5,454 research outputs found

    Surveillance of antimalarial drug resistance in China in the 1980s–1990s

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    Since the successful preparation of the microplates and the medium for field application, the resistance degree and its geographical distribution of chloroquine-resistant Plasmodium falciparum, the fluctuation of the resistance degree of P. falciparum to chloroquine, and the sensitivity of the parasite to commonly used antimalarial drugs were investigated between 1980 and 2003 by the in vitro microtest and the in vivo four-week test recommended by the World Health Organization (WHO). The results indicated that chloroquine-resistant falciparum malaria was present in all eight provinces/autonomous regions endemic for falciparum malaria in China, and the resistance was high and widely distributed in the Hainan and Yunnan provinces. When the use of chloroquine was stopped or administered in a decreased quanity, the drug resistance gradually decreased. In Hainan and Yunnan, P. falciparum was still highly resistant to chloroquine, amodiaquine and piperaquine, and sensitive to pyronaridine and artemisinin derivatives, but the sensitivity was gradually reduced. Based on these results, principles and therapeutic regimens for antimalarial drug use in China were formulated, the use of the antimalarials which had already developed resistance was stopped or reduced, and recommendations to use artemisinin derivatives or compound pyronaridine to promote a rational use of antimalarials and strengthen malaria control were made. The results showed that malaria incidence had declined, and endemic areas of falciparum malaria have been gradually reducing since the mid-1980s

    Noise in Genotype Selection Model

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    We study the steady state properties of a genotype selection model in presence of correlated Gaussian white noise. The effect of the noise on the genotype selection model is discussed. It is found that correlated noise can break the balance of gene selection and induce the phase transition which can makes us select one type gene haploid from a gene group.Comment: 8 pages, 4 figure

    Current Reversals in a inhomogeneous system with asymmetric unbiased fluctuations

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    We present a study of transport of a Brownian particle moving in periodic symmetric potential in the presence of asymmetric unbiased fluctuations. The particle is considered to move in a medium with periodic space dependent friction. By tuning the parameters of the system, the direction of current exhibit reversals, both as a function of temperature as well as the amplitude of rocking force. We found that the mutual interplay between the opposite driving factors is the necessary term for current reversals.Comment: 9 pages, 7 figure

    Nonsequential Double Ionization with Polarization-gated Pulses

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    We investigate laser-induced nonsequential double ionization by a polarization-gated laser pulse, constructed employing two counter-rotating circularly polarized few cycle pulses with a time delay TdT_{d}. We address the problem within a classical framework, and mimic the behavior of the quantum-mechanical electronic wave packet by means of an ensemble of classical electron trajectories. These trajectories are initially weighted with the quasi-static tunneling rate, and with suitably chosen distributions for the momentum components parallel and perpendicular to the laser-field polarization, in the temporal region for which it is nearly linearly polarized. We show that, if the time delay TdT_{d} is of the order of the pulse length, the electron-momentum distributions, as functions of the parallel momentum components, are highly asymmetric and dependent on the carrier-envelope (CE) phase. As this delay is decreased, this asymmetry gradually vanishes. We explain this behavior in terms of the available phase space, the quasi-static tunneling rate and the recollision rate for the first electron, for different sets of trajectories. Our results show that polarization-gating technique may provide an efficient way to study the NSDI dynamics in the single-cycle limit, without employing few-cycle pulses.Comment: 17 pages, 6 figure

    Fully integrated InGaAs/InP single-photon detector module with gigahertz sine wave gating

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    InGaAs/InP single-photon avalanche diodes (SPADs) working in the regime of GHz clock rates are crucial components for the high-speed quantum key distribution (QKD). We have developed for the first time a compact, stable and user-friendly tabletop InGaAs/InP single-photon detector system operating at a 1.25 GHz gate rate that fully integrates functions for controlling and optimizing SPAD performance. We characterize the key parameters of the detector system and test the long-term stability of the system for continuous operation of 75 hours. The detector system can substantially enhance QKD performance and our present work paves the way for practical high-speed QKD applications.Comment: 11 pages, 6 figures. Accepted for publication in Review of Scientific Instrument

    1-Benzoyl-3-chloro­azepan-2-one

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    In the crystal structure of the title compound, C13H14ClNO2, inter­molecular C—H⋯O inter­actions link the mol­ecules into a two-dimensional network

    3-Chloro­azepan-2-one

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    In the title compound, C6H10ClNO, an inter­mediate for the production of lysine, there are intra­molecular C—H⋯Cl hydrogen bonds

    Data-driven design of fault diagnosis for three-phase PWM rectifier using random forests technique with transient synthetic features

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    A three-phase pulse-width modulation (PWM) rectifier can usually maintain operation when open-circuit faults occur in insulated-gate bipolar transistors (IGBTs), which will lead the system to be unstable and unsafe. Aiming at this problem, based on random forests with transient synthetic features, a data-driven online fault diagnosis method is proposed to locate the open-circuit faults of IGBTs timely and effectively in this study. Firstly, by analysing the open-circuit fault features of IGBTs in the three-phase PWM rectifier, it is found that the occurrence of the fault features is related to the fault location and time, and the fault features do not always appear immediately with the occurrence of the fault. Secondly, different data-driven fault diagnosis methods are compared and evaluated, the performance of random forests algorithm is better than that of support vector machine or artificial neural networks. Meanwhile, the accuracy of fault diagnosis classifier trained by transient synthetic features is higher than that trained by original features. Also, the random forests fault diagnosis classifier trained by multiplicative features is the best with fault diagnosis accuracy can reach 98.32%. Finally, the online fault diagnosis experiments are carried out and the results demonstrate the effectiveness of the proposed method, which can accurately locate the open-circuit faults in IGBTs while ensuring system safety.Comment: IET Power Electronic

    4-Methyl-N-[(2-oxo-1,3-thia­zolidin-3-yl)carbon­yl]benzene­sulfonamide

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    The asymmetric unit of the title compound, C11H12N2O4S2, contains two independent mol­ecules with similar dihedral angles of 76.7 (1) and 77.3 (1)° between the mean planes of the five- and six-membered rings. In both mol­ecules, the amino groups are involved in intra­molecular N—H⋯O hydrogen bonds. In the crystal structure, weak inter­molecular C—H⋯O hydrogen bonds link mol­ecules into ribbons extended along the a axis
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