Anisotropy is the property of a material which allows it to change or assume different properties in different directions, as opposed to isotropy. It can be defined as a difference, when measured along different axes, in a material's physical or mechanical properties.
Magnetoresistance is the tendency of a material to change the value of its electrical resistance in an externally-applied magnetic field. There are a variety of effects that can be called magnetoresistance. Some occur in bulk non-magnetic metals and semiconductors, such as geometrical magnetoresistance, Shubnikov–de Haas oscillations, or the common positive magnetoresistance in metals. Other effects occur in magnetic metals, such as negative magnetoresistance in ferromagnets or anisotropic magnetoresistance (AMR). Finally, in multicomponent or multilayer systems, giant magnetoresistance (GMR), tunnel magnetoresistance (TMR), colossal magnetoresistance (CMR), and extraordinary magnetoresistance (EMR) can be observed.
In geophysics and reflection seismology, amplitude versus offset (AVO) or amplitude variation with offset is the general term for referring to the dependency of the seismic attribute, amplitude, with the distance between the source and receiver. AVO analysis is a technique that geophysicists can execute on seismic data to determine a rock's fluid content, porosity, density or seismic velocity, shear wave information, fluid indicators.
Earth's inner core is the innermost geologic layer of planet Earth. It is primarily a solid ball with a radius of about 1,220 km (760 mi), which is about 20% of Earth's radius or 70% of the Moon's radius.
Don Lynn Anderson was an American geophysicist who made significant contributions to the understanding of the origin, evolution, structure, and composition of Earth and other planets. An expert in numerous scientific disciplines, Anderson's work combined seismology, solid state physics, geochemistry and petrology to explain how the Earth works. Anderson was best known for his contributions to the understanding of the Earth's deep interior, and more recently, for the plate theory hypothesis that hotspots are the product of plate tectonics rather than narrow plumes emanating from the deep Earth. Anderson was Professor (Emeritus) of Geophysics in the Division of Geological and Planetary Sciences at the California Institute of Technology (Caltech). He received numerous awards from geophysical, geological and astronomical societies. In 1998 he was awarded the Crafoord Prize by the Royal Swedish Academy of Sciences along with Adam Dziewonski. Later that year, Anderson received the National Medal of Science. He held honorary doctorates from Rensselaer Polytechnic Institute and the University of Paris (Sorbonne), and served on numerous university advisory committees, including those at Harvard, Princeton, Yale, University of Chicago, Stanford, University of Paris, Purdue University, and Rice University. Anderson's wide-ranging research resulted in hundreds of published papers in the fields of planetary science, seismology, mineral physics, petrology, geochemistry, tectonics and the philosophy of science.
Seismic anisotropy is the directional dependence of the velocity of seismic waves in a medium (rock) within the Earth.
Jon F. Claerbout is an American geophysicist and seismologist. He is the Cecil Green Professor Emeritus of Geophysics at Stanford University. Since the later half of the 20th century, he has been a leading researcher and pioneered the use of computers in processing and filtering seismic exploration data, eventually developing the field of time series analysis and seismic interferometry, modelling the propagation of seismic waves.
The Stanford Exploration Project (SEP) is an industry-funded academic consortium within the Geophysics Department at Stanford University. SEP research has contributed greatly to improving the theory and practice of constructing 3-D and 4-D images of the earth from seismic echo soundings. The consortium was started in the 1970s by Jon Claerbout and is currently co-directed with Biondo Biondi.
In 2017 the department was merged with the Department of Geology and Mineral Resources Engineering, forming the new Department of Geoscience and Petroleum.
Albert Francis Birch was an American geophysicist. He is considered one of the founders of solid Earth geophysics. He is also known for his part in the atomic bombing of Hiroshima and Nagasaki.
James Anthony Jackson CBE FRS is Professor of Active Tectonics and head of Bullard Laboratories, Department of Earth Sciences, Cambridge University. He made his name in geophysics, using earthquake source seismology to examine how continents are deformed. His central research focus is to observe the active processes shaping our continents.
Osipkov–Merritt models are mathematical representations of spherical stellar systems. The Osipkov–Merritt formula generates a one-parameter family of phase-space distribution functions that reproduce a specified density profile in a specified gravitational potential. The density and potential need not be self-consistently related. A free parameter adjusts the degree of velocity anisotropy, from isotropic to completely radial motions. The method is a generalization of Eddington's formula for constructing isotropic spherical models.
Michael Schoenberg (1939–2008) was an American theoretical geophysicist noted for his fundamental contributions to the understanding of anisotropy in the real earth and its application to the determination of texture, fracture porosity, and flow properties of reservoir rocks.
John Peter Wikswo, Jr. is a biological physicist at Vanderbilt University. He was born in Lynchburg, Virginia, United States.
Shear wave splitting, also called seismic birefringence, is the phenomenon that occurs when a polarized shear wave enters an anisotropic medium. The incident shear wave splits into two polarized shear waves. Shear wave splitting is typically used as a tool for testing the anisotropy of an area of interest. These measurements reflect the degree of anisotropy and lead to a better understanding of the area's crack density and orientation or crystal alignment. We can think of the anisotropy of a particular area as a black box and the shear wave splitting measurements as a way of looking at what is in the box.
Reynolds stress equation model (RSM), also referred to as second moment closures are the most complete classical turbulence model. In these models, the eddy-viscosity hypothesis is avoided and the individual components of the Reynolds stress tensor are directly computed. These models use the exact Reynolds stress transport equation for their formulation. They account for the directional effects of the Reynolds stresses and the complex interactions in turbulent flows. Reynolds stress models offer significantly better accuracy than eddy-viscosity based turbulence models, while being computationally cheaper than Direct Numerical Simulations (DNS) and Large Eddy Simulations.
Maureen D. Long is an observational seismologist studying mantle and Mesosphere dynamics. She currently serves as a professor at Yale University within the Department of Geology and Geophysics.
John-Michael Kendall is a Geophysicist and Professor in the Department of Earth Sciences at the University of Oxford.
Nicholas Frederick Chilton is an Australian chemist and a Professor in the Department of Chemistry at the University of Manchester. His research is in the areas of magnetochemistry and computational chemistry, and includes the design of high-temperature single molecule magnets, molecular spin qubits for quantum information science, methods and tools for modelling magnetic calculations.
