Silent Doorway to the Past: “Vigil” Painting in Weidensall Hall

Every object has a story waiting to be told. There is one such artifact that hangs boldly on the mantle of the fireplace in Weidensall Hall its presence large and demanding. The plaque reads “‘The Vigil’ Presented in honor of Mrs. H.W.A. Hanson by the Altoona League.” The artist’s signature is absent from the painting. The painting acts as a window into the history of Gettysburg College. One cannot understand the history of “The Vigil” without knowing the story of the Woman’s League of Gettysburg College, or of Robert Weidensall and the Young Men’s Christian Association. “The Vigil” that hangs conspicuously in Weidensall lobby manages to be discreet in its presence. In other words, it is hidden in plain sight.1 Once researched however, this painting tells a colorful and intriguing story about the history of Gettysburg College. The painting “The Vigil” is symbolic of the College’s historical progression through the aid of religious and service organizations. [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/1003/thumbnail.jp

Mobility Extraction and Quantum Capacitance Impact in High Performance Graphene Field-effect Transistor Devices

The field-effect mobility of graphene devices is discussed. We argue that the graphene ballistic mean free path can only be extracted by taking into account both, the electrical characteristics and the channel length dependent mobility. In doing so we find a ballistic mean free path of 300nm at room-temperature for a carrier concentration of ~1e12/cm2 and that a substantial series resistance of around 300ohmum has to be taken into account. Furthermore, we demonstrate first quantum capacitance measurements on single-layer graphene devices

Electronic transport properties of a tilted graphene pn junction

Spatial manipulation of current flow in graphene could be achieved through the use of a tilted pn junction. We show through numerical simulation that a pseudo-Hall effect (i.e. non-equilibrium charge and current density accumulating along one of the sides of a graphene ribbon) can be observed under these conditions. The tilt angle and the pn transition length are two key parameters in tuning the strength of this effect. This phenomenon can be explained using classical trajectory via ray analysis, and is therefore relatively robust against disorder. Lastly, we propose and simulate a three terminal device that allows direct experimental access to the proposed effect.Comment: 7 pages, 7 figure

Inclination effects in T Tauri star spectra

CONTEXT. Because of the presence of rotation and accretion disks, classical T Tauri stars have symmetry planes that are normally inclined relative to the plane of the sky. The inclination angles affect the observed spectral properties of these objects. AIMS. We study the influence of the inclination angles on classical T Tauri star spectra in an empirical manner. METHODS. Published inclination angles, derived from the stellar photospheric rotation or from spatially resolved circumstellar disk observations, are compared with various observed spectral properties, and correlations are established and investigated. RESULTS. Inclinations derived from the stellar rotation are found to be much less accurate than the published disk inclinations, and no significant correlations between spectral properties and inclinations based on rotation data could be detected. In contrast, significant correlations are found between the disk inclination angles and the apparent velocities observed for the forbidden emission lines and the wind absorption features of permitted lines. These data support the assumption of cone-like polar winds with opening angles smaller than $\approx 45^\circ$. Other spectral features show weaker or no inclination dependence. Using these results, the true (deprojected) flow velocities of the polar winds are derived for the investigated sample of T Tauri stars. Deprojected wind-ejection velocities appear to differ by a factor of two among the stars in our sample, which spans a range of mass-loss rates from $10^{-10}$M$_\odot$/yr to $3 \times 10^{-7}$M$_\odot$/yr.Comment: accepted by Astronomy and Astrophysic

Improved modeling of Coulomb effects in nanoscale Schottky-barrier FETs

We employ a novel multi-configurational self-consistent Green's function approach (MCSCG) for the simulation of nanoscale Schottky-barrier field-effect transistors. This approach allows to calculate the electronic transport with a seamless transition from the single-electron regime to room temperature field-effect transistor operation. The particular improvement of the MCSCG stems from a division of the channel system into a small subsystem of resonantly trapped states for which a many-body Fock space becomes feasible and a strongly coupled rest which can be treated adequately on a conventional mean-field level. The Fock space description allows for the calculation of few-electron Coulomb charging effects beyond mean-field. We compare a conventional Hartree non-equilibrium Green's function calculation with the results of the MCSCG approach. Using the MCSCG method Coulomb blockade effects are demonstrated at low temperatures while under strong nonequilibrium and room temperature conditions the Hartree approximation is retained

Spectropolarimetry of the borderline Seyfert 1 galaxy ESO 323-G077

We report the detection of high linear polarization in the bright Seyfert 1 galaxy ESO 323-G077. Based on optical spectropolarimetry with FORS1 at the VLT we find a continuum polarization which ranges from 2.2 % at 8300A to 7.5 % at 3600A. Similar amounts of linear polarization are found for the broad emission lines, while the narrow lines are not polarized. The position angle of the polarization is independent of the wavelength and found to be perpendicular to the orientation of the extended [OIII] emission cone of this galaxy. Within the standard model of Seyfert nuclei the observations can be well understood assuming that this AGN is observed at an inclination angle where the nucleus is partially obscured and seen mainly indirectly in the light scattered by dust clouds within or above the torus and the illuminated inner edge of the dust torus itself. Hence we conclude that ESO 323-G077 is a borderline Seyfert 1 galaxy which can provide important information on the geometric properties of active nuclei