Macquarie University

About: Macquarie University is a education organization based out in Sydney, New South Wales, Australia. It is known for research contribution in the topics: Population & Context (language use). The organization has 14075 authors who have published 47673 publications receiving 1416184 citations. The organization is also known as: Macquarie uni.

The influence of temperature-induced phase changes on the kinetics of respiratory and other membrane-associated enzyme systems.

Abstract: Temperature-mediated changes in the kinetics of enzyme catalysed reactions can be due to effects on a number of different parameters. If the change in temperature does not (a) inactivate the enzyme, (b) alter the affinity of the enzyme for the substrate, an activator or an inhibitor or (c) alter the pH function of the reaction components, the velocity of enzyme catalysed reactions increases with increasing temperature. The relationship between the velocity of reaction and temperature can be expressed either as the activation energy (E) or the temperature coefficient (Q10). Both expressions can be derived from the empirical Arrhenius equation relating the velocity of reaction and temperature $$\frac{\alpha \ln k}{\alpha T}=\frac{E}{R{{T}^{2}}}$$ (1) where k is the reaction velocity constant, R the gas constant, T the absolute temperature and E a constant, subsequently called the activation energy (also written as A or μ.). Integration of equation (1) gives $$\ln \frac{{{k}_{2}}}{{{k}_{1}}}=\frac{E}{R}\left( \frac{1}{{{T}_{1}}}-\frac{1}{{{T}_{2}}} \right)$$ (2) from which it can be seen that the value for E can be obtained from the slope of the straight line when logk is plotted against 1/T $$E=2\cdot 303R\times slope$$ $$\therefore E=4\cdot 576\times slope \left( where R=1\cdot 987 cal/mole/{}^{\circ }K \right)$$

Biological responses to the press and pulse of climate trends and extreme events

Abstract: The interaction of gradual climate trends and extreme weather events since the turn of the century has triggered complex and, in some cases, catastrophic ecological responses around the world. We illustrate this using Australian examples within a press–pulse framework. Despite the Australian biota being adapted to high natural climate variability, recent combinations of climatic presses and pulses have led to population collapses, loss of relictual communities and shifts into novel ecosystems. These changes have been sudden and unpredictable, and may represent permanent transitions to new ecosystem states without adaptive management interventions. The press–pulse framework helps illuminate biological responses to climate change, grounds debate about suitable management interventions and highlights possible consequences of (non-) intervention.

Balancing the costs of carbon gain and water transport : testing a new theoretical framework for plant functional ecology

Abstract: A novel framework is presented for the analysis of ecophysiological field measurements and modelling. The hypothesis 'leaves minimise the summed unit costs of transpiration and carboxylation' predicts leaf-internal/ambient CO2 ratios (ci /ca ) and slopes of maximum carboxylation rate (Vcmax ) or leaf nitrogen (Narea ) vs. stomatal conductance. Analysis of data on woody species from contrasting climates (cold-hot, dry-wet) yielded steeper slopes and lower mean ci /ca ratios at the dry or cold sites than at the wet or hot sites. High atmospheric vapour pressure deficit implies low ci /ca in dry climates. High water viscosity (more costly transport) and low photorespiration (less costly photosynthesis) imply low ci /ca in cold climates. Observed site-mean ci /ca shifts are predicted quantitatively for temperature contrasts (by photorespiration plus viscosity effects) and approximately for aridity contrasts. The theory explains the dependency of ci /ca ratios on temperature and vapour pressure deficit, and observed relationships of leaf δ(13) C and Narea to aridity.

Palaeozoic–Mesozoic history of SE Asia

Abstract: SE Asia comprises a collage of Gondwana-derived continental blocks assembled by the closure of multiple Tethyan and back-arc ocean basins now represented by suture zones. Two major biogeographical boundaries, the Late Palaeozoic Gondwana–Cathaysia divide and the Cenozoic-Recent Australia–Asia divide (Wallace Line) are present. Palaeozoic and Mesozoic evolution involved the rifting and separation of three collages of continental terranes from eastern Gondwana and the opening and closure of three successive ocean basins, the PalaeoTethys (Devonian–Triassic), Meso-Tethys (Permian–Cretaceous) and Ceno-Tethys (Late Triassic–Cenozoic). This led to the opening and closing of ocean gateways and provision of shallow-marine and terrestrial land bridges and stepping-stones for biotic migration. The SE Asia core (Sundaland) comprises a western Sibumasu block, an eastern Indochina–East Malaya block, and the Sukhothai Island Arc terrane between. The Jinghong, Nan-Uttaradit and Sra Kaeo sutures represent the Sukhothai closed back-arc basin. The Palaeo-Tethys is represented by the Changning-Menglian, Chiang Mai/Inthanon and Bentong-Raub suture zones. The West Sumatra and West Burma blocks were accreted to the Sundaland core in the Late Permian– Early Triassic. SW Borneo and/or East Java–West Sulawesi are now identified as the missing ‘Argoland’ that separated from NW Australia in the Jurassic and accreted to SE Sundaland in the Cretaceous. SE Asia is located at the zone of convergence between the ESE moving Eurasia Plate, the NE moving Indian and Australian Plates and the ENE moving Philippine Plate (Fig. 1). SE Asia and adjoining regions comprise a complex collage of continental blocks, volcanic arcs, and suture zones that represent the closed remnants of ocean basins (including back-arc basins). The continental blocks of the region were derived from the margin of eastern Gondwana as three successive continental strips or collages of continental blocks that separated in the Devonian, Early Permian and Triassic– Jurassic and which then assembled during the Late Palaeozoic to Cenozoic to form present day East and SE Asia (Metcalfe 2005). Global, regional and local Palaeozoic–Mesozoic tectonic evolution resulted in changes to continent– ocean configurations, dramatic changes in relief both on land and in the seas, and changes in palaeo-ocean currents, including the opening and closing of oceanic gateways. The significant effect on ocean circulation caused by ocean gateway closure/ opening is well documented (e.g. Von der Heydt & Dijkstra 2006, 2008). The changes in continent– ocean, land–sea, relief, and ocean current patterns are fundamental factors leading to both global and regional climate-change and to important changes in biogeographical patterns. Changes in biogeographical barriers and bridges caused by geological evolution and consequent climate-change have also influenced the course of migration, dispersal, isolation and evolution of biota, both globally and in SE Asia. This paper provides an overview of the tectonic framework, and Palaeozoic and Mesozoic geological evolution and palaeogeography of SE Asia and adjacent regions as a background to and to underpin studies of the Indonesian Throughflow Gateway and the distribution and evolution of biota in the region. Geological and tectonic framework of SE Asia and adjacent regions Mainland East and SE Asia comprises a giant ‘jigsaw puzzle’ of continental blocks, volcanic arc terranes, suture zones (remnants/sites of destroyed ocean basins) and accreted continental crust (Figs 2 & 3). From: Hall, R., Cottam, M. A. & Wilson, M. E. J. (eds) The SE Asian Gateway: History and Tectonics of the Australia–Asia Collision. Geological Society, London, Special Publications, 355, 7–35. DOI: 10.1144/SP355.2 0305-8719/11/$15.00 # The Geological Society of London 2011. Continental blocks of SE Asia The principal continental blocks located in mainland SE Asia (Fig. 2) have been identified and established over the last two decades (e.g. Metcalfe 1984, 1986, 1988, 1990, 1996a, 1998, 2002, 2006) and include the South China block, the Indochina–East Malaya block(s), the Sibumasu block, West Burma block and SW Borneo block (Fig. 3). More recently, the West Sumatra block has been established outboard of Sibumasu in SW Sumatra (Barber & Crow 2003, 2009; Barber et al. 2005) and a volcanic arc terrane is now identified, sandwiched between Sibumasu and Indochina–East Malaya (Sone & Metcalfe 2008). A series of smaller continental blocks are identified in eastern (maritime) SE Asia and these were accreted to the mainland core of SE Asia in the Mesozoic– Cenozoic. The continental terranes of SE Asia and adjacent regions are here categorized into six types based on their specific origins, times of rifting and separation from Gondwana, and amalgamation/ accretion to form SE Asia. These are discussed below and the suture zones between them are described separately. Continental blocks derived from Gondwana

Effect of the Solvent Environment on the Spectroscopic Properties and Dynamics of the Lowest Excited States of Carotenoids

Abstract: The spectroscopic properties and dynamics of the lowest excited singlet states of peridinin, fucoxanthin, neoxanthin, uriolide acetate, spheroidene, and spheroidenone in several different solvents have been studied by steady-state absorption and fast-transient optical spectroscopic techniques. Peridinin, fucoxanthin, uriolide acetate, and spheroidenone, which contain carbonyl functional groups in conjugation with the carbon−carbon π-electron system, display broader absorption spectral features and are affected more by the solvent environment than neoxanthin and spheroidene, which do not contain carbonyl functional groups. The possible sources of the spectral broadening are explored by examining the absorption spectra at 77 K in glassy solvents. Also, carotenoids which contain carbonyls have complex transient absorption spectra and show a pronounced dependence of the excited singlet state lifetime on the solvent environment. It is postulated that these effects are related to the presence of an intramolecul...