Simplified estimation of forage degradability in the rumen assuming zero-order degradation kinetics

2008 ◽  
Vol 147 (3) ◽  
pp. 225-240 ◽  
Author(s):  
M. S. DHANOA ◽  
S. LÓPEZ ◽  
R. SANDERSON ◽  
J. FRANCE
Keyword(s):  
Reference Values ◽  
Incubation Time ◽  
Lag Time ◽  
Zero Order ◽  
Regression Equations ◽  
Order Model ◽  
First Order ◽  
Simplified Procedure ◽  
The Impact ◽  
Time Point

SUMMARYIn the present paper, a simplified procedure using few in situ data points is derived and then evaluated (using a large database) against reference values estimated with the standard nylon bag first-order kinetics model. The procedure proposed involved a two-stage mathematical process, with a statistical prediction of some degradation parameters (such as lag time) and then a kinetic model derived by assuming degradation follows zero-order kinetics to determine effective degradability in the rumen (E). In addition to the estimation of washout fraction and discrete lag, which is common to both procedures, the simplified procedure requires measurement of dry matter losses at one incubation time point only. Thus, interference of the animal rumen will be much reduced, which will lead to increased capacity for feed evaluation. Calibration of the zero-order model against the first-order model showed that suitable estimates of E can be obtained with disappearance at 24, 48 or 72 h as the single incubation end time point. The strength of the calibration is such that an end incubation time point as low as 24 h may be sufficient, which may reduce substantially the total incubation time required and thus the impact on the experimental animal. Relevant regression equations to predict reference values of parameters such as lag time or E are also developed and validated.

A preliminary study to predict net nitrogen mineralisation in a flooded rice soil using anaerobic incubation

1994 ◽  
Vol 34 (7) ◽  
pp. 995 ◽  
Author(s):  
JF Angus ◽  
M Ohnishi ◽  
T Horie ◽  
RL Williams
Keyword(s):  
N Uptake ◽  
Order Reaction ◽  
Zero Order ◽  
Organic N ◽  
N Mineralisation ◽  
Anaerobic Incubation ◽  
Flooded Soil ◽  
Order Model ◽  
First Order ◽  
Net Mineralisation

Complementary field and laboratory studies were conducted to determine whether laboratory measurements of net nitrogen (N) mineralisation under anaerobic conditions could be used to predict field rates in a flooded soil and N uptake by a rice crop. The laboratory experiment consisted of measurements of ammonium accumulation at 10, 20, 30, and 40�C for 7, 14, and 28 days of anaerobic incubation. There was no accumulation of ammonium at 10�C, but increasing ammonification rate at temperatures of 20�C was observed, except for a slower rate at 40�C after 14 days. Two models were tested on the data: a zero-order reaction in which rate of mineralisation was a linear function of temperature; a first-order reaction in which net N mineralisation rate was a proportion of a depleting pool of labile organic N. In the second model, the rate was also linearly related to temperature. Both models fitted the laboratory data well (R2 = 0.94 and 0.97, respectively), but the second model accounted better for mineralisation at 40�C for the 28-day incubation. These models were then run, using daily mean temperatures over a rice-growing season, to predict net mineralisation in the field. The predictions were compared with measured net N mineralisation in a flooded soil and N uptake by the crop measured throughout the season in the field from which the incubated soil was sampled. Net N mineralisation and crop uptake increased throughout the season, reaching maximum values of 115 and 111 kg N/ha at maturity. The zero-order and first-order models both predicted net N mineralisation accurately until the middle of the season, after which the zero-order model overestimated net N mineralisation but the first-order model predicted the reduction in the rate of net N mineralisation with reasonable accuracy. The close agreement between the laboratory incubations and field measurements of net mineralisation and crop N uptake suggest that incubation tests may provide useful information for including in a model to assist rice growers' decisions about N fertiliser.

scholarly journals Models based on variable fractional digestion rates to describe ruminal in situ digestion

1995 ◽  
Vol 73 (6) ◽  
pp. 793-807 ◽  
Author(s):  
Jaap Van Milgen ◽  
René Baumont
Keyword(s):  
Logistic Model ◽  
Lag Time ◽  
Order Model ◽  
Data Set ◽  
First Order ◽  
Scale Parameters ◽  
Fractional Rate ◽  
Independent Variable ◽  
Efficacy Function

Using a first-order model to describe ruminalin situdigestion implies that the rate of digestion is affected only by the quantity of potentially digestible substrate remaining. Other factors, like the microbial efficacy for digesting substrate, are assumed to be constant. However, microbes are not only the cause but also the result of digestion, being one of the digestion end-products. Two sigmoidal models (a logistic and a Gompertz-like model) were derived from a general digestion function in which the rate of digestion equals the product of the quantity of potentially digestible substrate remaining and a non-constant fractional rate of digestion (microbial efficacy function). The models were compared with a first-order model with a discrete lag time. The logistic model specifically accounted for the conversion of substrate mass to microbial mass, but did not describe microbial migration between the substrate and the ruminal fluid. In contrast, the Gompertz-like model assumed that the change in microbial efficacy was only time-dependent. There was little difference between models in estimates of scale parameters, but the asymptotic microbial efficacy was consistently higher for the logistic model than for the other models. Estimates of discrete lag time in the first-order model were biased towards obtaining values identical to the independent variable. Scale estimators appeared to be more robust than kinetic estimators. Lack-of-fit was present for most model-data set combinations. The similar patterns of residuals between models suggested that a four-parameter model may be insufficient to describe the data. It was concluded that if a four-parameter model is to be used, the model with a discrete lag time would be the least biologically appropriate.

Variation in Standard Dutch vowels: The impact of formant measurement methods on identifying the speaker's regional origin

2014 ◽  
Vol 26 (2) ◽  
pp. 247-272 ◽  
Author(s):  
Sander Van der Harst ◽  
Hans Van de Velde ◽  
Roeland Van Hout
Keyword(s):  
Polynomial Regression ◽  
Multiple Time ◽  
Regression Equations ◽  
Regional Patterns ◽  
Time Points ◽  
Regression Approach ◽  
Vowel Formants ◽  
Monosyllabic Words ◽  
The Impact ◽  
Time Point

AbstractIt is common practice in sociophonetics to measure vowel formants at one (monophthongs) or two (diphthongs) time points. This paper compares this traditional target approach with two dynamic approaches for investigating regional patterns of variation: the multiple time point approach, which measures formants at successive time points, and the regression approach, which estimates formant dynamics over time by fitting polynomial regression equations to formant contours. The speech material consisted of monosyllabic words containing all full vowels of Dutch, except for /y/. These words were read out by 160 speakers of Standard Dutch, who were distributed over four regions in the Netherlands and four regions in Flanders, Belgium. The results show that dynamic approaches outperform the target approach in uncovering regional vowel differences, which suggests that sociophonetic vowel studies that apply the target approach run the risk of overlooking important sociolinguistic patterns.

scholarly journals Development and characterization of miconazole nitrate transfersomal gel

2020 ◽  
Vol 1 (4) ◽  
pp. 109-116
Author(s):  
Shaik Sajid Ali ◽  
Madhu Gudipati ◽  
Ramarao Nadendla
Keyword(s):  
Fungal Infections ◽  
In Vitro Release ◽  
Zero Order ◽  
Skin Permeability ◽  
Order Model ◽  
Lipid Film ◽  
First Order ◽  
Miconazole Nitrate ◽  
Vitro Release

Miconazole nitrate (MIC) is an antifungal drug used for the treatment of superficial fungal infections. However, it has low skin permeability. Hence, the basic idea behind the development of such a system, transfersomes is to maintain a sustain release of drug from the dosage form and for target delivery. Miconazole nitrate was formulated as transfersomes, half-life can be increased and the desired effect can be obtained. MIC transfersomes were prepared using a thin lipid film hydration technique. The prepared transfersomes were evaluated with respect to entrapment efficiency (EE%), particle size, and quantity of in vitro drug released to obtain an optimized formulation. The optimized formulation of MIC transfersomes was incorporated into a Carbapol 934 gel base which was for drug content, pH, spreadability, viscosity, in vitro permeation, and in vitro activity. The prepared MIC transfersomes had a high EE% ranging from 65.45% to 80.11%, with small particle sizes ranging from 368 nm to 931 nm. The in vitro release study suggested that there was an inverse relationship between EE% and in vitro release. In 24 hrs the drug release was observed ranging from 79.08% to 88.72%. The kinetic analysis of all release profiles was found to follow Higuchi’s diffusion model. All independent variables had a significant effect on the dependent variables (p-values < 0.05). Therefore, Miconazole nitrate in the form of transfersomes has the ability to penetrate the skin, overcoming the stratum corneum barrier. When the data subjected to zero order and first order kinetics model, a linear relationship was observed with high R2 values for zero order model as compared to first order model and suggested that the formulations followed zero order sustained release.

A first-order model of thermal lensing of laser propagation in the eye and implications for laser safety

2005 ◽  
Author(s):  
Robert J. Thomas ◽  
Rebecca L. Vincelette ◽  
Gavin D. Buffington ◽  
Amber D. Strunk ◽  
Michael A. Edwards ◽  
...  
Keyword(s):  
Thermal Lensing ◽  
Order Model ◽  
Laser Safety ◽  
First Order ◽  
Laser Propagation

The impact of participant pathways on the effectiveness of a community-based physical activity intervention grounded in motivational interviewing

2020 ◽  
Author(s):  
Matthew Wade ◽  
Nicola Brown ◽  
James Steele ◽  
Steven Mann ◽  
Bernadette Dancy ◽  
...  
Keyword(s):  
Physical Activity ◽  
Primary Care ◽  
Motivational Interviewing ◽  
Social Action ◽  
Multilevel Models ◽  
Physical Activity Intervention ◽  
Mental Wellbeing ◽  
Community Based ◽  
The Impact ◽  
Time Point

Background: Brief advice is recommended to increase physical activity (PA) within primary care. This study assessed change in PA levels and mental wellbeing after a motivational interviewing (MI) community-based PA intervention and the impact of signposting [SP] and Social Action [SA] (i.e. weekly group support) pathways. Methods: Participants (n=2084) took part in a community-based, primary care PA programme using MI techniques. Self-reported PA and mental wellbeing data were collected at baseline (following an initial 30-minute MI appointment), 12-weeks, six-months, and 12-months. Participants were assigned based upon the surgery they attended to the SP or SA pathway. Multilevel models were used to derive point estimates and 95%CIs for outcomes at each time point and change scores. Results: Participants increased PA and mental wellbeing at each follow-up time point through both participant pathways and with little difference between pathways. Retention was similar between pathways at 12-weeks, but the SP pathway retained more participants at six-months and 12-months. Conclusions: Both pathways produced similar improvements in PA and mental wellbeing, suggesting the effectiveness of MI based PA interventions. However, due to lower resources required yet similar effects, SP pathways are recommended over SA to support PA in primary care settings.

THE MODEL FOR MANAGING INVESTMENTS IN THE MOSCOW ENVIRONMENT BASED ON A POWER REGRESSION EQUATION

2020 ◽  
Vol 2 (7) ◽  
pp. 91-99
Author(s):  
E. V. KOSTYRIN ◽  
◽  
M. S. SINODSKAYA ◽  
Keyword(s):  
Solid Waste ◽  
Influencing Factors ◽  
Pair Correlation ◽  
Approximation Error ◽  
Regression Equation ◽  
Regression Equations ◽  
The Impact ◽  
The Relationship ◽  
Average Approximation ◽  
Average Approximation Error

The article analyzes the impact of certain factors on the volume of investments in the environment. Regression equations describing the relationship between the volume of investment in the environment and each of the influencing factors are constructed, the coefficients of the Pearson pair correlation between the dependent variable and the influencing factors, as well as pairwise between the influencing factors, are calculated. The average approximation error for each regression equation is determined. A correlation matrix is constructed and a conclusion is made. The developed econometric model is implemented in the program of separate collection of municipal solid waste (MSW) in Moscow. The efficiency of the model of investment management in the environment is evaluated on the example of the growth of planned investments in the activities of companies specializing in the export and processing of solid waste.

Kinetics of catalytic reduction of nitrogen oxide by carbon monoxide on CuO/Al2O3 catalyst

1983 ◽  
Vol 48 (11) ◽  
pp. 3202-3208 ◽  
Author(s):  
Zdeněk Musil ◽  
Vladimír Pour
Keyword(s):  
Carbon Monoxide ◽  
Nitrogen Oxide ◽  
Rate Equation ◽  
Catalytic Reduction ◽  
Zero Order ◽  
Spectroscopic Measurements ◽  
First Order ◽  
Ir Spectroscopic ◽  
Kinetics Of ◽  
Al2o3 Catalyst

The kinetics of the reduction of nitrogen oxide by carbon monoxide on CuO/Al2O3 catalyst (8.36 mass % CuO) were determined at temperatures between 413 and 473 K. The reaction was found to be first order in NO and zero order in CO. The observed kinetics are consistent with a rate equation derived from a mechanism proposed on the basis of IR spectroscopic measurements.

Studies on Related ms Magnitude Rate Models in Triangular Wave Unloading Section of Calcium Medium-Fine Sandstone

2010 ◽  
Vol 152-153 ◽  
pp. 164-170
Author(s):  
Jie Liu ◽  
Jian Lin Li ◽  
Ying Xia Li ◽  
Shan Shan Yang ◽  
Ji Fang Zhou ◽  
...  
Keyword(s):  
Mechanical Response ◽  
Strain Curve ◽  
Experimental System ◽  
Constant Term ◽  
Lag Time ◽  
Vertical Force ◽  
Time Segment ◽  
Triangular Wave ◽  
Apparent Modulus ◽  
The Impact

Specific to the improvement in the present research of mechanical response under cyclic loading, this paper, taking the calcareous middle- coarse sandstone as the research subject and the RMT-150C experimental system in which data is recoded by ms magnitude as the platform, develops several related models concerning the unloading rate of triangle waves. The unloading process is divided into lag time segment and non-lag time segment, with criterions and related parameters provided as well. The term apparent elastic modulus is defined. The test data analysis shows that there exist a linear relationship between the apparent modulus and instant vertical force before load damage in non-lag time segment. On the preceding basis, a rate-dependent model of triangular wave un-installation section in non-lag time segment is established. Due to the inability of the loading equipment to accurately input the triangle wave, the average loading rate is amended and a constant term is added into it. The model is proved to be reliable, as the predicted value of the deformation rate and the stress strain curve coincides with measured value. At the same time, the impact of the lag time is pointed out quantitatively and a predication model of lag time segment is set up.

Sign in / Sign up

Export Citation Format

Share Document