Shape Index Values Research Articles

Using the Dugdale approximation to match a specific interaction in the adhesive contact of elastic objects

In the Maugis–Dugdale model of the adhesive contact of elastic spheres, the step cohesive stress σ 0 is arbitrarily chosen to be the theoretical stress σ th to match that of the Lennard-Jones potential. An alternative and more reasonable model is proposed in this paper. The Maugis model is first extended to that of arbitrary axisymmetric elastic objects with an arbitrary surface adhesive interaction and then applied to the case of a power-law shape function and a step cohesive stress. A continuous transition is found in the extended Maugis–Dugdale model for an arbitrary shape index n. A three-dimensional Johnson–Greenwood adhesion map is constructed. A relation of the identical pull-off force at the rigid limit is required for the approximate and exact models. With this requirement, the stress σ 0 is found to be k ( n ) Δ γ / z 0 , where k ( n ) is a coefficient, Δ γ the work of adhesion, and z 0 the equilibrium separation. Hence we have σ 0 ≐ 0.588 Δ γ / z 0 , especially for n = 2 . The prediction of the pull-off forces using this new value shows surprisingly better agreement with the Muller–Yushchenko–Derjaguin transition than that using σ th ≐ 1.026 Δ γ / z 0 , and this is true for other values of shape index n.

Measuring egg size using digital photography: testing Hoyt's method using Florida Scrub-Jay eggs

Egg volumes are most often estimated using a mathematical model that incorporates length and width measurements and a species-specific shape variable. Although adequate in many respects, this technique does not account for intraspecific variation in egg shape. We developed a computer-automated technique that uses calibrated digital photographs to render precise measurements of several egg-size parameters including length, width, volume, and surface area. The system extracts egg outlines from photographs, and divides each egg into latitudinal slices that are subsequently regarded as simple geometric shapes (cylinders or cone frustra) with volumes and surface areas that can be summed to generate size parameters for the entire egg. We tested this technique using 491 eggs from Florida Scrub-Jay (Aphelocoma coerulescens) nests and compared the resulting egg volumes with volumes calculated using the preeminent method of estimating volume from linear measurements. Our method was highly accurate, and differences between the volumes from our method and the alternative method were strongly associated with variation in egg shape. Advantages of our technique include decreased handling of eggs and increased accuracy. Software resources and additional information regarding the technique are available at http://www.archbold-station.org/abs/data/birddata/Bridge-JFO-eggsize.htm. SINOPSIS. Medidas de huevos utilizando fotograf´ ia digital: poniendo a pruebas el m´ etodo

3D free-form object recognition in range images using local surface patches

This paper introduces an integrated local surface descriptor for surface representation and 3D object recognition. A local surface descriptor is characterized by its centroid, its local surface type and a 2D histogram. The 2D histogram shows the frequency of occurrence of shape index values vs. the angles between the normal of reference feature point and that of its neighbors. Instead of calculating local surface descriptors for all the 3D surface points, they are calculated only for feature points that are in areas with large shape variation. In order to speed up the retrieval of surface descriptors and to deal with a large set of objects, the local surface patches of models are indexed into a hash table. Given a set of test local surface patches, votes are cast for models containing similar surface descriptors. Based on potential corresponding local surface patches candidate models are hypothesized. Verification is performed by running the Iterative Closest Point (ICP) algorithm to align models with the test data for the most likely models occurring in a scene. Experimental results with real range data are presented to demonstrate and compare the effectiveness and efficiency of the proposed approach with the spin image and the spherical spin image representations.

Egg Quality Traits of Layers Influenced by Supplementation of Different Levels of Sugarcane Press Residue

4 Abstract: Nearly three percent of the crushed sugarcane from sugar industries turns into Sugarcane Press Residue (SPR), which is a valuable source of minerals as well as organic matter. A biological experiment was conducted using 160 (32-week old) white leg horn hens to assess the beneficial effect of Sugarcane Press Residue (SPR) in soya and fish based diets. Two BIS (1992) specified practical control diets for both soya (T ) and fish based (T ) test diets were formulated, while the SPR was included at three levels (5%, 10% 1 5 and 15%) in test diets of both soya based (T to T ) and fish based (T to T ) types to form a total of eight 2 4 6 8 treatment diets. Each of such formulated diets was offered to five replicates of four birds each reared in colony cages for a period of twelve weeks. Among the egg characteristics studied, the 84 day mean egg weights were found to be 54.70, 53.58, 52.46, 54.69, 54.09, 54.22, 53.21 and 52.62 g in T through T groups, 1 8 respectively. Inclusion of SPR inconsistently (p>0.05) reduced the egg weights when compared to control groups both in soya and fish based diets. Average egg shape index values ranged from 76.30 (T ) to 78.16 1 (T ). Mean albumen index values were comparable. Mean Haugh unit score values ranged (p>0.05) from 7 52.17 (T ) to 56.49 (T ). From the different egg parameters studied, it can be concluded that SPR appears 1 8 to be a valuable source of organic as well as inorganic nutrients for economical layer production.

Some egg and hatching traits of local ducks, Turkish Pekins and Muscovy ducks in Isparta/Turkey (short communication)

Abstract. The purpose of the research was to study some egg and hatching traits of Boz, Yeşilbaş, Kara ducks (as the local names) in comparison with Turkish Pekin and Muscovy ducks in intensive conditions in Isparta province of Turkey. Average egg weights of Boz, Yeşilbaş, Kara, Turkish Pekin, Black Muscovy, Black-white Muscovy, White Muscovy ducks were 68.6, 71.5, 71.0, 71.5, 73.3, 76.3, 75.5g; average percentages of fertility were 70.2, 73.0, 54.2, 78.5, 63.4, 33.5, 64.5 %, respectively. Black-white Muscovy ducks had the highest egg weight. Minor differences were found in the values of egg shape index and values of fertility. The percentage of hatchability of fertile eggs and embryo mortality did not differ among genotypes. The weight of day-old bird there were significant differences between the genotypes. A high weight reached Black-White Muscovy ducks with 46.2 g and the lowest weight were found in Boz genotype with 41.7 g. The results were discussed.

Development of a Novel Computer-Aided Diagnosis System for Automatic Discrimination of Malignant From Benign Solitary Pulmonary Nodules on Thin-Section Dynamic Computed Tomography

As an application of the computer-aided diagnosis of solitary pulmonary nodules (SPNs), 3-dimensional contrast-enhanced (CE) dynamic helical computed tomography (HCT) was performed to evaluate temporal changes in the internal structure of nodules to differentiate between benign nodules (BNs) and malignant nodules (MNs). There were 62 SPNs (35 MNs and 27 BNs) included in this study. Scanning (2-mm collimation) was performed before and 2 and 4 minutes after CE dynamic HCT. The CT data were sent to a computer, and the pixels inside the nodule were characterized in terms of 3 parameters (attenuation, shape index, and curvedness value). Based on the CT data at 4 (MN: 1.81-27.1, BN: -42.8 to -3.29) minutes after CE-dynamic HCT, a score of 0 or higher can be assumed to indicate an MN. Three-dimensional computer-aided diagnosis of the internal structure of SPNs using CE dynamic HCT was found to be effective for differentiating between BNs and MNs.

Virtual Endoscopic Visualization of the Colon by Shape–Scale Signatures

We developed a new visualization method for virtual endoscopic examination of computed tomographic (CT) colonographic data by use of shape-scale analysis. The method provides each colonic structure of interest with a unique color, thereby facilitating rapid diagnosis of the colon. Two shape features, called the local shape index and curvedness, are used for defining the shape-scale spectrum. When we map the shape index and curvedness values within CT colonographic data to the shape-scale spectrum, specific types of colonic structures are represented by unique characteristic signatures in the spectrum. The characteristic signatures of specific types of lesions can be determined by use of computer-simulated lesions or by use of clinical data sets subjected to a computerized detection scheme. The signatures are used for defining a two-dimensional color map by assignment of a unique color to each signature region. The method was evaluated visually by use of computer-simulated lesions and clinical CT colonographic data sets, as well as by an evaluation of the human observer performance in the detection of polyps without and with the use of the color maps. The results indicate that the coloring of the colon yielded by the shape-scale color maps can be used for differentiating among the chosen colonic structures. Moreover, the results indicate that the use of the shape-scale color maps can improve the performance of radiologists in the detection of polyps in CT colonography.

Beat-to-beat measurement of the finger arterial pressure pulse shape index at rest and during exercise.

Arterial pressure waveform can be characterized by the pulse shape index kpulse determined as kpulse = (Pmean - Pdiast) / (Psyst - Pdiast). For brachial artery, the shape index value of 0.33 is usually applied to approximate Pmean from the measured Psyst and Pdiast. Our purpose was to test whether this value can validly be applied to finger vascular beds under different experimental conditions. By using Finapres, we non-invasively estimated the beat-to-beat values of kpulse in the fingers of young healthy persons in supine position at rest and during a 4-min moderate exercise (rhythmical exercise with the quadricep muscles in combination with handgrip compression). To detect intensive peripheral vasoconstrictions, a laser-Doppler probe was attached to the thumb pulp of the same hand. Periods of 30 s without intensive vasoconstriction for rest, different stages of exercise and recovery were involved in the analysis in every subject. The results demonstrated that the group-averaged value of kpulse (median with a 95% confidence interval) in the fingers of 11 healthy volunteers aged from 20 to 24, equalled 0.33 (0.31- 0.34), 0.31 (0.28-0.34), 0.35 (0.33-0.39) and 0.38 (0.34-0.43) for rest, first and second stages of exercise and recovery, respectively. We conclude that in the fingers of young healthy persons in supine position formula Pmean = Pdiast + 1/3 (Psyst - Pdiast) gives an adequate approximation for rest and low intensity exercise (first stage), and slightly underestimates the actual finger mean blood pressure during moderate exercise (second stage) and recovery.

Elongation and Random Orientation of Bovine Endothelial Cells in Response to Hydrostatic Pressure: Comparison with Response to Shear Stress

Morphological responses of cultured bovine endothelial cells (ECs) exposed to hydrostatic pressure were investigated. ECs were exposed to physiological blood pressure under a hydrostatic head of culture medium for 24 hours. Pressured ECs exhibited marked elongation and orientation with the random direction, together with development of centrally located, thick stress fibers. Pressured ECs also exhibited multilayered structure unlike under control conditions. The area and the shape index value significantly decreased after exposure to hydrostatic pressure, which were in good agreement with the results from conventional flow-imposed experiments. In contrast, a tortuosity index, which was newly introduced to represent cell shape tortuosity, significantly increased for pressured ECs, while sheared ECs had no difference in turtuosity index from control. In addition, pressured ECs aligned with no predominant direction, while sheared ECs aligned in the flow direction. These results indicate that ECs can respond very specifically to the type of imposed mechanical stimuli such as hydrostatic pressure and fluid shear stress.

Automated Detection of Polyps with CT Colonography: Evaluation of Volumetric Features for Reduction of False-Positive Findings

Rationale and Objectives To achieve high performance in computer-assisted diagnosis (CAD) of polyps with computed tomographic (CT) colonography, the authors ( a) developed new gradient concentration and directional gradient concentration (DGC) features for differentiating between the true-positive and false-positive (FP) findings generated by the authors' CAD scheme, and ( b) used receiver operating characteristic (ROC) analysis to quantify the differentiation performance of these and other volumetric features. Materials and Methods CT colonography was performed in 43 patients prone and supine with a helical CT scanner; there were 12 polyps in 11 patients. The polyp candidates generated by the authors' CAD scheme were characterized by nine statistics of six volumetric features, and the resulting 54 feature statistics were combined by a linear or quadratic discriminant classifier. The discrimination performance was measured with round-robin method by ROC analysis and the FP rate of the CAD scheme. Results The mean value of shape index (SI) yielded the highest individual ROC performance (area under the curve = 0.92). Among combinations, the mean values of SI and DGC and the variance of CT value yielded a high ROC performance (area under the curve = 0.95). With quadratic classifier, the sensitivity and FP rate of the case–based (data set–based) analysis was 100% (95%) with 2.4 FP findings per patient (1.7 FP findings per data set), respectively. Conclusion Combination of the mean values of SI and DGC and the variance of CT value reduced the FP rate substantially without sacrificing sensitivity. These three features are potentially useful in improving the performance of the authors' CAD scheme for detecting polypswith CT colonography.

Seasonal and physiological aspects of the isolation of tobacco protoplasts

The viability of tobacco (N. tabacum– L. cv. Xanthi‐nc) protoplasts isolated during the winter months is affected by membrane calcium, total calcium, plant age and supplementary lighting. Feeding calcium nitrate and calcium chloride helps to increase protoplast stability. Feeding is important because it increases membrane calcium, but it also has other beneficial effects which may be connected with increased nitrate and chloride (anion) uptake and cation/anion interaction. Whatever optimal feeding regime is chosen, it must be used in conjunction with the correct harvesting practice, which depends on whether or not supplementary light is given. Plants grown without supplementary light are best harvested between 8–9 weeks. If supplementary light is given, older plants (with and without supplementary calcium feeding) of approx. ten weeks are better for protoplast isolation. Plants grown under supplementary light have low leaf shape index (LSI) values (i.e. wider leaves) compared to plants in low light.Spring and summer calcium feeding treatments had no significant effect on increasing total or membrane calcium. Likewise, there was no significant correlation between total/membrane calcium and percentage protoplast viability from days 0–5; and protoplasts isolated from plants grown in shade and fed with calcium salts, were no more stable than protoplasts from control plants. Irrespective of the feed treatments given, spring and summer plants older than about fifty days and grown under shaded and normal light conditions, produced poor protoplasts despite the fact that there was more calcium present in the membranes compared to protoplasts of younger plants. This decrease in percentage protoplast viability appears to be associated with changes in leaf shape. As plants age from 49–63 days, the leaf shape index (LSI) values increase (i.e. leaves are becoming narrower) and % protoplast viability decreases.

Discrimination of particle zonation on a pebble beach

ABSTRACTThe extent to which pebble shapes are zonally sorted on a pebble beach is examined. On the basis of comprehensive point samples from a pebble beach in west Wales, and using factor analysis, a pebble shape index for each point sample is derived. It is proposed that the sum of squares (%RSS) explained by a linear trend surface of shape index values, approximates to the degree to which the second derivative of pebble shape with respect to distance downbeach, tends towards zero. If the second derivative is zero there is no zonation of sample shape values but, rather, a uniform trend. Strength of zonation on one beach is calculated for eight beach samples during 1971. A heterogeneity index (Ht) is introduced to show the degree of difference between clustered point samples on the basis of shape and size. On the basis of %RSS and Ht value, discrimination between pebble facies type on the sample beach over time can be made.