2,445 research outputs found

    Ongoing over-exploitation and delayed responses to environmental change highlight the urgency for action to promote vertebrate recoveries by 2030

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    To safeguard nature, we must understand the drivers of biodiversity loss. Time-delayed biodiversity responses to environmental changes (ecological lags) are often absent from models of biodiversity change, despite their well-documented existence. We quantify how lagged responses to climate and land-use change have influenced mammal and bird populations around the world, while incorporating effects of direct exploitation and conservation interventions. Ecological lag duration varies between drivers, vertebrate classes and body size groupings-e.g. lags linked to climate-change impacts are 13 years for small birds, rising to 40 years for larger species. Past warming and land conversion generally combine to predict population declines; however, such conditions are associated with population increases for small mammals. Positive effects of management (>+4% annually for large mammals) and protected areas (>+6% annually for large birds) on population trends contrast with the negative impact of exploitation (<-7% annually for birds), highlighting the need to promote sustainable use. Model projections suggest a future with winners (e.g. large birds) and losers (e.g. medium-sized birds), with current/recent environmental change substantially influencing abundance trends to 2050. Without urgent action, including effective conservation interventions and promoting sustainable use, ambitious targets to stop declines by 2030 may already be slipping out of reach

    Molybdenum targets for production of 99mTc by a medical cyclotron

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    Introduction Alternative methods for producing the medical imaging isotope 99mTc are actively being developed around the world in anticipation of the imminent shutdown of the National Research Universal (NRU) reactor in Chalk River, Ontario, Canada and the high flux reactor (HFR) in Petten, Holland that together currently produce up to 80 % of the world’s supply through fission. The most promising alternative methods involve accelerators that focus Bremsstrahlung radiation or protons on metallic targets comprised of 100Mo and a supporting material used to conduct heat away during irradiation. As an example, the reaction 100Mo(p,2n)99mTc provides a direct route that can be incorporated into routine production in regional nuclear medicine centers that possess medical cyclotrons for production of other isotopes, such as those used for Positron Emission Tomography (PET). The targets used to produce 99mTc are subject to a number of operational constraints. They must withstand the temperatures generated by the irradiation and be fashioned to accommodate temperature gradients from in situ cooling. The targets must be resilient, which means they cannot disintegrate during irradiation or post processing, because of the radioactive nature of the products. Yet, the targets must be easily post-processed to separate the 99mTc. In addition, the method used to manufacture the targets must not be wasteful of the 100Mo, because of its cost (~$2/mg). Any manufacturing process should be able to function remotely in a shielded space to accommodate the possibility of radioactive recycled target feedstock. There are a number of methods that have been proposed for large-scale target manufacturing including electrophoretic deposition, pressing and sinter-ing, electroplating and carburization [1]. How to develop these methods for routine production is an active business [2,3]. From the industrial perspective, plasma spraying showed promising results initially [4], but the process became very expensive requiring customized equipment in order to reduce losses because of overspray,which also required a large inventory of expen-sive feedstock. In this paper we report the ex-perimental validation of an industrial process for production of targets comprising a Mo layer and a copper support. Materials and methods Target Design Targets have been manufactured for irradiation at 15 MeV. Two targets are shown in FIG. 1: one as-manufactured and another after irradiation; no visible changes were observed following irradiation. The supporting circular copper (C101) disks have diameters of 24 mm and thickness of 1.6 mm. The molybdenum in the center of the target is fully dense with thickness 230 μm determined from SEM cross-sections.Targets have also been manufactured for irradi-ation in a general-purpose target holder designed to be attached to all makes of cyclotrons found in regional nuclear medicine centers. The elliptical targets were designed for high-volume production of 99mTc with 15 MeV protons at currents of 400 µA with 15% collimation [4]. The elliptical shape reduces the heat flux associated with high current sources. The cooling channels on the back of the target are designed to with-stand the high temperature generated during Irradiation. A thermal simulation of expected temperatures during irradiation is shown in FIG. 3. The center of the target is expected to reach 260 oC during irradiation. The elliptical targets were formed from a 27 mm C101 copper plate with width 22 mm and length 55 mm. The molybdenum in the center of the target is fully dense with thickness 60 m de-termined from SEM cross-sections. FIG. 4 shows the molybdenum deposition in the center of the target in a form of an ellipse (38×10 mm). Results and Conclusions Circular targets have been produced and suc-cessfully irradiated for up to 5 h with a proton beam with energy 15 MeV and current 50 µA. (FIG. 1). The targets were resilient. Before irradi-ation the targets were subjected to mechanical shock tests and thermal gradients with no ob-servable effect. After irradiation there was no indication of any degradation. The manufacturing process produced 20 consistently reproducible targets within an hour with a molybdenum loss of less than 2 %. After irradiation the targets were chemically processed and the products characterized by Ge-HP gamma spectrometry. Only Tc isotopes were found. No other contami-nants were identified after processing. The de-tails of the separation and purification are de-scribed elsewhere [5]. Circular targets suitable for low-volume produc-tion of 99mTc have been manufactured and test-ed. The targets have been shown to meet the required operation constraints: the targets are resilient withstanding mechanical shock and irradiation conditions; they are readily produced with minimal losses; and post-processing after irradiation for 5 h has been shown to produce 99mTc. Elliptical targets suitable for high-volume pro-duction of 99mTc with high power cyclotrons have been manufactured (FIG. 4). Like the circular targets, the elliptical targets are readily pro-duced with minimal losses and are able to with-stand mechanical shock and thermal gradients; however, they have yet to be irradiated

    Ring-opening polymerization of <em>rac</em>-lactide and ε-caprolactone using zinc and calcium salicylaldiminato complexes

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    Tridentate Schiff base complexes of zinc and calcium were prepared and tested in the ring-opening polymerization of ε-caprolactone and rac-lactide to generate biodegradable polymeric materials from biocompatible metals. Alteration of the pendant donor arm attached to the imine backbone provides some control over catalyst composition and polymerization activity. Complexes of the formula [ONN]ZnN(SiMe3)2, where [ONN] = 2-(N-donor arm-imine)[4,6-di(tert-butyl)phenoxide], were isolated with ethyldimethylamine, ethylpiperidine, and ethylmorpholine substituents, while disproportionation led to the isolation of [ONN]2Zn complexes with methylpyridine, quinoline, and ethyldiisopropylamine derivatives, two of which were crystallographically characterized. Calcium complexes were more stable and novel [ONN]CaN(SiMe3)2 complexes with ethylpiperidine and ethyldiisopropylamine substituents were reported. Zinc and calcium catalysts coordinated to a single tridentate ligand were effective at initiating the polymerization of ε-caprolactone, but did not control the polymerizations, whereas the bis(ligand) complexes produced no polymer. These catalysts were effective at controlling the polymerization of rac-lactide. Coordinatively saturated complexes inhibit the polymerization, while initiation from either the amido or ligand alkoxide functionalities produces poly(lactic acid) with low polydispersities. </jats:p

    Below the canopy: global trends in forest vertebrate populations and their drivers

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    Global forest assessments use forest area as an indicator of biodiversity status, which may mask below-canopy pressures driving forest biodiversity loss and 'empty forest' syndrome. The status of forest biodiversity is important not only for species conservation but also because species loss can have consequences for forest health and carbon storage. We aimed to develop a global indicator of forest specialist vertebrate populations to improve assessments of forest biodiversity status. Using the Living Planet Index methodology, we developed a weighted composite Forest Specialist Index for the period 1970-2014. We then investigated potential correlates of forest vertebrate population change. We analysed the relationship between the average rate of change of forest vertebrate populations and satellite-derived tree cover trends, as well as other pressures. On average, forest vertebrate populations declined by 53% between 1970 and 2014. We found little evidence of a consistent global effect of tree cover change on forest vertebrate populations, but a significant negative effect of exploitation threat on forest specialists. In conclusion, we found that the forest area is a poor indicator of forest biodiversity status. For forest biodiversity to recover, conservation management needs to be informed by monitoring all threats to vertebrates, including those below the canopy

    Time's up. descriptive epidemiology of multi-morbidity and time spent on health related activity by older Australians: a time use survey.

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    This is a freely-available open access publication. Please cite the published version which is available via the DOI link in this record.Most Western health systems remain single illness orientated despite the growing prevalence of multi-morbidity. Identifying how much time people with multiple chronic conditions spend managing their health will help policy makers and health service providers make decisions about areas of patient need for support. This article presents findings from an Australian study concerning the time spent on health related activity by older adults (aged 50 years and over), most of whom had multiple chronic conditions. A recall questionnaire was developed, piloted, and adjusted. Sampling was undertaken through three bodies; the Lung Foundation Australia (COPD sub-sample), National Diabetes Services Scheme (Diabetes sub-sample) and National Seniors Australia (Seniors sub-sample). Questionnaires were mailed out during 2011 to 10,600 older adults living in Australia. 2540 survey responses were received and analysed. Descriptive analyses were completed to obtain median values for the hours spent on each activity per month. The mean number of chronic conditions was 3.7 in the COPD sub-sample, 3.4 in the Diabetes sub-sample and 2.0 in the NSA sub-sample. The study identified a clear trend of increased time use associated with increased number of chronic conditions. Median monthly time use was 5-16 hours per month overall for our three sub-samples. For respondents in the top decile with five or more chronic conditions the median time use was equivalent to two to three hours per day, and if exercise is included in the calculations, respondents spent from between five and eight hours per day: an amount similar to full-time work. Multi-morbidity imposes considerable time burdens on patients. Ageing is associated with increasing rates of multi-morbidity. Many older adults are facing high demands on their time to manage their health in the face of decreasing energy and mobility. Their time use must be considered in health service delivery and health system reform.National Health and Medical Research Counci

    Ongoing over-exploitation and delayed responses to environmental change highlight the urgency for action to promote vertebrate recoveries by 2030

    Get PDF
    To safeguard nature, we must understand the drivers of biodiversity loss. Time-delayed biodiversity responses to environmental changes (ecological lags) are often absent from models of biodiversity change, despite their well-documented existence. We quantify how lagged responses to climate and land-use change have influenced mammal and bird populations around the world, while incorporating effects of direct exploitation and conservation interventions. Ecological lag duration varies between drivers, vertebrate classes and body size groupings—e.g. lags linked to climate-change impacts are 13 years for small birds, rising to 40 years for larger species. Past warming and land conversion generally combine to predict population declines; however, such conditions are associated with population increases for small mammals. Positive effects of management (>+4% annually for large mammals) and protected areas (>+6% annually for large birds) on population trends contrast with the negative impact of exploitation (<−7% annually for birds), highlighting the need to promote sustainable use. Model projections suggest a future with winners (e.g. large birds) and losers (e.g. medium-sized birds), with current/recent environmental change substantially influencing abundance trends to 2050. Without urgent action, including effective conservation interventions and promoting sustainable use, ambitious targets to stop declines by 2030 may already be slipping out of reach

    High-sensitivity photoacoustic leak testing

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    Skin health in northern Australia

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    Achieving healthy skin requires the prevention of infectious diseases that affect the skin. Prevention activities range from environmental health improvements to address inequities in living situations, through to community-wide treatment programs to reduce transmission and improve skin health. In this paper we discuss the pathogens that cause and conditions that arise when skin is infected, the burden of disease in northern Australia, and some of the current research underway to address this high burden, which predominantly affects remote-living Aboriginal and Torres Strait Islander children and families
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