Characterizing Activity-Dependent Processes with a Piecewise Exponential Model

Biometrics ◽  
1988 ◽  
Vol 44 (2) ◽  
pp. 549 ◽  
Author(s):  
C. F. Starmer
Keyword(s):  
Exponential Model ◽  
Piecewise Exponential Model ◽  
Piecewise Exponential ◽  
Activity Dependent ◽  
Dependent Processes

scholarly journals Morbidity and Mortality Rates of Boer and Central Highland Goats at Ataye Crossbreeding Program Research Site: Non-parametric Survival Analysis and Piecewise Exponential Model

2021 ◽  
Author(s):  
Erdachew Yitagesu Tesema ◽  
Enyiew Alemnew
Keyword(s):  
Post Partum ◽  
Evaluation Research ◽  
Exponential Model ◽  
Morbidity And Mortality ◽  
P Value ◽  
Boer Goat ◽  
Piecewise Exponential Model ◽  
Piecewise Exponential ◽  
Parametric Survival ◽  
Non Parametric

Abstract Non-parametric survival analysis and piecewise exponential model (PEM) was used to estimate prevalence and incidence of goat mortality, to identify major clinical causes of morbidity and mortality related disease, and to investigate animal and environmental related risk factors affecting goat mortality at Ataye boer goat breeding and evaluation research site. A total of 671 kids and 347 adult (yearling) age goats were used for the analysis of non-parametric survival and piecewise exponential model for survival, mortality incidence rate and causes of morbidity and mortality analysis. The mortality incidence rate of kids and adult goats were 0.638 and 0.302 per animal year respectively. The 25th, 50th and 75th percentile of survival time of kids were 5, 157 and 1,274 days respectively and of adult goats were 280, 828 and 1,557 days respectively. The present mortality rate is relatively larger than reports of boer cross breeding and evaluation research sites in Ethiopia as well as goat mortality prevalence abroad. Gastro-intestinal related diseases, pneumonia, weak kid, agalactia, mismothering and hear water (cowdriosis) were most important causes of mortality. Constant piecewise exponential regression analysis of risk factors indicates that breed, kid birth weight (BWT), doe post-partum weight (PPWT), birth type, birth year and precipitation variables were associated with (p-value < 0.05) kid mortality rate. Pure boer kids compared with CHG cross boer goat, are 2.505 times at higher probability of mortality (p ≤ 0.001). A 1 kilo gram increase of kid birth weight and dam PPWT reduces mortality probability by 32.5% (p-value ≤ 0.001) and 6.4% (p-value ≤ 0.001) respectively. Twin birth kids are1.512 times higher rate of mortality (p-value = 0.001) compared with single born kids. A one-millilitre increment of 15 days average precipitation significantly reduces kid mortality by 7.8% (p-value ≤ 0.001). Fleshing of does during early meeting to improve the post-partum weight of does and kids is also important to reduce both kid and doe mortality at and after kidding. Immunization of new introduced and kids to common endemic diseases in the area, extensive control of ticks to breakdown heart water transmission and use of proper comfortable housing to reduce stress of goats is recommended. Improving nutrition particularly during scarce grazing and browsing feed availability is important to improving the health and reducing mortality of goats in intensively managed goat farms.

MATHEMATICAL MODELS OF DUAL TRANSMISSIVITY AND EXAMPLES OF THEIR APPLICATION IN INTERPRETING PIEZOMETRIC TESTS CONDUCTED IN THE BEŁCHATÓW LIGNITE MINE

2018 ◽  
Vol 471 ◽  
pp. 193-200
Author(s):  
Filip WOLNY ◽  
Mariusz JAMRÓZ ◽  
Jerzy GASIŃSKI ◽  
Marek Marciniak ◽  
Mariusz KACZMAREK
Keyword(s):  
Mathematical Models ◽  
Exponential Model ◽  
Theoretical Background ◽  
Slug Test ◽  
Damped Oscillations ◽  
Piecewise Exponential Model ◽  
Lignite Mine ◽  
Piecewise Exponential ◽  
Heterogeneous Sediments ◽  
Exponential Response

Piezometric tests such as the slug test or PARAMEX test usually result in observing damped oscillations or exponential movement of the water level. However, during some tests, a bi-exponential response of the water table has been recorded. Bi-exponential movement may indicate the presence of a dual-permeability medium around the piezometer screen. Such medium is composed of two subdomains, each characterized by different hydraulic properties (including transmissivity, T). The paper aims to present two mathematical models – the piecewise exponential model and the bi-exponential model – which were applied in order to interpret the results of slug test conducted in heterogeneous sediments of the Bełchatów Lignite Mine. Theoretical background, interpretation algorithms and examples of dual transmissivity estimation for several chosen piezometers are presented. All necessary calculations were performed using Paramex 4 and MATLAB software. Furthermore, the limitations of the interpretation algorithms are discussed.

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