Galactic Punctuated Equilibrium: How to Undermine Carter's Anthropic Argument in Astrobiology

We investigate a new strategy which can defeat the (in)famous Carter's "anthropic" argument against extraterrestrial life and intelligence. In contrast to those already considered by Wilson, Livio, and others, the present approach is based on relaxing hidden uniformitarian assumptions, considering instead a dynamical succession of evolutionary regimes governed by both global (Galaxy-wide) and local (planet- or planetary system-limited) regulation mechanisms. This is in accordance with recent developments in both astrophysics and evolutionary biology. Notably, our increased understanding of the nature of supernovae and gamma-ray bursts, as well as of strong coupling between the Solar System and the Galaxy on one hand, and the theories of "punctuated equilibria" of Eldredge and Gould and "macroevolutionary regimes" of Jablonski, Valentine, et al. on the other, are in full accordance with the regulation- mechanism picture. The application of this particular strategy highlights the limits of application of Carter's argument, and indicates that in the real universe its applicability conditions are not satisfied. We conclude that drawing far-reaching conclusions about the scarcity of extraterrestrial intelligence and the prospects of our efforts to detect it on the basis of this argument is unwarranted.Comment: 3 figures, 26 page

Environmental and Technological Aspects of Converter Slag Utilization in Sintering and Blast-Furnace Production

The paper presents calculation results for predictive conditions of blast furnace operation with the use of converter slag in the iron ore portion of the blast furnace burden. It shows that addition of converter slag in the sinter and blast-furnace burden without correction of the operating conditions is not reasonable as it significantly worsens parameters of blast furnace operation. Long-term operation of blast furnaces with addition of converter slag in the burden will be accompanied by gradual accumulation of phosphorus in metal and will lead to increasing problems regarding phosphorus removal at the converter production stage. The use of converter slag makes it possible to increase the consumption of non-fluxed pellets without changing the sinter basicity and improve parameters of blast-furnace smelting.  The problem of efficient and continuous use of converter slag in blast furnaces can be solved by the complex analysis of this problem: evaluation of economic feasibility of its use as a fluxing agent; feasibility study of this issue for the “blast-furnace production – converter production” complex; analysis of environmental problems during operation at the factory and in the region. Keywords: blast-furnace process, converter slag, slag conditions, iron composition, smelting parameters, coke consumptio

Хирургическое лечение пациентов с патологией коленного сустава и деформациями нижних конечностей: систематический обзор литературы

Background. In patients with knee pathology, a phased approach to surgical treatment is often used: first, corrective osteotomies and then, if necessary, arthroplasty. This technique allows achieving optimal results of treatment. The study aimed to determine promising methods of surgical treatment of patients with knee pathology and deformities of the lower limb axis. Material and Methods. Publication search was conducted in the databases of eLibrary, PubMed, and Scopus from 2000 to 2020 (a search period of 20 years) using the following keywords: deformity of the lower limb axis, deformity correction, and total knee arthroplasty. Demographic data of the patients, features of surgical techniques, and treatment results were analyzed. Results. The literature search identified 1,232 publications, of which 12 studies that analyzed a total of 2.428 patients were included in this review. The surgical treatment covered the period from 1987 to 2018. The average follow-up period was 64.17.4 months, the average patient age was 58.81.4 years, the average duration of surgery was 114.23.9 min, and the average volume of blood loss was 484.030.0 mL. The fixation period with a metal plate, from the moment of osteotomy to hardware removal, was on average 18.01.8 months. Conclusion. Corrective osteotomies can prevent or delay knee replacement by an average of 11.8 years. Osteotomy preceding total arthroplasty does not negatively affect the survival of endoprosthesis, and its results are comparable with the medium- and long-term results of primary arthroplasty.Актуальность. У пациентов с патологией коленного сустава часто используется этапный подход к хирургическому лечению: сначала корригирующие остеотомии, а затем, при необходимости эндопротезирование. Такая тактика позволяет добиться оптимальных конечных результатов лечения. Целью данного обзора является определение перспективных способов хирургического лечения пациентов с патологией коленного сустава в сочетании с деформациями оси нижней конечности. Материал и методы. Поиск публикаций проводили в базах данных eLIBRARY, PubMed и Scopus с глубиной поиска 20 лет (с 2000 по 2020 г.) по ключевым словосочетаниям: деформация оси конечности (deformity of the lower limb axis), корригирующая остеотомия (deformity correction), тотальное эндопротезирование коленного сустава (total knee arthroplasty). Были проанализированы демографические данные пациентов, особенности хирургических вмешательств и результаты лечения. Результаты. По результатам поиска было найдено 1232 публикации, для анализа отобрано 12 исследований, в которые вошли 2428 пациентов. Сроки оперативного лечения пациентов охватили период с 1987 по 2018 г. Срок наблюдения составил в среднем 64,17,4 мес., средний возраст пациентов составил 58,81,4 года, средняя продолжительность операции 114,23,9 мин., средний объем кровопотери 484,030,0 мл. Время фиксации металлоконструкцией, прошедшее от момента остеотомии до удаления, составило в среднем 18,01,8 мес. Заключение. Корригирующие остеотомии могут предотвратить эндопротезирование или отсрочить его в среднем на 11,8 лет. Остеотомия, предшествующая тотальному эндопротезированию, не оказывает отрицательного влияния на выживаемость эндопротеза, ее результаты сопоставимы со среднесрочными и долгосрочными результатами первичного эндопротезирования

On particle collisions in the gravitational field of the Kerr black hole

Scattering of particles in the gravitational field of Kerr black holes is considered. It is shown that scattering energy of particles in the centre of mass system can obtain very large values not only for extremal black holes but also for nonextremal ones existing in Nature. This can be used for explanation of still unresolved problem of the origin of ultrahigh energy cosmic rays observed in Auger experiment. Extraction of energy after the collision is investigated. It is shown that due to the Penrose process the energy of the particle escaping the hole at infinity can be large. Contradictions in the problem of getting high energetic particles escaping the black hole are resolved.Comment: LaTeX, 7 pages, 2 figure

Stability of shear shallow water flows with free surface

Stability of inviscid shear shallow water flows with free surface is studied in the framework of the Benney equations. This is done by investigating the generalized hyperbolicity of the integrodifferential Benney system of equations. It is shown that all shear flows having monotonic convex velocity profiles are stable. The hydrodynamic approximations of the model corresponding to the classes of flows with piecewise linear continuous and discontinuous velocity profiles are derived and studied. It is shown that these approximations possess Hamiltonian structure and a complete system of Riemann invariants, which are found in an explicit form. Sufficient conditions for hyperbolicity of the governing equations for such multilayer flows are formulated. The generalization of the above results to the case of stratified fluid is less obvious, however, it is established that vorticity has a stabilizing effect

Electronic structure of FeSe monolayer superconductors

We review a variety of theoretical and experimental results concerning electronic band structure of superconducting materials based on FeSe monolayers. Three type of systems are analyzed: intercalated FeSe systems AxFe₂Se₂–xSx and [Li₁–xFexOH]FeSe as well as the single FeSe layer films on SrTiO₃ substrate. We present the results of detailed first principle electronic band structure calculations for these systems together with comparison with some experimental ARPES data. The electronic structure of these systems is rather different from that of typical FeAs superconductors, which is quite significant for possible microscopic mechanism of superconductivity. This is reflected in the absence of hole pockets of the Fermi surface at T-point in Brillouin zone, so that there are no “nesting” properties of different Fermi surface pockets. LDA + DMFT calculations show that correlation effects on Fe-3d states in the single FeSe layer are not that strong as in most of FeAs systems. As a result, at present there is no theoretical understanding of the formation of rather “shallow” electronic bands at M-points. LDA calculations show that the main difference in electronic structure of FeSe monolayer on SrTiO ₃ substrate from isolated FeSe layer is the presence of the band of O-2p surface states of TiO₂ layer on the Fermi level together with Fe-3d states, which may be important for understanding the enhanced Tc values in this system. We briefly discuss the implications of our results for microscopic models of superconductivity