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Variability in SSTc2d J163134.1-240100, a brown dwarf with quasi-spherical mass loss
No full textFunding: AS acknowledges support from the UKRI Science and Technology Facilities Council through grant ST/Y001419/1/. KM acknowledges support from the Fundação para a Ciência e a Tecnologia (FCT) through the CEEC individual contract 2022.03809.CEECIND and research grants UIDB/04434/2020 and UIDP/04434/2020.We report on a search for variability in the young brown dwarf SST1624 (∼M7 spectral type, M ∼ 0.05 M⊙), previously found to feature an expanding gaseous shell and to undergo quasi-spherical mass loss. We find no variability on timescales of 1-6 hours. Specifically, on these timescales, we rule out the presence of a period with amplitude > 1%. A photometric period in that range would have been evidence for either pulsation powered by Deuterium burning or rotation near breakup. However, we see a 3% decrease in the K-band magnitude between two consecutive observing nights (a 10 σ result). There is also clear evidence for variations in the WISE lightcurves at 3.6 and 4.5 µm on timescales of days, with a tentative period of about 6 d (with a plausible range between 3 and 7 d). The best explanation for the variations over days is rotational modulation due to spots. These results disfavour centrifugal winds driven by fast rotation as mechanism for the mass loss, which, in turn, makes the alternative scenario – a thermal pulse due to Deuterium burning – more plausible.Peer reviewe
Chimpanzees’ working memory is not affected by the presence and activity of zoo visitors
No full textFunding: Leverhulme Trust (ECF-2023-573); Templeton World Charity Foundation (TWCF-2021-20648).Cognitive research in non-human primates is increasingly conducted in zoos, where zoo visitors are likely to be present and observe the testing sessions. Previous zoo research has shown that such presence can modulate cognitive performance in monkeys, but similar investigations on great apes are still lacking. Here, we investigated the influence of the presence and activity level of zoo visitors on eight chimpanzees (Pan troglodytes) while they completed a working memory task with various difficulty levels. We also recorded whether their conspecifics were present or not in the testing area, and their approximate physical distance. We found that the presence and activity level of the visitors had no effect on chimpanzees’ working memory, regardless of the cognitive demands of the task. Similarly, the presence of conspecifics and how far they were from the individual being tested was not found to significantly influence performance either. These non-significant effects were supported by Bayesian analyses giving support for the null hypotheses. These results suggest that zoo-living chimpanzees are not distracted by visitors when completing a cognitive task. We suggest new directions to further explore social presence effects in great apes.Peer reviewe
Behavioral responses of goose-beaked whales (Ziphius cavirostris) to simulated military sonar
No full textFunding: US Fleet Forces Command Marine Species Monitoring Program; Naval Facilities Engineering Command Southeast, Grant/Award Numbers: N62470-10-D-3011, N62470-15-D-8006.We report direct measurements of changes in diving and movement behavior for 53 goose-beaked whales (Ziphius cavirostris) in relation to experimentally controlled mid-frequency (3–4 kHz) active sonar (MFAS) signals. These signals simulate powerful Navy sources that have been associated with multiple mortal stranding events for this species. We deployed a multi-scale combination of tags to monitor individual whales, including 50 long-duration (weeks), coarse-resolution satellite-transmitting tags and 3 short-duration (hours), high-resolution archival depth, orientation, and acoustic tags. We evaluated behavioral responses during 13 experimental trials (9 MFAS; 4 no-MFAS controls), resulting in 72 exposure events; some individuals were exposed in multiple trials. Whales were exposed at known and modeled horizontal ranges from ~2 to >200 km and from below ambient noise levels to received levels (RLs) up to ~142 dB re: 1μPa (root-mean-square [RMS]). We investigated changes in diving and movement behavior separately, with a suite of metrics, descriptive evaluations, and statistical tests. We observed similar patterns and probabilities of behavioral changes for control trials and the lowest RL conditions (<100 dB). Above 100 dB RLs, increasingly prevalent and consistent responses occurred, including extended deep dives, prolonged periods between deep dives, directed spatial movement away from the source, and cessation of echolocation. Aspects of these cryptic responses typically persisted for hours following exposure but did not result in broad-scale habitat abandonment. Our study builds upon experimental and observational studies conducted on sonar testing ranges and expands our understanding of the response of this species to MFAS in a region where operational sonar use occurs far less commonly than on Navy testing ranges. These data are directly applicable in the conservation and effective management of this sensitive, protected species.Peer reviewe
Syntheses, characterization, Hirshfeld analysis, and antioxidant activity of Co(II) and Ag(I) complexes based on oxadiazole ligand
No full textFunding: This work was supported by “the Deanship of Scientific Research, Vice Presidency for Graduate Studies and Scientific Research, King Faisal University, for financial support under the annual funding track [KFU254518]”.The antioxidant activities of [Co(L)2Cl2]·0.25H2O and [Ag2(L)2]n(ClO4)2n complexes with 2-(5-(pyridin-2-yl)-1,2,4-oxadiazol-3-yl)aniline ( L ) are reported to explore their molecular, supramolecular and antioxidant characteristics. Their molecular structures were examined using FTIR and other spectroscopic techniques, and single crystal X-ray diffraction. The Co(II) complex shows a discrete octahedral structure, while the Ag(I) complex is a 1D coordination polymer. Both complexes were evaluated for their antioxidant activities utilizing 1,1-diphenyl-2-picrylhydrazyl (DPPH), nitric oxide, and superoxide anion scavenging assays. The Ag(I) complex consistently demonstrated the highest antioxidant activity across all the three assays (DPPH; IC50 = 52.07 ± 1.22 µM), (nitric oxide; IC50 = 29.14 ± 1.04 µM), and (superoxide; IC50 = 8.74 ± 1.85 µM), particularly excelling in superoxide anion scavenging. The Co(II) complex also showed enhanced activity compared to L especially in the nitric oxide (IC50= 24.70±1.65 µM), and superoxide anion assays (IC50 = 20.78 ± 2.85 µM). These findings reveal how metal-ligand systems can be tuned to enhance antioxidant efficiency, providing insight for the design of bioactive metal complexes as antioxidants.Peer reviewe
A2A adenosine receptor agonists with last-step enzymatic 18F-labelling potential (fluorinase) for positron emission tomography (PET)
No full textFunding: This study was supported by Engineering and Physical Sciences Research Council (EP/X038904/1).New agonists of the A2A receptor are reported with 18F-labelling potential for positron emission tomography (PET). These were designed by exploiting common binding interactions of substrates for the fluorinase and agonists of the human A2A adenosine receptor. Target compounds were structurally inspired by the selective A2A receptor agonist CGS21680 . The new agonists were synthesised and their affinities for the human A2A receptor evaluated through radioligand displacement assays. 18F-Labelled analogues of the new agonists for potential PET radiotracer applications are now accessible through last-step radiosynthesis using the fluorinase enzyme and [18F]fluoride.Peer reviewe
Reimagining better addiction treatment services through telemedicine : a complex systems approach
No full textIn 2022, the United States, Scotland and Canada had among the highest drug-related death rates in the world, at 329 per million, 193.3 per million, and 190 per million of the population respectively. The use of Telemedicine to provide Medications for Opioid Use Disorder (TMOUD), such as buprenorphine or methadone, has been identified as an innovation which could increase access to evidence-based treatment. The COVID-19 pandemic saw a sharp rise in the use of TMOUD in North America. In Scotland, despite national efforts to drive telemedicine uptake during the pandemic, the number of addiction-related telemedicine consults fell by 67%. Three peer reviewed publications are presented in this thesis to inform a complex systems understanding of this discrepancy and to identify ways of maximising the potential of TMOUD in mitigating the DRD crisis in Scotland. Paper 1 synthesises the peer-reviewed literature to conceptualise TMOUD as a multifaceted healthcare delivery system. Paper 2 applies Normalisation Process Theory (NPT) to the peer-reviewed literature to understand the work required of stakeholders to embed and normalise TMOUD into routine practice. Paper 3 uses the Successful Healthcare Improvement From Translating Evidence in complex systems (SHIFT-Evidence) framework, collating evidence from Paper 1 and 2 with practice-based knowledge and expert opinion to develop a TMOUD implementation model. This thesis applies the accumulated knowledge from these three papers to make the case for TMOUD in re-imagining addiction treatment services in Scotland. Key findings applicable to both the Scottish and international contexts include the potential for telemedicine to enable low-barrier access, continuity of care, complex care management and improved service resilience. Further, the uptake and spread of TMOUD requires health equity driven, multi-level whole-systems policy and practice interventions which address structural stigma, siloed funding, data and services and power imbalances between clinicians and people who use drugs
Comparison of fluorescent, phosphorescent and TADF luminophores for explosive detection
No full textThe detection of nitroaromatic compounds is crucial for protecting people from explosive hazards, as well as for preserving ecosystems from their toxic effects. Photoluminescence-based sensors offer one approach to detect trace levels of explosives. The detection mechanism is commonly based on a bimolecular interaction between the luminophore and explosive molecule, in which a photoinduced electron transfer (PET) from the luminophore to the analyte causes a quenching of the photoluminescence. The sensitivity and quenching behaviour of the sensor is closely related to the interaction strength between these two compounds, and the emission mechanism of the luminophore.
In this thesis, the influence of the emission mechanisms (fluorescence, phosphorescence, and thermally activated delayed fluorescence - TADF) on the photoluminescent response towards the detection of nitroaromatic explosives was investigated. To evaluate the luminescence quenching kinetics of representative emitters, steady-state and time-resolved photoluminescence measurements are applied in solution and vapour sensing experiments.
The quenching behaviour exhibited by the TADF compounds in solution, was found to deviate from a linear Stern-Volmer relationship, and to be strongly dependent on the intrinsic parameters of the TADF emitter: the product of the initial ISC and RISC quantum yields; the sum of all singlet rate constants; and the sum of all triplet rate constants; with the singlet and triplet populations being quenched with different efficiencies. To model the quenching dynamics of this class of emitters, modified Stern–Volmer equations were derived and applied to different TADF molecules when used as luminophores for sensing a range of PET quenchers.
Vapour sensing was investigated through a combination of steady-state and time-resolved luminescence measurements, showing for the first time that TADF molecules can be used as a sensor for nitroaromatic vapours. These results indicate that in the solid state, the singlet and triplet populations are each quenched by the analyte, and that the temporal response may be modified by blending the luminophore in different polymer hosts.
In summary, the results presented in this thesis demonstrate for the first time the advantages of applying TADF materials as photoluminescent sensors of nitroaromatic compounds and, more broadly, PET quenchers, in both solution and vapour sensing. Besides offering a promising route to significantly increase the sensitivity of PET quencher, the careful monitoring of the singlet and triplet population of TADF quenching systems can be a valuable tool to achieve selectivity in photoluminescence sensors."This work was supported by the University of St Andrews Centre for Doctoral Training in Quantum Materials (QM-CDT) and Edinburgh Instruments Ltd."--Fundin
The SDSS-V Black Hole Mapper Reverberation Mapping project : light echoes of the coronal-line region in a luminous quasar
Full text linkFunding: T.B.S. acknowledges support from a UConn SURF award. L.B.F., J.R.T., M.C.D., and H.W.S. acknowledge support from NSF grants CAREER-1945546 and AST-2007993. Y.S. acknowledges support from NSF grant AST-2009947. F.E.B. acknowledges support from ANID-Chile BASAL CATA FB210003, FONDECYT Regular 1241005, and Millennium Science Initiative, AIM23-0001. J.D.M.’s research was supported by an appointment to the NASA Postdoctoral Program at the NASA Goddard Space Flight Center, administered by Oak Ridge Associated Universities under contract with NASA.We present a reverberation mapping (RM) analysis of the coronal line [Ne v] λ3427-emitting region of the quasar COS168 (SDSS J095910.30+020732.2). [Ne v] λ3427 is known as one of the “coronal lines,” which are a species of emission lines present in active galactic nuclei (AGN) spectra with high ionization potentials (≥ 100 eV) that can serve as tracers for AGN activity. The spatial extent of the coronal line region has been studied with only spatial resolving techniques that are not sensitive to the innermost regions of AGN. Through our RM analysis of [Ne v] λ3427, we measure a nominal “optimal emission radius” for [Ne v] λ3427 of 381.1+16-22 lt-day (observed frame). We place the coronal line region in context with other AGN regions by comparing it with the characteristic radius of Hα, the dust-sublimation radius, and the dusty torus. The coronal line region is located at a larger radius from the black hole than the characteristic radius of the dusty torus, measured using a torus–radius luminosity relationship. The virial product (v2R/G) of both Hα and [Ne v] λ3427 is consistent within the uncertainties, implying that the coronal line region, as probed by the [Ne v] λ3427 line, may be in a virialized orbit that is dominated by the gravitational potential of the black hole. This plausibly suggests that coronal lines could be an effective method for estimating black hole masses.Peer reviewe
Surgical fixation versus non-surgical care for children with a displaced medial epicondyle fracture of the elbow (the SCIENCE study) : a multicentre, randomised controlled, superiority trial and economic evaluation
Full text linkFunding: National Institute for Health and Care Research (NIHR) Health Technology Assessment programme (17/18/02), with additional support from the NIHR Academy, Oxford NIHR Biomedical Research Centre, and the Starship Foundation (New Zealand).Background: Displaced medial epicondyle fractures are among the most controversial injuries in children, with increasing trends towards surgical fixation despite little supporting evidence. Approximately half of affected children undergo surgical fixation, while others receive non-surgical care. The SCIENCE trial aimed to determine whether surgical fixation to restore the position of the bone provides superior functional outcomes and is cost-effective compared with non-surgical care. Methods: We conducted a pragmatic multicentre, randomised, superiority trial across 59 hospitals in the UK, Australia, and New Zealand. Recruiting sites were secondary or tertiary care hospitals providing acute paediatric trauma care. Eligible participants were aged 7-15 years with a displaced medial epicondyle fracture and patients were excluded if the injury occurred more than 2 weeks prior, they had a medial epicondyle fragment that was incarcerated (trapped) within the joint, the injury was part of a complex elbow fracture (ie, extending into the joint), or there were additional fractured bones outside of the elbow. Participants were randomly assigned (1:1) to either surgical fixation or non-surgical care using a web-based randomisation software from Oxford Clinical Trials Research Unit, with minimisation (including a random element) stratified by centre and elbow dislocation status at presentation. Participants and their parents and carers could not be masked to treatment. Surgical fixation was performed under general anaesthesia and involved a surgical incision, restoration of the anatomical alignment, and fixing the fragment, typically with a screw or wires. Non-surgical care involved immobilisation of the elbow at approximately 90° of flexion using a cast, splint, or sling. Both groups were allowed mobilisation as pain allowed, although cast immobilisation beyond 4 weeks was discouraged. The primary outcome was upper limb function at 12 months, measured using the Patient Report Outcomes Measurement System (PROMIS) Upper Extremity Score for Children in the intention-to-treat population, which included all participants in the groups to which they were randomly assigned, irrespective of treatment received. Complications and serious adverse events were summarised in a safety (as-treated) population defined by treatment received. A within-trial economic evaluation was undertaken from the perspective of the UK National Health Service and Personal Social Services over a 12-month time period. The trial was registered with ISRCTN, ISRCTN16619778; recruitment is complete and extended follow-up to age 16 years is ongoing. Findings: Between June 10, 2019, and Sept 22, 2023, 647 patients from 59 sites met the inclusion criteria. 146 patients were excluded (64 due to the injury being more than 2 weeks old and 24 because the epicondyle fragment was incarcerated within the joint), 161 families of children meeting the eligibility criteria declined to participate, and for five patients there was no clinician equipoise. 335 participants were randomly assigned to an intervention (166 to the non-surgical care group and 168 to the surgical fixation group) and one was immediately excluded due to a randomisation error. Primary outcome data were collected from 285 (85%) participants. 170 (51%) participants were female and 164 (49%) were male. Mean participant age at baseline was 11·7 years (SD 2·3). At 12 months post-randomisation, the PROMIS Upper Extremity score was 53·1 (SD 7·8) in the non-surgical care group and 54·3 (5·7) in the surgical fixation group (mean treatment difference, 1·57 [95% CI -0·01 to 3·14; p=0·052]). This estimate of treatment effect was below the clinically important difference specified (4 points), supporting the conclusion that a clinically important effect is unlikely. Additional episodes of surgery, either planned or related to complications, occurred in 24 participants in the surgical group and three in the non-surgical group. Among the 150 participants who underwent surgical fixation, there were 14 intraoperative complications from 13 (9%) participants, and seven participants had a postoperative complication (5% participants) each requiring surgery. Routine screw or wire removal was undertaken in a further 17 (11%) participants. From the 184 participants in the non-surgical group, there were five complications among four (2%) participants, three (2%) of which required additional surgery. The mean per patient cost from the NHS and Personal Social Services perspective was £2435 (95% CI 1812 to 3057) more for participants in the surgical fixation group with a mean per patient quality-adjusted life year difference of -0·008 (95% CI -0·039 to 0·024). The probability that surgical fixation is cost-effective at the £20 000 or £30 000 per quality-adjusted life year willingness-to-pay threshold was 0%. Interpretation: The SCIENCE trial demonstrates that surgical fixation offers no clinical benefit and is not cost-effective compared with non-surgical care, while exposing children to avoidable surgical risks. These findings suggest that non-surgical care should be adopted as the default management strategy for these injuries, regardless of initial elbow dislocation status.Peer reviewe
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