ISSN 0036-8075

29 April 1983

Volume 220, No. 4596_...

LETTERS Revitalizing EPA: R. E. Sievers; SETI Petition: C. Sagan; The Metric System:E. Leete; Folk Remedy: F. L. Quintana .................................. 462

EDITORIAL Glass Fiber Communication ................................................. 463

ARTICLES Design Automation for Integrated Circuits: S. B. Newell, A. J. de Geus,R. A. Rohrer ..........................................................

Selective Modification of Glutathione Metabolism: A. Meister...................

Mathematics and Science Learning: A New Conception: L. B. Resnick ..........

NEWS AND COMMENT

RESEARCH NEWS

BOOK REVIEWS

"Baby Doe" Regs Thrown Out by Court .....................................

Navy Secretary Torpedoes a Think Tank .....................................

Study of Big Science Groups Hits Raw Nerve.................................

Briefing: NRC Faults Utility, Delays Reactor Start-up; Ohio State'sTelescope Given Stay of Execution; Communications Satellite Rescuein Real Jeopardy; Weather Satellite Sale Gets a Hearing; NSFNominee Wins Committee Approval; Genentech Bows Out of NYU'sMalaria Project ........................................................

The Newly Improved MX Missile...........................................

Dietary Dogma Disproved ..................................................

The Two Sides of the Brain .................................................

Supersymmetry and Supergravity .........................................

465

472

477

479

481

482

484

486

487

488

491

Gametes and Spores, reviewed by S. A. Roe; Resource Competition andCommunity Structure, M. Westoby; Cell Interactions and Development,R. B. Marchase; Books Received ........................................ 494

REPORTS Death of a Hadal Deep-Sea Bacterium After Decompression: A. A. Yayanos andA. S. Dietz ............................................................ 497

Electron Microscope Tomography: Transcription in Three Dimensions:D. E. Olins et al. ...................................................... 498

Modes of Larval Development and Rates of Speciation in Early TertiaryNeogastropods: T. A. Hansen ........................................... 501

Liposomal Blockade of the Reticuloendothelial System: Improved Tumor Imagingwith Small Unilamellar Vesicles: R. T. Proffitt et al. ...... ................ 502

Hemagglutinin Variants of Reovirus Type 3 Have Altered Central Nervous SystemTropism: D. R. Spriggs, R. T. Bronson, B. N. Fields ...... ................ 505

A Cytokinin (Isopentenyl-Adenosyl-Mononucleotide) Linked to Ecdysone inNewly Laid Eggs of Locusta migratoria: G. Tsoupras, B. Luu,J. A. Hoffmann ........................................................ 507

A Glycolipid Antigen Associated with Burkitt Lymphoma Defined by aMonoclonal Antibody: E. Nudelman et al. ....... ........................ 509

Damselfish as Keystone Species in Reverse: Intermediate Disturbance andDiversity of Reef Algae: M. A. Hixon and W. N. Brostoff ..... ............. 511

Slow Compressional Wave Propagation in Wet Human and Bovine Cortical Bone:R. Lakes, H. S. Yoon, J. L. Katz ........................................ 513

Cloned Fragment A of Diphtheria Toxin Is Expressed and Secreted into thePeriplasmic Space of Escherichia coli K12: D. Leong, K. D. Coleman,J. R. Murphy .......................................................... 515

Platelet Thromboxane Synthetase Inhibitors with Low Doses of Aspirin: PossibleResolution of the "Aspirin Dilemma": V. Bertele et al. ..... .............. 517

Vasoactive Intestinal Polypeptide and Muscarinic Receptors: SupersensitivityInduced by Long-Term Atropine Treatment: B. Hedlund, J. Abens, T. Bartfai 519

Stimulation of Prostaglandin Biosynthesis by Urine of the Human Fetus MayServe as a Trigger for Parturition: D. M. Strickland et al. ..... ............ 521

Bovine x Mouse Hybridomas That Secrete Bovine Immunoglobulin G,:S. Srikumaran, A. J. Guidry, R. A. Goldsby ....... ....................... 522

Selective Photothermolysis: Precise Microsurgery by Selective Absorption ofPulsed Radiation: R. R. Anderson and J. A. Parrish ...... ................. 524

Brief Deprivation of Vision After Unilateral Lesions of the Frontal Eye FieldPrevents Contralateral Inattention: D. P. Crowne, C. M. Richardson, G. Ward 527

Spontaneous Orofacial Dyskinesia and Dopaminergic Function in Rats After6 Months of Neuroleptic Treatment: J. L. Waddington et al. ..... .......... 530

Treehoppers Transfer Parental Care to Ants: A New Benefit of Mutualism:C. M. Bristow .......................................................... 532

Pregnancy Increases Reactivity of Mice to Phenobarbital: L. D. Middaugh,J. W. Zemp, W. 0. Boggan ............................................. 534

Synaptic Activity Mediates Death of Hypoxic Neurons: S. M. Rothman ..... .... 536

COVER

Pseudocolor electron microscope to-mograph displaying a 6-nanometer slicethrough a Balbiani ring gene transcrip-tion unit. The hexagonal patter sug-gests a sixfold helical organization ofnascent transcripts in situ. See page498. [Donald E. Olins and Ada L.Olins_ Oak Ridge Graduate School of

___IIII Biomedical Sciences, Oak Ridge, Ten-nessee 37830]

29 April 1983, Volume 220, Number 4596

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SCIENCE

s Fiber CommunicationI progress is being made in research, development, and applicationsto glass fiber communication systems. A number of companies arern this field, but at present the Bell System, including Bell Labora-is the leader. In February of this year, the Washington-New Yorkits Northeast Corridor Lightwave Communication System became)nal. Shortly thereafter, the Sacramento-San Jose link of a Sacra-San Diego system was placed in service. The remaining links in boths are under construction and will be completed in 1984 and 1985,ively. The communication capabilities of the links in service are;ive, but recent disclosures of the progress ofR & D indicate that theities of fiber systems can be improved by orders of magnitude.Vashington-New York link contains 30,000 miles of tiny glass fibers.nication through the fibers is by means of light pulses generated by:hat can turn on and off 90 million times a second. The fibers,ng mainly of pure SiO2, transmit light with a wavelength of 1.3tters, In repeater stations every 4 miles, light is converted to electric,hat are amplified and then fed to lasers for injection of pulses intot section of the line.measure of the capabilities of the existing systems is that a pair ofould transmit the entire Encyclopedia Britannica in 1 minute. Butannouncements make it evident that greater achievements will beming as a result of improvements in the fibers and especially in theThe starting material for the fiber is a thick-walled tube of silica)uring the manufacturing process, the tube is rotated while beingA mixture of SiCl4, GeCl4, and 02 is introduced into the hot tube)2 and GeO2 are formed and deposited on the inner surface of theVith further heating, the tube collapses into a solid rod. Later, theulled out into fibers with an outer diameter of 100 micrometers. Theore, with a diameter of 5 to 10 micrometers, has an index of:n greater than the remainder of the fiber. Light transmitted alongr is confined to the core.y breakthrough has been the development at Bell Laboratories ofhat emit light which is practically monochromatic and free of siderhe speed of light is dependent on the wavelength. Confusing signalseach the detector from a source having a number of lines. At agth of 1.3 micrometers, the difference in velocity is minimal.the earlier systems employing lasers with side bands were designediat kind of light. However, the absorption curve of light in silica hasum at about 1.55 micrometers that is considerably lower than them at 1.3 micrometers. Development of monochromatic lasers at 1.55eters has opened that part of the spectrum for use in transmission.anges in the composition of the gallium-indium-arsenic-phosphorusthe emitted wavelength can be controlled. In principle, it will beto transmit simultaneously hundreds of independent signals

a fiber. At the same time, the attenuation of the light with distance,reased. This makes possible a much longer interval betweenr stations. Improvements in the lasers also make possible the use ofpulses. In one experiment conducted by Bell Laboratories, signalsccessfully transmitted at the rate of 420 million per second throughof fiber with no intervening repeater stations.of the equipment developed for long-distance transmission isle to local networks. Glass fiber loops have already been installed inDr of cities, including Los Angeles. With further R & D, costs willly drop, and it will become practical to provide voice, data, andrvices to offices, shops, and homes. Ian Ross, president of Bellories, has predicted that ultimately glass fibers carrying high-speedignals will make interactive video in color as widespread as today'sie service.-PHILIP H. ABELSON