1,305 research outputs found

    Game-theoretic analysis of pay-as-bid mechanisms

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    Enterprises are facing a challenging dilemma. In order to be able to accommodate peak loads on their IT systems, they must maintain large computing clusters, which lie idle most of the time. At the same time, IT departments are under constant pressure to cut down on hard- and software expenses. Grid technology offers a promising way out of this dilemma by allowing the dynamic sharing both within enterprises as well as across organizational boundaries. This sharing approach, however, requires proper economic incentives. This paper is concerned with the determination of dynamic market-based prices. Due to their simplicity, so-called pay-as-bid mechanisms have become popular. This paper is novel as we provide an in-depth analysis of two such pay-as-bid mechanisms – Proportional Share and a discriminatory pay-as-bid mechanism – for the case of three users, thus extending previous work by Sanghavi and Hajek (2004) and Stößer et al. (2008). This analysis is important as we show that the nice results for two users cannot be retained once three or more users are present. Even worse, we show that these results can even be reversed if we move to games with more than two players

    Budding and Fission Yeast Casein Kinase-I Isoforms Have Dual-Specificity Protein-Kinase Activity

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    We have examined the activity and substrate specificity of the Saccharomyces cerevisiae Hrr25p and the Schizosaccharomyces pombe Hhp1, Hhp2, and Cki1 protein kinase isoforms. These four gene products are isotypes of casein kinase I (CKI), and the sequence of these protein kinases predicts that they are protein serine/threonine kinases. However, each of these four protein kinases, when expressed in Escherichia coli in an active form, was recognized by anti-phosphotyrosine antibodies. Phosphoamino acid analysis of P-32-labeled proteins showed phosphorylation on serine, threonine, and tyrosine residues. The E. coli produced forms of Hhp1, Hhp2, and Cki1 were autophosphorylated on tyrosine, and both Hhp1 and Hhp2 were capable of phosphorylating the tyrosine-protein kinase synthetic peptide substrate polymer poly-E(4)Y(1). Immune complex protein kinases assays from S. pombe cells showed that Hhp1-containing precipitates were associated with a protein-tyrosine kinase activity, and the Hhp1 present in these immunoprecipitates was phosphorylated on tyrosine residues. Although dephosphorylation of Hhp1 and Hhp2 by Ser/Thr phosphatase had little effect on the specific activity, tyrosine dephosphorylation of Hhp1 and Hhp2 caused a 1.8-to 3.1-fold increase in the Km for poly-E(4)Y(1) and casein. These data demonstrate that four different CKI isoforms from two different yeasts are capable of protein-tyrosine kinase activity and encode dual-specificity protein kinases

    Increased unsaturation of lipids in cytoplasmic lipid droplets in DAOY cancer cells in response to cisplatin treatment.

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    Increases in 1H nuclear magnetic resonance spectroscopy (NMR) visible lipids are a well-documented sign of treatment response in cancers. Lipids in cytoplasmic lipid droplets (LDs) are the main contributors to the NMR lipid signals. Two human primitive neuroectodermal tumour cell lines with different sensitivities to cisplatin treatment were studied. Increases in NMR visible saturated and unsaturated lipids in cisplatin treated DAOY cells were associated with the accumulation of LDs prior to DNA fragmentation due to apoptosis. An increase in unsaturated fatty acids (UFAs) was detected in isolated LDs from DAOY cells, in contrast to a slight decrease in UFAs in lipid extracts from whole cells. Oleic acid and linoleic acid were identified as the accumulating UFAs in LDs by heteronuclear single quantum coherence spectroscopy (HSQC). 1H NMR lipids in non-responding PFSK-1 cells were unchanged by exposure to 10 μM cisplatin. These findings support the potential of NMR detectable UFAs to serve as a non-invasive marker of tumour cell response to treatment

    Changes in climatic elements and their impact on production of cardamom (Elettaria cardamomum Maton) in the Cardamom Hills of Kerala, India

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    The change in climatic elements namely, temperature and precipitation in Cardamom Hills (Kerala, India) was studied by analysing the weather data for 20 (temperature) and 40 years (precipitation). Minimum temperature exhibited drastic variation over the years. The difference betWeen the warmest and coolest month had narrowed considerably and the days have become warmer markedly. Except during 1967-76 (Decade-II) the total annual average precipitation received was more or less equal. Even though the total number of rainy days has increased, the distribution pattern was erratic during the last decade. The rainfall parameters had positive correlation with production of cardamom (Elettaria cardamomum) with significant relationship for number of rainy days. &nbsp

    Changes in climatic elements and their impact on production of cardamom (Elettaria cardamomum Maton) in the Cardamom Hills of Kerala, India

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    The change in climatic elements namely, temperature and precipitation in Cardamom Hills (Kerala, India) was studied by analysing the weather data for 20 (temperature) and 40 years (precipitation). Minimum temperature exhibited drastic variation over the years. The difference betWeen the warmest and coolest month had narrowed considerably and the days have become warmer markedly. Except during 1967-76 (Decade-II) the total annual average precipitation received was more or less equal. Even though the total number of rainy days has increased, the distribution pattern was erratic during the last decade. The rainfall parameters had positive correlation with production of cardamom (Elettaria cardamomum) with significant relationship for number of rainy days. &nbsp

    Membrane attachment of Slr0006 in Synechocystis sp PCC 6803 is determined by divalent ions

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    Slr0006 is one of the Synechocystis sp. PCC 6803 proteins strongly induced under carbon limiting conditions. Slr0006 has no predicted transmembrane helices or signal peptide sequence, yet it was exclusively recovered in the membrane fraction of Synechocystis, when the cells were broken in isolation buffers which contain divalent cations and are generally used for photosynthesis studies. Even subsequent washing of the membranes with high salt or various detergents did not release Slr0006, indicating strong binding of the Slr0006 protein to the membranes. Further, DNAse or RNAse treatment did not disturb the tight binding of Slr0006 protein to the membranes. Nevertheless, when the cells were broken in the absence of divalent cations, Slr0006 remained completely soluble. Binding of the Slr0006 to the membrane could not be properly reconstituted if the cations were added after breaking the cells in the absence of divalent ions. This unusual phenomenon has to be considered in identification and localization of other yet uncharacterized cyanobacterial proteins

    Light-induced self-synchronizing flow patterns

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    In this paper, we present the observation of light-induced self-synchronizing flow patterns in a light-fluid system. A light beam induces local flow patterns in a fluid, which oscillate periodically or chaotically in time. The oscillations within different regions of the fluid interact with each other through heat-and surface-tension-induced fluid waves, and they become synchronized. We demonstrate optical control over the state of synchronization and over the temporal correlation between different parts of the flow field. Finally, we provide a model to elucidate these results and we suggest further ideas on light controlling flow and vice versa
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