Search results for "Coefficient of Variation"
showing 10 items of 77 documents
Within-visit BP variability, cardiovascular risk factors, and BP control in central and eastern Europe: findings from the BP-CARE study.
2015
INTRODUCTION AND OBJECTIVE Blood pressure variability (BPV) within 24 h or between visits has been found to represent an independent risk factor for cardiovascular disease. The present study was aimed at determining whether a clinical significance can be given also to the BP variations occurring within a single clinical visit. METHODS BPV was quantified as coefficient of variation and as standard deviation (SD) of the mean of three systolic SBP values within a visit in the context of a large-cross subclinical survey (BP-CARE) of treated hypertensive patients living in Eastern European countries. The study population was divided into coefficient of variation and SD quartiles and for each qua…
Evaluation of 6 biometers based on different optical technologies
2021
This study shows that optical biometers based on different technologies provide repeatable measurements for different ocular parameters and, when compared, statistically significant differences between them were found when measuring most parameters.
Study of Glycemic Variability Through Time Series Analyses (Detrended Fluctuation Analysis and Poincaré Plot) in Children and Adolescents with Type 1…
2016
Time series analysis provides information on blood glucose dynamics that is unattainable with conventional glycemic variability (GV) indices. To date, no studies have been published on these parameters in pediatric patients with type 1 diabetes. Our aim is to evaluate the relationship between time series analysis and conventional GV indices, and glycosylated hemoglobin (HbA1c) levels.This is a transversal study of 41 children and adolescents with type 1 diabetes. Glucose monitoring was carried out continuously for 72 h to study the following GV indices: standard deviation (SD) of glucose levels (mg/dL), coefficient of variation (%), interquartile range (IQR; mg/dL), mean amplitude of the la…
Validation of a high-performance chromatographic method for determination of cefotaxime in biological samples
1999
An analytical method for detecting and quantifying cefotaxime in plasma and several tissues is described. The method was developed and validated using plasma and tissues of rats. The samples were analyzed by reversed phase liquid chromatography (HPLC) with UV detection (254 nm). Calibration graphs showed a linear correlation (r > 0.999) over the concentration ranges of 0.5–200 μg/mL and 1.25–25 μg/g for plasma and tissues, respectively. The recovery of cefotaxime from plasma standards prepared at the concentrations of 25 μg/mL and 100 μg/mL was 98.5 ± 3.5% and 101.8 ± 2.2%, respectively. The recovery of cefotaxime from tissue standards of liver, fat and muscle, prepared at the concentration…
Multicenter stability of diffusion tensor imaging measures: a European clinical and physical phantom study.
2011
Diffusion tensor imaging (DTI) detects white matter damage in neuro-psychiatric disorders, but data on reliability of DTI measures across more than two scanners are still missing. In this study we assessed multicenter reproducibility of DTI acquisitions based on a physical phantom as well as brain scans across 16 scanners. In addition, we performed DTI scans in a group of 26 patients with clinically probable Alzheimer's disease (AD) and 12 healthy elderly controls at one single center. We determined the variability of fractional anisotropy (FA) measures using manually placed regions of interest as well as automated tract based spatial statistics and deformation based analysis. The coefficie…
Granulometric moments and corneal endothelium status
2001
Abstract Specular microscopy is a common practice in Ophthalmology. The corneal endothelium status is usually evaluated by means of the density, the hexagonality, the mean, the standard deviation and the coefficient of variation of cell areas. We propose to replace the cell area moments by the corresponding moments of a different probability distribution, the granulometric size distribution associated to a disc. All cells touching the frame are ignored by the area moments but used by the granulometric moments. Twenty images have been analyzed. When the size of the focused region is reduced, the area moments show a greater variation than the corresponding granulometric moments.
A granulometric analysis of specular microscopy images of human corneal endothelia
2005
The inner layer of the human cornea, called the corneal endothelium, plays an important role in the maintenance of corneal transparency. Specular microscopy is the most widely used technique to study the corneal endothelium in vivo. Improvements in technology have allowed us to obtain good quality specular images, but the detection and quantification of small size-shape cell changes is not obvious, specially when the physician wants to evaluate endothelial cell changes after some surgical procedures. This paper proposes a methodology to analyze specular microscopy images. Every corneal endothelium is described by means of different cumulative distribution functions or some moments (mean, st…
Measuring the Spatial Homogeneity in Corneal Endotheliums by Means of a Randomization Test
1999
Quantification of regularity of cell sizes and the spatial arrangement of cells in corneal endotheliums becomes of a great importance associated to stress situations such as cataract surgery, corneal transplantation or implantation of intra-ocular lenses. A new index of regularity of the spatial distribution of cell sizes in corneal endotheliums is proposed. The corneal endothelium is described by means of a spatial marked point pattern (the cell centroids marked with the cell areas). The hypothesis of no dependency between mark and locations is tested by a Monte Carlo test. The new index is the p-value of the test validating the hypothesis. Pairs of endotheliums from different eyes of the …
Real-time quantitative PCR of Staphylococcus aureus and application in restaurant meals.
2006
Staphylococcus aureus is considered the second most common pathogen to cause outbreaks of food poisoning, exceeded only by Campylobacter. Consumption of foods containing this microorganism is often identified as the cause of illness. In this study, a rapid, reliable, and sensitive real-time quantitative PCR was developed and compared with conventional culture methods. Real-time quantitative PCR was carried out by purifying DNA extracts of S. aureus with a Staphylococcus sample preparation kit and quantifying it in the LightCycler system with hybridization probes. The assay was linear from a range of 10 to 10(6) S. aureus cells (r2 > 0.997). The PCR reaction presented an efficiency of >85%. …
Fourier-transform infrared determination of nicotine in tobacco samples by transmittance measurements after leaching with CHCl3
1998
Abstract A new procedure is proposed for the FT-IR spectrometric determination of nicotine in tobacco. The method is based on the extraction of nicotine in CHCl 3 from tobacco samples, wetted with an aqueous solution of NH 3 (0.1 M), and the measurement of absorbance in the stopped-flow mode at 1316 cm −1 , using a spectral baseline correction established from 1334 to 1300 cm −1 . The procedure developed does not requires a complex sample preparation, and provides a limit of detection of 0.045 mg ml −1 nicotine, a sampling frequency of 3.3 h −1 and a coefficient of variation of 0.3% for five independent measurements of a tobacco sample with a nicotine content of 1.5% w/w. The accuracy of th…