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Uncertainties in the production of iron-group nuclides in core-collapse supernovae from Monte Carlo variations of reaction rates
Full text linkCore-collapse supernovae, occurring at the end of massive star evolution, produce heavy elements, including those in the iron peak. Although the explosion mechanism is not yet fully understood, theoretical models can reproduce optical observations and observed elemental abundances. However, many nuclear reaction rates involved in explosive nucleosynthesis have large uncertainties, impacting the reliability of abundance predictions. To address this, we have previously developed a Monte Carlo-based nucleosynthesis code that accounts for reaction rate uncertainties and has been applied to nucleosynthesis processes beyond iron. Our framework is also well suited for studying explosive nucleosynthesis in supernovae. In this paper, we investigate 1D explosion models using the 'PUSH method', focusing on progenitors with varying metallicities and initial masses around. Detailed post-process nucleosynthesis calculations and Monte Carlo analyses are used to explore the effects of reaction rate uncertainties and to identify key reaction rates in explosive nucleosynthesis. We find that many reactions have little impact on the production of iron-group nuclei, as these elements are primarily synthesized in the nuclear statistical equilibrium. However, we identify a few 'key reactions' that significantly influence the production of radioactive nuclei, which may affect astrophysical observables. In particular, for the production of, we confirm that several traditionally studied nuclear reactions have a strong impact. However, determining a single reaction rate is insufficient to draw a definitive conclusion
Learning to Gaze: Bio-Inspired Attention Adaptation Strategy for Social Robots
Full text linkAdaptive attention allocation in dynamic social environments remains a fundamental challenge for autonomous robots, requiring the integration of perceptual saliency, social context, and real-time decision-making.We present a bio-inspired reinforcement learning framework for robotic gaze control that incorporates a habituation mechanism to regulate the exploration–exploitation trade-off, mirroring how biological attention systems filter redundant stimuli whilst remaining responsive to novel events. Through a comprehensive ablation study comparing Deep Q-Learning (DQL), Vanilla Q-Learning (VQL), and Multi-Objective Q-Learning (MOL), we uncover a critical insight: habituation significantly enhances DQL performance, improving response efficiency and policy stability, yet causes systematic degradation in MOL due to fundamental incompatibilities between fixed-threshold resets and the extended episodes required for multi-objective optimisation. This differential effect reveals that bio-inspired mechanisms cannot be applied universally across learning architectures but must be carefully matched to algorithmic characteristics. Real-world deployment on the ARI humanoid robot validates the framework’s practical applicability, achieving robust gaze prediction accuracy across diverse interaction scenarios with well-calibrated confidence metrics that reliably distinguish correct from incorrect predictions. Our findings provide evidence-based guidelines for integrating biological principles into cognitive robotics, demonstrating both the promise and the pitfalls of bio-inspired mechanism design
The effects of graded tasks on physical activity: a systematic review and meta-analysis
Full text linkThis review establishes the extent to which the behaviour change technique (BCT) Graded Tasks is effective in increasing physical activity. Databases, including PubMed, Cochrane and PsycINFO, were searched (October 2024) for randomised control trials of Graded Tasks interventions with adult physical activity change as the main outcome. Graded Tasks were always delivered alongside BCTs ‘goal setting (behaviour)’ and ‘action planning’. Of the 53 identified studies (N = 10,060), 39 were included in a random effects meta-analysis, indicating a significant, medium effect of Graded Tasks interventions in increasing physical activity (N = 4190, g = 0.61, CI 95% 0.42–0.81, p <.001, I 2= 83%). Prevention-based interventions (g = 0.78, CI 95% 0.43–1.12, p <.001, I 2= 90%) had larger effects than treatment-based interventions (g = 0.38, CI 95% 0.23–0.53, p <.001, I 2= 34). The number of Graded Task increments explained significant variability in physical activity change (R 2 = 0.47, β = 0.68, p <.001). GRADE certainty of evidence was rated low. Graded Tasks, in conjunction with other BCTs, are effective for increasing physical activity, particularly for prevention. The included studies did, however, show high heterogeneity and potential publication bias. PROSPERO registration: CRD42022347300
On the Origin of Kinematic Structure in the Young Association Serpens OB2
Full text linkThe Serpens OB2 association (l ~ 18.5 deg, b ~ 1.9 deg, d = 1950 +/- 30 pc) is a large star-forming complex ~65 pc above the Galactic midplane, with a clumpy, elongated structure extending ~50 pc parallel to the plane. We analyse probable association members, including OB stars and low-to-intermediate-mass young stellar objects (YSOs) from the SPICY catalogue. We use 13CO MWISP data to trace the molecular clouds. The OB stars are concentrated toward the centre of the association, coincident with a gap in the molecular clouds, and toward the side nearest the Galactic plane. The YSOs are distributed throughout the association, but cluster around molecular-cloud clumps. Using Gaia DR3 proper motions to probe the association's internal kinematics, we find aligned stellar velocities on length scales <2 pc, two-point statistics that show increasing velocity differences and predominantly divergent motions at larger separations, and distinct velocities for star clusters within the association. Finally, the association exhibits gradual but statistically significant global expansion perpendicular to the Galactic plane, with a spatial gradient of 0.10 +/- 0.02 km/s/pc. The clumpy stellar distribution, correlated velocities on small scales, and increasingly divergent motions on larger scales are consistent with an initial velocity field inherited from a turbulent molecular cloud modified by stellar feedback. The global vertical expansion may arise from large-scale turbulence or feedback-driven shell expansion, with the H II region Sh 2-54 preferentially pushing the molecular gas away from the Galactic plane. Ser OB2 demonstrates that the multi-scale expansion of an OB association can begin even while star formation is still ongoing throughout the complex
Inhibition of levodopa-induced abnormal involuntary movements (AIMs) using a selective α7 nicotinic positive allosteric modulator
Full text linkChronic administration of nicotine and nicotinic ligands have been shown to reduce levodopa-induced dyskinesia (LID) in rodents and primates. Due to its unique extra-striatal localisation and biochemical signalling properties, the α7 subtype of nicotinic acetylcholine receptors (nAChRs) may represent an important and unique target for drug development for the treatment of dyskinesia, particularly since positive allosteric modulator (PAM) at the α7 nAChRs subtype may provide an opportunity to reduce dyskinesia without side effects. In this study, we report on the anti-dyskinetic actions of a selective α7 PAM, PNU-120596 and compared its action to nicotine and other α7 nAChRs ligands. Unilaterally 6-OHDA lesioned female rats were primed with levodopa to display abnormal involuntary movements (AIMs) to model levodopa-induced dyskinesia. The effects of the α7 PAM, PNU-120596, an α7 agonist, PHA-543613 or the α7 antagonist, methyllycaconitine (MLA), as well as nicotine, a non-selective nAChR agonist were all examined on AIMs. Low doses of PNU-120596 and nicotine dose-dependently reduced AIMs, but combination of the PAM with nicotine produced only an additive effect which surprisingly, could not be demonstrated with the α7 agonist PHA-543613, while MLA dose-dependently reduced AIMS. The effects of PNU-120596 suggests that α7 PAMs may enhance the effect of basal acetylcholine on α7 receptors in the striatum and may provide a new avenue for the treatment of levodopa-induced dyskinesia. Reduction of AIMs by MLA suggests that the mechanism of AIMs reduction may involve the rapid desensitization of the α7 nAChRs subtype
Constraining black hole spin in PG 1535+547 amidst complex multi-layered absorption
Full text linkWe present a spectroscopic analysis of XMM-Newton and NuSTAR observations of the 'complex' NLS1 PG 1535+547 at redshift . These observations span three epochs: 2002 and 2006 with XMM-Newton alone, covering the keV energy range, and a coordinated XMM-Newton and NuSTAR observation in 2016, covering the keV energy range. The X-ray spectra across all epochs exhibit both neutral and ionized absorption, along with reflection features from the accretion disc, including a prominent Compton hump in the broadband data. Notably, the spectral shape varies across epochs. Our analysis suggests this variability is attributed to changes in both line-of-sight absorption and the intrinsic emission from PG 1535+547. The source is obscured by multiple layers of partially and/or fully covering neutral and ionized absorbers, with neutral column densities ranging from undetectable levels in the least obscured phase to in the most obscured phase. A clear warm absorber is revealed during the least obscured phase. The continuum remains fairly consistent () during the first two observations, followed by a substantial flux decrease (by a factor of in the keV band) in 2016 compared to 2006. The 2016 data indicates the source is in a reflection-dominated state during this epoch, with a reflection fraction of and an X-ray source located at a height . Simultaneous fitting of the multi-epoch data suggests a rapidly rotating black hole with a spin parameter, . These findings imply that strong light-bending effects may account for the observed continuum flux reduction
Evaluating the Impact of Dedicated Simulation Days on the Confidence of First-Year Diagnostic Radiography Students
Full text linkIntroduction From the use of phantoms to positioning software, simulation-based education (SBE) has become an integral part of radiography education. Evidence suggests that simulation is not only preferred by students but can substantially increase their clinical confidence1. This study aims to explore student’s confidence levels after undertaking a range of simulation-based activities. Methods First year diagnostic radiography students attended three dedicated simulation days prior to their first clinical placement block. The students were asked to complete a survey before and after their simulation days. This contained both qualitative and quantitative questions aimed at understanding the student's confidence level regarding clinical practice. Results A 13% response rate was obtained for the initial questionnaire. Clinical concerns included lack of experience, understanding radiation dose, and image evaluation. The second questionnaire showed increased confidence when communicating with patients, using the equipment and understanding how to apply radiation protection principles. An area that remained a concern was the positioning technique for some more complex examinations. Conclusion Results indicate an increase in reported confidence, with students able to give examples of specific areas where simulation had a significant impact, and where they perceived their abilities to be much improved. There were some lingering concerns regarding radiographic positioning of certain body parts, which could be due to the time limitations of the simulation sessions. Overall, the simulation days successfully increased student confidence prior to their first weeks of clinical placement. Implications for practice. The inclusion of dedicated simulation time should be considered for all undergraduate diagnostic radiography programs to improve student confidence levels and increase their ability to link theory to practice
Functional Varying-Coefficient Cox Model and Its Application
Full text linkWhen data become increasingly complex, desirable models are required to be more flexible for analyzing survival data. Building upon the existing functional Cox model, we introduce a novel functional varying-coefficient Cox model and the corresponding estimation algorithms are proposed in this article. The proposed model can simultaneously handle survival data with varying-coefficient covariates and functional covariates, thereby significantly enhancing the adaptability of survival models. The model performance is evaluated by simulation studies, and a real application using Alzheimer’s Disease Neuroimaging Initiative (ADNI) data is used to illustrate the practicality of the proposed model
Coping during the COVID-19 pandemic: insights from a qualitative study of organizational resilience in an English substance use support service
Full text linkIntroduction : The COVID-19 pandemic posed unprecedented challenges to health and care services, including substance use support, necessitating adaptations to maintain operational continuity. A lack of research exists into the factors that helped substance use services cope and maintain provision. This study aimed to elucidate the organizational resilience factors that assisted a substance use support service in sustaining operations and adapting during the COVID-19 pandemic. Theory : The study draws on recent conceptual and theoretical developments in the study of organizational resilience, examining findings primarily through the lens of bounce-back and bounce-forward resilience, and Duchek’s three-stage framework. Method : Participants were 36 staff members working for (n = 28) or in partnership with (n = 8) an organization delivering substance use support services across an area of northern England. A multi-method qualitative approach, including digital timelines (n = 19), in-depth interviews (n = 18), and five focus groups (n = 17), was employed. Timeline text was treated as qualitative text-based data. Interviews and focus groups were recorded and transcribed prior to coding. Data underwent Framework Analysis. Results : Seven themes were identified: 1) pre-existing relationships and effective multiagency working; 2) prioritization of service delivery; 3) development and implementation of guidance and protocols; 4) autonomy, devolution, and deference to expertise; 5) effective communication, regular meetings, and coordinated decision-making; 6) allowing flexibility and creativity; and 7) development of new and innovative approaches to facilitate the pandemic response. Discussion : This study identifies resilience factors that substance use and other support organizations should focus on in preparation for potential future crises, to minimise adverse impacts on vulnerable populations
Rescaling of distance judgments with geometric and contextual changes
Full text linkGrid cells have been identified in the entorhinal cortex of rodents and humans, as well as other mammals. In rodents, these “distance computing” neurons exhibit altered firing fields in response to environmental manipulations, including changes to geometry or specific contextual cues (e.g., color). The current study investigated whether these neurophysiological observations in rodents could predict human behavior in a distance judgment task under various environmental manipulations. Participants (n = 51) completed 22 trials involving distance traversal, memorisation, and distance replication across five experimental conditions: control (no manipulation), contextual manipulation (novel environment), and geometric manipulations (local expansion and contraction; global expansion and contraction). Results demonstrated that environmental expansions led to significant overestimations in distance judgments, consistent with rodent grid cell data. Global geometric manipulations yielded significant overestimations compared to the control condition. For the local manipulations, judgments were least accurate when made in the vicinity of the local manipulation. These behavioral patterns are consistent with localized deformations in spatial representations, as would be predicted from rodent grid cell studies. As hypothesized, changes to the environmental context (the novel environment condition) also resulted in significant distance overestimations. In conclusion, environmental manipulations influenced the accuracy of human distance judgments in a manner paralleling the firing field changes observed in rodent grid cells under similar environmental alterations. These findings demonstrate behavioral parallels between human distance estimation and rodent grid cell responses to environmental manipulations, suggesting possible commonalities in spatial processing across species