Generic mechanism for generating a liquid-liquid phase transition

Recent experimental results indicate that phosphorus--a single-component system--can have a high-density liquid (HDL) and a low-density liquid (LDL) phase. A first-order transition between two liquids of different densities is consistent with experimental data for a variety of materials, including single-component systems such as water, silica and carbon. Molecular dynamics simulations of very specific models for supercooled water, liquid carbon and supercooled silica predict a LDL-HDL critical point, but a coherent and general interpretation of the LDL-HDL transition is lacking. Here we show that the presence of a LDL and a HDL can be directly related to an interaction potential with an attractive part and two characteristic short-range repulsive distances. This kind of interaction is common to other single-component materials in the liquid state (in particular, liquid metals), and such potentials are often used to describe systems that exhibit a density anomaly. However, our results show that the LDL and HDL phases can occur in systems with no density anomaly. Our results therefore present an experimental challenge to uncover a liquid-liquid transition in systems like liquid metals, regardless of the presence of a density anomaly.     

Habitat use and food selection of small mammals near a sagebrush/crested wheatgrass interface in southeastern Idaho

Habitat use and food selection data were collected for deer mice ( Peromyscus maniculatus ), montane voles ( Microtus montanus ), Ord's kangaroo rats ( Dipodomys ordii ), and Townsend's ground squirrels ( Spermophilus townsendii ) near a sagebrush ( Artemisia tridentata )/crested wheatgrass ( Agropyron cristatum ) interface in southeastem Idaho. Significantly more captures occurred in the native sagebrush habitat than in areas planted in crested wheatgrass or in disturbed sites. Crested wheatgrass, a prolific seed producer, still accounted for over 30% of the total captures. Montane voles and Townsend's ground squirrels (during periods of aboveground activity) used the crested wheatgrass habitat throughout the summer, while deer mice and, Ord's kangaroo rats exhibited heavy use after seed set.     

Utah's rare plants revisited

Presented is a current evaluation of the status and distribution of Utah's rare plant species, including those officially listed as endangered or threatened, those under review for listing, those recommended by the Utah Native Plant Society, and those which recently have been removed from consideration. Taxa are discussed alphabetically. Information on status, distribution, habitat, elevation, and specimens deposited at Brigham Young University are included in the discussion of each species. Maps showing the state distribution of each listed or candidate plant are also provided. New combinations include Dalea flavescens (Wats.) Welsh var. epica (Welsh) Welsh & Chatterley and Schoenerambe suffrutescens (Rollins) Welsh & Chatterley.        

Preliminary index of authors of Utah plant names

Presented herein is an index to approximately 800 authors of vascular plant names of Utah. A standardized abbreviation is presented for each author. These are listed alphabetically. Following each abbreviation is the full name and birth and death dates (where available) of each individual. In some cases the date of publication is given when biographical information is not known.     

A fourth species of Oreoxis (Umbelliferae)

Described as a new species is Oreoxis trotteri Welsh & Goodrich from Utah.      

Utah botanical explorer Charles Christopher Parry (28 August 1823-20 February 1890)

The Utah botanical contributions of Charles Christopher Parry are discussed. Especial emphasis is on his trips to Utah in 1874 and 1875. Plants taken during those years, which were subsequently listed as type-specimens, are listed. Insight is gained into this window in Utah botanical history through his letters to Dr. George Engelmann and limited correspondence from Engelmann and Joseph Ellis Johnson.