scholarly journals Intraperson Variability

1978 ◽  
Vol 15 (1-6) ◽  
pp. 49-54 ◽  
Author(s):  
D. B. Morgan
Keyword(s):  
Steady State ◽  
Total Variation ◽  
Clinical Chemistry ◽  
Single Test ◽  
Analytical Error ◽  
Analytical Technique ◽  
A Value ◽  
The Common

summary In a person in a steady state the set of values obtained for a test carried out on a series of samples will show fluctuation about a value (the setting). In practice a single test value is usually taken as an estimate of the setting. The general consequences of this approximation are discussed in relation to the various uses of data in diagnosis, and illustrated for the common measurements of clinical chemistry. The magnitude of these consequences depends on the proportion of the total variation in a group of persons which is caused by these fluctuations in the person—within-person variation (Varwp). When the proportion is high the aim should be to reduce Varwp. When Varwp is high because of analytical error, then improved analytical technique or replicate analysis is required. Otherwise standardised techniques and conditions for venepuncture or, as a last resort, repeated samplings are necessary. These problems are discussed in relation to the detection of hypokalaemia.

A System for Individualized Dosing of Intravenous Aminophylline Using a Programmable Calculator

PEDIATRICS ◽  
1984 ◽  
Vol 73 (1) ◽  
pp. 64-67
Author(s):  
J. Chris Mitsuoka ◽  
Richard J. Fleck
Keyword(s):  
Steady State ◽  
Serum Sample ◽  
Drug Exposure ◽  
Plasma Concentrations ◽  
Dose Administration ◽  
Programmable Calculator ◽  
Concentration Determination ◽  
A Value ◽  
Individualized Dosing ◽  
History Of

A program that calculates a value of clearance for an individual patient prior to reaching steady state in the early stages of aminophylline therapy is presented. The program is written for the Texas Instruments TI-59 programmable calculator and may be used with or without the PC-100C printer. The program can provide clinically useful information concerning projected plasma concentrations prior to reaching steady state with an accurate history of the dose administration and serum concentration determination. If the patient has not received xanthene therapy prior to admission, only one serum sample is required. If there has been prior drug exposure, a second serum sample is required. An iterative technique, which would be impractical to use without calculator assistance, is employed to make these determinations.

Super-Fine Structure in the Critical Flow-Rate of Critical Flow Venturi Nozzles

2002 ◽  
Author(s):  
Masahiro Ishibashi
Keyword(s):  
Fine Structure ◽  
Steady State ◽  
Discharge Coefficient ◽  
Constant Pressure ◽  
Pressure Ratio ◽  
Critical Flow ◽  
Time Intervals ◽  
Critical Flow Rate ◽  
A Value ◽  
Long Time

It is shown that critical flow Venturi nozzles need time intervals, i.e., more than five hours, to achieve steady state conditions. During these intervals, the discharge coefficient varies gradually to reach a value inherent to the pressure ratio applied. When a nozzle is suddenly put in the critical condition, its discharge coefficient is trapped at a certain value then afterwards approaches gradually to the inherent value. Primary calibrations are considered to have measured the trapped discharge coefficient, whereas nozzles in applications, where a constant pressure ratio is applied for a long time, have a discharge coefficient inherent to the pressure ratio; inherent and trapped coefficients can differ by 0.03–0.04%.

scholarly journals Level of carbon dioxide diffuse degassing from the ground of Vesuvio: comparison between extensive surveys and inferences on the gas source

2013 ◽  
Vol 56 (4) ◽  
Author(s):  
Domenico Granieri ◽  
Maria Luisa Carapezza ◽  
Rosario Avino ◽  
Stefano Caliro ◽  
Carlo Cardellini ◽  
...  
Keyword(s):  
Emission Pattern ◽  
Diffuse Degassing ◽  
Summit Area ◽  
Gas Source ◽  
A Value ◽  
Volcanic Conduit ◽  
The Common ◽  
Soil Flux ◽  
Different Sources ◽  
Tectonic Line

<p>An extensive campaign of diffuse CO<span><sub>2</sub></span> soil flux was carried out at the cone of Vesuvio in October 2006 with two main objectives: 1) to provide an estimation of CO<span><sub>2</sub></span> diffusely discharged through the soils in the summit area and 2) to evidence those sectors of the volcano where structural and morphological conditions could favour the gas output. The survey consisted of 502 measurements of soil CO<span><sub>2</sub></span> flux homogenously distributed over an area of about 1.8 km<span><sup>2</sup></span>. Results of this survey were compared with those obtained during a similar campaign carried out by Frondini et al. in 2000, from which we have taken and reinterpreted a subset of data belonging to the common investigated area. Graphical statistical analysis showed three overlapping populations in both surveys, evidencing the contribution of three different sources feeding the soil CO<span><sub>2</sub></span> degassing process. The overall CO<span><sub>2</sub></span> emission pattern of 2006 is coherent with that observed in 2000 and suggests that a value between 120 and 140 t/day of CO<span><sub>2</sub></span> is representative of the total CO<span><sub>2</sub></span> discharged by diffuse degassing from the summit area of Vesuvio. The preferential exhaling area lies in the inner crater, whose contribution resulted in 45.3% of the total CO<span><sub>2</sub></span> emission in 2006 (with 62.8 t/day) and in 57.4% (with 70.3 t/day) in 2000, although its extension is only 13% of the investigated area. This highly emissive area correlated closely with the structural discontinuities of Vesuvio cone, mainly suggesting that the NW-SE trending tectonic line is actually an active fault leaking deep gas to the bottom of the crater. The drainage action of the fault could be enhanced by the “aspiration” effect of the volcanic conduit.</p>

scholarly journals Personalized Reference Intervals in Laboratory Medicine: A New Model Based on Within-Subject Biological Variation

2020 ◽  
Author(s):  
Abdurrahman Coşkun ◽  
Sverre Sandberg ◽  
Ibrahim Unsal ◽  
Coskun Cavusoglu ◽  
Mustafa Serteser ◽  
...  
Keyword(s):  
Steady State ◽  
Personalized Medicine ◽  
Clinical Chemistry ◽  
Reference Interval ◽  
Reference Intervals ◽  
Biological Variation ◽  
Test Results ◽  
Steady State Condition ◽  
Laboratory Test Results ◽  
Measurement Results

Abstract Background The concept of personalized medicine has received widespread attention in the last decade. However, personalized medicine depends on correct diagnosis and monitoring of patients, for which personalized reference intervals for laboratory tests may be beneficial. In this study, we propose a simple model to generate personalized reference intervals based on historical, previously analyzed results, and data on analytical and within-subject biological variation. Methods A model using estimates of analytical and within-subject biological variation and previous test results was developed. We modeled the effect of adding an increasing number of measurement results on the estimation of the personal reference interval. We then used laboratory test results from 784 adult patients (&gt;18 years) considered to be in a steady-state condition to calculate personalized reference intervals for 27 commonly requested clinical chemistry and hematology measurands. Results Increasing the number of measurements had little impact on the total variation around the true homeostatic set point and using ≥3 previous measurement results delivered robust personalized reference intervals. The personalized reference intervals of the study participants were different from one another and, as expected, located within the common reference interval. However, in general they made up only a small proportion of the population-based reference interval. Conclusions Our study shows that, if using results from patients in steady state, only a few previous test results and reliable estimates of within-subject biological variation are required to calculate personalized reference intervals. This may be highly valuable for diagnosing patients as well as for follow-up and treatment.

A Performance Study of Image Quality Attributes on Smoothened Image Obtained by Anisotropic Diffusion-Based Models

2020 ◽  
pp. 100-120
Author(s):  
Muthukumaran Malarvel ◽  
Sivakumar S.
Keyword(s):  
Image Quality ◽  
Total Variation ◽  
Anisotropic Diffusion ◽  
Diffusion Method ◽  
Synthetic Image ◽  
Noisy Image ◽  
Performance Study ◽  
Eigen Value ◽  
Edge Quality ◽  
The Common

Image acquisition systems usually acquire images with distortions due to various factors associated with digitization processes. Poisson is one of the common types of noises present in the image, and it distorts the fine features. Hence, it is necessary to denoise the noisy image by smoothing it to extract the features with fine details. Among the denoising methods, anisotropic diffusion method provides more adequate results. In this chapter, the authors dealt with existing models such as Perona-Malik (PM), total variation, Tsai, Chao, Chao TFT, difference eigen value PM, adaptive PM, modified PM, and Maiseli models. The performances of the models were tested on synthetic image added with the Poisson noise. Quality metrics are used to quantify and to ensure the smoothness of the resultant images. However, in order to ensure the completeness of the denoising effect, the qualitative attributes such as sharpness, blurriness, blockiness, edge quality, and false contouring are considered on smoothened images. The analysis results are shown the completeness of the denoising effect of the models.

scholarly journals Evaluation of the clinical chemistry tests analytical performance by using different models and specifications

2019 ◽  
Vol 45 (1) ◽  
pp. 11-18
Author(s):  
Murat Keleş
Keyword(s):  
Quality Management ◽  
Measurement Uncertainty ◽  
Goal Setting ◽  
Clinical Chemistry ◽  
Biological Variation ◽  
Analytical Performance ◽  
Analytical Quality ◽  
Analytical Error ◽  
Circular Letter ◽  
Clinical Chemistry Tests

Abstract Background The importance of managing analytical quality in clinical laboratories is known. Goal-setting models are critical for analytical quality management, along with correctly implemented error models. However, the methods used to determine analytical performance and more importantly, the relevant analytical quality goals are open to discussion. Our aim was to compare the analytical performance characteristics of routine clinical chemistry tests with different goal-setting models which was proposed by various establishments. In addition, to provide a perspective to Turkish total analytical error (TAE) circular letter that compulsory to calculate from 2016. Materials and methods This study was performed by the data obtained from the internal and external quality control of clinical chemistry tests which were measured by Roche Cobas c501 biochemistry analyzer. TAE calculated with TAE% = 1.65 ×(CV%) + Bias% formula. Nordtest uncertainty model was used in the calculation of measurement uncertainty (MU). In this context, total analytical error was evaluated with biological variation (BV), RCPA, CLIA and Turkish allowable total error (ATE) goals. Measurement uncertainty was evaluated with only permissible measurement uncertainty (pU%) goal. Results In our study, RCPA goals are the most stringent, followed by the BVEuBIVAS, BVRicos, pU%, CLIA and finally the ATETurkey goals coming in last. In cumulatively, BVEuBIVAS goals were 18.3% lower than BVRicos for evaluated parameters. Conclusion The balance between applicability and analytical assurance of goals should be well ensured when determining goal-setting models. Circular letter (2016/18) creates awareness to the analytical quality management but still open to development. Biological variation dependent total allowable error model never designed to be used as benchmarks for measurement uncertainty and it is not methodologically appropriate for assessing measurement uncertainty which was estimated by the Nordtest method. Also considered that, the use of “permissible MU” is more methodologically appropriate in the evaluation of measurement uncertainty.

Kinetics of the hydrolysis of cellobiose and p-nitrophenyl-β-D-glucoside by cellobiase of Trichoderma viride

1977 ◽  
Vol 55 (1) ◽  
pp. 19-26 ◽  
Author(s):  
R. James Maguire
Keyword(s):  
Steady State ◽  
Trichoderma Viride ◽  
Solution Temperature ◽  
Temperature Range ◽  
A Value ◽  
Steady State Kinetics ◽  
Decreasing Ph ◽  
Ph Curve ◽  
Kinetics Of ◽  
Hydrolysis Of

Cellobiase has been isolated from the crude cellulase mixture of enzymes of Trichoderma viride using column chromatographic and ion-exchange methods. The steady-state kinetics of the hydrolysis of cellobiose have been investigated as a function of cellobiose and glucose concentrations, pH of the solution, temperature, and dielectric constant, using isopropanol–buffer mixtures. The results show that (i) there is a marked activation of the reaction by initial glucose concentrations of 4 × 10−3 M to 9 × 10−2 M and strong inhibition of the reaction at higher initial concentrations, (ii) the log rate – pH curve has a maximum at pH 5.2 and enzyme pK values of 3.5 and 6.8, (iii) the energy of activation at pH 5.1 is 10.2 kcal mol−1 over the temperature range 5–56 °C, and (iv) the rate decreases from 0 to 20% (v/v) isopropanol.The hydrolysis by cellobiase (EC 3.2.1.21) of p-nitrophenyl-β-D-glucoside was examined by pre-steady-state methods in which [Formula: see text], and by steady-state methods as a function of pH and temperature. The results show (i) a value for k2 of 21 s−1 at pH 7.0 (where k2 is the rate constant for the second step in the assumed two-intermediate mechanism [Formula: see text]) (ii) a log rate–pH curve, significantly different from that for hydrolysis of cellobiose, in which the rate increases with decreasing pH below pH 4.5, is constant in the region pH 4.5–6, and decreases above pH 6 (exhibiting an enzyme pK value of 7.3), and (iii) an activation energy of 12.5 kcal mol−1 at pH 5.7 over the temperature range 10–60 °C.

scholarly journals The future of clinical chemistry and its role in healthcare: a report of the Athena Society

1996 ◽  
Vol 42 (1) ◽  
pp. 96-101 ◽  
Keyword(s):  
Clinical Laboratory ◽  
Clinical Chemistry ◽  
Analytical Techniques ◽  
Leadership Role ◽  
Professional Organizations ◽  
Clinical Laboratory Science ◽  
Disciplinary Expertise ◽  
New Type ◽  
The Common ◽  
The Individual

Abstract Given the omnipresent cost-containment environment in which clinical chemists now work, they must adapt to a host of changed conditions and new pressures. Much of the onus of adapting is on the individual who must assume a different attitude to his or her work. The American Association for Clinical Chemistry can, and should, take a leadership role in developing a new type of laboratory director by working with other professional organizations in the clinical laboratory field to create training programs and retraining programs for existing clinical laboratory scientists, which will equip them for broader scientific and managerial responsibilities than hitherto. AACC needs to develop alliances with its sister organizations so that the common issues are addressed collectively rather than competitively. The scope of clinical chemistry must expand into areas other than traditional clinical chemistry, e.g., microbiology, immunology, certain aspects of hematology (including coagulation), and even aspects of blood banking. The former clinical chemist needs to become a clinical laboratory scientist and promote him- or herself as having cross-disciplinary expertise in analytical techniques and automation, which are the common threads linking all branches of clinical laboratory science.

Coupling and Cooperative Up-conversion Coefficients in Er-doped Si Nanocrystals

2003 ◽  
Vol 770 ◽  
Author(s):  
Domenico Pacifici ◽  
Giorgia Franzò ◽  
Fabio Iacona ◽  
Francesco Priolo
Keyword(s):  
Steady State ◽  
Energy Level ◽  
Energy Level Scheme ◽  
Time Resolved ◽  
A Value ◽  
Si Nanocrystals ◽  
Si Nanocrystal ◽  
Conversion Coefficients ◽  
Quantitative Understanding ◽  
Er Doped

AbstractIn the present work, a quantitative understanding of the Er-doped Si nanocrystals interaction is reported. We present a model based on an energy level scheme taking into account the coupling between each Si nanocrystal and the neighboring Er ions. By fitting the steady state and time resolved luminescence signals at both the 1.54 and 0.98 μm Er lines we were able to determine a value of 3×10-15 cm3 s-1 for the coupling coefficient. Moreover, a strong cooperative up-conversion mechanism, active between two excited Er ions and characterized by a coefficient of 7×10-17 cm3 s-1, will be shown to be active in the system, demonstrating that each Si nanocrystal can actually excite more than one Er ion.

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