MIT Theses https://hdl.handle.net/1721.1/7582 Tue, 24 Nov 2020 10:10:06 GMT 2020-11-24T10:10:06Z Predicting the obvious : a machine learning approach to superstar inventions https://hdl.handle.net/1721.1/128608 Predicting the obvious : a machine learning approach to superstar inventions Raymond, Lindsey Rebecca. While patent citations are a common way to measure innovative output, their use as a measure of invention quality involves a paradox. How can we use an ex-post measure of impact (the number of received citations) to identify the ex-ante quality of a given innovation? This paper proposes a novel method of measuring patent quality using patent text and sections of the patent citation distribution with the highest signal to noise ratio. We provide empirical evidence that the bias from using citations to measure quality varies by location in the patent distribution and, contrary to what one might expect, superstar patents are the most predictable while patents in the middle of the distribution are most contaminated with noise. We show predictability of patents increases monotonically over the patent distribution - with the most valuable being the most predictable - and removing the middle of the distribution has little impact on accuracy. We also provide suggestive evidence on the importance of patent text in measuring quality and conclude with suggestive geometric evidence we are capturing differences in underlying patent characteristics. As our model demonstrates, our empirical results generalize to other situations involving highly skewed processes observed with noise. This paper also has implications for empirical work using citation weighted metrics. Thesis: S.M. in Management Research, Massachusetts Institute of Technology, Sloan School of Management, September, 2019; Cataloged from PDF of thesis.; Includes bibliographical references (pages 36-41). Tue, 01 Jan 2019 00:00:00 GMT https://hdl.handle.net/1721.1/128608 2019-01-01T00:00:00Z Development of a reactive peptide sequence for site-selective bioconjugation https://hdl.handle.net/1721.1/128606 Development of a reactive peptide sequence for site-selective bioconjugation Tuang, Suan Lian. Achieving catalyst-free, site-selective modification of proteins in water is a significant challenge in chemical biology. Issues of residue specificity, site-selectivity, reagent stability, and reaction rate are pervasive in this field, and despite advances over the past few decades, achieving fast, pinpoint modifications of complex molecules remains a tremendous obstacle. Herein, we describe the development of a nine-amino acid motif (Met-Cys-Pro-Phe-Leu-Pro-Val-Val-Tyr) termed engineered reaction (EnAct) tag. The EnAct interface, discovered by iterative screening of peptide libraries, consists of a reactive peptide (EnAct tag) that undergoes rapid (second-order rate constant, k ~ 150 M?1 s?1) nucleophilic aromatic substitution with a perfluoroarene-containing peptide (EnAct probe).; Bioconjugation reactions centered on peptide interfaces are emerging as promising strategies to prepare homogeneous biological conjugates, and our results with the EnAct interface represent a 210-fold increase in reaction rate over the previous standard for this class of cysteine arylation. Furthermore, the EnAct sequence consists of all-natural amino acids and thus enables the facile genetic engineering of the sequence onto proteins of interest. We disclose here the incorporation of the EnAct sequence at the C-termini of the IgG antibody trastuzumab heavy chains, which were subsequently conjugated to the EnAct probe with excellent site-selectivity, despite the 32 other Cys residues on this protein. Remarkably, this system's rapid kinetics enabled quantitative conversion in 1.5 hours and at lower substrate concentrations.; Finally, this bioconjugation reaction is still selective even in the complex environments of cell lysate mixtures, illustrating the enhanced selectivity and rapid reactivity of the EnAct interface. The appreciable increase in cysteine arylation rate and selectivity achieved with the EnAct sequenced represents a new standard for site-selective bioconjugations using peptide interfaces. To explore the versatility of the reactive peptide sequence, we found that this reactive peptide enabled aqueous arylations of Cys with small molecule electrophiles in mostly water, which was not previously accessed with this class of electrophiles. Furthermore, the perfluoroarene on the probe was found not only to function as an electrophile for thiol arylation, but also to offer a handle for easy elimination to form dehydroalanine. Thus, the EnAct system represents a powerful, versatile, and selective bioconjugation method. Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemistry, February, 2020; Cataloged from the PDF of thesis. "The Table of Contents does not accurately represent the page numbering"--Disclaimer page.; Includes bibliographical references. Wed, 01 Jan 2020 00:00:00 GMT https://hdl.handle.net/1721.1/128606 2020-01-01T00:00:00Z Palladium catalyzed cross-coupling of esters and amides https://hdl.handle.net/1721.1/128605 Palladium catalyzed cross-coupling of esters and amides Shinabery, Ryan Spence. Over the last 40 years, great strides have been made in the use of palladium as both a catalyst and a reagent for a multitude of chemical transformations that have had tremendous impacts all walks of life from material science to the development and large-scale synthesis of new, novel pharmaceuticals. One such class of reactions is the palladium-catalyzed functionalization of the [alpha]-position of carbonyl compounds using aryl halides. When compared to palladium catalyzed C-N bond forming reactions, these reactions have been understudied and underutilized. Herein we report our efforts towards the development of the [alpha]-arylation of ethyl acetate by using a continuous flow reactor and a unique lithium amide base. Lessons learned from these studies lead to the development of a simple, one-pot protocol for the mono-[alpha]-arylation of amides under palladium catalysis. Previously reported palladium catalyzed [alpha]-arylations of amides with aryl halides required relatively high catalyst loadings, the use of a glove box, excess ligand, pyrophoric reagents, high temperatures or extended reaction times. This protocol affords the desired mono-[alpha]-arylated amide products in good to excellent yields using 1-2 mol % catalyst loading at ambient temperature in as little as two hours. Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemistry, 2019; Cataloged from the PDF of thesis. "The Table of Contents does not accurately represent the page numbering"--Disclaimer page.; Includes bibliographical references. Tue, 01 Jan 2019 00:00:00 GMT https://hdl.handle.net/1721.1/128605 2019-01-01T00:00:00Z Wrestling with systemic edges designing for long-term social change https://hdl.handle.net/1721.1/128604 Wrestling with systemic edges designing for long-term social change Sharrief, Sultan. In this work I seek to show how the lack of nuance in data representation and media practices of the American educational system impedes the design of effective educational interventions for low-income Black youth. First, I argue that data on educational attainment misrepresents race and class thereby masking the educational reality of low-income Black youth. "Data realities" and "Black Hole Data" emerge as hidden phenomena. Next, I analyze a successful transmedia civic initiative, the Ice Bucket Challenge, to illustrate how new media structures and technologies are being used to create new opportunities for social impact. I will then communicate the design process called HIIPE, as well as the work titled Black (w)Hole SC-i52 (Street Cred' iteration 52) that I produced using this process. The goal of this body of work and design approach is to create a new communication system using virtual reality that more clearly articulates the impacts of race and class on educational attainment for low-income Black youth. Thesis: S.M. in Comparative Media Studies, Massachusetts Institute of Technology, Department of Comparative Media Studies/Writing, September, 2019; Cataloged from the official PDF of thesis. "September 2019." "Figure 17 is missing from p.51"--Disclaimer page.; Includes bibliographical references (pages 138-140). Tue, 01 Jan 2019 00:00:00 GMT https://hdl.handle.net/1721.1/128604 2019-01-01T00:00:00Z 狠狠躁天天躁中文字幕_日韩欧美亚洲综合久久_漂亮人妻被中出中文字幕