Fine Tuning in Quintessence Models with Exponential Potentials

We explore regions of parameter space in a simple exponential model of the form $V = V_0 e^{- \lambda \frac{Q}{M_p}}$ that are allowed by observational constraints. We find that the level of fine tuning in these models is not different from more sophisticated models of dark energy. We study a transient regime where the parameter $\lambda$ has to be less than $\sqrt{3}$ and the fixed point $\Omega_Q = 1$ has not been reached. All values of the parameter $\lambda$ that lead to this transient regime are permitted. We also point out that this model can accelerate the universe today even for $\lambda > \sqrt{2}$, leading to a halt of the present acceleration of the universe in the future thus avoiding the horizon problem. We conclude that this model can not be discarded by current observations.Comment: 15 pages, 8 figure

Model independent constraints on mass-varying neutrino scenarios

Models of dark energy in which neutrinos interact with the scalar field supposed to be responsible for the acceleration of the universe usually imply a variation of the neutrino masses on cosmological time scales. In this work we propose a parameterization for the neutrino mass variation that captures the essentials of those scenarios and allows to constrain them in a model independent way, that is, without resorting to any particular scalar field model. Using WMAP 5yr data combined with the matter power spectrum of SDSS and 2dFGRS, the limit on the present value of the neutrino mass is $m_0 \equiv m_{\nu}(z=0) < 0.43 (0.28)$ eV at 95% C.L. for the case in which the neutrino mass was lighter (heavier) in the past, a result competitive with the ones imposed for standard (i.e., constant mass) neutrinos. Moreover, for the ratio of the mass variation of the neutrino mass $\Delta m_{\nu}$ over the current mass $m_0$ we found that $\log[|\Delta m_{\nu}|/m_0] < -1.3 (-2.7)$ at 95% C.L. for $\Delta m_{\nu} 0)$, totally consistent with no mass variation. These stringent bounds on the mass variation are not related to the neutrino free-streaming history which may affect the matter power spectrum on small scales. On the contrary, they are imposed by the fact that any significant transfer of energy between the neutrino and dark energy components would lead to an instability contradicting CMB and large scale structure data on the largest observable scales.Comment: 13 pages, 7 figures, 2 tables. Some few comments and references added. To be published in PR

Ruxolitinib – better prognostic impact in low-intermediate 1 risk score: evaluation of the ‘rete ematologica pugliese’ (REP) in primary and secondary myelofibrosis

We evaluated ruxolitinib in 65 patients with myelofibrosis according to age, sex, time of diagnosis, grade of fibrosis, prognostic score risk, Janus kinase (JAK) status, primary or secondary myelofibrosis, previous treatment, and dosage. Outcome measures were response rate, time to response, duration of response, and event-free survival and survival. Kaplan and Meier curves show a significant difference in event-free survival according to the prognostic score, in favor of patients with low int1 (p = 0.0009). The Cox stepwise model confirmed the result, the int2 high-risk score being the most powerful negative independent parameter (0.001), followed by JAK (0.008); other parameters, such as diagnosis more than 5 years earlier, grade III–IV fibrosis, and ruxolitinib dose have a negligible impact. Time to response was shorter (p = 0.001) in primary myelofibrosis. In conclusion, ruxolitinib is effective, with a better outcome in patients with a low-int1 risk score. This may suggest considering an earlier administration in the disease course

The clinical effectiveness of an integrated multidisciplinary evidence-based program to prevent intraoperative pressure injuries in high-risk children undergoing long-duration surgical procedures: a quality improvement study

The prevention of hospital-acquired pressure injuries (HAPIs) in children undergoing long-duration surgical procedures is of critical importance due to the potential for catastrophic sequelae of these generally preventable injuries for the child and their family. Long-duration surgical procedures in children have the potential to result in high rates of HAPI due to physiological factors and the difficulty or impossibility of repositioning these patients intraoperatively. We developed and implemented a multi-modal, multi-disciplinary translational HAPI prevention quality improvement program at a large European Paediatric University Teaching Hospital. The intervention comprised the establishment of wound prevention teams, modified HAPI risk assessment tools, specific education, and the use of prophylactic dressings and fluidized positioners during long-duration surgical procedures. As part of the evaluation of the effectiveness of the program in reducing intraoperative HAPI, we conducted a prospective cohort study of 200 children undergoing long-duration surgical procedures and compared their outcomes with a matched historical cohort of 200 children who had undergone similar surgery the previous year. The findings demonstrated a reduction in HAPI in the intervention cohort of 80% (p &lt; 0.01) compared to the comparator group when controlling for age, pathology, comorbidity, and surgical duration. We believe that the findings demonstrate that it is possible to significantly decrease HAPI incidence in these highly vulnerable children by using an evidence-based, multi-modal, multidisciplinary HAPI prevention strategy

Cosmological implications of some nonstandard particle physics scenarios

203 páginas. Tesis doctoral del Departamento de Física Teórica, de la Universidad de Valencia. Fecha de lectura: 3 octubre 2012.The standard cosmological model has been very successful in describing the evolution of the Universe from the first seconds until today. However, some challenges still remain concerning the nature of some of its components as well as observationally probing some of the periods of its expansion. In this thesis we discuss what are probably the three least known components of the Universe: neutrinos, dark matter, and dark energy. In particular, concerning the neutrino sector, we place limits on the relic neutrino asymmetries using some of the latest cosmological data, taking into account the effect of flavor oscillations. We find that the present bounds are still dominated by the limits coming from big bang nucleosynthesis, while the limits on the total neutrino mass from cosmological data are essentially independent of 13. Moreover, we perform a forecast for Cosmic Origins Explorer, taken as an example of a future cosmic microwave background experiment, and find that it could improve the limits on the total lepton asymmetry. We also consider models of dark energy in which neutrinos interact with the scalar field sup- posed to be responsible for the acceleration of the Universe, usually implying a variation of the neutrino masses on cosmological time scales. We propose a parameterization for the neutrino mass variation that captures the essentials of those scenarios and allows one to constrain them in a model independent way, that is, without resorting to any particular scalar field model. Using different datasets we show that the ratio of the mass variation of the neutrino mass over the current mass is smaller than ≈ 10−2 at 95% C.L., totally consistent with no mass variation. Finally, we discuss how observations of the 21-cm line of the atomic hydrogen at the early universe have the potential to probe the unexplored period between the so-called dark ages and the reionization epoch of the Universe, and how it can be used to place limits on particle physics properties, in particular constraints on the mass and self-annihilation cross-section of the dark matter particles