The Mountain Pass Rare-Earth Deposits

Rare-earth minerals were discovered near Mountain Pass in northeastern San Bernardino County, Calif., in April 1949, and in the following year the Sulphide Queen carbonate body was found. This body is the world's greatest known concentration of rare-earth metals with a tonnage larger than the total of all rare earths used in the world prior to 1950. The rare earths in the Mountain Pass district are chiefly cerium, lanthanum, and neodymium. These elements occur principally in bastnaesite, a rare-earth fluocarbonate, heretofore reported from only about 10 localities in the world. The bastnaesite was discovered in samples from Mountain Pass obtained by H. E. Woodward and Clarence Watkins of Goodsprings, Nev., and its identity was established in laboratory studies by E . T. Schenk of the U. S. Bureau of Mines and D. F. Hewett of the U. S. Geological Survey. Subsequent prospecting by individuals and geologic investigations by the U. S. Geological Survey resulted in the discovery of bastnaesite in the Sulphide Queen carbonate body and numerous other deposits in a belt 6 miles long. Investigations by the U. S. Geological Survey since 1949 (Olson et al., in preparation) include detailed mapping of the site of the initial discovery-the Birthday claims-by L. C. Pray and W. N. Sharp; geologic mapping of the district by J. C. Olson; detailed mapping of the Sulphide Queen carbonate body and several smaller deposits by D. R. Shawe and W. N. Sharp; and laboratory mineralogic investigations by H. W. Jaffe

Jamming in Granular Polymers

We examine the jamming transition in a two-dimensional granular polymer system using compressional simulations. The jamming density \phi_c decreases with increasing length of the granular chain due to the formation of loop structures, in excellent agreement with recent experiments. The jamming density can be further reduced in mixtures of granular chains and granular rings, also as observed in experiment. We show that the nature of the jamming in granular polymer systems has pronounced differences from the jamming behavior observed for polydisperse two-dimensional disk systems at Point J. This result provides further evidence that there is more than one type of jamming transition.Comment: 5 pages, 7 postscript figures, version to appear in PR

Health Care for Modern Families: Practical suggestions concerning care for families of gay men and lesbians

This article offers a first person perspective concerning how health care providers can better recognize modern families and improve health care for them, especially families founded by gay men and lesbians in U.S. culture. It interweaves information concerning the historical, legal, and economic situation impinging on gay men and lesbians while offering personal stories in dealing with health care professionals. The article references germane scholarly literature for further reading throughout

Restoration of multichannel microwave radiometric images

A constrained iterative image restoration method is applied to multichannel diffraction-limited imagery. This method is based on the Gerchberg-Papoulis algorithm utilizing incomplete information and partial constraints. The procedure is described using the orthogonal projection operators which project onto two prescribed subspaces iteratively. Some of its properties and limitations are also presented. The selection of appropriate constraints was emphasized in a practical application. Multichannel microwave images, each having different spatial resolution, were restored to a common highest resolution to demonstrate the effectiveness of the method. Both noise-free and noisy images were used in this investigation

Leading-edge slat optimization for maximum airfoil lift

A numerical procedure for determining the position (horizontal location, vertical location, and deflection) of a leading edge slat that maximizes the lift of multielement airfoils is presented. The structure of the flow field is calculated by iteratively coupling potential flow and boundary layer analysis. This aerodynamic calculation is combined with a constrained function minimization analysis to determine the position of a leading edge slat so that the suction peak on the nose of the main airfoil is minized. The slat position is constrained by the numerical procedure to ensure an attached boundary layer on the upper surface of the slat and to ensure negligible interaction between the slat wake and the boundary layer on the upper surface of the main airfoil. The highest angle attack at which this optimized slat position can maintain attached flow on the main airfoil defines the optimum slat position for maximum lift. The design method is demonstrated for an airfoil equipped with a leading-edge slat and a trailing edge, single-slotted flap. The theoretical results are compared with experimental data, obtained in the Ames 40 by 80 Foot Wind Tunnel, to verify experimentally the predicted slat position for maximum lift. The experimentally optimized slat position is in good agreement with the theoretical prediction, indicating that the theoretical procedure is a feasible design method

Hysteresis and Noise in Stripe and Clump Forming Systems

We use simulations to examine hysteresis and noise in a model system that produces heterogeneous orderings including stripe and clump phases. In the presence of a disordered substrate, these heterogeneous phases exhibit 1/f$^\alpha$ noise and hysteresis in transport. The noise fluctuations are maximal in the heterogeneous phases, while in the uniform phases the hysteresis vanishes and both $\alpha$ and the noise power decrease. We compare our results to recent experiments exhibiting noise and hysteresis in high-temperature superconductors where charge heterogeneities may occur.Comment: 4 pages, 5 postscript figure

Electromagnetic plasma wave propagation along a magnetic field

The linearized response of a Vlasov plasma to the steady-state excitation of transverse plasma waves along an external magnetic field is examined. Assuming a delta-function excitation mechanism, and performing a detailed Vlasov-Maxwell equation analysis using Fourier-Laplace transforms, the plasma response is found to consist of three terms: a branch-cut term, a free-streaming term, and a dielectric-pole term. Also considered is the phenomenon of plasma wave echoes. The case of longitudinal electrostatic waves is extended to the case of transverse plasma waves that propagate along an external magnetic field. It is shown that a transverse echo results in lowest order only when one excitation is transverse and the other is longitudinal