U.S.-RUSSIA COLLABORATIONPrime Minister Viktor Chernomyrdin appears to have ended a pair of long-running battles that had imperiled major international projects in astrophysics and seismology. Last week, Chernomyrdin pledged that the Russian government would withdraw an earlier threat to sell 60 tons of gallium at the heart of a neutrino detector in southern Russia and signed a decree that will end customs snafus that have dogged a global seismic monitoring network.