We have examined whether the development of embryonic muscle fiber type is regulated by competing influences between Hedgehog and TGF-beta signals, as previously shown for development of neuronal cell identity in the neural tube. We found that ectopic expression of Hedgehogs or inhibition of protein kinase A in zebrafish embryos induces slow muscle precursors throughout the somite but muscle pi...

The Pioneer 10 and 11 spacecraft yielded very accurate navigation in deep space that was, however, limited by a small, anomalous frequency drift of their carrier signals received by the radio-tracking stations of the NASA Deep Space Network (DSN). This drift signifies a discrepancy between the frequency of the Doppler signals observed by the DSN and that frequency modeled using modern-day deep ...

Tho flare associated interplanetary (IP) shock of February 15-16, 1967 observed by Explorer 33 and Pioneer 7 is analyzed to yield an estimntion of the ecliptic plane geometry of the shock surface near 1 AU. These spacocraft were separated by 23° in heliocentric longitude and Pioneer 7 was at a distance of 1.12 AU from the sun. There was an 18.9 hour delay between the two observations. The estim...