The present invention provides a field weldable connection. A strain inducing layer is formed over the transistor to apply a strain thereto to alter transistor operating characteristics, and more particularly to enhance the mobility of carriers within the transistor. Furthermore the invention relates to a corresponding power converter for connecting to a grid, preferably it relates to a solar power converter. A relational database query may be generated that includes a predicate for at least one member from at least one level above the identified level in the hierarchy, instead of a plurality of predicates for members from the identified level.