428,779 research outputs found
Mach Stem Height and Growth Rate Predictions
A new, more accurate prediction of Mach stem height in steady flow is presented. In addition, starting with a regular reflection in the dual-solution domain, the growth rate of the Mach stem from the time it is first formed till it reaches its steady-state height is presented. Comparisons between theory, experiments, and computations are presented for the Mach stem height. The theory for the Mach stem growth rate in both two and three dimensions is compared to computational results. The Mach stem growth theory provides an explanation for why, once formed, a Mach stem is relatively persistent
Species-specific forest variable estimation using non-parametric modeling of multi-spectral photogrammetric point cloud data
The recent development in software for automatic photogrammetric processing of multispectral aerial imagery, and the growing nation-wide availability of Digital Elevation Model (DEM) data, are about to revolutionize data capture for forest management planning in Scandinavia. Using only already available aerial imagery and ALS-assessed DEM data, raster estimates of the forest variables mean tree height, basal area, total stem volume, and species-specific stem volumes were produced and evaluated. The study was conducted at a coniferous hemi-boreal test site in southern Sweden (lat. 58° N, long. 13° E). Digital aerial images from the Zeiss/Intergraph Digital Mapping Camera system were used to produce 3D point-cloud data with spectral information. Metrics were calculated for 696 field plots (10 m radius) from point-cloud data and used in k-MSN to estimate forest variables. For these stands, the tree height ranged from 1.4 to 33.0 m (18.1 m mean), stem volume from 0 to 829 m3 ha-1 (249 m3 ha-1 mean) and basal area from 0 to 62.2 m2 ha-1 (26.1 m2 ha-1 mean), with mean stand size of 2.8 ha. Estimates made using digital aerial images corresponding to the standard acquisition of the Swedish National Land Survey (Lantmäteriet) showed RMSEs (in percent of the surveyed stand mean) of 7.5% for tree height, 11.4% for basal area, 13.2% for total stem volume, 90.6% for pine stem volume, 26.4 for spruce stem volume, and 72.6% for deciduous stem volume. The results imply that photogrammetric matching of digital aerial images has significant potential for operational use in forestry
Investigation of the limits of nanoscale filopodial interactions
Mesenchymal stem cells are sensitive to changes in feature height, order and spacing. We had previously noted that there was an inverse relationship between osteoinductive potential and feature height on 15-, 55- and 90 nm-high titania nanopillars, with 15 nm-high pillars being the most effective substrate at inducing osteogenesis of human mesenchymal stem cells. The osteoinductive effect was somewhat diminished by decreasing the feature height to 8 nm, however, which suggested that there was a cut-off point, potentially associated with a change in cell–nanofeature interactions. To investigate this further, in this study, a scanning electron microscopy/three-dimensional scanning electron microscopy approach was used to examine the interactions between mesenchymal stem cells and the 8 and 15 nm nanopillared surfaces. As expected, the cells adopted a predominantly filopodial mode of interaction with the 15 nm-high pillars. Interestingly, fine nanoscale membrane projections, which we have termed ‘nanopodia,’ were also employed by the cells on the 8 nm pillars, and it seems that this is analogous to the cells ‘clinging on with their fingertips’ to this scale of features
Evaluasi Uji Keturunan Pulai Darat (Alstonia Angustiloba Miq.) Umur Tiga Tahun Di Wonogiri, Jawa Tengah
Evaluation were observed at three years old of Alstonia angustiloba Miq. progeny trial at Wonogiri, Central Java. The experimental design of the trial was laid out in Randomized Complete Block Design consisting of 43 families, 6 replications, 4 tree-plot and spacing of 3 x 3 meters. This study was aimed to observe the adaptability, the growth variation (height, stem diameter and stem volume) and the estimates of heritability, genetic correlation and phenotipic correlation among the three growth traits.The results of study showed that the adaptability was not significantly different between populations and families with survival rate at 80.04 ± 25.34%. Analysis of variance showed that population and families were significantly different for height, stem diameter and stem volume. Pendopo, Carita, and Lubuk Linggau were the best populations in height growth (3.12 – 3.4 m) and stem diameter (4.07 – 4.65 cm). Pendopo population was the best population in stem volume (0.0047 m3). The estimates of individual heritabilities were around 0.32; 0.20, and 0.13 for height, stem diameter and stem volume, respectively. While the family heritabilities were around 0.59; 0.49, and 0.42 for height, stem diameter and stem volume, respectively. Genetic and phenotipic correlation among the three traits were positive and strong at 0.96 and 0.86 for height and diameter, 0.92 and 0.80 for height and stem volume then 0.89 and 0.95 for diameter and stem volume
Developing Allometric Equations for Teak Plantations Located in the Coastal Region of Ecuador from Terrestrial Laser Scanning Data
Traditional studies aimed at developing allometric models to estimate dry above-ground biomass (AGB) and other tree-level variables, such as tree stem commercial volume (TSCV) or tree stem volume (TSV), usually involves cutting down the trees. Although this method has low uncertainty, it is quite costly and inefficient since it requires a very time-consuming field work. In order to assist in data collection and processing, remote sensing is allowing the application of non-destructive sampling methods such as that based on terrestrial laser scanning (TLS). In this work, TLS-derived point clouds were used to digitally reconstruct the tree stem of a set of teak trees (Tectona grandis Linn. F.) from 58 circular reference plots of 18 m radius belonging to three different plantations located in the Coastal Region of Ecuador. After manually selecting the appropriate trees from the entire sample, semi-automatic data processing was performed to provide measurements of TSCV and TSV, together with estimates of AGB values at tree level. These observed values were used to develop allometric models, based on diameter at breast height (DBH), total tree height (h), or the metric DBH2 × h, by applying a robust regression method to remove likely outliers. Results showed that the developed allometric models performed reasonably well, especially those based on the metric DBH2 × h, providing low bias estimates and relative RMSE values of 21.60% and 16.41% for TSCV and TSV, respectively. Allometric models only based on tree height were derived from replacing DBH by h in the expression DBH2 x h, according to adjusted expressions depending on DBH classes (ranges of DBH). This finding can facilitate the obtaining of variables such as AGB (carbon stock) and commercial volume of wood over teak plantations in the Coastal Region of Ecuador from only knowing the tree height, constituting a promising method to address large-scale teak plantations monitoring from the canopy height models derived from digital aerial stereophotogrammetry
Estimasi Parameter Genetik Pada Uji Keturunan Alstonia Scholaris Umur Dua Tahun Di Gunungkidul, YOGYAKARTA
Estimates of genetic parameter were observed at two years old of Alstonia scholaris progeny trial in Gunungkidul, Yogyakarta. The experimental design of the trial was laid out in Randomized Complete Block Design consisting of 48 families, 5 replications, 4 tree-plot and spacing of 4 x 2 meters. This study is aimed to observe the growth variation (height and stem diameter) and the estimates of heritability and genetic correlation among the two growth traits. The results of study showed that the tested families were significantly different for height and stem diameter. The estimate of individual heritability was high at around 0.53 and 0.44 for height and stem diameter, respectively. While the corresponding of family heritability was at around 0.67 and 0.63 for height and stem diameter, respectively. Positive and strong genetic correlation were found between height and stem diameter of this species at two years of age (rg = 0.94)
Pengaruh Seleksi Terhadap Perolehan Genetik Pada Uji Keturunan Generasi Pertama (F-1) Jabon Merah (Anthocephalus Macrophyllus (Roxb.) Havil) Di Wonogiri
Selection is a fundamental process in the establishment of a progeny trial that will be converted into a seedling seed orchard. In present study, selection practiced in first-generation progeny trial of jabon merah (Anthocephalus macrophyllus Roxb. Havil.) was observed. The study was aimed to find out a criteria selection accompanied with the effective coefficient weight for predicting genetic gain in the first-generation progeny trial of jabon merah. The trial was established in Wonogiri which was laid out in randomized complete block design (RCBD) using 55 families, 4 replications, 4 tree-plot with a spacing of 4 x 2 meter. Measurement was conducted at 40 months after planting covering tree height, diameter at breast height, stem straightness, stem volume. First within-plot selection by culling 2 poorer trees within each plot was practiced at 46 months age. Selection differential from within-plot selection was used to derive coefficient weight which was then applied to predict genetic gain. Results of study showed that selection differential from first within-plot selection were positive for all measured traits. Stem volume was observed as highest priority trait with coefficient weight for each trait were -0.0863 (height), 0.1426 (diameter), 0.2195 (stem straightness), 2.3025 (stem volume). Prediction of genetic gain from within-plot selection were 3,50% (height), 3.58% (diamater), 3.41% (stem straightness), 7.40% (stem volume). While the gain from family selection were 2.80%, 3.75%, 3.54%, 7.10% for height, diamater, stem straightness, stem volume, respectively
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