The Running Gravitational Couplings

We compute the running of the cosmological constant and Newton's constant taking into account the effect of quantum fields with any spin between 0 and 2. We find that Newton's constant does not vary appreciably but the cosmological constant can change by many orders of magnitude when one goes from cosmological scales to typical elementary particle scales. In the extreme infrared, zero modes drive the cosmological constant to zero.Comment: 19 pages, TeX file, revised and expanded, some misprints correcte

Assessing drivers' preferences for hybrid electric vehicles (HEV) in Spain

With the aim of analyzing preferences for hybrid electric vehicles (HEVs), two stated preference methods (a contingent valuation exercise and a discrete choice experiment (DCE)) were used in a survey conducted in a representative sample of Spanish drivers. Overall, our findings show robustness between the willingness to pay (WTP) estimates elicited via a latent class model (LCM) and those from a payment card questionPostprint (published version

Black Hole Entropy as Causal Links

We model a black hole spacetime as a causal set and count, with a certain definition, the number of causal links crossing the horizon in proximity to a spacelike or null hypersurface $\Sigma$. We find that this number is proportional to the horizon's area on $\Sigma$, thus supporting the interpretation of the links as the ``horizon atoms'' that account for its entropy. The cases studied include not only equilibrium black holes but ones far from equilibrium.Comment: Latex, 20 pages, 4 postscript figures, to appear in a special issue of {\it Foundations of Physics} in honor of Jacob Bekenstein, ``Thirty years of black hole physics'', edited by L. Horwit