Integrated Calendar

MRI is truly unique in that contrast and acquisition can be manipulated to highlight a many tissues and physiologic processes at a wide range of speeds and resolutions. In the early 90’s, echo-planar imaging (EPI), a rapid imaging method that required specialized hardware, enabled time series acquisition of images - each collected in tens of milliseconds. Susceptibility contrast weighting sensitized the images to subtle shifts in blood oxygenation, allowing localized brain activation changes in oxygenation to be observed in near real time, thus introducing fMRI to the world. Since this breakthrough, fMRI has continued to advance in sophistication and impact. Higher fields, higher performance gradients, and novel pulse sequences and contrasts have allowed ever more subtle effects to be observed at higher fidelity, speed, and resolution. The signal became more informative as brain activation paradigms and processing methods advanced in conjunction with our deeper understanding of artifact and signal. Importantly, our insight into brain structure and function motivated and informed the experiments and, likewise, was enriched by the results.

In this talk, I’ll trace the progress in fMRI, showing how the creative tension between advances in technology, processing, and our understanding of brain activation dynamics and physiology generated many of the innovations. My talk will include retinotopy, event-related fMRI, multi-echo EPI, resting state fMRI, connectivity, representational similarity analysis, decoding, naturalistic stimuli, inter-subject correlation, high field, and layer fMRI. Lastly, I’ll describe some of the technical and practical challenges facing the field today.

Self-assembly of inorganic nanoparticles (NPs) into ordered structures has led to a wide range of materials with unique optical, electronic, and catalytic properties. Various interactions have been employed to direct the crystallization of NPs, including van der Waals forces, hydrogen bonding, and magnetic dipolar interactions. Among them, Coulombic interactions have remained largely unexplored, owing to the rapid charge exchange between spherical NPs bearing high densities of opposite charges (superionic NPs). In this talk, I will describe a new method to assemble superionic NPs under conditions that preserve their native surface charge density. Our methodology was used to assemble oppositely charged NPs (“spherical polyelectrolytes”) into highly ordered assemblies exhibiting previously unknown morphologies.

The classical literature on streaming algorithms has mainly studied two types of algorithms: randomized and deterministic.
However, almost all classical analyses of randomized streaming algorithms assume that the stream is “fixed in advance”, making them unfit for use in adaptive settings where future stream updates depend on previous outputs of the algorithm. Meanwhile, deterministic algorithms are guaranteed to work in adaptive settings, but many important problems in the streaming literature do not admit efficient deterministic algorithms. This raises the question of whether one can enjoy both worlds: do there exist robust randomized streaming algorithms, which are space-efficient and provably work in adaptive settings?

The recent couple of years have seen a surge of work on this topic, starting from a generic robustification framework we developed, which turns “standard” randomized algorithms into robust ones. As it turns out, the answer to the above question is largely positive for insertion-only streams, but still unknown in general turnstile (insertion-deletion) streams. I will present our framework and mention several lines of follow-up work on this topic, including improved frameworks, results for specific algorithms, and connections to a wide range of topics within computer science, including differential privacy, cryptography, learning theory and others. Focusing on classical problems such as distinct elements counting and norm estimation, I will highlight what we know in the turnstile setting and present several directions for future work.

Based in part on joint works with Rajesh Jayaram, David Woodruff, and Eylon Yogev, and with Talya Eden and Krzysztof Onak. (I will also briefly mention related joint works with Noga Alon, Yuval Dagan, Shay Moran, Moni Naor, and Eylon Yogev.)