Borel chromatic number of closed graphs

We construct, for each countable ordinal $\xi$, a closed graph with Borel chromatic number two and Baire class $\xi$ chromatic number $\aleph\_0$.Comment: The proof of the main lemma has been changed, and the main result is now better than in the previous versio

Too good to be true: pitfalls of usingmean Ellenberg indicator values in vegetation analyses

Question: Mean Ellenberg indicator values (EIVs) inherit information about compositional similarity, because during their calculation species abundances (or presence–absences) are used as weights. Can this similarity issue actually be demonstrated, does it bias results of vegetation analyses correlating mean EIVs with other aspects of species composition and how often are biased studies published? Methods: In order to separate information on compositional similarity possibly present in mean EIVs, a new variable was introduced, calculated as a weighted average of randomized species EIVs. The performance of these mean randomized EIVs was compared with that of the mean real EIVs on the one hand and random values (randomized mean EIVs) on the other. To demonstrate the similarity issue, differences between samples were correlated with dissimilarity matrices based on various indices. Next, the three mean EIV variables were tested in canonical correspondence analysis (CCA), detrended correspondence analysis (DCA), analysis of variance (ANOVA) between vegetation clusters, and in regression on species richness. Subsequently, a modified permutation test of significance was proposed, taking the similarity issue into account. In addition, an inventory was made of studies published in the Journal of Vegetation Science and Applied Vegetation Science between 2000 and 2010 likely reporting biased results due to the similarity issue. Results: Using mean randomized EIVs, it is shown that compositional similarity is inherited into mean EIVs and most resembles the inter-sample distances in correspondence analysis, which itself is based on iterative weighted averaging. The use of mean EIVs produced biased results in all four analysis types examined: unrealistic (too high) explained variances in CCA, too many significant correlations with ordination axes in DCA, too many significant differences between cluster analysis groups and too high coefficients of determination in regressions on species richness. Modified permutation tests provided ecologically better interpretable results. From 95 studies using Ellenberg indicator values, 36 reported potentially biased results. Conclusions: No statistical inferences should bemade in analyses relatingmean EIVs with other variables derived from the species composition as this can produce highly biased results, leading to misinterpretation. Alternatively, a modified permutation test using mean randomized EIVs can sometimes be used

Certification of the Deuterium-to-Hydrogen (D/H) amount-of-substance ratio in a 1,1,3,3 - tetramethylurea batch: Certified Reference Material STA-003m

This report describes the production of a tetramethylurea (TMU) reference material (STA-003m), certified for its deuterium-to-hydrogen (D/H) amount-of-substance ratio. The material is to be used as an internal standard in site-specific natural isotope fractionation – nuclear magnetic resonance (SNIF-NMR) spectrometry measurements for determining the D/H amount-of-substance ratios of ethanol distilled from wines, an important measure in wine authenticity testing (Commission Regulation 2676/90). Commercially obtained TMU with a sufficiently high D/H amount-of-substance ratio (>120 x 10-6) was first purified by removing most of the residual water and then filled into amber glass bottles of 500 mL. Between-unit homogeneity was quantified and stability during dispatch and storage were assessed in accordance with ISO Guide 35:2006. Batch characterisation was accomplished by comparing STA-003m samples with samples of the TMU master batch (IRMM-425) under repeatability conditions and by adhering to the SNIF-NMR technique. The certified value was calculated as the unweighted mean of 18 individual results obtained on 3 different NMR appliances. The uncertainty of the certified value was estimated in compliance with ISO Guide 98-3, Guide to the Expression of Uncertainty in Measurement (GUM); it includes contributions from possible inhomogeneity, instability, and characterisation.JRC.D.2-Standards for Innovation and sustainable Developmen

On Multiobjective Evolution Model

Self-Organized Criticality (SOC) phenomena could have a significant effect on the dynamics of ecosystems. The Bak-Sneppen (BS) model is a simple and robust model of biological evolution that exhibits punctuated equilibrium behavior. Here we will introduce random version of BS model. Also we generalize the single objective BS model to a multiobjective one.Comment: 6 pages, 5 figure

A comparative study of two key algorithms in multiple objective linear programming

Multiple objective linear programming problems are solved with a variety of algorithms. While these algorithms vary in philosophy and outlook, most of them fall into two broad categories: those that are decision space-based and those that are objective space-based. This paper reports the outcome of a computational investigation of two key representative algorithms, one of each category, namely the parametric simplex algorithm which is a prominent representative of the former and the primal variant of Bensons Outer-approximation algorithm which is a prominent representative of the latter. The paper includes a procedure to compute the most preferred nondominated point which is an important feature in the implementation of these algorithms and their comparison. Computational and comparative results on problem instances ranging from small to medium and large are provided