Analog geometry in an expanding fluid from AdS/CFT perspective

The dynamics of an expanding hadron fluid at temperatures below the chiral transition is studied in the framework of AdS/CFT correspondence. We establish a correspondence between the asymptotic AdS geometry in the 4+1-dimensional bulk with the analog spacetime geometry on its 3+1 dimensional boundary with the background fluid undergoing a spherical Bjorken type expansion. The analog metric tensor on the boundary depends locally on the soft pion dispersion relation and the four-velocity of the fluid. The AdS/CFT correspondence provides a relation between the pion velocity and the critical temperature of the chiral phase transition.Comment: 16 pages, 2 figures, revised to match the published version, relation to static solutions clarified, the section on de Sitter boundary removed, results unchange

Video game consumer profiles

The video game development path is full of drastic changes. The growth and strengthening of technology and the growth of innovation in the technology sector have inevitably led to the growth of this industry, which is nowadays achieving unexpected, enviable results. The basic human need for entertainment and socializing contributes to the popularity of video games. Today, video games are played by people of all ages and genders, and the most common reasons for playing video games are fun, socializing, learning, and reducing stress, but video games also provide interactive entertainment, unlike books, movies or theatre performances. The popularity of video games is witnessed by numerous communities on social networks through which professional gamers share their experiences, tips and video game reviews, and there are statistics that support this popularity and growth. The features offered by the video game industry do not need to be particularly emphasized because the results, statistics and enthusiastic players speak for themselves. This paper deals with the demographics and behaviour of consumers playing video games. The aim is to identify the main features of the user, video game players, and to identify and determine user habits and trends affecting the users. The consumer is a social and cultural being. At the same time, he is an individual for himself, a member of a family, a member of a group or a certain class or class in society, a representative of a particular nation, race, religion, nationality of a particular country, etc. The consumer is a person who has the money (assets) and a will to buy the goods or a service. In this paper, the above consumer definitions will be brought in correlation with the video game market, with an industry that encompasses various forms of modern entertainment. It is shown that technology and new modes of entertainment are present among all, and that we need to adjust the time we live in. Playing some kind of video games has become a normal activity of any normal, modern individual

ANALOGUE COSMOLOGY IN A HADRONIC FLUID

Analog gravity models of general relativity seem promising routes to providing laboratory tests of the foundation of quantum field theory in curved space-time. In contrast to general relativity, where geometry of a spacetime is determined by the Einstein equations, in analog models geometry and evolution of analog spacetime are determined by the equations of fluid mechanics. In this paper we study the analogue gravity model based on massless pions propagating in a expanding hadronic fluid. The analog expanding spacetime takes the form of an FRW universe, with the apparent andtrapping horizons dened in the standard way

Analogue surface gravity near the QCD chiral phase transition

Using the formalism of relativistic acoustic geometry we study the expanding chiral fluid in the regime of broken chiral symmetry near the QCD chiral phase transition temperature T_c. The dynamics of pions below T_c is described by the equation of motion for a massless scalar field propagating in curved spacetime similar to an open FRW universe. The metric tensor depends locally on the soft pion dispersion relation and the four-velocity of the fluid. In the neighborhood of the critical point an analogue trapped region forms with the analogue trapped horizon as its boundary. We show that the associated surface gravity diverges near the critical point as 1/(T_c-T). Hence, if the horizon forms close to the critical temperature the analogue Hawking temperature may be comparable with or even larger than the background fluid temperature.Comment: 11 pages, typos corrected, clarifications added, references added, accepted in Phys. Lett.

Occurrence of P. aeruginosa in Water Intended for Human Consumption and in Swimming Pool Water

Considering the fact that water is a basic need of every living being, it is important to ensure its safety. In this work, the data on the presence of the opportunistic pathogen P. aeruginosa in drinking water (n = 4171) as well as in pool water (n = 5059) in Primorje-Gorski Kotar County in Croatia in the five-year period (2016–2020) were analysed. In addition, the national criteria were compared with those of neighboring countries and worldwide. The proportion of P. aerugino-sa- positive samples was similar for drinking water (3.9%) and pool water (4.6%). The prevalence of this bacterium was most pronounced in the warmer season. P. aeruginosa-positive drinking water samples were mostly collected during building commissioning, while pool samples were from entertainment and spa/hydromassage pools. Outdoor pools showed a higher percentage of positive samples than indoor pools, as well as the pools filled with freshwater rather than sea-water. The highest P. aeruginosa load was found in rehabilitation pools. Cro

Analogue cosmology in relativistic fluids

Glavni ciljevi ove disertacije su postići vjerno simuliranje širenja svemira pomoću analognih modela gravitacije i istražiti doprinos analogne kozmološke produkcije čestica u relativističkom hadronskom fluidu. Koristeći ideju da je zakrivljenost u geometriji prostora moguće postići dinamikom fluida, opisani su učinci klasične gravitacije u analognom relativističkom sustavu. Dan je teorijski recept kako u realističnom laboratoriju visokih energija reproducirati gravitacijske fenomene koje nije moguće direktno opaziti u prirodi, kao što su Hawkingovo zračenje, vremenski ovisne konfiguracije crnih rupa i dinamika evolucije širećeg svemira. Geometrija i evolucija analognog prostor-vremena određene su jednadžbama mehanike fluida, za razliku od opće teorije relativnosti gdje ovu ulogu igraju Einsteinove jednadžbe. Kao prirodni medij za relativističke analogne modele proučavamo hadronsku materiju nastalu u sudarima teških iona. Ekstremni uvjeti visoke gustoće i temperature u kojima nastaje hadronska materija odgovaraju uvjetima u ranom svemiru neposredno nakon Velikog Praska. Pokazuje se kako propagacija bezmasenih piona u hadronskom fluidu simulira analogni svemir geometrijski ekvivalentan Friedmann-Robertson-Walkerovom (FRW) prostor-vremenu s negativnom prostornom zakrivljenošću. Dobiveni su uvjeti pod kojima se u hadronskom fluidu formiraju uhvaćene plohe te je izračunata temperatura analognog Hawkingovog zračenja iz uhvaćenog horizonta. Napravljena je kvantitativna usporedba analogne kozmološke produkcije čestica i analognog Hawkingovog zračenja.The main objectives of this research are to faithfully simulate the expansion of the universe using analog models of gravity and investigate the contribution of the analog cosmological particle production in a relativistic hadronic fluid. Using the idea that a curved space geometry can be achieved by the means of fluid dynamics, the effects of classical gravity in relativistic analog system are described. A theoretical recipe is given how to reproduce, in a high-energy realistic laboratory, gravitational phenomena that can not be directly observed in nature, such as the Hawking radiation, time-dependent configurations of black holes and evolution dynamics of an expanding universe. Geometry and evolution of analog spacetime are determined by the equations of fluid mechanics, in contrast to the general relativity where they are described by Einstein’s equations. As a natural medium for relativistic analog models we study the hadron matter created in relativistic heavy ion collisions. Extreme conditions of very high density and temperature in which hadronic matter is created correspond to the conditions in the early universe shortly after the Big Bang. It is shown that propagation of massles pions in the hadronic fluid simulates an analog universe which is geometrically equivalent to the Friedmann-Robertson- Walker (FRW) spacetime with negative spatial curvature. We find the conditions under which trapped surfaces are formed and calculate the analog Hawking radiation temperature from the trapped horizon. A quantitative comparison of analogue cosmological particle production and analogue Hawking radiation is given

Simulating SIR processes on networks using weighted shortest paths

ISSN:2045-232