Entanglement entropy in de Sitter: no pure states for conformal matter

In this paper, we consider the entanglement entropy of conformal matter for finite and semi-infinite entangling regions, as well as the formation of entanglement islands in four-dimensional de Sitter spacetime partially reduced to two dimensions. We analyze complementarity and pure state condition of the entanglement entropy of pure states and show that they never hold in the given setup. We consider two different types of Cauchy surfaces in the extended static patch and flat coordinates, correspondingly. For former, we found that entanglement entropy of a pure state is always bounded from below by a constant and never becomes zero, as required by quantum mechanics. In turn, the difference between the entropies for some region and its complement, which should be zero for a pure state, in direct calculations essentially depends on how the boundaries of these regions evolve with time. Regarding the flat coordinates, it is impossible to regularize spacelike infinity in a way that would be compatible with complementarity and pure state condition, as opposed, for instance, to two-sided Schwarzschild black hole. Finally, we discuss the information paradox in de Sitter and show that the island formula does not resolve it. Namely, we give examples of a region with a time-limited growth of entanglement entropy, for which there is no island solution, and the region, for which entanglement entropy does not grow, but the island solution exists.Comment: v1: 25 pages, 10 figures; v2: 25 pages, 10 figures, references added, notation clarifie

Entanglement Islands and Infrared Anomalies in Schwarzschild Black Hole

In this paper, island formation for entangling regions of finite size in the asymptotically flat eternal Schwarzschild black hole is considered. We check the complementarity property of entanglement entropy which was implicitly assumed in previous studies for semi-infinite regions. This check reveals the emergence of infrared anomalies after regularization of a Cauchy surface. A naive infrared regularization based on ``mirror symmetry'' is considered and its failure is shown. We introduce an improved regularization that gives a correct limit agreed with the semi-infinite results from previous studies. As the time evolution goes, the endpoints of a finite region compatible with the improved regularization become separated by a timelike interval. We call this phenomenon the ``Cauchy surface breaking''. Shortly before the Cauchy surface breaking, finite size configurations generate asymmetric entanglement islands in contrast to the semi-infinite case. Depending on the size of the finite regions, qualitatively new behaviour arises, such as discontinuous evolution of the entanglement entropy and the absence of island formation. Finally, we show that the island prescription does not help us to solve the information paradox for certain finite size regions.Comment: v1: 55 pages, 19 figures; v2: 57 pages, 19 figures, references added, Sec. 5 presentation improve

Treatment of ischemic stroke caused by dissection and occlusion of internal carotid artery in a young patient

The type and etiology of stroke in young patients are known to differ from those in elderly patients, that influences the diagnosis and treatment. Dissection of cerebral arteries holds the top position in the structure of the causes of ischemic stroke in children and young people below 45 years. Currently no clear guideline on the proper treatment of this pathology exists. The article presents the case of acute ischemic stroke in a young patient (the stroke was caused by the occlusion due to dissection of the internal carotid artery) successfully treated with radiosurgical method - stenting of the cervical part of the artery with the transition to petrous segment of the left carotid artery using combined proximal and distal protection of cerebral vessels. The control of patient's state and results of angiography and ultrasound demonstrate the favourable immediate and medium-term prognosis for the patient

Local quenches in fracton field theory: non-causal dynamics and fractal excitation patterns

We study the out-of-equilibrium dynamics induced by a local perturbation in fracton field theory. For the ${\mathbb Z}_4$ and ${\mathbb Z}_8$-symmetric free fractonic theories, we compute the time dynamics of several observables such as the two-point Green function, $\langle \phi^2\rangle$ condensate, energy density, and the dipole momentum. The time-dependent considerations highlight that the free fractonic theory breaks causality and exhibits instantaneous signal propagation, even if an additional relativistic term is included to enforce a speed limit in the system. For the theory in finite volume, we show that the fracton wave front acquires fractal shape with non-trivial Hausdorff dimension, and argue that this phenomenon cannot be explained by a simple self-interference effect.Comment: v1: 25 pages, 7 figures; v2: 25 pages, 7 figures, references added, minor correction

Dilation of the Infarct-Related Coronary Artery to Reduce the Incidence of the No-Reflow Phenomenon in STEMI Patients

Background: The pathogenesis of slow/no-reflow phenomena is a critical socio-medical problem due to high mortality and work disability rates in patients with ST-segment elevation myocardial infarction (STEMI). Slow/no-reflow phenomena are multifactorial involving 4 key elements: 1) distal embolization of the coronary bed of the infarct-related coronary artery; 2) ischemic damage to the myocardium; 3) reperfusion injury of the heart muscle; 4) individual (genetic) susceptibility of the microcirculation to injury.   Objective: To analyze the outcomes of percutaneous coronary interventions (PCI) in patients with STEMI and TIMI 0 blood flow of an infarct-related coronary artery based on the strategy to restore antegrade blood flow (balloon predilation or dilation of an infarctrelated artery).   Materials and methods: We analyzed treatment outcomes of 209 patients with STEMI and TIMI 0 blood flow. The patients were grouped based on the PCI strategy: group 1 included 147 patients who underwent balloon angioplasty to restore antegrade blood flow, and group 2 included 62 patients who underwent dilation of an infarct-related coronary artery.   Results: Our study found that direct stenting in STEMI patients was associated with statistically significantly lower risk of slow/noreflow phenomena (P = 0.001, Pearson’s χ2) and, as a result, better functional outcomes of treatment (chronic heart failure grade classified according to Strazhesko-Vasilenko and by left ventricular ejection fraction) that were also statistically significant (P = 0.001, Pearson’s χ2).   Conclusions: Our study demonstrated that the risk of slow/no-reflow phenomena in patients with TIMI 0 blood flow of an infarctrelated coronary artery was statistically significantly lower (P = .001, Pearson’s χ2) in the group of patients who underwent dilation of an infarct-related coronary artery to restore antegrade blood flow. Functional outcomes (chronic heart failure grade and overall survival) were also better in this group of patients (P = .001, Pearson’s Chi-square). Moreover, dilation of an infarct-related coronary artery was associated with preserved left ventricular ejection fraction compared with the group of patients who underwent balloon angioplasty to restore antegrade blood flow (P < 0.001, Pearson’s χ2)

Clinical use of various endovascular stenting techniques in challenging coronary interventions

Aim. Development of an algorithm of actions for stenting of artery stenosis during challenging percutaneous coronary interventions (PCI) based on the analysis of the results of different endovascular techniques. Methods. We analyzed the experience of the department of radiologic endovascular diagnosis and treatment of Stavropol regional clinical hospital for endovascular surgical treatment of atherosclerosis of coronary arteries. The study included 317 cases of coronary interventions with technically impossible stent delivery to stenosis by standard method along the front-line guidewire and standard choice of the guide in case of distal TIMI 3 flow. For the study the patients were divided into 3 groups comparable by the number of subjects: 104, 113 and 100 respectively. For each group we determined different stages of enhancing support with consistent step-wise transition. The groups differed by the used methods of enhancing support and consistency of their use. Among other methods of support group 2 included the method of guide change and delivery of the second guidewire of enhanced support. At the same time groups 1 and 3 used these methods separately. Results. The smallest number of unsuccessful interventions was observed in group 2 compared to those of groups 1 and 3. The relative risk indicators also demonstrate the high effectiveness of tactics used in the group 2. Conclusion. The most preferable method for the necessary support when stent delivery distal to stenosis is impossible, is a choice of optimal guide and use of the second guidewire of enhanced support

Curie Temperatures for Three-Dimensional Binary Ising Ferromagnets

Using the Swendsen and Wang algorithm, high accuracy Monte Carlo simulations were performed to study the concentration dependence of the Curie temperature in binary, ferromagnetic Ising systems on the simple-cubic lattice. Our results are in good agreement with known mean-field like approaches. Based on former theoretical formulas we propose a new way of estimating the Curie temperature of these systems.Comment: nr. of pages:13, LATEX. Version 2.09, Scientific Report :02/1994 (Univ. of Bergen, Norway), 7 figures upon reques

The charge-assisted hydrogen-bonded organic framework (CAHOF) self-assembled from the conjugated acid of tetrakis(4-aminophenyl)methane and 2,6-naphthalenedisulfonate as a new class of recyclable Brønsted acid catalysts

The acid–base neutralization reaction of commercially available disodium 2,6-naphthalenedisulfonate (NDS, 2 equivalents) and the tetrahydrochloride salt of tetrakis(4-aminophenyl)methane (TAPM, 1 equivalent) in water gave a novel three-dimensional charge-assisted hydrogen-bonded framework (CAHOF, F-1). The framework F-1 was characterized by X-ray diffraction, TGA, elemental analysis, and 1H NMR spectroscopy. The framework was supported by hydrogen bonds between the sulfonate anions and the ammonium cations of NDS and protonated TAPM moieties, respectively. The CAHOF material functioned as a new type of catalytically active Brønsted acid in a series of reactions, including the ring opening of epoxides by water and alcohols. A Diels–Alder reaction between cyclopentadiene and methyl vinyl ketone was also catalyzed by F-1 in heptane. Depending on the polarity of the solvent mixture, the CAHOF F-1 could function as a purely heterogeneous catalyst or partly dissociate, providing some dissolved F-1 as the real catalyst. In all cases, the catalyst could easily be recovered and recycled

MODELING APPROACH FOR LEAN BLOWOUT PHENOMENON

ABSTRACT Modern concepts for reducing thermal NO emissions require the use of very lean fuel/air mixtures. Therefore a problem of lean quench should be solved during design process of gas turbine combustor and it's operational development. Since maintenance of flame stability for wide range of gas turbine engine operational modes is essential, therefore there is a great demand for models which are able to predict lean blow out limits of turbulent, premixed and partially premixed, aerodynamically stabilized flames. In this paper a model describing flame destabilization process is presented. This model takes into account various physical processes, which lead to flame destabilization. The model is based on equation for reaction progress variable. An expression of source term of this equation contains turbulent flame speed, which is calculated with the use of Zimont's formula modification, proposed by authors. The results of simulation were compared with test results for our lean premixed combustor. Fuel mass flow rate of pilot zone was decreased during test until heat release of pilot flame front became insufficient and couldn't support a combustion process in a lean premixed zone. Our simulation with modified model allows to get prediction of lean blowout limit