Significance of electrokinetic characterization for interpreting interfacial phenomena at planar, macroscopic interfaces

Journal ArticleStreaming potential measurements provide valuable information for the validation and interpretation of interfacial phenomena that occur at flat macroscopic surfaces. Planar substrates have been extensively used for the interpretation of events, which occur at particulate surfaces; however, these flat surfaces are often only questionably representative of their particulate counterparts due to variations in surface chemistry and topography. In this study, the zeta potential from planar macroscopic surfaces of PMMA, mica, graphite, fluorite, and calcite have been calculated from streaming potentials measured in aqueous solutions using an asymmetric clamping cell. These zeta potentials have been found to significantly contribute to understanding and interpretation of interfacial phenomena influenced by Coulombic interactions including adsorption, surface forces, and the structure of surface micelles

Ecologically Sensitive Wetlands on Maui: Groundwater Protection Strategy for Hawaii

The EPA Ground-Water Protection Strategy has established differential protection levels based on the beneficial uses of groundwaters. Groundwater resources that are: (1) Irreplaceable sources of drinking water; and/or (2) Ecologically Vital are designated as of unusually high value. To determine those groundwaters that meet the EPA criteria for qualifying as “Ecologically Vital” we have examined 24 groundwater based (wetland) ecological systems on the island of Maui. An inventory of the physical, biological and cultural characteristics of each area including “red flag” features has been developed and coded. Using this “habitat code” a rating system that reflects the sensitivity, i.e. “uniqueness” of “nonrenewable” attributes of each system was designed and 18 “ecologically vital” habitats were identified that meet the EPA criteria for Class 1 level of groundwater protection. Insufficient information was available to determine the sensitivity of one of the sites.Department of Health, State of Hawai

Resonance- and Chaos-Assisted Tunneling

We consider dynamical tunneling between two symmetry-related regular islands that are separated in phase space by a chaotic sea. Such tunneling processes are dominantly governed by nonlinear resonances, which induce a coupling mechanism between ``regular'' quantum states within and ``chaotic'' states outside the islands. By means of a random matrix ansatz for the chaotic part of the Hamiltonian, one can show that the corresponding coupling matrix element directly determines the level splitting between the symmetric and the antisymmetric eigenstates of the pair of islands. We show in detail how this matrix element can be expressed in terms of elementary classical quantities that are associated with the resonance. The validity of this theory is demonstrated with the kicked Harper model.Comment: 25 pages, 5 figure

Nuclear Spin-Isospin Correlations, Parity Violation, and the fπf_\pi Problem

The strong interaction effects of isospin- and spin-dependent nucleon-nucleon correlations observed in many-body calculations are interpreted in terms of a one-pion exchange mechanism. Including such effects in computations of nuclear parity violating effects leads to enhancements of about 10%. A larger effect arises from the one-boson exchange nature of the parity non-conserving nucleon- nucleon interaction, which depends on both weak and strong meson-nucleon coupling constants. Using values of the latter that are constrained by nucleon-nucleon phase shifts leads to enhancements of parity violation by factors close to two. Thus much of previously noticed discrepancies between weak coupling constants extracted from different experiments can be removed.Comment: 8 pages 2 figures there should have been two figures in v

Exact Solutions for Matter-Enhanced Neutrino Oscillations

The analogy between supersymmetric quantum mechanics and matter-enhanced neutrino oscillations is exploited to obtain exact solutions for a class of electron density profiles. This integrability condition is analogous to the shape-invariance in supersymmetric quantum mechanics. This method seems to be the most direct way to obtain the exact survival probabilities for a number of density profiles of interest, such as linear and exponential density profiles. The resulting neutrino amplitudes can also be utilized as comparison amplitudes for the uniform semiclassical treatment of neutrino propagation in arbitrary electron density profiles.Comment: Submitted to Physical Review D. Latex file, 8 pages. This paper is also available at http://nucth.physics.wisc.edu/preprints

Multidisciplinary Design Optimization of an Extreme Aspect Ration HALE UAV

Development of High Altitude Long Endurance (HALE) aircraft systems is part of a vision for a low cost communications/surveillance capability. Applications of a multi payload aircraft operating for extended periods at stratospheric altitudes span military and civil genres and support battlefield operations, communications, atmospheric or agricultural monitoring, surveillance, and other disciplines that may currently require satellite-based infrastructure. The central goal of this research was the development of a multidisciplinary tool for analysis, design, and optimization of HALE UAVs, facilitating the study of a novel configuration concept. Applying design ideas stemming from a unique WWII-era project, a pinned wing HALE aircraft would employ self-supporting wing segments assembled into one overall flying wing. When wrapped in an optimization routine, the integrated design environment shows potential for a 17.3% reduction in weight when wing thickness to chord ratio, aspect ratio, wing loading, and power to weight ratio are included as optimizer-controlled design variables. Investigation of applying the sustained day/night mission requirement and improved technology factors to the design shows that there are potential benefits associated with a segmented or pinned wing. As expected, wing structural weight is reduced, but benefits diminish as higher numbers of wing segments are considered. For an aircraft consisting of six wing segments, a maximum of 14.2% reduction in gross weight over an advanced technology optimal baseline is predicted

Spinless particle in rapidly fluctuating random magnetic field

We study a two-dimensional spinless particle in a disordered gaussian magnetic field with short time fluctuations, by means of the evolution equation for the density matrix $$; in this description the two coordinates are associated with the retarded and advanced paths respectively. The static part of the vector potential correlator is assumed to grow with distance with a power $h$; the case $h = 0$ corresponds to a $\delta$-correlated magnetic field, and $h = 2$ to free massless field. The value $h = 2$ separates two different regimes, diffusion and logarithmic growth respectively. When $h < 2$ the baricentric coordinate $r = (1/2)(x^{(1)} + x^{(2)})$ diffuses with a coefficient $D_{r}$ proportional to $x^{-h}$, where $x$ is the relative coordinate: $x = x^{(1)} - x^{(2)}$. As $h > 2$ the correlator of the magnetic field is a power of distance with positive exponent; then the coefficient $D_{r}$ scales as $x^{-2}$. The density matrix is a function of $r$ and $x^2/t$,and its width in $r$ grows for large times proportionally to $log(t/x^2)$.Comment: latex2e; 2 figure