September 2, 1997

Janus, giant new supercomputer at Sandia National Laboratories in New Mexico, is giving scientists the power to perform a once-inconceivable trillion mathematical operations per second; immense power of 9,072 Pentium Pro processors, set up by Intel Corp, enables scientists to see what would happen if comet such as Shoemaker-Levy hit ocean on earth; simulation sequence illustrated; photo of early Eniac machine, which could do 7,500 calculations per second; Janus is so fast and has so much memory, hundreds of billions of bytes, that it can simulate complex events such as explosions, nuclear fusion reactions and missile impacts in unprecedented detail; new teraflop machine was ordered for Energy Department's Acelerated Strategic Computing Initiative, which uses simulations to test nuclear weapons without actual explosions; one side of Janus is used for such classified work, while the other solves unclassified scientific problems; physicist Dr Mark Boslough describes recent simulation of nuclear fusion (M)

Congress returns from summer recess basking in historic balanced-budget and tax-cutting agreement with Pres Clinton, and seems ready to confront mechanics that are needed to make agreement work; even though there is little talk of kind of warfare that shut down Government in 1995, major battles loom over several prickly issues (M)

New York City's child welfare system will receive additional $22.7 million in combined city, state and Federal aid this year to ease shortage of beds in foster care that had forced more than 1,000 children to sleep on office floors since January; money will restore dollars lost three years ago when state budget cuts resulted in elimination of about 400 beds in group homes (M)

Attention Deficit Disorder, once diagnosed primarily in school-age children, is being diagnosed in record number of adults; several recent studies estimate between 6 million and 9.5 million Americans suffer from disorder, making it as common as severe clinical depression or drug abuse; after spotting it in generations of children, psychiatrists have only recently accepted that illness carries over into adulthood; at current pace, adults will receive 729,000 prescriptions in 1997 for Ritalin, mild stimulant used to treat disorder, compared with 217,000 in 1992; critics say illness is being overdiagnosed, and many question whether it really exists; of particular concern is growing use of Ritalin as recreational stimulant by college students and fast-track professionals; photos; graphs (M)

Deadly maelstrom off Norwegian coast, which has terrified sailors for centuries and inspired dramatic literary descriptions, has been precisely explained and charted by Dr Bjorn Gjevik and two of his mathematics students at University of Oslo; report in journal Nature says that, although there is no funnel-like whirlpool within maelstrom as imagined by writers, dangers of currents and winds between Ferroe and Loffoden islands are formidable, causing big vessels to skirt area even today; 17th-century illustration; map; Gjevik says strong currents and waves in opposite directions create steep, choppy and breaking waves (M)