Quantum cosmology and the accelerated Universe

The quantized Friedmann-Lema\^{\i}tre-Robertson-Walker (FLRW) model minimally coupled to a free massless scalar field is studied and interpreted in the Bohm-de Broglie framework. We analyze the quantum bohmian trajectories corresponding to a certain class of gaussian packets, solutions of the Wheeler-DeWitt equation. We show that these bohmian trajectories undergo an accelerated expansion in the middle of its evolution due to the presence of quantum cosmological effects in this period. It is shown that the luminosity-redshift relation in the quantum cosmological model can be made close to the corresponding relation coming from the classical model suplemented by a cosmological constant, for $z<1$. In this way we have the posibility of interpreting the present observations of high redshift supernovae as the consequence of a quantum cosmological effect.Comment: Talk given at X Marcell Grossmann Meeting, Rio de Janeiro, 2003. Added references and some minor typos correction

Might EPR particles communicate through a wormhole?

We consider the two-particle wave function of an Einstein-Podolsky-Rosen system, given by a two dimensional relativistic scalar field model. The Bohm-de Broglie interpretation is applied and the quantum potential is viewed as modifying the Minkowski geometry. In this way an effective metric, which is analogous to a black hole metric in some limited region, is obtained in one case and a particular metric with singularities appears in the other case, opening the possibility, following Holland, of interpreting the EPR correlations as being originated by an effective wormhole geometry, through which the physical signals can propagate.Comment: Corrected version, to appears in EP

Human equilibrative nucleoside transporter 1 (hENT1) levels predict response to gemcitabine in patients with biliary tract cancer (BTC)

Background and aim: Translational data suggest that nucleoside transporters, in particular human equilibrative nucleoside transporter 1 (hENT1), play an important role in predicting clinical outcome after gemcitabine chemotherapy for several types of cancer. The aim of this study was to retrospectively determine patients' outcome according to the expression of hENT1 in tumoral cells of patients receiving gemcitabine-based therapy. Materials and Methods: The immunohistochemistry analysis was performed on samples from thirty-one patients with unresectable biliary tract cancer (BTC) consecutively treated with first line gemcitabine-based regimens. Results: Positive hENT1 staining patients were 21 (67.7%); negative hENT1 staining patients were 10 (32.3%). Statistical analysis revealed no association between baseline characteristics, toxicities and tumor response to gemcitabine and hENT1 levels. In the univariate analysis, HENT1 expression was significantly correlated with time to progression (TTP) (p=0.0394; HR 2.902, 95%CI 1.053-7.996). The median TTP was 6.33 versus 2.83 months, respectively in patients with positive versus negative hENT1 staining. Moreover, patients with positive hENT1 expression showed a longer median overall survival when compared with patients with low hENT1 expression (14 versus 7 months, respectively), but this difference did not reach the statistical significance (p=0.128). Conclusions: Therefore, hENT1 may be a relevant predictive marker of benefit from gemcitabine-based therapies in patients with advanced BTC. © 2011 Bentham Science Publishers Ltd