Payments fraud : consumer considerations

This article examines the potential for fraud associated with various "traditional" payment methods and the protective measures that consumers should take when using them.Payment systems ; Checks ; Credit cards

Frequency comb based four-wave-mixing spectroscopy

We experimentally demonstrate four-wave-mixing spectroscopy using frequency combs. The experiment uses a geometry where excitation pulses and four-wave-mixing signals generated by a sample co-propagate. We separate them in the radio frequency domain by heterodyne detection with a local oscillator comb that has a different repetition frequency

Two-dimensional Fourier-transform Spectroscopy of Potassium Vapor

Optical two-dimensional Fourier-transformed (2DFT) spectroscopy is used to study the coherent optical response of potassium vapor in a thin transmission cell. Rephasing and non-rephasing spectra of the D1 and D2 transitions are obtained and compared to numerical simulations. Calculations using the optical Bloch equations gives very good agreement with the experimental peak strengths and line shapes. Non-radiative Raman-like coherences are isolated using a different 2DFT projection. Density-dependent measurements show distortion of 2DFT spectra due to pulse propagation effects

Reynolds number effects on the transonic aerodynamics of a slender wing-body configuration

Aerodynamic forces and moments for a slender wing-body configuration are summarized from an investigation in the Langley National Transonic Facility (NTF). The results include both longitudinal and lateral-directional aerodynamic properties as well as slideslip derivatives. Results were selected to emphasize Reynolds number effects at a transonic speed although some lower speed results are also presented for context. The data indicate nominal Reynolds number effects on the longitudinal aerodynamic coefficients and more pronounced effects for the lateral-directional aerodynamic coefficients. The Reynolds number sensitivities for the lateral-directional coefficients were limited to high angles of attack