Optimization of contrast sensitivity and specificity of post-beamforming Volterra filters for contrast-assisted nonlinear pulse-echo ultrasonic imaging.

摘要

My three-essay thesis centers on complex interorganizational adoption settings for information technologies (IT) that exhibit network externalities. I propose a new theoretical perspective---a rational expectations theory of technology adoption---that is intended to offer a better understanding of the issues around multi-partite technology adoption , involving multiple parties with shared expectations. The applied context of my research is the adoption of electronic bill presentment and payment (EBPP) technology.; The first essay looks into EBPP technology adoption from the welfare economics perspective and discusses the issues related to the formation of business value present in multi-party technology adoption settings. I use a simple two-period model in which there are two competing technologies and two potential adopting firms. The primary finding of this work is that although expectations about network externalities are essential in determining the timing of adoption, little emphasis has been placed on studying how potential IT adopters reach a level of expectations that triggers adoption.; The second essay extends the model by including a set of potential adopting firms---instead of just one---in the period when only one technology is available. I use the rational expectations hypothesis (REH) and adaptive learning theory to analyze an optimal control model to show why and how different firms that initially have heterogeneous expectations about the potential value of an IT are eventually able to arrive at contemporaneous decisions to adopt the same technology, creating the desired network externalities.; The third essay is an empirical piece that tests the rational expectations theory of technology by determining whether clustered adoption occurs in EBPP adoption. I develop several hypotheses based on the theory. Specifically, I test for the existence of clustered adoption and the role of interorganizational information sharing in shaping adoption expectations. My primary argument is that adoption should occur in a similar time frame when firms have been able to effectively share information about the future costs and benefits of the technology. My results show some evidence for the clustered adoption hypotheses.; My research demonstrates the importance of information sharing in shaping expectations for the effective adoption of IT in interorganizational settings.