Development of a pathogenicity testing system for Dothistroma pini infection of Pinus radiata : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Microbiology at Massey University

Dothistroma pini is a fungal pathogen of pine species around the world and can be found in most parts of New Zealand. Infection by D. pini causes a disease commonly known as Dothistroma needle blight. Dothistroma needle blight has a significant financial impact on New Zealand's forestry industry. Although control of infection by D. pini is currently very successful there is a possibility that a new strain introduced from another country could be a lot more damaging and overcome current control measures. In recent years both the incidence and severity of the disease have increased in the northern hemisphere and other parts of the world. A distinctive characteristic of Dothistroma needle blight is the production in the infected needle of a toxic red pigment called dothistromin. Dothistromin is produced as a secondary metabolite by D. pini and has known phytotoxic properties as well as clastogenic and mutagenic properties towards human cells. Purified dothistromin toxin injected into pine needles has been shown to reproduce symptoms similar to those observed during D. pini infection. Because of this production, dothistromin is thought to play an important role in the infection process. Mutants of D. pini that are deficient in dothistromin production have been made recently that will allow this role to be investigated. The aim of this study was to develop a pathogenicity testing system under PC2 containment (required for dothistromin deficient mutant) and to develop microscopy methods required to monitor both epiphytic and endophytic growth of the fungus on the needle D. pini requires high light intensity, continuous leaf moisture and a specific temperature range in order to infect pine needles. Progress was made towards developing a robust pathogenicity testing system. This study has also developed several microscopy techniques for the visualisation of epiphytic growth including a fluorescent microscopy technique. Other bright field and fluorescent staining techniques were investigated with some success. Staining techniques were not successful for the visualisation of endophytic D. pini growth but a green fluorescent protein (sgfp) reporter construct was obtained and two gfp plasmid contracts were developed for the transformation of D. pini for use as biomarkers. Successful introduction of the gfp constructs into D. pini will allow in situ visualisation of endophytic and epiphytic D. pini growth. The work done in this study will be useful for the further investigation into the role of dothistromin toxin, which may lead to new or more efficient methods of controlling D. pini as well as possibly providing information about other polyketide molecules of economic or medical significance

Heterobimetallic Complexes of Rhenium and Zinc: Potential Catalysts for Homogeneous Syngas Conversion

6-(Diphenylphosphino)-2,2′-bipyridine (PNN) coordinates to rhenium carbonyls in both κ^1(P) and κ^2(N,N) modes; in the former, the free bpy moiety readily binds to zinc alkyls and halides. [Re(κ^1(P)-PNN)(CO)_5][OTf] reacts with dialkylzinc reagents to form [Re(κ^1(P)-PNN·ZnR)(CO)_4(μ_(2-)C(O)R)][OTf] (R = Me, Et, Bn), in which an alkyl group has been transferred to a carbonyl carbon and the resulting monoalkyl Zn is bound both to the bpy nitrogens and the acyl oxygen. ZnCl_2 binds readily to the bpy group in Re(κ^1(P)-PNN)(CO)_4Me, and the resulting adduct undergoes facile migratory insertion, assisted by the Lewis acidic pendent Zn, to yield Re(κ^1(P)-PNN·ZnCl)(μ_(2-)Cl)(CO)_3(μ_(2-)C(O)Me), in which one of the chlorides occupies the sixth coordination site on Re. Migratory insertion is inhibited by THF or other ethers that can coordinate to ZnCl_2. Migratory insertion is also observed for Re(κ1(P)-PNN)(CO)_4(CH_2Ph) but not for Re(κ^1(P)-PNN)(CO)_4(CH_2OCH_3); coordination of the methoxy oxygen to Zn appears to block its ability to coordinate to the carbonyl oxygen and facilitate migratory insertion. Intramolecular Lewis acid promoted hydride transfer from [(dmpe)_2PtH][PF_6] to a carbonyl in [Re(κ^1(P)-PNN)(CO)_5][OTf] results in formation of a Re–formyl species; additional hydride transfer leads to a novel Re–Zn-bonded product along with some formal dehyde

A Unified Theory of Matter Genesis: Asymmetric Freeze-In

We propose a unified theory of dark matter (DM) genesis and baryogenesis. It explains the observed link between the DM density and the baryon density, and is fully testable by a combination of collider experiments and precision tests. Our theory utilises the "thermal freeze-in" mechanism of DM production, generating particle anti-particle asymmetries in decays from visible to hidden sectors. Calculable, linked, asymmetries in baryon number and DM number are produced by the feeble interaction mediating between the two sectors, while the out-of-equilibrium condition necessary for baryogenesis is provided by the different temperatures of the visible and hidden sectors. An illustrative model is presented where the visible sector is the MSSM, with the relevant CP violation arising from phases in the gaugino and Higgsino masses, and both asymmetries are generated at temperatures of order 100 GeV. Experimental signals of this mechanism can be spectacular, including: long-lived metastable states late decaying at the LHC; apparent baryon-number or lepton-number violating signatures associated with these highly displaced vertices; EDM signals correlated with the observed decay lifetimes and within reach of planned experiments; and a prediction for the mass of the dark matter particle that is sensitive to the spectrum of the visible sector and the nature of the electroweak phase transition.Comment: LaTeX, 22 pages, 6 figure

Asian Century… on a Knife-edge

Asian Century; Asia's middle class; Urbanisation in Asia; Asian demographic challenges; Democracy and politics in Asia; Asia's global value chains; Economic crime in Asia; Power transition in Asia; China and US rivalry; Inclusive growth in Asi

Moving in the Underground: The Politics of Black Joy in Roller-Skating and Funk Music in Chicago

Skating provides a moment of limited protection from the dangers of being Black in the after-life of slavery. Skating provides a way to temporarily escape the pain of the outside that is depicted above. The pain of a modern post-racial colorblind slave society. A society plagued with hyper-surveillance, mass incarceration, and domestic militarism targeted at Black and Brown bodies. Our joy and pleasure are what sustain us. We turn to jubilee to offer a moment of freedom from the burden of racial capitalism. Subversive Black joy, the joy that allows Black folk to restore, recreate, and reinvent themselves is how we evade the crisis of social death. Black expressive practices like roller-skating, funk music, and dancing are what heal us, helping us get through the alienation and exploitation of slavery and its afterlives. Cultural practices help promote, what Ronaldo Walcott refers to as, glimpses of freedom: where Black folk reimagine themselves and create new worlds resistant to the systemic anti-blackness that marks modern slavery

War and the workers

https://stars.library.ucf.edu/prism/1407/thumbnail.jp

Big Bang Synthesis of Nuclear Dark Matter

We investigate the physics of dark matter models featuring composite bound states carrying a large conserved dark "nucleon" number. The properties of sufficiently large dark nuclei may obey simple scaling laws, and we find that this scaling can determine the number distribution of nuclei resulting from Big Bang Dark Nucleosynthesis. For plausible models of asymmetric dark matter, dark nuclei of large nucleon number, e.g. > 10^8, may be synthesised, with the number distribution taking one of two characteristic forms. If small-nucleon-number fusions are sufficiently fast, the distribution of dark nuclei takes on a logarithmically-peaked, universal form, independent of many details of the initial conditions and small-number interactions. In the case of a substantial bottleneck to nucleosynthesis for small dark nuclei, we find the surprising result that even larger nuclei, with size >> 10^8, are often finally synthesised, again with a simple number distribution. We briefly discuss the constraints arising from the novel dark sector energetics, and the extended set of (often parametrically light) dark sector states that can occur in complete models of nuclear dark matter. The physics of the coherent enhancement of direct detection signals, the nature of the accompanying dark-sector form factors, and the possible modifications to astrophysical processes are discussed in detail in a companion paper.Comment: 27 pages, 5 figures, v3; minor additional comments - matches published versio

An Underappreciated Radiation Hazard from High Voltage Electrodes in Vacuum

The use of high voltage (HV) electrodes in vacuum is commonplace in physics laboratories. In such systems, it has long been known that electron emission from an HV cathode can lead to bremsstrahlung X-rays; indeed, this is the basic principle behind the operation of standard X-ray sources. However, in laboratory setups where X-ray production is not the goal and no electron source is deliberately introduced, field-emitted electrons accelerated by HV can produce X-rays as an unintended hazardous byproduct. Both the level of hazard and the safe operating regimes for HV vacuum electrode systems are not widely appreciated, at least in university laboratories. A reinforced awareness of the radiation hazards associated with vacuum HV setups would be beneficial. We present a case study of a HV vacuum electrode device operated in a university atomic physics laboratory. We describe the characterisation of the observed X-ray radiation, its relation to the observed leakage current in the device, the steps taken to contain and mitigate the radiation hazard, and suggest safety guidelines.Comment: Submitted to Health Physic