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Changes in fire regimes since the Last Glacial Maximum: an assessment based on a global synthesis and analysis of charcoal data(2008) Power, M; Marlon, J; Ortiz, N; Bartlein, P; Harrison, Simon; Mayle, F; Ballouche, A; Bradshaw, R; Carcaillet, C; Cordova, C; Mooney, Scott; Moreno, P; Prentice, I; Thonicke, K; Tinner, W; Whitlock, C; Zhang, Yanling; Zhao, Yong; Ali, Amna; Anderson, Richard; Beer, R; Behling, H; Briles, C; Brown, Katherine; Brunelle, A; Bush, M; Camill, P; Chu, G; Clark, J; Colombaroli, D; Connor, Stuart; Daniau, A; Daniels, M; Dodson, John; Doughty, E; Edwards, Meredith; Finsinger, W; Foster, Douglas; Frechette, J; Gaillard, M; Gavin, D; Gobet, E; Haberle, Simon; Hallett, D; Higuera, P; Hope, G; Horn, S; Inoue, J; Kaltenrieder, P; Kennedy, Liz; Kong, Z; Larsen, C; Long, C; Lynch, Jodi; Lynch, E; McGlone, M; Meeks, S; Mensing, S; Meyer, G; Minckley, T; Mohr, J; Nelson, D; New, J; Newnham, R; Noti, R; Oswald, W; Pierce, J; Richard, P; Rowe, C; Goni, M; Shuman, B; Takahara, H; Toney, J; Turney, C; Urrego-Sanchez, D; Umbanhowar, C; Vandergoes, M; Vanniere, B; Vescovi, EJournal ArticleFire activity has varied globally and continuously since the last glacial maximum (LGM) in response to long-term changes in global climate and shorter-term regional changes in climate, vegetation, and human land use. We have synthesized sedimentary charcoal records of biomass burning since the LGM and present global maps showing changes in fire activity for time slices during the past 21,000 years (as differences in charcoal accumulation values compared to pre-industrial). There is strong broad-scale coherence in fire activity after the LGM, but spatial heterogeneity in the signals increases thereafter. In North America, Europe and southern South America, charcoal records indicate less-than-present fire activity during the deglacial period, from 21,000 to ∼11,000 cal yr BP. In contrast, the tropical latitudes of South America and Africa show greater-than-present fire activity from ∼19,000 to ∼17,000 cal yr BP and most sites from Indochina and Australia show greater-than-present fire activity from 16,000 to ∼13,000 cal yr BP. Many sites indicate greater-than-present or near-present activity during the Holocene with the exception of eastern North America and eastern Asia from 8,000 to ∼3,000 cal yr BP, Indonesia and Australia from 11,000 to 4,000 cal yr BP, and southern South America from 6,000 to 3,000 cal yr BP where fire activity was less than present. Regional coherence in the patterns of change in fire activity was evident throughout the post-glacial period. These complex patterns can largely be explained in terms of large-scale climate controls modulated by local changes in vegetation and fuel load.
Wastewater-based monitoring and genomic characterisation of antibiotic-resistant bacteria in the Sydney community(2023) Zillur Rahman, Kazi MohammadThesisCurrent healthcare infection surveillance rarely monitors the distribution of antimicrobial resistance (AMR) in bacteria beyond clinical settings in Australia and overseas. This results in a significant gap in our ability to fully understand and manage the spread of AMR in the general community. This thesis explores whether wastewater-based monitoring could reveal geospatial-temporal and demographic trends of antibiotic-resistant bacteria in the urban area of Greater Sydney, Australia. Untreated wastewater from 25 wastewater treatment plants sampled between 2017 and 2019 consistently contained extended-spectrum β-lactamases-producing Enterobacteriaceae (ESBL-E) isolates, suggesting its endemicity in the community. Carbapenem-resistant Enterobacteriaceae (CRE), vancomycin-resistant enterococci (VRE), and methicillin-resistant Staphylococcus aureus (MRSA) isolates were occasionally detected. Demographic and healthcare infection-related factors correlated with the ESBL-E load, and demographic variables influenced the VRE load. In contrast, the healthcare infection-related factor mainly drove the CRE load. These findings demonstrate the potential of wastewater-based surveillance to understand the factors driving AMR distribution in the community. The subsequent thesis work covers the genomic characterisation of selected ESBL-E and CRE wastewater isolates to reveal their nature, origin, and underlying resistance mechanisms. Phylogenetic analysis showed that Escherichia coli isolates were related to high-risk human-associated pandemic clones and non-human-associated clones. The Klebsiella pneumoniae and K. variicola isolates were related to globally disseminated and emerging human-associated clones, and some were detected for the first time in Australia. Genomic analysis also indicated novel resistance mechanisms against nitrofurantoin in E. coli, and against piperacillin/tazobactam and ticarcillin/clavulanic acid in Klebsiella isolates. The virulence gene content indicated that some E. coli and Klebsiella isolates were likely associated with infections, while the asymptomatic carriage was suggested for other isolates. These results demonstrate a clear potential for wastewater-based surveillance to monitor the emergence and dissemination of resistance in non-clinical isolates, and in particular, isolates from the community and non-human sources. The findings of this study can complement healthcare infection surveillance to inform management strategies to mitigate the emergence and dissemination of AMR and important human pathogens in the general community.