Best-fit Values Research Articles

Can a pseudoscalar with a mass of 365 GeV in two-Higgs-doublet models explain the CMS [formula omitted] excess?

We investigate the recently reported tt¯ excess by the CMS Collaboration within the framework of conventional Two-Higgs-Doublet Models (2HDMs). Considering all four types (I, II, X, and Y), we perform a comprehensive parameter space scan using the best-fit values for a pseudoscalar boson A: MA=365 GeV, ΓA/MA=2%, and tan⁡β=1.28. Theoretical requirements and experimental constraints are systematically applied, including conditions from a bounded-below scalar potential, vacuum stability, unitarity, perturbativity, Flavor-Changing Neutral Currents (FCNCs), and direct searches at high-energy colliders. Our analysis shows that perturbativity imposes upper bounds of around 723 GeV on MH± and MH. FCNC constraints exclude all viable parameter space in Types II and Y, while a small region persists in Types I and X, but this region is ultimately ruled out by recent tt¯Z measurements by the ATLAS and CMS Collaborations at the LHC. We conclude that conventional 2HDMs alone cannot accommodate a pseudoscalar boson that explains the observed tt¯ excess within viable parameter space. However, incorporating toponium effects in the background fit could potentially alter this conclusion.

The ultraviolet luminosity function of star-forming galaxies between redshifts of 0.4 and 0.6

Abstract We combine ultraviolet imaging of the 13H survey field, taken with the XMM-Newton Optical Monitor telescope (XMM-OM) and the Neil Gehrels Swift Observatory Ultraviolet and Optical Telescope (UVOT) in the UVM2 band, to measure rest-frame ultraviolet 1,500 Å luminosity functions of star-forming galaxies with redshifts z between 0.4 and 0.6. In total the UVM2 imaging covers a sky area of 641 arcmin2, and we detect 273 galaxies in the UVM2 image with 0.4 < z < 0.6. The luminosity function is fit by a Schechter function with best-fit values for the faint end slope $\alpha =-1.8^{+0.4}_{-0.3}$ and characteristic absolute magnitude $M^{*} = -19.1^{+0.3}_{-0.4}$. In common with XMM-OM based studies at higher redshifts, our best-fitting value for M* is fainter than previous measurements. We argue that the purging of active galactic nuclei from the sample, facilitated by the co-spatial X-ray survey carried out with XMM-Newton is important for the determination of M*. At the brightest absolute magnitudes (M1500 < −18.5) the average UV colour of our galaxies is consistent with that of minimal-extinction local analogues, but the average UV colour is redder for galaxies at fainter absolute magnitudes, suggesting that higher levels of dust attenuation enter the sample at absolute magnitudes somewhat fainter than M*.

Improved precision on 2–3 oscillation parameters using the synergy between DUNE and T2HK

A high-precision measurement of ∆m312\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\Delta {m}_{31}^2 $$\\end{document} and θ23 is inevitable to estimate the Earth’s matter effect in long-baseline experiments which in turn plays an important role in addressing the issue of neutrino mass ordering and to measure the value of CP phase in 3ν framework. After reviewing the results from the past and present experiments, and discussing the near-future sensitivities from the IceCube Upgrade and KM3NeT/ORCA, we study the expected improvements in the precision of 2–3 oscillation parameters that the next-generation long-baseline experiments, DUNE and T2HK, can bring either in isolation or combination. We highlight the relevance of the possible complementarities between these two experiments in obtaining the improved sensitivities in determining the deviation from maximal mixing of θ23, excluding the wrong-octant solution of θ23, and obtaining high precision on 2–3 oscillation parameters, as compared to their individual performances. We observe that for the current best-fit values of the oscillation parameters and assuming normal mass ordering (NMO), DUNE + T2HK can establish the non-maximal θ23 and exclude the wrong octant solution of θ23 at around 7σ C.L. with their nominal exposures. We find that DUNE + T2HK can improve the current relative 1σ precision on sin2θ23∆m312\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\left(\\Delta {m}_{31}^2\\right) $$\\end{document} by a factor of 7 (5) assuming NMO. Also, we notice that with less than half of their nominal exposures, the combination of DUNE and T2HK can achieve the sensitivities that are expected from these individual experiments using their full exposures. We also portray how the synergy between DUNE and T2HK can provide better constraints on (sin2θ23–δCP) plane as compared to their individual reach.

Characterisation of the stellar wind in Cyg X-1 via modelling of colour-colour diagrams

Context. Cygnus X-1 (Cyg X-1) is a high-mass X-ray binary where accretion onto the black hole (BH) is mediated by the stellar wind from the blue supergiant companion star HDE 226868. Due to its inclination, the system is a perfect laboratory to study the not yet well-understood stellar wind structure. In fact, depending on the position of the BH along the orbit, X-ray observations can probe different layers of the stellar wind. Deeper wind layers can be investigated at superior conjunction (i.e. null orbital phases). Aims. We aim to characterise the stellar wind in the Cyg X-1/HDE 226868 system, analysing one passage at superior conjunction covered by XMM-Newton during the ‘Cyg X-1 Hard state Observations of a Complete Binary Orbit in X-rays’ (CHOCBOX) campaign. Methods. To analyse the properties of the stellar wind, we computed colour-colour diagrams. Since X-ray absorption is energy-dependent, colour indices provide information on the parameters of the stellar wind, such as the column density, NH, w, and the covering factor, fc. We fitted colour-colour diagrams with models that include both a continuum and a stellar wind component. We used the kernel density estimation method to infer the unknown probability distribution of the data points in the colour-colour diagram, and selected the model corresponding to the highest likelihood. In order to study the temporal evolution of the wind around superior conjunction, we extracted and fitted time-resolved colour-colour diagrams. Results. We found that the model that best describes the shape of the colour-colour diagram of Cyg X-1 at superior conjunction requires the wind to be partially ionised. The shape of the colour-colour diagram strongly varies during the analysed observation, due to concurrent changes of the mean NH, w and the fc of the wind. Our results suggest the existence of a linear scaling between the rapid variability amplitude of NH, w (on timescales between 10 s and 11 ks) and its long-term variations (on timescales > 11 ks). Using the inferred best-fit values, we estimated the stellar mass loss rate to be ∼7 × 10−6 M⊙ yr−1 and the clumps to have a characteristic mass of ∼1017 g.

Development of the compliance with mechanical ventilator scale in: A validity and reliability study.

Mechanical ventilation is a widely used treatment modality in cardiac surgery intensive care units (ICUs), especially for patients requiring respiratory support during postoperative management. The aim of this study was to define the process of developing a scale to assess adherence to mechanical ventilation in cardiac surgery patients and to assess the validity and reliability of the scale. This is a scale development and scale validation study. The study was conducted with 222 patients between April and September 2023. In the first stage, face-to-face interviews were conducted with seven nurses. Based on the literature review and content analysis of the interviews, the researchers created an item pool. In the second stage, the validity and reliability of the Mechanical Ventilator Compliance Scale in cardiac surgery patients were assessed. The scale was developed to be used by nurses working in cardiac surgery ICUs. The first 36-item scale was subjected to content validity assessment by 14 experts. It was revised according to the experts' feedback and a content validity criterion of 0.83 was obtained. Confirmatory factor analysis showed good fit values for the scale (χ2/SD = 3.09, GFI = 0.90, AGFI = 0.90, CFI = 0.91, RMSEA = 0.06, and RMR = 0.07). Test-retest analysis to assess the reliability of the scale showed good agreement between responses over time (ICC: 0.932; p < .001). Cronbach's alpha values for the scale and its subscales, behavioural and physical responses were 0.956, 0.949 and 0.912, respectively. The study findings indicate that the scale is a reliable and valid tool for assessing mechanical ventilator compliance in cardiac surgery patients. This study provides nurses in cardiac surgery intensive care units with a measurement tool to objectively assess patients' compliance with mechanical ventilation therapy. The scale provides more reliable results by preventing subjective judgement and estimation in patient assessment.

Statistical and observation comparison of Weyl-type f(Q,T) models with the ΛCDM paradigm

We study the f(Q,T) gravity in the framework of Weyl geometry (known as Weyl-type f(Q,T) gravity), where Q denotes the non-metricity scalar, and T denotes the energy-momentum tensor trace. In this work, we consider the f(Q,T) model, which is defined as f(Q,T)=αQm+1+β6κ2T and investigating two scenarios: (I) m=0 (linear model) and (II)m≠0 (nonlinear model). For both scenarios, we find the explicit solution for the field equations by using the barotropic equation of state as p=wρ, where w is the equation-of-state (EoS) parameter. Further, we study the obtained solutions statistically using the Pantheon+ (Without SHOES Calibrated) dataset with 1701 data points. For both models, the best-fit values of model parameters for 1−σ and 2−σ confidence level. The higher Hubble constant values in both models emphasize the presence of Tension. We statistically compare our models to the ΛCDM model using χmin2, χred2, AIC, ΔAIC, BIC and ΔBIC. We also examine cosmological parameters such as deceleration and EoS parameters to determine the current acceleration expansion of the Universe. Furthermore, we test our model using Om diagnostic and compare it to the ΛCDM model to determine its dark energy profile. Finally, we draw the conclusion that statistically speaking, both linear and nonlinear models show good compatibility with the ΛCDM model.

Electrical conductance study of Schiff base in different solvents and temperatures: DFT calculation

The electrical conductivities of the N-(2-chlorobenzylidene)benzylamine (NCB) as Schiff bases (SB) compound in water and methanol were studied in different temperatures, the mixtures of methanol and water studied in various percentages of methanol at 298 K. Initially, the relationship between equivalent conductivity and the square root of molar concentration was plotted to find electrolyte types using Kohlrausch equations. The plot indicates that NCB was weakly associated with water, methanol, and mixtures. Lee-Wheaton equation treated the experimental results of symmetrical electrolytes (1:1) to calculate the conductivity confines: equivalent conductance at infinite dilution Λₒ, association constant KA, and the main distance between ions in solution (R) at best-fit values of (ϬΛ). Thermodynamic quantities for the ion association reaction (∆Go, ∆Ho and ∆So) have been measured. Also, the theoretical calculation was used to optimize the energy of the molecule in the gas phase then measured many descriptors by using (AM1, PM3) then DFT. In addition, recalculated the optimization energy in water, and methanol. After theoretical calculation and analysis, it was found that the Λₒ value is related to the molecular volume of the system (molecules assembled in the solvent). As the molecular volume increases, the Λₒ value decreases due to association. KEY WORDS: Schiff bases, Electrical conductivities, Lee-Wheaton equation, Thermodynamic parameter, DFT Bull. Chem. Soc. Ethiop. 2025, 39(1), 177-187. DOI: https://dx.doi.org/10.4314/bcse.v39i1.15

Thermodynamic study of pyridoxine in different solvents and temperatures: DFT study

The equivalent conductivities (Λ) of B6 vitamin (pyridoxine) in HշՕ and MeOH were measured at different temperatures between 293 to 313 K, as well as in mixtures of H₂O and MeOH at percentages of 10, 20, 30, 40, and, 50% MeOH at 310 K. All the practical results were mathematically processed using the Lee Wheaton equation, which is applied to the derived conductivity of electrolytes with a similar composition (1:1). This equation calculates various conductivity components, including the equivalent conductance at infinite dilution (Λₒ), the ionic conductivity, the distance between ions (R), and also the constant of ionic aggregation (Ka) at best-fit values of (ϬΛ). The values of these parameters differed from one solvent to another depending on the molecular interactions in the solution and the physical properties of the solvents, such as viscosity and dielectric constant. Finally, thermodynamic quantities for the ion association reaction (ΔG°, ΔH°, and ΔS°) were also studied. Density functional theory (DFT) calculations (B3LYP/6-31G (d,p)) were employed to analyze vitamin B6 in the gas phase and diverse solvents. Three different continuum methods, namely AM1, PM3, and HF, were utilized, followed by DFT. The final method was utilized to explore the effects on its characteristics. KEY WORDS: Electrical conductivity, Lee-Wheaton equation, Theoretical chemistry, DFT. Bull. Chem. Soc. Ethiop. 2025, 39(1), 165-176. DOI: https://dx.doi.org/10.4314/bcse.v39i1.14

Psychometric evaluation of the Turkish version of the nurses' perception of the gap between knowledge and practice scale.

Progress in the nursing profession and clinical decision-making are largely sustained by the coherence between theory and practice. The quality of healthcare provided by nurses and patient outcomes are adversely impacted by the gap between knowledge and practice. Measurement tools used to assess nurses' perceptions of this gap are inadequate in Türkiye. This research aimed to adapt the nurses' perception of the gap between knowledge and practice scale into Turkish and to evaluate its reliability and validity. The study, in which a methodological design was employed, was conducted with 406 nurses between March and June 2022. A descriptive information form and the nurses' perception of the gap between knowledge and practice scale (NPGKPS) were employed to gather data. The validity study included content and construct validity analyses, and the reliability study included item analysis, split-half test, and Cronbach alpha coefficients. The scale had 35 items and four dimensions, which explained 54.65% of the total variance. The goodness of fit values, which were found following a confirmatory factor analysis, were estimated as follows: CMIN = 1808.984, DF = 512, CMIN/DF = 3.533, IFI = 0.89, TLI = 0.87, RFI = 0.83, CFI = 0.89, RMSEA = 0.079, and NFI = 0.86. Cronbach's alpha coefficient of the total scale was estimated as 0.95 and it was in the range of 0.84 to 0.93 for four factors. In conclusion, the nurses' perception of the gap between knowledge and practice scale was a reliable and valid measure which could be applied to Turkish society.

Constraining the entropy corrected (m, n)-type pilgrim dark energy in fractal cosmology

This study explores the impact of introducing particle and future event horizon as infrared (IR) cutoff on (m, n)-type entropy corrected versions of pilgrim dark energy. We investigate (m, n)-type power-law entropy corrected pilgrim dark energy in a flat fractal platform by considering a non-interacting scenario with cold dark matter. Then, our focus shifts to (m, n)-type logarithmic entropy corrected pilgrim dark energy. We derive the evolution of some relevant cosmological parameters and cosmological planes. Finally, we constrain the model parameters using H(z)+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$H(z)+$$\\end{document}BAO combined observational data from the DA and BAO methods. For statistical analysis, we apply the χ2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\chi ^2$$\\end{document}-minimization technique (equivalent to the maximum likelihood method) to estimate the best-fit value of the model parameters. We incorporate public Cosmo Hammer (EMCEE) Python package code to perform the MCMC method. Finally, we display the plot of cosmological parameters and cosmological plane and analyze the triangular contour plot by using the optimal values of the model parameters.

Electronic Health (eHealth) Literacy and Self-Care Behaviors—Results from a Survey of University Students in a Developing Country

eHealth literacy (eHL) is directly linked to disease prevention, health promotion, and improved healthcare outcomes. The objectives of this study are to assess undergraduate university students’ knowledge and perceived skills of finding, appraising, and applying electronic health information to health-related problems, as well as to assess the association of eHL with physical, psychological, and emotional self-care. Methods: The measurement model, comprising four correlated factors based on the 28 valid items from two reliable and valid tests, the ‘eHealth literacy scale (eHEALS)’ and ‘the self-care assessment tool (SCAT)’, was estimated using confirmatory factor analysis (CFA) among a sample of 1557 undergraduate university students in Pakistan. Results: The mean value of the eHEALS ranges between 2.90 and 3.33, indicating that the majority of the respondents had moderate levels of eHL skills. Female respondents and respondents from urban areas have greater levels of perceived eHL skills compared with their male and rural counterparts. The CFA model fit indices show that the goodness of fit values are acceptable: x2 = 7.727, p = 0.000; RMSEA = 0.065; TLI = 0.930, CFI = 0.936, IFI = 0.936, GFI = 0.890, NFI = 0.928, RFI = 0.920, PGFI = 0.754. Conclusion: Electronic health (eHealth) literacy has a strong positive association with physical, psychological, and emotional self-care. However, perceived eHL skills among undergraduate university students are moderate, making them potentially susceptible to health risks. Implications: Our study has several practical implications. Its findings can be used to devise eHealth literacy programs for developing relevant skills among undergraduate university students based on their identified needs.

Bouncing universe scenarios in an extended gravitational framework involving curvature-matter coupling

Exploration of bouncing cosmic models in modified theories has gained much popularity in modern cosmology. This paper explores the Lagrangian function of a new theory namely F(R,Lm,T) framework by taking four renowned cosmic bouncing models, i.e., the exponential bounce, oscillatory bounce scenario, power law, and matter bouncing. Our primary objective is to fix the form of F(R,Lm,T) function for each model and investigate which kinds of reconstructed Lagrangian function have potential of regenerating bouncing scenario in terms of analytical form. It is seen that except power law model, the analytical solutions are conceivable only for certain cases of these bouncing models. For power law bounce, different cases of Lagrangian function may be rebuilt analytically while for some other bouncing scenarios, it is found that particular solutions are not always attainable and hence only the complimentary solutions can be explored. Further, we examine the behavior of energy constraints and stability of these analytically formed bouncing solutions. Additionally, we determine that the dark energy phase in F(R,Lm,T) gravity is compatible with the experimental data of BAO+Sne-Ia+CMB+H(z) and it is shown that cosmic bounce can be produced with dark energy eras in this gravity. We also present some constraints on the model parameters with Hubble parameter values and ΛCDM to determine the best-fit values of model via least square and reduced chi-squares methods. It is concluded that matter bounce model is the best fitted with the observational data set as well as ΛCDM model because it has least value of χm2.

A-sloth reveals the nature of the first stars

ABSTRACT The first generation of stars (Pop III) are too dim to be observed directly and probably too short-lived to have survived for local observations. Hence, we rely on simulations and indirect observations to constrain the nature of the first stars. In this study, we calibrate the semi-analytical model a-sloth (Ancient Stars and Local Observables by Tracing Haloes), designed for simulating star formation in the early Universe, using a likelihood function based on nine independent observables. These observables span Milky Way-specific and cosmologically representative variables, ensuring a comprehensive calibration process. This calibration methodology ensures that a-sloth provides a robust representation of the early Universe’s star formation processes, aligning simulated values with observed benchmarks across a diverse set of parameters. The outcome of this calibration process is best-fitting values and their uncertainties for 11 important parameters that describe star formation in the early Universe, such as the shape of the initial mass function (IMF) of Pop III stars or escape fractions of ionizing photons. Our best-fitting model has a Pop III IMF with a steeper slope, dN/d$M \propto M^{-1.77}$, than the log-flat models often proposed in the literature, and also relatively high minimum and maximum masses, $M_{\rm min} = 13.6~\, \mathrm{M}_\odot$ and $M_{\rm max} = 197~\, \mathrm{M}_\odot$. However, we emphasize that the IMF-generating parameters are poorly constrained and, e.g. the IMF slope could vary from log-flat to Salpeter. We also provide data products, such as delay time distribution, bubble size distributions for ionizing and metal-enriched bubbles at high redshift, and correlation plots between all 11 input parameters. Our study contributes to understanding the formation of early stars through a-sloth, providing valuable insights into the nature of Pop III stars and the intricate processes involved in the early Universe’s star formation.

Construction and validation of a nomogram prediction model for the catheter-related thrombosis risk of central venous access devices in patients with cancer: a prospective machine learning study.

Central venous access devices (CVADs) are integral to cancer treatment. However, catheter-related thrombosis (CRT) poses a considerable risk to patient safety. It interrupts treatment; delays therapy; prolongs hospitalisation; and increases the physical, psychological and financial burden of patients. Our study aims to construct and validate a predictive model for CRT risk in patients with cancer. It offers the possibility to identify independent risk factors for CRT and prevent CRT in patients with cancer. We prospectively followed patients with cancer and CVAD at Xiangya Hospital of Central South University from January 2021 to December 2022 until catheter removal. Patients with CRT who met the criteria were taken as the case group. Two patients with cancer but without CRT diagnosed in the same month that a patient with cancer and CRT was diagnosed were selected by using a random number table to form a control group. Data from patients with CVAD placement in Qinghai University Affiliated Hospital and Hainan Provincial People's Hospital (January 2023 to June 2023) were used for the external validation of the optimal model. The incidence rate of CRT in patients with cancer was 5.02% (539/10 736). Amongst different malignant tumour types, head and neck (9.66%), haematological (6.97%) and respiratory (6.58%) tumours had the highest risks. Amongst catheter types, haemodialysis (13.91%), central venous (8.39%) and peripherally inserted central (4.68%) catheters were associated with the highest risks. A total of 500 patients with CRT and 1000 without CRT participated in model construction and were randomly assigned to the training (n = 1050) or testing (n = 450) groups. We identified 11 independent risk factors, including age, catheterisation method, catheter valve, catheter material, infection, insertion history, D-dimer concentration, operation history, anaemia, diabetes and targeted drugs. The logistic regression model had the best discriminative ability amongst the three models. It had an area under the curve (AUC) of 0.868 (0.846-0.890) for the training group. The external validation AUC was 0.708 (0.618-0.797). The calibration curve of the nomogram model was consistent with the ideal curve. Moreover, the Hosmer-Lemeshow test showed a good fit (P > 0.05) and high net benefit value for the clinical decision curve. The nomogram model constructed in this study can predict the risk of CRT in patients with cancer. It can help in the early identification and screening of patients at high risk of cancer CRT.

Observational Constraints and Cosmographic Analysis of f(T,TG) Gravity and Cosmology

We perform observational confrontation and cosmographic analysis of f(T,TG) gravity and cosmology. This higher-order torsional gravity is based on both the torsion scalar, as well as on the teleparallel equivalent of the Gauss–Bonnet combination, and gives rise to an effective dark-energy sector which depends on the extra torsion contributions. We employ observational data from the Hubble function and supernova Type Ia Pantheon datasets, applying a Markov chain Monte Carlo sampling technique, and we provide the iso-likelihood contours, as well as the best-fit values for the parameters of the power-law model, an ansatz which is expected to be a good approximation of most realistic deviations from general relativity. Additionally, we reconstruct the effective dark-energy equation-of-state parameter, which exhibits a quintessence-like behavior, while in the future the Universe enters into the phantom regime, before it tends asymptotically to the cosmological constant value. Furthermore, we perform a detailed cosmographic analysis, examining the deceleration, jerk, snap, and lerk parameters, showing that the transition to acceleration occurs in the redshift range 0.52≤ztr≤0.89, as well as the preference of the scenario for quintessence-like behavior. Finally, we apply the Om diagnostic analysis to cross-verify the behavior of the obtained model.

Evaluating the Application of the SIR Model to a Localized Population

Objective Using data collected from the Johns Hopkins COVID-19 Repository, I investigated the reliability of the SIR (Susceptible-Infected-Removed) model. Summary of Background Data Modern pandemic responses have evolved into effective defenses when implemented correctly but present issues in epidemiological modeling efforts. Intervention strategies such as quarantining and masking limit population size (N), which affects the accuracy of modeling population-based rate systems especially in highly transmissible diseases. Methods I begin by reviewing the SIR model retroactively to the initial SARS-CoV-2 Wuhan strain. I compared the parameters available in the published literature (N = 2,717,000, β = 2, γ = 1/14) to the best-fitting SIR-yielded values by minimizing the root mean squared error function. Subsequently, I evaluated its predictive capabilities on the Delta variant using early surge data, which was later compared against a retroactive analysis. Results Using a least-squares error best-fit analysis allowed me to retroactively define remarkably accurate model parameters for the Wuhan waves. Parameters including N = 730, β = 0.46, γ = 0.043 in the first wave and N = 11,200, β = 0.198, γ = 0.07 in the second reflected effective intervention strategies. I show it is an effective predictive tool regarding the Delta variant, yielding parameters N = 50,900, β = 0.87, γ = 1/3.7 that proved accurate when compared with parameters from a full retroactive analysis (N = 60,000, β = 0.94, γ = 1/3.6). Conclusion The similarity of the yielded parameters in my results supports the SIR model’s utility in epidemiological monitoring of high-transmissibility, low-mortality outbreaks vis-à-vis various containment measures.

Cosmological model with linear equation of state parameter in f(R,Lm) gravity

In this paper, we examine the universe's expansion in f(R,Lm) gravity for a particular form of f(R,Lm)=R2+Lmn. The field equations for flat FLRW metric with matter Lagrangian Lm=ρ are derived. Hubble parameter in terms of red-shift(z) are derived using the linear form of Equation of State (EoS) parameter ω=w0+w1z. By using Bayesian statistical techniques based on χ2-minimization technique, we have obtained the best fit values of the model parameters of this model for cosmic chronometer and supernovae Pantheon datasets. The evolution of the equation of state parameter(ω), energy density (ρ), pressure (p), cosmographic parameters, and the impact of the energy conditions with best-fit values of the model parameters are all thoroughly examined. We have also analyze Om diagnostic's behaviour and determine the present age of universe for this model.

Accelerating universe in [formula omitted] gravity

This paper investigates the dynamics of cosmic expansion within the framework of f(R,Lm) gravity, focusing on the late-time behavior of the universe modeled as a flat Friedmann–Lemaître–Robertson–Walker spacetime. We derive an analytical solution for the field equations and employ advanced statistical techniques, including the Markov Chain Monte Carlo (MCMC) method, to determine best-fit values for the key cosmological parameters, such as the Hubble parameter and the deceleration parameter. Our findings reveal a transition from a decelerating to an accelerating phase of cosmic expansion, aligning closely with observational data as in the ΛCDM model. The analysis of energy conditions indicates that the strong energy condition is violated, in keeping with the current accelerated expansion of the universe and the nature of dark energy. By elucidating the quintessence behavior of our model through statefinder and Om diagnostics, this study contributes to a deeper understanding of cosmic evolution and the fundamental forces at play. The insights gained pave the way for future research into alternative cosmological models, inviting further exploration of the mysteries surrounding dark energy and the ultimate fate of the universe.

Computation of bulk viscous pressure with observational constraints via scalar field in the General relativity and [formula omitted] gravity

The present article deals with the isotropic cosmological model of f(Q) gravity filled with bulk viscous fluid, where Q is the non-metricity term and it is responsible for the gravitational interaction. Aside from the tachyon and quintessence scalar fields, the modified Einstein’s field equations have been resolved through the application of the power law form of the expansion. In this model, the Markov chain Monte Carlo (MCMC) analysis method has been utilized to obtained the best-fit value of the model parameter and it confirms that the model satisfies the recent observational data. We have also examined the EoS parameter for bulk viscosity in these cosmological contexts and it has been determined that ωeff will be located in the phantom region. The correspondence between bulk pressure and the reconstructed ωrec,Q in f(Q) gravity has also been addressed. In the presence of holographic Ricci dark energy, the reconstructed f(Q) gravity yields a transition from the quintessence era into phantom era.

Spectral Calculations of 3D Radiation Magnetohydrodynamic Simulations of Super-Eddington Accretion onto a Stellar-mass Black Hole

We use the Athena++ Monte Carlo (MC) radiation transfer module to postprocess simulation snapshots from nonrelativistic Athena++ radiation magnetohydrodynamic (RMHD) simulations. These simulations were run using a gray (frequency-integrated) approach but were also restarted and ran with a multigroup approach that accounts for Compton scattering with a Kompaneets operator. These simulations produced moderately super-Eddington accretion rates onto a 6.62 M ⊙ black hole. Since we only achieve inflow equilibrium out to 20–25 gravitational radii, we focus on the hard X-ray emission. We provide a comparison between the MC and RMHD simulations, showing that the treatment of Compton scattering in the gray RMHD simulations underestimates the gas temperature in the funnel regions above and below the accretion disk. In contrast, the restarted multigroup snapshots provide a treatment for the radiation field that is more consistent with the MC calculations, and result in postprocessed spectra with harder X-ray emission compared to their gray snapshot counterparts. We characterize these MC postprocessed spectra using commonly employed phenomenological spectral fitting models. We also attempt to fit our MC spectra directly to observations of the ultraluminous X-ray source (ULX) NGC 1313 X-1, finding best-fit values that are competitive to phenomenological model fits, indicating that first principle models of super-Eddington accretion may adequately explain the observed hard X-ray spectra in some ULX sources.