Autogenous and efficient acceleration of energetic ions upstream of Earth's bow shock.

Earth and its magnetosphere are immersed in the supersonic flow of the solar-wind plasma that fills interplanetary space. As the solar wind slows and deflects to flow around Earth, or any other obstacle, a 'bow shock' forms within the flow. Under almost all solar-wind conditions, planetary bow shocks such as Earth's are collisionless, supercritical shocks, meaning that they reflect and accelerate a fraction of the incident solar-wind ions as an energy dissipation mechanism1,2, which results in the formation of a region called the ion foreshock3. In the foreshock, large-scale, transient phenomena can develop, such as 'hot flow anomalies'4-9, which are concentrations of shock-reflected, suprathermal ions that are channelled and accumulated along certain structures in the upstream magnetic field. Hot flow anomalies evolve explosively, often resulting in the formation of new shocks along their upstream edges5,10, and potentially contribute to particle acceleration11-13, but there have hitherto been no observations to constrain this acceleration or to confirm the underlying mechanism. Here we report observations of a hot flow anomaly accelerating solar-wind ions from roughly 1-10 kiloelectronvolts up to almost 1,000 kiloelectronvolts. The acceleration mechanism depends on the mass and charge state of the ions and is consistent with first-order Fermi acceleration14,15. The acceleration that we observe results from only the interaction of Earth's bow shock with the solar wind, but produces a much, much larger number of energetic particles compared to what would typically be produced in the foreshock from acceleration at the bow shock. Such autogenous and efficient acceleration at quasi-parallel bow shocks (the normal direction of which are within about 45 degrees of the interplanetary magnetic field direction) provides a potential solution to Fermi's 'injection problem', which requires an as-yet-unexplained seed population of energetic particles, and implies that foreshock transients may be important in the generation of cosmic rays at astrophysical shocks throughout the cosmos.

High-Energy (>10 MeV) Oxygen and Sulfur Ions Observed at Jupiter From Pulse Width Measurements of the JEDI Sensors.

The Jovian polar regions produce X-rays that are characteristic of very energetic oxygen and sulfur that become highly charged on precipitating into Jupiter's upper atmosphere. Juno has traversed the polar regions above where these energetic ions are expected to be precipitating revealing a complex composition and energy structure. Energetic ions are likely to drive the characteristic X-rays observed at Jupiter (Haggerty et al., 2017, https://doi.org/10.1002/2017GL072866; Houston et al., 2018, https://doi.org/10.1002/2017JA024872; Kharchenko et al., 2006, https://doi.org/10.1029/2006GL026039). Motivated by the science of X-ray generation, we describe here Juno Jupiter Energetic Particle Detector Instrument (JEDI) measurements of ions above 1 MeV and demonstrate the capability of measuring oxygen and sulfur ions with energies up to 100 MeV. We detail the process of retrieving ion fluxes from pulse width data on instruments like JEDI (called "puck's"; Clark, Cohen, et al., 2016, https://doi.org/10.1002/2017GL074366; Clark, Mauk, et al., 2016, https://doi.org/10.1002/2015JA022257; Mauk et al., 2013, https://doi.org/10.1007/s11214-013-0025-3) as well as details on retrieving very energetic particles (>20 MeV) above which the pulse width also saturates.

Pluto's Interaction With Energetic Heliospheric Ions.

Pluto energies of a few kiloelectron volts and suprathermal ions with tens of kiloelectron volts and above. We measure this population using the Pluto Energetic Particle Spectrometer Science Investigation (PEPSSI) instrument on board the New Horizons spacecraft that flew by Pluto in 2015. Even though the measured ions have gyroradii larger than the size of Pluto and the cross section of its magnetosphere, we find that the boundary of the magnetosphere is depleting the energetic ion intensities by about an order of magnitude close to Pluto. The intensity is increasing exponentially with distance to Pluto and reaches nominal levels of the interplanetary medium at about 190R P distance. Inside the wake of Pluto, we observe oscillations of the ion intensities with a periodicity of about 0.2 hr. We show that these can be quantitatively explained by the electric field of an ultralow-frequency wave and discuss possible physical drivers for such a field. We find no evidence for the presence of plutogenic ions in the considered energy range.

Dust grains fall from Saturn's D-ring into its equatorial upper atmosphere.

The sizes of Saturn's ring particles range from meters (boulders) to nanometers (dust). Determination of the rings' ages depends on loss processes, including the transport of dust into Saturn's atmosphere. During the Grand Finale orbits of the Cassini spacecraft, its instruments measured tiny dust grains that compose the innermost D-ring of Saturn. The nanometer-sized dust experiences collisions with exospheric (upper atmosphere) hydrogen and molecular hydrogen, which forces it to fall from the ring into the ionosphere and lower atmosphere. We used the Magnetospheric Imaging Instrument to detect and characterize this dust transport and also found that diffusion dominates above and near the altitude of peak ionospheric density. This mechanism results in a mass deposition into the equatorial atmosphere of ~5 kilograms per second, constraining the age of the D-ring.

The Low-Energy Neutral Imager (LENI).

To achieve breakthroughs in the areas of heliospheric and magnetospheric energetic neutral atom (ENA) imaging, a new class of instruments is required. We present a high angular resolution ENA imager concept aimed at the suprathermal plasma populations with energies between 0.5 and 20 keV. This instrument is intended for understanding the spatial and temporal structure of the heliospheric boundary recently revealed by Interstellar Boundary Explorer instrumentation and the Cassini Ion and Neutral Camera. The instrument is also well suited to characterize magnetospheric ENA emissions from low-altitude ENA emissions produced by precipitation of magnetospheric ions into the terrestrial upper atmosphere, or from the magnetosheath where solar wind protons are neutralized by charge exchange, or from portions of the ring current region. We present a new technique utilizing ultrathin carbon foils, 2-D collimation, and a novel electron optical design to produce high angular resolution (≤2°) and high-sensitivity (≥10-3 cm2 sr/pixel) ENA imaging in the 0.5-20 keV energy range.

The "Puck" energetic charged particle detector: Design, heritage, and advancements.

Energetic charged particle detectors characterize a portion of the plasma distribution function that plays critical roles in some physical processes, from carrying the currents in planetary ring currents to weathering the surfaces of planetary objects. For several low-resource missions in the past, the need was recognized for a low-resource but highly capable, mass-species-discriminating energetic particle sensor that could also obtain angular distributions without motors or mechanical articulation. This need led to the development of a compact Energetic Particle Detector (EPD), known as the "Puck" EPD (short for hockey puck), that is capable of determining the flux, angular distribution, and composition of incident ions between an energy range of ~10 keV to several MeV. This sensor makes simultaneous angular measurements of electron fluxes from the tens of keV to about 1 MeV. The same measurements can be extended down to approximately 1 keV/nucleon, with some composition ambiguity. These sensors have a proven flight heritage record that includes missions such as MErcury Surface, Space ENvironment, GEochemistry, and Ranging and New Horizons, with multiple sensors on each of Juno, Van Allen Probes, and Magnetospheric Multiscale. In this review paper we discuss the Puck EPD design, its heritage, unexpected results from these past missions and future advancements. We also discuss high-voltage anomalies that are thought to be associated with the use of curved foils, which is a new foil manufacturing processes utilized on recent Puck EPD designs. Finally, we discuss the important role Puck EPDs can potentially play in upcoming missions.

Brain-stem dysfunction in autism. Results of vestibular stimulation.

Responses to vestibular stimulation can, under well-controlled experimental conditions, provide a measure of brain-stem function. Autistic children had significantly longer time constants during the primary nystagmus response and significantly fewer beats during the secondary response than normal children when stimulated with constant angular acceleration in complete darkness. These findings could not be attributed to gross differences in arousal, to developmental retardation, to associated clinical conditions, or to either the influence of vision or habituation. Rather, they are suggestive of a neurophysiologic dysfunction, perhaps involving the brain stem, and may be an expression of the process that underlies those autistic behaviors that suggest faulty modulation of sensory input and motor output. Brain-stem centers modulate both general sensory input and motor excitation and may play a role in the elaboration of the more complex adaptive and motivated behaviors that are also disturbed in autism.

C-band polymorphism: comparison between trisomy 21 cases and mentally retarded controls.

C-banding was done prospectively on 50 Down syndrome (trisomy 21) cases and 50 mentally retarded controls. Heterochromatin was quantitated by measuring the lengths of heterochromatin blocks and comparing these segments to the length of the short arm of chromosome 16 for 1, 9 and 16 heterochromatin, and to the total length of the Y chromosome for the Y heterochromatin in the distal long arm. For the first 30 individuals in each group, there was no difference in the mean lengths of C-band blocks of the 1, 9, 16 and Y chromosomes. For the total sample, there also was no difference between the trisomy 21 cases and controls in the number or size of pericentric inversions involving the heterochromatin blocks of chromosomes 1 and 9. Assuming random segregation of the parental C-band polymorphisms, this study gives no evidence for an association between such polymorphisms of the 1, 9, 16 and Y chromosomes and nondisjunction of chromosome 21.

Minor chromosome variants in child psychiatric patients.

The frequency of minor chromosome variants, as detected by conventional chromosome analysis, was examined among 1,289 child psychiatric patients, of whom one-fourth had only behavioral problems and three-fourths had congenital abnormalities and more severe mental disorders. There was no more than random association between prominent satellites, prominent secondary constrictions or a long Y chromosome, and congenital abnormalities or more severe mental disorders. The frequencies of these chromosome variants were affected by race as has been shown in previous studies. These findings do not support the evidence for a developmental effect of minor variants in man.

Parental reproductive problems and gestational hormonal exposure in autistic and schizophrenic children.

The incidence of infertility and two or more spontaneous abortions was significantly increased in the parents, compared to that reported for the general population, in this pilot survey of 61 patients evaluated for major childhood psychoses. In addition, 18% of our patients had a history of early gestational exposure to progesterone/estrogen compounds (9 patients) and to cortisone (2 patients). This frequency of gestational hormoné exposure was significantly increased over that in normal infants from three published surveys. However, in 5 of the 11 patients with gestational hormonal exposure, the medication was prescribed because of prior parental reproductive problems or bleeding during the current pregnancy. Therefore, it cannot be concluded that the gestational hormonal exposure was causally related to the psychoses present in these patients. In order to obtain more conclusive data, there will need to be continued monitoring of parental reproductive histories and gestational environmental exposures in autistic and schizophrenic children.

Development of the vestibulo-ocular reflex from infancy to adulthood.

The time constants and gains of the vestibulo-ocular reflex were computed from the primary nystagmus evoked by constant angular acceleration in 79 normal infants and children, ranging in age from 2 months to 11 years old, and 10 normal adults. There were significant changes in both time constant and gain in respect to development. The time constants increased while the gains decreased as a function of the logarithm of age. The time constants of the youngest infants were close to the cupular time constant. The lengthening of the time constant with increasing age was discussed in respect to maturation of inhibitory brainstem reticular formation mechanisms.

A mass analysis technique using coincidence measurements from the Interstellar Boundary Explorer-Hi (approximately 0.3- approximately 6 keV) detector.

NASA's Interstellar Boundary Explorer (IBEX) mission, scheduled to launch in October 2008, will make the first observations of charge exchange energetic neutral atoms (ENAs) produced near the edge of the heliosphere. IBEX will measure these ENAs with two ultra-high sensitivity, single-pixel ENA sensors in the energy range of approximately 0.01- approximately 2 keV (IBEX-Lo) and approximately 0.3- approximately 6 keV (IBEX-Hi), respectively. The primary purpose of IBEX is to measure hydrogen ENAs from the outer heliosphere, but it will also be sensitive to heavier species of ENAs produced anywhere throughout the solar system. For this study, we measured the coincidence response of the IBEX-Hi detector section to H, He, N, and O ions. Based on these results, we have developed an innovative technique in estimating the hydrogen to heavy ion ratio in the signal. This new technique can be applied more widely than the IBEX-Hi detector section, and the basic principle may be useful for other, future space and ground-based measurements.

The process of tholin formation in Titan's upper atmosphere.

Titan's lower atmosphere has long been known to harbor organic aerosols (tholins) presumed to have been formed from simple molecules, such as methane and nitrogen (CH4 and N2). Up to now, it has been assumed that tholins were formed at altitudes of several hundred kilometers by processes as yet unobserved. Using measurements from a combination of mass/charge and energy/charge spectrometers on the Cassini spacecraft, we have obtained evidence for tholin formation at high altitudes (approximately 1000 kilometers) in Titan's atmosphere. The observed chemical mix strongly implies a series of chemical reactions and physical processes that lead from simple molecules (CH4 and N2) to larger, more complex molecules (80 to 350 daltons) to negatively charged massive molecules (approximately 8000 daltons), which we identify as tholins. That the process involves massive negatively charged molecules and aerosols is completely unexpected.

Plasma unconjugated estriol values in high-risk pregnancy.

The usefulness of plasma estriol concentrations in the management of high-risk pregnancy is controversial. In this study, serial plasma unconjugated estriol (E3) concentrations determined by radioimmunoassay were evaluated in 321 patients with high-risk pregnancy for correlation with fetal and neonatal performance. A plasma E3 concentration of 4 ng. per milliliter or less in late pregnancy correlated significantly with low one-and five-minute Apgar scores and selected neonatal problems in pregnancies complicated by chronic hypertension and intrauterine growth retardation, with a similar trend for pregnancies complicated by moderate and severe pre-eclampsia. Most perinatal deaths in the study were associated with acute problems which began during labor and delivery, or fetal death occurred before early intervention was practical. Therefore, the perinatal mortality rate is not likely to be influenced by the use of E3 values, and the perinatal mortality rate is not a realistic measure of the usefulness of plasma E3 values in management of high-risk pregnancy. Low plasma E3 values were not always ominous, and for this reason it is suggested that clinical indications and the results of other tests for fetal-placental function be considered along with plasma E3 values in the selection of patients for early delivery to reduce the possibility of inappropriate intervention.

Extensions to pedigree analysis. III. Variance components by the scoring method.

The classic variance components for simple polygenic traits - additive, dominance, and environmental variance - have traditionally been estimated from sample covariances between first-degree relatives. If data is gathered on pedigrees, this statistical procedure wastes information. Recently Elston & Stewart suggested an alternative likelihood procedure that uses all the information in a set of pedigrees. A refinement of their method based on the scoring technique gives rapidly converging maximum likelihood estimates of the variance components and of the male and female means. Tests of statistical hypotheses about the various parameters can then be made by the likelihood ratio method. Furthermore, using classical regression analysis, the estimated parameter values allow prediction of unknown trait values from known trait values within a pedigree. These methods should apply to traits like total finger ridge count and to quantitative measurements associated with disease traits. Since the model postulates independent environmental effects and no assortative mating, its utility in human behaviour genetics seems limited.

Estimation of the variance components for dermal ridge count.

Refinements of the scoring algorithm to estimate variance components from pedigree data are developed. Subsequent to these modifications, heritability estimates were readily obtained from data for over 50 traits, including total finger ridge count reported here. A significant contribution to the total variance of ridge count could be attributed to the effects of dominance, a finding not previously reported for this dermatoglyphic trait.

Blind oxytocin challenge test and perinatal outcome.

A total of 435 oxytocin challenge tests (OCT) were performed on 217 high-risk pregnant patients, and the test results were blinded. The results were correlated with late decelerations of the fetal heart rate during labor, Apgar scores at 5 minutes, a neonatal morbidity score, and perinatal mortality. The incidence of late decelerations during labor was 17% in the negative group, 24% in the suspicious group, and 33% in the positive group. The correlation of OCT results and the various measures of fetal outcome indicated that an individual fetus at risk cannot be identified with a high degree of accuracy since 67% of the tests were false positive and 17% were false negative. Even when the OCT was positive, 61% of infants did not have late decelerations in labor, low Apgar scores, or significant neonatal morbidity. When elective delivery has been decided upon after consideration of all clinical information, induction of labor rather than primary cesarean section is usually indicated. In this study 78% of patients were delivered vaginally with no significant increase of cesarean sections in the positive and suspicious groups as compared with the negative group.

Y chromosome length related to fetal loss.

The Y/20 ratio (length of Y chromosome/length of chromosome 20) was examined among 216 males, 108 of whose wives had a history of repeated abortions (study group), and 108 who were mentally retarded (controls). There was no significant difference in frequency of long Y (Y/20 equal to or greater than 1) between the study group and controls. Also, there was the expected male: female ratio among normal living children of couples in the study group, and the Y/20 ratio was not significantly increased among fathers with abnormal male offspring. However, wives of long Y males were more likely to have at least one abnormal male birth, compared with other wives (this approached statistical significance, p less than 0.08). In addition, a significantly higher frequency of long Y was found in a subset of affected males whose wives had 2 or more spontaneous abortions plus some other abnormal pregnancy outcome. Although the findings reported here do not strongly support a causal relationship, they at least suggest an association between long Y chromosome and abnormal fetal development.

Retention reproducibility of basic drugs in high-performance liquid chromatography on a silica column with a methanol-ammonium nitrate eluent. Batch-to-batch reproducibility of the stationary phase.

The effect of changing the brand and batches of the silica stationary phase used with a methanol-aqueous ammonium nitrate eluent for the high-performance liquid chromatographic separation of basic drugs has been studied. Considerable care had to be taken to obtain a reproducible eluent and the effect of small changes in the concentration of the ammonia solution were examined closely. Large differences in both the capacity factor and relative capacity factors were found for separations on columns packed with four different brands of silica. Significant differences were also observed with columns containing eighteen different batches of Spherisorb S5W, which had been manufactured over a period of several years.

Retention reproducibility of basic drugs in high-performance liquid chromatography on a silica column with a methanol-high-pH buffer eluent. Changes in selectivity with the age of the stationary phase.

The long-term reproducibility of the separation of basic drugs by high-performance liquid chromatography using a silica column with a methanol-high-pH eluent was examined. The relative capacity factors of specific tertiary amines changed systematically compared with the other drugs on storage of the columns for 1 year. The changes were enhanced on storing the column in mobile phase and were accelerated by prolonged washing with water. A comparison of freshly packed columns suggested that similar changes also occurred with the dry silica on storage. These effects may be a contributor to previously observed batch-to-batch differences in the silica.