IMMUNOELECTROPHORESIS?

We invite you to examine our line of

equipment and reagents for qual-itative IEP, counter-electrophoresisand rocket immunoelectrophoresis.Our chambers, punches andaccessories feature design simplicitywhich translates into ease of use

and durability.While you are considering our

equipment, please note that we

offerthe stains, buffers and agarose~~~used in immunoelectrophoresis

techniques.Miles also offers a very broad line

of immunochemicals, including pre-

0''0f0"70000 ",0000$,05.500',5,0.,,,').00000.,004,.0:0,5:00j0." 4 cipitati ng antisera to many anim al

and human proteins.

If you want a closer look at our Elkhart, Ind. 46514immunoelectrophoresis Phone: 219-264-8804products, call or write for our MiesLaffiberaBtox37 stoke Pogesill1ustrated catalog . Slough England SL 2 4 LYillustratedcatalog. ~~~~~~Phone: Famham Common 2151

Circle No. 88 on Readers' Service Card

17 FEBRUARY 1978 727

We wish that were the case... that raising acar's miles per gallon lowers its exhaust pollutantparts per million. But mpg and ppm don'tseesaw. They tend to move up or down to-gether, unfortunately.

Given that tendency and a fixed poliutantlimit, how do you achieve good fuel economy in

an automobile engine?MINICOMFUTER EFUEL EMISSIONS Electroncs en-

SAF EGR gineers here at thetISA C_General Motors Re-OR SPEED search Laboratories

are helping close in onthe answer. They'redoing it through an

DYNAMOMETER understanding of thedynamic interaction

between spark advance (SA), air-fuel ratio(A/F), and exhaust gas recirculation (EGR) andhow this affects fuel economy and emissions.Their goals have been to determine the optimumcontrol strategies for the three variables anddevise systems to implement these strategies.

By extending and applying microprocessor(minicomputer) technology and optimal controltheory - the same kind of sophisticated theoryused to control the descent of lunar modulesLab engineers have:* Produced the first on-line dynamometer sys-tem in which a computer, programmed with amathematical optimization algorithm, auto-matically converges on the maximumeconomy. point(represented atright) in a run-ning enginewithin specified,emission limits.It does thisat speed-loadpoints typical offederal drivingschedules.

* Modified thissystem so thatthe computermakes the engine think it's in a vehicle, thendrives the "vehicle" through federalschedules.

Upwith mpg.

down with ppmm

General Motors

Reseairch LabortoriesWarren, Michigan 48090

* Developed a unique computerized test facilityin a station wagon to evaluate experimentalcontrol concepts in a real-world environment.Not exactly a giant leap for mankind. Just

three of the many determined steps we're takingon earth to push mpg up while holding ppmdown.

SCIENCE, VOL. 199732

S e p a r a t e m o s t s a m p l es_i n

les s t h a n a| m i n u t e;wi t h a n

E pe n d or V M i r C e n t r i f u g e._I_ _ __ : _ _ _X _0 _ _ _ _ _ - - - ; _: D _ _ : w_'6

Just as Eppendorf Micropipettes greatly simplify samplepick-up, Eppendorf Micro Centrifuges greatly simplify sampleseparation.

Compact and quiet-running, Eppendorf Micro Centrifugesare precision instruments that mjaintain constant high speedregardless of load. Because of their very high speed, thesecentrifuges are ideally suited for a wide variety of clinical andresearch applications, particularly those. involving separationof heat-sensitive materials.

iFor maximum sped, choose Model 5412. It acceptstwelve disposable Eppendorf 1 .5ml test tubes in an angledrotor, or twelve 500/Al, 400,.1 or 250AI tubes using adapters.It reaches 15,000 rpm (RCF 12,800xG) in just ten seconds,and stops in fifteen seconds.

For maximum capacity, choose Model 5413. It acceptsforty 1 .5m1, 4001I or 25/l tubes fin four vertical carriers

that each hold tenf tubes horizontally. Model 5413 attainsa maximum speed of 11,500 rpm (RCF 6,500xG).

Both models are equipped with automatic 15-minute timer, safety switch (prevents operation

with top open) and safety lid lock (preventsopening lid while cientrifuge is spinning).For literature describing Eppendorf MicroCentrifuges, test tubes, adapters andaccessories, write: Eppendorf Division,

E;X; ;...Brinkmann Instruments, Inc., CantiagueRoad, Westbury, N.Y. 11590. In Canada:Brinkmann Instruments (Canada), Ltd.

......

Circle No. 102 on Readers' Service Card

weHEWLETT-PACKARD

Model Your Cost Model Your CostHP 67 224 step programming S357.95 HP 97 224 Program Step/Printer $596.95HP t9C Comb betw. HP25C/HP67/ptr 274.95 HP 29C Comb bet. HP25C/HP67 154.95HP 92 Bond Trader-Finance-Printer 496.95 HP 25C Scient. retains memory 127.95HP 25 Scient -programmable 99.50 HP 27 Comb Bus.-Science-Stat. 138.95HP 80 R/E-Bus-Fin-200 yr calendar 234.95 HP 91 Printer Scient.-HP 45 specs 25995HP 21 Scient. slide rule 63.95 HP 10 hand held Ptr-mem., small 139.95HP user lib solut books I40each 9.50 HP 22 R/E Business-Finance 99.50

HP accessories at discount pricesBetween 2/1/78 and 3/31/78. buy one HP-67 or 97, get $105 wonh of software free. Buy oneHP-19C or 29C, get S37 50 of software free.We are an HP franchised dealer Each unit comes complete with charger, bateries. case.manuals One year guarantee by Hewlett-Packard We will beat any deal Try us

TEXAS INSTRUMENTSModel Your CostTI 59 960 prog step 100 mems 0214.95PC IOOA printer for TI 59-58 56-52 146 95 Model hour CostSR 40 Scoent slde rule, pareritheses 24.95 TI 30 Scient slide rule, parentheses S17.95Bus. Analyst R/E and Finance 28.95 Money Manager for R/E and Finance 18.95SR 51-2 Super Slide Rule-Conv 48.95 TI 1750 Thin, wall. LCO 2M Hrs, mem. 17.95Data Clip pencil thin LCO 1000 Hrs 28.95 MBA Business-Finance-Stats 64.95Tl 1680 Instant Replay calcs 25.95 Little Prof for kids 5 yr./up 12.95TI 2550-3 Business-Memory 2595 Data-Man (Big Prof.I educ. 21 95TI 5040 Printer-Doisplay-Memory 98.95 TI 5015 Printer-Grand Total-Percent 64.95TI 5050M AC-DC printer, memory 83.95 TI 5100 Desk-Digital. mem -percent 4395Tl 1050 Mem. pcrcent-square root 12.95 TI 1025 Memory-Percent-+-l 10.95Libraries for TI 59 and TI 58 29W00 TI Digital Watches 5 funcs. from 995TI 58 480 step prog -60 memories 97.95 TI Digital watches all models inclTI 57150 step prog -replaces SR56 63.95 Star Wars LED-LCD-Ladies-Men's

-All styles 9 95 upWe are a TI franchised dealer and carry TI accessories at discount prices.We vinll beat any deal. Try us All TI calculators are guaranteed by Texas Instruments. Inc.

SPECIALSModel Your Cost Model Your CostNorelco #185 Dictating unit 99.95 Sony KV-2141R Color Remote 21 619.95Norelco #88 Dictating unit 242.00 Sony Betamax 879.95Norelco #186 Transcribing unit 245.00 Zenith Video Recorder 859 95Norelco #NT-1 new dictating unit 164.00 RCA Selectavision 819.95Norelco #97 dictating or transc 298000 3M dry photocopy machine #149 79.95Norelco #98 dictating or transc 40900 Hughes calculator watch 119.95Norelco Minn Cassenes 2.95 LCD calculator watch 199.95Craig # 2625 elect. notebook 149.00 Atari comput TV garne/27 war games 159.95Craig #2706A dictating/transc 18995 Phone Mate-Code A Phone-Sony KV-1204 Color Trinitron 12" 309 95 Record A Call-Ans. Systems call usSony KV-1512 Color Trinitron 15" 359 95 Chessmaster II, comput 199.95Sony KV-1541R Color Remote 15" 409.95 Gammonmaster adv., comput 199 95Sony KV-1741R Color Remote 17" 469 95 Royal, APF-Lloyd, Victor, Oliv.Sony KV-1921 Color Trinitron 19' 449.95 Unitrex. etc. print calcs call usSony KV-1941R Color Remote 19" 529.95 Atari pinball TV game 74 95Sony KIt-2101 Color Trinitron 21" 55995

We carry Royal Oliveeni- Smith Corona Amana--Linon Commodore-APF Unitrex Canon Casio--Sharp Panasonic Sanyo -Bally JVC -

HY Gain Kosmos Vyctor Sinclairn Pearlcorder Midex alarm 3MMicroma -Lloyds Boshei Rockwell Sentry Sates- Walton Gymequipt RCA Zenith Sony -Atarn-Phone Mate-Record A Call-Code APhone and many more Over 20,00D units (Try COFFEE PLUS at S1 79 perone pound can bin he case of 24 cans Frerqht prepaid Good seller

Prices are t.o.b LA. Goods subject to availability Ask for our famous catalog.We will teat any prices it the competition has the goods on hand.

Add S3 00 for shipping hand held calculators CA residents add 6% sales tax

I&,'f'i ,~,,p

w urace a uo., North Bergen, N.J. UIU47 Circle No. 162 on Readersj Service Card

Circle No. 184 on Readers' Service Card

New Enzymes ForMolecular Biology |New product research at P-L Biochemicals has resultedin these often requested items to support your effortsin Molecular Biology.0918 DNA Polymerase For several

(T4-infected E. coli) intern progra20,000 units/mg, 70% pure .... 100 units .... $45.00 natural and s

0919 DNA, Nuclease Digested, Assay and prodducticReagent, Mung Bean Nuclease In 1978, otlTreated CT-DNA ........... 5 vials ... $16.00 dents, primar

0734 Polynucleotide Kinase Gratis with 0918 apply to bc(T4-infected E. coli), 80% pure vision station"Nuclease Free" ............. 100 units.... $72.00 oult the U'nite

portuinity to p~0880 RNA Ligase (T4-infected E. coli) pn(lt idtas bec

"RNase Free"........ 100 units .... $60.00 tnig of editori0870 DNA Ligase (T4-infected E. coli) scinination, (l

Suitable for Recombining DNA .100 units .... $50.00 of science to

0912 NUCLEASE, MUNG BEAN carecr choiceSingle-Strand specific ......... 5000 units ... $45.00 To obtain a

These products must be shipped cold. Insulated container and tion procedusrefrigerant charge - $6.00. May require air freight shipment.

excellence inbiochemistry

abiochmicals,inc. Thetteatl1037 'NEST McKINLEY AVENUE. MILWAUKEE, WNIS. 53205Call (414) 347-7442 Telex 26881

808 Circle No. 194 on Readers' Service Card

UI I-01n

Circle No. 138 on Readers' Service Card

I~~~~~~~~~~~~

SCIENCE, VOL. 199

Let me sendyou a freefolder ofSlide-filingIdeas with

the versatile VPDSLIDE-SHOO SYSTEM

For protecting, fast viewing, filing and find-ing slides it is superior to anything around.Rigid, plastic pages each hold 20 slides,each protected in a recessed slot. No vinylpockets to trap moisture and damageemulsion. Translucent, matte, light-dif-fusing backing for easy viewing, even inordinary light. Pages nest compactly, 10pages (200 slides) per inch, fit file drawersor ring binders. Ideal for medical, scien-tific, educational and other visual com-munication applications.

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AAASMlass Media

7 InterntProgram

yvears,,AAAS has had a unique, 10-weekam to support advanced students in the,ocial sciences as rcporters, researchers,on assistants in the mass media.itstanding natural and social science stu-rilv at the graduate level, arc inivitcd tome suminer interns at radio and tele-

is, newspapers and magazines through-d States. These interns wvill have the op-articipate in the process by which events'ome news, to increase thcir understand-ial decision-making and in formation dis-ndl to prepare themselves as interpretersthe ptublic, no Inatter wvhat their finalinav be.deliscription of the prograiim an(l applica-

res, write to:Coordinator

Mass Media Intern ProgramAAAS, 8th Floor

776 Massachusetts Ave., N.W.Washington, D.C. 20036

[line for receipt of application is27 February 1978