How many water molecules are needed to solvate one?

Many efforts undertaken to study the solvation process have led to general theories that may describe mean properties, but are unable to provide a detailed understanding at the molecular level. Remarkably, the basic question of how many solvent molecules are necessary to solvate one solute molecule is still open. By exploring several water aggregates of increasing complexity, in this contribution we employ semiclassical spectroscopy to determine on quantum dynamical grounds the minimal network of surrounding water molecules to make the central one display the same vibrational features of liquid water.

Caldeira-Leggett model vs ab initio potential: A vibrational spectroscopy test of water solvation.

We present a semiclassically approximate quantum treatment of solvation with the purpose of investigating the accuracy of the Caldeira-Leggett model. We do that by simulating the vibrational features of water solvation by means of two different approaches. One is entirely based on the adoption of an accurate ab initio potential to describe water clusters of increasing dimensionality.

Machine learning for vibrational spectroscopy via divide-and-conquer semiclassical initial value representation molecular dynamics with application to N-methylacetamide.

A machine learning algorithm for partitioning the nuclear vibrational space into subspaces is introduced. The subdivision criterion is based on Liouville's theorem, i.e.

Improved semiclassical dynamics through adiabatic switching trajectory sampling.

We introduce an improved semiclassical dynamics approach to quantum vibrational spectroscopy. In this method, a harmonic-based phase space sampling is preliminarily driven toward non-harmonic quantization by slowly switching on the actual potential. The new coordinates and momenta serve as initial conditions for the semiclassical dynamics calculation, leading to a substantial decrease in the number of chaotic trajectories to deal with.

Pediatrician knowledge and attitudes regarding human papillomavirus disease and its prevention.

Between 1 September and 8 October 2006, we used a self-administered, anonymous questionnaire in order to evaluate knowledge and attitudes regarding HPV disease and its prevention in a nationally representative sample of Italian pediatricians. Three hundred and eleven of the 400 enrolled physicians (175 primary care pediatricians, 160 hospital pediatricians and 65 residents in pediatrics) returned completed surveys (227 females; mean age+/-standard deviation, 45.3+/-11.

Impact on respiratory tract infections of heptavalent pneumococcal conjugate vaccine administered at 3, 5 and 11 months of age.

Background: Medical and public health importance of pneumococcal infections justifies the implementation of measures capable of reducing their incidence and severity, and explains why the recently marketed heptavalent pneumococcal conjugate vaccine (PCV-7) has been widely studied by pediatricians. This study was designed to evaluate the impact of PCV-7 administered at 3, 5 and 11 months of age on respiratory tract infections in very young children.

Methods: A total of 1,571 healthy infants (910 males) aged 75-105 days (median 82 days) were enrolled in this prospective cohort trial to receive a hexavalent vaccine (DTaP/IPV/HBV/Hib) and PCV-7 (n = 819) or the hexavalent vaccine alone (n = 752) at 3, 5 and 11 months of age.

Impact of human coronavirus infections in otherwise healthy children who attended an emergency department.

This prospective clinical and virological study of 2,060 otherwise healthy children aged <15 years of age (1,112 males; mean age +/- SD, 3.46 +/- 3.30 years) who attended the Emergency Department of Milan University's Institute of Pediatrics because of an acute disease excluding trauma during the winter season 2003-2004 was designed to compare the prevalence and clinical importance of human coronaviruses (HCoVs) in children.

Differences in nasopharyngeal bacterial flora in children with nonsevere recurrent acute otitis media and chronic otitis media with effusion: implications for management.

Background: The interactions between nasopharyngeal flora and the individual entities covered by the broad term otitis media have not been completely elucidated. We investigated in infants and children ages 6 months to 7 years with nonsevere recurrent acute otitis media (rAOM) or with chronic otitis media with effusion (cOME): (1) the nasopharyngeal carriage rate and bacterial density of respiratory pathogens and alpha-hemolytic streptococci in comparison with healthy children; (2) the resistance pattern of respiratory pathogens; and (3) the relationship between the type of nasopharyngeal colonization and long term outcome.

Methods: Nasopharyngeal cultures were obtained from 85 children with rAOM,113 children with cOME and 55 controls.