The purposeof this studywas to Analyzing factors that effecting on rangeland degradation. Statistical population of this research consisted of whole farmer in Pirtaj district (N= 1600); from that 120 farmer were selected as sample using cluster sampling. The main tool to collect data was a researcher made questionnaire that Content validity of the questionnaire was approved, by a panel of exper...

OBJECTIVE To show the complications that increase the permanence at intensive care unit (ICU) of the patients submitted to cardiac surgery. METHODS Eighty-five handbooks of patients submitted to cardiac surgery had been analyzed, retrospectively, from March to May 2009 at Santa Casa de Misericórdia de Juiz de Fora (MG)--Brazil--and 14 (16.47%) patients had been studied. They remained more tha...

The permanence of a single-species population discrete model with feedback control is considered. We found that if we use the method of comparison theorem, then the additional condition, to some extent, is necessary. But for the system itself, this condition may not be necessary. Here, we use new methods instead of the comparison theorem to get the permanence of the system in consideration; the...

here, a predator-prey model with hassell-varley type functional responses is studied. some sufficient conditions are obtained for the permanence and global asymptotic stability of the system by using comparison theorem and constructing a suitable lyapunov functional. moreover, an example is illustrated to verify the results by simulation.

Human social life is structured by social norms creating both obligations and entitlements. Recent research has found that young children enforce simple obligations against norm violators by protesting. It is not known, however, whether they understand entitlements in the sense that they will actively object to a second party attempting to interfere in something that a third party is entitled t...

An age-structured prey-predator model with delays is proposed and analyzed. Mathematical analyses of the model equations with regard to boundedness of solutions, permanence, and stability are analyzed. By using the persistence theory for infinite-dimensional systems, the sufficient conditions for the permanence of the system are obtained. By constructing suitable Lyapunov functions and using an...

As inkjet printers move into mainstream photography markets, consumers and professionals alike are asking many questions about how the permanence of inkjet prints compares with that of traditional silver halide based, chromogenic color prints. The various factors affecting color print permanence are described. The similarities and differences between inkjet prints and traditional color prints i...

The question of the long term survival of species in models governed by Lotka-Volterra difference equations is considered. The criterion used is the biologically realistic one of permanence, that is populations with all initial values positive must eventually all become greater than some fixed positive number. We show that in spite of the complex dynamics associated even with the simplest of su...

A periodic delay single-species difference system with feedback control is established. With the help of analysis method and Lyapunov function, a good understanding of the permanence and global attractivity of the system is gained. Numerical simulations are presented to verify the validity of the proposed criteria. Our results show that feedback control has no influence on the permanence while ...