515 research outputs found

    Motility of the reticulum and rumen of sheep given juice-extracted pasture

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    1. Sheep were fed on different diets of juice-extracted herbage to determine what effect juice-extraction had on reticulo-rumen motility. 2. The frequency of A and B sequences of contraction of the reticulo-rumen were recorded during eating, rumination and inactivity for continuous periods of 24–72 h by using integrated electromyograms obtained from electrodes implanted in the musculature of the reticulum and cranial dorsal rumen. 3. Animals were fed on herbage in which approximately 200 g/kg dry matter had been removed in juice extracted from ryegrass (Lolium perenne), white clover (Trifolium repens), mixed ryegrass–white clover and lucerne (Medicago saliva). 4. Over all the frequency of A sequences of contraction did not differ in animals fed on pressed herbage or the unpressed material from which it was derived, although it was slower during rumination on some of the pressed material. In contrast, the frequency of B sequences was higher on the pressed material. The frequencies of contraction of A and B sequences in animals fed on pressed herbage was related to the activity of the animals in the order eating > rumination > inactivity. 5. Changes in reticulo-rumen motility due to juice extraction were small and the frequencies of A and B sequences of contraction in sheep fed on pressed herbage were in the range encountered in ruminants consuming more conventional foods

    Data mining in bioinformatics using Weka

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    The Weka machine learning workbench provides a general purpose environment for automatic classification, regression, clustering and feature selection-common data mining problems in bioinformatics research. It contains an extensive collection of machine learning algorithms and data exploration and the experimental comparison of different machine learning techniques on the same problem. Weka can process data given in the form of a single relational table. Its main objectives are to (a) assist users in extracting useful information from data and (b) enable them to easily identify a suitable algorithm for generating an accurate predictive model from it

    A global scale geospatially located landslide dam dataset

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    Landslide dams are a common hazard reported in mountainous areas around the world, where the dams block the normal flow of the river and can cause catastrophic flooding downstream when the temporary dam subsequently fails. Most of the research that couples landslide dams and fluvial systems have been concentrated on a site-specific scale and thus little is known about where these hazards are clustered and how they connect to climate and geology. A detailed and comprehensive dataset of landslide dams is not currently available at the global scale, since most global landslide dam datasets contain very little precise spatial information, which makes it harder to explore and to analyze the impacts on floods by modelling over larger scales. To narrow this data gap, we are developing a new global landslide dam dataset, recording: spatial coordinates, time information, dam materials, geomorphic characteristics of catchments, landslides, landslide dams and impounded lakes, and hydrographic characteristics of subsequent flood events and their consequent damage. This has been collated from bibliographic works in a number of languages. In the process of building the database we have encountered several obstacles including language barriers, indistinct naming standards, vague and patchy spatial information, and the diversity of data access in different countries. So far, we have data from over 700 individual events that have been synthesized into the same data format with consistent units and spatial references. The spatial distribution of landslide dam shows hazard hot spot areas concentrated around mountainous areas. The number of landslide dams reported increases exponentially during the past 1000 years, with the highest peak in the last 20 years. This increase is most likely due to better records in more recent years. Some extreme large-scale events, including earthquakes, floods, typhoons and volcanic eruptions have contributed to other peaks in the record. Initial analysis of the data will be used to explore distribution differences of dimension data, such as height, length and volume, of landslide dams that are induced by different triggers, to explore the triggers effect on landslide dam formation. The summary information of the dataset and the characteristic analysis result will be presented with a comparison to existing landslide dam datasets. A spatial distribution map of landslide dams and hazard hot spot areas will also be presented. This extensive global landslide dam dataset will allow researchers to understand the spatial distribution, geomorphic characteristics of landslide dams, and the connections among the dimensions of landslide sources, landslide dams, impounded lakes and upstream catchments. We will continue to develop this current landslide dam dataset and welcome feedback and additional datasets to supplement the database. Upon completion, the dataset will be made open access for wider research purposes and collaborations

    Using Artifacts as Triggers for Participatory Analysis

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    Based on a study of a three-day workshop between users and developers, we show how artifacts like computer prototypes can be used to trigger productive discussions. We demonstrate how clashes between contextualized artifacts and the practitioners' (users) conceptions and experiences of their work practices trigger new understandings of current practice as well as possible futures. In this way, artifacts support the work of participatory analysis as well as participatory design

    ApplBuilder: An Object-Oriented Application Generator Supporting Rapid Prototyping

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    This paper describes an object-oriented application generator, APPLBUILDER, currently being developed in the Mjølner BETA programming environment. APPLBUILDER supports several rapid prototyping styles as well as final development of BETA applications. User interface objects such as dialogs, menus, and windows are designed using direct manipulation graphical editors. Actions behind buttons and menu items are programmed as ''scripts'' in textual editors activated from within a graphical editor. The editors reflect changes in the code directly in an underlying Abstract Syntax Tree (AST) thus saving compilation time. Moreover, generated applications are modularized so that editing, for instance the script for a button, only requires re-compilation of the script itself. An advantage of APPLBUILDER compared to other user-interface design tools such as HyperCard is that APPLBUILDER's scripts are embedded in a general purpose programming language making it possible to avoid calls to external routines written in another language. In addition, APPLBUILDER's ability to work with ASTs instead of textual code skeletons supports reverse engineering

    OPEN-ENDED INTERACTION IN COOPERATIVE PROTOTYPING: A Video-Based Analysis

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    Cooperative Prototyping can be characterized as the use and development of prototypes as catalysts during discussions between designers and potential users - the overall intention being one of mutual learning. On the one hand, the designers learn more about the work practices of the users in ways that are tied concretely to some current version of the prototype. On the other hand, the users learn more about the potential for change in their work practice, whether computer-based or otherwise. This paper presents the results of a field study of the cooperative prototyping process. The study is based on a fine-grained video-based analysis of a single prototyping session, and focuses on the effects of an open-ended style of interaction between users and designers around a prototype. An analysis of focus shifts, initiative and storytelling during the session is brought to bear on the question of whether and how cooperative prototyping can be successful with users who are reluctant to \u27play in the future.\u27 The paper also discusses issues in applying video analysis to system design

    Observations of High Definition Symmetric Quasi‐Periodic Scintillations in the Mid‐Latitude Ionosphere With LOFAR

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    We present broadband ionospheric scintillation observations of highly defined symmetric quasi‐periodic scintillations (QPS: Maruyama, 1991, https://doi.org/10.1029/91rs00357) caused by plasma structures in the mid‐latitude ionosphere using the LOw Frequency ARray (LOFAR: van Haarlem et al., 2013, https://doi.org/10.1051/0004‐6361/201220873). Two case studies are shown, one from 15 December 2016, and one from 30 January 2018, in which well‐defined main signal fades are observed to be bounded by secondary diffraction fringing. The ionospheric plasma structures effectively behave as a Fresnel obstacle, in which steep plasma gradients at the periphery result in a series of decreasing intensity interference fringes, while the center of the structures largely block the incoming radio signal altogether. In particular, the broadband observing capabilities of LOFAR permit us to see considerable frequency dependent behavior in the QPSs which, to our knowledge, is a new result. We extract some of the clearest examples of scintillation arcs reported in an ionospheric context, from delay‐Doppler spectral analysis of these two events. These arcs permit the extraction of propagation velocities for the plasma structures causing the QPSs ranging from 50 to 00 m s−1, depending on the assumed altitude. The spacing between the individual plasma structures ranges between 5 and 20 km. The periodicities of the main signal fades in each event and, in the case of the 2018 data, co‐temporal ionosonde data, suggest the propagation of the plasma structures causing the QPSs are in the E‐region. Each of the two events is accurately reproduced using a thin screen phase model. Individual signal fades and enhancements were modeled using small variations in total electron content (TEC) amplitudes of order 1 mTECu, demonstrating the sensitivity of LOFAR to very small fluctuations in ionospheric plasma density. To our knowledge these results are among the most detailed observations and modeling of QPSs in the literature

    Observations of High Definition Symmetric Quasi‐Periodic Scintillations in the Mid‐Latitude Ionosphere With LOFAR

    Get PDF
    We present broadband ionospheric scintillation observations of highly defined symmetric quasi‐periodic scintillations (QPS: Maruyama, 1991, https://doi.org/10.1029/91rs00357) caused by plasma structures in the mid‐latitude ionosphere using the LOw Frequency ARray (LOFAR: van Haarlem et al., 2013, https://doi.org/10.1051/0004‐6361/201220873). Two case studies are shown, one from 15 December 2016, and one from 30 January 2018, in which well‐defined main signal fades are observed to be bounded by secondary diffraction fringing. The ionospheric plasma structures effectively behave as a Fresnel obstacle, in which steep plasma gradients at the periphery result in a series of decreasing intensity interference fringes, while the center of the structures largely block the incoming radio signal altogether. In particular, the broadband observing capabilities of LOFAR permit us to see considerable frequency dependent behavior in the QPSs which, to our knowledge, is a new result. We extract some of the clearest examples of scintillation arcs reported in an ionospheric context, from delay‐Doppler spectral analysis of these two events. These arcs permit the extraction of propagation velocities for the plasma structures causing the QPSs ranging from 50 to 00 m s−1, depending on the assumed altitude. The spacing between the individual plasma structures ranges between 5 and 20 km. The periodicities of the main signal fades in each event and, in the case of the 2018 data, co‐temporal ionosonde data, suggest the propagation of the plasma structures causing the QPSs are in the E‐region. Each of the two events is accurately reproduced using a thin screen phase model. Individual signal fades and enhancements were modeled using small variations in total electron content (TEC) amplitudes of order 1 mTECu, demonstrating the sensitivity of LOFAR to very small fluctuations in ionospheric plasma density. To our knowledge these results are among the most detailed observations and modeling of QPSs in the literature

    Spatiotemporal expression of regulatory kinases directs the transition from mitosis to cellular morphogenesis in Drosophila

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    Embryogenesis depends on a tightly regulated balance between mitosis, differentiation, and morphogenesis. Understanding how the embryo uses a relatively small number of proteins to transition between growth and morphogenesis is a central question of developmental biology, but the mechanisms controlling mitosis and differentiation are considered to be fundamentally distinct. Here we show the mitotic kinase Polo, which regulates all steps of mitosis in Drosophila, also directs cellular morphogenesis after cell cycle exit. In mitotic cells, the Aurora kinases activate Polo to control a cytoskeletal regulatory module that directs cytokinesis. We show that in the post-mitotic mesoderm, the control of Polo activity transitions from the Aurora kinases to the uncharacterized kinase Back Seat Driver (Bsd), where Bsd and Polo cooperate to regulate muscle morphogenesis. Polo and its effectors therefore direct mitosis and cellular morphogenesis, but the transition from growth to morphogenesis is determined by the spatiotemporal expression of upstream activating kinases
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