ABSTRACT
The core mantle boundary (CMB) separates Earth's liquid iron outer core from the solid but slowly convecting mantle. The detailed structure and dynamics of the mantle within ~300 km of this interface remain enigmatic: it is a complex region, which exhibits thermal, compositional and phase-related heterogeneity, isolated pockets of partial melt and strong variations in seismic velocity and anisotropy. Nonetheless, characterising the structure of this region is crucial to a better understanding of the mantle's thermo-chemical evolution and the nature of core-mantle interactions. In this study, we examine the heterogeneity spectrum from a recent P-wave tomographic model, which is based upon trans-dimensional and hierarchical Bayesian imaging. Our tomographic technique avoids explicit model parameterization, smoothing and damping. Spectral analyses reveal a multi-scale wavelength content and a power of heterogeneity that is three times larger than previous estimates. Inter alia, the resulting heterogeneity spectrum gives a more complete picture of the lowermost mantle and provides a bridge between the long-wavelength features obtained in global S-wave models and the short-scale dimensions of seismic scatterers. The evidence that we present for strong, multi-scale lowermost mantle heterogeneity has important implications for the nature of lower mantle dynamics and prescribes complex boundary conditions for Earth's geodynamo.
ABSTRACT
OBJECTIVE: The primary objective was to determine whether oral morphine sulfate contributed to decreased length of stay, both in the hospital and neonatal intensive care unit (NICU), when compared to oral methadone for the treatment of neonatal abstinence syndrome (NAS). Secondary objectives included evaluation of NAS scores, opioid requirements, use of adjuvant therapy, and total cost of hospital stay. METHODS: An equal number of neonates who received oral morphine sulfate and oral methadone as treatment for NAS were identified. Inclusion criteria included in utero exposure to opioids as determined by maternal history, toxicology reports during pregnancy or at the time of delivery, or infant urine toxicology reports and symptoms of NAS requiring pharmacological treatment. Exclusion criteria included neonates transferred to or from another facility during treatment, neonates discharged on NAS treatment, and neonates diagnosed with iatrogenic NAS due to postnatal exposure to opioids. RESULTS: Twenty six neonates met inclusion criteria. Statistically significant decreases in length of hospital and NICU stay, length of treatment, maximum opioid requirements, and total cost were found when neonates treated for NAS with oral morphine sulfate were compared to those treated with oral methadone. No statistically significant differences in average maximum NAS score or use of adjuvant therapy were found between the two groups. CONCLUSION: Oral morphine sulfate reduced length of NICU and hospital stay, length of treatment, and total cost of treatment for neonates treated for NAS.
