Estimation of Larch Growth at the Stem, Crown and Branch Levels Using Ground-based LiDAR Point Cloud

BackgroundTree growth is an important indicator of forest health and can reflect changes in forest structure. Traditional tree growth estimates use easy-to-measure parameters (e.g., tree height, diameter at breast height (DBH), and crown diameter) obtained via forest in situ measurements, which are labor-intensive and time-consuming to perform and cannot easily describe the changes throughout the whole growth period of a tree. The combination of Terrestrial Laser Scanning (TLS) and Quantitative Structure Modelling (QSM) can accurately estimate tree structural parameters nondestructively and has the potential to estimate tree growth. Therefore, this paper estimates tree growth according to the stem-, crown-, and branch-level attributes observed by ground-based LiDAR point clouds. Compared with conventional methods, this paper used tree height, DBH, stem volume, crown diameter, crown volume and first-order branch volume to estimate the growth of 55-year-old larch trees in Saihanba at the stem, crown and branch levels, respectively. ResultsThe experimental results showed that the absolute growth of the first-order branch volume was equivalent to that of the stems, which highlights the importance of branches in the study of tree growth. For 55-year-old larch, tree growth is mainly reflected in the growth of the crown, i.e., the growth of branches. Compared to one-dimensional parameters (tree height, DBH and crown diameter), the growth of three-dimensional parameters (crown, stem and first-order branch volumes) was more obvious. ConclusionsFor 55-year-old larch, three-dimensional tree parameters can more effectively describe tree growth, and the absolute growth of the first-order branch volume is close to the stem volume. In addition, it is necessary to estimate tree growth at different levels.

Transcriptome analysis of two inflorescence branching mutants reveals cytokinin is an important regulator in controlling inflorescence architecture in the woody plant Jatropha curcas

Background In higher plants, inflorescence architecture is an important agronomic trait directly determining seed yield. However, little information is available on the regulatory mechanism of inflorescence development in perennial woody plants. Based on two inflorescence branching mutants, we investigated the transcriptome differences in inflorescence buds between two mutants and wild-type (WT) plants by RNA-Seq to identify the genes and regulatory networks controlling inflorescence architecture in Jatropha curcas L., a perennial woody plant belonging to Euphorbiaceae. Results Two inflorescence branching mutants were identified in germplasm collection of Jatropha. The duo xiao hua (dxh) mutant has a seven-order branch inflorescence, and the gynoecy (g) mutant has a three-order branch inflorescence, while WT Jatropha has predominantly four-order branch inflorescence, occasionally the three- or five-order branch inflorescences in fields. Using weighted gene correlation network analysis (WGCNA), we identified several hub genes involved in the cytokinin metabolic pathway from modules highly associated with inflorescence phenotypes. Among them, Jatropha ADENOSINE KINASE 2 (JcADK2), ADENINE PHOSPHORIBOSYL TRANSFERASE 1 (JcAPT1), CYTOKININ OXIDASE 3 (JcCKX3), ISOPENTENYLTRANSFERASE 5 (JcIPT5), LONELY GUY 3 (JcLOG3) and JcLOG5 may participate in cytokinin metabolic pathway in Jatropha. Consistently, exogenous application of cytokinin (6-benzyladenine, 6-BA) on inflorescence buds induced high-branch inflorescence phenotype in both low-branch inflorescence mutant (g) and WT plants. These results suggested that cytokinin is an important regulator in controlling inflorescence branching in Jatropha. In addition, comparative transcriptome analysis showed that Arabidopsis homologous genes Jatropha AGAMOUS-LIKE 6 (JcAGL6), JcAGL24, FRUITFUL (JcFUL), LEAFY (JcLFY), SEPALLATAs (JcSEPs), TERMINAL FLOWER 1 (JcTFL1), and WUSCHEL-RELATED HOMEOBOX 3 (JcWOX3), were differentially expressed in inflorescence buds between dxh and g mutants and WT plants, indicating that they may participate in inflorescence development in Jatropha. The expression of JcTFL1 was downregulated, while the expression of JcLFY and JcAP1 were upregulated in inflorescences in low-branch g mutant. Conclusions Cytokinin is an important regulator in controlling inflorescence branching in Jatropha. The regulation of inflorescence architecture by the genes involved in floral development, including TFL1, LFY and AP1, may be conservative in Jatropha and Arabidopsis. Our results provide helpful information for elucidating the regulatory mechanism of inflorescence architecture in Jatropha.

On the evaluation of a general model for optimum revolute cylindrical cylindrical cylindrical path generation

A general optimization model for the dimensional synthesis of defect free revolute cylindrical cylindrical cylindrical (RCCC) joint path generators is formulated, implemented and evaluated in this work. With this optimization model, RCCC dimensions required to approximate precision points are calculated. The model includes constraints to eliminate order, branch and circuit defects, which are common in dyad-based dimensional synthesis. Therefore, the originality of this work is the development of a general optimization model for RCCC path generation that simultaneously considers order, branch, and circuit defect elimination. This work demonstrates both the benefits and drawbacks realized when implementing the optimization model on a personal computer using the commercial mathematical analysis software package Matlab.

Capillary pericytes express α-smooth muscle actin, which requires prevention of filamentous-actin depolymerization for detection

Recent evidence suggests that capillary pericytes are contractile and play a crucial role in the regulation of microcirculation. However, failure to detect components of the contractile apparatus in capillary pericytes, most notably α-smooth muscle actin (α-SMA), has questioned these findings. Using strategies that allow rapid filamentous-actin (F-actin) fixation (i.e. snap freeze fixation with methanol at −20°C) or prevent F-actin depolymerization (i.e. with F-actin stabilizing agents), we demonstrate that pericytes on mouse retinal capillaries, including those in intermediate and deeper plexus, express α-SMA. Junctional pericytes were more frequently α-SMA-positive relative to pericytes on linear capillary segments. Intravitreal administration of short interfering RNA (α-SMA-siRNA) suppressed α-SMA expression preferentially in high order branch capillary pericytes, confirming the existence of a smaller pool of α-SMA in distal capillary pericytes that is quickly lost by depolymerization. We conclude that capillary pericytes do express α-SMA, which rapidly depolymerizes during tissue fixation thus evading detection by immunolabeling.

Revolute-Cylindrical-Cylindrical-Cylindrical linkage optimum dimensional synthesis with static structural loading

General optimization models for the dimensional synthesis of defect-free Revolute-Cylindrical-Cylindrical-Cylindrical linkages with static loading are formulated and evaluated in this work. With these optimization models, Revolute-Cylindrical-Cylindrical-Cylindrical linkage dimensions required to approximate coupler positions or coupler path points while achieving static equilibrium (given coupler loads) within a maximum driver static torque are calculated. These models also include constraints that eliminate order, branch and circuit defects-defects that are common in traditional dyad-based dimensional synthesis. Therefore, the novelty of this work is the development of optimization models that permit the synthesis of order, branch and circuit defect-free Revolute-Cylindrical-Cylindrical-Cylindrical motion and path generators that also achieve static equilibrium within a maximum specified driver torque magnitude for specified coupler loads. This work conveys both the benefits and drawbacks realized when implementing these optimization models on a personal computer using the commercial mathematical analysis software package Matlab.

On RCCC Linkage Motion Generation With Defect Elimination for an Indefinite Number of Precision Positions

A general optimization model for the dimensional synthesis of defect-free revolute-cylindrical-cylindrical-cylindrical joint (or RCCC) motion generators is formulated and demonstrated in this work. With this optimization model, the RCCC dimensions required to approximate an indefinite number of precision positions are calculated. The model includes constraints to eliminate order branch and circuit defects—defects that are common in dyad-based dimensional synthesis. Therefore, the novelty of this work is the development of a general optimization model for RCCC motion generation for an indefinite number of precision positions that simultaneously considers order, branch, and circuit defect elimination. This work conveys both the benefits and drawbacks realized when implementing the optimization model on a personal computer using the commercial mathematical analysis software package matlab.

On Adjustable Planar Four-Bar Motion Generation With Order, Branch and Circuit Defect Rectification

This work is an incremental extension of adjustable planar four-bar kinematic synthesis theory to consider not only synthesis, but also the elimination of the defects inherent in synthesis. A nonlinear equation system for moving pivot-adjustable planar four-bar motion generation that includes constraints for order defect, branch defect and circuit defect elimination is presented in this work. In the objective function of the equation system, the error between the prescribed and achieved precision positions is minimized. The equation system includes inequality constraints to eliminate order defects and branch defects. The equation system also includes a complete planar four-bar displacement model to eliminate circuit defects.

Reconstructing a lost world: Ediacaran rangeomorphs from Spaniard's Bay, Newfoundland

Ediacaran fronds at Spaniard's Bay on the Avalon Peninsula of Newfoundland exhibit exquisite, three-dimensional preservation with morphological features less than 0.05 mm in width visible on the best preserved specimens. Most of the nearly 100 specimens are juvenile rangeomorphs, an extinct Ediacaran clade that numerically dominated the early evolution of complex multicellular life. Spaniard's Bay rangeomorphs are characterized by cm-scale architectural elements exhibiting self-similar branching over several fractal scales that were used as modules in construction of larger structures. Four taxa of rangeomorph fronds are present – Avalofractus abaculus n. gen. et sp., Beothukis mistakensis Brasier and Antcliffe, Trepassia wardae (Narbonne and Gehling), and Charnia cf. C. masoni Ford. All of these taxa exhibit an alternate array of primary rangeomorph branches that pass off a central stalk or furrow that marks the midline of the petalodium. Avalofractus is remarkably self similar over at least four fractal scales, with each scale represented by double-sided rangeomorph elements that were constrained only at their attachment point with the higher-order branch and thus were free to rotate and pivot relative to other branches. Beothukis is similar in organization, but its primary branches show only one side of a typical rangeomorph element, probably due to longitudinal branch folding, and the position of the individual branches was moderately constrained. Trepassia shows only single-sided branches with both primary and secondary branches emanating from a central stalk or furrow; primary branches were capable of minor pivoting as reflected in bundles of secondary branches. Charnia shows only single-sided primary branches that branch from a zigzag central furrow and that were firmly constrained relative to each. This sequence provides a developmental linkage between Rangea-type and Charnia-type rangeomorphs. Avalonian assemblages show a wide array of rangeomorph constructions, but later Ediacaran assemblages contain a lower diversity of rangeomorphs represented mainly by well-constrained forms.