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Abstract On 12 January 2022, an iceberg collapsed at the edge of frozen Atka Bay, Antarctica. The event generated seismic, hydroacoustic, and atmospheric infrasound waves recorded by a local network comprising land‐ and iceshelf‐based seismometers, an underwater hydrophone, and an on‐ice infrasound array. Analysis of the seismic and hydroacoustic data shows that the collapse occurred in at least three stages separated by approximately 16.5 and 8 s. The first stage produced a seismic head wave, a P‐wave, and a Rayleigh wave, and clear hydroacoustic and infrasound arrivals. Later stages were dominated by hydroacoustic and seismic Rayleigh waves. Two localization techniques were benchmarked: azimuthal cross‐bearing and a Bayesian joint inversion based on time‐difference‐of‐arrival. Both approaches accurately located the iceberg within a few hundred meters of its geolocation. These unique observations highlight the value of continuous seismo‐acoustic monitoring for investigating local cryospheric dynamics. 

Abstract Viable nature-based climate solutions (NbCS) are needed to achieve climate goals expressed in international agreements like the Paris Accord. Many NbCS pathways have strong scientific foundations and can deliver meaningful climate benefits but effective mitigation is undermined by pathways with less scientific certainty. Here we couple an extensive literature review with an expert elicitation on 43 pathways and find that at present the most used pathways, such as tropical forest conservation, have a solid scientific basis for mitigation. However, the experts suggested that some pathways, many with carbon credit eligibility and market activity, remain uncertain in terms of their climate mitigation efficacy. Sources of uncertainty include incomplete GHG measurement and accounting. We recommend focusing on resolving those uncertainties before broadly scaling implementation of those pathways in quantitative emission or sequestration mitigation plans. If appropriate, those pathways should be supported for their cobenefits, such as biodiversity and food security. 

This paper describes the ways in which an established K12 informal learning program, called Young Women in Computing (YWIC), utilizes culturally sustaining pedagogical practices to support learning, development, and leadership of youth outreach participants as well as undergraduate instructional staff. Authors emphasize the leadership roles undergraduates (here, authors 1-3) play in developing and implementing outreach designed and embodied at a Hispanic[1]Serving Institution. The three themes illustrated in this study include (1) opportunities for agency, or ownership, choice and autonomy for undergraduate leaders, (2) an emphasis on relationality, or developing personal relationships among undergraduate leaders and youth, and (3) the multiplicity of relevant knowledge and “ways of knowing” which contribute to viable pathways into computing. This paper argues the elevation of undergraduates better apprentices the next diverse educators and leaders in computing. 

Abstract Progress in gravitational-wave (GW) astronomy depends upon having sensitive detectors with good data quality. Since the end of the Laser Interferometer Gravitational-Wave Observatory-Virgo-KAGRA third Observing run in March 2020, detector-characterization efforts have lead to increased sensitivity of the detectors, swifter validation of GW candidates and improved tools used for data-quality products. In this article, we discuss these efforts in detail and their impact on our ability to detect and study GWs. These include the multiple instrumental investigations that led to reduction in transient noise, along with the work to improve software tools used to examine the detectors data-quality. We end with a brief discussion on the role and requirements of detector characterization as the sensitivity of our detectors further improves in the future Observing runs. 

Abstract The Gravitational-Wave Transient Catalog (GWTC) is a collection of short-duration (transient) gravitational-wave signals identified by the LIGO–Virgo–KAGRA Collaboration in gravitational-wave data produced by the eponymous detectors. The catalog provides information about the identified candidates, such as the arrival time and amplitude of the signal and properties of the signal’s source as inferred from the observational data. GWTC is the data release of this dataset, and version 4.0 extends the catalog to include observations made during the first part of the fourth LIGO–Virgo–KAGRA observing run up until 2024 January 31. This Letter marks an introduction to a collection of articles related to this version of the catalog, GWTC-4.0. The collection of articles accompanying the catalog provides documentation of the methods used to analyze the data, summaries of the catalog of events, observational measurements drawn from the population, and detailed discussions of selected candidates. 

The Heisenberg uncertainty principle dictates that the position and momentum of an object cannot be simultaneously measured with arbitrary precision, giving rise to an apparent limitation known as the standard quantum limit (SQL). Gravitational-wave detectors use photons to continuously measure the positions of freely falling mirrors and so are affected by the SQL. We investigated the performance of the Laser Interferometer Gravitational-Wave Observatory (LIGO) after the experimental realization of frequency-dependent squeezing designed to surpass the SQL. For the LIGO Livingston detector, we found that the upgrade reduces quantum noise below the SQL by a maximum of three decibels between 35 and 75 hertz while achieving a broadband sensitivity improvement, increasing the overall detector sensitivity during astrophysical observations. 

Abstract We report the observation of gravitational waves from two binary black hole coalescences during the fourth observing run of the LIGO–Virgo–KAGRA detector network, GW241011 and GW241110. The sources of these two signals are characterized by rapid and precisely measured primary spins, nonnegligible spin–orbit misalignment, and unequal mass ratios between their constituent black holes. These properties are characteristic of binaries in which the more massive object was itself formed from a previous binary black hole merger and suggest that the sources of GW241011 and GW241110 may have formed in dense stellar environments in which repeated mergers can take place. As the third-loudest gravitational-wave event published to date, with a median network signal-to-noise ratio of 36.0, GW241011 furthermore yields stringent constraints on the Kerr nature of black holes, the multipolar structure of gravitational-wave generation, and the existence of ultralight bosons within the mass range 10⁻¹³–10⁻¹²eV.