Phylogeny of the Subfamilies of Ichneumonidae (Hymenoptera)

A combined morphological and molecular phylogenetic analysis was performed to evaluate the subfamily relationships of the parasitoid wasp family Ichneumonidae (Hymenoptera). Data were obtained by coding 135 morphological and 6 biological characters for 131 exemplar species of ichneumonids and 3 species of Braconidae (the latter as outgroups). The species of ichneumonids represent all of the 42 currently recognized subfamilies. In addition, molecular sequence data (cytochrome oxidase I “DNA barcoding” region, the D2 region of 28S rDNA and part of the F2 copy of elongation factor 1-alpha) were obtained from specimens of the same species that were coded for morphology (1309 base pairs total). The data were analyzed using parsimony and Bayesian analyses. The parsimony analysis using all data recovered previ-ously recognized informal subfamily groupings (Pimpliformes, Ophioniformes, Ichneumoniformes), al-though the relationships of these three groups to each other differed from previous studies and some of the subfamily relationships within these groupings had not previously been suggested. Specifically, Ophioni-formes was the sister group to (Ichneumoniformes + Pimplformes), and Labeninae was placed near Ich-neumoniformes, not as sister group to all Ichneumonidae except Xoridinae. The parsimony analysis using only morphological characters was poorly resolved and did not recover any of the three informal subfamily groupings and very few of the relationships were similar to the total-evidence parsimony analysis. The mo-lecular-only parsimony analysis and both Bayesian analyses (total-evidence and molecular-only) recovered Pimpliformes, a restricted Ichneumoniformes grouping and many of the subfamily groupings recovered in the total-evidence parsimony analysis. A comparison and discussion of the results obtained by each phylo-genetic method and different data sets is provided. It is concluded that the molecular characters produced results that were relatively consistent with traditional, non-phylogenetic concepts of relationships between the ichneumonid subfamilies, whereas the morphological characters did not (at least not by themselves). The inclusion of both molecular and morphological characters using parsimony produced a topology that was the closest to the traditional subfamily relationships. The method of analysis did not greatly affect the overall topology for the molecular-only analyses, but there were differences between Bayesian and parsi-mony results for the total-evidence analyses (especially near the root of the tree). The Bayesian results did not seem to be altered very much by the inclusion of morphological characters, unlike in the parsimony analysis. In summary, the following groups were supported in multiple analyses regardless of the characters used or method of tree-building: Pimpliformes, higher Ophioniformes, higher Pimpliformes, (Claseinae + Pedunculinae), (Banchinae + Stilbopinae), Campopleginae, Cremastinae, Diplazontinae, Ichneumoninae (including Alomya), Labeninae, Ophioninae, Poemeniinae, Rhyssinae, and Tersilochinae sensu stricto. Conversely, Ctenopelmatinae and Tryphoninae were never recovered without inclusion of other taxa. Based on the hypothesis of relationships obtained by the total-evidence parsimony analysis, the following formal taxonomic changes are proposed: Alomyinae Förster (= Alomya Panzer and Megalomya Uchida) is once again synonymized with Ichneumoninae and is now considered a tribe (Alomyini rev. stat.); and Notostilbops Townes is transferred from Stilbopinae to Banchinae, tribe Atrophini

Application of the Local Approach to Cleavage Fracture to Failure Predictions of Heat Affected Zones

With the increased capabilities of elastic-plastic finite element analyses and hence the possibilities to determine accurately the stress distribution ahead of sharp cracks the use of fracture risk predictions based on a local fracture parameter has recently attracted much interest. To date most investigations in this area concentrated on homogeneous materials avoiding the complications related to the complex situation of welded joints. In this paper results are presented where the Local Approach to cleavage fracture has been applied to the heat affected zone of two structural steel welds. Local cleavage fracture parameters were determined from tests and finite element modelling of notched tensile specimens. In all cases the properties of the weld metal, the parent material and the heat affected zone (HAZ) were determined. A thermal simulation technique was used to produce large enough areas of HAZ microstructures for tensile and notched tensile testing. Subsequent application of the Local Approach to the crack tip situation for the prediction of the dependence of fracture toughness on temperature and the scatter in fracture toughness only produced satisfactory results for a limited number of the situations modelled. Discrepancies between predictions and actual results are thought to be due partly to the differences in FE mesh and stress distribution between notched tensile and pre-cracked bend specimens

Connected vertex covers in dense graphs

SCOPUS: cp.kinfo:eu-repo/semantics/publishe

The stackelberg minimum spanning tree game on planar and bounded-treewidth graphs

The Stackelberg Minimum Spanning Tree Game is a two-level combinatorial pricing problem introduced at WADS’07. The game is played on a graph, whose edges are colored either red or blue, and where the red edges have a given fixed cost. The first player chooses an assignment of prices to the blue edges, and the second player then buys the cheapest spanning tree, using any combination of red and blue edges. The goal of the first player is to maximize the total price of purchased blue edges. We study this problem in the cases of planar and bounded-treewidth graphs. We show that the problem is NP-hard on planar graphs but can be solved in polynomial time on graphs of bounded treewidth