Measurement Of Linear Dimensions Research Articles

The abdominal aortic aneurysm sac after endoluminal exclusion: A medium-term morphologic follow-up based on volumetric technology

Purpose: The purpose of this study was to evaluate the role of three-dimensional spiral computed tomographic angiography (SCTA) for the assessment of the feasibility and results of endoluminal repair of infrarenal abdominal aortic aneurysm.Methods: Laboratory studies: Phantom glass aneurysms, filled with contrast, underwent SCTA. The correlation between SCTA and laboratory measurements of linear dimensions and volumes was highly accurate (r2 = 1.0). Clinical studies: From the first 7 patients that were suitable for endoluminal repair, the correlation between SCTA and angiocatheter measurements was 0.85 to 0.99 (P < .04), but there was poor agreement between individual values. As determined from the measurements by 2 experienced investigators, intraobserver and interobserver errors for volume calculation in 12 randomly chosen scans from a total of 120 scans were 5.7 and 4.4 mL, respectively (range of volumes, 100–403 mL). The conditions of 53 patients were judged suitable for endoluminal repair of which 30 patients reached 1 year or more follow-up. The median aneurysm neck length and diameter were 24.5 mm (range, 11.5–60.8 mm) and 23.4 mm (18.3–31.5 mm), respectively. The fate of the sac after endografting by two techniques (pre-expanded polytetrafluoroethylene [PTFE] fixed with Palmaz stents and endografts) was defined with three-dimensional SCTA.Results: The sac volume after endografting by pre-expanded PTFE (n = 12 patients) showed a significant median increase (P = .02) from 129 mL before surgery to 141 mL at 5 days after the operation with no change at 6 (139 mL), 12 (137 mL), and 18 (159 mL) months later. With the endografts (n = 18), there was an initial increase in median volume at 5 days (179–194 mL; P= .02) and then a significant shrinkage at 6 (148 mL; P = .012) and 12 (94.9 mL; P = .02) months.Conclusion: Three-dimensional SCTA has been validated and is both precise and reliable. Interobserver and intraobserver errors are within acceptable ranges. Angiocatheter measurements are less accurate and may give misleading information when used for patient selection and endograft construction. The sac volume increased after endografting and later shrank in patients who were treated with endografts, but not in those patients treated with pre-expanded PTFE. We propose that three-dimensional SCTA should be regarded as the gold standard for linear and volumetric measurement for infrarenal abdominal aortic aneurysm. (J Vasc Surg 2000;31:490–500)

Increasing the accuracy of gauge-block measurements of linear dimensions

The first stage in increasing the accuracy of measurements of the linear dimensions of precision parts the exact reproduction of a certified gauge block, is investigated. Recommendations are made on the use of a new method to evaluate the increase in the accuracy of evaluation of unmonitored lapping-in and contact deformations during measurements.

Construction and use of an inexpensive "anthropometer".

An inexpensive anthropometer, suitable for use in undergraduate projects, was constructed from aluminum rod and components designed from laboratory retort stands. Only modest workshop skills and widely available machine tools were required to produce the device, which could be used to take accurate and reproducible measurements of linear dimensions and the angles of orientation of body segments. Its use in student projects indicates the value of the angular measurements in investigating posture.

Measurement of linear dimensions of submicron structures with a scanning electron microscope

A scanning electron microscope, operating in conditions of secondary slow-electron collection, was used to measure the dimensions of raised rectangular structures in the form of 90–500 nm slit-like groves in silicon. The average measurement error was 0.5–1%.

Accuracy of in-vivo assessment of prostatic volume by MRI and transrectal ultrasonography.

More accurate noninvasive estimation of prostate size is important in therapeutic trials for benign prostatic hyperplasia. The accuracy of MRI and transrectal ultrasound (TRUS) in assessing prostate weight was evaluated in 48 patients who underwent radical prostatectomy for stage A or B cancer. The volume derived from the wet weight of the freshly excised specimen was used as a reference. We compared that volume with volume estimates derived from the three-axis linear dimension measurement by MRI and TRUS using a tissue density of 1.05 g/cc and the standard formula for an ellipsoid object. Prostate and seminal vesicle volumes were also computed by contouring T2-weighted 5 mm thick contiguous MR images using a semiautomatic edge detection program and pixel summation. Three-axis volume MRI method versus volume from wet weight has slightly less scatter than TRUS three-axis method (r = 0.85 vs r = 0.81). Contoured MR volume method has the least scatter r = 0.93, statistically better than the linear axis method. Contoured MRI volumetric analysis appears superior to linear MRI or TRUS methods in estimating true prostate volume.

Choice of devices for measurement of linear dimensions in the engineering industry and permissible measurement error

Choice of devices for measurement of linear dimensions in the engineering industry and permissible measurement error

Contact errors in precision linear-dimension measurement

Contact errors in precision linear-dimension measurement

Automated measurements of crystal dimensions and concentration of inclusions in ice cores: Methods and first results

This paper describes an experimental set-up for the automated measurement of linear dimensions of crystals in samples of artificial and natural ice. We also show the feasibility of automatic measurements of concentration and dimensions of air inclusions. The theoretical rate of measurements of the above mentioned parameters can reach 1000 per second, corresponding to a travel speed of about 1 m/s when moving the sensors along an ice core. The narrow beam laser optics allow the detection of ice inclusions down to about one micrometer in diameter.

BODY SIZE, SPERM COMPETITION, AND DETERMINANTS OF REPRODUCTIVE SUCCESS IN MALE SAVANNA BABOONS.

One component of sexual selection is sperm competition. It has been reasoned that the intensity of sperm competition may be reflected in the relative testicular sizes of animals. Among males residing in multimale breeding systems, testicular size is relatively larger than among males residing in unimale mating systems. Information on whether differences in testicular size within a species can account for differences in male reproductive success is unavailable for natural populations of primates. A population of six troops of savanna baboons in Kenya was surveyed for morphometric analysis, and one of these troops was the subject of extensive behavioral observations afterwards. Testicular weights could not be obtained, but measurements of linear dimensions were transformed into volumetric estimates. Male weight accounted for 30% of the variance in testicular volume. Neither body size nor testicular volume was associated with differences in male reproductive activity. The outcome of fights over access to females could not be related to male body size, and ejaculatory patterns of males were independent of testicle size. Both sperm competition and aggressive competition intensified during the four-day optimum conception period, but fights over access to consort females were infrequent. Among savanna baboons, the probability of an ejaculation resulting in a conception is fairly low, which may account for the infrequency of injurious fights. Although testicle size influences sperm production, it does not influence either the timing of mating or the fertilizing capacity of spermatozoa, and both of these factors probably account for a substantial fraction of the variance in male baboon paternity. Sperm competition is an adjunct to agonistic competition as a mechanism affecting male baboon reproductive success. It is concluded that male reproductive success in baboons is affected more by social factors than by morphological traits associated with size.

Quantitative approaches to primate morphology.

Quantitative morphometric methods are focused mainly on dental morphology, skull shape, shapes of body segments, body proportions and overall size. In the majority of cases simple measurements of linear dimensions or angles have been used. Only rarely are the possibilities inherent to a quantitative description of shape fully exploited. Nevertheless, the utility of morphometrics for taxonomic studies is now generally accepted, in particular if the measurements provide the data base for multivariate statistics. For an understanding of the selective value of the characters studied, a different kind of quantitative data is necessary. As most of the observed variation is in locomotor and jaw structures, which serve to fulfil mechanical functions, quantitative data from the field of mechanics are required: moments of force, moments of resistance, velocities, accelerations, forces, stresses. Even more important than these empirical data is precise knowledge of the way in which these factors are connected in mathematical equations which describe the mechanical laws governing the animal and its motions. If the basic constraint which directs the phylogenetic development of forms is indeed the saving of energy as is commonly accepted, the mechanical approach will open up a causal understanding of evolution.

Instrumental measurement and control of colour

In spite of the fact that the basic method of colour measurement was established more than harf a centuy ago, it is only during the last fifteen years that the application of colour measurement is particularly substantial and significant because of the advancement of computer technology, better understanding of colour science, and the revolution in equipment design. This has brought colour science from a scientific exercise in the research laboratory to a widely used industrial and commercial tool.The present state of the art of colour measurement is such that an analogy can be made to the measurement of linear dimensions at one time by the relatively crude yardstick, but now replaced by the precisely scaled micrometer. Thus with colour measurement now, colour can be measured with a precision unmatched by the human eye. To‐day, both the colorant industry and colour dependent commerce (industries such as dyes, textiles, pigments, cosmetics, coatings, paper, plastics etc.) are taking advantage of such techniques since the economic advantages are quite substantial. Furthermore, the techniques involved are, to a large extent, no longer trade secrets. The literature abounds with practical theories and concepts which can be applied directly in the workplace by competent colourists. It is expected that more applications of colour measurement for similar general usage are being developed.This paper is designed to introduce the fundamental concept of colour science and various types of colour measuring instruments and their selection. The value of these colour measuring instruments for practical use in industry and commerce is discussed. Finally, the sources of the technical information and assistance are given.

Use of a video-imaging system for estimating leaf surface area of Pinussylvestris seedlings

A method is described for a rapid, nondestructive estimation of the surface area of the shoot system of intact pine seedlings. A video camera and image analyzer were used to quantify the area of a video image of pine seedling shoots. Surface area values were displayed in dimensionless units, referred to as silhouette area. Silhouette area was significantly correlated with several other methods of estimating needle surface area, including dry weight, calculation based on measurement of linear dimensions, volume displacement, and optical planimetry. Correspondence between dry weight, or surface area estimates based on dry weight, and silhouette area was relatively low (r2 &lt; 0.9) but statistically significant. The correlation between shoot area and silhouette area were improved (r2 &gt; 0.9) when shoot area was estimated from volume displacement or optical planimetry.

Contactless linear-dimension measurement with elevated sensitivity and accuracy

Contactless linear-dimension measurement with elevated sensitivity and accuracy

Accuracy in linear-dimension measurement in engineering

Accuracy in linear-dimension measurement in engineering

A device for optical measurement of linear dimensions by means of matrix signal converters

A device for optical measurement of linear dimensions by means of matrix signal converters

An electron-microscope-based system for accurate microdimensional measurements

Calibration measurements of linear dimensions in the range 0.1 to 100 μm are provided by a high-resolution, scanning electron microscope-scanning specimen stage system. Computer-controlled, with a stationary sem electron beam and interferometric measurement of stage position, the system can provide point-to-point measurements accurate to 0.01 μm. It also forms the basis for development and certification of calibrated standards for planar objects, particles, and other microscopic objects and features

Environmental variation in a fossil scleractinian coral

Sample populations of Solenastrea fairbanksi, collected from different environments in the Pliocene Imperial Formation, can be distinguished by measurements of linear dimensions of the coenosteum and thickness of septal structures. In these characters, magnitudes of intercolony variance components are lower than interpopulation or intracolony components, suggesting that the variation is largely caused by environmental factors. Three patterns of mean variation exist between populations: (1) Highest means occur in shallow, offshore (high energy) environments. (2) Highest means occur in shallow environments with low turbidity (high light intensity). (3) Highest means occur in clear, deeper offshore environments (favorable nutrient supply). The distance between adjacent corallites and the inverse of coenosteal porosity follow the first pattern, measures of thickness of vertical corallite structures follow the second, whereas estimates of annual growth rate follow the third. Corallite diameters and columella thicknesses do not vary between populations. Comparisons with modern species show that many characters in S. fairbanksi respond to environmental factors in a manner different from similar characters in other scleractinian species. In fact, some inflexible characters in S. fairbunksi are highly flexible in other species.

Measurement of linear dimensions and displacement by vibrational contact

Measurement of linear dimensions and displacement by vibrational contact

Estimating achievable accuracy in measurement of linear dimensions by contact instruments using method of comparison with rod gauges

Estimating achievable accuracy in measurement of linear dimensions by contact instruments using method of comparison with rod gauges

Choice of means of linear-dimension measurement in terms of error level

Choice of means of linear-dimension measurement in terms of error level