Born-Infeld Black Holes in 4D Einstein-Gauss-Bonnet Gravity

A novel four-dimensional Einstein-Gauss-Bonnet gravity was formulated by D. Glavan and C. Lin [Phys. Rev. Lett. 124, 081301 (2020)], which is intended to bypass the Lovelock's theorem and to yield a non-trivial contribution to the four-dimensional gravitational dynamics. However, the validity and consistency of this theory has been called into question recently. We study a static and spherically symmetric black hole charged by a Born-Infeld electric field in the novel four-dimensional Einstein-Gauss-Bonnet gravity. It is found that the black hole solution still suffers the singularity problem, since particles incident from infinity can reach the singularity. It is also demonstrated that the Born-Infeld charged black hole may be superior to the Maxwell charged black hole to be a charged extension of the Schwarzschild-AdS-like black hole in this new gravitational theory. Some basic thermodynamics of the black hole solution is also analyzed. Besides, we regain the black hole solution in the regularized four-dimensional Einstein-Gauss-Bonnet gravity proposed by H. L\"u and Y. Pang [arXiv:2003.11552].Comment: 13 pages and 18 figures, published versio

Motion of Spinning Particles around Electrically Charged Black Hole in Eddington-inspired Born-Infeld Gravity

A test particle possessing spin angular momentum moves along a non-geodesic path due to an additional spin-curvature force. We study the spinning test particle moving in the vicinity of the electrically charged black hole formation in Eddington-inspired Born-Infeld (EiBI) gravity. Through the numerical analysis of its effective potential and orbits, it is found that the orbital eccentricity reduces as the deviation parameter $\kappa$ increases. The parameters of inner most stable circular orbit (ISCO) decrease monotonously with $\kappa$ when the spin angular momentum is small, however they changes non-monotonously with $\kappa$ when the spin is large enough. Moreover, the spin dependences of ISCO parameters have similar behavior to that of Reissner-Nordstr\"om (RN) black hole. We analyze the causality of the circular orbits by using the superluminal constraint condition as well. As a result, two new parameter regions may emerge in case of large $\kappa$, where the particle has two stable circular orbits with one subluminal and the other superluminal.Comment: 12 pages, 28 figure

Primordial black holes from an inflationary potential valley

Primordial black holes (PBHs) could be formed if large perturbations are generated on small scales in inflation. We study a toy inflation model with a local minimum. The curvature perturbations are enhanced when the inflaton passes through the local minimum, with more efficient amplification rate than that of quasi-inflection point inflation, leading to the production of PBHs on small scales. The PBHs could comprise the total dark matter in the mass window $10^{16}$--$10^{20}$g.Comment: 7 pages,4 figure

Decoupled advection-dispersion method for determining wall thickness of slurry trench cutoff walls

Low-permeability slurry trench cutoff walls are commonly constructed as barriers for containment of subsurface point-source pollution or as part of seepage-control systems on contaminated sites. A method to estimate wall thickness in slurry wall design is proposed based on decoupling the advective and dispersive components of contaminant fluxes through the wall. The relative error of the result obtained by the proposed method compared with that by an analytical solution was found to increase as the ratio of the specified breakthrough exit concentration (c*) to the source concentration (c0) increased. For c*/c0 of less than 0.1, which covers common practical situations, the relative error was not greater than 4% and was always conservative, indicating that the proposed method provides sufficient accuracy for design. For a given breakthrough criterion (i.e., c*/c0), the relative error was low for the scenarios having either a low or high column Peclet number, where either dispersion or advection dominates the contaminant migration, respectively, and the relative error was high for the scenario having an intermediate column Peclet number, in which case the coupling effect of advective and dispersive migrations is relatively high

Study on the influencing factors and strategies of sorted collection of urban refuse in China

Although the sorted collection of urban refuse in China started later than that in developed countries, it has been sustained 14 years since the implementation of pilot project of waste sorting. However, the waste sorting among cities is still making slow progress and beset with difficulties in China. With a review of the actual situation of waste sorting in China, this article firstly introduced the urban refuse sorted way in China, and then analysed the influencing factors of the sorted collection of urban refuse. At last, we put forward some strategies and suggestions for dealing with the prominent challenges of the sorted collection of urban refuse in China

Clinical parameters associated with absence of endocervical/transformation zone component in conventional cervical Papanicolaou smears

AbstractObjectiveTo study clinical factors predicting the absence of endocervical/transformation zone (EC/TZ) components of conventional cervical Papanicolaou (Pap) smears.Materials and methodsThe medical charts of patients who received Pap smears between March 2006 and August 2006 in the hospital were reviewed. The results of their Pap smears were retrieved while their demographic and clinical information were obtained from the medical charts. After excluding 378 cases with incomplete demographic data and 1397 cases with a history of pelvic irradiation, pelvic malignancy, and hysterectomy, 5662 cases were enrolled for data analysis. The relationship between clinical parameters and the absence of EC/TZ component was analyzed by Pearson Chi-square tests with Yates continuity correction and binary logistic regression tests.ResultsThe incidence of satisfactory but absence of EC/TZ component was 8.7% (491/5662). Pregnancy increased the absence of EC/TZ component [odds ratio (OR}: 2.84, 95% confidence interval (CI): 2.14–3.77, p<0.0001]. Postpartum status and endocervical polyps decreased incidence (OR: 0.61, 95% CI: 0.38–0.98, p = 0.043 and OR: 0.33, 95% CI: 0.25–0.44, p<0.0001, respectively).ConclusionsPregnancy is the only clinical factor associated with increased incidence of absence of EC/TZ cells. For these pregnant women undergoing a Pap smear, a more effective strategy may be needed to get a satisfactory smear with adequate EC/TZ components