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Bio-Inspired Ocean Exploration
No full textSubstantial efforts have been made to expand our knowledge of the physics, biology, chemistry, and geography of the ocean using state-of-the-art measurement tools. With new global projects and technological advances, the collaborative efforts of the Ocean Decade (2021–2030) are well on the way to revolutionizing our knowledge of ocean sciences and sustainability. Yet even today, over three-quarters of the seafloor is still unmapped, more than 90% of marine life still awaits discovery and classification, and the number of ocean sensors required to study global phenomena at sufficient temporal and spatial resolutions is seemingly intractable. To address this challenge, new approaches such as bio-inspired robotics can expand our existing toolbox and bridge this knowledge gap. The concept of biology-inspired engineering has emerged as a powerful tool to complement traditional engineering approaches to technology development. For example, specific swimming features of jellyfish and fish have been applied to a variety of fields, from vehicular propulsion to wind energy to medical diagnostics. In particular, jellyfish are advantageous model organisms because of their energy efficiency, with the lowest known cost of transport compared to other animals, as well as their ubiquity and survivability in various ocean environments. In this article we highlight the evolution of research into jellyfish-inspired robotic constructs and their potential applications in ocean exploration. After initial projects using entirely engineered materials (i.e., jellyfish-inspired submarine propellers) and tissue engineering methods (i.e., rat cardiac cells seeded on flexible films), recent work to integrate microelectronic systems onto live jellyfish demonstrates that their swimming speeds can be increased (up to three times compared to their baselines) and their energy efficiency can be improved (up to four times compared to their baselines). This shows promise for the robotic control of jellyfish in real-world oceanic environments, where the animals are already distributed globally. Future work can improve the maneuverability of these bio-hybrid jellyfish robots, incorporate miniaturized sensors to profile regions of interest, and ultimately deploy swarms of these low-power, low-cost robots to obtain high-resolution data and improve ocean climate models. The synergy of bio-inspired technologies with existing ocean measurement tools holds promise to push the frontiers of ocean exploration and stewardship
HIV-1 CD4-binding site germline antibody-Env structures inform vaccine design
No full textBG24, a VRC01-class broadly neutralizing antibody (bNAb) against HIV-1 Env with relatively few somatic hypermutations (SHMs), represents a promising target for vaccine strategies to elicit CD4-binding site (CD4bs) bNAbs. To understand how SHMs correlate with BG24 neutralization of HIV-1, we report 4.1 Å and 3.4 Å single-particle cryo-EM structures of two inferred germline (iGL) BG24 precursors complexed with engineered Env-based immunogens lacking CD4bs N-glycans. Structures reveal critical Env contacts by BG24_(iGL) and identify antibody light chain structural features that impede Env recognition. In addition, biochemical data and cryo-EM structures of BG24_(iGL) variants bound to Envs with CD4bs glycans present provide insights into N-glycan accommodation, including structural modes of light chain adaptations in the presence of the N276_(gp120) glycan. Together, these findings reveal Env regions critical for germline antibody recognition and potential sites to alter in immunogen design
Comparative Oncology Assessment of a Novel Inhibitor of Valosin-Containing Protein in Tumor-Bearing Dogs
No full textPet dogs with naturally occurring cancers play an important role in studies of cancer biology and drug development. We assessed tolerability, efficacy, and pharmacokinetic/pharmacodynamic relationships with a first-in-class small molecule inhibitor of valosin-containing protein (VCP/p97), CB-5339, administered to 24 tumor-bearing pet dogs. Tumor types assessed included solid malignancies, lymphomas, and multiple myeloma. Through a stepwise dose and schedule escalation schema, we determined the maximum tolerated dose to be 7.5 mg/kg when administered orally on a 4 days on, 3 days off schedule per week for 3 consecutive weeks. Adverse events were minimal and mainly related to the gastrointestinal system. Pharmacokinetic/pharmacodynamic data suggest a relationship between exposure and modulation of targets related to induction of the unfolded protein response, but not to tolerability of the agent. An efficacy signal was detected in 33% (2/6) of dogs with multiple myeloma, consistent with a mechanism of action relating to induction of proteotoxic stress in a tumor type with abundant protein production. Clinical trials of CB-5339 in humans with acute myelogenous leukemia and multiple myeloma are ongoing
TOI-1468: A system of two transiting planets, a super-Earth and a mini-Neptune, on opposite sides of the radius valley
No full textWe report the discovery and characterization of two small transiting planets orbiting the bright M3.0V star TOI-1468 (LSPM J0106+1913), whose transit signals were detected in the photometric time series in three sectors of the TESS mission. We confirm the planetary nature of both of them using precise radial velocity measurements from the CARMENES and MAROON-X spectrographs, and supplement them with ground-based transit photometry. A joint analysis of all these data reveals that the shorter-period planet, TOI-1468 b (P_b = 1.88 d), has a planetary mass of M_b = 3.21 ± 0.24M_⊕ and a radius of R_b = 1.280_(−0.039)^(+0.038) R_⊕, resulting in a density of ρ_b = 8.39_(−0.92)^(+1.05) g cm^(−3), which is consistent with a mostly rocky composition. For the outer planet, TOI-1468 c (P_c = 15.53 d), we derive a mass of M_c = 6.64_(−0.68)^(+0.67) M_⊕,aradius of R_c = 2.06 ± 0.04 R_⊕, and a bulk density of ρ_c = 2.00_(−0.19)^(+0.21) g cm^(−3), which corresponds to a rocky core composition with a H/He gas envelope. These planets are located on opposite sides of the radius valley, making our system an interesting discovery as there are only a handful of other systems with the same properties. This discovery can further help determine a more precise location of the radius valley for small planets around M dwarfs and, therefore, shed more light on planet formation and evolution scenarios
Expedient Synthesis of a Library of Heparan Sulfate‐Like "Head-to-Tail" Linked Multimers for Structure and Activity Relationship Studies
No full textHeparan sulfate (HS) plays important roles in many biological processes. The inherent complexity of naturally existing HS has severely hindered the thorough understanding of their structure-activity relationship. To facilitate biological studies, a new strategy has been developed to synthesize a HS-like pseudo-hexasaccharide library, where HS disaccharides were linked in a “head-to-tail” fashion from the reducing end of a disaccharide module to the non-reducing end of a neighboring module. Combinatorial syntheses of 27 HS-like pseudo-hexasaccharides were achieved. This new class of compounds bound with fibroblast growth factor 2 (FGF-2) with similar structure-activity trends as HS oligosaccharides bearing native glycosyl linkages. The ease of synthesis and the ability to mirror natural HS activity trends suggest that the new head-to-tail linked pseudo-oligosaccharides could be an exciting tool to facilitate the understanding of HS biology
AdS/BCFT from Conformal Bootstrap: Construction of Gravity with Branes and Particles
No full textWe initiate a conformal bootstrap program to study AdS3/BCFT2 with heavy
excitations. We start by solving the bootstrap equations associated with
two-point functions of scalar/non-scalar primaries under the assumption that
one-point functions vanish. These correspond to gravity with a brane and a
non-spinning/spinning particle where the brane and the particle do not
intersect with each other. From the bootstrap equations, we obtain the energy
spectrum and the modified black hole threshold. We then carefully analyze the
gravity duals and find the results perfectly match the BCFT analysis. In
particular, brane self-intersections, which are usually considered to be
problematic, are nicely avoided by the black hole formation. Despite the
assumption to solve the bootstrap equations, one-point functions of scalar
primaries can be non-zero in general. We construct the holographic dual for a
non-vanishing one-point function, in which the heavy particle can end on the
brane, by holographically computing the Renyi entropy in AdS/BCFT. As a bonus,
we find a refined formula for the holographic Renyi entropy, which appears to
be crucial to correctly reproduce the boundary entropy term. On the other hand,
we explain why one-point functions of non-scalar primaries always vanish from
the gravity dual. The independence of the bootstrap equations to the boundary
entropy helps us to construct gravity duals with negative tension branes. We
also find a holographic dual of boundary primaries
The transfer of entanglement negativity at the onset of interactions
No full textQuantum information, in the form of entanglement with an ancilla, can be transmitted to a third system through interaction. Here, we investigate this process of entanglement transmission perturbatively in time. Using the entanglement monotone negativity, we determine how the proclivity of an interaction to either generate, transfer or lose entanglement depends on the choice of Hamiltonians and initial states. These three proclivities are captured by Hamiltonian- and state-dependent quantities that we call negativity susceptibility, negativity transmissibility and negativity vulnerability respectively. These notions could serve, for example, as cost functions in quantum technologies such as machine-learned quantum error correction
Hohenberg-Mermin-Wagner-type theorems and dipole symmetry
No full textWe study the possibility of spontaneous symmetry breaking in systems with both charge and dipole symmetries. For d-dimensional systems at a positive temperature, we show that charge symmetry cannot be spontaneously broken for d ≤ 4, while dipole symmetry cannot be spontaneously broken for d ≤ 2. For T = 0, we show that charge symmetry cannot be spontaneously broken for d ≤ 2 if the compressibility is finite. We also show that continuum systems with a dipole symmetry have infinite inertial mass density
Tight Bounds on the Convergence of Noisy Random Circuits to the Uniform Distribution
No full textWe study the properties of output distributions of noisy random circuits. We obtain upper and lower bounds on the expected distance of the output distribution from the “useless” uniform distribution. These bounds are tight with respect to the dependence on circuit depth. Our proof techniques also allow us to make statements about the presence or absence of anticoncentration for both noisy and noiseless circuits. We uncover a number of interesting consequences for hardness proofs of sampling schemes that aim to show a quantum computational advantage over classical computation. Specifically, we discuss recent barrier results for depth-agnostic and/or noise-agnostic proof techniques. We show that in certain depth regimes, noise-agnostic proof techniques might still work in order to prove an often-conjectured claim in the literature on quantum computational advantage, contrary to what has been thought prior to this work
Photothermal effect in macroscopic optomechanical systems with an intracavity nonlinear optical crystal
No full textIntracavity squeezing is a promising technique that may improve the sensitivity of gravitational wave detectors and cool optomechanical oscillators to the ground state. However, the photothermal effect may modify the occurrence of optomechanical coupling due to the presence of a nonlinear optical crystal in an optical cavity. We propose a novel method to predict the influence of the photothermal effect by measuring the susceptibility of the optomechanical oscillator and identifying the net optical spring constant and photothermal absorption rate. Using this method, we succeeded in precisely estimating parameters related to even minor photothermal effects, which could not be measured using a previously developed method