428 research outputs found

    Pre-clearing vegetation of the coastal lowlands of the Wet Tropics Bioregion, North Queensland

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    A pre-clearing vegetation map and digital coverage at approximately 1:50 000 scale for the coastal lowlands (up to about 200 m elevation) of the Wet Tropics Bioregion, North Queensland is presented. The study area covers about 508 000 ha from Cooktown, 420 km south almost to Townsville (latitude 15° 30’–18° 20’ longitude 144° 50’–146° 40’). Data sources included historical aerial photography, early surveyors’ plans, explorers’ journals, previous vegetation maps, and maps of soils and geology. The pre-clearing mapping was built around the remnant vegetation mapping of Stanton & Stanton (2005), and the vegetation classification of this latter work was adopted. Vegetation units were further classified into regional ecosystems compatible with the standard State-wide system used by Queensland government. The digital coverage is part of the current Queensland Herbarium regional ecosystem coverage (Queensland Herbarium and Wet Tropics Management Authority 2005). Coloured maps (1:100 000 scale) of the pre-clearing vegetation of the Herbert, Tully, Innisfail and Macalister/Daintree subregions are on an accompanying CD-ROM. An evaluation of vegetation loss through clearing on the coastal lowlands of the Wet Tropics revealed several nearextinct vegetation communities and regional ecosystems, and many others that are drastically reduced in area. Even ecosystems occurring on poorly drained lands have suffered a surprisingly high level of loss due to the effectiveness of drainage operations. Grassland ecosystems were found to be widespread on the Herbert and Tully floodplains, but are now close to extinction. The lowlands vegetation of the Wet Tropics that remains today continues to be fragmented and degraded despite the introduction of State-wide broad-scale tree-clearing laws in 1999, and the cessation of broadscale tree-clearing in December 2006

    Tetraethylene Gycol-Based Electrolytes for High Temperature Electrodeposition of Compound Semiconductors

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    We report an investigation of tetraethylene glycol (TEG) solutions of chloride salts (CdCl2 ,TeCl4 ,and HgCl2 ) for electrodeposition of films of CdTe and Hg1.xCdxTe, leading II-VI semiconductors. The high boiling point (314°C), below-room temperature (T) (-6°C) melting point, adequate metal chloride solubilities, and low toxicity of TEG make it a good candidate for electrodeposition at T \u3e 200°C. Such temperatures tend to activate growth of larger crystallites than with aqueous electrolytes at T\u3c 100 °C, as are advantageous in optoelectronic applications. Initial results do, indeed, indicate a dramatic increase in crystallinity with deposition temperature, especially for the CdTe films which are nearly amorphous when grown at room temperature. Hg1.xCdxTe films (x\u3c 0.5) are marginally polycrystalline when grown at room temperature but also improve in crystallinity at higher growth temperatures. There appears to be a strong decrease in film adherence and uniformity as growth temperature increases for both materials probably because the greatly increased carrier concentrations at higher temperatures increase film conductivity which, in turn, supports easy electroplating of protruding loose dendritic and/or columnar crystallites, instead of the monolayer-by monolayer growth of lower conductivity material as occurs at lower temperatures, especially in the higher bandgap/lower conductivity CdTe. The same increase in film conductivity with temperature is responsible for the decrease in the relative photosensitivity of both the CdTe and Hg1.x CdxTe with temperature. At all temperatures, the inferior adherence, uniformity, and photosensitivity as well as the superior crystallinity of Hg1.xCd xTe over that of the CdTe are also explained by its lower bandgap and higher conductivity. On balance, however, the initial results prove the utility of high temperature TEG electrolytes for electrodepositing CdTe and Hg1.xCdxTe films with much better crystallinity than for those grown at lower temperatures, notably in aqueous baths

    Continental materials on Earth by 4.5Ga from Hf-Pb isotope systematics of the Jack Hills zircons, Western Australia

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    [Extract] There is mounting radiogenic isotope evidence for wholesale differentiation of the terrestrial planets within the first few million years of accretion, as seen for example in the formation of feldspathic meteorite suits and samples from the moon and probably mars

    Medical student wellbeing - a consensus statement from Australia and New Zealand

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    Abstract Background Medical student wellbeing – a consensus statement from Australia and New Zealand outlines recommendations for optimising medical student wellbeing within medical schools in our region. Worldwide, medical schools have responsibilities to respond to concerns about student psychological, social and physical wellbeing, but guidance for medical schools is limited. To address this gap, this statement clarifies key concepts and issues related to wellbeing and provides recommendations for educational program design to promote both learning and student wellbeing. The recommendations focus on student selection; learning, teaching and assessment; learning environment; and staff development. Examples of educational initiatives from the evidence-base are provided, emphasising proactive and preventive approaches to student wellbeing. Main recommendations The consensus statement provides specific recommendations for medical schools to consider at all stages of program design and implementation. These are:Design curricula that promote peer support and progressive levels of challenge to students.Employ strategies to promote positive outcomes from stress and to help others in need.Design assessment tasks to foster wellbeing as well as learning.Provide mental health promotion and suicide prevention initiatives.Provide physical health promotion initiatives.Ensure safe and health-promoting cultures for learning in on-campus and clinical settings.Train staff on student wellbeing and how to manage wellbeing concerns. Conclusion A broad integrated approach to improving student wellbeing within medical school programs is recommended. Medical schools should work cooperatively with student and trainee groups, and partner with clinical services and other training bodies to foster safe practices and cultures. Initiatives should aim to assist students to develop adaptive responses to stressful situations so that graduates are prepared for the realities of the workplace. Multi-institutional, longitudinal collaborative research in Australia and New Zealand is needed to close critical gaps in the evidence needed by medical schools in our region

    Electrodeposition of Copper Indium Sulfide Films from Organic Solutions

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    We report on organic solutions ofCuCl 2 ,InClg, and elemental sulfur for electrodepositing CuIn x Sv films. CuInS 2 and CuInSe 2 are promising solar cellmaterials; our work on CuInSg prefaces planned work on plating CuInSe 2 from nonaqueous solvents. Two promising solvent systems are (1) mixed propylcne carbonate and water and (2) mixed ethylene glycol, propionic acid, and water (Engelken et al., 1988). Gray-brown films ofCuInx Sy (nominally GuInS2 ) have been plated from both baths. Major problems include (1) reduction ofCu+2 to Cu and Cu x S by the solvent at high temperatures (T\u3el()0°C), hence depleting Cu+2,(2) poor adherence/uniformity, (3) controlling stoichiometry, and (4) sluggish indium deposition. The paper willdiscuss our routes to solving these problems and present filmdata

    Improved Methods for Electroplating Cadmium Sulfide Thin Films

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    We report improved methods for electroplating cadmium sulfide (CMS) films. Aprevious problem was cracking/flaking of films deposited from organic solutions of elemental sulfur; attempts to improve adhesion via bath additives reduced grain size. Aqueous baths of thiosulfate ions yield cadmium-richness at low T temperatures (T), long deposition times, and/or poor bath stability. Developments in our work to be discussed include (1) plating ofuniform, adherent, and stoichiometric CdS from tetraethylene baths of CdCl 2 and elemental sulfur at T \u3e70° C with minimal cracking/flaking, (2) improved uniformity/ adherence by use of CdL\u3e, and (3) swept voltage methods in aqueous thiosulfate baths to plate stoichiometric (vs. Cd-rich) films near room temperature

    Improved Methods for Electroplating Cadmium Sulfide Thin Films

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    We report improved methods for electroplating cadmium sulfide (CMS) films. Aprevious problem was cracking/flaking of films deposited from organic solutions of elemental sulfur; attempts to improve adhesion via bath additives reduced grain size. Aqueous baths of thiosulfate ions yield cadmium-richness at low T temperatures (T), long deposition times, and/or poor bath stability. Developments in our work to be discussed include (1) plating ofuniform, adherent, and stoichiometric CdS from tetraethylene baths of CdCl 2 and elemental sulfur at T \u3e70° C with minimal cracking/flaking, (2) improved uniformity/ adherence by use of CdL\u3e, and (3) swept voltage methods in aqueous thiosulfate baths to plate stoichiometric (vs. Cd-rich) films near room temperature

    Preparation of Powder Precursors and Evaporation of Photoconductive Indium Sulfide Films

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    We have demonstrated significant photoconductance in indium sulfide thin films prepared by thermal vacuum evaporation ofIn2$3 powders synthesized in-house by chemical precipitation ofInCl3 or In(CH3COO)3, and (NH4)2S or Na2S. The Delta G lambda/Gdark values have been as high as 0.1 in the initial unoptimized films. Excess sulfur (via a mixture of polysulfide and sulfide ions in the synthesis bath) appears to be important in achieving reproducible and large photoconductivities. In2S3 is particularly attractive as a lower toxicity alternative to CdS in optoelectronic applications such as photovoltaic and photoconductive cells
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