The People\u27s Voice: The Orator in American Society

In this flavorful and perceptive study of the American orator, Barnet Baskerville makes an inquiry into American attitudes toward orators and oratory and the reflection of these attitudes in speaking practices. He examines the role of the orator in society and the kinds or qualities of oratory that were dominant in each period of American history, and he looks into the nature and importance of oratory as perceived by audiences and by speakers themselves. By examining this “public image” of the orator, the author is able to tell us much about the people who drew that image. Barnet Baskerville is professor of speech communication at the University of Washington.https://uknowledge.uky.edu/upk_social_history/1002/thumbnail.jp

Groups and Niches in Food-Web Structure: Bayesian Methods and Consequences for Robustness.

Food webs, networks of feeding links, provide a valuable abstraction for studying the structure and dynamics of ecosystems. This dissertation examines the importance of groups and niches to food-web structure, develops methodology for identifying these patterns, links these patterns to ecological and evolutionary relationships among species, and finally explores how these patterns relate to network robustness. One pattern thought to be important for food-web structure is the presence of compartments, sub-networks of highly connected species. In one study, we explore the large-scale network architecture of a newly compiled plant-mammal food web from the Serengeti by developing a Bayesian method that identifies groups of species and patterns of linkages within and between groups. At the plant level, groups reflect habitat structure, an observation made possible by unusually high taxonomic resolution. Plant groups are coupled by groups of herbivores, which are in turn coupled by groups of carnivores, forming a pyramid structure that differs from the standard notion of compartmentalization. Food webs have also been observed to exhibit low dimensionality in feeding niche space: species can be ordered so that diets consist of largely contiguous intervals. In a second study, we extend the Serengeti analysis using a hybrid model that simultaneously infers groups alongside niche structure. We find that both elements are important: groups reflect the overall trophic architecture of the web, while niche space constrains the fine detail of feeding interactions. We identify statistical relationships between model parameters and evolutionary relationships, thus demonstrating a relationship between biological traits and network topology. Network structure determines, in part, how robust a food web is to extinctions. In a third study, we ask how different group structures vary in their robustness to bottom-up extinctions. We find that compartmentalization and interval niche structure reduce robustness. Notably, a coupled-pyramid structure like the one observed in the Serengeti is more robust than a compartmentalized structure, mirroring observations that spatial coupling can stabilize food webs. These results contrast with the prevailing wisdom that compartments are stabilizing, a difference that may result from opposing top-down and bottom-up effects.PHDEcology and Evolutionary Biology and Scientific ComputingUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/102289/1/ebaskerv_1.pd