A theory relating sonic velocity to mineral content in bone, S. Lees and C. L. Davidson, SP525, pp. 179-187 (Apr. 1979).

Key words: bone; collagen; crosslinking modification; curvelinking; hydroxyapatite; sonic velocity.

Bony tissues consist primarily of mineral hydroxyapatite (HAP) crystallites embedded in a matrix of a much softer material, collagen. Currey and others suggested that bone is a two-phase composite, like mineral filled plastics, but the known laws of mixtures give at best a crude approximation of the observed elastic properties of bone. We have investigated the problem by measuring the ultrasonic velocity in mineral filled particulate composites as a function of the mineral concentration.

It was found that the ultrasonic velocity can be predicted for some mineral filled plastics by applying the Reuss formalism to the longitudinal elastic modulus, indicating that these are families of Reuss solids in some sense. Other mineral filled plastics do not seem to obey this rule, the ultrasonic velocity being greater than predicted. Bone appears to belong to this latter class of particulate composites.

The literature indicates that in certain situations the mineral filler affects the plastic matrix, giving the plastic constituent a higher modulus. A maximum longitudinal modulus is ultimately attained so that two Reuss formalism bounds can be obtained, the lower one calculated from the modulus of the unfilled plastic, the upper using the maximum modulus. The ultrasonic velocities of a system of fluorapatite (FAP) filled epoxy was found to lie between such bounds.

Currey and his successors assumed bone collagen has the same elastic properties as tendon collagen and that these are invariant with respect to contained HAP. The literature shows the contrary, that bone collagen, even when demineralized, is more highly cross linked than any other collagen. Moreover, the literature indicates that HAP crystallites are chemically bonded to the collagen

molecules.

It is postulated that bone collagen is stiffened because HAP crystallites form on the intermolecular cross links, encasing them and making their effective lengths very short. It is shown that the sonic velocity for bone can be bounded by two Reuss formalism curves in the same manner as for FAP epoxy.

Ultrasonic properties and microtexture of human cortical bone, H. S. Yoon and J. L. Katz, SP525, pp. 189-196 (Apr. 1979).

Key words: anisotropy; dispersion; elasticity; human bone; microhardness; microstructure; piezoelectricity; thermodynamics; ultrasound; viscoelasticity; wave propagation.

The wave propagation in human cortical bone (dried) was investigated, using an ultrasonic pulse transmission method at room temperature. Firstly, it has been found that the symmetry of human cortical bone is consistent with the hexagonal system, based on the ultrasonic velocity measurement and microscopic observations. The five independent elastic stiffnesses were determined at 5 MHz, and they are (in GPa): C11 = 23.4 ± 0.31, C1 = 32.5 ± 0.44, = 8.71 ± 0.13, C12 = 9.06 ± 0.38, c1 = 9.11 ± 0.55. Secondly, this study shows that bone filters and polarizes ultrasonic waves. Thirdly, since, in a piezoelectric medium such as bone, the wave propagation (or elastic stiffnesses) is modified by the piezoelectric coupling, the piezoelectric contribution or “stiffening" was calculated for bone, employing the piezoelectric and dielectric constants of bone

C44

reported in the literature. Compared with the corresponding values of two well-known piezoelectric materials, aquartz (single crystal) and "poled" barium titanate ceramic (polycrystalline), it has been found that the piezoelectric "stiffening" in bone is negligible. Finally, the sound velocities were measured over the frequency range of 1 to 5 MHz for the transverse mode and of 2 to 10 MHz for the longitudinal mode. For all the eight independent modes the ultrasonic velocities are found to increase with increasing frequency, implying that bone is viscoelastic even at these high frequencies.

Attenuation and dispersion of ultrasound in cancellous bone, J. E. Barger, SP525, pp. 197-201 (Apr. 1979).

Key words: attenuation; dispersion; skull bone; sound speed; ultrasound.

Measurements of the insertion loss and insertion phase shift for ultrasound transmitted through sections of cancellous bone from human skull are reported as functions of frequency over the range extending from 0.3 MHz to 3.0 MHz. The frequency dependence of insertion loss and of phase speed are both found to be caused principally by scattering of sound by the blood and fat filled interstices in the bone matrix. Independent scattering measurements made at all observation angles confirm the scattering phenomenon. It is concluded that both the high attenuation and the significant dispersion at frequencies above about 1 MHz will limit the ability to characterize brain tissue by its backscatter at these high frequencies. Also, most reported sound speeds in cancellous bone have been calculated from the time-of-flight of broad-band pulses, and are therefore group speeds. These group speeds will exceed the phase speeds by about 15 percent in magnitude.

Transkull transmission of axisymmetric focused ultrasonic beams in the 0.5 to 1 MHz frequency range: Implications for brain tissue visualization, interrogation, and therapy, F. J. Fry, SP525, pp. 203-208 (Apr. 1979).

Key words: axisymmetric; beams; focal thermal flaw; skull transmission; ultrasound.

can

In order for ultrasound to become a practical clinical technique for diagnosis of many intracerebral diseases in the adult human, it has been necessary to answer questions concerning insertion loss of skull, temporal and spatial characteristics of beams operating in the 0.5 to 1.0 MHz range (the requisite frequency is a function of the particular adult skull) have a maximum single pass skull insertion loss of nearly 10 dB (20 dB for a pulse echo system) which be handled with present techniques to provide adequate signal strength from normal and pathological features of brain. In this frequency range, for skulls in our studies, the appropriately selected frequency is unchanged after double pass skull transmission, the 6 dB beam width is increased by a maximum of 40 percent and the beam focus is shifted laterally by a maximum of 3 mm. Resolution of string targets or live brain targets has been demonstrated to be in the 2 to 3 mm range at 1 MHz and at 0.5 MHz it appears that 4 to 6 mm resolution can be achieved. A high intensity focused ultrasonic beam (1 MHz) has been transmitted through an excised adult skull and used to produce a focal thermal flaw in lucite. This simulation test indicates that the induction of transkull focal lesions in live adult brain may now be possible.

Some advances in acoustic imaging through skull, S. W. Smith, D. J. Phillips, O. T. von Ramm, and F. L. Thurstone, SP525, pp. 209-218 (Apr. 1979).

Key words: brain scanning; echoencephalography; neurology; phase compensation.

Previous attempts to image the adult brain through the skull using diagnostic ultrasound have resulted in images of poor lateral resolution and limited dynamic range. The skull can be modeled as an acoustic lens whose attenuation increases rapidly above the 1 MHz and whose thickness variations introduce phase aberrations on the order of several wavelengths across the transducer aperture. Statistical analysis of skull thickness data indicate that an electronic sector scanner using a 1 MHz linear array transducer is less sensitive to these effects of the skull than traditional pulse echo systems operating at higher frequencies. Representative ultrasound tomograms of the brain are shown. In addition, water tank experiments are described in which the skull phase aberration, ♣ (x), was measured on line and removed by incorporating a compensating phase variation, — (x), into the transmit and receive timing of a digitally controlled real time phased array imaging system. Preliminary results show that the lateral resolution of the imaging system is restored in both the transmit and receive modes.

Characterization of in vivo breast tissue by ultrasonic timeof-flight computer tomography, G. H. Glover, SP525, pp. 221-225 (Apr. 1979).

Key words: breast cancer; computerized tomography; mammography; time-of-flight; tissue characterization; ultrasonic imaging; ultrasound.

The use of ultrasonic time-of-flight (TOF) computed tomography for characterization of tissue in live breasts is reported. Quantitative distributions of the refractive index within a tomogram of the specimen were obtained by reconstruction from 5 MHz TOF projection data. Fifteen breast cancer patients and five asymptomatic volunteers were scanned during the clinical feasibility study. The results indicate that young, dense breasts have wide variation in the refractive index distributions. In older subjects, however, various lesions are found to have distinctive indices. Histograms of the reconstructions show differences between pathological and normal breasts.

Variation of acoustic speed with temperature in various excised human tissues studied by ultrasound computerized tomography, B. Rajagopalan, J. F. Greenleaf, P. J. Thomas, S. A. Johnson, and R. C. Bahn, SP525, pp. 227-233 (Apr. 1979).

Key words: aperture synthesis; computed tomography; Doppler; fluid flow; high resolution; reconstruction; temperature reconstruction; ultrasound.

Variation of acoustic speed as a function of temperature was measured in fresh excised human liver, psoas muscle, spleen, spinal cord, kidney and fat, parenchyma and muscles associated with female breasts. Tissues were encased in rubber finger cots and suspended in a temperature controlled bath. A prototype clinical ultrasound breast scanner was used to obtain data required to reconstruct distributions of acoustic speed within two-dimensional planes through the tissue specimens over a temperature range of 20 to 40 °C. Quantitative images (printer listings of acoustic speed) of 64 × 64 pixels were used to obtain averages of up to 16 speed measurements within the image of each tissue. The acoustic speed in most tissues increased monotonically with temperature following the behavior of water. Acoustic speed of fat showed an anomalous decrease in acoustic speed around 34 °C suggesting possible phase transition.

High spatial resolution ultrasonic measurement techniques for characterization of static and moving tissues, S. A. Johnson, J. F. Greenleaf, B. Rajagopalan, R. C. Bahn, B. Baxter, and D. Christensen, SP525, pp. 235-246 (Apr. 1979).

Key words: aperture synthesis; computed tomography; Doppler; fluid flow; high resolution; reconstruction; temperature reconstruction; ultrasound.

Clinical and pathology-based arguments are presented for the need for higher resolution ultrasound images. The theoretical foundation and experimental characteristics of a high resolution, sampled aperture, reflection technique termed "synthetic focus" imaging are given. It is shown by theory and simulation that such synthetic focus images may be corrected for attenuation and refraction effects and thereby approach one-half wavelength resolution. The similarity between synthetic focus and seismic migration techniques is discussed. An example of a high resolution, seismic processed (i.e., migrated) image obtained from real data at medical ultrasound frequencies is shown. Synthetic focus imaging theory is extended to moving coordinate systems and the effect of Doppler shift effects on echo pulse shape is discussed. A generalized wide aperture Doppler imaging theory is presented which suggests further improvements in signal-to-noise ratio, spatial resolution and flow velocity over narrow aperture systems is possible. A new computed tomographic flow measurement and reconstruction technique based on transmission measurements is presented. This technique permits imaging the three flow velocity components and temperature of homogeneous fluids in a three-dimensional domain.

A comprehensive ultrasonic tissue analysis system, M. Linzer, S. I. Parks, S. J. Norton, F. P. Higgins, D. R. Dietz, R. W. Shideler, T. H. Shawker, and J. L. Doppman, SP525, pp. 255-259 (Apr. 1979).

Key words: annular array; breast cancer; chirp signals; imaging; opto-acoustic; pulse compression; sensitivity; signal averaging; signal processing; tissue characterization; tomography; transducers; ultrasonics.

A progress report on the development of a comprehensive system for ultrasonic tissue characterization is presented. Major elements of the program include computerized tomography studies, particularly for breast cancer detection; opto-acoustic visualization of ultrasonic fields, for testing of new imaging schemes, studies of propagation through inhomogeneous media, in vitro measurements, and transducer calibration; electronic focusing, especially annular array imaging; sensitivity enhancement, using digital signal averaging and pulse compression techniques; computer and chirp waveform techniques for compensation of frequency-dependent attenuation; the SonoChromascope, a digital device for real-time acquisition, processing, and display of B-scan images; and computer-based image processing.

Theoretical analysis of instantaneous power spectra as applied to spectra-color ultrasonography, W. D. Jennings, E. Holasek, and E. W. Purnell, SP525, pp. 261-266 (Apr. 1979).

Key words: instantaneous power spectra; color-coded Bscan; spectra-color ultrasonography (SCU); spectrum analysis; ultrasonic spectroscopy.

Spectra-color ultrasonography (SCU), a technique for two-dimensional (B-mode) display of ultrasonic spectral data, has been analyzed theoretically. The analysis includes the use of an instantaneous power spectrum calculated

from broadband gated echo spectra produced by an analog spectrum analyzer. The results of the analysis indicate that additional signal processing factors must be added to the SCU system as it was originally designed. With the inclusion of these modifications, the SCU scan represents a true low resolution instantaneous spectral analysis of ultrasonic echo waveforms. An experiment was performed to test the theoretical equations we have developed relating SCU to an instantaneous spectral analysis. The comparison of the SCU signals and the computed SCU equivalent based on an instantaneous power spectrum is presented.

Identification of tissue parameters by digital processing of real-time ultrasonic clinical cardiac data, L. Joynt, D. Boyle, H. Rakowski, R. Popp, and W. Beaver, SP525, pp. 267-273 (Apr. 1979).

Key words: clinical cardiac data; digital processing; Fast Fourier Transform; frequency spectra; in vivo; microprocessor-controlled data acquisition; myocardial infarction; real-time; tissue characterization; ultrasound diagnosis.

A study to assess the feasibility of obtaining diagnostically useful tissue characterization information by digitally processing clinical cardiac data is described. Normal subjects, myocardial infarction, IHSS, and amyloid patients were studied. The data acquisition system used to record data from a real-time scanner is also described. Significant changes in the RF signals and frequency spectra as the heart moves were noted over very short time intervals, indicating the need for a dynamic tissue characterization measure. Wide variation in the spectral characteristics of the signals from the normal population were found. Behavior of the spectra for the MI patient data were noted wich differentiated them from the other subjects.

Dynamic autocorrelation analysis of A-scans in vivo, J. C. Gore, S. Leeman, C. Metreweli, N. J. Plessner, and K. Willson, SP525, pp. 275-280 (Apr. 1979).

Key words: A-scan; correlation analysis; temporal changes.

A realistic tissue model has been analysed to indicate the information that may be derived from autocorrelation studies of in vivo A-scan echograms, as well as to show some of the limitations of such techniques. Although many of these difficulties are not easily overcome when considering single, or even averaged, realisations of the autocorrelation function (ACF), an analysis of the time course of the ACF is less subject to such objections.

Several potentially useful clinical applications of such temporal changes are being investigated. These include measurements of echoes from within heart muscle throughout the cardiac cycle as a possible indicator of cardiac disease; similar variations in echoes from the stomach wall during gastric emptying are demonstrated, and a relationship to contractile state is postulated.

Results are also presented which indicate that the perfusion of tissues with blood may be assessed by this technique, and, on a different physiological time scale, changes in the placenta throughout pregnancy have been investigated. The technique is being extended to the study of the response of malignant tumours to treatment. Computer spectral analysis of ultrasonic A mode echoes, D. E. Robinson, SP525, pp. 281-286 (Apr. 1979).

Key words: acoustic; computer processing; digital acquisition; digital signal processing; pulse-echo techniques; spectrum analysis; ultrasonics.

Tissue

attenuation as a function of frequency measured by the effect on the power density spectrum of the echo off glass shadowed by the tissue sample is shown to give results comparable to those published previously. A method of measuring attenuation within tissue by comparison of the scattered echoes from shallow and deep scatterers is investigated and shown to have limitations. An assessment of properties of the scatterers from investigation of the spectral properties of the echoes from a scattering region is suggested.

Cepstral signal processing for tissue signature analysis, J. Fraser, G. S. Kino, and J. Birnholz, SP525, pp. 287-295 (Apr. 1979).

Key words: attenuation; B-scan; cepstrum; computer; convolution; de-convolution; liver; power spectrum; signal processing; tissue characterization; tissue parameters; ultrasound.

The reflected signal received by an ultrasonic transducer is modeled as a convolution of a transducer response with a reflection function for the target region. Cepstral analysis translates that signal into a domain where those components interact additively rather than through convolution and where separation can be accomplished with simple bandpass filtering operations. The cepstral transform of the pulse echo signal also provides direct access to any periodic behavior of reflectors arising from their spacing. As an example of these capabilities, the technique is used experimentally to describe the characteristic spacing of macrostructural reflecting elements in the pig liver in vitro and to determine the frequency dependent attenuation behavior of normal human liver in vivo.

Recognition of patterns in ultrasonic sectional pictures of the prostate for tumor diagnosis, W. von Seelen, A. Gaca, E. Loch, W. Scheiding, and G. Wessels, SP525, pp. 297-302 (Apr. 1979).

Key words: pattern recognition; prostate tumors; ultrasound.

We examined the prostate with ultrasonics to diagnose tumorous alterations of the organ. We scanned directly from the abdominal wall through the filled bladder (transvesical). The research is aimed at: 1) improvement and mathematical preparation of the ultrasonic pictures to assist the physician in his diagnosis; and 2) ascertainment of significant parameters which allow the classes "normal prostate," "adenoma" and "carcinoma" to be distinguished in screening examinations. The results show that with ultrasonics, adenomas and carcinomas are recognizable in 96 percent of the examined patients and can be differentiated from normal prostate tissue. The palpation finding was used as a reference in most cases.

Recent developments in obtaining histopathological information from ultrasound tissue signatures, K. Preston, Jr., M. J. Czerwinski, M. L. Skolnik, and D. E. Leb, SP525, pp. 303313 (Apr. 1979).

Key words: picture processing; signal analysis; ultrasound.

Statistical, signal-analytic techniques may be applied to ultrasonic pulse-echoes received from organs of the human body. Simultaneous tissue biopsies of these organs may be sectioned, stained, and measured by the computerized optical microscope using various image-analytic techniques. This paper reports some preliminary work along these lines as related to the kidney and liver.

Damage and death in tissues and associated changes in their mechanical properties, L. Weiss, SP525, pp. 317-322 (Apr. 1979).

Key words: cell detachment; mechanical properties; tissue damage; tissue death.

Mechanical effects of tissue damage associated with artefactual change during examination, and that developing naturally during tumor development, have been demonstrated by a quantitated cell detachment test. Although the precise relationship between this semi-destructive test of tissue properties and ultrasonic, nondestructive tests is uncertain, it appears feasible to consider the following points in studies of the interaction of ultrasound with tissue specimens: a) thin specimens should be examined quickly to avoid anoxic and hypoxic damage; b) note must be made of the heterogeneities within solid tumors, particularly those produced by necrosis; c) degenerative changes in a tumor and surrounding non-malignant tissues may act as image-enhancers.

A human abdominal tissue phantom, P. D. Edmonds, Z. Reyes, D. B. Parkinson, R. A. Filly, and H. Busey, SPS25, pp. 323-326 (Apr. 1979).

Key words: gelatin; human abdominal tissues; phantom.

The objective of this work was to determine the feasibility of constructing a phantom that would simulate human abdominal tissues when interrogated by advanced B-scan diagnostic ultrasound equipment operating 2.25 and 3.5 MHz. Satisfactory results were obtained with gelatin based components having dispersed scatterers and embedded sponge, plastic tubes and rubber bulbs filled with saline solution. Stability of the gelatin was achieved by addition of a stabilizing agent, a preservative and impervious coatings to prevent water evaporation.

Tissue simulators for diagnostic ultrasound, R. C. Eggleton and J. A. Whitcomb, SP525, pp. 327-336 (Apr. 1979).

Key words: tissue signature; tissue simulators; training phantoms; ultrasonic phantoms.

Factors are presented related to the design, construction and use of phantoms to replace human patients or subjects in the development, testing, clinical training and promotion of ultrasonic diagnostic equipment. Materials are described which match the acoustic properties of tissue. Realistic echograms can be obtained by scanning properly configured phantoms using such materials.

The phantoms may be simple geometric test patterns, sections of human torso or complete human torsos simulating dynamic cardiovascular and respiratory movements to evaluate the real-time systems.

Tissue equivalent test objects for comparison of ultrasound transmission tomography by reconstruction with pulse echo ultrasound imaging, P. L. Carson, L. Shabason, D. E. Dick, and W. Clayman, SP525, pp. 337-340 (Apr. 1979).

Key words: computed tomography-ultrasonic; diagnosis-ultrasonic; tissue equivalent test objects and phantoms; ultrasonic tissue characterization; ultrasound imaging.

Tissue equivalent materials have been investigated for evaluation and comparison of pulse echo ultrasound imaging and ultrasound transmission tomography by reconstruction (UTTR). Investigations have centered primarily on various urethane polymers and 3M Reston Brand Flotation Pad material. Attenuation coefficients of the urethane polymers still are somewhat too high, and thus initial test

objects or "phantoms" have been constructed from the flotation pad material. One phantom chosen to simulate several characteristics of human breast tissue consists of an annulus of unaltered flotation pad material surrounding a center region in which scattering polystyrene microspheres are embedded. Contrasting material such as polyethylene rods can be inserted between the inner and outer areas of the phantom. The UTTR technique clearly delineates polyethelene rods in the phantom as small as .6 mm in diameter. The scattering at 2.2 to 3.5 MHz nominal frequency exhibits a pulse echo appearance, similar to that of liver tissue, and causes only approximately a 5 percent increase in the attenuation coefficient of the pure flotation pad material.

Data of the velocity and attenuation of ultrasound in mammalian tissues-A survey, R. J. Parry and R. C. Chivers, SP525, pp. 343-360 (Apr. 1979).

Key words: attenuation; mammalian tissues; ultrasound; velocity.

A compilation of the reported values of velocity and attenuation of ultrasound in mammalian tissues is presented to give a clear picture of the state of knowledge and enable it to be assessed. In the twenty years since the last such compilation, the progress in estimating the relative contributions of the animal species, tissue condition, temperature and frequency at which measurements were made and the method of measurement to the observed variation has been small. It is hoped that this compilation will both be of practical use and also encourage the establishment of a stronger body of fundamental information for the application of ultrasound in medicine and biology.

SP527. Footwear technology symposium-Manufacturing a competitive advantage. Proceedings of the Footwear Technology Symposium held at the National Bureau of Standards, Gaithersburg, MD, June 1-2, 1978, M. H. King, Ed., Nat. Bur. Stand. (U.S.), Spec. Publ. 527, 348 pages (Feb. 1979) SN003-003-02025-7.

Key words: computer-aided design and manufacture (CAD/CAM); footwear industry; fragmented industries; government-industry cooperation; imports; innovation; leather; manufacturing technology; materials development; shoes; technology transfer.

The Footwear Technology Symposium, hosted by the National Bureau of Standards, was held in Gaithersburg, Maryland on June 1 and 2, 1978. Approximately 220 people participated representing the manufacturing, supplier and retailing segments of the footwear industry, as well as federal officials concerned with assistance to the industry. The objective of this symposium was to assess manufacturing technologies which could be adapted or developed to provide a competitive advantage for the U.S. footwear industry, and to develop a specific plan for activities that would be appropriate for government and industry cooperation. The meeting was part of a three-year Department of Commerce Program to help restore the growth and vitality of the domestic footwear industry. Initial sessions presented technical and evaluative information as an input to the subsequent working group discussions of footwear industry representatives. Government staff described the results of their assessment of the problems and opportunities of the industry. To stimulate constructive dialogue, five private research organizations presented ideas and recommendations for future footwear technological development resulting from Commerce Department sponsored studies. The major new technologies and processes presented addressed materials development, leather technologies, customfitting and computer assistance in shoe

design and manufacture (CAD/CAM). In other presentations, the President of the American Footwear Industry Association shared his concerns, a leading footwear designer explored design, marketing and the technology interfaces, and representatives of technologically advanced industries, (aerospace, automobiles, communications) shared their views on manufacturing technologies and applications to footwear industry problems. Preliminary symposium results were evidence of in

dustry enthusiasm and support for government-industry

cooperative activities, interest in establishing a footwear center to provide industry-wide technical assistance, and a desire to assess computer-aided design and manufacture (CAD/CAM). Reports by the consulting firms on new technologies and business strategies for the footwear industry are included as appendices. These proceedings include the following papers (indented):

Manufacturing a competitive advantage, J. Baruch, SP527, pp. 3-6 (Feb. 1979).

General accounting office perspective, F. Haynes, SP527, pp. 7-10 (Feb. 1979).

Fitting technology into the picture, M. King, SP527, pp. 1320 (Feb. 1979).

Technology reviews, A. D. Little, SP527, pp. 21-50 (Feb.

1979).

The potential of new technology, F. Daley, SP527, pp. 5159 (Feb. 1979).

A matter of trust, S. Harman, SP527, pp. 73-77 (Feb. 1979).

Industry response, R. M. Ansin, SP527, pp. 79-80 (Feb. 1979).

Industry view, F. A. Meister, SP527, pp. 83-86 (Feb. 1979).

Relating technologies to the marketplace, B. Levine, SP527, pp. 87-91 (Feb. 1979).

Symposium integration and future directions, J. Baruch, SP527, pp. 95-97 (Feb. 1979).

SP532. Report of the 63d National Conference on Weights and Measures 1978, H. F. Wollin, L. E. Barbrow, and A. P. Heffernan, Nat. Bur. Stand. (U.S.), Spec. Publ. 532, 323 pages (Feb. 1979) SN003-003-02045-1.

Key words: consumer affairs; education; electromagnetic interference; electronic devices; International Organization of Legal Metrology; measurement assurance; metrication; model laws and regulations; national type approval; packaging and labeling; specifications and tolerances; vapor recovery; weights and measures.

This is a report of the proceedings (edited) of the Sixty-Third National Conference on Weights and Measures, sponsored by the National Bureau of Standards, held in Washington, DC, July 9-14, 1978, and attended by State, county, and city weights and measures officials, and representatives of the Federal Government, business, industry, and consumer organizations.

Major issues discussed at this Conference included metric conversion in the United States; problems relating to the quantity fill, labeling, and inspection of packaged commodities; requirements covering the design and performance of new weighing and measuring technology; and recommendations for improvement in weights and measures administration. These proceedings include the following papers (indented):

Electromagnetic interference—A problem of growing concern, C. K. S. Miller, SP532, pp. 1-12 (Feb. 1979).

A practical approach to the EMI-RFI problem in the field, F. L. Platt, SP532, pp. 13-16 (Feb. 1979).

Laboratory metrology—Its goals and needs, R. C. Egnew, SP532, pp. 17-19 (Feb. 1979).

National Food Processors Association solid content weight labeling program, A. W. Matthys, SP532, pp. 20-23 (Feb. 1979).

An industry perspective on packaging regulations, R. W. Miller, SP532, pp. 24-28 (Feb. 1979).

Measurements in the United Kingdom market place, F. L. N. Samuels, SP532, pp. 29-41 (Feb. 1979).

Food labeling-The next step, E. Williams, SP532, pp. 4247 (Feb. 1979).

Measurement assurance—The future of legal metrology, A. O. McCoubrey, SP532, pp. 48-54 (Feb. 1979).

Experience in program evaluation, D. Guensler, SP532, pp. 55-58 (Feb. 1979).

Cost-benefit performance auditing—A tool for weights and measures program improvement, C. H. Vincent, SP532, pp. 59-60 (Feb. 1979).

Cost-benefit performance auditing—A tool for weights and measures program improvement, R. Lockridge, SP532, pp. 61-65 (Feb. 1979).

Application of quantity of contents requirements to packaged seafoods, I. D. Sackett, Jr., SP532, pp. 66-71 (Feb. 1979).

Pressure measurement—A new activity for weights and measures, C. R. Tilford, SP532, pp. 72-77 (Feb. 1979).

Net weight assurance—A responsibility for both government and industry, S. J. Butler, SP532, pp. 118-124 (Feb. 1979). SP534. Utility and use of large-scale mathematical models. Proceedings of a Workshop held at the National Bureau of Standards, Gaithersburg, MD, Apr. 28-29, 1977, S. I. Gass, Ed., Nat. Bur. Stand. (U.S.), Spec. Publ. 534, 217 pages (May 1979) SN003-003-02060-5.

Key words: documentation; energy; evaluation; guidelines; implementation; large-scale; management; mathematical models; policy analysis; software; standards; transfer.

The Workshop on the Utility and Use of Large-Scale Mathematical Models, held at the National Bureau of Standards, Gaithersburg, Maryland (Apr. 28-29, 1977), was a "first" in its purpose: to examine the problem of how to improve the use and utility of large-scale mathematical models in the Federal Government. The Workshop speakers addressed specific problem areas of concern, including: the present status of model use in DOD and non-DOD applications; issues facing developers; problems of model implementation; transfer and development in the energy field; model assessment and evaluation; use in analysis; comparison of models; management of the modeling process; model software and documentation; guidelines, standards and management improvement activities. This proceedings volume presents the papers and much of the discussion presented at the Workshop, along with a summary of directions for needed research. These proceedings include the following papers (indented):