnal Laboratory to assess, quantify, and predict the hazards from the natural space environment and the anthropogenic environment produced by high altitude nuclear explosions (HANE). DREAM was initially developed as a basic research activity to understand and predict the dynamics of the Earth's Van Allen radiation belts. It uses Kalman filter techniques to assimilate data from space environment instruments with a physics-based model of the radiation belts. DREAM can assimilate data from a variety of types of instruments and data with various levels of resolution and fidelity by assigning appropriate uncertainties to the observations. Data from any spacecraft orbit can be assimilated but DREAM was designed to function with as few as two spacecraft inputs: one from geosynchronous orbit and one from GPS orbit. With those inputs, DREAM can be used to predict the environment at any satellite in any orbit whether space environment data are available in those orbits or not. Even with very limited data input and relatively simple physics models, DREAM specifies the space environment in the radiation belts to a high level of accuracy. DREAM has been extensively tested and evaluated as we transition from research to operations. We report here on one set of test results in which we predict the environment in a highly-elliptical polar orbit. We also discuss long-duration reanalysis for spacecraft design, using DREAM for real-time operations, and prospects for 1-week forecasts of the radiation belt environment.

  8. Uitwisselen van teelten helpt kwekers verder : biologische teelt

    NARCIS (Netherlands)

    Pronk, A.A.; Reuler, van H.

    2004-01-01

    Beschrijving van ontwikkelingen in de biologische teelt van boomkwekerijgewassen. Genoemd worden: biologische bestrijding van aaltjes met tagetes; tussengewas als vanggewas om uitspoelen van stikstof te voorkomen

  9. Vijfde afdeeling : schorsing van de vervolging : artikelen 14-20

    NARCIS (Netherlands)

    Kristen, F.G.H.; Groenhuijsen, M.S.; de Roos, Th.A.; Swart, A.H.J.

    2000-01-01

    In deze inleiding op de vijfde afdeling van Titel I van Boek 1 van het Wetboek van Strafvordering wordt ingegaan op de inhoud, de betekenis, de reikwijdte en de gevolgen van schorsing van de vervolging. Daartoe de regeling van de schorsing van de vervolging gepositioneerd ten opzichte van andere

  10. Die bevordering van geesteswetenskaplike studie*

    Directory of Open Access Journals (Sweden)

    M. Elaine Botha

    1980-03-01

    Full Text Available Hierdie tema sou op ’n verskeidenheid van wyses aangepak kon word: Eerstens is dit moontlik om planne te bedink op grond waarvan die studentegetalle in die geesteswetenskappe verhoog sou kon word. Tweedens is dit moontlik om ’n soort wetenskaplike rasionalisasie te verskaf vir die feit dat die oënskynlik anachronis- tiese geesteswetenskappe nog steeds aangebied word in ’n tyd waarin die hele samelewing in die teken van die wetenskap en die tegniek staan. Dit sou natuurlik ook moontlik wees om die tema aan te pak vanuit ’n statistiese ontleding van die stand van die geesteswetenskappe en daardeur op tendense en ontwikkelingsrig- tinge te dui. Natuurlik sou daar voldoende grond wees om ook die hele kwessie van die gebrekkige finansiering van die geesteswetenskappe aan die orde te stel en ’n pleidooi te lewer vir beter salariëring van geesteswetenskaplik-geskooldes, beter beurse vir studente in die geesteswetenskappe en beslis meer geleenthede vir na- vorsing in die geesteswetenskappe. Voorts sou die uiteindelike werksituasie van die geesteswetenskaplik-geskoolde in oënskou geneem kon word. Indien daar ’n oor- skot van geesteswetenskaplik-geskooldes bestaan, sou dit geremedieer moes word en indien daar ’n tekort aan dergelike geskooldes sou bestaan, sou planne beraam moes word vir die aanmoediging van studie in hierdie rigting.

  11. Electromagnetic van Kampen waves

    Energy Technology Data Exchange (ETDEWEB)

    Ignatov, A. M., E-mail: aign@fpl.gpi.ru [Russian Academy of Sciences, Prokhorov General Physics Institute (Russian Federation)

    2017-01-15

    The theory of van Kampen waves in plasma with an arbitrary anisotropic distribution function is developed. The obtained solutions are explicitly expressed in terms of the permittivity tensor. There are three types of perturbations, one of which is characterized by the frequency dependence on the wave vector, while for the other two, the dispersion relation is lacking. Solutions to the conjugate equations allowing one to solve the initial value problem are analyzed.

  12. Ellis-van Creveld

    Directory of Open Access Journals (Sweden)

    Dhandabani Jayaraj

    2012-01-01

    Full Text Available Ellis-van Creveld (EVC syndrome is an autosomal recessive disorder that is also known as chondro-ectodermal dysplasia. The common manifestations of this syndrome are short ribs, postaxial polydactyly, growth retardation, and ectodermal and cardiac defects. The present case report is about an 8-year-old boy who had the features of bilateral hexadactyly, knocked knees, cardiac problems, congenital absence of incisors, fused upper and lower labial frenulum, and mulberry molars.

  13. Telemarketing: irritatie geregeld? Onderzoek naar de perceptie van consumenten ten aanzien van telemarketing en effectiviteit van (zelf)regulering

    NARCIS (Netherlands)

    Baarsma, B.E.; van Buiren, K.H.S.; Gerritsen, M.; Leenheer, J.; van Honk, J.

    2007-01-01

    SEO Economisch Onderzoek heeft in opdracht van het Ministerie van Economische Zaken onderzocht (i) in welke mate consumenten irritatie ondervinden van telemarketing en (ii) in hoeverre de huidige (zelf)regulering effectief is in het voorkomen van irritatie. Uit het onderzoek blijkt dat ruimt 90% van

  14. Onderzoek naar de effecten van snoezelen op het gedrag van demente verpleeghuisbewoners en de werkbeleving van verzorgenden.

    NARCIS (Netherlands)

    Weert, J. van; Peter, J.; Dulmen, S. van; Ribbe, M.; Bensing, J.

    2004-01-01

    Het effect van snoezelen in de 24-uurszorg op de stemming en het gedrag van demente ouderen is nooit eerder onderzocht. Ook is in geen van de eerdere studies het effect onderzocht van snoezelen op de werkbeleving van verzorgenden. Uit onderzoek is bekend dat in verpleeghuizen waar geen

  15. [Van Helmont and gas].

    Science.gov (United States)

    van Gijn, Jan; Gijselhart, Joost P

    2012-01-01

    Johan Baptista van Helmont (1579-1644) was born in Brussels, around the time the Southern Netherlands ceased their resistance against the Spanish rule. He studied a variety of disciplines in Louvain and made a 'grand tour' in Europe, but remained dissatisfied with traditional knowledge, which he regarded as empty phrases and sophistry. His spouse being wealthy, he devoted himself to studying nature anew, unencumbered by prejudice, as Paracelsus (1493-1541) had done before him. Yet in his attempts to explain living and inanimate matter he could not avoid making basic assumptions. Among these was his view that there were only two elements: water and air. Water might carry elementary seeds from which a variety of substances could develop. When a substance was consumed by fire, an ethereal essence would remain, which he called 'Gas' (a term perhaps derived from Paracelsian 'chaos', perhaps from 'Geist'). Today 'gas' is defined as the volatile state of a given substance, but in Van Helmont's view it was mainly a metaphysical characteristic. Most of Van Helmont's work was published only after his death, through a verdict of the Spanish Inquisition.

  16. Verwijdering van fenol uit waterige stromen : Nieuw type van solvent impregnated resins omtwikkeld door TNO

    NARCIS (Netherlands)

    Geerdink, P.; Berg, C. van den

    2014-01-01

    Binnen de procesindustrie kan het reinigen van grote, waterige stromen een belangrijk onderdeel van de proceskosten vormen. Voor het verwijderen en terugwinnen van hydrofobe koolwaterstoffen zoals benzeen, bestaan verschillende processen. Het winnen van wateroplosbare koolwaterstoffen is echter een

  17. De bodemgesteldheid van het landinrichtingsgebied Ramele-Pleegste; resultaten van een bodemgeografisch onderzoek

    NARCIS (Netherlands)

    Vroon, H.R.J.

    1999-01-01

    Het landinrichtingsgebied Ramele-Pleegste bestaat grotendeels uit pleistocene afzettingen. Op de fluviatiele afzettingen van de Rijn (Formatie van Kreftenheye) liggen fluvioperiglaciale en eolische afzettingen (formatie van Twente). Op een groot aantal plaatsen komt in de laagste delen van het

  18. Bepaling van enkele neurotransmitters, monoaminen, en metabolieten, met behulp van Continuous Flowapparatuur

    NARCIS (Netherlands)

    Eigeman L; Schonewille F; Borst M; van der Laan JW

    1986-01-01

    Bij het onderzoek in de psychofarmacologie kan kennis van de effecten van stoffen op de omzettingssnelheid van neurotransmitters een belangrijk aspect zijn. Met de huidige psychofarmaca lijken vooral de klassieke neurotransmitters zoals de monoaminen, noradrenaline, dopamine en serotonine van

  19. Interpretatie van grond- en oppervlaktewateranalyses van het natuurreservaat in het ruilverkavelingsgebied Giethoorn - Wanneperveen

    NARCIS (Netherlands)

    Kemmers, R.H.

    1984-01-01

    In het kader van de voorgenomen ruilverkaveling Giethoorn-Wanneperveen is een uitgebreid hydrologisch onderzoek uitgevoerd naar de gevolgen van polderpeilverlaging ten oosten van het natuurreservaat in bezit van Natuurmonumenten. Als aanvulling op het hydrologisch onderzoek is door de

  20. Registratie van voedselinfecties en -vergiftigingen onderzocht door GGD's en Keuringsdiensten van waren, 1999

    NARCIS (Netherlands)

    van Duynhoven YTHP; de Wit MAS; CIE

    2000-01-01

    In deze rapportage worden de gegevens gepresenteerd van voedselinfecties en voedselvergiftigingen in Nederland in 1999. De resultaten zijn gebaseerd op meldingen door consumenten aan de Keuringsdienst van Waren, op standaard rapportages van onderzochte explosies van voedselinfecties en

  1. Hormonen in importvlees. Een evaluatie van recente gegevens over gehalten aan van nature voorkomende hormonen

    NARCIS (Netherlands)

    Kootstra PR; Rossum HJ van; Zoontjes PW; Schwillens PLWJ; Wubs KL; Herbold HA; Stephany RW; Sterk SS; Ginkel LA van; ARO

    2005-01-01

    Consumptie van vlees, geimporteerd uit Zuid-Amerika, met name Argentinie en Brazilie, leidt niet tot inname van lichaamsvreemde hormonen. Bovendien zijn er geen aanwijzingen voor inname van verhoogde hoeveelheden lichaamseigen hormonen. Onderzoek naar het illegaal gebruik van groeibevorderende

  2. De betekenis van leugens - Anita Mooi, 1996. Feit en fictie en JFK - Henk van Renssen, 1996

    NARCIS (Netherlands)

    Vos, Chris

    1998-01-01

    textabstractReviews of:De betekenis van leugens, over historische beeldvorming, audiovisuele geschiedschrijving en de functie van historische fictie, Anita Mooi. Doctoraalscriptie Film- en Televisiewetenschap, Universiteit van Amsterdam, 1996.Feit en fictie en JFK, Henk van Renssen.

  3. Bepaling van 14C in afvalwater

    NARCIS (Netherlands)

    Hiemstra YS; Kwakman PJM; Nissan LN; Aldenkamp FJ; LSO

    1998-01-01

    In opdracht van de Hoofdinspectie Milieuhygiene van het ministerie van VROM heeft LSO een methode ontwikkeld om 14C in afvalwater van nucleaire installaties te bepalen. De methode meet organisch gebonden-14C en anorganisch-14C in de vorm van carbonaat (14CO32-) in afvalwater. Het rapport

  4. Droge vergisting van berm- en natuurgras

    NARCIS (Netherlands)

    Zwart, K.B.; Boer, de D.

    2015-01-01

    Dit rapport beschrijft de resultaten van de proef met droge vergisting van bermgras en natuurgras. Daarbij wordt niet alleen aandacht besteed aan de hoeveelheid biogas die geproduceerd kan worden, maar ook aan de kwaliteit van de geproduceerde compost en aan de duurzaamheid van deze vorm van

  5. Bemesting van iris in de broeierij

    NARCIS (Netherlands)

    Pasterkamp, H.P.; Marinova, S.; Wees, van N.S.

    2003-01-01

    Bij de bloementeelt van iris komt een aantal afwijkingen voor; vooral bloemverdroging en bladverbranding. Een oplossing hiervoor zou aanpassing van de beschikbaarheid van bepaalde nutriënten zijn. PPO Bloembollen deed onderzoek naar het voorkomen van deze afwijkingen. Vooral de broeiers van irissen

  6. Outsourcing van het ICT door overheidsinstellingen

    NARCIS (Netherlands)

    Kok, L.; Theeuwes, J.J.M.; Janssens, L.

    2003-01-01

    Het IWI heeft onlangs gewezen op de risico’s van outsourcing van ICT door het UWV. Ook het uitbesteden van ICT door gemeenten is niet zonder risico. Om outsourcingsbeslissingen van gemeenten en UWV te kunnen beoordelen wil het ministerie meer inzicht in de effecten van outsourcing. De directie

  7. 08 Botha Van Vuuren 03.pmd

    African Journals Online (AJOL)

    hond

    7 Apr 2007 ... karakters, van byvoorbeeld die taal van die mistiek, van die wetenskap, van die skone kunste. Taal wat weerstand bied” (De Waal e.a. 2004; ons kursivering). Winterbach se kom- mentaar skakel met Mikhail Bakhtin se teorie oor meerstemmigheid. Niggieis 'n poli- foniese teks waarin die taal van mistiek, ...

  8. De syntaxis van de Italiaanse preposities

    NARCIS (Netherlands)

    Boer, M.G. de

    2010-01-01

    SAMENVATTING In dit hoofdstuk wordt een inventaris opgesteld van de Italiaanse preposities die voorkomen in een corpus bestaande uit de romans La Ciociara van Moravia en Il Gattopardo van Tomasi di Lampedusa. Achtergrond voor de herkenning van preposities is de Extended Standard Theory van de

  9. Het Aquacultuurprogramma van Initiatief Duurzame Handel (IDH)

    NARCIS (Netherlands)

    Heijden, van der P.G.M.

    2016-01-01

    Na bijna 10 jaar bij Ahold als manager product integriteit te hebben gewerkt, is Aldin Hilbrands sinds een jaar directeur van het Aquacultuurprogramma van IDH. Deze organisatie is gericht op het verduurzamen van internationale handelsketens. IDH doet dit door middel van het bouwen van

  10. Ontwikkelingen omtrent de nieuwbouw van het Pluimveeproefbedrijf

    NARCIS (Netherlands)

    Tinholt, J.

    1991-01-01

    Na een stilstand van bijna een jaar is half september 1990 de bouw van het nieuwe proefbedrijf hervat. Met het bereiken van het hoogste punt van de eerste stal op 26 oktober 1990 zal volgens verwachting in augustus 1991 de voltooiing van het geheel kunnen plaatsvinden.

  11. Hoge resolutie typering van Coxiella burnetii

    NARCIS (Netherlands)

    Janse, I.; Bossers, A.; Roest, H.I.J.; Rotterdam, van B.

    2011-01-01

    Dit rapport beschrijft het onderzoek wat uitgevoerd is in het kader van het project ‘Hoge Resolutie Typering Coxiella burnetii’’. Het doel van dit project was om de genoomsequenties van een aantal Nederlandse isolaten van de bacterie Coxiella burnetii, de veroorzaker van Q-koorts, in kaart te

  12. Tien eeue leksikografie: Van woordelys tot woordeboek

    African Journals Online (AJOL)

    In 1953 het die Lexicon in Veteris Testamenti Libros van Ludwig. Koehler en Walter Baumgartner verskyn, 'n gebeurtenis van deurslag- gewende betekenis op die gebied van die studie van die Ou Testament. Dit was die resultaat van ongeveer veertig jaar se werk, soos Koehler dit self in die inleiding tot sy woordeboek ...

  13. Erkennen van een MOOC: een statusoverzicht

    NARCIS (Netherlands)

    Robert Schuwer

    2015-01-01

    Toekennen van studiepunten aan het succesvol volgen van een MOOC. Dit onderwerp is in de afgelopen jaren al meermalen aan bod gekomen bij discussies over mogelijke effecten van MOOC’s op het reguliere onderwijs. Medio 2014 verscheen een verkenning hierover van de NVAO (NVAO, 2014). Eén van de

  14. (Zelf) meten aan de vitaliteit van bijen

    NARCIS (Netherlands)

    Steen, van der J.J.M.

    2012-01-01

    Tijdens het symposium van bijen@wur PRI op 18 maart vertelde Sjef van der Steen over zijn onderzoek in 2009 en 2010 naar invloed van variatie en continuïteit in de aanvoer van stuifmeel op de vitaliteit van bijenvolken. Voor Bijenhouden schreef hij een artikel over zijn aanpak en de uitkomsten, met

  15. De kleur van de Omgevingswet

    OpenAIRE

    Backes, C.W.

    2017-01-01

    Auteur stelt de Utrechtse oratie van Michiels uit 2001 ‘Kleur in het omgevingsrecht’ centraal. In deze oratie ging Michiels in op de relatie tussen het ruimtelijkeordeningsrecht en het milieurecht en stelde de vraag of wij niet naar een integrale omgevingswet zouden moeten en wat de kleur daarvan zou moeten zijn. Auteur gaat in op de vraag welke kleur de Omgevingswet heeft gekregen. Is er sprake van een grijsbruin mengsel of van een kleurrijk schilderij?

  16. Die winder van Afrikaans III.

    Directory of Open Access Journals (Sweden)

    S. du Toit

    1959-03-01

    Full Text Available Dit was ’n gelukkige gedagte om vir hierdie feeste as tema te kies: die wonder van Afrikaans. Inderdaad het daar ’n wonder gebeur — die geboorte van ’n nuwe taal. Maar ’n taal kan nie bestaan sonder dat daar ’n nasie is wat dit praat en skryf nie. Die geboorte van ’.n nuwe nasie is net so ’n wonder.

  17. Duurzaamheidseffecten aanpak milieuschadelijke subsidies: de duurzaamheidseffecten van aanpassing of afschaffing van milieuschadelijke subsidies nader onderzocht

    NARCIS (Netherlands)

    J.A. van Ast (Jacko); K.E.H. Maas (Karen); J.J. Bouma (Jan Jaap)

    2006-01-01

    textabstractDit onderzoek heeft betrekking op enerzijds het ontwikkelen van een transparante methodiek voor het bepalen van de sociale en economische effecten van subsidies en anderzijds het toepassen van de ontwikkelde methodiek voor het bepalen van sociale, economische en ook milieueffecten van

  18. Onderzoek naar het nitraatgehalte van het ondiepe grondwater in de omgeving van Achterberg

    NARCIS (Netherlands)

    Tusveld, M.C.L.; Welling, S.E.

    1984-01-01

    Een bestudering van het verloop van het nitraatgehalte van het ondiepe grondwater en bepaling van de menselijke invloed op de samenstelling van het ondiepe grondwater door het chloridegehalte hiervan te vergelijken met het nitraatgehalte; dit in verband met de eutrofiering van het grond- en

  19. Aanwezigheid van ascosporen van Sclerotinia sclerotiorum binnen en buiten besmette percelen

    NARCIS (Netherlands)

    Lamers, J.G.; Wander, J.; Russchen, H.J.

    2012-01-01

    De aantasting van een gewas door Sclerotinia sclerotiorum hangt af van de aanwezigheid van ascosporen van deze schimmel in de lucht. In dit onderzoek dat gefinancierd wordt door PT en PA werd nagegaan in hoeverre de ascosporen van het eigen perceel afkomstig zijn of ook van een naburig perceel

  20. Naar een grotere impact van energiebesparingsprojecten door middel van stakeholderanalyse en - management

    OpenAIRE

    Kool, de, S.A.M.

    2011-01-01

    Het doel van dit project is het krijgen van inzicht in de houding en de belangen van adviseurs, toeleverende bedrijven en installatietechnische bedrijven en het krijgen van commitment voor het uitdragen van een eensluidende boodschap over energiebesparingsmogelijkheden. Hierdoor zal een grotere groep telers informatie krijgen over energiebesparingsmogelijkheden en deze mogelijkheden durven benutten, waardoor de energiebesparing op sectorniveau zal toenemen. Door middel van een stakeholderanal...

  1. Kognitiewe en persoonlikheidskorrelate van aandaggewing

    Directory of Open Access Journals (Sweden)

    S. J. Vos

    1993-06-01

    Full Text Available Cognitive and personality correlates of attention. The principal aim of the study was to determine the cognitive and personality correlates of attention. Two contrasting groups were formed on the basis of scores from a self report inventory of attention. These two groups were compared in terms of the NSAG, the SAT, the 16PF and the JPQ. With the aid of the Hotelling T2 it was found that the vectors of means scores of the two contrasting groups differed statistically significantly from one another in respect of both the cognitive and personality variables. Opsomming Die hoofdoel van die studie was om die persoonlikheids- en kognitiewe korrelate van aandaggewing vas te stel. Twee kontrasterende groepe is saamgestel aan die hand van tellings op 'n selfverslaggewende vraelys oor aandaggewing. Hierdie twee groepe is met mekaar vergelyk ten opsigte van die NSAG, die SAT, die 16PF, en die JPV. Met behulp van Hotelling se T'toets is vasgestel dat die vektore van gemiddeldes van die twee groepe statistics beduidend van mekaar verskil ten opsigte van sowel die kognitiewe as die persoonlikheidsmetings.

  2. Quantifying the Precipitation Loss of Radiation Belt Electrons During a Rapid Dropout Event

    Science.gov (United States)

    Pham, K. H.; Tu, W.; Xiang, Z.

    2017-10-01

    Relativistic electron flux in the radiation belt can drop by orders of magnitude within the timespan of hours. In this study, we used the drift-diffusion model that includes azimuthal drift and pitch angle diffusion of electrons to simulate low-altitude electron distribution observed by POES/MetOp satellites for rapid radiation belt electron dropout event occurring on 1 May 2013. The event shows fast dropout of MeV energy electrons at L > 4 over a few hours, observed by the Van Allen Probes mission. By simulating the electron distributions observed by multiple POES satellites, we resolve the precipitation loss with both high spatial and temporal resolutions and a range of energies. We estimate the pitch angle diffusion coefficients as a function of energy, pitch angle, and L-shell and calculate corresponding electron lifetimes during the event. The simulation results show fast electron precipitation loss at L > 4 during the electron dropout, with estimated electron lifetimes on the order of half an hour for MeV energies. The electron loss rate shows strong energy dependence with faster loss at higher energies, which suggest that this dropout event is dominated by quick and localized scattering process that prefers higher energy electrons. The improved temporal and spatial resolutions of electron precipitation rates provided by multiple low-altitude observations can resolve fast-varying electron loss during rapid electron dropouts (over a few hours), which occur too fast for a single low-altitude satellite. The capability of estimating the fast-varying electron lifetimes during rapid dropout events is an important step in improving radiation belt model accuracy.

  3. Quantitative mid-infrared spectra of allene and propyne from room to high temperatures

    KAUST Repository

    Es-sebbar, Et-touhami

    2014-11-01

    Allene (a-C3H4; CH2CCH2) and propyne (p-C3H4; CH3C2H) have attracted much interest because of their relevance to the photochemistry in astrophysical environments as well as in combustion processes. Both allene and propyne have strong absorption in the infrared region. In the present work, infrared spectra of a-C3H4 and p-C3H4 are measured in the gas phase at temperatures ranging from 296 to 510 K. The spectra are measured over the 580-3400 cm-1 spectral region at resolutions of 0.08 and 0.25 cm-1 using Fourier Transform Infrared spectroscopy. Absolute integrated intensities of the main infrared bands are determined at room temperature and compared with values derived from literature for both molecules. Integrated band intensities are also determined as a function of temperature in various spectral regions.

  4. De kleur van de lucht en van de zee

    NARCIS (Netherlands)

    Kunz, G.J.; Laane, R.W.P.M.

    1989-01-01

    Alvorens wat dieper in te gaan op de kleur van de lucht, zal eerst de betekenis van de woorden 'kleur' en 'lucht' wat nader onderzocht worden. Dit is nodig omdat kleur een subjectieve indruk is en omdat lucht niet een éénduidige betekenis heeft.

  5. Ontrafelen van het effect van zorg op de boerderij

    OpenAIRE

    Noorduyn, L.

    2004-01-01

    Aardbeien plukken helpt mensen die depressief zijn. Dat komt door de mooie rode kleur van de vrucht. Deze en andere uitspraken tekenden onderzoeker Jan Hassink en zijn collega’s op uit de mond van zorgboeren en -boerinnen. Hassink: ‘Ik weet niet of dat zo is, maar het is boeiend om dit soort ervaringen uit te zoeken.’

  6. Ontrafelen van het effect van zorg op de boerderij

    NARCIS (Netherlands)

    Noorduyn, L.

    2004-01-01

    Aardbeien plukken helpt mensen die depressief zijn. Dat komt door de mooie rode kleur van de vrucht. Deze en andere uitspraken tekenden onderzoeker Jan Hassink en zijn collega’s op uit de mond van zorgboeren en -boerinnen. Hassink: ‘Ik weet niet of dat zo is, maar het is boeiend om dit soort

  7. Specifieke deskundigheid van paramedici op het terrein van chronische aandoeningen.

    NARCIS (Netherlands)

    Veenhof, C.; Plas, M.; Dekker, J.; Ende, E. van den

    2000-01-01

    Zowel beroepsorganisaties als patiëntenorganisaties melden dat de specifieke deskundigheid van paramedici op het terrein van de genoemde ziekten vooral in instellingen aanwezig is. Daar werkt men in multidisciplinaire samenwerkingsverbanden waaraan ook paramedici deelnemen. In de eerste lijn treft

  8. Karakterisering van het Etimologie- woordeboek van Afrikaans (EWA)

    African Journals Online (AJOL)

    rbr

    Abstract: Characterisation of the Etimologiewoordeboek van Afrikaans (EWA). In 2003, thirty six years after Afrikaanse etimologieë by Boshoff and Nienaber, a new etymological dictionary of Afrikaans has been published: the Etimologiewoordeboek van Afrikaans (EWA). There is a substantial difference between these two ...

  9. Geschiktheid van bermmaaisel als meststof; een verslag van acht praktijkproeven

    NARCIS (Netherlands)

    Spijker, J.H.; Ehlert, P.A.I.; Jong, de J.J.; Niemeijer, C.M.; Scheepens, P.C.; Vries, de E.A.

    2004-01-01

    In acht pilots is op praktijkschaal bermmaaisel verzameld en voorbewerkt met als doel te kunnen inzetten als meststof in de landbouw. Dit bermmaaisel is geanalyseerd op organische-stofgehalte, homogenitiet van de organische stof, contaminatie met zware metalen en de aanwezigheid van vitale

  10. Voorzitter van de Joodse Raad. De herinneringen van David Cohen

    NARCIS (Netherlands)

    Somers, E.L.M.

    2010-01-01

    Geen instantie heeft na de oorlog zo onder vuur gelegen vanwege haar functioneren tijdens de Duitse bezetting als de Joodsche Raad. Hoofdrolspeler in deze bewogen jaren was prof. David Cohen, samen met Abraham Asscher voorzitter van de Joodse Raad. Op verzoek van prof. Jacques Presser en dr. Loe de

  11. Kwaliteit van de huisartsenzorg vanuit migrantenperspectief: ontwikkeling van een meetinstrument.

    NARCIS (Netherlands)

    Fakiri, F. el; Sixma, H.J.; Weide, M.G.

    2000-01-01

    In het kader van de Tweede Nationale studie voor ziekten en verrichtingen in de huisartsenpraktijk (NS2) zal in 2000 een enquête gehouden onder Turken, Marokkanen, Surinamers en Antillianen. Voor deze enquête is in opdracht van ZorgOnderzoek Nederland (ZON) een meetinstrument ontwikkeld om de

  12. Nanotechnologie in dienst van veiligheid en justitie: Verkenning van toepassingsmogelijkheden

    NARCIS (Netherlands)

    Schulze Greiving, Verena C.; te Kulve, Haico; Konrad, Kornelia Elke; Kuhlmann, Stefan; Pinkse, Pepijn Willemszoon Harry

    2016-01-01

    In de afgelopen 15 jaar is nanotechnologie steeds meer onder de aandacht gekomen en heeft de financiering van nanotechnologisch onderzoek een grote vlucht genomen. Een aantal producten op basis van nanotechnologie is reeds op de markt verschenen. Over het algemeen is nanotechnologie nog steeds een

  13. Prestatiemeting ten tijde van economische crisis: de aanpak van DSM

    NARCIS (Netherlands)

    van Rinsum, M.; den Dekker, R.; Maas, V.

    2011-01-01

    Deze studie besteedt aandacht aan de gevolgen van de financiële crisis voor het prestatiemeetsysteem van een onderneming. Vanwege de financiële crisis hebben veel ondernemingen naast langetermijndoelstellingen ook een aantal kortetermijndoelstellingen geformuleerd die betrekking hebben op hun

  14. n Oorsig van die huidige stand van navorsing oor die ...

    African Journals Online (AJOL)

    Test

    7 Jun 2011 ... duidelike beskrywing van die opponente nie (kyk Schmid. 2002; Van der Merwe 2007 vir volledige besprekings). In 'n poging om die opponente te identifiseer, word die direkte opmerkings wat wél oor hulle gemaak word met sekere indirekte opmerkings gekombineer ten einde 'n volledige prentjie te skets.

  15. Dutch Water Mining: Potentie van een zuiverend landschap van overvloed

    NARCIS (Netherlands)

    Os, van E.; Kruijs, A.; Bomas, B.; Poelman, M.; Pater, de M.; Bokhoven, van D.

    2012-01-01

    De blauwalg in het Volkerak - Zoommeer zorgt jaarlijks voor veel overlast. In de zomerperiode zijn giftig water en stank een hinderlijk fenomeen voor iedereen. Met de techniek Dutch Water Mining verdwijnt de overlast van blauwalgen. Voor de omliggende landbouwbedrijven ontstaat de zekerheid van een

  16. LYS VAN GESKRIFTE VAN PROF. DR. S. P. ENGELBRECHT*) A ...

    African Journals Online (AJOL)

    Test

    Amsterdam en Pretoria). 1925 Qeschiedenis van de Nederdüits Hervormde Ker^ in Ztitd-Afri^a. ... 1930 Ibid: Papiergeídindteotídae. —. Die SoMter Liedekens. —. In „Die Nuwe Brandwag", Mei-uitgawe: Die geskiedenis van die Transvaaise ...

  17. Invloed van waterconditioners en hulpstoffen op de effectiviteit van gewasbeschermingsmiddelen

    NARCIS (Netherlands)

    Zeeland, van M.G.

    2007-01-01

    In 2005 heeft de gebruikerscommissie naar aanleiding van de literatuurstudie over hulpstoffen drie aanbevelingen voor verder onderzoek geformuleerd. In 2006 zijn twee daarvan in onderzoek genomen, namelijk: wordt door toevoegen van waterconditioners (Easi-mix, Intake, X-change) aan hard water de

  18. Planning en ontwerp van kantoorgebouwen : Typologie van gebouwen

    NARCIS (Netherlands)

    De Gunst, D.D.; De Jong, T.

    1989-01-01

    Het kantoorgebouw behoort tot de categorie bedrijfsgebouwen waarbij efficiency, econom ie en exploitatie veel aandacht vragen Dit boek is in de eerste plaats bedoeld als informatie bron over kantoorgebouwen voor studerenden, waarbij op een breed scala van aspekten die bij het ontwerpen van

  19. Betekenis van Legionella-soorten voor preventiebeleid van leidingwaterinstallaties

    NARCIS (Netherlands)

    Versteegh JFM; Brandsema PS; Lodder WJ; de Roda Husman AM; Schalk JAC; van der Aa NGFM; IMG; LZO; EPI

    2009-01-01

    Het RIVM adviseert om de huidige normstelling voor het preventiebeleid van Legionella te handhaven en niet uitsluitend op Legionella pneumophila te richten. Als andere Legionella-soorten worden aangetroffen kan er ook groei van Legionella pneumophila optreden. Als er dan geen maatregelen worden

  20. Het dichtwerk van Jan van Foreest (1585-1651)

    NARCIS (Netherlands)

    Vries, M. de

    2007-01-01

    The dissertation consists of an edition of Jan van Foreest's Greek poems and the greater part of those written in Latin, provided with translations and a succinct commentary in Dutch. A number of the Latin poems appears in print for the first time ever. Jan van Foreest (1586-1651) studied arts at