13 research outputs found
A New Cosmological Model: Exploring the Evolution of the Universe and Unveiling Super-Accelerated Expansion
In this paper, we present a cosmological model designed to study the
evolution of the universe based on a new parametrization of the deceleration
parameter. The model considers a spatially flat, homogeneous, and isotropic
Friedmann-Lema\^itre-Robertson-Walker (FLRW) universe filled with radiation,
dark matter (DM), and dark energy (DE). We derive the Friedmann equations and
the energy conservation equation for the universe, accounting for separate
conservation equations for radiation, DM, and DE. Our proposed deceleration
parameter is given by a formula involving constants , ,
, , , , and . which we
subsequently fit to observational data. To assess the model's viability, we
compare it with a diverse range of observational data, including cosmic
chronometers, type Ia supernovae, baryon acoustic oscillations, and cosmic
microwave background measurements. Employing the chi-square statistic and a
Markov Chain Monte Carlo (MCMC) method, we estimate the best-fit values for the
free parameters and investigate the constraints imposed by observational data
on the model. Our results indicate that our cosmological model provides an
excellent fit to the observed data and exhibits a remarkable agreement with the
standard CDM paradigm at higher redshifts. However, the most
intriguing discovery lies in the model's prediction of a super-accelerated
expansion in the distant future, in contrast to the de Sitter phase predicted
by CDM. This implies the presence of dark energy driving the
universe's accelerated expansion. These findings suggest that our proposed
cosmological model offers a compelling alternative to the CDM
paradigm, shedding new light on the nature of dark energy and the future fate
of the cosmos.Comment: 10 figures, 2 table
Exploring Tidal Force Effects and Shadow Constraints for Schwarzschild-like Black Hole in Starobinsky-Bel-Robinson Gravity
The current manuscript deals with the tidal force effects, geodesic
deviation, and shadow constraints of the Schwarzschild-like black hole
theorised in Starobinsky-Bel-Robinson gravity exhibiting M-theory
compactification. In the current analysis, we explore the radial and angular
tidal force effects on a radially in-falling particle by the central black
hole, which is located in this spacetime. We also numerically solve the
geodesic deviation equation and study the variation of the geodesic separation
vector with the radial coordinate for two nearby geodesics using suitable
initial conditions. All the obtained results are tested for Sag A* and M87* by
constraining the value of the stringy gravity parameter using the
shadow data from the event horizon telescope observations. All the results are
compared with Schwarzschild black hole spacetime. In our study, we found that
both the radial and angular tidal forces experienced by a particle switch their
initial behaviour and turn compressive and stretching, respectively, before
reaching the event horizon. The geodesic deviation shows an oscillating trend
as well for the chosen initial condition. For the constrained value of ,
we see that the spacetime geometry generated by Sag A* and M87* is effectively
same for both Schwarzschild and Starobinsky-Bel-Robinson black hole.
Furthermore, we also calculated the angular diameter of the shadow in
Starobinsky-Bel-Robinson black hole and compared with the Schwarzschild black
hole. It is observed that the angular diameter of shadow for M87* and Sgr A* in
Starobinsky-Bel-Robinson black hole is smaller than the Schwarzschild black
hole. The calculated results satisfy the event horizon telescope observational
constraints. Finally, we have concluding remarks.Comment: 12 pages, 18 figures, accepted for publication in European Physical
Journal
Machine Reading Comprehension using Case-based Reasoning
We present an accurate and interpretable method for answer extraction in
machine reading comprehension that is reminiscent of case-based reasoning (CBR)
from classical AI. Our method (CBR-MRC) builds on the hypothesis that
contextualized answers to similar questions share semantic similarities with
each other. Given a target question, CBR-MRC retrieves a set of similar
questions from a memory of observed cases and predicts an answer by selecting
the span in the target context that is most similar to the contextualized
representations of answers in the retrieved cases. The semi-parametric nature
of our approach allows CBR-MRC to attribute a prediction to the specific set of
cases used during inference, making it a desirable choice for building reliable
and debuggable QA systems. We show that CBR-MRC achieves high test accuracy
comparable with large reader models, outperforming baselines by 11.5 and 8.4 EM
on NaturalQuestions and NewsQA, respectively. Further, we also demonstrate the
ability of CBR-MRC in identifying not just the correct answer tokens but also
the span with the most relevant supporting evidence. Lastly, we observe that
contexts for certain question types show higher lexical diversity than others
and find CBR-MRC to be robust to these variations while performance using
fully-parametric methods drops.Comment: 9 pages, 2 figure
Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries
Abstract
Background
Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres.
Methods
This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries.
Results
In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia.
Conclusion
This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries
Exploring tidal force effects and shadow constraints for Schwarzschild-like black hole in Starobinsky–Bel-Robinson gravity
Abstract The current manuscript deals with the tidal force effects, geodesic deviation, and shadow constraints of the Schwarzschild-like black hole theorised in Starobinsky–Bel-Robinson gravity exhibiting M-theory compactification. In the current analysis, we explore the radial and angular tidal force effects on a radially in-falling particle by the central black hole, which is located in this spacetime. We also numerically solve the geodesic deviation equation and study the variation of the geodesic separation vector with the radial coordinate for two nearby geodesics using suitable initial conditions. All the obtained results are tested for Sag A* and M87* by constraining the value of the stringy gravity parameter β using the shadow data from the event horizon telescope observations. All the results are compared with Schwarzschild black hole spacetime. In our study, we found that both the radial and angular tidal forces experienced by a particle switch their initial behaviour and turn compressive and stretching, respectively, before reaching the event horizon. The geodesic deviation shows an oscillating trend as well for the chosen initial condition. For the constrained value of β , we see that the spacetime geometry generated by Sag A* and M87* is effectively same for both Schwarzschild and Starobinsky–Bel-Robinson black hole. Furthermore, we also calculated the angular diameter of the shadow in Starobinsky–Bel-Robinson black hole and compared with the Schwarzschild black hole. It is observed that the angular diameter of shadow for M87* and Sgr A* in Starobinsky–Bel-Robinson black hole is smaller than the Schwarzschild black hole. The calculated results satisfy the event horizon telescope observational constraints
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Stroke is the fifth leading cause of death in the United States and a major cause of severe disability worldwide. Yet, recognizing the signs of stroke in an acute setting is still challenging and leads to loss of opportunity to intervene, given the narrow therapeutic window. A decision support system using artificial intelligence (AI) and clinical data from electronic health records combined with patients presenting symptoms can be designed to support emergency department providers in stroke diagnosis and subsequently reduce the treatment delay. In this article, we present a practical framework to develop a decision support system using AI by reflecting on the various stages, which could eventually improve patient care and outcome. We also discuss the technical, operational, and ethical challenges of the process
Using artificial intelligence for improving stroke diagnosis in emergency departments: a practical framework.
Stroke is the fifth leading cause of death in the United States and a major cause of severe disability worldwide. Yet, recognizing the signs of stroke in an acute setting is still challenging and leads to loss of opportunity to intervene, given the narrow therapeutic window. A decision support system using artificial intelligence (AI) and clinical data from electronic health records combined with patients\u27 presenting symptoms can be designed to support emergency department providers in stroke diagnosis and subsequently reduce the treatment delay. In this article, we present a practical framework to develop a decision support system using AI by reflecting on the various stages, which could eventually improve patient care and outcome. We also discuss the technical, operational, and ethical challenges of the process