A radiation-like era before inflation

We show that the semiclassical approximation to the Wheeler-DeWitt equation for the minisuperspace of a minimally coupled scalar field in the spatially flat de Sitter Universe prompts the existence of an initial power-law evolution driven by non-adiabatic terms from the gravitational wavefunction which act like radiation. This simple model hence describes the onset of inflation from a previous radiation-like expansion during which the cosmological constant is already present but subleading.Comment: LaTeX, 8 pages, no figures; final version to be published in JCA

Hints of (trans-Planckian) asymptotic freedom in semiclassical cosmology

We employ the semiclassical approximation to the Wheeler-DeWitt equation in the spatially flat de Sitter Universe to investigate the dynamics of a minimally coupled scalar field near the Planck scale. We find that, contrary to naive intuition, the effects of quantum gravitational fluctuations become negligible and the scalar field states asymptotically approach plane-waves at very early times. These states can then be used as initial conditions for the quantum states of matter to show that each mode essentially originated in the minimum energy vacuum. Although the full quantum dynamics cannot be solved exactly for the case at hand, our results can be considered as supporting the general idea of asymptotic safety in quantum gravity.Comment: 11 pages, 2 figures; replaced to match content of published versio

Multicenter retrospective study on management and outcome of newborns affected by surgical necrotizing enterocolitis

BACKGROUND: Necrotizing enterocolitis (NEC) is the most common surgical emergency in newborns and it is still a leading cause of death despite the improvements reached in the management of the critically ill neonate. The purpose of this study was to evaluate risk factors, surgical treatments and outcome of surgical NEC.METHODS: We retrospectively evaluated a multicentric group of 184 patients with surgical NEC over a period of 5 years (2008-2012). Indications to operation were modified NEC Bell stages IIIA or IIIB. The main outcome was measured in terms of survival and postsurgical complications.RESULTS: Data on 184 patients who had a surgical NEC were collected. The majority of patients (153) had a primary laparotomy (83%); 10 patients had peritoneal drainage insertion alone (5%) and 21 patients had peritoneal drainage followed by laparotomy (12%). Overall mortality was 28%. Patients with lower gestational age (P=0.001), lower birth weight (P=0.001), more extensive intestinal involvement (P=0.002) and cardiac diseases (P=0.012) had a significantly higher incidence of mortality. There was no statistically significant association between free abdominal air on the X-ray and mortality (P=0.407). Mortality in the drainage group was 60%, in the laparotomy group and drainage followed by laparotomy group was of 23-24% (P=0.043). There was a high incidence of stenosis (28%) in the drainage group (P=0.002). On multivariable regression, lower birth weight, feeding, bradycardia-desaturation and extent of bowel involvement were independent predictors of mortality.CONCLUSIONS: Laparotomy was the most frequent method of treatment (83%). Primary laparotomy and drainage with laparotomy groups had similar mortalities (23-24%), while the drainage alone treatment cohort was associated with the highest mortality (60%) with statistical value (P=0.043). Consequently laparotomy is highly protective in terms of survival rate. Stenosis seemed to be statistically associated with drainage. These findings could discourage the use of peritoneal drainage versus a primary laparotomy whenever the clinical conditions of patients allow this procedure