Theory of the Nernst effect near quantum phase transitions in condensed matter, and in dyonic black holes

We present a general hydrodynamic theory of transport in the vicinity of superfluid-insulator transitions in two spatial dimensions described by "Lorentz"-invariant quantum critical points. We allow for a weak impurity scattering rate, a magnetic field B, and a deviation in the density, \rho, from that of the insulator. We show that the frequency-dependent thermal and electric linear response functions, including the Nernst coefficient, are fully determined by a single transport coefficient (a universal electrical conductivity), the impurity scattering rate, and a few thermodynamic state variables. With reasonable estimates for the parameters, our results predict a magnetic field and temperature dependence of the Nernst signal which resembles measurements in the cuprates, including the overall magnitude. Our theory predicts a "hydrodynamic cyclotron mode" which could be observable in ultrapure samples. We also present exact results for the zero frequency transport co-efficients of a supersymmetric conformal field theory (CFT), which is solvable by the AdS/CFT correspondence. This correspondence maps the \rho and B perturbations of the 2+1 dimensional CFT to electric and magnetic charges of a black hole in the 3+1 dimensional anti-de Sitter space. These exact results are found to be in full agreement with the general predictions of our hydrodynamic analysis in the appropriate limiting regime. The mapping of the hydrodynamic and AdS/CFT results under particle-vortex duality is also described.Comment: 44 pages, 4 figures; (v3) Added new subsection highlighting negative Hall resistance at hole densities smaller than 1/

The effect of herbicides on seed productivity of Festulolium

ArticleAn artificially developed intergeneric hybrid Festulolium (+Festulolium F. Aschers, et Graebn.) is the best forage crop with high energy and protein nutrition value which can be used for green fodder when creating cultural haylands and pastures. The advantages of this crop are high regrow capacity, high content of sugars and good winter hardiness. Wide use of this new crop in fodder production is constrained, firstly, because the crop is yet new and little known and, secondly, because there is a lack of seeds due to imperfections in the production technology. There are still very few scientific studies on the biology and technology of Festulolium cultivation in the forest-steppe of the Central Chernozem Region of Russia. In our works we were the first to study the biological features of Festulolium and develop the main technological methods of growing and harvesting its seeds. The work was carried out in long-term studies of the Department of Crop Science, Forage Production and Agricultural Technologies of Voronezh State Agrarian University in 2009 2011. The soil in the experimental plot was leached medium loamy chernozem. The experiments involved the VIK-90 Festulolium variety with the preceding crop being the vetch-oat mixture harvested for green fodder. The soil preparation was conventional for seed herbage of perennial grasses in the Central Chernozem Region. The associated records and observations were made according to conventional methods adopted in the seed production of perennial grasses. A high efficiency of the Aurorex (0.55 L ha -1 ) and the Dicamba (0.15 L ha -1 ) herbicides in the suppression of annual and perennial dicotyledonous weed plants has been identified. The application of these herbicides has significantly reduced (by 40-73%) the weed infestation of seed herbage in the first year of vegetation and, as a result, has improved its structure and crop quality. The use of the developed agricultural techniques allows reducing the energy costs and receiving an average of 433 496 kg ha -1 of certified seeds

Festulolium seed production dependence on fertilizer application system

ArticleFestulolium ( × Festulolium F. Aschers. et Graebn.) is a new perennial grass Роасеае family. The benefits of this culture are good regrow capacity, increased sugars content and higher winter hardiness. It can be used as a green feed when c reating cultivated hayfields and pastures. Widespread application of this new culture for forage production is constrained by the shortage of seeds, due to the imperfection of their production technologies. There are still very few of studies on the biolog y and technology of Festulolium cultivation in the forest - steppe of the Central Chernozem Region of Russia (CCR). The experiments involved the VIC - 90 Festulolium variety with the first crop being the vetch - oat mixture harvested for green fodder. The soil in the experimental plots was leached medium thick medium loamy chernozem. The humus content in the arable horizon was 4.56%, pH was 4.9, degree of base saturatio n was 74‒86%, P 2 O 5 content was 129 mg kg - 1 , K 2 O content was 115 mg kg - 1 (according to Chirikov) and the hydrothermal index was 1.13. The experiment included the following variants: no fertilizer application (control) and application of mineral fertilizers (ammonium nitrate and ammonium nitrate phosphate fertilizer) at different doses. Soil preparation was conventional for seed swards of perennial grasses in the CCR. Festulolium was sown in broad drills by coverless sowing to the depth of 0.5 – 1.0 cm at the s eeding rate of 6.0 kg ha - 1 . Experiments, records, observations and determination of economic and bioenergetic efficiency were carried out according to conventional procedures. It was found that the climatic conditions in the forest steppe of the CCR were f avorable for Festulolium seed cultivation. Application of mineral nitrogen fertilizers in autumn at a dose of 60 kg ha - 1 of active ingredient (AI) ensures the formation of high yielding erect seed - producing sward, and can increase harvest energy efficiency an average by 1.45‒1.82 times and obtain 591‒620 kg ha - 1 of certified seeds. The greatest profitability of production (179%) and the highest notional farm net income (RUB 43,000 per hectare) are provided by a single application of ammonium nitrate fertili zer at a dose of 60 kg ha - 1 of active ingredient in autumn (after vegetative mass topping)

Film agents as an effective means of reducing seed shattering in Festulolium

ArticleIn the conditions of the forest steppe of the Central Chernozem region, methods were studied to reduce shatter losses in the pre-harvesting period for Festulolium during the period 2009–2011, applying the film forming agents, Elastik (0.8–1.2 L ha-1), Bifaktor (0.8–1.2 L ha-1), and Metylan Universal Premium (1.4–3.8 kg ha-1). The agents were used at seed humidity levels of between 60–65%. Following anti-shattering treatment, seed moisture content gradually decreased. The application of film forming agents prevented seed shattering, and seeds were harvested by direct combining at a humidity of between 20–25% without heavy losses being suffered. Moreover, decreased seed losses due to film forming agents significantly reduced the cost of seed heap drying. In the control treatment, the seed yield amounted to 214.8 kg ha-1, and 360.7 kg ha-1 was lost as a result of natural seed shattering in the process of ripening. The Elastik and Bifaktor preparations prevented seed shattering and contributed to the preservation of a seed yield of between 522.1–563.5 kg ha-1. The application of film forming agents contributed to a reduction in losses during harvesting within the range of 9.7–16.8%. Application of the Metylan Universal Premium glue in the studied doses provided a significant increase of seed yield. The highest seed yield (490.1–495.2 kg ha-1) was obtained in the treatment which used a Metylan application at a dose of 3.0–3.4 kg ha-1, where seed shattering was reduced by 14.8–17.6%

Search for Anomalous Top--Quark Interaction at LEP-2 Collider

We show that a search for $e^+ e^- \to t \bar q$ $(\bar q = \bar c, \bar u)$ events at LEP--2 collider provide a possibility to improve significantly the modern constraints on coupling constants of anomalous $t$--quark interaction via flavor--changing neutral currents.Comment: 12 pages, LaTeX, epsfig, 4 figures. Corrected typo

Thermohydrodynamics in Quantum Hall Systems

A theory of thermohydrodynamics in two-dimensional electron systems in quantizing magnetic fields is developed including a nonlinear transport regime. Spatio-temporal variations of the electron temperature and the chemical potential in the local equilibrium are described by the equations of conservation with the number and thermal-energy flux densities. A model of these flux densities due to hopping and drift processes is introduced for a random potential varying slowly compared to both the magnetic length and the phase coherence length. The flux measured in the standard transport experiment is derived and is used to define a transport component of the flux density. The equations of conservation can be written in terms of the transport component only. As an illustration, the theory is applied to the Ettingshausen effect, in which a one-dimensional spatial variation of the electron temperature is produced perpendicular to the current.Comment: 10 pages, 1 figur

Oscillations of the Nernst coefficient in bismuth

We calculate the magnetic-field dependence (oscillations) of the Nernst coefficient in bismuth at low temperatures for the case when the magnetic field is directed along the trigonal axis of the crystal. In the calculations we take into account the scattering of the electrons and holes in bismuth on impurities and the dependence of this scattering on the magnetic field. The results of these calculations are compared with the experimental data recently published