Scheduling parallel jobs to minimize the makespan

We consider the NP-hard problem of scheduling parallel jobs with release dates on identical parallel machines to minimize the makespan. A parallel job requires simultaneously a prespecified, job-dependent number of machines when being processed. We prove that the makespan of any nonpreemptive list-schedule is within a factor of 2 of the optimal preemptive makespan. This gives the best-known approximation algorithms for both the preemptive and the nonpreemptive variant of the problem. We also show that no list-scheduling algorithm can achieve a better performance guarantee than 2 for the nonpreemptive problem, no matter which priority list is chosen. List-scheduling also works in the online setting where jobs arrive over time and the length of a job becomes known only when it completes; it therefore yields a deterministic online algorithm with competitive ratio 2 as well. In addition, we consider a different online model in which jobs arrive one by one and need to be scheduled before the next job becomes known. We show that no list-scheduling algorithm has a constant competitive ratio. Still, we present the first online algorithm for scheduling parallel jobs with a constant competitive ratio in this context. We also prove a new information-theoretic lower bound of 2.25 for the competitive ratio of any deterministic online algorithm for this model. Moreover, we show that 6/5 is a lower bound for the competitive ratio of any deterministic online algorithm of the preemptive version of the model jobs arriving over time.     

The multifunctional regulatory proteins ABF1 and CPF1 are involved in the formation of a nuclease-hypersensitive region in the promoter of the QCR8 gene

The abundant DNA-binding proteins ABF1 and CPF1 are members of a family of global regulators with diverse chromosomal functions in the yeast Saccharomyces cerevisiae. Recent evidence suggests that these protein factors may be involved in establishing and maintaining well-defined chromatin structures in promoter regions and other genetic elements. We have investigated the involvement of ABF1 and CPF1 in chromatin organization at the QCR8 gene, encoding subunit VIII of the mitochondrial ubiquinol-cytochrome c oxidoreductase. The promoter region of the QCR8 gene contains overlapping binding sites for ABF1 and CPF1. Nucleosome positioning studies indicate that the QCR8 gene is associated with a phased array of nucleosomes under both catabolite-repressed and derepressed growth conditions. Analysis of binding site mutants reveals that both ABF1 and CPF1 are involved in maintaining a nuclease-hypersensitive region in the QCR8 promoter. The chromatin structure at QCR8 during steady-state growth is, however, mainly dependent on binding of ABF1 to the promoter region. Implications of these findings for the role played by ABF1 and CPF1 in the regulation of mitochondrial biogenesis and other processes important for cell growth and division will be discussed.     

Thermomechanical calculations related to thermally induced rock loosening in an underground cavity

Zones of loosening, together with failure probability and safety factors, can be used to characterize the stability of underground caverns. The effect of a cylindrical heat source on the surrounding rock salt has been investigated in an in situ test carried out in a rock salt mass at a depth of about 750 m. The results of the calculations were confirmed by comparison with the temperatures and displacements measured during the in situ experiment.     

Steering molecular organization and host-guest interactions using two-dimensional nanoporous coordination systems

Metal-organic coordination networks (MOCNs) have attracted wide interest because they provide a novel route towards porous materials that may find applications in molecular recognition, catalysis, gas storage and separation. The so-called rational design principle-synthesis of materials with predictable structures and properties-has been explored using appropriate organic molecular linkers connecting to metal nodes to control pore size and functionality of open coordination networks. Here we demonstrate the fabrication of surface-supported MOCNs comprising tailored pore sizes and chemical functionality by the modular assembly of polytopic organic carboxylate linker molecules and iron atoms on a Cu(100) surface under ultra-high-vacuum conditions. These arrays provide versatile templates for the handling and organization of functional species at the nanoscale, as is demonstrated by their use to accommodate C(60) guest molecules. Temperature-controlled studies reveal, at the single-molecule level, how pore size and chemical functionality determine the host-guest interactions.     

A 44.736 Mbits/s Codec for U600 Mastergroups

A coder-decoder which codes a 600 channel mastergroup into a 44.736 Mbits/s digital is described. It includes a double frequency shift of the mastergroup, eight bit coding with three segment companding, and has format and features necessary for operation in a telephone network.     

Primary processes of the thermal degradation of HET acid containing unsaturated polyester cured with styrene

The primary processes of thermal degradation of 1,4,5,6,7,7-hexachloro-5-norbornene-2,3-dicarboxylic (HET) group containing unsturated polyesters cured with styrene were investigated. DTA traces in nitrogen atmosphere showed a much more pronounced endothermic reaction as the chlorine content in the unsaturated polyester resin decreased. This could be associated to the unzipping of the polystyrene units which is interfered by hexachlorocyclopentadiene ejected during degradation. Actually the styrene formation is prevented in a certain range of temperature due to the interaction with hexachlorocyclopentadiene. This was proved by on-line mass spectroscopic analysis of the degrading polymer.     

Microarrays for the screening of allergen-specific IgE in human serum

The described in vitro test system for allergy diagnosis is based on microscope glass slides activated with (3-glycidyloxypropyl)trimethoxysilane. Allergen solutions are immobilized as small droplets (approximately 10 nL) on the activated glass slides with a piezoelectric arrayer. In contrast to other tests for specific IgE, such as Pharmacia CAP FEIA, AlaSTAT, or FAST, only a 25-microL serum sample is needed for the screening of allergen-specific IgE against a multitude of allergens and the test can be performed in less than 1 h. Compared with multiallergen dipstick screening tests (e.g., IgEquick, CMG Immunodot) based on multiallergen-coated nitrocellulose strips, the measurement of the microarray-based system can be performed automatically. The chemiluminescence intensities are detected with a sensitive CCD camera. Allergen extracts and recombinant/purified allergens (24 preparations) have been used on the same modified surface for the screening of allergen-specific IgE. With these disposable microarray slides, it is possible to distinguish between patients with and without elevated levels of allergen-specific IgE. Repeated measurements of serum samples demonstrated a sufficient reproducibility. Detection limits (microg/L) of 0.35 (r Betvl), 0.16 (PLA2), and 1.9 (Der p1) were achieved.