5,884 research outputs found
Portrait of Thaddeus Stevens by Jacob Eichholtz
When we were approached to do a paper on the hidden history of an object in Gettysburg College, a colleague and I decided to take a weekend afternoon to walk around the campus in order to find an object to write about. After wandering for a while, we entered Penn Hall, and in the Lyceum we looked at the portraits of great contributors to Gettysburg College. One face that struck me was that of Thaddeus Stevens, who I remembered as one of the great Radical Republicans of the Civil War era. Gettysburg is very much a Civil War oriented area. However, I wondered what made Thaddeus Stevens so important as to merit a painting in the Lyceum. I then, embarrassedly realized that Stevens was also the namesake of Stevens Hall, and that clearly he must have been very important to the area. So what exactly warranted his place in Penn Hall and in the name of a building? [excerpt]
Course Information: Course Title: HIST 300: Historical Method Academic Term: Spring 2006 Course Instructor: Dr. Michael J. Birkner \u2772
Hidden in Plain Sight is a collection of student papers on objects that are hidden in plain sight around the Gettysburg College campus. Topics range from the Glatfelter Hall gargoyles to the statue of Eisenhower and from historical markers to athletic accomplishments. You can download the paper in pdf format and click View Photo to see the image in greater detail.https://cupola.gettysburg.edu/hiddenpapers/1017/thumbnail.jp
Non-geometric branes are DFT monopoles
The double field theory monopole solution by Berman and Rudolph is shown to
reproduce non-geometric backgrounds with non-vanishing Q- and R-flux upon an
appropriate choice of physical and dual coordinates. The obtained backgrounds
depend non-trivially on dual coordinates and have only trivial monodromies.
Upon smearing the solutions along the dual coordinates one reproduces the known
solution for the Q-brane and co-dimension 1 solution for the R-brane.
The T-duality invariant magnetic charge is explicitly calculated for all these
backgrounds and is found to be equal to the magnetic charge of (unsmeared)
NS5-brane.Comment: 26 pages and appendi
Low-energy electron beam focusing in self-organized porous alumina vacuum windows
Micromachined, micron-thick porous alumina membranes with closed pore endings show high electron transparency above an energy of 5 keV. This is due to the channeling of electrons along the negatively charged insulating pores after surmounting the thin entrance layer. We also find a sharp hightransparency energy window at energies as low as 2 keV which may be the result of a local maximum of channeling, as predicted by simulations, and positive charge up of the entrance layer causing electron electrostatic focusing. Applications for these membranes range from atmospheric electron spectroscopy to self-assembled, nanoscale, large-area electron collimators
The different faces of branes in Double Field Theory
We show how the Wess-Zumino terms of the different branes in string theory
can be embedded within double field theory. Crucial ingredients in our
construction are the identification of the correct brane charge tensors and the
use of the double field theory potentials that arise from dualizing the
standard double field theory fields. This leads to a picture where under
T-duality the brane does not change its worldvolume directions but where,
instead, it shows different faces depending on whether some of the worldvolume
and/or transverse directions invade the winding space. As a non-trivial
by-product we show how the different Wess-Zumino terms are modified when the
brane propagates in a background with a non-zero Romans mass parameter.
Furthermore, we show that for non-zero mass parameter the brane creation
process, when one brane passes through another brane, gets generalized to brane
configurations that involve exotic branes as well.Comment: 23 pages + Appendi
Time scale of entropic segregation of flexible polymers in confinement: Implications for chromosome segregation in filamentous bacteria
We report molecular dynamics simulations of the segregation of two
overlapping chains in cylindrical confinement. We find that the entropic
repulsion between the chains can be sufficiently strong to cause segregation on
a time scale that is short compared to the one for diffusion. This result
implies that entropic driving forces are sufficiently strong to cause rapid
bacterial chromosome segregation.Comment: Minor changes. Added some references, corrected the labels in figure
6 and reformatted in two columns. Also added reference to published version
in PR
Mask pattern transferred transient grating technique for molecular-dynamics study in solutions
We have developed a mask pattern transferred transient grating (MPT-TG) technique by using metal grating films. Transient thermal grating is generated by an ultraviolet light pattern transfer to nitrobenzene in 2-propanol solution, and the subsequent effect is detected through its diffraction to a probe beam. The thermal diffusion coefficient is obtained by the relationship between the grating periods and the signal decay lifetime, and is well in agreement with the calculated value. This technique has many advantages, such as a simple setting, an easy alignment, accurate phase control, and high stability for molecular-dynamics study in solutions
Quantum Fluctuations in Dipolar Bose Gases
We investigate the influence of quantum fluctuations upon dipolar Bose gases
by means of the Bogoliubov-de Gennes theory. Thereby, we make use of the local
density approximation to evaluate the dipolar exchange interaction between the
condensate and the excited particles. This allows to obtain the Bogoliubov
spectrum analytically in the limit of large particle numbers. After discussing
the condensate depletion and the ground-state energy correction, we derive
quantum corrected equations of motion for harmonically trapped dipolar Bose
gases by using superfluid hydrodynamics. These equations are subsequently
applied to analyze the equilibrium configuration, the low-lying oscillation
frequencies, and the time-of-flight dynamics. We find that both atomic magnetic
and molecular electric dipolar systems offer promising scenarios for detecting
beyond mean-field effects.Comment: Published in PR
GPU-accelerated discontinuous Galerkin methods on hybrid meshes
We present a time-explicit discontinuous Galerkin (DG) solver for the
time-domain acoustic wave equation on hybrid meshes containing vertex-mapped
hexahedral, wedge, pyramidal and tetrahedral elements. Discretely energy-stable
formulations are presented for both Gauss-Legendre and Gauss-Legendre-Lobatto
(Spectral Element) nodal bases for the hexahedron. Stable timestep restrictions
for hybrid meshes are derived by bounding the spectral radius of the DG
operator using order-dependent constants in trace and Markov inequalities.
Computational efficiency is achieved under a combination of element-specific
kernels (including new quadrature-free operators for the pyramid), multi-rate
timestepping, and acceleration using Graphics Processing Units.Comment: Submitted to CMAM
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