Courses

1miminology. I alke Forr est. Ill. 20 JuIly-l Aulguist. This couirse is intended priml iily for university or college instructors w ho requlire more breaidth of knowledge of imminlle mechanisms for teatching aind research. Limited to 50 andl selection xw ill he on a competitive basis. Applicants shou1ld submit a letter to Dr. Fdxx ard C. Fra nkliin. Ilrofessor of Nledicine, New Yorlk University, College of Medicine. Newx Yorki 1)01 6, iot 1latcr thloa, 1 April. The letter should be alccompanied hb yi) ,a CUIIricUltim vit.ae, (ii) cuirrent research and activities. (iii) reasons for xv anttraining; ing to enroll in the coUrse, and (iv) backgi otInd in immuinology. This material shotildt be in qUad rUplicate. IFcc: $1(00) per diem costs aire approximately $1t). (Dr. Peter- A. Ward. Chief. Immtinobiology Branch. Arimledi Forces Instituite of Pathology. Washington, D.C. 20305) ropics ill Quaiitum Il Icctroiiics. San Francisco. Calif. 2-6 Febl-Liua-y. Topics x ill inclede Q-sxx itching and modle-locking of lasers. self-foCLusilln and defocusing of laser hearns, laser deflection and modUlation, gene ration and propagation of iltrrashort puilses. far infrared sotu rces. nonlinear optics and high-power lasers. F c: $30)0. (ContillUillng EdLICation in Engi neering. Unixeisity of California Extension, 2223 Fuilton St. Berkeley 94720) Funidamenitals of Electrode Kinetics. Rolla. Nlo. 26-28 Januar y. The Couir-se is designed for those workiing in the electr-ochemical field who may havxe a good xvoi-k ing kno\ ledge of their area buIt have had little or no formal training in fundarmental principles. Subjects to be inclutded are (i) introdLction to electrode measurements (.ipplication of the Nernst equation. react ant and prodLict activities. refer-ence electrodes, cell design and potentiall cLiurenit relationships) and (ii) introductionl to electrodle kinetics, transient and cyclic techniiquLes, anodic processes. cathodic pr-ocesses. and corrosioni. Fcc: $2t)0. 1)Dadliuic for (Ipplicatiohi s: 19 January. ( Fxtension Dix ision. University of MissoLuri. Rolla 65401 ) C(omputer Graphics-From the 60's to the 70's. Las Vegas. Nev., 2t)-21 Nox emheI. Fhis seminar deals with a suihject xwhich has trig-ered an exciting era in man-machine communication aind the tech nological i evolution. The fasciniating possibilities of a draxx ing that can be consti ticted dynamical ly on a cathode-ra;yihe display wx ith a light pen and then modified. irepeated. expanded. or coniracted. devxeloped iiito thr-ee dlimensions. A d1 simIlultanLIeously iubjected to precise comIputiation0ll iianlysis-hax e stirr-ed the imna-iilations of reseaii-ch and design en-inerCIs, scienitists, architects, mendical doctors. eduLcAtoi s. and many others. There w-ill he sex-eral moxvies covei inc a xx ide ar iety of subjects. suIch Is stRict iLii-l desigil. circLit design. numeric;al contr-ol, and medicine. A panel xx ill discusS the prob1emns of stairting in compuIter graphicsthe ec)noniics, the fUndamentals. mnianaement's x icx point. aind the fituLi-e of compuitcl griaphics in science and enginecirIn. ( Fngineering Update InstitUtes. 1'.0. Biox 39/V. Woodlands Hills. C ailif. 9 1364)

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POSITIONS WANTED: 40 per word, minimum charge $10. Use of Box Number counts as 10 additional words. Payment in advance is required. These rates apply to individuals only. Personnel agencies and companies take display rate for all advertising. POSITIONS OPEN: $7 per column line, if publisher's type is used (12 lines = 1 inch). Minimum ad is 12 lines or $84. All ads using larger than 6 point type will be billed as display ads at $90 per inch. No charge for Box Number. Rates net. No agency commission allowed for ads under 4 inches. No cash discount. Ads over 1 inch will be billed to the nearest half inch. Payment in advance is required except where satisfactory credit has been established. COPY for ads must reach SCIENCE 4 weeks before issue date (Friday of every week). Send copy for Personnel Placement advertising to: SCIENCE, Room Massachusetts Ave., NW Washington, D.C. 20005 Replies to blind ads should be addressed as follows: Box (give number) SCIENCE 1515 Massachusetts Ave., NW Washington, D.C. 20005
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As part of an expanding program, the Research Activities group of SK&F's dynamic Science Information Department is now seeking a modern, versatile Ph.D. organic chemist, preferably with both industrial and postdoctoral experience. The successful candidate will probably be experienced in the evaluation of biological data, have some foreign language facility, and be willing to undertake domestic and foreign travel. The position entails two principal areas of responsibility both of which offer excellent opportunities for publications. generation and maintenance of research associations with both U.S. and non-U.S. academic chemists * research team involvement: correlation of chemical structure with biological activity; provision of chemical back-up utilizing available information services; generation and presentation of research ideas. The position demands ability to work effectively with top research scientists and offers an outstanding opportunity for personal and scientific growth and development. Salary and benefits are excellent. Send resume in confidence to John A. Paro, Employment Manager,
GRADUASTETUDY lI I I I I IBI I I I
Postdoctoral Traineeships In Journal Editing. Applications are invited for the third 8-month training program for executive editors of biomedical journals, to begin October 1970. Applicants must have a doctorate (Ph.D. or M.D.) in science and at least 3 years of research experience, including publication in scientific journals. No editorial experience is necessary. All aspects of journal editing and management will be taught through experience with editorial offices of five leading biomedical journals. Trainees will receive a stipend commensurate with their training, experience, and present status. Apply (enclosing a curriculum vitae) by 15 December 1969 to Dr. F. Peter Woodford, The Rockefeller University, New York 10021.
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Applications are invited for teaching posts available in the Deprtment 1 July 1970. Academic rank and salary depend on the experience of the candidate. The successful candidate is expected to develop a strong research and Graduate teaching program in one of the following areas: Population genetics; Developmental Physiology or Genetics; Sensory Physiology and Systems Analysis; Plant Physiology or Biochemistry; Phycology. Suitable candidates in other areas will be considered. In early 1971 the Department is moving into new quarters with excellent facilities Applications, giving names of two referees, should be sent to the Chairman, Department of Biology, Dalhousie University, Halifax, Nova Scotia, Canada.

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M.D. Write Dr. G. S. Marks.
Physiologlsts: (a) Recent Ph.D.; teaching and research in Dental School located in Midwest (may teach medical physiology in the future); 1 February, 1970; opensng begins January orannual salary about Assistant Professor with $14,000; indicate your interests: (1) Teaching and research or (2) administration, teaching, and research; send r2sum6 including name and address of three reerences. (b) Sabbatical leave or retired personnel who would like to teach physiology in Dental School from 1 February to 31 May 1970; remuneration open; send r6sume to Box 381, SCIENCE.

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SCIENCE. VOL. 166

MAKE PACKARD YOUR SOURCE FOR

References and Notes

1. L. V. Ackerman and J. A. del Rcgato, Cancer -Diagnosis, Treatienit, anid Progiiosis (Mosby, St. Louis, Mo., ed. 1, 1962), p. 821. 2. M. J. Allen, E. Boyland. C. E. Dukes, E. S. Horning, J. G. Watson, Brit. J. Canicer 11, 212
PRE-M IXED SCINTILLATORS. PREPARED LIQUID SCINTILLATORS

(1957).

3. H. Eisenberg. D. F. Odoardo. T. C. Campbell. Cancer in Conniiecticit Mortality Data 1949-1961 (Connectictut State Dept. of Health, Hartford, 1964), p. 68; 1969 Canicer Facts and Figires (American Cancer Society, New York, 1969). 4. D. R. Stoltz, K. Khera, R. Bendall, S. Gunner, "Cytogenetic studies with cyclamate metabolites," talk given at the Eighth Somatic Cell Genetics Conference, 7 Oct. 1969 at Chatham, Mass. 5. M. V. Barrow. in Birtl Defects Origiuial Article Series 5, D. Bergsma. Ed. (National Foundation, New York, 1969), pp. 202-206. 6. J. G. Wilson and J. Warkany. Teratologu' Printciples antd Techniques (Univ. of Chicago Press, Chicago. 1965), p. 35. 7. A. S. Goldman and W. C. Yakovac. Arch. En,siron. Healthl 8, 648 (1964). 8. M. S. Legator. K. A. Palmer, S. Green. K. 'V. Petersen, Science 165. 1139 (1969).

Reactors and the Public Good
It is dismaying to find that The Careless Atom, by Sheldon Novick. was assigned to a book reviewer (I Aug., p. 483) who admits to "not being an expert in these matters." I find The C'aleless Atom77 a thinly disguised antireactor tract which seems more intended to alarm than to inform. It contains statements taken out of context, misrepresentations and partial presentations of fact, and depictions of conjectures atnd events of low probability as seeming imminent disasters. Novick uses several excerpts from hypothetical studies of reactor accidents to support his allegation that the potential consequences of a reactor malfunction are unacceptably great. One finds irn the book no accompanying indication of the assumed succession of human, mechanical, and structural failures on which these postulated incidents are based, and hence of their extremely small probability. He states that the dozen atomic power plants which were to be built by the utilities alone or in cooperation with the Atomic Energy Commission "ran into trouble from the outset. The Fermi and the Hallam plants, both novel types l(which have presented economic problems to their backers but no radiation hazard to the public), are cited. From reading The Careless Atom one would not know of Yankee, Indian Point I. or Shippingport, not to mention the total of about 100 other reactors in the United States, that operate rouLtinely and dependably. Besides offering a one-sided picture of the safety and reliability of nuclear reactors. Novick has made a sensa-
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Make Packard your source for all nuclear chemicals and supplies. For complete details write for 28-page catalog 405U to Packard Instrument Company, Inc., 2200 Warrenville Road, Downers Grove, Illinois 60515 or Packard Instrument International S.A., Talstrasse 39, 8001 Zurich, Switzerland.

I Packard I

Circle No. 91 on Readers' Service Card 686
tional rather than a factual presentation to suggest that the current radiation protection standards for the routine discharge of low-level radioactivity from nuclear facilities are inadequate to protect man and the environment from present serious risk and future calamity. He describes radiation effects quite graphically, but without relating them to dose or doserate. Thus he gives his lay readers no quantitative basis for assessing the degree of the risk involved. Although the releases of radioactivity during past years to White Oak Lake and to the Columbia River. which Novick uses.as examples, were considerably in excess of the amounts from modern re.actor power and fuel reprocessing f'acilities, neither has constituted a demonstrated radiation safety hazard to even the immediate populations. With regard to current releases Novick asserts that "reactors will continue to function just within AEC limits." This is contradicted by Bloemke and Harrington (AEC Report ORNL-4070), from which I conclude that most re.actors function at less than 1 percent of these release limits. Novick attacks the basis of public r adiation protection standards which are set in comparison to background and ,at which no measurable damage is anticipated. He says, "It is past time that we realized that in radiation 'n3o measurable damage' eventually means 'not quite fatal' for everyone." This is a large assertion which indicates either Novick's bias or his ignorance of the painstaking search of the considerable available data on radiation effects mlade by such bodies as the International Commission on Radiation Protection, of the careful interpretation iriade by them in recommending radiation protection standards, and of the conservative practices of health physicists in their application. In my view, to live in the health and well-being made generally possible by a technologically developed society is also to live at risk from a host of potentially deleterious agents. Before getting upset about the possible risk from the operation of nuclear reactors and associated activities, a reasonable person, it seems to me, would want to arrive at the best possible quantitative judgment of how this compares with other accepted risks. I believe that anyone who does not have an a priori conviction otherwise will find it small. This is not to suggest that there are no disagreements about safety within

SCIENCE, VOL. 166

`11.11

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Add this low-cost option to your Tri-Carb Liquid Scintillation Spectrometer and you're ready to do fully automatic gamma counting on up to 100 samples. Model 5022 uses the electronics of your existing instrument for sample analysis and changer actuation; it has its own sample changer and well-type crystal detector. Its beta-gamma switch and independent high-voltage supply let you switch from beta to gamma counting with no adverse effects on counting stability. "Built-in" gamma counting capability is just one of the user-oriented features you'll find in Tri-Carb Liquid Scintillation Spectrometers. Doesn't it make sense to choose a system that can grow with your needs? Call your Packard Sales Engineer for details, or write for Bulletin 1057U to Packard Instrument Company, Inc., 2200 Warrenville Road, Downers Grove, Illinois 60515, or Packard Instrument International S.A., Talstrasse 39, 8001 Zurich, Switzerland.

Get Set!

just remove the protective bag. Complete pre-sterilized systemeverything you need except the

vacuum.

Amchitka: Waves of Opinion
Carter's technique in his article on large-yield explosions on Amchitka (22 Aug., p. 773) is to quote the opinions of "authorities." Though factual in the sense of offering valid quotes, this approach does not truly provide the reader with a basis for drawing
his own conclusions. Carter further fails the scientific community by (i) quoting only seismologists who feel some degree of alarm (he could have quoted others of equal scientific renown who would have said there was no danger from large tests on Amchitka), and (ii) quoting the opinions of other scientists who have no basis for forming definitive opinions on the subject, or who are allowing their scientific opinions to be dictated by their political beliefs. Much scientific information is available on the matter and could have been presented by Carter if he had attended the meetings of the American Geophysical Union or if he had sought the data. The possibility of venting is to be argued only by inspection of the venting history at the Nevada Test Site and Amchitka, that history being available. The possibility that large shots on Amchitka would cause tsunamis should be evaluated in terms of the relation between large shots, observed patterns of seismic radiation from such explosions, observed aftershock activSCIENCE, VOL. 166

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Nalgene Filter Units are available with Sartorius membranes-0.20 micron (plain) or 0.45 micron (grid) membrane porosities. One dollar each. When you specify Nalgene Labware, 20 years' leadership says you're right. Ask your Lab Supply Dealer for our catalog or write Dept.2111, Nalgene Labware Division, Nalge Company, Rochester, New York 14602.

Moon, Mars, and Money

Carter's rundown on NASA plans (5 Sept., p. 987) prompts me to recall Geographer George Sauer's comment as chairman of the international symposium in the 1950's on Man's Role in Changing the Face of the Earth. "We are now come," he said, at the end of that week, "to a revised version of Aldous Huxley's 'brave new world' of the '20's-to a faceless, mindless, countless multitude managed from the cradle to the grave by a brilliant elite of madmen intent on technological progress." Paine knows full well that there is a great deal more to be done, of vital urgency, than "to fill 200 million alimentary canals every day." For one

SYBRON CORPORATION

Circle No. 97 on Readers' Service Card 688
Start with the excellence of the Gilford Monochromator-cast housing for lasting, precise alignment of the finest optical system and control mechanisms-obstacle-free exit plane-integral aperture slide with standard and micro apertures-four place manual positioner with accuracy for micro cuvettes - rugged optical bench for rapid interchange of accessories. Enjoy the convenience and accuracy of linearized wavelength and slit width controls-direct digital indication-wavelengths readable to 0.1 nm. - slit widths adjustable and readable to 0.001 nm. Both control mechanisms are free of backlash and vibrational instability, and make provision for attachment of servo drives. Put to work the unique usefulness of the Gilford Linear Absorbance Photometer-accurately linearized output directly in absorbance, not % T converted to A-resolution of 0.001 A throughout the entire 0.000 to 3.000 A measuring rangedirect absorbance indication in clearly readable digits-0.05 % A photometric accuracy-less than 0.01 A drift per hour. These inherent advantages, coupled with the Gilford "building block" design concept, permit you to add attachments as needed for automated operation and special applications. The rapid quantitation of enzyme rates, for example, is
achieved with the patented combination of the Gilford Photometer, Gilford Automatic Cuvette Positioner and a linear strip chart recorder. Unlike % T instruments, the Gilford linear absorbance output requires no damping circuitry. With the Gilford Model 240 Spectrophotometer, you have the potential of starting with a fundamentally superior basic system and converting it to as sophisticated a system as you may ever need. Thousands of research, clinical, and industrial laboratories have discovered that Gilford systems offer unsurpassed versatility for a wide variety of spectrophotometric techniques.

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Linear Strip Chart Recorder. Registers linear absorbance output directly. Full scale sensitivity variable from 3.0 A to 0.1 A. Readable to 0.001 A.
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and breakage.

Circle No. 15 on Readers' Service Card

7 NOVEMBER 1969

ity, and the regional strain pattern in Nevada, and locations and modes of genesis of tsunamis, location of Amchitka relative to earthquake foci and observed seismic radiation patterns from Longshot. GENE DAVIDSON 17269 Tennyson Place, Granaclda Hills, Californlia 91344
We're not lost in the crowd.
Davidson misrepresents my article by seeming to suggest that I arbitrarily chose to quote only those scientists who feel some concern about the Amchitka test series. To the contrary, several of the scientists' whose views I mentioned were members of the President's Science Advisory Committee's ad hoc panel on the safety of underground testing. Two others whom I mentioned, and who also are concerned about the Amchitka tests, are members of the AEC's own ad hoc panel on seismology. If I have chosen my authorities from among scientists whose judgment is colored by political beliefs, it would seem that the PSAC and the AEC have committed a similar error. LUTHER J. CARTER Science
There are lots of UV flow monitors, but only ISCO:
records directly in linear absorbance.
has the least stray light-low enough to permit quantitative results in practically all applications.

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Dyons Versus Quarks
Two quite different references to particles of fractional electric charge have appeared recently in the pages of Science. The term "quark" was introduced in 1964 to designate hypothetical entities carrying electric charges of one-third or two-thirds the normal unit. In a "Research Topics" article (26 Sept., p. 1340), Robert W. Holcomb has reported on Australian cosmic ray observations of a few events with less than normal ionization, which were detected in very high energy showers. This has been advanced as evidence for the quark, although a more conventional explanation is also
operate a fraction collector so separate UV-absorbing peaks are deposited into separate tubes.
steroids in research, Brinkmann's new EMReagents Steroid Catalog is 'must' reading. Its 28pages are crammed with valuable information on more than 100 differentcompounds, including molecular weight, chemical and structural formula, and various technical data such as melting range, specific rotation and extinction, loss on drying and sulfate ash. To make this catalog really complete, we've also included packaging and price information for each compound-just in case you'd like to order. For your free copy, write: EM-Reagents Division, Brinkmann Instruments, Cantiague Road, Westbury, N.Y. 11590. In Canada, write: Brinkmann Instruments (Canada) Ltd., 50 Galaxy Blvd., Rexdale (Toronto), Ontario.

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mentioned in this article. The other reference occurs in my article "A magnetic model of matter" (22 Aug., p. 757). It is pointed out that the speculation of magnetic charge can account for the observed integral nature of electric charge in ordinary, magnetically neutral, matter, while also implying that particles carrying both electric and magnetic charges can exhibit fractional electric charges in just the way suggested by high energy particle empirics. To emphasize the fundamental dyad of
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Circle No. 95 on Readers' Service Card

automatically at all points in the log scale. There's also a switch for inactivating the zero adjustment and automatically setting the voltagedivider zero-point. Conformance of the logarithmic scale to the theoretical function is 0.003 at any point.
But the SRLG is a linear-log recorder. (You change the mode of operation by simply changing the gears.)

log A=log e + tog cl

Its accuracy on the linear scale is 0.25% of full span and its reproducibility is 0.1% of full span.
We discuss here some of the advantages of recording the logarithm of absorbance.
To begin, the term absorbance (A) Is defined thus:
such as for "fingerprinting"' a compound.
'Now when we plot log A versus wavelength (figure 2), we immediately see our three 1:2:5 samples are represented by curves that have identical shapes. Each curve is that of
log e displaced along the log A axis by the amount log c/. And each curve is separated by intervals that correspond to the 1:2:5 ratio of cL
and for quickly determining reaction rates.
As long as the reaction is first-order, both log (c-x) and log A will be linear with time. So when we plot log A versus time at a fixed wavelength for a first-order reaction of a dye fading, we get the curve shown in figure 3.
The linearity of the curve in figure 3, in itself, tells us that this is a firstorder equation. And where the linear section of the curve termintes (-'t the right of the curve) indicates a departure from strict first-order reaction. Finally, the rate constant, k, can be determined from the slope of the linear section. These applications-for fingerprinting a compound and for studying the kinetics of first-order reactions-are but two to which log A recording is eminently suited. Other applications
and we, of course, also recommend the ideal recorder for the task:

our own SRLG.

The SRLG Linear-Log Recorder, like all Sargent recorders, is true potentiometric in its basic (millivolt) ranges, with no voltage dividers to load 4he circuit. Its full-scale pen response is less than 1 second. There are seven switch-selected, calibrated spans and three switchselected chart speeds. Plus improved input filtering and circuit guarding to eliminate A.C. components of the input signal. All circuitry is solidstate. And batteries have been replaced by zener-diode regulation of all critical voltages.
where c is the concentration of sam-
ple in the absorption cell,
I is the light-path (the inside distance between front and back windows of the cell), and
e is a numerical coefficient.
Here's where the "fingerprinting" of compounds comes in. Reference files of log A recordings facilitate the identification of unknown compounds

by making it easy to compare their
log A curves to those already on file.
Large files of this sort are used in organic synthesis. Now, a new topic: log A recording is also a valuable technique in studies of the kinetics of first-order reactions.
The fact is that e is a characteristic
of each compound or substance. It

FIGURE 1

FIGURE 2

FIGURE 3

<04

<0:~

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II II 4 I s I I 7 I

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Is dependent on temperature and wavelength, but independent of either the concentration, c, or the light-path length, /.
For proof of this statement, we resort once again to a basic equation:
include the precise specification of color and the measurements of small differences in color. In all cases, this type of log recording requires an advanced, accurate, versatile recorder. The Sargent SRLG Recorder is just that. It uses precision, non-linear gears for accuracy and fidelity; these gears are much superior to electrical circuit approximations. Amplifier gain is adjusted

Readers' Service Card

SARGENT-WELCI
If we plot A versus wavelength for three samples of the same substance In concentrations in the ratio 1:2:5, we get the curves shown in figure 1. There is, unhappily, no basic correspondence among them.
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dc is the rate at which the dt concentration is decreasing with time.
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k is the velocity or rate constant, and

Is the concentration

Circle No. 5

SCIENCE,

VOL. 166