Oxygen torus and its coincidence with EMIC wave in the deep inner magnetosphere: Van Allen Probe B and Arase observations.

We investigate the longitudinal structure of the oxygen torus in the inner magnetosphere for a specific event found on 12 September 2017, using simultaneous observations from the Van Allen Probe B and Arase satellites. It is found that Probe B observed a clear enhancement in the average plasma mass (M) up to 3-4 amu at L = 3.3-3.6 and magnetic local time (MLT) = 9.0 h. In the afternoon sector at MLT ~ 16.0 h, both Probe B and Arase found no clear enhancements in M. This result suggests that the oxygen torus does not extend over all MLT but is skewed toward the dawn. Since a similar result has been reported for another event of the oxygen torus in a previous study, a crescent-shaped torus or a pinched torus centered around dawn may be a general feature of the O+ density enhancement in the inner magnetosphere. We newly find that an electromagnetic ion cyclotron (EMIC) wave in the H+ band appeared coincidently with the oxygen torus. From the lower cutoff frequency of the EMIC wave, the ion composition of the oxygen torus is estimated to be 80.6% H+, 3.4% He+, and 16.0% O+. According to the linearized dispersion relation for EMIC waves, both He+ and O+ ions inhibit EMIC wave growth and the stabilizing effect is stronger for He+ than O+. Therefore, when the H+ fraction or M is constant, the denser O+ ions are naturally accompanied by the more tenuous He+ ions, resulting in a weaker stabilizing effect (i.e., larger growth rate). From the Probe B observations, we find that the growth rate becomes larger in the oxygen torus than in the adjacent regions in the plasma trough and the plasmasphere.

Rapid local acceleration of relativistic radiation-belt electrons by magnetospheric chorus.

Recent analysis of satellite data obtained during the 9 October 2012 geomagnetic storm identified the development of peaks in electron phase space density, which are compelling evidence for local electron acceleration in the heart of the outer radiation belt, but are inconsistent with acceleration by inward radial diffusive transport. However, the precise physical mechanism responsible for the acceleration on 9 October was not identified. Previous modelling has indicated that a magnetospheric electromagnetic emission known as chorus could be a potential candidate for local electron acceleration, but a definitive resolution of the importance of chorus for radiation-belt acceleration was not possible because of limitations in the energy range and resolution of previous electron observations and the lack of a dynamic global wave model. Here we report high-resolution electron observations obtained during the 9 October storm and demonstrate, using a two-dimensional simulation performed with a recently developed time-varying data-driven model, that chorus scattering explains the temporal evolution of both the energy and angular distribution of the observed relativistic electron flux increase. Our detailed modelling demonstrates the remarkable efficiency of wave acceleration in the Earth's outer radiation belt, and the results presented have potential application to Jupiter, Saturn and other magnetized astrophysical objects.

Intense chorus waves are the cause of flux-limiting in the heart of the outer radiation belt.

Chorus waves play a key role in outer Van Allen electron belt dynamics through cyclotron resonance. Here, we use Van Allen Probes data to reveal a new and distinct population of intense chorus waves excited in the heart of the radiation belt during the main phase of geomagnetic storms. The power of the waves is typically ~ 2-3 orders of magnitude greater than pre-storm levels, and are generated when fluxes of ~ 10-100 keV electrons approach or exceed the Kennel-Petschek limit. These intense chorus waves rapidly scatter electrons into the loss cone, capping the electron flux to a value close to the limit predicted by Kennel and Petschek over 50 years ago. Our results are crucial for understanding the limits to radiation belt fluxes, with accurate models likely requiring the inclusion of this chorus wave-driven flux-limiting process, that is independent of the acceleration mechanism or source responsible for enhancing the flux.

Collaborative Research Activities of the Arase and Van Allen Probes.

This paper presents the highlights of joint observations of the inner magnetosphere by the Arase spacecraft, the Van Allen Probes spacecraft, and ground-based experiments integrated into spacecraft programs. The concurrent operation of the two missions in 2017-2019 facilitated the separation of the spatial and temporal structures of dynamic phenomena occurring in the inner magnetosphere. Because the orbital inclination angle of Arase is larger than that of Van Allen Probes, Arase collected observations at higher L -shells up to L ∼ 10 . After March 2017, similar variations in plasma and waves were detected by Van Allen Probes and Arase. We describe plasma wave observations at longitudinally separated locations in space and geomagnetically-conjugate locations in space and on the ground. The results of instrument intercalibrations between the two missions are also presented. Arase continued its normal operation after the scientific operation of Van Allen Probes completed in October 2019. The combined Van Allen Probes (2012-2019) and Arase (2017-present) observations will cover a full solar cycle. This will be the first comprehensive long-term observation of the inner magnetosphere and radiation belts.

The Magnetic Electron Ion Spectrometer: A Review of On-Orbit Sensor Performance, Data, Operations, and Science.

Measurements from NASA's Van Allen Probes have transformed our understanding of the dynamics of Earth's geomagnetically-trapped, charged particle radiation. The Van Allen Probes were equipped with the Magnetic Electron Ion Spectrometers (MagEIS) that measured energetic and relativistic electrons, along with energetic ions, in the radiation belts. Accurate and routine measurement of these particles was of fundamental importance towards achieving the scientific goals of the mission. We provide a comprehensive review of the MagEIS suite's on-orbit performance, operation, and data products, along with a summary of scientific results. The purpose of this review is to serve as a complement to the MagEIS instrument paper, which was largely completed before flight and thus focused on pre-flight design and performance characteristics. As is the case with all space-borne instrumentation, the anticipated sensor performance was found to be different once on orbit. Our intention is to provide sufficient detail on the MagEIS instruments so that future generations of researchers can understand the subtleties of the sensors, profit from these unique measurements, and continue to unlock the mysteries of the near-Earth space radiation environment. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s11214-021-00855-2.

The FIREBIRD-II CubeSat mission: Focused investigations of relativistic electron burst intensity, range, and dynamics.

FIREBIRD-II is a National Science Foundation funded CubeSat mission designed to study the scale size and energy spectrum of relativistic electron microbursts. The mission consists of two identical 1.5 U CubeSats in a low earth polar orbit, each with two solid state detectors that differ only in the size of their geometric factors and fields of view. Having two spacecraft in close orbit allows the scale size of microbursts to be investigated through the intra-spacecraft separation when microbursts are observed simultaneously on each unit. Each detector returns high cadence (10 s of ms) measurements of the electron population from 200 keV to >1 MeV across six energy channels. The energy channels were selected to fill a gap in the observations of the Heavy Ion Large Telescope instrument on the Solar, Anomalous, and Magnetospheric Particle Explorer. FIREBIRD-II has been in orbit for 5 years and continues to return high quality data. After the first month in orbit, the spacecraft had separated beyond the expected scale size of microbursts, so the focus has shifted toward conjunctions with other magnetospheric missions. FIREBIRD-II has addressed all of its primary science objectives, and its long lifetime and focus on conjunctions has enabled additional science beyond the scope of the original mission. This paper presents a brief history of the FIREBIRD mission's science goals, followed by a description of the instrument and spacecraft. The data products are then discussed along with some caveats necessary for proper use of the data.

A Revised Look at Relativistic Electrons in the Earth's Inner Radiation Zone and Slot Region.

We describe a new, more accurate procedure for estimating and removing inner zone background contamination from Van Allen Probes Magnetic Electron Ion Spectrometer (MagEIS) radiation belt measurements. This new procedure is based on the underlying assumption that the primary source of background contamination in the electron measurements at L shells less than three, energetic inner belt protons, is relatively stable. Since a magnetic spectrometer can readily distinguish between foreground electrons and background signals, we are able to exploit the proton stability to construct a model of the background contamination in each MagEIS detector by only considering times when the measurements are known to be background dominated. We demonstrate, for relativistic electron measurements in the inner zone, that the new technique is a significant improvement upon the routine background corrections that are used in the standard MagEIS data processing, which can "overcorrect" and therefore remove real (but small) electron fluxes. As an example, we show that the previously reported 1-MeV injection into the inner zone that occurred in June of 2015 was distributed more broadly in L and persisted in the inner zone longer than suggested by previous estimates. Such differences can have important implications for both scientific studies and spacecraft engineering applications that make use of MagEIS electron data in the inner zone at relativistic energies. We compare these new results with prior work and present more recent observations that also show a 1-MeV electron injection into the inner zone following the September 2017 interplanetary shock passage.

RBSP-ECT Combined Spin-Averaged Electron Flux Data Product.

We describe a new data product combining the spin-averaged electron flux measurements from the Radiation Belt Storm Probes (RBSP) Energetic Particle Composition and Thermal Plasma (ECT) suite on the National Aeronautics and Space Administration's Van Allen Probes. We describe the methodology used to combine each of the data sets and produce a consistent set of spectra for September 2013 to the present. Three-minute-averaged flux spectra are provided spanning energies from 15 eV up to 20 MeV. This new data product provides additional utility to the ECT data and offers a consistent cross calibrated data set for researchers interested in examining the dynamics of the inner magnetosphere across a wide range of energies.

Transcription factors control invasion: AP-1 the first among equals.

Metastasis, the aggressive spread of a malignant tumor to distant organs, is a major cause of death in cancer patients. Despite this critical role in cancer outcomes, the molecular mechanisms that control this process are just beginning to be understood. Metastasis is largely dependent upon the ability of tumor cells to invade the barrier formed by the basement membrane and to migrate through neighboring tissues. This review will summarize the evidence that tumor cell invasion is the result of oncogene-mediated signal transduction pathways that control the expression of a specific set of genes that together mediate tumor cell invasion. We focus on the role of the transcription factor AP-1 to both induce the expression of genes that function as invasion effectors and repress other genes that function as invasion suppressors. This identifies AP-1 as a critical regulator of a complex program of gene expression that defines the invasive phenotype.

Energization of the Ring Current by Substorms.

The substorm process releases large amounts of energy into the magnetospheric system, although where the energy is transferred to and how it is partitioned remains an open question. In this study, we address whether the substorm process contributes a significant amount of energy to the ring current. The ring current is a highly variable region, and understanding the energization processes provides valuable insight into how substorm-ring current coupling may contribute to the generation of storm conditions and provide a source of energy for wave driving. In order to quantify the energy input into the ring current during the substorm process, we analyze Radiation Belt Storm Probes Ion Composition Experiment and Helium Oxygen Proton Electron ion flux measurements for H+, O+, and He+. The energy content of the ring current is estimated and binned spatially for L and magnetic local time. The results are combined with an independently derived substorm event list to perform a statistical analysis of variations in the ring current energy content with substorm phase. We show that the ring current energy is significantly higher in the expansion phase compared to the growth phase, with the energy enhancement persisting into the substorm recovery phase. The characteristics of the energy enhancement suggest the injection of energized ions from the tail plasma sheet following substorm onset. The local time variations indicate a loss of energetic H+ ions in the afternoon sector, likely due to wave-particle interactions. Overall, we find that the average energy input into the ring current is ∼9% of the previously reported energy released during substorms.

What effect do substorms have on the content of the radiation belts?

Substorms are fundamental and dynamic processes in the magnetosphere, converting captured solar wind magnetic energy into plasma energy. These substorms have been suggested to be a key driver of energetic electron enhancements in the outer radiation belts. Substorms inject a keV "seed" population into the inner magnetosphere which is subsequently energized through wave-particle interactions up to relativistic energies; however, the extent to which substorms enhance the radiation belts, either directly or indirectly, has never before been quantified. In this study, we examine increases and decreases in the total radiation belt electron content (TRBEC) following substorms and geomagnetically quiet intervals. Our results show that the radiation belts are inherently lossy, shown by a negative median change in TRBEC at all intervals following substorms and quiet intervals. However, there are up to 3 times as many increases in TRBEC following substorm intervals. There is a lag of 1-3 days between the substorm or quiet intervals and their greatest effect on radiation belt content, shown in the difference between the occurrence of increases and losses in TRBEC following substorms and quiet intervals, the mean change in TRBEC following substorms or quiet intervals, and the cross correlation between SuperMAG AL (SML) and TRBEC. However, there is a statistically significant effect on the occurrence of increases and decreases in TRBEC up to a lag of 6 days. Increases in radiation belt content show a significant correlation with SML and SYM-H, but decreases in the radiation belt show no apparent link with magnetospheric activity levels.

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

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.

Krp1, a novel kelch related protein that is involved in pseudopod elongation in transformed cells.

We have previously shown that the transcription factor AP-1 regulates the expression of genes which allow neoplastically transformed rat fibroblasts to become invasive. Searches for further AP-1 target genes led to the identification of a gene encoding a novel rat kelch family member, named kelch related protein 1 (Krp1). Kelch family members are characterized by a series of repeats at their carboxyl terminus and a BTB/POZ domain near their amino terminus. Rat Krp1 has a primarily cytoplasmic localization, and a small fraction appears to accumulate and co-localize with F-actin at membrane ruffle-like structures in the tips of pseudopodia. Overexpression of Krp1 in transformed rat fibroblasts led to the formation of dramatically elongated pseudopodia, while expression of truncated Krp1 polypeptides resulted in a reduction in the length of pseudopodia. We propose that the transformation-specific expression of Krp1 is required for pseudopod elongation, which are structures that are required for cell motility and invasion.

Regulation of a multigenic invasion programme by the transcription factor, AP-1: re-expression of a down-regulated gene, TSC-36, inhibits invasion.

The transcription factor AP-1 (activator protein-1) is required for transformation by many oncogenes, which function upstream of it in the growth factor-ras signal transduction pathway. Previously, we proposed that one role of AP-1 in transformation is to regulate the expression of a multigenic invasion programme. As a test of this proposal we sought to identify AP-1 regulated genes based upon their differential expression in 208F rat fibroblasts transformed by FBR-v-fos (FBR), and to determine if they functioned in the invasion programme. Subtracted cDNA libraries specific for up- or down-regulated genes in FBRs compared to 208Fs were constructed and analysed. Northern analysis revealed that the cDNAs in both libraries represented differentially expressed genes. Nucleic acid sequence analysis of randomly selected cDNA clones from each library coupled with searches of nucleic acid and amino acid sequence databases determined that many of the cDNAs represented proteins that function in various aspects of the invasion process. Functional analysis of one the down-regulated genes, TSC-36/follistatin-related protein (TSC-36/Frp), which has not previously been associated with invasion, demonstrated that its expression in FBRs inhibited in vitro invasion. These results support the proposal that AP-1 in transformed cells regulates a multigenic invasion programme.

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

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.

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

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.

Molecular cloning of a human thyrotropin receptor cDNA fragment. Use of highly degenerate, inosine containing primers derived from aligned amino acid sequences of a homologous family of glycoprotein hormone receptors.

Autoantibodies to the thyrotropin (TSH) hormone receptor (TSH-R) are present in the sera of patients with thyroid autoimmune disease which are pathogenetic leading to hyperthyroidism of Graves' disease. Considerable interest has been focused on the cloning of the human TSH-R, which has until very recently, proven exceedingly difficult due to the very low receptor level expression on thyroid cells. We have used polymerase chain reaction and highly degenerate, inosine containing oligonucleotides derived from sequence alignments of the transmembrane regions 2 and 7 of a number of G-binding protein receptors including the lutropin/choriogonadotropin (LH/CG) receptors to amplify various cDNAs from human thyroid cDNA. Sequencing analysis of 27 different clones revealed that they fall into eight different groups. The very recent publication of the complete nucleotide sequence of the human TSH-R revealed that one of the groups (GT1) containing seven clones which had been sequenced belong to the human TSH-receptor. The sequence of all 7 GT1 clones was identical and in complete concordance with transmembrane regions 2 and 7 of the published TSH-R sequence. Our results show that by designing oligonucleotides to common transmembrane regions of G-binding proteins where the primers are biased in their sequence to the LH/CG receptors it is possible to amplify the TSH-R receptor sequence.

Transcriptional regulation of cell invasion: AP-1 regulation of a multigenic invasion programme.

The focus of this review will be on the regulation of the multigenic invasion programme by activator protein-1 (AP-1). Investigation of AP-1-regulated gene expression in transformed cells can be used to identify the genes in the multigenic invasion programme and to validate them as targets for diagnosis or therapy.

The magnocellular neurons of the hypothalamo-neurohypophyseal system display remarkable neuropeptidergic phenotypes leading to novel insights in neuronal cell biology.

For decades the magnocellular neurons of the hypothalamo-neurophypophyseal system (HNS), in which either vasopressin or oxytocin are produced and released into the bloodstream, have been playing a pivotal role in fundamental discoveries in the nervous system. The primary structure of vasopressin and oxytocin was the first of all neuropeptides to be published, i.e., in the 1950s by the Nobel prize laureate Du Vigneaud. Moreover, many trend-setting discoveries have their origin in the HNS, which abundantly expresses vasopressin and oxytocin, clearly displays its function and is relatively easily to manipulate. Examples are the phenomenon of coexpression of neuropeptides, patch-clamping of nerve endings, axonal transport of RNA, neuroglia interactions and the behavioral effects. An extraordinarily intriguing example is the homozygous Brattleboro rat, which lacks vasopressin by a germ-line mutation, and has disclosed many of the fundamental characteristics of peptidergic neurons, and neurons in general. In this chapter we will discuss a few of them, in particular the recent data on mutations in vasopressin RNA. It is to be expected that the HNS will retain its informative role in the next decades.

Reed Nesbit and pediatric urology.

OBJECTIVES: To ascertain the pediatric urology experience and contributions of Reed Nesbit, a urologist known primarily as an educator, transurethral resectionist, and prostate expert. METHODS: The writings of Nesbit and appropriate background references were analyzed. RESULTS: Nesbit's contributions to pediatric urology, particularly the Cabot-Nesbit orchidopexy, the buttonhole preputial transposition, the dorsal tunical tuck for chordee, and the elliptical anastomosis were significant. CONCLUSIONS: Nesbit's contributions to pediatric urology were innovative and enduring.