Measurements of the single and the ratio of double to single ionization cross sections for positron impact on neon, krypton and xenon are presented from near threshold to 1000 eV. By multiplying the values of each target by the appropriate , new data for the corresponding double ionization cross sections have also been obtained. The ratio between positron and electron maxima is generally seen to be lower for higher target atomic number, as expected from the static interaction between the projectile and undistorted target. Comparison with available data suggests that Ps formation accompanied by the production of singly or doubly charged ions is a significant channel in positron - atom scattering.

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We present the complete nucleotide sequences of two leghemoglobin genes isolated from soybean DNA. Both genes contain three intervening sequences which interrupt the two coding sequences in identical positions. The 5' and 3' flanking sequences in both genes contain conserved sequences similar to those found in corresponding positions in other eukaryotic genes. Thus, the general DNA sequence organization of these plant genes is similar to that of other eukaryotic genes.

Measurements of antiproton stopping powers around the stopping-power maximum are presented for targets of Al, Si, Ti, Cu, Ag, Ta, Pt, and Au. The Low Energy Antiproton Ring antiproton beam of 5.9 MeV is degraded to 50-700 keV, and the energy loss is found by measuring the antiproton velocity before and after the target. Target thicknesses have been determined accurately by weighing and Rutherford backscattering techniques. The antiproton stopping powers are found to be reduced by around 35% for both light and heavy elements near the electronic stopping-power maximum as compared to the equivalent proton stopping power. The antiproton stopping powers and the Barkas effect; that is, the difference in stopping power between protons and antiprotons is compared to theoretical estimates, based on a harmonic-oscillator model and an electron-gas model, and good agreement is obtained.

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