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  1. Abstract

    Deuterium fractionation provides a window into the thermal history of volatiles in the solar system and protoplanetary disks. While evidence of active molecular deuteration has been observed toward a handful of disks, it remains unclear whether this chemistry affects the composition of forming planetesimals due to limited observational constraints on the radial and vertical distribution of deuterated molecules. To shed light on this question, we introduce new Atacama Large Millimeter/submillimeter Array observations of DCO+and DCNJ= 2–1 at an angular resolution of 0.″5 (30 au) and combine them with archival data of higher energy transitions toward the protoplanetary disk around TW Hya. We carry out a radial excitation analysis assuming both LTE and non-LTE to localize the physical conditions traced by DCO+and DCN emission in the disk, thus assessing deuterium fractionation efficiencies and pathways at different disk locations. We find similar disk-averaged column densities of 1.9 × 1012and 9.8 × 1011cm−2for DCO+and DCN, with typical kinetic temperatures for both molecules of 20–30 K, indicating a common origin near the comet- and planet-forming midplane. The observed DCO+/DCN abundance ratio, combined with recent modeling results, provide tentative evidence of a gas-phase C/O enhancement within <40 au. Observations of DCO+and DCN in othermore »disks, as well as HCN and HCO+, will be necessary to place the trends exhibited by TW Hya in context, and fully constrain the main deuteration mechanisms in disks.

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  2. Recent breakthroughs in deep-learning (DL) approaches have resulted in the dynamic generation of trace links that are far more accurate than was previously possible. However, DL-generated links lack clear explanations, and therefore non-experts in the domain can find it difficult to understand the underlying semantics of the link, making it hard for them to evaluate the link's correctness or suitability for a specific software engineering task. In this paper we present a novel NLP pipeline for generating and visualizing trace link explanations. Our approach identifies domain-specific concepts, retrieves a corpus of concept-related sentences, mines concept definitions and usage examples, and identifies relations between cross-artifact concepts in order to explain the links. It applies a post-processing step to prioritize the most likely acronyms and definitions and to eliminate non-relevant ones. We evaluate our approach using project artifacts from three different domains of interstellar telescopes, positive train control, and electronic healthcare systems, and then report coverage, correctness, and potential utility of the generated definitions. We design and utilize an explanation interface which leverages concept definitions and relations to visualize and explain trace link rationales, and we report results from a user study that was conducted to evaluate the effectiveness of the explanationmore »interface. Results show that the explanations presented in the interface helped non-experts to understand the underlying semantics of a trace link and improved their ability to vet the correctness of the link.« less
    Free, publicly-accessible full text available May 21, 2023
  3. Schmerl, Bradley R. ; Maggio, Martina ; Camara, Javier (Ed.)
    The MAPE-K feedback loop has been established as the primary reference model for self-adaptive and autonomous systems in domains such as autonomous driving, robotics, and Cyber-Physical Systems. At the same time, the Human Machine Teaming (HMT) paradigm is designed to promote partnerships between humans and autonomous machines. It goes far beyond the degree of collaboration expected in human-on-the-loop and human-in-the-loop systems and emphasizes interactions, partnership, and teamwork between humans and machines. However, while MAPE-K enables fully autonomous behavior, it does not explicitly address the interactions between humans and machines as intended by HMT. In this paper, we present the MAPE-K-HMT framework which augments the traditional MAPE-K loop with support for HMT. We identify critical human-machine teaming factors and describe the infrastructure needed across the various phases of the MAPE-K loop in order to effectively support HMT. This includes runtime models that are constructed and populated dynamically across monitoring, analysis, planning, and execution phases to support human-machine partnerships. We illustrate MAPE-KHMT using examples from an autonomous multi-UAV emergency response system, and present guidelines for integrating HMT into MAPE-K.
    Free, publicly-accessible full text available May 18, 2023
  4. Authentic hands-on laboratory research is essential for undergraduate STEM education. Yet the tactile authenticity required to impact affective, cognitive, or psychomotor learning outcomes associated with laboratory training remains underexplored. Virtual and mixed-reality (VR/MR) have enabled increasingly realistic hands-on STEM training experiences. However, they still lack authenticity with regard to user manipulation of fully-functional and realistic laboratory tools, analysis of realistic (i.e. user-acquired) noisy data, and the application of critical thinking skills to draw conclusions from such noisy (and possible faulty) data. Here we present efforts to develop such an approach while also providing faculty content experts tools for code-free customization of VR/MR training experiences via structured spreadsheets. This approach enables nuanced real-time user feedback on laboratory skills such as proper pipetting or sterile technique which are otherwise difficult to provide. It also offers complete safety from chemical, biological, and radiological hazards and is more cost-effective than a traditional lab. This Hands-On Virtual-Reality (HOVR) Lab platform is uniquely enabling and will be valuable in the physical and life sciences for both research and instructional applications.
    Free, publicly-accessible full text available June 1, 2023
  5. Software traceability establishes a network of connections between diverse artifacts such as requirements, design, and code. However, given the cost and effort of creating and maintaining trace links manually, researchers have proposed automated approaches using information retrieval techniques. Current approaches focus almost entirely upon generating links between pairs of artifacts and have not leveraged the broader network of interconnected artifacts. In this paper we investigate the use of intermediate artifacts to enhance the accuracy of the generated trace links - focusing on paths consisting of source, target, and intermediate artifacts. We propose and evaluate combinations of techniques for computing semantic similarity, scaling scores across multiple paths, and aggregating results from multiple paths. We report results from five projects, including one large industrial project. We find that leveraging intermediate artifacts improves the accuracy of end-to-end trace retrieval across all datasets and accuracy metrics. After further analysis, we discover that leveraging intermediate artifacts is only helpful when a project's artifacts share a common vocabulary, which tends to occur in refinement and decomposition hierarchies of artifacts. Given our hybrid approach that integrates both direct and transitive links, we observed little to no loss of accuracy when intermediate artifacts lacked a shared vocabulary withmore »source or target artifacts.« less
  6. Abstract High spatial resolution CO observations of midinclination (≈30°–75°) protoplanetary disks offer an opportunity to study the vertical distribution of CO emission and temperature. The asymmetry of line emission relative to the disk major axis allows for a direct mapping of the emission height above the midplane, and for optically thick, spatially resolved emission in LTE, the intensity is a measure of the local gas temperature. Our analysis of Atacama Large Millimeter/submillimeter Array archival data yields CO emission surfaces, dynamically constrained stellar host masses, and disk atmosphere gas temperatures for the disks around the following: HD 142666, MY Lup, V4046 Sgr, HD 100546, GW Lup, WaOph 6, DoAr 25, Sz 91, CI Tau, and DM Tau. These sources span a wide range in stellar masses (0.50–2.10 M ⊙ ), ages (∼0.3–23 Myr), and CO gas radial emission extents (≈200–1000 au). This sample nearly triples the number of disks with mapped emission surfaces and confirms the wide diversity in line emitting heights ( z / r ≈ 0.1 to ≳0.5) hinted at in previous studies. We compute the radial and vertical CO gas temperature distributions for each disk. A few disks show local temperature dips or enhancements, some of which correspondmore »to dust substructures or the proposed locations of embedded planets. Several emission surfaces also show vertical substructures, which all align with rings and gaps in the millimeter dust. Combining our sample with literature sources, we find that CO line emitting heights weakly decline with stellar mass and gas temperature, which, despite large scatter, is consistent with simple scaling relations. We also observe a correlation between CO emission height and disk size, which is due to the flared structure of disks. Overall, CO emission surfaces trace ≈2–5× gas pressure scale heights (H g ) and could potentially be calibrated as empirical tracers of H g .« less
    Free, publicly-accessible full text available June 1, 2023
  7. With the rise of new AI technologies, autonomous systems are moving towards a paradigm in which increasing levels of responsibility are shifted from the human to the system, creating a transition from human-in-the-loop systems to human-on-the-loop (HoTL) systems. This has a significant impact on the safety analysis of such systems, as new types of errors occurring at the boundaries of human-machine interactions need to be taken into consideration. Traditional safety analysis typically focuses on system-level hazards with little focus on user-related or user-induced hazards that can cause critical system failures. To address this issue, we construct domain-level safety analysis assets for sUAS (small unmanned aerial systems) applications and describe the process we followed to explicitly, and systematically identify Human Interaction Points (HiPs), Hazard Factors and Mitigations from system hazards. We evaluate our approach by first investigating the extent to which recent sUAS incidents are covered by our hazard trees, and second by performing a study with six domain experts using our hazard trees to identify and document hazards for sUAS usage scenarios. Our study showed that our hazard trees provided effective coverage for a wide variety of sUAS application scenarios and were useful for stimulating safety thinking and helping usersmore »to identify and potentially mitigate human-interaction hazards.« less
  8. Abstract We report the discovery of a circumplanetary disk (CPD) candidate embedded in the circumstellar disk of the T Tauri star AS 209 at a radial distance of about 200 au (on-sky separation of 1.″4 from the star at a position angle of 161°), isolated via 13 CO J = 2−1 emission. This is the first instance of CPD detection via gaseous emission capable of tracing the overall CPD mass. The CPD is spatially unresolved with a 117 × 82 mas beam and manifests as a point source in 13 CO, indicating that its diameter is ≲14 au. The CPD is embedded within an annular gap in the circumstellar disk previously identified using 12 CO and near-infrared scattered-light observations and is associated with localized velocity perturbations in 12 CO. The coincidence of these features suggests that they have a common origin: an embedded giant planet. We use the 13 CO intensity to constrain the CPD gas temperature and mass. We find that the CPD temperature is ≳35 K, higher than the circumstellar disk temperature at the radial location of the CPD, 22 K, suggesting that heating sources localized to the CPD must be present. The CPD gas mass is ≳0.095more »M Jup ≃ 30 M ⊕ adopting a standard 13 CO abundance. From the nondetection of millimeter continuum emission at the location of the CPD (3 σ flux density ≲26.4 μ Jy), we infer that the CPD dust mass is ≲0.027 M ⊕ ≃ 2.2 lunar masses, indicating a low dust-to-gas mass ratio of ≲9 × 10 −4 . We discuss the formation mechanism of the CPD-hosting giant planet on a wide orbit in the framework of gravitational instability and pebble accretion.« less
    Free, publicly-accessible full text available July 27, 2023
  9. Runtime monitoring is essential for ensuring the safe operation and enabling self-adaptive behavior of Cyber-Physical Systems (CPS). It requires the creation of system monitors, instrumentation for data collection, and the definition of constraints. All of these aspects need to evolve to accommodate changes in the system. However, most existing approaches lack support for the automated generation and setup of monitors and constraints for diverse technologies and do not provide adequate support for evolving the monitoring infrastructure. Without this support, constraints and monitors can become stale and become less effective in long-running, rapidly changing CPS. In this ``new and emerging results'' paper we propose a novel framework for model-integrated runtime monitoring. We combine model-driven techniques and runtime monitoring to automatically generate large parts of the monitoring framework and to reduce the maintenance effort necessary when parts of the monitored system change. We build a prototype and evaluate our approach against a system for controlling the flights of unmanned aerial vehicles.