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Physical Sciences and Mathematics Commons™

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Gettysburg College

Series

2009

Articles 1 - 6 of 6

Full-Text Articles in Physical Sciences and Mathematics

Absolute Dimensions Of The G7+K7 Eclipsing Binary Star Im Virginis: Discrepancies With Stellar Evolution Models, Juan Carlos Morales, Guillermo Torres, Laurence A. Marschall, William C. Brehm Dec 2009

Absolute Dimensions Of The G7+K7 Eclipsing Binary Star Im Virginis: Discrepancies With Stellar Evolution Models, Juan Carlos Morales, Guillermo Torres, Laurence A. Marschall, William C. Brehm

Physics and Astronomy Faculty Publications

We report extensive spectroscopic and differential photometric BVRI observations of the active, detached, 1.309-day double-lined eclipsing binary IMVir, composed of a G7-type primary and a K7 secondary.With these observations, we derive accurate absolute masses and radii of M1 = 0.981 + 0.012M, M2 = 0.6644 + 0.0048M, R1 = 1.061 + 0.016R, and R2 = 0.681 + 0.013R for the primary and secondary, with relative errors under 2%. The effective temperatures are 5570 + 100 K and 4250 + 130 K, respectively. The significant difference in mass makes this a favorable case for comparison with stellar evolution theory.We find that …

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Galois Structure And De Rhan Invariants Of Elliptic Curves, Darren B. Glass, Sonin Kwon Jan 2009

Galois Structure And De Rhan Invariants Of Elliptic Curves, Darren B. Glass, Sonin Kwon

Math Faculty Publications

Let K be a number field with ring of integers OK. Suppose a finite group G acts numerically tamely on a regular scheme X over OK. One can then define a de Rham invariant class in the class group Cl(OK[G]), which is a refined Euler characteristic of the de Rham complex of X. Our results concern the classification of numerically tame actions and the de Rham invariant classes. We first describe how all Galois etale G-covers of a K-variety may be built up from finite Galois extensions of K and from geometric covers. When X is a curve of positive …

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Radiocarbon Date List Xi: Radiocarbon Dates From Marine Sediment Cores Of The Iceland, Greenland, And Northeast Canadian Arctic Shelves And Nares Strait, U. Quillmann, J.T. Andrews, A.E. Jennings, J. Bendle, H. Jonsdottir, G.B. Kristjansdottir, J. Lloyd, S. Olafsdottir, Sarah M. Principato Jan 2009

Radiocarbon Date List Xi: Radiocarbon Dates From Marine Sediment Cores Of The Iceland, Greenland, And Northeast Canadian Arctic Shelves And Nares Strait, U. Quillmann, J.T. Andrews, A.E. Jennings, J. Bendle, H. Jonsdottir, G.B. Kristjansdottir, J. Lloyd, S. Olafsdottir, Sarah M. Principato

Environmental Studies Faculty Publications

Radiocarbon Date List XI contains an annotated listing of 178 AMS radiocarbon dates on samples from marine (169 samples) and lake (9 samples) sediment cores. Marine sediment cores, from which the samples for dating were taken, were collected on the Greenland Shelf, Baffin Bay, and the Eastern Canadian Arctic shelf. About 80% of the marine samples for dating were collected on the SW to N Icelandic shelf. The lake sediment cores were collected in northwestern Iceland. For dating of the marine samples, we submitted molluscs (117 samples), benthic and planktic foraminifera (45 samples), plant macrofauna (3 samples), and one serpulid …

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Using Gis To Quantify Patterns Of Glacial Erosion On Northwest Iceland: Implications For Independent Ice Sheets, Sarah M. Principato, Jeremiah S. Johnson Jan 2009

Using Gis To Quantify Patterns Of Glacial Erosion On Northwest Iceland: Implications For Independent Ice Sheets, Sarah M. Principato, Jeremiah S. Johnson

Environmental Studies Faculty Publications

Glacial erosion patterns on northwest Iccliind are quantified using a Geographic Information System (GIS) in order to interpret subglacial characteristics of part of northwest Iceland affected by ice sheet glaciation. Ice scour lake density is used as a proxy for glacial erosion. Erosion classes are interpreted from variations in the density of lake basins. Lake density was calculated using two dilTerent methods: the first is sensitive to the total number of lakes in a specific area, and the second is sensitive to total lake area in a specific area. Both of these methods result in a value for lake density, …

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An Interview With Julian Agyeman: Just Sustainability And Ecopedagogy, Salma Monani Jan 2009

An Interview With Julian Agyeman: Just Sustainability And Ecopedagogy, Salma Monani

Environmental Studies Faculty Publications

This interview with Julian Agyeman, a key originator of the concept of just sustainability, engages Agyeman in discussion of how just sustainability evolved, and how its theoretical and practical dimensions relate to the principles of ecopedagogy.

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The 2-Ranks Of Hyperelliptic Curves With Extra Automorphisms, Darren B. Glass Jan 2009

The 2-Ranks Of Hyperelliptic Curves With Extra Automorphisms, Darren B. Glass

Math Faculty Publications

This paper examines the relationship between the automorphism group of a hyperelliptic curve defined over an algebraically closed field of characteristic two and the 2-rank of the curve. In particular, we exploit the wild ramification to use the Deuring-Shafarevich formula in order to analyze the ramification of hyperelliptic curves that admit extra automorphisms and use this data to impose restrictions on the genera and 2-ranks of such curves. We also show how some of the techniques and results carry over to the case where our base field is of characteristic p > 2.

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