Search

Subauroral emissions known as STEVEs (Strong Thermal Emission Velocity Enhancements) are sometimes accompanied by green arcs containing magnetic field‐aligned “picket fence” structures. In a newly published spectrum of a green picket fence arc Gillies et al. (2019, https://doi.org/10.1029/2019GL083272) showed that the visible emission in such arcs is mostly OI 557.7 nm with minimal N2+1N. This finding is consistent with the color ratios found in digital camera photos (Mende & Turner, 2019, https://doi.org/10.1029/2019JA026851) and is distinct from the ratios in auroral precipitation. The spectrum also contains intense N2first positive (1P) emission. The presence of OI 557.7 (~4.19 eV excitation energy) and N21P (~7.35 eV), combined with the lack of N2+first negative (~18.75 eV) commonly seen in the aurora, suggests that the particles exciting the emission have energy <18.75 eV. This is strong evidence against the precipitation hypothesis recently put forth (Nishimura et al., 2019, https://doi.org/10.1029/2019GL082460; Gillies et al., 2019, https://doi.org/10.1029/2019GL083272). Recent spectra of a green STEVE arc shows intense 557.7 nm OI and N21P nitrogen emission in the IR but minimal N2+1N in the blueColor ratios in photos of the green "picket fence" arcs are consistent with the spectrospcopic resultsSpectra and the color ratios show low energy excitation which is inconsistent with auroral source from the magnetosphere

Photos of a spectacular optical phenomenon, nicknamed STEVE, show finely structured, purple‐colored, east‐west arcs spanning the sky. These purple Sub‐auroral Arc Emissions are associated with Sub‐Auroral Ion Drifts, often accompanied by separate green arcs frequently displaying magnetic field aligned rays suggesting charge particle excitation. Both types of these arcs and polar auroras appear in some photos. Splitting the images into red, green, and blue channels allowed comparison of color ratios of the three phenomena. Wavelength calibration of the camera verified that the dominant atmospheric auroral emissions, 630.0 nm O(1D), O(1S) 557.7 nm, and N2+1N bands, were cleanly separated in the red, green, and blue channels of the camera. In the absence of a spectrogram the ratios between the color channels were interpreted in terms of possible excitation mechanisms. The purple arcs contained an excess of blue, presumably N2+1N intensity. This excess production could be due to the excitation of N2+ions that were ionized through charge exchange with O+. The green companion arcs appear to be purely green (557.7) with almost no blue and minimal red suggesting excitation by low‐energy electrons excitation at altitudes >100 and <150 km. The color ratios of purple and green subauroral arcs were compared to normal aurora using there red, green and blue intensisitiesIn purple arcs blue emission is enhanced, perhaps due to soft electron acting on charge exchanged N2+, and red due to 630 nm from OGreen companion arcs are likely to be soft electron excited green line at low altitudes with no blue. Source of soft electrons is unknown

As with all optical systems the calibration of wide‐field ultraviolet (UV) systems includes three main areas: sensitivity, imaging quality, and imaging capability. The one thing that makes UV calibrations difficult is the need for working in vacuum substantially extending the required time and effort compared to visible systems. In theory a ray tracing and characterization of each individual component of the optical system (mirrors, windows, and grating) should provide the transmission efficiency of the combined system. However, potentially unknown effects (contamination, misalignment, and measurement errors) can make the final error too large and unacceptable for most applications. Therefore, it is desirable to test and measure the optical properties of the whole system in vacuum and compare the overall response to the response of a calibrated photon detector. A proper comparison then allows the quantification of individual sources of uncertainty and ensures that the whole instrument performance is within acceptable tolerances or pinpoints which parts fail to meet requirements. Based on the experience with the IMAGE Spectrographic Imager, the Wide‐band Imaging Camera, and the ICON Far Ultraviolet instruments, we discuss the steps and procedures for the proper radiometric sensitivity and passband calibration, spot size, imaging distortions, flatfield, and field of view determination. As with all optical systems the calibration of wide‐field ultraviolet (UV) systems includes three main areas: sensitivity, imaging quality, and imaging capability. The one thing that makes UV calibrations difficult is the need for working in vacuum substantially extending the required time and effort compared to visible systems. Based on the experience with the IMAGE Spectrographic Imager, the Wide‐band Imaging Camera (WIC), and the ICON Far Ultraviolet instruments, we discuss the steps and procedures for the proper radiometric sensitivity and pass‐band calibration, spot size, imaging distortions, flatfield, and field of view determination. Summary of tests for imaging capabilities and imaging quality of wide‐angle UV instruments for space applicationsDescription of steps to determine quantitative sensitivity of UV instrumentInfluence and test of environmental effects on imaging properties

The elve is the dominant type of transient luminous event (TLE) at the base of the Eregion ionosphere. The hydroxyl nightglow (OH* nightglow hereafter) has been reported at a similar altitude. Statistical studies show that the mean heights of elve and OH* nightglow are 87 km and 87.5 km, respectively, and that 91% of the 291 limb elves are located within ±5 km of the altitude of the brightest OH* nightglow emission and both elves and OH* nightglow show the semiannual oscillation (SAO) at low latitude. The physical reasons for the collocation of elves and OH* nightglow are the main focus of attention. A model for elve emission with the environmental‐adapted electron density profile is tested with three density profiles of atomic oxygen (O): the original profile from the NRLMSISE‐00 model and two other profiles which are shifted 5 km upward/downward from the original. For higher altitudes of the given O density profile, the peak altitudes of the elve emission layers are also increased. This result reveals the leading role of atomic oxygen in the collocation. Furthermore, the altitude variation of elves is compared with the VLF reflection height observed by DEMETER. The latter height not only shows the SAO similarity to the elve/OH* heights but also exhibits a difference between land and ocean. The possible relationship between VLF reflection height and elve/OH* height is also discussed. The collocation of elves and OH Meinel band nightglow implies that OH* nightglow is the visible upper boundary of the VLF waveguide. The collocation of OH* and elves with a well‐calibrated satellite image is shown for the first timeAtomic oxygen causes elves and OH* to oscillate vertically with the same phase on the semiannual time scaleThe OH* nightglow may be the visible indicator of VLF reflection height

In this study we examine the dynamic evolution of Southern Hemisphere auroral precipitation patterns, specifically poleward moving auroral forms (PMAFs). The spatial, structural, and temporal characteristics of these events have been linked to underlying magnetopause‐boundary layer flux transfer events which are responsible for the generation of these ionospheric transient forms. We present five case studies of Southern Hemisphere PMAFs using optical data for 630.0 nm and 427.8 nm wavelengths from the US Automatic Geophysical Observatory Network in Antarctica. Emphasis is put on the unique capabilities of two‐dimensional optical data when it comes to studying PMAFs in the context of pulsed magnetic reconnection. In a detailed examination of three PMAFs recorded in 2007, we have found that their motion closely follows the underlying plasma convection patterns as determined from backscatter radar data, which in turn are governed by the interplanetary magnetic field (IMF) configuration. Of particular interest are periods when the positive IMF Bycomponent causes an asymmetric convection pattern which is biased toward the dawn region. These cases are consistent with the expected antisymmetric nature of the northern and southern hemisphere convection. In addition, we present two “pseudo” PMAFs which are actually independent auroral arcs executing poleward motions and occurring when the IMF Bzwas positive. Using two‐dimensional images instead of one‐dimensional keograms or meridian scanning photometer recordings, we were able to distinguish these arcs from PMAFs. The misidentification of these arcs as PMAFs would cause inconsistencies with the theories of cusp aurora dynamics and magnetic reconnection, and some previous studies may have included such non‐PMAF events. Two‐dimensional all‐sky images allow for an in‐depth analysis of the dynamic evolution of Southern Hemisphere PMAFsMotion of PMAFs follows the plasma convection pattern for the given IMF configuration and is consistent with Northern Hemisphere studiesSome events of earlier meridian scanning photometer studies identified as Bz> 0 PMAFs may have been independent auroral arcs

Auroral substorms are often associated with optical ray or bead structures during initial brightening (substorm auroral onset waves). Occurrence probabilities and properties of substorm onset waves have been characterized using 112 substorm events identified in Time History of Events and Macroscale Interactions during Substorms (THEMIS) all‐sky imager data and compared to Rice Convection Model–Equilibrium (RCM‐E) and kinetic instability properties. All substorm onsets were found to be associated with optical waves, and thus, optical waves are a common feature of substorm onset. Eastward propagating wave events are more frequent than westward propagating wave events and tend to occur during lower‐latitude substorms (stronger solar wind driving). The wave propagation directions are organized by orientation of initial brightening arcs. We also identified notable differences in wave propagation speed, wavelength (wave number), period, and duration between westward and eastward propagating waves. In contrast, the wave growth rate does not depend on the propagation direction or substorm strength but is inversely proportional to the wave duration. This suggests that the waves evolve to poleward expansion at a certain intensity threshold and that the wave properties do not directly relate to substorm strengths. However, waves are still important for mediating the transition between the substorm growth phase and poleward expansion. The relation to arc orientation can be explained by magnetotail structures in the RCM‐E, indicating that substorm onset location relative to the pressure peak determines the wave propagation direction. The measured wave properties agree well with kinetic ballooning interchange instability, while cross‐field current instability and electromagnetic ion cyclotron instability give much larger propagation speed and smaller wave period. Occurrence probability and property of different types of auroral onset waves are determinedWave property does not relate to substorm strength but to plasma sheet configurationWave properties are most consistent with kinetic ballooning interchange instability

The Imager for Sprites and Upper Atmospheric Lightning (ISUAL) was the first specifically dedicated instrument to observe lightning‐induced transient luminous events (TLE): sprites, elves, halos, and gigantic jets from space. The Imager is an intensified CCD system operating in the visible wavelength region with a filter wheel to select from six positions with filters. The Imager has a 5° × 20° (vertical times horizontal) field of view. The spectrophotometer (SP) is populated with six photometers with individual filters for emissions from the far ultraviolet to the near infrared. An array photometer with two channels operating in the blue and red provides altitude profiles of the emission over 16 altitude bins each. The Associated Electronics Package (AEP) controls instrument functions and interfaces with the spacecraft. ISUAL was launched 21 May 2004 into a Sun‐synchronous 890 km orbit on the Formosat‐2 satellite and has successfully been collecting data ever since. ISUAL is running on the nightside of the orbit and is pointed to the east of the orbit down toward the limb. The instrument runs continuously and writes data to a circular buffer. Whenever the SP detects a sudden signal increase above a preset threshold, a trigger signal is generated that commands the system to keep the data for about 400 ms starting from ~50 ms before the trigger. Over its lifetime of ~11 years the system recorded thousands of TLE and also successfully observed aurora and airglow. ISUAL is the first dedicated science instrument for comprehensive, long‐term, and global transient luminous event observations from spaceInstrument includes CCD Imager, spectrophotometer, and array photometer for spatial and spectral characterization of TLEOperations aim at separating pure lightning from lightning accompanied by TLE

Monochromatic all‐sky imagers at South Pole and other Antarctic stations of the Automatic Geophysical Observatory chain recorded the aurora in the region where the Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellites crossed the dayside magnetopause. In several cases the magnetic field lines threading the satellites when mapped to the atmosphere were inside the imagers' field of view. From the THEMIS magnetic field and the plasma density measurements, we were able to locate the position of the magnetopause crossings and map it to the ionosphere using the Tsyganenko‐96 field model. Field line mapping is reasonably accurate on the dayside subsolar region where the field is strong, almost dipolar even though compressed. From these coordinated observations, we were able to prove that the dayside cusp aurora of high 630 nm brightness is on open field lines, and it is therefore direct precipitation from the magnetosheath. The cusp aurora contained significant highly structured N2+427.8 nm emission. The THEMIS measurements of the magnetosheath particle energy and density taken just outside the magnetopause compared to the intensity of the structured N2+427.8 nm emissions showed that the precipitating magnetosheath particles had to be accelerated. The most likely electron acceleration mechanism is by dispersive Alfvén waves propagating along the field line. Wave‐accelerated suprathermal electrons were seen by FAST and DMSP. The 427.8 nm wavelength channel also shows the presence of a lower latitude hard‐electron precipitation zone originating inside the magnetosphere. Comparison between THEMIS satellite data and ground‐based optical auroral data proves that cusp auroras are on open field linesThe source of the dayside cusp auroral particles is the magnetosheathThe soft cusp auroras contain significant N2+intensity to imply that acceleration of the magnetosheath particles takes place

Simultaneous measurements of F‐region neutral winds near 250 km and topside field‐aligned interhemispheric plasma flow near 600 km, made by the ionospheric connections satellite, allow the connection between these parameters to be observationally established for the first time. The largest variations in the topside plasma flows are seen as a function of season and are shown to depend on trans‐equatorial neutral winds near the F peak in a manner that is essentially the same during the daytime and the nighttime for the solar minimum conditions that prevail in 2020. This finding is consistent with established principles of a servo model of the ionosphere for which both production and loss rates in the topside are specified by the O/N2ratio at the F‐peak height. The intermediate relationships, describing how the neutral wind influences the F‐peak height and how the O+plasma pressure gradient across the equator influences the interhemispheric plasma flow are also investigated and found to be consistent with expectations. Neutral winds in the upper atmosphere apply collisional forces to the charged particles that produce motions parallel and perpendicular to the magnetic field. Motions parallel to the magnetic field influence the distribution of charged particle pressure and thus change the plasma motion everywhere along the magnetic field. Simultaneous measurements of the neutral winds and the plasma motions at remote locations connected by the magnetic field allow the relationships between these quantities to be observationally established for the first time. These relationships show the direct relationships between the meridional winds near 250 km, the peak height of the ionospheric density and the field‐aligned interhemispheric plasma transport velocity at the apex of the magnetic field near 600 km. Meridional winds near the F‐peak directly drive F‐peak height and topside field‐aligned interhemispheric plasma flowsMeridional wind across the magnetic equator at 250 km is linearly related to field‐aligned plasma flow across the magnetic equator at 600 kmIonospheric Connections satellite provides the first simultaneous observations of F‐region winds and topside field‐aligned interhemispheric plasma flows Meridional winds near the F‐peak directly drive F‐peak height and topside field‐aligned interhemispheric plasma flows Meridional wind across the magnetic equator at 250 km is linearly related to field‐aligned plasma flow across the magnetic equator at 600 km Ionospheric Connections satellite provides the first simultaneous observations of F‐region winds and topside field‐aligned interhemispheric plasma flows

Substorm auroral onset is often preceded by plasma sheet flow bursts, poleward boundary intensifications (PBIs), and subsequent auroral streamers, suggesting that enhanced transient flows in the plasma sheet propagating toward the near‐Earth plasma sheet play an important role in leading to substorm onset. This study aims at determining the magnetotail source region of preonset PBIs and plasma sheet flows by using the ARTEMIS spacecraft coordinated with the THEMIS all‐sky imager array. ARTEMIS has an advantage of measuring flows between the nominal near‐Earth neutral line (NENL) and distant neutral line (DNL) locations, and thus, the flow direction allows identifying which source region is dominant. We found three preonset conjunction events, and all cases show earthward flow bursts ~10–30 min before substorm onset when PBIs and streamers are detected in the conjugate ionosphere. This time lag is sufficiently long to bring plasma from the ARTEMIS location toward the near‐Earth plasma sheet before onset. The earthward flow direction indicates that preonset enhanced flow channels leading to precursor PBIs originate from further downtail of ARTEMIS, possibly from DNL rather than from NENL. The flow direction changes to tailward after the substorm onset, suggesting that NENL is not related to preonset flow and auroral activity but becomes active during the expansion phase. We determined the source region of pre‐onset PBIs using the ARTEMIS‐ASI pair.All cases show earthward flows ~10‐30 min before substorm onset during PBIs.The earthward flow direction indicates pre‐onset flows originating from DNL.

Abstract: Two substorms occurred at ∼04:05 and ∼04:55 UT on February 26, 2008 are studied with the in-situ observations of THEMIS satellites and ground-based aurora and magnetic field measurements. Angelopoulos et al. have made a comprehensive study of the 04:55 UT event. We showed detailed features of the two substorms with much attention to the first event and to the relationship between mid-tail magnetic reconnection (MR) and substorm activities. It was found that in the earlier stage of each substorm, a first auroral intensification occurred 2–3 min soon after the start of mid-tail MR, followed by a slow and very limited expansion. The auroral arcs were weak, short-lived, and localized, characterizing all features of a pseudobreakup. We regarded the first auroral brightening as the initial onset of the substorms. A few minutes later, a second stronger auroral intensification appeared, followed by quick and extensive expansions. It was interesting to note that the second brightening and related poleward expansion happened almost simultaneously (within a couple of minutes) with the onset of earthward flow and dipolarization in the near-Earth tail and other phenomenon of the substorm expansion phase. We thus regarded the second auroral brightening as the major onset of the substorms. Furthermore, it was seen that during the growth phase of the two substorms, the polar cap open flux Ψ kept increasing, while it quickly reduced during the substorm expansion and recovery phase. These variations of Ψ implied that the evolution of the two substorm expansion phases were closely related to MR of tail lobe open field lines. Analysis of substorm activities revealed that the two events studied were small substorms; while estimate of MR rate indicated that the MR processes in the two substorms were weak. The aforementioned observations suggested that mid-tail MR initiated the pseudobreakup first; the earthward flow generated by MR transported magnetic flux and energy to the near-Earth tail to cause the formation of SCW and CD, which induced near-Earth dipolarization and major auroral brightening, and eventually led to the onset of the substorm expansion phase. These results were clearly consistent with the picture of NENL and RCS models and supported the two step initiation scenario of substorms.

We present a method for estimating incident photoelectrons' energy spectra as a function of altitude by combining global scale far‐ultraviolet (FUV) and radio‐occultation (RO) measurements. This characterization provides timely insights important for accurate interpretation of ionospheric parameters inferred from the recently launched Ionospheric Connection Explorer (ICON) observations. Quantification of photoelectron impact is enabled by the fact that conjugate photoelectrons (CPEs) directly affect FUV airglow emissions but not RO measurements. We demonstrate a technique for estimation of photoelectron fluxes and their spectra by combining coincident ICON and COSMIC2 measurements and show that a significant fraction of ICON‐FUV measurements is affected by CPEs during the winter solstice. A comparison of estimated photoelectron fluxes with measured photoelectron spectra is used to gain further insights into the estimation method and reveals consistent values within 10–60 eV. The impact of solar radiation on the atmosphere produces highly energetic electrons, which travel freely along the magnetic Earth's field lines from one hemisphere to the other. When these electrons flow from the sunlit side into the nightside hemisphere, they interact with the neutral species and produce noticeable effects in the ionosphere such as an increase in electron temperature and enhancement of airglow emissions. This study presents a method to quantify the amount of precipitating electrons and their energy on a global scale using two recent satellite missions, ICON and COSMIC2. Our results demonstrate that coincident far‐ultraviolet (ICON) and radio‐occultation (COSMIC2) measurements from space are valuable resources to study precipitating electrons in the ionosphere and their impact on inferring ionospheric plasma parameters. Nightglow emissions excited by photoelectrons originating in the magnetically conjugate hemisphere are observed by the ICON missionConjugate photoelectron energy spectra are derived for the first time using global scale far‐ultraviolet and radio‐occultation observationsComparison of estimated photoelectron fluxes with measurements on a rocket flight shows consistent characteristics at all altitudes Nightglow emissions excited by photoelectrons originating in the magnetically conjugate hemisphere are observed by the ICON mission Conjugate photoelectron energy spectra are derived for the first time using global scale far‐ultraviolet and radio‐occultation observations Comparison of estimated photoelectron fluxes with measurements on a rocket flight shows consistent characteristics at all altitudes

The Far Ultra Violet (FUV) ultraviolet imager onboard the NASA‐ICON mission is dedicated to the observation and study of the ionosphere dynamics at mid and low latitudes. We compare O+density profiles provided by the ICON FUV instrument during nighttime with electron density profiles measured by the COSMIC‐2 constellation (C2) and ground‐based ionosondes. Co‐located simultaneous observations are compared, covering the period from November 2019 to July 2020, which produces several thousands of coincidences. Manual scaling of ionogram sequences ensures the reliability of the ionosonde profiles, while C2 data are carefully selected using an automatic quality control algorithm. Photoelectron contribution coming from the magnetically conjugated hemisphere is clearly visible in FUV data around solstices and has been filtered out from our analysis. We find that the FUV observations are consistent with the C2 and ionosonde measurements, with an average positive bias lower than 1 × 1011e/m3. When restricting the analysis to cases having an NmF2value larger than 5 × 1011e/m3, FUV provides the peak electron density with a mean difference with C2 of 10%. The peak altitude, also determined from FUV observations, is found to be 15 km above that obtained from C2, and 38 km above the ionosonde value on average. We compare ICON‐FUV NmF2 and hmF2 observations with those provided by COSMIC‐2 and ionosondesFar Ultra Violet Imaging Spectrograph (FUV) observations are affected by conjugate photoelectrons mainly around solsticesThe FUV performance during nighttime allows for reliable electron density measurement We compare ICON‐FUV NmF2 and hmF2 observations with those provided by COSMIC‐2 and ionosondes Far Ultra Violet Imaging Spectrograph (FUV) observations are affected by conjugate photoelectrons mainly around solstices The FUV performance during nighttime allows for reliable electron density measurement

No abstracts.

Analysis of conjugate data from extended magnetometer networks in northern and southern high latitudes is used to elucidate the initiation and the evolution of a magnetic impulse event (MIE) on June 6, 1997. In addition, data from all‐sky imagers, imaging riometers, and Super Dual Auroral Radar Network radars in Antarctica are investigated to confirm the energy content, motion, and electrical current structure of the MIE. The MIE was accompanied by traveling convection vortices (TCVs) that began at ∼10 MLT and moved eastward (toward dusk) and slightly equatorward at 1–3 km/s across the noon meridian with north‐south conjugacy. The MIE had upward field‐aligned currents with soft electron precipitation that was located near the trailing edge of the Hall current loop. During the MIE interval the interplanetary magnetic field (IMF) was directed strongly outward from the Sun (Bx= −5 nT), with a slightly positive (1–2 nT) Bz, and a nearly zero By. Since abrupt solar wind pressure changes are unlikely under this IMF orientation (and none was, in fact, observed), classical mechanisms for MIE generation, such as a pressure pulse or dayside reconnection, are excluded. It is speculated that an abrupt IMF cone angle change from 60° to 20°, ∼30 min prior to the MIE onset, may have been an indirect trigger of this event via the interaction between the solar wind and the bow shock.

Sudden, short‐lived dayside auroral activity is often observed equatorward of the quiescent auroral oval. Several cases from the 1996 South Pole and United States Automatic Geophysical Observatory data were examined. In all cases the optical events were accompanied by well‐correlated magnetic impulsive events. Most optical auroral activity was primarily in 630‐nm emission (soft electron precipitation presumably of plasma sheet or magnetosheath origin). Most optical events also show the presence of much shorter lived 427.8‐nm emission (harder electron precipitation with associated electron acceleration). In almost all events the keograms showed repeated poleward propagation, indicating that the event started at lower latitudes and propagated to higher latitudes. The optical emissions showed distinct periodicities, which usually correlated well with the magnetic signature. All the events began equatorward of the preexisting quiescent aurora, indicating that they initiated in the region of closed field lines. The interplanetary magnetic field Bzcomponent prior to the events was either small or positive in most cases. The majority of the observed events were consistent with being triggered by interplanetary Bzor solar wind pressure change. For some events, no specific trigger was found.

To investigate the dynamics of auroras and faint upper atmospheric emissions, a new type of imaging instrument was developed. The instrument is a wide field of view, narrow-spectral-band imaging system using an intensified S.E.C. TV camera in a time exposure mode. Pictures were taken at very low light levels of a few photons per exposure per resolution element. These pictures are displayed in the form of a pseudocolor presentation in which the color represents spectral ratios of two of the observed auroral spectral emission features. The spectral ratios play an important part in the interpretation of auroral particle dynamics. A digital picture processing facility is also part of the system which enables the digital manppulation of the pictures at standard TV rates. As an example, hydrogen auroras can be displayed having been corrected for nonspectral background by subtracting a picture obtained by a suitable background filter. The instrumentation was calibrated in the laboratory and was used in several field experiments. Elaborate exposure sequences were developed to extend the dynamic range and to cover the large range of auroral brightnesses in a fairly linear manner.

For palliative therapy during the chronic phase of CML busulfan has proved to be the drug of choice. During the past years hydroxyurea and also interferon-alpha have gained increasing significance since they might prolong the duration of the chronic phase. In a multicenter study it is being determined, whether the use of hydroxyurea or of interferon-alpha instead of busulfan prolongs the duration of the chronic phase of Philadelphia positive CML. Additional goals are the examination of whether the types of disease evolution and the terminal phases differ between the treatment groups, and the prospective recognition of prognostic criteria for the duration of the chronic phase of CML. By December 31, 1987, 326 CML-patients had been randomized, 150 for busulfan, 150 for hydroxyurea and 26 for interferon-alpha. The average age is 50 years. 59 patients reached the end of the chronic phase, 55 died. The mean observation time of all patients is 1.34 years. At present no significant difference in survival is recognizable between the busulfan and hydroxyurea groups. Fewer adverse effects have been observed in the hydroxyurea group. Philadelphia chromosome negative patients show a higher average age and tend to have lower white blood cell and platelet counts. The number of patients having received interferon-alpha is still too small to allow evaluation. This report intends to document organization and progress of this study which to our knowledge is, at present, the largest ongoing prospective multicenter study on the therapy of CML.

We have determined the molecular internal energy distribution in the N2B³IIgstate from the fluorescence measured during the observations of sprites during 1995. Spectrally resolved data from two different instruments and three different sprites are compared with theoretical spectra to obtain excited state vibrational distributions. Energy dependent electron excitation cross‐sections and laboratory data were used to estimate the energies of electrons producing the red sprite radiance. Implications for chemical production in the mesosphere and critical future measurements are discussed.

It is demonstrated that for maximizing the scientific output of future ionospheric and magnetospheric ion cloud release experiments a new type of instrument is required which will measure the line-of-sight velocity of the ion cloud by the Doppler technique. A simple instrument was constructed using a 5-cm diam solid Fabry-Perot etalon coupled to a low-light-level integrating TV camera. It was demonstrated that the system has both the sensitivity and spectral resolution for detection of ion clouds and measurement of their line-of-sight Doppler velocity. The tests consisted of (1) a field experiment using a rocket barium cloud release to check sensitivity, and (2) laboratory experiments to show the spectral resolving capabilities of the system. The instrument was found to be operational if the source was brighter than ~1 kR, and it had a wavelength resolution much better than 0.2 Å, which corresponds to ~12 km/sec or in the case of barium ion an acceleration potential of 100 V. The instrument is rugged and, therefore, simple to use in field experiments or on flight instruments. The sensitivity limit of the instrument can be increased by increasing the size of the etalon.

In a conventional grating spectrograph consisting of a single entrance slit, a grating, and a multichannel (imaging) detector, considerable light throughput advantage can be realized by replacement of the single entrance slit with a mask. This replacement can yield a signal-to-noise ratio increase because of increased light collection over an extended area of the mask when compared with a single slit. The mask produces a spectrum on the detector, which is the convolution of the mask pattern and the spectral distribution of the light source. To retrieve the spectrum, the spectrum has to be inverted. In special cases in which emission spectra are superimposed on weak backgrounds, the signal-to-noise advantage is preserved through the inversion process. Thus this technique is valuable in the observation of light sources that are produced by atomic or molecular emissions such as aurora, airglow, some interstellar emission, or laboratory spectra. Considerable signal-to-noise advantages can also be realized when the background noise of the imaging detector is not negligible. The spectral mixing of the light from the mask on the detector causes high photon fluxes on the detector, which tend to swamp the detector noise. This is a particularly important advantage in the application of CCD’s as detectors because they can have significant background noise. The technique was demonstrated by computer simulations and laboratory tests.

Summary In ten patients with IRSA, chromosome analysis and bone marrow cytology were performed once or several times during 24 months. Bone marrow chromosomes from eight patients showed a normal karyotype. Two patients were found to have stable clonal chromosome aberrations (45, X, -Y [male] and 46, XX, + mar). In a median duration of 6.8 years of IRSA no patient has yet developed acute leukemia. In another ten deceased patients with IRSA no evidence of leukemia, but a carcinoma of colon and prostate were observed in a latency of 7.7 years.

Zusammenfassung 44 Patienten mit myelomonozytärer Leukämie (MML) wurden während der letzten vier Jahre beobachtet. Eine Einteilung in akute myelomonozytäre und akute monoblastäre Leukämien (AMML, n = 12; AMoL, n = 10), subakute myelomonozytäre Leukämien (SMML, n = 13) und chronische myelomonozytäre Leukämien (CMML, n = 9) wurde aufgrund der Knochenmarkzytologie (Blasten- und Promonozytenanteil, Ausreifung der Granulopoese) und zytochemischer Befunde (Peroxydase- und unspezifische Esterase-Reaktion) vorgenommen. Diese Einteilung erwies sich als prognostisch relevant durch eine gute Korrelation mit den mittleren Überlebenszeiten (AMML: 4,5 Monate, AMoL: 2,4 Monate, SMML: 8 Monate, CMML: 18 Monate). Die akuten Verlaufsformen wurden in der Regel kombiniert zytostatisch behandelt, während SMML und CMML nur beim Übergang in eine akute Phase zytostatisch therapiert wurden. Derartige Übergänge in AMML wurden bei den subakuten Verlaufsformen häufiger und eher als bei den chronischen beobachtet. Zur Diagnose SMML, CMML trägt das Vorkommen seeblauer Histiozyten im Knochenmark, eine Lysozymerhöhung in Serum und Urin und das Fehlen des Philadelphia-Chromosoms bei.

Summary Drug resistance is a major problem in chemotherapy of squamous cell head and neck cancers (SCHNC). Since glutathione (GSH) plays a crucial role in mediating tumor cell resistance against various toxic insults, GSH metabolism in SCHNC xenografts was investigated. Xenografts from lymph node metastases contained markedly higher GSH concentrations compared with those derived from the corresponding primary lesions. After subcurative chemotherapy with cisplatin (DDP), a significant increase of both GSH levels and γ-glutamyltranspeptidase activity (γ-GT) was gained in tumor HT1M. Tumor HT3M showed high concentrations of GSH and γ-GT, although these latter concentrations did not increase following chemotherapy with DDP. These findings suggest a possible impact of GSH metabolism on both the formation of metastases and the phenomenon of drug resistance in SCHNC.

The glow on ram surfaces of the space shuttle has been reported from a series of photographic observations made during several orbiter missions1–13. These measurements have shown that the spectrum of the glow is a continuum7,13, has a spectral peak at 680 nm4,7, and the brightness decreases with altitude5. The spectrum has been tentatively identified as the nitrogen dioxide continuum and follows the interaction of adsorbed nitric oxide with ramming atmospheric oxygen7–9. One recent observation of the ram glow displayed an unusually low intensity10,13. Further investigation has led us to discover that the main difference between this, and earlier measurements was the spacecraft attitude which in turn significantly influenced the temperature of the ram surfaces observed. In this paper the variation of the glow brightness among several different shuttle flights is re-examined and it is shown that a major contributing factor to glow brightness is probably the temperature of the rammed surface. The derived temperature dependence is also consistent with the Atmospheric Explorer-C satellite ‘red’ glow intensity data.

A linear self-scanning array of 512 elements was exposed to photoelectron bombardment in a Kron camera tube. This is a demountable tube in which the photocathode and the electron focal plane can be separated by means of a special coin valve. The diode array was mounted in the electron optical focal plane. The video signal amplitude distributions were analyzed when the diode array was exposed to electrons between 30 keV and 35 keV. The distribution of the signals due to single electrons could be resolved from the distribution of signals when no photoelectrons were present. The impairment of the SNR due to the lack of perfect resolution of the distributions amounts to no more than the loss of a few percent of the photoelectrons. The result of these tests encourages the immediate application of the diode array Kron tube spectrography to high resolution spectroscopy of very faint objects.

A unique multichannel photoelectron counting system can be made by using self-scanning semiconductor arrays in the electron bombardment induced mode provided the SNR in the self-scanning arrays permits the detection of single electrons. To investigate this in an experimental program, self-scanning light sensitive diode arrays were subjected to electron bombardment. In one experiment, a radioactive source Ni^63 was used to show that the 128 element (Reticon RL128L) self-scanned linear diode arrays were responsive to electrons, and good agreement could be derived between the high energy portion of the incident and measured fluxes. In another experiment using an electron accelerator and 42-keV electrons, clear resolution of the pulse distribution peaks was obtained due to single, double, and triple incidences of electrons. The relative heights of the observed peaks obeyed a Poisson distribution as expected for random electron incidence. The incorporation of this device into a photoelectronic tube will result in a self-scanned photoelectronic detector closely approaching the theoretical performance limit.

The use of simple photographic cameras on early Shuttle missions allowed spacecraft glow to be clearly identified, and its potential for the contamination of weak atmospheric emissions to be estimated. Since those early flights the equipment has been extensively modified so that it is now possible to obtain images with a spectral resolution of 0.1 nm. The early Shuttle glow observations are reviewed and the use of spatially scanned filters to obtain spectral results is described. These glow measurements are discussed in terms of some current ideas for vehicle induced glows and it is suggested that the glow intensity may be controlled by the temperature of the glowing surface. An example of an atmospheric image obtained with the interference filter camera is presented and the limitations in the use of such images are discussed.

A high sensitivity satellite-borne television camera has been developed to measure such faint light sources as auroras. A secondary electron conduction (SEC) television camera tube is used as the image sensor. In the present application for the Rice/NASA satellites code-named Owls, the tube is exposed by the application of a high voltage pulse of 0.1 sec or 0.2 sec duration. The picture is scanned for about 19 sec, and the video is digitized in synchronism with the satellite PCM system. The television data are then telemetered to the ground either real time or stored in one of the tape recorders. The optical system superimposes star images on the picture for azimuthal aspect reference. The sensitivity of the slow scan camera was measured; it agrees with the sensitivity of a camera scanning at normal scan rate. Comparison was made of the relative sensitivity of the camera at the wavelength of the three most important auroral components. The camera has sensitivity comparable with the dark-adapted human eye. The weight of the system is 3.9 kg, and the power dissipation is 3.9 W.

A combination of a four-stage cascaded image intensifier and a plumbicon television camera system was used to record photoelectrons from faint images. The lens coupled system needs image intensifier gains of the order of 10^6 to overcome TV camera noise by single photoelectron scintillations. The properties of the system were evaluated with special emphasis on recording efficiency. The recorded pulse height distribution was analyzed, and it was shown that inefficiencies in the TV sampling process produce an exponential pulse height distribution.

Abstract: In cases of complicated identifications the neutron activation analysis of dental metals may inform more than usual descriptions of the teeth including X-rays. Identifications would become more effective in the field of forensic stomatology by adding “pilot” elements into the alloys of dental metals by the factories. The neutron activation analysis of dental metals from Halsbrücke (GDR) are discussed and compared with spectral analyses.

Summary Extraordinary platelet adherence to polymorphonuclear leukocytes was seen in EDTA anticoagulated blood smears of two patients. From the same blood samples platelets were greatly reduced in number. Platelet satellitism (granulocyte platelet rosettes) is a rare phenomenon in vitro, only seen in EDTA anticoagulated blood, and the platelets surrounded polymorphonuclear leukocytes only. Phagocytosis of platelets was also observed. The cause of platelet satellitism is unknown. Capillary blood should be investigated in order to prevent a false thrombocytopenia.

The Imager of Sprites and Upper Atmospheric Lightnings (ISUAL) often recorded events that have significant far‐ultraviolet (FUV) emissions in the spectrophotometer but have no discernible transient luminous events (TLEs) in the imager. These FUV events likely are dim TLEs. To confirm the conjecture, lightning emissions were simulated and proved to be completely absorbed by the atmosphere. The FUV emission of the FUV events follows the lightning OI emission within 1 ms, similar to the characteristics of elves. After analyzing the imager‐N21P brightness of the elves and their FUV intensity, a linear correlation was found, which is consistent with the work of Kuo et al. (2007). The intensity of the FUV events ranks among the dimmest elves and is less than 1 × 104photons/cm2. Combining all the information, the FUV events are identified as dim elves that eluded the detection of the ISUAL imager. Also from the detection limits of the ISUAL spectrophotometer (SP) and the imager, for the before‐the‐limb elves the detection number of SP is found to be nearly 16 times higher than that of the imager. This result is consistent with a related factor of ∼13 that was inferred from the U.S. National Lightning Detection Network (NLDN) peak current distribution for the negative cloud‐to‐ground lightning. Hence the ISUAL spectrophotometer can be used to perform elve survey, to infer the peak current of the elve‐producing lightning, and possibly to be used to deduce other lightning parameters. Evidence is also found for the existence of multielves, which are FUV events from the M‐components or the multiple strokes in lightning flashes.

The ISUAL gigantic jets (GJs) are categorized into three types from their generating sequence and spectral properties. Generating sequence of the type I GJs resembles that reported previously; after the fully developed jet (FDJ) established the discharge channel, the ISUAL photometers registered a peak that was from a return‐stroke‐like process. The associated ULF (ultra‐low‐frequency) sferics of these type I GJs indicates that they are negative cloud‐to‐ionosphere discharges (−CIs). Type II GJs begin as blue jets and then developed into GJs in ∼100 ms. Blue jets also frequently occurred at the same region before and after the type II GJs. No identifiable ULF sferics of the type II GJs were found, though an extra event that has +CI ULF signature is probably a type II GJ. The FDJ streamer brightness of the type I GJs is ∼3.4 times of that of the type II GJs. These evidences suggest that the type II GJs are composed of positive streamers. Type III GJs were preceded by lightning, and a GJ subsequently occurred near this preceding lightning. The spectral data of the type III GJs are dominated by lightning signals and the ULF data have high background noise; thus both cannot be properly analyzed. However, the average brightness of the type III GJs falls between those of the other two types of GJs. We propose that the discharge polarity of the type III GJs can be either negative or positive, depending on the type of the charge imbalance left by the trigger lightning.

A critical, long‐standing problem in substorm research is identification of the sequence of events leading to substorm auroral onset. Based on event and statistical analysis of THEMIS all‐sky imager data, we show that there is a distinct and repeatable sequence of events leading to onset, the sequence having similarities to and important differences from previous ideas. The sequence is initiated by a poleward boundary intensification (PBI) and followed by a north‐south (N‐S) arc moving equatorward toward the onset latitude. Because of the linkage of fast magnetotail flows to PBIs and to N‐S auroras, the results indicate that onset is preceded by enhanced earthward plasma flows associated with enhanced reconnection near the pre‐existing open‐closed field line boundary. The flows carry new plasma from the open field line region to the plasma sheet. The auroral observations indicate that Earthward‐transport of the new plasma leads to a near‐Earth instability and auroral breakup ∼5.5 min after PBI formation. Our observations also indicate the importance of region 2 magnetosphere‐ionosphere electrodynamic coupling, which may play an important role in the motion of pre‐onset auroral forms and determining the local times of onsets. Furthermore, we find motion of the pre‐onset auroral forms around the Harang reversal and along the growth phase arc, reflecting a well‐developed region 2 current system within the duskside convection cell, and also a high probability of diffuse‐appearing aurora occurrence near the onset latitude, indicating high plasma pressure along these inner plasma sheet field lines, which would drive large region 2 currents.

No abstract.

On April 28 2001, simultaneous global images of electron and proton aurora were obtained by IMAGE‐FUV following a sudden increase of solar wind dynamic pressure. The local time and intensity distribution of both types of precipitation are examined and compared. It is found that the electron and the proton precipitation both start in the post noon sector and expand concurrently, but the expansion into the nightside starts sooner for the protons than for the electrons. The characteristic rise time in the onset sector is on the order of 6 minutes. A distinct dynamics and morphology of electron and proton precipitation is observed in the nightside sector. DMSP electron measurements in the afternoon sector indicate that the shock has a significant effect on the electron spectral characteristics. It is suggested that the various Alfven frequencies generated by the shock account for the two different speeds of propagation of the disturbance.

No abstract.