Big Bang in AdS5AdS_{5} with external field and flat 4d Universe

We describe spontaneous creation of the Brane World in $AdS_{5}$ with external field. The resulting Brane World consists of a flat 4d spatially finite expanding Universe and curved expanding "regulator" branes. No negative tension branes are involved.Comment: Latex, 11 pages, 5 eps figures, references adde

Technical and Economical Substantiation of the Technology of Joint Pyrometallurgical Processing of Oxidized Nickel Ores and Sulfide Copper Ores

The technological scheme of processing of nickel and copper ores from the Urals deposits is substantiated, including calcination of oxidized nickel ore with limestone, partial oxidative roasting of sulfide copper ore, blending of calcines with coke, and melting of charge to obtain copper-nickel matte. The implementation of the scheme will increase the complexity of possible uses of raw materials and ensure a high environmental protection level. A feasibility study was carried out for the organization of industrial enterprise, which entailed the joint processing of oxidized nickel ores and sulfide copper ores with a capacity of 700,000 tons per year of a mixture of initial ores, including 400,000 tonnes of nickel ore and 300,000 tonnes of copper ore (dry weight). Finished products are: copper-nickel matte, containing not less than, wt.%: 3.3 Cu, 4.7 Ni, 0.6 Co, 1.5 g/t Au, 2.6 g/t Ag; granular slag containing, wt.%: 0.01–0.02 Ni, 0.01–0.02 Cu, 0.01–0.06 Co, 13–16 Fe, 44–50 SiO2, 13–14 MgO, 4–5 Al 2O3, 9–11 CaO; and technical grade sulfuric acid (mass fraction of monohydrate not less than 92.5 %). The planned enterprise is expected to produce the following annual volumes of finished products (not less than): 94,900 tonnes of matte; 512,300 tonnes of granular slag; and 235,500 tonnes of technical grade sulfuric acid. The estimated period of project implementation is 13 years. The total amount of investment costs is 1407 million roubles, current costs for the annual production program are 3820 million roubles. The financial results of the investment project are characterized by the following indicators: net profit is 5,735.5 million roubles, net discounted income is 1546.6 million roubles, the profitability index of discounted investments is 2.1, the internal rate of return is 36.4 %, and the discounted payback period is 5.5 years. The results indicate the viability and economic efficiency of the project. Keywords: ore, processing, sulfides, oxides, copper, nickel, cobalt, smelting, extraction, products, economy, indicators, efficienc

Semiclassical Calculation of Photon-Stimulated Schwinger Pair Creation

We consider the electron-positron pair creation by a photon in an external constant electric field. The presented treatment is based on a purely quasiclassical calculation of the imaginary part of the on-shell photon polarization operator. By using this approach we find the pair production rate for photons with polarization parallel as well as orthogonal to the external electric field in the leading order in the parameter $eE / m ^ 2$, which has been recently found by other methods. For the orthogonal polarization we also find a new contribution to the rate, which is leading in the ratio of the photon energy to the electron mass $\omega/m$. We also reproduce by a purely geometrical calculation the exponential factor in the probability of the stimulated pair creation at arbitrary energy of the photon.Comment: 16 pages, 4 figure

Decay of metastable current states in one-dimensional resonant tunneling devices

Current switching in a double-barrier resonant tunneling structure is studied in the regime where the current-voltage characteristic exhibits intrinsic bistability, so that in a certain range of bias two different steady states of current are possible. Near the upper boundary V_{th} of the bistable region the upper current state is metastable, and because of the shot noise it eventually decays to the stable lower current state. We find the time of this switching process in strip-shaped devices, with the width small compared to the length. As the bias V is tuned away from the boundary value V_{th} of the bistable region, the mean switching time \tau increases exponentially. We show that in long strips \ln\tau \propto (V_{th} -V)^{5/4}, whereas in short strips \ln\tau \propto (V_{th} -V)^{3/2}. The one-dimensional geometry of the problem enables us to obtain analytically exact expressions for both the exponential and the prefactor of \tau. Furthermore, we show that, depending on the parameters of the system, the switching can be initiated either inside the strip, or at its ends.Comment: 12 pages, 5 figures, update to published versio

Stochastic current switching in bistable resonant tunneling systems

Current-voltage characteristics of resonant-tunneling structures often exhibit intrinsic bistabilities. In the bistable region of the I-V curve one of the two current states is metastable. The system switches from the metastable state to the stable one at a random moment in time. The mean switching time \tau depends exponentially on the bias measured from the boundary of the bistable region V_{th}. We find full expressions for \tau (including prefactors) as functions of bias, sample geometry, and in-plane conductivity. Our results take universal form upon appropriate renormalization of the threshold voltage V_{th}. We also show that in large samples the switching initiates inside, at the edge, or at a corner of the sample depending on the parameters of the system.Comment: 21 pages, 5 figure

Turing Degrees in Refinements of the Arithmetical Hierarchy

© 2018, Springer Science+Business Media, LLC, part of Springer Nature. We investigate the problem of characterizing proper levels of the fine hierarchy (up to Turing equivalence). It is known that the fine hierarchy exhausts arithmetical sets and contains as a small fragment finite levels of Ershov hierarchies (relativized to ∅n, n < ω), which are known to be proper. Our main result is finding a least new (i.e., distinct from the levels of the relativized Ershov hierarchies) proper level. We also show that not all new levels are proper