This paper presents two strategies for multi‐way testing (i.e. t‐way testing with t>2). The first strategy generalizes an existing strategy, called in‐parameter‐order, from pairwise testing to multi‐way testing. This strategy requires all multi‐way combinations to be explicitly enumerated. When the number of multi‐way combinations is large, however, explicit enumeration can be prohibitive in terms of both the space for storing these combinations and the time needed to enumerate them. To alleviate this problem, the second strategy combines the first strategy with a recursive construction procedure to reduce the number of multi‐way combinations that have to be enumerated. Both strategies are deterministic, i.e. they always produce the same test set for the same system configuration. This paper reports a multi‐way testing tool called FireEye, and provides an analytic and experimental evaluation of the two strategies. Copyright © 2007 John Wiley & Sons, Ltd.

A collaborative study was conducted for the determination of paralytic shellfish poisoning (PSP) toxins in shellfish. The method used liquid chromatography with fluorescence detection after prechromatographic oxidation of the toxins with hydrogen peroxide and periodate. The PSP toxins studied were saxitoxin (STX), neosaxitoxin (NEO), gonyautoxins 2 and 3 (GTX2,3; together), gonyautoxins 1 and 4 (GTX1,4; together), decarbamoyl saxitoxin (dcSTX), B-1 (GTX5), C-1 and C-2 (C1,2; together), and C-3 and C-4 (C3,4; together). B-2 (GTX6) toxin was also included, but for qualitative identification only. Mussels, both blank and naturally contaminated, were mixed and homogenized to provide a variety of PSP toxin mixtures and concentration levels. The same procedure was followed with clams, oysters, and scallops. Twenty-one test samples in total were sent to 21 collaborators who agreed to participate in the study. Results were obtained from 18 laboratories representing 14 different countries. It is recommended that the method be adopted First Action by AOAC INTERNATIONAL.

No abstract

A series of 22 lakes in southern Quebec spanning a wide trophic range were sampled to develop models of changes in cyanobacterial abundance and toxicity. All lakes contained toxic cyanobacteria, and epilimnetic toxin content, expressed as microcystin equivalents, was best predicted by total nitrogen concentration and total phosphorus concentration (TP). Although phytoplankton biomass increased linearly with increases in TP among lakes, toxigenic biomass increased as greater than the squared power of TP. The only potentially toxigenic genera whose biomass was correlated with microcystin concentration were Microcystis and Anabaena. Surprisingly, the best model for toxicspecies biomass was based on epilimnetic nitrogen. The level of the hepatotoxin microcystin per unit biomass in these organisms did not vary markedly among lakes, supporting the idea that environmental factors control the occurrence, but have only a limited effect on the toxicity, of potentially toxic species.Résumé : Nous avons échantillonné une série de 22 lacs du sud du Québec couvrant une large gamme trophique afin de mettre au point des modèles du changement d'abondance et de toxicité des cyanobactéries. Tous les lacs contiennent des cyanobactéries toxiques et le contenu de toxines dans l'épilimnion, exprimé en équivalents de microcystine, est prédit le mieux par les concentrations d'azote total (TN) et de phosphore total (TP). Bien que la masse du phytoplancton s'accroisse de façon linéaire en fonction de l'accroissement de TP parmi les lacs, la biomasse des toxigènes augmente plus rapidement que la puissance au carré de TP. Les seuls genres potentiellement toxigènes dont la biomasse est en corrélation avec la concentration de microcystine sont Microcystis et Anabaena. De façon inattendue, le meilleur modèle de la biomasse des espèces toxiques est basé sur l'azote de l'épilimnion. La concentration chez ces organismes de l'hépatotoxine microcystine par unité de biomasse ne varie pas considérablement d'un lac à l'autre, ce qui appuie la proposition que les facteurs du milieu contrôlent la présence des espèces potentiellement toxiques, mais qu'ils ont un effet limité sur leur toxicité.[Traduit par la Rédaction] Giani et al. 2109

Given a subset L of the 2 d closed orthants in ^-dimensional Euclidean space, is there a convex set K which intersects those closed orthants in L, while missing those not in L? A strong combinatorial condition on L, which is necessary for the existence of such a convex set, is exhibited. This condition is studied and its close connections with the theory of oriented matroids are examined. The sets L satisfying this conditionthe "lopsided" sets -have a rich combinatorial structure which can be exploited in the study of convex sets and systems of linear inequalities.1. Introduction. Let E be a finite set and denote by V(E) the vector space of all real-valued functions / on E. Let C(E) denote the subset of V(E) consisting of all functions/from E to the set { -1,1}, so that C(E) is the set of vertices of a cube in V(E). If/is in C( E), then the set: