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The effect of dynamic loading on the stress-strain and failure characteristics of nugget sandstone was investigated at strain rates from 102 to 103 per second and confining pressures to 30 ksi. The apparatus developed for these experiments consists of a conventional split Hopkinson bar enclosed in a pressure vessel. The apparatus permitted determination and recording of all principal stresses and strains from the onset of loading to failure. A description of the experimental techniques used in obtaining data including the method of determining stress and strain, the method of reducing data, and use of various shaped projectiles to tailor the input-stress wave are reported together with experimental results for nugget sandstone. All rocks tested exhibited an increase in strength as the loading rate increased. The dynamic stress-strain curves were similar in shape to curves from quasi-static testing of the same material.

In bacterial conjugation in the Escherichia coli system, two cells with heterosexual properties, donor and receptor cells, form a temporary pair and DNA is transferred up to the amount of a whole bacterial chromosome which would represent, if stretched out, a 1 mm long molecule. The physical mode of DNA transfer between two cells which have tight cell walls and cytoplasmic membranes is far from clear.

A study of the diurnal migration and geographic extent of the deep layers of sound scatterers found in the ocean has been made with fathograms and oscillographic records of reverberation received with vertically directed projectors. The deep scattering layer was observed consistently throughout the area investigated. The principal features of the diurnal observations are the movement of the deep scattering layer toward the surface in the evening and away from the surface in the morning. Observations of the diurnal migration of plankton made during the acoustic observations indicates that the cause of the sound scattering is associated with organisms. Some observations indicate that the scatterers near the surface are found in “swarms” rather than in well‐defined strata. With conditions of strong downward refraction, the layer acts somewhat like a false bottom, giving rise to a pronounced increase of horizontal reverberation strength which is not observed in the absence of strong downward refraction. Forward scattering from the deep layer is observed in transmission measurements as a ragged “pip” following the signal.