38 research outputs found

    Bounds on graviton mass using weak lensing and SZ effect in galaxy clusters

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    In General Relativity (GR), the graviton is massless. However, a common feature in several theoretical alternatives of GR is a non-zero mass for the graviton. These theories can be described as massive gravity theories. Despite many theoretical complexities in these theories, on phenomenological grounds, the implications of massive gravity have been widely used to put bounds on graviton mass. One of the generic implications of giving a mass to the graviton is that the gravitational potential will follow a Yukawa-like fall off. We use this feature of massive gravity theories to probe the mass of graviton by using the largest gravitationally bound objects, namely galaxy clusters. In this work, we use the mass estimates of galaxy clusters measured at various cosmologically defined radial distances measured via weak lensing (WL) and Sunyaev-Zel'dovich (SZ) effect. We also use the model independent values of Hubble parameter H(z)H(z) smoothed by a non-parametric method, Gaussian process. Within 1σ1\sigma confidence region, we obtain the mass of graviton mg<5.9×1030m_g < 5.9 \times 10^{-30} eV with the corresponding Compton length scale λg>6.82\lambda_g > 6.82 Mpc from weak lensing and mg<8.31×1030m_g < 8.31 \times 10^{-30} eV with λg>5.012\lambda_g > 5.012 Mpc from SZ effect. This analysis improves the upper bound on graviton mass obtained earlier from galaxy clusters.Comment: 9 Pages, 3 Figures, 2 Tables, Accepted for publication in Physics Letters

    Examining Temporal Variation of the Fermi Coupling Constant using SNe Ia Light Curves

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    In standard model, the Fermi coupling constant, GFG_F, sets the strength of electroweak decay. We attempt an approach to constrain the temporal variation of the Fermi coupling constant GFG_F. To probe it, Type Ia supernovae (SNe Ia) light curves are being used as a source of reliable primordial nucleosynthesis events across the redshifts. We utilized studies suggesting that in the initial phase after the SNe Ia explosion, the electroweak decay of 56Ni56Co56Fe^{56}Ni \rightarrow ^{56}Co \rightarrow ^{56}Fe is the key contributor to powering the SNe Ia light curve. We hence used the Pan-STARRS supernovae catalog having 1169 supernovae light curves in gg, rr, ii, and zz spectral filters. The post-peak decrease in the apparent magnitude of light curves (in the rest frame of SNe) was related to the electroweak decay rate of primordial nucleosynthesis. Further, the decay rate relates to GFG_F. To keep the analysis independent of the cosmological model, we used the Hubble parameter measurement and a non-parametric statistical method, the Gaussian Process. Our study suggests a small yet finite temporal variation of GFG_F and puts a strong upper bound on the present value of the fractional change in the Fermi coupling constant i.e; G˙FGFz=01011yr1\dfrac{\dot G_F}{G_F}\big\rvert_{z=0} \approx 10^{-11} yr^{-1} using datasets spread over a redshift range 0<z<0.750<z<0.75.Comment: 14 pages, 7 figures, 1 tabl

    Strong lensing systems and galaxy cluster observations as probe to the cosmic distance duality relation

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    In this paper, we use large scale structure observations to test the cosmic distance duality relation (CDDR), DL(1+z)2/DA=η=1D_{\rm L}(1+z)^{-2}/D_{\rm A}=\eta=1 , with DLD_{\rm L} and DAD_{\rm A}, being the luminosity and angular diameter distances, respectively. In order to perform the test, the following data set are considered: strong lensing systems and galaxy cluster measurements (gas mass fractions). No specific cosmological model is adopted, only a flat universe is assumed. By considering two η(z)\eta(z) parametrizations, we obtained the validity of the CDDR within 1.5σ1.5\sigma which is in full agreement with other recent tests involving cosmological data. It is worth to comment that our results are independent of the baryon budget of galaxy clusters.Comment: 6 pages, two figs, one tabl

    Evaluation of coronary arteries in congenital heart disease in children : diagnostic comparison of electrocardiogram-gated and non-electrocardiogram-gated computed tomography cardiac angiograpy

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    Purpose: To compare the visualization and anatomy of coronary arteries in children (≤ 2 years) with congenital heart disease (CHD) on non-electrocardiogram (ECG)-gated and ECG-gated computed tomography angiography (CTA). Material and methods: In this retrospective study, approved by the Ethics Committee of our institute, evaluation of coronary arteries in CHD was performed in 40 children on non-ECG-gated CTA and in 42 children on ECG-gated CTA. The origin and course of the right coronary artery (RCA), left main coronary artery (LMCA), left anterior descending (LAD) artery, and left circumflex (LCX) artery were evaluated by 2 paediatric radiologists independently. Results: ECG-gated CT scans yielded increased (additional) visualization of all the coronary arteries, when compared to non-ECG-gated CT scans. The RCA, LMCA, LAD artery, and LCX artery were visualized in 47.5%, 62.5%, 55%, and 32.5% of children, respectively, on non-ECG-gated studies, while they were visualized in 64.3%, 92.8%, 80.9%, and 62% children, respectively, on ECG-gated studies. The coronary artery anatomical variations were also supplementarily detected more in the ECG-gated group (23.8%) than in the non-ECG gated group (2.5%). Conclusions: ECG-gated CT cardiac angiography studies yield enhanced diagnostic outcomes for the evaluation of the coronary arteries in comparison to non-ECG-gated studies

    The global burden of cancer attributable to risk factors, 2010-19 : a systematic analysis for the Global Burden of Disease Study 2019

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    Background Understanding the magnitude of cancer burden attributable to potentially modifiable risk factors is crucial for development of effective prevention and mitigation strategies. We analysed results from the Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 to inform cancer control planning efforts globally. Methods The GBD 2019 comparative risk assessment framework was used to estimate cancer burden attributable to behavioural, environmental and occupational, and metabolic risk factors. A total of 82 risk-outcome pairs were included on the basis of the World Cancer Research Fund criteria. Estimated cancer deaths and disability-adjusted life-years (DALYs) in 2019 and change in these measures between 2010 and 2019 are presented. Findings Globally, in 2019, the risk factors included in this analysis accounted for 4.45 million (95% uncertainty interval 4.01-4.94) deaths and 105 million (95.0-116) DALYs for both sexes combined, representing 44.4% (41.3-48.4) of all cancer deaths and 42.0% (39.1-45.6) of all DALYs. There were 2.88 million (2.60-3.18) risk-attributable cancer deaths in males (50.6% [47.8-54.1] of all male cancer deaths) and 1.58 million (1.36-1.84) risk-attributable cancer deaths in females (36.3% [32.5-41.3] of all female cancer deaths). The leading risk factors at the most detailed level globally for risk-attributable cancer deaths and DALYs in 2019 for both sexes combined were smoking, followed by alcohol use and high BMI. Risk-attributable cancer burden varied by world region and Socio-demographic Index (SDI), with smoking, unsafe sex, and alcohol use being the three leading risk factors for risk-attributable cancer DALYs in low SDI locations in 2019, whereas DALYs in high SDI locations mirrored the top three global risk factor rankings. From 2010 to 2019, global risk-attributable cancer deaths increased by 20.4% (12.6-28.4) and DALYs by 16.8% (8.8-25.0), with the greatest percentage increase in metabolic risks (34.7% [27.9-42.8] and 33.3% [25.8-42.0]). Interpretation The leading risk factors contributing to global cancer burden in 2019 were behavioural, whereas metabolic risk factors saw the largest increases between 2010 and 2019. Reducing exposure to these modifiable risk factors would decrease cancer mortality and DALY rates worldwide, and policies should be tailored appropriately to local cancer risk factor burden. Copyright (C) 2022 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license.Peer reviewe

    Impact of opioid-free analgesia on pain severity and patient satisfaction after discharge from surgery: multispecialty, prospective cohort study in 25 countries

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    Background: Balancing opioid stewardship and the need for adequate analgesia following discharge after surgery is challenging. This study aimed to compare the outcomes for patients discharged with opioid versus opioid-free analgesia after common surgical procedures.Methods: This international, multicentre, prospective cohort study collected data from patients undergoing common acute and elective general surgical, urological, gynaecological, and orthopaedic procedures. The primary outcomes were patient-reported time in severe pain measured on a numerical analogue scale from 0 to 100% and patient-reported satisfaction with pain relief during the first week following discharge. Data were collected by in-hospital chart review and patient telephone interview 1 week after discharge.Results: The study recruited 4273 patients from 144 centres in 25 countries; 1311 patients (30.7%) were prescribed opioid analgesia at discharge. Patients reported being in severe pain for 10 (i.q.r. 1-30)% of the first week after discharge and rated satisfaction with analgesia as 90 (i.q.r. 80-100) of 100. After adjustment for confounders, opioid analgesia on discharge was independently associated with increased pain severity (risk ratio 1.52, 95% c.i. 1.31 to 1.76; P &lt; 0.001) and re-presentation to healthcare providers owing to side-effects of medication (OR 2.38, 95% c.i. 1.36 to 4.17; P = 0.004), but not with satisfaction with analgesia (beta coefficient 0.92, 95% c.i. -1.52 to 3.36; P = 0.468) compared with opioid-free analgesia. Although opioid prescribing varied greatly between high-income and low- and middle-income countries, patient-reported outcomes did not.Conclusion: Opioid analgesia prescription on surgical discharge is associated with a higher risk of re-presentation owing to side-effects of medication and increased patient-reported pain, but not with changes in patient-reported satisfaction. Opioid-free discharge analgesia should be adopted routinely
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