Using Moment of Inertia and Observable Planetary Features to Approximate the Two-Layer Structure of Earth, Jupiter, and Neptune

This paper examines the interior structure and composition of Earth, Jupiter, and Neptune by using moment of inertia (MoI) and observable planetary features to create approximate two-layer interior structure models. The moment inertia of a uniform sphere, hollow sphere, and a sphere with a shell are derived to calculate the radius and density variables that identify the relationship between the different radii and densities of the two layers. A two-layer model of the planet’s interior can then be formulated based on the radius, density, known MoI factor and the surface density or the assumed composition density of the planet. The models created for Jupiter and Neptune are compared to Earth’s model and conclude that Jupiter may have a silica-rich core, whereas Neptune’s model has inconclusive density and radius results that should be further investigated. Published literature containing current three-layer models of planetary interiors confirm the results produced from the two-layer models in this paper

Using Moment of Inertia and Observable Planetary Features to Approximate the Two-Layer Structure of Earth, Jupiter, and Neptune

This paper examines the interior structure and composition of Earth, Jupiter, and Neptune by using moment of inertia (MoI) and observable planetary features to create approximate two-layer interior structure models. The moment inertia of a uniform sphere, hollow sphere, and a sphere with a shell are derived to calculate the radius and density variables that identify the relationship between the different radii and densities of the two layers. A two-layer model of the planet’s interior can then be formulated based on the radius, density, known MoI factor and the surface density or the assumed composition density of the planet. The models created for Jupiter and Neptune are compared to Earth’s model and conclude that Jupiter may have a silica-rich core, whereas Neptune’s model has inconclusive density and radius results that should be further investigated. Published literature containing current three-layer models of planetary interiors confirm the results produced from the two-layer models in this paper

Preservation of inherited argon in plagioclase crystals and implication for residence time after reservoir remobilization

International audienceWe compare K-Ar ages obtained on groundmass and plagioclase from lava domes that erupted after flank collapse events in the Lesser Antilles and Ecuador. All samples contain plagioclase with distinct zoning patterns, as well as inclusion-rich zones, that reveal one or more crystal resorption events due to rapid temperature changes. In these samples, plagioclase crystals yield ages 2 to 3 times older than the groundmass due to a partial retention of inherited 40Ar. We investigate textural and compositional zoning in plagioclase phenocrysts using backscattered electron images, electron microprobe and scanning electron microscope analysis of major and trace elements. Age and zoning patterns are coupled to modelling of Ar and Sr diffusion to calculate residence time of crystals at magmatic temperature after reservoir remobilization. Combined data suggest that crystals were remobilized after a magma mixing event related to a flank collapse event. In order to account for the age difference, we have modeled the residence time of plagioclase using magma temperature conditions and possible inherited crystal initial ages. We have calculated that the age differences observed require residence times of tens to a few hundred years. This suggests that eruptions studied here have been triggered by reservoir remobilization in less than 100 years. This can be related to changes in the volcano’s morphology due to large scale flank collapse having affected the plumbing system relatively quickly. Based on similar features observed in different settings, it can be proposed that similar processes are common at arc volcanoes. Our approach should help us to better constrain the timing between magmatic intrusion, mixing, flank collapse and eruptions

Genetic aspects of behavioral neurotoxicology

Considerable progress has been made over the past couple of decades concerning the molecular bases of neurobehavioral function and dysfunction. The field of neurobehavioral genetics is becoming mature. Genetic factors contributing to neurologic diseases such as Alzheimer’s disease have been found and evidence for genetic factors contributing to other diseases such as schizophrenia and autism are likely. This genetic approach can also benefit the field of behavioral neurotoxicology. It is clear that there is substantial heterogeneity of response with behavioral impairments resulting from neurotoxicants. Many factors contribute to differential sensitivity, but it is likely that genetic variability plays a prominent role. Important discoveries concerning genetics and behavioral neurotoxicity are being made on a broad front from work with invertebrate and piscine mutant models to classic mouse knockout models and human epidemiologic studies of polymorphisms. Discovering genetic factors of susceptibility to neurobehavioral toxicity not only helps identify those at special risk, it also advances our understanding of the mechanisms by which toxicants impair neurobehavioral function in the larger population. This symposium organized by Edward Levin and Annette Kirshner, brought together researchers from the laboratories of Michael Aschner, Douglas Ruden, Ulrike Heberlein, Edward Levin and Kathleen Welsh-Bohmer conducting studies with Caenorhabditis elegans, Drosophila, fish, rodents and humans studies to determine the role of genetic factors in susceptibility to behavioral impairment from neurotoxic exposure