Taxonomy and phylogeny of Ophiostoma spp. with Sporothrix anamorphs and their generic relationships in the Ophiostomatales

The ophiostomatoid fungi included more than 450 species of ascomycetes specifically adapted for insect dispersal. Many of these species have a significant economic impact as sapstaining fungi or tree pathogens harmful to forestry industries, but some are also as opportunistic human pathogens. DNA based studies in recent years have shown that the majority of these fungi belonged in either the Ophiostomatales or Microascales (Sordariomycetes), with a few Sporothrix spp. grouping in the Microstromatales (Ustilaginomycetes). However, most phylogenetic studies have focussed on restricted numbers of taxa sharing similar morphology. The aim of the studies in this thesis was to reconsider the taxonomy of all the ophiostomatoid fungi at the order and family levels, and the status of genera and species with sporothrix-like anamorphs in the Ophiostomatales and Microstromatales. All available published sequence data were screened for reliable sequences representing as many species as possible, and new data were generated where necessary for ex-type or other isolates. The resulting phylogenies enabled the formal redefinition of the Ophiostomatales and Ophiostomataceae, and the description of two new families, the Graphiaceae (Microascales) and Quambalariaceae (Microstromatales). Problems relating to the delineation of Ophiostoma s.l., Leptographium s.l., and Raffaelea s.l. were exposed and discussed, 18 species complexes were defined in the Ophiostomatales, and four genera were formally redefined: Sporothrix, Graphium, Graphilbum and Knoxdaviesia. Forty six new combinations were made, primarily in Sporothrix, Ophiostoma, Graphilbum and Knoxdaviesia. One nomen novum was erected in Ceratocystis and one new Quambalaria species was described. A comprehensive nomenclator for 596 ophiostomatoid species including references to all descriptions, synonymies and phylogenetic data was also compiled. This study represents the first comprehensive, all-inclusive assessment of the taxonomy and nomenclature of the ophisotomatoid fungi based on phylogenetic relationships and the one fungus one name principles. Finally, the immediate and indiscriminate application of the one fungus one name principles in Ophiostoma s.l. and Leptographium s.l. might result in many unnecessary name changes. Thus, several recommendations have been made to ensure nomenclatural stability in these genera in the immediate future and until more robust phylogenies become available that can refine the delineation of these genera.PhDMicrobiology and Plant PathologyUnrestricte

Magnetic phase transitions in the two-dimensional frustrated quantum antiferromagnet Cs2CuCl4

We report magnetization and specific heat measurements in the 2D frustrated spin-1/2 Heisenberg antiferromagnet Cs2CuCl4 at temperatures down to 0.05 K and high magnetic fields up to 11.5 T applied along a, b and c-axes. The low-field susceptibility chi (T) M/B shows a broad maximum around 2.8 K characteristic of short-range antiferromagnetic correlations and the overall temperature dependence is well described by high temperature series expansion calculations for the partially frustrated triangular lattice with J=4.46 K and J'/J=1/3. At much lower temperatures (< 0.4 K) and in in-plane field (along b and c-axes) several new intermediate-field ordered phases are observed in-between the low-field incommensurate spiral and the high-field saturated ferromagnetic state. The ground state energy extracted from the magnetization curve shows strong zero-point quantum fluctuations in the ground state at low and intermediate fields

DNA sequence comparisons of Ophiostoma spp., including Ophiostoma aurorae sp. nov., associated with pine bark beetles in South Africa

Bark beetles (Coleoptera: Scolytinae) are well-recognized vectors of Ophiostoma species. Three non-native bark beetle species infest various Pinus species in South Africa, and they are known to carry at least 12 different species of ophiostomatoid fungi. Some of these fungi have not been identified to species level. The aim of this study was to determine or confirm the identities of Ophiostoma species associated with bark beetles in South Africa using comparisons of DNA sequence data. Identities of Ophiostoma ips, O. floccosum, O. pluriannulatum, O. quercus and O. stenoceras were confirmed. Ophiostoma abietinum, O. piliferum and Pesotum fragrans are recognised for the first time and the new species, O. aurorae sp. nov., is described from pine-infesting bark beetles in South Africa

Minimal-invasiver Zugang für EVAR: Chirurgisch oder rein interventionell?

Zusammenfassung: Komplikationen kommen sowohl beim rein chirurgischen als auch rein interventionellen (perkutanen) Gefäßzugang nicht selten vor. Sie beinhalten eine nicht zu unterschätzende Morbidität und können sogar zum Tod führen. Wir beschreiben eine Technik, die die Vorteile der chirurgisch offenen mit den rein perkutanen Zugangsmethoden kombiniert: die minimale chirurgische Freilegung des Zugangsgefäßes, gefolgt von einer schnellen und sicheren Punktion mittels einer modifizierten, offenen Seldinger-Technik unter direkter taktiler und visueller Kontrolle. Diese einzigartige Kombination verschiedener Techniken erhöht die Sicherheit des Gefäßzugangs derart, dass lokale Komplikationen fast vollständig vermieden werden können. Ökonomische und sicherheitsrelevante Betrachtungen werden diskutiert, abgerundet durch einen ausgewogenen Überblick über die Vorteile der verschiedenen Technike

Study of neutron response and n-gamma discrimination by charge comparison method for small liquid scintillation detector

The study of the neutron response and n-gamma discrimination for small (18x26x8) mm3 liquid scintillator BC501A (Bicron) detector was carried out by digital charge comparison method. Three ranges of neutron energies were used: uniform distribution from 0.95 MeV to 1.23 MeV, continuous spectra of AmBe source and monoenergetic 16.2 MeV neutrons. The obtained results are compared with those for cylindrical liquid scintillation detector (40 mm diameter, 60 mm length) at the same energies of neutrons. A dramatic fall of the neutron response function at 400 keVee for small detector at 16.2 MeV neutron energy was measured. For (0.95 - 1.23) MeV neutron energy range such fall takes place at 260 keVee. The greater slope of neutron locus at (0.95 - 1.23) MeV neutron energy comparing to 16.2 MeV for both detectors is explained by longer tail of pulse from proton recoils within (0.1-1.23) MeV energy range.Comment: submitted to Nuclear Instruments and Methods in Phys. Res. Sect.

Bose-Einstein Condensation of Magnons in Cs2CuCl4

We report on results of specific heat measurements on single crystals of the frustrated quasi-2D spin-1/2 antiferromagnet Cs_2CuCl_4 (T_N=0.595 K) in external magnetic fields B30 mK. Decreasing B from high fields leads to the closure of the field-induced gap in the magnon spectrum at a critical field B_c = 8.51 T and a magnetic phase transition is clearly seen below B_c. In the vicinity to B_c, the phase transition boundary is well described by the power-law T_c(B)\propto (B_c-B)^{1/\phi} with the measured critical exponent \phi\simeq 1.5. These findings are interpreted as a Bose-Einstein condensation of magnons.Comment: 5 pages, 4 figures, experiment and theor

DNA-based identification of Quambalaria pitereka causing severe leaf blight of Corymbia citriodora in China

Quambalaria spp. include serious plant pathogens, causing leaf and shoot blight of Corymbia and Eucalyptus spp. In this study, a disease resembling Quambalaria leaf blight was observed on young Corymbia citriodora trees in a plantation in the Guangdong Province of China. Comparisons of rDNA sequence data showed that the causal agent of the disease is Q. pitereka. This study provides the first report of Quambalaria leaf blight from China, and it is also the first time that this pathogen has been found on trees outside the native range of Eucalypts

Statistical mechanics of triangulated ribbons

We use computer simulations and scaling arguments to investigate statistical and structural properties of a semiflexible ribbon composed of isosceles triangles. We study two different models, one where the bending energy is calculated from the angles between the normal vectors of adjacent triangles, the second where the edges are viewed as semiflexible polymers so that the bending energy is related to the angles between the tangent vectors of next-nearest neighbor triangles. The first model can be solved exactly whereas the second is more involved. It was recently introduced by Liverpool and Golestanian Phys.Rev.Lett. 80, 405 (1998), Phys.Rev.E 62, 5488 (2000) as a model for double-stranded biopolymers such as DNA. Comparing observables such as the autocorrelation functions of the tangent vectors and the bond-director field, the probability distribution functions of the end-to-end distance, and the mean squared twist we confirm the existence of local twist correlation, but find no indications for other predicted features such as twist-stretch coupling, kinks, or oscillations in the autocorrelation function of the bond-director field.Comment: 10 pages, 13 figures. submitted to PRE, revised versio