Continuous-time analog circuits for statistical signal processing

Thesis (Ph. D.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2003.Vita.Includes bibliographical references (p. 205-209).This thesis proposes an alternate paradigm for designing computers using continuous-time analog circuits. Digital computation sacrifices continuous degrees of freedom. A principled approach to recovering them is to view analog circuits as propagating probabilities in a message passing algorithm. Within this framework, analog continuous-time circuits can perform robust, programmable, high-speed, low-power, cost-effective, statistical signal processing. This methodology will have broad application to systems which can benefit from low-power, high-speed signal processing and offers the possibility of adaptable/programmable high-speed circuitry at frequencies where digital circuitry would be cost and power prohibitive. Many problems must be solved before the new design methodology can be shown to be useful in practice: Continuous-time signal processing is not well understood. Analog computational circuits known as "soft-gates" have been previously proposed, but a complementary set of analog memory circuits is still lacking. Analog circuits are usually tunable, rarely reconfigurable, but never programmable. The thesis develops an understanding of the convergence and synchronization of statistical signal processing algorithms in continuous time, and explores the use of linear and nonlinear circuits for analog memory. An exemplary embodiment called the Noise Lock Loop (NLL) using these design primitives is demonstrated to perform direct-sequence spread-spectrum acquisition and tracking functionality and promises order-of-magnitude wins over digital implementations. A building block for the construction of programmable analog gate arrays, the "soft-multiplexer" is also proposed.by Benjamin Vigoda.Ph.D

A nonlinear dynamic system for spread spectrum code acquisition

Thesis (S.M.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 1999.Includes bibliographical references (leaves 88-89).Nonlinear differential equations and iterated maps can perform any computation. Sometimes, the most difficult part of performing a useful computation, however, is writing the program. Furthermore, in practice, we often need to build special purpose computing hardware suited to run a particular program. Nonlinear dynamics provides a novel and useful language for constructing "algorithms" and "computer architectures." We apply the language of nonlinear dynamics to solve a fast coding problem which has previously been implemented by a Digital Signal Processor chip in digital wireless receivers. We eventually hope to produce a novel physical system which exhibits the nonlinear dynamics we require, thereby creating one of the first nonlinear dynamic systems engineered to perform a practical computation. This system, called an Analog Feedback Shift Register (AFSR), should be a faster, more reliable, less expensive, and lower power Spread Spectrum (SS) code acquisition system for wireless receivers. A prohibitive factor in creating ubiquitous short range, digital radio transceivers is the difficulty and expense of creating a mechanism for locking onto the incoming Spread Spectrum code sequence. AFSR is also potentially useful in other applications where low cost, low power channel sharing or addressing is required, for example in wireless auto-identification tags.by Benjamin William Vigoda.S.M

Reweighted LP Decoding for LDPC Codes

We introduce a novel algorithm for decoding binary linear codes by linear programming (LP). We build on the LP decoding algorithm of Feldman and introduce a postprocessing step that solves a second linear program that reweights the objective function based on the outcome of the original LP decoder output. Our analysis shows that for some LDPC ensembles we can improve the provable threshold guarantees compared to standard LP decoding. We also show significant empirical performance gains for the reweighted LP decoding algorithm with very small additional computational complexity

JamiOki-PureJoy: A Game Engine and Instrument for Electronically-Mediated Musical Improvisation ABSTRACT

JamiOki-PureJoy is a novel electronically mediated musical performance system. PureJoy is a musical instrument; A highly flexible looper, sampler, effects processor and sound manipulation interface based on Pure Data, with input from a joystick controller and headset microphone. PureJoy allows the player to essentially sculpt their voice with their hands. JamiOki is an engine for running group-player musical game pieces. JamiOki helps each player by ‘whispering instructions ’ in their ear. Players track and control their progress through the game using a graphical display and a touch-sensitive footpad. JamiOki is an architecture for bringing groups of players together to express themselves musically in a way that is both spontaneous and formally satisfying. The flexibility of the PureJoy instrument offers to JamiOki the ability for any player to play any requested role in the music at any time. The musical structure provided by JamiOki helps PureJoy players create more complex pieces of music on the fly with spontaneous sounds, silences, themes, recapitulation, tight transitions, structural hierarchy, interesting interactions, and even friendly competition. As a combined system JamiOki-PureJoy is exciting and fun to play

Illuminating biological pathways for drug targeting in head and neck squamous cell carcinoma.

Head and neck squamous cell carcinoma (HNSCC) remains a morbid disease with poor prognosis and treatment that typically leaves patients with permanent damage to critical functions such as eating and talking. Currently only three targeted therapies are FDA approved for use in HNSCC, two of which are recently approved immunotherapies. In this work, we identify biological pathways involved with this disease that could potentially be targeted by current FDA approved cancer drugs and thereby expand the pool of potential therapies for use in HNSCC treatment. We analyzed 508 HNSCC patients with sequencing information from the Genomic Data Commons (GDC) database and assessed which biological pathways were significantly enriched for somatic mutations or copy number alterations. We then further classified pathways as either "light" or "dark" to the current reach of FDA-approved cancer drugs using the Cancer Targetome, a compendium of drug-target information. Light pathways are statistically enriched with somatic mutations (or copy number alterations) and contain one or more targets of current FDA-approved cancer drugs, while dark pathways are enriched with somatic mutations (or copy number alterations) but not currently targeted by FDA-approved cancer drugs. Our analyses indicated that approximately 35-38% of disease-specific pathways are in scope for repurposing of current cancer drugs. We further assess light and dark pathways for subgroups of patient tumor samples according to HPV status. The framework of light and dark pathways for HNSCC-enriched biological pathways allows us to better prioritize targeted therapies for further research in HNSCC based on the HNSCC genetic landscape and FDA-approved cancer drug information. We also highlight the importance in the identification of sub-pathways where targeting and cross targeting of other pathways may be most beneficial to predict positive or negative synergy with potential clinical significance. This framework is ideal for precision drug panel development, as well as identification of highly aberrant, untargeted candidates for future drug development