1,589 research outputs found

    Удалённое управление прибором измерения параметров электрохимической защиты нефтегазотрубопроводов с применением мобильных устройств

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    The following article presents the implementation of the control measuring device using a mobile device via Bluetooth. It explains the structure of this software. This article can be of interest for software engineers who develop mobile applications for control devices via Bluetooth

    Servicio SURAD, 2011 primer año de funcionamiento

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    1 copia .pdf del póster original, presentado en tamaño din A0 en las 4as Jornadas de Análisis de la Red de Bibliotecas del CSIC (Madrid. 26-27 abril, 2012). Más información de las Jornadas en: http://jornadas.urici.csic.es/IVjornadas/El servicio SURAD presenta los resultados del 2011, su primer año de actividad. SURAD es el servicio de localización y suministro de documentos científicos para la comunidad investigadora del CSIC, que atiende aquellas solicitudes que no pueden gestionar en primera instancia sus bibliotecas. SURAD se gestiona a través de la Unidad de Recursos de la Información Científica para la Investigación y integrado dentro del Plan 100% Digital del CSIC. Su objetivo es dar un servicio de acceso al documento a la comunidad científica del CSIC que carece de servicio de biblioteca presencial en su centro/instituto y actuar como servicio de último recurso de obtención de documentos para las bibliotecas de la Red, proporcionando los documentos que éstas no puedan obtener.Peer reviewe

    Bringing Order to Special Cases of Klee's Measure Problem

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    Klee's Measure Problem (KMP) asks for the volume of the union of n axis-aligned boxes in d-space. Omitting logarithmic factors, the best algorithm has runtime O*(n^{d/2}) [Overmars,Yap'91]. There are faster algorithms known for several special cases: Cube-KMP (where all boxes are cubes), Unitcube-KMP (where all boxes are cubes of equal side length), Hypervolume (where all boxes share a vertex), and k-Grounded (where the projection onto the first k dimensions is a Hypervolume instance). In this paper we bring some order to these special cases by providing reductions among them. In addition to the trivial inclusions, we establish Hypervolume as the easiest of these special cases, and show that the runtimes of Unitcube-KMP and Cube-KMP are polynomially related. More importantly, we show that any algorithm for one of the special cases with runtime T(n,d) implies an algorithm for the general case with runtime T(n,2d), yielding the first non-trivial relation between KMP and its special cases. This allows to transfer W[1]-hardness of KMP to all special cases, proving that no n^{o(d)} algorithm exists for any of the special cases under reasonable complexity theoretic assumptions. Furthermore, assuming that there is no improved algorithm for the general case of KMP (no algorithm with runtime O(n^{d/2 - eps})) this reduction shows that there is no algorithm with runtime O(n^{floor(d/2)/2 - eps}) for any of the special cases. Under the same assumption we show a tight lower bound for a recent algorithm for 2-Grounded [Yildiz,Suri'12].Comment: 17 page

    Comparison of cardiac volumetry using real-time MRI during free-breathing with standard cine MRI during breath-hold in children

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    Background Cardiac real-time magnetic resonance imaging (RT-MRI) provides high-quality images even during free- breathing. Difficulties in post-processing impede its use in clinical routine. Objective To demonstrate the feasibility of quantitative analysis of cardiac free-breathing RT-MRI and to compare image quality and volumetry during free-breathing RT-MRI in pediatric patients to standard breath-hold cine MRI. Materials and methods Pediatric patients (n= 22) received cardiac RT-MRI volumetry during free breathing (1.5 T; short axis; 30 frames per s) in addition to standard breath-hold cine imaging in end-expiration. Real-time images were binned retrospec- tively based on electrocardiography and respiratory bellows. Image quality and volumetry were compared using the European Cardiovascular Magnetic Resonance registry score, structure visibility rating, linear regression and Bland–Altman analyses. Results Additional time for binning of real-time images was 2 min. For both techniques, image quality was rated good to excellent. RT-MRI was significantly more robust against artifacts (P< 0.01). Linear regression revealed good correlations for the ventricular volumes. Bland–Altman plots showed a good limit of agreement (LoA) for end-diastolic volume (left ventricle [LV]: LoA -0.1 ± 2.7 ml/m2, right ventricle [RV]: LoA -1.9 ± 3.4 ml/m2), end-systolic volume (LV: LoA 0.4 ± 1.9 ml/m2, RV: LoA 0.6 ± 2.0 ml/m2), stroke volume (LV: LoA -0.5± 2.3 ml/m2, RV: LoA -2.6± 3.3 ml/m2) and ejection fraction (LV: LoA -0.5 ± 1.6%, RV: LoA -2.1 ± 2.8%). Conclusion Compared to standard cine MRI with breath hold, RT-MRI during free breathing with retrospective respiratory binning offers good image quality, reduced image artifacts enabling fast quantitative evaluations of ventricular volumes in clinical practice under physiological conditions

    Model of Low-pass Filtering of Local Field Potentials in Brain Tissue

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    Local field potentials (LFPs) are routinely measured experimentally in brain tissue, and exhibit strong low-pass frequency filtering properties, with high frequencies (such as action potentials) being visible only at very short distances (\approx10~μm\mu m) from the recording electrode. Understanding this filtering is crucial to relate LFP signals with neuronal activity, but not much is known about the exact mechanisms underlying this low-pass filtering. In this paper, we investigate a possible biophysical mechanism for the low-pass filtering properties of LFPs. We investigate the propagation of electric fields and its frequency dependence close to the current source, i.e. at length scales in the order of average interneuronal distance. We take into account the presence of a high density of cellular membranes around current sources, such as glial cells. By considering them as passive cells, we show that under the influence of the electric source field, they respond by polarisation, i.e., creation of an induced field. Because of the finite velocity of ionic charge movement, this polarization will not be instantaneous. Consequently, the induced electric field will be frequency-dependent, and much reduced for high frequencies. Our model establishes that with respect to frequency attenuation properties, this situation is analogous to an equivalent RC-circuit, or better a system of coupled RC-circuits. We present a number of numerical simulations of induced electric field for biologically realistic values of parameters, and show this frequency filtering effect as well as the attenuation of extracellular potentials with distance. We suggest that induced electric fields in passive cells surrounding neurons is the physical origin of frequency filtering properties of LFPs.Comment: 10 figs, revised tex file and revised fig

    Economic performance or electoral necessity? Evaluating the system of voluntary income to political parties

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    Whilst the public funding of political parties is the norm in western democracies, its comprehensive introduction has been resisted in Britain. Political and electoral arrangements in Britain require parties to function and campaign on a regular basis, whilst their income follows cycles largely related to general elections. This article shows that the best predictor of party income is the necessity of a well-funded general election campaign rather than party performance. As a result, income can only be controlled by parties to a limited degree, which jeopardises their ability to determine their own financial position and fulfil their functions as political parties
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