Endogenous and exogenous constraints in the population changes of wild boar (sus scrofa Linnaeus, 1758)

The population dynamics of wild boar (Sus scrofa) was studied in a time series over 26 years using data from the Regional Hunting Reserve of Somiedo (northern Spain). This population is controlled by a complex negative feedback system that acts with one (main) and two (secondary) years of delay (lags). The primary feedback might be explained by intraspecific competition for food resulting from fluctuations in mast production (acorns and beech), and the secondary feedback might be explained by the influence of weather conditions or the delay of a cohort to reach reproductive status. We used a stochastic model that takes environmental variability into consideration when testing the demographical analysis that’s obtains simulations from real data

A STUDY ON DYNAMIC SYSTEMS RESPONSE OF THE PERFORMANCE CHARACTERISTICS OF SOME MAJOR BIOPHYSICAL SYSTEMS

Dynamic responses of biophysical systems - performance characteristic

Stability and Bifurcation Analysis of a Delayed Three Species Food Chain Model with Crowley-Martin Response Function

In this paper we have studied the dynamical behaviors of three species prey-predator system. The interaction between prey and middle-predator is Crowley-Martin type functional response. Positivity and boundedness of the system are discussed. Stability analysis of the equilibrium points is presented. Permanence and Hopf-bifurcation of the system are analyzed under some conditions. The effect of discrete time-delay is studied, where the delay may be regarded as the gestation period of the super-predator. The direction and the stability criteria of the bifurcating periodic solutions are determined with the help of the normal form theory and the center manifold theorem. Extensive numerical simulations are carried out to validate our analytical findings. Implications of our analytical and numerical findings are discussed critically

Hysterisis in Food Safety Investments

Concerns regarding the safety and integrity of the fresh produce supply chain are becoming all too common in the media. In 2006, an outbreak of E. coli O157:H7 from farms in Central California sickened almost two hundred people and lead to the deaths of three. Estimated costs to the industry ranged from $100 per month to$200 million until spinach sales returned to normal. By some accounts, the spinach industry has yet to recover and may not for years to come. The incident, however, has lead to a host of initiatives from industry officials, legislators and fresh produce retailers to ensure the safety of fresh produce. The necessary technology and best practices knowledge exists, yet some growers have not made the investment required to ensure that such outbreaks do not happen again in the future.Agribusiness, Agricultural and Food Policy, Farm Management, Food Consumption/Nutrition/Food Safety, Industrial Organization,