Single and binary stellar progenitors of long-duration gamma-ray bursts

This review describes the most common theories behind long-duration gamma-ray burst progenitors. I discuss two astrophysical scenarios: the collapsar and the magnetar models. According to their requirements, the progenitor should be an envelope-free massive star with a fast rotating, collapsing iron core. Such an object, called a TWUIN star, may be produced by chemically homogeneous evolution either from a massive single star or a massive binary system. Various outcomes of this evolutionary path (e.g. supernova explosions and gravitational wave production) are also mentioned, and directions for future research are suggested. In the era of multi-messenger astronomy, my hope is to present a timely overview on how stellar astrophysicists are searching for progenitor models of long-duration gamma-ray bursts, and what they have found so far.Comment: Proceedings of the XII Multifrequency Behaviour of High Energy Cosmic Sources Workshop, 12-17 June, 2017, Palermo, Ital

How may short-duration GRBs form? A review of progenitor theories

The origin of gamma-ray bursts (GRBs) is still a fascinating field of research nowadays. While we have been collecting more and more observationally constrained properties of GRB-physics, new theoretical results on the progenitor evolution (be it stellar or compact object) have also emerged. I review some of the most promising progenitor theories for forming a short-duration GRB. A special emphasis is put on the hypothetical case of forming a short-duration GRB through the double black hole merger scenario -- in which case we may expect to observe a gravitational wave emission too. The chemically homogeneous channel for forming a black hole binary is discussed, and the stellar progenitors (so called TWUIN stars) are introduced. The birth place of these short-duration GRBs with a gravitational wave counterpart may be low-metallicity, starforming dwarf galaxies.Comment: Conference Proceedings of 14th INTEGRAL/BART Workshop, 3-7 April 2017, Karlovy Vary, Czech Republic http://adsabs.harvard.edu/abs/2017CoSka..47..108

The Hierarchical Ray Engine

Due to the success of texture based approaches, ray casting has lately been confined to performing preprocessing in realtime applications. Though GPU based ray casting implementations outperform the CPU now, they either do not scale well for higher primitive counts, or require the costly construction of spatial hierarchies. We present an improved algorithm based on the Ray Engine approach, which builds a hierarchy of rays instead of objects, completely on the graphics card. Exploiting the coherence between rays when displaying refractive objects or computing caustics, realtime frame rates are achieved without preprocessing. Thus, the method fills a gap in the realtime rendering repertoire

Politikai kommunikáció az átalakuló médiatérben

A politikus kommunikációs szerepeket játszik, amelyekre ma is erőteljes hatást gyako - rolnak azok a technikák, amelyek segítségével üzeneteit a célszemélyekhez el kíván - ja juttatni. Ezek a hatások – legyenek azok általános, a politikus gondolkodását, fogal - mi apparátusát, nyelvi kultúráját érintő, illetve konkrét, a kommunikációs stratégiákat befolyásoló fejlemények – egyaránt összetettebbé teszik a kommunikációs szituáció - kat, s ezáltal a politikusok kommunikációs szerepét is

Community and Language in the Information Age

This article argues that the electronically mediated communication contributes to the construction of new, mediated forms of communities which are based on the interaction or operational synthesis of virtual and physical communities. The appearance of these new forms of communities leads to a new conceptualization of the relation between self and community. The aim of this essay, on the one hand, is to show that with the mediatization of communities, our conce pt of community becomes more complex. On the other hand, in this article I try to prove the assumption that the medium of the mediatization and new conceptualization of community is a specific pictorial language of electronically mediated communication

The Hierarchical Ray Engine

Due to the success of texture based approaches, ray casting has lately been confined to performing preprocessing in realtime applications. Though GPU based ray casting implementations outperform the CPU now, they either do not scale well for higher primitive counts, or require the costly construction of spatial hierarchies. We present an improved algorithm based on the Ray Engine approach, which builds a hierarchy of rays instead of objects, completely on the graphics card. Exploiting the coherence between rays when displaying refractive objects or computing caustics, realtime frame rates are achieved without preprocessing. Thus, the method fills a gap in the realtime rendering repertoire

Mediated communication and mediated communities in the information age

This article argues that the electronically mediated communication contributes to the construction of new, mediated forms of communities which are based on the synthesis of virtual and physical communities. The appearance of these new forms of communities leads to a new conceptualization of the relation between self and community. The aim of this article, on the one hand, is to show that with the mediatization of communities, our concept of community becomes more comples. On the other hand, in this essay we consider the assumption that the medium of the mediatization and new conceptualization of community is a specific, pictorial language of electronically mediated communication