533 research outputs found
Apparent horizons in cosmologically-embedded black holes
No full textWe present exact solutions for the cosmological embedding of a broad class of non-singular black holes and we focus on the behavior of their apparent horizons. The evolution of the latter is analyzed as a function of the cosmological redshift z. We show that its size exceeds that of the event horizon of an isolated black hole and increases monotonically with increasing z. Explicit formulas and numerical results are provided for the specific cases of the Hayward and Fan & Wang non-singular black-hole models. Furthermore, we explore the distinct dynamical roles of the event and apparent horizons, highlighting connection between the latter and the recently identified cosmological mass shift in non-singular black holes
Mirko Breyer, Publisher from Križevci
No full textU tekstu se donosi kratak prikaz života i djela križevačkog nakladnika Mirka Breyera. Mirko Breyer bio je pr\>ak hrvatske bibliografije, bibliofil, knjižar-nakladnik i antikvar. Obilježio je početak dvadesetog stoljeća svojim kulturnim radom. Autor donosi dio objavljene i dio neobjavljene građe o Mirku Breyeru.The text is a short overview of the life and work of a Križevci publisher Mirko Breyer. Mirko Breyer was a pioneer of Croation bibliography, a bibliophile, bookseller, publisher and antiquarian. He marked the beginning of the 20th century with his cultural work. The author presents parts of published as well as unpublished material on Mirko Breyer, with his bibliography
Stable wormholes in conformal gravity
No full textWe present a class of Lorentzian traversable wormholes in conformal gravity,
constructed via Weyl rescaling of Minkowski spacetime. As a result, these wormholes are
solutions of every theory of gravity that is both conformally invariant and admits Minkowski
spacetime as a solution. We specifically examine the case of a wormhole possessing a MorrisThorne shape function, arising as a solution of a scalar-tensor conformally invariant theory
of gravity. We show that these solutions represent regular, traversable wormholes that are
also stable at the linear perturbation level. We argue that, when the Weyl symmetry is
spontaneously broken, the broken symmetry phase may lead to a stable “wormhole phase”
alternative to the flat “Minkowski phase”
Cosmological coupling of local gravitational systems
No full textWe investigate the cosmological coupling of spherical, local astrophysical systems. We derive a general formula quantifying the cosmological coupling of the Misner-Sharp mass of these objects. We show that, in the weak-field limit, the cosmological coupling is only allowed if there are pressure anisotropies. We also apply our results to galaxies, modelling them with the Navarro-Frenk-White and Einasto profiles. We show that the galactic mass can be coupled to the cosmological dynamics and examine its dependence on the scale factor of the universe
Effective quantum spacetimes from functional renormalization group
No full textUsing the functional renormalization group approach, we construct effective quantum spacetime geometries by self-consistently deforming the classical Schwarzschild-de Sitter black hole solution. This involves studying how quantum corrections, driven by the running of the Newton's and cosmological constants, modify the solution across the infrared and ultraviolet regimes. We show that these quantum modifications replace the Schwarzschild singularity with a milder conical one. Moreover, two new features emerge in the ultraviolet regime. First, we identify a phase transition between anti-de Sitter/de Sitter spacetime occurring when the object's mass exceeds a first critical threshold. Second, we predict the formation of horizons once the object's mass exceeds a second threshold. Both thresholds are of the order of the Planck mass. Finally, we investigate the role of the anomalous dimension in the conformal sector of the theory
Quasi-local masses and cosmological coupling of black holes and mimickers
No full textMotivated by the recent heated debate on whether the masses of local objects,
such as compact stars or black holes (BHs), may be affected by the large-scale,
cosmological dynamics, we analyze the conditions under which, in a general
relativity framework, such a coupling small/large scales is allowed. We shed
light on some controversial arguments, which have been used to rule out the
latter possibility. We find that the cosmological coupling occurs whenever the
energy of the central objects is quantified by the quasi-local Misner-Sharp
mass (MS). Conversely, the decoupling occurs whenever the MS mass is fully
equivalent to the (nonlocal) Arnowitt-Deser-Misner (ADM) mass. Consequently,
for singular BHs embedded in cosmological backgrounds, like the
Schwarzschild-de Sitter or McVittie solutions, we show that there is no
cosmological coupling, confirming previous results in the literature.
Furthermore, we show that nonsingular compact objects couple to the
cosmological background, as quantified by their MS mass. We conclude that
observational evidence of cosmological coupling of astrophysical BHs would be
the smoking gun of their nonsingular nature.Comment: 16 pages, no figures, some discussions expanded, matches version
published on JCA
Professor Mirko Škampa - personality portrait
No full textBakalářská práce se zabývá osobností Mirko Škampy. Obsahuje stručný životopis, přehled jeho nejvýznamnějších absolventů a osobní rozhovor s pedagogem. Velkou část práce autor věnuje analýze některých cvičení z jeho metodické publikace – Škola hry na violoncello.The goal of the thesis is to present the personality of Mirko Škampa. It includes a brief biography, an overview of his most famous graduates and an personal interveiw with professor Škampa. The author of this thesis devotes its great part to analyse of some exercises from his methodics – School of cello playing for kids
Professor Mirko Bagaric, 2019
No full textLeading sentencing and criminal justice scholar, Professor Mirko Bagaric, has been appointed as the new Dean of Swinburne Law School, where he has been Director of Research for three years.
Professor Bagaric brings vast experience to the role. He was Dean of Law at Deakin University from 2003 to 2006 and 2012 to 2015. He has been a practicing lawyer for 20 years, and is a prolific author and media commentator.
Photograph originally appeared in the Media Centre Release, 'Leading criminal justice scholar appointed new Dean of Swinburne Law School' on Monday 02 December 2019
Postmodern Aspects of Mirko Kovač`s Novels
No full textThis paper deals with postmodern techniquesin of the novels of Mirko Kovač, a prominent figure in the postmodern literature. In particular, the study examinesnarrative strategies which deviate from traditional paradigms and yet create a distinct reality of the text. Postmodern principles such as “the poetic narrator ” (and the “poetic reading ” associated with it), temporal distortion, the questioning of historical facts, hybridization of narrative texts, metatextuality and citationality, documentation, fragmentation and text segmentation will be addressed using concrete examples. Mirko Kovač stands out with his distinctive poetics which contains elements of postmodernism, intertwined with traces of other poetics. In this paper we will dwell precisely on the postmodern aspects of his texts. In weaving the fabric of his texts, the author employs narrative strategies that threaten and break the traditional conventional narrative with its prominent elements such as narrative instance, time, space, composition, characters. All canonised forms and values are reviewed and dissolved in a specific way. In his writings, Kovač makes use of specific forms of citation and documentarity. Special attention in our work shall be devoted to Kovač’s novelistic structures, in which he as an author spans a full creative range. We will try to shed light on all phenomena of the narrative text which are developed in terms of the postmodern
Mirko Ramovš – znanstvenik med ljubitelji
No full textAvtor v članku predstavlja prispevek Mirka Ramovša pri prenašanju etnokoreoloških spoznanj v dejavnost folklornih skupin. V prvem delu prispevka opozarja na njegovo vlogo v folklorni dejavnosti in dosežke na tem področju, v drugem prispevka pa analizira vprašanja, povezana z njegovim dojemanjem izvirnosti folklornih skupin, njihovim ohranjanjem izročila in kulturnim poslanstvom.
***
In this paper, the author presents Mirko Ramovš’s contribution to the transfer of ethnochoreological findings to folk dance groups. In the first part, the author highlights Ramovš’s role in the world of folklore activity and his achievements, whereas the second part of the paper focuses on an analysis of questions related to his understanding of the originality of folk dance groups, the preservation of their traditions and their cultural mission
- …
