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Critical Art Encounters offer sustained and at times meditative engagements with contemporary artworks. This Critical Art Encounter is a kind of reprise, a return to a joint performance by visual artist Suné Woods, poet and theorist Fred Moten, and musician and theorist James Gordon Williams. Titled You are mine. I see now, I'm a have to let you go, the piece was performed live at the Hammer Museum during their 2018 biennial event “Made in L.A.” This special section of liquid blackness aims to sample the fully realized collaboration and audiovisual experimentation that took place in the largely improvised art event. This Critical Art Encounter includes the intimate ecological exploration that takes place in Woods's video work; Moten's poem “the general balm,” which was written in part for the performance and later published in his book of poetry and criticism all that beauty (2019); and finally, a conversation with Erin Christovale, an associate curator at the Hammer who helped organize the event. Although not all three artists are featured (Williams's original compositions can be heard in the footage from the performance), we were fortunate to expand this creative dialogue by including a curatorial perspective. Thus we are able to consider how this work expresses liquidity as both a concern of contemporary black art and a call to the congregation.

Tides and Earth-Moon system evolution are coupled over geological time. Tidal energy dissipation on Earth slows Earth's rotation rate, increases obliquity, lunar orbit semi-major axis and eccentricity, and decreases lunar inclination. Tidal and core-mantle boundary dissipation within the Moon decrease inclination, eccentricity and semi-major axis. Here we integrate the Earth-Moon system backwards for 4.5Ga with orbital dynamics and explicit ocean tide models that are "high-level" (i.e., not idealized). To account for uncertain plate tectonic histories, we employ Monte Carlo simulations, with tidal energy dissipation rates (normalized relative to astronomical forcing parameters) randomly selected from ocean tide simulations with modern ocean basin geometry and with 55, 116, and 252Ma reconstructed basin paleogeometries. The normalized dissipation rates depend upon basin geometry and Earth's rotation rate. Faster Earth rotation generally yields lower normalized dissipation rates. The Monte Carlo results provide a spread of possible early values for the Earth-Moon system parameters. Of consequence for ocean circulation and climate, absolute (un-normalized) ocean tidal energy dissipation rates on the early Earth may have exceeded today's rate due to a closer Moon. Prior to ∼3Ga , evolution of inclination and eccentricity is dominated by tidal and core-mantle boundary dissipation within the Moon, which yield high lunar orbit inclinations in the early Earth-Moon system. A drawback for our results is that the semi-major axis does not collapse to near-zero values at 4.5Ga, as indicated by most lunar formation models. Additional processes, missing from our current efforts, are discussed as topics for future investigation.

Christian Scott aTunde Adjuah is an African American trumpeter, composer and producerfrom New Orleans, Louisiana. He has written compositions and performed improvisationscommitted to social justice themes. His cultural work is a natural extensionof his community service training directed by his grandfather Donald Harrison Sr. Hiscomposition 'Danziger' (2012) gives voice to the unarmed citizens injured and killed bypolice as they crossed the Danziger Bridge in the wake of Hurricane Katrina. 'Danziger'extends from his stretch music theory which aTunde Adjuah describes as disassemblingand reassembling musical ideas so that his compositions and improvisations canbe understood holistically. While aTunde Adjuah's interpretation of the Danziger Bridgeshootings is funneled through the ontological cornucopia of his trumpet and referenceshis particular community, the message he sends out through his custom-made trumpetbell is universal because his critique supports everyday human rights.

Differing environmental conditions can have profound effects on many behaviours in animals, especially where species have large geographic ranges. Seasonal changes or progression through life history stages impose differential constraints, leading to changes in behaviours. Furthermore, species which show flexibility in behaviours, may have a higher capacity to adapt to anthropogenic-induced changes to their environment. The red-throated diver (RTD) is an aquatic bird, that is able to forage in both freshwater and marine environments, though little else is known about its behaviours and its capacity to adapt to different environmental conditions. Here, we use time-depth recorders and saltwater immersion loggers to examine the foraging behaviour of RTDs from three regions across northwest Europe. We found that in the breeding season, birds from two regions (Iceland and Scotland) foraged in the marine environment, while birds from Finland, foraged predominantly in freshwater. Most of the differences in diving characteristics were at least partly explained by differences in foraging habitat. Additionally, while time spent foraging did not change through the breeding season, dives generally became more pelagic and less benthic over the season, suggesting RTDs either switched prey or followed vertical prey movements, rather than increasing foraging effort. There was a preference for foraging in daylight over crepuscular hours, with a stronger effect at two of the three sites. Overall, we provide the first investigation of RTD foraging and diving behaviour from multiple geographic regions and demonstrate variation in foraging strategies in this generalist aquatic predator, most likely due to differences in their local environment.

We utilize dissipatively coupled, time-multiplexed photonic resonator net-works to demonstrate topologically nontrivial behaviors in the dissipation of one- and two-dimensional lattices. We present edge state and band structure measurements of the these networks.

Quantum key distribution allows for a provably secure transmission of cryptographic keys over an optical channel. Encoded polarization states or time-bin degree of freedom have been used for successful demonstrations. However, photon losses in long fibers, slow single photon detectors, and detector dark counts significantly limit the overall bit rate. Improving key throughput and reducing the overhead of key reconciliation remain as major challenges. Methods which utilize multiple time bins allow for multiple key bits to be encoded in a single photon, thus increasing the fidelity of transmitted keys and decreasing the overhead of key reconciliation in real-world conditions. Previous implementations of these methods required that Alice and Bob share a time reference by sharing a dedicated classical channel used for synchronization. This work presents a technique that allows two parties to exchange time-bin encoded photons without the need for synchronized time references. Our technique uses a framing protocol which allows Alice to encode a time reference along with a key which is determined by Alice before transmission. Security can be achieved by monitoring the visibility of a pair of Franson interferometers, using decoy pulses and measuring the round trip time between Alice and Bob. The bit rate of this technique is limited only by the recovery time of the detector and the speed of the modulation electronics. We experimentally demonstrate a raw bit rate of 5Mb/s over an optical channel with 55dB of loss, which is competitive with current research. We also demonstrate absolute timing synchronization with an accuracy of 20ps.

Five retroreflector arrays currently on the Moon reflect short laser pulses back to Earth, allowing range to be measured. Each array has multiple small corner cubes. Due to variable lunar optical librations of the direction to Earth, the tilted arrays spread return times of single photons in the returned laser pulse, degrading the synthesized multiphoton normal point range accuracy. The Next Generation Lunar Retroreflectors (NGLRs) and MoonLIGHT reflectors currently being fabricated are larger 10 cm single corner cubes that do not spread the pulse. The Lunar Geophysical Network (LGN) mission will place NGLRs at three separated sites on the lunar nearside. The Commercial Lander Payload Service (CLPS) and early Artemis missions will precede the LGN mission. Solutions that include 6 yr of simulated Lunar Laser Ranging (LLR) data to two sites in the north and two in the south show improvement in the uncertainties of many science parameters. Lunar solution parameters include displacement Love numbers h 2 and l 2, tidal dissipation at several frequencies, fluid-core/solid-mantle boundary (CMB) dissipation, and moment of inertia combinations (C–A)/B and (B–A)/C, with principal moments of inertia A < B < C. Submeter-accuracy coordinates of the new reflectors will result from the first month of well-distributed data. There are benefits other than lunar science: gravitational physics includes the equivalence principle; Earth science includes terrestrial tidal dissipation and ranging station positions and motions; and astronomical constants with GM(Earth+Moon) for the gravitational constant times the mass of the Earth–Moon system. Improvements are illustrated for h 2, l 2, (C–A)/B, (B–A)/C, equivalence principle, and GM(Earth+Moon).

The Lunar Laser Ranging (LLR) experiment has accumulated 50 years of range data of improving accuracy from ground stations to the laser retroreflector arrays (LRAs) on the lunar surface. The upcoming decade offers several opportunities to break new ground in data precision through the deployment of the next generation of single corner-cube lunar retroreflectors and active laser transponders. This is likely to expand the LLR station network. Lunar dynamical models and analysis tools have the potential to improve and fully exploit the long temporal baseline and precision allowed by millimetric LLR data. Some of the model limitations are outlined for future efforts. Differential observation techniques will help mitigate some of the primary limiting factors and reach unprecedented accuracy. Such observations and techniques may enable the detection of several subtle signatures required to understand the dynamics of the Earth-Moon system and the deep lunar interior. LLR model improvements would impact multi-disciplinary fields that include lunar and planetary science, Earth science, fundamental physics, celestial mechanics and ephemerides., 8 pages, 1 figure, A white paper submitted to the Committee on the Planetary Science Decadal Survey (2023-2032) of The National Academies of Sciences

In this study, we investigate the machining behaviour of a Piperidine and a MDA cured DGEBA epoxy resin under low speed orthogonal micro-cutting conditions. The characteristics of chip-workpiece separation, chip formation and machined surface damage were examined in association with thermomechanical and mechanical properties of the epoxies. It is found that the separation of the chip from the workpiece takes place by fracture, according to Williams' model of machining. Further, cube-square scaling principles can be used to explain the mechanism of the observed brittle-to- ductile cutting behaviour of the epoxies. The results also show that the chip formation process is determined by both shear yielding and plastic bending behaviour of the material. In particular, chip formation involves the imposition of large strain plastic deformation. This explains the dependence of the cutting states (such as continuous chip and broken chip) on the degree of crosslink density of the epoxy, since the latter controls the post-yield deformability of epoxy chips. Based on our new findings, a modified Williams' cutting model is proposed to account for the chip formation behaviour of polymers in cutting.