http://hdl.handle.net/10092/24 2013-05-22T04:07:22Z http://hdl.handle.net/10092/7741 Title: Changing epidemiological trends of legionellosis in New Zealand, 1979-2009 Authors: Graham, F.F.; White, P.S.; Harte, D.J.G.; Kingham, S.P. Abstract: This study evaluated the spatio-temporal variation of Legionella spp. in New Zealand using notification and laboratory surveillance data from 1979 to 2009 and analysed the epidemiological trends. To achieve this we focused on changing incidence rates and occurrence of different species over this time. We also examined whether demographic characteristics such as ethnicity may be related to incidence. The annual incidence rate for laboratory-proven cases was 2.5/100 000 and 1.4/100 000 for notified cases. Incidence was highest in the European population and showed large geographical variations between 21 District Health Boards. An important finding of this study is that the predominant Legionella species causing disease in New Zealand differs from that found in other developed countries, with about 30–50% of cases due to L. longbeachae and a similar percentage due to L. pneumophila for any given year. The environmental risk exposure was identified in 420 (52%) cases, of which 58% were attributed to contact with compost; travel was much less significant as a risk factor (6.5%). This suggests that legionellosis has a distinctive epidemiological pattern in New Zealand. 2012-01-01T00:00:00Z http://hdl.handle.net/10092/7715 Title: Adaptive evolution by recombination is not associated with increased mutation rates in Maize streak virus Authors: Monjane, A.L.; Pande, D.; Lakay, F.; Shepherd, D.N.; van der Walt, E.; Lefeurve, P.; Lett, J-M.; Varsani, A.; Rybicki, E.P.; Martin, D.P. Abstract: Background Single-stranded (ss) DNA viruses in the family Geminiviridae are proving to be very useful in real-time evolution studies. The high mutation rate of geminiviruses and other ssDNA viruses is somewhat mysterious in that their DNA genomes are replicated in host nuclei by high fidelity host polymerases. Although strand specific mutation biases observed in virus species from the geminivirus genus Mastrevirus indicate that the high mutation rates in viruses in this genus may be due to mutational processes that operate specifically on ssDNA, it is currently unknown whether viruses from other genera display similar strand specific mutation biases. Also, geminivirus genomes frequently recombine with one another and an alternative cause of their high mutation rates could be that the recombination process is either directly mutagenic or produces a selective environment in which the survival of mutants is favoured. To investigate whether there is an association between recombination and increased basal mutation rates or increased degrees of selection favoring the survival of mutations, we compared the mutation dynamics of the MSV-MatA and MSV-VW field isolates of Maize streak virus (MSV; Mastrevirus), with both a laboratory constructed MSV recombinant, and MSV recombinants closely resembling MSV-MatA. To determine whether strand specific mutation biases are a general characteristic of geminivirus evolution we compared mutation spectra arising during these MSV experiments with those arising during similar experiments involving the geminivirus Tomato yellow leaf curl virus (Begomovirus genus). Results Although both the genomic distribution of mutations and the occurrence of various convergent mutations at specific genomic sites indicated that either mutation hotspots or selection for adaptive mutations might elevate observed mutation rates in MSV, we found no association between recombination and mutation rates. Importantly, when comparing the mutation spectra of MSV and TYLCV we observed similar strand specific mutation biases arising predominantly from imbalances in the complementary mutations G → T: C → A. Conclusions While our results suggest that recombination does not strongly influence mutation rates in MSV, they indicate that high geminivirus mutation rates are at least partially attributable to increased susceptibility of all geminivirus genomes to oxidative damage while in a single stranded state. 2012-01-01T00:00:00Z http://hdl.handle.net/10092/7379 Title: Single-Pulse Pulsed Laser Polymerization–Electron Paramagnetic Resonance Investigations into the Termination Kinetics of n-Butyl Acrylate Macromonomers Authors: Barth, J.; Buback, M.; Barner-Kowollik, C.; Junkers, T.; Russell, G.T. Abstract: The termination of model mid-chain radicals (MCRs), which mimic radicals that occur in acrylate polymerization over a broad range of reaction conditions, has been studied by singlepulse pulsed-laser polymerization (SP PLP) in conjunction with electron paramagnetic resonance (EPR) spectroscopy. The model radicals were generated by initiator-fragment addition to acrylic macromonomers that were preformed prior to the kinetic experiments, thus enabling separation of termination from the propagation reaction, for these model radicals propagate sparingly, if at all, on the timescale of SP-PLP experiments. Termination rate coefficients of the MCRs were determined in the temperature range 0–60 °C in acetonitrile and butyl propionate solution as well as in bulk macromonomer over 0–100 °C. Termination rate coefficients slightly below those of the corresponding secondary radicals were deduced, demonstrating the relatively high termination activity of this species, even when undergoing MCR-MCR termination. For chain length 10, a reduction by a factor of 6 is observed. Unusually high activation energies were found for the termination rate coefficient in these systems, with 35 kJ mol⁻¹ being determined for bulk macromonomer. Description: The definitive version is available at www3.interscience.wiley.com 2012-01-01T00:00:00Z http://hdl.handle.net/10092/7350 Title: Determining the order of a molecular point group Authors: Williamson, B.E. Abstract: Conventional methods of identifying the point group of a molecule require skills in finding symmetry elements and operations. A useful aid to error checking is an ability to determine the order of a group purely from its label. To this end, Curnow has promulgated a set of simple empirical rules. In this article, Curnow’s rules are substantiated using simple geometric considerations from the basis of point group generators. The proof is provided in a form that will be accessible to undergraduate chemistry students and their teachers 2011-01-01T00:00:00Z