Search

Abstract: Mental illness grow to become one of the most significant issues in the global medical burden. Ultrasound therapy has shown excellent performance in many clinical applications. Some encouraging evidence has shown that transcranial ultrasound stimulation (TUS) has a beneficial effect on relieving symptoms of mental illness (neuropsychiatric disorders). However, the commercially available low-intensity pulsed ultrasound (LIPUS) devices are usually bulky, power-consuming, and not designed explicitly for transcranial stimulation. There is a need for the implementation of a portable LIPUS device suitable for area-constrained embedded applications designed particularly for applying ultrasound stimulation to the brain. To address this need, this study designs and implements an internet of things (IoT) portable LIPUS generation system for TUS application. The LIPUS generating system is composed of head-mounted transmission equipment, a LIPUS signal driving device, and a mobile application. In the head-mounted transmission equipment, in addition to the necessary accessories and appearance parts, the main components include an ultrasonic transducer, a rubber cap, the ultrasound agents, and an impedance matching circuit board. Studies are carried out to investigate the applicable ultrasound generation characteristic. The driving circuit module, the Bluetooth module, the power module, and the appearance accessories form a LIPUS signal driving module. The ultimate goal of this work is to design a prototype LIPUS generation system that is implemented using discrete components. After verification, the LIPUS generator can work appropriately after manufacture, and can generate LIPUS power from 30 mW to 590 mW (LIPUS intensity from 6.1 mW/cm^2 to 120 mW/cm^2) at the resonant frequency of 1.5 MHz of the transducer. In addition, there have been a few studies that have estimated the risk of using therapeutic ultrasound. After developing a head-mounted LIPUS device, verification is performed to evaluate possible tissue damage when different intensity levels of LIPUS stimulation are applied through the temple to the brain. Our computer simulations and in vitro experiments show that our customized LIPUS devices can safely deliver small doses of low-intensity pulsed ultrasound to the brain through the skull without damage to the contacted skin and inner tissue. When a higher dose of LIPUS is applied to the temple, the skin in contact with the transducer may produce temporarily reversible injury. These results show that this approach has the potential to be used in the treatment of many neurological diseases as a TUS method in the future.

This dissertation is a collection of three essays that deal with a number of different topics in Industrial Organization. Mainly, they are concerned with market dynamics, regulation policies and advertising. Chapter 1 develops and estimates a dynamic oligopoly model of advertising in the cigarette industry. With this estimated model, I evaluate the impact of the 1971 TV/Radio advertising ban on the cigarette industry. A puzzling fact about this ban is that, while industry advertising spending decreased sharply immediately following its passage, spending then recovered and actually exceeded its pre-ban level within five years. While simple static models cannot account for such a turn of events, the rich dynamic model developed in this paper can. This chapter exploits new previously confidential micro data, now made public through tobacco litigation. In addition, the chapter uses a new concept of Oblivious Equilibrium to handle intractable state space and accelerate equilibrium computation. Chapter 2 studies how advertising influences firms' incentives to invest in R&D. The link between advertising and industry innovation is important, not only because advertising can spur R&D by spreading product knowledge, but also because advertising can discourage new innovative firms from entering the industry. This chapter finds that a worse advertising technology can result in local improvements in industry innovation rates. Globally, however, a complete ban on advertising always reduces industry growth. This result is significant because industry advertising spending is quantitatively significant and there are potential connections between public policy towards advertising and R&D. In chapter 3, we study the performance of the New-Deal sugar manufacturing cartel that existed from 1934 to 1974. We show that the cartel led to major distortions in both how sugar produced at a given factory, and in where the industry was located. The setup of this legal cartel involved four important provisions: sale quotas, land restriction, side payments, and government negotiated factory-farm contracts. We argue that all four provisions distorted how sugar was produced and led to significant loss in productivity measured by sugar recovery rate. Furthermore, we present extensive evidence from industry, company and factory records to support these conclusions.