3,190 research outputs found

    Real-Time Water Vapor Maps from a GPS Surface Network: Construction, Validation, and Applications

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    In this paper the construction of real-time integrated water vapor (IWV) maps from a surface network of global positioning system (GPS) receivers is presented. The IWV maps are constructed using a twodimensional variational technique with a persistence background that is 15 min old. The background error covariances are determined using a novel two-step method, which is based on the Hollingsworth¿Lonnberg method. The quality of these maps is assessed by comparison with radiosonde observations and IWV maps from a numerical weather prediction (NWP) model. The analyzed GPS IWV maps have no bias against radiosonde observations and a small bias against NWP analysis and forecasts up to 9 h. The standard deviation with radiosonde observations is around 2 kg m-2, and the standard deviation with NWP increases with increasing forecast length (from 2 kg m-2 for the NWP analysis to 4 kg m-2 for a forecast length of 48 h). To illustrate the additional value of these real-time products for nowcasting, three thunderstorm cases are discussed. The constructed GPS IWV maps are combined with data from the weather radar, a lightning detection network, and surface wind observations. All cases show that the location of developing thunderstorms can be identified 2 h prior to initiation in the convergence of moist air

    Exact Markovian kinetic equation for a quantum Brownian oscillator

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    We derive an exact Markovian kinetic equation for an oscillator linearly coupled to a heat bath, describing quantum Brownian motion. Our work is based on the subdynamics formulation developed by Prigogine and collaborators. The space of distribution functions is decomposed into independent subspaces that remain invariant under Liouville dynamics. For integrable systems in Poincar\'e's sense the invariant subspaces follow the dynamics of uncoupled, renormalized particles. In contrast for non-integrable systems, the invariant subspaces follow a dynamics with broken-time symmetry, involving generalized functions. This result indicates that irreversibility and stochasticity are exact properties of dynamics in generalized function spaces. We comment on the relation between our Markovian kinetic equation and the Hu-Paz-Zhang equation.Comment: A few typos in the published version are correcte

    Orde in de Nederlandse filosofie

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    Legal and Actual Central Bank Independence: A Case Study of Bank Indonesia

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    Indicators of central bank independence (CBI) based on the interpretation central bank laws in place may not capture the actual independence of the central bank. This paper develops an indicator of actual independence of the Bank Indonesia (BI), the central bank of Indonesia, for the period 1953-2008 and compares it with a new legal CBI indicator based on Cukierman (1992). The indicator of actual independence captures institutional and economic factors that affect CBI. We find that before 1999, legal and actual independence of BI diverged substantially. After a new central bank law was enacted, the legal independence of BI increased and converged to actual independence.

    Device, system and method for tumor detection and/or monitoring

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    A device, system and method for tumor detection and/or monitoring is proposed. The proposed device comprises a first analysis unit for analyzing the spatial distribution of the photoplethysmographic, PPG, amplitude of PPG signals obtained from a region of interest, a second analysis unit for analyzing the spatial distribution of arterial blood oxygen saturation obtained from said PPG signals, and an evaluation unit for detecting and/or monitoring a tumor in said region of interest based on said two analyses.</p

    Distortion reduced signal detection

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    A device and a method for extracting information from detected characteristic signals receives a data stream derivable from electromagnetic radiation emitted or reflected by an object. The data stream comprises a continuous or discrete characteristic signal including physiological information and a disturbing signal portion. The physiological information is representative of at least one at least partially periodic vital signal. The disturbing signal portion is representative of at least one of an object motion portion and/or a non-indicative reflection portion. The characteristic signal is transferred by converting at least three absolute components of the characteristic signal related to respective additive channels to at least two difference components of the characteristic signal, wherein each of the at least two difference components can be derived through a respective arithmetic transformation considering at least two of the at least three absolute components, wherein the arithmetic transformation for each of the at least two difference components further comprises coefficients that substantially sum to zero. Consequently, the disturbing signal portion can be at least partially suppressed in the transferred signal.</p

    The effects of pulse stimulation on biota - Research in relation to ICES advice - Effects on dogfish

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    Onderzoek naar het welzijn van hondshaaien bij de vangst. Er is onderzocht of de methode van het gebruik van stroom wel diervriendelijk is. De conclusie is dat dit geen beletsel voor de diervriendelijkheid oplever

    Constructing curves using BI-ARCS

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