Chiral recognition of organic molecules by atomic kinks on surfaces.

Two distinct non-mirror-symmetric conformations of D- and L-cysteine were found after adsorption on Au(17 11 9)S. This demonstrates chiral heterorecognition, i.e., enantioselectivity of S kinks on vicinal Au(111). The structures as determined by angle scanned x-ray photoelectron diffraction agree well with those from density functional theory calculations. The calculations predict adsorption energies of approximately 2 eV where D-cysteine binds 140 meV stronger than L-cysteine. The classical three point contact model for molecular recognition fails to explain these findings.

Atomically resolved images from near node photoelectron holography experiments on Al(111).

Szöke's concept for electron holography is hampered by forward scattering that dominates electron diffraction from electron point sources below the surface top layer. Forward scattering was proposed to be suppressed if the anisotropic nature of the electron source wave is exploited [T. Greber and J. Osterwalder, Chem. Phys. Lett. 256, 653 (1996)]. Experiments show a strong suppression of forward scattering in Al(111) if Al 2s photoelectrons (E(kin) = 952 eV) are measured near the nodal plane of the outgoing p wave. The holographic reconstruction from such diffraction data provides three dimensional images of atomic sites in unit cells with a size of more than 10 A.

Dialogue. Industry consolidation: what's at stake for consumers and purchasers?

The behavioral healthcare field has undergone massive consolidation, especially in the last year. Health plans, hospital systems, and community-based organizations have all been affected. Economists argue that consolidation is a logical consequence of the current, competitive healthcare market. But consumers and purchasers wonder if the mergers and acquisitions will benefit them. Efficient markets are supposed to stimulate competition in ways that reward purchasers and consumers of services. When prices go down and quality improves as a result of competitive market forces, then the market has functioned properly and has served its purpose. Behavioral healthcare, however, is an essential human service, not a commodity. And the consumers and purchasers of healthcare are typically not the same person or entity, which also makes the healthcare market different from the markets for cars, computers, food, or any other type of consumer product. More than 100 million Americans now receive managed behavioral health benefits from only three companies. With such intense power concentrated in the hands of such a small number of providers, the time has come to evaluate the impact of the consolidation trend. In the following dialogue article, leaders, representing different interest groups review the benefits and risks of massive industry consolidation, and propose solutions to the critical challenges that it raises.