Constraints on massive gravity from dipolar mode excitations

We study extreme-mass-ratio systems in theories admitting the Schwarzschild solution and propagating a massive graviton. We show that, in addition to small corrections to the quadrupolar and higher-order modes, a dipolar mode is excited in these theories and we quantify its excitation. While LIGO-Virgo-KAGRA observations are not expected to impose meaningful constraints in the dipolar sector, future observations by the Einstein Telescope or by LISA, together with bounds from dispersion relations, can rule out theories of massive gravity admitting vacuum General Relativistic backgrounds. For the bound to be circumvented, one needs to move away from Ricci-flat solutions, and enter a territory where constraints based on wave propagation and dispersion relations are not reliable.Comment: 5 pages plus Supplemental Materia

Anxiety impact during COVID-19: a systematic review

Introduction: The COVID-19 epidemic has been causing serious physical, but also psychological effects in society. This systematic review sought to identify studies that describe COVID-19 related anxiety, and to understand the impact of anxiety assessment in defining strategies to be implemented in future studies.Methodology: This systematic review included cross-sectional studies with no publication year limit. It was performed a systematic search through three databases, namely, PubMed, Science Direct and Web of Science using the descriptors “COVID-19” and “anxiety”. PRISMA criteria reporting of systematic reviews and meta-analyses were applied. Eligible articles were selected in accordance with inclusion and exclusion criteria. The inclusion criteria were: research articles related with anxiety measurement during the COVID-19 outbreak; interventions to reduce anxiety; and published in English.Results: From 44 references, just four scientific articles were accepted for inclusion within this review. These studies were analyzed regarding their sample, methodology, instruments used, and its results.Conclusions: This systematic review was based on published data at the onset of the pandemic, and it could serve as a basis for the development of implementations plans to improve anxiety disorders. The importance of this theme, the implications and potential directions for future investigations will be discussed.info:eu-repo/semantics/publishedVersio

Axion Weak Leaks: extreme mass-ratio inspirals in ultra-light dark matter

Previous works have argued that future gravitational-wave detectors will be able to probe the properties of astrophysical environments where binary coalesce, including accretion disks, but also dark matter structures. Most analyses have resorted to a Newtonian modelling of the environmental effects, which are not suited to study extreme-mass-ratio inspirals immersed in structures of ultra-light bosons. In this letter, we use relativistic perturbation theory to consistently study these systems in spherical symmetry. We compute the flux of scalar particles and the rate at which orbital energy (and angular momentum) is dissipated via gravitational radiation and depletion of scalars, i.e. dynamical friction. Our results suggest that the Laser Inteferometer Space Antenna will be able to probe ultra-light dark matter structures in the Galaxy by tracking the phase of extreme-mass-ratio inspirals.Comment: 5 pages, 2 figures + supplemental material 9 pages, 2 figure

Gravitational waves from extreme-mass-ratio systems in astrophysical environments

We establish a generic, fully-relativistic formalism to study gravitational-wave emission by extreme-mass-ratio systems in spherically-symmetric, non-vacuum black-hole spacetimes. The potential applications to astrophysical setups range from black holes accreting baryonic matter to those within axionic clouds and dark matter environments, allowing to assess the impact of the galactic potential, of accretion, gravitational drag and halo feedback on the generation and propagation of gravitational-waves. We apply our methods to a black hole within a halo of matter. We find fluid modes imparted to the gravitational-wave signal (a clear evidence of the black hole fundamental mode instability) and the tantalizing possibility to infer galactic properties from gravitational-wave measurements by sensitive, low-frequency detectors.Comment: 7 pages, 3 figures, comments are welcom

Fatores influenciadores do sucesso da implementação de sistemas CRM – uma revisão de literatura

Customer Relationship Management (CRM) is currently an important strategic tool used by organizations to gain competitive advantages. However, since the implementation of a CRM system is not risk-free, it is important to know about the factors that influence its success. This article presents the results of a literature review carried out aiming to identify and describe the main success factors of the implementation of CRM systems.A gestão do relacionamento com o cliente, ou Customer Relationship Management (CRM), assumiu nos últimos anos o papel de ferramenta estratégica fundamental para as organizações obterem vantagens competitivas. No entanto, dado que o processo de implementação de um sistema CRM não é isento de riscos, torna-se importante conhecer os fatores que influenciam o seu sucesso. Este artigo apresenta o resultado de uma revisão da literatura realizada com a finalidade de identificar e descrever os principais fatores influenciadores do sucesso da implementação de sistemas CR