How can a building and the landscape be integrated in such a way that the interior and exterior begin to infiltrate each other, blurring and in some cases breaking the threshold between them? A threshold is a place, time, or event that indicates the passage from one state to another. Instead of a simple dividing line, thresholds should be understood as a choreographed sequence of spaces, both inside and outside the building envelope. This project will explore the means to strategically break thresholds between different conditions to create a building intimately bound to the physical, social, and mental landscape it inhabits. / Master of Architecture

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Thesis (Ph.D.)--Boston University / PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / Normal hearing is typically defined by threshold audibility, or the loudness of sounds that an individual is able to hear. This convention exists despite the fact that everyday communication relies on extracting and interpreting features of supra-threshold sound. Many normal-hearing listeners struggle to perform certain supra-threshold auditory tasks, and debate persists as to whether such difficulties originate from deficits in cognitive processing or in peripheral, sensory encoding. In this work, we show that there are large individual differences among normal-hearing adults (18 to 55 years), who were asked to report a stream of digits located directly ahead in a simulated rectangular room. Simultaneous, competing masker digit streams were simulated at locations 15° left and right of center, and the level of reverberation was adjusted to vary task difficulty. Performance was best in the anechoic condition and worst in the high-reverberation condition, but listeners nearly always reported a digit from one of the three competing streams, showing that reverberation did not render the digits unintelligible. Most importantly, inter-subject differences were extremely large. These differences were not significantly correlated with age, memory span, or hearing status. They were, however, correlated with behavioral differences in the ability to detect small frequency modulations in pure tones and with the strength of the frequency following response (FFR), a physiological measure of spectro-temporal detail encoding in supra-threshold sounds early in the auditory pathway. The decomposition of the FFR into envelope and carrier components shows that envelope frequency following is the preferred cue for completing the spatial attention task, but it degrades with early aging. As a result, older listeners depend more on carrier phase locking cues than younger people. These results suggest that differences in peripheral encoding help explain individual differences in the ability to communicate in challenging settings, but that aging also has a separate, dissociable effect on early encoding in the auditory system. Tests like these may help tease apart contributions of peripheral and central deficits to communication impairments, ultimately leading to new approaches for helping listeners cope with complex listening environments. / 2031-01-02

This thesis is concerned with a novel local threshold segmentation algorithm for digital images incorporating shape information. In image segmentation, most local threshold algorithms are based only on intensity analysis. In many applications where an image contains objects with a similar shape, in addition to the intensity information, some prior known shape attributes could be exploited to improve the segmentation. The goal of this work is to design a local threshold algorithm that includes shape information to enhance the segmentation quality. The algorithm adaptively selects a local threshold. Shape attribute distributions are learned from typical objects in ground truth images. Local threshold for each object in an image to be segmented is chosen to maximize probabilities in these shape attributes distributions. Then for the application of the oil sand image segmentation, a supervised classifier is introduced to further enhance the segmentation accuracy. The algorithm applies a supervised classifier trained by shape features to reject unwanted fragments. To meet different image segmentation intents in practical applications, we investigate a variety of combination of shape attributes and classifiers, and also look for the optimal one. Experiments on oil sand images have shown that the proposed algorithm has superior performance to local threshold approaches based on intensity information in terms of segmentation quality.

Quantum error correcting codes have been introduced to encode the data bits in extra redundant bits in order to accommodate errors and correct them. However, due to the delicate nature of the quantum states or faulty gate operations, there is a possibility of catastrophic spread of errors which might render the error correction techniques ineffective. Hence, in this thesis we concentrate on how various operations can be carried out fault-tolerantly so that the errors are not propagated in the same block. We prove universal fault-tolerance for nonbinary CSS codes. This thesis is focussed only on nonbinary quantum codes and all the results pertain to nonbinary codes. Efficient error detection and correction techniques using fault-tolerant techniques can help as long as we ensure that the gate error probability is below a certain threshold. The calculation of this threshold is therefore important to see if quantum computations are realizable or not, even with fault-tolerant operations. We derive an expression to compute the gate error threshold for nonbinary quantum codes and test this result for different classes of codes, to get codes with best threshold results.

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Thesis (Ph.D.) -- McMaster University, 2001. / Includes bibliographical references. Also available via World Wide Web.