Quartz and Prehnite: Minerals during the Renaissance

Minerals were displayed in wonder rooms for their beauty and used by apothecaries for their medical properties and artists, for sculptures and pigments. Minerals during the Renaissance were collected and displayed in wonder rooms to illustrate the beauty of nature. Humanists would have categorized minerals by their external qualities- color, transparency, form, luster, and smell. Over time, geologists continue to study these external qualities when they are first analyzing minerals, and the internal properties. Today the six major factors in identifying minerals are cleavage, the tendency of minerals to break into flat surfaces; color; crystal form or how the form of the mineral changes as the mineral crystallizes; hardness, the resistance to scratching to measure its strength; luster, the light reflection; and streak, the color of the streak left when a mineral is grinded on porcelain. [excerpt

The Things We Don’t See: Oppressive Mental Health Language in 1940’s East Texas

In the mental health files I examine, the oppressive mental health language, descriptions, and inaccurate twentieth-century perceptions of female patients will be brought to light and reexamined. It is my hope that, by doing so, the patients who suffered will be remembered, and their stories never again repeated

Plasma cleaning device

High vacuum cleaning of contaminated surfaces such as hydrocarbon containment films can be accomplished by a plasma cleaning device which includes a plasma discharge housing to permit generation of a plasma in an environment having a higher pressure than the surface which is to be cleaned. A ground electrode and a radio frequency electrode partially surround a quartz plasma tube, for the introduction of an ionizable gas. These electrodes ionize the gas and help generate the plasma. This plasma flows through a non-constrictive aperture, through the plasma discharge housing and then on to the contaminated surface

Classical Statistics Inherent in a Quantum Density Matrix

A density matrix formulation of classical bipartite correlations is constructed. This leads to an understanding of the appearance of classical statistical correlations intertwined with the quantum correlations as well as a physical underpinning of these correlations. As a byproduct of this analysis, a physical basis of the classical statistical correlations leading to additive entropy in a bipartite system discussed recently by Tsallis et al emerges as inherent classical spin fluctuations. It is found that in this example, the quantum correlations shrink the region of additivity in phase space.Comment: 10 pages, 3 figure

Design of a variable-focal-length optical system

Requirements to place an entire optical system with a variable focal length ranging from 20 to 200 cm within a overall length somewhat less than 100 cm placed severe restrictions on the design of a zoom lens suitable for use on a comet explorer. The requirements of a wavelength range of 0.4 to 1.0 microns produced even greater limitations on the possibilities for a design that included a catadioptric (using mirrors and glass) front and followed by a zooming refractive portion. Capabilities available commercial zoom lenses as well as patents of optical systems are reviewed. Preliminary designs of the refractive optics zoom lens and the catadioptric system are presented and evaluated. Of the two, the latter probably has the best chance of success, so long as the shortest focal lengths are not really needed

MS-057: The Papers of Donna O. Schaper, Class of 1969: The Gettysburg Years

This collection consists of correspondence and college papers from Donna Osterhoudt Schaper, who graduated from Gettysburg College in 1969. As a student, she was part of the student protest movement against the Vietnam War, and she interned for the College Chapel before attending the Lutheran Theological Seminary. Special Collections and College Archives Finding Aids are discovery tools used to describe and provide access to our holdings. Finding aids include historical and biographical information about each collection in addition to inventories of their content. More information about our collections can be found on our website http://www.gettysburg.edu/special_collections/collections/.https://cupola.gettysburg.edu/findingaidsall/1052/thumbnail.jp

Orbital ordering in the ferromagnetic insulator Cs2_2AgF4_4 from first principles

We found, using density-functional theory calculations within the generalized gradient approximation, that Cs$_2$AgF$_4$ is stabilized in the insulating orthorhombic phase rather than in the metallic tetragonal phase. The lattice distortion present in the orthorhombic phase corresponds to the $x^2-z^2$/$y^2-z^2$ hole-orbital ordering of the Ag$^{2+}$ $4d^9$ ions, and this orbital ordering leads to the observed ferromagnetism, as confirmed by the present total-energy calculations. This picture holds in the presence of moderate 4d-electron correlation. The results are compared with the picture of ferromagnetism based on the metallic tetragonal phase.Comment: 5 pages, 4 figures, 1 table; a few energy/moment entries in Table I are corrected due to a proper treatment of the Ag 4s semicore stat