Convection in the Earth's core driven by lateral variations in the core-mantle boundary heat flux

Moving core fluid maintains an isothermal core-mantle boundary (CMB), so lateral variations in the CMB heat flow result from mantle convection. Such variations will drive thermal winds, even if the top of the core is stably stratified. These flows may contribute to the magnetic secular variation and are investigated here using a simple, non-magnetic numerical model of the core. The results depend on the equatorial symmetry of the boundary heat flux variation. Large-scale equatorially symmetric (ES) heat flux variations at the outer surface of a rapidly rotating spherical shell drive deeply penetrating flows that are strongly suppressed in stratified fluid. Smaller-scale ES heat flux variations drive flows less dominated by rotation and so less inhibited by stratification. Equatorially anti-symmetric flux variations drive flows an order of magnitude less energetic than those driven by ES patterns but, due to the nature of the Coriolis force, are less suppressed by stratification. The response of the rotating core fluid to a general CMB heat flow pattern will then depend strongly on the subadiabatic temperature profile. Imposing a lateral heat flux variation linearly related to a model of seismic tomography in the lowermost mantle drives flow in a density stratified fluid that reproduces some features found in flows inverted from geomagnetic data

Experiments pertaining to the formation and equilibration of planetary cores

The phase diagram of FeO was experimentally determined to pressures of 155 GPa and temperatures of 4000 K using shock wave and diamond-cell techniques. Researchers discovered a metallic phase of FeO at pressures greater than 70 GPa and temperatures exceeding 1000 K. The metallization of FeO at high pressures implies that oxygen can be present as the light alloying element of the Earth's outer core, in accord with the geochemical predictions of Ringwood. The high pressures necessry for this metallization suggest that the core has acquired its composition well after the initial stages of the Earth's accretion. The core forming alloy can react chemically with oxides such as those forming the mantle. The core and mantle may never have reached complete chemical equilibrium, however. If this is the case, the core-mantle boundary is likely to be a zone of active chemical reactions

Central Square: Kansas City, Missouri

The program for this project outlines uses both specific in nature (a YMCA, restaurant, and club), and speculative in nature (new commercial and office space). Three buildings currently occupy the site

Regulation of ErbB4 signaling by post-translational modifications

ErbB4 is a member of the epidermal growth receptor family (EGFR/ErbB1, ErbB2, ErbB3, ErbB4) of receptor tyrosine kinases. ErbB receptors are activated by extracellular growth factor ligands, and control the activity of intracellular signaling pathways that regulate fundamental cellular processes such as proliferation, differentiation and survival. ErbB receptors are necessary for the development and homeostasis of several tissues, and aberrant ErbB signaling is a common feature of human pathologies, such as cancer. Accordingly, several regulatory mechanisms are required to ensure the appropriate function of ErbB receptors. This thesis aimed to characterize novel regulatory mechanisms of ErbB4 signaling, with a focus on ubiquitin and ubiquitin-like post-translational modifications. ErbB4 is expressed as functionally distinct isoforms, and the results of this thesis indicate that ErbB4 is ubiquitinated, endocytosed and degraded in an isoform-specific manner. Ubiquitination, a signal for endocytosis and degradation, was catalyzed by a ubiquitin ligase that specifically interacted with one of the isoforms. This study also demonstrated that ErbB4 intracellular domain (ICD), released by ErbB4 isoforms that undergo regulated intramembrane proteolysis, is modified by small ubiquitin-like modifier (SUMO). SUMOylation promoted the nuclear accumulation of ErbB4 ICD and regulated the nuclear signaling of ErbB4. Together, these findings represent novel molecular mechanisms that regulate the stability, subcellular localization and activity of ErbB4. Moreover, this study demonstrates for the first time that SUMOylation controls the function of an ICD of a receptor tyrosine kinase in the nucleus. The post-translational regulation of quantitative and qualitative aspects of ErbB4 signaling may have implications for the function of ErbB receptors in both normal tissues and cancer. Finally, the findings of this thesis can potentially be extended to provide new understanding on the mechanisms that regulate the functions of receptor tyrosine kinases other than ErbB4.Siirretty Doriast

A comparison of the ideal of private property held by St Augustine with that held by St Francis of Assisi

Thesis (M.A.)--Boston University, 1938. This item was digitized by the Internet Archive

Modified thermal analyzer digital computer program (TAP)

Computer program for solving n-dimensional transient or steady state heat flow problems by creating electrical analogy of problem and solving by finite difference metho