5,454 research outputs found
Surveillance of antimalarial drug resistance in China in the 1980s–1990s
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
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
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
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 . 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 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
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
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
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
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
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
- …