Selected publications

• When Words Fail: ICU Nurses' Experiences Caring for Patients With Limited English Proficiency in the United States

  Journal of Advanced Nursing · 2025-09-05 · 1 citations

  article

  AIMS: To explore the lived experiences of intensive care nurses caring for patients with limited English proficiency. DESIGN: A hermeneutic, interpretive phenomenological design was used. METHODS: Semi-structured interviews were conducted with intensive care nurses recruited through purposive sampling. Data collection included Qualtrics screening surveys and semi-structured Zoom interviews. The research team, comprising linguistically diverse faculty and undergraduate research assistants, employed reflexivity techniques to minimise bias and enhance interpretive rigour. Data were analysed via inductive analysis using the hermeneutic circle. RESULTS: Five main themes emerged organically from the data: Complications of Care Relating to Verbal Communication Challenges. Benefits and Barriers of Nursing Informatics in Linguistic Care. The Universal Language: Nursing Effort Builds Trust. The Ripple Effect: Chronological Considerations for Patient Care. Moving Forward: Where Do We Go From Here? Based on these findings, a four-phase model was developed to guide individual and system-level interventions to reduce nurse moral distress and improve language equity in critical care. CONCLUSION: Language barriers in the intensive care unit hinder communication, increase stress for patients and nurses, and impact care quality. While nurses' efforts to bridge these gaps are valued, systemic changes (such as expanded interpreter availability and improved cultural safety training) are necessary to support culturally, linguistically, and medically appropriate care. IMPLICATIONS FOR THE PROFESSION AND/OR PATIENT CARE: Findings highlight the need for increased institutional support, additional resources for night-shift staff, and the integration of cultural humility education into intensive care training. The Limited English Proficiency Moral Distress Action Cycle for Critical Care Nursing, developed from this study, offers a flexible framework to guide the implementation of these improvements and reduce nurse moral distress. Future research should explore interventions to promote cultural and linguistic competence in multilingual patient populations. IMPACT: Q: What problem did the study address? A: The nurse-identified clinical, ethical, and workflow risks created when interpreters or translation tools are inadequate for critical care. Q: What were the main findings? A: Language barriers jeopardise teaching, informed consent, and symptom reporting. Video and phone interpreters or translation apps are vital but are often scarce, unreliable, or impersonal, particularly during night shifts. Nurses bridge these gaps by building trust through empathy, non-verbal communication, and learning key phrases. Yet, effective care for patients with limited English proficiency requires extra time, increasing workloads and fuelling moral distress related to language-discordant care. Nurses consistently called for 24/7 interpreter coverage; more reliable devices and cultural humility training must be implemented system-wide. Q: Where and on whom will the research have an impact? A: Findings can guide nurses, managers, leaders, and administrators to improve both language concordant and discordant nursing care and train nurses in cultural and linguistic competencies for a multilingual patient population. Ultimately, these efforts have been shown to improve the quality, outcomes, and cost-effectiveness of patient care. The study also identifies moral-distress triggers and introduces the Limited English Proficiency Moral Distress Action Cycle (LEP-MDAC). This model is proposed for use in other high-acuity settings worldwide that seek to provide language-concordant or language-discordant care effectively. REPORTING METHOD: SRQR. PATIENT OR PUBLIC CONTRIBUTION: None.

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• Automatic Machine Learning Framework to Study Morphological Parameters of AGN Host Galaxies within $z < 1.4$ in the Hyper Supreme-Cam Wide Survey

  ArXiv.org · 2025-01-27

  preprintOpen access

  We present a composite machine learning framework to estimate posterior probability distributions of bulge-to-total light ratio, half-light radius, and flux for Active Galactic Nucleus (AGN) host galaxies within $z<1.4$ and $m<23$ in the Hyper Supreme-Cam Wide survey. We divide the data into five redshift bins: low ($0

  PublisherOA PDFDOI

• BASS. LIII. The Eddington Ratio as the Primary Regulator of the Fraction of X-Ray Emission in Active Galactic Nuclei

  The Astrophysical Journal · 2025-08-29 · 2 citations

  articleOpen access

  Abstract Active galactic nuclei (AGN) emit radiation via accretion across the entire energy spectrum. While the standard disk and corona model can somewhat describe this emission, it fails to predict specific features such as the soft X-ray excess, the short-term optical/UV variability, and the observed UV/X-ray correlation in AGN. In this context, the fraction of AGN emission in different bands (i.e., bolometric corrections) can be useful to better understand the accretion physics of AGN. Past studies have shown that the X-ray bolometric corrections are strongly dependent on the physical properties of AGN, such as their luminosities and Eddington ratios. However, since these two parameters depend on each other, it has been unclear which is the main driver of the X-ray bolometric corrections. We present here results from a large study of hard-X-ray-selected (14–195 keV) nearby ( z < 0.1) AGN. Based on our systematic analysis of the simultaneous optical-to-X-ray spectral energy distributions of 236 unobscured AGN, we found that the primary parameter controlling the X-ray bolometric corrections is the Eddington ratio. Our results show that, while the X-ray bolometric correction increases with the bolometric luminosity for sources with intermediate Eddington ratios (0.01–1), this dependence vanishes for sources with lower Eddington ratios (<0.01). This could be used as evidence for a change in the accretion physics of AGN at low Eddington ratios.

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• BASS XLVII: 22 GHz Radio Atlas of Swift-BAT Selected AGN

  ArXiv.org · 2025-01-28

  preprintOpen access

  We present the third phase of the largest high-frequency, high-resolution imaging survey of 231 nearby, hard X-ray selected AGN, with a very high $98 \pm 1\%$ detection fraction. This survey presents VLA 22 GHz radio observations with 1" spatial resolution covering over $6$ orders of magnitude in radio luminosity in nearby AGN that span $\sim4$ orders of magnitude in black hole mass and X-ray luminosity. We identify three different radio morphologies: $44 \pm 3\%$ (102/231) are compact or unresolved, $46 \pm 3\%$ (106/231) show an extended structure (star formation, possible one-sided jets, etc.), and $8 \pm 2\%$ (19/231) have a biconical or two-sided jet-like morphology. The remaining $2 \pm 1\%$ (4/231) sources are non-detections. The radio-to-X-ray luminosity ratios of the Swift-BAT AGN ($\text{L}_R/\text{L}_{14-195 \text{keV}} \sim 10^{-5.5}$ and $\text{L}_R/\text{L}_{2-10 \text{keV}} \sim 10^{-5}$) with a scatter of $\sim0.5$ dex are similar to that of coronally active stars ($\text{L}_R/\text{L}_X \sim 10^{-5}$). For most targets, extended emission in radio-quiet objects is broadly consistent with the expectation for star formation from previous FIR observations, once the contribution from the radio core has been subtracted. Our sample represents nearby analogs of distant AGN at the peak of black hole growth, and thus the high detection fraction in our work has important implications for future high frequency AGN radio surveys with the next generation VLA (ngVLA) or Square Kilometre Array (SKA), both of which should detect large fractions of more distant AGN.

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• NuSTAR observations of a varying-flux quasar in the Epoch of Reionization

  ArXiv.org · 2025-01-13

  preprintOpen accessSenior author

  With enough X-ray flux to be detected in a 160s scan by SRG/eROSITA, the $z = 6.19$ quasar CFHQS J142952+544717 is, by far, the most luminous X-ray source known at $z > 6$. We present deep (245 ks) NuSTAR observations of this source; with $\sim180$ net counts in the combined observations, CFHQS J142952+544717 is the most distant object ever observed by the observatory. Fortuitously, this source was independently observed by Chandra $\sim110$ days earlier, enabling the identification of two nearby (30'' and 45'' away), fainter X-ray sources. We jointly fit both Chandra and NuSTAR observations--self-consistently including interloper sources--and find that, to greater than 90% confidence, the observed 3-7 keV flux varied by a factor of $\sim2.6$ during that period, corresponding to approximately two weeks in the quasar rest-frame. This brightening is one the most extreme instances of statistically significant X-ray variability seen in the Epoch of Reionization. We discuss possible scenarios that could produce such rapid change, including X-ray emission from jets too faint at radio frequencies to be observed.

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• BASS. XLV. Quantifying Active Galactic Nuclei Selection Effects in the Chandra COSMOS-legacy Survey with BASS

  The Astrophysical Journal · 2025-03-25 · 1 citations

  articleOpen access

  Abstract Deep extragalactic X-ray surveys, such as the Chandra COSMOS-Legacy field (CCLS), are prone to be biased against active galactic nuclei (AGN) with high column densities due to their lower count rates at a given luminosity. To quantify this selection effect, we forward model nearby ( z ∼ 0.05) AGN from the BAT AGN Spectroscopic Survey (BASS) with well-characterized (≳1000 cts) broadband X-ray spectra (0.5–195 keV) to simulate the CCLS absorption distribution. We utilize the BASS low-redshift analogs with similar luminosities to the CCLS ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msubsup> <mml:mrow> <mml:mi>L</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> <mml:mo>−</mml:mo> <mml:mn>10</mml:mn> <mml:mspace width="0.25em"/> <mml:mi mathvariant="normal">keV</mml:mi> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">int</mml:mi> </mml:mrow> </mml:msubsup> </mml:math> ∼ 10 42−45 erg s), which are much less affected by obscuration and low-count statistics, as the seed for our simulations and follow the spectral fitting of the CCLS. Our simulations reveal that Chandra would fail to detect the majority (53.3%; 563/1056) of obscured ( N H ≥ 10 22 cm −2 ) simulated BASS AGN given the observed redshift and luminosity distribution of the CCLS. Even for detected sources with sufficient counts (≥30) for spectral modeling, the level of obscuration is significantly overestimated. This bias is most extreme for objects whose best fit indicates a high-column density AGN ( N H ≥ 10 24 cm −2 ), since the majority (66.7%; 18/27) of these are actually unobscured sources ( N H &lt; 10 22 cm −2 ). This implies that previous studies may have significantly overestimated the increase in the obscured fraction with redshift and the fraction of luminous obscured AGN. Our findings highlight the importance of directly considering obscuration biases and forward modeling in X-ray surveys, as well as the need for higher-sensitivity X-ray missions such as the Advanced X-ray Imaging Satellite (AXIS), and the importance of multiwavelength indicators to estimate obscuration in distant supermassive black holes.

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• Automatic Machine Learning Framework to Study Morphological Parameters of AGN Host Galaxies within z &lt; 1.4 in the Hyper Supreme-Cam Wide Survey

  The Astrophysical Journal · 2025-02-21 · 2 citations

  articleOpen access

  Abstract We present a composite machine learning framework to estimate posterior probability distributions of bulge-to-total light ratio, half-light radius, and flux for active galactic nucleus (AGN) host galaxies within z &lt; 1.4 and m &lt; 23 in the Hyper Supreme-Cam (HSC) Wide survey. We divide the data into five redshift bins: low (0 &lt; z &lt; 0.25), mid (0.25 &lt; z &lt; 0.5), high (0.5 &lt; z &lt; 0.9), extra (0.9 &lt; z &lt; 1.1), and extreme (1.1 &lt; z &lt; 1.4), and train our models independently in each bin. We use PSFGAN to decompose the AGN point-source light from its host galaxy, and invoke the Galaxy Morphology Posterior Estimation Network (GaMPEN) to estimate morphological parameters of the recovered host galaxy. We first trained our models on simulated data, and then fine-tuned our algorithm via transfer learning using labeled real data. To create training labels for transfer learning, we used GALFIT to fit ∼20,000 real HSC galaxies in each redshift bin. We comprehensively examined that the predicted values from our final models agree well with the GALFIT values for the vast majority of cases. Our PSFGAN + GaMPEN framework runs at least three orders of magnitude faster than traditional light-profile fitting methods, and can be easily retrained for other morphological parameters or on other data sets with diverse ranges of resolutions, seeing conditions, and signal-to-noise ratios, making it an ideal tool for analyzing AGN host galaxies from large surveys coming soon from the Rubin-LSST, Euclid, and Roman telescopes.

  PublisherDOI

• Molecular Gas in Major Mergers Hosting Dual and Single AGNs at &lt;10 kpc Nuclear Separations

  The Astrophysical Journal · 2025-12-09 · 1 citations

  articleOpen accessSenior author

  Abstract We present high-resolution (∼50–100 pc) Atacama Large Millimeter/submillimeter Array observations of 12 CO(2–1) or 12 CO(1–0) emission in seven local ( z ≲ 0.05) major mergers—five of which are dual active galactic nucleus (AGN) systems, and two of which are single AGN systems. We model the molecular gas kinematics through rotating disk profiles using a Bayesian Markov Chain Monte Carlo approach. The residuals were then used to isolate nonrotating components of the molecular gas—the most likely contributor to future supermassive black hole (SMBH) growth. We find that more-massive SMBHs have higher surface densities of nonrotating molecular gas within their sphere of influence. This potential molecular gas supply, however, does not correlate with the current accretion efficiency of the SMBHs, suggesting that only a fraction of the observed nonrotating gas is currently reaching the SMBH. Finally, we tentatively find no significant differences in the nuclear molecular gas masses of single-AGN and dual-AGN hosts, both within the SMBH sphere of influence and within the central kiloparsec. Our results indicate that the probability of occurrence of the dual AGN phenomenon is likely dependent on AGN variability and/or obscuration rather than the availability of molecular gas in the nuclear regions.

  PublisherDOI

• BASS. LII. The Prevalence of Double-peaked Broad Lines at Low Accretion Rates among Hard X-Ray Selected Active Galactic Nuclei

  The Astrophysical Journal · 2025-09-19 · 3 citations

  articleOpen accessSenior author

  Abstract A fraction of active galactic nuclei (AGN) have double-peaked H α , H β, and Mg II broad lines attributed to emission from rotating gas in the accretion disk. Using optical spectroscopy of a flux-limited sample of AGN selected via ultrahard X-rays from the BAT AGN Spectroscopic Survey (BASS), we systematically identify 71 double-peaked emitters (DPEs) among 343 broad-line AGN with redshifts 0.004 &lt; z &lt; 0.297 and X-ray luminosities of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>40</mml:mn> <mml:mo>&lt;</mml:mo> <mml:mi>log</mml:mi> <mml:msub> <mml:mrow> <mml:mi>L</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> <mml:mo>−</mml:mo> <mml:mn>10</mml:mn> <mml:mspace width="0.1em"/> <mml:mtext>KeV</mml:mtext> <mml:mspace width="0.1em"/> </mml:mrow> </mml:msub> </mml:math> (erg s −1 ) &lt; 45.7, and provide their best-fit accretion disk parameters. We find that ∼21% of X-ray-selected broad-line AGN are DPEs, consistent with rates previously reported for z &lt; 0.2 broad-line AGN selected for strong optical variability in the Zwicky Transient Facility. 11 of 71 DPEs (15%) exhibited a single-peaked Gaussian component to the broad line profile in addition to the double-peaked disk profile. In this sample, DPEs have intrinsically higher masses by ∼0.4 dex and lower Eddington ratios by ∼0.3 dex than other broad-line AGN, and have a preference for elliptical host galaxies, higher X-ray luminosities, and higher [O i ] λ 6302 to narrow H α flux ratios than other broad-line AGN. We find that DPEs are not segregated from non-DPE broad-line AGN in the L bol versus M BH relation or their X-ray to radio luminosity ratios, and do not show a preference for intermediate Seyfert types over Seyfert 1s. We do not find differences in a wide range of multiwavelength properties when comparing DPEs to non-DPE broad-line AGN, including optical and mid-IR variability levels, Wide-field Infrared Survey Explorer colors, α ox , the column density of neutral obscuring material N H , and the rate of changing-look events. We discuss the two populations in the context of multicomponent disk-wind models of the AGN broad-line region and consider how unrecognized contributions of disk emission to the broad lines may introduce biases in “virial” supermassive black hole mass estimates, with consequences for the inferred M BH – M * relation.

  PublisherDOI

• BASS. LIV. Physical Properties of AGN-hosting Galaxy Mergers from Multiwavelength SED Fitting

  The Astrophysical Journal · 2025-11-25 · 1 citations

  articleOpen accessCorresponding

  Abstract Galaxy mergers are believed to play an important role in triggering rapid supermassive black hole (SMBH) growth. As merging nuclei approach each other, the physical properties of the participating galaxies and the associated SMBH growth are expected to evolve significantly. This study measures and characterizes these physical properties throughout the merger sequence. We constructed multiwavelength spectral energy distributions (SEDs) from hard X-rays to the far-IR for a sample of 72 nearby active galactic nucleus (AGN) host galaxies. The sample comprises 64 interacting systems, including single AGN in mergers and dual AGN, with nuclear separations ≤30 kpc, as well as eight isolated active galaxies with merging features. We carefully adapted available photometric measurements at each wavelength to account for their complex morphologies and varying spatial resolutions, to perform SED fitting using CIGALE, aimed to derive critical physical properties. Our results reveal that merging galaxies hosting AGN(s) show deviations from the star-forming main sequence and a wide range of star formation rates (SFRs). Both AGN activity and star formation are significantly influenced by the merger process, but these effects are more prominent in major (mass ratios &lt; 4:1) interactions. We find that the projected nuclear separation is not a good tracer of the merger stage. Instead, morphological classification accurately assesses the merger progression. Based on this morphological analysis, late-stage mergers exhibit elevated SFRs (5.1×), AGN luminosities (2.4×), and nuclear obscuration (2.8×) compared to earlier stages, supporting previous findings and reinforcing the link between merger-driven galaxy evolution and SMBH growth.

  PublisherDOI