Nucleon-Nucleon Scattering in a Strong External Magnetic Field and the Neutrino Emissivity

The nucleon-nucleon scattering in a large magnetic background is considered to find its potential to change the neutrino emissivity of the neutron stars. For this purpose we consider the one-pion-exchange approximation to find the NN cross-section in a background field as large as $10^{15}\texttt{G}-10^{18}\texttt{G}$. We show that the NN cross-section in neutron stars with temperatures in the range 0.1-5 \texttt{MeV} can be changed up to the one order of magnitude with respect to the one in the absence of the magnetic field. In the limit of the soft neutrino emission the neutrino emissivity can be written in terms of the NN scattering amplitude therefore the large magnetic fields can dramatically change the neutrino emissivity of the neutron stars as well.Comment: 21 pages, 5 figures, to appear in PR

Generation of circular polarization of the CMB

According to the standard cosmology, near the last scattering surface, the photons scattered via Compton scattering are just linearly polarized and then the primordial circular polarization of the CMB photons is zero. In this work we show that CMB polarization acquires a small degree of circular polarization when a background magnetic field is considered or the quantum electrodynamic sector of standard model is extended by Lorentz-noninvariant operators as well as noncommutativity. The existence of circular polarization for the CMB radiation may be verified during future observation programs and it represents a possible new channel for investigating new physics effects.Comment: 28 pages, v3, Phys. Rev. D 81, 084035 (2010

Neutrino-electron scattering in noncommutative space

Neutral particles can couple with the $U(1)$ gauge field in the adjoint representation at the tree level if the space-time coordinates are noncommutative (NC). Considering neutrino-photon coupling in the NC QED framework, we obtain the differential cross section of neutrino-electron scattering. Similar to the magnetic moment effect, one of the NC terms is proportional to $\frac 1 T$, where $T$ is the electron recoil energy. Therefore, this scattering provides a chance to achieve a stringent bound on the NC scale in low energy by improving the sensitivity to the smaller electron recoil energy.Comment: 12 pages, 2 figure

Risk of stroke in hospitalized SARS-CoV-2 infected patients: A multinational study

Background: There is an increased attention to stroke following SARS-CoV-2. The goal of this study was to better depict the short-term risk of stroke and its associated factors among SARS-CoV-2 hospitalized patients. Methods: This multicentre, multinational observational study includes hospitalized SARS-CoV-2 patients from North and South America (United States, Canada, and Brazil), Europe (Greece, Italy, Finland, and Turkey), Asia (Lebanon, Iran, and India), and Oceania (New Zealand). The outcome was the risk of subsequent stroke. Centres were included by non-probability sampling. The counts and clinical characteristics including laboratory findings and imaging of the patients with and without a subsequent stroke were recorded according to a predefined protocol. Quality, risk of bias, and heterogeneity assessments were conducted according to ROBINS-E and Cochrane Q-test. The risk of subsequent stroke was estimated through meta-analyses with random effect models. Bivariate logistic regression was used to determine the parameters with predictive outcome value. The study was reported according to the STROBE, MOOSE, and EQUATOR guidelines. Findings: We received data from 26,175 hospitalized SARS-CoV-2 patients from 99 tertiary centres in 65 regions of 11 countries until May 1st, 2020. A total of 17,799 patients were included in meta-analyses. Among them, 156(0.9) patients had a stroke�123(79) ischaemic stroke, 27(17) intracerebral/subarachnoid hemorrhage, and 6(4) cerebral sinus thrombosis. Subsequent stroke risks calculated with meta-analyses, under low to moderate heterogeneity, were 0.5 among all centres in all countries, and 0.7 among countries with higher health expenditures. The need for mechanical ventilation (OR: 1.9, 95 CI:1.1�3.5, p = 0.03) and the presence of ischaemic heart disease (OR: 2.5, 95 CI:1.4�4.7, p = 0.006) were predictive of stroke. Interpretation: The results of this multi-national study on hospitalized patients with SARS-CoV-2 infection indicated an overall stroke risk of 0.5(pooled risk: 0.9). The need for mechanical ventilation and the history of ischaemic heart disease are the independent predictors of stroke among SARS-CoV-2 patients. Funding: None. © 2020 The Author

Trace of energy-momentum tensor and gravitational backreaction of Schwinger scalars in 3D de Sitter spacetime

In this paper, we consider a massive charged scalar field coupled to a uniform electric field background in a 3 dimensional de Sitter spacetime. We consider the value of the dimensionless coupling constant of the scalar field to the scalar curvature of a 3 dimensional de Sitter spacetime equal to 1/8. We compute the expectation value of the trace of the energy-momentum tensor in the in-vacuum state and we show that using adiabatic subtraction regularization method the linear ultraviolet divergence is removed and a finite expression obtain. We investigate the behavior of the regularized trace for different intensities of the scalar field mass and the electric field. We show that the trace as a function of the electric field has a discontinuity at which it changes the sign. We show that for the case of a conformally coupled scalar field to the de Sitter spacetime the trace vanishes, and there is no trace anomaly. We discuss the gravitational backreaction effect of the created Schwinger pairs. &nbsp

Impact of Urban Morphology on Urban Heat Island Intensity in a Mediterranean City: Global Sensitivity and Uncertainty Analysis

Urban microclimate tools are used to estimate the magnitude of urban heat island (UHI) and the effectiveness of mitigation strategies. However, acquiring information for creating reliable models is often challenging. Sensitivity analysis (SA) and uncertainty analysis (UA) can be effectively used to acquire information and make informed decisions even in uncertain scenarios. However, few studies still carry out SA and UA on microclimate models. This study used SA and UA techniques to evaluate the impact of urban morphology on the UHI phenomenon in the Mediterranean climate during a summer heat wave period in Rome, Italy. The urban weather generator (UWG) tool is used, coupled to SA and UA tools. The input parameters of four common local climate zones (LCZs) are used to develop the urban model. The UA results show that the highest urban heat island intensity (UHII) occurs in LCZ2, the densest district among the selected LCZs. The SA confirms that LCZ parameters such as the mean height of buildings, building surface fraction, and aspect ratio are the most influential ones in this study

Prooxidant-antioxidant balance and hs-CRP in patients with Beta-thalassemia major

Background: Beta-thalassemia major is one of the most frequent hemoglobinopathies in the world. This is a study on the levels of prooxidant-antioxidant balance (PAB) that can measure the pro-oxidant burden and the anti-oxidant capacity simultaneously in one assay, giving a redox index, as well as an assessment of high-sensitivity C-reactive protein (hs-CRP) in patients with β-thalassemia major. It also determines the impact both on kidney function tests. Methods: Ninety subjects with β-thalassemia major (βTM) and 90 more healthy subjects as the control group were enrolled in the study. Laboratory parameters, serum hs-CRP, and the novel assay of prooxidant-antioxidant balance were measured. Results: Biochemical and hematological variables, except MCHC, were significantly decreased in patients. Ferritin (p 0.05) did not significantly increase in patients. Spearman's correlation univariate analysis showed no significant correlation between PAB with hs-CRP or ferritin. However, there was a significant statistical correlation between hs-CRP with creatinine and triglycerides. Also we found a slight and negative correlation between high-density lipoprotein cholesterol, hemoglobin, and hemotocrit with inflammatory factor. Conclusions: Briefly, we found higher levels of PAB values and a slight increase in hs-CRP concentration in patients, which may be involved in the pathological consequences of β-thalassemia major and contribute to the gradual development of injury to the organs