78 research outputs found

    Transient field-resolved reflectometry at 50-100 THz

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    Transient field-resolved spectroscopy enables studies of ultrafast dynamics in molecules, nanostructures, or solids with sub-cycle resolution, but previous work has so far concentrated on extracting the dielectric response at frequencies below 50 THz. Here, we implemented transient field-resolved reflectometry at 50-100 THz(3-6 mu m) with MHz repetition rate employing 800 nm few-cycle excitation pulses that provide sub-10 fs temporal resolution. The capabilities of the technique are demonstrated in studies of ultrafast photorefractive changes in semiconductors Ge and GaAs, where the high frequency range permits to explore the resonance-free Drude response. The extended frequency range in transient field-resolved spectroscopy can further enable studies with so far inaccessible transitions, including intramolecular vibrations in a large range of systems. Published by The Optical Society under the terms of the Creative Commons Attribution 4.0 License

    Community engagement and professionalization: Emerging tensions

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    © 2019 by Emerald Publishing Limited. An increase in community engagement by governments across Australia’s three-tiered federal polity conforms to international trends. It represents a multidimensional institutionalization of participatory democracy designed to involve the public in decision-making. Increasingly, it is a practice which displays the markers of professionalization, including (self-described) professionals, professional associations and a code of ethics. The individuals who design, communicate, and facilitate community engagement are placed in a unique position, whereas most professions claim to serve both their client or employer and a greater public good, community engagement practitioners play these roles while also claiming to serve as “guardians” of democratic processes. Yet the claimed professionalization of community engagement is raising some questions: Is community engagement really a profession – and by what criteria ought this be assessed? What tensions do community engagement practitioners face by “serving multiple masters,” and how do they manage these? More pointedly, how can ethics inform our understanding of community engagement and its professionalization? This chapter examines the case for the practice of community engagement as a profession using Noordegraaf’s (2007) pillars of pure professionalism as a guide. It then explores some practical examples of the tensions practitioners may experience. The chapter concludes by reflecting on the future direction of community engagement given its positioning

    Fear and Exploration in European Starlings (Sturnus vulgaris): A Comparison of Hand-Reared and Wild-Caught Birds

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    The revision of EU legislation will ban the use of wild-caught animals in scientific procedures. This change is partially predicated on the assumption that captive-rearing produces animals with reduced fearfulness. Previously, we have shown that hand-reared starlings (Sturnus vulgaris) indeed exhibit reduced fear of humans compared to wild-caught conspecifics. Here, we asked whether this reduction in fear in hand-reared birds is limited to fear of humans or extends more generally to fear of novel environments and novel objects. Comparing 6–8 month old birds hand-reared in the lab with age-matched birds caught from the wild as fledged juveniles a minimum of 1 month previously, we examined the birds' initial reactions in a novel environment (a small cage) and found that wild-caught starlings were faster to initiate movement compared to the hand-reared birds. We interpret this difference as evidence for greater escape motivation in the wild-caught birds. In contrast, we found no differences between hand-reared and wild-caught birds when tested in novel object tests assumed to measure neophobia and exploratory behaviour. Moreover, we found no correlations between individual bird's responses in the different tests, supporting the idea that these measure different traits (e.g. fear and exploration). In summary, our data show that developmental origin affects one measure of response to novelty in young starlings, indicative of a difference in either fear or coping style in a stressful situation. Our data contribute to a growing literature demonstrating effects of early-life experience on later behaviour in a range of species. However, since we did not find consistent evidence for reduced fearfulness in hand-reared birds, we remain agnostic about the welfare benefits of hand-rearing as a method for sourcing wild birds for behavioural and physiological research

    Deep Convective Microphysics Experiment (DCMEX) coordinated aircraft and ground observations: microphysics, aerosol, and dynamics during cumulonimbus development

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    Cloud feedbacks associated with deep convective anvils remain highly uncertain. In part, this uncertainty arises from a lack of understanding of how microphysical processes influence the cloud radiative effect. In particular, climate models have a poor representation of microphysics processes, thereby encouraging the collection and study of observation data to enable better representation of these processes in models. As such, the Deep Convective Microphysics Experiment (DCMEX) undertook an in situ aircraft and ground-based measurement campaign of New Mexico deep convective clouds during July–August 2022. The campaign coordinated a broad range of instrumentation measuring aerosol, cloud physics, radar, thermodynamics, dynamics, electric fields, and weather. This paper introduces the potential data user to DCMEX observational campaign characteristics, relevant instrument details, and references to more detailed instrument descriptions. Also included is information on the structure and important files in the dataset in order to aid the accessibility of the dataset to new users. Our overview of the campaign cases illustrates the complementary operational observations available and demonstrates the breadth of the campaign cases observed. During the campaign, a wide selection of environmental conditions occurred, ranging from dry, northerly air masses with low wind shear to moist, southerly air masses with high wind shear. This provided a wide range of different convective growth situations. Of 19 flight days, only 2 d lacked the formation of convective cloud. The dataset presented (https://doi.org/10.5285/B1211AD185E24B488D41DD98F957506C; Facility for Airborne Atmospheric Measurements et al., 2024) will help establish a new understanding of processes on the smallest cloud- and aerosol-particle scales and, once combined with operational satellite observations and modelling, can support efforts to reduce the uncertainty of anvil cloud radiative impacts on climate scales

    Diel patterns of fin whale 20 Hz acoustic presence in Eastern Antarctic waters

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    This study presents evidence of diel patterns in fin whale (Balaenoptera physalus) 20 Hz acoustic presence in Eastern Antarctic waters. Passive acoustic recordings were collected at four sites in Eastern Antarctica from 2013 to 2019. A generalized linear model fitted by a generalized estimating equation was used to test the hypothesis that fin whale 20 Hz acoustic presence shows significant variation between light regimes dawn, day, dusk and night. In the Indian sector of Antarctica, at the Prydz and Southern Kerguelen Plateau sites, fin whale acoustic presence was significantly more common during the night and dawn before declining during the day and dusk periods. A different diel pattern was observed in the Pacific sector, at the Dumont d'Urville site: fin whale acoustic presence was significantly more common during the day than dusk and night periods. No diel pattern was identified at the Casey site. The identified diel patterns in the Indian sector of Eastern Antarctica correlate with previously identified diel patterns of the fin whales' prey. We suggest an indirect association between fin whale acoustic presence and foraging, with the animals more likely to produce the 20 Hz pulse during the night when not foraging and less likely to vocalize when foraging during the day

    Focal cortical dysplasia of the temporal lobe with late-onset partial epilepsy : serial quantitative MRI

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    We describe serial studies of focal cortical dysplasia causing temporal lobe seizures and progressive aphasia in a 54-year-old woman. Initially, MRI volumetry of the temporal lobes showed significant left cortical thickening corresponding to an elevated amino-acid uptake in the left temporoparietal and inferior frontal cortex on SPECT using 3-[I-123]iodo-alpha-methyl-L-tyrosine (IMT). After 1 year there was severe shrinkage of the left temporal lobe, possibly the result of recurrent complex partial seizures
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