University of Utah

About: University of Utah is a education organization based out in Salt Lake City, Utah, United States. It is known for research contribution in the topics: Population & Poison control. The organization has 52894 authors who have published 124076 publications receiving 5265834 citations. The organization is also known as: The U & The University of Utah.

Oral Contraceptives and the Risk of Hereditary Ovarian Cancer

Abstract: Background Women with mutations in either the BRCA1 or the BRCA2 gene have a high lifetime risk of ovarian cancer. Oral contraceptives protect against ovarian cancer in general, but it is not known whether they also protect against hereditary forms of ovarian cancer. Methods We enrolled 207 women with hereditary ovarian cancer and 161 of their sisters as controls in a case–control study. All the patients carried a pathogenic mutation in either BRCA1 (179 women) or BRCA2 (28 women). The control women were enrolled regardless of whether or not they had either mutation. Lifetime histories of oral-contraceptive use were obtained by interview or by written questionnaire and were compared between patients and control women, after adjustment for year of birth and parity. Results The adjusted odds ratio for ovarian cancer associated with any past use of oral contraceptives was 0.5 (95 percent confidence interval, 0.3 to 0.8). The risk decreased with increasing duration of use (P for trend, <0.001); use for six or...

Vulnerability to xylem cavitation and the distribution of Sonoran Desert vegetation

Abstract: We studied 15 riparian and upland Sonoran desert species to evaluate how the limitation of xylem pressure (Cx) by cavitation corresponded with plant distribution along a moisture gradient. Riparian species were obligate riparian trees ( Fraxinus velutina, Populus fremontii, and Salix gooddingii), native shrubs (Baccharis spp.), and an exotic shrub (Tamarix ramosissima). Upland species were evergreen (Juniperus monosperma, Larrea tridentata ), drought-deciduous (Ambrosia dumosa, Encelia farinosa, Fouquieria splendens, Cercidium microphyllum ), and winter-deciduous (Acacia spp., Prosopis velutina) trees and shrubs. For each species, we measured the ‘‘vulnerability curve’’ of stem xylem, which shows the decrease in hydraulic conductance from cavitation as a function of Cx and the Ccrit representing the pressure at complete loss of transport. We also measured minimum in situ Cx(Cxmin) during the summer drought. Species in desert upland sites were uniformly less vulnerable to cavitation and exhibited lower Cxmin than riparian species. Values of Ccrit were correlated with minimum Cx. Safety margins (Cxmin‐Ccrit) tended to increase with decreasing Cxmin and were small enough that the relatively vulnerable riparian species could not have conducted water at the Cx experienced in upland habitats (2 4t o210 MPa). Maintenance of positive safety margins in riparian and upland habitats was associated with minimal to no increase in stem cavitation during the summer drought. The absence of less vulnerable species from the riparian zone may have resulted in part from a weak but significant trade-off between decreasing vulnerability to cavitation and conducting efficiency. These data suggest that cavitation vulnerability limits plant distribution by defining maximum drought tolerance across habitats and influencing competitive ability of drought tolerant species in mesic habitats.

Multiscale coarse graining of liquid-state systems.

Abstract: A methodology is described to systematically derive coarse-grained (CG) force fields for molecular liquids from the underlying atomistic-scale forces. The coarse graining of an interparticle force field is accomplished by the application of a force-matching method to the trajectories and forces obtained from the atomistic trajectory and force data for the CG sites of the targeted system. The CG sites can be associated with the centers of mass of atomic groups because of the simplicity in the evaluation of forces acting on these sites from the atomistic data. The resulting system is called a multiscale coarse-grained (MS-CG) representation. The MS-CG method for liquids is applied here to water and methanol. For both liquids one-site and two-site CG representations without an explicit treatment of the long-ranged electrostatics have been derived. In addition, for water a two-site model having the explicit long-ranged electrostatics has been developed. To improve the thermodynamic properties (e.g., pressure and density) for the MS-CG models, the constraint for the instantaneous virial was included into the force-match procedure. The performance of the resulting models was evaluated against the underlying atomistic simulations and experiment. In contrast with existing approaches for coarse graining of liquid systems, the MS-CG approach is general, relies only on the interatomic interactions in the reference atomistic system.