A recurrent nova super-remnant in the Andromeda galaxy.

The accretion of hydrogen onto a white dwarf star ignites a classical nova eruption-a thermonuclear runaway in the accumulated envelope of gas, leading to luminosities up to a million times that of the Sun and a high-velocity mass ejection that produces a remnant shell (mainly consisting of insterstellar medium). Close to the upper mass limit of a white dwarf (1.4 solar masses), rapid accretion of hydrogen (about 10 solar masses per year) from a stellar companion leads to frequent eruptions on timescales of years to decades.

Safety of chronic exercise in a rat model of kidney disease.

Purpose: The objective of this study was to determine the effect of treadmill running on polycystic kidney disease (PKD) progression and bone mineral density in Han:SPRD-cy rats, an animal model of PKD.

Methods: Using a 2 x 2 design, normal and polycystic male rats were divided randomly into exercise and sedentary groups at 4 wk of age. The exercising group performed treadmill exercise (14 m x min(-1)) for 30 min 3 d x wk(-1) for 6 wk, whereas the control group remained sedentary.