Crystallization of Arthrobacter sp. strain 1C N-(1-D-carboxyethyl)-L-norvaline dehydrogenase and its complex with NAD+

The novel NAD+-linked opine dehydrogenase from a soil isolate Arthrobacter sp. strain 1C belongs to an enzyme superfamily whose members exhibit quite diverse substrate specificites. Crystals of this opine dehydrogenase, obtained in the presence or absence of co-factor and substrates, have been shown to diffract to beyond 1.8 ? resolution. X-ray precession photographs have established that the crystals belong to space group P21212, with cell parameters a = 104.9, b = 80.0, c = 45.5 ? and a single subunit in the asymmetric unit. The elucidation of the three-dimensional structure of this enzyme will provide a structural framework for this novel class of dehydrogenases to enable a comparison to be made with other enzyme families and also as the basis for mutagenesis experiments directed towards the production of natural and synthetic opine-type compounds containing two chiral centres.     

Angular momentum decoupling approximations in the quantum dynamics of reactive systems

Two methods for implementing angular momentum decoupling approximations in quantum mechanical reactive scattering examined. Applications of both reactive and nonreactive H + H₂ collisions indicate that for the most intense individual reactive transitions and for all degeneracy-averaged ones, these decoupling methods (especially the “proper” decoupling method) yield results in good agreement with those of fully-coupled calculations. However, for the less intense reactive transitions and all individual nonreactive transitions, very large errors can result from use of these approximate methods.     

Sun Exposure over a Lifetime in Australian Adults from Latitudinally Diverse Regions

Spatio‐temporal patterns in sun exposure underlie variations in skin cancer incidence and vitamin D deficiency, indicate effectiveness of sun protection programs and provide insights into future health risks. From 558 adults across four regions of Australia (Brisbane (27°S), Newcastle (33°S), Geelong and the Western Districts of Victoria (37°S) and Tasmania (43°S)), we collected: self‐report data on time‐in‐the‐sun from age 6 years; natural skin color and ethnicity; silicone skin casts (for cumulative skin damage); and serum for vitamin D status. Ambient ultraviolet radiation (UVR) at the location of residence, with time‐in‐the‐sun, was used to calculate a “UVR dose” for each year of life. Individuals maintained their ranking compared to their peers for time‐in‐the‐sun in summer compared to winter and across ages (Spearman rho 0.24–0.84, all P < 0.001). Time‐in‐the‐sun decreased with age in all birth cohorts, and over calendar time. Summer time‐in‐the‐sun increased with increasing latitude (P < 0.001). Seasonal variation in vitamin D status had greater amplitude and vitamin D deficiency increased with increasing latitude. Temporal patterns are consistent with effectiveness of sun protection programs. Higher relative time‐in‐the‐sun persists from childhood through adulthood. Lower summer time‐in‐the‐sun in the warmest location may have implications for predictions of UVR‐related health risks of climate change.     

First results from KamLAND: evidence for reactor antineutrino disappearance

KamLAND has measured the flux of nu;(e)'s from distant nuclear reactors. We find fewer nu;(e) events than expected from standard assumptions about nu;(e) propagation at the 99.95% C.L. In a 162 ton.yr exposure the ratio of the observed inverse beta-decay events to the expected number without nu;(e) disappearance is 0.611+/-0.085(stat)+/-0.041(syst) for nu;(e) energies >3.4 MeV. In the context of two-flavor neutrino oscillations with CPT invariance, all solutions to the solar neutrino problem except for the "large mixing angle" region are excluded.     

Partition Complexes, Tits Buildings and Symmetric Products

We construct a homological approximation to the partition complex,and identify it as the Tits building. This gives a homologicalrelationship between the symmetric group and the affine group,leads to a geometric tie between symmetric powers of spheresand the Steinberg idempotent, and allows us to use the self-dualityof the Steinberg module to study layers in the Goodwillie towerof the identity functor. 2000 Mathematics Subject Classification:55N25, 55S15, 20B30, 55P25.