4,306 research outputs found

    TypEx : a type based approach to XML stream querying

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    We consider the topic of query evaluation over semistructured information streams, and XML data streams in particular. Streaming evaluation methods are necessarily eventdriven, which is in tension with high-level query models; in general, the more expressive the query language, the harder it is to translate queries into an event-based implementation with finite resource bounds

    Extracting partition statistics from semistructured data

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    The effective grouping, or partitioning, of semistructured data is of fundamental importance when providing support for queries. Partitions allow items within the data set that share common structural properties to be identified efficiently. This allows queries that make use of these properties, such as branching path expressions, to be accelerated. Here, we evaluate the effectiveness of several partitioning techniques by establishing the number of partitions that each scheme can identify over a given data set. In particular, we explore the use of parameterised indexes, based upon the notion of forward and backward bisimilarity, as a means of partitioning semistructured data; demonstrating that even restricted instances of such indexes can be used to identify the majority of relevant partitions in the data

    Backward-looking analysis

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    We develop a new modelling approach combining micro and macro simulations to analyse distributional and stabilizing effects of a European Unemployment Benefit System (EUBS). We run counterfactual simulations based on micro data for the period 1995 to 2013 to estimate net contributions for different variants of EUBS across European member states. Our micro estimates are then used to feed the macro-econometric model in order to obtain counterfactual evolutions of income and unemployment. These new income and employment series are finally simulated again at the micro level. We compare results before and after taking account of the macroeconomic feedback effects and analyse the difference that the feedback effects make.This paper was written as part of Task 3B for the research project 'Feasibility and Added Value of a European Unemployment Benefit Scheme' (contract VC/2015/0006)

    Chronic dietary intake of enniatin B in broiler chickens has low impact on intestinal morphometry and hepatic histology, and shows limited transfer to liver tissue

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    The Fusarium mycotoxin enniatin B (ENN B) is a so-called emerging mycotoxin frequently contaminating poultry feed. To investigate the impact of chronic ENN B exposure on animal health, broiler chickens were fed either a diet naturally contaminated with ENN B (2352 mu g/kg) or a control diet (135 mu g/kg) for 2, 7, 14, or 21 days. ENN B concentrations were determined in plasma and liver using a validated ultra-high performance liquid chromatographytandem mass spectrometry UHPLC-MS/MS method. Liver was evaluated histologically, and the villus length and crypt depth of the duodenum, jejunum, and ileum were measured. Histopathology of the livers did not reveal major abnormalities. Feeding an ENN B-contaminated diet could possibly inhibit the proliferation of enterocytes in the duodenal crypts, but did not affect villus length, crypt depth, or villus length-crypt depth ratio of the jejunum and ileum. ENN B levels in plasma and liver were significantly higher in the ENN B-fed group and ranged between <25-264 pg/mL and <0.05-0.85 ng/g, respectively. ENN B carry-over rates from feed to liver tissue were 0.005-0.014% and 0.034-0.109% in the ENN B and control group, respectively. Carry-over rates were low and indicated a limited contribution of poultry tissue-derived products to the total dietary ENN B intake for humans. The above results support the opinion of the European Food Safety Authority stating that adverse health effects from ENN B in broiler chickens are unlikely

    End-group functionalization of poly(2-oxazoline)s using methyl bromoacetate as initiator followed by direct amidation

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    Poly(2-alkyl/aryl-2-oxazoline)s (PAOx) are an alluring class of polymers for many applications due to the broad chemical diversity that is accessible for these polymers by simply changing the initiator, terminating agent and the monomer(s) used in their synthesis. Additional functionalities (that are not compatible with the cationic ring-opening polymerization) can be introduced to the polymers via orthogonal post-polymerization modifications. In this work, we expand this chemical diversity and demonstrate an easy and straightforward way to introduce a wide variety of functional end-groups to the PAOx, by making use of methyl bromoacetate (MeBrAc) as a functional initiator. A kinetic study for the polymerization of 2-ethyl-2-oxazoline (EtOx) in acetonitrile (CH3CN) at 140 degrees C revealed relatively slow initiation and slower polymerization than the commonly used initiator, methyl tosylate (MeOTs). Nonetheless, well-defined polymers could be obtained with MeBrAc as initiator, yielding polymers with near-quantitative methyl ester end-group functionality. Next, the post-polymerization modification of the methyl ester end-group with different amines was explored by introducing a range of functionalities, i.e. hydroxyl, amino, allyl and propargyl end-groups. The lower critical solution temperature (LCST) behavior of the resulting poly(2-ethyl-2-oxazoline)s was found to vary substantially in function of the end-group introduced, whereby the hydroxyl group resulted in a large reduction of the cloud point transition temperature of poly(2-ethyl-2-oxazoline), ascribed to hydrogen bonding with the polymer amide groups. In conclusion, this paper describes an easy and fast modular approach for the preparation of end-group functionalized PAOx

    Robust design of all-optical PSK regenerator based on phase sensitive amplification

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    More compact, stable, and efficient configuration of a recently-developed regenerator is presented. The regenerator is assessed at data rates up to 56 Gbit/s using white phase noise for the first time

    Experimental Testing and modeling of a Dual-Fired LiBr-H2O Absorption Chiller

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    An LiBr-H2O chiller was modified to utilize heat sources from natural gas combustion and/or from hot fluid. This was achieved by replacing the original gas-fired generator with a dual-fired generator. Steam was used as the hot fluid. The generator of the chiller can be powered by each source separately or both sources simultaneously. Experimental investigation was performed to obtain capacity and coefficient of performance (COP) of the original chiller and the modified chiller. During the experiments, the modified chiller was powered solely by steam, natural gas, or both. There was a significant increase in COP and capacity when steam was used as a heat source. The tests using natural gas resulted in performance similar to the original chiller. The experimental conditions were closely modeled by a numerical program
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