The Kelvin Formula for Thermopower

Thermoelectrics are important in physics, engineering, and material science due to their useful applications and inherent theoretical difficulty, especially in strongly correlated materials. Here we reexamine the framework for calculating the thermopower, inspired by ideas of Lord Kelvin from 1854. We find an approximate but concise expression, which we term as the Kelvin formula for the the Seebeck coefficient. According to this formula, the Seebeck coefficient is given as the particle number $N$ derivative of the entropy $\Sigma$, at constant volume $V$ and temperature $T$, $S_{\text{Kelvin}}=\frac{1}{q_e}\{\frac{\partial {\Sigma}}{\partial N} \}_{V,T}$. This formula is shown to be competitive compared to other approximations in various contexts including strongly correlated systems. We finally connect to a recent thermopower calculation for non-Abelian fractional quantum Hall states, where we point out that the Kelvin formula is exact.Comment: 6 pages, 2 figure

Thermopower as a Possible Probe of Non-Abelian Quasiparticle Statistics in Fractional Quantum Hall Liquids

We show in this paper that thermopower is enhanced in non-Abelian quantum Hall liquids under appropriate conditions. This is because thermopower measures entropy per electron in the clean limit, while the degeneracy and entropy associated with non-Abelian quasiparticles enhance entropy when they are present. Thus thermopower can potentially probe non-Abelian nature of the quasiparticles, and measure their quantum dimension.Comment: 5 pages. Minor revisions in response to referee comments. Published versio

Thermopower of Two-Dimensional Electrons at ν\nu = 3/2 and 5/2

The longitudinal thermopower of ultra-high mobility two-dimensional electrons has been measured at both zero magnetic field and at high fields in the compressible metallic state at filling factor $\nu = 3/2$ and the incompressible fractional quantized Hall state at $\nu = 5/2$. At zero field our results demonstrate that the thermopower is dominated by electron diffusion for temperatures below about $T = 150$ mK. A diffusion dominated thermopower is also observed at $\nu = 3/2$ and allows us to extract an estimate of the composite fermion effective mass. At $\nu = 5/2$ both the temperature and magnetic field dependence of the observed thermopower clearly signal the presence of the energy gap of this fractional quantized Hall state. We find that the thermopower in the vicinity of $\nu = 5/2$ exceeds that recently predicted under the assumption that the entropy of the 2D system is dominated by non-abelian quasiparticle exchange statistics.Comment: 10 pages, 10 figures

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/

Revision der palaearktische arten der gattungen Nycteola Hb. und Erschoviella gen. nov. (Lepidoptera, Nycteolidae)

Número abril-diciembreNach dem Katalog von Staudinger Sz. Rebel (Cat. Lep. Pal. Faun., 1, 1901, p. 361) wurden zur Gattung Sarrothripus Curt , drei palaearktische Arten gestellt, und zwar : revayana Sc., musculana Ersch. und nilotica Rghfr. Von diesen hat Hampson (Cat. Lep. Phal., XI, 1912, p. 231) die letzterwähnte Art in die Gattung Characorna Wkr. übertragen, zu Sarrothripus Curt. aber neben den zahlreichen ausserpalaearktischen Arten noch die wenig bekannte coreana Leech gestellt (Hampson, op. cit., p. 266, -t. CLXXXI, fig. 5). Hampson ebenso wie später Warren (in : Seitz, Gross-Schm. d. Erde, III, 1913, p. 290), hat zu revayana neben ihren zahlreichen Formen auch degenerana (Hb.) Hw. zugezogen, obwohl die Artrechte dieser Form schon durch die Studien von Klos & 1Vleixner (Verh. z.-b. Ges. Wien, LVII, 19° 7, Berichte, pp. i73-174) bewiesen wurden und sie bei Spuler (Schm. Eur., II, 1910, p. 49 1) wie auch bei Rebel (Berge's Schmetterlingsbuch, 1910, pp. 421-422) als eine selbständige Art angeführt ist. Später hat Filipjev (Ann. Mus. Zool. Acad. Sci. URSS, XXVIII, 1927, p. 260) in einer seiner faunistischen Arbeiten die als eine revayana-Form beschriebene asiatica Krul. für eine eigene Art erklärt (ohne dies näher zu begründen) und beabsichtigte der Gattung Sarrothripus Curt. eine Revision zu widmen, was leider unerfüllt blieb.Peer reviewe

Double Top Production at Hadronic Colliders

We calculate the contribution of anomalous top-quark interaction with a gluon, photon, and $Z$-boson (FCNC) to $t \bar t$ pair production in hadronic collisions. Using the current data from Run~1 of the Tevatron we evaluate the upper limit on the the anomalous coupling of $t$-quark with gluon, $|\kappa_g/\Lambda| \le 0.52$ TeV$^{-1}$. We examine the production of double top ($t t$ or $\bar t \bar t$) at hadronic colliders as a result of FCNC interactions of the top quark. It is shown that the study of such reactions at LHC collider makes possible to obtain the constraint on strength of coupling at the level of $|\kappa_g /\Lambda| \le 0.09$ TeV$^{-1}$.Comment: 16 pages, LaTeX, epsfig, 12 figure

Recognition With Learning As a Problem of Choice

The paper highlights a problem of pattern recognition with learning as a part of a wider problem of choice. It is shown that by information basis the problem can be compared with problems of formulae classification in sentence calculus and logical diagnostics. A family of algorithms is constructed that can be used for solving any of the above-mentioned problems. It is shown that an algorithm from the family can be compared with classical ones (method of resolution, etc), and, therefore, is justified at least in the algorithmic sense