Birthing Washington: Objects, memory, and the creation of a national monument

The National Park Service\u27s (NPS) George Washington Birthplace National Monument has commemorated Washington and his life for over seventy-five years. For much of that time, the NPS worked closely with the memorial\u27s progenitors, the \u27ladies\u27 of the Wakefield National Memorial Association (WNMA). Although equally committed to the preservation of Washington\u27s legacy, these two groups clashed over questions of authenticity, historical authority, and proper commemorative strategy. This dissertation explores their relationship for what it reveals about the rise of public history in this country and Federal involvement therein.;We witness at Washington\u27s birthplace a collision between old-order Colonial Revivalists (led for a time by renowned preservationist Louise DuPont Crowninshield) and a new generation of male museum professionals under NPS Director Horace Albright. The WNMA erected a \u27replica\u27 Memorial House atop a site marked in 1815 by George Washington Parke Custis. The NPS determined the Memorial House was neither properly located nor an authentic replica. Still, the WNMA defended the building\u27s veracity. Birthing Washington argues that the two groups defined authenticity differently and that those definitions reflected not only gendered difference and political motivation, but also new ways of constituting historical knowledge available during the first half of the twentieth century.;What began as a confused argument about authenticity manifested publicly in decisions made about what kind of objects to display at Washington\u27s birthplace and how to display them. The WNMA preferred charming interiors to the NPS\u27s stark historical realism. Both methods created considerable interpretive possibilities and limitations. Buoyed by national trends, historical realism prevailed at Washington\u27s birthplace. But \u27living history\u27 only created new interpretive dilemmas by failing to grapple with old questions about authenticity perpetuated by the Memorial House\u27s ongoing presence. I conclude that sites of public memory cannot help but reify the historical currents of their formative moments and, for that reason, the NPS must challenge itself to interpret the history of commemoration at sites like Washington\u27s birthplace

Influence of organic molecules on the aggregation of TiO2 nanoparticles in acidic conditions

Engineered nanoparticles released into the environment may interact with natural organic matter (NOM). Surface complexation affects the surface potential, which in turn may lead to aggregation of the particles. Aggregation of synthetic TiO2 (anatase) nanoparticles in aqueous suspension was investigated at pH 2.8 as a function of time in the presence of various organic molecules and Suwannee River fulvic acid (SRFA), using dynamic light scattering (DLS) and high-resolution transmission electron microscopy (TEM). Results showed that the average hydrodynamic diameter and ?-potential were dependent on both concentration and molecular structure of the organic molecule. Results were also compared with those of quantitative batch adsorption experiments. Further, a time study of the aggregation of TiO2 nanoparticles in the presence of 2,3-dihydroxybenzoic acid (2,3-DHBA) and SRFA, respectively, was performed in order to observe changes in ?-potential and particle size over a time period of 9 months. In the 2,3-DHBA-TiO2 system, ?-potentials decreased with time resulting in charge neutralization and/or inversion depending on ligand concentration. Aggregate sizes increased initially to the micrometer size range, followed by disaggregation after several months. No or very little interaction between SRFA and TiO2 occurred at the lowest concentrations tested. However, at the higher concentrations of SRFA, there was an increase in both aggregate size and the amount of SRFA adsorbed to the TiO2 surface. This was in correlation with the ?-potential that decreased with increased SRFA concentration, leading to destabilization of the system. These results stress the importance of performing studies over both short and long time periods to better understand and predict the long-term effects of nanoparticles in the environment

Memorials and monuments

An essay republished from The Inclusive Historian’s Handbook, a free, online resource, sponsored by the American Association for State and Local History and the National Council on Public History (inclusivehistorian.com)

Memorials and monuments

An essay republished from The Inclusive Historian’s Handbook, a free, online resource, sponsored by the American Association for State and Local History and the National Council on Public History (inclusivehistorian.com)

Passenger mutations confound interpretation of all genetically modified congenic mice

Targeted mutagenesis in mice is a powerful tool for functional analysis of genes. However, genetic variation between embryonic stem cells (ESCs) used for targeting (previously almost exclusively 129-derived) and recipient strains (often C57BL/6J) typically results in congenic mice in which the targeted gene is flanked by ESC-derived passenger DNA potentially containing mutations. Comparative genomic analysis of 129 and C57BL/6J mouse strains revealed indels and single nucleotide polymorphisms resulting in alternative or aberrant amino acid sequences in 1,084 genes in the 129-strain genome. Annotating these passenger mutations to the reported genetically modified congenic mice that were generated using 129-strain ESCs revealed that nearly all these mice possess multiple passenger mutations potentially influencing the phenotypic outcome. We illustrated this phenotypic interference of 129-derived passenger mutations with several case studies and developed a Me-PaMuFind-It web tool to estimate the number and possible effect of passenger mutations in transgenic mice of interest