Breaks of gauge’ in Australian railway history: the significance of standardisation in national infrastructures

Australia’s railway suffered from breaks of gauge from the beginning of the systems’ development in the 1850s and long after the foundation of the federation in 1901. The failure was caused by economic, social and political factors, and it brought significant consequences for each of those domains. While explaining the causes and impacts of breaks of gauge, we consider economic and technological factors in the development of the railway network. We suggest that economic considerations of Australian territories and the governance structure of the federation were the key factors causing the breaks of gauges. The consequences were significant for economic development and demonstrate the prominence of standardisation in the technological and economic development of national infrastructures. The lessons learned have implications for standardisation in developing national infrastructures

Photoproduktion von -Endzustaenden im Energiebereich von 20-70 GeV

SIGLEAvailable from the library of Bonn Univ. (DE) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Excluding Hooks and their Complements

The long-standing Erdős-Hajnal conjecture states that for every n-vertex undirected graph H there exists ϵ(H)>0 such that every graph G that does not contain H as an induced subgraph contains a clique or an independent set of size at least nϵ(H). A natural weakening of the conjecture states that the polynomial-size clique/independent set phenomenon occurs if one excludes both H and its complement Hc. These conjectures have been shown to hold for only a handful of graphs: it is not even known if they hold for all graphs on 5vertices.In a recent breakthrough, the symmetrized version of the Erdős-Hajnal conjecture was shown to hold for all paths. The goal of this paper is to show that the symmetrized conjecture holds for all trees on 6(or fewer) vertices. In fact this is a consequence of showing that the symmetrized conjecture holds for any path with a pendant edge at its third vertex; thus we also give a new infinite family of graphs for which the symmetrized conjecture holds

DNA barcoding and faunistic criteria for a revised taxonomy of Italian Ephemeroptera

<p>Mayfly (Ephemeroptera) systematics has considerably changed over the years, but many questions have yet to be answered. The synergistic connection between traditional knowledge and new data sources, producing increasingly complex information, has become a compelling issue for modern taxonomy. Molecular tests and the use of reliable reference sequence libraries may constitute effective complements to the traditional method in guiding recognition of species and giving information about taxonomic incongruences which require further examination. In the present study, we sought to verify the current Italian mayfly nomenclatural system through DNA barcoding and relevant points to reliably manage the available amount of morpho-ecological and molecular data are discussed. We investigated COI (Cytochrome oxidase I) sequence variation in 163 individuals of Italian mayflies, 126 of which were previously assigned to 24 morphologically recognised species, and 37 could be attributed only to generic taxonomic entities (“sp.”, “cf.” or “gr.”). DNA barcoding statistical tests for species delimitation hypotheses based on genetic distances and inferred gene trees were integrated with GenBank searches and surveys of the historical literature to better understand the knowledge acquired on the status and diversity of the investigated taxa. Combined criteria to define three categories of reliability were then assessed. Concurrent data allowing unambiguous identification were attained for only eight species. High intraspecific genetic distances (> 3%) and a lack of reliable reference material or convincing taxonomic information evidenced 29 critical states, deserving further investigation. Solid species names, potential cryptic species and entities about which little is known are pointed out for a future upgrade/reorganisation of the taxonomy of Italian Ephemeroptera.</p