Projection Surface Area Research Articles

Novel patterns for the growing main bronchi in the human fetus: an anatomical, digital and statistical study

PurposeIntensive progress in prenatal medicine results in performing airway management in the fetus affected by life-threatening congenital malformations. This study aimed to examine age-specific reference intervals and growth dynamics for length, proximal and distal external transverse diameters, and projection surface areas of the two main bronchi at varying gestational ages, including their relative growth in length and projection surface area.Materials and methodsUsing anatomical dissection, digital image analysis and statistics, length, proximal and distal external transverse diameters, and projection surface areas of the right and left main bronchi were examined in 73 human fetuses (39 males, 34 females) aged 14–25 weeks, derived from spontaneous abortions and stillbirths.ResultsStatistical analysis showed no sex differences. Between the 14 and 25th week of gestation, the lengths of the right and left main bronchi increased from 1.43 ± 0.18 to 3.18 ± 0.39 mm, and from 2.97 ± 0.16 to 7.58 ± 1.95 mm, in accordance with the functions: y = - 4.850 + 2.452 x ; text{ln}left( {text{Age}} right) pm 0.400;{text{and}};y = - 15.005 + 7.093x ; text{ln} left( {text{Age}} right) pm 0.579 , respectively. The proximal external transverse diameters of the right and left main bronchi varied from 2.13 ± 0.41 to 4.24 ± 0.20 mm, and from 1.84 ± 0.06 to 3.67 ± 0.66 mm, following the logarithmic models: y = - 8.666 + 4.018x ; text{ln}{rm (Age)} pm 0.367;{text{and}};y = - 6.938 + 3.305x{text{ ln(Age) }} pm 0.323 , respectively. The distal external transverse diameter rose from 2.09 ± 0.47 to 4.24 ± 0.20 mm, as y = - 8.723 + 4.021x{text{ ln(Age)}} pm 0.392 for the right main bronchus, and from 1.85 ± 0.04 to 3.67 ± 0.66 mm, like y = - 6.924 + 3.280x{text{ ln(Age)}} pm 0.348 for the left one. On either side, there were no statistically significant differences between values of the proximal and distal transverse diameters of the main bronchus. The projection surface areas of the right and left main bronchi ranged from 2.95 ± 0.19 to 13.34 ± 2.12 mm2, and from 5.57 ± 0.21 to 28.52 ± 5.24 mm2, as y = - 10.212 + 0.943x{text{ Age}} pm 1.739 and y = - 19.119 + 1.875x{text{ Age}} pm 3.054 . The two main bronchi revealed a proportionate increase in both length and projection surface area, since the right-to-left bronchial length ratio and the right-to-left bronchial projection surface area ratio were stable, 0.41 ± 0.07 and 0.47 ± 0.08, respectively, throughout the analyzed period.ConclusionsThe main bronchi show no sex differences. The right and left main bronchi grow logarithmically in length and external transverse diameter, and linearly in projection surface area. The right and left main bronchi evolve proportionately, with the right-to-left bronchial ratios of 0.41 ± 0.07 for length, and 0.47 ± 0.08 for projection surface area.

Influence of screw diameter and number on reduction loss after plating of distal radius fractures

The current options for plate-screw combinations in volar locking distal radius plates used for the treatment of distal radius fractures are either plates with a single distal screw row or plates with multiple distal screw rows. Additionally, the screws themselves may have either fixed angle locking or polyaxial locking mechanisms. To date, there is no evidence or consensus regarding the optimal plate-screw combination. The aim of this study was to assess the biomechanical behaviour of different plate-screw combinations with respect to total distal screw number, number of distal screw rows and screw projection surface area of the most distal row. Biomechanical study to assess six different plating configurations in five different volar locking plate models in a Sawbone distal radius fracture model. The specimens were loaded with 800 Newton loads for 2.000 cycles at 1 Hz. After cyclic loading, load-to-failure testing was performed. With cyclical testing, there was a significant and positive correlation between rigidity and a greater projection area of the most distal screws. Dorsal tilting was significantly more pronounced in plate models with a lesser projection area of the most distal screws and a smaller number of distal screws. With load-to-failure testing, there was a significant increase in rigidity with increasing screw projection area of the most distal row and total number of distal screws. Additional distal screw rows in volar locking distal radius plates might not add substantially to resistance against loss of reduction in the post-operative period.

Calculation of the projection area, surface area and volume of canopy by some model crowns

Calculation of the projection area, surface area and volume of canopy by some model crowns

Variation of soil organic carbon estimates in mountain regions: A case study from Southwest China

Soil organic carbon (SOC) is an important soil component of farming systems and plays a key role in terrestrial ecosystems. However, there is a large variation in SOC estimates at both regional and global scales. The widely used soil type method is usually projected using a planimetric approach, and hence SOC estimates vary notably compared to those generated from more rigorous 3-D surfaces describing rugged terrain. In order to improve the accuracy of SOC storage estimates for regions with complex landforms, this paper examined the causes of variability in estimated SOC storage and SOC density in the upper 1 m soil depth based on 798 soil profiles from Southwest China. The study area is a region with rugged terrain, including the Guangxi Zhuang Autonomous Region, and the Guizhou and Yunnan Provinces. Three methods, the soil profile statistics (SPS), the GIS-based planar soil type (GST-2D), and the GIS-based three-dimensional soil type (GST-3D), were applied to estimate SOC storage. Results demonstrate that the GST-3D, which used soil surface area data, was more accurate than the other two methods. The SOC storages estimated by the SPS and the GST-2D methods were lower than the GST-3D mainly due to the underestimation of soil acreage. Of the four geomorphologic units represented in the study area, the complex landforms with slopes greater than 18.2° covered more than 30%. There is a relatively big difference (> 6%) between planimetric projection area and surface area in this region, making the effect of landform on the estimate of SOC an important factor to be considered. However, such thresholds (30% and 18.2°) as terrain descriptor boundaries need to be further verified in other mountainous regions.

Nipple reconstruction in Asian females using banked cartilage graft and modified top hat flap

Nipple reconstruction is usually the final stage of breast reconstruction and there are over 50 articles that describe different techniques. The majority of methods use local soft tissue as local flaps but they face the disadvantage of reduction in nipple projection after the initial two months. This is particularly troublesome in Asian females who may have wider nipples with prominent projection but small areola surface area. We developed a method to correct this problem using cartilage graft harvested during the initial breast reconstruction operation and banked beneath the skin flap. Using the modified ‘top hat’ flap, we found that no excess soft tissue is required to compensate for the reduction. We have used this method in 25 cases of nipple reconstruction and have obtained satisfactory result in projection.

Méthodes d’estimation des surfaces développées de coraux scléractiniaires à l’échelle d’une colonie ou d’un peuplement

Methods to estimate actual surface areas of scleractinian coral at the colony- and community-scale. This study presents an original method for the determination of the actual surface area of Scleractinian corals at colony-scale and at the scale of a whole reef. Firstly, at colony-scale, the technique consists of dipping coral colonies in a liquid paraffin bath and measuring the weight of the coral before and after the dipping. It is based on the relationship between the weight and the surface area of paraffin deposited and allows one to obtain the actual surface area of coral colonies in the laboratory. The main advantages of this method compared to others is that it uses easily obtainable materials and it is adaptable to all colony shapes. It was used on coral colonies representing the six most frequently seen colony shapes on the reefs of the island of Moorea (French Polynesia). It is shown that, within a wide range of sizes of any given shape, the relationship between vertical projection surface area and actual surface area is linear for most of the colony shapes. The shapes tested were: branching ( Synaraea rus), encrusting ( Montipora aequituberculata), massive ( Porites lobata), sub-massive ( Pocillopora verrucosa), mushroom ( Fungia scutaria) and tabular ( Acropora hyacinthus). Conversion indices for each shape (vertical projection surface area versus actual surface area) were determined from this preliminary study. Secondly, to estimate the actual surface area of coral colonies at the scale of the reef for nine different coral communities, the conversion indices determined above were used to convert vertical projection percent cover to actual surface area. Because of differences in shape composition among the studied coral communities, differences between communities in classical planar percentage cover are not proportional to differences observed in actual coral surface area. These results show that actual surface area may provide a more appropriate measure than planar percentage cover for future quantitative studies of coral communities. © 2000 Ifremer/CNRS/IRD/Éditions scientifiques et médicales Elsevier SAS actual surface area / coral colony / coral reef

Leaf Development and Stem Growth of Ash (Fraxinus excelsior) as Affected by Tree Competitive Status

1. Leaf development and stem growth of ash were studied during year 1993, in an experimental area installed in a mixed natural broadleaved stand, where ash trees, aged 20-24 years, formed part of the dominant layer of the stand. Seventeen trees were selected to represent the range of diameter classes and competitive conditions. 2. For each sample tree, stem girth was measured at several heights above the ground, at the beginning and at the end of the growing season, to evaluate stem volume growth. Crown projection surface area before the growing season and tree height growth were used to estimate a foliar volume. Total leaf dry weight of each tree was obtained by collecting leaves in autumn, and total leaf area was obtained from a sample of leaves. 3. To collect leaves without cutting down the trees, tree crowns were wrapped with nets before leaf fall, from a truck equipped with a nacelle mounted on an articulated arm. Leaves were collected as they fell and accumulated in the bottom of the net. 4. Size relationships were established between foliage biomass and stem and crown dimensions (basal area, crown projection area, foliar volume), between leaf area and foliage biomass, and between bole volume increment and basal area. 5. A basic growth equation was established. This equation shows that consideration of bole surface area is essential for understanding the relationship between annual stem volume increment and foliage biomass. 6. Competition between trees was responsible not only for the differences observed in tree dimensions and growth, but also for the differences in foliage efficiency expressed as bole volume increment per unit of foliage biomass.