206 research outputs found
Velocity-selective sublevel resonance of atoms with an array of current-carrying wires
Resonance transitions between the Zeeman sublevels of optically-polarized Rb
atoms traveling through a spatially periodic magnetic field are investigated in
a radio-frequency (rf) range of sub-MHz. The atomic motion induces the
resonance when the Zeeman splitting is equal to the frequency at which the
moving atoms feel the magnetic field oscillating. Additional temporal
oscillation of the spatially periodic field splits a motion-induced resonance
peak into two by an amount of this oscillation frequency. At higher oscillation
frequencies, it is more suitable to consider that the resonance is mainly
driven by the temporal field oscillation, with its velocity-dependence or
Doppler shift caused by the atomic motion through the periodic field. A
theoretical description of motion-induced resonance is also given, with
emphasis on the translational energy change associated with the internal
transition.Comment: 7 pages, 3 figures, final versio
Estimating Promotional Effects with Retailer-Level Scanner Data*
Abstract Demand models produce biased results when applied to data aggregated across stores with heterogeneous promotional activity. We show how to modify extant aggregate demand frameworks to avoid this problem. First a consumer-level model is developed, which is then integrated over the heterogeneous stores to arrive at aggregate demand. Our approach is highly practical since it requires only standard scanner data of the type produced by the major vendors. Using data for super-premium ice cream, we apply the proposed methodology to the random coefficients logit demand framework
NMR hyperpolarization techniques of gases
Nuclear spin polarization can be significantly increased through the process of hyperpolarization, leading to an increase in the sensitivity of nuclear magnetic resonance (NMR) experiments by 4–8 orders of magnitude. Hyperpolarized gases, unlike liquids and solids, can often be readily separated and purified from the compounds used to mediate the hyperpolarization processes. These pure hyperpolarized gases enabled many novel MRI applications including the visualization of void spaces, imaging of lung function, and remote detection. Additionally, hyperpolarized gases can be dissolved in liquids and can be used as sensitive molecular probes and reporters. This Minireview covers the fundamentals of the preparation of hyperpolarized gases and focuses on selected applications of interest to biomedicine and materials science
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ISOTOPE-SHIFT ZEEMAN EFFECT FOR TRACE-ELEMENT DETECTION: AN APPLICATION OF ATOMIC PHYSICS TO ENVIRONMENTAL PROBLEMS
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