18 A Mathematical Model that Evaluates the Effect of Circadian Rhythms in the Activities of Several Enzymes on Their Average Coefficient of Variation

2015 ◽  
pp. 107-111
Author(s):  
R R Delongchamp ◽  
R J Feuers ◽  
L E Scheving
Keyword(s):  
Mathematical Model ◽  
Circadian Rhythms ◽  
Coefficient Of Variation ◽  
Average Coefficient

Collaborative Study of the Extraction of Plant Sterols from Adulterated Butter Oil Using a Digitonin-impregnated Celite Column

1970 ◽  
Vol 53 (3) ◽  
pp. 535-538
Author(s):  
Denis E Lacroix
Keyword(s):  
Liquid Chromatography ◽  
Vegetable Oil ◽  
Coefficient Of Variation ◽  
Collaborative Study ◽  
Screening Method ◽  
Rapid Screening ◽  
Gas Liquid Chromatography ◽  
Butter Oil ◽  
Average Coefficient ◽  
Rapid Screening Method

Abstract A rapid screening method for the analysis of the phytosterol, β-sitosterol, in butter oil adulterated with vegetable oil has been studied collaboratively. The sterols are removed from the adulterated butter oil by passing the sample through a digitonin-impregnated Celite 545 column, eluting the sterols with dimethyl sulfoxide, and analyzing the eluate for β-sitosterol by gas-liquid chromatography using a 3% JXR column. The average coefficient of variation for those samples containing more than 4 mg β-sitosterol/100 g adulterated butter oil is 12.6%. Therefore, β-sitosterol can be used as an index to qualitatively detect vegetable oil adulteration of butter oil.

Extraction of Chlorinated Hydrocarbon Insecticides from Soil: Collaborative Study

1974 ◽  
Vol 57 (3) ◽  
pp. 604-609
Author(s):  
Edwin A Woolson
Keyword(s):  
Coefficient Of Variation ◽  
Collaborative Study ◽  
Chlorinated Hydrocarbon ◽  
Spiked Sample ◽  
Average Coefficient

Abstract Soil premoistened with 0.2M NH4C1 was shaken with hexane-acetone (1+1) to extract chlorinated hydrocarbon insecticides. Standard AOAC methods (29.014 and 29.017) were used for cleanup and detection of residues in the extract. Seven laboratories analyzed 3 soil unknown samples which contained 6 added insecticides each (at a range of 0.24 to 6.18 ppm) and a spike-and-recovery sample which contained 10 insecticides. Recovery from the spiked sample averaged 9 1% (86-100%) of the added insecticides, with an average coefficient of variation of 13.54%. Recovery from the 3 unknown samples averaged 88% (69-118%) with a coefficient of variation of 12.84%. The method has been adopted as official first action.

Beating Yourself: How Do Runners Improve Their Own Records?

2020 ◽  
Vol 15 (3) ◽  
pp. 437-440 ◽  
Author(s):  
Carl Foster ◽  
Jos J. de Koning ◽  
Christian Thiel ◽  
Bram Versteeg ◽  
Daniel A. Boullosa ◽  
...  
Keyword(s):  
Coefficient Of Variation ◽  
Mean Velocity ◽  
Cross Sectional ◽  
Pacing Strategy ◽  
Average Coefficient ◽  
Before And After ◽  
Cross Sectional Studies ◽  
World Records ◽  
Elite Runners

Background: Pacing studies suggest the distribution of effort for optimizing performance. Cross-sectional studies of 1-mile world records (WRs) suggest that WR progression includes a smaller coefficient of variation of velocity. Purpose: This study evaluates whether intraindividual pacing used by elite runners to break their own WR (1 mile, 5 km, and 10 km) is related to the evolution of pacing strategy. We provide supportive data from analysis in subelite runners. Methods: Men’s WR performances (with 400-m or 1-km splits) in 1 mile, 5 km, and 10 km were retrieved from the IAAF database (from 1924 to present). Data were analyzed relative to pacing pattern when a runner improved their own WR. Similar analyses are presented for 10-km performance in subelite runners before and after intensified training. Results: WR performance was improved in 1 mile (mean [SD]: 3:59.4 [11.2] to 3:57.2 [8.6]), 5 km (13:27 [0:33] to 13:21 [0:33]), and 10 km (28:35 [1:27] to 28:21 [1:21]). The average coefficient of variation did not change in the 1 mile (3.4% [1.8%] to 3.6% [1.6%]), 5 km (2.4% [0.9%] to 2.2% [0.8%]), or 10 km (1.4% [0.1%] to 1.5% [0.6%]) with improved WR. When velocity was normalized to the percentage mean velocity for each race, the pacing pattern was almost identical. Very similar patterns were observed in subelite runners in the 10 km. When time improved from 49:20 (5:30) to 45:56 (4:58), normalized velocity was similar, terminal RPE increased (8.4 [1.6] to 9.1 [0.8]), coefficient of variation was unchanged (4.4% [1.1%] to 4.8% [2.1%]), and VO2max increased (49.8 [7.4] to 55.3 [8.8] mL·min−1·kg−1). Conclusion: The results suggest that when runners break their own best performances, they employ the same pacing pattern, which is different from when WRs are improved in cross-sectional data.

Collaborative Study for the Determination of Nequinate in Feeds

1971 ◽  
Vol 54 (1) ◽  
pp. 69-71
Author(s):  
Phillip L Cox
Keyword(s):  
Formic Acid ◽  
Coefficient Of Variation ◽  
Collaborative Study ◽  
Methanesulfonic Acid ◽  
Average Coefficient

Abstract A collaborative study has been conducted on a previously reported method for the determination of nequinate in feeds. The drug is extracted from feed with 1% formic acid in chloroform and measured spectrofluorometrically after dilution with chloroform and the addition of methanesulfonic acid. Eight collaborators participated in the study, analyzing 7 different feeds. The average coefficient of variation for the study was 5.3%. The method is recommended for adoption as official first action.

Inter-Site Validation of a Single Breath Hold T2* MR Technique for Heart and Liver Iron Measurement.

Blood ◽  
2005 ◽  
Vol 106 (11) ◽  
pp. 3830-3830 ◽  
Author(s):  
Paul Kirk ◽  
Lisa J. Anderson ◽  
Mark A. Tanner ◽  
Renzo Galanello ◽  
Gildo Matta ◽  
...  
Keyword(s):  
Coefficient Of Variation ◽  
Breath Hold ◽  
Iron Loading ◽  
Myocardial Iron ◽  
Thalassaemia Major ◽  
Liver Iron ◽  
Single Breath ◽  
Single Breath Hold ◽  
Average Coefficient ◽  
Siemens Sonata

Abstract Background Approximately 60,000 people are born with thalassaemia major every year. The average life expectancy of thalassaemia major patients is 35 years due to iron overload Cardiomyopathy. The cardiomyopathy is reversible when treated early, but once heart failure is established it is often rapidly progressive, and unresponsive to treatment. The single breath hold (SBH) T2* technique has been validated as the most robust and reproducible non-invasive measurement of myocardial and iron load. Our aim in this study was to validate the transferability and reproducibility of this technique in different scanners worldwide. Methods We aim to compare the reproducibility in six different sites worldwide as part of an NIH funded grant (R01-DK66084-01). So far, two of these sites have been validated: Singapore (Siemens Sonata, 1.5T scanner) and Cagliari, Italy (GE Signa, 1.5 T scanner). At both validation sites, 10 patients were scanned for heart and liver T2*, and scans were repeated for interstudy reproducibility. All patients then flew to London to be rescanned on our reference Siemens Sonata scanner. Results Of the 20 patients scanned, 70% had myocardial iron loading (T2* <20ms) and in 10% the myocardial iron loading was severe. Liver iron loading was present in 65% of patients and in 30% this was severe. The coefficient of variation (COV) for the heart T2* measurements between the local sites and London was 5.9% and 4.9% yielding an average coefficient of variation across both sites of 5.4% (figure 1). The coefficient of variation (COV) for the liver T2* measurements between the local sites and London was 11.3% and 3.9% yielding an average coefficient of variation across both sites of 7.6% (figure 2). There was no significant correlation between liver and myocardial loading. Conclusion These are the first data demonstrating the transferability of the SBH T2* technique and the clinical validation from the 2 collaborating centers were excellent for both heart and liver measurements. Further MR sites confirmed for validation include Children’s Hospital of Philadelphia (USA); Ramathibodi Hospital, Bangkok (Thailand); and Chinese University Hong Kong. Figure 1 Figure 1. Figure 2 Figure 2.

scholarly journals Accuracy of Cycling Power Meters against a Mathematical Model of Treadmill Cycling

2017 ◽  
Vol 38 (06) ◽  
pp. 456-461 ◽  
Author(s):  
Thomas Maier ◽  
Lucas Schmid ◽  
Beat Müller ◽  
Thomas Steiner ◽  
Jon Wehrlin
Keyword(s):  
Mathematical Model ◽  
Coefficient Of Variation ◽  
Mean Deviation ◽  
First Principle ◽  
Power Meter ◽  
Coefficients Of Variation ◽  
The Mean

AbstractThe aim of this study was to compare the accuracy among a high number of current mobile cycling power meters used by elite and recreational cyclists against a first principle-based mathematical model of treadmill cycling. 54 power meters from 9 manufacturers used by 32 cyclists were calibrated. While the cyclist coasted downhill on a motorised treadmill, a back-pulling system was adjusted to counter the downhill force. The system was then loaded 3 times with 4 different masses while the cyclist pedalled to keep his position. The mean deviation (trueness) to the model and coefficient of variation (precision) were analysed. The mean deviations of the power meters were –0.9±3.2% (mean±SD) with 6 power meters deviating by more than±5%. The coefficients of variation of the power meters were 1.2±0.9% (mean±SD), with Stages varying more than SRM (p<0.001) and PowerTap (p<0.001). In conclusion, current power meters used by elite and recreational cyclists vary considerably in their trueness; precision is generally high but differs between manufacturers. Calibrating and adjusting the trueness of every power meter against a first principle-based reference is advised for accurate measurements.

scholarly journals Effect of Pressure on the Uniformity of Nozzles Transverse Distribution and Mathematical Model Development

2017 ◽  
Vol 65 (2) ◽  
pp. 563-568 ◽  
Author(s):  
Vladimir Višacki ◽  
Aleksandar Sedlar ◽  
Rajko Bugarin ◽  
Jan Turan ◽  
Patrik Burg
Keyword(s):  
Mathematical Model ◽  
Coefficient Of Variation ◽  
Model Development ◽  
Pressure Change ◽  
Operating Pressure ◽  
Pesticide Application ◽  
Working Pressure ◽  
Transverse Distribution ◽  
Working Liquid

Timely and high-quality application of pesticides contributes to environmental protection, economical production and production of healthy food. The efficacy of pesticide application depends not only on the quality of pesticides but also the quality of the application. One of the factor that most influences the quality of applications, from the standpoint of mechanization, are nozzles. They working liquid applied on the surface the plant resulting in the same volume of pesticide is applied to the entire surface of the plants. To achieve this goal, nozzles must be performed uniform application of working liquid per unit area, or tractor sprayer working width. The variable factor in the application of pesticides may be nozzle and operating pressure. With increasing working pressure obtained smaller droplets. The paper presents test of three different nozzles. Each nozzle is characterized by a flat jet with an angle of 110° and a flow rate of 1.6 l∙min−1 at a pressure of 3 bar. Differ from each other are by the way of disintegration of the jet. Exactly this characteristic causes that with pressure change coming to changes in the uniformity of nozzles transverse distribution. So the best distribution has nozzle with a flat jet. The coefficient of variation is between roughly from 4 to 6 % at the pressure application of 2 to 4 bar. Obtained mathematical model that describes changes in the coefficient of variation depending on pressure applications can be a good basis for easy harmonization parameters in the pesticide application.

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