Valley Entrance Shut By American TroopsBy Ml RUN SPENCERGEN MacARTHUR'S HEADQUARTERS, Lcvt*. Philippines —(/P)—Mud-caked Yanks today slammed shut the southern door of strategic Leyte valley, a potential Japanese death trap, andtightened their stranglehold on Nil pone*c communications with adjacent islands.•V naval and air unit lieat off the Japanese licet threat, the entire American land front muted forward through mud and rain, beneath the cover of supporting air-crrft and growing artillery fire.The southernmost of three column'* driving into Leyte valley, where Japacnse defenders are being crowded, captured Ruiaucn, a key road juncture nine miles inland from Dulag. Armor-led infantrymen of the 24th corps broke into the toun. after taking nearby .San Pablo and its cluster of airfields.