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result(s) for
"Kynoch, D"
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Intensive X-ray/UVOIR continuum reverberation mapping of the Seyfert AGN MCG+08-11-11
by
Cackett, E M
,
Done, C
,
Hernández Santisteban, J V
in
Active galactic nuclei
,
Luminosity
,
Mapping
2025
We present results from intensive (x3 daily), three-month-long X-ray, UV and optical monitoring of the bright Seyfert active galactic nucleus (AGN) MCG+08-11-11 with Swift, supported by optical-infrared ground-based monitoring. The 12 resultant, well-sampled, lightcurves are highly correlated; in particular, the X-ray to UV correlation r_max = 0.85 is, as far as we know, the highest yet recorded in a Seyfert galaxy. The lags increase with wavelength, as expected from reprocessing of central high-energy emission by surrounding material. Our lag spectrum is much shallower than that obtained from an optical monitoring campaign conducted a year earlier when MCG+08-11-11 was approximately 4 times brighter. After filtering out long-term trends in the earlier optical lightcurves we recover shorter lags consistent with our own - demonstrating concurrent reverberation signals from different spatial scales and the luminosity dependence of the measured lags. We use our lag spectrum to test several physical models, finding that disc reprocessing models cannot account for the observed 'excess' lags in the u and r-i-bands that are highly indicative of the Balmer and Paschen continua produced by reprocessing in the broad line region (BLR) gas. The structure seen in both the variable (rms) and lag spectra, and the large time delay between X-ray and UV variations (approximately 2 days) all suggest that the BLR is the dominant reprocessor. The hard X-ray spectrum (Gamma approximately 1.7) and faint, red, UV-optical spectrum both indicate that the Eddington accretion ratio is low: approximately 0.03. The bolometric luminosity then requires that the black hole mass is substantially greater than current reverberation mapping derived estimates.
The first spectroscopic IR reverberation programme on Mrk 509
by
Mitchell, J A J
,
Hernández Santisteban, J V
,
Packham, C
in
Accretion disks
,
Active galactic nuclei
,
Blackbody
2024
Near IR spectroscopic reverberation of Active Galactic Nuclei (AGN) potentially allows the infrared (IR) broad line region (BLR) to be reverberated alongside the disc and dust continua, while the spectra can also reveal details of dust astro-chemistry. Here, we describe results of a short pilot study (17 near-IR spectra over a 183 d period) for Mrk 509. The spectra give a luminosity-weighted dust radius of \\(\\langle R_{\\mathrm{d,lum}} \\rangle = 186 \\pm 4\\) light-days for blackbody (large grain dust), consistent with previous (photometric) reverberation campaigns, whereas carbon and silicate dust give much larger radii. We develop a method of calibrating spectral data in objects where the narrow lines are extended beyond the slit width. We demonstrate this by showing our resultant photometric band light curves are consistent with previous results, with a hot dust lag at >40 d in the K band, clearly different from the accretion disc response at <20 d in the z band. We place this limit of 40 d by demonstrating clearly that the modest variability that we do detect in the H and K band does not reverberate on time-scales of less than 40 d. We also extract the Pa\\(\\beta\\) line light curve, and find a lag which is consistent with the optical BLR H\\(\\beta\\) line of \\(\\sim\\)70-90 d. This is important as direct imaging of the near-IR BLR is now possible in a few objects, so we need to understand its relation to the better studied optical BLR.
The first spectroscopic dust reverberation programme on active galactic nuclei: the torus in NGC 5548
2019
We have recently initiated the first spectroscopic dust reverberation programme on active galactic nuclei (AGN) in the near-infrared. Spectroscopy enables measurement of dust properties, such as flux, temperature and covering factor, with higher precision than photometry. In particular, it enables measurement of both luminosity-based dust radii and dust response times. Here we report results from a one-year campaign on NGC 5548. The hot dust responds to changes in the irradiating flux with a lag time of ~70 light-days, similar to what was previously found in photometric reverberation campaigns. The mean and rms spectra are similar, implying that the same dust component dominates both the emission and the variations. The dust lag time is consistent with the luminosity-based dust radius only if we assume a wavelength-independent dust emissivity-law, i.e. a blackbody, which is appropriate for grains of large sizes (of a few microns). For such grains the dust temperature is ~1450 K. Therefore, silicate grains have most likely evaporated and carbon is the main chemical component. But the hot dust is not close to its sublimation temperature, contrary to popular belief. This is further supported by our observation of temperature variations largely consistent with a heating/cooling process. Therefore, the inner dust-free region is enlarged and the dusty torus rather a \"dusty wall\", whose inner radius is expected to be luminosity-invariant. The dust-destruction mechanism that enlarges the dust-free region seems to partly affect also the dusty region. We observe a cyclical decrease in dust mass with implied dust reformation times of ~5-6 months.
On the black hole mass of the gamma-ray emitting narrow-line Seyfert 1 galaxy 1H 0323+342
2016
Narrow-line Seyfert 1 galaxies have been identified by the Fermi Gamma-Ray Space Telescope as a rare class of gamma-ray emitting active galactic nuclei (AGN). The lowest-redshift candidate among them is the source 1H 0323+342. Here we present quasi-simultaneous Gemini near-infrared and Keck optical spectroscopy for it, from which we derive a black hole mass based on both the broad Balmer and Paschen emission lines. We supplement these observations with a NuSTAR X-ray spectrum taken about two years earlier, from which we constrain the black hole mass based on the short timescale spectral variability. Our multiwavelength observations suggest a black hole mass of ~2x10^7 solar masses, which agrees well with previous estimates. We build the spectral energy distribution and show that it is dominated by the thermal and reprocessed emission from the accretion disc rather than the non-thermal jet component. A detailed spectral fitting with the energy-conserving accretion disc model of Done et al. constrains the Eddington ratio to L/L_Edd ~ 0.5 for a (non-rotating) Schwarzschild black hole and to L/L_Edd ~ 1 for a Kerr black hole with dimensionless spin of a*=0.8. Higher spin values and so higher Eddington ratios are excluded, since they would strongly overpredict the observed soft X-ray flux.
Broad-scale acoustic telemetry reveals long-distance movements and large home ranges for invasive lionfish on Atlantic coral reefs
by
Akins, John L.
,
Nemeth, Richard S.
,
Green, Stephanie J.
in
Acoustic telemetry
,
Coral reefs
,
Culling
2021
Tracking studies for invasive lionfish (Pterois volitans and P. miles) in the Western Atlantic can provide key information on habitat use to inform population control, but to date have likely underestimated home range size and movement due to constrained spatial and temporal scales. We tracked 35 acoustically tagged lionfish for >1 yr (March 2018–May 2019) within a 35 km² acoustic array in Buck Island Reef National Monument, St. Croix, US Virgin Islands (an area 10× larger than previous studies). Tracking lionfish at this scale revealed that home range size is 3–20 times larger than previously estimated and varies more than 8-fold across individuals (~48 000–379 000 m²; average: 101 000 m²), with estimates insensitive to assumptions about potential mortality for low-movement individuals. Lionfish move far greater distances than previously reported, with 37% of fish traveling >1 km from the initial tagging site toward deeper habitats, and 1 individual moving ~10 km during a 10 d period. Movement rates, home range size, and maximum distance traveled were not related to lionfish size (18–35 cm total length) or lunar phase. Lionfish movement was lowest at night and greatest during crepuscular periods, with fish acceleration (m s−2) increasing with water temperature during these times. Our results help reconcile observed patterns of rapid recolonization following lionfish removal, and suggest complex drivers likely result in highly variable patterns of movement for similarly sized fish occupying the same habitat. Culling areas ≥ the average lionfish home range size identified here (i.e. ~10 ha) or habitat patches isolated by ≥ ~180 m (radius of average home range) may minimize subsequent recolonization. If the shallow–deep long-distance movements observed here are unidirectional, mesophotic habitats may require culling at relatively greater frequencies to counteract ongoing migration.
Journal Article
Assessing the Impact of Nurse Post-Discharge Telephone Calls on 30-Day Hospital Readmission Rates
by
Quinn, Kathryn
,
Kynoch, Ellen
,
Mourad, Michelle
in
Adult
,
Aftercare - organization & administration
,
Aged
2014
ABSTRACT
BACKGROUND
Several care transition interventions propose that post-discharge phone calls can reduce adverse events and decrease costly return visits to the hospital. However, given the multi-faceted nature of most care transitions interventions, the true relationship between post-discharge phone calls and readmissions in a real world setting is uncertain.
OBJECTIVE
To determine the effect of receiving a post-discharge telephone call on all-cause 30-day readmission in a general medicine population.
DESIGN
Retrospective observational study.
PARTICIPANTS
Patients discharged home from the Medicine Service at a tertiary care academic medical center between November 2010 and May 2012.
INTERVENTION
Patients received two telephone call attempts by a nurse within 72 h of discharge. Nurses followed a standard script to address issues associated with readmission.
MAIN OUTCOME AND MEASURES
Billing data captured readmissions. We used logistic regression-adjusted patient and clinical covariates as well as a propensity score representing likelihood of being called to determine the association between call receipt and risk for readmission.
KEY RESULTS
There were 5,507 eligible patients. In unadjusted analyses, patients who received a call and completed the intervention were significantly less likely to be readmitted compared to those who did not [155 (5.8 %) vs 123 (8.6 %),
p
< 0.01]. In multivariable models adjusting for socio-demographic and clinical covariates alone, completing a post-discharge telephone call intervention was associated with lower odds for readmission (AOR 0.71; 95 % CI: 0.55–0.91). However, when models adjusted for the likelihood of receiving the phone call using the propensity score, no association between call receipt and readmission was observed (AOR 0.91; 95%CI: 0.69–1.20).
CONCLUSIONS
Effectiveness of post-discharge phone call programs may be more related to whether patients are able to answer a phone call than to the care delivered by the phone call. Programs would benefit from improving their ability to perform phone outreach while simultaneously improving on the care delivered during the calls.
Journal Article
Multiple drivers of invasive lionfish culling efficiency in marine protected areas
by
Green, Stephanie J.
,
Akins, Lad
,
Johnston, Michelle A.
in
Atlantic
,
Caribbean
,
citizen science
2021
Designing effective local management for invasive species poses a major challenge for conservation, yet factors affecting intervention success and efficiency are rarely evaluated and incorporated into practice. We coordinated regional efforts by divers to cull invasive lionfish (Pterois spp.) on 33 U.S. Atlantic, Gulf of Mexico, and Caribbean protected coral reefs from 2013 to 2019 and estimated removal efficiency and efficacy as a function of environmental and habitat conditions, invasion status, and personnel expertise. Highly experienced individuals culling during crepuscular periods (<2 hr from sunrise/sunset) are three times more efficient (in terms of minutes) than novice divers during midday, suggesting: (a) retention of experienced individuals is key for efficient programs, and (b) planning culls with personnel and time of day in mind increases the number of sites covered with the same effort. Lionfish behavior and habitat characteristics had little effect on removal efficiency and efficacy, but divers had higher capture success at reefs with higher lionfish densities. We suggest reefs with persistently <20 fish ha−1 as low priority, given that impacts to native fauna are unlikely and culling effectiveness declines to <50% below this level. Incorporating efficiency factors in spatial management planning along with density estimates derived from remotely sensed data can ensure limited resources for control are extended across a greater range of invaded habitats. Many invasive species removal plans must now strive for suppressing densities rather than total eradication of the invasive species. Invasive lionfish in the Western Atlantic and Caribbean is such a species due to its widespread range and detrimental effects on native species. We found removal efficacy of invasive lionfish is determined by removal experience, density, and size of the lionfish as well as the time of day when removal are performed.
Journal Article
Feeding ecology of invasive lionfish (Pterois volitans and Pterois miles) in the temperate and tropical western Atlantic
by
Layman, Craig A
,
Chapman, Jennifer
,
Morris, James A
in
Carnivores
,
Computer simulation
,
Crabs
2018
Numerous location-based diet studies have been published describing different aspects of invasive lionfish (Pterois volitans and Pterois miles) feeding ecology, but there has been no synthesis of their diet composition and feeding patterns across regional gradients. 8125 lionfish stomachs collected from 10 locations were analyzed to provide a generalized description of their feeding ecology at a regional scale and to compare their diet among locations. Our regional data indicate lionfish in the western Atlantic are opportunistic generalist carnivores that consume at least 167 vertebrate and invertebrate prey species across multiple trophic guilds, and carnivorous fish and shrimp prey that are not managed fishery species and not considered at risk of extinction by the International Union for Conservation of Nature disproportionately dominate their diet. Correlations between lionfish size and their diet composition indicate lionfish in the western Atlantic transition from a shrimp-dominated diet to a fish-dominated diet through ontogeny. Lionfish total length (TL) (mm) was found to predict mean prey mass per stomach (g) by the following equation mean prey mass =0.0002*TL1.6391, which can be used to estimate prey biomass consumption from lionfish length-frequency data. Our locational comparisons indicate lionfish diet varies considerably among locations, even at the group (e.g., crab) and trophic guild levels. The Modified Index of Relative Importance developed specifically for this study, calculated as the frequency of prey a × the number of prey a, can be used in other diet studies to assess prey importance when prey mass data are not available. Researchers and managers can use the diet data presented in this study to make inference about lionfish feeding ecology in areas where their diet has yet to be described. These data can be used to guide research and monitoring efforts, and can be used in modeling exercises to simulate the potential effects of lionfish on marine food webs. Given the large variability in lionfish diet composition among locations, this study highlights the importance of continued location-based diet assessments to better inform local management activities.
Journal Article
Tomorrow's paediatricians: factors influencing graduating doctors in choosing a career in paediatrics
2012
Aim To identify influencing factors for a graduating doctor considering a career in paediatrics. Methods An online structured questionnaire was distributed using SurveyMonkey to all graduating doctors at Cardiff, Bristol and Glasgow Schools' of Medicine. Respondents were asked to provide demographic information, as well as their ideal career choice followed by the specialty they realistically see themselves pursuing. Following this, respondents rated 19 career influences using a 5-point Likert scale. Data was analysed using non-parametric tests. Results The response rate was 31% (233/751) with 60.5% from Cardiff, 23.6% from Glasgow and 15.5% from Bristol. 81.5% (n=190) were undergraduates and 63.1% (n=147) were female. Mann-Whitney tests were employed to characterise the differing career influences between males and females. Males were more influenced than females by public prestige (p=0.01), professional prestige (p=0.01) and research opportunities (p=0.03), whereas factors more influential for females were patient relationships (p=<0.001), working hours (p=<0.001), job stress (p=0.01) and lifestyle (p=<0.001). 19.8% (n=46) stated they would ideally like a career in paediatrics, with only 6.9% (n=16) feeling they would realistically end up fulfilling this ambition. Of those 30 students who felt an alternative career was more likely, 28/30 felt they would realistically become GPs. Those who were confident of an eventual career in paediatrics were significantly less influenced by working hours (p=0.002), lifestyle (p=0.02), financial incentives (p=0.006) and training length (p=0.001). Conclusion These findings highlight the importance of engaging with the future paediatric workforce, especially for ensuring high quality workforce planning. The apparent move towards specialties that allow a better work-life balance means that those responsible for maintaining adequate recruitment into paediatrics will need to address the priorities of tomorrow's doctors.
Journal Article