Ruler Measurements Research Articles

Instrument-induced measurement errors during strabismus surgery

Purpose: The purpose of this study was to determine the clinical setting where errors in measurements of muscle position during strabismus surgery made by the Scott curved ruler or by calipers become important and to characterize the magnitude of those errors. Methods: Geometric analysis was used to determine the measurement error between true arc lengths of 3.0 to 20.0 mm versus Scott curved ruler measurements and caliper measurements for axial lengths ranging from 18 to 30 mm. Results: For measurements less than 9.0 mm, neither the Scott curved ruler nor calipers had any clinically important measurement error for any axial length. For axial lengths substantially smaller than 21 mm or larger than 24 mm, the Scott curved ruler, although more accurate than calipers, caused clinically important measurement errors with arc length measurements as small as 12 mm in very small eyes and 14 mm in large eyes. For axial lengths of 30 mm or more, both calipers and the Scott curved ruler had similar accuracy for measuring long arc lengths. Conclusions: Both the Scott curved ruler and calipers are accurate in measuring arc lengths 9.0 mm or less. For longer arc length measurements, accuracy becomes dependent on axial length. The Scott curved ruler, although substantially more accurate than calipers for most common axial lengths, can introduce clinically important measurement errors when measuring arc lengths as small as 12 mm. Axial length should be considered when measuring muscle position during strabismus surgery. (J AAPOS 1999;3:18-25)

The prediction of saleable meat yield in lamb carcasses

A total of 281 lamb carcasses covering three weight groups (18–22.9, 23–25.9 and 26–30 kg) and fatness (< 3 mm, 3–5 mm and > 5 mm) were used to determine the usefulness of several carcass measurements for predicting saleable meat yield. Carcasses were measured for fat and muscle depth, 3–4 cm from the mid-line between the 10th and 11th ribs, 12th and 13th ribs and immediately adjacent to the 13th rib using a Hennessey Grading Probe. This technique also determined total tissue depth at 11 cm from the mid-line between the 10th and 11th and 12th and 13th ribs. The depth of tissues over the 12th rib 11 cm from the mid-line was measured with a ruler. Carcasses were also visually assessed for muscle development (conformation score) on a 5-point scale (1 = thinly fleshed; 5 = thickly fleshed). All carcasses were fabricated into primal cuts which were trimmed to 5 mm of fat and deboned to provide an estimate of saleable meat yield. Ewe lamb carcasses had a higher proportion of kidney fat than wethers in all weight and fat groups (which ranged from 2.6 to 17.9 g kg−1 carcass weight). Saleable meat yield decreased as carcasses became fatter, whereas weight group had little influence on saleable meat yield within a fat group. Ewe lamb carcasses had lower saleable meat yields than wether lamb carcasses, mainly because of their higher amounts of kidney fat. A ruler measurement of tissue depth over the 12th rib combined with carcass conformation score provided the most precise prediction (R2 = 0 61; RSD 17.1) of saleable meat yield. It was concluded that a simple manual system based on these two measurements provided an adequate prediction of saleable meat yield. The accuracy of the procedure would be increased by excluding kidney fat from carcass weight for the prediction of saleable meat yield. Key words: Lamb, carcass, composition, probe, fat, grade

Ultrasound evaluation of cervical shortening after loop excision of the transformation zone (LETZ)

To assess cervical shortening after loop excision of the transformation zone (LETZ), and confirm the validity of ultrasound measurement of cervical length. Subjects (n = 29) were patients at the colposcopy clinic of Beth Israel Hospital who underwent vaginal ultrasound measurement of cervical length before and after LETZ. The pathologic specimen was measured by ruler. Mean cervical length (+/- S.D.), mean percentage (+/- S.D.) of cervical length removed, and correlation (r) between ultrasound and pathology specimen measurement were determined. Mean (+/- S.D.) cervical length measurements prior to LETZ were 3.2 +/- 0.9 cm and after LETZ were 2.6 +/- 0.9 cm, with a difference of 0.7 +/- 0.4 cm. The pathologic specimen (mean +/- S.D.) was 0.6 +/- 0.3 cm. The correlation between ultrasound and pathology measurement was r = 0.9 (p = 0.0001). Mean (+/- S.D.) cervical length was shortened by 22 +/- 12%. There is excellent correlation between ultrasound and ruler measurement of the cervix. There is significant cervical length shortening after LETZ, but further study is needed to see whether this persists or leads to pregnancy complications.

Alternative pork carcass evaluation techniques: II. Statistical analysis of error attributable to sex, genotype, and weight.

Carcasses of 154 hogs representing seven genotypes with substantial variation in carcass composition and percentage of lean were completely dissected and analyzed. Measurements from a ruler, Hennessy probe, and electromagnetic scanner were each used to predict wholesale and lean boneless carcass value. Error, defined as dissected value minus predicted value, due to the omission of sex, genotype, weight, and their interactions was estimated for each model. The errors were significantly different from zero for the models using ruler and electromagnetic scanning measurements separately (P < .01). Errors due to sex, genotype, weight, and their interactions were greatest for the less lean barrows. A combination of probe and electromagnetic scanner measurements resulted in the least error. The value of barrows with low percentage of lean was consistently overpredicted, whereas the value of leaner gilts was underpredicted for the models using ruler and electromagnetic scanning separately (P < .001).

Leaf growth responses to ABA are temperature dependent

The robustness of a leaf elongation bioassay was evaluated by conducting trials with detached shoots of wheat at several different temperatures. Leaf elongation rate (LER) was monitored for shoots fed either an artificial xylem solution or xylem solution plus 10 -3 mol m -3 abscisic acid (ABA). Consistent results were obtained when periodic ruler measurements of many shoots were made and compared with simultaneous measurements on a single shoot made with a linearly variable displacement transducer (LVDT). ABA treatment consistently inhibited leaf growth; however, the magnitude of the inhibition was dependent on the temperature at which the assay was conducted

Prediction of lean yield in cull sows

Data from 204 sows were used to predict percentage carcass lean yield and lean weight. Backfat thickness (probe fat) and muscle depth (probe lean) were measured with an electronic probe. Fat thickness was also measured by ruler at the midline at maximum fat depth over the lumbar vertebrae (maximum fat), fat depth at the last rib (last-rib fat), and fat depth between the 3rd- and 4th-last ribs (fat depth 3–4). Fat depth over maximum loin-muscle depth (loin fat 1), maximum fat depth over loin muscle (loin fat 2), maximum loin depth (loin lean 1) and maximum loin width (loin lean 2) were measured on loin cross section. On the warm carcass, the prediction accuracy of percentage lean yield was highest for probe fat (R2 = 0.77), whereas probe lean had the lowest coefficient of determination (R2 = 0.01). Among the ruler measurements, maximum fat was associated with the most accurate prediction of percentage lean yield (R2 = 0.71). Among cross-section measurements, loin fat 2 was the most accurate predictor of percentage lean yield (R2 = 0.78). For predicting lean weight in the carcass, carcass weight gave the highest coefficient of determination (R2 = 0.82) of any single measurement, but addition of probe fat to the equation improved R2 by 11% and reduced the RSD from 3.16 to 2.00. A single measurement by probe (probe fat) or ruler (maximum fat) was concluded to be sufficient to accurately predict percentage lean yield in sow carcasses. Key words: Lean yield, sows, prediction, carcass composition, grading

Cool Temparature Effects on Cotton Fiber Initiation and Elongation Clarified Using In Vitro Cultures

An understanding of the mechanistic basis of adverse environmental effects on cotton fiber development is a prerequisite to future improvement through genetic engineering and aids in field management to minimize such adverse effects. In order to clarify previous results from field studies on the effects of cool temperatures on initiation, early elongation, and later elongation of cotton fibers, cotton ovules (Gossypium hirsutum L.) cultured in vitro were used as a manipulable and reproducible experimental system based on previous evidence that they provide a valid model. Culture temperature varied from a control of 34 °C constant to 34/15 °C cycling (12/12 h) to mimic a typical diurnal temperature cycle. Fiber initiation and early elongation were analyzed by scanning electron microscopy, and the progress of later elongation was determined by ruler measurements. The results demonstrated that fiber initiation and early elongation (up to about 0.5‐mm length) were independently delayed by cycling cool temperatures, but that later elongation preceded in a temperature‐independent manner. The early delay in fiber development caused by cycling cool temperatures was associated with a longer elongation period during which fibers could attain the control length. Therefore, the results suggest that there are three stages of fiber elongation as distinguished by different temperature responses: initiation, early elongation, and later elongation to attain the genetically determined potential. Consequently, the field temperature during fiber initiation and early elongation may have a profound effect on the final fiber length attained in a limited growing season.

Commentary: Changes to our health service. Is there a cost to the infertile patient? A survey of general practitioners

Assessment of cervical status is an important component of the management of patients at risk for preterm delivery. Although digital examination is the most common method of cervical assessment, there has been recent interest in sonographic cervical examination. To compare the accuracy of digital examination and ultrasound, 20 nongravid women undergoing total hysterectomy for gynecologic indications had measurements of cervical length performed digitally and with both transabdominal and transvaginal ultrasound before surgery. These measurements were then compared with measurements made with a ruler immediately after hysterectomy. Separate examiners performed the digital, ultrasound, and ruler measurements, and each was blinded to the results of the others. Digital examination underestimated cervical length by an average of 13.6 mm and was significantly shorter than ruler measurement (P = .0001). Neither ultrasound method differed significantly from ruler measurement (P greater than .9 for each), and measurements were similar between the sonographic techniques (P greater than .9). These results validate the accuracy of sonographic estimation of cervical length. In addition, they suggest that sonographic measurement is more accurate than digital examination in predicting true cervical length. Finally, in the nonpregnant women, neither ultrasound technique seems superior to the other.

Empirical derivation of bathymetric resolution.

Two properties can be used to define the accuracy of a bathymetric sonar system: (1) the system’s response to the seafloor, which determines lateral resolution, and (2) the system noise, or spurious addition of a high-wave-number component, which determines vertical resolution. The methodologies presented here attempt to quantitatively characterize these properties using only the bathymetric data, independent of theoretical predictions of system resolution. One method of analysis, useful for characterizing system response, is to compare co-registered data of differing quality, with the highest resolution data serving as the measure against which other systems are judged. Comparison techniques include the use of ruler measures, covariance functions, and power spectra that allow for the investigation of the size of features measured as a function of scale. Another method of analysis seeks to quantify noise characteristics by isolating the contribution of noise to the bathymetric autocovariance function. This yields both the rms noise height and the noise correlation distance, the former an estimate of the vertical resolution of the system and the latter providing information regarding the spatial/temporal persistence of noise spikes.

Quantitative comparison of bathymetric survey systems

Spatially coincident Deep‐Tow, Sea Beam, and SeaMARC II bathymetric data are statistically analyzed to determine the scales at which each system is reliable for mapping seafloor features. The methods we employ, including ruler measures of contours and profiles, and the covariance function and power spectrum of profiles, allow us to investigate the size of features measured as a function of scale.

Declarative, Conceptual, and Procedural Knowledge in the Understanding of Fractions and Acquisition of Ruler Measurement Skills

AbstractThis study examined the relationship among declarative, conceptual, and procedural knowledge in the acquisition of ruler measurement skills. Sixth-grade industrial arts students were taught how to use a ruler with one of two instructional methods; the fractional method was based on an understanding of fractions, whereas the line identification method required no understanding of fractions. Results indicated that the line identification method was superior overall to the fractional method, both for the initial acquisition as well as retention of skills. This superiority occurred for questions measuring understanding of fractions but not for ruler skills, indicating that students were able to use procedural knowledge to infer conceptual knowledge. Results are discussed in terms of several models of learning that address how declarative, conceptual, and procedural knowledge interact in the learning process.

EVALUATION OF THE DESTRON PG-100 ELECTRONIC PROBE FOR GRADING WARM PORK CARCASSES

The Destron PG-100 electronic grading probe was evaluated for prediction of lean yield, comparison with the ruler measurement, and precision on 204 pork carcasses representing equal numbers of barrows and gilts and a warm carcass weight range of 56.8–111.4 kg. A complete cutout was done on the left side from each carcass to determine a regression equation for prediction of lean yield from the probe measurements of thickness of fat and muscle between the 3rd and 4th last rib, 7 cm off the mid-line. The Hennessy probe was used as the standard for this study. Both probes performed equally well when compared with the ruler measurement and in their ability to predict lean yield. Key words: Electronic grading, pork carcasses, pork grading

Use of the Hennessy Grading Probe (GP) for predicting the meat, fat and bone yields of beef carcasses

Left sides of 36 bulls, 22 cows, 57 steers and 38 heifer carcasses were weighed hot (HCWL) and were probed with the Hennessy Grading Probe (HGP) at five sites to give four subcutaneous fat depths, two M. longissimus dorsi depths and one total tissue depth measurement. A fat depth (GR) over the 10th rib was also measured by ruler probe. The left sides were later separated by knife into saleable eat (90% visual lean), fat trim and bone. Probe readings of subcutaneous fat thickness at the fatter rump sites (BF, 5–7 cm lateral to the perianal region over the M. biceps femoris; SC8, 8 cm lateral to the prominence of the sacral crest) were smaller than ruler measurements at the same sites. Probe eye muscle depth measurements were smaller than measurements taken at the same site by ruler. The BF measurement taken by probe, combined with HCWL, gave the best prediction of percentage fat trim (RSD = 2·0% for steers and 2·2% for heifers) and edible meat yield (RSD = 2·0% for steers and 2·6% for heifers) in the left sides of all the measurements studied, either singly or in combination. A major problem was to find a measurement site where subcutaneous fat was not removed from some carcasses during hide removal.

Reliability of a Noninvasive Method for Measuring the Lumbar Curve

The purposes of this paper were to describe a clinically useful and noninvasive method of characterizing the shape of the lumbar spine and to evaluate the reliability and validity of this measurement technique. A flexible ruler was applied to the skin over the lumbar spines of 23 normal adults and an angle in degrees between two spinous processes (L 1 -S2) was calculated. lntratester test-retest reliability was good (ICC = 0.97, N = 89) for two separate measures of two spinal postures. The validity of the flexible ruler measurements was also good when compared to two different measurement techniques from a limited number of patient roentgenographs. The flexible ruler was determined to be a reliable and valid measurement technique for the shape of the lumbar spine and may prove helpful in quantifying lumbar postures and the effectiveness of clinical treatments designed to affect lumbar postures. J Orthop Sports Phys Ther 1986;8(4):180-184.

Predicting the fatness of lamb carcasses from carcass wall thickness measured by ruler or by a total depth indicator (TDI) probe

In a trial involving 38 carcasses, a ruler measurement (M5) of carcass wall thickness taken between the 11th and 12th ribs, 11 cm from the mid-line, was as closely related to the chemical fat content of lamb carcasses as other measurements (GR, C) considered for use in carcass classification/grading systems. A trial on 55 lamb carcasses showed the Hennessy and Chong Total Depth Indicator (TDI) was a satisfactory probe to take the M5 measurement on intact carcasses immediately following slaughter. Additional trials are needed to establish whether the TDI can be used at the rate lamb carcasses can be presented off the slaughter chain (6–8 per min) and whether the instrument is sufficiently robust for constant slaughterhouse use.

Ruler vs. the Apple II/FIRST system analysis of analog signals in classical conditioning

In our judgment, the Apple II/FIRST system (Scandrett & Gormezano, 1980) is an efficient and versatile system for experimental control and data acquisition in classical conditioning experiments. However, these attributes would be of limited value if the system did not extract measures from our analog signals with a high degree of correspondence with our ruler measurement procedures. Accordingly, we determined the system’s validity in extracting measures of CR occurrence and CR latency in three conditioning experiments. Pearson productmoment correlation coefficients indicated a very satisfactory degree of agreement on measurements made by the Apple II/FIRST system and ruler. Moreover, intraclass correlations and analysis of variance procedures applied to percent CRs and CR latency revealed several small, but divergent, differences between ruler and computer measurement of CR latency across the three experiments. However, subsequent analyses of variance revealed that the number and pattern of significant sources of variation for ruler or computer measurements were virtually identical. Accordingly, we have concluded that our system can successfully replace our traditional method of ruler measurement.

THE ACCURACY OF TWO RECORDING INSTRUMENTS IN THE MEASUREMENT OF SUBCUTANEOUS FAT THICKNESS IN PORK CARCASSES

The Hennessy and Chong Fat Depth Indicator (FDI) and a compact, ultrasonic instrument (Renco) were compared using 152 pork carcasses. Fat thickness measurements were taken 5 cm off the midline at five locations (shoulder, SF; mid-back, MB; last rib, LR; loin, LO; and lumbar, LU) on both sides of the carcass immediately after sticking (before scalding), after splitting the carcass and 24 h postslaughter (FDI only). Actual thicknesses were determined, using a ruler, for these locations on the left side and at the midline of the split carcass. Instrument readings made on the right or left side of the carcass were not different (P &gt; 0.05). Precision (similarity of first and repeated reading of fat thickness) was higher for the FDI than the Renco with average residual standard deviations for both instruments being 1.2 mm and 1.4 mm, respectively. Precision was similar for all locations except the SF site which had significantly (P &lt; 0.05) poorer values. The average bias was smaller for the FDI than for Renco, but was not large for either instrument except at the shoulder. However, regressions of instrument readings on ruler measurements for both instruments gave slopes that were considerably lower (P &lt; 0.05) than unity with positive values for intercepts. This indicates that fat thickness would be over- and under predicted in lean and fat carcasses, respectively, using both instruments. Key words: Swine, carcass backfat, ultrasonic, fat probes

THE MEASUREMENT OF SUBCUTANEOUS FAT THICKNESS IN COLD BEEF CARCASSES WITH AN AUTOMATIC PROBE

Left sides from 360 cold beef carcasses were probed at the 11th rib site for fat thickness at three positions (1/4, 1/2 and 3/4 positions). Each probe measurement was repeated and the fat thickness at the three sites was then measured using a ruler. Comparison of probe readings with ruler measures showed that the probe consistantly overpredicted fat thickness by margins ranging from 3 to 8 mm (P &lt; 0.001). Regression of probe readings on ruler measures showed that only in the 1/4 position was the slope not different (P &gt; 0.05) from unity. Regression of the first probe reading on the repeated reading also showed that the slope for the 1/4 position was not different (P &gt; 0.05) from unity. Key words: Beef, carcass grading, fat thickness, FDI

Compatibility of Canadian snowfall and snow cover data

The accuracy and compatibility of Canadian snowfall and snow survey data were investigated in the Cold Creek research basin in southern Ontario. Problems in obtaining compatible point measurements of snowfall precipitation from gauge and ruler measurements are discussed. However, it is shown that correction of gauge measurements (MSC Nipher, Universal, Fischer and Porter) of snowfall water equivalent for catch variations caused by environmental factors, notably wind speed, results in compatible storm or seasonal totals. Accurate statistics of basin snow cover were determined from snow courses specifically sited in relation to basin land use. At the time of peak accumulation, which might occur at any time during the winter, there was a statistically significant difference in snow cover between land use categories. Mean basin snow cover was calculated by weighting the snow survey measurements in proportion to basin land use. The need to consider the effect of changing land use on snow course measurements is demonstrated. Results show that as an alternative to direct snow survey measurements, accumulated precipitation may be used to estimate snow cover up to peak accumulation. Net snow cover determined from accumulated corrected gauge data less short‐term melt losses and snow evaporation was within the confidence limits of the basin mean snow cover measured during the winter. Compatible results are only achieved when precipitation measurements are corrected for gauge catch variations and snow survey data are representative of basin land use.

ULTRASONIC MEASUREMENTS OF BACKFAT THICKNESS AT DIFFERENT LOCATIONS AND POSITIONS ON THE WARM PORK CARCASS AND COMPARISONS OF RULER AND ULTRASONIC PROCEDURES

Two hundred and fifty-six warm pork carcasses selected on the rail in a commercial abattoir were utilized to evaluate differences in backfat thickness at various anatomical locations and positions as measured with an ultrasonic device and to compare the ultrasonic measurements taken along the mid-line with the corresponding ruler measurements. Ultrasonic backfat measurements were made at the mid-line, and 2.5 and 5.0 cm off the mid-line over the last rib and at four positions posterior and five positions anterior to the last rib at 5-cm intervals. Ruler measurements of backfat thickness were only taken at the same 10 mid-line positions as the ultrasonic measurements. Areas of minimal variation in dorsal fat thickness were identified. The correlation between ruler and ultrasonic measures varied from 0.82 to 0.93 depending on the position, with the ultrasonic value consistently lower than the corresponding ruler value. The relationship between backfat thickness and warm carcass weight was positive and linear.