42 research outputs found

    Boson and neutron stars with increased density

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    We discuss boson stars and neutron stars, respectively, in a scalar-tensor gravity model with an explicitly time-dependent real scalar field. While the boson stars in our model -- in contrast to the neutron stars -- do not possess a hard core, we find that the qualitative effects of the formation of scalar hair are similar in both cases : the presence of the gravity scalar allows both type of stars to exist for larger central density as well as larger mass at given radius than their General Relativity counterparts. In particular, we find new types of neutron stars with scalar hair which have radii very close to the corresponding Schwarzschild radius and hence are comparable in density to black holes. This new branch of solutions is stable with respect to the decay into individual baryons.Comment: Matches version published in Phys. Lett.

    White Paper and Roadmap for Quantum Gravity Phenomenology in the Multi-Messenger Era

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    The unification of quantum mechanics and general relativity has long been elusive. Only recently have empirical predictions of various possible theories of quantum gravity been put to test. The dawn of multi-messenger high-energy astrophysics has been tremendously beneficial, as it allows us to study particles with much higher energies and travelling much longer distances than possible in terrestrial experiments, but more progress is needed on several fronts. A thorough appraisal of current strategies and experimental frameworks, regarding quantum gravity phenomenology, is provided here. Our aim is twofold: a description of tentative multimessenger explorations, plus a focus on future detection experiments. As the outlook of the network of researchers that formed through the COST Action CA18108 "Quantum gravity phenomenology in the multi-messenger approach (QG-MM)", in this work we give an overview of the desiderata that future theoretical frameworks, observational facilities, and data-sharing policies should satisfy in order to advance the cause of quantum gravity phenomenology

    White Paper and Roadmap for Quantum Gravity Phenomenology in the Multi-Messenger Era

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    The unification of quantum mechanics and general relativity has long been elusive. Only recently have empirical predictions of various possible theories of quantum gravity been put to test. The dawn of multi-messenger high-energy astrophysics has been tremendously beneficial, as it allows us to study particles with much higher energies and travelling much longer distances than possible in terrestrial experiments, but more progress is needed on several fronts. A thorough appraisal of current strategies and experimental frameworks, regarding quantum gravity phenomenology, is provided here. Our aim is twofold: a description of tentative multimessenger explorations, plus a focus on future detection experiments. As the outlook of the network of researchers that formed through the COST Action CA18108 "Quantum gravity phenomenology in the multi-messenger approach (QG-MM)", in this work we give an overview of the desiderata that future theoretical frameworks, observational facilities, and data-sharing policies should satisfy in order to advance the cause of quantum gravity phenomenology.Comment: Submitted to CQG for the Focus Issue on "Quantum Gravity Phenomenology in the Multi-Messenger Era: Challenges and Perspectives". Please contact us to express interesst of endorsement of this white pape

    Behaviour of a biocompatible titanium alloy during orthogonal micro-cutting employing green machining techniques

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    The sustainability of a process is the objective of modern industries aiming to reduce waste in production, since consumers require high quality and efficiency with fair price. Thus, a good understanding of the process should be its starting point. The manufacture of dental implants is an example in which waste reduction is important for the reduction of prices due to the demand for great quality and accuracy. This study observed the behaviour of sustainable micro-cutting applied to the Ti-6Al-7Nb titanium alloy, considering the ploughing effect on minimum quantity lubrication (MQL) and high-speed machining (HSM) conditions. When compared with dry condition and low-speed cutting in orthogonal micro-cutting, the use of HSM in dry cutting was more efficient than using MQL. The dry condition presented lower surface roughness, whilst the cooled/lubricated condition presented lower burr formation.publishe

    Black holes with scalar hair in Einstein–Gauss–Bonnet gravity

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    Place of fibrates for the treatment of patients with atherogenic dyslipidemia

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    peer reviewedThe demography of dyslipidemia has changed towards a more complex atherogenic dyslipidemia involving increased levels of LDL cholesterol, in particular highly atherogenic small dense particles, hypertriglyceridemia and low HDL cholesterol, together with increased levels of markers of inflammation, thrombogenesis and endothelial dysfunction. Statins were shown to significantly lower cardiovascular morbidity and mortality, but treated patients are still left with a high residual risk, in particular for those with metabolic syndrome, type 2 diabetes, or low HDL cholesterol levels. Fibrates have been shown to reduce plasma triglycerides and increase HDL cholesterol, while improving inflammation, thrombogenesis and endothelial dysfunction. Clinical trials with fibrates have demonstrated their potential to reduce cardiovascular morbidity and mortality too, often through other mechanisms than those of statins. Combination trials of statins with fibrates have shown a more complete improvement of lipid profile and risk markers than each class separately. In contrast with gemfibrozil, fenofibrate does not interact significantly with the pharmacokinetics of statins, and its combination with statins has been shown to have a low risk of muscular side-effects or liver toxicity. The ACCORD outcome trial is exploring possible benefits of the combination of fenofibrate with statins on morbidity and mortality of patients with type 2 diabetes
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