keyword
MENU ▼
Read by QxMD icon Read
search

kurtosis

keyword
https://www.readbyqxmd.com/read/28208820/optimal-resonant-band-demodulation-based-on-an-improved-correlated-kurtosis-and-its-application-in-bearing-fault-diagnosis
#1
Xianglong Chen, Bingzhi Zhang, Fuzhou Feng, Pengcheng Jiang
The kurtosis-based indexes are usually used to identify the optimal resonant frequency band. However, kurtosis can only describe the strength of transient impulses, which cannot differentiate impulse noises and repetitive transient impulses cyclically generated in bearing vibration signals. As a result, it may lead to inaccurate results in identifying resonant frequency bands, in demodulating fault features and hence in fault diagnosis. In view of those drawbacks, this manuscript redefines the correlated kurtosis based on kurtosis and auto-correlative function, puts forward an improved correlated kurtosis based on squared envelope spectrum of bearing vibration signals...
February 13, 2017: Sensors
https://www.readbyqxmd.com/read/28208489/prediction-of-the-moments-in-advection-diffusion-lattice-boltzmann-method-ii-attenuation-of-the-boundary-layers-via-double-%C3%AE-bounce-back-flux-scheme
#2
Irina Ginzburg
Impact of the unphysical tangential advective-diffusion constraint of the bounce-back (BB) reflection on the impermeable solid surface is examined for the first four moments of concentration. Despite the number of recent improvements for the Neumann condition in the lattice Boltzmann method-advection-diffusion equation, the BB rule remains the only known local mass-conserving no-flux condition suitable for staircase porous geometry. We examine the closure relation of the BB rule in straight channel and cylindrical capillary analytically, and show that it excites the Knudsen-type boundary layers in the nonequilibrium solution for full-weight equilibrium stencil...
January 2017: Physical Review. E
https://www.readbyqxmd.com/read/28208379/prediction-of-the-moments-in-advection-diffusion-lattice-boltzmann-method-i-truncation-dispersion-skewness-and-kurtosis
#3
Irina Ginzburg
The effect of the heterogeneity in the soil structure or the nonuniformity of the velocity field on the modeled resident time distribution (RTD) and breakthrough curves is quantified by their moments. While the first moment provides the effective velocity, the second moment is related to the longitudinal dispersion coefficient (k_{T}) in the developed Taylor regime; the third and fourth moments are characterized by their normalized values skewness (Sk) and kurtosis (Ku), respectively. The purpose of this investigation is to examine the role of the truncation corrections of the numerical scheme in k_{T}, Sk, and Ku because of their interference with the second moment, in the form of the numerical dispersion, and in the higher-order moments, by their definition...
January 2017: Physical Review. E
https://www.readbyqxmd.com/read/28207858/non-small-cell-lung-cancer-whole-lesion-histogram-analysis-of-the-apparent-diffusion-coefficient-for-assessment-of-tumor-grade-lymphovascular-invasion-and-pleural-invasion
#4
Naoko Tsuchiya, Mariko Doai, Katsuo Usuda, Hidetaka Uramoto, Hisao Tonami
PURPOSE: Investigating the diagnostic accuracy of histogram analyses of apparent diffusion coefficient (ADC) values for determining non-small cell lung cancer (NSCLC) tumor grades, lymphovascular invasion, and pleural invasion. MATERIALS AND METHODS: We studied 60 surgically diagnosed NSCLC patients. Diffusion-weighted imaging (DWI) was performed in the axial plane using a navigator-triggered single-shot, echo-planar imaging sequence with prospective acquisition correction...
2017: PloS One
https://www.readbyqxmd.com/read/28205277/preliminary-evaluation-of-altered-brain-microstructure-in-the-emotion-cognition-region-in-children-with-haemophilia-a-a-diffusional-kurtosis-imaging-study
#5
D Hu, H Kang, Y Lv, N Zhang, L Tang, J Zhang, K Shi, R Wu, Y Peng
AIM: Using diffusional kurtosis imaging (DKI) to assess the impact of emotional disorders on microstructural changes of the brain in children with haemophilia A. MATERIALS AND METHODS: Diffusional kurtosis imaging was acquired from haemophilia A (n = 22) and controls (n = 22) using a 3T scanner. A regression analysis of frontal, cingulate, hippocampus, insula and amygdala regions of interest (ROIs) was conducted. Clinical data and results of psychological tests were collected...
February 15, 2017: Haemophilia: the Official Journal of the World Federation of Hemophilia
https://www.readbyqxmd.com/read/28199367/evaluation-of-different-mathematical-models-and-different-b-value-ranges-of-diffusion-weighted-imaging-in-peripheral-zone-prostate-cancer-detection-using-b-value-up-to-4500-s-mm2
#6
Zhaoyan Feng, Xiangde Min, Daniel J A Margolis, Caohui Duan, Yuping Chen, Vivek Kumar Sah, Nabin Chaudhary, Basen Li, Zan Ke, Peipei Zhang, Liang Wang
OBJECTIVES: To evaluate the diagnostic performance of different mathematical models and different b-value ranges of diffusion-weighted imaging (DWI) in peripheral zone prostate cancer (PZ PCa) detection. METHODS: Fifty-six patients with histologically proven PZ PCa who underwent DWI-magnetic resonance imaging (MRI) using 21 b-values (0-4500 s/mm2) were included. The mean signal intensities of the regions of interest (ROIs) placed in benign PZs and cancerous tissues on DWI images were fitted using mono-exponential, bi-exponential, stretched-exponential, and kurtosis models...
2017: PloS One
https://www.readbyqxmd.com/read/28194415/diffusion-kurtosis-imaging-detects-microstructural-changes-in-the-brain-after-acute-alcohol-intoxication-in-rats
#7
Xi-Ran Chen, Jie-Ying Zeng, Zhi-Wei Shen, Ling-Mei Kong, Wen-Bin Zheng
The aim of this study was to test the technical feasibility of diffusion kurtosis imaging (DKI) in the brain after acute alcohol intoxication. Diffusion tensor imaging (DTI) and DKI during 7.0 T MRI were performed in the frontal lobe and thalamus before and 30 min, 2 h, and 6 h after ethyl alcohol administration. Compared with controls, mean kurtosis values of the frontal lobe and thalamus first decreased by 44% and 38% within 30 min (p < 0.01 all) and then increased by 14% and 46% at 2 h (frontal lobe, p > 0...
2017: BioMed Research International
https://www.readbyqxmd.com/read/28176436/differential-microstructural-and-morphological-abnormalities-in-mild-cognitive-impairment-and-alzheimer-s-disease-evidence-from-cortical-and-deep-gray-matter
#8
Nan-Jie Gong, Chun-Chung Chan, Lam-Ming Leung, Chun-Sing Wong, Russell Dibb, Chunlei Liu
One aim of this study is to use non-Gaussian diffusion kurtosis imaging (DKI) for capturing microstructural abnormalities in gray matter of Alzheimer's disease (AD). The other aim is to compare DKI metrics against thickness of cortical gray matter and volume of deep gray matter, respectively. A cohort of 18 patients with AD, 18 patients with amnestic mild cognitive impairment (MCI), and 18 normal controls underwent morphological and DKI MR imaging. Images were investigated using regions-of-interest-based analyses for deep gray matter and vertex-wise analyses for cortical gray matter...
February 8, 2017: Human Brain Mapping
https://www.readbyqxmd.com/read/28169141/measuring-interobserver-disagreement-in-rating-diagnostic-characteristics-of-pulmonary-nodule-using-the-lung-imaging-database-consortium-and-image-database-resource-initiative
#9
Hongli Lin, Changxing Huang, Weisheng Wang, Jiawei Luo, Xuedong Yang, Yuling Liu
RATIONALE AND OBJECTIVES: The purpose of this study was to measure and analyze interobserver disagreement in rating diagnostic characteristics of pulmonary nodules on computed tomography scans using the Lung Imaging Database Consortium and Image Database Resource Initiative (LIDC/IDRI) database, and then to provide investigators with understanding the variability in rating diagnostic characteristics among radiologists. MATERIALS AND METHODS: A histogram-based accumulated nodule-level approach is proposed to measure interobserver disagreement in rating diagnostic characteristics of pulmonary nodules among radiologists...
February 3, 2017: Academic Radiology
https://www.readbyqxmd.com/read/28160039/measuring-the-apparent-diffusion-coefficient-in-primary-rectal-tumors-is-there-a-benefit-in-performing-histogram-analyses
#10
Miriam M van Heeswijk, Doenja M J Lambregts, Monique Maas, Max J Lahaye, Z Ayas, Jos M G M Slenter, Geerard L Beets, Frans C H Bakers, Regina G H Beets-Tan
PURPOSE: The apparent diffusion coefficient (ADC) is a potential prognostic imaging marker in rectal cancer. Typically, mean ADC values are used, derived from precise manual whole-volume tumor delineations by experts. The aim was first to explore whether non-precise circular delineation combined with histogram analysis can be a less cumbersome alternative to acquire similar ADC measurements and second to explore whether histogram analyses provide additional prognostic information. METHODS: Thirty-seven patients who underwent a primary staging MRI including diffusion-weighted imaging (DWI; b0, 25, 50, 100, 500, 1000; 1...
February 3, 2017: Abdominal Radiology
https://www.readbyqxmd.com/read/28151889/early-white-matter-injuries-in-patients-with-acute-carbon-monoxide-intoxication-a-tract-specific-diffusion-kurtosis-imaging-study-and-strobe-compliant-article
#11
Ping-Huei Tsai, Ming-Chung Chou, Shih-Wei Chiang, Hsiao-Wen Chung, Hua-Shan Liu, Hung-Wen Kao, Cheng-Yu Chen
Evaluation of acute white matter injuries caused by carbon monoxide (CO) poisoning can be limited by conventional magnetic resonance (MR) imaging. We aim to evaluate the feasibility of diffusion kurtosis imaging (DKI) for early detection of white matter alterations in patients with acute CO intoxication.A total of 30 subjects including 15 acute CO patients and 15 age- and sex-matched healthy volunteers were enrolled in this study. MR examinations were performed on a 3T MR scanner within 8 days after CO intoxication...
February 2017: Medicine (Baltimore)
https://www.readbyqxmd.com/read/28139225/toward-ideal-separation-by-size-exclusion-chromatography
#12
Miloš Netopilík
In analyses of polystyrene standards by size-exclusion chromatography for polymers of molecular weight about thirty thousand and higher, the separation improved with decreasing flow-rate is in accord with Giddings observation of transversal diffusion as a factor decreasing the broadening of the band broadening function. The variance of the elution curves is larger than it corresponds to dispersity M¯w/M¯n and the shape of the elution curves depends on the experimental conditions which suggests that it reflects properties of the band broadening function...
January 19, 2017: Journal of Chromatography. A
https://www.readbyqxmd.com/read/28139036/multiparametric-diffusion-weighted-imaging-in-breast-lesions-association-with-pathologic-diagnosis-and-prognostic-factors
#13
Shiteng Suo, Fang Cheng, Mengqiu Cao, Jiwen Kang, Mingyao Wang, Jia Hua, Xiaolan Hua, Lan Li, Qing Lu, Jialin Liu, Jianrong Xu
PURPOSE: To determine the utility of multiparametric diffusion-weighted imaging (DWI) including monoexponential (apparent diffusion coefficient [ADC]), biexponential (Df , Ds , and f), stretched-exponential (distributed diffusion coefficient [DDC] and α), and kurtosis (mean diffusivity [MD] and mean kurtosis [MK]) models in the differentiation and characterization of breast lesions, and assess their associations with prognostic factors in invasive breast cancer. MATERIALS AND METHODS: This study included 101 patients (44 benign and 57 malignant lesions) who underwent 3T breast multi-b-value DWI...
January 31, 2017: Journal of Magnetic Resonance Imaging: JMRI
https://www.readbyqxmd.com/read/28113791/a-robust-motion-artifact-detection-algorithm-for-accurate-detection-of-heart-rates-from-photoplethysmographic-signals-using-time-frequency-spectral-features
#14
Duy Dao, S M A Salehizadeh, Yeon Noj, Jo Woon Chong, Chae Cho, Dave Mcmanus, Chad E Darling, Yitzhak Mendelson, Ki H Chon
Motion and noise artifacts (MNAs) impose limits on the usability of the photoplethysmogram (PPG), particularly in the context of ambulatory monitoring. MNAs can distort PPG, causing erroneous estimation of physiological parameters such as heart rate (HR) and arterial oxygen saturation (SpO2). In this study we present a novel approach, "TifMA," based on using the Time-frequency spectrum of PPG to first detect the MNA-corrupted data and next discard the non-usable part of the corrupted data. The term "non-usable" refers to segments of PPG data from which the HR signal cannot be recovered accurately...
October 21, 2016: IEEE Journal of Biomedical and Health Informatics
https://www.readbyqxmd.com/read/28113317/noise-level-estimation-for-natural-images-based-on-scale-invariant-kurtosis-and-piecewise-stationarity
#15
Li Dong, Jiantao Zhou, Yuan Y Tang
Noise level estimation is crucial in many image processing applications such as blind image denoising. In this work, we propose a novel noise level estimation approach for natural images by jointly exploiting the piecewise stationarity and a regular property of the kurtosis in band-pass domains. We design a K-means based algorithm to adaptively partition an image into a series of non-overlapping regions, each of whose clean versions is assumed to be associated with a constant, but unknown kurtosis throughout scales...
December 14, 2016: IEEE Transactions on Image Processing: a Publication of the IEEE Signal Processing Society
https://www.readbyqxmd.com/read/28112048/the-influence-of-change-in-slice-thickness-on-the-accuracy-of-reconstruction-of-cranium-geometry
#16
Grzegorz Budzik, Paweł Turek, Julian Traciak
The article presents a comparative study of change in slice thickness on the accuracy of reconstruction of cranium geometry. Research was performed on 10 different patients. Digital Imaging and Communications in Medicine data were obtained on the Siemens Somatom Sensation Open 40 scanner. At the stage of reconstruction, the same parameters were utilized, while only slice thickness was changed. Modeling with voxel dimensions of 0.4 mm × 0.4 mm × 2.4 mm was chosen as the gold standard over the modeling approach comprising voxel dimensions of 0...
January 1, 2017: Proceedings of the Institution of Mechanical Engineers. Part H, Journal of Engineering in Medicine
https://www.readbyqxmd.com/read/28111394/comparison-of-analytical-values-in-diffusion-kurtosis-imaging-among-different-mri-units
#17
Shogo Tan, Koichi Ujita, Yasuhiro Fukushima, Takayuki Suto
Diffusion kurtosis imaging (DKI) is a method of analyzing restricted diffusion. Mean kurtosis (MK) is obtained from DKI. It is not known how different MRI scanners and coil systems will change MK when the same imaging parameters are used. The purpose of this study is to identify tendencies in MK when using various MRI scanners and coil systems. A total of 27 healthy volunteers were enrolled in this study. DKI was performed on the brain for each volunteer on five MRI scanner/coil system combinations using the same scan parameters...
2017: Nihon Hoshasen Gijutsu Gakkai Zasshi
https://www.readbyqxmd.com/read/28101424/detection-and-classification-of-three-class-initial-dips-from-prefrontal-cortex
#18
Amad Zafar, Keum-Shik Hong
In this paper, the use of initial dips using functional near-infrared spectroscopy (fNIRS) for brain-computer interface (BCI) is investigated. Features and window sizes for detecting initial dips are also discussed. Three mental tasks including mental arithmetic, mental counting, and puzzle solving are performed in obtaining fNIRS signals from the prefrontal cortex. Vector-based phase analysis method combined with a threshold circle, as a decision criterion, are used to detect the initial dips. Eight healthy subjects participate in experiment...
January 1, 2017: Biomedical Optics Express
https://www.readbyqxmd.com/read/28090658/analysis-of-the-effects-of-noise-dwi-sampling-and-value-of-assumed-parameters-in-diffusion-mri-models
#19
Elizabeth B Hutchinson, Alexandru V Avram, M Okan Irfanoglu, C Guan Koay, Alan S Barnett, Michal E Komlosh, Evren Özarslan, Susan C Schwerin, Sharon L Juliano, Carlo Pierpaoli
PURPOSE: This study was a systematic evaluation across different and prominent diffusion MRI models to better understand the ways in which scalar metrics are influenced by experimental factors, including experimental design (diffusion-weighted imaging [DWI] sampling) and noise. METHODS: Four diffusion MRI models-diffusion tensor imaging (DTI), diffusion kurtosis imaging (DKI), mean apparent propagator MRI (MAP-MRI), and neurite orientation dispersion and density imaging (NODDI)-were evaluated by comparing maps and histogram values of the scalar metrics generated using DWI datasets obtained in fixed mouse brain with different noise levels and DWI sampling complexity...
January 16, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28076867/identifying-host-genetic-variants-associated-with-microbiome-composition-by-testing-multiple-beta-diversity-matrices
#20
Xing Hua, James J Goedert, Maria Teresa Landi, Jianxin Shi
OBJECTIVES: Host genetics have been recently reported to affect human microbiome composition. We previously developed a statistical framework, microbiomeGWAS, to identify host genetic variants associated with microbiome composition by testing a distance matrix. However, statistical power depends on the choice of a microbiome distance matrix. To achieve more robust statistical power, we aim to extend microbiomeGWAS to test the association with many distance matrices, which are defined based on multilevel taxa abundances and phylogenetic information...
2016: Human Heredity
keyword
keyword
70065
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"