Ornithine decarboxylase gene deletion mutants of Leishmania donovani

A knockout strain of Leishmania donovani lacking both ornithine decarboxylase (ODC) alleles has been created by targeted gene replacement. Growth of Deltaodc cells in polyamine-deficient medium resulted in a rapid and profound depletion of cellular putrescine pools, although levels of spermidine were relatively unaffected. Concentrations of trypanothione, a spermidine conjugate, were also reduced, whereas glutathione concentrations were augmented. The Deltaodc L. donovani exhibited an auxotrophy for polyamines that could be circumvented by the addition of the naturally occurring polyamines, putrescine or spermidine, to the culture medium. Whereas putrescine supplementation restored intracellular pools of both putrescine and spermidine, exogenous spermidine was not converted back to putrescine, indicating that spermidine alone is sufficient to meet the polyamine requirement, and that L. donovani does not express the enzymatic machinery for polyamine degradation. The lack of a polyamine catabolic pathway in intact parasites was confirmed radiometrically. In addition, the Deltaodc strain could grow in medium supplemented with either 1,3-diaminopropane or 1, 5-diaminopentane (cadaverine), but polyamine auxotrophy could not be overcome by other aliphatic diamines or spermine. These data establish genetically that ODC is an essential gene in L. donovani, define the polyamine requirements of the parasite, and reveal the absence of a polyamine-degradative pathway.     

Native-oxide-based selective area growth of InP nanowires via metal-organic molecular beam epitaxy mediated by surface diffusion

The growth of InP nanowires on an InP(111) B substrate is reported. The substrate native oxide was not removed from the surface prior to growth. Nanowires were grown at 400 °C from gold catalysts in a selective area manner, without bulk growth. Unlike SiO(2)-based metal-organic molecular beam epitaxy selective area growth, the growth reported here is mediated by surface diffusion with a characteristic diffusion length of 4 μm, about an order of magnitude larger than values for diffusion on bare substrates. A pre-growth heating treatment at 450 °C was found to increase the yield of nanowire nucleation from the gold catalysts.     

Collaborative capacity sharing among manufacturers on the same supply network horizontal layer for sustainable and balanced returns

To deal with volatile demand and rapidly changing manufacturing technologies for sustainable returns, as a solution, collaborative capacity sharing (CCS) among manufacturers at the same horizontal layer in supply networks is discussed in this research, especially focusing on a long-term aspect. Such horizontal collaboration can minimise manufacturers’ lost sales, as well as maximise their production capacity utilisation in a long-term period against lumpy demand. Hence, to help manufacturers determine whether and with whom they have to collaborate a CCS protocol based on a theoretical analysis is developed. It is a distributed decision protocol suggesting an effective coalition for each manufacturer. Furthermore, for well-balanced distribution of resulting profits to each manufacturer, two procedures are proposed: (1) determination of appropriate substitution production cost and (2) bids among manufacturers/coalitions. To evaluate the effect of those processes, two types of CCS protocols are designed – CCS-(1) and CCS-(2); only CCS-(2) performs those procedures. A numerical experiment is conducted to compare the performance of four models: No collaboration, complete collaboration, and two types of selective collaboration by CCS-(1) and CCS-(2). The performance of CCS-(2) is at least equal to or better than other models with higher and balanced returns.     

Chemical modification of polynorbornene: transformation of ester moiety containing polynorbornene to carboxylic acid structure

Polynorbornene (PNB) having methyl ester in side chain was partially hydrolyzed under alkaline condition in mixed organic solvents containing tetramethylammonium hydroxide as a base. Through hydrolysis of methyl ester group in PNB under basic condition, PNB having carboxylic acid can be obtained and degree of hydrolysis (DH) were evaluated by ¹H NMR measurement from 0.1 to 0.8, depending upon reaction conditions such as reaction time, solvent, and amount of base. The resulting hydrolyzed PNB were characterized by differential scanning calorimetry, Fourier transform infrared spectroscopy, and size exclusion chromatography. No remarkable decreasing of molecular weight was observed and chain scission does not occur during the hydrolysis of PNB in the reaction condition examined here. The glass transition temperature of hydrolyzed PNB increased with increase in DH which can be attributed to the existence of intermacromolecular association of carboxylic acid in hydrolyzed PNB. Esterification of PNB having carboxylic acid was also carried out by using alkyl halide and DBU.     

Oil prices,speculation, and fundamentals: Interpreting causal relations among spot and futures prices

A consensus that the world oil market is unified begs the question, where do innovations in oil prices enter the market? Here we investigate where changes in the price of crude oil originate and how they spread by examining causal relationships among prices for crude oils from North America, Europe, Africa, and the Middle East on both spot and futures markets. Results indicate that innovations first appear in spot prices for Dubai–Fateh and spread to other spot and futures prices while other innovations first appear in the far month contract for West Texas Intermediate and spread to other exchanges and contracts. Links between spot and futures markets are relatively weak and this may have allowed the long-run relationship between spot and future prices to change after September 2004. Together, these results suggest that market fundamentals initiated a long-term increase in oil prices that was exacerbated by speculators, who recognized an increase in the probability that oil prices would rise over time.     

The TSIMMIS Approach to Mediation: Data Models and Languages

TSIMMIS—The Stanford-IBM Manager of Multiple InformationSources—is a system for integrating information. It offers a datamodel and a common query language that are designed to support thecombining of information from many different sources. It also offerstools for generating automatically the components that are needed tobuild systems for integrating information. In this paper we shalldiscuss the principal architectural features and their rationale.     

Distributed planning of collaborative production

Collaborative production is viewed in two related dimensions: collaboration among machines to achieve increased reliability, quality and productivity; and collaboration between machines and human supervisors to combine internal and global control information. A structure, combining centralised planning and human-machine integration, is developed for distributed planning of such collaborative production. The centralised planning relies on game-theoretic optimisation techniques supported by knowledge-based rules for coalition formation of cooperating production operations. The product of the centralised planner is a general, common production plan. The feasibility of this model is demonstrated mathematically. If the centralised planner cannot reach a solution, then human input is sought. For integrating the human and machine knowledge to reach effective solutions, a neural network model is demonstrated. A simulation demonstrates that the distributed human and machine inputs can be combined under this framework. Such a distributed planning structure can overcome the major difficulties encountered in computerised production systems that seek full automation.