Restoring Orders of Accuracy for Multilevel Schemes for Non-linear Hyperbolic Systems in Many Space Variables

In this paper boundary procedures are discussed for a new secondorder accurate method, developed in Morris (1972) and Zwas,Eilon & Gottlieb (1972), for non-linear hyperbolic systemsin two space variables. This method is a multilevel scheme ofthe same type as those of Strang, (1964, 1968). It is shownthat the straightforward method of incorporating boundary datagives, in general, only locally first order accurate values.A boundary procedure which preserves local second order accuracyis developed. The method is also extended to systems in manyspace variables. The results of some numerical experiments arereported.     

Transitivity and Dense Periodicity for Graph Maps

In 1984, Blokh proved [A. M. Blockh, On transitive mappings of one-dimensional branched manifolds, Differential-Difference Equations and Problems of Mathematical physics (Russian), Akad. Nauk Ukrain. SSR Inst. Mat., Kiev, 131, pp. 3–9, 1984] that any topologically transitive continuous map from a graph into itself which has periodic points has a dense set of periodic points and has positive topological entropy (in this proof a crucial role is played by the specification property, which implies these two statements). Also, he characterized the topologically transitive continuous graph maps without periodic points. Unfortunately, this clever paper is only available in Russian (except for a translation to English of the statements of the theorems without proofs—see [A. M. Blockh, The connection between entropy and transitivity for one-dimensional mappings, Uspekhi Mat. Nauk, 42(5(257)) (1987), pp. 209–210]).     

Electric charge systems moving with the velocity of light and associated with charge creation

A discussion is given of certain electromagnetic fields associated with charges moving with the velocity of light which are associated with zero magnetic field, and the creation of charge. The stress energy tensor associated with charge creation is also discussed and it is shown that the stress energy tensor includes a term which may be interpreted as a shear.     

VIDAS enzyme-linked immunoflourescent assay for detection of Listeria in foods: collaborative study

The VIDAS LIS method and the traditional culture methods for detection of Listeria species in food were evaluated in a multilaboratory comparative study. The 6 foods tested were either naturally contaminated or inoculated with 3 different concentrations of Listeria. Results for each food and each contamination level with the VIDAS LIS method were as good as or better than those obtained with the traditional culture method. Of 1558 samples tested, 935 were positive: 839 by the VIDAS method and 809 by standard culture methods. Overall false negative rates were 10.3 and 13.5% for the VIDAS LIS and culture methods, respectively. The false positive rate for the VIDAS LIS assay was 1.4% based on 9 VIDAS LIS positive assays that did not confirm positive by isolation of Listeria. The agreement between the VIDAS LIS and culture methods for all samples tested was 86%.     

四乙基氯化胺-乙醇胺低共熔溶剂高效捕集CO2的研究

本文采用一步合成法制备不同摩尔比的TEAC-MEA DES;通过测定熔点,以及分析核磁和红外得出TE-AC-MEA DES之间是依靠氢键作用形成的DES.DES通过化学吸附CO2,生成了氨基甲酸酯,从而实现CO2的捕集;还研究了温度、HBA/HBD摩尔比、水含量、气体流速对DES吸收CO2的影响,结果表明CO2的吸收量...     

Isolation of NO(3)(-)-N as 1-phenylazo-2-naphthol (Sudan-1) for measurement of delta(15)N

The conversion of nitrate (NO(3)(-)) to 1-phenylazo-2-naphthol (Sudan-1) has been examined as a method for natural abundance measurement of delta(15)N of NO(3)(-). The reaction results in dilution of NO(3)(-)-N with only one reagent-derived N and the product is readily concentrated from dilute samples by reverse phase chromatography. There is systematic isotopic fractionation during the reaction, but this can be allowed for by analysing known NO(3)(-) standards along with each sample set. Sudan-1 prepared from surface water samples containing approximately 50 &mgr;g NO(3)(-)-N can be analysed by automated continuous flow isotope ratio mass spectrometry with a precision of 0.2 per thousand (one standard deviation) and the accuracy is not affected by interference from other nitrogenous species in the sample or reagents. Copyright 1999 John Wiley & Sons, Ltd.     

Linear Combinations of Generalized Crank Nicolson Schemes

The combination of two or more generalized Crank Nicolson schemesin order to obtain second, third and fourth order accurate discretizationsin time is considered. Particular attention is given to thestability properties of the methods proposed.