Performance of SM8 on a Test To Predict Small-Molecule Solvation Free Energies

The SM8 quantum mechanical aqueous continuum solvation model is applied to a 17-molecule test set proposed by Nicholls et al. (J. Med. Chem.2008, 51, 769) to predict free energies of solvation. With the M06-2X density functional, the 6-31G(d) basis set, and CM4M charge model, the root-mean-square error (RMSE) of SM8 is 1.08 kcal mol−1 for aqueous geometries and 1.14 kcal mol−1 for gas-phase geometries. These errors compare favorably with optimal explicit and continuum models reported by Nicholls et al., having RMSEs of 1.33 and 1.87 kcal mol−1, respectively. Other models examined by these workers had RMSEs of 1.5−2.6 kcal mol−1. We also explore the use of other density functionals and charge models with SM8 and the RMSE increases to 1.21 kcal mol−1 for mPW1/CM4 with gas-phase geometries, to 1.50 kcal mol−1 for M06-2X/CM4 with gas-phase geometries, and to 1.27−1.64 kcal mol−1 with three different models at B3LYP gas-phase geometries

Missing domesticated plant forms: can artificial selection fill the gap?

In the course of their evolution, the angiosperms have radiated into most known plant forms and life histories. Their adaptation to a recently created habitat, the crop field, produced a novel form: the plant that allocates an unprecedented 30–60% of its net productivity to sexual structures. Long-lived trees, shrubs and vines of this form evolved, as did annual herbs. Perennial herb forms with increased allocation to asexual reproduction evolved, but there are no examples of perennial herbs with high sexual effort. We suggest that sowing seed into annually tilled fields favored shorter-lived herbs because of trade-offs between first-year seed production and relative growth rate and/or persistence. By propagating cuttings, people quickly domesticated tuber crops and large woody plants. Perennial herbs were too small to be efficiently propagated by cuttings, and the association between longevity, allogamy and genetic load made rapid domestication by sexual cycles unlikely. Perennial grain crops do not exist because they could not have evolved under the original set of conditions; however, they can be deliberately developed today through artificial phenotypic and genotypic selection

Design details and specifications for a water works system, Buchanan, Mich.

http://www.archive.org/details/designdetailsspe00chamThesis (B.S.)--Armour Institute of Technolog

XQueryP: Programming with XQuery

XQuery is a declarative language for querying and updating XML data sources. Interfacing XQuery to a host programming language is difficult because of the type system mismatch, and global optimization is difficult in a mixed-language environment. In this paper, we investigate a small extension called XQueryP that enables XQuery expressions to exchange state information through variables. This extension makes it easier to develop applications in XQuery without relying on a host programming language. We draw an analogy between the proposed extension and similar extensions that have been added over the years to the SQL query language for similar reasons. 1