Fluid Borders, Concrete Locations: Epicenters of Cross-Cultural Interaction in the Eighteenth Century Borderland of the Great Lakes

In a recent article on the advent of borderlands history as a prominent field of historical scholarship, Pekka Hämäläinen and Samuel Truett described borderlands as “realms where boundaries are also crossroads, peripheries are also central places, homelands are also passing-through places, and the end points of empire are also forks in the road.” One such region that certainly fits this definition of a borderland and unquestionably hosts such specific crossroads and cultural junctions is the maritime region of the Great Lakes of North America. [excerpt

The Minority Experience at Gettysburg College: The Hanson Years (1961-1977)

The years of C. Arnold Hanson’s term as president at Gettysburg College were years of turbulence, change, and challenge. Rising to the position of president in 1961, in the dawning of a dynamic era of modern American history, C. A. Hanson served well into the middle of the next decade, during which time he helped guide Gettysburg College through some of its most trying and vital changes. This was the era of the hippie and the free thinker, the era of the Women’s and Civil Rights Movements, the era of Vietnam and anti-war protests, the era that shaped modern American society and culture. During this period, one of the areas in which the most dramatic changes occurred was in the sphere of Civil Rights; Gettysburg was far from the forefront in dealing with bigotry, but it did confront the race issue. As this occurred on the national scale, efforts were made at Gettysburg to follow suit. Sadly, this was often difficult and unsuccessful, occurring “in fits and starts.” During C. A. Hanson’s tenure as president, minorities experienced discrimination as they pursued equal opportunities in education, faculty and administrators struggled to construct a successful strategy for integration, students brought down racial barriers through interaction, and above all, many African Americans demonstrated extraordinary strength of character in their fight for equality and acceptance into the Gettysburg College community. [excerpt

Three-dimensional Self-similar Fractal Light in Canonical Resonators

Unstable canonical resonators can possess eigenmodes with a fractal intensity structure [Karman et al., Nature 402, 138(1999)]. In one particular transverse plane, the intensity is not merely statistically fractal, but self-similar [Courtial and Padgett, PRL 85, 5320 (2000)]. This can be explained using a combination of diffraction and imaging with magnification greater than one. Here we show that the same mechanism also shapes the intensity cross-section in the longitudinal direction into a self-similar fractal, but with a different magnification. This results in three-dimensional, self-similar, fractal intensity structure in the eigenmodes

Shatter cones in Illinois: Evidence for metoeritic impacts at Glasford and Des Plaines

Shatter cone fragments were recovered from rock cores at two previously suspected, but heretofore unverified, impact structures in Illinois. Both sites are buried features known from geophysical surveys and drill holes. Shatter cones are accepted widely as field criteria of meteoritic impact. Detection of these shock indicators in both the Glasford Structure and the Des Plains Disturbance upgrades these sites in Earth's inventory of known and suspected impact structures from possible impact sites with compatible structure and morphology to probable impact structures which possess also evidence of shock metamorphism

Neogene grabens in southernmost Illinois

National Earthquake Hazards Reduction Program Award No. 1434-HQ-97-GR-03195Ope

Neogene grabens in southernmost Illinois

U.S. Geological Survey, Department of the Interior, National Earthquake Hazards Reduction Program Award No. 1434-HQ-97-GR-03195Ope

Chemical mechanical polishing of thin film diamond

The demonstration that Nanocrystalline Diamond (NCD) can retain the superior Young's modulus (1,100 GPa) of single crystal diamond twinned with its ability to be grown at low temperatures (<450 {\deg}C) has driven a revival into the growth and applications of NCD thin films. However, owing to the competitive growth of crystals the resulting film has a roughness that evolves with film thickness, preventing NCD films from reaching their full potential in devices where a smooth film is required. To reduce this roughness, films have been polished using Chemical Mechanical Polishing (CMP). A Logitech Tribo CMP tool equipped with a polyurethane/polyester polishing cloth and an alkaline colloidal silica polishing fluid has been used to polish NCD films. The resulting films have been characterised with Atomic Force Microscopy, Scanning Electron Microscopy and X-ray Photoelectron Spectroscopy. Root mean square roughness values have been reduced from 18.3 nm to 1.7 nm over 25 {\mu}m$^2$, with roughness values as low as 0.42 nm over ~ 0.25 {\mu}m$^2$. A polishing mechanism of wet oxidation of the surface, attachment of silica particles and subsequent shearing away of carbon has also been proposed.Comment: 6 pages, 6 figure