Publications (20)
TWIG: Two-Step Image Generation using Segmentation Masks in Diffusion Models
Mazharul Islam Rakib, Showrin Rahman, Joyanta Jyoti Mondal +4
In today's age of social media and marketing, copyright issues can be a major roadblock to the free sharing of images. Generative AI models have made it possible to create high-qua…
Validation of the HERA Phase I Epoch of Reionization 21 cm Power Spectrum Software Pipeline
James E. Aguirre, Steven G. Murray, Robert Pascua +73
We describe the validation of the HERA Phase I software pipeline by a series of modular tests, building up to an end-to-end simulation. The philosophy of this approach is to valida…
Low-Frequency Radio Recombination Lines Away From the Inner Galactic Plane
Akshatha K. Vydula, Judd D. Bowman, David Lewis +8
Diffuse radio recombination lines (RRLs) in the Galaxy are possible foregrounds for redshifted 21~cm experiments. We use EDGES drift scans centered at ~declination to char…
Absolute Calibration of Diffuse Radio Surveys at 45 and 150 MHz
Raul A. Monsalve, Alan E. E. Rogers, Judd D. Bowman +7
We use EDGES measurements to determine scale and zero-level corrections to the diffuse radio surveys by Guzmán et al. at MHz and Landecker & Wielebinski at MHz. We find…
A Real Time Processing System for Big Data in Astronomy: Applications to HERA
Paul La Plante, Peter K. G. Williams, Matthew Kolopanis +72
As current- and next-generation astronomical instruments come online, they will generate an unprecedented deluge of data. Analyzing these data in real time presents unique conceptu…
Exoplanet weather and climate regimes with clouds and thermal ionospheres: A model grid study in support of large-scale observational campaigns
Christiane Helling, Dominic Samra, David Lewis +7
With observational efforts moving from the discovery into the characterisation mode, systematic campaigns that cover large ranges of global stellar and planetary parameters will be…
Validation of EDGES Low-Band Antenna Beam Model
Nivedita Mahesh, Judd D. Bowman, Thomas J. Mozdzen +4
The response of the antenna is a source of uncertainty in measurements with the Experiment to Detect the Global EoR Signature (EDGES). We aim to validate the beam model of the low-…
First Results from HERA Phase I: Upper Limits on the Epoch of Reionization 21 cm Power Spectrum
The HERA Collaboration, Zara Abdurashidova, James E. Aguirre +74
We report upper-limits on the Epoch of Reionization (EoR) 21 cm power spectrum at redshifts 7.9 and 10.4 with 18 nights of data ( hours of integration) from Phase I of the…
Rainbow saturation of graphs
António Girão, David Lewis, Kamil Popielarz
In this paper we study the following problem proposed by Barrus, Ferrara, Vandenbussche, and Wenger. Given a graph and an integer , what is $\operatorname{sat}_{t}\left(n, \…
The order dimension of divisibility
David Lewis, Victor Souza
The Dushnik-Miller dimension of a partially-ordered set is the smallest such that one can embed into a product of linear orders. We prove that the dimension of the…
On Covering Numbers, Young Diagrams, and the Local Dimension of Posets
Gábor Damásdi, Stefan Felsner, António Girão +4
We study covering numbers and local covering numbers with respect to difference graphs and complete bipartite graphs. In particular we show that in every cover of a Young diagram w…
A computational algorithm for the Hardy function , utilising sub-sequences of generalised cubic Gauss sums, with an overall operational complexity of , for
David Lewis, Ashley Brereton
In 2011 G. A. Hiary devised a computational algorithm for the Hardy function , requiring just operations. This compares to operations n…
Redundant-Baseline Calibration of the Hydrogen Epoch of Reionization Array
Joshua S. Dillon, Max Lee, Zaki S. Ali +76
In 21 cm cosmology, precision calibration is key to the separation of the neutral hydrogen signal from very bright but spectrally-smooth astrophysical foregrounds. The Hydrogen Epo…
Quantum State Absorptions Coupled To Resonance Raman Spectroscopy Could Result In A General Explanation of TERS
Zachary D. Schultz, John Parthenios, Rimma Dekhter +8
Tip enhanced Raman scattering (TERS) amplifies the intensity of vibrational Raman scattering by employing the tip of a probe interacting, in ultra close proximity, with a surface.…
HERA Phase I Limits on the Cosmic 21-cm Signal: Constraints on Astrophysics and Cosmology During the Epoch of Reionization
The HERA Collaboration, Zara Abdurashidova, James E. Aguirre +81
Recently, the Hydrogen Epoch of Reionization Array (HERA) collaboration has produced the experiment's first upper limits on the power spectrum of 21-cm fluctuations at z~8 and 10.…
Detection of Cosmic Structures using the Bispectrum Phase. II. First Results from Application to Cosmic Reionization Using the Hydrogen Epoch of Reionization Array
Nithyanandan Thyagarajan, Chris L. Carilli, Bojan Nikolic +69
Characterizing the epoch of reionization (EoR) at via the redshifted 21 cm line of neutral Hydrogen (HI) is critical to modern astrophysics and cosmology, and thus a k…
The local dimension of suborders of the Boolean lattice
David Lewis
We prove upper and lower bounds on the local dimension of any pair of layers of the Boolean lattice, and show that the local dimension of the first and middle layers of the -dim…
Improved Constraints on the 21 cm EoR Power Spectrum and the X-Ray Heating of the IGM with HERA Phase I Observations
The HERA Collaboration, Zara Abdurashidova, Tyrone Adams +92
We report the most sensitive upper limits to date on the 21 cm epoch of reionization power spectrum using 94 nights of observing with Phase I of the Hydrogen Epoch of Reionization…
Effects of model incompleteness on the drift-scan calibration of radio telescopes
Bharat K. Gehlot, Daniel C. Jacobs, Judd D. Bowman +76
Precision calibration poses challenges to experiments probing the redshifted 21-cm signal of neutral hydrogen from the Cosmic Dawn and Epoch of Reionization (z~30-6). In both inter…
Local -dimension
David Lewis
In this note, we introduce a new poset parameter called local -dimension. We also discuss the fractional variants of this and other dimension-like parameters.