HEALTH SCIENCES LIBRARYMQMASTER UNIVERSITY

OlENCEOCT 1 5176

3 October 1975Volume 190, No. 4209

.vI-036iD

..*~tIt

"'I*

_ s}_

- 1WaI, E. =

01w 8 e

I.ll,Dj q-,;

.:-t+ ej, ¢~~~~~:I:

,, e'*t "

L 1- ^

rn .-w.5C

04

'Z_*_ C_i, A:t* ::,

, i. idWgAM_lmi, {A

K ., 4'-A-.

¾4t

AMERICAN ASSOCIATION rOR THE ADVANCEMENT or SCIENCE

_W :0w

V - -1. ,I

. -Ovw4

A&

w .&A--

.. . -% jw,., & ";Is. .1.1 -.., v. "I

5. fts"WlOZ..', -q.- ., -:1 ',ioo".. . s

.,t ,,I

, NI

-1%4. -00, .

. t. ,

k., *..

I

I.,-1,

6.NV=

.^ XI't .,

.- **,

--..: . 7

Awl, .'.-, 't-

t,.,'O- , 'W. I

4., '-.w4t

Now there are

3L4 Rotors for Beckman

L-5 Ultracentrifuges

These two new rotors join 32 otherBeckman preparative ultracentrifugerotors- 16 fixed angle, 10 swingingbucket, 5 zonal, and 1 continuousflow- to meet virtually any separationneed.

Both these new rotors are unique.The Type 25 in the foreground is

the first ultracentrifuge rotor to hold100 samples. It generates 70,000 to90,000 g, depending on the location ofthe tube in the rotor. This high force,together with the small-diameter

1-ml tubes, gives rapid, high qualityseparations of such materials as

lipoproteins.The 45,000-rpm Type 45 is the

first of a new generation of rotorswhich are specially contouredto give them a more favorableweight-to-capacity ratio. Thisone, of titanium, is the onlyfixed-angle rotor capable ofspinning more than a half liter Xat forces in excess of 200,000 g.

The four versions of the L-5, theirrotors and accessories, are described inData File 400/174. For your copy, writeBeckman Instruments, Inc., Spinco

Division, 1117 CaliforniaAvenue, Palo Alto,

o . ~~~CA 94304.

I

mwtC3A

mrrlz;.=

Herekitty, kitty kitty, kitty, kitty!

Between the eyes,the upward arrow.All done with thestatistics of distri-bution of skeins ofultramicro silverfilaments. Forcolor, little cloudsof dye.When magnifica-

tion is carried too far, the subjectiveeffect called graininess manifests itself.It correlates with granularity, a phys-ically measurable quantity. That's notjust playing with words. Graininess,quite appropriately, is the sensation onegets when looking at a handful of grain.If instead of lying helter-skelter in

your palm the kernels were uniformlyspaced, graininess would no longer bethe word for the sensation, even thoughyou were still seeing individual grains.It's randomness that elicits the graini-ness sensation.

Except at extreme right above, oneis seeing only random variations inspacing and overlapping of the indi-vidual silver skeins or dye clouds. Wequantify these variations as deviationsfrom density 1.0 when scanned in adensitometer with a 48-pAm aperture.For all kinds of uniformly exposedKodak films, the root-mean-square ofthe deviations multiplied by 1,000 andappropriately rounded off becomes"diffuse rms granularity value."

Here is how these values relate tothe words we use to state graininess:

45, 50, 55 "Very Coarse"33,36,39,42 "Coarse"26, 28, 30 "Moderately

Coarse"21, 22, 24 "Medium"16, 17, 18, 19, 20 "Fine"11,12,13,14, 15 "Very Fine"6, 7, 8, 9, 10 "Extremely

Fine"5 or less "Micro Fine"Emulsion progress over the years

has consisted largely of lifting the up-sloping line that plots light sensitivityagainst granularity. Result: the num-ber of pictures taken per year goes upmuch faster than acres of film manu-factured-less material required formore and better results with less in theway of equipment and folderol. Goodfor the customer. Good for us.

KITTY IS MISSING! Circulars are to be run off bearing thekitty's picture. But, since the printing press either does ordoes not deposit ink at any given point on the paper, theinformation about that all-important streak on the head isto be conveyed through arrayed dots of varying size.

Dealers in materials for the graphic arts (check the YellowPages) can supply KODALITH AUTOSCREEN Ortho Film 2563(ESTAR Base). It makes possible a simpler procedure toconvert a photo to dots than used for the illustrations in themagazine you are now reading. The sensitivity of its emulsionvaries cyclically with a frequency of 133 per inch. This re-sults in a grid of dots whose size varies with brightness dis-tribution over the image. The film is quite slow; for directphotography, instead of making halftones from existingphotographs, only still-life subjects are practical. But thatmight be quite useful if instead of finding your lost cat youjust want to reproduce photographs decently with a dupli-cating machine. The film can be exposed in a conventionalview camera.

Details in Kodak Publication No. Q-20 ("Making Half-tones with KODALITH AUTOSCREEN Ortho Film 2563"),available from above dealers or Kodak, Dept. 412-L, Roch-ester, N.Y. 14650.

3 OCTOBER 1975

KITTY MAY BE HIDDEN IN HOLOGRAPHIC FRINGES. Whypeople should want to render an image holographically theydon't always say. At any rate, it is reported in Applied Phys-ics Letters for August 1, 1975 that KODAK Holographic PlateType 120-01, employed in a stunt described in 1840 by SirJohn F. W. Herschel, yields what is believed to be the high-est diffraction efficiency (for red-light reconstruction) everreported in an infrared-recording material, with spatial fre-quency better than 1300 cycles/mm. It was Sir John whorevealed the existence of the infrared in the first place, andthen he found that it erased latent image in a light-exposedphotographic material. Now it turns out that infrared holo-graphic images can be recorded by Herschel-effect erasurein prefogged 120-01 plates. Doesn't seem to work on ourother high-resolution emulsions. See Applied Physics Lettersfor details. Type 120 plates are stocked by dealers in holo-graphic specialties.

MEASUREMENTsCOMPUTATION advances from Hewlett-Packard

Two more members join HP'sfamily of small miracles.

The secret of all HP's small miracles is in thekeys, and the array of special functions theyperform. (Just take a moment to examine thekeyboards in the photograph.)But there is one key common to all. It says[ENTER], and is both literal and figurative. Literal inthat you use it to enter data to be computed.Figurative in that it opens the door to answersyou can trust: simply, directly, conveniently.

Like the rest of the family, these two new hand-held calculators feature HP's advanced design,4-register stack, and special logic system. Thesmall miracle is that each leads its class in power,weighs a mere 6 ounces, and costs less than $200.

HP-25 Scientific Programmable Calculator. $195*.

Preprogrammed to solve 72 scientific, engineer-ing, and mathematical functions with keystrokeease, the HP-25 has the power you need to solvetechnical problems.But that's just the beginning. Its comprehensivekeystroke programming capability lets you solverepetitive and iterative problems-even some

complicated ones that force you to wait in line forcomputer time-at your desk, in minutes or even

seconds. The HP-25's programming power in-

cludes a 49-step memory; direct and conditionalbranching using as many as 8 relational tests;integer/fraction truncation and absolute valuekeys; and a full editing capability that lets you see

6

what your program looks like, step by step, and letsyou look at intermediate results by means of con-trolled pauses in the program.The new HP-25 also has 8 addressable memories,each capable of register arithmetic. And it's thefirst hand-held to offer not onlyfixed and scientificbut also engineering notation (i.e., exponent dis-played as a multiple of ±3, as in giga and nano).

HP-22 Business Management Calculator. $165*.

Combining the preprogrammed power of threepresent-day calculators, this new model solves vir-tually every number problem that a business man-ager faces. Its easy-to-use keyboard includes:* A complete range of financial keys for evaluat-

ing time-and-money problems; compound in-terest and internal rate of return; annuity andannuity due comparisons; and margins, mark-ups, discounts, and percent differences.

* Advanced statistical functions including ac-cumulations; mean and standard deviation;linear regression and linear estimate; andgrowth curves.

* A powerful range of mathematical functionssuch as log, antilog, exponentiation, and root .extraction.

Both hand-helds come complete with battery packand recharger, soft vinyl carrying pouch, and com-prehensive owner's handbook. In addition, theHP-25 includes a 162-page book of applicationsprograms concerning mathematics, statistics, fi-nance, surveying, navigation, and games.See the HP family of professional hand-helds atquality department stores or campus bookstores.Call 800-538-7922 (in California, 800-662-9862) forthe name of the retailer nearest you.

SCIENCE, VOL. 190

_,..........-.b __

Preoperative mammogram (in this case,a xeroradiograph) shows a partially cal-cified nonpalpable breast lesion.

9.< Y-a .<>.- .-: :- ..@ ::..:

-,. >EtO, .. S-c. A;~~~~~~~~~~~ii

The specimen x-ray reveals the calcificationsshown in the mammogram, confirming thatthe surgeon has indeed excised the properarea. In addition, the specimen x-ray identifiescalcified sites that may not have been visible inthe mammogram.

The suspicious region is biopsied and the excised tissueradiographed with the Faxitron. Because this small lesion isnot palpable to the surgeon, immediate x-ray examination ofthe tissue is essential to show whether or not the lesion hasbeen removed.

Specimen x-rays: mandatoryadjunct to mammography forearly detection of cancer.

At the Virginia Mason Clinic in Seattle, an HPcabinet x-ray permits fast radiographic analysisof excised breast tissue for detection of cancer-indicative microcalcifications.

Specimen radiography has proved to be a "man-datory adjunct to mammography" according to theVirginia Mason Clinic in Seattle, Washington,where pathologists have used the procedure forseven years in detecting and localizing breast cal-cifications.

Using a Hewlett-Packard 43805 Faxitron cabinetx-ray, pathologists have radiographed more than800 breast biopsies since 1968, when the unit wasdonated to the clinic by the Washington State Divi-sion of the American Cancer Society. Specimenradiographs from the Faxitron have made possiblethe detection of calcifications within breast lesionswhich are not grossly apparent: calcifications as

small as 10 to 20 microns can be identified, permit-ting diagnosis at an early, more curable stage.

Because specimen x-rays can be made quickly dur-ing surgery, while the patient is anesthetized, the

HEVLETTtPACKARD

Sales and service from 172 offices in 65 countries

Faxitron has become important in cases where amammogram indicates a calcification that is notclinically palpable. Specimen radiography ismandatory in such situations because it is the onlyway the surgeon, operating on a lesion that cannotbe felt, can verify whether or not the correct areahas been removed. With the easy-to-operate Faxi-tron available in the pathology lab, pathology per-sonnel can very rapidly take their own high-resolution films without prolonging the surgery.Diagnosis can be quick because the specimenradiograph enables the pathologist to pinpoint thecritical areas for histological examination.Although primarily used at Virginia Mason Clinicfor breast biopsies, the Faxitron also lends itself toexamination and detection of bone lesions andvascular lesions of various body organs.The 43805N Faxitron is certified by Hewlett-Packard to meet the stringent 1975 safety regula-tions ofthe Bureau ofRadiological Health. Price ofthe unit is $4100*.

For more information on these products, write tous, Hewlett-Packard, 1505 Page Mill Road, PaloAlto, California 94304.

Mail to: Hewlett-Packard, 1505 Page Mill Road, Palo Alto, CA 94304.Please send me further information on

HP-25 Scientific Programmable Calculator( HP-22 Business Management Calculator

HP 43805N Faxitron Cabinet X-ray

Name

Company

Address

City State Zip

*Domestic USA prices only.

3 OCTOBER 1975

00549

7

You want the ozone question

So doesAnd most scientists agree thereis time to find the answer.

Fluorocarbons are liquidsand gases used in refriger-ation, for air conditioning, andas propellants in about half theaerosol spray cans sold in thiscountry. Some say that theseuseful, normally safe com-pounds will cause a healthhazard by attacking the earth'sozone layer. We believe this is anoversimplification.

The point is, to date thereis no conclusive evidence toprove this statement. To under-stand, then, why there is acontroversy, it is necessary tounsimplify the issue. We musttreat the real world on its ownterms, and they are complex.

The modelthat raised thequestion.Ozone is continually

created and destroyed by nat-ural forces scientists are seek-ing to understand. The ozonedepletion theory, based on acomputer model of thestratosphere, was reportedin 1974 by two chemistsat the University of California.

This mathematical modelcalculates how fluorocarbons

__ _ _ ~~~~~~~~~30mi.

TRPSHR 8mi

in the stratosphere behaveunder the influence of a seriesof variables (such as tempera-

8

ture, altitude, sunlight, chemi-cal concentration) to affect theozone layer.

In order to estimate hypo-thetical reactions, and becauselittle is actually known aboutthe real ones, the modelersmade a number of assump-tions about the way the upperatmosphere behaves.

The unmeasuredyardstick.

Before anyjudgmentscan be made using this modelas a stratospheric yardstick, itsaccuracy must be determined.

Does it describe the real,three-dimensional world? Tofind this out, the validity of themodeler's basic assumptionsmust be determined.

Turning assump-tions into facts.

Before a valuable industryis hypothesized out of exis-tence, more facts are needed.To get these facts Du Pont andthe other fluorocarbonmanufacturers are fundingindependent technologicalinvestigations in universitiesand research laboratories.Under the direction ofacknowledged scientificexperts, this research isdesigned to either prove ordisprove the assumptionsmost important to the com-puter case against fluorocar-bons.

Some research has beencarried out since the model

was first presented. Scientistsnow have a better idea of theaccuracy of the assumptionsin the model.

ASSUMPTION: Theozone-depleting reaction withchlorine from fluorocarbonstakes place at a rate thatdemands an immediate deci-sion on fluorocarbon use.

FACT: Recent determina-tions of reaction rates disclosethat the ozone/ chlorine reac-tion actually takes place at aslower rate than that assumedby the model. In addition, thesame research has shown thatthe reaction of chlorine withstratospheric methane pro-ceeds at a faster rate. Sincethis reaction tends to removechlorine from the ozone layer,the net effect of both reactionsis to lessen the originally-calculated impact of fluorocar-bons. In fact, the impact wasoverstated by 300%.

RESEARCH: To guidefuture measurements ofstratospheric reactions, a labo-ratory program has beenfunded to measure the reac-tions of chlorine compoundsand ozone under simulatedstratospheric conditions.

Most scientists agree thereis time to conduct the researchneeded to settle the contro-versy one way or the other...before a final decision is madeon fluorocarbon productionand use.

ASSUMPTION: There isno other way tget fluorocar-bons out of the atmosphereexcept by the ozone-depletingreaction.

FACT: One well-knownclass of chemical reactions notconsidered in the model is thatof chlorine compounds in the

SCIENCE, VOL. 190

answered one way or the other.

Du Pont.atmosphere in heterogeneousreactions.

In an article in SCIENCE(Feb. 14, 1975), ProfessorsS. C. Wofsy, M. B. McElroy, andN. D. Sze of Harvard Universitycaution that "If additionalremoval processes could beidentified ... or if additionalsinks could be identified forstratospheric odd chlorine, theatmospheric and biologicalimpacts of [fluorocarbons]would be reduced accordingly."

RESEARCH: Atmosphericchemistry involving ion mole-cule reactions has beendescribed in recent months byseveral investigators. Reactionrates with ion molecules areknown to be extremely fastand are believed to occur pri-marily in the lower stratosphere.

Thus, ion molecules couldreact with fluorocarbons,allowing them to be removedfrom the atmosphere.

ASSUMPTION: Fluorocar-bons are the only significantsource of chlorine available forinteraction with ozone in thestratosphere.

FACT: Many chlorine-con-taining materials are present inthe atmosphere in varyingconcentrations. Of particularsignificance, large amounts ofmethyl chloride and carbontetrachloride have been dis-covered in the troposphereand stratosphere.

In addition, new calcula-tions on the injection ofgaseous chlorine compoundsinto the stratosphere from vol-canic eruptions have shownthis as a significant contributorof chlorine not taken intoaccount by the model.

RESEARCH: Scientists arecompleting an inventory of3 OCTOBER 1975

chlorine-containing com-pounds in the atmosphere. Itmust be determined hownature deals with chlorinefrom these natural sources,before it can be shown thatchlorine from fluorocarbonsmight pose a threat to theozone layer.

Additionalresearch.A fluorocarbon industry

research program is fundingthe development of a com-puter model that will betterreflect the complex chemistryof the stratosphere.

In addition, other studiesare under way to broaden ourunderstanding of the totalozone production/destructionbalance. These will concernthemselves with other strato-spheric reactions affectingozone.

A panel of highly qualifiedacademic scientists will adviseon the technical programscovering various facets of theproblem. This panel of inde-pendent experts will review theprojects, providing a criticalopinion on the pertinence ofeach, the probability of theirsuccess, and the complete-ness of the overall investigation.

Conclusion.Much more experimental

evidence is needed to evaluatethe ozone depletion theory.Fortunately, as most scientistsagree, there is time to gatherthis evidence. Du Pont hasjoined with other fluorocarbonmanufacturers to providefunds for work by independentuniversity scientists. Govern-mental agencies are also con-

ducting research to help in theassessment of the theory.

Should the theory beproven correct after all the evi-dence is in, Du Pont, as wehave stated, will stop the man-ufacture and sale of theoffending compounds.

In the meantime, webelieve that to act without thefacts -whether it be to alarmconsumers, or to enact restric-tive legislation-is irrespon-sible. Final decisions cannotbe made with only the infor-mation at hand.

The independent researchdescribed above is presentlybeing carried out by scientistsat the following institutions:Cambridge University-

EnglandEnvironmental Research and

Technology, Inc.Massachusetts Institute of

TechnologyState University of NewYorkThe Battelle Memorial InstituteThe University of Reading

EnglandUniversity of CaliforniaUniversity of DenverUniversity of IllinoisUniversity of MarylandUniversity of MichiganWashington State UniversityYork University- CanadaXonics, Inc.

This is the second in a series of dis-cussions by Du Pont to offer a perspec-tive on an important subject. If you wouldlike copies of either this or the first dis-cussion, please write to: FREON*,Room 24517, Du Pont Company.Wilmington, DE 19898.

'*Du Pont's trademark for fluorocarbonrefrigerants and aerosol propellants.

lMG-u&traTm °O"

9

The only 1 gallonBlendor in the worldis aWaring Blendor.The only Blendordesigned especiallyfor laboratory use isa Waring Blendor.Formore informationon the world's onlyWaring LaboratoryBlendor write:Waring ProductsDivision, DynamicsCorporation OfAmerica, Route 44,New Hartford,Conn. 06057.

wlaring aib12 SCIENC E, VOL. 190

western ElectricReports:

I~~Afls vWeIon implantationXXwitha new twist.W Xestern Electric produces millions of semi-

conductor components a year for use in BellSystem telecommunications equipment.

An essential step in the process is "doping" -introducinga precisely controlled impurity into the semiconductormaterial to alter its electrical characteristics. Untilnow, that's generally been done through diffusiontechniques which entail masking a semiconductorwafer and "baking in" impurities-basicallya broad brush process.

Bell Labs engineers felt that using ion beams toimplant the dopants would be better than diffusiontechniques. Ion implantation would improve theperformance of some existing devices and would Ion implantation:agaspermit the design of new devices that require very ionized. Ionsare drawn intcprecise control during manufacture. beam, mass selected a

precise ~~~~~~~~~~~~~~~~~implantedinto target wafeBut until recently, conventional ion Withatherotatii

* ' ~~~~~~~~~~~~~~~mechanicalscan meth(implantation systems had serious drawbacks for a 3-inch silicon waheavy doping of wafers at fast production rates. can be implanted inaf

seconds. Conventional.Electrical systems, in which a moving beam mechanical scans requ

scans a stationary wafer, tolerate only relatively abouta minilow currents before the beam starts to spread apart.And low currents mean low production rates.

Mechanical (x-y) systems in which wafers aremoved back and forth across a stationary beam, canuse high currents but are unacceptably slow.

Now, engineers at Western Electric'sEngineering Research Center in Princeton, N.J.have developed a new rotating mechanicalscanner that overcomes the low speed limitationwhile still accommodating a high beam current.

The heart of the rotating scanner is a 20-inchaluminum disc which holds 60 silicon wafersin concentric rings.The disc rotates at about 1000 rpmas it moves from side to side through the pathof a stationary ion beam.The beam tracesa long overlap spiral on the disc.

To ensure uniform dosage, a digital controlsystem adjusts the speed of the disc'sside-to-side motion as the spiral movestoward the center of the disc.

Benefit: Rotating ion implantationtechniques are one more manufacturinginnovation that allows the Bell System tomeet your communications needs reliablyand economically.

©Western Electric

s istoa -ande?rs.

x-yijireute.

SCIENCE, VOL. 190