University of Turku

About: University of Turku is a education organization based out in Turku, Finland. It is known for research contribution in the topics: Population & Galaxy. The organization has 16296 authors who have published 45124 publications receiving 1505428 citations. The organization is also known as: Turun yliopisto & Åbo universitet.

International benchmarking of terrestrial laser scanning approaches for forest inventories

Abstract: The last two decades have witnessed increasing awareness of the potential of terrestrial laser scanning (TLS) in forest applications in both public and commercial sectors, along with tremendous research efforts and progress. It is time to inspect the achievements of and the remaining barriers to TLS-based forest investigations, so further research and application are clearly orientated in operational uses of TLS. In such context, the international TLS benchmarking project was launched in 2014 by the European Spatial Data Research Organization and coordinated by the Finnish Geospatial Research Institute. The main objectives of this benchmarking study are to evaluate the potential of applying TLS in characterizing forests, to clarify the strengths and the weaknesses of TLS as a measure of forest digitization, and to reveal the capability of recent algorithms for tree-attribute extraction. The project is designed to benchmark the TLS algorithms by processing identical TLS datasets for a standardized set of forest attribute criteria and by evaluating the results through a common procedure respecting reliable references. Benchmarking results reflect large variances in estimating accuracies, which were unveiled through the 18 compared algorithms and through the evaluation framework, i.e., forest complexity categories, TLS data acquisition approaches, tree attributes and evaluation procedures. The evaluation framework includes three new criteria proposed in this benchmarking and the algorithm performances are investigated through combining two or more criteria (e.g., the accuracy of the individual tree attributes are inspected in conjunction with plot-level completeness) in order to reveal algorithms’ overall performance. The results also reveal some best available forest attribute estimates at this time, which clarify the status quo of TLS-based forest investigations. Some results are well expected, while some are new, e.g., the variances of estimating accuracies between single-/multi-scan, the principle of the algorithm designs and the possibility of a computer outperforming human operation. With single-scan data, i.e., one hemispherical scan per plot, most of the recent algorithms are capable of achieving stem detection with approximately 75% completeness and 90% correctness in the easy forest stands (easy plots: 600 stems/ha, 20 cm mean DBH). The detection rate decreases when the stem density increases and the average DBH decreases, i.e., 60% completeness with 90% correctness (medium plots: 1000 stem/ha, 15 cm mean DBH) and 30% completeness with 90% correctness (difficult plots: 2000 stems/ha, 10 cm mean DBH). The application of the multi-scan approach, i.e., five scans per plot at the center and four quadrant angles, is more effective in complex stands, increasing the completeness to approximately 90% for medium plots and to approximately 70% for difficult plots, with almost 100% correctness. The results of this benchmarking also show that the TLS-based approaches can provide the estimates of the DBH and the stem curve at a 1–2 cm accuracy that are close to what is required in practical applications, e.g., national forest inventories (NFIs). In terms of algorithm development, a high level of automation is a commonly shared standard, but a bottleneck occurs at stem detection and tree height estimation, especially in multilayer and dense forest stands. The greatest challenge is that even with the multi-scan approach, it is still hard to completely and accurately record stems of all trees in a plot due to the occlusion effects of the trees and bushes in forests. Future development must address the redundant yet incomplete point clouds of forest sample plots and recognize trees more accurately and efficiently. It is worth noting that TLS currently provides the best quality terrestrial point clouds in comparison with all other technologies, meaning that all the benchmarks labeled in this paper can also serve as a reference for other terrestrial point clouds sources.

Effects of an antioxidant-rich juice (sea buckthorn) on risk factors for coronary heart disease in humans

Abstract: There is increasing evidence to support the hypothesis that free radical-mediated oxidative processes contribute to atherogenesis. More recently the ability of antioxidant nutrients to affect cell response and gene expression has been reported in vitro, providing a novel mechanistic perspective for the biological activity of antioxidants. Sea buckthorn (Hippophae rhamnoides L.) is a rich source of antioxidants both aqueous and lipophilic, as well as polyunsaturated fatty acids. The objective of the study was to characterize the antioxidant profile of Sea buckthorn juice (SBJ) and to evaluate its effect on plasma lipids, LDL oxidation, platelet aggregation and plasma soluble cell adhesion protein concentration. Twenty healthy male volunteers were given either a placebo or SBJ for 8 weeks. Additional daily intakes of vitamin C, α-tocopherol, β-carotene and flavonoids through SBJ supplementation were 462, 3.2, 1.0 and 355 mg respectively. There were no significant changes in plasma total cholesterol, LDL-C, platelet aggregation or plasma intercellular cell adhesion molecule 1 (ICAM-1) levels between treatment groups. Although not significant, a 20% and 17% increase in plasma HDL-C and triacylglycerol (TAG) concentrations were observed. SBJ supplementation also resulted in a moderate decrease in the susceptibility of LDL to oxidation.

Optimization of cryptic coloration in heterogeneous habitats

Abstract: We present a theoretical approach to the optimization of crypsis in heterogeneous habitats. Our model habitat consists of two different microhabitats, and the optimal combination of crypsis in the microhabitats is supposed to maximize the probability of escaping detection by a predator. The probability of escaping detection for a prey is a function of: (i) degree of crypsis, (ii) probability of occurrence in the microhabitats and (iii) probability of encountering a predator in the microhabitats. Because crypsis is background-specific there is a trade-off between crypsis in two visually different microhabitats. Depending on the nature of the trade-off, the optimal coloration is either a compromise between the requirements of the differing microhabitats or entirely adapted to only one of them. An increased risk of predation in one of the microhabitats favours increased crypsis in that microhabitat. Because the trade-off constrains possible optimal solutions, it is not possible to predict the optimal coloration only from factors (i)–(iii). However, habitat choice may fundamentally change the situation. If minimizing predation risk does not incur any costs, the prey should exclusively prefer the microhabitat where it has a lower probability of encountering a predator and better crypsis. The implications of these results for variation in cryptic coloration and polymorphism are discussed.