Individuals take up preexisting roles and mainly reproduce structures they neither choose nor question.
According to this idea, ties do not reflect preexisting roles; instead, they allow actors to play certain functions - for instance, broker information.
Traditionally, research on social networks has assumed that network structure mirrors preexisting roles: being a professor at a university or a director in a company translates into having a set of similar ties with the other actors in the network (i.e. students and faculty, or other directors).
Health care and protection of coverage for people with preexisting conditions played a role, for example.
We discuss mechanisms of action, routes of delivery, and the role of preexisting immunity on antitumor efficacy.
Understanding the role of preexisting stress concentrations (such as notches, inclusions, and hard second phases) provides a bridge for understanding the fatigue damage evolution in a smooth specimen compared to that in a cracked specimen.
Studies have also not examined the moderating role of preexisting cardiovascular disease (CVD) or intensity of glucose control (9, 12).
Although these studies have reported an association of PM with survival, they have not evaluated the role of preexisting cardiac disease or whether risk changed with annual changes in exposure, nor have they treated pollution as a time-varying covariate.
Community-based family studies indicate that relatives of drug-dependent individuals have eight times the risk of developing drug abuse disorders themselves (3), but the role of preexisting vulnerability in addiction remains poorly understood.
Most importantly, the application of genome-wide technologies will tell us how significant has been the role of preexisting genetic variation versus de novo induced genetic variation by transposons and other mechanisms, such as RNAi or epigenetic modifications, in the phenotypic variation and speciation in groups of organisms that are suitable for these type of studies.
