Dynamical Casimir-Polder energy between an excited and a ground-state atom

We consider the Casimir-Polder interaction between two atoms, one in the ground state and the other in its excited state. The interaction is time-dependent for this system, because of the dynamical self-dressing and the spontaneous decay of the excited atom. We calculate the dynamical Casimir-Polder potential between the two atoms using an effective Hamiltonian approach. The results obtained and their physical meaning are discussed and compared with previous results based on a time-independent approach which uses a non-normalizable dressed state for the excited atom.Comment: 11 page

Field fluctuations near a conducting plate and Casimir-Polder forces in the presence of boundary conditions

We consider vacuum fluctuations of the quantum electromagnetic field in the presence of an infinite and perfectly conducting plate. We evaluate how the change of vacuum fluctuations due to the plate modifies the Casimir-Polder potential between two atoms placed near the plate. We use two different methods to evaluate the Casimir-Polder potential in the presence of the plate. They also give new insights on the role of boundary conditions in the Casimir-Polder interatomic potential, as well as indications for possible generalizations to more complicated boundary conditions.Comment: 10 page

Effect of boundaries on vacuum field fluctuations and radiation-mediated interactions between atoms

In this paper we discuss and review several aspects of the effect of boundary conditions and structured environments on dispersion and resonance interactions involving atoms or molecules, as well as on vacuum field fluctuations. We first consider the case of a perfect mirror, which is free to move around an equilibrium position and whose mechanical degrees of freedom are treated quantum mechanically. We investigate how the quantum fluctuations of the mirror's position affect vacuum field fluctuations for both a one-dimensional scalar and electromagnetic field, showing that the effect is particularly significant in the proximity of the moving mirror. This result can be also relevant for possible gravitational effects, since the field energy density couples to gravity. We stress that this interaction-induced modification of the vacuum field fluctuations can be probed through the Casimir-Polder interaction with a polarizable body, thus allowing to detect the effect of the mirror's quantum position fluctuations. We then consider the effect of an environment such as an isotropic photonic crystal or a metallic waveguide, on the resonance interaction between two entangled identical atoms, one excited and the other in the ground state. We discuss the strong dependence of the resonance interaction with the relative position of the atomic transition frequency with the gap of the photonic crystal in the former case, and with the cut-off frequency of waveguide in the latter.Comment: 8 pages, 2 figures, Proceedings of the Eighth International Workshop DICE 2016 Spacetime - Matter - Quantum Mechanic

Validation of an Emission Model for a Marine Diesel Engine with Data from Sea Operations

In this study, a model is developed to simulate the dynamics of an internal combustion engine, and it is calibrated and validated against reliable experimental data, making it a tool that can effectively be adopted to conduct emission predictions. In this work, the Ricardo WAVE software is applied to the simulation of a particular marine diesel engine, a four-stroke engine used in the maritime field. Results from the bench tests are used for the calibration of the model. Finally, the calibration of the model and its validation with full-scale data measured at sea are presented. The prediction includes not only the classic engine operating parameters for a comparison with surveys but also an estimate of nitrogen oxide emissions, which are compared with similar results obtained with emission factors. The calibration of the model made it possible to obtain an overlap between the simulation results and real data with an average error of approximately 7% on power, torque, and consumption. The model provides encouraging results, suggesting further applications, such as in the study on transient conditions, coupling of the engine model with the ship model for a complete simulation of the operating conditions, and optimization studies on consumption and emissions. The availability of the emission data during the sea trial and validated simulation results are the strengths and novelties of this work

Are Swift gamma-ray bursts consistent with the Ghirlanda relation?

A few tight correlations linking several properties of gamma-ray bursts (GRBs), namely the spectral peak energy, the total radiated energy, and the afterglow break time, have been discovered with pre-Swift GRBs. They were used to constrain the cosmological parameters, together with type-Ia supernovae. However, the tightness of these correlations is a challenge to GRB models. We explore the effect of adding Swift bursts to the Ghirlanda and Liang-Zhang relations. Although they are both still valid, they become somewhat weakened mostly due to the presence of significant outliers, which otherwise are apparently normal GRBs so difficult to distinguish. The increased dispersion of the relations makes them less reliable for purposes of precision cosmology.Comment: Paper accepted for publication on A&A (7 pages, 2 figures). Small changes after comment

Nonlocal field correlations and dynamical Casimir-Polder forces between one excited- and two ground-state atoms

The problem of nonlocality in the dynamical three-body Casimir-Polder interaction between an initially excited and two ground-state atoms is considered. It is shown that the nonlocal spatial correlations of the field emitted by the excited atom during the initial part of its spontaneous decay may become manifest in the three-body interaction. The observability of this new phenomenon is discussed.Comment: 17 pages, 1 figure, sub. to Phys. Rev.

Laryngectomized patients caregivers' life experience: A phenomenological study

Background: Laryngectomized patients often depend on their caregivers who have a central and difficult role in supporting them dealing with financial, social, and relational issues. In fact, they feel very responsible and committed, especially considering the time devoted to take care of their beloved. Besides, providing care induces caregivers high stress levels, emotional distress, anxiety and the fear of cancer recurrence or progress. Few studies investigated laryngectomized patients caregivers\u2019 life experience during both the whole course of illness and at the end of the treatment. Therefore, the purpose of our study was to explore, through a phenomenological approach, the lived-experience of primary family caregivers of laryngectomized patients undergoing radical surgery. Methods: Qualitative semi-structured and audiotaped interviews were held with 12 laryngectomized patients\u2019 primary family caregivers. Data were analysed using the descriptive phenomenological approach outlined by Colaizzi. Results: Three key themes emerged: the caregivers lived experience of illness; the change of caregivers\u2019 daily life and how they support their sick beloved. The experience of caregivers\u2019 lived relations changes from being a family member to a supportive carer, and the illness of their beloved negatively affects their psychological lived experience. Their perception of time and Quality of Life change as their perception of the future becomes uncertain. Finally, they feel guilty mainly because of the limited amount of time they can devote to their beloved. Conclusions: The study findings allowed to understand in depth how the presence of a laryngectomized person in the family may affect the life of the caregiver, even after the treatment phase. This suggests the need for healthcare professionals to support caregivers throughout the whole care journey and especially in dealing with the perception of time during the diagnosis and care phases. Further research should be conducted on factors contributing to time perception alteration and possible interventions to support caregivers to cope with it