1,988 research outputs found

    Introduction : The Arctic as an Archive

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    Author's accepted version (postprint). This is an Accepted Manuscript of a book chapter published by transcript Verlag, Bielefeld, in 2019. Available online: https://www.transcript-verlag.de/978-3-8376-4656-6/arctic-archives/This is an Accepted Manuscript of a book chapter published by transcript Verlag, Bielefeld, in 2019.Available online: https://www.transcript-verlag.de/978-3-8376-4656-6/arctic-archives/This introductory articles explains the key concepts and issues for the volume. The Arctic is an important and highly endangered archive of knowledge about natural as well as human history of the Anthropocene. Focusing on the Arctic as an archive means not only to investigate it as a place of human history and memory―of Arctic exploring, conquering, and colonizing―but to take into account also the specific environmental conditions of the circumpolar region: ice and permafrost. These have allowed a huge natural archive to emerge, offering rich sources for natural scientists and historians alike. Notably the articles reviews the debate on the notion of (“natural”) archive, the concept of entropoy and the cultural semantics and historicity of the meaning of concepts like “warm,” “cold,” “freezing,” and “melting. What kind of memory supports do. Media in nature and culture, like snow and ice, earth and stone, but also film, photography and text can all be seen as memory supports. How do they differ in what they remember and what they forget? What kind of events are preserved in ice, for example compared to earth, and what is discarded, and what information is provided when entropy rises?acceptedVersio

    Game play in vocational training and engineering education

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    Educational games may create a new and improved learning culture by drawing advantage of the new knowledge and skills of today’s students obtained from extensive use of interactive game software. This paper presents a design basis and online learning resources taking advantage of game-related features like a high degree of interactivity, attractive graphics, a dynamical virtual universe, and an incentive system to promote prolonged and more advanced use. The educational resources, denoted PIDstop, are targeted towards the engineering domain. Feedback from over 2000 users clearly indicates that PIDstop has a positive learning effect. Training packages for vocational training of Automation Technicians is emphasized in this paper. Such learning resources must have a limited mathematical complexity; hence, the representation should be rather descriptive. Evaluation of learning resources to assess the actual learning effect is important, and a two-step procedure based on formative and summative evaluation is proposed for this purpose

    Amplification of pico-scale DNA mediated by bacterial carrier DNA for small-cell-number transcription factor ChIP-seq

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    BACKGROUND: Chromatin-Immunoprecipitation coupled with deep sequencing (ChIP-seq) is used to map transcription factor occupancy and generate epigenetic profiles genome-wide. The requirement of nano-scale ChIP DNA for generation of sequencing libraries has impeded ChIP-seq on in vivo tissues of low cell numbers. RESULTS: We describe a robust, simple and scalable methodology for ChIP-seq of low-abundant cell populations, verified down to 10,000 cells. By employing non-mammalian genome mapping bacterial carrier DNA during amplification, we reliably amplify down to 50 pg of ChIP DNA from transcription factor (CEBPA) and histone mark (H3K4me3) ChIP. We further demonstrate that genomic profiles are highly resilient to changes in carrier DNA to ChIP DNA ratios. CONCLUSIONS: This represents a significant advance compared to existing technologies, which involve either complex steps of pre-selection for nucleosome-containing chromatin or pre-amplification of precipitated DNA, making them prone to introduce experimental biases. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s12864-014-1195-4) contains supplementary material, which is available to authorized users

    Patterns of use, effectiveness and safety of gadolinium contrast agents: a European prospective cross-sectional multicentre observational study

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    Background: The EU gadolinium-based contrast agents (GBCA) market has changed in recent years due to the European Medicines Agency decision to suspend the marketing authorisation of linear GBCA and the marketing authorisation of new generic macrocyclic GBCA. The study aims to understand the patterns of (GBCA) use, and to study the effectiveness and safety of GBCA in routine practice across Europe. Methods: Prospective, cross-sectional, multicentre, observational study in patients undergoing contrast-enhanced magnetic resonance. Reported usage patterns included indication, referral and examination details. Assessment of effectiveness included changes in radiological diagnosis, diagnostic confidence and image quality. Safety data were collected by spontaneous patient adverse event (AE) reporting. Results: 2118 patients were included from 8 centres across 5 European countries between December 2018 and November 2019. Clariscan, Dotarem (gadoteric acid), Gadovist (gadobutrol) and ProHance (gadoteridol) were utilised in 1513 (71.4%), 356 (16.8%), 237 (11.2%) and 12 (0.6%) patients, respectively. Most were performed in CNS-related indications (46.2%). Mean GBCA doses were 0.10 mmol/kg body weight, except for Gadovist (mean 0.12 mmol/kg). GBCA use increased confidence in diagnosis in 96.2% of examinations and resulted in a change in radiological diagnosis in 73.9% of patients. Image quality was considered excellent or good in 96.1% of patients and across all GBCA. Four patients reported AEs (0.19%), with only 1 (0.05%) considered serious. Conclusions: This European study confirmed that GBCAs are used appropriately in Europe for a wide range of indications. The study demonstrated a significant increase in diagnostic confidence after GBCA use and confirmed the good safety profile of GBCAs, with comparable results for all agents used

    Sandbanks, sandwaves and megaripples on Spitsbergenbanken, Barents Sea

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    Recently acquired multibeam echosounder data from the shallowest part (26–53 m depth) of Spitsbergenbanken in the western Barents Sea reveal a variety of bedforms, including megaripples, sandwaves and sandbanks. The bedforms exhibit varying degrees of superimposition and differ in their age of formation and present depositional regime, being either active or moribund. These are the first observations of co-occurring current induced bedforms in the western Barents Sea and provide evidence of a high energy environment in the study area. The bedforms indicate both sediment erosion and transport and confirm that there is enough sand available in this area to maintain them. Such conditions are not known to be common in the western Barents Sea and reflect the unique oceanographic and benthic environment of Spitsbergenbanken.publishedVersio

    Modeling Vortex Swarming In Daphnia

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    Based on experimental observations in \textit{Daphnia}, we introduce an agent-based model for the motion of single and swarms of animals. Each agent is described by a stochastic equation that also considers the conditions for active biological motion. An environmental potential further reflects local conditions for \textit{Daphnia}, such as attraction to light sources. This model is sufficient to describe the observed cycling behavior of single \textit{Daphnia}. To simulate vortex swarming of many \textit{Daphnia}, i.e. the collective rotation of the swarm in one direction, we extend the model by considering avoidance of collisions. Two different ansatzes to model such a behavior are developed and compared. By means of computer simulations of a multi-agent system we show that local avoidance - as a special form of asymmetric repulsion between animals - leads to the emergence of a vortex swarm. The transition from uncorrelated rotation of single agents to the vortex swarming as a function of the swarm size is investigated. Eventually, some evidence of avoidance behavior in \textit{Daphnia} is provided by comparing experimental and simulation results for two animals.Comment: 24 pages including 11 multi-part figs. Major revisions compared to version 1, new results on transition from uncorrelated rotation to vortex swarming. Extended discussion. For related publications see http://www.sg.ethz.ch/people/scfrank/Publication

    In the Beginning: The First Sources of Light and the Reionization of the Universe

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    The formation of the first stars and quasars marks the transformation of the universe from its smooth initial state to its clumpy current state. In popular cosmological models, the first sources of light began to form at redshift 30 and reionized most of the hydrogen in the universe by redshift 7. Current observations are at the threshold of probing the hydrogen reionization epoch. The study of high-redshift sources is likely to attract major attention in observational and theoretical cosmology over the next decade.Comment: Final revision: 136 pages, including 42 figures; to be published in Physics Reports 2001. References updated, and a few minor corrections made. In this submission, several figures were compressed, resulting in just a slight reduction in quality; a postscript file with the full figures is available at http://www.cita.utoronto.ca/~barkana/review.htm

    The use of synthetic and natural vitamin D sources in pig diets to improve meat quality and vitamin D content

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    This study investigated the effects of synthetic and natural sources of vitamin D biofortification in pig diets on pork vitamin D activity and pork quality. One hundred and twenty pigs (60 male, 60 female) were assigned to one of four dietary treatments for a 55 d feeding period. The dietary treatments were (1)50â€ŻÎŒg vitamin D₃/kg of feed; (2)50â€ŻÎŒg of 25-hydroxvitamin D₃/kg of feed (25-OH-D₃); (3)50â€ŻÎŒg vitamin D₂/kg of feed; (4)50â€ŻÎŒg vitamin D₂-enriched mushrooms/kg of feed (Mushroom D₂). The pigs offered the 25-OH-D₃ diet exhibited the highest (P < 0.001) serum total 25-hydroxyvitamin D concentration and subsequently exhibited the highest (P < 0.05) Longissimus thoracis (LT) total vitamin D activity. Mushroom D2 and 25-OH-D3 supplementation increased pork antioxidant status. The vitamin D₂-enriched mushrooms improved (P < 0.05) pig performance, carcass weight and LT colour. In conclusion, 25-OH-D₃ is the most successful source for increasing pork vitamin D activity, while Mushroom D2 may be a new avenue to improve animal performance and pork quality
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