ANU Research Publications

Permanent URI for this collectionhttps://hdl.handle.net/1885/26

The Australian National University's Research Publications collection is an online location for collecting, preserving and disseminating the scholarly output of the University. This service allows members of the University to share their research with the wider community. ANU Open Research accepts journal articles, conference papers, book chapters, working or technical papers and other forms of scholarly communication.

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Now showing 1 - 20 of 123392

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Reimagining strategy and statecraft for the future
(ANU Press, 2025) Prantl, Jochen
Crystal balls are a rare commodity in strategic policymaking. Yet, developing a structured and systematic way of imagining the future is more critical than ever in a strategic and policy environment that is undergoing transformational change.
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The state of the art in plant lipidomics
(2021) Kehelpannala, Cheka; Rupasinghe, Thusitha; Hennessy, Thomas; Bradley, David; Ebert, Berit; Roessner, Ute
Lipids are a group of compounds with diverse structures that perform several important functions in plants. To unravel and better understand their in vivo functions, plant biologists have been using various lipidomic technologies including liquid-chromatography (LC)-mass spectrometry (MS). However, there are still significant challenges in LC-MS based plant lipidomics, which need to be addressed. In this review, we provide an overview of the key developments in LC-MS based lipidomic approaches to detect and identify plant lipids with emphasis on areas that can be further improved. Given that the cellular lipidome is estimated to contain hundreds of thousands of lipids,1,2 many of the lipid structures remain to be discovered. Furthermore, the plant lipidome is considered to be significantly more complex compared to that of mammals. Recent technical developments in mass spectrometry have made the detection of novel lipids possible; hence, approaches that can be used for plant lipid discovery are also discussed.
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Self-esteem, epistemic needs, and responses to social feedback
(2018) Hoplock, Lisa B.; Stinson, Danu Anthony; Marigold, Denise C.; Fisher, Alexandra N.
People with lower self-esteem (LSEs) suffer from poor relational well-being. This may occur, in part, because LSEs’ epistemic needs constrain their ability to benefit from positive social feedback. Consistent with this hypothesis, LSEs felt undeserving of positive social feedback, which undermined their relational well-being (Experiment 1). After receiving positive social feedback, LSEs displayed an equal preference for additional positive and negative feedback, and their willingness to pursue negative feedback predicted poor well-being (Experiment 2). However, LSEs did seize the opportunity to pursue additional positive feedback about a domain of personal strength, and when they did so, their well-being benefited (Experiment 3). These results help explain chronic self-esteem differences in relational well-being and suggest avenues for future well-being interventions.
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Comparison of Care System and Treatment Approaches for Patients with Traumatic Brain Injury in China versus Europe
(2020-07-21) Feng, Junfeng; Van Veen, Ernest; Yang, Chun; Huijben, Jilske A.; Lingsma, Hester F.; Gao, Guoyi; Jiang, Jiyao; Maas, Andrew I.R.; Gruen, Russell
Traumatic brain injury (TBI) poses a huge public health and societal problem worldwide. Uncertainty exists on how care system and treatment approaches for TBI worked in China may differ from those in Europe. Better knowledge on this is important to facilitate interpretation of findings reported by Chinese researchers and to inform opportunities for collaborative studies. We aimed to investigate concordance and variations in TBI care between Chinese and European neurotrauma centers. Investigators from 52 centers in China and 68 in Europe involved in the Collaborative European Neuro Trauma Effectiveness Research in Traumatic Brain Injury (CENTER-TBI) study were invited to complete provider profiling (PP) questionnaires, which covered the main aspects of care system and treatment approaches of TBI care. Participating Chinese and European centers were mainly publicly funded and academic. More centers in China indicated available dedicated neuro-intensive care than those in Europe (98% vs. 60%), and treatment decisions in the ICU were mainly determined by neurosurgeons (58%) in China while in Europe, (neuro)intensivists often took the lead (61%). The ambulance dispatching system was automatic in half of Chinese centers (49%), whereas selective dispatching was more common in European centers (74%). For treatment of refractory intracranial hypertension, a decompressive craniectomy was more frequently regarded as general policy in China compared with in Europe (89% vs. 45%). We observed both concordance and substantial variations with regard to the various aspects of TBI care between Chinese and European centers. These findings are fundamental to guide future research and offer opportunities for collaborative comparative effectiveness research to identify best practices.
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A comparison of classification algorithms within the Classifynder pollen imaging system
(2013) Lagerstrom, Ryan; Arzhaeva, Yulia; Bischof, Leanne; Haberle, Simon; Hopf, Felicitas; Lovell, David
We describe an investigation into how Massey University's Pollen Classifynder can accelerate the understanding of pollen and its role in nature. The Classifynder is an imaging microscopy system that can locate, image and classify slide based pollen samples. Given the laboriousness of purely manual image acquisition and identification it is vital to exploit assistive technologies like the Classifynder to enable acquisition and analysis of pollen samples. It is also vital that we understand the strengths and limitations of automated systems so that they can be used (and improved) to compliment the strengths and weaknesses of human analysts to the greatest extent possible. This article reviews some of our experiences with the Classifynder system and our exploration of alternative classifier models to enhance both accuracy and interpretability. Our experiments in the pollen analysis problem domain have been based on samples from the Australian National University's pollen reference collection (2890 grains, 15 species) and images bundled with the Classifynder system (400 grains, 4 species). These samples have been represented using the Classifynder image feature set. In addition to the Classifynder's native neural network classifier, we have evaluated linear discriminant, support vector machine, decision tree and random forest classifiers on these data with encouraging results. Our hope is that our findings will help enhance the performance of future releases of the Classifynder and other systems for accelerating the acquisition and analysis of pollen samples.
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Land of the disconnected
(Taylor and Francis Ltd., 2017-01-01) Logan, Sarah; Suwamaru, Joseph
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Finite-temperature hydrodynamics for one-dimensional Bose gases
(2016) Bouchoule, I.; Szigeti, S. S.; Davis, M. J.; Kheruntsyan, K. V.
We develop a finite-temperature hydrodynamic approach for a harmonically trapped one-dimensional quasicondensate and apply it to describe the phenomenon of frequency doubling in the breathing-mode oscillations of the quasicondensate momentum distribution. The doubling here refers to the oscillation frequency relative to the oscillations of the real-space density distribution, invoked by a sudden confinement quench. By constructing a nonequilibrium phase diagram that characterizes the regime of frequency doubling and its gradual disappearance, we find that this crossover is governed by the quench strength and the initial temperature rather than by the equilibrium-state crossover from the quasicondensate to the ideal Bose gas regime. The hydrodynamic predictions are supported by the results of numerical simulations based on a finite-temperature c-field approach and extend the utility of the hydrodynamic theory for low-dimensional quantum gases to the description of finite-temperature systems and their dynamics in momentum space.
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Resistance and resilience
(2014-11-01) Bennett, Joanne M.; Nimmo, Dale G.; Clarke, Rohan H.; Thomson, James R.; Cheers, Garry; Horrocks, Gregory F.B.; Hall, Mark; Radford, James Q.; Bennett, Andrew F.; Mac Nally, Ralph
Aim: Climate change is expected to increase the frequency and intensity of extreme climatic events, such as severe droughts and intense rainfall periods. We explored how the avifauna of a highly modified region responded to a 13-year drought (the 'Big Dry'), followed by a two-year period of substantially higher than average rainfall (the 'Big Wet'). Location: Temperate woodlands in north central Victoria, Australia. Methods: We used two spatially extensive, long-term survey programmes, each of which was repeated three times: early and late in the Big Dry, and in the Big Wet. We compared species-specific changes in reporting rates between periods in both programmes to explore the resistance (the ability to persist during drought) and resilience (extent of recovery post-drought) of species to climate extremes. Results: There was a substantial decline in the reporting rates of 42-62% (depending on programme) of species between surveys conducted early and late in the Big Dry. In the Big Wet, there was some recovery, with 21-29% of species increasing substantially. However, more than half of species did not recover and 14-27% of species continued to decline in reporting rate compared with early on in the Big Dry. Species' responses were not strongly related to ecological traits. Species resistance to the drought was inversely related to resilience in the Big Wet for 20-35% of the species, while 76-78% of species with low resistance showed an overall decline across the study period. Conclusions: As declines occurred largely irrespective of ecological traits, this suggests a widespread mechanism is responsible. Species that declined the most during the Big Dry did not necessarily show the greatest recoveries. In already much modified regions, climate extremes such as extended drought will induce on-going changes in the biota.
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Chemodynamical modelling of the galactic bulge and bar
(2017-09-01) Portail, Matthieu; Wegg, Christopher; Gerhard, Ortwin; Ness, Melissa
We present the first self-consistent chemodynamical model fitted to reproduce data for the galactic bulge, bar and inner disc. We extend the Made-to-Measure method to an augmented phase-space including the metallicity of stars, and show its first application to the bar region of the Milky Way. Using data from the ARGOS and APOGEE (DR12) surveys, we adapt the recent dynamical model from Portail et al. to reproduce the observed spatial and kinematic variations as a function of metallicity, thus allowing the detailed study of the 3D density distributions, kinematics and orbital structure of stars in different metallicity bins. We find that metal-rich stars with [Fe/H] ≥ -0.5 are strongly barred and have dynamical properties that are consistent with a common disc origin. Metal-poor stars with [Fe/H] ≤ -0.5 show strong kinematic variations with metallicity, indicating varying contributions from the underlying stellar populations. Outside the central kpc, metal-poor stars are found to have the density and kinematics of a thick disc while in the inner kpc, evidence for an extra concentration of metal-poor stars is found. Finally, the combined orbit distributions of all metallicities in the model naturally reproduce the observed vertex deviations in the bulge. This paper demonstrates the power of Made-to-Measure chemodynamical models, that when extended to other chemical dimensions will be very powerful tools to maximize the information obtained from large spectroscopic surveys such as APOGEE, GALAH and MOONS.
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Stars behind Bars II: A Cosmological Formation Scenario for the Milky Way’s Central Stellar Structure
(2019) Buck, Tobias; Ness, Melissa; Obreja, Aura; Macciò, Andrea V.; Dutton, Aaron A.
The stellar populations in the inner kiloparsecs of the Milky Way (MW) show complex kinematical and chemical structures. The origin and evolution of these structures are still under debate. Here we study the central region of a fully cosmological hydrodynamical simulation of a disk galaxy that reproduces key properties of the inner kiloparsecs of the MW: it has a boxy morphology and shows an overall rotation and dispersion profile in agreement with observations. We use a clustering algorithm on stellar kinematics to identify a number of discrete kinematic components: a high- and low-spin disk, a stellar halo, and two bulge components, one fast-rotating and one slow-rotating. We focus on the two bulge components and show that the slow-rotating one is spherically symmetric while the fast-rotating component shows a boxy/peanut morphology. Although the two bulge components are kinematically discrete populations at present day, they are both mostly formed over similar timescales, from disk material. We find that stellar particles with lower initial birth angular momentum (most likely thick-disk stars) end up in the slow-rotating low-spin bulge, while stars with higher birth angular momentum (most likely thin-disk stars) are found in the high-spin bulge. This has the important consequence that a bulge population with a spheroidal morphology does not necessarily indicate a merger origin. In fact, we do find that only ∼2.3% of the stars in the bulge components are ex situ stars brought in by accreted dwarf galaxies early on. We identify these ex situ stars as the oldest and most metal-poor stars on highly radial orbits with large vertical excursions from the disk.
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SSSpaNG! stellar spectra as sparse, data-driven, non-Gaussian processes
(2021) Feeney, Stephen M.; Wandelt, Benjamin D.; Ness, Melissa K.
Upcoming million-star spectroscopic surveys have the potential to revolutionize our view of the formation and chemical evolution of the Milky Way. Realizing this potential requires automated approaches to optimize estimates of stellar properties, such as chemical element abundances, from the spectra. The sheer volume and quality of the observations strongly motivate that these approaches should be driven by the data. With this in mind, we introduce SSSpaNG: a data-driven non-Gaussian Process model of stellar spectra. We demonstrate the capabilities of SSSpaNG using a sample of APOGEE red clump stars, whose model parameters we infer using Gibbs sampling. By pooling information between stars to infer their covariance, we permit clear identification of the correlations between spectral pixels. Harnessing this correlation structure, we infer the true spectrum of each red clump star, inpainting missing regions and denoising by a factor of at least two for stars with signal-to-noise ratios of ∼20. As we marginalize over the covariance matrix of the spectra, the effective prior on these true spectra is non-Gaussian and sparsifying, favouring typically small but occasionally large excursions from the mean. The high-fidelity inferred spectra produced with our approach will enable improved chemical elemental abundance estimates for individual stars. Our model also allows us to quantify the information gained by observing portions of a star's spectrum, and thereby define the most mutually informative spectral regions. Using 25 windows centred on elemental absorption lines, we demonstrate that the iron-peak and alpha-process elements are particularly mutually informative for these spectra and that the majority of information about a target window is contained in the 10-or-so most informative windows. Such mutual information estimates have the potential to inform models of nucleosynthetic yields and the design of future observations. Our code is made publicly available at https://github.com/sfeeney/ddspectra.
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Galactic Doppelgangers
(2018-02-01) Ness, M.; Rix, H. W.; Hogg, David W.; Casey, A. R.; Holtzman, J.; Fouesneau, M.; Zasowski, G.; Geisler, D.; Shetrone, M.; Minniti, D.; Frinchaboy, Peter M.; Roman-Lopes, Alexandre
We explore to what extent stars within Galactic disk open clusters resemble each other in the high-dimensional space of their photospheric element abundances and contrast this with pairs of field stars. Our analysis is based on abundances for 20 elements, homogeneously derived from APOGEE spectra (with carefully quantified uncertainties of typically 0.03 dex). We consider 90 red giant stars in seven open clusters and find that most stars within a cluster have abundances in most elements that are indistinguishable (in a X2-sense) from those of the other members, as expected for stellar birth siblings. An analogous analysis among pairs of >1000 field stars shows that highly significant abundance differences in the 20 dimensional space can be established for the vast majority of these pairs, and that the APOGEE-based abundance measurements have high discriminating power. However, pairs of field stars whose abundances are indistinguishable even at 0.03 dex precision exist: ∼0.3% of all field star pairs and ∼1.0% of field star pairs at the same (solar) metallicity [Fe/H]=0±0.02. Most of these pairs are presumably not birth siblings from the same cluster, but rather doppelgngers. Our analysis implies that chemical tagging in the strict sense, identifying birth siblings for typical disk stars through their abundance similarity alone, will not work with such data. However, our approach shows that abundances have extremely valuable information for probabilistic chemo-orbital modeling, and combined with velocities, we have identified new cluster members from the field.
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Superphenylphosphines
(2018-01-24) Smith, Jordan N.; Hook, James M.; Lucas, Nigel T.
Tertiary phosphines remain widely utilized in synthesis, most notably as supporting ligands in metal complexes. A series of triarylphosphines bearing one to three hexa-peri-hexabenzocoronene (HBC) substituents has been prepared by an efficient divergent route. These "superphenylphosphines", P{HBC(t-Bu) 5 } n Ph 3-n (n = 1-3), form the palladium complexes PdCl 2 L 2 and Pd 2 Cl 4 L 2 where the isomer distribution in solution is dependent on the number of HBC substituents. The crystalline structures of five complexes all show intramolecular π-stacking between HBC-phosphines to form a supramolecular bidentate-like ligand that distorts the metal coordination geometry. When n = 2 or 3, the additional HBC substituents engage in intermolecular π-stacking to assemble the complexes into continuous ribbons or sheets. The phosphines adopt HBC's characteristics including strong optical absorption, green emission, and redox activity.
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Meat consumption trends and health
(2005) McMichael, Anthony J.; Bambrick, Hilary J.
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Energy levels of terbium(III) in the elpasolite Cs2NaTbF6
(1998-01-01) Berry, A. J.; Morrison, I. D.; Denning, R. G.
Polarized two-photon excitation (TPE) and emission spectra are presented for terbium(III) in the elpasolite Cs2NaTbF6. Almost 90 levels of unambiguous symmetry have been assigned up to 35 000 cm−1 with the aid of a one-electron crystal field Hamiltonian. This represents the most complete and extensive data set so far reported for a lanthanide ion at a cubic site. Large deviations from the predictions of the one-electron crystal field model are observed in the splitting of a number of multiplets. These are discussed in terms of the correlation crystal field (CCF).
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Specialist clinics in remote Australian Aboriginal communities
(2004) Gruen, Russell; Bailie, Ross
People in remote Aboriginal communities in the Northern Territory have greater morbidity and mortality than other Australians, but face considerable barriers when accessing hospital-based specialist services. The Specialist Outreach Service, which began in 1997, was a novel policy initiative to improve access by providing a regular multidisciplinary visiting specialist services to remote communities. It led to two interesting juxtapositions: that of 'state of the art' specialist services alongside under-resourced primary care in remote and relatively traditional Aboriginal communities; and that of attempts to develop an evidence base for the effectiveness of outreach, while meeting the short-term evaluative requirements of policy-makers. In this essay, first we describe the development of the service in the Northern Territory and its initial process evaluation. Through a Cochrane systematic review we then summarise the published research on the effectiveness of specialist outreach in improving access to tertiary and hospital-based care. Finally we describe the findings of an observational population-based study of the use of specialist services and the impact of outreach to three remote communities over 11 years. Specialist outreach improves access to specialist care and may lessen the demand for both outpatient and inpatient hospital care. Specialist outreach is, however, dependent on well-functioning primary care. According to the way in which outreach is conducted and the service is organised, it can either support primary care or it can hinder primary care and, as a result, reduce its own effectiveness.
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Interactions between bitter taste, diet and dysbiosis
(2018) Turner, Alexandria; Veysey, Martin; Keely, Simon; Scarlett, Christopher; Lucock, Mark; Beckett, Emma L.
The type 2 family of taste receptors (T2Rs) detect and respond to bitter tastants. These receptors are expressed throughout the gastrointestinal (GI) tract, with location dependant roles. In the oral cavity, T2Rs are involved in the conscious perception of bitter tastants, while in the lower GI tract they have roles in chemoreception and regulation of GI function. Through these diverse roles, these receptors may be involved in modulating appetite and diet, with consequences for weight regulation and obesity. Interestingly, the concentration of T2Rs in the GI tract is greatest in the large intestine, the organ with the densest colonisation of bacteria. The gut microbiome has been the subject of intense research, as a plethora of roles linking microbiota to human health continue to be uncovered. Of particular interest is the microbial signature associated with obesity. Obesity is a leading health concern, and advances in our understanding of this disease are needed. Diet is a known modifiable factor in the development of obesity. However, diet only partially explains disease risk. Changes in microbial energy harvesting by the microbiota plays a role in obesity, and the composition of these energy harvesting populations may be controlled by taste receptors. This review explores T2Rs as a potential link between obesity and the human GI microbiome.
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Turbulence in the highly restricted dynamics of a closure at second order
(2014) Constantinou, N. C.; Lozano-Durán, A.; Nikolaidis, M. A.; Farrell, B. F.; Ioannou, P. J.; Jiménez, J.
S3T (Stochastic Structural Stability Theory) employs a closure at second order to obtain the dynamics of the statistical mean turbulent state. When S3T is implemented as a coupled set of equations for the streamwise mean and perturbation states, nonlinearity in the dynamics is restricted to interaction between the mean and perturbations. The S3T statistical mean state dynamics can be approximately implemented by similarly restricting the dynamics used in a direct numerical simulation (DNS) of the full Navier-Stokes equations (referred to as the NS system). Although this restricted nonlinear system (referred to as the RNL system) is greatly simplified in its dynamics in comparison to the associated NS, it nevertheless self-sustains a turbulent state in wall-bounded shear flow with structures and dynamics comparable to those observed in turbulence. Moreover, RNL turbulence can be analysed effectively using theoretical methods developed to study the closely related S3T system. In order to better understand RNL turbulence and its relation to NS turbulence, an extensive comparison is made of diagnostics of structure and dynamics in these systems. Although quantitative differences are found, the results show that turbulence in the RNL system closely parallels that in NS and suggest that the S3T/RNL system provides a promising reduced complexity model for studying turbulence in wall-bounded shear flows.
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Photometric monitoring of the doubly imaged quasar UM 673: possible evidence for chromatic microlensing
(2005-10-01) Nakos, Th.; Courbin, F.; Poels, J.; Libbrecht, C.; Magain, P.; Surdej, J.; Manfroid, J.; Burud, I.; Hjorth, J.; Germany, L.; Lidman, C.; Meylan, G.; Pompei, E.; Pritchard, J.; Saviane, I.
We present the results of two-band CCD photometric monitoring of the gravitationally lensed quasar Q 0142-100 (UM 673). The data, obtained at ESO-La Silla with the 1.54 m Danish telescope in the Gunn i-band (October 1998-September 1999) and in the Johnson V-band (October 1998 to December 2001), were analyzed using three different photometric methods. The light-curves obtained with all methods show variations, with a peak-to-peak amplitude of 0.14 mag in V. Although it was not possible to measure the time delay between the two lensed QSO images, the brighter component displays possible evidence for microlensing: it becomes bluer as it gets brighter, as expected under the assumption of differential magnification of a quasar accretion disk.
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Time to antimicrobial therapy in septic shock patients treated with an early goal-directed resuscitation protocol
(2020-10-09) Bulle, Esther B.; Peake, Sandra L.; Finnis, Mark; Bellomo, Rinaldo; Delaney, Anthony; Peake, C.; Cameron, P. A.; Higgins, A. M.; Holdgate, A.; Howe, B. D.; Webb, S. A.R.; Williams, P.; Cooper, D. J.; Cross, A.; Gomersall, C.; Graham, C.; Holdgate, A.; Howe, B. D.; Jacobs, I.; Johanson, S.; Jones, P.; Kruger, P.; McArthur, C.; Myburgh, J.; Nichol, A.; Pettilä, V.; Rajbhandari, D.; Williams, A.; Williams, J.; Williams, P.; Bennett, V.; Board, J.; McCracken, P.; McGloughlin, S.; Nanjayya, V.; Teo, A.; Hill, E.; Jones, P.; O'Brien, E.; Sawtell, F.; Schimanski, K.; Wilson, D.; Bolch, S.; Eastwood, G.; Kerr, F.; Peak, L.; Young, H.; Edington, J.; Mitchell, I.; Rodgers, H.
Objective: Intravenous antimicrobial therapy within 1 h of the diagnosis of septic shock is recommended in international sepsis guidelines. We aimed to evaluate the association between antimicrobial timing and mortality in patients presenting to the ED with septic shock. Methods: Post-hoc analysis of 1587 adult participants enrolled in the Australasian Resuscitation in Sepsis Evaluation (ARISE) multicentre trial of early goal-directed therapy for whom the time of initial antimicrobial therapy was recorded. We compared participants who had initiation of antimicrobials within the first hour (early) or later (delayed) of ED presentation. A propensity score model using inverse probability of treatment weighting was constructed to account for confounding baseline covariates. The primary outcome was 90-day mortality. Results: The median (interquartile range) time to initiating antimicrobials was 69 (39–112) min with 712 (44.9%) participants receiving the first dose within the first hour of ED presentation. Compared with delayed therapy, early administration was associated with increased baseline illness severity score and greater intensity of resuscitation pre-randomisation (fluid volumes, vasopressors, invasive ventilation). All-cause 90-day mortality was also higher; 22.6% versus 15.5%; unadjusted odds ratio (OR) 1.58 (95% confidence interval [CI] 1.16–2.15), P = 0.004. After inverse probability of treatment weighting, the mortality difference was non-significant; OR 1.30 (95% CI 0.95–1.76), P = 0.1. Live discharge rates from ICU (OR 0.81, 95% CI 0.72–0.91; P = 0.80) and hospital (OR 0.93, 95% CI 0.82–1.06; P = 0.29) were also not different between groups. Conclusion: In this post-hoc analysis of the ARISE trial, early antimicrobial therapy was associated with increased illness severity, but 90-day adjusted mortality was not reduced.

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