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Scanning tunneling microscopy (STM) offers unparalleled sub-molecular resolution for visualizing surface-bound molecular assemblies. We developed a custom 3D-printed liquid cell that enabled stable, long-duration liquid-phase STM imaging of a metallocene dimer assembled on a highly oriented pyrolytic graphite (HOPG) substrate. High-resolution images revealed two distinct molecular packing structures. However, STM alone is difficult to pinpoint the detailed molecular arrangements, resonance Raman spectroscopy (RRS) was used to provide complementary information. Aided with density functional theory (DFT) calculated RRS, a cis conformer of the metallocene dimer was identified as the more probable form in both crystal and surface-bound states. These findings led to assemblies with cyclopentadienyl rings pointing towards the HOPG, and the carbonyl groups towards the water. This work demonstrates the synergistic power of integrating STM, RRS, and DFT in elucidating molecular assembling structures at the solid–liquid interface. 

We explore the relative roles of Earth’s axial tilt (‘tilt effect’) and orbital eccentricity (‘distance effect’) on the seasonal cycle of tropical sea surface temperature (SST), decomposing the two contributions using simulations of an Earth System model varying eccentricity and longitude of perihelion.  This dataset archives model output produced in this investigation using the Community Earth System Model version 2, and MATLAB code for analyzing the data. 

We explore the relative roles of Earth’s axial tilt (‘tilt effect’) and orbital eccentricity (‘distance effect’) in generating the seasonal cycle of tropical sea surface temperature (SST), decomposing the two contributions using simulations of an Earth System model varying eccentricity and longitude of perihelion. Tropical SST seasonality is largely explained by the annual contribution from tilt, but with significant contributions from the semiannual contribution from tilt and annual contribution from distance, especially in regions where the tilt annual contribution is relatively small. Precessional changes to tropical SST seasonality are readily explained by the distance annual component whose amplitude increases linearly with eccentricity and whose phase changes linearly with the longitude of perihelion, while the tilt contributions remain essentially unchanged. As such, the annual cycle contribution from distance can become significant at high eccentricity (e > 0.05) and dominate the SST annual cycle in some regions of the Tropics. The annual cycle tropical SST response to the distance effect consists of a tropics-wide warming peaking ∼2 months after perihelion consistent with a direct thermodynamic effect, and a dynamic contribution characterized by a cooling of the Pacific cold tongue peaking 5-6 months after perihelion. For current orbital conditions, the thermodynamic contribution acts to dampen the tropical SST seasonal cycle of the northern hemisphere from the tilt influence and amplify it in the southern hemisphere. The dynamic contribution acts to shift the Pacific cold tongue seasonal cycle arising from tilt to earlier in the season, by ∼1 month. 

Abstract TESS and Kepler have revealed that practically all close-in sub-Neptunes form in mean-motion resonant chains, most of which unravel on timescales of 100 Myr. UsingN-body integrations, we study how planetary collisions from destabilized resonant chains produce the orbital period distribution observed among mature systems, focusing on the resonant fine structures remaining post-instability. In their natal chains, planets near first-order resonances have period ratios just wide of perfect commensurability, driven there by disk migration and eccentricity damping. Sufficiently large resonant libration amplitudes are needed to trigger instability. Ensuing collisions between planets (“major mergers”) erode but do not eliminate resonant pairs; surviving pairs show up as narrow “peaks” just wide of commensurability in the histogram of neighboring-planet period ratios. Merger products exhibit a broad range of period ratios, filling the space between relatively closely separated resonances such as the 5:4, 4:3, and 3:2, but failing to bridge the wider gap between the 3:2 and 2:1—a “trough” thus manifests just short of the 2:1 resonance, as observed. Major mergers generate debris that undergoes “minor mergers” with planets, in many cases further widening resonant pairs. With all this dynamical activity, free eccentricities of resonant pairs, and by extension the phases of their transit timing variations, are readily excited. Nonresonant planets, being merger products, are predicted to have higher masses than resonant planets, as observed. At the same time, a small fraction of mergers produce a high-mass tail in the resonant population, also observed. 

Language documentation involving diaspora communities presents a combination of challenges and opportunities for approaches leveraging large data collection and assisted transcription and annotation. Demonstrating our projects on Kichwa and Mapudungun, we will present a suite of our computational tools designed to effectively work with diaspora communities for language documentation.