The paper proposes a general framework allowing the analysis of wetting problems in thesituation when interfacial tensions depend on external fields. An equation predictingapparent contact angles of sessile droplets deposited on rough surfaces in the presence ofexternal fields is derived. The problem of wetting is discussed in the framework of thevariational approach. Derivation of a general equation generalizing the Cassie and Wenzelapproaches is presented. The effects related to the line tension which are important fornano-structured surfaces are considered.

In an attempt to clean up an unruly literature, we specify the necessary and sufficient conditions for household optimality in a model where money is the only financial asset and provide the relevant proofs. We use our results to analyze when deflationary bubbles can and cannot exist. Our findings are in contrast to the results in several prominent contributions to the literature. We argue for particular specifications of the no-Ponzi-game restrictions on the representative household's and the government's intertemporal budget constraints in a model with money and bonds. Using the restriction on the household we derive the necessary and sufficient conditions for household optimality. The resulting equilibrium terminal conditions are then used to demonstrate that the existence of bonds does not affect when deflationary bubbles can and cannot occur. This result differs from that in other recent works.