29,457 research outputs found

    Water productivity in Zhanghe Irrigation System: issues of scale

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    Irrigation systemsWater productivityReservoirsWater useWater stressWater conservationRicePaddy fieldsCrop yield

    Spin-Kick Correlation in Neutron Stars: Alignment Conditions and Implications

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    Recent observations of pulsar wind nebulae and radio polarization profiles revealed a tendency of the alignment between the spin and velocity directions in neutron stars. We study the condition for spin-kick alignment using a toy model, in which the kick consists of many off-centered, randomly-oriented thrusts. Both analytical considerations and numerical simulations indicate that spin-kick alignment cannot be easily achieved if the proto-neutron star does not possess some initial angular momentum, contrary to some previous claims. To obtain the observed spin-kick misalignment angle distribution, the initial spin period of the neutron star must be smaller than the kick timescale. Typically, an initial period of a hundred milliseconds or less is required.Comment: 17 pages, 8 figures. Accepted by Ap

    Optimal Conclusive Discrimination of Two Non-orthogonal Pure Product Multipartite States Locally

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    We consider one copy of a quantum system prepared in one of two non-orthogonal pure product states of multipartite distributed among separated parties. We show that there exist protocols which obtain optimal probability in the sense of conclusive discrimination by means of local operations and classical communications(LOCC) as good as by global operations. Also, we show a protocol which minimezes the average number of local operations. Our result implies that two product pure multipartite states might not have the non-local property though more than two can have.Comment: revtex, 3 pages, no figur

    Optimization of Protein-Protein Interaction Measurements for Drug Discovery Using AFM Force Spectroscopy

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    Increasingly targeted in drug discovery, protein-protein interactions challenge current high throughput screening technologies in the pharmaceutical industry. Developing an effective and efficient method for screening small molecules or compounds is critical to accelerate the discovery of ligands for enzymes, receptors and other pharmaceutical targets. Here, we report developments of methods to increase the signal-to-noise ratio (SNR) for screening protein-protein interactions using atomic force microscopy (AFM) force spectroscopy. We have demonstrated the effectiveness of these developments on detecting the binding process between focal adhesion kinases (FAK) with protein kinase B (Akt1), which is a target for potential cancer drugs. These developments include optimized probe and substrate functionalization processes and redesigned probe-substrate contact regimes. Furthermore, a statistical-based data processing method was developed to enhance the contrast of the experimental data. Collectively, these results demonstrate the potential of the AFM force spectroscopy in automating drug screening with high throughput

    Information-technology approach to quantum feedback control

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    Quantum control theory is profitably reexamined from the perspective of quantum information, two results on the role of quantum information technology in quantum feedback control are presented and two quantum feedback control schemes, teleportation-based distant quantum feedback control and quantum feedback control with quantum cloning, are proposed. In the first feedback scheme, the output from the quantum system to be controlled is fed back into the distant actuator via teleportation to alter the dynamics of system. The result theoretically shows that it can accomplish some tasks such as distant feedback quantum control that Markovian or Bayesian quantum feedback can't complete. In the second feedback strategy, the design of quantum feedback control algorithms is separated into a state recognition step, which gives "on-off" signal to the actuator through recognizing some copies from the cloning machine, and a feedback (control) step using another copies of cloning machine. A compromise between information acquisition and measurement disturbance is established, and this strategy can perform some quantum control tasks with coherent feedback.Comment: 10 pages,submitte

    Control design of uncertain quantum systems with fuzzy estimators

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    Infrared spectroscopy of the charge ordering transition in Na0.5_{0.5}CoO2_2

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    We report infrared spectra of a Na0.5_{0.5}CoO2_2 single crystal which exhibits a sharp metal-insulator transition near 50 K due to the formation of charge ordering. In comparison with x=0.7 and 0.85 compounds, we found that the spectral weight associated with the conducting carriers at high temperature increases systematically with decreasing Na contents. The charge ordering transition only affects the optical spectra below 1000 cm−1^{-1}. A hump near 800 cm−1^{-1} develops below 100 K, which is accompanied by the appearance of new lattice modes as well as the strong anti-resonance feature of phonon spectra. At lower temperature TcoT_{co}, an optical gap develops at the magnitude of 2Δ≈3.5kBTco\Delta\approx3.5k_BT_{co}, evidencing an insulating charge density wave ground state. Our experimental results and analysis unequivocally point towards the importance of charge ordering instability and strong electron-phonon interaction in Nax_xCoO2_2 system.Comment: 4 pages, 3 figure
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