Proline induced disruption of the structure and dynamics of water.

We use quasi-elastic neutron scattering spectroscopy to study the diffusive motion of water molecules at ambient temperature as a function of the solute molar fraction of the amino acid, proline. We validate molecular dynamics simulations against experimental quasielastic neutron scattering data and then use the simulations to reveal, and understand, a strong dependence of the translational self-diffusion coefficient of water on the distance to the amino acid molecule. An analysis based on the juxtaposition of water molecules in the simulation shows that the rigidity of proline imposes itself on the local water structure, which disrupts the hydrogen-bond network of water leading to an increase in the mean lifetime of hydrogen bonds.

Promising strategies for preventing perinatal HIV transmission: model programs from three states.

Objectives: This paper describes and compares three innovative methods for preventing perinatal HIV transmission. Each of these strategies has been developed based on an in-depth assessment of the strengths and weaknesses of existing prevention approaches, and the needs of the populations they serve.

Methods: Florida expanded an existing outreach program to include women in jails in several high-prevalence counties.