Cooperative Research Centre

About: Cooperative Research Centre is a based out in . It is known for research contribution in the topics: Population & Sea ice. The organization has 7633 authors who have published 8607 publications receiving 429721 citations.

Seasonal evolution of upper ocean thermal structure between Tasmania and Antarctica

Abstract: We describe the upper ocean thermal structure between Tasmania and Antarctica based on thirteen repeat temeprature sections occupied between 1991 and 1994. The sections cross three main fronts. The subtropical front is found between Tasmania and the South Tasman Rise in each of the sections. The subantarctic front (SAF) is composed of two parts, which have distinct thermohaline signatures and behave somewhat independently: the northern part, associated with the 6–8°C isotherms, is characterised by large meridional gradients of both temperature and salinity; the southern part is associated with a weaker meridional temperature gradient and negligible salinity gradient between the 3° and 5°C isotherms. The northern part of the SAF is located between 50°S and 51°S in each of the sections, but the position of the southern part of the SAF is more variable with time. A cold core eddy or meander is found north of the SAF throughout the 1993–1994 austral summer. The polar front (PF) is found near 53°S in all sections. Dynamic height is estimated for each of the XBT sections by exploiting the tight correlation in this region between vertically-integrated temperature and dynamic height. Dynamic height decreases relatively smoothly with latitude between 50°S and 53°S, so that the SAF, PF and the water between the two fronts forms a broad belt of eastward flow relative to a deeper level. The difference in dynamic height at the sea surface relative to 2000 m is 1.03 dyn m between 47°S and 60°S and is constant through the 1993–1994 austral summer to within the accuracy of the method (rms error ≈ 0.07 dyn m). The dynamic height expression of the cold core eddy reaches a maximum of 0.23 dyn m in February 1994. The upper 100 m of the water column warms by about 1.6°C between December and March south of 54°S, corresponding to an average warming rate of 95 W m−2. Changes in heat content at other latitudes are dominated by meridional shifts of the fronts, and no clear seasonal trend can be identified.

Wide-swath space-borne SAR using a quad-element array

Abstract: The authors describe an array-based approach to increasing the swath width of space-borne synthetic aperture radar beyond the limit normally imposed by ambiguity. The nulls of a quad-element rectangular array are used to suppress returns from range and azimuth ambiguities, allowing the swath to be increased by a factor of approximately four. A conceptual design is presented, based on ERS-1, that gives a swath extending from 250 km off nadir to over 700 km, with a blind region centred at 500 km. Some adaptive techniques for steering the nulls are discussed.

Physiological responses of a Southern Ocean diatom to complex future ocean conditions

Abstract: Investigation of multiple stressors on a subantarctic diatom reveals the importance of considering individual and interactive effects. Experiments show that temperature and iron enrichment enhance growth and help overcome nutrient depletion.

Induction of different pathogenesis-related cDNAs in grapevine infected with powdery mildew and treated with ethephon

Abstract: Uncinula necator, the causal agent of grapevine powdery mildew, was found to elevate the activity of the pathogenesis-related (PR) proteins, chitinase and β-1,3-glucanase in leaves and berries of a number of susceptible grapevine (Vitis vinifera) cultivars. The increase in hydrolytic activity was directly related to the severity of powdery mildew infection on both leaves and berries but no systemic induction was observed in uninfected tissues. A number of cDNA clones encoding various PR proteins, including chitinases (PR-2), β-1,3-glucanases (PR-3) and thaumatin-like (TL) proteins (PR-5), were isolated and their expression in response to powdery mildew infection examined. PR genes encoding extracellular proteins were most strongly induced in infected leaves, including an acidic class III chitinase (VvChi3), a basic class I glucanase (VvGlub) and a thaumatin-like protein (VvTl2). A basic class I chitinase (VvChi1b) was also detected, but only in severely infected leaves. A similar pattern of PR gene induction was observed in mildew-infected preveraison berries, with the exception of VvChi1b, which was not detected. Chitinase and β-1,3-glucanase enzyme activities were also found to be highly induced in leaves and preveraison berries by ethephon treatment. The pattern of chitinase gene induction by ethephon, however, was markedly different for mildew infection, with no apparent induction of VvChi3 but a marked increase in the transcript level of an acidic class IV chitinase, VvChi4. These results demonstrate that the leaves and preveraison berries of grapevine respond to environmental and stress-related stimuli by the expression of specific PR genes but that the induction of these genes during pathogen invasion does not afford complete protection of these tissues against Uncinula necator. The following abbreviations have been used: Tris: 2-amino-2-(hydroxymethyl)-1,3-propanediol; EDTA: ethylenediaminetetra-acetic acid; PVPP: polyvinylpolypyrrolidone. The GenBank accession numbers for VvChi1b and VvGlub are AF053341 and AF053750, respectively.