Stationary Lifshitz black holes of R^2-corrected gravity theory

In this short note, I present a generalization of a set of static D-dimensional (D >= 3) Lifshitz black holes, which are solutions of the gravitational model obtained by amending the cosmological Einstein theory with the addition of only the curvature-scalar-squared term and that are described by two parameters, to a more general class of exact, analytic solutions that involves an additional parameter which now renders them stationary. In the special D=3 and the dynamical exponent z=1 case, the parameters can be adjusted so that the solution becomes identical to the celebrated BTZ black hole metric.Comment: 7 pages, no figures; ver. 2: added 5 new references (accepted by PRD as a Brief Report

Local cosmic strings in Brans-Dicke theory with a cosmological constant

It is known that Vilenkin's phenomenological equation of state for static straight cosmic strings is inconsistent with Brans-Dicke theory. We will prove that, in the presence of a cosmological constant, this equation of state is consistent with Brans-Dicke theory. The general solution of the full nonlinear field equations, representing the interior of a cosmic string with a cosmological constant is also presented.Comment: 5 pages, Revte

Spain’s referendum on the European Constitutional Treaty: a quantitative analysis within the conceptual framework of first and second order elections

In contrast to the attention devoted to the rejection of the EU Constitutional Treaty at French and Dutch referenda; the Spanish referendum, where this Treaty was ratified, remained under-researched by political scientists. This paper analyses the voting behaviour at the Spanish referendum on the EU Constitutional Treaty with the use of quantitative methods and the concept of first and second-order elections. This paper finds that the Spanish referendum was a second-order referendum, because the effects of domestic political issues in Spain had a greater impact on the electoral behaviour of Spanish voters than had genuinely European issues. This finding raises doubts over the suitability of using direct democracy in the EU in order to raise the legitimacy and democratic accountability of the European project

Harnessing bifurcations in tapping-mode atomic force microscopy to calibrate time-varying tip-sample force measurements

Torsional harmonic cantilevers allow measurement of time varying tip-sample forces in tapping-mode atomic force microscopy. Accuracy of these force measurements is important for quantitative nanomechanical measurements. Here we demonstrate a method to convert the torsional deflection signals into a calibrated force waveform with the use of non-linear dynamical response of the tapping cantilever. Specifically the transitions between steady oscillation regimes are used to calibrate the torsional deflection signals.Comment: 13 page

Classification of Occluded Objects using Fast Recurrent Processing

Recurrent neural networks are powerful tools for handling incomplete data problems in computer vision, thanks to their significant generative capabilities. However, the computational demand for these algorithms is too high to work in real time, without specialized hardware or software solutions. In this paper, we propose a framework for augmenting recurrent processing capabilities into a feedforward network without sacrificing much from computational efficiency. We assume a mixture model and generate samples of the last hidden layer according to the class decisions of the output layer, modify the hidden layer activity using the samples, and propagate to lower layers. For visual occlusion problem, the iterative procedure emulates feedforward-feedback loop, filling-in the missing hidden layer activity with meaningful representations. The proposed algorithm is tested on a widely used dataset, and shown to achieve 2$\times$ improvement in classification accuracy for occluded objects. When compared to Restricted Boltzmann Machines, our algorithm shows superior performance for occluded object classification.Comment: arXiv admin note: text overlap with arXiv:1409.8576 by other author

Position Space Feynman quadrics and their motives

In this note, we introduce and study position space Feynman quadrics that are the loci of divergences of the position space Feynman integrals for Euclidean massless scalar quantum field theories. We prove that the Feynman quadrics define objects in the category of mixed Tate motives for complete graphs with a bound on the number of vertices. This result shows a strong contrast with the graph hypersurfaces approach which produces also non-mixed Tate examples.Comment: 20 pages, 3 figure