Exciton-photon coupling in Perovskite-nanocrystals-based photonic systems
A. Paul Alivisatos, Departments of Chemistry, and Materials Science and Engineering, UC Berkeley
Tal Ellenbogen, Department of Physical Electronics, Tel Aviv University
Lead-halides with the perovskites crystal structure, emerged into the spot-light after demonstrating remarkable conversion efficiencies in photovoltaics and light emitting diodes. This class of materials has astonished the scientific community, with fabricated devices yielding 20% photoelectric conversion efficiencies after only a few years of research, comparable to those achieved in silicon based devices after decades. The remarkable performance of these materials raises fundamental questions as to what gives rise to their unique photophysical properties to make them such good photo-convertors. Recently, it was suggested that strong-light matter interactions in perovskites result in formation of longed-lived large polarons, which protect energetic charge carriers from scattering and recombination, ultimately resulting in efficient photoelectric energy conversion. These intriguing properties of perovskites together with their remarkable electro-optical performance, inspire us to study these materials, better understand them and improve control of their properties, ultimately benefiting future applications. Recently we have utilized perovskite nanocrystals as a model system to study fundamental photo-physical properties of these materials. Through colloidal synthetic techniques, we modify the shape and composition of the nanocrystals to explore their properties, we learned how structure-function relate in perovskites, adding new understandings which are relevant also to bulk material. The next step of coupling perovskites to electromagnetic modes holds great promises and challenges. Here we propose a multidisciplinary approach that combines complementary strengths of two groups in Berkeley and Tel-Aviv University, to study and control the interaction between excitons in low-dimensional perovskite nanocrystals and photonic modes of optical nanostructures.
Deep Assembly: Combining Deep Learning with Geometric Planning to Compute Robust Robot Assembly Sequences
Ken Goldberg, Department of Industrial Engineering and Operations Research, UC Berkeley
Dan Halperin, School of Computer Science, Tel Aviv University
Robust assembly planning is the problem of finding and sequencing motions robust to
small perturbations that can put the initially separated parts of an assembly together to form the assembled product. Algorithms for robust assembly planning can be used to help design products that are more effective to manufacture and for planning of the layout of manufacturing facilities. There are a number of factors that make this problem computationally hard. Indeed progress in devising efficient algorithms for assembly planning has been slow. However, recent developments in several areas, including motion planning, robust geometric computing and machine learning, open the door to new lines of attack on the problem. On the one hand there is significant headway in motion planning in tight quarters both algorithmically as well as in software implementation - this is the Tel Aviv group expertise. On the other hand, advances in deep learning in robotics enable robust manipulation plans for grasping and inserting parts, and advances in supervised learning enable learning of shape similarity and path planning from demonstrations - this is the Berkeley group's expertise. In this convergent research project, we propose to jointly design and implement a hybrid deep learning/computational geometric framework for the robust assembly problem. We aim to test the new hybrid machinery on assembly tasks that are currently considered prohibitively difficult.
Role of Scribble-SnoN-Hippo interactions in regulation of cell proliferation by tissue architecture and polarity
Kunxin Luo, Department of Molecular and Cell Biology, UC Berkeley
Yoav I. Henis, Department of Neurobiology, Tel Aviv University
Tissue architecture is essential for the function and homeostasis of epithelial cells. Although it has been proposed that an intact tissue structure and polarity can govern epithelial cell proliferation, the underlying mechanism remains unclear. The objectives of this project are to determine the molecular mechanism by which tissue architecture regulates the proliferation and differentiation of epithelial cells, and explore how disruption of polarity leads to tumorigenesis. This interdisciplinary project combines the expertise of Dr. Henis (TAU) in biophysical and cell imaging methods with that of Dr. Luo (Berkeley) in biochemistry and cancer. It is aimed to test the hypothesis that the Scribble basolateral (BL) polarity complex regulates the outcome of the Hippo-SnoN interaction to modulate cell proliferation. SnoN is a potent regulator of cell proliferation by modulating the activity of TGFB/Smads, p53, STAT5 and Hippo pathways. We have recently shown that SnoN physically associates with both Scribble and the Lats2 kinase in the Hippo pathway in polarized epithelial cells. We hypothesize that that in polarized cells, SnoN is localized to the BL domain through its interaction with the Scribble polarity complex, where it is downregulated by the Scribble-activated Lats2 kinase. Two specific aims have been designed to test this hypothesis: 1) to investigate the interaction among Scribble, SnoN and Lats2 at the BL domain; (2) to delineate the functional impact of this interaction on mammary epithelial cell proliferation and differentiation. Our study will provide a novel mechanism by which tissue architecture suppresses cell proliferation.
New factors affecting epigenetic processes
Jasper Rine, Department of Molecular and Cell Biology, UC Berkeley
Martin Kupiec, Department of Molecular Microbiology and Biotechnology, Tel Aviv University
Parts of the eukaryotic genomes exist in a densely packed chromatin state, called heterochromatin. Heterochromatin exerts a heritable form of eukaryotic gene repression and contributes to chromosome segregation fidelity and genome stability. Among the most important pending questions in the field of epigenetics is how epigenetic information is perpetuated onto newly replicated DNA and ultimately inherited. Numerous factors that associate with the replication fork are known to impact gene silencing, though the specifics of how each of these factors contributes to silencing remain limited. It is also unknown whether each of these proteins contributes to silencing through one common process or through multiple processes required for silencing during DNA replication. The Rine laboratory has developed a new yeast assay (CRASH for Cre-Reported Altered States of Heterochromatin) to detect transient losses of epigenetic silencing. Using this assay, in a recent sabbatical year, Prof. Kupiec has found that the Elg1 RFC-like complex, in charge of unloading the clamp PCNA during DNA replication, plays a role in maintaining the heterochromatic state at the silenced mating-type loci of yeast. Moreover, preliminary results show that this is achieved in conjunction with the well-characterized Sir1 protein. The Rine lab is a recognized expert in the biology of epigenetic events in yeast. The Kupiec lab studies the effect of timely PCNA loading and unloading in genome stability. Here we join forces to study the effect of DNA replication factors on epigenetic phenomena. We will use a combination of microscopic, genetic and biochemical approaches to characterize the novel pathway(s) involved in epigenetic silencing.