A short note on three Nilotonia species from Trinidad (Acariformes: Hydrachnidia: Anisitsiellidae)

International audienceExamination of three Nilotonia species described by Bader (1995) revealed, that they all belong to Anisitsiella aculeata Daday

Computing graph gonality is hard

There are several notions of gonality for graphs. The divisorial gonality dgon(G) of a graph G is the smallest degree of a divisor of positive rank in the sense of Baker-Norine. The stable gonality sgon(G) of a graph G is the minimum degree of a finite harmonic morphism from a refinement of G to a tree, as defined by Cornelissen, Kato and Kool. We show that computing dgon(G) and sgon(G) are NP-hard by a reduction from the maximum independent set problem and the vertex cover problem, respectively. Both constructions show that computing gonality is moreover APX-hard.Comment: The previous version only dealt with hardness of the divisorial gonality. The current version also shows hardness of stable gonality and discusses the relation between the two graph parameter

A new method for the separation of androgens from estrogens and for the partition of estriol from the estrone-estradiol fraction: with special reference to the identification and quantitative microdetermination of estrogens by ultraviolet absorption spectrophotometry

It is recognized generally that a qualitative and quantitative knowledge of the excretion pattern of the urinary estrogens is one index to an understanding of the functional activity of the ovary and adrenal cortex. Obviously, such determinations may be useful also in evaluating the normal and abnormal functions of other physiologically related endocrine glands as well as of organs like the liver and kidneys. The clinical applications of these data are self-evident. Various attempts have been made to circumvent the notoriously inaccurate values which have been obtained for the urinary estrogens by a variety of bioassay methods and calorimetric techniques (1, 2). The acknowledged shortcomings of these methods have led us to investigate the application of ultraviolet absorption spectrophotometry to the quantitative determination of the urinary estrogens in an attempt to develop an objective physical method for their accurate determination. It is known that the infra-red portion of the spectrum yields more differentially characteristic curves, but those of the ultraviolet range are more readily obtainable, and consequently better adapted to clinical use. This communication is concerned with studies of the following aspects of the problem: (1) spectrophotometric identification and quantitative micro determination of crystalline estrogens; (2) detection by spectrophotometric assay of gross errors in current methods for extraction and partition of estrogens; (3) studies on the ultraviolet absorption of substances comprising the background material; (4) separation of the phenolic estrogens from the so called neutral steroid fraction; (5) separation of urinary estrogens from other urinary phenolic substances by steam distillation; (6) micro-Girard separation of estrone from estradiol; (7) an essentially new method for the extraction and partition of crystalline estrone, estradiol, and estriol, and their quantitative assay by ultraviolet spectrophotometry

Popper and Wittgenstein on the Metaphysics of Experience

In the Tractatus Wittgenstein argued that there are metaphysical truths. But these are ineffable, for metaphysical sentences try to say what can only be shown. Accordingly, they are pseudo-propositions because they are ill-formed. In the Investigations he no longer thought that metaphysical propositions are pseudo-propositions, but argued that they are either nonsense or norms of descriptions. Popper criticized Wittgenstein’s ideas and argued that metaphysical truths are effable. Yet it is by now clear that he misunderstood Wittgenstein’s arguments (namely that metaphysical propositions are ill-formed because they employ unbound variables) and misguidedly thought that Wittgenstein used the principle of verification for distinguishing empirical propositions from metaphysical propositions. Because Popper developed his philosophy in part as a critique of Wittgenstein’s philosophy, this invites the question of whether these misunderstandings have consequences for his own philosophy. I discuss this question and argue that Popper’s attempt to distinguish metaphysics and science with the aid of a criterion of testability is from Wittgenstein’s perspective misguided. The main problem facing Popper’s philosophy is that alleged metaphysical propositions are not theoretical propositions but rules for descriptions (in the misleading guise of empirical propositions). If Wittgenstein’s ideas are correct, then metaphysical problems are not scientific but grammatical problems which can only be resolved through conceptual investigations