A transmission/reflection material characterization technique that uses dual-ridged waveguides is presented. The proposed dual-ridged-waveguide system combines many of the positive aspects of traditional transverse electromagnetic-mode (e.g., coaxial, free space, and stripline) and rectangular waveguide systems, i.e., broadband measurements and accurate calibration. A brief discussion on the derivation of the theoretical scattering parameters, required for the extraction of permittivity and permeability of a material under test, is provided. Two methods for computing the cutoff wavenumber of the dual-ridged waveguide-essential to the material characterization processare also discussed. The first, which utilizes the mode-matching technique, is applicable to dual-ridged-waveguide apertures composed of right-angled corners. The second uses the surface equivalence principle and a magnetic-field integral equation formulation to find the cutoff wavenumber. This approach is applicable to dual-ridged waveguides with rounded corners, which often result from the dual-ridged waveguide manufacturing process. Thus, for the first time, the effect of rounded dual-ridged-waveguide aperture corners on the measurement of permittivity and permeability is assessed. Experimental material characterization results of a magnetic absorbing material are presented and analyzed to validate the proposed technique. An extensive error analysis on the extracted values of permittivity and permeability is also performed by taking into account manufacturer-specified dual-ridged-waveguide design tolerances as well as uncertainties in sample position, sample thickness, sample-holder length, and measured scattering parameters.

Efforts to reverse the obesity epidemic require policy, systems, and environmental (PSE) change strategies. Despite the availability of evidence-based and other promising PSE interventions, limited evidence exists on the "how-to" of transitioning them into practice. For the past 13 years, the Los Angeles County Department of Public Health has been building capacity among community residents and other stakeholders to create effective community coalitions and to implement well-designed policy strategy campaigns using an evidence-based approach to policy change, the policy adoption model (PAM). Implementing a phase-based approach to policy change, the PAM was initially used to support the passage of over 140 tobacco control and prevention policies in Los Angeles County. Following these successes, Los Angeles County Department of Public Health applied the PAM to obesity prevention, operationalizing the policy process by training community residents and other stakeholders on the use of the model. The PAM has shown to be helpful in promoting PSE change in tobacco control and obesity prevention, suggesting a local-level model potentially applicable to other fields of public health seeking sustainable, community-driven policy change.

Alumina nanopore structures find applications in magnetic sensors, optical filters, and various biological devices. In this work, we 1 present a ray-optics model for the optical filter. We present a detailed simulation and a simplified analytical expression for the; reflectance as a function of the alumina parameters such as pore diameter, pore density, alumina thickness, and a function of the ' wavelength and angle of incidence of the illuminating plane electromagnetic wave. The reflectance vs wavelength in the range of.: 400-800 nm obtained from the simulation and the analytical expression are compared with that of the experiments for thin and thick alumina. All results agree well for a thin layer of alumina pores (90 nm). When comparing experimental and theoretical results for a thick layer of alumina ( 1300 nm), the results disagree. One possible explanation for the discrepancy is that the dielectric constant may vary with the thickness of the anodized alumina. Based on this work, a ray optic mixing theory is presented for waves propagating obliquely to parallel slabs of dielectric mediums with a degree of spatial periodicity.Physical and chemical properties of nanoscale materials depend on the geometrical shape and size.

Electron stimulated electron desorption yielding secondary electron emission is to be examined both experimentally and computationally. A novel secondary electron emission test stand at UNLV housing a particle position detector maps the evolution of the spatial distribution of electron beam stimulated secondary electrons emitted from a metal target. Electrons emitted from the target in the drift free region with initial momentum within an approximate 3 o <θ<40 o conical angle of acceptance relative to the primary beam axis are collected and recorded. This allows for transient surface conditioning and degrading studies on a single pulse basis and a multi-pulse basis over time. In this preliminary study, an approximate analysis of the secondary electron emission test stand is provided with special considerations given to the detector assembly (e.g., grid, micro-channel plate, and particle position detector) and data acquisition electronics. Spatial distribution tendencies and total secondary electron emission counts are provided for a single target under test. The MAGIC modeling tool is employed to study the secondary electron emission process. Comparisons will be made with experiment.

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