Spatial stochastic modeling of resin yield from pine stands

2001 ◽  
Vol 31 (7) ◽  
pp. 1140-1147 ◽  
Author(s):  
Nikos Nanos ◽  
Wubalem Tadesse ◽  
Gregorio Montero ◽  
Luis Gil ◽  
Ricardo Alia
Keyword(s):  
Spatial Structure ◽  
Stochastic Modeling ◽  
Economic Modeling ◽  
Complete Spatial Randomness ◽  
The Mean ◽  
Pine Stands ◽  
K Function ◽  
Modeling Strategy ◽  
Future Work ◽  
Scale Data

The spatial structure of resin-yield in maritime pine stands in central Spain was studied on two different scales and with data from two tapping periods (1998 and 1999). For the fine scale, Moran's I and the K function were used to study within-stand spatial variation. We found that in one plot, trees separated by distances of less than 5 m had similar production. The K function results showed that the distribution of trees did not depart significantly from complete spatial randomness. For a much larger scale, data was available from 37 and 59 ten-tree plots for years 1998 and 1999, respectively. Partial (monthly) yields were also measured. The experimental variograms for the mean plot production showed that a large percentage of the total variance was spatially structured. Furthermore, the experimental variograms for the partial yields revealed changes in the spatial structure of this phenomenon within the same year. Spatial stochastic modeling was shown to be an effective and economic modeling strategy. Temporal variation should be included in future work, with the use of geostatistical space-time models.

scholarly journals A Statistical Test for Ripley’s K Function Rejection of Poisson Null Hypothesis

ISRN Ecology ◽  
2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Eric Marcon ◽  
Stéphane Traissac ◽  
Gabriel Lang
Keyword(s):  
Monte Carlo ◽  
Spatial Structure ◽  
Monte Carlo Simulations ◽  
Tropical Forest ◽  
Null Hypothesis ◽  
Statistical Test ◽  
Forest Plot ◽  
Complete Spatial Randomness ◽  
Point Patterns ◽  
K Function

Ripley’s K function is the classical tool to characterize the spatial structure of point patterns. It is widely used in vegetation studies. Testing its values against a null hypothesis usually relies on Monte-Carlo simulations since little is known about its distribution. We introduce a statistical test against complete spatial randomness (CSR). The test returns the P value to reject the null hypothesis of independence between point locations. It is more rigorous and faster than classical Monte-Carlo simulations. We show how to apply it to a tropical forest plot. The necessary R code is provided.

Estimating Utility Values for Health States of DFU Patients Using EQ-5D-5L and cTTO

2021 ◽  
pp. 153473462110143
Author(s):  
Morteza Arab-Zozani ◽  
Hossein Safari ◽  
Zoha Dori ◽  
Somayeh Afshari ◽  
Hosein Ameri ◽  
...  
Keyword(s):  
Foot Ulcer ◽  
Diabetic Foot Ulcer ◽  
Economic Modeling ◽  
Health State ◽  
Health States ◽  
Utility Values ◽  
The Mean ◽  
The Difference ◽  
Diabetes Center ◽  
Health State Utility Values

Health-state utility values of diabetic foot ulcer (DFU) patients are necessary for clinical praxis and economic modeling. The purpose of this study was to estimate utility values in DFU patients using the EuroQol-5-dimension-5-level (EQ-5D-5L) and composite time trade-off (cTTO). The EQ-5D-5L and cTTO were used for estimating utility values. Data were collected from 228 patients referred to the largest governmental diabetes center in the South of Iran, Yazd province. When appropriate, independent sample t-test or analysis of variance test was used to test the difference in the utility values in each of the demographic and clinical characteristics of the patients. Finally, the BetaMix was used to identify predictors of the utility values. The means of EQ-5D-5L and cTTO values were 0.55( SD 0.21) and 0.67( SD 0.23), respectively. Anxiety and pain were the most common problems reported by the patients. The difference between the mean EQ-5D-5L values was significant for age, grade of ulcer, number of comorbidities, and having complications. In addition, variables of gender, age, grade of ulcer, and having complications were significant predictors of the EQ-5D-5L. The difference between the mean cTTO values was significant for age, employment status, grade of ulcer, number of comorbidities, and having complications. Moreover, variables of gender, age, grade of ulcer, number of comorbidities, and developing complications were significant predictors of cTTO. The current study provided estimates of utility values for DFU patients for clinical praxis and economic modeling. These estimates, similar to utilities reported in other studies, were low. Identifying strategies to decrease anxiety/depression and pain in patients is important to improve the utility values.

Using LiDAR Point Clouds in Determination of the Scots Pine Stands Spatial Structure Meaning in the Conservation of Lichen Communities in “Bory Tucholskie” National Park

2019 ◽  
Vol 31 (1) ◽  
pp. 85-103
Author(s):  
Piotr Wężyk ◽  
Paweł Hawryło ◽  
Marta Szostak ◽  
Karolina Zięba-Kulawik ◽  
Monika Winczek ◽  
...  
Keyword(s):  
Spatial Structure ◽  
National Park ◽  
Laser Scanning ◽  
Ground Level ◽  
Point Clouds ◽  
Organic Layer ◽  
Active Protection ◽  
Scanning Lidar ◽  
Pine Stands ◽  
Biometric Features

Abstract The aim of the research carried out in 2018 and financed by the Forest Fund was the analysis of biometric features and parameters of pine stands in the area of the “Bory Tucholskie” National Park (PNBT), where a program of active protection of lichen was initiated in 2017. Environmental analyses were conducted in relation to selected biometric features of trees and stands using laser scanning (LiDAR), including ULS (Unmanned Laser Scanning; RIEGL VUX-1) and TLS (Terrestrial Laser Scanning; FARO FOCUS 3D; X130). Thanks to the application of LiDAR technology, the structure of pine stands was precisely determined by means of a series of descriptive statistics characterizing the 3D spatial structure of vegetation. Using the Trees Crown Model (CHM), the analysis of the volume of tree crowns and the volume of space under canopy was performed. For the analysed sub-compartments, GIS solar analyses were carried out for the solar energy reaching the canopy and the ground level due to active protection of lichen. Multispectral photos were obtained using a specialized RedEdge-M camera (MicaSense) mounted on the UAV multi rotor platform Typhoon H520 (Yuneec). Flights with a thermal camera were also performed in order to detect places on the ground with high temperature. Plant indices: NDVI, NDRE, GNDVI and GRVI were also calculated for sub-compartments. The data obtained in 2017 and 2018 were the basis for spatial and temporal analyses of 4-D changes in stands which were related to the removal of some trees and organic layer (litter, moss layer).

scholarly journals Population dynamics with spatial structure and an Allee effect

2020 ◽  
Author(s):  
Anudeep Surendran ◽  
Michael Plank ◽  
Matthew Simpson
Keyword(s):  
Population Dynamics ◽  
Spatial Structure ◽  
Short Range ◽  
Allee Effect ◽  
Mean Field ◽  
Mean Field Approximation ◽  
Continuum Approximation ◽  
Spatial Moment ◽  
Mean Field Models ◽  
The Mean

AbstractAllee effects describe populations in which long-term survival is only possible if the population density is above some threshold level. A simple mathematical model of an Allee effect is one where initial densities below the threshold lead to population extinction, whereas initial densities above the threshold eventually asymptote to some positive carrying capacity density. Mean field models of population dynamics neglect spatial structure that can arise through short-range interactions, such as short-range competition and dispersal. The influence of such non mean-field effects has not been studied in the presence of an Allee effect. To address this we develop an individual-based model (IBM) that incorporates both short-range interactions and an Allee effect. To explore the role of spatial structure we derive a mathematically tractable continuum approximation of the IBM in terms of the dynamics of spatial moments. In the limit of long-range interactions where the mean-field approximation holds, our modelling framework accurately recovers the mean-field Allee threshold. We show that the Allee threshold is sensitive to spatial structure that mean-field models neglect. For example, we show that there are cases where the mean-field model predicts extinction but the population actually survives and vice versa. Through simulations we show that our new spatial moment dynamics model accurately captures the modified Allee threshold in the presence of spatial structure.

MMPI-2 Scores of Puerto Rican, Mexican, and U.S. Latino College Students: A Research Note

2000 ◽  
Vol 87 (1) ◽  
pp. 266-268 ◽  
Author(s):  
Jose J. Cabiya ◽  
Denise A. Chavira ◽  
Francisco C. Gomez ◽  
Emilia Lucio ◽  
Jeanett Castellanos ◽  
...  
Keyword(s):  
United States ◽  
College Students ◽  
Puerto Rico ◽  
Standard Deviation ◽  
Puerto Rican ◽  
The United States ◽  
Clinical Scale ◽  
The Mean ◽  
The One ◽  
Scale Data

In this brief report, we present MMPI-2 basic validity and clinical scale data of Latino-descent persons from Puerto Rico ( n = 290), Mexico ( n = 1,920), and the United States ( n = 28). All were administered one of three Spanish translations of the MMPI-2. A review of the mean scores of these respective groups indicates similarities across all scales. Differences among these three groups, with the exception of the Mf scale (which is keyed to sex), were well within the one standard deviation band. More importantly, these findings are promising given the fact that three different translations of the MMPI-2 were applied.

scholarly journals Three-dimensional spatial structure of the macro-pores and flow simulation in anthracite coal based on X-ray μ-CT scanning data

2020 ◽  
Vol 17 (5) ◽  
pp. 1221-1236
Author(s):  
Hui-Huang Fang ◽  
Shu-Xun Sang ◽  
Shi-Qi Liu
Keyword(s):  
Spatial Structure ◽  
Flow Velocity ◽  
Single Channel ◽  
Three Dimensional ◽  
Bedding Plane ◽  
Mean Flow ◽  
Equivalent Radius ◽  
Flow Pressure ◽  
The Mean ◽  
Mean Flow Velocity

Abstract The three-dimensional (3D) structures of pores directly affect the CH4 flow. Therefore, it is very important to analyze the 3D spatial structure of pores and to simulate the CH4 flow with the connected pores as the carrier. The result shows that the equivalent radius of pores and throats are 1–16 μm and 1.03–8.9 μm, respectively, and the throat length is 3.28–231.25 μm. The coordination number of pores concentrates around three, and the intersection point between the connectivity function and the X-axis is 3–4 μm, which indicate the macro-pores have good connectivity. During the single-channel flow, the pressure decreases along the direction of CH4 flow, and the flow velocity of CH4 decreases from the pore center to the wall. Under the dual-channel and the multi-channel flows, the pressure also decreases along the CH4 flow direction, while the velocity increases. The mean flow pressure gradually decreases with the increase of the distance from the inlet slice. The change of mean flow pressure is relatively stable in the direction horizontal to the bedding plane, while it is relatively large in the direction perpendicular to the bedding plane. The mean flow velocity in the direction horizontal to the bedding plane (Y-axis) is the largest, followed by that in the direction horizontal to the bedding plane (X-axis), and the mean flow velocity in the direction perpendicular to the bedding plane is the smallest.

Reduction of mountain pine beetle (Coleoptera: Scolytidae) attacks by verbenone in lodgepole pine stands in British Columbia

1989 ◽  
Vol 19 (1) ◽  
pp. 65-68 ◽  
Author(s):  
B. S. Lindgren ◽  
J. H. Borden ◽  
G. H. Cushon ◽  
L. J. Chong ◽  
C. J. Higgins
Keyword(s):  
British Columbia ◽  
Mountain Pine Beetle ◽  
Lodgepole Pine ◽  
Management Tool ◽  
Mountain Pine ◽  
Pine Beetle ◽  
The Mean ◽  
Pine Stands ◽  
Release Devices

The effect of the aggregation-inhibiting pheromone verbenone on mountain pine beetle attacks in lodgepole pine stands was assessed by affixing verbenone release devices on trees on a 10 × 10 m grid. In one experiment, aggregation to trees baited with an attractive combination of trans-verbenol, exo-brevicomin, and myrcene was reduced in verbenone-treated blocks compared with control blocks (attractive baits only). The mean number of trees with mass attacks (≥31.3 attacks/m2), mean percentage of available trees mass attacked, and mean total number of trees infested were reduced by 74.3, 66.7, and 58.5%, respectively. The ratio of 1987 attacks to 1986 attacks was reduced from 14.0 to 2.6. In a second experiment, using no attractive baits, verbenone caused similar but nonsignificant reductions. The mean number of trees with mass attacks, mean percentage of available trees mass attacked, and mean total number of trees infested were reduced by 75.2, 53.5, and 62.1%, respectively. The 1987 to 1986 attack ratio was reduced from 13.2 in control blocks to 0.2 in the verbenone-treated blocks, and the percentage of trees that were infested but not mass attacked was significantly increased, from 45.7% in the control blocks to 63.2% in the verbenone-treated blocks. We conclude that verbenone shows promise as a management tool for controlling the mountain pine beetle.

Evaluating Oil Spill Risks through Stochastic and Deterministic Trajectory Modeling

2017 ◽  
Vol 2017 (1) ◽  
pp. 2017247
Author(s):  
Keyword(s):  
Stochastic Modeling ◽  
Oil Spill ◽  
Oil And Gas ◽  
Natural Variability ◽  
Potential Consequence ◽  
Oil And Gas Exploration ◽  
Exploration And Production ◽  
Modeling Strategy ◽  
Computational Resources ◽  
Spatially Varying

Oil spill risks associated with oil and gas exploration and production are changing as industry moves to deeper water. Computer-based modeling is typically used to quantify the fate and trajectory of sub sea releases (e.g., well blowouts). Stochastic modeling has become common as computational resources have grown, allowing for a large number of combinations of met ocean parameters to be evaluated. Simulating many potential realizations of a single discharge event allows for the calculation of spatially varying probabilities of oiling due to natural variability in the prevailing wind and current, but this needs to be treated separately from the likelihood of the sub sea release occurring to appropriately evaluate the oil spill risks of the offshore activity. Some industry guidance explicitly recognizes that the likelihood of a discharge event occurring is independent of the natural variability of the environmental setting and correctly treat these items as statistically independent; however, this distinction is sometimes lost in practice. In these instances, the resulting oil spill risk assessments may inadvertently be based on highly improbable combinations of release conditions and met ocean forcing. A transparent and robust risk-based oil spill risk assessment needs to explicitly communicate the differences between the likelihood of a release event occurring and the probabilities of the potential trajectories that could result under different combinations of met ocean parameters. This poster uses a hypothetical deepwater blowout to illustrate how stochastic and deterministic modeling can be combined to characterize the probability distribution associated with the (variable) potential consequence of a discharge event. The proposed modeling strategy allows for the set of trajectories generated by stochastic modeling to be ranked based on various metrics of interest (e.g., volume of water column swept, area of surface slick, or volume of oil ashore) so the distribution of potential consequence can be evaluated. Following recently industry guidance (IPECA-OGP), it is suggested that the most probably deterministic trajectory be paired with statistical analysis, although the strategy allows for an identifiable amount of conservatism to be incorporated into the analyses by selecting one or more other trajectories for detailed impacts assessment.

Self-Assembled TPPS4 Nanostructures Revealed by Atomic Force Microscopy

2004 ◽  
Vol 97-98 ◽  
pp. 191-194 ◽  
Author(s):  
R. Augulis ◽  
Valentinas Snitka ◽  
R. Rotomskis
Keyword(s):  
Atomic Force Microscopy ◽  
Spatial Structure ◽  
Water Soluble ◽  
Silicon Substrates ◽  
Force Microscopy ◽  
Atomic Force ◽  
The Mean ◽  
J Aggregates ◽  
Self Assembled ◽  
Experimental Findings

Meso-tetra (4-sulfonatophenyl) porphine (TPPS4) is water-soluble tetrapyrrolic dye, which forms self assembled nanostructures – J-aggregates under appropriate conditions. It was shown, that such aggregates survive dried on the substrate. The spatial structure of TPPS4 Jaggregates formed in acidic aqueous solutions and dispersed on silicon substrates was analyzed by means of atomic force microscopy (AFM). The stripe-like structures were observed. The size of individual stripes ranged 4,5×40×(200-1000) nm (H×W×L). The width and height was almost the same for all stripes and independent upon the concentration of the solution, however the length was statistically distributed and the mean length increased with increasing concentration of initial TPPS4 solution. At higher concentrations such stripes stacked into thicker fibers containing 2-20 stripes. Such fibers branched and formed large bush-like structures sized up to several millimeters. According to experimental findings the model of mesostructures, formed by TPPS4 J-aggregates, was proposed.

scholarly journals Feasibility and Validation of Real-Time Patient Evaluations of Internal Medicine Interns' Communication and Professionalism Skills

2014 ◽  
Vol 6 (1) ◽  
pp. 71-77 ◽  
Author(s):  
C. Jessica Dine ◽  
Stefanie Ruffolo ◽  
Jennifer Lapin ◽  
Judy A. Shea ◽  
Jennifer R. Kogan
Keyword(s):  
Internal Medicine ◽  
Factor Analysis ◽  
Communication Skills ◽  
Standardized Patient ◽  
Varimax Rotation ◽  
Faculty Evaluations ◽  
Evaluation Systems ◽  
New Information ◽  
The Mean ◽  
Future Work

Abstract Background Residents receive little information about how they interact with patients. Objective This pilot study assessed the feasibility and validity of a new 16-item tool developed to assess patients' perspectives of interns' communication skills and professionalism and the team's communication. Methods Feasibility was determined by the percentage of surveys completed, the average time for survey completion, the percentage of target interns evaluated, and the mean number of evaluations per intern. Generalizability was analyzed using an (evaluator:evaluatee) × item model. Simulated D studies estimated optimal numbers of items and evaluators. Factor analysis with varimax rotation was used to examine the structure of the items. Scores were correlated with other measures of communication and professionalism for validation. Results Most patients (225 of 305 [74%]) completed the evaluation. Each survey took approximately 6.3 minutes to complete. In 43 days over 18 weeks, 45 of 50 interns (90%) were evaluated an average of 4.6 times. Fifty evaluations would be required to reach a minimally acceptable coefficient (0.57). Two factor structures were identified. The evaluation did not correlate with faculty evaluations of resident communication but did correlate weakly (r  =  0.140, P  =  .04) with standardized patient evaluations. Conclusions A large number of patient evaluations are needed to reliably assess intern and team communication skills. Evaluations by patients add a perspective in assessing these skills that is different from those of faculty evaluations. Future work will focus on whether this new information adds to existing evaluation systems and warrants the added effort.

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