An optical atomic clock based on a highly charged ion.

Optical atomic clocks are the most accurate measurement devices ever constructed and have found many applications in fundamental science and technology1-3. The use of highly charged ions (HCI) as a new class of references for highest-accuracy clocks and precision tests of fundamental physics4-11 has long been motivated by their extreme atomic properties and reduced sensitivity to perturbations from external electric and magnetic fields compared with singly charged ions or neutral atoms. Here we present the realization of this new class of clocks, based on an optical magnetic-dipole transition in Ar13+. Its comprehensively evaluated systematic frequency uncertainty of 2.2 × 10-17 is comparable with that of many optical clocks in operation. From clock comparisons, we improve by eight and nine orders of magnitude on the uncertainties for the absolute transition frequency12 and isotope shift (40Ar versus 36Ar) (ref. 13), respectively. These measurements allow us to investigate the largely unexplored quantum electrodynamic (QED) nuclear recoil, presented as part of improved calculations of the isotope shift, which reduce the uncertainty of previous theory14 by a factor of three. This work establishes forbidden optical transitions in HCI as references for cutting-edge optical clocks and future high-sensitivity searches for physics beyond the standard model.

Development of a catalytic enantioselective conjugate addition of 1,3-dicarbonyl compounds to nitroalkenes for the synthesis of endothelin-A antagonist ABT-546. Scope, mechanism, and further application to the synthesis of the antidepressant rolipram.

The enantioselective synthesis of endothelin-A antagonist ABT-546 has been accomplished via the discovery and development of a highly selective catalytic asymmetric conjugate addition of ketoesters to nitroolefins. Employing just 4 mol % bis(oxazoline)-Mg(OTf)(2) complex with an amine cocatalyst, we obtained the product nitroketone with 88% selectivity at the aryl-bearing stereocenter and in good yield on scales ranging to 13 mol. The effects of ligand structure, metal salt, and solvent on the reaction are described. Particularly important to the reaction is the water content. While water is necessary during the generation of the catalyst, the water must be then removed to maximize stereoselectivity and reactivity. The reaction has been extended to other dicarbonyl substrates, and a variety of substitution patterns are tolerated on the nitroolefin partner. The reaction has also been employed in the synthesis of the antidepressant rolipram. Investigations relating to the mechanism of the reaction are also described.

Factors for predicting premature termination from a multidisciplinary inpatient chronic pain program.

Forty-eight chronic pain patients who were discharged from or left the 21-day inpatient component of a multidisciplinary pain program prior to completion were compared with a randomly selected matched group of program patients who stayed the entire 21 days. The purpose of the study was to determine if pre-admission factors are useful in predicting whether a chronic pain patient will complete an inpatient pain program. The results of pre-admission MMPI, POMS, MPQ, and information obtained from a questionnaire specially created for the program were studied. On the tests, the non-completers admitted to less psychopathology than those who did complete the program. The non-completers also had a higher number of pain-related surgeries and were more likely to be college graduates; limited social support from their families and lower MMPI premature termination scale scores were also found. Implications of these findings for the management of chronic pain patients are discussed.