This study aimed to investigate and compare nonlinear growth models (NLMs) with the predicted performance of broilers using an artificial neural network (ANN). Six hundred forty broiler chicks were sexed and randomly reared in 32 separate pens as a factorial experiment with 4 treatments and 4 replicates including 20 birds per pen in a 42-day period. Treatments consisted of 2 metabolic energy le...

the application time of weed control methods due to population dynamics of this species is one of the most important aspects of weed management. in this study tried to use four sigmoidal functions (logistic, gompertz, richards and weibull) and to select the best fit by using r2adj , rmse and aicc. our results showed that the seedling models of every weed are different from one another and the m...

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 (...

A macroscopic model of the tumor Gompertzian growth is proposed. This approach is based on the energetic balance among the different cell activities, described by methods of statistical mechanics and related to the growth inhibitor factors. The model is successfully applied to the multicellular tumor spheroid data.

This article addresses the design of therapeutic procedures for cancer using a control based on the Gompertz model, that describes the nonlinear dynamics of tumor growth. The aim is to reduce the tumor size according to a decreasing target reference. The approach presented on this work uses a control Lyapunov function and yields an adaptive PI strategy that results from the exact linearization....

Senescence (ageing) and apoptosis (programmed cell death) are phenomena that have troubled theoreticians and experimentalists. Previous research showed that the mortality curve of the yeast population followed the Gompertz-Makeham equation. We develop a generalised theoretical model which shows that the mortality of the organism can be expressed as a function of Ageing Factors such as ERCs. We ...

In this communication, based upon the deterministic Gompertz growth law, a stochastic nonlinear model of tumour growth is proposed to model the conventional size-dependent therapy strategy of tumours. The probability density function of the size of the tumour obeys a nonlinear Fokker-Planck equation which can be solved analytically. It is found that during the cancer treatments the dose intensi...

In this work a new probabilistic and dynamical approach to an extension of the Gompertz law is proposed. A generalized family of probability density functions, designated by Beta • (p,q), which is proportional to the right hand side of the Tsoularis-Wallace model, is studied. In particular, for p=2, the investigation is extended to the extreme value models of Weibull and Frechet type. These mod...

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...

It is often necessary in applied statistical research to perform direct numerical optimization because the problem can not be transformed to be solved by standard procedures implemented in the statistical packages. One example of such a problem comes from the field of growth modeling: The Polynomial Gompertz model is known to provide a good fit to individual growth curves and growth percentiles...