Published on 25 Apr 2024
Supermassive black hole masses may be overestimated for distant quasars
This paper draws an analogy between ultraluminous X-ray sources (ULXs) and distant quasars to suggest that the high black hole mass estimates for quasars may be too large. Like ULXs, quasars could be 'beamed' with anisotropic emission if fed at super-Eddington rates, causing observers to overestimate their luminosities and masses. Their emission line properties would still match unbeamed quasars. So quasars may have lower masses that grew from stellar remnants, rather than requiring massive early seeds.
Published on 25 Apr 2024
Monocular depth estimation challenge tests generalization
The paper summarizes the third Monocular Depth Estimation Challenge, which tested algorithms on their ability to generalize to complex natural and indoor scenes. 19 submissions outperformed the baseline method. 10 teams submitted reports, showing widespread use of Depth Anything model. The top method increased the 3D F-Score from 17.51% to 23.72%.
Published on 25 Apr 2024
Topological gravity from Chern-Simons gauge theory
This paper applies a mathematical technique called 'double copy' to construct a novel topological gravity theory in 3 dimensions, starting from Chern-Simons gauge theory. The resulting gravity theory features a metric fluctuation and two 2-form fields, is gauge-invariant and local, but non-Lagrangian. An action can be constructed by giving up locality. The theory is also related to 6-dimensional Kodaira-Spencer gravity. Overall, this gives an explicit gravitational theory from the double copy of a gauge theory.
Published on 25 Apr 2024
Realistic Material Assignment for 3D Objects
This paper presents Make-it-Real, a novel approach that leverages large language models to identify materials from images and assign them to 3D objects. This allows creating realistic material properties for existing 3D assets and generated models.
Published on 25 Apr 2024
Correcting lens errors using quantum gases
Researchers developed a technique to measure and correct for lens aberrations in an ultracold quantum gas experiment by using the gas itself to probe the optical phase. They split a laser beam into two paths using a spatial light modulator, passed the beams through optics to the quantum gas, and observed interference between them. By changing the relative phase and monitoring the gas density, they extracted the aberrated wavefront and corrected it with the modulator. This enabled high-precision tailoring of optical potentials below the imagi...
Published on 25 Apr 2024
Trajectory optimization via continuous-time constraint satisfaction
This paper proposes a trajectory optimization method that guarantees continuous-time feasibility of state and control trajectories with respect to path constraints. It achieves this by reformulating path constraints into an auxiliary dynamical system with periodic boundary conditions. The method converges to an approximate Karush-Kuhn-Tucker point via sequential convex programming using a technique called prox-linear optimization. It is applicable to a wide range of nonlinear optimal control problems with nonconvex dynamics and constraints. ...
Published on 25 Apr 2024
Jointly Rescaling and Rendering Panoramas for VR Viewing
This paper proposes a new framework called ResVR that jointly handles image rescaling and viewport rendering of 360-degree panoramic images to optimize visual quality when viewed through VR headsets. It develops techniques to enable end-to-end training of the full pipeline from server to headset display. A novel sampling method handles irregular correspondence between equirectangular and viewport image areas. A spherical pixel shape representation further enhances rendered view quality.
Published on 25 Apr 2024
Deep visual and audio watermarking for AI video editing forensics
This paper proposes V2A-Mark, a method to embed invisible visual and audio watermarks into videos to enable precise tamper localization and copyright protection. It addresses limitations of current forensic methods like poor generalizability and singular functionality. V2A-Mark combines fragile video steganography with robust watermarking, using temporal alignment and cross-modal extraction between video and audio. Experiments show it achieves superior localization precision and copyright accuracy compared to other methods, without needing r...
Published on 25 Apr 2024
Learning dexterity from human demonstrations
The authors develop HATO, a low-cost bimanual teleoperation system using off-the-shelf virtual reality hardware and prosthetic hands equipped with touch sensors. They collect visuotactile demonstration data of complex manipulation tasks and use it to train policies that successfully replicate human dexterity, motion patterns and perceptual experiences. Key results show vision and touch are critical for policy success, and performance saturates at 100-300 demos.
Published on 25 Apr 2024
Dark radiation from neutrino mixing: Impact on cosmic microwave background and connection to Hubble tension
This paper studies models where dark radiation abundance changes over time due to mixing with neutrinos. The full equations are derived and implemented to study impact on cosmic microwave background and connection to Hubble tension. For strong coupling, tight mass prior gives minor impact, but larger mass range allows interpolation between standard model and extra dark radiation. For weak coupling, parameter spaces relevant for neutrino anomalies and Hubble tension are found.
Published on 25 Apr 2024
Bridging open-source and commercial multimodal models
This paper introduces InternVL 1.5, an open-source multimodal model that aims to match proprietary counterparts in capabilities. It does so through 3 key improvements: a reusable vision encoder, dynamic high resolution, and a bilingual dataset. When evaluated on 18 benchmarks, it achieved state-of-the-art results on 8, showing it has narrowed the gap.
Published on 25 Apr 2024
Ordered and disordered point patterns across dimensions
This paper explores the properties of stealthy hyperuniform point patterns, which have unusual spatial structure, across dimensions. It shows mathematically that the most dense stealthy patterns are always periodic lattices. It also simulates disordered stealthy patterns, finding they lose structure with more dimensions. This helps explain why stealthy patterns have useful properties in our 3D world.
Published on 25 Apr 2024
Principal Mask Proposals for Unsupervised Semantic Segmentation
This paper presents a method called PriMaPs to decompose images into semantically meaningful masks using principal components of self-supervised image features. These masks serve as proposals to guide an expectation-maximization algorithm, PriMaPs-EM, to realize unsupervised semantic segmentation by fitting class prototypes. Despite simplicity, PriMaPs-EM leads to competitive accuracy across datasets and backbone models. Notably, it boosts results when combined with state-of-the-art methods, suggesting it uses representation properties ortho...
Published on 25 Apr 2024
Modified scattering and absence of energy cascades for cubic NLS on Diophantine waveguides
This paper studies the cubic nonlinear Schrödinger equation on product spaces satisfying a Diophantine condition. It shows that small-amplitude solutions exhibit modified scattering to an effective dynamics that does not amplify Sobolev norms. This contrasts with the infinite energy cascade observed without Diophantine conditions, indicating sensitivity to boundary perturbations.
Published on 25 Apr 2024
Benchmark for evaluating language models on generation tasks in Indian languages
The authors release IndicGenBench, a new benchmark to measure the ability of language models to perform generation tasks like summarization, translation, and question answering across 29 languages native to India. It extends existing datasets, providing multi-way parallel test data in many under-resourced Indic languages for the first time.
Published on 25 Apr 2024
Quantum effects extend primordial black hole lifetimes as dark matter candidates
This paper explores how quantum effects like the 'memory burden' could significantly extend the lifetimes of primordial black holes (PBHs), possibly allowing lighter PBHs to comprise all dark matter. The authors calculate dark matter abundance from both extended-lifetime PBHs and their Hawking radiation decay products.
Published on 25 Apr 2024
Exploring transfer learning to classify rare skin diseases
This paper examines combining few-shot learning and transfer learning to address challenges in classifying rare skin diseases with limited data. Models using DenseNet121, MobileNetV2, ImageNet pretraining, episodic training, and data augmentation are tested on datasets like SD-198. Key findings show transfer learning helps represent features and boosts performance, traditional training surpasses episodic past few shots, and data augmentation further improves accuracy, achieving state-of-the-art on some datasets.
Published on 25 Apr 2024
Atmospheres of highly irradiated brown dwarfs WD-0137B and EPIC-2122B
The atmospheres of two brown dwarfs orbiting close to white dwarfs were studied using Hubble Space Telescope spectroscopy across six orbital phases. WD-0137B's atmosphere transitions from hot and inverted on its star-facing side, to cooler with water absorption on its night side, similar to ultra hot Jupiters. Meanwhile EPIC-2122B remains inverted on both sides but hotter overall, showing hydrogen minus opacity throughout. Retrieval modeling suggests differences arise from the inclined viewing angle always revealing some of the hotter daysid...
Published on 25 Apr 2024
Electrostatically Enhanced Nanocrystal Superlattice Assembly
This paper investigates how electrostatic interactions between semiconductor nanocrystals can be tuned to control their assembly into ordered superlattice arrays. Using in situ X-ray scattering, the authors systematically study the phase behavior and kinetics as they vary nanocrystal concentration and solution ionic strength. They identify one- and two-step assembly pathways, with the latter proceeding through a metastable liquid intermediate. This liquid phase increases assembly rates and enhances superlattice order compared to direct assem...
Published on 25 Apr 2024
Non-supersymmetric duality cascade of bifundamental QCD via semiclassics
We apply a novel semiclassical approach with baryon-'t Hooft flux on R^2 x T^2 to study the bifundamental QCD (QCD(BF)) of different ranks. We derive the 2d effective theory from dilute gas approximation of center vortices. This determines the phase diagram under adiabatic continuity. We justify the non-supersymmetric duality cascade between different QCD(BF)s, conjectured from large-N. We construct the explicit duality map including the coupling correspondence.
Published on 25 Apr 2024
Flow around a cylinder benchmark
The paper proposes a benchmark test problem for computational fluid dynamics codes based on simulating flow around a cylinder. It focuses on 2D flow at Reynolds numbers where complex, chaotic vortex shedding occurs. Accurately capturing this long-term unsteady behavior is challenging and requires quality numerical methods on a curved domain.
Published on 25 Apr 2024
Atmospheric escape from young exoplanets
This paper presents a survey of 20 young exoplanets looking for atmospheric escape signals in the helium triplet and hydrogen alpha spectral lines. Two new helium detections were found for TOI-1268b and TOI-2018b. When combined with 50 other planets from the literature, the results show that young planets do not exhibit more frequent escape signatures compared to older planets. Instead, escape seems more common for 1-3 billion year old systems. The paper explores what factors best explain the observed helium absorption, like the ratio of the...
Published on 25 Apr 2024
Obstructions to commutativity in positive characteristic
This paper explores the relationship between commutative algebras and E-infinity algebras in positive characteristic. It defines new cohomology operations called cotriple products that generalize Massey products and serve as obstructions to commutativity. The paper computes secondary operations for strictly commutative algebras, constructs counterexamples, defines higher cotriple products, and proves that E-infinity algebras can be rectified if and only if higher Steenrod operations vanish coherently.
Published on 25 Apr 2024
Colorizing Images with Diffusion and Guidance
This paper proposes an automatic image colorization method that uses diffusion models to generate color, with guidance from the grayscale image's luminance and high-level semantics like text captions, to produce more realistic and vibrant colorization.
Published on 25 Apr 2024
Clustering based on similarity across networks
This paper introduces a new clustering model that uses similarity information across multiple networks to find clusters that are consistent across all the networks. The model aims to minimize disagreements between the clustering and the similarity information on each network. The paper gives approximation algorithms for the problem, including an O(L log n) approximation where L is the number of networks and n the number of nodes. For an important special case with probability constraints, the paper presents a (2.5 + 2) approximation, leverag...
Published on 25 Apr 2024
Operator realizations and analytic properties of noncommutative functions
This paper studies operator realizations of noncommutative (NC) functions, which are a generalization of power series to several noncommuting variables. It shows that an NC function is entire (defined on the whole NC universe) if and only if it has a compact and quasinilpotent realization. For one variable, this implies a function analytic near 0 extends meromorphically if and only if it has a compact realization. This motivates defining global uniformly meromorphic NC functions as those having compact realizations, forming a skew field prop...
Published on 25 Apr 2024
Quantum effects on a spherical black hole with global monopoles
This paper introduces a model for a spherically symmetric quantum corrected black hole within an anti-de Sitter background, including both regular and phantom global monopoles. It investigates how the monopoles and quantum effects influence key properties: thermal behavior, particle trajectories, shadow radius, and emission rate.
Published on 25 Apr 2024
Periodicity of repeating fast radio bursts indicates a neutron star with a nearby planet
The authors analyze over 1000 bursts from repeating fast radio burst FRB 20121102A, detecting a 157-day quasi-period consistent with a binary degenerate star system. Notably, they also find a 4.6-day candidate period only visible in high-energy bursts, indicative of a planet closely orbiting the primary neutron star.