Estimates of structural complexity in clonal plant morphology: comparisons of grazed and ungrazed Acaena magellanica rhizomes

1999 ◽  
Vol 77 (6) ◽  
pp. 869-876 ◽  
Author(s):  
Jon Moen ◽  
Pär K Ingvarsson ◽  
David WH Walton
Keyword(s):  
Structural Complexity ◽  
Fractal Dimensions ◽  
Clonal Plant ◽  
Plant Morphology ◽  
Directional Growth ◽  
Growth Simulation ◽  
Rhizome Growth ◽  
Highly Correlated ◽  
Rhizome Morphology ◽  
Parameter Values

The aim of this study is to examine the information given by various indices of rhizome morphology that describe grazed and ungrazed rhizome systems of Acaena magellanica (Rosaceae). Internode lengths, branching probabilities, and branching angles were estimated from grazed and ungrazed rhizomes in the field. These parameter values were then used in computer simulations of rhizome growth, and the structural complexity of the simulated rhizomes were described using size, topology, and fractal dimensions. Grazed rhizomes had shorter internodes, higher probabilities of branching, and more open branching angles than ungrazed rhizomes. This resulted in a more directional growth (herring-bone pattern) in the simulated ungrazed rhizomes, whereas the grazed rhizomes had a more space-filling growth pattern. Most indices, even though they are based on different mathematical and theoretical backgrounds, were highly correlated and thus equally good at describing the structural complexity exhibited by the rhizomes. However, indices have different relationships to theories about function, and we suggest that any study of structural complexity of branching systems should use several different indices of shape depending on the questions asked.Key words: Acaena magellanica, fractal dimension, grazing, growth simulation, topology.

scholarly journals DYNAMICS OF A LARGE-SPIN-BOSON SYSTEM IN THE STRONG COUPLING REGIME

2003 ◽  
Vol 17 (28) ◽  
pp. 5489-5493 ◽  
Author(s):  
TILL VORRATH ◽  
TOBIAS BRANDES ◽  
BERNHARD KRAMER
Keyword(s):  
Strong Coupling ◽  
Collective Effects ◽  
Strong Coupling Regime ◽  
Markov Approximation ◽  
Expectation Value ◽  
Maximum Value ◽  
Two Level Systems ◽  
Highly Correlated ◽  
Parameter Values ◽  
Large Spin

We investigate collective effects of an ensemble of biased two-level systems interacting with a bosonic bath in the strong coupling regime. The two level systems are described by a large pseudo-spin J. An equation for the expectation value M(t) of the z-component of the pseudo spin is derived and solved numerically for an ohmic bath at T=0. In case of a large cut-off frequency of the spectral function, a Markov approximation is justified and an analytical solution is presented. We find that M(t) relaxes towards a highly correlated state with maximum value ±J for large times. However, this relaxation is extremely slow for most parameter values so as if the system was "frozen in" by interaction with the bosonic bath.

Texture Analyses Show Synergetic Effects of Biomechanical and Biochemical Stimulation on Mesenchymal Stem Cell Differentiation into Early Phase Osteoblasts

2013 ◽  
Vol 20 (1) ◽  
pp. 219-227 ◽  
Author(s):  
So Hee Park ◽  
Ji Won Shin ◽  
Yun Gyeong Kang ◽  
Jin-Sook Hyun ◽  
Min Jae Oh ◽  
...  
Keyword(s):  
Stem Cell ◽  
Fractal Dimension ◽  
Cell Differentiation ◽  
Early Phase ◽  
Human Mesenchymal Stem Cells ◽  
Structural Complexity ◽  
Fractal Dimensions ◽  
Stem Cell Differentiation ◽  
Control Group ◽  
Mesenchymal Stem Cell Differentiation

AbstractWe investigated the structural complexity and texture of the cytoskeleton and nucleus in human mesenchymal stem cells during early phase differentiation into osteoblasts according to the differentiation–induction method: mechanical and/or chemical stimuli. For this, fractal dimension and a number of parameters utilizing the gray-level co-occurrence matrix (GLCM) were calculated based on single-cell images after confirmation of differentiation by immunofluorescence staining. The F-actin and nuclear fractal dimensions were greater in both stimulus groups compared with the control group. The GLCM values for energy and homogeneity were lower in fibers of the F-actin cytoskeleton, indicating a dispersed F-actin arrangement during differentiation. In the nuclei of both stimulus groups, higher values for energy and homogeneity were calculated, indicating that the chromatin arrangement was chaotic during the early phase of differentiation. It was shown and confirmed that combined stimulation with mechanical and chemical factors accelerated differentiation, even in the early phase. Fractal dimension analysis and GLCM methods have the potential to provide a framework for further investigation of stem cell differentiation.

Fractal nature of regional ventilation distribution

2000 ◽  
Vol 88 (5) ◽  
pp. 1551-1557 ◽  
Author(s):  
William A. Altemeier ◽  
Steve McKinney ◽  
Robb W. Glenny
Keyword(s):  
Blood Flow ◽  
Regional Blood Flow ◽  
Fractal Dimensions ◽  
Close Correlation ◽  
Aerosol Deposition ◽  
Regional Ventilation ◽  
Significant Difference ◽  
Ventilation Heterogeneity ◽  
Highly Correlated ◽  
Ventilation And Perfusion

High-resolution measurements of pulmonary perfusion reveal substantial spatial heterogeneity that is fractally distributed. This observation led to the hypothesis that the vascular tree is the principal determinant of regional blood flow. Recent studies using aerosol deposition show similar ventilation heterogeneity that is closely correlated with perfusion. We hypothesize that ventilation has fractal characteristics similar to blood flow. We measured regional ventilation and perfusion with aerosolized and injected fluorescent microspheres in six anesthetized, mechanically ventilated pigs in both prone and supine postures. Adjacent regions were clustered into progressively larger groups. Coefficients of variation were calculated for each cluster size to determine fractal dimensions. At the smallest size lung piece, local ventilation and perfusion are highly correlated, with no significant difference between ventilation and perfusion heterogeneity. On average, the fractal dimension of ventilation is 1.16 in the prone posture and 1.09 in the supine posture. Ventilation has fractal properties similar to perfusion. Efficient gas exchange is preserved, despite ventilation and perfusion heterogeneity, through close correlation. One potential explanation is the similar geometry of bronchial and vascular structures.

Correlation Between In Silico Physicochemical Characteristics of Drugs and Their Mean Residence Time in Human and Dog

2012 ◽  
Vol 31 (1) ◽  
pp. 25-33 ◽  
Author(s):  
Tomasz Grabowski ◽  
Jerzy Jan Jaroszewski ◽  
Shayne Cox Gad ◽  
Marcin Feder
Keyword(s):  
Mathematical Model ◽  
Residence Time ◽  
Mean Residence Time ◽  
Physicochemical Parameters ◽  
Physicochemical Characteristics ◽  
Pharmacokinetic Data ◽  
Specific Drug ◽  
Highly Correlated ◽  
Parameter Values ◽  
The Relationship

The correlation between 52 physicochemical parameters and mean residence time (MRT) for 27 drugs used in human and dog were investigated. The physicochemical parameter values calculated provided a basis for deriving a series of arithmetic expressions, which were used to build a mathematical model describing the relationship between them and the MRT values. From the entire set of analyzed parameters, a subset of 14 was identified that contributed to the derivation of an arithmetic expression: [Formula: see text] the value of which is highly correlated with the MRT value in dogs ( P < .001) and allowed prediction of the MRT predicted (MRT(pred)). In humans, no correlation was found that allowed the calculation of MRT(pred). These results indicate that predicting the pharmacokinetics of any specific drug for humans based on pharmacokinetic data obtained in the dog should be undertaken with knowledge of the inherent limitations.

scholarly journals The power of 3D fractal dimensions for comparative shape and structural complexity analyses of irregularly shaped organisms

2017 ◽  
Vol 8 (12) ◽  
pp. 1650-1658 ◽  
Author(s):  
Jessica Reichert ◽  
André R. Backes ◽  
Patrick Schubert ◽  
Thomas Wilke
Keyword(s):  
Structural Complexity ◽  
Fractal Dimensions

Validation of a Mathematical Model for Road Cycling Power

1998 ◽  
Vol 14 (3) ◽  
pp. 276-291 ◽  
Author(s):  
James C. Martin ◽  
Douglas L. Milliken ◽  
John E. Cobb ◽  
Kevin L. McFadden ◽  
Andrew R. Coggan
Keyword(s):  
Mathematical Model ◽  
Measurement System ◽  
Standard Error ◽  
Power Measurement ◽  
Model Parameters ◽  
Model Parameter ◽  
Road Cycling ◽  
Highly Correlated ◽  
Parameter Values ◽  
Measured Power

This investigation sought to determine if cycling power could be accurately modeled. A mathematical model of cycling power was derived, and values for each model parameter were determined. A bicycle-mounted power measurement system was validated by comparison with a laboratory ergometer. Power was measured during road cycling, and the measured values were compared with the values predicted by the model. The measured values for power were highly correlated (R2= .97) with, and were not different than, the modeled values. The standard error between the modeled and measured power (2.7 W) was very small. The model was also used to estimate the effects of changes in several model parameters on cycling velocity. Over the range of parameter values evaluated, velocity varied linearly (R2> .99). The results demonstrated that cycling power can be accurately predicted by a mathematical model.

scholarly journals Length-weight relationship and growth pattern inference of a small indigenous freshwater Prawn, Macrobrachium lamarrei (H. Milne-Edwards, 1837) in Bangladesh

2015 ◽  
Vol 1 (1) ◽  
pp. 137-145
Author(s):  
Motia Gulshan Ara ◽  
Md Noor Nabi ◽  
Zoarder Faruque Ahmed ◽  
Mst Kaniz Fatema
Keyword(s):  
Body Weight ◽  
Carapace Length ◽  
Freshwater Prawn ◽  
Allometric Growth ◽  
Pooled Data ◽  
Weight Relationship ◽  
Length Measurements ◽  
Highly Correlated ◽  
Pattern Inference ◽  
Parameter Values

The length-weight relationships (LWRs) of Macrobrachium lamarrei (H. Milne-Edwards, 1837) was studied to construct the generalized relationships of body weight to carapace length measurements for male, female and combined prawn population separately over a calendar year. A total of 1018 specimens were used for this study. The parameter values of the equation W = a Lb describing the relationships between body weight and carapace length for male, female and combined prawns. The parameter of equations, a varied from 0.00096 to 0.00333, 0.00059 to 0.00728 and 0.00081 to 0.00440 for male, female and combined prawn population respectively. On the other hand, the slope of equations, b varied from 2.4363 to 2.8229, 2.0761 to 3.0314 and 2.2915 to 2.8998 for male, female and combined prawn population respectively indicating isometric growth in females but negative allometric for males suggesting that female prawns were comparatively in better condition than males of the same population. The generalized length-weight relationship was fitted with the pooled data of all monthly samples for male, female and combined prawn separately which were BW = 0.0008 CL2.924, BW = 0.0012 CL2.783 and BW = 0.0010CL2.845 respectively indicating negative allometric growth as b varied from 2.783 to 2.924. The results further revealed that all length-weight relationships (LWRs) were highly correlated (r2 > 0.904). DOI: http://dx.doi.org/10.3329/ralf.v1i1.22377 Res. Agric., Livest. Fish.1(1): 137-145, Dec 2014

FLUCTUATION-INDUCED LOCAL OSCILLATIONS AND FRACTAL PATTERNS IN THE LATTICE LIMIT CYCLE MODEL

2003 ◽  
Vol 03 (02) ◽  
pp. L241-L250 ◽  
Author(s):  
A. PROVATA ◽  
G. A. TSEKOURAS ◽  
F. DIAKONOS ◽  
D. FRANTZESKAKIS ◽  
F. BARAS ◽  
...  
Keyword(s):  
Hopf Bifurcation ◽  
Limit Cycle ◽  
Fractal Dimensions ◽  
Square Lattice ◽  
Cycle Model ◽  
Fractal Properties ◽  
Fractal Patterns ◽  
Self Similar ◽  
Parameter Values ◽  
Lattice Limit

The fractal properties of the Lattice Limit Cycle model are explored when the process is realized on a 2-dimensional square lattice support via Monte Carlo Simulations. It is shown that the structure of the steady state presents inhomogeneous fluctuations in the form of domains of identical particles. The various domains compete with one another via their borders which have self-similar, fractal structure. The fractality is more prominent, (fractal dimensions df < 2), when the parameter values are near the critical point where the Hopf bifurcation occurs. As the distance from the Hopf bifurcation increases in the parameter space the system becomes more homogeneous and the fractal dimension tends to the value df = 2.

Comparing the urban form of South European cities using fractal dimensions

2018 ◽  
Vol 47 (7) ◽  
pp. 1149-1166 ◽  
Author(s):  
Apostolos Lagarias ◽  
Poulicos Prastacos
Keyword(s):  
Urban Development ◽  
Urban Form ◽  
Fractal Dimensions ◽  
Binary Images ◽  
Soil Sealing ◽  
European Cities ◽  
Relative Ranking ◽  
Highly Correlated ◽  
D Values ◽  
Mediterranean France

This paper compares built-up patterns and the urban form of South European cities using fractal dimensions. Fractal dimensions (D) are estimated in two different ways: (a) using binary images with information only on the built-up and non-built-up areas and (b) using grayscale images that represent the different built-up densities. The Urban Atlas and the Imperviousness-Soil Sealing Degree datasets are used to compute fractal dimensions for the 14 cities in Spain, Portugal, Italy, Greece and the Mediterranean France with a population exceeding one million. The results indicate that differences in urban form are reflected in the fractal dimensions. Fractal dimensions are higher in cities characterized by a relatively continuous and homogeneous sprawl than in cities with elongated urban form or discontinuous development in periurban areas. In Spanish cities urban development is fragmented with clustered and contrasted patterns and this leads to lower fractal dimensions. In Italian and Portuguese cities, development follows relatively homogeneous patterns and D values are significantly higher. Other key findings of the research indicate that: (a) grayscale fractal dimensions are lower than the corresponding binary ones, nonetheless the relative ranking of the cities according to D remains about the same regardless of the method used and (b) fractal dimensions are highly correlated to the average built-up density.

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