Infertility in a ram associated with a knobbed acrosome abnormality of the spermatozoa

A yearling Rambouillet ram with an asymmetrical scrotum was examined for potential breeding soundness prior to use in a synchronized mating program in a purebred flock of 20 ewes. Initial sperm cell evaluation revealed 78% knobbed acrosomes associated with few other abnormalities of the head and midpiece. Use of the ram resulted in no conception in one group of ten synchronized ewes. One month later, the proportion of sperm cells with knobbed acrosomes was 80%.     

Strain accumulation in the shumagin and yakataga seismic gaps, alaska

Strain accumulation during the 1980-85 interval has been measured by means of trilateration surveys in the Shumagin and Yakataga seismic gaps, which are the two regions identified as the most likely sites for the next great thrust earthquakes along the Alaska-Aleutian arc. No significant strain accumulation was detected in the Shumagin gap, but experience at similar subduction zones and simple models of the subduction process suggest that a measurable amount of strain should have accumulated. The most likely explanation of the observation is that subduction there is either aseismic or episodic. The strain accumulation measured in the Yakataga gap is consistent with that expected for the plate convergence rate, although the direction of maximum compression may suggest a somewhat more oblique convergence than expected.     

Strain on the san andreas fault near palmdale, california: rapid, aseismic change

Frequently repeated strain measurements near Palmdale, California, during the period from 1971 through 1980 indicate that, in addition to a uniform accumulation of right-lateral shear strain (engineering shear, 0.35 microradian per year) across the San Andreas fault, a 1-microstrain contraction perpendicular to the fault that accumulated gradually during the interval 1974 through 1978 was aseismically released between February and November 1979. Subsequently (November 1979 to March 1980), about half of the contraction was recovered. This sequence of strain changes can be explained in terms of south-southwestward migration of a slip event consisting of the south-southwestward movement of the upper crust on a horizontal detachment surface at a depth of 10 to 30 kilometers. The large strain change in 1979 corresponds to the passage of the slip event beneath the San Andreas fault.     

Auroral photography from a satellite

Photographs taken from satellites show the form, location, and intensity of the aurora from a new perspective. They provide an effective way of monitoring auroral activity on a worldwide basis and are likely to become one of the major tools in the effort to understand this phenomenon.     

Seismic anisotropy beneath Ruapehu volcano: a possible eruption forecasting tool

The orientation of crustal seismic anisotropy changed at least twice by up to 80 degrees because of volcanic eruptions at Ruapehu Volcano, New Zealand. These changes provide the basis for a new monitoring technique and possibly for future midterm eruption forecasting at volcanoes. The fast anisotropic direction was measured during three seismometer deployments in 1994, 1998, and 2002, providing an in situ measurement of the stress in the crust under the volcano. The stress direction changed because of an eruption in 1995-1996. Our 2002 measurements revealed a partial return to the pre-eruption stress state. These changes were probably caused by repeated filling and depressurizing of a magmatic dike system.