Visitor Tech Talks

The exchange of indivisible goods without money addresses a variety of constrained economic settings where a medium of exchange—such as money—is considered inappropriate. Participants are either matched directly with another participant or, in more complex domains, in barter cycles and chains with other participants before exchanging their endowed goods. We show that techniques from computer science and operations research, combined with the recent availability of massive data and inexpensive computing, can guide the design of such matching markets and enable the markets by running them in the real world. A key application domain for our work is kidney exchange, an organized market where patients with end-stage renal failure swap willing but incompatible donors. We present new models that address three fundamental dimensions of kidney exchange: (i) uncertainty over the existence of possible trades, (ii) balancing efficiency and fairness, and (iii) inherent dynamism. For each dimension, we design scalable branch-and-price-based integer programming market clearing methods. Next, we combine these dimensions, along with high-level human-provided guidance, into a unified framework for learning to match in a general dynamic setting. This framework, which we coin FutureMatch, takes as input a high-level objective (e.g., “maximize graft survival of transplants over time”) decided on by experts, then automatically learns based on data how to make this objective concrete and learns the “means” to accomplish this goal—a task that, in our experience, humans handle poorly.

We complement our theoretical models and claims with extensive experiments on real data from the United Network for Organ Sharing (UNOS) Kidney Paired Donation Pilot Program, a large kidney exchange clearinghouse consisting of 66% of the transplant centers in the US. The UNOS exchange uses our algorithms and software to autonomously match donors to patients twice per week.

Changing someone's opinion is arguably one of the most important challenges of social interaction. The underlying process proves difficult to study: it is hard to know how someone's opinions are formed and whether and how someone's views shift. Fortunately, ChangeMyView, an active community on Reddit, provides a platform where users present their own opinions and reasoning, invite others to contest them, and acknowledge when the ensuing discussions change their original views. In this work, we study these interactions to understand the mechanisms behind persuasion. We find that persuasive arguments are characterized by interesting patterns of interaction dynamics, such as participant entry-order and degree of back-and-forth exchange. Furthermore, by comparing similar counterarguments to the same opinion, we show that language factors play an essential role. In particular, the interplay between the language of the opinion holder and that of the counterargument provides highly predictive cues of persuasiveness. Finally, since even in this favorable setting people may not be persuaded, we investigate the problem of determining whether someone's opinion is susceptible to being changed at all. For this more difficult task, we show that stylistic choices in how the opinion is expressed carry predictive power.

Today we find ourselves jumping from our iPhones to our tablets, from our desktops to our laptops, and back again. Little do we know that we are living out the multimedia dreams of several dozen Cold War social scientists, a handful of Bauhaus artists, and the musician John Cage. This talk tracks those dreams from the anti-Fascist propaganda of World War II to the psychedelic Happenings of the 1960s. Along the way, it lays bare the long-buried cultural roots of today’s surveillance driven, peer-to-peer media environment, and with them, of Facebook itself.

Peer effects are an important component of both technology and idea/'policy' adoption. Two key research questions emerge: First, do peer effects dominate geographic spillovers, or vice versa? E.g. does an individual 'conversion' on purchasing a new technology increase the likelihood of friends taking the same step, or does geographic proximity dominate? Second, in cases where a campaign seeks an ecosystem-wide shift (e.g., a change in public opinion in support of a 'green' policy), what are the tradeoffs between individual actions (e.g., buying a 'green' product) versus costlier, 'collective' actions requiring coordination (e.g., making creative content to persuade others). Two theories point in opposite directions: (i) 'Single-action bias' implies that taking one costly step precludes another; e.g., buying a 'green' product implies there's less time and money to spend on other green objectives; (ii) 'Self-perception theory' points in the opposite direction: see yourself as greener by having bought the technology, take further green steps. Psychologists and sociologists have unearthed anecdotal evidence for both theories. What is lacking is a convincing, large-scale test, with sufficient controls to detect the role of peer and geographic effects.

In addition to their broadening market and commercial applications, games are an increasingly important form of artistic expression and social practice. As we explore the latest immersive and connected technologies, we shape our communities and cultures in ways we're only just beginning to understand.

In this talk I will review my history as a game designer and co-founder, why I believe diversity is so important within our community, and how a new program I'm directing at UC Santa Cruz brings diversity, technology and experimental platforms together in one place.

In this talk, I will present our work on large scale social systems to unveil the social phenomena emerging from individual users’ interactions. I will focus on demographic inference, discovering social strategies and network superfamilies, link prediction, and scientific impact prediction. I will present the results on a country-wide cell phone communication network, 116 different types of social and information network (largest study on structural diversity and network superfamilies), and an author collaboration network with 1.7 million authors and 2 million papers. This work offers the potential to understand the fundamental principles that drive our social interactions, activities, and network evolution and dynamics.

Pakistan is the 6th largest country in the world by population. Over half of the population lives below $2 poverty line; 40% of the adult population is unable to read or write; 30% lack access to clean drinking water; 85% of the world's polio cases are from Pakistan. At the same time, with over 137 Million cellphone users in Pakistan, almost every household has a cellphone; Pakistani's sent over 320 Billion SMS last year; you can buy a smartphone for less than $50 in Pakistan.

In this talk, I will present a number of smartphone-based systems we have developed to monitor government work, improve civic services and collect citizen feedback in Pakistan. This talk will explain how we used smartphones to track and contain a Dengue epidemic, identify crime hotspots, measure teacher presence and monitor visits of rural doctors. I will specifically talk about an innovative vaccinator tracking application that has totally transformed the vaccination program in Pakistan to eradicate Polio.

In daily life, we exploit a variety of input and output modalities, and the modalities that involve contact with our bodies can dramatically affect our ability to experience and express ourselves. To understand the human perception in a scientific aspect, we must focus on both individual and combined effects of our sensory modalities. Therefore, in the pursuit for applications of enhanced reality and communication, we should give attention to multi/cross modal effect both in micro and macro sense. This talk will present several approaches that use multi/cross modal interfaces. They include Augmented Haptics, Telexistence, Optical Camouflage, Stop-Motion Goggle and Galvanic Vestibular Stimulation.

See his TEDxTokyo short 6 min talk on one of the projects.