1,517 research outputs found

    Information seeking in the Humanities: physicality and digitality

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    This paper presents a brief overview of a research project that is examining the information seeking practices of humanities scholars. The results of this project are being used to develop digital resources to better support these work activities. Initial findings from a recent set of interviews is offered, revealing the importance of physical artefacts in the humanities scholars’ research processes and the limitations of digital resources. Finally, further work that is soon to be undertaken is summarised, and it is hoped that after participation in this workshop these ideas will be refined

    Multi-metallic conduction cooled superconducting radio-frequency cavity with high thermal stability

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    Superconducting radio-frequency cavities are commonly used in modern particle accelerators for applied and fundamental research. Such cavities are typically made of high-purity, bulk Nb and are cooled by a liquid helium bath at a temperature of ~2 K. The size, cost and complexity of operating a particle accelerator with a liquid helium refrigerator makes the current cavity technology not favorable for use in industrial-type accelerators. We developed a multi-metallic 1.495~GHz elliptical cavity conductively cooled by a cryocooler. The cavity has a ~2 μ\mum thick layer of Nb3_3Sn on the inner surface, exposed to the rf field, deposited on a ~3 mm thick bulk Nb shell and a bulk Cu shell, of thickness 5\geqslant 5 mm deposited on the outer surface by electroplating. A bolt-on Cu plate 1.27 cm thick was used to thermally connect the cavity equator to the second stage of a Gifford-McMahon cryocooler with a nominal capacity of 2 W at 4.2 K. The cavity was tested initially in liquid helium at 4.3 K and reached a peak surface magnetic field of ~36 mT with a quality factor of 2×1092\times 10^9. The cavity cooled by the crycooler achieved a peak surface magnetic field of ~29 mT, equivalent to an accelerating gradient of 6.5 MV/m, and it was able to operate in continuous-wave with as high as 5 W dissipation in the cavity for 1 h without any thermal breakdown. This result represents a paradigm shift in the technology of superconducting accelerator cavities

    Ionisation and discharge in cloud-forming atmospheres of brown dwarfs and extrasolar planets

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    Brown dwarfs and giant gas extrasolar planets have cold atmospheres with rich chemical compositions from which mineral cloud particles form. Their properties, like particle sizes and material composition, vary with height, and the mineral cloud particles are charged due to triboelectric processes in such dynamic atmospheres. The dynamics of the atmospheric gas is driven by the irradiating host star and/or by the rotation of the objects that changes during its lifetime. Thermal gas ionisation in these ultra-cool but dense atmospheres allows electrostatic interactions and magnetic coupling of a substantial atmosphere volume. Combined with a strong magnetic field , a chromosphere and aurorae might form as suggested by radio and x-ray observations of brown dwarfs. Non-equilibrium processes like cosmic ray ionisation and discharge processes in clouds will increase the local pool of free electrons in the gas. Cosmic rays and lighting discharges also alter the composition of the local atmospheric gas such that tracer molecules might be identified. Cosmic rays affect the atmosphere through air showers in a certain volume which was modelled with a 3D Monte Carlo radiative transfer code to be able to visualise their spacial extent. Given a certain degree of thermal ionisation of the atmospheric gas, we suggest that electron attachment to charge mineral cloud particles is too inefficient to cause an electrostatic disruption of the cloud particles. Cloud particles will therefore not be destroyed by Coulomb explosion for the local temperature in the collisional dominated brown dwarf and giant gas planet atmospheres. However, the cloud particles are destroyed electrostatically in regions with strong gas ionisation. The potential size of such cloud holes would, however, be too small and might occur too far inside the cloud to mimic the effect of, e.g. magnetic field induced star spots

    Rural-led exchange rate appreciation in China

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    © 2016 Elsevier Inc. The departure of a factor in excess supply in a non-traded rural sector leads to a Rural-led Exchange Rate Real Appreciation (RERA), in a dual economy setup. The RERA highlights for the first time a potential link between intra-national factor movements and real exchange rates. In China, where there is excess labor employed in the production of (largely) non-traded rural goods, we attribute around one third of the recent appreciation of the real exchange rate - defined as the relative price of nontradables - to a RERA effect

    An examination of the physical and the digital qualities of humanities research

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    Traditionally humanities scholars have worked in physical environments and with physical artefacts. Libraries are familiar places, built on cultural traditions over thousands of years, and books are comfortable research companions. Digital tools are a more recent addition to the resources available to a researcher. This paper explores both the physical and the digital qualities of modern humanities research, drawing on existing literature and presenting a study of humanities scholars’ perceptions of the research resources they use. We highlight aspects of the physical and digital that can facilitate or hinder the researcher, focusing on three themes that emerge from the data: the working environment; the experience of finding resources; and the experience of working with documents. Rather than aiming to replace physical texts and libraries by digital surrogates, providers need to recognise the complementary roles they play: digital information environments have the potential to provide improved access and analysis features and the facility to exploit the library from any place, while the physical library and resources provide greater authenticity, trustworthiness and the demand to be in a particular place with important material properties

    Cognitive economy and satisficing in information seeking: A longitudinal study of undergraduate information behavior

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    This article reports on a longitudinal study of information seeking by undergraduate information management students. It describes how they found and used information, and explores their motivation and decision making. We employed a use-in-context approach where students were observed conducting, and were interviewed about, information-seeking tasks carried out during their academic work. We found that participants were reluctant to engage with a complex range of information sources, preferring to use the Internet. The main driver for progress in information seeking was the immediate demands of their work (e.g., assignments). Students used their growing expertise to justify a conservative information strategy, retaining established strategies as far as possible and completing tasks with minimum information-seeking effort. The time cost of using library material limited the uptake of such resources. New methods for discovering and selecting information were adopted only when immediately relevant to the task at hand, and tasks were generally chosen or interpreted in ways that minimized the need to develop new strategies. Students were driven by the demands of the task to use different types of information resources, but remained reluctant to move beyond keyword searches, even when they proved ineffective. They also lacked confidence in evaluating the relative usefulness of resources. Whereas existing literature on satisficing has focused on stopping conditions, this work has highlighted a richer repertoire of satisficing behaviors

    Lightning climatology of exoplanets and brown dwarfs guided by Solar system data

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    We highlight financial support of the European Community under the FP7 by an ERC starting grant number 257431. RAT thanks the Royal Astronomical Society (RAS) and the Physics Trust of the University of St Andrews for supporting his summer placement at the University of St Andrews.Clouds form on extrasolar planets and brown dwarfs where lightning could occur. Lightning is a tracer of atmospheric convection, cloud formation and ionization processes as known from the Solar system, and may be significant for the formation of prebiotic molecules. We study lightning climatology for the different atmospheric environments of Earth, Venus, Jupiter and Saturn. We present lightning distribution maps for Earth, Jupiter and Saturn, and flash densities for these planets and Venus, based on optical and/or radio measurements from the World Wide Lightning Location Network and Sferics Timing and Ranging Network radio networks, the Lightning Imaging Sensor/Optical Transient Detector satellite instruments, the Galileo, Cassini, New Horizons and Venus Express spacecraft. We also present flash densities calculated for several phases of two volcano eruptions, Eyjafjallajökull's (2010) and Mt Redoubt's (2009). We estimate lightning rates for sample, transiting and directly imaged extrasolar planets and brown dwarfs. Based on the large variety of exoplanets, six categories are suggested for which we use the lightning occurrence information from the Solar system. We examine lightning energy distributions for Earth, Jupiter and Saturn. We discuss how strong stellar activity may support lightning activity. We provide a lower limit of the total number of flashes that might occur on transiting planets during their full transit as input for future studies. We find that volcanically very active planets might show the largest lightning flash densities. When applying flash densities of the large Saturnian storm from 2010/11, we find that the exoplanet HD 189733b would produce high lightning occurrence even during its short transit.Publisher PDFPeer reviewe

    A library or just another information resource? A case study of users' mental models of traditional and digital libraries

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    A user's understanding of the libraries they work in, and hence of what they can do in those libraries, is encapsulated in their “mental models” of those libraries. In this article, we present a focused case study of users' mental models of traditional and digital libraries based on observations and interviews with eight participants. It was found that a poor understanding of access restrictions led to risk-averse behavior, whereas a poor understanding of search algorithms and relevance ranking resulted in trial-and-error behavior. This highlights the importance of rich feedback in helping users to construct useful mental models. Although the use of concrete analogies for digital libraries was not widespread, participants used their knowledge of Internet search engines to infer how searching might work in digital libraries. Indeed, most participants did not clearly distinguish between different kinds of digital resource, viewing the electronic library catalogue, abstracting services, digital libraries, and Internet search engines as variants on a theme

    Brain-derived neurotrophic factor association with amygdala response in major depressive disorder

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    Background: Brain-derived neurotrophic factor (BDNF) has an essential role in synaptic plasticity and neurogenesis. BDNF mediates amygdala-dependent learning for both aversive and appetitive emotional memories. The expression of BDNF in limbic regions is posited to contribute the development of depression, and amygdala responsivity is a potential marker of depressive state. Methods: The present study examined the relationship between platelet BDNF levels and amygdala volume and function in major depressive disorder (MDD). Participants were 23 MDD (mean age 38.9 years) and 23 healthy controls (mean age 38.8 years). All participants were recruited from the community. MDD participants were in a current depressive episode of moderate severity and medication-free. Amygdala responses were acquired during a functional MRI task of implicit emotional processing with sad facial expressions. Results: Significant correlation was observed between platelet BDNF levels and left amygdala responses, but no significant correlations were found with right amygdala responses or with amygdala volumes. Limitations: Interactions with neuroprotective as well as neurotoxic metabolites in the kyneurenine pathway were not examined. Conclusions: Relationship between BDNF levels and amygdala responsivity to emotionally salient stimuli in MDD could reflect the importance of BDNF in amygdala-dependent learning with clinical implications for potential pathways for treatment
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