Molecular-dynamics simulations were used to model two stepped ͕101 4͖ surfaces of the calcium carbonate polymorph calcite. The acute monatomic steps were found to be more stable than the obtuse monatomic steps. The initial stages of dissolution from the steps were considered in vacuo and in water. In vacuo CaCO 3 was shown to dissolve preferentially from the obtuse step. In aqueous environment both stepped surfaces are stabilized by the presence of the water molecules although the relative stabilities remain similar. Using potential parameters that reproduce experimental enthalpies of the dissolution of calcite crystal, the formation of the double kinks on the obtuse step is shown to cost less energy than dissolution from the acute step, probably due to the lower stability of the obtuse surface. The simulations suggest that formation of the kink sites on the dissolving edge of the obtuse step of calcite is the rate determining step and this edge is predicted to dissolve preferentially, which is in agreement with experimental findings of calcite dissolution under aqueous conditions.

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This study probes the antecedents of father-daughter sexual abuse, utilizing perspectives of parent-child bonding and an emerging theory of incest avoidance. Data were obtained from a sample of abusive fathers and a comparison group who were not known abusers. Fathers' involvement in the early socialization of their daughters constituted a major differentiating variable.

We introduce a potential model for MgCO3 and CdCO3 which reproduces experimental structural parameters and solution energies. We employed atomistic simulation techniques to model the absorption and segregation of magnesium and cadmium ions to the low-index surfaces of calcite. Both magnesium and cadmium ions absorb at the surfaces from solution. The absorption energies are surface dependent, due to distinct relaxations of the different surfaces, and ion dependent with the smaller sized magnesium ion showing larger relaxations. The absorption energies are larger for magnesium than for cadmium, mainly due to the closer coordination of the water molecules to the magnesium substituted surfaces. The cadmium ions segregate to the bulk crystal more easily than the magnesium ions which prefer to remain at the surface. However, segregation energies for both cations in second and further layers of some surfaces are positive, indicating that once a calcium carbonate layer has overgrown the substituted surface layer, segregation to the bulk is energetically possible.

Antiresorptive therapy with a bisphosphonate decreases the fracture rate and preserves bone mass 1 year after lung transplantation. In end-stage lung disease patients with osteopenia or osteoporosis, bisphosphonate therapy should be initiated before transplant surgery is contemplated.