keyword
MENU ▼
Read by QxMD icon Read
search

fractal dimension

keyword
https://www.readbyqxmd.com/read/28445607/fractal-characteristics-of-the-microvascular-network-a-useful-index-to-assess-vascularization-level-of-porous-silk-fibroin-biomaterial
#1
Kuihua Zhan, Lun Bai, Qinqin Wu, Derong Lei, Guangqian Wang
The neovascularization of biomaterials for tissue engineering is not only related to growth of capillaries but also involves appropriate hierarchy distribution of the microvessels. In this study, we proposed hierarchy distribution contrast method which can assess vascular transport capacity, in order to examine the hierarchy distribution of the neovessels during vascularization of the porous silk fibroin biomaterials implanted into rats and its evolution. The results showed that the fractal characteristics appeared toward the end of the vascularization stages, and the structure of the microvascular network after 3 weeks of implantation was similar to the fractal microvascular tree with bifurcation exponent x=3 and fractal dimension D=1...
April 26, 2017: Journal of Biomedical Materials Research. Part A
https://www.readbyqxmd.com/read/28443878/influence-of-high-energy-electron-irradiation-on-the-network-structure-of-gelatin-hydrogels-as-investigated-by-small-angle-x-ray-scattering-saxs
#2
Emilia I Wisotzki, Paolo Tempesti, Emiliano Fratini, Stefan G Mayr
The impact of high energy crosslinking on the network structure of gelatin hydrogels was investigated in comparison to physically entangled gels by small-angle X-ray scattering (SAXS). Physically entangled gelatin of increasing concentration exhibited a nearly constant correlation length of several nanometers. These gels had scattering behavior close to that of polymer coils swollen in a good solvent, as evidenced by the Porod exponent of 1.8. The mass fractal dimension decreased towards 1, indicating increased formation of semiflexible gelatin triple helices and rod-like structures as a function of the gelatin concentration...
April 26, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/28439649/differences-in-tibial-subchondral-bone-structure-evaluated-using-plain-radiographs-between-knees-with-and-without-cartilage-damage-or-bone-marrow-lesions-the-oulu-knee-osteoarthritis-study
#3
Jukka Hirvasniemi, Jérôme Thevenot, Ali Guermazi, Jana Podlipská, Frank W Roemer, Miika T Nieminen, Simo Saarakkala
OBJECTIVES: To investigate whether subchondral bone structure from plain radiographs is different between subjects with and without articular cartilage damage or bone marrow lesions (BMLs). METHODS: Radiography-based bone structure was assessed from 80 subjects with different stages of knee osteoarthritis using entropy of Laplacian-based image (ELap) and local binary patterns (ELBP), homogeneity index of local angles (HIAngles,mean), and horizontal (FDHor) and vertical fractal dimensions (FDVer)...
April 24, 2017: European Radiology
https://www.readbyqxmd.com/read/28437483/quantitative-microvascular-analysis-of-retinal-venous-occlusions-by-spectral-domain-optical-coherence-tomography-angiography
#4
Nicole Koulisis, Alice Y Kim, Zhongdi Chu, Anoush Shahidzadeh, Bruce Burkemper, Lisa C Olmos de Koo, Andrew A Moshfeghi, Hossein Ameri, Carmen A Puliafito, Veronica L Isozaki, Ruikang K Wang, Amir H Kashani
PURPOSE: To quantitatively evaluate the retinal microvasculature in human subjects with retinal venous occlusions (RVO) using optical coherence tomography angiography (OCTA). DESIGN: Retrospective, cross-sectional, observational case series. PARTICIPANTS: Sixty subjects (84 eyes) were included (20 BRVO, 14 CRVO, 24 unaffected fellow eyes, and 26 controls). METHODS: OCTA was performed on a prototype, spectral domain-OCTA system in the 3x3mm central macular region...
2017: PloS One
https://www.readbyqxmd.com/read/28436450/definition-of-fractal-topography-to-essential-understanding-of-scale-invariance
#5
Yi Jin, Ying Wu, Hui Li, Mengyu Zhao, Jienan Pan
Fractal behavior is scale-invariant and widely characterized by fractal dimension. However, the cor-respondence between them is that fractal behavior uniquely determines a fractal dimension while a fractal dimension can be related to many possible fractal behaviors. Therefore, fractal behavior is independent of the fractal generator and its geometries, spatial pattern, and statistical properties in addition to scale. To mathematically describe fractal behavior, we propose a novel concept of fractal topography defined by two scale-invariant parameters, scaling lacunarity (P) and scaling coverage (F)...
April 24, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28430738/three-dimensional-fractal-analysis-of-99mtc-maa-spect-images-in-chronic-thromboembolic-pulmonary-hypertension-for-evaluation-of-response-to-balloon-pulmonary-angioplasty-association-with-pulmonary-arterial-pressure
#6
Yasuhiro Maruoka, Michinobu Nagao, Shingo Baba, Takuro Isoda, Yoshiyuki Kitamura, Yuzo Yamazaki, Koichiro Abe, Masayuki Sasaki, Kohtaro Abe, Hiroshi Honda
OBJECTIVE: Balloon pulmonary angioplasty (BPA) is used for inoperable chronic thromboembolic pulmonary hypertension (CTEPH), but its effect cannot be evaluated noninvasively. We devised a noninvasive quantitative index of response to BPA using three-dimensional fractal analysis (3D-FA) of technetium-99m-macroaggregated albumin (Tc-MAA) single-photon emission computed tomography (SPECT). PATIENTS AND METHODS: Forty CTEPH patients who underwent pulmonary perfusion scintigraphy and mean pulmonary arterial pressure (mPAP) measurement by right heart catheterization before and after BPA were studied...
April 20, 2017: Nuclear Medicine Communications
https://www.readbyqxmd.com/read/28430461/quantifying-the-dynamical-complexity-of-chaotic-time-series
#7
Antonio Politi
A powerful approach is proposed for the characterization of chaotic signals. It is based on the combined use of two classes of indicators: (i) the probability of suitable symbolic sequences (obtained from the ordinal patterns of the corresponding time series); (ii) the width of the corresponding cylinder sets. This way, much information can be extracted and used to quantify the complexity of a given signal. As an example of the potentiality of the method, I introduce a modified permutation entropy which allows for quantitative estimates of the Kolmogorov-Sinai entropy in hyperchaotic models, where other methods would be unpractical...
April 7, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28430459/direct-observation-of-percolation-in-the-yielding-transition-of-colloidal-glasses
#8
Antina Ghosh, Zoe Budrikis, Vijayakumar Chikkadi, Alessandro L Sellerio, Stefano Zapperi, Peter Schall
When strained beyond the linear regime, soft colloidal glasses yield to steady-state plastic flow in a way that is similar to the deformation of conventional amorphous solids. Because of the much larger size of the colloidal particles with respect to the atoms comprising an amorphous solid, colloidal glasses allow us to obtain microscopic insight into the nature of the yielding transition, as we illustrate here combining experiments, atomistic simulations, and mesoscopic modeling. Our results unanimously show growing clusters of nonaffine deformation percolating at yielding...
April 7, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28422647/eeg-based-affect-and-workload-recognition-in-a-virtual-driving-environment-for-asd-intervention
#9
Jing Fan, Joshua W Wade, Alexandra P Key, Zachary Warren, Nilanjan Sarkar
OBJECTIVE: To build group-level classification models capable of recognizing affective states and mental workload of individuals with autism spectrum disorder (ASD) during driving skill training. METHODS: Twenty adolescents with ASD participated in a six-session virtual reality driving simulator based experiment, during which their electroencephalogram (EEG) data were recorded alongside driving events and a therapist's rating of their affective states and mental workload...
April 12, 2017: IEEE Transactions on Bio-medical Engineering
https://www.readbyqxmd.com/read/28419951/can-fractal-methods-applied-to-video-tracking-detect-the-effects-of-deltamethrin-pesticide-or-mercury-on-the-locomotion-behavior-of-shrimps
#10
Bruno Mendes Tenorio, Eurípedes Alves da Silva Filho, Gentileza Santos Martins Neiva, Valdemiro Amaro da Silva, Fernanda das Chagas Angelo Mendes Tenorio, Themis de Jesus da Silva, Emerson Carlos Soares E Silva, Romildo de Albuquerque Nogueira
Shrimps can accumulate environmental toxicants and suffer behavioral changes. However, methods to quantitatively detect changes in the behavior of these shrimps are still needed. The present study aims to verify whether mathematical and fractal methods applied to video tracking can adequately describe changes in the locomotion behavior of shrimps exposed to low concentrations of toxic chemicals, such as 0.15µgL(-1) deltamethrin pesticide or 10µgL(-1) mercuric chloride. Results showed no change after 1min, 4, 24, and 48h of treatment...
April 15, 2017: Ecotoxicology and Environmental Safety
https://www.readbyqxmd.com/read/28418811/hypertrabeculated-left-ventricular-myocardium-in-relationship-to-myocardial-function-and-fibrosis-the-multi-ethnic-study-of-atherosclerosis
#11
Nadine Kawel-Boehm, Robyn L McClelland, Filip Zemrak, Gabriella Captur, W Gregory Hundley, Chia-Ying Liu, James C Moon, Steffen E Petersen, Bharath Ambale-Venkatesh, João A C Lima, David A Bluemke
Purpose To determine if excess greater left ventricle (LV) trabeculation is associated with decreased average regional myocardial function, diffuse fibrosis, or both. Materials and Methods This was a HIPAA-compliant institutional board approved multicenter study, and all participants provided written informed consent. Participants in the Multi-Ethnic Study of Atherosclerosis (MESA) underwent a comprehensive cardiac magnetic resonance (MR) examination. LV trabeculation was measured with the maximal apical fractal dimension (FD), which is a marker of endocardial complexity...
April 17, 2017: Radiology
https://www.readbyqxmd.com/read/28416437/the-ct-based-fractal-analysis-of-trabecular-bone-structure-may-help-in-detecting-decreased-quality-of-bone-prior-to-urgent-spinal-procedures
#12
Marcin Czyz, Arion Kapinas, James Holton, Renata Pyzik, Bronek M Boszczyk, Nasir A Quraishi
BACKGROUND CONTEXT: To date no reliable method is available to determine the parameters of bone density based on the routine spinal CT in the emergency setup. We propose the use of fractal analysis to detect patients with poor quality of bone prior to urgent or semi-urgent spinal procedures. PURPOSE: To validate the hypothesis that the CT-based fractal analysis of the trabecular bone structure may help in detecting patients with poor quality of bone prior to urgent spinal procedures...
April 14, 2017: Spine Journal: Official Journal of the North American Spine Society
https://www.readbyqxmd.com/read/28406937/cost-and-time-effective-method-for-multi-scale-measures-of-rugosity-fractal-dimension-and-vector-dispersion-from-coral-reef-3d-models
#13
G C Young, S Dey, A D Rogers, D Exton
We present a method to construct and analyse 3D models of underwater scenes using a single cost-effective camera on a standard laptop with (a) free or low-cost software, (b) no computer programming ability, and (c) minimal man hours for both filming and analysis. This study focuses on four key structural complexity metrics: point-to-point distances, linear rugosity (R), fractal dimension (D), and vector dispersion (1/k). We present the first assessment of accuracy and precision of structure-from-motion (SfM) 3D models from an uncalibrated GoPro™ camera at a small scale (4 m2) and show that they can provide meaningful, ecologically relevant results...
2017: PloS One
https://www.readbyqxmd.com/read/28405381/a-model-of-urban-scaling-laws-based-on-distance-dependent-interactions
#14
Fabiano L Ribeiro, Joao Meirelles, Fernando F Ferreira, Camilo Rodrigues Neto
Socio-economic related properties of a city grow faster than a linear relationship with the population, in a log-log plot, the so-called superlinear scaling. Conversely, the larger a city, the more efficient it is in the use of its infrastructure, leading to a sublinear scaling on these variables. In this work, we addressed a simple explanation for those scaling laws in cities based on the interaction range between the citizens and on the fractal properties of the cities. To this purpose, we introduced a measure of social potential which captured the influence of social interaction on the economic performance and the benefits of amenities in the case of infrastructure offered by the city...
March 2017: Royal Society Open Science
https://www.readbyqxmd.com/read/28399465/influences-of-fractal-dimension-of-membrane-surface-on-interfacial-interactions-related-to-membrane-fouling-in-a-membrane-bioreactor
#15
Xiang Cai, Lining Yang, Zhiwei Wang, Meijia Zhang, Liguo Shen, Huachang Hong, Hongjun Lin, Genying Yu
Influences of fractal dimension (Df) of membrane surface on interfacial interactions related to membrane fouling in a membrane bioreactor were investigated based on thermodynamic methods. It was found that membrane surface had significant fractal features, and its fractal dimension could be characterized by the power spectrum method. The modified Weierstrass-Mandelbrot (WM) function was found to be effective to model the fractal membrane surface, and higher Df corresponded to higher number of fine asperities in the modeled surface...
March 29, 2017: Journal of Colloid and Interface Science
https://www.readbyqxmd.com/read/28388703/quantitative-oct-angiography-of-the-retinal-microvasculature-and-the-choriocapillaris-in-myopic-eyes
#16
Mayss Al-Sheikh, Nopasak Phasukkijwatana, Rosa Dolz-Marco, Mansour Rahimi, Nicholas A Iafe, K Bailey Freund, SriniVas R Sadda, David Sarraf
Purpose: To study the retinal capillary microvasculature and the choriocapillaris (CC) in myopic eyes using quantitative optical coherence tomography angiography (OCTA) analysis. Methods: Macular OCTA images of 3 × 3 mm were obtained using the RTVue-XR Avanti with AngioVue. Quantitative measurements of the retinal capillary microvascular layers and the CC were analyzed using en face projection images. Vessel density and fractal dimension of the superficial and deep retinal capillary plexus, and area and density of flow reduction in the CC were analyzed, quantified, and compared with an age-matched control group...
April 1, 2017: Investigative Ophthalmology & Visual Science
https://www.readbyqxmd.com/read/28388117/rapid-sampling-of-stochastic-displacements-in-brownian-dynamics-simulations
#17
Andrew M Fiore, Florencio Balboa Usabiaga, Aleksandar Donev, James W Swan
We present a new method for sampling stochastic displacements in Brownian Dynamics (BD) simulations of colloidal scale particles. The method relies on a new formulation for Ewald summation of the Rotne-Prager-Yamakawa (RPY) tensor, which guarantees that the real-space and wave-space contributions to the tensor are independently symmetric and positive-definite for all possible particle configurations. Brownian displacements are drawn from a superposition of two independent samples: a wave-space (far-field or long-ranged) contribution, computed using techniques from fluctuating hydrodynamics and non-uniform fast Fourier transforms; and a real-space (near-field or short-ranged) correction, computed using a Krylov subspace method...
March 28, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28381973/saxs-analysis-of-single-and-multi-core-iron-oxide-magnetic-nanoparticles
#18
Wojciech Szczerba, Rocio Costo, Sabino Veintemillas-Verdaguer, Maria Del Puerto Morales, Andreas F Thünemann
This article reports on the characterization of four superparamagnetic iron oxide nanoparticles stabilized with dimercaptosuccinic acid, which are suitable candidates for reference materials for magnetic properties. Particles p1 and p2 are single-core particles, while p3 and p4 are multi-core particles. Small-angle X-ray scattering analysis reveals a lognormal type of size distribution for the iron oxide cores of the particles. Their mean radii are 6.9 nm (p1), 10.6 nm (p2), 5.5 nm (p3) and 4.1 nm (p4), with narrow relative distribution widths of 0...
April 1, 2017: Journal of Applied Crystallography
https://www.readbyqxmd.com/read/28381788/evaluation-of-3d-printer-accuracy-in-producing-fractal-structure
#19
Kana Kikegawa, Kyuuichirou Takamatsu, Masaru Kawakami, Hidemitsu Furukawa, Hiroyuki Mayama, Yoshimune Nonomura
Hierarchical structures, also known as fractal structures, exhibit advantageous material properties, such as water- and oil-repellency as well as other useful optical characteristics, owing to its self-similarity. Various methods have been developed for producing hierarchical geometrical structures. Recently, fractal structures have been manufactured using a 3D printing technique that involves computer-aided design data. In this study, we confirmed the accuracy of geometrical structures when Koch curve-like fractal structures with zero to three generations were printed using a 3D printer...
2017: Journal of Oleo Science
https://www.readbyqxmd.com/read/28373892/tips-a-system-for-automated-image-based-phenotyping-of-maize-tassels
#20
Joseph L Gage, Nathan D Miller, Edgar P Spalding, Shawn M Kaeppler, Natalia de Leon
BACKGROUND: The maize male inflorescence (tassel) produces pollen necessary for reproduction and commercial grain production of maize. The size of the tassel has been linked to factors affecting grain yield, so understanding the genetic control of tassel architecture is an important goal. Tassels are fragile and deform easily after removal from the plant, necessitating rapid measurement of any shape characteristics that cannot be retained during storage. Some morphological characteristics of tassels such as curvature and compactness are difficult to quantify using traditional methods, but can be quantified by image-based phenotyping tools...
2017: Plant Methods
keyword
keyword
60173
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"