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fractal dimension

Felix Sebastian Leo Thomsen, Jaime Andrés Peña, Yongtao Lu, Gerd Huber, Michael Morlock, Claus-Christian Glüer, Claudio Augusto Delrieux
PURPOSE: Existing microstructure parameters are able to predict vertebral in vitro failure load, but for noisy in vivo data more complex algorithms are needed for a robust assessment. METHODS: A new algorithm is proposed for the microstructural analysis of trabecular bone under in vivo quantitative computed tomography (QCT). Five fractal parameters are computed: (1) the average local fractal dimension FD, (2) its standard deviation FD.SD, (3) the fractal rod volume ratio fRV/BV, (4) the average fractal trabecular thickness fTb...
December 2016: Medical Physics
Haitao Fan, Xiuhong Liu, Hao Wang, Yunping Han, Lu Qi, Hongchen Wang
In activated sludge systems, the aeration process consumes the most energy. The energy cost can be dramatically reduced by decreasing the operating dissolved oxygen (DO) concentration. However, low DO may lead to incomplete nitrification and poor settling performance of activated sludge flocs (ASFs). This study investigates oxygen transfer dynamics and settling performances of activated sludge under different sludge retention times (SRTs) and DO conditions using microelectrodes and microscopic techniques. Our experimental results showed that with longer SRTs, treatment capacity and settling performances of activated sludge improved due to smaller floc size and less extracellular polymeric substances (EPS)...
November 27, 2016: Chemosphere
Yi Yu, Yun Zhao, Yajing Si, Qiongqiong Ren, Wu Ren, Changqin Jing, Hongxing Zhang
BACKGROUND: In schizophrenia, executive dysfunction is the most critical cognitive impairment, and is associated with abnormal neural activities, especially in the frontal lobes. Complexity estimation using electroencephalogram (EEG) recording based on nonlinear dynamics and task performance tests have been widely used to estimate executive dysfunction in schizophrenia. METHODS: The present study estimated the cool executive function based on fractal dimension (FD) values of EEG data recorded from first-episode schizophrenia patients and healthy controls during the performance of three cool executive function tasks, namely, the Trail Making Test-A (TMT-A), Trail Making Test-B (TMT-B), and Tower of Hanoi tasks...
November 25, 2016: Biomedical Engineering Online
Hongwei Yang, Béatrice A Baudet, Ting Yao
The surface roughness of soil grains affects the mechanical behaviour of soils, but the characterization of real soil grain roughness is still limited in both quantity and quality. A new method is proposed, which applies the power spectral density (PSD), typically used in tribology, to optical interferometry measurements of soil grain surfaces. The method was adapted to characterize the roughness of soil grains separately from their shape, allowing the scale of the roughness to be determined in the form of a wavevector range...
October 2016: Proceedings. Mathematical, Physical, and Engineering Sciences
Hao Hu, Robert M Ziff, Youjin Deng
The no-enclave percolation (NEP) model introduced recently by Sheinman et al. can be mapped to a problem of holes within a standard percolation backbone, and numerical measurements of such holes give the same size-distribution exponent τ=1.82(1) as found for the NEP model. An argument is given that τ=1+d_{B}/2≈1.822 for backbone holes, where d_{B} is the backbone dimension. On the other hand, a model of simple holes within a percolation cluster yields τ=1+d_{f}/2=187/96≈1.948, where d_{f} is the fractal dimension of the cluster, and this value is consistent with the experimental results of gel collapse of Sheinman et al...
October 28, 2016: Physical Review Letters
Otilia Constantina Rogoveanu, Diana Kamal, Magdalena Rodica Trăistaru, Costin Teodor Streba
Gonarthrosis is a degenerative disease that affects mainly older people, but whose incidence has increased significantly in the last decade in population under the age of 65. The main objective of this study was developing a predictive model of synovial membrane degradation in relation to local nerve structures in patients with knee osteoarthritis, based on advanced morphometry and artificial neural networks (ANNs). We present here a pilot test of the method, describing preliminary findings in analyzing a pre-set number of images...
2016: Romanian Journal of Morphology and Embryology, Revue Roumaine de Morphologie et Embryologie
Jun Cheng, Qing Ye, Zongbo Yang, Weijuan Yang, Junhu Zhou, Kefa Cen
The response mechanisms of microalgal mutant Chlorella PY-ZU1 cells were investigated in their removal of antibiotic tilmicosin from wastewater under 15% CO2. Low concentrations (0.01-2mgL(-1)) of tilmicosin in wastewater stimulated the growth of microalgal cells, whereas high concentrations (5-50mgL(-1)) of tilmicosin significantly inhibited cell growth. When initial tilmicosin concentration increased from 0 to 50mgL(-1), fractal dimension of microalgal cells monotonically increased from 1.36 to 1.62 and cell size monotonically decreased from 4...
November 3, 2016: Journal of Hazardous Materials
Meiyan Xing, Cenran Li, Jinzhou Jiang, Yin Wang, Jian Yang
To improve excess sludge dewaterability, a two-stage vermifilter was developed to qualitatively and quantitatively analyze sludge physico-chemical properties (fractal dimension, zeta potential, extracellular polymeric substances (EPS), particle size distribution, etc.) and to correlate them with sludge dewatering characteristics (specific resistance to filtration (SRF) and capillary suction time (CST)). Results demonstrated that sludge dewatering performance was significantly improved after the primary vermifilter VF1 and the second-stage vermifilter VF2...
November 8, 2016: Applied Microbiology and Biotechnology
Tolga F Tözüm, Erhan Dursun, Serdar Uysal
BACKGROUND: The aim of the present study was to investigate whether the mandibular cortical index (MCI) has a relationship with fractal dimension of bone and/or implant stability, and to justify the possible association between MCI, fractal dimension, and stability. MATERIALS AND METHODS: Eighty-two subjects who received dental implants to replace missing mandibular premolar/molar sites were selected. Three months after surgical placement, implants were restored with fixed ceramic fused metal crowns...
December 2016: Implant Dentistry
Igor Pantic, Dejan Nesic, Milos Basailovic, Mila Cetkovic, Sanja Mazic, Jelena Suzic-Lazic, Martin Popevic
Despite previous research efforts in the fields of histology and cell physiology, the relationship between chromatin structural organization and nuclear shape remains unclear. The aim of this research was to test the existence and strength of correlations between mathematical parameters of chromatin microarchitecture and roundness of the nuclear envelope. On a sample of 240 nuclei of adrenal zona fasciculata cells stained using the DNA-specific Feulgen method, we quantified fractal parameters such as fractal dimension and lacunarity, as well as textural parameters such as angular second moment (ASM), entropy, inverse difference moment, contrast, and variance...
November 8, 2016: Microscopy and Microanalysis
Lei Yang, Ran Wei, Henggen Shen
New principal component analysis (PCA) respirator fit test panels had been developed for current American and Chinese civilian workers based on anthropometric surveys. The PCA panels used the first two principal components (PCs) obtained from a set of 10 facial dimensions. Although the PCA panels for American and Chinese subjects adopted the bivairate framework with two PCs, the number of the PCs retained in the PCA analysis was different between Chinese subjects and Americans. For the Chinese youth group, the third PC should be retained in the PCA analysis for developing new fit test panels...
January 2017: Journal of Occupational and Environmental Hygiene
Carlo Cottone, Camillo Porcaro, Andrea Cancelli, Elzbieta Olejarczyk, Carlo Salustri, Franca Tecchio
Brodmann's pioneering work resulted in the classification of cortical areas based on their cytoarchitecture and topology. Here, we aim at documenting that diverse cortical areas also display different neuronal electric activities. We investigated this notion in the hand-controlling sections of the primary somatosensory (S1) and motor (M1) areas, in both hemispheres. We identified S1 and M1 in 20 healthy volunteers by applying functional source separation (FSS) to their recorded electroencephalograms (EEG). Our results show that S1 and M1 can be clearly differentiated by their neuroelectric activities in both hemispheres and independently of the subject's state (i...
November 1, 2016: Brain Structure & Function
Angelo Rosa, Ralf Everaers
Randomly branching polymers with annealed connectivity are model systems for ring polymers and chromosomes. In this context, the branched structure represents transient folding induced by topological constraints. Here we present computer simulations of melts of annealed randomly branching polymers of 3 ≤ N ≤ 1800 segments in d = 2 and d = 3 dimensions. In all cases, we perform a detailed analysis of the observed tree connectivities and spatial conformations. Our results are in excellent agreement with an asymptotic scaling of the average tree size of R ∼ N(1/d), suggesting that the trees behave as compact, territorial fractals...
October 28, 2016: Journal of Chemical Physics
Lorea Flores, R A Bailey, Arturo Elosegi, Aitor Larrañaga, Julia Reiss
Habitat complexity can influence predation rates (e.g. by providing refuge) but other ecosystem processes and species interactions might also be modulated by the properties of habitat structure. Here, we focussed on how complexity of artificial habitat (plastic plants), in microcosms, influenced short-term processes driven by three aquatic detritivores. The effects of habitat complexity on leaf decomposition, production of fine organic matter and pH levels were explored by measuring complexity in three ways: 1...
2016: PloS One
Wanyu Tan, Yongmei Li, Kaixuan Tan, Xianzhe Duan, Dong Liu, Zehua Liu
Radon diffusion and transport through different media is a complex process affected by many factors. In this study, the fractal theories and field covering experiments were used to study the fractal characteristics of particle size distribution (PSD) of six kinds of geotechnical materials (e.g., waste rock, sand, laterite, kaolin, mixture of sand and laterite, and mixture of waste rock and laterite) and their effects on radon diffusion. In addition, the radon diffusion coefficient and diffusion length were calculated...
December 2016: Health Physics
Yanxia Zhao, Yangyang Sun, Chang Tian, Baoyu Gao, Yan Wang, Hokyong Shon, Yanzhao Yang
Titanium-based coagulation is expected to achieve both efficient water purification and sludge recycling. This study is the first attempt to use titanium tetrachloride (TiCl4) for silver nanoparticle (AgNP)-humic acid composite contaminant removal in a coagulation-ultrafiltration (C-UF) process, where characterization of flocs and membrane fouling under varied coagulant dose, initial solution pH, and AgNP concentration conditions are the main contents. Results suggested that the TiCl4 achieved high AgNP removal in the form of silver nanoparticle through adsorption and sweep flocculation and simultaneously exerted additional 68...
October 29, 2016: Environmental Science and Pollution Research International
Hamidreza Namazi, Amin Akrami, Jamal Hussaini, Osmar N Silva, Albert Wong, Vladimir V Kulish
Human DNA is the main unit that shapes human characteristics and features such as behavior. Thus, it is expected that changes in DNA (DNA mutation) influence human characteristics and features. Face is one of the human features which is unique and also dependent on his gen. In this paper, for the first time we analyze the variations of human DNA and face simultaneously. We do this job by analyzing the fractal dimension of DNA walk and face during human aging. The results of this study show the human DNA and face get more complex by aging...
October 29, 2016: Bioscience Trends
Tiago M Barbosa, Wan X Goh, Jorge E Morais, Mário J Costa, David Pendergast
The aim of this study was to compare the non-linear properties of the four competitive swim strokes. Sixty-eight swimmers performed a set of maximal 4 × 25 m using the four competitive swim strokes. The hip's speed-data as a function of time was collected with a speedo-meter. The speed fluctuation (dv), approximate entropy (ApEn) and the fractal dimension by Higuchi's method (D) were computed. Swimming data exhibited non-linear properties that were different among the four strokes (14.048 ≤ dv ≤ 39.722; 0...
2016: Frontiers in Psychology
Jasmin Nurković, Ivan Zaletel, Selmina Nurković, Šefćet Hajrović, Fahrudin Mustafić, Jovan Isma, Aleksandra Jurišić Škevin, Vesna Grbović, Milica Kovačević Filipović, Zana Dolićanin
In recent years, electromagnetic field (EMF) and low-level laser (LLL) have been found to affect various biological processes, the growth and proliferation of cells, and especially that of stem cells. The aim of this study was to investigate the effects of EMF and LLL on proliferation of human adipose tissue-derived mesenchymal stem cells (hAT-MSCs) and thus to examine the impact of these therapeutic physical modalities on stem cell engraftment. hAT-MSCs were isolated from subcutaneous adipose tissue of six persons ranging in age from 21 to 56 years...
October 21, 2016: Lasers in Medical Science
B L Altshuler, E Cuevas, L B Ioffe, V E Kravtsov
We combine numerical diagonalization with semianalytical calculations to prove the existence of the intermediate nonergodic but delocalized phase in the Anderson model on disordered hierarchical lattices. We suggest a new generalized population dynamics that is able to detect the violation of ergodicity of the delocalized states within the Abou-Chakra, Anderson, and Thouless recursive scheme. This result is supplemented by statistics of random wave functions extracted from exact diagonalization of the Anderson model on ensemble of disordered random regular graphs (RRG) of N sites with the connectivity K=2...
October 7, 2016: Physical Review Letters
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