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fractal dimension

Matteo Beretta-Piccoli, Giuseppe D'Antona, Cristian Zampella, Marco Barbero, Ron Clijsen, Corrado Cescon
The aim of this study was to determine the test-retest reliability of muscle fiber conduction velocity (CV) and fractal dimension (FD) obtained from multichannel surface electromyographic (sEMG) recordings. Forty healthy recreationally active subjects (20 men and 20 women) performed two elbow flexions on two trials with a 1-week interval. The first was a 20% maximal voluntary contraction (MVC) of 120 s, and the second at 60% MVC held until exhaustion. sEMG signals were detected from the biceps brachii, using bi-dimensional arrays...
February 17, 2017: Physiological Measurement
Shweta Jatav, Yogesh M Joshi
Investigating microstructure of suspensions with particles having anisotropic shape that share complex interactions is a challenging task leading to competing claims. This work investigates phase behavior of one such system: aqueous Laponite suspension, which is highly contested in the literature, using rheological and microscopic tools. Remarkably, we observe that over a broad range of Laponite (1.4 to 4 weight %) and salt concentrations (0 to 7 mM), the system overwhelmingly demonstrates all the rheological characteristics of the sol-gel transition leading to a percolated network...
February 17, 2017: Langmuir: the ACS Journal of Surfaces and Colloids
Monika Krasowska, Anna Strzelewicz, Gabriela Dudek, Michał Cieśla
Two-dimensional diffusion in heterogenic composite membranes, i.e., materials comprising polymer with dispersed inorganic fillers, composed of ethylcellulose and magnetic powder is studied. In the experimental part, the morphology of membranes is described by the following characteristics: the amount of polymer matrix, the fractal dimension of polymer matrix, the average size of polymer matrix domains, the average number of obstacles in the proximity of each polymer matrix pixel. The simulation work concentrates on the motion of a particle in the membrane environment...
January 2017: Physical Review. E
Daniel Shu Wei Ting, Gavin Siew Wei Tan, Rupesh Agrawal, Yasuo Yanagi, Nicole Ming Sie, Chee Wai Wong, Ian Yew San Yeo, Shu Yen Lee, Chui Ming Gemmy Cheung, Tien Yin Wong
Importance: Optical coherence tomographic angiography (OCT-A) is able to visualize retinal microvasculature without the need for injection of fluorescein contrast dye. Nevertheless, it is only able to capture a limited view of macula and does not show leakage. Objectives: To evaluate the retinal microvasculature using OCT-A in patients with type 2 diabetes as well as the association of OCT-A characteristics with diabetic retinopathy (DR) and systemic risk factors...
February 16, 2017: JAMA Ophthalmology
Azim Parandakh, Mohammad Tafazzoli-Shadpour, Mohammad-Mehdi Khani
This study aimed to investigate stepwise remodeling of human mesenchymal stem cells (hMSCs) in response to cyclic stretch through rearrangement and alignment of cells and cytoskeleton regulation toward smooth muscle cell (SMC) fate in different time spans. Image analysis techniques were utilized to calculate morphological parameters. Cytoskeletal reorganization was observed by investigating F-actin filaments using immunofluorescence staining, and expression level of contractile SMC markers was followed by a quantitative polymerase chain reaction method...
February 15, 2017: In Vitro Cellular & Developmental Biology. Animal
Despoina Geogiou, Eleni P Kalogianni
Capillary penetration is commonly used in a wide range of applications such as oil recovery, textile engineering and food technology. Furthermore, it is a useful tool for surface characterization of powders and porous media. Two are the commonest experimental methods to study capillary penetration: the height-time and the weight-time technique. However, it is not clear whether the two approaches provide the same results. This work aims to investigate similarities and differences between the two approaches and assess whether it is possible to replace one with another...
February 7, 2017: Journal of Colloid and Interface Science
Ting Hu, Qilin Huang, Kahing Wong, Hong Yang, Jingsi Gan, Yanru Li
An alkali-soluble polysaccharide was extracted from Lignosus rhinocerotis sclerotia (LRP). Its structural characteristics were determined by GC-MS, FT-IR, GC, 1D and 2D NMR combined with Smith degradation and methylation analysis. The LRP had a (1→3)-β-d-Glcp backbone with every three residues bearing a (1→6)-linked and hyperbranched side chain that contained three (1→6)-β-d-Glcp residues as secondary main chain and two terminal β-d-Glcp residues linked at O3. The degree of branching was 0.76 from GC-MS analysis, implying a highly branched structure for LRP...
June 15, 2017: Food Chemistry
Piotr Polanowski, Jeremiasz K Jeszka, Andrzej Sikorski
The static properties of two-dimensional athermal polymer solutions were studied by performing Monte Carlo lattice simulations using the cooperative motion algorithm (CMA) and taking into account the presence of explicit solvent molecules. The simulations were performed for a wide range of polymer chain lengths N (16-1024) and concentrations φ (0.0156-1). The results obtained for short chains (N < 256) were in good agreement with those given by previous simulations. For the longest chains (512 or 1024 beads), some unexpected behavior was observed in the dilute and semidilute regimes...
February 2017: Journal of Molecular Modeling
Qi He, Zhao Yang, Bin Gong, Jingjing Wang, Kaijun Xiao, Shang-Tian Yang
This work aimed to establish an effective approach to evaluate the quality of frozen fish, focusing on changes in fish tissue structure and chemical composition during storage. Fresh tilapia samples were treated by coating with tangerine peel (TP) extract and then stored at -4, -8 and -18 °C, respectively, for 40 days. The frozen fish tissues were analyzed for structural and chemical changes. Fractal dimension, which quantifies the porous structure formed in the tissue samples, texture properties including hardness and springiness, and moisture content and water activity all decreased during the storage, while the extents of lipid oxidation, measured as peroxide value and thiobarbituric acid concentration, and protein degradation, monitored with total volatile basic nitrogen and trichloroacetic acid soluble peptides, increased...
February 7, 2017: Scientific Reports
Gabriella Captur, Dina Radenkovic, Chunming Li, Yu Liu, Nay Aung, Filip Zemrak, Catalina Tobon-Gomez, Xuexin Gao, Perry M Elliott, Steffen E Petersen, David A Bluemke, Matthias G Friedrich, James C Moon
PURPOSE: To report the development of easy-to-use magnetic resonance imaging (MRI) fractal tools deployed on platforms accessible to all. The trabeculae of the left ventricle vary in health and disease but their measurement is difficult. Fractal analysis of cardiac MR images can measure trabecular complexity as a fractal dimension (FD). MATERIALS AND METHODS: This Health Insurance Portability and Accountability Act (HIPAA)-compliant study was approved by the local Institutional Review Board...
February 2, 2017: Journal of Magnetic Resonance Imaging: JMRI
Hui-Qun Wu, Huan Wu, Li-Li Shi, Li-Yuan Yu, Li-Yuan Wang, Ya-Lan Chen, Jin-Song Geng, Jian Shi, Kui Jiang, Jian-Cheng Dong
AIM: To determine the association between retinal vasculature changes and stroke. METHODS: MEDLINE and EMBASE were searched for relevant human studies to September 2015 that investigated the association between retinal vasculature changes and the prevalence or incidence of stroke; the studies were independently examined for their qualities. Data on clinical characteristics and calculated summary odds ratios (ORs) were extracted for associations between retinal microvascular abnormalities and stroke, including stroke subtypes where possible, and adjusted for key variables...
2017: International Journal of Ophthalmology
Yang Ju, Qingang Zhang, Jiangtao Zheng, Chun Chang, Heping Xie
The irregular morphology of single rock fracture significantly influences subsurface fluid flow and gives rise to a complex and unsteady flow state that typically cannot be appropriately described using simple laws. Yet the fluid flow in rough fractures of underground rock is poorly understood. Here we present a numerical method and experimental measurements to probe the effect of fracture roughness on the properties of fluid flow in fractured rock. We develop a series of fracture models with various degrees of roughness characterized by fractal dimensions that are based on the Weierstrass-Mandelbrot fractal function...
February 1, 2017: Scientific Reports
K Alba, R J Bingham, V Kontogiorgos
Mesoscopic structure of pectin with different molecular characteristics was investigated by means of small angle X-ray scattering (SAXS), electrokinetic measurements and data modelling. The influence of a broad range of pH (2-7) on chain conformation in the dilute and semi-diluted regime was investigated. Scattering data and concomitant analysis revealed two length scales at all environmental conditions studied. pH showed greater influence at acidic values (pH 2.0) enhancing the globular component of the structure due to association of galacturonic acid residues...
January 31, 2017: Biopolymers
Lihong Wang, Qin Wang, Lifeng Xi, Jin Chen, Songjing Wang, Liulu Bao, Zhouyu Yu, Luming Zhao
In this paper, we revisit the fractality of complex network by investigating three dimensions with respect to minimum box-covering, minimum ball-covering and average volume of balls. The first two dimensions are calculated through the minimum box-covering problem and minimum ball-covering problem. For minimum ball-covering problem, we prove its NP-completeness and propose several heuristic algorithms on its feasible solution, and we also compare the performance of these algorithms. For the third dimension, we introduce the random ball-volume algorithm...
January 27, 2017: Scientific Reports
Edurne Ibarrola-Ulzurrun, Consuelo Gonzalo-Martin, Javier Marcello-Ruiz, Angel Garcia-Pedrero, Dionisio Rodriguez-Esparragon
Ecosystems provide a wide variety of useful resources that enhance human welfare, but these resources are declining due to climate change and anthropogenic pressure. In this work, three vulnerable ecosystems, including shrublands, coastal areas with dunes systems and areas of shallow water, are studied. As far as these resources' reduction is concerned, remote sensing and image processing techniques could contribute to the management of these natural resources in a practical and cost-effective way, although some improvements are needed for obtaining a higher quality of the information available...
January 25, 2017: Sensors
V V Nishawala, M Ostoja-Starzewski, M J Leamy, E Porcu
This paper reports on a generalization of Lamb's problem to a linear elastic, infinite half-space with random fields (RFs) of mass density, subject to a normal line load. Both, uncorrelated and correlated (with fractal and Hurst characteristics) RFs without any weak noise restrictions, are proposed. Cellular automata (CA) is used to simulate the wave propagation. CA is a local computational method which, for rectangular discretization of spatial domain, is equivalent to applying the finite difference method to the governing equations of classical elasticity...
December 2016: Proceedings. Mathematical, Physical, and Engineering Sciences
Xue Shen, Baoyu Gao, Xin Huang, Fan Bu, Qinyan Yue, Ruihua Li, Bo Jin
This study systematically determined the optimal dosage ratio and the viscosity (η) of co-coagulants, polyaluminum chloride (PAC) and poly dimethyldiallylammonium chloride (PDMDAAC), on coagulation performance and membrane fouling in a hybrid coagulation-ultrafiltration (C-UF) process for natural organic matter (NOM) removal. Floc characteristics-including floc size, fractal dimension, strength and re-growth ability-were studied with respect to coagulant-dosing operations. Membrane fouling was evaluated in association with assessment of NOM removal performance by the hybrid process...
January 21, 2017: Chemosphere
L M Almassalha, A Tiwari, P T Ruhoff, Y Stypula-Cyrus, L Cherkezyan, H Matsuda, M A Dela Cruz, J E Chandler, C White, C Maneval, H Subramanian, I Szleifer, H K Roy, V Backman
Most of what we know about gene transcription comes from the view of cells as molecular machines: focusing on the role of molecular modifications to the proteins carrying out transcriptional reactions at a loci-by-loci basis. This view ignores a critical reality: biological reactions do not happen in an empty space, but in a highly complex, interrelated, and dense nanoenvironment that profoundly influences chemical interactions. We explored the relationship between the physical nanoenvironment of chromatin and gene transcription in vitro...
January 24, 2017: Scientific Reports
Wenyu Wang, Shuang Zhao, Qinyan Yue, Baoyu Gao, Wen Song, Lijuan Feng
The objective of this study was to investigate the effect of different Al species and chitosan (CS) dosages on coagulation performance, floc characteristics (floc sizes, strength and regrowth ability and fractal dimension) and membrane resistance in a coagulation-ultrafiltration hybrid process. Results showed that different Al species combined with humic acid in diverse ways. Ala had better removal efficiency, as determined by UV254 and dissolved organic carbon, which could be further improved by the addition of CS...
January 2017: Journal of Environmental Sciences (China)
Muhammad Shafiq-Ul-Hassan, Geoffrey G Zhang, Kujtim Latifi, Ghanim Ullah, Dylan C Hunt, Yoganand Balagurunathan, Mahmoud Abrahem Abdalah, Matthew B Schabath, Dmitry G Goldgof, Dennis Mackin, Laurence Edward Court, Robert James Gillies, Eduardo Gerardo Moros
PURPOSE: Many radiomics features were originally developed for non-medical imaging applications and therefore original assumptions may need to be reexamined. In this study, we investigated the impact of slice thickness and pixel spacing (or pixel size) on radiomics features extracted from Computed Tomography (CT) phantom images acquired with different scanners as well as different acquisition and reconstruction parameters. The dependence of CT texture features on gray level discretization was also evaluated...
January 23, 2017: Medical Physics
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