Approximate relations and charts for low-speed stability derivatives of swept wings

Contains derivations, based on a simplified theory, of approximate relations for low-speed stability derivatives of swept wings. Method accounts for the effects and, in most cases, taper ratio. Charts, based on the derived relations, are presented for the stability derivatives of untapered swept wings. Calculated values of the derivatives are compared with experimental results

The Refractive Index of Silicon at Gamma Ray Energies

The index of refraction n(E_{\gamma})=1+\delta(E_{\gamma})+i\beta(E_{\gamma}) is split into a real part \delta and an absorptive part \beta. The absorptive part has the three well-known contributions to the cross section \sigma_{abs}: the photo effect, the Compton effect and the pair creation, but there is also the inelastic Delbr\"uck scattering. Second-order elastic scattering cross sections \sigma_{sca} with Rayleigh scattering (virtual photo effect), virtual Compton effect and Delbr\"uck scattering (virtual pair creation) can be calculated by integrals of the Kramers-Kronig dispersion relations from the cross section \sigma_{abs}. The real elastic scattering amplitudes are proportional to the refractive indices \delta_{photo}, \delta_{Compton} and \delta_{pair}. While for X-rays the negative \delta_{photo} dominates, we show for the first time experimentally and theoretically that the positive \delta_{pair} dominates for \gamma rays, opening a new era of \gamma optics applications, i.e. of nuclear photonics.Comment: 4 pages, 3 figure

Measuring Heterogeneous Preferences for Residential Amenities

This study reports on estimates of heterogeneous preferences for residential amenities among households in the Mountain West region of the US. The estimates are derived from a choice experiment funded by the Utah Department of Transportation and Utah Transit Authority—an experiment based upon large samples of both homeowners and renters who participated in a larger, statewide transportation study. The choice experiment and transportation study allow us to control for a rich set of household-level demographic and lifestyle characteristics, which in turn permits identification of a host of factors contributing to heterogeneity in residential preferences. We leverage a percentage-change housing cost attribute included in the experiment to obtain measures of marginal willingness to pay (MWTP) for the various residential attributes and attribute levels in our study. Our method of converting the percentage-change cost attributed to dollar-denominated MWTP results in theoretically plausible estimates of a household\u27s MWTP. We find that preferences for residential amenities differ across homeowners and renters with respect to intensity rather than direction—homeowners are generally willing to pay more for these amenities, in some cases up to seven times more. Our quantitative estimates of these preferences and the extent to which we control for heterogeneity across households provide urban and regional planners with precise monetary welfare measures for a sizable majority of the region\u27s residents

Туризм и внешняя торговля АР Крым: географические аспекты современного развития

Целью данной статьи является оценка современного состояния внешней торговли АР Крым и ее составляющей – туристской деятельности