Diameter Standard Deviation Research Articles

In Vivo Lamina Cribrosa Micro-Architecture in Healthy and Glaucomatous Eyes as Assessed by Optical Coherence Tomography

The lamina cribrosa (LC) is a prime location of glaucomatous damage. The purpose of this study was to compare LC 3-dimensional micro-architecture between healthy and glaucomatous eyes in vivo by using optical coherence tomography (OCT). Sixty-eight eyes (19 healthy and 49 glaucomatous) from 47 subjects were scanned in a 3.5 × 3.5 × 3.64-mm volume (400 × 400 × 896 pixels) at the optic nerve head by using swept-source OCT. The LC micro-architecture parameters were measured on the visible LC by an automated segmentation algorithm. The LC parameters were compared to diagnosis and visual field mean deviation (VF MD) by using a linear mixed effects model accounting for age. The average VF MD for the healthy and glaucomatous eyes was -0.50 ± 0.80 dB and -7.84 ± 8.75 dB, respectively. Beam thickness to pore diameter ratio (P = 0.04) and pore diameter standard deviation (P < 0.01) were increased in glaucomatous eyes. With worse MD, beam thickness to pore diameter ratio (P < 0.01), pore diameter standard deviation (P = 0.05), and beam thickness (P < 0.01) showed a statistically significant increase while pore diameter (P = 0.02) showed a significant decrease. There were no significant interactions between any of the parameters and age (all P > 0.05). Glaucomatous micro-architecture changes in the LC, detected by OCT analysis, reflect beams remodeling and axonal loss leading to reduction in pore size and increased pore size variability.

Concentrations and Size Distributions of Airborne Particulate Matter and Bacteria in an Experimental Aviary Laying-Hen Chamber

<abstract> <bold><sc>Abstract.</sc></bold> High levels of airborne particulate matter (PM) and bacteria may exist in animal housing, which can be detrimental to the health of animals and workers. The sizes of these bioaerosols determine their aerial transport behaviors and depositions in the respiratory tracts of animals and humans. However, little is known regarding the size distribution of airborne PM and bacteria in livestock houses, especially in alternative animal housing systems that aim to enhance animal welfare, such as aviary hen-housing systems. The study reported here was therefore conducted to characterize the concentrations and size distributions of airborne bacteria (in count) and PM (both in count and in mass) in a pilot-scale aviary laying-hen chamber. Thirty-four laying hens were kept in the environmentally controlled aviary chamber (L × W × H = 2.2 × 2.3 × 2.4 m) for three months. The hens were given a 16L:8D photoperiod (lights on at 6:00 h and off at 22:00 h) and access to the litter floor from 12:00 h to 22:00 h daily. Airborne bacteria and PM were simultaneously sampled for 15 min at 1.5 m above the litter floor every fourth day at 5:45 h, 9:45 h, 13:45 h, 17:45 h, and 21:45 h. Concentrations of airborne bacteria at six size ranges (0.65 to 1.1 μm, 1.1 to 2.1 μm, 2.1 to 3.3 μm, 3.3 to 4.7 μm, 4.7 to 7.1 μm, and >7.1 μm) and PM concentrations (0.523 to 20.535 μm) were determined. The daily mean (±SD) concentrations of PM count, PM mass, and airborne bacteria were 1.70 (±0.66) × 10⁷ particles m^-3, 1.12 (±0.47) mg m^-3, and 3.39 (±2.38) × 10⁵ cfu m^-3, respectively. Concentrations of airborne PM and bacteria during the litter-access period (12:00 to 22:00 h) were significantly higher than those during the rest of the day when the hens were off the floor (p < 0.05). Median diameter and geometric standard deviation (GSD) for the PM count (0.523 to 20.535 μm) were 2.11 and 2.34 μm, respectively. Median diameter and GSD for the PM mass (0.523 to 20.535 μm) were 7.45 and 4.58 μm, respectively. PM <10 μm accounted for more than 95% of the total PM count, whereas PM >2.5 μm accounted for more than 90% of the total PM mass, in the size range of 0.523 to 20.535 μm. The majority (>95%) of the airborne bacteria were carried by particles >3.3 μm. Airborne bacteria count concentration was positively related to PM mass concentration (p < 0.05) with a slope of 3.84 (±2.70) × 10⁵ cfu mg^-1 PM. Results of the study are useful for improving understanding of transport behaviors of aerosols in aviary hen systems, assessing potential respiratory risks to humans and animals, and exploring mitigation techniques.

Mass magnetophoretic experiment applied to the separation of biocompatible magnetic nanoparticles with potential for magnetohyperthermia

A mass magnetophoretic experiment was developed to segregate nanoparticles according to their diameter and size dispersion. The samples were synthesized by the coprecipitation method and characterized using x-ray diffraction, high-resolution transmission electron microscopy and vibrating sample magnetometry. The mean diameter (standard deviation) showed a decrease of nanoparticle size (size dispersion) in the surface of the magnetic fluid sample submitted to the magnetophoretic experiment. Those effects were monitored by time-dependent apparent mass variation data, which could be important for scale-up applications. Magnetohyperthemia experiments were also performed, confirming our findings.

Genetic trends for growth and wool traits of Chinese superfine Merino sheep using a multi-trait animal model

The objective of the present study was to estimate genetic trends for birth weight (BW), weaning weight (WW), weaning staple length (WSL), yearling liveweight (YLW), and greasy fleece weight (YGFW), staple length (YSL), mean fibre diameter (YFD), fibre diameter standard deviation (YFDSD) and fibre diameter variation (YFDCV) at first shearing, which are essential to design a more efficient selection breeding programme for Chinese superfine Merino sheep. Data was collected on progeny from eight birth years (2001–2008) in the Chinese superfine Merino breeding flock maintained at Xinjiang Gongnaisi Fine Wool Sheep Breeding Farm. Different appropriate models for investigation of each trait using multivariate analysis were applied. (Co)variance components were estimated by average information restricted maximum likelihood (AIREML) and breeding values of individuals were predicted with Best Linear Unbiased Prediction (BLUP) methodology under multi-trait animal models. Genetic trends of studied traits were estimated by regressing mean of breeding values on birth year. Genetic trends were negative and significant for YFD and YFDSD (p<0.01) being 0.059 and 0.005μm/year respectively. The genetic changes for other traits were insignificant and maintained at the level of base year. Our results herein form a practical basis for designing optimal breeding schemes in Chinese superfine Merino.

The solid-state and morphological characteristics of particles generated from solution-based metered dose inhalers: Influence of ethanol concentration and intrinsic drug properties

The aerosol performance, physical properties and formation process of two corticosteroids (beclomethasone dipropionate and fluticasone propionate) and caffeine (active pharmaceutical ingredients: APIs) from ethanol-based pressurized metered dose inhaler solution formulations, containing various ethanol fractions, were evaluated using cascade impaction, thermal analysis and scanning electron microscopy. In general, the final aerosol particle size distribution (post USP induction port) was unaffected by ethanol concentration (mass median aerodynamic diameter and geometric standard deviation values for each formulation were independent of ethanol concentration (%, w/w) in the initial formulation). However, ethanol concentration directly affected the percentage of particles that passed the USP induction, resulting in a significant decrease in fine particle fraction, across all formulations, as ethanol was increased. Thus it can be concluded that particle size is governed by initial droplet diameter and API concentration, while performance is governed by drying time. The physico-chemical properties and morphology of the dried API particles, collected from cascade impactor stages, showed that the solid state was related to the glass transition temperature (Tg) and, to some extent, the saturated hydrofluoroalkane propellant (HFA)/ethanol solubility of the APIs. The low Tg API caffeine, with high HFA solubility resulted in crystalline particles, while the high Tg corticosteroids were amorphous. Furthermore, the final structure of the particles was dependent on the ethanol concentration and drying kinetics after initial droplet formation. This study has shown that the solid-state physico-chemical properties and morphology of particles is intrinsically linked to the API properties and drying kinetics of the propellant/co-solvent. These variations in aerosol efficiency, particle morphology and solid-state characteristics may have direct effects on drug efficacy and bioavailability after deposition in the lung.

Optimization of Electrospun Polyacrylonitrile/Poly(Vinylidene Fluoride) Nanofiber Diameter Using the Response Surface Method

Electrospinning of polyacrylonitrile/poly(vinylidene fluoride) (PAN/PVdF) was applied using Box–Benkhen experimental design to obtain a quantitative relationship between selected electrospinning parameters (namely applied voltage, solution concentration, and PVdF composition) and nanofiber diameter and standard deviation of nanofiber diameter. Important parameters in the model were determined by analysis of variance (ANOVA). The model was consequently used to find the optimal conditions that yield the minimum PAN/PVdF nanofiber diameter. The morphology and nanofiber diameter were investigated by field emission scanning electron microscopy (FESM). The range of produced nanofiber diameters was from 116 to 379 nm. It was concluded that the nanofiber diameter tended to increase with solution concentration and decrease with PVdF composition. The applied voltage had no significant effect on the nanofiber diameters. Nanofibers with smaller standard deviation in diameter could be obtained at lower solution concentrations and higher PVdF composition. The model predicted the minimum nanofiber diameter of 114 nm when the applied voltage was set at 19.7 kV, solution concentration set at 14.07 wt%, and the PVdF composition set at 58.78 wt%.

Prediction of Concentration Distribution in Pipeline Flow of Highly Concentrated Slurry

The Kaushal and Tomita's (2002a) model, which has already been found satisfactory for broadly graded multisized particulate zinc tailings slurry with moderate concentration up to 26%, flow velocity up to 3.5 m/s in 105 mm diameter pipe, mean diameter 140 μm, and geometric standard deviation of particles of 4.0, is tested for concentration distribution data collected by Kaushal et al. (2005) on two sizes of glass beads, of which mean diameter and geometric standard deviation are 440 μm and 1.2, and 125 μm and 1.15, respectively, with concentration up to 50% and flow velocity up to 5 m/s in 54.9 mm diameter pipe. Kaushal and Tomita's (2002a) model gives more asymmetric concentration distributions. A modified model is proposed by alleviating some of the restrictive assumptions used in the existing model. Comparison of experimental data by Kaushal et al. (2005), Gillies and Shook (1994), and Matousek (2009) with the proposed model is satisfactory.

Correlation Between Endobutton Loop Length and Tunnel Widening After Hamstring Anterior Cruciate Ligament Reconstruction

Background: Previous reports have shown that graft fixation with the Endobutton is associated with tunnel widening because it provides distant fixation rather than aperture fixation. Hypothesis: A longer loop of the Endobutton results in greater tunnel widening than a shorter loop. Study Design: Cohort study; Level of evidence, 3. Methods: A total of 171 consecutive patients underwent hamstring anterior cruciate ligament (ACL) reconstruction fixed with the Endobutton. They were followed for a minimum of 2 years postoperatively. A 15-mm loop was used in 20 patients, a 20-mm loop in 53, a 25-mm loop in 58, and a >30-mm loop in 40. On anterior-posterior (AP) and lateral radiographs, the measured diameters of the femoral tunnel at 2 years after surgery were compared with the diameter of the reamer used at surgery. The measured diameter of the tibial tunnel at 2 years after surgery was compared with measurements taken on the immediate postoperative day. The center of the tibial tunnel and direction of the ACL graft were also measured. Postoperative knee stability was evaluated using the Lachman test, pivot-shift test, and KT-1000 arthrometer. Functional evaluations were performed using the Lysholm score and Tegner activity scale. All measurements were compared among the 4 groups according to the length of the Endobutton loop. Results: The mean ± standard deviation (SD) diameter of the femoral tunnel increased by 50.7% ± 23.3% and 37.0% ± 18.8% on AP and lateral radiographs at 2 years after surgery, respectively. The mean ± SD diameter of the tibial tunnel increased by 40.8% ± 19.3% and 46.4% ± 22.6% on AP and lateral radiographs, respectively. No significant difference in tunnel widening was present according to the length of the Endobutton loop. There were no significant differences in the average center of the tibial tunnel or the average angle of the direction of the ACL graft among the 4 groups. There was no significant difference in Lachman test results, postoperative KT-1000 arthrometer side-to-side differences, Lysholm score, and Tegner activity scale score among the 4 groups. The group with a >30-mm loop showed a significant difference in the pivot-shift test than the other 3 groups (P = .023). Conclusion: A longer Endobutton loop did not result in greater tunnel widening than a shorter loop. Long fixation distance may not be associated with tunnel widening after hamstring ACL reconstructions.

Simulation of the Brownian coagulation of nanoparticles with initial bimodal size distribution via moment method

The Brownian coagulation of nanoparticles with initial bimodal size distribution, i.e., mode i and j, is numerically studied using the moment method. Evolutions of particle number concentration, geometric average diameter and geometric standard deviation are given in the free molecular regime, the continuum regime, the free molecular regime and transition regime, the free molecular regime and continuum regime, respectively. The results show that, both in the free molecular regime and the continuum regime, the number concentration of mode i and j decreases with increasing time. The evolutions of particle geometric average diameter with different initial size distribution are quite different. Both intra-modal and inter-modal coagulation finally make the polydispersed size distribution become monodispersed. As time goes by, the size distribution with initial bimodal turns to be unimodal and shifts to a larger particle size range. In the free molecular regime and transition regime, the inter-modal coagulation becomes dominant when the number concentrations of mode i and j are of the same order. The effects of the number concentration of mode i and mode j on the evolution of geometric average diameter of mode j are negligible, while the effects of the number concentration of mode j on the evolution of geometric average diameter of mode j is distinct. In the free molecular regime and continuum regime, the higher the initial number concentration of mode j, the more obvious the variation of the number concentration of mode i.

Development of Budesonide Nanocluster Dry Powder Aerosols: Formulation and Stability

The physical and chemical stability of dry powder aerosol formulations is an essential component in the development of an inhaled therapeutic. The pharmaceutical processing methods and storage conditions are primary determinants of the stability of a dry powder inhaler (DPI) formulation. Wet milling was used to produce budesonide NanoClusters (NCs), which are agglomerates of drug nanoparticles (≈ 300 nm) with a mean aerodynamic diameter between 1 and 3 µm, capable of deep lung penetration. In this study, the reproducibility of NC processing and performance was established. The physical stability of a selected budesonide NC formulation was investigated using industry standard dose content uniformity and cascade impaction techniques. The chemical stability of the lead formulation was also determined as a function of processing parameters and storage conditions. This study confirms the reproducibility and robust stability of NC powders as a novel means to turn drug particles into high-performance aerosols.

Nanoparticle Migration in a Fully Developed Turbulent Pipe Flow Considering the Particle Coagulation

Numerical simulations of nanoparticle migration in a fully developed turbulent pipe flow are performed. The evolution of particle number concentration, total particle mass, polydispersity, particle diameter and geometric standard deviation is obtained by using a moment method to approximate the particle general dynamic equation. The effects of Schmidt number and Damköhler number on the evolution of the particle parameters are analyzed. The results show that nanoparticles move to the pipe center. The particle number concentration and total particle mass are distributed non-uniformly along the radial direction. In an initially monodisperse particle field, the particle clusters with various sizes will be produced because of coagulation. As time progresses, the particle cluster diameter grows from an initial value at different rates depending on the radial position. The largest particle clusters are found in the pipe center. The particle cluster number concentration and total particle mass decrease with the increase of Schmidt number in the region near the pipe center, and the particles with lower Schmidt number are of many different sizes, i.e. more polydispersity. The particle cluster diameter and geometric standard deviation increase with the increase of Damköhler number at the same radial position. The migration properties for nano-sized particles are different from that for micro-sized particles.

Effect of Coagulation and Diffusion on Nanoparticle Distribution in a Fully Developed Turbulent Boundary Layer

Nanoparticle distributions in a fully developed turbulent boundary layer are simulated numerically using the moment method. The effects of Schmidt number and Damköhler number on the nanoparticle distribution are studied. It is found that the particle number concentration and total particle mass increase from the wall to the outside. The difference of particle number concentration and total particle mass near the wall and near the outside becomes smaller with the increasing Schmidt number Sc. The particle diameter and geometric standard deviation increase from the wall to the outside at a fixed Damköhler number Da, and grow with the increase of Da at the same lateral position.

Assessing Coagulant Dosage in Full-Scale Drinking Water Treatment Plants Using Nephelometry

Abstract A nephelometric turbidimeter monitoring system (NTMS) was utilized to measure the standard deviation (SD) of turbidity of suspension solutions. Experimental results demonstrated that turbidity SD was consistent with the theory that underlay the “turbidity fluctuation technique.” The NTMS was also used at a full-scale drinking water treatment plant to continuously monitor turbidity in all flocculation tanks. Experimental results revealed that under coagulant dosages of 0.33, 0.92, 1.67, and 2.67 mg/L, turbidity SD was strongly correlated with floc diameter in the flocculation tank. Turbidity SD and floc diameter increased to their maximum values at a coagulant dosage of 0.92 mg/L. This result suggested that turbidity SD obtained by using an NTMS could be used to determine the operational important parameters of water treatment plants.

Lognormal Fitting of Particle Size Distribution Data Monitored in Animal Buildings: Linear versus Nonlinear Regression Approach

Lognormal distribution is the most frequently used particle size distribution (PSD) model in agricultural air quality research, and a proper determination of volume median diameter (VMD) and geometric standard deviation (GSD) is crucial for model applications. In this study, the prevalent linear regression approach was compared to the nonlinear regression approach with PSD data monitored in 15 animal buildings using four particle size analyzers: Horiba, DSP, Coulter, and Malvern. Results showed that the linear regression approach significantly underestimated VMD values, and the resulting relative errors were higher overall than those yielded by the nonlinear regression approach. As a measure of model approximation, the values of the sum of absolute differences (SAD) derived from linear regression were considerably larger than those offered by nonlinear regression. The relative errors and SAD values both suggested a poorer performance of the linear regression approach. The SAD values and the relative errors in estimated VMD and GSD decreased as R2 approached 1. However, even at R2 = 0.98, the linear regression approach misestimated VMD values by up to 30% (or 14.6 µm) and yielded SAD values of around 20% to 40%. A strong interference of minor PSD peaks on the linear regression results was identified, which partly explains the inferior performance of the linear regression approach as compared to the nonlinear regression approach. For future relevant studies, the limitations of the linear regression approach should be recognized, and a preliminary comparison between different PSD parameter estimation approaches is recommended.

The effect of sieve agitators and dispersing agent on the method of determining and expressing fineness of feed materials by sieving

Research in both swine and poultry continue to investigate the optimal particle size for growth and gut health. Although researchers have reported the methods used to determine the particle size of the grain in a study, most reports have not provided details of the actual procedure. Although the standard method suggested adding both agitators and dispersing agents to facilitate the flow of material through the sieves there has been limited research as to whether these modifiers significantly change the particle size value. Researchers, laboratories, and feed mills that analyse samples without sieve agitators or a dispersing agent could overestimate the particle size and underestimate the distribution of the particles of a sample. Two experiments were conducted to determine the effect of adding sieve agitators and dispersing agent to the ANSI/ASAE S319.3 FEB03 ‘Method of Determining and Expressing Fineness of Feed Materials by Sieving’. The first experiment evaluated the effect of sieve agitator use and dispersing agent use on the geometric mean diameter (dgw) and geometric standard deviation (Sgw) of hammermill and roller mill corn samples. Whole corn was ground to produce samples that were classified as either coarse, medium, or fine. The second experiment evaluated the effect of sieve agitators, a dispersing agent, and the combination of agitators with a dispersing agent on dgw and Sgw of hammermill ground corn, wheat, and sorghum. The results of Expt 1 indicated that a decreased (P &lt; 0.01) dgw resulted when agitators were added to the hammermill ground samples while a further decrease (P &lt; 0.01) was observed due to the addition of the dispersing agent. The largest decrease in dgw was observed due to the addition of the dispersing agent. The addition of agitators to the roller mill samples only decreased the dgw of the medium grind sample. The dispersing agent decreased (P &lt; 0.01) the dgw of roller mill samples. The addition of a dispersing agent consistently decreased the dgw of all the ground corn samples as compared with the standard method without modifiers. The results of Expt 2 were consistent with those of Expt 1 in that the addition of the dispersing agent and agitators decreased dgw values and appeared to have an additive effect in both corn and sorghum samples. The addition of a dispersing agent facilitated the flow of product through the sieves. The wider distribution (Sgw) indicated that a greater percentage of material flowed to the smaller sieves. The results of the experiments clearly showed the benefit of adding sieve agitators and a dispersing agent to facilitate the flow of material through the sieves, so that a better estimate of the micron diameter and particle size distribution could be achieved.

Cashmere quality of Raeini goats kept by nomads in Iran

The income of the nomads in Kerman Province depends mainly on Raeini goats that produce meat, milk and cashmere. This paper assesses the cashmere quality and its variation in Raeini herds to determine the scope for improvement. In April 2010 fleece weights (FW) and midside fleece samples were taken from a total of 686 male and female cashmere goats of 1, 2 and 3 years of age belonging to 29 herds. The herds were randomly chosen in the summer grazing area of nomads within 20km of the city of Baft, province of Kerman, South of Iran, the main cashmere producing area in Iran. Cashmere yield (CY) was determined from the weight of dehaired cashmere to weight of shorn fiber. Cashmere fibers were analyzed using an OFDA instrument. A general mixed linear model including sex, age and sex by age interaction as fixed effects and herd as random effect was used to analyze the data and measure the relationships between different cashmere characteristics and fleece attributes. The overall means±standard deviations were for fleece weights (FW) 507±183g, cashmere yield (CY) 56.5±12.2%, mean fiber diameter (MFD) 19.7±1.5μm, fiber diameter standard deviation (FDSD) 4.5±0.6μm, fiber curvature (FC) 62.9±8.5°/mm and staple length (SL) 54.2±7.0mm, respectively. Herd effect was significant for all traits except for SL and sex by age effect was only significant for MFD. One year old males and females had finer cashmere than older goats. FW and FDSD were higher in males and CY and FC was higher in young animals. Pearson correlation between MFD and FC, FDSD and MFD, MFD and FW was −0.647, 0.399 and 0.211 respectively. Raeini cashmere is white, has an excellent SL and FC but is relatively coarse. Given the differences between and within herds there seems to be substantial scope to improve the commercial value of Raeini cashmere.

Geographic mosaic of mutually exclusive dominance of obligate commensals in symbiotic communities associated with a burrowing echiuran worm

Species richness and community composition of symbionts associated with the burrowing echiuran worm, Ochetostoma erythrogrammon Leuckart & Ruppell, 1828, were quantitatively surveyed on subtropical intertidal flats in the Ryukyu Archipelago, Japan. Overall, we recorded seven species of burrow associates, including at least six obligate commensals. According to symbiont community composition, the study sites were largely divided into two groups; one was characterized by the dominance of a snapping shrimp, Alpheus barbatus Coutiere, 1897, and the other by the dominance of a scale worm, Lepidonotus sp. Furthermore, a granulometric analysis showed that the sediment characteristics differed significantly between shrimp- and scale worm-dominant sites in terms of median diameter and inclusive graphic standard deviation. These results suggest that these symbionts have different habitat requirements, resulting in the mutually exclusive dominance pattern. Our findings indicate that habitat heterogeneity is important to the evaluation and conservation of the symbiotic diversity in intertidal flats.

Parametric pedotransfer functions of a simple linear scale model for soil moisture retention curve

Soil moisture retention (SMR) curve is a basic soil property. Since, direct measurement of the SMR curve is costly and time-consuming; it can be estimated using pedotransfer functions (PTFs) based on more easily available soil properties. Parametric PTFs estimate the parameters of a closed-form analytical equation for representation of SMR curve. In this study, we derived parametric PTFs for the model of Groenevelt and Grant (2004) which include three adjustable fitting parameters (K0, K1 and n). Our results tended to consider the constant value of 5 for the parameter of K0, and the parameters K1 and n were estimated based on more easily available soil properties by using twenty-two soils. The value of soil water content at matric potential of 1500 kPa (qwp) must also be available for this model. In this study, we considered two conditions for entering the qwp in the model: using measured qwp and estimated qwp with more easily available soil properties considering sand fraction of the soil, organic matter content, geometric mean particle-size diameter and geometric standard deviation of the particle-size diameter. Finally, the derived PTFs were evaluated for eight independent soils. The results indicate that there was no considerable difference between the two mentioned conditions for using qwp to estimate the SMR curve. Also, the results demonstrated that the proposed model in this study can be used for estimating the SMR curve with acceptable accuracy. Key words: Model of Groenevelt and Grant, soil moisture retention curve, pedotransfer functions.

Nanoparticle distribution in a rotating curved pipe considering coagulation and dispersion

We study the evolution of the particle number concentration, mass concentration, particle polydispersity, particle diameter and geometric standard deviation considering particle coagulation and dispersion in a rotating curved pipe at different Reynolds number, Schmidt number and F number. It is found that, when the Coriolis force and the centrifugal force point to the same direction, particles concentrate near the outside edge of the pipe, which becomes more obvious as time goes by. The particle number and mass concentration increase faster at the early stage than that at the later stage, and approach a stable value finally. As the coagulation proceeds, the particle diameter, polydispersity and geometric standard deviation increase and have high values in the region close to the outside edge of the pipe. When the Coriolis force and the centrifugal force point to the opposite direction and the Coriolis force is more dominant than the centrifugal force, particles concentrate near the inside edge of the pipe. The particles in the region with a high number concentration have high mass concentration, large diameter and high polydispersity as well as large geometric standard deviation. The particle distribution is dependent on the balance of the pipe curvature and rotating speed. The Reynolds number and the Schmidt number have effects on the particle distribution when other parameters remain unchanged. An increase in the Reynolds number leads to an increase in particle number concentration and mass concentration, and a decrease in particle polydispersity, particle diameter and geometric standard deviation. With the increase of Schmidt number the particle number concentration and mass concentration increase, and the particle polydispersity, particle diameter and geometric standard deviation decrease.

Predicting forest structural parameters using the image texture derived from WorldView-2 multispectral imagery in a dryland forest, Israel

Estimation of forest structural parameters by field-based data collection methods is both expensive and time consuming. Satellite remote sensing is a low-cost alternative in modeling and mapping structural parameters in large forest areas. The current study investigates the potential of using WordView-2 multispectral satellite imagery for predicting forest structural parameters in a dryland plantation forest in Israel. The relationships between image texture features and the several structural parameters such as Number of Trees (NT), Basal Area (BA), Stem Volume (SV), Clark-Evans Index (CEI), Diameter Differentiation Index (DDI), Contagion Index (CI), Gini Coefficient (GC), and Standard Deviation of Diameters at Breast Heights (SDDBH) were examined using correlation analyses. These variables were obtained from 30m×30m square-shaped plots. The Standard Deviation of Gray Levels (SDGL) as a first order texture feature and the second order texture variables based on Gray Level Co-occurrence Matrix (GLCM) were calculated for the pixels that corresponds to field plots. The results of the correlation analysis indicate that the forest structural parameters are significantly correlated with the image texture features. The highest correlation coefficients were calculated for the relationships between the SDDBH and the contrast of red band (r=0.75, p<0.01), the BA and the entropy of blue band (r=0.73, p<0.01), and the GC and the contrast of blue band (r=0.71, p<0.01). Each forest structural parameter was modeled as a function of texture measures derived from the satellite image using stepwise multi linear regression analyses. The determination coefficient (R2) and root mean square error (RMSE) values of the best fitting models, respectively, are 0.38 and 109.56ha−1 for the NT; 0.54 and 1.79m2ha−1 for the BA; 0.42 and 27.18m3ha−1 for the SV; 0.23 and 0.16 for the CEI; 0.32 and 0.05 for the DDI; 0.25 and 0.06 for the CI; 0.50 and 0.05 for the GC; and 0.67 and 0.70 for the SDDBH. The leave-one-out cross-validation technique was applied for validation of the best-fitted models (R2>0.50). In conclusion, cross-validated statistics confirmed that the structural parameters including the BA, SDDBH, and GC can be predicted and mapped with a reasonable accuracy using the texture features extracted from the spectral bands of WorldView-2 image.