9,238 research outputs found
Correction to: Malignant epithelioid neoplasm of the ileum with ACTB-GLI1 fusion mimicking an adnexal mass (BMC Women's Health, (2022), 22, 1, (104), 10.1186/s12905-022-01679-0)
No full textFollowing publication of the original article (1), The author names were incorrectly published as Ambrosio Marco, Virgilio Agnese, Raffone Antonio, Arena Alessandro, Raimondo Diego, Alletto Andrea, Seracchioli Renato and Casadio Paolo. But this should have been Marco Ambrosio, Agnese Virgilio, Antonio Raffone, Alessandro Arena, Diego Raimondo, Andrea Alletto, Renato Seracchioli, and Paolo Casadio. The original article has been updated
SEMINARIO di SCIENZA e FILOSOFIA: Le leggi di Natura
No full textCosa significa legge di natura? Dopo le più recenti scoperte scientifiche, che significato assume questa domanda? E ancora scorgiamo regoralità in natura perché la natura è intrinsecamente regolare o perché il nostro modo di interpretarla è teso alla regolarizzazione dei fenomeni? Il problema di capire e capirci in un universo quanto mai sconosciuto sarà affrontato in modo comparato da alcuni esperti in settori diversi delle Scienze Naturali e della Filosofia per focalizzare l’attenzione sulla necessaria integrazione delle recenti scoperte scientifiche nel dibattito sempre aperto della moderna Cosmologia.
Il Prof. Antonino Zichichi terrà la prima lezione introduttiva il giorno 11 Febbraio alle ore 17. Le lezioni successive, a carattere seminariale si svolgeranno dal 12 al 17 Febbraio 2008 dalle 16 alle 19.30 del pomeriggio e il 17 Febbraio dalle 9.30 alle 12.30. Ogni giornata prevede l’intervento di un docente esperto in una delle Scienze Naturali ed uno esperto in Filosofia, per illustrare le problematiche esposte nel programma allegato. La partecipazione al Seminario, previo colloquio finale, può essere accreditata come corso a libera scelta (2CFU) per gli studenti della Facoltà di Scienze Matematiche, Fisiche Naturali e per quelli iscritti al Bacelleriato in Filosofia.
Comitato Scientifico: Giovanni Bertuzzi (Preside dello Studio Filosofico Domenicano e Direttore del Centro San Domenico) e Rita Casadio (Cattedra di Biofisica/Bioinformatica, Presidente del Bologna International Master in Bioinformatics, Università di Bologna).
Docenti: Giovanni Bertuzzi (Studio Filosofico Domenicano, Facoltà Teologica dell’Emilia-Romagna); Fabrizio Bolletta (Cattedra di Chimica generale, Università di Bologna), Giorgio Carbone (Studio Filosofico Domenican, Facoltà Teologica dell’Emilia-Romagna); Rita Casadio (Cattedra di Biofisica/Bioinformatica, Università di Bologna); Mauro Dorato (Cattedra di Filosofia della Scienza, Università di Roma Tre); Andrea Porcarelli (Cattedra di Pedagogia generale e sociale, Università di Padova; Studio Filosofico Domenicano); Alessandro Toscano (Cattedra di Campi Elettromagnetici, Università di Roma Tre); Giorgio Turchetti (Cattedra di Meccanica Analitica, Università di Bologna). Sede del Seminario: Studio Filosofico Domenicano, Convento San Domenico, Piazza San Domenico 13, Bologna. Segreteria Organizzativa: E-mail: [email protected]; http: www.studiofilosofico.it. Piazza San Domenico, 13 - I - 40124 Bologna BO
Matter and gravitons in the gravitational collapse
No full textAbstractWe consider the effects of gravitons in the collapse of baryonic matter that forms a black hole. We first note that the effective number of (soft off-shell) gravitons that account for the (negative) Newtonian potential energy generated by the baryons is conserved and always in agreement with Bekenstein's area law of black holes. Moreover, their (positive) interaction energy reproduces the expected post-Newtonian correction and becomes of the order of the total ADM mass of the system when the size of the collapsing object approaches its gravitational radius. This result supports a scenario in which the gravitational collapse of regular baryonic matter produces a corpuscular black hole without central singularity, in which both gravitons and baryons are marginally bound and form a Bose–Einstein condensate at the critical point. The Hawking emission of baryons and gravitons is then described by the quantum depletion of the condensate and we show the two energy fluxes are comparable, albeit negligibly small on astrophysical scales
Bootstrapped Newtonian Cosmology and the Cosmological Constant Problem
No full textBootstrapped Newtonian gravity was developed with the purpose of estimating the impact of quantum physics in the nonlinear regime of the gravitational interaction, akin to corpuscular models of black holes and inflation. In this work, we set the ground for extending the bootstrapped Newtonian picture to cosmological spaces. We further discuss how such models of quantum cosmol- ogy can lead to a natural solution to the cosmological constant problem
The role of collapsed matter in the decay of black holes
No full textWe try to shed some light on the role of matter in the final stages of black hole evaporation from the fundamental frameworks of classicalization and the black-to-white hole bouncing scenario. Despite being based on very different grounds, these two approaches attempt at going beyond the background field method and treat black holes as fully quantum systems rather than considering quantum field theory on the corresponding classical manifolds. They also lead to the common prediction that the semiclassical description of black hole evaporation should break down and the system be disrupted by internal quantum pressure, but they both arrive at this conclusion neglecting the matter that formed the black hole. We instead estimate this pressure from the bootstrapped description of black holes, which allows us to express the total Arnowitt–Deser–Misner mass in terms of the baryonic mass still present inside the black hole. We conclude that, although these two scenarios provide qualitatively similar predictions for the final stages, the corpuscular model does not seem to suggest any sizeable deviation from the semiclassical time scale at which the disruption should occur, unlike the black-to- white hole bouncing scenario. This, in turn, makes the phenomenology of corpuscular black holes more subtle from an astrophysical perspective
Corpuscular slow-roll inflation
No full textWe show that a corpuscular description of gravity can lead to an inflationary scenario similar to Starobinsky’s model without requiring the introduction of the inflaton field. All relevant properties are determined by the number of gravitons in the cosmological condensate or, equivalently, by their Compton length. In particular, the relation between the Hubble parameter H and its time derivative dot H required by cosmic microwave background observations at the end of inflation, as well as the (minimum) initial value of the slow-roll parameter, are naturally obtained from the Compton size of the condensate
Orbits in a stochastic Schwarzschild geometry
No full textWe study geodesics in the Schwarzschild space-time affected by an uncertainty in the mass parameter described by a Gaussian distribution. This study could serve as a first attempt at investigating possible quantum effects of black hole space-times on the motion of matter in their surroundings as well as the role of uncertainties in the measurement of the black hole parameters
Global and local horizon quantum mechanics
No full textHorizons are classical causal structures that arise in systems with sharply defined energy and corresponding gravitational radius. A global gravitational radius operator can be introduced for a static and spherically symmetric quantum mechanical matter state by lifting the classical “Hamiltonian” constraint that relates the gravita- tional radius to the ADM mass, thus giving rise to a “horizon wave-function”. This minisuperspace-like formalism is shown here to be able to consistently describe also the local gravitational radius related to the Misner–Sharp mass function of the quantum source, provided its energy spectrum is determined by spatially localised modes
Horizon quantum mechanics of rotating black holes
No full textAbstract The horizon quantum mechanics is an approach that was previously introduced in order to analyze the gravitational radius of spherically symmetric systems and compute the probability that a given quantum state is a black hole. In this work, we first extend the formalism to general space-times with asymptotic (ADM) mass and angular momentum. We then apply the extended horizon quantum mechanics to a harmonic model of rotating corpuscular black holes. We find that simple configurations of this model naturally suppress the appearance of the inner horizon and seem to disfavor extremal (macroscopic) geometries
Quantum corpuscular corrections to the Newtonian potential
No full textWe study an effective quantum description of the static gravitational potential for spherically symmetric systems up to the first post-Newtonian order. We start by obtaining a Lagrangian for the gravitational potential coupled to a static matter source from the weak field expansion of the Einstein-Hilbert action. By analyzing a few classical solutions of the resulting field equation, we show that our construction leads to the expected post-Newtonian expressions. Next, we show that one can reproduce the classical Newtonian results very accurately by employing a coherent quantum state, and modifications to include the first post-Newtonian corrections are considered. Our findings establish a connection between the corpuscular model of black holes and post-Newtonian gravity, and set the stage for further investigations of these quantum models
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