Instrumentation for Millimeter-wave Magnetoelectrodynamic Investigations of Low-Dimensional Conductors and Superconductors

We describe instrumentation for conducting high sensitivity millimeter-wave cavity perturbation measurements over a broad frequency range (40-200 GHz) and in the presence of strong magnetic fields (up to 33 tesla). A Millimeter-wave Vector Network Analyzer (MVNA) acts as a continuously tunable microwave source and phase sensitive detector (8-350 GHz), enabling simultaneous measurements of the complex cavity parameters (resonance frequency and Q-value) at a rapid repetition rate (approx. 10 kHz). We discuss the principal of operation of the MVNA and the construction of a probe for coupling the MVNA to various cylindrical resonator configurations which can easily be inserted into a high field magnet cryostat. We also present several experimental results which demonstrate the potential of the instrument for studies of low-dimensional conducting systems.Comment: 20 pages including fig

T-Parity Violation by Anomalies

Little Higgs theories often rely on an internal parity ("T-parity'') to suppress non-standard electroweak effects or to provide a dark matter candidate. We show that such a symmetry is generally broken by anomalies, as described by the Wess-Zumino-Witten term. We study a simple SU(3) x SU(3)/SU(3) Little Higgs scheme where we obtain a minimal form for the topological interactions of a single Higgs field. The results apply to more general models, including [SU(3) x SU(3)/SU(3)]^4, SU(5)/SO(5), and SU(6)/Sp(6).Comment: 17 page

Development and stability of gyrotactic plumes in bioconvection

Using the continuum model of Pedley, Hill and Kessler (1988) for bioconvection in a suspension of swimming, gyrotactic micro-organisms, we investigate the existence and stability of a two-dimensional plume in tall, narrow chambers with stress-free sidewalls. The system is governed by the Navier–Stokes equations for an incompressible fluid coupled with a micro-organism conservation equation. These equations are solved numerically using a conservative finite-difference scheme. In sufficiently deep chambers, the plume is always unstable to both varicose and meandering modes. A linear stability analysis for an infinitely long plume predicts the growth rates of these instabilities, explains the mechanisms, and is in good agreement with the numerical results

Topological Physics of Little Higgs Bosons

Topological interactions will generally occur in composite Higgs or Little Higgs theories, extra-dimensional gauge theories in which A_5 plays the role of a Higgs boson, and amongst the pNGB's of technicolor. This phenomena arises from the chiral and anomaly structure of the underlying UV completion theory, and/or through chiral delocalization in higher dimensions. These effects are described by a full Wess-Zumino-Witten term involving gauge fields and pNGB's. We give a general discussion of these interactions, some of which may have novel signatures at future colliders, such as the LHC and ILC.Comment: 22 page

The analytical representation of viscoelastic material properties using optimization techniques

This report presents a technique to model viscoelastic material properties with a function of the form of the Prony series. Generally, the method employed to determine the function constants requires assuming values for the exponential constants of the function and then resolving the remaining constants through linear least-squares techniques. The technique presented here allows all the constants to be analytically determined through optimization techniques. This technique is employed in a computer program named PRONY and makes use of commercially available optimization tool developed by VMA Engineering, Inc. The PRONY program was utilized to compare the technique against previously determined models for solid rocket motor TP-H1148 propellant and V747-75 Viton fluoroelastomer. In both cases, the optimization technique generated functions that modeled the test data with at least an order of magnitude better correlation. This technique has demonstrated the capability to use small or large data sets and to use data sets that have uniformly or nonuniformly spaced data pairs. The reduction of experimental data to accurate mathematical models is a vital part of most scientific and engineering research. This technique of regression through optimization can be applied to other mathematical models that are difficult to fit to experimental data through traditional regression techniques

Anomalies, Chern-Simons Terms and Chiral Delocalization in Extra Dimensions

Gauge invariant topological interactions, such as the D=5 Chern-Simons terms, are required in models in extra dimensions that split anomaly free representations. The Chern-Simons term is necessary to maintain the overall anomaly cancellations of the theory, but it can have significant, observable, physical effects. The CS-term locks the KK-mode parity to the parity of space-time, leaving a single parity symmetry. It leads to new processes amongst KK-modes, eg, the decay of a KK-mode to a 2-body final state of KK-modes. A formalism for the effective interaction amongst KK-modes is constructed, and the decay of a KK-mode to KK-mode plus zero mode is analyzed as an example. We elaborate the general KK-mode current and anomaly structure of these theories. This includes a detailed study of the triangle diagrams and the associated ``consistent anomalies'' for Weyl spinors on the boundary branes. We also develop the non-abelian formalism. We illustrate this by showing in a simple way how a D=5 Yang-Mills ``quark flavor'' symmetry leads to the D=4 chiral lagrangian of mesons and the quantized Wess-Zumino-Witten term.Comment: 51 pages, 3 figures; Corrected typos, amplified discussio

L-band, 1.2 m parabolic antenna-noise temperature measurement

Extensive antenna-noise temperature measurements at 1.6 GHz (L-band) were made using a 1.2 m (4 ft. diameter) parabolic dish antenna mounted on the flying bridge of a modern 15,690-ton, commercial-container ship. Both in-harbor and at-sea radiometer measurements were made that indicated a steady background, antenna-noise temperature value slightly less than 70 degrees Kelvin (K) at elevation angles of 5 percent, and greater, at 1.6 GHz. A comparison of theoretical and measured values indicate excellent agreement within about 5K for at-sea data. These measurements are helpful to RF equipment designers of maritime, L-band shipboard terminals for operation with the two, geostationary, maritime satellites, Marisat-A and -B

Can my mechanic fix blue cars? A discussion of health clinician\u27s interactions with Aboriginal Australian clients

We expect our professional mechanics to ‘diagnose’ and \u27treat\u27 our cars irrespective of colour, but are we expecting less from our health professionals? There is an increasing focus in the literature on health practitioner decision-making and its influence on the nature and quality of health care. In this article we explore how the basic diagnostic and therapeutic skills that health care practitioners have should be utilised equitably for all clients and propose ways this might be realised. Could the development of Indigenous specific curricula be teaching our medical students to think that Aboriginal patients are different from the norm? We conclude that despite the gains in introducing more comprehensive Aboriginal health curricula there remains considerable work to be done before we can be confident that we are ensuring that health practitioners are no longer contributing to health disparities

Managing healthcare workflows in a multi-agent system environment

Whilst Multi-Agent System (MAS) architectures appear to offer a more flexible model for designers and developers of complex, collaborative information systems, implementing real-world business processes that can be delegated to autonomous agents is still a relatively difficult task. Although a range of agent tools and toolkits exist, there still remains the need to move the creation of models nearer to code generation, in order that the development path be more rigorous and repeatable. In particular, it is essential that complex organisational process workflows are captured and expressed in a way that MAS can successfully interpret. Using a complex social care system as an exemplar, we describe a technique whereby a business process is captured, expressed, verified and specified in a suitable format for a healthcare MAS.</p

Evaluation of a high temperature adhesive for fabricating graphite/PMR-15 polyimide structures

Tests are conducted to measure shear strength, shear modulus and flatwise tensile strength of the A7F (amide-imide modified LARC-13) adhesive system. An investigation is also conducted to determine the effect of geometric material parameters, and elevated temperature on the static strength of standard joints. Single-lap and double-lap composite joints, and single, double and step lap composite to metal joints are characterized. A series of advanced joints consisting of preformed adherends, adherends with scalloped edges and joints with hybrid interface plies are tested and compared to baseline single and double-lap designs