Universality in edge-source diffusion dynamics

We show that in edge-source diffusion dynamics the integrated concentration N(t) has a universal dependence with a characteristic time-scale tau=(A/P)^2 pi/(4D), where D is the diffusion constant while A and P are the cross-sectional area and perimeter of the domain, respectively. For the short-time dynamics we find a universal square-root asymptotic dependence N(t)=N0 sqrt(t/tau) while in the long-time dynamics N(t) saturates exponentially at N0. The exponential saturation is a general feature while the associated coefficients are weakly geometry dependent.Comment: 4 pages including 4 figures. Minor changes. Accepted for PR

The Implications of Content Analysis for the Interpretation of Unguentaria in Museum Collections

Scent has traditionally been an ephemeral component of rituals in ancient societies, including burial and other practices associated with the anointing of the body (Classen et al. 1994: 43; Houston and Taube 2000: 271). This thesis investigates the possible signifiers and social impact such scents might have had for individuals participating in such rituals by using the little explored approach of sensory archaeology. A discussion of the correlation between olfaction and the triggering of both the experiential and emotional aspects of memory contributes to a broader view of these rituals in the anthropological literature (Classen et al. 1994), while Houston and Taube\u27s work on scent in Mayan rituals provides a framework for applying sensory archaeology to Classical contexts (2000). Vessel contents are used as a proxy in this thesis for reconstructing the particular olfactory atmosphere associated with mortuary ritual in late Greek and early Roman cultural contexts. The residue spectra derived from the visible contents of twenty-seven out of a total of thirty-nine small glass and ceramic vials from collections at the Milwaukee Public Museum (MPM) are compared to other unguentaria residue studies as well as Greek and Roman written sources in which scented unguents, oils, perfumes, creams, and cosmetics are described to test the archaeological classification of this vessel category. Stylistic conventions are tested against data derived from content analysis rather than solely on the basis of assumed function implied by form. The chemical characterization of the contents of these vessels relies on the use of inductively coupled plasma-mass spectrometry (ICP-MS) and Fourier transform-infrared spectroscopy (FTIR). FT-IR was chosen for its successful application in a recent residue study of unguentaria (Ribechini et al. 2008a-b) while ICP-MS analysis was performed based upon its widespread application to the determination of sample origin

Improved Load Alleviation Capability for the KC-135

The Air Force will greatly increase its use of Unmanned Aerial Vehicles (UAVs) in the next century and the latter part of this decade. These UAVs will require refueling like their manned counterparts. The KC-135 and the KC-10 are candidates to provide this refueling task. The KC-10 is equipped with an automatic load alleviation system on its refueling boom which minimizes radial loads at the receiver of the aircraft being refueled. The KC-135 does not have such a system on its boom. Because the boom operator relies on visual cues to tell him when the boom is bending to adjust the boom\u27s ruddevators, large loads may be imparted to receiver aircraft at the fuel receiver port. While load alleviation is required for all aircraft in order to ensure that binding of the nozzle does not prevent disconnect, load alleviation may also be important for the lightweight UAV in order to prevent unwanted disturbance to its flight control system. A Controller was designed to control the longitudinal motion of the boom. This controller can control the angle of the boom so no forces are imparted to the nozzle as the tanker moves from its nominal orientation. The optimal controller design uses both feed forward and rate feedback to modulate the commanded torque signal sent to the ruddevators. The results show that using an automatic controller promises to provide accurate control of the KC-135 refueling boom during refueling operations with minimal nozzle forces being imparted to the receiver aircraft

Plasmon-exciton polaritons in 2D semiconductor/metal interfaces

The realization and control of polaritons is of paramount importance in the prospect of novel photonic devices. Here, we investigate the emergence of plasmon-exciton polaritons in hybrid structures consisting of a two-dimensional (2D) transition metal dichalcogenide (TMDC) deposited onto a metal substrate or coating a metallic thin-film. We determine the polaritonic spectrum and show that, in the former case, the addition of a top dielectric layer, and, in the latter, the thickness of the metal film,can be used to tune and promote plasmon-exciton interactions well within the strong coupling regime. Our results demonstrate that Rabi splittings exceeding 100 meV can be readily achieved in planar dielectric/TMDC/metal structures under ambient conditions. We thus believe that this work provides a simple and intuitive picture to tailor strong coupling in plexcitonics, with potential applications for engineering compact photonic devices with tunable optical properties.Comment: 6 pages, including 5 figures and reference

Economic Effects of the 1988 Drought in North Dakota: A 1989 Update of the Financial Conditions of Farm and Ranch Operators

Agricultural Finance, Farm Management, Resource /Energy Economics and Policy,

Outlook of North Dakota Farm Households: Results of the 1988 Longitudinal Farm Survey

Agricultural Finance, Farm Management,

The scattering of a cylindrical invisibility cloak: reduced parameters and optimization

We investigate the scattering of 2D cylindrical invisibility cloaks with simplified constitutive parameters with the assistance of scattering coefficients. We show that the scattering of the cloaks originates not only from the boundary conditions but also from the spatial variation of the component of permittivity/permeability. According to our formulation, we propose some restrictions to the invisibility cloak in order to minimize its scattering after the simplification has taken place. With our theoretical analysis, it is possible to design a simplified cloak by using some peculiar composites like photonic crystals (PCs) which mimic an effective refractive index landscape rather than offering effective constitutives, meanwhile canceling the scattering from the inner and outer boundaries.Comment: Accepted for J. Phys.