The Third-Annual Abolitionists’ Day Event

Three years ago, Adams County declared the first ever Abolitionists Day—a day dedicated to honoring the lives of the county’s abolitionists. The county’s abolitionists were a varied group, comprised of both whites and free blacks, men and women. Through their efforts, thousands of slaves were able to find their freedom in the North. One impressive couple, William and Phebe Wright, helped approximately one thousand men, women, and children to freedom. Adams County was also home to Thaddeus Stevens, a Gettysburg resident who used his position in the US House of Representatives to fight against the institution of slavery. With people as distinguished as these in the county’s history, it is fitting that the county has set aside a day to commemorate them. To aid in this commemoration, several groups from the county came together to create a two-hour program that honored these abolitionists and educated modern county residents about their legacy in a performance that featured a collection of skits, talks, and music. [excerpt

A Song for Jennie

The simple tune was created by lyricist E. B. Dewing and composer J. P. Webster who hoped they would inspire patriotism in their female audience while they worked to become accomplished musicians. When the Civil War broke out, the young women who played the piece had been left behind on the home front, only to imagine what horrors their men were facing. The government and the warfront alike relied on the homefront to present a brave and loyal face in order to maintain support for the war effort through the fostering of a nationalistic, sentimental culture that bled into all aspects of Union life. Music was a feminine expression of patriotic devotion that many women used to empathize with those on the battle front as well as to inspire themselves and their peers toward acts of patriotic sacrifice on behalf of their war-torn nation. After the war ended and America moved into Reconstruction, music like “Jennie Wade, the Heroine of Gettysburg” continued to inspire women, who were busy honoring the dead and healing the country’s gaping wounds. [excerpt

The aerobic treatment of reverse osmosis permeate for reuse : a thesis submitted in partial fulfilment of the requirements for the degree of Master of Technology in Environmental Engineering

The reduction of effluent streams and the demand for freshwater intake in the dairy industry, may be accomplished by the segregation and reuse of streams that can be readily treated. This study assessed the biodegradability and suitability for reuse of reverse osmosis (R/O) permeate from Kiwi Dairies Ltd processing factory (Hawera), using aerobic treatment. Analysis of the permeate showed that there was a direct relationship between chemical oxygen and lactose concentration. The chemical oxygen demand of R/O permeate from two reverse osmosis membrane plants operating in parallel varied widely during the period of study. This wide variation in permeate chemical oxygen was directly related to the membrane efficiency. Elemental analysis of the R/O permeate showed that iron and phosphorous would need to be supplemented to ensure balanced microbial growth. The biodegradability was characterised by a series of batch tests to determine the biokinetic constants µm, Ks, qsm and Yt. These tests showed that the biodegradability of reverse osmosis permeate is comparable to general dairy wastes. Batch tests were also performed on permeate from R/O membranes of varying performance efficiency, with different lactose and mineral concentrations. There were no conclusive variations in biokinetic constants between permeates from R/O membranes of varying performance efficiency. Operation of a model activated sludge pilot plant showed that soluble COD removal efficiencies of over 90% could be achieved at hydraulic retention times of 10 and 20 hours. The sludge settling characteristics were more favourable at a 10 hour hydraulic retention time. Sudden fluctuations in membrane efficiency caused shock loads resulting in a deterioration in treatment efficiency and sludge settling characteristics. Although the pilot plant achieved satisfactory reductions, soluble COD levels were not decreased to the level of 10 to 15 mg l -1 required to enable the reuse of the permeate. In order to determine if low substrate levels could be achieved when aerobically treating R/O permeate from an efficient membrane plant, a laboratory scale reactor was used to treat permeate with a COD of 200 mg l-1. It was established that R/O permeate could be aerobically treated to levels suitable for reuse, provided the previous membrane processes performed efficiently

Magnetic incommensurability and fluctuating charge density waves in the repulsive Hubbard model

Magnetic and charge susceptibilities of the two-dimensional repulsive Hubbard model are investigated applying a strong coupling diagram technique in which the expansion in powers of the hopping constants is used. For small lattices and high temperatures results are in agreement with Monte Carlo simulations. With the departure from half-filling $x$ the low-frequency magnetic susceptibility becomes incommensurate and the incommensurability parameter grows with $x$. The incommensurability, its dependence on frequency and on $x$ resemble experimental results in lanthanum cuprates. Also for finite $x$ sharp maxima appear in the static charge susceptibility. The maxima are finite which points to the absence of the long-range charge ordering (static stripes). However, for $x\approx 0.12$ the maxima are located near the momenta $(0,\pm\pi/2)$, $(\pm\pi/2,0)$. In this case an interaction of carriers with tetragonal distortions can stabilize stripes with the wavelength of four lattice spacings, as observed in the low-temperature tetragonal phase of cuprates. As follows from the obtained results, the magnetic incommensurability is not a consequence of the stripes.Comment: 4 pages, 3 figures, manuscript for proceefings of LT2

A planar diagram approach to the correlation problem

We transpose an idea of 't Hooft from its context of Yang and Mills' theory of strongly interacting quarks to that of strongly correlated electrons in transition metal oxides and show that a Hubbard model of N interacting electron species reduces, to leading orders in N, to a sum of almost planar diagrams. The resulting generating functional and integral equations are very similar to those of the FLEX approximation of Bickers and Scalapino. This adds the Hubbard model at large N to the list of solvable models of strongly correlated electrons. PACS Numbers: 71.27.+a 71.10.-w 71.10.FdComment: revtex, 5 pages, with 3 eps figure

Beyond the Nca: New Results for the Spectral Properties of the Anderson Model

In the framework of direct perturbation theory a fully self-consistent approximation beyond the well known NCA will be presented for the Anderson Model. The resummation of a class of skeleton diagrams up to infinite order in $V$ includes all contribution up to the order $O(1/N^2)$ ( $N$ = degeneracy of the magnetic state). Qualitative improvements in maintaining local Fermi-Liquid relations and one-particle spectral properties in comparison to the well known NCA will be reported. The location and temperature dependence of the AS-resonance for the case $N=2$ is found to be rather close to the chemical potential in excellent agreement with Friedel's sum rule; the static magnetic susceptibility exhibits the same $N$-dependence as the exact {\em Bethe-Ansatz} solution.Comment: 3 pages including 4 figures, Postscript file, self-extracting shell script;(submitted to the SCES 94 Conference, Amsterdam

The Remnants of the Crater

This post is part of a series featuring behind-the-scenes dispatches from our Pohanka Interns on the front lines of history this summer as interpreters, archivists, and preservationists. See here for the introduction to the series. In the final years of the Civil War, the Army of the Potomac laid siege to Petersburg, Virginia. Petersburg was the center of supply for both the city of Richmond and Lee’s Army of Northern Virginia, and Grant understood that he could cripple the Confederate army by capturing the city. He hoped to end the battle quickly, but through a series of missteps and complicated battle scenarios, the siege lasted more than nine months—longer than any other Civil War battle. [excerpt

Theory for the Doping Dependence of Spin Fluctuation Induced Shadow States in High-Tc_{c} Superconductors

We analyze the doping dependence of the intensity and energetical position of shadow states in high -T$_{c}$ superconductors within the 2D Hubbard model and using our recently developed numerical method for the self consistent summation of bubble and ladder diagrams. It is shown that shadow states resulting from short range antiferromagnetic correlations occur for small but finite excitation energies which decrease for decreasing doping, reflecting a dynamically broken symmetry with increasing lifetime. Simultanously, the intensity of these new states increases, the quasiparticle dispersion is strongly flattened, and a pseudogap in the density of states occurs. Finally, we discuss the importance of flat bands at the Fermi level and nesting of the Fermi surface as general prerequisites for the observability of shadow states.Comment: 9 pages (TeX) with 3 figures (Postscript