Thermal Conditions for Scalar Bosons in a Curved Space Time

The conditions that allow us to consider the vacuum expectation value of the energy-momentum tensor as a statistical average, at some particular temperature, are given. When the mean value of created particles is stationary, a planckian distribution for the field modes is obtained. In the massless approximation, the temperature dependence is as that corresponding to a radiation dominated Friedmann-like model.Comment: 14 pages (TeX manuscript

Particle creation, renormalizability conditions and the mass-energy spectrum in gravity theories of quadratic Lagrangians

Massive scalar particle production, due to the anisotropic evolution of a five-dimensional spacetime, is considered in the context of a quadratic Lagrangian theory of gravity. Those particles, corresponding to field modes with non-vanishing momentum component along the fifth dimension, are created mostly in the neighbourhood of a singular epoch where only their high-frequency behaviour is of considerable importance. At the 1-loop approximation level, general renormalizability conditions on the physical quantities relevant to particle production are derived and discussed. Exact solutions of the resulting Klein-Gordon field equation are obtained and the mass-energy spectrum attributed to the scalar field due to the cosmological evolution is being investigated further. Finally, analytic expressions regarding the number and the energy density of the created particles at late times, are also derived and discussed.Comment: LaTeX file, 23 page

Shielding and shadowing: a tale of two strategies for opinion control in the voting dynamics

This paper focuses on influence maximization or opinion control in the voting dynamics on social networks. We show two simple heuristics that are effective strategies to enhance vote shares: (i) avoiding the nodes controlled by your opponent when having a lower budget while focusing on them when having a larger budget (shadowing) and (ii) ring-fencing her influence by targeting control on adjacent nodes (shielding). The paper presents an empirical numerical evaluation of these strategies for various classes of complex networks which is backed up by analytical results obtained via a mean-field approach, in good agreement with numerical results. Importantly, we also show that optimal influence allocations tend to not be localized, but can include targeting nodes significant distances away from opposing influence

Large network inference: new insights in health economics

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