Non Linear Control System Based Modeling of Cardiac Muscle using Describing Function and Lyapnuov Stability.

Main focus of this research work is aims towards the nonlinear analysis of human cardiac muscle by describing function technique and finding stability using lyapnuov stability theory. The nature of cardiac muscle can be modeled by mass, spring with a damper where for simplicity spring and damper are considered a linear element. In reality, it has been observed that, the characteristics of spring and damper are not linear rather nonlinear. Not only that, transportation delay (non-zero reaction time) or lag phase of cardiac muscle plays an important role to make the overall model nonlinear. The range of transportation delay for which the system is stable has been calculated here to ensure the presence of dead zone type nonlinearity in cardiac muscle. In this paper a nonlinear characteristics of the model has been analyzed considering dead zone combined with saturation. The describing function technique is used here to represent the nonlinearity. A converging stable limit cycle has been found after the analysis. Finally, lyapnuov stability theorem is applied on our proposed model and it has been that the system is asymptotically stable in the sense of lyapnuov

Spontaneous intake and long-term effects of essential oils after a negative postnatal experience in chicks

The postnatal period is critical for broiler chicks as they are exposed to, possibly stressful, environmental changes in the hatchery and during transportation to the rearing houses. The ability of broiler chicks to spontaneously drink essential oils (EO) to mitigate the effects of a negative postnatal experience was tested. Chicks were either immediately placed in the rearing facility (C group), or subjected to a 24h-delay period before their placement (D group), mimicking the possible transportation delay in commercial conditions.In experiment 1, each group had access to either water only or to water and one EO (cardamom, marjoram or verbena) from D1 to D13. The verbena EO intake was higher in the D group than in the C group from D1 to D6 and the cardamom EO intake was lower in the D group than in the C group from D6 to D13.In experiment 2, half of the groups had access to water only and the other half was offered water and the 3 EO simultaneously. The EO were not differently chosen by chicks between D and C groups except a lower cardamom EO intake was observed in the D group than in the C group from D6 to D12. The delayed placement of the D group reduced chicken growth until 34 days of age and temporarily increased the feed conversion ratio, but did not affect their welfare or the prevalence of health disorders. The EO intake did not allow the chicks in the D group to overcome the growth reduction, but did overcome the reduction in Pectoralis major muscle yield. In conclusion, chicks are able to make spontaneous choices regarding EO intake according to their postnatal experience when EO are presented individually, but in our experimental design, they were not when EO were simultaneously presented. The EO intake only partially mitigated the decrease in chicken performance after the negative postnatal experience.