9,640 research outputs found
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
Spainâs 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 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
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