A self-adapting latency/power tradeoff model for replicated search engines

For many search settings, distributed/replicated search engines deploy a large number of machines to ensure efficient retrieval. This paper investigates how the power consumption of a replicated search engine can be automatically reduced when the system has low contention, without compromising its efficiency. We propose a novel self-adapting model to analyse the trade-off between latency and power consumption for distributed search engines. When query volumes are high and there is contention for the resources, the model automatically increases the necessary number of active machines in the system to maintain acceptable query response times. On the other hand, when the load of the system is low and the queries can be served easily, the model is able to reduce the number of active machines, leading to power savings. The model bases its decisions on examining the current and historical query loads of the search engine. Our proposal is formulated as a general dynamic decision problem, which can be quickly solved by dynamic programming in response to changing query loads. Thorough experiments are conducted to validate the usefulness of the proposed adaptive model using historical Web search traffic submitted to a commercial search engine. Our results show that our proposed self-adapting model can achieve an energy saving of 33% while only degrading mean query completion time by 10 ms compared to a baseline that provisions replicas based on a previous day's traffic

Methods for processing ash residues of TPS vanadium containing slurry

Application of vanadium industrial waste complex processing provides the decision of two main tasks: expanding the raw material base for extremely scarce metal and reduction of an environmental impact on nature. Combined and hydrometallurgical methods of vanadium extraction from the ash residues of TPS vanadium sludge have been developed. These methods allow to extract up to 95% of vanadium that contains in waste, and to obtain a vanadium product suitable for using in different areas of industry

Subexponential estimations in Shirshov's height theorem (in English)

In 1993 E. I. Zelmanov asked the following question in Dniester Notebook: "Suppose that F_{2, m} is a 2-generated associative ring with the identity x^m=0. Is it true, that the nilpotency degree of F_{2, m} has exponential growth?" We show that the nilpotency degree of l-generated associative algebra with the identity x^d=0 is smaller than Psi(d,d,l), where Psi(n,d,l)=2^{18} l (nd)^{3 log_3 (nd)+13}d^2. We give the definitive answer to E. I. Zelmanov by this result. It is the consequence of one fact, which is based on combinatorics of words. Let l, n and d>n be positive integers. Then all the words over alphabet of cardinality l which length is greater than Psi(n,d,l) are either n-divided or contain d-th power of subword, where a word W is n-divided, if it can be represented in the following form W=W_0 W_1...W_n such that W_1 >' W_2>'...>'W_n. The symbol >' means lexicographical order here. A. I. Shirshov proved that the set of non n-divided words over alphabet of cardinality l has bounded height h over the set Y consisting of all the words of degree <n. Original Shirshov's estimation was just recursive, in 1982 double exponent was obtained by A.G.Kolotov and in 1993 A.Ya.Belov obtained exponential estimation. We show, that h<Phi(n,l), where Phi(n,l) = 2^{87} n^{12 log_3 n + 48} l. Our proof uses Latyshev idea of Dilworth theorem application.Comment: 21 pages, Russian version of the article is located at the link arXiv:1101.4909; Sbornik: Mathematics, 203:4 (2012), 534 -- 55

Electron screening and excitonic condensation in double-layer graphene systems

We theoretically investigate the possibility of excitonic condensation in a system of two graphene monolayers separated by an insulator, in which electrons and holes in the layers are induced by external gates. In contrast to the recent studies of this system, we take into account the screening of the interlayer Coulomb interaction by the carriers in the layers, and this drastically changes the result. Due to a large number of electron species in the system (two projections of spin, two valleys, and two layers) and to the suppression of backscattering in graphene, the maximum possible strength of the screened Coulomb interaction appears to be quite small making the weak-coupling treatment applicable. We calculate the mean-field transition temperature for a clean system and demonstrate that its highest possible value $T_c^\text{max}\sim 10^{-7}\epsilon_F\lesssim 1 \text{mK}$ is extremely small ($\epsilon_F$ is the Fermi energy). In addition, any sufficiently short-range disorder with the scattering time $\tau \lesssim \hbar /T_c^\text{max}$ would suppress the condensate completely. Our findings renders experimental observation of excitonic condensation in the above setup improbable even at very low temperatures.Comment: 4+ pages, 3 figure

Evaluation of energy metabolism in calves on the use of energy substrates

Adequate nutrition of ruminants and physiologically correct assessment of the nutritional value of feed rations need additional knowledge about the quantitative transformation of the main components of any particular feed in different parts of the digestive tract. The study of the principles of substrate energy use is necessary in each particular case to define the actual need in substrates, which determines the efficiency of their use for implementing biosynthesis and physiological functions. The determination of the influence of the energy supply of the diet of young cattle aged 7-12 months on the efficiency of energy use in the organism. Efficiency of the use of metabolizable energy of diets for calves with the increased level of energy nutritional value by 5.0% (MEC is equal to 9.6 MJ/kg) promoted the increase of energy deposition and weight gain synthesis by 10.04%, weight gain energy by 19.50%, the efficiency of the use of metabolizable energy for weight gain by 3.81%

Coulomb interaction and magnetic catalysis in the quantum Hall effect in graphene

The dynamics of symmetry breaking responsible for lifting the degeneracy of the Landau levels in the integer quantum Hall effect in graphene is studied in a low-energy model with the Coulomb interaction. The gap equation for Dirac quasiparticles is analyzed for both the lowest and higher Landau levels, taking into account the Landau levels mixing. It is shown that the characteristic feature of the long-range Coulomb interaction is the decrease of the gap parameters with increasing the Landau level index $n$ ("running" gaps). The renormalization (running) of the Fermi velocity as a function of $n$ is also studied. The solutions of the gap equation reproduce correctly the experimentally observed integer quantum Hall plateaus in graphene in strong magnetic fields.Comment: 22 pages, 5 figures; Final version published in the Proceedings of the 2010 Nobel Symposium on Graphene and Quantum Matte

Genetic control of traits determining phosphorus uptake by rice varieties (Oryza sativa L.)

The objectives of this research are: (1) to find genetic material associated with high growth rate and maximum size of root system, (2) to study polymorphism of rice varieties for markers connected with genes defining effective utilization of phosphorus, (3) to estimate the possibility of using listed SSR markers for introgression of previously mapped genes, and (4) to classify donor accessions found in the Russian gene pool into groups according to the probability of stability formation by various genetic mechanisms. Traits determining the rate of phosphorus uptake by rice varieties and their inheritance are discussed. Polymorphism of 72 rice accessions of Russian and foreign breeding by the rate of the formation of the root system and its size at maturity is considered. The highest rates of root system formation are found in varieties Liman, Arborio, Dalnevostochnyi, Selenio, Oceano, Atlant, Musa, Fontan, Cerere, Sharm, Serpentine, Khankaiskii 52, Leader, Boyarin, and Druzhnyi. Russian varieties outperform Italian ones in growth rate. Root weights at the maturation stage varied from 1,5 to 4,5 grams. Varieties Carnise, Rapan, Onix and G-57 display the greatest root weights at the maturation stage. Root lengths at the maturation stage varied from 17 to 26 cm. Varieties D 25-2, G 75-5, Ryzhik, G-52, Krepysh, and Snezhinka had the maximum values. Study of polymorphism of Russian and foreign varieties on the markers associated with the genes determining uptake of phosphorus has revealed polymorphism for all markers; thus, marker-assisted selection can be applied to them in breeding for this trait. The maximum number of alleles is noted for the RM 247 marker, located on chromosome 12

Excitonic condensation in a double-layer graphene system

The possibility of excitonic condensation in a recently proposed electrically biased double-layer graphene system is studied theoretically. The main emphasis is put on obtaining a reliable analytical estimate for the transition temperature into the excitonic state. As in a double-layer graphene system the total number of fermionic "flavors" is equal to N=8 due to two projections of spin, two valleys, and two layers, the large-$N$ approximation appears to be especially suitable for theoretical investigation of the system. On the other hand, the large number of flavors makes screening of the bare Coulomb interactions very efficient, which, together with the suppression of backscattering in graphene, leads to an extremely low energy of the excitonic condensation. It is shown that the effect of screening on the excitonic pairing is just as strong in the excitonic state as it is in the normal state. As a result, the value of the excitonic gap \De is found to be in full agreement with the previously obtained estimate for the mean-field transition temperature $T_c$, the maximum possible value $\Delta^{\rm max},T_c^{\rm max}\sim 10^{-7} \epsilon_F$ ($\epsilon_F$ is the Fermi energy) of both being in $1{\rm mK}$ range for a perfectly clean system. This proves that the energy scale $\sim 10^{-7} \epsilon_F$ really sets the upper bound for the transition temperature and invalidates the recently expressed conjecture about the high-temperature first-order transition into the excitonic state. These findings suggest that, unfortunately, the excitonic condensation in graphene double-layers can hardly be realized experimentally.Comment: 21 pages, 5 figures, invited paper to Graphene special issue in Semiconductor Science and Technolog