Minimizing the number of tardy jobs with precedence constraints and agreeable due dates

AbstractMinimizing the number of precedence constrained, unit-time tardy jobs is strongly NP-hard on a single machine. We study a special case of the problem where a job is tardy if it is finished more than a fixed K time units after its earliest possible completion time under the precedence constraints. We prove that the problem remains strongly NP-hard even with these special due dates. We also present polynomial time solutions for the weighted version of the problem if the precedence constraints are out-forests or interval orders. In the process, we also present a polynomial time solution for a special case of the minimum weight hitting set problem

L’inadvertance du Docteur Cottard

Cet article s'intéresse à la réception de Shakespeare en France en constatant une résistance linguistique, littéraire et culturelle à l'oeuvre du dramaturge anglais, puis en proposant une réflexion quant au pourquoi de ces rapports conflictuels. George Steiner parcourt le sort que les différents siècles et modes littéraires et critiques ont réservé à Shakespeare, de la rencontre manquée de Racine et Shakespeare au rejet politique de de Gaulle, en passant par l'indifférence de Proust. Le romantisme et la canonisation du Barde par Hugo font figure d'exception, tout comme l'oeuvre «shakespearienne» de Paul Claudel. L'auteur émet alors différentes hypothèses, dont le malaise que crée la coexistence du tragique et du comique chez Shakespeare pour des Français plus enclins à séparer rigoureusement les genres et l'impossibilité de catégoriser Shakespeare sous une étiquette religieuse ou idéologique. Enfin, l'auteur rejette l'explication linguistique d'une incompatibilité entre le français et l'anglais, en prenant l'exemple d'autres langues européennes et en analysant de récentes traductions (résumé d'Anne Dunan)

Development of a Contingency Gas Analyzer for the Orion Crew Exploration Vehicle

NASA's experience with electrochemical sensors in a hand-held toxic gas monitor serves as a basis for the development of a fixed on-board instrument, the Contingency Gas Analyzer (CGA), for monitoring selected toxic combustion products as well as oxygen and carbon dioxide on the Orion Crew Exploration Vehicle (CEV). Oxygen and carbon dioxide are major components of the cabin environment and accurate measurement of these compounds is critical to maintaining a safe working environment for the crew. Fire or thermal degradation events may produce harmful levels of toxic products, including carbon monoxide (CO), hydrogen cyanide (HCN), and hydrogen chloride (HCl) in the environment. These three components, besides being toxic in their own right, can serve as surrogates for a panoply of hazardous combustion products. On orbit monitoring of these surrogates provides for crew health and safety by indicating the presence of toxic combustion products in the environment before, during and after combustion or thermal degradation events. Issues identified in previous NASA experiences mandate hardening the instrument and components to endure the mechanical and operational stresses of the CEV environment while maintaining high analytical fidelity. Specific functional challenges involve protecting the sensors from various anticipated events- such as rapid pressure changes, low cabin pressures, and extreme vibration/shock exposures- and extending the sensor lifetime and calibration periods far beyond the current state of the art to avoid the need for on-orbit calibration. This paper focuses on lessons learned from the earlier NASA hardware, current testing results, and engineering solutions to the identified problems. Of particular focus will be the means for protecting the sensors, addressing well known cross-sensitivity issues and the efficacy of a novel self monitoring mechanism for extending sensor calibration periods

Food habits and species composition of neritic reef fishes off Depoe Bay, Oregon

The distribution and trophic ecology of neritic reef fishes was studied to provide biological information useful in conserving these stocks. Houk and line fishing was conducted from July 1976 to July 1977 on neritic reefs within 5 km of the Oregon coast adjacent to Depoe Bay. Sampling was designed to determine the seasonal and depth variations in species composition of nearshore reef-fish communities, and to determine the trophic relationships within these species. The species composition of fish communities on reefs shoreward of the 20 m depth contour was markedly different from that on deeper (20-50 m) reefs. While fish communities on shallow reefs were dominated by black rockfish (Sebastes melanops), those on deeper reefs were dominated collectively by lingcod (Ophiodon elongatus), yelloweye rockfish (Sebastes ruberrirnus), and black rockfish. The mean lengths of the two most abundant species, black rockfish and lingcod, were decidedly longer on the deep reefs than on the shallow reefs. Several neritic reef fish species were seldom found shoreward of the 20-30 m depth interval, suggesting that this zone constitutes a functional boundary to the distribution of these species. The catch per unit of effort for black rockfish was significantly (p = .01) greater on shallow reefs (10-20 m) during summer and winter than it was during spring and fall. The species composition of catches in all reef areas changed seasonally due mainly to a significant (p = . 10) increase in lingcod abundance in reef areas during their winter spawning period. Analysis of stomach contents of the five principal species using Bray-Curtis dissimilarity indices revealed that these nearshore reef fish communities are relatively uncoupled trophic systems. This suggests that the principal species do not exclude one another from reef areas through competition for food, and thus, for purposes of conservation, can probably be considered separately. Because of the continuing increase in sport and commercial fishing effort on neritic reef fishes, it is increasingly possible that these stocks could be overexploited. Restriction of the lingcod fishery during their winter spawning period and a maximum size limit for lingcod are possible strategies to help insure adequate recruitment of these species. However, before such restrictions are considered, the role of offshore stocks of lingcod with regard to spawning and recruitment needs to be better understood

Hubbard-U calculations for Cu from first-principles Wannier functions

We present first-principles calculations of optimally localized Wannier functions for Cu and use these for an ab-initio determination of Hubbard (Coulomb) matrix elements. We use a standard linearized muffin-tin orbital calculation in the atomic-sphere approximation (LMTO-ASA) to calculate Bloch functions, and from these determine maximally localized Wannier functions using a method proposed by Marzari and Vanderbilt. The resulting functions were highly localized, with greater than 89% of the norm of the function within the central site for the occupied Wannier states. Two methods for calculating Coulomb matrix elements from Wannier functions are presented and applied to fcc Cu. For the unscreened on-site Hubbard $U$ for the Cu 3d-bands we have obtained about 25eV. These results are also compared with results obtained from a constrained local-density approximation (LDA) calculation.Comment: 13 pages, 8 figures, 5 table

On the Origin of the Treponematoses: A Phylogenetic Approach

For 500 years, controversy has raged around the origin of T. pallidum subsp. pallidum, the bacterium responsible for syphilis. Did Christopher Columbus and his men introduce this pathogen into Renaissance Europe, after contracting it during their voyage to the New World? Or does syphilis have a much older history in the Old World? This paper represents the first attempt to use a phylogenetic approach to solve this question. In addition, it clarifies the evolutionary relationships between the pathogen that causes syphilis and the other T. pallidum subspecies, which cause the neglected tropical diseases yaws and endemic syphilis. Using a collection of pathogenic Treponema strains that is unprecedented in size, we show that yaws appears to be an ancient infection in humans while venereal syphilis arose relatively recently in human history. In addition, the closest relatives of syphilis-causing strains identified in this study were found in South America, providing support for the Columbian theory of syphilis's origin