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Coefficient of variation

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https://www.readbyqxmd.com/read/28434071/repeatability-and-agreement-of-central-corneal-thickness-measurement-with-non-contact-methods-a-comparative-study
#1
Tarannum Mansoori, Nagalla Balakrishna
PURPOSE: To compare the central corneal thickness (CCT) measurements and reliability of RTVue XR-100 anterior segment optical coherence tomography (AS-OCT), AL-scan optical biometer and Schwind Sirius anterior segment analysis system. METHODS: The CCT was measured in one hundred and twenty-seven eyes of 127 healthy subjects with AS-OCT, AL-scan and Sirius system. Mean CCT was compared among the instruments, and the level of agreement was assessed using Bland-Altman plots...
April 22, 2017: International Ophthalmology
https://www.readbyqxmd.com/read/28433988/comparison-of-choriocapillaris-flow-measurements-between-two-optical-coherence-tomography-angiography-devices
#2
Jost L Lauermann, Peter Heiduschka, Pieter Nelis, Maximilian Treder, Maged Alnawaiseh, Christoph R Clemens, Nicole Eter, Florian Alten
PURPOSE: To evaluate choriocapillaris (CC) perfusion in healthy subjects using 2 different optical coherence tomography angiography (OCT-A) devices. PROCEDURES: Macular OCT-A imaging (36 eyes of 36 subjects) was performed using Optovue AngioVue and Zeiss AngioPlex devices. CC decorrelation signal index was assessed, and CC data were analyzed regarding intra-device variability, inter-device correlation, age, signal strength, and fields of view. RESULTS: The intra-device variability of CC measurements in the 3 × 3 mm2 field was 5...
April 22, 2017: Ophthalmologica. Journal International D'ophtalmologie
https://www.readbyqxmd.com/read/28433868/effects-of-attentional-focus-on-walking-stability-in-elderly
#3
Jonathan L A de Melker Worms, John F Stins, Erwin E H van Wegen, Sabine M P Verschueren, Peter J Beek, Ian D Loram
INTRODUCTION: Balance performance in the elderly is related to psychological factors such as attentional focus. We investigated the effects of internal vs. external focus of attention and fall history on walking stability in healthy older adults. METHOD: Walking stability of twenty-eight healthy older adults was assessed by applying random unilateral decelerations on a split-belt treadmill and analysing the resulting balance recovery movements. The internal focus instruction was: concentrate on the movement of your legs, whereas the external focus instruction was: concentrate on the movement of the treadmill...
April 4, 2017: Gait & Posture
https://www.readbyqxmd.com/read/28433037/directed-motion-from-particle-size-oscillations-inside-an-asymmetric-channel
#4
Yurii A Makhnovskii, Sheh-Yi Sheu, Dah-Yen Yang, Sheng Hsien Lin
The motion of a spherical Brownian particle in an asymmetric periodic channel is considered. Under an external periodic stimulus, the particle switches between two states with different particle radius, every half-period. Using Brownian dynamics simulations, we show that the particle size oscillation, combined with the asymmetry of the channel, induces a drift along the channel axis, directed towards the steeper wall of the channel. The oscillation of the particle size is accompanied by a time variation of the space accessible to the particle and by an oscillation of its diffusion coefficient...
April 21, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28433026/variational-koopman-models-slow-collective-variables-and-molecular-kinetics-from-short-off-equilibrium-simulations
#5
Hao Wu, Feliks Nüske, Fabian Paul, Stefan Klus, Péter Koltai, Frank Noé
Markov state models (MSMs) and master equation models are popular approaches to approximate molecular kinetics, equilibria, metastable states, and reaction coordinates in terms of a state space discretization usually obtained by clustering. Recently, a powerful generalization of MSMs has been introduced, the variational approach conformation dynamics/molecular kinetics (VAC) and its special case the time-lagged independent component analysis (TICA), which allow us to approximate slow collective variables and molecular kinetics by linear combinations of smooth basis functions or order parameters...
April 21, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28432897/hba1c-variability-in-type-2-diabetes-is-associated-with-the-occurrence-of-new-onset-albuminuria-within-three-years
#6
Sreemanee Raaj Dorajoo, Joceline Shi Ling Ng, Jessica Hui Fen Goh, Su Chi Lim, Chun Wei Yap, Alexandre Chan, Joyce Yu Chia Lee
AIMS: To evaluate the association between HbA1c coefficient of variation (HbA1c-CV) and 3-year new-onset albuminuria risk. METHODS: A retrospective cohort study involving 716 normoalbuminuric type 2 diabetes patients was conducted between 2010 and 2014. HbA1c-CV was used to categorize patients into low, moderate or high variability groups. Multivariate logistic models were constructed and validated. Integrated discrimination (IDI) and net reclassification (NRI) improvement indices were used to quantify the added predictive value of HbA1c-CV...
February 14, 2017: Diabetes Research and Clinical Practice
https://www.readbyqxmd.com/read/28432895/predictive-ability-of-visit-to-visit-variability-in-hba1c-and-systolic-blood-pressure-for-the-development-of-microalbuminuria-and-retinopathy-in-people-with-type-2-diabetes
#7
Toshiko Takao, Machi Suka, Hiroyuki Yanagisawa, Yutaka Matsuyama, Yasuhiko Iwamoto
AIMS: We explored whether visit-to-visit variability in both glycated hemoglobin (HbA1c) and systolic blood pressure (SBP) simultaneously predicted the development of microalbuminuria and retinopathy, and whether the predictive ability of these measurements changed according to mean HbA1c and SBP levels in people with type 2 diabetes. METHODS: A retrospective observational cohort study was conducted on 243 type 2 diabetes patients with normoalbuminuria and 486 without retinopathy at the first visit and within 1year thereafter...
April 7, 2017: Diabetes Research and Clinical Practice
https://www.readbyqxmd.com/read/28432780/single-subject-independent-component-analysis-based-intensity-normalization-in-non-quantitative-multi-modal-structural-mri
#8
Sebastian Papazoglou, Jens Würfel, Friedemann Paul, Alexander U Brandt, Michael Scheel
Non-quantitative MRI is prone to intersubject intensity variation rendering signal intensity level based analyses limited. Here, we propose a method that fuses non-quantitative routine T1-weighted (T1w), T2w, and T2w fluid-saturated inversion recovery sequences using independent component analysis and validate it on age and sex matched healthy controls. The proposed method leads to consistent and independent components with a significantly reduced coefficient-of-variation across subjects, suggesting potential to serve as automatic intensity normalization and thus to enhance the power of intensity based statistical analyses...
April 22, 2017: Human Brain Mapping
https://www.readbyqxmd.com/read/28432612/evaluation-of-the-analgesia-nociception-index-ani-in-healthy-awake-volunteers
#9
Rami Issa, Marco Julien, Elizabeth Décary, Olivier Verdonck, Louis-Philippe Fortier, Pierre Drolet, Philippe Richebé
BACKGROUND: Analgesia might be evaluated with simple changes in vital signs, a non-specific and non-sensitive method. Heart rate variability (HRV) correlates with autonomous nervous system activity and can be used to evaluate painful stimuli. Heart rate variability is then transformed into a numeric scale called the analgesia nociception index (ANI), where higher values represent predominant parasympathetic tone, thus low nociception. Under general anesthesia, the ANI decreases following painful stimuli and increases after administration of analgesia, but significant interindividual variability is present...
April 21, 2017: Canadian Journal of Anaesthesia, Journal Canadien D'anesthésie
https://www.readbyqxmd.com/read/28432423/note-on-the-coefficient-of-variations-of-neuronal-spike-trains
#10
Johannes Lengler, Angelika Steger
It is known that many neurons in the brain show spike trains with a coefficient of variation (CV) of the interspike times of approximately 1, thus resembling the properties of Poisson spike trains. Computational studies have been able to reproduce this phenomenon. However, the underlying models were too complex to be examined analytically. In this paper, we offer a simple model that shows the same effect but is accessible to an analytic treatment. The model is a random walk model with a reflecting barrier; we give explicit formulas for the CV in the regime of excess inhibition...
April 21, 2017: Biological Cybernetics
https://www.readbyqxmd.com/read/28430222/impact-of-partial-coherence-on-the-apparent-optical-transfer-function-derived-from-the-response-to-amplitude-edges
#11
S Mojtaba Shakeri, Lucas J van Vliet, Sjoerd Stallinga
We present an investigation of the impact of partial coherence on optical imaging systems with the focus on whole slide imaging (WSI) systems for digital pathology. The investigation is based on the analysis of the edge response of the optical system, which gives rise to an apparent optical transfer function (OTF) that can be linked to two elementary complex functions Q and U. The function Q is directly related to the transmission cross coefficient (TCC) and can be identified with the performance function first introduced by Kintner and Sillitto...
April 20, 2017: Applied Optics
https://www.readbyqxmd.com/read/28429598/preliminary-clinical-validation-of-a-differential-correction-method-for-improving-measurement-accuracy-in-noninvasive-measurement-of-blood-glucose-using-near-infrared-spectroscopy
#12
Guang Han, Xuyao Yu, Dandan Xia, Rong Liu, Jin Liu, Kexin Xu
One of the main challenges in the noninvasive sensing of blood glucose by near-infrared (NIR) spectroscopy is the background variations from light source drift, sweating, and temperature change at the human-machine interface. In this paper, a differential correction method based on the spectra from the floating-reference position and measuring position is proposed to eliminate these spectral variations from background interferences. Its effectiveness was validated by in vitro and in vivo experiments in which the diffuse reflectance of intralipid solutions and human skin was collected at the source distances of 0...
January 1, 2017: Applied Spectroscopy
https://www.readbyqxmd.com/read/28429448/white-matter-microstructure-variations-contribute-to-neurological-soft-signs-in-healthy-adults
#13
Dusan Hirjak, Philipp A Thomann, Robert C Wolf, Katharina M Kubera, Caspar Goch, Jan Hering, Klaus H Maier-Hein
OBJECTIVE: Neurological soft signs (NSS) are core features of psychiatric disorders with significant neurodevelopmental origin. However, it is unclear whether NSS correlates are associated with neuropathological processes underlying the disease or if they are confounded by medication. Given that NSS are also present in healthy persons (HP), investigating HP could reveal NSS correlates, which are not biased by disease-specific processes or drug treatment. Therefore, we used a combination of diffusion MRI analysis tools to provide a framework of specific white matter (WM) microstructure variations underlying NSS in HP...
April 21, 2017: Human Brain Mapping
https://www.readbyqxmd.com/read/28428849/species-distribution-models-predict-temporal-but-not-spatial-variation-in-forest-growth
#14
Ernst van der Maaten, Andreas Hamann, Marieke van der Maaten-Theunissen, Aldo Bergsma, Geerten Hengeveld, Ron van Lammeren, Frits Mohren, Gert-Jan Nabuurs, Renske Terhürne, Frank Sterck
Bioclimate envelope models have been widely used to illustrate the discrepancy between current species distributions and their potential habitat under climate change. However, the realism and correct interpretation of such projections has been the subject of considerable discussion. Here, we investigate whether climate suitability predictions correlate to tree growth, measured in permanent inventory plots and inferred from tree-ring records. We use the ensemble classifier RandomForest and species occurrence data from ~200,000 inventory plots to build species distribution models for four important European forestry species: Norway spruce, Scots pine, European beech, and pedunculate oak...
April 2017: Ecology and Evolution
https://www.readbyqxmd.com/read/28428836/muscle-function-and-fatigability-of-trunk-flexors-in-males-and-females
#15
Rita E Deering, Jonathon W Senefeld, Tatyana Pashibin, Donald A Neumann, Sandra K Hunter
BACKGROUND: Optimal function of the abdominal muscles is necessary for several life functions including lifting and carrying tasks. Sex differences in strength and fatigability are established for many limb muscles and back extensor muscles, but it is unknown if sex differences exist for the abdominal muscles despite their functional importance. METHODS: Eighteen females (24.3 ± 4.8 years) and 15 males (24.1 ± 6.6 years) performed (1) isometric trunk flexion maximal voluntary contractions (MVCs) in a range of trunk positions to establish a torque-angle curve and (2) submaximal (50% MVC), intermittent isometric contraction (6 s on, 4 s off) until task failure to determine fatigability of the trunk flexor muscles...
2017: Biology of Sex Differences
https://www.readbyqxmd.com/read/28428241/heralds-of-parallel-ms-data-independent-acquisition-surpassing-sequential-identification-of-data-dependent-acquisition-in-proteomics
#16
Roland Bruderer, Oliver Martin Bernhardt, Tejas Gandhi, Yue Xuan, Julia Sondermann, Manuela Schmidt, David Gomez-Varela, Lukas Reiter
Comprehensive, reproducible and precise analysis of large sample cohorts is one of the key objectives of quantitative proteomics. Here, we present an implementation of data-independent acquisition using its parallel acquisition nature that surpasses the serial limitation of data-dependent acquisition on a quadrupole ultra-high field Orbitrap mass spectrometer. In deep single shot data-independent acquisition, we quantified over 7,500 proteins of human cell lines and 9,000 proteins of mouse tissues, with fewer than 2...
April 20, 2017: Molecular & Cellular Proteomics: MCP
https://www.readbyqxmd.com/read/28428213/clinically-feasible-microstructural-mri-to-quantify-cervical-spinal-cord-tissue-injury-using-dti-mt-and-t2-weighted-imaging-assessment-of-normative-data-and-reliability
#17
A R Martin, B De Leener, J Cohen-Adad, D W Cadotte, S Kalsi-Ryan, S F Lange, L Tetreault, A Nouri, A Crawley, D J Mikulis, H Ginsberg, M G Fehlings
BACKGROUND AND PURPOSE: DTI, magnetization transfer, T2*-weighted imaging, and cross-sectional area can quantify aspects of spinal cord microstructure. However, clinical adoption remains elusive due to complex acquisitions, cumbersome analysis, limited reliability, and wide ranges of normal values. We propose a simple multiparametric protocol with automated analysis and report normative data, analysis of confounding variables, and reliability. MATERIALS AND METHODS: Forty healthy subjects underwent T2WI, DTI, magnetization transfer, and T2*WI at 3T in <35 minutes using standard hardware and pulse sequences...
April 20, 2017: AJNR. American Journal of Neuroradiology
https://www.readbyqxmd.com/read/28427838/stratification-strategy-for-evaluating-the-influence-of-diabetes-complication-severity-index-on-the-risk-of-hospitalization-a-record-linkage-data-in-western-australia
#18
Ninh Thi Ha, Mark Harris, Suzanne Robinson, David Preen, Rachael Moorin
OBJECTIVE: This study aimed to develop a risk stratification strategy for evaluating the relationship between complications of diabetes and the risk of diabetic-related hospitalization to accurately classify diabetes severity. METHODS: The study used administrative health records for 40,624 individuals with diabetes aged ≥18years in Western Australian. The adapted Diabetes Complication Severity Index (DCSI), socio-demographic and clinical characteristics were used in random effects negative binomial and threshold effect models to determine the optimal stratification strategy for diabetes severity based on the homogeneity of the risk of hospitalization in response to variation of the DCSI...
April 5, 2017: Journal of Diabetes and its Complications
https://www.readbyqxmd.com/read/28427301/corneal-endothelial-changes-in-long-term-cannabinoid-users
#19
Nihat Polat, Birgul Cumurcu, Tongabay Cumurcu, İlknur Tuncer
PURPOSE: The aim of this study was to evaluate the effects of long-term cannabis use on the corneal endothelial cells with the specular microscopy. METHODS: The study enrolled 28 eyes of 28 patients diagnosed with cannabinoid use disorder. The cannabinoid group was selected among patients who had been using the substance for 3 days or more per week over the past 1 year. 32 eyes of 32 age- and sex-matched healthy individuals enrolled as control group in the study...
April 20, 2017: Cutaneous and Ocular Toxicology
https://www.readbyqxmd.com/read/28426775/dynamic-behaviors-of-a-modified-sir-model-in-epidemic-diseases-using-nonlinear-incidence-and-recovery-rates
#20
Gui-Hua Li, Yong-Xin Zhang
The transmission of infectious diseases has been studied by mathematical methods since 1760s, among which SIR model shows its advantage in its epidemiological description of spread mechanisms. Here we established a modified SIR model with nonlinear incidence and recovery rates, to understand the influence by any government intervention and hospitalization condition variation in the spread of diseases. By analyzing the existence and stability of the equilibria, we found that the basic reproduction number [Formula: see text] is not a threshold parameter, and our model undergoes backward bifurcation when there is limited number of hospital beds...
2017: PloS One
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