8,168 research outputs found

    Imaging Pulsed Laser Deposition oxide growth by in-situ Atomic Force Microscopy

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    To visualize the topography of thin oxide films during growth, thereby enabling to study its growth behavior quasi real-time, we have designed and integrated an atomic force microscope (AFM) in a pulsed laser deposition (PLD) vacuum setup. The AFM scanner and PLD target are integrated in a single support frame, combined with a fast sample transfer method, such that in-situ microscopy can be utilized after subsequent deposition pulses. The in-situ microscope can be operated from room temperature (RT) up to 700^\circC and at (process) pressures ranging from the vacuum base pressure of 106^{-6} mbar up to 1 mbar, typical PLD conditions for the growth of oxide films. The performance of this instrument is demonstrated by resolving unit cell height surface steps and surface topography under typical oxide PLD growth conditions.Comment: 8 pages, 8 figure

    Local Environment of Ferromagnetically Ordered Mn in Epitaxial InMnAs

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    The magnetic properties of the ferromagnetic semiconductor In0.98Mn0.02As were characterized by x-ray absorption spectroscopy and x-ray magnetic circular dichroism. The Mn exhibits an atomic-like L2,3 absorption spectrum that indicates that the 3d states are highly localized. In addition, a large dichroism at the Mn L2,3 edge was observed from 5-300 K at an applied field of 2T. A calculated spectrum assuming atomic Mn2+ yields the best agreement with the experimental InMnAs spectrum. A comparison of the dichroism spectra of MnAs and InMnAs show clear differences suggesting that the ferromagnetism observed in InMnAs is not due to hexagonal MnAs clusters. The temperature dependence of the dichroism indicates the presence of two ferromagnetic species, one with a transition temperature of 30 K and another with a transition temperature in excess of 300 K. The dichroism spectra are consistent with the assignment of the low temperature species to random substitutional Mn and the high temperature species to Mn near-neighbor pairs.Comment: 10 pages, 4 figures, accepted by Applied Physics Letter

    Issues of alcohol safety in the Vologda oblast

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    The article presents the destructive social processes and threats to alcohol safety. The estimation of the basic indicators of production and consumption of alcoholic beverages in the region. The study of the international experience of regulate alcohol consumption, the necessity of toughening of state regulation of turnover of alcoholic products

    The RESET Mindset Model applied on decreasing antibiotic usage in dairy cattle in the Netherlands

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    This article analyses sanctuary initiatives intended to change the situation of ‘irregularised residents’. Through fieldwork, three main activities are identified: assistance for welfare services, alternatives to inaccessible services, and inventing new ways of organising togetherness in the city. The role of activists in the initiatives links to discussions within Critical Human Rights literature, which emphasise the anti-institutionalist origins of rights. Yet, a complex interplay also plays out through co-current resistance against the state’s migration policing and collaboration with city-level state agencies. Understanding this complex process is important to improving knowledge of both the politics of sanctuary and human rights

    What’s in a name? Politicising wastewater reuse in irrigated agriculture

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    Wastewater is increasingly being reused as a solution to water scarcity in agriculture. This article combines a literature review with an ethnographic study of water reuse in Dar es Salaam, Tanzania, to explore the field of wastewater reuse and what it is made to represent. The academic literature largely focuses on the practical challenges of wastewater treatment, while underlying political dynamics that contextualise the planning of, and control over, water flows remain largely unaddressed. Because people seek to take control over water through the manipulation of flows and qualities, wastewater reuse is inherently political. The study of water reuse practices in Dar es Salaam shows how water quality decline is co-produced with processes of urbanisation that cause inequalities in the urban waterscape. Farmers are subject to changes in the physical characteristics and normative understandings of the urban water system, yet do not have the power to reconfigure these to their own ends or challenge the way that their practices are portrayed. This paper shows the importance of politicising wastewater reuse and calls for a more diverse and emancipatory understanding of, and response to, water reuse in agriculture through interdisciplinary research and the collaborative production of knowledge and interventions

    Formation of viable cell fragments by treatment with colchicine

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    Time-lapse cinematography of human fibroblasts revealed that mitotic cells separated into numerous cell fragments containing varying amounts of chromatin and cytoplasm when treated with colchicine. As cell fragments were very loosely attached to the surface of the culture vessel during their formation, they could be easily detached like mitotic cells by gently shaking the vessel and thus separated from normal interphase cells. Fragments obtained by this procedure were able to exclude trypan blue indicating, therefore, an intact cell membrane. When placed into Petri dishes many of them attached to and even spread out on the surface. Five hours later the majority of the attached fragments incorporated [3H]leucine. Time-lapse films showed that fragments were able to extend and retract pseudopodia at least for several hours after their formation. Although the fragments degenerated within a few days, in the present experiments the possibility was not excluded that fragments which had lost only a very small amount of chromatin and cytoplasm survived for longer periods of time. The observations clearly indicate viability of many newly formed fragments

    Is there a reentrant glass in binary mixtures?

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    By employing computer simulations for a model binary mixture, we show that a reentrant glass transition upon adding a second component only occurs if the ratio α\alpha of the short-time mobilities between the glass-forming component and the additive is sufficiently small. For α1\alpha \approx 1, there is no reentrant glass, even if the size asymmetry between the two components is large, in accordance with two-component mode coupling theory. For α1\alpha \ll 1, on the other hand, the reentrant glass is observed and reproduced only by an effective one-component mode coupling theory.Comment: 4 pages, 3 figure
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