Resolving Magnetopause Shadowing Using Multimission Measurements of Phase Space Density

Loss mechanisms act independently or in unison to drive rapid loss of electrons in the radiation belts. Electrons may be lost by precipitation into the Earth's atmosphere, or through the magnetopause into interplanetary space-a process known as magnetopause shadowing. While magnetopause shadowing is known to produce dropouts in electron flux, it is unclear if shadowing continues to remove particles in tandem with electron acceleration processes, limiting the overall flux increase. We investigated the contribution of shadowing to overall radiation belt fluxes throughout a geomagnetic storm starting on the 7 September 2017. We use new, multimission phase space density calculations to decipher electron dynamics during each storm phase and identify features of magnetopause shadowing during both the net-loss and the net-acceleration storm phases on sub-hour time scales. We also highlight two distinct types of shadowing; "direct," where electrons are lost as their orbit intersects the magnetopause, and "indirect," where electrons are lost through ULF wave driven radial transport toward the magnetopause boundary.

A diagnosis of the plasma waves responsible for the explosive energy release of substorm onset

During geomagnetic substorms, stored magnetic and plasma thermal energies are explosively converted into plasma kinetic energy. This rapid reconfiguration of Earth's nightside magnetosphere is manifest in the ionosphere as an auroral display that fills the sky. Progress in understanding of how substorms are initiated is hindered by a lack of quantitative analysis of the single consistent feature of onset; the rapid brightening and structuring of the most equatorward arc in the ionosphere. Here, we exploit state-of-the-art auroral measurements to construct an observational dispersion relation of waves during substorm onset. Further, we use kinetic theory of high-beta plasma to demonstrate that the shear Alfven wave dispersion relation bears remarkable similarity to the auroral dispersion relation. In contrast to prevailing theories of substorm initiation, we demonstrate that auroral beads seen during the majority of substorm onsets are likely the signature of kinetic Alfven waves driven unstable in the high-beta magnetotail.

Photochemistry Illuminates Ubiquitous Organic Matter Fluorescence Spectra

Dissolved organic matter (DOM) in aquatic environments forms a vast reservoir of carbon present as a complex supermixture of compounds. An efficient approach to tracking the production and removal of specific DOM fractions is needed across disciplines, for purposes that range from improving global carbon budgets to optimizing water treatment in engineered systems. Although widely used to study DOM, fluorescence spectroscopy has yet to deliver specific fractions with known spectral properties and predictable distributions. Here, we mathematically isolate four visible-wavelength fluorescent fractions in samples from contrasting lake, river, and ocean environments. Using parallel factor analysis (PARAFAC), we show that most measured fluorescence in environmental samples can be explained by ubiquitous spectra with nearly stable optical properties and photodegradation behaviors over environmental pH gradients. Sample extraction changed bulk fluorescence spectra but not the number or shape of underlying PARAFAC components, while photobleaching preferentially removed the two longest-wavelength components. New approaches to analyzing fluorescence data sets incorporating these findings should improve the interpretation of DOM fluorescence and increase its utility for tracing organic matter biogeochemistry in aquatic systems.

Long-lasting poloidal ULF waves observed by multiple satellites and high-latitude SuperDARN radars

Poloidal ultra-low frequency (ULF) waves between 5-10 mHz were observed by multiple satellites and three high-latitude Super Dual Auroral Radar Network (SuperDARN) radars during the recovery phase of a moderate geomagnetic storm on Jan 24-27, 2016. The long-lasting ULF waves were observed in the magnetic field and energetic particle flux perturbations during three successive passes by two Geostationary Operational Environmental Satellites (GOES) through the dayside magnetosphere, during which plasmasphere expansion and refilling were observed by two Time History of Events and Macroscale Interactions during Substorms (THEMIS) probes. The radial magnetic field oscillation was in phase (~ 180° out of phase) with the northward (southward) moving proton flux oscillation at 95 keV, consistent with high-energy drift-bounce resonance signatures of protons with second harmonic poloidal standing Alfvén waves. The longitudinal extent of the waves approached 10 hours in local time on the dayside and gradually decreased with time. High-time resolution (~ 6 s) data from three high-latitude SuperDARN radars show that the wave intensification region was localized in latitude with a radial extent of ~ 135-225 km in the subauroral ionosphere. No signature of these waves were observed by ground-based magnetometers colocated with the GOES satellites suggesting that the poloidal waves were high-m mode and thus screened by the ionosphere. During this interval one of the THEMIS probes observed a bump-on-tail ion distribution at 1-3 keV which we suggest is the source of the long-lasting second harmonic poloidal ULF waves.

Using ultra-low frequency waves and their characteristics to diagnose key physics of substorm onset

Substorm onset is marked in the ionosphere by the sudden brightening of an existing auroral arc or the creation of a new auroral arc. Also present is the formation of auroral beads, proposed to play a key role in the detonation of the substorm, as well as the development of the large-scale substorm current wedge (SCW), invoked to carry the current diversion. Both these phenomena, auroral beads and the SCW, have been intimately related to ultra-low frequency (ULF) waves of specific frequencies as observed by ground-based magnetometers. We present a case study of the absolute and relative timing of Pi1 and Pi2 ULF wave bands with regard to a small substorm expansion phase onset. We find that there is both a location and frequency dependence for the onset of ULF waves. A clear epicentre is observed in specific wave frequencies concurrent with the brightening of the substorm onset arc and the presence of "auroral beads". At higher and lower wave frequencies, different epicentre patterns are revealed, which we conclude demonstrate different characteristics of the onset process; at higher frequencies, this epicentre may demonstrate phase mixing, and at intermediate and lower frequencies these epicentres are characteristic of auroral beads and cold plasma approximation of the "Tamao travel time" from near-earth neutral line reconnection and formation of the SCW.

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.

Statistical characterization of the growth and spatial scales of the substorm onset arc

We present the first multievent study of the spatial and temporal structuring of the aurora to provide statistical evidence of the near-Earth plasma instability which causes the substorm onset arc. Using data from ground-based auroral imagers, we study repeatable signatures of along-arc auroral beads, which are thought to represent the ionospheric projection of magnetospheric instability in the near-Earth plasma sheet. We show that the growth and spatial scales of these wave-like fluctuations are similar across multiple events, indicating that each sudden auroral brightening has a common explanation. We find statistically that growth rates for auroral beads peak at low wave number with the most unstable spatial scales mapping to an azimuthal wavelength λ≈ 1700-2500 km in the equatorial magnetosphere at around 9-12 R_E . We compare growth rates and spatial scales with a range of theoretical predictions of magnetotail instabilities, including the Cross-Field Current Instability and the Shear Flow Ballooning Instability. We conclude that, although the Cross-Field Current instability can generate similar magnitude of growth rates, the range of unstable wave numbers indicates that the Shear Flow Ballooning Instability is the most likely explanation for our observations.

Fluorescence as a potential monitoring tool for recycled water systems: a review

A rapid, highly sensitive and selective detector is urgently required to detect contamination events in recycled water systems - for example, cross-connection events in dual reticulation pipes that recycle advanced treated sewage effluent - as existing technologies, including total organic carbon and conductivity monitoring, cannot always provide the sensitivity required. Fluorescence spectroscopy has been suggested as a potential monitoring tool given its high sensitivity and selectivity. A review of recent literature demonstrates that by monitoring the fluorescence of dissolved organic matter (DOM), the ratios of humic-like (Peak C) and protein-like (Peak T) fluorescence peaks can be used to identify trace sewage contamination in river waters and estuaries, a situation analogous to contamination detection in recycled water systems. Additionally, strong correlations have been shown between Peak T and biochemical oxygen demand (BOD) in rivers, which is indicative of water impacted by microbial activity and therefore of sewage impacted systems. Hence, this review concludes that the sensitive detection of contamination events in recycled water systems may be achieved by monitoring Peak T and/or Peak C fluorescence. However, in such systems, effluent is treated to a high standard resulting in much lower DOM concentrations and the impact of these advanced treatment processes on Peaks T and C fluorescence is largely unknown and requires investigation. This review has highlighted that further work is also required to determine (a) the stability and distinctiveness of recycled water fluorescence in relation to the treatment processes utilised, (b) the impact of matrix effects, particularly the impact of oxidation, (c) calibration issues for online monitoring, and (d) the advanced data analytical techniques required, if any, to improve detection of contamination events.

Time perception and reproduction in young adults with attention deficit hyperactivity disorder

Adults with attention deficit hyperactivity disorder (ADHD; n = 104) were compared with a control group (n = 64) on time estimation and reproduction tasks. Results were unaffected by ADHD subtype or gender. The ADHD group provided larger time estimations than the control group, particularly at long intervals. This became nonsignificant after controlling for IQ. The ADHD group made shorter reproductions than did the control group (15- and 60-s intervals) and greater reproduction errors (12-, 45-, 60-s durations). These differences remained after controlling for IQ and comorbid oppositional defiant disorder, depression, and anxiety. Only the level of anxiety contributed to errors (at 12-s duration) beyond the level of ADHD. Results extended findings on time perception in ADHD children to adults and ruled out comorbidity as the basis of the errors.

Time perception and reproduction in young adults with attention deficit hyperactivity disorder

Adults with attention deficit hyperactivity disorder (ADHD; n = 104) were compared with a control group (n = 64) on time estimation and reproduction tasks. Results were unaffected by ADHD subtype or gender. The ADHD group provided larger time estimations than the control group, particularly at long intervals. This became nonsignificant after controlling for IQ. The ADHD group made shorter reproductions than did the control group (15- and 60-s intervals) and greater reproduction errors (12-, 45-, 60-s durations). These differences remained after controlling for IQ and comorbid oppositional defiant disorder, depression, and anxiety. Only the level of anxiety contributed to errors (at 12-s duration) beyond the level of ADHD. Results extended findings on time perception in ADHD children to adults and ruled out comorbidity as the basis of the errors.

Executive functioning and olfactory identification in young adults with attention deficit-hyperactivity disorder

Young adults with attention deficit-hyperactivity disorder (ADHD; N = 105) were compared with a control group (N = 64) on 14 measures of executive function and olfactory identification using a 2 (group) X 2 (sex) design. The ADHD group performed significantly worse on 11 measures. No Group X Sex interaction was found on any measures. No differences were found in the ADHD group as a function of ADHD subtype or comorbid oppositional defiant disorder. Comorbid depression influenced the results of only 1 test (Digit Symbol). After IQ was controlled for, some group differences in verbal working memory, attention, and odor identification were no longer significant, whereas those in inhibition, interference control, nonverbal working memory, and other facets of attention remained so. Executive function deficits found in childhood ADHD exist in young adults with ADHD and are largely not influenced by comorbidity but may be partly a function of low intelligence.

The level of MHC class I expression on murine adenocarcinoma can change the antitumor effector mechanism of immunocytokine therapy

The huKS1/4-IL2 fusion protein, directed against the human epithelial cell adhesion molecule (huEpCAM) has been shown to induce a strong CD8+ T-cell-dependent, natural killer (NK) cell-independent, antitumor response in mice bearing the huEp-CAM-transfected CT26 colon cancer CT26-EpCAM. Here we investigate the effectiveness of huKS1/4-IL2 against CT26-Ep21.6, a subclone of CT26-EpCAM, expressing low levels of MHC class I. In vitro antibody-dependent cellular cytotoxicity (ADCC) assays in the presence of huKS1/4-IL2 demonstrate that murine NK cells from spleen and blood can kill CT26-Ep21.6 significantly better than they kill CT26-EpCAM. NK-mediated ADCC of CT26-EpCAM can be enhanced by blocking the murine NK cell-inhibitory receptor, Ly-49C. A potent in vivo antitumor effect was observed when BALB/c mice bearing experimental metastases of CT26-Ep21.6 were treated with huKS1/4-IL2. The depletion of NK cells during huKS1/4-IL2 treatment significantly reduced the antitumor effect against CT26-Ep21.6. Together our in vitro and in vivo data in the huEp-CAM-transfected CT26 models indicate that the amount of MHC class I expressed on the tumor target cell plays a critical role in the in vivo antitumor mechanism of huKS1/4-IL2 immunotherapy. A low MHC class I level favors NK cells as effectors, whereas a high level of MHC class I favors T cells as effectors. Given the heterogeneity of MHC class I expression seen in human tumors and the prevailing T-cell suppression in many cancer patients, the observation that huKS1/4-IL2 has the potential to effectively activate an NK cell-based antitumor response may be of potential clinical relevance.

Computer-based patient education

The computer can be a powerful ally in clinicians efforts to empower their patients to make the right individual decisions. The Internet, in particular, is an extremely valuable resource that enables patients to quickly obtain the latest information on support groups, therapeutic modalities, late-breaking research, and individual coping strategies. The technology is now mature enough that every provider should consider incorporating some type of computer-based patient education into his or her practice.

Performance evaluation in work settings

Recent research from 1993 on performance evaluations in work settings is reviewed and integrated with the prior reset and historical bases. Contemporary research reflects several themes: General models of job performance are being developed, the job performance domain is being expanded, research continues to explore the psychometric characteristics of performance ratings, research is developing on potential bias in ratings, rater training is examined, and research continues in terms of efforts to attach utility values to rated performance. We conclude that research is progressing in traditional content areas as well in the exploration of new ground. Researchers are recognizing that job performance is more than just the execution of specific tasks and that it involves a wider array of important organizational activities. There is also an increased optimism regarding the use of supervisory ratings and recognition that such "subjective" appraisal instruments do not automatically translate into rater error or bias.

Motor vehicle driving competencies and risks in teens and young adults with attention deficit hyperactivity disorder

PURPOSE

To evaluate the motor vehicle driving knowledge, skills, and negative driving outcomes of older teens and young adults with attention deficit hyperactivity disorder (ADHD).

LOCATION

A university medical center clinic for adult ADHD.

SUBJECTS

A total of 25 young adults with ADHD and 23 young adults without ADHD 17 to 30 years old drawn from the community and equated for age, gender, and educational level.

MEASURES

Structured interview, behavior ratings by self- and others, video test of driving knowledge, computer simulated driving test, and official motor vehicle records.

RESULTS

ADHD young adults were cited more often for speeding, were more likely to have had their licenses suspended, were involved in more crashes, were more likely to have had crashes causing bodily injury, and were rated by themselves and others as using poorer driving habits. Official driving records corroborated these negative outcomes. Although no group differences in driving knowledge were evident, young adults with ADHD had more crashes, scrapes, and erratic steering during the computer-stimulated driving test than did the control subjects.

CONCLUSIONS

Findings supported previous research suggesting that greater driving risks are associated with ADHD and suggested that ADHD does not interfere with driving knowledge so much as with actual performance (motor control) during vehicle operation.

Influence of job characteristics on the acceptability of employee drug testing

Measures of the acceptability of employee drug testing were obtained from a sample of college students (N = 371) and a second sample of nontraditional, older college students (N = 112) and were correlated with job-analysis data from the Position Analysis Questionnaire (PAQ) and Dictionary of Occupational Titles (DOT) databases, and with measures of perceived danger from impaired performance in each job. Both PAQ and DOT data accounted for variance in ratings of acceptability. Perceptions of danger were the best single predictor of acceptability and appeared to mediate the relationships between job characteristics and the acceptability of employee drug testing.

Refractory congestive heart failure after ribavirin in infants with heart disease and respiratory syncytial virus

Although treatment with ribavirin has been known to be associated with a decreased mortality in infants with congenital heart disease (CHD) who have respiratory syncytial virus (RSV), few data are available regarding morbidity. We reviewed records of 10 consecutively hospitalized infants with CHD during a recent RSV epidemic. Despite the presence of left-to-right shunt in each patient, symptoms of RSV were respiratory at presentation. After ribavirin, decreased respiratory symptoms were found in 8 infants but in 2 assisted ventilation were required 1 and 3 days after admission. Congestive heart failure worsened in 8 patients, 6 of whom had improved respiratory status after ribavirin. Of the 8 patients with worse CHF (pulmonary edema), 3 responded to medical management but 5 were refractory and 4 required surgical repair of CHD. One patient died of pulmonary hemorrhage. Medically refractory CHF may develop in infants with CHD who become infected with RSV and are treated with ribavirin. Further studies are needed to determine whether the pulmonary edema is caused by RSV, ribavirin, or combination of effects on pulmonary capillary function or some other unrecognized mechanism.

The requirement for polymorphonuclear leukocytes in the late asthmatic response and heightened airways reactivity in an animal model

The antigen-induced late asthmatic response (LAR) and subsequent heightened airways reactivity after this response have been associated with increased airways inflammation. Employing an animal model of the LAR in rabbits previously developed in our laboratory, 3 phases of experiments were performed to investigate the role of polymorphonuclear leukocytes (PML) in the LAR and heightened reactivity. In all 3 phases, airways reactivity to histamine and bronchoalveolar lavage analysis were performed 3 days before and 3 days after bronchial challenge with ragweed extract. In Phase 1, 2 groups of rabbits receiving nitrogen mustard were studied: an immune group received immune serum containing antiragweed IgE, and a control group received nonimmune serum. In Phase II, nitrogen mustard was administered to immune rabbits during aortic occlusion to allow the lungs to be exposed to nitrogen mustard while limiting exposure of the bone marrow to this drug, preventing depletion of PML. In Phase III, both an immune and a nonimmune group of rabbits received nitrogen mustard as in Phase I; however, prior to antigen challenge, they were repleted with a neutrophil-rich population of PML. In all experiments, no group of control (nonimmune) rabbits, whether depleted or repleted of PML, developed an immediate asthmatic response (IAR) or a LAR. In addition, no significant increases in lavage cells or airways reactivity occurred after ragweed challenge. In contrast, those animals receiving immune serum and nitrogen mustard developed an IAR; however, no LAR occurred, and no significant change in airways reactivity was observed. Rabbits receiving immune serum and nitrogen mustard with aortic occlusion developed an IAR and LAR, and airways reactivity increased.(ABSTRACT TRUNCATED AT 250 WORDS)

Increases in airway reactivity to histamine and inflammatory cells in bronchoalveolar lavage after the late asthmatic response in an animal model

An increase in airway reactivity after the late asthmatic response (LAR) has been noted in humans. Although these alterations in reactivity have been proposed to be associated with inflammation, no clinical study of the LAR has shown both increased airway reactivity and evidence of pulmonary inflammation. Employing an animal model of the LAR in rabbits developed in our laboratory (Am Rev Respir Dis 1982; 126:493-498), we examined changes in airway reactivity and pulmonary inflammation in rabbits having a late asthmatic response. Two groups of rabbits were studied: a control group (n = 10) received nonimmune serum, and a sensitized group (n = 10) received serum containing homocytotropic antibody (IgE) to ragweed extract (RWE) from rabbits previously immunized from birth with ragweed. Airway reactivity to histamine and the evaluation of different cell types in bronchoalveolar lavage fluid were determined 3 days before and 3 days after bronchial challenge with RWE in all rabbits. No control rabbit developed a LAR, and no significant changes occurred in this group's airway reactivity or cells in lavage fluid after bronchial challenge with RWE. In contrast, all sensitized rabbits developed a LAR, and airway reactivity for this group was markedly increased 3 days later. In addition, the total number of cells including both polymorphonuclear and mononuclear cells in lavage fluid increased significantly 3 days after the LAR. Ten days after the LAR in the sensitized group (n = 8), as airway reactivity returned towards baseline, so did the cells in lavage. We conclude that increased airway reactivity to histamine is temporally associated with pulmonary inflammation as defined by cells in lavage after the LAR in this model.

Measles control in Yaounde: justification of a one dose, nine month minimum age vaccination policy in tropical Africa

For tropical countries the World Health Organisation recommends a single dose of measles vaccine, administered at a minimum age of 9 months. In some African nations, however, up to 26% of all reported measles occurs before the age of 9 months, and many African nations have been reluctant to follow the WHO recommendation. In 1974 the Ministry of Health of the United Republic of Cameroon made several changes in the existing measles control strategy, including increasing the minimum age for measles vaccination from 6 to 9 months. Surveillance of measles in Yaounde, the capital city, during the five years after the increase in age at vaccination did not reveal a need to return to the minimum age of 6 months. In fact, by 1979, with measles vaccination coverage among children 12-23 months of age at 40%, there had been a 44% decrease in reported measles among children of all ages, including a 64% decrease in the measles attack rate among children under the age of 9 months. These observations support the one dose, 9 month minimum age measles vaccination policy in tropical Africa.

Assessing The Discriminant Validity Of Regression Models And Subjectively Weighted Models Of Judgments

When either regression models or subjectively weighted models are used as aids in making placement decisions, the discriminant validity of these models is of interest. When all predictor information is used in all decisions, models which assign equal weights cannot simultaneously show high levels of predictive accuracy and discriminant validity; in some settings, both regression models and subjectively weighted models may. The discriminant validity of regression models and of subjectively weighted models was investigated in two judgment experiments. Both types of models showed high levels of accuracy and cross-validity in both experiments. Regression models showed discriminant validity in both experiments, while subjectively weighted models failed to show discriminant validity in the second. The homogeneity of cue validities appeared to moderate both the level of discriminant validity and the relationship between similarity of subjective models, across tasks, and discriminant validity.