RESUMO
The aim of this paper is to prove the uniqueness of isolated periodic solutions (i.e. limit cycles) in two simple models for microparasitic and macroparasitic diseases. Both models are described by systems of planar autonomous ordinary differential equations. After transformation of these systems to generalized Liénard systems, we will apply a modified theorem of Zhang and Dulac's criterion to prove the uniqueness of limit cycles.
Assuntos
Métodos Epidemiológicos , Modelos Estatísticos , Doenças Parasitárias/epidemiologia , Animais , Interações Hospedeiro-Parasita , Humanos , Doenças Parasitárias/parasitologia , Densidade Demográfica , Estados UnidosRESUMO
Slow arm movements were made over a smooth horizontal table at shoulder height. With visual cues excluded, target position was indicated by the index finger of the nonmoving arm touching the underside of the table. 11 students (mean age 21.9 yr.) and 24 children (mean age 10.3 yr.) were compared. Both groups showed an 'overlap effect': movements with the right hand went too far to the left, while movements with the left hand went too far to the right. The children as a group were significantly less accurate than the students and showed a significant asymmetry in that movements with the dominant hand were more accurate than those with the nondominant hand.
