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Abstract Background The bone thickness of the human mandibular ramus is an important parameter in mandibular surgeries. The aim of this study was to systematically measure the bicortical bone thickness, the ramus dimensions and the position of the lingula. The measurements were tested on significant correlations to the patients’ parameters. Methods Based on CBCT scans 150 rami were reconstructed as 3D polygon surfaces. An anatomical grid was adapted to the ramus surface to mark the bone thickness measurement points and to achieve comparability between the measurements on different mandibles. The bone thickness, ramus height, ramus width and the gonion angle were measured. A cluster analysis was performed with these parameters to identify clinically relevant groups with anatomical similarities. Results The median distribution of the bone thickness was calculated and visualized in a pseudo-colour map. The mean ramus height was 44.78 mm, the mean width was 31.31 mm and the mean gonion angle was 124.8°. The average distance from the lingula to the dorsal tangent was 53% of the total width and its distance to the caudal tangent was 65% of the total height. Significant correlations between the bone thickness and the ramus proportions could be identified. Age and sex had no significant influence on the mean bone thickness. The measured rami could be divided into two groups by cluster analysis. Conclusion The dimensions of the human mandibular ramus can be determined from 3D reconstructed surface models from CBCT scans. Measurements could be made comparable by applying an anatomically oriented grid. A cluster analysis allowed the differentiation of two groups with different bone thickness distributions and geometries, which can be used for the optimization of osteosynthesis systems and their precision of adaptation to different ramus morphologies.

Quantification of tropical forest above-ground biomass (AGB) over large areas as input for Reduced Emissions from Deforestation and forest Degradation (REDD+) projects and climate change models is challenging. This is the first study which attempts to estimate AGB and its variability across large areas of tropical lowland forests in Central Kalimantan (Indonesia) through correlating airborne light detection and ranging (LiDAR) to forest inventory data. Two LiDAR height metrics were analysed, and regression models could be improved through the use of LiDAR point densities as input (R2 = 0.88; n = 52). Surveying with a LiDAR point density per square metre of about 4 resulted in the best cost / benefit ratio. We estimated AGB for 600 km of LiDAR tracks and showed that there exists a considerable variability of up to 140% within the same forest type due to varying environmental conditions. Impact from logging operations and the associated AGB losses dating back more than 10 yr could be assessed by LiDAR but not by multispectral satellite imagery. Comparison with a Landsat classification for a 1 million ha study area where AGB values were based on site-specific field inventory data, regional literature estimates, and default values by the Intergovernmental Panel on Climate Change (IPCC) showed an overestimation of 43%, 102%, and 137%, respectively. The results show that AGB overestimation may lead to wrong greenhouse gas (GHG) emission estimates due to deforestation in climate models. For REDD+ projects this leads to inaccurate carbon stock estimates and consequently to significantly wrong REDD+ based compensation payments.

Background: The bone thickness of the human mandibular ramus is an important parameter in mandibular surgeries. The aim of this study was to systematically measure the bicortical bone thickness, the ramus dimensions and the position of the lingula. The measurements were tested on significant correlations to the patients' parameters., Methods: Based on CBCT scans 150 rami were reconstructed as 3D polygon surfaces. An anatomical grid was adapted to the ramus surface to mark the bone thickness measurement points and to achieve comparability between the measurements on different mandibles. The bone thickness, ramus height, ramus width and the gonion angle were measured. A cluster analysis was performed with these parameters to identify clinically relevant groups with anatomical similarities., Results: The median distribution of the bone thickness was calculated and visualized in a pseudo-colour map. The mean ramus height was 44.78 mm, the mean width was 31.31 mm and the mean gonion angle was 124.8°. The average distance from the lingula to the dorsal tangent was 53% of the total width and its distance to the caudal tangent was 65% of the total height. Significant correlations between the bone thickness and the ramus proportions could be identified. Age and sex had no significant influence on the mean bone thickness. The measured rami could be divided into two groups by cluster analysis., Conclusion: The dimensions of the human mandibular ramus can be determined from 3D reconstructed surface models from CBCT scans. Measurements could be made comparable by applying an anatomically oriented grid. A cluster analysis allowed the differentiation of two groups with different bone thickness distributions and geometries, which can be used for the optimization of osteosynthesis systems and their precision of adaptation to different ramus morphologies.