Quasi-linear static solutions in massive gravity

The static vacuum spherically symmetric solutions of massive gravity theories possess two integration constant: the mass M and a scalar charge S. The presence of this scalar charge reflects the modification of the gravitational interaction as compared to General Relativity. Surprisingly, these solutions are non-linear even at large distances from the sources, implying that their asymptotic behavior is different from that obtained in the linear perturbation theory. The aim of this paper is to understand how these modified spherically symmetric solutions emerge from a quasi-linear approximation in order to generalize them to any arbitrary mass distribution. Along with these modified solutions, we found a new class of static solutions having a Yukawa shape

Theoretical and phenomenological aspects of theories with massive gravitons

In this thesis, we study three aspects of theories with massive gravitational waves. In the first part, we review to problems and issues of theories with massive gravitons before introducing models where Lorentz invariance is spontaneously broken by the vacuum expectation value of four scalar fields. In the second part, we discuss three aspects of these models: instantaneous interaction, spherically vacuum solutions and cosmological perturbations.Comment: PhD thesis, 116 page

Instantaneous interaction in massive gravity

In general relativity, the instantaneous contributions to the gravitational potentials cancel each other in observable, leaving the theory free of physical instantaneous interactions. In models where these subtle cancellations are spoiled by the presence of fields that break Lorentz invariance, physical instantaneous interactions are possible. Such interactions are studied for a model of Lorentz- violating massive gravity

Vers un éclairage public plus durable - Le cas de la Wallonie

Presentation organised by the Smart Light-HUB (INTERREG V A Grande Région) at Bliiida (Metz). The presentation aims to discuss the management of public lighting in Wallonia, and the development of sustainable public lighting. The presentation follows the framework of a political, economic, social, technological, environmental and legal (PESTEL) analysis.3. Good health and well-being11. Sustainable cities and communities13. Climate action14. Life below water15. Life on lan

Impact de la pollution lumineuse sur la biodiversité

" Chauves-souris, chouettes, crapauds, lucioles… Pour ces animaux et bien d’autres, la nuit n’est pas un temps de repos, mais au contraire, une période d’activité privilégiée. Des milliers d’années d’évolution leur ont conféré une parfaite adaptation à l’obscurité dont ils tirent avantage. Mais voilà que depuis quelques décennies, la lune et les étoiles ne sont plus les seules sources de lumière nocturne. Les bords de routes, les bâtiments et même les falaises sont éclairés tandis que les halos des villes illuminent le ciel. Naturalistes et astronomes tirent la sonnette d’alarme. Quelles sont les conséquences de cette profusion d’éclairage sur la faune nocturne et sur le fonctionnement des écosystèmes en général ? Que faire pour permettre aux animaux de se déplacer malgré ces innombrables barrières de lumière ? Alors que l’emprise de l’Homme sur son environnement n’a jamais été aussi forte, ne serait-il pas temps de rendre sa place à la nuit ? "3. Good health and well-being11. Sustainable cities and communities13. Climate action14. Life below water15. Life on lan

Light pollution and biodiversity

3. Good health and well-being14. Life below water15. Life on land13. Climate actio

Impact de la pollution lumineuse sur la biodiversité

" Chauves-souris, chouettes, crapauds, lucioles… Pour ces animaux et bien d’autres, la nuit n’est pas un temps de repos, mais au contraire, une période d’activité privilégiée. Des milliers d’années d’évolution leur ont conféré une parfaite adaptation à l’obscurité dont ils tirent avantage. Mais voilà que depuis quelques décennies, la lune et les étoiles ne sont plus les seules sources de lumière nocturne. Les bords de routes, les bâtiments et même les falaises sont éclairés tandis que les halos des villes illuminent le ciel. Naturalistes et astronomes tirent la sonnette d’alarme. Quelles sont les conséquences de cette profusion d’éclairage sur la faune nocturne et sur le fonctionnement des écosystèmes en général ? Que faire pour permettre aux animaux de se déplacer malgré ces innombrables barrières de lumière ? Alors que l’emprise de l’Homme sur son environnement n’a jamais été aussi forte, ne serait-il pas temps de rendre sa place à la nuit ? "3. Good health and well-being11. Sustainable cities and communities13. Climate action14. Life below water15. Life on lan

Impact of public lighting on passengers’ modal choice for nocturnal transportation

Artificial light at night has many ecological consequences, including attracting or repelling certain animals. Dark corridors have been implemented in several regions to preserve or restore an ecological network conducive to nocturnal wildlife, maintain the quality of the night sky, and protect human health. These dark corridors are land-use plans that aim to reduce or delete specific light points and create paths of darkness, allowing for the movement of nocturnal species. As such, these corridors help preserve biodiversity and reduce energy consumption. However, they can also induce a sense of insecurity and modify the modal choice of night-time travel. In order to analyse the impact of public lighting on Walloons, we conducted a survey. This questionnaire has been completed by 685 citizens (allowing us to reach a 3.74% error margin, with a 95% confidence level). Our study enabled us to determine the evolution of the feeling of safety in different contexts and lighting conditions, the changes in modal split, and the acceptance of lighting reduction policies, respondents being or not aware of light pollution. Our results should help decision-makers determine appropriate policies in land-use management and, more specifically, public lighting.9. Industry, innovation and infrastructure11. Sustainable cities and communities13. Climate action15. Life on land14. Life below wate

Hamiltonian Analysis of the Higgs Mechanism for Graviton

In this paper we perform the canonical description of the Higgs mechanism for gravity and provide the Hamiltonian definition of the massive gravities.Comment: 18 page

Shedding light on passenger modal choice: Examining the relationship between public lighting and nocturnal mobility

Lighting is an essential aspect of our daily lives, but artificial lighting has received criticism for its negative impact on the environment, wildlife, and health of people . Adequate lighting is crucial for creating a safe environment (in terms of road safety, criminality and feeling of safety), especially when using soft modes of transport like walking or cycling at night. Poor lighting, on the other hand, can make people feel unsafe and uncomfortable, potentially deterring them from using these modes. Our research offers three contributions. Firstly, it identifies the required characteristics of public lighting for safe and acceptable nocturnal mobility. Secondly, it investigates how the night affects modal choices. Thirdly, it assesses citizens' willingness to accept reduced public lighting and how the energy crisis has impacted their judgement. To gain insights into the mobility patterns of the population in the Walloon region, we conducted two surveys using Qualtrics. The target population for both surveys was individuals aged 16 and above living in the Walloon region. The first survey was administered online from February 16th to March 29th, 2022, resulting in a total of 677 complete responses. The second survey was also administered online from 1st October to 15th November 2022, resulting in 807 complete responses. The collected dataset was analysed using RStudio, and population weights were applied based on three demographic criteria (gender, age, and province) to ensure that the sample was representative of the Walloon population. The findings of this study highlight the importance of public lighting in nocturnal mobility and provide insights into the factors influencing citizens' modal choices and acceptable levels of lighting reductions. Citizens are willing to accept reductions in public lighting levels during the night, which could contribute to reducing light pollution and energy consumption. The study also reveals a positive correlation between the energy crisis and citizens' willingness to accept reductions in public lighting levels, highlighting the importance of implementing energy-efficient public lighting systems. Further research could examine the impact of public lighting on the health of citizens, potential emerging technologies such as smart lighting systems and autonomous vehicles, and the impact of reduced lighting on nocturnal wildlife, light pollution, and carbon emissions.11. Sustainable cities and communities15. Life on land13. Climate actio