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Highlights • Irregularities in long (30 ka to 6.2 Ma) records of Kamchatka volcanism have been studied. • The grouping of eruptions is more pronounced than in a Poisson process, even with assumed data loss. • Milankovitch frequencies have not been detected in the datasets. • The variation in timing of ash-falls among the North Pacific sites predominates over hemispheric-scale climatic forcing. Abstract Explosive volcanism is one of the most dangerous and far-reaching natural hazards. The largest eruptions are the rarest, so studies of their temporal patterns have to rely on long archives. In this paper, we apply fractal and spectral analyses to the 6.2 Ma-long record of ash-falls at the Detroit Seamount (DS6M), > 600 km east of the Kamchatka Peninsula, NW Pacific, combined with a terrestrial record for the last 30 ka (T30ka). These datasets are the most complete for volcanism in the North Pacific, and DS6M spans all Pleistocene glaciations. In both datasets, events are grouped (Weibull parameter k < 0.84) with no characteristic scale of grouping in the time domain of thousands to millions of years. The fractal dimension of the studied data below the unity may be intrinsic to the volcanism (e.g. as a proxy of fractal composition and topography of a subducting plate) or represent uneven deposition and recovery of tephra. Only for the last 700 ka of DS6M, an increase in the correlation dimension values suggests the applicability of spectral analysis; however, no Milankovitch frequencies have been detected in this dataset. When compared to other North Pacific data for areas repeatedly glaciated in the Middle and Late Pleistocene and to a climate proxy of 18O isotopic stack LR04, the studied data suggest that variation in timing of ash-falls among the sites predominates over hemispheric-scale climatic forcing. If so, Quaternary glaciations had a limited effect on the timing of large explosive eruptions in North Pacific, still affecting the transit and deposition of erupt

In this paper we represent nonperturbative calculation for one-loop Quantum Electrodynamics (QED) vacuum birefringence in presence of strong magnetic field. The dispersion relations for electromagnetic wave propagating in strong magnetic field point to retention of vacuum birefringence even in case when the field strength greatly exceeds Sauter-Schwinger limit. This gives a possibility to extend some predictions of perturbative QED such as electromagnetic waves delay in pulsars neighbourhood or wave polarization state changing (tested in PVLAS) to arbitrary magnetic field values. Such expansion is especially important in astrophysics because magnetic fields of some pulsars and magnetars greatly exceed quantum magnetic field limit, so the estimates of perturbative QED effects in this case require clarification., Comment: 4 figures

В сложившейся экономической ситуации многие предприятия столкнулись с проблемой нехватки ликвидных средств, свободных денежных активов, которые могут быть направлены на реконструкцию производственных мощностей, наращивание объемов производственной деятельности. В данном случае актуально создание новых рыночных механизмов, направленных на привлечение свободных денежных средств инвесторов, ускорение оборачиваемости производства. Одним из таких механизмов является формирование холдингов на базе существующих предприятий.