Self-organized criticality in boson clouds around black holes

Boson clouds around black holes exhibit interesting physical phenomena through the Penrose process of superradiance, leading to black hole spin-down. Axionic clouds are of particular interest, since the axion Compton wavelength could be comparable to the Schwarzschild radius, leading to the formation of "gravitational atoms" with a black hole nucleus. These clouds collapse under certain conditions, leading to a "Bosenova". We model the dynamics of such unstable boson clouds by a simple cellular automaton and show that it exhibits self-organized criticality. Our results suggest that the evolution through the black hole Regge plane is due to self-organized criticality

Disclosure Style and Its Determinants in Integrated Reports

Integrated Reporting promotes a more cohesive and efficient approach to corporate reporting and aims to improve the quality of information available to providers of financial capital. The purpose of this paper was to investigate the determinants of readability and optimism which build the disclosure style of integrated reports. Our research draws on impression management theory and legitimacy theory, while also taking into consideration the cultural system of Hofstede with its further developments by Gray. Our sample consisted of 30 annual reports, extracted randomly from the Integrated Reporting examples database set up by the International Integrated Reporting Council. For the purposes of our investigation, we have carried out a multivariate regression analysis. Firstly, our results show that the higher the revenues of the reporting company, the more balanced their integrated reports, while younger companies use a more optimistic tone when reporting. Additionally, optimism seems to be inversely correlated with the length of the reports. Secondly, entities based in countries with a stronger tendency towards transparency surprisingly provide less readable integrated reports. It was also revealed that companies operating in non-environmentally sensitive industries, as well as International Financial Reporting Standards adopters deliver foggier and thus less readable integrated reports

Revealing the intrinsic nature of the mid-gap defects in amorphous Ge 2 Sb 2 Te 5

Abstract: Understanding the relation between the time-dependent resistance drift in the amorphous state of phase-change materials and the localised states in the band gap of the glass is crucial for the development of memory devices with increased storage density. Here a machine-learned interatomic potential is utilised to generate an ensemble of glass models of the prototypical phase-change alloy, Ge2Sb2Te5, to obtain reliable statistics. Hybrid density-functional theory is used to identify and characterise the geometric and electronic structures of the mid-gap states. 5-coordinated Ge atoms are the local defective bonding environments mainly responsible for these electronic states. The structural motif for the localisation of the mid-gap states is a crystalline-like atomic environment within the amorphous network. An extra electron is trapped spontaneously by these mid-gap states, creating deep traps in the band gap. The results provide significant insights that can help to rationalise the design of multi-level-storage memory devices

Origin of radiation tolerance in amorphous Ge2Sb2Te5 phase-change random-access memory material.

The radiation hardness of amorphous Ge2Sb2Te5 phase-change random-access memory material has been elucidated by ab initio molecular-dynamics simulations. Ionizing radiation events have been modeled to investigate their effect on the atomic and electronic structure of the glass. Investigation of the short- and medium-range order highlights a structural recovery of the amorphous network after exposure to the high-energy events modeled in this study. Analysis of the modeled glasses reveals specific structural rearrangements in the local atomic geometry of the glass, as well as an increase in the formation of large shortest-path rings. The electronic structure of the modeled system is not significantly affected by the ionizing radiation events, since negligible differences have been observed before and after irradiation. These results provide a detailed insight into the atomistic structure of amorphous Ge2Sb2Te5 after irradiation and demonstrate the radiation hardness of the glass matrix

Random walks and search in time-varying networks

The random walk process underlies the description of a large number of real world phenomena. Here we provide the study of random walk processes in time varying networks in the regime of time-scale mixing; i.e. when the network connectivity pattern and the random walk process dynamics are unfolding on the same time scale. We consider a model for time varying networks created from the activity potential of the nodes, and derive solutions of the asymptotic behavior of random walks and the mean first passage time in undirected and directed networks. Our findings show striking differences with respect to the well known results obtained in quenched and annealed networks, emphasizing the effects of dynamical connectivity patterns in the definition of proper strategies for search, retrieval and diffusion processes in time-varying network

Synthesis and electronic properties of polycyclic aromatic hydrocarbons doped with phosphorus and sulfur

International audienc

The use of endoscopic ligation in the treatment and prophylaxis of bleeding from esophageal varices in patients with liver cirrhosis and portal hypertension

Scopul lucrării. Hemoragia din varicele esofagiene și gastrice reprezintă una din cele mai grave complicații la pacienții cu hipertensiune portală cirogenă. Una din metodele eficiente de prevenire și stopare a recurenței hemoragiilor din varicele esofagiene este ligaturarea endoscopică cu aplicarea benzilor elastice. Scopul este analiza rezultatelor obținute în tratamentul hemoragiilor din varicele esofagiene la pacienții cu ciroză hepatică și hipertensiune portală prin metoda de ligaturare endoscopică. Materiale şi metode. Studiul a inclus 110 pacienți cu vârstă cuprinsă între 37-87 ani, diagnosticați cu ciroză hepatică și hipertensiune portală, la care a fost utilizată ligaturarea endoscopică a varicelor esofagiene. Profilaxia primară a hemoragiilor din varicele esofagiene prin ligaturare endoscopică a varicelor esofagiene a fost efectuată la 69 (62,72%) pacienți, iar hemostaza și profilaxia secundară - la 41 (37,28%) pacienți cu varice esofagiene gradul II-III și esofagită erozivă. Rezultate. La 13 pacienți (11,81%), care prezintă hemoragie activă variceală, în primele 24-36 ore prin ligaturare endoscopică s-a obținut hemostaza. Dintre pacienții la care a fost efectuată ligaturarea profilactică în prevenirea primului episod de hemoragie, doar la 4 pacienți (3,63%) au avut loc hemoragii minore, care au fost stopate prin metode conservative de tratament. La 5 pacienți (4,54%) peste 6 luni, din cauza recidivei hemoragiei, a fost repetată ligaturarea endoscopică. Alte complicații sau recidiva hemoragiilor din varicele esofagiene la pacienții supravegheați nu au fost depistate. Concluzii. În urma utilizări ligaturării endoscopice cu benzi elastice a varicelor esofagiene complicații majore sau sistemice nu s-au înregistrat, ceea ce semnifică o rată înaltă de reușită a metodei respective.Aim of study. Hemorrhage from esophageal and gastric varices is one of the most serious complications in patients with cirrhogenic portal hypertension. One of the effective methods of preventing and stopping the recurrence of bleeding from esophageal varices is endoscopic ligation with the application of elastic bands. The purpose is the analysis of the results obtained in the treatment of bleeding from esophageal varices in patients with liver cirrhosis and portal hypertension by the endoscopic ligation method. Materials and methods. The study included 110 patients aged 37-87 years, diagnosed with liver cirrhosis and portal hypertension, who underwent endoscopic ligation of esophageal varices. Primary prophylaxis of bleeding from esophageal varices by endoscopic ligation of esophageal varices was performed in 69 (62.72%) patients, hemostasis and secondary prophylaxis - in 41 (37.28%) patients with grade II-III esophageal varices and erosive esophagitis. Results. In 13 patients (11.81%), who had active variceal hemorrhage, hemostasis by endoscopic ligation was achieved in the first 24-36 hours. Among the patients in whom prophylactic ligation was performed to prevent the first episode of hemorrhage, only 4 patients (3.63%) had minor hemorrhages, which were stopped by conservative treatment methods. In 5 patients (4.54%) due to recurrence of bleeding, endoscopic ligation was repeated over 6 months, Other complications or recurrence of bleeding from esophageal varices in the monitored patients were not detected. Conclusions. In the use of elastic band ligation of esophageal varices, no major or systemic complications were recorded, which signifies a high success rate of this method