24,407 research outputs found
Optical bistability for two-level atoms in a standing-wave cavity
Observations of optical bistability are reported for a system composed of multiple atomic beams passing through a high-finesse optical cavity. Both the transmitted power and the intracavity fluorescent intensity have been recorded as functions of incident laser power for zero cavity and atomic detunings. A quantitative study has been made of the evolution of the steady-state switching intensities from well below the critical onset of bistability to well above this point. The results show reasonable agreement with a Gaussian-beam theory of optical bistability, but systematic departures are noted
Data conditioning and display for Apollo prelaunch checkout - Test matrix technique
Test matrix technique for checkout and launching of Apollo-Saturn spacecraf
Commensurability oscillations due to pinned and drifting orbits in a two-dimensional lateral surface superlattice
We have simulated conduction in a two-dimensional electron gas subject to a
weak two-dimensional periodic potential, . The usual commensurability oscillations in are seen with
alone. An increase of suppresses these oscillations, rather than
introducing the additional oscillations in expected from
previous perturbation theories. We show that this behavior arises from drift of
the guiding center of cyclotron motion along contours of an effective
potential. Periodic modulation in the magnetic field can be treated in the same
way.Comment: 3 pages text, 4 eps figures, revte
Lunar sample analysis
The surface composition of two samples from the highly shocked, glass-coated lunar basalt (12054) and from four glass-coated fragments from the 1-2 mm (14161) fines were examined by X-ray photoemission spectroscopy to determine whether the agglutination process itself is responsible for the difference between their surface and bulk compositions. Auger electron spectroscopy of glass balls from the 15425 and 74001 fines were analyzed to understand the nature, extent, and behavior of volatile phases associated with lunar volcanism. Initial results indicate that (1) volatiles, in the outer few atomic layers sampled, vary considerably from ball to ball; (2) variability over the surface of individual balls is smaller; (3) the dominant volatiles on the balls are S and Zn; and (4) other volatiles commonly observed are P, Cl, and K
Family friendly? The impact on children of the family migration rules: a review of the financial requirements
This report, published by the Children's Commissioner, explores the impact on children of the financial requirements of the Immigration Rules (the ‘Rules’), in particular, the minimum income threshold of £18,600 per annum which came into force on 9th July 2012. The Rules govern the admission of spouses and partners from outside the European Economic Area
Concentration and state of cerium in coastal waters
The cerium contents of several coastal water samples were found to be 0.1 to 0.6 µg/l. These are in contrast to the cerium concentrations of 0.004 and 0.014 µg/l observed in samples taken near Bermuda…
Significance of solutions of the inverse Biot-Savart problem in thick superconductors
The evaluation of current distributions in thick superconductors from field
profiles near the sample surface is investigated theoretically. A simple model
of a cylindrical sample, in which only circular currents are flowing, reduces
the inversion to a linear least squares problem, which is analyzed by singular
value decomposition. Without additional assumptions about the current
distribution (e.g. constant current over the sample thickness), the condition
of the problem is very bad, leading to unrealistic results. However, any
additional assumption strongly influences the solution and thus renders the
solutions again questionable. These difficulties are unfortunately inherent to
the inverse Biot-Savart problem in thick superconductors and cannot be avoided
by any models or algorithms
Distances to the high galactic latitude molecular clouds G192-67 and MBM 23-24
We report on distance determinations for two high Galactic latitude cloud
complexes, G192-67 and MBM 23-24. No distance determination exists in the
literature for either cloud. Thirty-four early type stars were observed towards
the two clouds, more than half of which have parallaxes measured by the
Hipparcos satellite. For the remaining stars we have made spectroscopic
distance estimates. The data consist of high resolution echelle spectra
centered on the Na I D lines, and were obtained over six nights at the Coude
Feed telescope at Kitt Peak National Observatory. Interstellar absorption lines
were detected towards some of the stars, enabling estimates of the distances to
the clouds of 109 +/- 14 pc for G192-67, and of 139 +/- 33 pc for MBM 23-24. We
discuss the relationship of these clouds to other ISM features such as the
Local Hot Bubble and the local cavity in neutral hydrogen.Comment: 15 pages, 6 embedded figures, to be published in the ApJ Vol. 516,
No.
Relativistic J-matrix method
The relativistic version of the J-matrix method for a scattering problem on
the potential vanishing faster than the Coulomb one is formulated. As in the
non-relativistic case it leads to a finite algebraic eigenvalue problem. The
derived expression for the tangent of phase shift is simply related to the
non-relativistic case formula and gives the latter as a limit case. It is due
to the fact that the used basis set satisfies the ``kinetic balance
condition''.Comment: 21 pages, RevTeX, accepted for publication in Phys. Rev.
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