1,673 research outputs found

    The Jahn-Teller active fluoroperovskites ACrF3A\mathrm{CrF_3} A=Na+,K+A=\mathrm{Na^+},\mathrm{K^+}: thermo- and magneto optical correlations as function of the AA-site

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    Chromium (II) fluoroperovskites ACrF3(A=Na+,K+)A\mathrm{CrF_3}(A\mathrm{=Na^+,K^+}) are strongly correlated Jahn-Teller active materials at low temperatures. In this paper, we examine the role that the AA-site ion plays in this family of fluoroperovskites using both experimental methods (XRD, optical absorption spectroscopy and magnetic fields) and DFT simulations. Temperature-dependent optical absorption experiments show that the spin-allowed transitions E2E_2 and E3E_3 only merge completely for AA= Na at 2 K. Field-dependent optical absorption measurements at 2 K show that the oscillating strength of the spin-allowed transitions in NaCrF3\mathrm{NaCrF_3} increases with increasing applied field. Direct magneto-structural correlations which suppress the spin-flip transitions are observed for KCrF3{\rm KCrF_3} below its Ne\'el temperature. In NaCrF3{\rm NaCrF_3} the spin-flip transitions vanish abruptly below 9 K revealing magneto-optical correlations not linked to crystal structure changes. This suggests that as the long range ordering is reduced local JT effects in the individual CrF64−{\rm CrF_6^{4-}} octahedra take control of the observed behavior. Our results show clear deviation from the pattern found for the isoelectronic AxMnF3+xA_x{\rm MnF}_{3+x} system. The size of the AA-site cation is shown to be central in dictating the physical properties and phase transitions in ACrF3A{\rm CrF}_3, opening up the possibility of varying the composition to create novel states of matter with tuneable properties

    In-Seasno Nitrogen Management for Corn Production

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    Water quality impairment related to nitrogen (N) continues to be a concern in Iowa, including the nitrate drinking water standard, USEPA proposed surface water quality nutrient criteria, and Gulf of Mexico hypoxia. Addressing these issues could include strict guidance for N input to corn and resultant N use practices that require very high level of management and risk, with unknown economic consequences. Rate of N application is an important management factor in corn production related to nitrate reaching surface water systems. Rate is also important in regard to economic return. While applying only the needed fertilizer N rate in a given year will not stop nitrate from leaving corn fields, nor necessarily achieve proposed water quality goals, it can result in reduced residual soil nitrate and help lessen corn production\u27s impact on water quality Therefore, it is possible that being able to assess corn N fertilization need differentially each season would improve corn N use efficiency and reduce nitrate susceptible to loss compared to application of an average agronomic rate each year

    Capacity-building barriers to S3 implementation: an empirical framework for catch-up regions

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    In this paper, we investigate the implementation challenge of Smart Specialisation Strategies (S3) in catch-up regional environments, through the lens of capacity building. We analyse capacity building at two levels: micro-level (individual organisations) and meso-level (regional inter-organisational networks). We use empirical evidence from 50 interviews conducted in the period 2015–2017 from two Greek regions dramatically hit by the economic crisis (Crete and Central Macedonia). We argue that in the Cretan and Central Macedonian context, the difficulty of implementing S3 is directly linked with firms’ lack of adsorptive capability to exploit university-generated knowledge, university knowledge that is too abstract for firm’s to easily acquire, as well as to the capability of regional actors to build inter-organisational networking that fits their strategic needs

    Science fiction and economic cycles. A dialogue on technological expectations

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    Was the 2007 - 8 financial and economic crisis brought about by the exhaustion of the current techno - economic paradigm, and will a new paradigm will lead to eventual recovery? Lundvall and Steinmueller respond to Arch ibugi’s Blade Runner economics . Lundvall argues that whilst it is useful to think in terms of techno - economic paradigms to understand the uneven process of technological and social advancement, the main reason for the crisis and the main requirement for a new upswing are both socio - political rather than technological in nature. There is a link between the neoliberal deregulation regime that led to the crisis and ICTs. This regime might actually slow down the formation of a new techno - economic paradigm based around genetic engineering, artificial intelligence and nanotechnology. Steinmueller discusses what role science fiction might play in developing insights about possible futures. Might the present day equivalent for techno - economic paradigm change be mor e about the innovations necessary to rebuild or retrofit our existing technologies than about producing new growth sectors? Taking on board these insights, Archibugi contends that we need to understand why the economic crisis has been so long, so deep and so wide. An innovation - based recovery will need to take advantage of technological opportunities. Pro - active public intervention in science and technology will additionally be required, combined with new social imagination

    Canted antiferromagnetism in high purity NaFeF3\mathrm{NaFeF_3} prepared by a novel wet-chemical synthesis method

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    We report a novel synthesis method for, and structural and magnetic characterization of the fluoroperovskite NaFeF3\mathrm{NaFeF_3}. We have developed a wet-chemical method that allows preparation of large volumes of air-sensitive fluoroperovskites with high purity. NaFeF3\mathrm{NaFeF_3} has a N\'eel temperature (TNT_N) of 90 K and a Weiss constant (θ\theta) of -124 K, corresponding to dominant antiferromagnetic interactions. Below TNT_N, a slight difference is observed between zero-field and field cooled samples, indicating spin-canting and weak ferromagnetism. AC magnetometry confirms that weak ferromagnetism is inherent to NaFeF3\mathrm{NaFeF_3} and not due to impurities. From powder neutron diffraction data, we describe the magnetic structure precisely as a weakly canted G-type (magnetic space group Pn′ma′Pn'ma'). A ferromagnetic component is allowed in Pn′ma′Pn'ma', however, this component may be absent in zero magnetic fields and is too small to be confirmed on the basis of powder neutron diffraction data.Comment: 9 pages, 10 figure

    Innovation and Control: Universities, the Knowledge Economy, and the Authoritarian State in China

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    Like many other education systems in the world, Chinese education has undergone various reforms in order to adapt to the challenges that are perceived to emanate from the knowledge economy. Central to this transformation is the concept of ‘innovation’, which is to guide the country on its path from a production economy to a knowledge economy. Chinese policymakers have been targeting the higher education sector both as a motor for innovation and as a realm to be innovated, and have invested heavily in the sector’s internationalization, above all in the form of international collaboration and student mobility, affecting higher education and academia worldwide. However, a number of structural and political constraints delimit the directions that innovation can take, both within Chinese education in general and within Chinese higher education. The article takes stock of these constraints and assesses the potential for innovation in Chinese higher education in terms of the underlying school system, exam and recruitment policies, the (re-)organization of universities, as well as the universities’ and science system’s performance according to indicators of innovation. The article then identifies four ‘Chinese innovation dilemmas’, that is, educational policies and developments that are to spur innovation but run counter to existing structures and practices of educational, social, and political governance: ideological control versus creativity; state planning versus grassroots innovation; old-boy networks versus anti-corruption; and exam-based student recruitment versus flexible recruitment

    Examining the Connections within the Startup Ecosystem: A Case Study of St. Louis

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    This paper documents the resurgence of entrepreneurial activity in St. Louis by reporting on the collaboration and local learning within the startup community. This activity is happening both between entrepreneurs and between organizations that provide support, such as mentoring and funding, to entrepreneurs. As these connections deepen, the strength of the entrepreneurial ecosystem grows. Another finding from the research is that activity-based events, where entrepreneurs have the chance to use and practice the skills needed to grow their businesses, are most useful. St. Louis provides a multitude of these activities, such as Startup Weekend, 1 Million Cups, Code Until Dawn, StartLouis, and GlobalHack. Some of these are St. Louis specific, but others have nationwide or global operations, providing important implications for other cities

    An exploratory study into everyday problem solving in the design process of medical devices

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    We investigated accounts of how individuals in public and private organisations operating in the medical device industry use different forms of capital (social e.g. networks and cultural e.g. knowledge) to solve design based problems. We define capital as resources embedded in social networks, knowledge or economic wealth (Bourdieu, 1986). Data were collected from interviews and written diaries from individuals involved in the design process of medical devices using interpretative analysis. Inferences made from our analyses suggested that individuals working in organisations who successfully solve problems may do so by using both social and cultural capital and so may be more likely to engage in innovative activity than others. These exploratory findings suggest workers in large organisations may have the capability to use a greater level of in-house social and cultural capital, whereas those in smaller organisations may be more reliant on high levels of social capital in order to ‘tap into’ cultural capital beyond organisational boundaries
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