Scalar fields in the Lense-Thirring background with a cosmic string and Hawking radiation

We analyze the influence of the gravitational field produced by a slowly rotating black hole with a cosmic string along the axis of symmetry on a massive scalar field. Exact solutions of both angular and radial parts of the Klein-Gordon equation in this spacetime are obtained, and are given in terms of the confluent Heun functions. We emphasize the role of the presence of the cosmic string in these solutions. We also investigate the solutions in regions near and far from the event horizon. From the radial solution, we obtain the exact wave solutions near the exterior horizon of the black hole, and discuss the Hawking radiation of massive scalar particles.Comment: 6 page

Inconsistencies on the Hubble tension from the ages of the oldest astrophysical objects

Recently different cosmological measurements have shown a tension in the value of the Hubble constant, $H_0$. Assuming the $\Lambda$CDM model, the Planck satellite mission has inferred the Hubble constant from the cosmic microwave background (CMB) anisotropies to be $H_0 = 67.4 \pm 0.5 \, \rm{km \, s^{-1} \, Mpc^{-1}}$. On the other hand, low redshift measurements such as those using Cepheid variables and supernovae Type Ia (SNIa) have obtained a significantly larger value. For instance, Riess et al. reported $H_0 = 73.04 \pm 1.04 \, \rm{km \, s^{-1} \, Mpc^{-1}}$, which is $5\sigma$ apart of the prediction from Planck observations. This tension is a major problem in cosmology nowadays, and it is not clear yet if it comes from systematic effects or new physics. The use of new methods to infer the Hubble constant is therefore essential to shed light on this matter. In this paper, we discuss using the age of the oldest astrophysical objects (OAO) to probe the Hubble tension. We show that, although this data can provide additional information, the method can also artificially introduce a tension.Comment: 6 pages, 6 figure

The Importance of Preventive and Corrective Maintenance in Works

The present study addresses the problems brought by the lack of preventive and corrective maintenance. The purpose of this work is to focus on the importance of preventive and corrective maintenance, for the prevention and conservation of engineering works. This work will focus and indicate some guidelines and measures that must be taken to keep the engineering works in order and in a good state of repair. The importance of the implementation of preventive and corrective maintenance for engineering works will also be mentioned, as well as the importance of always having at disposal a specialized team to be always ready to attend such eventualities that may occur in the facilities of this type of service and what are the basic requirements for a good manutentor

A Systematic Review

Publisher Copyright: © 2023 by the authors.The recognition that the gut microbiota of obese children differs from lean children has grown, and some studies suggest that physical activity positively influences the gut microbiota. This systematic review explores the changes in the gut microbiota composition of obese and non-obese children and adolescents and provides an understanding of the effects of physical activity interventions in modulating their microbiota. The PRISMA protocol was used across PubMed, Scopus, and Web of Science. Overall, twenty-four research papers were included in accordance with the chosen inclusion and exclusion criteria, eighteen studies compared the gut microbiota of obese and normal-weight children and adolescents, and six studies explored the effect of physical activity interventions on the gut microbiota. The analysis indicated that obese gut microbiota is reduced in Bacteroidetes, Bifidobacterium and alpha diversity but enriched in Proteobacteria and Lactobacillus. Interventions with physical activity seem to improve the alpha diversity and beneficial bacteria linked to body weight loss in children and adolescents. The gut microbiota of obese children exhibited a remarkably individual variation. More interventions are needed to clearly and accurately explore the relationships between child obesity, gut microbiota, and physical activity and to develop approaches to decrease the incidence of paediatric obesity.publishersversionpublishe