Local Group Research Articles

Gibbs state sampling via cluster expansions

Gibbs states (i.e., thermal states) can be used for several applications such as quantum simulation, quantum machine learning, quantum optimization, and the study of open quantum systems. Moreover, semi-definite programming, combinatorial optimization problems, and training quantum Boltzmann machines can all be addressed by sampling from well-prepared Gibbs states. With that, however, comes the fact that preparing and sampling from Gibbs states on a quantum computer are notoriously difficult tasks. Such tasks can require large overhead in resources and/or calibration even in the simplest of cases, as well as the fact that the implementation might be limited to only a specific set of systems. We propose a method based on sampling from a quasi-distribution consisting of tensor products of mixed states on local clusters, i.e., expanding the full Gibbs state into a sum of products of local “Gibbs-cumulant” type states easier to implement and sample from on quantum hardware. We begin with presenting results for 4-spin linear chains with XY spin interactions, for which we obtain the ZZ dynamical spin-spin correlation functions and dynamical structure factor. We also present the results of measuring the specific heat of the 8-spin chain Gibbs state ρ8.

Impacts of aquaculture practices on the sustainability of social-ecological systems in coastal zones of the Mekong Delta

Coastal and deltaic regions face increasing natural and human-induced hazards, such as cyclones, storm surges, erosion, and saline intrusion, exacerbated by climate change. In tropical zones, mangrove ecosystems provide vital protection against these threats, yet the conversion of mangroves to shrimp aquaculture undermines these benefits, even in protected areas.The Mekong Delta in Vietnam, historically rich in biodiversity and diverse habitats like mangroves and mudflats, has seen local communities thrive. However, rising global market demands have led to more intensive aquaculture models, posing new risks.This research examines the impact of shrimp farming models, from extensive to hyper-intensive, under multiple natural hazards and transformative processes like land conversion and mangrove restoration. Using risk assessment tools and data from local community interviews and focus groups, we present a model showcasing the influence of aquaculture on socio-ecological systems.Key findings reveal the interplay between livelihoods and landscape conversion, highlighting the risks and benefits of various shrimp farming models. The study stresses the need for stakeholder collaboration and improved wastewater treatment to enhance sustainability and environmental health in the Mekong Delta.

My Facebook Community

This article offers an autoethnographic account of the ways in which users of local Facebook groups in a U.S. suburb use the spaces to form community and personal identities. Through a reflection on my experiences of using local suburban Facebook groups, the article makes the argument that Facebook fails to offer a needed space for public discourse. However, it does provide a lens through which the negotiation and performance of a middle-class identity can be affirmed and contested. Through a reflection on the author’s experiences using local Facebook groups over a period of three years, the article aims to better understand how this platform fulfills this role in a suburban New Jersey community.

Galactic-Seismology Substructures and Streams Hunter with LAMOST and Gaia. I. Methodology and Local Halo Results

We present a novel, deep-learning-based method—dubbed Galactic-Seismology Substructures and Streams Hunter, or GS3 Hunter for short—to search for substructures and streams in stellar kinematics data. GS3 Hunter relies on a combined application of Siamese neural networks to transform the phase space information and the K-means algorithm for the clustering. As a validation test, we apply GS3 Hunter to a subset of the Feedback in Realistic Environments (FIRE) cosmological simulations. The stellar streams and substructures thus identified are in good agreement with corresponding results reported earlier by the FIRE team. In the same vein, we apply our method to a subset of local halo stars from the Gaia Early Data Release 3 and GALAH DR3 data sets and recover several previously known dynamical groups, such as Thamnos 1+2, the hot thick disk, ED-1, L-RL3, Helmi 1+2, Gaia-Sausage-Enceladus, Sequoia, Virgo Radial Merger, Cronus, and Nereus. Finally, we apply our method without fine-tuning to a subset of K giant stars located in the inner halo region, obtained from the LAMOST Data Release 5 data set. We recover three previously known structures (Sagittarius, Hercules-Aquila Cloud, and the Virgo Overdensity), but we also discover a number of new substructures. We anticipate that GS3 Hunter will become a useful tool for the community dedicated to the search for stellar streams and structures in the Milky Way (MW) and the Local Group, thus helping advance our understanding of the stellar inner and outer halos and the assembly and tidal stripping history in and around the MW.

First resolved stellar halo kinematics of a Milky Way-mass galaxy outside the Local Group: The flat counter-rotating halo in NGC 4945

First resolved stellar halo kinematics of a Milky Way-mass galaxy outside the Local Group: The flat counter-rotating halo in NGC 4945

The Local Group L-band Survey: The First Measurements of Localized Cold Neutral Medium Properties in the Low-metallicity Dwarf Galaxy NGC 6822

Abstract Measuring the properties of the cold neutral medium (CNM) in low-metallicity galaxies provides insights into heating and cooling mechanisms in early Universe-like environments. We report detections of two localized atomic neutral hydrogen (H i) absorption features in NGC 6822, a low-metallicity (0.2 Z ⊙) dwarf galaxy in the Local Group. These are the first unambiguous CNM detections in a low-metallicity dwarf galaxy outside the Magellanic Clouds. The Local Group L-band Survey (LGLBS) enabled these detections, due to its high spatial (15 pc for H i emission) and spectral (0.4 km s−1) resolution. We introduce LGLBS and describe a custom pipeline for searching for H i absorption at high angular resolution and extracting associated H i emission. A detailed Gaussian decomposition and radiative transfer analysis of the NGC 6822 detections reveals five CNM components, with key properties: a mean spin temperature of 32 ± 6 K, a mean CNM column density of 3.1 × 1020 cm−2, and CNM mass fractions of 0.33 and 0.12 for the two sightlines. Stacking nondetections does not reveal low-level signals below our median optical depth sensitivity of 0.05. One detection intercepts a star-forming region, with the H i absorption profile encompassing the CO (2−1) emission, indicating coincident molecular gas and a depression in high-resolution H i emission. We also analyze a nearby sightline with deep, narrow H i self-absorption dips, where the background warm neutral medium is attenuated by intervening CNM. The association of CNM, CO, and Hα emissions suggests a close link between the colder, denser H i phase and star formation in NGC 6822.

Prioritising animals for Yirralka Ranger management and research collaborations in the Laynhapuy Indigenous Protected Area, northern Australia

Context Amidst growing international calls for inclusive conservation and a backdrop of declining species and cultural diversity, Indigenous-led approaches that offer opportunities for biocultural benefits are of growing interest. Species prioritisation is one area that can be decolonised, shifting from quantitative, large-scale threatened species metrics to pluralistic, place-based approaches that include culturally significant species. Aim This study aimed to establish a list of priority animals of concern to Ŋaḻapaḻmi (senior knowledge holders) in the Laynhapuy Indigenous Protected Area, north-eastern Arnhem Land, Australia. This list could focus the research and management efforts of the Yirralka Rangers and collaborators. Methods Adhering to local governance structures, through six group-elicitation sessions, Ŋaḻapaḻmi were asked to identify animals of concern and describe reasons for concern. Existing occurrence records and threat status of these species were compiled to assess baseline data and guide next steps. Results The Ŋaḻapaḻmi-defined Laynhapuy Priority Animal List contained 30 animals (species/groups), with the highest-ranked animals including Marrtjinyami wäyin (walking animals), Rupu (possums), and Djanda (goannas), all mammals and varanid lizards. The list of 30 animals included 43 species from a Western-science perspective, of which 12 were also listed as threatened through Western conservation frameworks. Some animals were considered high priority locally, such as the waṉ’kurra (northern brown bandicoot, Isoodon macrourus), although not a concern from a Western-science perspective, demonstrating mismatch between local and larger-scale approaches. To help disentangle whether this mismatch is due to cultural significance and/or localised decline not captured at larger-scale assessments, we provide the animal’s publicly known Yolŋu clan connections and reasons for concern alongside existing baseline occurrence data. Recent collaborative surveys have substantially increased data for Laynhapuy Priority Animals, demonstrating the benefits of community engaged wildlife research. Conclusions Multidisciplinary research collaborations can produce Indigenous-led ‘working’ lists of priority animals to guide culturally attuned on-ground action. Approaches that draw on different cultural knowledge systems require interrogation of how knowledge is created and conveyed to ensure mutual comprehension and practical use. Implications Indigenous-led approaches offer possibilities for enhanced management of species by local groups, with anticipated co-benefits to species and cultural knowledge.

Mutual stacked autoencoder for unsupervised fault detection under complex multi-residual correlations

Due to the increasing complexity of variable relationships, fault detection has garnered significant attention, as it is crucial for ensuring industrial safety and engineering reliability. Traditional detection methods can be classified as twofold: global-based and local-based strategies, which respectively focus on mining macro- and micro-level information. However, our theoretical derivation and experiment results reveal that some spurious assumptions, such as local groups and their provided information are mutually independent are implicitly adhered to but are hardly satisfied in unsupervised fault detection under real industrial scenarios. Hence, this study introduces a novel mutual stacked autoencoder (M-SAE) which can be divided into three sub-networks: L-Net, R-Net, and M-Net. L-Net enriches local information learning through multiple local backbones by incorporating the unsupervised clustering algorithm. R-Net, employing a multi-scale attention mechanism, leverages complete local information for residual strength calculation and utilizes local features to capture residual information within the latent feature space. M-Net fuses the multi-scale local feature information to perform a reconstruction for each local. A multitask entropy-aided loss function is introduced to enrich local details, the global structure, and the residual associations. Finally, results on eleven datasets validate the high-performance of the proposed M-SAE and the ablation experiments demonstrate the efficacy of each component in M-SAE, confirming that this research effectively and accurately addresses multivariable industrial fault detection tasks, thereby enabling timely interventions that are crucial for maintaining operational safety in real-world scenarios.

LoVoCCS. II. Weak Lensing Mass Distributions, Red-sequence Galaxy Distributions, and Their Alignment with the Brightest Cluster Galaxy in 58 Nearby X-Ray-luminous Galaxy Clusters

The Local Volume Complete Cluster Survey is an ongoing program to observe nearly a hundred low-redshift X-ray-luminous galaxy clusters (redshifts 0.03 < z < 0.12 and X-ray luminosities in the 0.1–2.4 keV band L X500c > 1044 erg s−1) with the Dark Energy Camera, capturing data in the u, g, r, i, z bands with a 5σ point source depth of approximately 25th–26th AB magnitudes. Here, we map the aperture masses in 58 galaxy cluster fields using weak gravitational lensing. These clusters span a variety of dynamical states, from nearly relaxed to merging systems, and approximately half of them have not been subject to detailed weak lensing analysis before. In each cluster field, we analyze the alignment between the 2D mass distribution described by the aperture mass map, the 2D red-sequence (RS) galaxy distribution, and the brightest cluster galaxy (BCG). We find that the orientations of the BCG and the RS distribution are strongly aligned throughout the interiors of the clusters: the median misalignment angle is 19° within 2 Mpc. We also observe the alignment between the orientations of the RS distribution and the overall cluster mass distribution (by a median difference of 32° within 1 Mpc), although this is constrained by galaxy shape noise and the limitations of our cluster sample size. These types of alignment suggest long-term dynamical evolution within the clusters over cosmic timescales.

Cb-WoFS: Migrating the Warn-on-Forecast System to the Cloud

Abstract This article provides a brief, technical narrative of the WoFS journey to a cloud-based high-performance computing (HPC) system, including some of the technological challenges encountered and solutions found. Also, discussed are a few new components that are in development for cloud-based Warn-on-Forecast System (cb-WoFS), such as the cloud infrastructure project for managing resources, as well as a new web application that manages cb-WoFS runs. An important initial step in our cloud journey is containerizing all of the compiled applications, such as WRF, GSI, and EnKF and their dependencies like netCDF and MPI. With these applications compiled within an Apptainer container, WoFS can run on any local or cloud-based HPC cluster that supports MPI. Furthermore, an additional software layer was developed that creates and manages cloud vendor resources. This layer, which is referred to as the WoFS framework, contains the workflow required to run cb-WoFS, as well as management for other aspects of cb-WoFS (including but not limited to creation of HPC pools in the end-to-end workflow, runtime notifications, and database management). This additional layer was developed to separate the WoFS business logic from vendor-specific API calls. The WoFS framework exposes features through its service library, which is then referenced by the newly developed cb-WoFS web application and other cloud applications. This makes WoFS a complete end-to-end cloud-based application, where an administrator can launch a model run, manage resources, and view output all within a single web app.

An advocacy based cross sectional study of healthcare professionals of factors impacting on medication adherence across nine Sub-Saharan African countries

BackgroundAdherence to anti-seizure medication (ASM) by people diagnosed with epilepsy in sub-Saharan Africa remains low. The factors for low adherence are not well understood. To improve adherence, it is important to understand the perceptions and views of healthcare professionals delivering epilepsy care to this population. The aim was to investigate the factors influencing ASM adherence. MethodsThis study uses a brief online questionnaire which asked healthcare professionals (both from nursing and medical backgrounds) who work in sub-Saharan African countries to rate a set of pre-established options designed with the feedback of a local focus group of epilepsy experts from countries targeted. The questionnaire consisted of six questions and was a mix of multiple choice and Likert scale questions. ResultsThere were 217 healthcare professionals who replied to the questionnaire. The most important factors believed to be influencing adherence from a healthcare professional perspective are; lack of availability of medication for epilepsy (71%), affordability of medication (60%), the patient, family, carer lacking in understanding of medication (43%), cultural misconceptions about epilepsy (40%) and side effects of the medication (32%). The survey was answered by many different healthcare professionals; 65 participants were doctors and 152 were other healthcare professionals such as nurses (59%) pharmacists (10%) and when comparing them, the three most important categories were consistent across groups. ConclusionHealthcare workers in Sub-Saharan Africa identify that the primary factors impacting adherence to ASMs, in their view, is affordability and availability of ASMs.Addressing this issue may reduce the treatment gap.

Playing the scales: A strategy adopted by resistance coalitions for public value creation

Local actors can defend public value by mobilizing resistance coalitions against threats from higher spatial scales. Drawing on existing scholarship on resistance movements and public value creation, this paper proposes a theoretical framework for understanding how local actors can protect public value from threats of rescaling driven solely by hegemonic discourses and presents a strategy that we call “playing the scales.” Our case study analyzes a Local Action Group’s resistance to a state-imposed and EU-framed regulation that threatened local forms of value creation on the Croatian peninsula of Pelješac. Employing a longitudinal participatory approach, our findings outline the strategy of playing the scales, which involved three key tactics: gathering relevant knowledge from various scales; crafting an alternative narrative; and leveraging this narrative across scales to reshape the dominant organizational logic. The study contributes to the understanding of public value creation by showing how it can be defended by resistance coalitions that are capable of playing the scales. It also sheds light on alternative dynamics of rescaling that, rather than oppositional resistance to higher scales or attempts to scale up micro-practices can also be driven by trans-scalar alliances that inscribe the interests of local communities into dominant discourses.

Exploring the Experiences of Parents Caring for Children with Autism Spectrum Disorder in Nepal

This study aimed to explore the experiences of parents caring for children with Autism Spectrum Disorder (ASD). Ten parents (three males, seven females) with at least seven years of ASD caregiving experience were purposively sampled. In-depth interviews, recorded with consent, were conducted and transcribed, supplemented by phone interviews. Manual analysis of the data revealed common themes and patterns, offering insights into the challenges and experiences of ASD caregiving in Nepal. Parents in Nepal invest significant time and resources into their children's well-being, but identifying atypical behavior, particularly in children with ASD, might lead to stress and complications. Challenges in effective parenting stem from cultural, economic, and knowledge gaps in ASD caregiving. While sharing culture and essential caregiving knowledge aids in stress management, it's insufficient. Local governments and community groups might be offered accessible resources. Similarly, comprehensive support networks, stress management courses, instructional materials, and targeted interventions are necessary to address family-related stress effectively.

COMPUTING THE DEGREE-4 INVARIANT POLYNOMIAL BASIS FOR 7 QUBITS

Understanding the complexity of entangled states within the context of SLOCC (stochastic local operations and classical communications) involving several number qubits is essential for advancing our knowledge of quantum systems. This complexity is often analyzed by classifying the states via local symmetry groups. Practically, tthe resulting classes can be distinguished using invariant polynomials, but the size of these polynomials grows rapidly. Hence, it is crucial to obtain the smallest possible invariants. In this short note, we compute the basis of invariant polynomials of 7 qubits of degree 4, which are the smallest degree invariants. We obtain these polynomials using the representation theory and algebraic combinatorics.

Generalized symmetry in dynamical gravity

We explore generalized symmetry in the context of nonlinear dynamical gravity. Our basic strategy is to transcribe known results from Yang-Mills theory directly to gravity via the tetrad formalism, which recasts general relativity as a gauge theory of the local Lorentz group. By analogy, we deduce that gravity exhibits a one-form symmetry implemented by an operator Uα labeled by a center element α of the Lorentz group and associated with a certain area measured in Planck units. The corresponding charged line operator Wρ is the holonomy in a spin representation ρ, which is the gravitational analog of a Wilson loop. The topological linking of Uα and Wρ has an elegant physical interpretation from classical gravitation: the former materializes an exotic chiral cosmic string defect whose quantized conical deficit angle is measured by the latter. We verify this claim explicitly in an AdS-Schwarzschild black hole background. Notably, our conclusions imply that the standard model exhibits a new symmetry of nature at scales below the lightest neutrino mass. More generally, the absence of global symmetries in quantum gravity suggests that the gravitational one-form symmetry is either gauged or explicitly broken. The latter mandates the existence of fermions. Finally, we comment on generalizations to magnetic higher-form or higher-group gravitational symmetries.

A heterogeneous continuum traffic flow model considering mixed connected and autonomous vehicles

Under the background of mixed scenarios of Connected and Autonomous Vehicles and Connected and Autonomous Electric Vehicles, a novel mixed car-following model considering the information of multiple vehicles and the difference of safety spacing in different driving scenarios is proposed. Then, the corresponding heterogeneous continuum traffic flow model is derived. Secondly, through the linear and nonlinear analysis approaches, the linear stability condition and the KdV-Burgers equation are yielded to describe the characteristics of traffic flow evolution. Finally, numerical simulations are performed to explore the density evolution of traffic flow under different initial density and permeability conditions. The conclusions can be summarized as follows: (1) The derived model can well simulate spatiotemporal phase changes and traffic flow phenomena such as stop-and-go waves and local cluster effects. (2) With the increase of the permeability of electric vehicles and speed difference sensitivity coefficient, the road density decreases from 0.15veh/m to 0.06veh/m, the traffic congestion area decreases, and the traffic congestion is effectively suppressed, which also verifies the rationality of the above theory.

Computing whole embryo strain maps during gastrulation

Gastrulation is a critical process during embryonic development that transforms a single-layered blastula into a multilayered embryo with distinct germ layers, which eventually give rise to all the tissues and organs of the organism. Studies across species have uncovered the mechanisms underlying the building blocks of gastrulation movements, such as localized in-plane and out-of-plane epithelial deformations. The next challenge is to understand dynamics on the scale of the embryo: this requires quantifying strain tensors, which rigorously describe the differences between the deformed configurations taken on by local clusters of cells at time instants of observation and their reference configuration at an initial time. We present a systematic strategy for computing such tensors from the local dynamics of cell clusters, which are chosen across the embryo from several regions whose morphogenetic fate is central to viable gastrulation. As an application of our approach, we demonstrate a strategy of identifying distinct Drosophila morphological domains using strain tensors.

A simple model of dust extinction in gamma-ray burst host galaxies

Context. Gamma-ray burst (GRB) afterglows are powerful probes for studying the different properties of their host galaxies (e.g., the interstellar dust) at all redshifts. By fitting their spectral energy distribution (SED) over a large range of wavelengths, we can gain direct insights into the properties of the interstellar dust by studying the extinction curves. Unlike the dust extinction templates, such as those of the average Milky Way (MW) or the Small and Large Magellanic Cloud (SMC and LMC), the extinction curves of galaxies outside the Local Group exhibit deviation from these laws. Altogether, X-ray and gamma-ray satellites as well as ground-based telescopes, such as Neil Gehrels Swift Observatory (Swift) and Gamma-Ray Optical and Near-Infrared Detector (GROND), provide measurements of the afterglows from the X-ray to the NIR, which can be used to extract information on dust extinction curves along their lines of sight (LoS). The study presented in this paper undertakes such a photometric study, comprising a preparatory work for the SVOM mission and its ground-based follow-up telescope COLIBRI. Aims. We propose a simple approach to parameterize the dust extinction curve of GRB host galaxies. The model used in this analysis is based on a power law form with the addition of a Loretzian-like Drude profile with two parameters: the extinction slope, γ, and the 2175 Å bump amplitude, Eb. Methods. Using the g′r′i′z′JHKs GROND filter bands, we tested our dust extinction model and explored the parameter space in extinction and redshift by fitting SEDs of simplified simulations of GRB afterglow spectra based on different extinction curve templates. From a final sample of 10 real Swift/GROND extinguished GRBs, we determined the quantities of the dust extinction in their host and measured their extinction curves. Results. We find that our derived extinction curves are in agreement with the spectroscopic measurements reported for four GRBs in the literature. We compared four other GRBs to the results of photometric studies where fixed laws were used to fit their data. We additionally derived two new GRB extinction curves. The measured average extinction curve is given by a slope of γ = 1.051 ± 0.129 and Eb = 0.070 ± 0.036, which is equivalent to a quasi-featureless in-between SMC-LMC template. This is consistent with previous studies aimed at deriving the dust host galaxy extinction where we expect that small dust grains dominate in GRB environment, yielding a steeper curve than the mean MW extinction curve.

The Rise of the r-process in the Gaia-Sausage/Enceladus Dwarf Galaxy ∗

Neutron star mergers (NSMs) produce r-process elements after a time-delayed inspiral process. Once a significant number of NSMs are present in a galaxy, r-process elements, such as Eu, are expected to significantly increase with time. Yet, there have been limited observational data in support of Eu increasing within Local Group galaxies. We have obtained high-resolution Magellan/MIKE observations of 43 metal-poor stars in the Gaia-Sausage/Enceladus (GSE) tidally disrupted galaxy with −2.5 < [Fe/H] < −1. For the first time, we find a clear rise in [Eu/Mg] with increasing [Mg/H] within one galaxy. We use a simple chemical evolution model to study how such a rise can result from the interplay of prompt and delayed r-process enrichment events. Delayed r-process sources are required to explain the rise and subsequent leveling off of [Eu/Mg] in this disrupted galaxy. However, the rise may be explained by delayed r-process sources with either short (∼10 Myr) or long (∼500 Myr) minimum delay times. Future studies on the nature of r-process sources and their enrichment processes in the GSE will require additional stars in the GSE at even lower metallicities than the present study.

Networks between Ireland and the Irish American Diaspora during the Northern Ireland Peace Process

Abstract This article explores the complex relationship between the network of actors in the United States and Ireland who sought to influence American foreign policy in the Northern Ireland peace process. These networks operated in civil society, representing numerous Irish American organizations linking corporate and church leaders and the media to members of the Irish American diaspora in government to influence the United States’ diplomacy. These Irish American groups and individuals interested in influencing events in Northern Ireland were linked with a wide array of governmental and non-governmental actors in Ireland. Often, Americans were quite deferential to leaders and groups in Ireland and Northern Ireland who sought to mobilize the Irish diaspora in the United States for their cause. Thus, the United States’ role in Ireland and Northern Ireland was not that of a hegemonic power but one of an empathetic actor responding to developments and cues provided by various actors in the Irish context. Transatlantic networking, made more possible due to technological changes in communication and transportation, facilitated increased exchanges of ideas, agents, and information. These networks allowed groups across the Atlantic to elicit support for local groups in Northern Ireland and mobilize the US government to play a political and diplomatic role in the conflict and peace process. Ultimately, the majority of Irish Americans moved from supporting the nationalist/republican side in the early years of the Troubles to becoming strong supporters of the peace process in the 1990s.