An algorithmic characterization of antimatroids

In an article entitled “Optimal sequencing of a single machine subject to precedence constraints” E.L. Lawler presented a now classical minmax result for job scheduling. In essence, Lawler's proof demonstrated that the properties of partially ordered sets were sufficient to solve the posed scheduling problem. These properties are, in fact, common to a more general class of combinatorial structures known as antimatroids, which have recently received considerable attention in the literature. It is demonstrated that the properties of antimatroids are not only sufficient but necessary to solve the scheduling problem posed by Lawler, thus yielding an algorithmic characterization of antimatroids. Examples of problems solvable by the general result are provided

Quantum computing with alkaline earth atoms

We present a complete scheme for quantum information processing using the unique features of alkaline earth atoms. We show how two completely independent lattices can be formed for the $^1$S$_0$ and $^3$P$_0$ states, with one used as a storage lattice for qubits encoded on the nuclear spin, and the other as a transport lattice to move qubits and perform gate operations. We discuss how the $^3$P$_2$ level can be used for addressing of individual qubits, and how collisional losses from metastable states can be used to perform gates via a lossy blockade mechanism.Comment: 4 pages, 3 figures, RevTeX

The Viability of Cross-Country Running Appearing in the Winter Olympic Games

Today cross-country running celebrates over 200 years of being a practiced organized sport Originally adapted as a form of imitation fox hunting by schoolboys in England it is now a globally sanctioned program governed by World Athletics which oversees marathon running track and field and other athletics events First introduced to the International Olympic Committee by Percy Fischer a member of the Olympic track committee of the Amateur Athletics Association in October 1910 crosscountry running appeared three times on the program for the Summer Olympic Games in 1912 1920 and 1924 as both a team and individually-scored event Due to the overwhelming popularity of track and field and marathon events in the current Olympic Games program in the summer recent attention has turned to promoting cross-country running largely practiced in the autumnal and winter months the world over for inclusion on the Winter Olympic Games schedule Despite a history of nearly 100 years of effor ts for reinclusion back into the Olympics crosscountry running has had difficulty in gaining traction for support for the winter program largely due to the winter olympic charter mandating all sports be practiced exclusively on snow or ic

Effect of Urea and Distillers Inclusion in Dry- Rolled Corn Based Diets on Heifer Performance and Carcass Characteristics

Crossbred heifers (n=96, BW = 810 ± 20) were utilized to evaluate the effects of increasing wet distillers grains plus solubles and urea inclusion in a dry rolled corn based finishing diet on performance and carcass characteristics. Heifers were individually fed using a calan gate system with a 2 × 2 factorial arrangement of treatments. Factors included distillers inclusion at either 10 or 20% of diet DM and urea inclusion at either 0.2 or 1.4% of diet DM. Th ere was no difference for final body weight, average daily gain, and feed conversion on a live or carcass adjusted basis for either urea or distillers inclusion in the diet. Dry matter intake was reduced with increased urea inclusion; however, distillers inclusion did not influence intake. Added distillers and urea in the diet had minimal impact on performance suggesting supplemental urea in a dry rolled corn based finishing diets is of minimal benefit when feeding at least 10% distillers grains