425 research outputs found

    Evaluating pasture species for less fertile soils in a subtropical aseasonal low rainfall zone

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    Grasses, legumes, saltbushes and herbs were evaluated at 6 sites in southern inland Queensland to identify potential pasture and forage plants for use on marginal cropping soils. The region experiences summer heat waves and severe winter frosts. Emphasis was on perennial plants, and native species were included. Seedlings were transplanted into the unfertilized fields in either summer or autumn to suit the growing season of plants, and watered to ensure estab-lishment. Summer-growing grasses were the most successful group, while cool season-growing perennials mostly failed. Summer legumes were disappointing, with Stylosanthes scabra and Indigofera schimperi performing best. Some lines such as I. schimperi and the Eragrostis hybrid cv. Cochise were assessed as potential weeds owing to low animal acceptance. Native Rhynchosia minima grew well at some sites and deserves more study. Cenchrus ciliaris was always easy to establish and produced the highest yields. Persistence of some Digitaria and Bothriochloa species, Eragrostis curvula and Fingerhuthia africana at specific sites was encouraging, but potential weediness needs careful assessment. Standard species were identified to represent the main forage types, such as Austrostipa scabra for cool season-growing grasses, for incorporation into future trials with new genetic materials. The early field testing protocol used should be considered for use elsewhere, if unreliable rainfall poses a high risk of establishment failure from scarce seed

    Evaluating pasture species for less fertile soils in a subtropical aseasonal low rainfall zone

    Get PDF
    Grasses, legumes, saltbushes and herbs were evaluated at 6 sites in southern inland Queensland to identify potential pasture and forage plants for use on marginal cropping soils. The region experiences summer heat waves and severe winter frosts. Emphasis was on perennial plants, and native species were included. Seedlings were transplanted into the unfertilized fields in either summer or autumn to suit the growing season of plants, and watered to ensure estab-lishment. Summer-growing grasses were the most successful group, while cool season-growing perennials mostly failed. Summer legumes were disappointing, with Stylosanthes scabra and Indigofera schimperi performing best. Some lines such as I. schimperi and the Eragrostis hybrid cv. Cochise were assessed as potential weeds owing to low animal acceptance. Native Rhynchosia minima grew well at some sites and deserves more study. Cenchrus ciliaris was always easy to establish and produced the highest yields. Persistence of some Digitaria and Bothriochloa species, Eragrostis curvula and Fingerhuthia africana at specific sites was encouraging, but potential weediness needs careful assessment. Standard species were identified to represent the main forage types, such as Austrostipa scabra for cool season-growing grasses, for incorporation into future trials with new genetic materials. The early field testing protocol used should be considered for use elsewhere, if unreliable rainfall poses a high risk of establishment failure from scarce seed

    Oscillating carbon nanotori along carbon nanotubes

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    The discovery of carbon nanostructures, such as nanotubes and C₆₀ fullerenes, has given rise to a number of potential nanoscale devices. One such device is the gigahertz oscillator, comprising an inner shell sliding inside an outer shell of a multiwalled carbon nanotube, and which, at least theoretically, generates oscillatory frequencies in the gigahertz range. Following the concept of these gigahertz oscillators and the recent discovery of “fullerene crop circles,” here we propose the notion of a nanotorus-nanotube oscillator comprising a carbon nanotorus which is sucked by the van der Waals force onto the carbon nanotube, and subsequently oscillates along the nanotube axis due to the equal and opposite pulselike forces acting at either end of the nanotube. Assuming a continuum approach, where the interatomic interactions are replaced by uniform atomic surface densities, and assuming that the geometry of the nanotube and nanotorus is such that the nanotorus always remains symmetrically situated around the nanotube, we present the basic mechanics of such a system, including the determination of the suction and acceptance energies, and the frequency of the resulting oscillatory motion. In contrast to the previously studied gigahertz nanoscale oscillators, here the oscillatory frequencies are shown to be in the megahertz range. Our study, although purely theoretical must necessarily precede any experimental implementation of such oscillatory systems.Tamsyn A. Hilder and James M. Hil

    Continuum modelling of gigahertz nano-oscillators

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    Fullerenes and carbon nanotubes are of considerable interest throughout many scientific areas due to their unique and exceptional properties, such as low weight, high strength, flexibility, high thermal conductivity and chemical stability. These nanostructures have many potential applications in nano-devices. One concept that has attracted much attention is the creation of nano-oscillators, which can produce frequencies in the gigahertz range, for applications such as ultra-fast optical filters and nano-antennae. In this paper, we provide the underlying mechanisms of the gigahertz nano-oscillators and we review some recent results derived by the authors using the Lennard-Jones potential together with the continuum approach to mathematically model three different types of nano-oscillators including double-walled carbon nanotube, C60-nanotube and C60-nanotorus oscillators

    Mapping the Planetary Wake in HD 163296 with Kinematics

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    We map the planetary wake associated with the embedded protoplanet creating the CO kink in the disk of HD~163296. We show that the wake can be traced by a series of correlated perturbations in the peak velocity map. The sign change of the perturbations across the disk major axis confirm that the wake induces predominantly radial motion, as predicted by models of planet-disk interaction. These results provide the first direct confirmation of planet wakes generated by Lindblad resonances. Mapping the wake provides a constraint on the disk aspect ratio, which is required to measure the mass of the planet.Comment: 10 Pages, 6 figures. Accepted in ApJ

    Preparing linked population data for research: cohort study of prisoner perinatal health outcomes.

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    ABSTRACTObjectivesThis paper assessed linkage quality and describes the generation of population representative samples of perinatally exposed and non-exposed mothers for cohort analysis and “own-control” analysis from the linked data. ApproachA study of pregnancy outcomes related to pregnancy in prison in New South Wales, Australia, used record linkage to add information about incarceration and serious mental health morbidity (MHM) to birth data. MHM data were oversampled and all available prisoner alias identities were requested for the linkage. Data custodians applied restrictions limiting the control group to a sample of unlinked records and required that year and person age in days be used instead of dates for all events. Linkage was performed by a dedicated state-wide data linkage authority.Multiple-matched identities were counted. Linked data was assessed to quantify duplicated births; excessive births; non-chronological progression of year of birth and to maternal age; concurrent pregnancies; concurrent incarcerations; and conception during incarceration. Exposure status was determined by interrogation of the temporal relationships of all incarceration periods with each to identify prisoner maternities. Maternities with incarceration status for each mother distinguished prisoner mothers from prisoner controls. The subset of prisoner mothers with both types maternity were “own controls”. Standard descriptive statistics are used to provide population prevalence of exposures and compare data quality across study stratified population sub-groups.ResultsLinked records for 3,260 prisoners and 3087 women who had given birth were resolved to 3085 unique person records. Linked person records inconsistent with a singular identity based on maternity factors only were within the predicted limit of the false positive rate set by the linkage authority (<0.5%) for non-prisoners with no mental health morbidity, but were twice as high for women with MHM (RR 2.2; 95%CI 1.9, 2.6) and tenfold higher among prisoners (RR 9.9; 95%CI 8.2, 11.9). The 2,589 prisoners not excluded comprised 558 prisoners (238 “own controls”) pregnant while in prison and 2,031 prisoner controls. The population estimated from study data represents 99.7% of the 404,144 women who actually birthed in NSW, of whom <1% were prisoners (68% with MHM) and 7% had serious mental health morbidity. ConclusionAlthough not set up to test use of alias identities for record linkage, these results suggest that the expected improved linkage sensitivity from including aliases was offset by reduced linkage specificity. The capacity to report results for prisoners against the whole population increased their utility.</jats:p

    Selective foraging behavior of seabirds in small-scale slicks

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    Lieber L, FĂĽchtencordsjĂĽrgen C, Hilder RL, et al. Selective foraging behavior of seabirds in small-scale slicks. Limnology and Oceanography Letters . 2022.Marine predator foraging opportunities are often driven by dynamic physical processes enhancing prey accessibility. Surface slicks are ubiquitous yet ephemeral ocean features where convergent flows accumulate flotsam, concentrating marine organisms and pollutants. Slicks can manifest on the sea surface as meandering lines and seabirds often associate with slicks. Yet, how slicks may influence the fine-scale foraging behavior of seabirds is only coarsely resolved. Here we show that seabirds selectively forage in small-scale slicks. We used aerial drone technology to track surface-foraging terns (Sternidae, 107 tracks) over evolving slicks advected by the mean flow and reshaped by localized turbulence at scales of meters and seconds. Terns were more likely to switch into high-tortuosity foraging behavior when over slicks, with plunge-dive events occurring significantly more often within slicks. As we demonstrate that terns select dynamic slicks for foraging, our approach will also lend itself to interaction studies with pollutants, plumes, and fronts

    Prospects for local co-governance

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    British local authorities and their partners are increasingly developing new ways of working together with local communities. The nature of this co-working, however, is complex, multi-faceted and little understood. This article argues for greater clarity of thinking on the topic, by analysing this co-working as a form of political co-governance, and drawing attention in particular to issues of scale and democracy. Using evidence from a study of 43 local authority areas, 16 authorities are identified where co-governance is practised, following three main types of approach: service-influencing, service-delivering and parish council developing. It is concluded that strengthening political co-governance is essential for a healthy democracy
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