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We study the problem of finding algebraically stable models for non-invertible holomorphic fixed point germs

We study the interaction between a plane gravitational wave and electromagnetic fields, analyzing this interaction in the proper detector frame. The gravitational field is treated as an effective electromagnetic medium, and within this framework, we demonstrate that the coupling between pre-existing electromagnetic fields and the gravitational wave generates new effective currents. This approach, an alternative to previously explored methods, has the advantage of employing Fermi coordinates, which enable direct reference to measurable quantities. To assess the impact of the effect of gravitational waves, we solve Maxwell’s equations for some standard configurations of the electric and magnetic fields.

We discuss the linear gravitoelectromagnetic approach used to solve Einstein’s equations in the weak-field and slow-motion approximation, which is a powerful tool to explain, by analogy with electromagnetism, several gravitational effects in the solar system, where the approximation holds true. In particular, we discuss the analogy, according to which Einstein’s equations can be written as Maxwell-like equations, and focus on the definition of the gravitoelectromagnetic fields in non-stationary conditions. Furthermore, we examine to what extent, starting from a given solution of Einstein’s equations, gravitoelectromagnetic fields can be used to describe the motion of test particles using a Lorentz-like force equation.

Gravitoelectromagnetic analogies are somewhat ubiquitous in General Relativity, and they are often used to explain peculiar effects of Einstein’s theory of gravity in terms of familiar results from classical electromagnetism. Perhaps, the best known of these analogy pertains to the similarity between the equations of electromagnetism and those of the linearized theory of General Relativity. But the analogy is somewhat deeper and ultimately rooted in the splitting of spacetime, which is preliminary to the definition of the measurement process in General Relativity. In this paper we review the various approaches that lead to the introduction of a magnetic-like part of the gravitational interaction, briefly called gravitomagnetic and, then, we provide a survey of the recent developments both from the theoretical and experimental viewpoints.

In-service teacher training must ensure professional development based on both disciplinary and pedagogical research, taking advantage of collaboration between different training and institutional agencies. In this article we will talk about a collaborative experience among different training partners, to increase teachers’ interest in new tools and learning environments. We use different kinds of training sessions to introduce innovative didactic methodologies for teaching and learning involving both university research staff and secondary school teachers. The training project has planned a series of five meetings, divided into a seminar and a laboratorial part on the following topics: new didactic technologies, weather data processing, space missions, image processing, and modern physics. The laboratorial workshops were centered on applications that can be integrated into civic education and dual training. The meetings, followed by a hundred teachers, formed a design basis for the initial teacher training courses that will be activated from 2024 by the Italian Universities.

Background: The prevalence of refractive errors has sharply risen over recent decades. Despite the established role of genetics in the onset and progression of such conditions, the environment was also shown to play a pivotal role. Indeed, the COVID-19 pandemic has majorly impacted people’s lifestyles and healthy habits, especially among the youth, which might have led to a significant increase in this trend. Therefore, the aim of this study was to investigate the actual prevalence of refractive errors in a large cohort of pediatric patients. Methods: A large cohort of 496 participants was screened through anamnesis, a non-cycloplegic autorefractometry, a corrected and uncorrected visual acuity assessment, and a questionnaire and was retrospectively evaluated. Results: Overall, refractive errors were present in 25.1% of eyes, of which 14.6% were diagnosed with myopia/myopic astigmatism and 10.5% with hyperopia/hyperopic astigmatism. Among the patients enrolled, 298 (60%) had their eyes checked one year earlier or before and 122 (25%) had never had ophthalmological consultations; a total of 105 (21%) needed glasses and 34 (7%) required a change in their previous prescription. A substantial increase in daily electronic device screen exposure was declared by 426 patients (87.6%). Conclusions: Pediatric patients appear to have a higher prevalence of refractive errors than before.

Light can be used as a probe to explore the structure of space-time: this is usual in astrophysical and cosmological tests; however, it has been recently suggested that this can be done also in terrestrial laboratories. Namely, the Gyroscopes In General Relativity (GINGER) project aims at measuring post-Newtonian effects, such as the gravito-magnetic ones, in an Earth-based laboratory, by means of a ring laser array. Here, we first review the theoretical foundations of the Sagnac effect, on which ring lasers are based, and then, we study the Sagnac effect in a terrestrial laboratory, emphasizing the origin of the gravitational contributions that GINGER aims at measuring. Moreover, we show that accurate measurements allow one to set constraints on theories of gravity different from general relativity. Eventually, we describe the experimental setup of GINGER.

The GINGER project is based on ring lasers and is under construction at the underground Gran Sasso laboratories, as part of the underground geophysical observatory of Gran Sasso (UGGS). Large frame ring lasers are top sensitivity instruments to measure angular rotation rate, in particular when attached to the Earth crust they can measure with very high precision the Earth angular velocity. This kind of measurements when the precision is of the order of 1 part in 10 9 , are certainly relevant for geophysics and geodesy, for instance to measure the fast variation of the length of Day (LoD), but are also relevant for fundamental physics, since are affected by de Sitter and Lense-Thirring effects and can be used to investigate Lorentz’s violations. Ring lasers ensure long-term continuous operation with record sensitivity. The limit of 1 part in 10 9 of the Earth’s rotation rate has already been demonstrated, and recent sensitivity study has shown that the ring laser shot noise limit is at least a factor 10 better than expected. GINGER and its status report will be described.

In this paper, we consider the space-time of a charged mass endowed with an angular momentum. The geometry is described by the exact Kerr–Newman solution of the Einstein equations. The peculiar symmetry, though exact, is usually described in terms of the gravito-magnetic field originated by the angular momentum of the source. A typical product of this geometry is represented by the generalized Sagnac effect. We write down the explicit form for the right/left asymmetry of the times of flight of two counter-rotating light beams along a circular trajectory. Letting the circle shrink to the origin the asymmetry stays finite. Furthermore it becomes independent both from the charge of the source (then its electromagnetic field) and from Newton’s constant: it is then associated only to the symmetry produced by the gravitomagnetic field. When introducing, for the source, the spin of a Fermion, the lowest limit of the Heisenberg uncertainty formula for energy and time appears.

We study the interaction between gravitational waves and a quantum two-level system consisting of a spin 1/2 particle using the formalism of the proper detector frame. This approach highlights the effects of gravitational waves on both the particles and the observer, emphasizing that only relative measurements can be made. Specifically, within this framework, the gravitational field of the waves is described using the gravitoelectromagnetic analogy. The interaction of the system is then determined by the gravitomagnetic field of the wave, which induces a time-dependent perturbation. We analyze this perturbation for both generic frequencies and resonance conditions, and discuss its implications.