RadiX-Net: Structured Sparse Matrices for Deep Neural Networks

The sizes of deep neural networks (DNNs) are rapidly outgrowing the capacity of hardware to store and train them. Research over the past few decades has explored the prospect of sparsifying DNNs before, during, and after training by pruning edges from the underlying topology. The resulting neural network is known as a sparse neural network. More recent work has demonstrated the remarkable result that certain sparse DNNs can train to the same precision as dense DNNs at lower runtime and storage cost. An intriguing class of these sparse DNNs is the X-Nets, which are initialized and trained upon a sparse topology with neither reference to a parent dense DNN nor subsequent pruning. We present an algorithm that deterministically generates RadiX-Nets: sparse DNN topologies that, as a whole, are much more diverse than X-Net topologies, while preserving X-Nets' desired characteristics. We further present a functional-analytic conjecture based on the longstanding observation that sparse neural network topologies can attain the same expressive power as dense counterpartsComment: 7 pages, 8 figures, accepted at IEEE IPDPS 2019 GrAPL workshop. arXiv admin note: substantial text overlap with arXiv:1809.0524

Training Behavior of Sparse Neural Network Topologies

Improvements in the performance of deep neural networks have often come through the design of larger and more complex networks. As a result, fast memory is a significant limiting factor in our ability to improve network performance. One approach to overcoming this limit is the design of sparse neural networks, which can be both very large and efficiently trained. In this paper we experiment training on sparse neural network topologies. We test pruning-based topologies, which are derived from an initially dense network whose connections are pruned, as well as RadiX-Nets, a class of network topologies with proven connectivity and sparsity properties. Results show that sparse networks obtain accuracies comparable to dense networks, but extreme levels of sparsity cause instability in training, which merits further study.Comment: 6 pages. Presented at the 2019 IEEE High Performance Extreme Computing (HPEC) Conference. Received "Best Paper" awar

Evaluating Wireless Carrier Consolidation Using Semiparametric Demand Estimation

The US mobile phone service industry has dramatically consolidated over the last two decades. One justification for consolidation is that merged firms can provide consumers with larger coverage areas at lower costs. We estimate the willingness to pay for national coverage to evaluate this motivation for past consolidation. As market level quantity data is not publicly available, we devise an econometric procedure that allows us to estimate the willingness to pay using market share ranks collected from a popular online retailer, Amazon. Our semiparametric maximum score estimator controls for consumers' heterogeneous preferences for carriers, handsets and minutes of calling time. We find that national coverage is strongly valued by consumers, providing an efficiency justification for across-market mergers. The methods we propose can estimate demand for other products using data from Amazon or other online retailers where quantities are not observed, but product ranks are observed. Since Amazon data can easily be gathered by researchers, these methods may be useful for the analysis of other product markets where high quality data are not publicly available.Technology and Industry

Evaluating Wireless Carrier Consolidation Using Semiparametric Demand Estimation

The US mobile phone service industry has dramatically consolidated over the last two decades. One justification for consolidation is that merged firms can provide consumers with larger coverage areas at lower costs. We estimate the willingness to pay for national coverage to evaluate this motivation for past consolidation. As market level quantity data is not publicly available, we devise an econometric procedure that allows us to estimate the willingness to pay using market share ranks collected from a popular online retailer, Amazon. Our semiparametric maximum score estimator controls for consumers%u2019 heterogeneous preferences for carriers, handsets and minutes of calling time. We find that national coverage is strongly valued by consumers, providing an efficiency justification for across-market mergers. The methods we propose can estimate demand for other products using data from Amazon or other online retailers where quantities are not observed, but product ranks are observed. Since Amazon data can easily be gathered by researchers, these methods may be useful for the analysis of other product markets where high quality data are not publicly available.

Design and synthesis of probes for detection of protein-protein interaction and RNA localization

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2005.Includes bibliographical references.The use of the ketone biotin - benzophenone-biotin hydrazide system for detecting the formation of cyan fluorescent protein and NF-kappaB p50 dimers was assessed. A series of benzophenone-based probes were synthesized and tested for photocrosslinking activity to investigate the efficiency of photocrosslinking in these systems. Three series of small molecule probes were synthesized for the selection of ribozymes from a random sequence pool. Solid-phase immobilized fluorescein and fluorescein phosphates were synthesized for the indirect selection of a fluorescein phosphatase ribozyme. A corresponding thiophosphate analog was created for the in-gel selection of a thiophosphatase ribozyme via APM-PAGE. Finally, a series of fluorescein-nucleoside phosphate conjugates was designed and synthesized for use in the solution phase preparation of a fluorogenic ribozyme substrate, and later immobilization of this substrate on a silyl resin for direct ribozyme selection.by Jeremy Adam Ryan.S.M

Why we were not there: American intervention policy and the failure to act in Rwanda

This work addresses questions about why the United States did not get involved in intervention efforts during the 1994 Rwandan genocide. To answer this, the work will analyze the history of Rwanda leading up to and through the genocide and changes in American policy towards Africa and military intervention. After presenting and analyzing the information, this work will argue that the United States did not send military aid to Rwanda because American policy makers did not hold Rwanda as a key foreign interest, there was no large-scale call to assist the Rwandans coming from the American public and that American policy makers did not want to involve American combat personnel in future civil wars after the devastating failure of Operation Restore Hope in Somalia. The conclusion of the paper will analyze how American-Rwanda relations have changed in the years since the genocide

EXPERIMENTAL FLOW VISUALIZATION FOR CORRUGATED AIRFOILS AT LOW REYNOLDS NUMBER INCLUDING DEVELOPMENT OF A PITCH AND PLUNGE FIXTURE

Micro Air Vehicles (MAV’s) have small size and extreme maneuverability which makes them ideal for surveillance. Propulsion mechanisms include propellers, rotors, and flapping airfoils. Flapping motions, along with biologically-inspired wing profiles, are of interest due to their use of natural physics. Corrugated airfoil structures appears to have poor aerodynamic performance at higher Reynolds numbers, but serve well at Re\u3c10,000. Understanding flow structures around corrugated profiles and comparing them to a standard airfoil will aid in understanding how these corrugated profiles perform well and have been adopted by some of nature’s most acrobatic flyers. Motivation for this investigation is to compare static flow visualizations of corrugated profiles to a standard National Advisory Committee for Aeronautics (NACA) airfoil from low to high angles of attack and further observe flow structure development of a pitching and plunging flat plate at a Re\u3c10,000 and a Strouhal number relevant to natural fliers. The static visualization was conducted at Re=1,000 with a NACA 0012 airfoil and two corrugated models. The Pitch and Plunge Fixture (PPF) developed was constructed by simplifying flapping wings as a two degree of freedom motion in plunge (translation) and pitch (rotation). Results obtained from the PPF were compared with a numerical simulation

Solving the World\u27s Problems: Walker Percy\u27s Cultural Critique in Love in the Ruins

This thesis examines Walker Percy\u27s manipulation of time in Love in the Ruins as a component of indirectly communicating his solution to problems in twentieth-century Western society: existential authenticity. By examining this often overlooked novel, I clarify the process by which Percy conveys his solution and the difficulties inherent in his attempts to do so. Research shows how Percy perceived such problems stemmed from the tendency of postmodern thought to place human subjective experience within an overarching, objective framework. These problems that Percy exaggerates in the novel are essentially distractions of immediacy that lead the characters away from choosing authentic existence. He juxtaposes his critique of culture with time devices, such as his selection of genre, his use of flashback, and his persistent present tense narration, so that the reader can reflectively contemplate the concept of eternity, a major component of the existential authenticity he prescribes. The reader\u27s recognition of the tension between the two modes of time, immediacy and eternity, is crucial to identifying the solution Percy indirectly communicates

Doctor of Philosophy

dissertationSustainability has become an omnipresent concept within our culture and society. The importance of sustainability continues to grow as resources are depleted and cultures are irreparably damaged. The science of sustainability has taken on many forms such as renewable energy sources, transportation systems, political platforms, and sustainable tourism. Within the tourism industry, sustainability is now being manifested through certification programs. These programs allow tourism operators to reduce environmental impacts and incorporate sociocultural considerations into business practices, all the while maintaining, if not improving, the financial status of their businesses. This study examined why Bed and Breakfast (B&B) operators in the United States chose to participate or not in sustainable tourism certification programs. Ajzen's theory of planned behavior was employed to investigate the attitudes, social influence, perceived behavioral control, and belief structures of the B&B operators to further understanding of the behavioral intention of B&B operators and their participation in sustainable tourism certification programs