Commonwealth Scientific and Industrial Research Organisation

About: Commonwealth Scientific and Industrial Research Organisation is a government organization based out in Canberra, Australian Capital Territory, Australia. It is known for research contribution in the topics: Population & Soil water. The organization has 33765 authors who have published 79910 publications receiving 3356114 citations.

Recent trends and drivers of regional sources and sinks of carbon dioxide

Abstract: . The land and ocean absorb on average just over half of the anthropogenic emissions of carbon dioxide (CO2) every year. These CO2 "sinks" are modulated by climate change and variability. Here we use a suite of nine dynamic global vegetation models (DGVMs) and four ocean biogeochemical general circulation models (OBGCMs) to estimate trends driven by global and regional climate and atmospheric CO2 in land and oceanic CO2 exchanges with the atmosphere over the period 1990–2009, to attribute these trends to underlying processes in the models, and to quantify the uncertainty and level of inter-model agreement. The models were forced with reconstructed climate fields and observed global atmospheric CO2; land use and land cover changes are not included for the DGVMs. Over the period 1990–2009, the DGVMs simulate a mean global land carbon sink of −2.4 ± 0.7 Pg C yr−1 with a small significant trend of −0.06 ± 0.03 Pg C yr−2 (increasing sink). Over the more limited period 1990–2004, the ocean models simulate a mean ocean sink of −2.2 ± 0.2 Pg C yr−1 with a trend in the net C uptake that is indistinguishable from zero (−0.01 ± 0.02 Pg C yr−2). The two ocean models that extended the simulations until 2009 suggest a slightly stronger, but still small, trend of −0.02 ± 0.01 Pg C yr−2. Trends from land and ocean models compare favourably to the land greenness trends from remote sensing, atmospheric inversion results, and the residual land sink required to close the global carbon budget. Trends in the land sink are driven by increasing net primary production (NPP), whose statistically significant trend of 0.22 ± 0.08 Pg C yr−2 exceeds a significant trend in heterotrophic respiration of 0.16 ± 0.05 Pg C yr−2 – primarily as a consequence of widespread CO2 fertilisation of plant production. Most of the land-based trend in simulated net carbon uptake originates from natural ecosystems in the tropics (−0.04 ± 0.01 Pg C yr−2), with almost no trend over the northern land region, where recent warming and reduced rainfall offsets the positive impact of elevated atmospheric CO2 and changes in growing season length on carbon storage. The small uptake trend in the ocean models emerges because climate variability and change, and in particular increasing sea surface temperatures, tend to counter\-act the trend in ocean uptake driven by the increase in atmospheric CO2. Large uncertainty remains in the magnitude and sign of modelled carbon trends in several regions, as well as regarding the influence of land use and land cover changes on regional trends.

Role of Nanoparticles in Photocatalysis

Abstract: The aim of this review paper is to give an overview of the development and implications of nanotechnology in photocatalysis. The topics covered include a detailed look at the unique properties of nanoparticles and their relation to photocatalytic properties. Current applications of and research into the use of nanoparticles as photocatalysts has also been reviewed. Also covered is the utilization of nanoparticles in doped, coupled, capped, sensitized and organic–inorganic nanocomposite semiconductor systems, with an effort to enhance photocatalytic and/or optical properties of commonly used semiconductor materials. The use of nanocrystalline thin films in electrochemically assisted photocatalytic processes has been included. Finally, the use of nanoparticles has made a significant contribution in providing definitive mechanistic information regarding the photocatalytic process.

Transposon Tn21, Flagship of the Floating Genome

Abstract: The transposon Tn21 and a group of closely related transposons (the Tn21 family) are involved in the global dissemination of antibiotic resistance determinants in gram-negative facultative bacteria. The molecular basis for their involvement is carriage by the Tn21 family of a mobile DNA element (the integron) encoding a site-specific system for the acquisition of multiple antibiotic resistance genes. The paradigm example, Tn21, also carries genes for its own transposition and a mercury resistance (mer) operon. We have compiled the entire 19,671-bp sequence of Tn21 and assessed the possible origins and functions of the genes it contains. Our assessment adds molecular detail to previous models of the evolution of Tn21 and is consistent with the insertion of the integron In2 into an ancestral Tn501-like mer transposon. Codon usage analysis indicates distinct host origins for the ancestral mer operon, the integron, and the gene cassette and two insertion sequences which lie within the integron. The sole gene of unknown function in the integron, orf5, resembles a puromycin-modifying enzyme from an antibiotic producing bacterium. A possible seventh gene in the mer operon (merE), perhaps with a role in Hg(II) transport, lies in the junction between the integron and the mer operon. Analysis of the region interrupted by insertion of the integron suggests that the putative transposition regulator, tnpM, is the C-terminal vestige of a tyrosine kinase sensor present in the ancestral mer transposon. The extensive dissemination of the Tn21 family may have resulted from the fortuitous association of a genetic element for accumulating multiple antibiotic resistances (the integron) with one conferring resistance to a toxic metal at a time when clinical, agricultural, and industrial practices were rapidly increasing the exposure to both types of selective agents. The compendium offered here will provide a reference point for ongoing observations of related elements in multiply resistant strains emerging worldwide.

A Framework for Conceptualizing Human Effects on Landscapes and Its Relevance to Management and Research Models

Abstract: The concept of habitat fragmentation is limited in its ability to describe the range of possible landscape configurations created by a variety of disturbances. This limitation is especially problematic in landscapes where human use of the habitat matrix occurs at multiple levels and where habitat modification may be a more important consideration than a simple binary classification of habitat versus nonhabitat. We propose a synthesizing scheme that places intact, variegated, fragmented, and relictual landscape states on a continuum, depending on the degree of habitat destruction. At a second level, the scheme considers the patterns of habitat modification that are imposed on remaining habitats. Management for conservation involves halting and sometimes reversing the trends of habitat destruction and modification. Conservation strategies will differ according to the state of alteration of the landscape, but all strategies include some consideration of the degree of modification of the matrix in determining habitat viability. It is convenient for biologists to assess landscape alteration state in terms of the persistence of large structural elements such as trees. Because animal species use habitats differently, however, they also experience the landscape differently. A landscape considered structurally fragmented by humans may be functionally variegated to other species. Therefore, it is necessary to consider the extent to which the entire landscape, including the matrix, is accessible and utilized by organisms with different spatial scales of resource use.