A new lower bound approach for single-machine multicriteria scheduling

The concept of maximum potential improvement has played an important role in computing lower bounds for single-machine scheduling problems with composite objective functions that are linear in the job completion times. We introduce a new method for lower bound computation; objective splitting. We show that it dominates the maximum potential improvement method in terms of speed and quality

Complexity of scheduling multiprocessor tasks with prespecified processor allocations

We investigate the computational complexity of scheduling multiprocessor tasks with prespecified processor allocations. We consider two criteria: minimizing schedule length and minimizing the sum of the task completion times. In addition, we investigate the complexity of problems when precedence constraints or release dates are involved

The sedimentary legacy of a palaeo-ice stream on the shelf of the southern Bellingshausen Sea: Clues to West Antarctic glacial history during the Late Quaternary

A major trough ("Belgica Trough") eroded by a palaeo-ice stream crosses the continental shelf of the southern Bellingshausen Sea (West Antarctica) and is associated with a trough mouth fan ("Belgica TMF") on the adjacent continental slope. Previous marine geophysical and geological studies investigated the bathymetry and geomorphology of Belgica Trough and Belgica TMF, erosional and depositional processes associated with bedform formation, and the temporal and spatial changes in clay mineral provenance of subglacial and glaciomarine sediments. Here, we present multi-proxy data from sediment cores recovered from the shelf and uppermost slope in the southern Bellingshausen Sea and reconstruct the ice-sheet history since the last glacial maximum (LGM) in this poorly studied area of West Antarctica. We combined new data (physical properties, sedimentary structures, geochemical and grain-size data) with published data (shear strength, clay mineral assemblages) to refine a previous facies classification for the sediments. The multi-proxy approach allowed us to distinguish four main facies types and to assign them to the following depositional settings: 1) subglacial, 2) proximal grounding-line, 3) distal sub-ice shelf/sub-sea ice, and 4) seasonal open-marine. In the seasonal open-marine fades we found evidence for episodic current-induced winnowing of near-seabed sediments on the middle to outer shelf and at the uppermost slope during the late Holocene. In addition, we obtained data on excess Pb-210 activity at three core sites and 44 AMS C-14 dates from the acid-insoluble fraction of organic matter (AIO) and calcareous (micro-) fossils, respectively, at 12 sites. These chronological data enabled us to reconstruct, for the first time, the timing of the last advance and retreat of the West Antarctic Ice Sheet (WAIS) and the Antarctic Peninsula Ice Sheet (APIS) in the southern Bellingshausen Sea. We used the down-core variability in sediment provenance inferred from clay mineral changes to identify the most reliable AIO C-14 ages for ice-sheet retreat. The palaeo-ice stream advanced through Belgica Trough after similar to 36.0 corrected C-14 ka before present (B.P.). It retreated from the outer shelf at similar to 25.5 ka B.P, the middle shelf at similar to 19.8 ka B.P., the inner shelf in Eltanin Bay at similar to 12.3 ka B.P., and the inner shelf in Ronne Entrance at similar to 6.3 ka B.P. The retreat of the WAIS and APIS occurred slowly and stepwise, and may still be in progress. This dynamical ice-sheet behaviour has to be taken into account for the interpretation of recent and the prediction of future mass-balance changes in the study area. The glacial history of the southern Bellingshausen Sea is unique when compared to other regions in West Antarctica, but some open questions regarding its chronology need to be addressed by future work. (C) 2010 Elsevier Ltd. All rights reserved

Laboratory capture, isolation and analysis of microparticles in aerogel: Preparation for the return of Stardust

We present observations from the laboratory capture of particles in aerogel. The paper focuses on a possible extraction technique and the bulk mineral characterization of the captured material using non-destructive analytical techniques

Dislodgement force and shell morphology vary according to wave exposure in a tropical gastropod (Cittarium pica)

Wave exposure has strong influences on population density, morphology and behaviour of intertidal species in temperate zones, but little is known about how intertidal organisms in tropical regions respond to gradients in wave exposure. We tested whether dislodgement force and shell shape of a tropical gastropod, Cittarium pica, differs among shores that vary in wave exposure. After adjusting for body size, we found that C. pica from exposed shores required greater dislodgement force to remove them from the shore, had slightly larger opercula (the closure to the shell aperture), and were slightly squatter in shape (reduced in shell height relative to shell width) than C. pica from sheltered shores. These morphological adjustments are consistent with those observed in temperate gastropods, which are argued to represent adaptive responses to the risk of mortality associated with dislodgement

Minimal chordal sense of direction and circulant graphs

A sense of direction is an edge labeling on graphs that follows a globally consistent scheme and is known to considerably reduce the complexity of several distributed problems. In this paper, we study a particular instance of sense of direction, called a chordal sense of direction (CSD). In special, we identify the class of k-regular graphs that admit a CSD with exactly k labels (a minimal CSD). We prove that connected graphs in this class are Hamiltonian and that the class is equivalent to that of circulant graphs, presenting an efficient (polynomial-time) way of recognizing it when the graphs' degree k is fixed

Dielectronic Recombination in Li+ Ions

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Dielectronic Recombination in Li+ Ions

This research was sponsored by the National Science Foundation Grant NSF PHY-931478

Critical Decisions for Ensuring Plant or Animal Breeding is Gender-Responsive

Widespread adoption and impact of improved crop varieties and animal breeds depends on the tangible benefits they provide for the women and men involved in their production, consumption and marketing. For breeders to meet the needs of resource-poor users, interdisciplinary collaboration is needed to understand the priorities that women and men assign to genetically determined traits, and reflect those priorities in their breeding decisions. Many CGIAR breeding programs understand that if they overlook gender differences and traits important to women users, this can aggravate household food insecurity and poverty. To help breeding programs avoid this problem and provide them with general guidance in making their breeding more gender responsive, four principles regarding the issue are proposed (see Box 1). However, many breeding programs do not yet fully understand how to put these principles into practice, making it difficult to become more gender-responsive. This brief addresses the challenge of putting principles into practice. It lays out an approach that involves the systematic inclusion of relevant information about gender differences in critical decisions made at key points in the breeding cycle. The aim is to enable plant and animal breeding programs to become more gender responsive