569 research outputs found

    Trip-Based Public Transit Routing

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    We study the problem of computing all Pareto-optimal journeys in a public transit network regarding the two criteria of arrival time and number of transfers taken. We take a novel approach, focusing on trips and transfers between them, allowing fine-grained modeling. Our experiments on the metropolitan network of London show that the algorithm computes full 24-hour profiles in 70 ms after a preprocessing phase of 30 s, allowing fast queries in dynamic scenarios.Comment: Minor corrections, no substantial changes. To be presented at ESA 201

    Method and System for Creating Three-Dimensional Spatial Audio

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    A system and method for rendering a virtual sound source using a plurality of speakers in an arbitrary arrangement includes expanding a wave field of the virtual sound source and a composite wave field generated by the plurality of speakers into multi-pole expansions, and equating the multi-pole expansions to each other to form a continuous equation. A set of constraints is applied to the continuous equation that minimize an error in a sweet spot region resulting in a linear system of equations. The linear system of equations is solved using singular-value decomposition to arrive at a pseudo-inverse representing a multi-dimensional transfer function between the virtual sound source and the plurality of speakers. The multi-dimensional transfer function is then applied to a signal of the virtual sound source to render the virtual sound source in the sweet spot region using the plurality of speakers in the arbitrary arrangement

    A conceptual approach to the use of Cost Benefit and Multi Criteria Analysis in natural hazard management

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    International audienceDecision-making for protection measures against natural hazards entails major complexities for final decision makers. The issue in question does not only implicate a variety of criteria that need to be considered but also scarce financial resources make the allocation decision a difficult task. Furthermore, these decisions appear to be multidisciplinary in nature. Stakeholders from experts over politicians and the public are among the affected parties in making and dealing with the consequences of such decisions. In order to capture the complexity that arises when incorporating the varieties of interests as well as impacts protection measures have on the environment, the economy and society, transparent and multidisciplinary decision support techniques are needed. This paper looks at how Cost Benefit Analysis (CBA), a tool already applied to decisions concerning protective measures, and Multi Criteria Analysis (MCA), even though new to the field as such but already successfully practiced in other environmental areas, perform according to the abovementioned criteria. A conceptual overview of the methodologies will be given along with a discussion of the respective strengths and weaknesses. Looking at past applications, this overview gives an analysis about the potential of socio economics in its contribution to natural hazard research

    A relaxationless demonstration of the Quantum Zeno Paradox on an individual atom

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    The driven evolution of the spin of an individual atomic ion on the ground-state hyperfine resonance is impeded by the observation of the ion in one of the pertaining eigenstates. Detection of resonantly scattered light identifies the ion in its upper ``bright'' state. The lower ``dark'' ion state is free of relaxation and correlated with the detector by a null signal. Null events represent the straightforward demonstration of the quantum Zeno paradox. Also, high probability of survival was demonstrated when the ion, driven by a fractionated π\pi pulse, was probed {\em and monitored} during the intermissions of the drive, such that the ion's evolution is completely documented.Comment: 7 page

    The Properties of Red Blood Cells from Patients Heterozygous for HbS and HbC (HbSC Genotype)

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    Sickle cell disease (SCD) is one of the commonest severe inherited disorders, but specific treatments are lacking and the pathophysiology remains unclear. Affected individuals account for well over 250,000 births yearly, mostly in the Tropics, the USA, and the Caribbean, also in Northern Europe as well. Incidence in the UK amounts to around 12–15,000 individuals and is increasing, with approximately 300 SCD babies born each year as well as with arrival of new immigrants. About two thirds of SCD patients are homozygous HbSS individuals. Patients heterozygous for HbS and HbC (HbSC) constitute about a third of SCD cases, making this the second most common form of SCD, with approximately 80,000 births per year worldwide. Disease in these patients shows differences from that in homozygous HbSS individuals. Their red blood cells (RBCs), containing approximately equal amounts of HbS and HbC, are also likely to show differences in properties which may contribute to disease outcome. Nevertheless, little is known about the behaviour of RBCs from HbSC heterozygotes. This paper reviews what is known about SCD in HbSC individuals and will compare the properties of their RBCs with those from homozygous HbSS patients. Important areas of similarity and potential differences will be emphasised

    Evolution of magnetic and microstructural properties of thick sputtered NdFeB films with processing temperature

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    Ta (100 nm) / NdFeB (5 μ\mum) / Ta (100 nm) films have been deposited onto Si substrates using triode sputtering (deposition rate ~ 18 μ\mum/h). A 2-step procedure was used : deposition at temperatures up to 400 C followed by ex-situ annealing at higher temperatures. Post-deposition annealing temperatures above 650 C are needed to develop high values of coercivity. The duration of the annealing time is more critical in anisotropic samples deposited onto heated substrates than in isotropic samples deposited at lower temperatures. For a given set of annealing conditions (750 C/ 10'), high heating rates (≥ 2000 C / h) favour high coercivity in both isotropic and anisotropic films. The shape and size of Nd2Fe14B grains depend strongly on the heating rate

    High-fidelity state detection and tomography of a single ion Zeeman qubit

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    We demonstrate high-fidelity Zeeman qubit state detection in a single trapped 88 Sr+ ion. Qubit readout is performed by shelving one of the qubit states to a metastable level using a narrow linewidth diode laser at 674 nm followed by state-selective fluorescence detection. The average fidelity reached for the readout of the qubit state is 0.9989(1). We then measure the fidelity of state tomography, averaged over all possible single-qubit states, which is 0.9979(2). We also fully characterize the detection process using quantum process tomography. This readout fidelity is compatible with recent estimates of the detection error-threshold required for fault-tolerant computation, whereas high-fidelity state tomography opens the way for high-precision quantum process tomography
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