00961nas a2200133   4500008004100000245014200041210006900183260003100252520042800283100002300711700002300734700001900757856005100776       2016                        en  d00aPairs of positive periodic solutions of nonlinear ODEs with indefinite weight: a topological degree approach for the super-sublinear case0 aPairs of positive periodic solutions of nonlinear ODEs with inde  bCambridge University Press3 a<p>We study the periodic and Neumann boundary value problems associated with the second order nonlinear differential equation u''+cu'+λa(t)g(u)=0, where g:[0,+∞[→[0,+∞[ is a sublinear function at infinity having superlinear growth at zero. We prove the existence of two positive solutions when ∫a(t)dt 0 is sufficiently large. Our approach is based on Mawhin's coincidence degree theory and index computations.</p>1 aBoscaggin, Alberto1 aFeltrin, Guglielmo1 aZanolin, Fabio  uhttp://urania.sissa.it/xmlui/handle/1963/35262