6,318 research outputs found

    Pyrmont-Ultimo Precinct (PUP) Scale Organics Management Scoping Study

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    This report, the “Pyrmont Ultimo Precinct (PUP) Scale Organics Management Scoping Study” has been prepared by the Institute for Sustainable Futures (ISF), University of Technology Sydney (UTS). The research, conducted by ISF and funded through a collaboration between Sydney Water Corporation (SWC) and the NSW Environment Protection Authority (EPA), has investigated at a high level, a suite of innovative organic waste management options that could potentially be piloted in Pyrmont-Ultimo, currently the densest urban area in Australia. The Pyrmont-Ultimo precinct (PUP), encompassing Pyrmont, Ultimo and the newly developed Central Park, has been specifically chosen due to the significant potential in the area, existing network of sustainability practitioners (i.e. Smart Locale1) and ISF’s/UTS’s direct involvement in research in food waste management

    Compact Brillouin devices through hybrid integration on Silicon

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    A range of unique capabilities in optical and microwave signal processing have been demonstrated using stimulated Brillouin scattering. The desire to harness Brillouin scattering in mass manufacturable integrated circuits has led to a focus on silicon-based material platforms. Remarkable progress in silicon-based Brillouin waveguides has been made, but results have been hindered by nonlinear losses present at telecommunications wavelengths. Here, we report a new approach to surpass this issue through the integration of a high Brillouin gain material, As2S3, onto a silicon chip. We fabricated a compact spiral device, within a silicon circuit, achieving an order of magnitude improvement in Brillouin amplification. To establish the flexibility of this approach, we fabricated a ring resonator with free spectral range precisely matched to the Brillouin shift, enabling the first demonstration of Brillouin lasing in a silicon integrated circuit. Combining active photonic components with the SBS devices shown here will enable the creation of compact, mass manufacturable optical circuits with enhanced functionality

    An Overview of the Dwarf Galaxy Survey

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    The Dwarf Galaxy Survey (DGS) program is studying low-metallicity galaxies using 230 hr of far-infrared (FIR) and submillimetre (submm) photometric and spectroscopic observations of the Herschel Space Observatory and draws from this a rich database of a wide range of wavelengths tracing the dust, gas and stars. This sample of 50 galaxies includes the largest metallicity range achievable in the local Universe including the lowest metallicity (Z) galaxies, 1/50 Z_⊙, and spans four orders of magnitude in star formation rates. The survey is designed to get a handle on the physics of the interstellar medium (ISM) of low metallicity dwarf galaxies, especially their dust and gas properties and the ISM heating and cooling processes. The DGS produces PACS and SPIRE maps of low-metallicity galaxies observed at 70, 100, 160, 250, 350, and 500 μm with the highest sensitivity achievable to date in the FIR and submm. The FIR fine-structure lines, [CII] 158 μm, [OI] 63 μm, [OI] 145 μm, [OIII] 88 μm, [NIII] 57 μm, and [NII] 122 and 205 μm have also been observed with the aim of studying the gas cooling in the neutral and ionized phases. The SPIRE FTS observations include many CO lines (J = 4–3 to J = 13–12), [NII] 205 μm, and [CI] lines at 370 and 609 μm. This paper describes the sample selection and global properties of the galaxies and the observing strategy as well as the vast ancillary database available to complement the Herschel observations. The scientific potential of the full DGS survey is described with some example results included

    Effect of low-Raman window position on correlated photon-pair generation in a chalcogenide Ge11.5As24Se64.5 nanowire

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    We investigated correlated photon-pair generation via spontaneous four-wave mixing in an integrated chalcogenideGe11.5As24Se64.5photonicnanowire. The coincidence to accidental ratio, a key measurement for the quality of correlated photon-pair sources, was measured to be only 0.4 when the photon pairs were generated at 1.9 THz detuning from the pump frequency due to high spontaneous Raman noise in this regime. However, the existence of a characteristic low-Raman window at around 5.1 THz in this material's Raman spectrum and dispersion engineering of the nanowire allowed us to generate photon pairs with a coincidence to accidental ratio of 4.5, more than 10 times higher than the 1.9 THz case. Through comparing the results with those achieved in chalcogenide As2S3waveguides which also exhibit a low Raman-window but at a larger detuning of 7.4 THz, we find that the position of the characteristic low-Raman window plays an important role on reducing spontaneous Raman noise because the phonon population is higher at smaller detuning. Therefore the ultimate solution for Raman noise reduction in Ge11.5As24Se64.5 is to generate photon pairs outside the Raman gain band at more than 10 THz detuning

    Dielectric response of a polar fluid trapped in a spherical nanocavity

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    We present extensive Molecular Dynamics simulation results for the structure, static and dynamical response of a droplet of 1000 soft spheres carrying extended dipoles and confined to spherical cavities of radii R=2.5R=2.5, 3, and 4 nm embedded in a dielectric continuum of permittivity ϵ1\epsilon' \geq 1. The polarisation of the external medium by the charge distribution inside the cavity is accounted for by appropriate image charges. We focus on the influence of the external permittivity ϵ\epsilon' on the static and dynamic properties of the confined fluid. The density profile and local orientational order parameter of the dipoles turn out to be remarkably insensitive to ϵ\epsilon'. Permittivity profiles ϵ(r)\epsilon(r) inside the spherical cavity are calculated from a generalised Kirkwood formula. These profiles oscillate in phase with the density profiles and go to a ``bulk'' value ϵb\epsilon_b away from the confining surface; ϵb\epsilon_b is only weakly dependent on ϵ\epsilon', except for ϵ=1\epsilon' = 1 (vacuum), and is strongly reduced compared to the permittivity of a uniform (bulk) fluid under comparable thermodynamic conditions. The dynamic relaxation of the total dipole moment of the sample is found to be strongly dependent on ϵ\epsilon', and to exhibit oscillatory behaviour when ϵ=1\epsilon'=1; the relaxation is an order of magnitude faster than in the bulk. The complex frequency-dependent permittivity ϵ(ω)\epsilon(\omega) is sensitive to ϵ\epsilon' at low frequencies, and the zero frequency limit ϵ(ω=0)\epsilon(\omega=0) is systematically lower than the ``bulk'' value ϵb\epsilon_b of the static primitivity.Comment: 12 pages including 17 figure

    Measuring Urban Green Space in Australia

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    The Hort Innovation Green Cities project “Measuring Australia’s Green Space Asset” (MUGS) undertook a global review of urban green space (UGS) measurement research and engaged with Australian stakeholders to gauge current practice. The overall aim of the project was to foster best-practice UGS planning and management by juxtaposing the scientific state of the art with the contextualised needs expressed by potential Australian end users. The synthesis of findings informed a ‘blueprint’ which sketches the contours of a possible nationally consistent UGS decision-support framework. The framework is illustrated with a worked example from Australia (rapid assessment of urban green space assets using satellite imagery)

    Equilibrium solvation in quadrupolar solvents

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    We present a microscopic theory of equilibrium solvation in solvents with zero dipole moment and non-zero quadrupole moment (quadrupolar solvents). The theory is formulated in terms of autocorrelation functions of the quadrupolar polarization (structure factors). It can be therefore applied to an arbitrary dense quadrupolar solvent for which the structure factors are defined. We formulate a simple analytical perturbation treatment for the structure factors. The solute is described by coordinates, radii, and partial charges of constituent atoms. The theory is tested on Monte Carlo simulations of solvation in model quadrupolar solvents. It is also applied to the calculation of the activation barrier of electron transfer reactions in a cleft-shaped donor-acceptor complex dissolved in benzene with the structure factors of quadrupolar polarization obtained from Molecular Dynamics simulations.Comment: Submitted to J. Chem. Phys., 20 pages and 13 figure

    Detecting microRNA activity from gene expression data

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    <p>Abstract</p> <p>Background</p> <p>MicroRNAs (miRNAs) are non-coding RNAs that regulate gene expression by binding to the messenger RNA (mRNA) of protein coding genes. They control gene expression by either inhibiting translation or inducing mRNA degradation. A number of computational techniques have been developed to identify the targets of miRNAs. In this study we used predicted miRNA-gene interactions to analyse mRNA gene expression microarray data to predict miRNAs associated with particular diseases or conditions.</p> <p>Results</p> <p>Here we combine correspondence analysis, between group analysis and co-inertia analysis (CIA) to determine which miRNAs are associated with differences in gene expression levels in microarray data sets. Using a database of miRNA target predictions from TargetScan, TargetScanS, PicTar4way PicTar5way, and miRanda and combining these data with gene expression levels from sets of microarrays, this method produces a ranked list of miRNAs associated with a specified split in samples. We applied this to three different microarray datasets, a papillary thyroid carcinoma dataset, an in-house dataset of lipopolysaccharide treated mouse macrophages, and a multi-tissue dataset. In each case we were able to identified miRNAs of biological importance.</p> <p>Conclusions</p> <p>We describe a technique to integrate gene expression data and miRNA target predictions from multiple sources.</p
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