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Peng Jin, PhD
Professor of Human Genetics, Department of Human Genetics, Emory University School of Medicine
Epigenetic information encoded by 5mC has a profound influence on mammalian development and affects various human diseases. Recent studies have shown that 5mC can be oxidized by TET family dioxygenases stepwise to 5-hydroxymethylcytosine (5hmC) first, then 5-formylcytosine (5fC), and finally 5-carboxylcytosine (5caC). The later oxidation products 5fC and 5caC can be recognized and excised by mammalian DNA glycosylase TDG and subsequently converted to cytosine through base excision repair (BER), resulting in active DNA demethylation in mammals. To understand the roles of these new cytosine modifications in gene regulation, we have developed a series of tools to profile the genome-wide distribution for each modification. Our analyses suggest a dynamic regulation of these new DNA modifications during neuronal differentiation, neurodevelopment and aging. I will discuss our most recent findings on the roles of these cytosine modifications in gene regulation, and their involvements in neurodevelopment and autism.
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Host: Jim Glass and Victor Zue
Host Affiliation: MIT CSAIL
What effect does language have on people, and what effect do people have on language?
You might say in response, "Who are you to discuss these problems?" and you would be right to do so; these are Major Questions that science has been tackling for many years. But as a field, I think natural language processing and computational linguistics have much to contribute to the conversation, and I hope to encourage the community to further address these issues. To this end, I'll describe two efforts I've been involved in.
The first project provides evidence that in group discussions, power differentials between participants are subtly revealed by how much one individual immediately echoes the linguistic style of the person they are responding to. We consider multiple types of power: status differences (which are relatively static), and dependence (a more ''situational'' relationship). Using a precise probabilistic formulation of the notion of linguistic coordination, we study how conversational behavior can reveal power relationships in two very different settings: discussions among Wikipedians and arguments before the U.S. Supreme Court.
Our second project is motivated by the question of what information achieves widespread public awareness. We consider whether, and how, the way in which the information is phrased --- the choice of words and sentence structure --- can affect this process. We introduce an experimental paradigm that seeks to separate contextual from language effects, using movie quotes as our test case. We find that there are significant differences between memorable and non-memorable quotes in several key dimensions, even after controlling for situational and contextual factors. One example is lexical distinctiveness: in aggregate, memorable quotes use less common word choices (as measured by statistical language models), but at the same time are built upon a scaffolding of common syntactic patterns.
Joint work with Justin Cheng, Cristian Danescu-Niculescu-Mizil, Jon Kleinberg, and Bo Pang.
Lillian Lee is a professor of computer science at Cornell University. Her research interests include natural language processing, information retrieval, and machine learning. She is the recipient of the inaugural Best Paper Award at HLT-NAACL 2004 (joint with Regina Barzilay), a citation in "Top Picks: Technology Research Advances of 2004" by Technology Research News (also joint with Regina Barzilay), and an Alfred P. Sloan Research Fellowship; and in 2013, she was named a Fellow of the Association for the Advancement of Artificial Intelligence (AAAI). Her group's work has received several mentions in the popular press, including The New York Times, NPR's All Things Considered, and NBC's The Today Show.
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Sponsor: Earth, Atmospheric, and Planetary Sciences (EAPS)
Dr. James Hansen, formerly Director of the NASA Goddard Institute for Space Studies, is Adjunct Professor and at Columbia University’s Earth Institute, where he directs a program in Climate Science, Awareness and Solutions. He was trained in physics and astronomy in the space science program of Dr. James Van Allen at the University of Iowa. His early research on the clouds of Venus helped identify their composition as sulfuric acid. Since the late 1970s, he has focused his research on Earth's climate, especially human-made climate change. Dr. Hansen is best known for his testimony on climate change to congressional committees in the 1980s that helped raise broad awareness of the global warming issue. He was elected to the National Academy of Sciences in 1995 and was designated by Time Magazine in 2006 as one of the 100 most influential people on Earth. He has received numerous awards including the Carl-Gustaf Rossby and Roger Revelle Research Medals, the Sophie Prize and the Blue Planet Prize. Dr. Hansen is recognized for speaking truth to power, for identifying ineffectual policies as greenwash, and for outlining actions that the public must take to protect the future of young people and other life on our planet.
One of Professor Hansen's research interests is radiative transfer in planetary atmospheres, especially interpreting remote sounding of the Earth's atmosphere and surface from satellites. He is also interested in the development and application of global numerical models for the purpose of understanding current climate trends and projecting humans' potential impacts on climate.
Charlestown Navy Yard 149 13th St Seminar room 2204 Charlestown, MA
Richard Born, MD.
Harvard Medical School
Department of Neurobiology.
Feedback connections are prevalent throughout the cerebral cortex, yet their function remains poorly understood. Previous studies in anesthetized monkeys found that inactivating feedback from extrastriate visual cortex produced effects in striate cortex that were relatively weak, generally suppressive, largest for visual stimuli confined to the receptive field center, and detectable only at low stimulus contrast. We studied the influence of corticocortical feedback in alert monkeys using cortical cooling to reversibly inactivate visual areas 2 (V2) and 3 (V3) while characterizing receptive field properties in primary visual cortex (V1).We show that inactivation of feedback results in both response suppression and facilitation for stimuli restricted to the receptive field center, in most cases leading to a small reduction in the degree of orientation selectivity but no change in orientation preference. For larger-diameter stimuli that engage regions beyond the center of the receptive field, eliminating feedback from V2/V3 results in strong and consistent response facilitation, effectively reducing the strength of surround suppression in V1 for stimuli of both low and high contrast. For extended contours, eliminating feedback had the effect of reducing end stopping. Inactivation effects were largest for neurons that exhibited strong surround suppression before inactivation, and their timing matched the dynamics of surround suppression under control conditions. Our results provide direct evidence that feedback contributes to surround suppression, which is an important source of contextual influences essential to vision.
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National University of Singapore
Electronic devices all around us contain classical control circuits. Such circuits consist of a network of controllers which can read and write signals to wires of the circuit with the goal to minimize the cost function of the circuit's output signal. Here, we propose the use of shared entanglement between controllers as a resource to improve the performance of otherwise purely classical control circuits. We study a well-known example by Witsenhausen from the classical control literature and demonstrate that allowing two controllers to share entanglement improves their ability to control. More precisely, we exhibit a family of circuits in which the the cost function using entanglement stays constant, but the minimal cost function without entanglement grows arbitrarily large. This demonstrates that entanglement can be a powerful resource in a classical control circuit. Joint work with Duy Nguyen Truong and Matthew McKague. Preprint available at http://arxiv.org/abs/1307.1569
Stephanie Wehner is an Associate Professor in the School of Computing at the National University Singapore and the Centre for Quantum Technologies. Prior to coming to Singapore in 2010, she spent two years as a Postdoctoral Fellow at the California Insitute of Technology, and three and half as a PhD student at the University of Amsterdam. Stephanie is one of the founders of QCRYPT, presently the largest conference in quantum cryptography, and was elected to the Steering Committee of QIP in 2013. Before entering academia, she worked in industry as a professional hacker.
Her research interests include quantum cryptography, quantum information theory, and the application of information-theoretic techniques to physics.
Tisch University Professor
A growing set of applications take place on the social network neighborhoods that individuals form on-line. These network neighborhoods exhibit a rich graph-theoretic structure, and they form an interesting substrate on which a range of information-sharing and social processes take place.
We discuss some of the issues that arise in this domain, including the flow of information through network neighborhoods, the algorithmic management of this information, and the problem of identifying an individual's most significant social ties from a snapshot of his or her neighborhood. This latter question involves the analysis of a type of network measure that we refer to as "dispersion", measuring the extent to which the mutual friends of two people are well-connected.
Jon Kleinberg is the Tisch University Professor in the Computer Science Department at Cornell University. His research focuses on issues at the interface of networks and information, with an emphasis on the social and information networks that underpin the Web and other on-line media. He is a member of the National Academy of Sciences, the National Academy of Engineering, and the American Academy of Arts and Sciences, and serves on the Computer and Information Science and Engineering (CISE) Advisory Committee of the National Science Foundation, and the Computer Science and Telecommunications Board (CSTB) of the National Research Council. He is the recipient of MacArthur, Packard, and Sloan Foundation Fellowships, as well as awards including the Nevanlinna Prize, the Lanchester Prize, and the ACM-Infosys Foundation Award in the Computing Sciences.
The talk is based on joint work with Lars Backstrom, Cristian Danescu-Niculescu-Mizil, Lillian Lee, Cameron Marlow, and Johan Ugander.
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Prof. Gilead Tadmor
Department of Electrical & Computer Engineering and Mathematics
Active fluid flow control dates to Prandtl's groundbreaking work on shear layer flows during the first decade of the 20th century and has been the subject of intensive experimental and theoretical research over the past several decades. The potential benefits of success are of truly epic proportions. Yet to date there is no noticeable penetration of active flow control into the realm of engineered products. The talk concerns one largely outstanding hurdle, i.e., the development of low order models suitable for the design of feedback loops for active fluid flow control.
The focus will be on data driven Galerkin models. Motivated by a number of appealing properties, these models are of ubiquitous use in the field. That is the case notwithstanding a persistent mismatch between fundamental axioms underlying the conventional Galerkin framework and basic tenets of most active flow control systems. We shall highlight a few of these difficulties and suggest possible modifications, to accommodate the needs of feedback flow control design.