Overlay board for control consoles

Board that fits over the control panel decreases errors and time loss. Device has cutouts for controls and indicators, bears all appropriate labeling information, can be removed with the changing computer assignments, and guards against accidental changes in control settings

Fingers of God

Very long wavelength universal gravitational waves cannot now produce in clusters of galaxies velocity dispersions greater than that which these systems would possess if they were expanding with the Universe, if the Universe is not younger than $10^{10}$ yr and Hubble's constant is not less than 50 km/sec/ Mpc. A diagram shows that actual velocity dispersions are significantly greater than this limit.Comment: Published long before the advent of large-scale redshift surveys, as "A Critique of Rees's Theory of Primordial Gravitational Radiation", this paper includes the first presentation of what has come to be known as the fingers-of-god effect. The effect is mentioned several hundred times in arXive papers, rarely with a wrong attribution, usually with none at al

Directional spectra of ocean waves from microwave backscatter: A physical optics solution with application to the short-pulse and two-frequency measurement techniques

Two simple microwave radar techniques that are potentially capable of providing routine satellite measurements of the directional spectrum of ocean waves were developed. One technique, the short pulse technique, makes use of very short pulses to resolve ocean surface wave contrast features in the range direction; the other technique, the two frequency correlation technique makes use of coherency in the transmitted waveform to detect the large ocean wave contrast modulation as a beat or mixing frequency in the power backscattered at two closely separated microwave frequencies. A frequency domain analysis of the short pulse and two frequency systems shows that the two measurement systems are essentially duals; they each operate on the generalized (three frequency) fourth-order statistical moment of the surface transfer function in different, but symmetrical ways, and they both measure the same directional contrast modulation spectrum. A three dimensional physical optics solution for the fourth-order moment was obtained for backscatter in the near vertical, specular regime, assuming Gaussian surface statistics

A high frequency correction to the Kirchhoff approximation, with application to rough surface EM wave scattering

A high frequency correction to the Kirchhoff approximation is developed for application to rough surface scattering. An approximate solution to the magnetic field integral equation for perfect conductivity and plane wave excitation yields a perturbed surface current expressed as a linear function of the second derivatives of surface height. The corrected surface current vector is substituted into the far field Stratton-Chu integral and average backscattered powers for the four polarization combinations are computed on the assumption that the surface is describable as a stationary Gaussian random process. The strength of this scattering solution is that it can account for height curvature correlation without requiring small height and slope

Can Higher-Achieving Peers Explain the Benefits to Attending Selective Schools?: Evidence from Trinidad and Tobago

Using exogenous secondary school assignments to remove self-selection bias to schools and peers within schools, I credibly estimate both (1) the effect of attending schools with higher-achieving peers, and (2) the direct effect of short-run peer quality improvements within schools, on the same population. While students at schools with higher-achieving peers have better academic achievement, within-school short-run increases in peer achievement improve outcomes only at high-achievement schools. Short-run (direct) peer quality accounts for only one tenth of school value-added on average, but at least one-third among the most selective schools. There are large and important differences by gender.