... Most modern authors have focused on the existence, nonexistence and multiplicity of positive solutions. The case where Ω ⊆ R n , for n ≥ 2, has been studied by numerous authors: Concus and Finn [18, 19, 20, 21, 22, 23, 24]; Giusti [31, 32, 33, 34]; Gilbarg and Trudinger [30]; Ni and Serrin [48, 49, 50]; Finn [27, 28] (and the references therein); Peletier and Serrin [60]; Atkinson, Peletier and Serrin [3, 4]; Serrin [61]; Ishimura [37, 38]; Kusano and Swanson [40]; Nakao [47]; Noussair, Swanson and Jianfu [51]; Bidaut-Veron [9]; Clément, Manásevich and Mitidieri [16]; Coffman and Ziemer [17]; Conti and Gazzola [25]; Amster and Mariani [1]; Habets and Omari [35]; Le [42, 43]; Chang and Zhang [15]; del Pino and Guerra [26]; Moulton and Pelesko [45, 46]; Bereanu, Jebelean and Mawhin [7, 8]; Obersnel and Omari [53, 54]; Brubaker and Pelesko [13]; Brubaker and Lindsay [12]. Also, the case where n = 1 has been studied by numerous authors in a recent series of papers: Kusahara and Usami [39]; Benevieri, dò O and * Department of Mathematical Sciences, University of Delaware, Newark, DE 19716, USA (Email addresses: de Medeiros [5, 6]; Bonheure, Habets, Obersnel and Omari [10, 11]; Habets and Omari [36]; Obersnel [52]; Pan [56]; Li and Liu [44]; Burns and Grinfeld [14]; Pan and Xing [58, 57]. ...