Combined grazing incidence RBS and TEM analysis of luminescent nano-SiGe/SiO2 multilayers.

Multilayer structures with five periods of amorphous SiGe nanoparticles/SiO2 layers with different thickness were deposited by Low Pressure Chemical Vapor Deposition and annealed to crystallize the SiGe nanoparticles. The use of grazing incidence RBS was necessary to obtain sufficient depth resolution to separate the signals arising from the individual layers only a few nm thick. The average size and areal density of the embedded SiGe nanoparticles as well as the oxide interlayer thickness were determined from the RBS spectra. Details of eventual composition changes and diffusion processes caused by the annealing processes were also studied. Transmission Electron Microscopy was used to obtain complementary information on the structural parameters of the samples in order to check the information yielded by RBS. The study revealed that annealing at 900 °C for 60 s, enough to crystallize the SiGe nanoparticles, leaves the structure unaltered if the interlayer thickness is around 15 nm or higher

What's the Use? Welfare Estimates from Revealed Preference Models when Weak Complementarity Does Not Hold

In this paper we consider the theoretical and empirical ramifications of welfare measurement in revealed preference models when weak complementarity does not hold. In the context of a Kuhn-Tucker model of recreation demand we show that, while it is possible to estimate preferences that do not appear to exhibit weak complementarity, the calculation of welfare measurements from these models requires a cardinal interpretation of preferences that cannot be tested. Furthermore, we reiterate the under-appreciated fact that even traditional use value estimates require a cardinal restriction on preferences that, while often intuitive, also cannot be tested. We demonstrate empirically that the choice of restrictions can have significant ramifications, as use value estimates can vary widely based on the assumed preference structure.

Estimation and Welfare Calculations in a Generalized Corner Solution Model with an Application to Recreation Demand

The Kuhn-Tucker model of Wales and Woodland (1983) provides a utility theoretic framework for estimating preferences over commodities for which individuals choose not to consume one or more of the goods. Due to the complexity of the model, however, there have been few applications in the literature and little attention has been paid to the problems of welfare analysis within the Kuhn-Tucker framework. This paper provides an application of the model to the problem of recreation demand. In addition, we develop and apply a methodology for estimating compensating variation, relying on Monte Carlo integration to derive expected welfare changes.

Valuing Water Quality As a Functionof Water Quality Measures

This paper incorporates a rich set of physical water quality attributes, as well as site and household characteristics, into a model of recreational lake usage in Iowa. Our analysis shows individuals are responsive to physical water quality measures. Willingness-to-pay estimates are reported based on improvements in these measures.

Rossby waves in rapidly rotating Bose-Einstein condensates

We predict and describe a new collective mode in rotating Bose-Einstein condensates, which is very similar to the Rossby waves in geophysics. In the regime of fast rotation, the Coriolis force dominates the dynamics and acts as a restoring force for acoustic-drift waves along the condensate. We derive a nonlinear equation that includes the effects of both the zero-point pressure and the anharmonicity of the trap. It is shown that such waves have negative phase speed, propagating in the opposite sense of the rotation. We discuss different equilibrium configurations and compare with those resulting from the Thomas-Fermi approximation.Comment: 4 pages, 2 figures (submitted to PRL

Examining Seasonal Trends of the Martian Polar Warming with the NASA Ames Mars Global Climate Model

The presented work focuses on polar warming as a diagnostic of the mean circulation to increase our understanding of processes that control the mean meridional circulation and transport in the Mars middle atmosphere. The NASA Ames Mars Global Climate Model is utilized to isolate physical processes to determine their impact on polar warming and its seasonal trends

What\u27s the Use? Welfare Estimates from Revealed Preference Models When Weak Complementarity Does Not Hold

In this paper we consider the theoretical and empirical ramifications of welfare measurement in revealed preference models when weak complementarity does not hold. In the context of a Kuhn–Tucker model of recreation demand we show that, while it is possible to estimate preferences that do not appear to exhibit weak complementarity, the calculation of welfare measurements from these models requires a cardinal interpretation of preferences that cannot be tested. Furthermore, we reiterate the under-appreciated fact that even traditional use value estimates require a cardinal restriction on preferences that, while often intuitive, also cannot be tested. We demonstrate empirically that the choice of restrictions can have significant ramifications, as use value estimates can vary based on the assumed preference structure

Estimation and Welfare Calculation in a Generalized Corner Solution Model with an Application to Recreation Demand

The Kuhn-Tucker model of Wales and Woodland (1983) provides a utility theoretic framework for estimating preferences over commodities for which individuals choose not to consume one or more of the goods. Due to the complexity of the model, however, there have been few applications in the literature and little attention has been paid to the problems of welfare analysis within the Kuhn-Tucker framework. This paper provides an application of the model to the problem of recreation demand. In addition, we develop and apply a methodology for estimating compensating variation, relying on Monte Carlo integration to derive expected welfare changes