The purpose of this work was to study the effect of initial pH and yeast Saccharomyces Cerevisiae on biogas production from tofu wastewater (TW). The initial pH was varied in ranging of 5 – 9 in substrate without yeast (T5-T9) and with yeast (TY5-TY9). The results showed that optimum initial pH was 8. The maximum biogas was resulted in T8 (275 mL) and TY8 (421 mL). Yeast addition increased tota...

We defend the hypothesis that life-spanning population survivorship curves, as described by Gompertz' law and composed from cross-sectional data (here mortality), reflect an intrinsic aging principle active in each subject of that population. In other words Gompertz' law reflects aging of a prototypical subject, provided minimal (or no) external causes of death (i.e. fatal infections, starvatio...

In this paper, we introduce a new four-parameter generalized version of the Gompertz model which is called Beta-Gompertz (BG) distribution. It includes some well-known lifetime distributions such as beta-exponential and generalized Gompertz distributions as special sub-models. This new distribution is quite flexible and can be used effectively in modeling survival data and reliability problems....

The Gompertz model is well known and widely used in many aspects of biology. It has been frequently used to describe the growth of animals and plants, as well as the number or volume of bacteria and cancer cells. Numerous parametrisations and re-parametrisations of varying usefulness are found in the literature, whereof the Gompertz-Laird is one of the more commonly used. Here, we review, prese...

This study was undertaken to describe the growth pattern of the pearl gray Guinea fowl. Using BW data from hatch to 22 wk, 3 nonlinear mathematical functions (Richards, Gompertz, and logistic) were used to estimate growth patterns of the pearl gray guinea fowl. The logistic and Gompertz models are a special case of the Richards model, which has a variable point of inflection defined by the shap...

Maximum lifespan has been one of the most common aging measures in comparative studies, while the Gompertz model has recently attracted both proponents and critics of its capacity to adequately describe the acceleration of mortality in the oldest age classes. The Gompertz demographic model describes age-dependent mortality rate acceleration and age-independent mortality using the parameters alp...

We develop a new generalized family of the Gompertz-G distribution, namely, Marshall-Olkin-Gompertz-G distribution. Statistical properties proposed model are presented. Some special cases distributions Maximum likelihood estimates parameters also determined. A simulation study was conducted to assess performance maximum estimates. Applications demonstrate usefulness Marshall-Olkin-Gompertz-Weib...

In this paper we provide an interval of existence of critical mortality rate parameters A and α and its asymptotic expressions in Gompertz survival model, in the absence of age specific mortality data. c © 2007 Elsevier Ltd. All rights reserved.

Factors determining the diffusion of digital mobile telephony across 200 developed and developing countries in the 1990s are studied with the aid of a Gompertz model. The market size and network effects are found to play more important roles in the developing countries; there is also more need for complementing innovations in, for example, financial and payment systems. Even though the developi...