Integrated Calendar

Tumors are spatially organized ecosystems that are comprised of distinct cell types, each of which can assume a variety of phenotypes defined by coexpression of multiple proteins. To underscore this complexity, and move beyond single cells to multicellular interactions, it is essential to interrogate cellular expression patterns within their native context in the tissue. We have pioneered MIBI-TOF (Multiplexed Ion Beam Imaging by Time of Flight), a platform that enables simultaneous imaging of forty proteins within intact tissue sections at subcellular resolution. In this talk, I will describe our application of multiplexed imaging to study the tumor immune microenvironment in triple negative breast cancer. Our work reveals archetypical organizations, linking molecular expression patterns, cell composition and histology, which are predictive of patient survival.

Supercooled clouds substantially impact polar surface energy budgets but large-scale models often underestimate their occurrence, which motivates accurately establishing metrics of basic processes. A polar stratiform cloud’s lifecycle is determined by a set of complex interactions and feedbacks between different micro-physical and macro-physical processes, some of which are not fully understood or quantified, leading to uncertainty in climate predictions. These polar clouds are commonly presupposed as being turbulent as a result of intense cloud-top longwave radiative cooling, while experiencing desiccation dominated by precipitating ice. In this talk, I examine some of these underlying assumptions and provide applicable guidance for large-scale model evaluation.
I first present observations of persistent formation of drizzle drops at cloud temperatures below -25 °C detected over McMurdo Station, Antarctica. These supercooled drizzle observations supported by large-eddy simulations (LES) used to examine the cloud’s formation and evolution under initially stable, nonturbulent conditions, suggest that drizzle can be common over polar regions and serve as the main cloud moisture sink even well below the freezing temperature. A persistent nonturbulent cloud state suggested by the LES leads to the examination of nonturbulent cloud occurrence in observational datasets from Arctic and Antarctic ground-based sites. Such stable, nonturbulent conditions, surmised to preferentially occur early in cloud lifecycles, are estimated to prevail in a quarter of cloud occurrences over these polar sites. I use LES sensitivity tests to examine how short to intermediate period gravity waves, which are supported by such stable conditions, may catalyze turbulence formation when aerosol particles available for activation are sufficiently small. The observational datasets are also utilized to examine ice precipitation processes, and show that the vast majority of polar supercooled clouds are at least weakly precipitating ice at the cloud base even when they are not seeded from above, consistent with commonly observed supercooled cloud longevity. These results indicate that supercooled cloud layers are a sustained source of ice precipitation, and suggest that ground-based statistics offer valuable guidance for large-scale models. Finally, as an example of how some of these observational and modeling results may be used to evaluate the representations of polar clouds in large-scale models, I briefly describe using the GISS E3 climate model in single-column model (SCM) mode applied to the supercooled drizzle case study.

In quantum science, we often encounter the tension between elongating the coherence time of a system and retaining the ability to control and interact with it. An extreme example is the nuclear spin of noble gases, which is isolated from the environment by the complete electronic shells. In our lab, the spins of a helium-3 gas maintain coherence for up to two hours. Unfortunately, these spins are not accessible to light in the optical domain, and their (potential) quantum qualities have been beyond reach and largely overlooked. We establish that thermal spin-exchange collisions between noble-gas atoms and alkali-metal atoms form a quantum interface between them. These weak collisions, despite their stochastic nature, accumulate to a deterministic, efficient, and controllable coupling between the collective spins of the two gases. In experiments, we realize the strong coupling between potassium and helium-3 spins and, by coupling light to the potassium spins, demonstrate an efficient, two-way, optical interface to the helium-3 spins. The interface paves the way to employing noble-gas spins in the quantum domain, and we discuss prospects for quantum memories and entanglement of distant noble-gas ensembles with hour-long lifetimes.

We model intrinsically disordered proteins (IDPs) as associative polymers (APs). We study the kinetics of gelation in solutions of amphiphilic polymers that contain strongly associating stickers connected by long soluble chain segments. We explore the relation between primary sequence and droplet morphology in APs in poor solvent. We find that gelation of APs can be suppressed by grafting them to surfaces, a possible way to control aggregation of IDPs.

Zoom Link: https://weizmann.zoom.us/j/99868477151?pwd=U3hFTWhjZ05nT3Ryd1ZHOXJ6Z3Y1Zz09