The Marx model for the profit rate r depending on the exploitation rate e and on the organic composition of the capital k is studied using a dynamical approach. Supposing both e(t) and k(t) are continuous functions of time we derive a law for r(t) in the long term. Depending upon the hypothesis set on the growth of k(t) and e(t) in the long term, r(t) can fall to zero or remain constant. This l...

This article discusses t,he selection of the domain for a knowledge-based expert system for a corporate application The selection of the domain is a critical task in an expert system development At the st,art of a project looking into the development of an expert, syst,em, the knowledge engineering project team must investigate one or several possible expert system domains They must decide whet...

Auto regressive integrated moving average (ARIMA) models have been widely used to calculate monthly time series data formed by interannual variations of monthly data or inter-monthly variation. However, the influence brought about by inter-monthly variations within each year is often ignored. An improved ARIMA model is developed in this study accounting for both the interannual and inter-monthl...

Question: Are there general life-history rules for exploitation-caused extinction of mammal populations? Mathematical methods: A population of size N faced with the added mortality of human exploitation will deterministically go extinct if its per-capita birth rate can no longer match its per-capita mortality rate as N approaches zero. We develop exploitation-extinction theory for a mammal life...

The growth and mortality coefficient of Rutilus frisii kutum, were estimated using length frequency data collected in southern waters of the Caspian Sea during October 2008 to April 2009. The following population parameters were evaluated: length-weight relationship, W = 0.004L 3.258, (r= 0.976) Von Bertalanffy growth constants, W∞ (g) = 4192.3, L∞ (cm) = 70.45, K = 0.2, per year t0 = −0.75 tot...