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Articles 1 - 8 of 8
Full-Text Articles in Physical Sciences and Mathematics
The Savannah River Site: Site Description, Land Use And Management History, David L. White, Karen F. Gaines
The Savannah River Site: Site Description, Land Use And Management History, David L. White, Karen F. Gaines
Publications
The 78,000-ha Savannah River Site, which is located in the upper Coastal Plain of South Carolina along the Savannah River, was established as a nuclear production facility in 1951 by the Atomic Energy Commission. The site’s physical and vegetative characteristics, land use history, and the impacts of management and operations are described. Aboriginal and early European settlement was primarily along streams, where much of the farming and timber cutting have occurred. Woodland grazing occurred in the uplands and lowlands. Land use intensity increased after the Civil War and peaked in the 1920s. Impacts from production of cotton and corn, naval …
Book Review: 3-D Atlas Of Stars And Galaxies, T. D. Oswalt
Book Review: 3-D Atlas Of Stars And Galaxies, T. D. Oswalt
Publications
This document is Dr. Oswalt’s review of 3-D Atlas of Stars and Galaxies by Richard Monkhouse and John Cox Springer, 2000. 95p, 1-85233-189-5 $42.00.
Secular Variations Of Atomic Oxygen In The Mesopause Region Induced By Transient Gravity Wave Packets, Michael P. Hickey Ph.D., R. L. Walterscheid, Philip G. Richards
Secular Variations Of Atomic Oxygen In The Mesopause Region Induced By Transient Gravity Wave Packets, Michael P. Hickey Ph.D., R. L. Walterscheid, Philip G. Richards
Publications
We employ a 2-dimensional, time-dependent, fully nonlinear model of minor species in the mesopause region and our Spectral Full-Wave Model to simulate the response of atomic oxygen (O) to a gravity wave packet in the mesopause region. We demonstrate that gravity waves affect the time-averaged distribution of O in the mesosphere and lower thermosphere (MLT) region through the constituent fluxes the waves induce. Our conclusions are based on simulations of two wave packets that violate the non-acceleration conditions through transience and dissipation. The net cycle-averaged effect of the waves is to significantly increase (by as much as 50%) the O …
Resolving Ambiguities In Gravity Wave Propagation Directions Inherent In Satellite Observations: A Simulation Study, Michael P. Hickey Ph.D., Jason S. Brown
Resolving Ambiguities In Gravity Wave Propagation Directions Inherent In Satellite Observations: A Simulation Study, Michael P. Hickey Ph.D., Jason S. Brown
Publications
We simulate space-based, sub-limb viewing observations of airglow brightness fluctuations caused by atmospheric gravity wave interactions with the O2 atmospheric airglow, and we demonstrate that, due to the geometry associated with such observations, the brightness fluctuations observed for the optically thick 0–0 band emission will always appear stronger for waves traveling towards the observer (satellite). The effect should be most noticeable for waves having relatively small vertical wavelengths (∼10 km) and horizontal wavelengths of 50 km or greater. For waves of short (∼100 km) horizontal wavelength, the brightness fluctuation anisotropy with respect to viewing direction may also be evident in …
The White Dwarf Cooling Age Of The Open Cluster Ngc 2420, Ted Von Hippel, Gerard Gilmore
The White Dwarf Cooling Age Of The Open Cluster Ngc 2420, Ted Von Hippel, Gerard Gilmore
Publications
We have used deep HST WFPC2 observations of two fields in NGC 2420 to produce a cluster color-magnitude diagram down to V ≈ 27. After imposing morphological selection criteria we find eight candidate white dwarfs in NGC 2420. Our completeness estimates indicate that we have found the terminus of the WD cooling sequence. We argue that the cluster distance modulus is likely to be close to 12.10 with E(B-V) = 0.04. With these parameters we find a white dwarf cooling age for NGC 2420 of 2.0 ± 0.20 (1 σ) Gyr. The 0.20 Gyr uncertainty includes errors in the photometry, …
An Elliptic Equation With Spike Solutions Concentrating At Local Minima Of The Laplacian Of The Potential, Gregory S. Spradlin
An Elliptic Equation With Spike Solutions Concentrating At Local Minima Of The Laplacian Of The Potential, Gregory S. Spradlin
Publications
We consider the equation −ԑ2∆u + V (z)u = f(u) which arises in the study of nonlinear Schrödinger equations. We seek solutions that are positive on RN and that vanish at infinity. Under the assumption that f satisfies super-linear and sub-critical growth conditions, we show that for small ԑ there exist solutions that concentrate near local minima of V. The local minima may occur in unbounded components, as long as the Laplacian of V achieves a strict local minimum along such a component. Our proofs employ vibrational mountain-pass and concentration compactness arguments. A penalization technique developed by Felmer and del …
The Wiyn Open Cluster Study: A New Color-Magnitude Diagram For M35 - A Twin Of The Pleiades, Ted Von Hippel, Vera Kozhurina-Platais, Imants Platais, Pierre Demarque, Ata Sarajedini
The Wiyn Open Cluster Study: A New Color-Magnitude Diagram For M35 - A Twin Of The Pleiades, Ted Von Hippel, Vera Kozhurina-Platais, Imants Platais, Pierre Demarque, Ata Sarajedini
Publications
M35 (NGC 2168) is rich, young, and in some regards a better laboratory for stellar cluster research at 100 million years than the Pleiades. Yet, while M35 has been the subject of intriguing photometric, astrometric, and theoretical studies, to the best of our knowledge no published CCD-based photometry exists for this cluster. We have obtained relatively wide-field (23' x23') precise UBVRJ CCD photometry for M35 as part of the WIYN Open Cluster Study (WOCS) at the 0.9m telescope at Kitt Peak National Observatory. The photometry extends from the main sequence turn off to beyond V = 19. We find that …
Book Review: The Birth Of Time: How Astronomers Measured The Age Of The Universe, T. D. Oswalt
Book Review: The Birth Of Time: How Astronomers Measured The Age Of The Universe, T. D. Oswalt
Publications
This document is Dr. Oswalt’s review of The Birth of Time : How Astronomers Measured the Age of the Universe by John Gribbin. Yale, 2000 237p, 0-300-08346-7 $22.50.