Energetic Electron Precipitation Driven by Electromagnetic Ion Cyclotron Waves from ELFIN's Low Altitude Perspective.

We review comprehensive observations of electromagnetic ion cyclotron (EMIC) wave-driven energetic electron precipitation using data collected by the energetic electron detector on the Electron Losses and Fields InvestigatioN (ELFIN) mission, two polar-orbiting low-altitude spinning CubeSats, measuring 50-5000 keV electrons with good pitch-angle and energy resolution. EMIC wave-driven precipitation exhibits a distinct signature in energy-spectrograms of the precipitating-to-trapped flux ratio: peaks at >0.5 MeV which are abrupt (bursty) (lasting ∼17 s, or ΔL∼0.56) with significant substructure (occasionally down to sub-second timescale). We attribute the bursty nature of the precipitation to the spatial extent and structuredness of the wave field at the equator. Multiple ELFIN passes over the same MLT sector allow us to study the spatial and temporal evolution of the EMIC wave - electron interaction region. Case studies employing conjugate ground-based or equatorial observations of the EMIC waves reveal that the energy of moderate and strong precipitation at ELFIN approximately agrees with theoretical expectations for cyclotron resonant interactions in a cold plasma. Using multiple years of ELFIN data uniformly distributed in local time, we assemble a statistical database of ∼50 events of strong EMIC wave-driven precipitation. Most reside at L∼5-7 at dusk, while a smaller subset exists at L∼8-12 at post-midnight. The energies of the peak-precipitation ratio and of the half-peak precipitation ratio (our proxy for the minimum resonance energy) exhibit an L-shell dependence in good agreement with theoretical estimates based on prior statistical observations of EMIC wave power spectra. The precipitation ratio's spectral shape for the most intense events has an exponential falloff away from the peak (i.e., on either side of ∼1.45 MeV). It too agrees well with quasi-linear diffusion theory based on prior statistics of wave spectra. It should be noted though that this diffusive treatment likely includes effects from nonlinear resonant interactions (especially at high energies) and nonresonant effects from sharp wave packet edges (at low energies). Sub-MeV electron precipitation observed concurrently with strong EMIC wave-driven >1 MeV precipitation has a spectral shape that is consistent with efficient pitch-angle scattering down to ∼ 200-300 keV by much less intense higher frequency EMIC waves at dusk (where such waves are most frequent). At ∼100 keV, whistler-mode chorus may be implicated in concurrent precipitation. These results confirm the critical role of EMIC waves in driving relativistic electron losses. Nonlinear effects may abound and require further investigation.

Cord Blood Thyroid Stimulating Hormone Values in Healthy Term Babies delivered at Abubakar Tafawa Balewa University Teaching Hospital Bauchi, Northeastern Nigeria.

BACKGROUND: Congenital hypothyroidism is one of the most common preventable causes of mental retardation and clinical manifestations are often subtle or absent at birth and hence the need for screening. Implementation of newborn screening requires local normative values. OBJECTIVES: To determine the normative values of cord Thyroid Stimulating Hormone (TSH) among term babies in Bauchi, Northeast Nigeria and compare it with that from other centers in Nigeria. METHODOLOGY: Cord blood samples from 200 term babies were analyzed for TSH by Fluorescence Immunoassay technique in this descriptive cross-sectional study. A cut-off of >20 µIU/ml was used for recall. The mean and range were determined and compared with those of previous local studies using t-test. Impact of some maternal and infant factors on TSH was also assessed. RESULTS: The overall mean (SD) cord TSH was 3.74 (±1.99) µIU/ ml and the range was 0.73 to 15.22 µIU/ml (2.5th to 97.5th centile) and none had TSH > 20 µIU/ml and hence our recall rate was 0%. The mean cord TSH was comparable to that reported by a lone local multicenter study (p = 0.120) but significantly different from that of 3 other local studies (p < 0.001). There was also no significant difference between the means of different gender, birth weight groups, mode of delivery, socio-economic classes, maternal age and parity. CONCLUSION: The Cord blood TSH level of most term newborn in Bauchi, similar to other Nigerian studies, is < 10 µIU/ml with a few but significant percentage recording cord TSH level > 10 µIU/ml. Gender, birth weight, mode of delivery, socio-economic class, maternal age and parity were not significantly related to cord TSH level. The mean blood TSH values from different studies across the country tend to vary based on the assay technique. We recommend a nationwide multicenter study with a much larger sample size, lower cutoff value for recall and a unified sample processing laboratory if national normative values are to be developed.

BACKGROUND: L'hypothyroïdie congénitale est l'une des causes évitables les plus courantes de retard mental et les manifestations cliniques sont souvent subtiles ou absentes à la naissance, d'où la nécessité d'un dépistage. La mise en œuvre du dépistage néonatal nécessite des valeurs normatives locales. OBJECTIFS: Déterminer les valeurs normatives de l'hormone stimulatrice de la thyroïde (TSH) du cordon chez les bébés nés à terme à Bauchi, Nord-Est du Nigeria et les comparer à celles d'autres centres du Nigeria. MÉTHODOLOGIE: Des échantillons de sang ombilical de 200 bébés nés à terme ont été analysés pour la TSH par la technique d' étude descriptive transversale. Un seuil de >20 µUI/ml a été utilisé pour le rappel. La moyenne et l'intervalle ont été déterminés et comparés avec ceux des études locales précédentes en utilisant le test t. L'impact de certains facteurs maternels myet infantiles sur la TSH a également été évalué. RÉSULTATS: La moyenne globale (SD) de la TSH du cordon était de 3,74 (±1,99) µIU/ml et l'intervalle était de 0,73 à 15,22 µIU/ml (2,5 à 97,5 centiles) aucun n'avait une TSH > 20 µIU/ml et donc notre taux de rappel était de 0%. La moyenne de TSH au cordon était comparable à celle rapportée par une seule étude multicentrique locale unique (p = 0,120) mais significativement différente de celle de 3 autres études locales (p < 0,001). Il n'y avait pas non plus de différence significative entre les moyennes des différents sexes, groupes de poids de naissance, mode d'accouchement, classes socio d'accouchement, les classes socio-économiques, l'âge maternel et la parité. CONCLUSION: Le niveau de TSH dans le sang de cordon de la plupart des nouveau-nés à termede la plupart des nouveau-nés à terme à Bauchi, comme dans d'autres études nigérianes, est < 10 µUI/ml mais significatif, enregistrant un niveau de TSH du cordon > 10 µIU/ml. Le sexe, le poids à la naissance, le mode d'accouchement, la classe socio-économique maternelle et la parité n'étaient pas significativement liés au taux de TSH au cordon. Le site valeurs moyennes de la TSH sanguine provenant de différentes études dans le pays ont tendance à varier en fonction de la technique de dosage. Nous recommandons une étude nationale multicentrique avec une taille d'échantillon beaucoup plus grande, une valeur seuil pour le rappel et un laboratoire de traitement des échantillons unifié si des valeurs normatives nationales doivent être développées. Mots clés: Sang de cordon, Hormone de stimulation thyroïdienne, Bébés à terme.

Drift wave stabilized by an additional streaming ion or plasma population.

It is shown that the universally unstable kinetic drift wave in an electron-ion plasma can very effectively be suppressed by adding an extra flowing ion (or plasma) population. The effect of the flow of the added ions is essential, their response is of the type (vph-vf0)exp[-(vph-vf0)2], where vf0 is the flow speed and vph is the phase speed parallel to the magnetic field vector. The damping is strong and it is mainly due to this ion exponential term, and this remains so for vf0