Modeling of broiler chicken supply-chain economics depends on robust biological models of growth and yield of broiler chickens. In this paper, 8 dynamic nonlinear broiler carcass and carcass part yield models were evaluated statistically for their suitability for predicting weights of carcass parts. The analysis employed 4 sigmoidal (S) models (Gompertz, modified Gompertz, Richards, and Lopez) ...

The Gompertz function was formulated to represent an actuarial curve, yet it often fits growth of organisms, organs and tumors. Despite numerous attempts, no consensus has been forged about the biological foundation of the broad applicability of the model. Here we revisit the Gompertzian notion of the "power to grow" and equate it with growth fraction. Aside from conferring biological interpret...

This study provided the basic needs of parameters estimation for nonlinear growth model such as partial derivatives of each model, determination of initial values for each parameter and statistical tests of industrial usage. Twelve nonlinear growth models and its partial derivatives for oil palm yield growth are presented in this study. The parameters are estimated using the Marquardt iterative...

Experimental data of different animals (e.g. cocks, pigs, cats, dogs, cattles, etc.) from recent bibliography were selected to evaluate the capability of five classical sigmoidal equations (i.e. Bertalanffy, Weibull, logistic, Gompertz, and modified Hill) to model growth. These functions were used in different reparameterized forms in order to define all growth phases and to characterize signif...

In this paper, we consider a discrete Gompertz model with time delay. Firstly, the stability of the equilibrium of the system is investigated by analyzing the characteristic equation. By choosing the time delay as a bifurcation parameter, we prove that NeimarkSacker bifurcations occur when the delay passes a sequence of critical values. The direction and stability of the Neimark-Sacker are dete...

This study uses the modified Gompertz model and sparse data to analyze the growth rates of different types of computer and Internet-related crimes. The Gompertz model is an appropriate diffusion model because it is capable of modeling two opposite behaviors: (1) acts of attacks and imitation of attacks and (2) deterrence acts to prevent such attacks. In addition, this model can handle sparse da...

Software reliability models (SRMs) are very important for estimating and predicting software reliability in the testing/debugging phase. The contributions of this paper are as follows. First, a historical review of the Gompertz SRM is given. Based on several software failure data, the parameters of the Gompertz software reliability model are estimated using two estimation methods, the tradition...

Time course measurements of in vitro gas production of feedstuffs incubated with buffered ruminal fluid give information about the rate at which the feed is fermented. To compare gas production kinetics from different feeds, a mathematical model was needed to describe the data. We investigated several existing models (exponential, logistic, Gompertz, Richards, Schnute), fitting them to 50 gas p...

The tambaqui, Colossoma macropomum, is one of the most commercially valuable Amazonian fish species, and in the floodplains of the region, they are caught in both rivers and lakes. Most growth studies on this species to date have adjusted only one growth model, the von Bertalanffy, without considering its possible uncertainties. In this study, four different models (von Bertalanffy, Logistic, G...

The Gompertz model since 1825 has significantly contributed to interpretation of ageing in biological and social sciences. However, in modern research findings, it is clear that the Gompertz model is not successful to describe the whole demographic trajectories. In this letter, a new demographic model is introduced especially to describe human demographic trajectories, for example, for Sweden (...